| 1 | \input texinfo @c -*-Texinfo-*- |
| 2 | @c Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, |
| 3 | @c 2001, 2002, 2003, 2004, 2005, 2006 |
| 4 | @c Free Software Foundation, Inc. |
| 5 | @c UPDATE!! On future updates-- |
| 6 | @c (1) check for new machine-dep cmdline options in |
| 7 | @c md_parse_option definitions in config/tc-*.c |
| 8 | @c (2) for platform-specific directives, examine md_pseudo_op |
| 9 | @c in config/tc-*.c |
| 10 | @c (3) for object-format specific directives, examine obj_pseudo_op |
| 11 | @c in config/obj-*.c |
| 12 | @c (4) portable directives in potable[] in read.c |
| 13 | @c %**start of header |
| 14 | @setfilename as.info |
| 15 | @c ---config--- |
| 16 | @macro gcctabopt{body} |
| 17 | @code{\body\} |
| 18 | @end macro |
| 19 | @c defaults, config file may override: |
| 20 | @set have-stabs |
| 21 | @c --- |
| 22 | @c man begin NAME |
| 23 | @c --- |
| 24 | @include asconfig.texi |
| 25 | @include gasver.texi |
| 26 | @c --- |
| 27 | @c man end |
| 28 | @c --- |
| 29 | @c common OR combinations of conditions |
| 30 | @ifset COFF |
| 31 | @set COFF-ELF |
| 32 | @end ifset |
| 33 | @ifset ELF |
| 34 | @set COFF-ELF |
| 35 | @end ifset |
| 36 | @ifset AOUT |
| 37 | @set aout-bout |
| 38 | @end ifset |
| 39 | @ifset ARM/Thumb |
| 40 | @set ARM |
| 41 | @end ifset |
| 42 | @ifset BOUT |
| 43 | @set aout-bout |
| 44 | @end ifset |
| 45 | @ifset H8/300 |
| 46 | @set H8 |
| 47 | @end ifset |
| 48 | @ifset SH |
| 49 | @set H8 |
| 50 | @end ifset |
| 51 | @ifset HPPA |
| 52 | @set abnormal-separator |
| 53 | @end ifset |
| 54 | @c ------------ |
| 55 | @ifset GENERIC |
| 56 | @settitle Using @value{AS} |
| 57 | @end ifset |
| 58 | @ifclear GENERIC |
| 59 | @settitle Using @value{AS} (@value{TARGET}) |
| 60 | @end ifclear |
| 61 | @setchapternewpage odd |
| 62 | @c %**end of header |
| 63 | |
| 64 | @c @smallbook |
| 65 | @c @set SMALL |
| 66 | @c WARE! Some of the machine-dependent sections contain tables of machine |
| 67 | @c instructions. Except in multi-column format, these tables look silly. |
| 68 | @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so |
| 69 | @c the multi-col format is faked within @example sections. |
| 70 | @c |
| 71 | @c Again unfortunately, the natural size that fits on a page, for these tables, |
| 72 | @c is different depending on whether or not smallbook is turned on. |
| 73 | @c This matters, because of order: text flow switches columns at each page |
| 74 | @c break. |
| 75 | @c |
| 76 | @c The format faked in this source works reasonably well for smallbook, |
| 77 | @c not well for the default large-page format. This manual expects that if you |
| 78 | @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the |
| 79 | @c tables in question. You can turn on one without the other at your |
| 80 | @c discretion, of course. |
| 81 | @ifinfo |
| 82 | @set SMALL |
| 83 | @c the insn tables look just as silly in info files regardless of smallbook, |
| 84 | @c might as well show 'em anyways. |
| 85 | @end ifinfo |
| 86 | |
| 87 | @ifinfo |
| 88 | @format |
| 89 | START-INFO-DIR-ENTRY |
| 90 | * As: (as). The GNU assembler. |
| 91 | * Gas: (as). The GNU assembler. |
| 92 | END-INFO-DIR-ENTRY |
| 93 | @end format |
| 94 | @end ifinfo |
| 95 | |
| 96 | @finalout |
| 97 | @syncodeindex ky cp |
| 98 | |
| 99 | @ifinfo |
| 100 | This file documents the GNU Assembler "@value{AS}". |
| 101 | |
| 102 | @c man begin COPYRIGHT |
| 103 | Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002, 2006 Free Software Foundation, Inc. |
| 104 | |
| 105 | Permission is granted to copy, distribute and/or modify this document |
| 106 | under the terms of the GNU Free Documentation License, Version 1.1 |
| 107 | or any later version published by the Free Software Foundation; |
| 108 | with no Invariant Sections, with no Front-Cover Texts, and with no |
| 109 | Back-Cover Texts. A copy of the license is included in the |
| 110 | section entitled ``GNU Free Documentation License''. |
| 111 | |
| 112 | @c man end |
| 113 | |
| 114 | @ignore |
| 115 | Permission is granted to process this file through Tex and print the |
| 116 | results, provided the printed document carries copying permission |
| 117 | notice identical to this one except for the removal of this paragraph |
| 118 | (this paragraph not being relevant to the printed manual). |
| 119 | |
| 120 | @end ignore |
| 121 | @end ifinfo |
| 122 | |
| 123 | @titlepage |
| 124 | @title Using @value{AS} |
| 125 | @subtitle The @sc{gnu} Assembler |
| 126 | @ifclear GENERIC |
| 127 | @subtitle for the @value{TARGET} family |
| 128 | @end ifclear |
| 129 | @sp 1 |
| 130 | @subtitle Version @value{VERSION} |
| 131 | @sp 1 |
| 132 | @sp 13 |
| 133 | The Free Software Foundation Inc. thanks The Nice Computer |
| 134 | Company of Australia for loaning Dean Elsner to write the |
| 135 | first (Vax) version of @command{as} for Project @sc{gnu}. |
| 136 | The proprietors, management and staff of TNCCA thank FSF for |
| 137 | distracting the boss while they got some work |
| 138 | done. |
| 139 | @sp 3 |
| 140 | @author Dean Elsner, Jay Fenlason & friends |
| 141 | @page |
| 142 | @tex |
| 143 | {\parskip=0pt |
| 144 | \hfill {\it Using {\tt @value{AS}}}\par |
| 145 | \hfill Edited by Cygnus Support\par |
| 146 | } |
| 147 | %"boxit" macro for figures: |
| 148 | %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3) |
| 149 | \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt |
| 150 | \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil |
| 151 | #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline |
| 152 | \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box |
| 153 | @end tex |
| 154 | |
| 155 | @vskip 0pt plus 1filll |
| 156 | Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002, 2006 Free Software Foundation, Inc. |
| 157 | |
| 158 | Permission is granted to copy, distribute and/or modify this document |
| 159 | under the terms of the GNU Free Documentation License, Version 1.1 |
| 160 | or any later version published by the Free Software Foundation; |
| 161 | with no Invariant Sections, with no Front-Cover Texts, and with no |
| 162 | Back-Cover Texts. A copy of the license is included in the |
| 163 | section entitled ``GNU Free Documentation License''. |
| 164 | |
| 165 | @end titlepage |
| 166 | |
| 167 | @ifnottex |
| 168 | @node Top |
| 169 | @top Using @value{AS} |
| 170 | |
| 171 | This file is a user guide to the @sc{gnu} assembler @command{@value{AS}} version |
| 172 | @value{VERSION}. |
| 173 | @ifclear GENERIC |
| 174 | This version of the file describes @command{@value{AS}} configured to generate |
| 175 | code for @value{TARGET} architectures. |
| 176 | @end ifclear |
| 177 | |
| 178 | This document is distributed under the terms of the GNU Free |
| 179 | Documentation License. A copy of the license is included in the |
| 180 | section entitled ``GNU Free Documentation License''. |
| 181 | |
| 182 | @menu |
| 183 | * Overview:: Overview |
| 184 | * Invoking:: Command-Line Options |
| 185 | * Syntax:: Syntax |
| 186 | * Sections:: Sections and Relocation |
| 187 | * Symbols:: Symbols |
| 188 | * Expressions:: Expressions |
| 189 | * Pseudo Ops:: Assembler Directives |
| 190 | * Machine Dependencies:: Machine Dependent Features |
| 191 | * Reporting Bugs:: Reporting Bugs |
| 192 | * Acknowledgements:: Who Did What |
| 193 | * GNU Free Documentation License:: GNU Free Documentation License |
| 194 | * AS Index:: AS Index |
| 195 | @end menu |
| 196 | @end ifnottex |
| 197 | |
| 198 | @node Overview |
| 199 | @chapter Overview |
| 200 | @iftex |
| 201 | This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}. |
| 202 | @ifclear GENERIC |
| 203 | This version of the manual describes @command{@value{AS}} configured to generate |
| 204 | code for @value{TARGET} architectures. |
| 205 | @end ifclear |
| 206 | @end iftex |
| 207 | |
| 208 | @cindex invocation summary |
| 209 | @cindex option summary |
| 210 | @cindex summary of options |
| 211 | Here is a brief summary of how to invoke @command{@value{AS}}. For details, |
| 212 | @pxref{Invoking,,Command-Line Options}. |
| 213 | |
| 214 | @c man title AS the portable GNU assembler. |
| 215 | |
| 216 | @ignore |
| 217 | @c man begin SEEALSO |
| 218 | gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}. |
| 219 | @c man end |
| 220 | @end ignore |
| 221 | |
| 222 | @c We don't use deffn and friends for the following because they seem |
| 223 | @c to be limited to one line for the header. |
| 224 | @smallexample |
| 225 | @c man begin SYNOPSIS |
| 226 | @value{AS} [@b{-a}[@b{cdhlns}][=@var{file}]] [@b{--alternate}] [@b{-D}] |
| 227 | [@b{--defsym} @var{sym}=@var{val}] [@b{-f}] [@b{-g}] [@b{--gstabs}] |
| 228 | [@b{--gstabs+}] [@b{--gdwarf-2}] [@b{--help}] [@b{-I} @var{dir}] [@b{-J}] |
| 229 | [@b{-K}] [@b{-L}] [@b{--listing-lhs-width}=@var{NUM}] |
| 230 | [@b{--listing-lhs-width2}=@var{NUM}] [@b{--listing-rhs-width}=@var{NUM}] |
| 231 | [@b{--listing-cont-lines}=@var{NUM}] [@b{--keep-locals}] [@b{-o} |
| 232 | @var{objfile}] [@b{-R}] [@b{--reduce-memory-overheads}] [@b{--statistics}] |
| 233 | [@b{-v}] [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}] |
| 234 | [@b{--fatal-warnings}] [@b{-w}] [@b{-x}] [@b{-Z}] [@b{@@@var{FILE}}] |
| 235 | [@b{--target-help}] [@var{target-options}] |
| 236 | [@b{--}|@var{files} @dots{}] |
| 237 | @c |
| 238 | @c Target dependent options are listed below. Keep the list sorted. |
| 239 | @c Add an empty line for separation. |
| 240 | @ifset ALPHA |
| 241 | |
| 242 | @emph{Target Alpha options:} |
| 243 | [@b{-m@var{cpu}}] |
| 244 | [@b{-mdebug} | @b{-no-mdebug}] |
| 245 | [@b{-relax}] [@b{-g}] [@b{-G@var{size}}] |
| 246 | [@b{-F}] [@b{-32addr}] |
| 247 | @end ifset |
| 248 | @ifset ARC |
| 249 | |
| 250 | @emph{Target ARC options:} |
| 251 | [@b{-marc[5|6|7|8]}] |
| 252 | [@b{-EB}|@b{-EL}] |
| 253 | @end ifset |
| 254 | @ifset ARM |
| 255 | |
| 256 | @emph{Target ARM options:} |
| 257 | @c Don't document the deprecated options |
| 258 | [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]] |
| 259 | [@b{-march}=@var{architecture}[+@var{extension}@dots{}]] |
| 260 | [@b{-mfpu}=@var{floating-point-format}] |
| 261 | [@b{-mfloat-abi}=@var{abi}] |
| 262 | [@b{-meabi}=@var{ver}] |
| 263 | [@b{-mthumb}] |
| 264 | [@b{-EB}|@b{-EL}] |
| 265 | [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}| |
| 266 | @b{-mapcs-reentrant}] |
| 267 | [@b{-mthumb-interwork}] [@b{-k}] |
| 268 | @end ifset |
| 269 | @ifset CRIS |
| 270 | |
| 271 | @emph{Target CRIS options:} |
| 272 | [@b{--underscore} | @b{--no-underscore}] |
| 273 | [@b{--pic}] [@b{-N}] |
| 274 | [@b{--emulation=criself} | @b{--emulation=crisaout}] |
| 275 | [@b{--march=v0_v10} | @b{--march=v10} | @b{--march=v32} | @b{--march=common_v10_v32}] |
| 276 | @c Deprecated -- deliberately not documented. |
| 277 | @c [@b{-h}] [@b{-H}] |
| 278 | @end ifset |
| 279 | @ifset D10V |
| 280 | |
| 281 | @emph{Target D10V options:} |
| 282 | [@b{-O}] |
| 283 | @end ifset |
| 284 | @ifset D30V |
| 285 | |
| 286 | @emph{Target D30V options:} |
| 287 | [@b{-O}|@b{-n}|@b{-N}] |
| 288 | @end ifset |
| 289 | @ifset H8 |
| 290 | @c Renesas family chips have no machine-dependent assembler options |
| 291 | @end ifset |
| 292 | @ifset HPPA |
| 293 | @c HPPA has no machine-dependent assembler options (yet). |
| 294 | @end ifset |
| 295 | @ifset I80386 |
| 296 | |
| 297 | @emph{Target i386 options:} |
| 298 | [@b{--32}|@b{--64}] [@b{-n}] |
| 299 | [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] |
| 300 | @end ifset |
| 301 | @ifset I960 |
| 302 | |
| 303 | @emph{Target i960 options:} |
| 304 | @c see md_parse_option in tc-i960.c |
| 305 | [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}| |
| 306 | @b{-AKC}|@b{-AMC}] |
| 307 | [@b{-b}] [@b{-no-relax}] |
| 308 | @end ifset |
| 309 | @ifset IA64 |
| 310 | |
| 311 | @emph{Target IA-64 options:} |
| 312 | [@b{-mconstant-gp}|@b{-mauto-pic}] |
| 313 | [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}] |
| 314 | [@b{-mle}|@b{mbe}] |
| 315 | [@b{-mtune=itanium1}|@b{-mtune=itanium2}] |
| 316 | [@b{-munwind-check=warning}|@b{-munwind-check=error}] |
| 317 | [@b{-mhint.b=ok}|@b{-mhint.b=warning}|@b{-mhint.b=error}] |
| 318 | [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}] |
| 319 | @end ifset |
| 320 | @ifset IP2K |
| 321 | |
| 322 | @emph{Target IP2K options:} |
| 323 | [@b{-mip2022}|@b{-mip2022ext}] |
| 324 | @end ifset |
| 325 | @ifset M32C |
| 326 | |
| 327 | @emph{Target M32C options:} |
| 328 | [@b{-m32c}|@b{-m16c}] |
| 329 | @end ifset |
| 330 | @ifset M32R |
| 331 | |
| 332 | @emph{Target M32R options:} |
| 333 | [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}| |
| 334 | @b{--W[n]p}] |
| 335 | @end ifset |
| 336 | @ifset M680X0 |
| 337 | |
| 338 | @emph{Target M680X0 options:} |
| 339 | [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}] |
| 340 | @end ifset |
| 341 | @ifset M68HC11 |
| 342 | |
| 343 | @emph{Target M68HC11 options:} |
| 344 | [@b{-m68hc11}|@b{-m68hc12}|@b{-m68hcs12}] |
| 345 | [@b{-mshort}|@b{-mlong}] |
| 346 | [@b{-mshort-double}|@b{-mlong-double}] |
| 347 | [@b{--force-long-branchs}] [@b{--short-branchs}] |
| 348 | [@b{--strict-direct-mode}] [@b{--print-insn-syntax}] |
| 349 | [@b{--print-opcodes}] [@b{--generate-example}] |
| 350 | @end ifset |
| 351 | @ifset MCORE |
| 352 | |
| 353 | @emph{Target MCORE options:} |
| 354 | [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}] |
| 355 | [@b{-mcpu=[210|340]}] |
| 356 | @end ifset |
| 357 | @ifset MIPS |
| 358 | |
| 359 | @emph{Target MIPS options:} |
| 360 | [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-O}[@var{optimization level}]] |
| 361 | [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}] |
| 362 | [@b{-non_shared}] [@b{-xgot}] |
| 363 | [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}] |
| 364 | [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}] |
| 365 | [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips32r2}] |
| 366 | [@b{-mips64}] [@b{-mips64r2}] |
| 367 | [@b{-construct-floats}] [@b{-no-construct-floats}] |
| 368 | [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}] |
| 369 | [@b{-mfix7000}] [@b{-mno-fix7000}] |
| 370 | [@b{-mips16}] [@b{-no-mips16}] |
| 371 | [@b{-msmartmips}] [@b{-mno-smartmips}] |
| 372 | [@b{-mips3d}] [@b{-no-mips3d}] |
| 373 | [@b{-mdmx}] [@b{-no-mdmx}] |
| 374 | [@b{-mdsp}] [@b{-mno-dsp}] |
| 375 | [@b{-mmt}] [@b{-mno-mt}] |
| 376 | [@b{-mdebug}] [@b{-no-mdebug}] |
| 377 | [@b{-mpdr}] [@b{-mno-pdr}] |
| 378 | @end ifset |
| 379 | @ifset MMIX |
| 380 | |
| 381 | @emph{Target MMIX options:} |
| 382 | [@b{--fixed-special-register-names}] [@b{--globalize-symbols}] |
| 383 | [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}] |
| 384 | [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}] |
| 385 | [@b{--linker-allocated-gregs}] |
| 386 | @end ifset |
| 387 | @ifset PDP11 |
| 388 | |
| 389 | @emph{Target PDP11 options:} |
| 390 | [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}] |
| 391 | [@b{-m}@var{extension}|@b{-mno-}@var{extension}] |
| 392 | [@b{-m}@var{cpu}] [@b{-m}@var{machine}] |
| 393 | @end ifset |
| 394 | @ifset PJ |
| 395 | |
| 396 | @emph{Target picoJava options:} |
| 397 | [@b{-mb}|@b{-me}] |
| 398 | @end ifset |
| 399 | @ifset PPC |
| 400 | |
| 401 | @emph{Target PowerPC options:} |
| 402 | [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}| |
| 403 | @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}| |
| 404 | @b{-mbooke32}|@b{-mbooke64}] |
| 405 | [@b{-mcom}|@b{-many}|@b{-maltivec}] [@b{-memb}] |
| 406 | [@b{-mregnames}|@b{-mno-regnames}] |
| 407 | [@b{-mrelocatable}|@b{-mrelocatable-lib}] |
| 408 | [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}] |
| 409 | [@b{-msolaris}|@b{-mno-solaris}] |
| 410 | @end ifset |
| 411 | @ifset SPARC |
| 412 | |
| 413 | @emph{Target SPARC options:} |
| 414 | @c The order here is important. See c-sparc.texi. |
| 415 | [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite} |
| 416 | @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}] |
| 417 | [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}] |
| 418 | [@b{-32}|@b{-64}] |
| 419 | @end ifset |
| 420 | @ifset TIC54X |
| 421 | |
| 422 | @emph{Target TIC54X options:} |
| 423 | [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}] |
| 424 | [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}] |
| 425 | @end ifset |
| 426 | |
| 427 | @ifset Z80 |
| 428 | |
| 429 | @emph{Target Z80 options:} |
| 430 | [@b{-z80}] [@b{-r800}] |
| 431 | [@b{ -ignore-undocumented-instructions}] [@b{-Wnud}] |
| 432 | [@b{ -ignore-unportable-instructions}] [@b{-Wnup}] |
| 433 | [@b{ -warn-undocumented-instructions}] [@b{-Wud}] |
| 434 | [@b{ -warn-unportable-instructions}] [@b{-Wup}] |
| 435 | [@b{ -forbid-undocumented-instructions}] [@b{-Fud}] |
| 436 | [@b{ -forbid-unportable-instructions}] [@b{-Fup}] |
| 437 | @end ifset |
| 438 | |
| 439 | @ifset Z8000 |
| 440 | @c Z8000 has no machine-dependent assembler options |
| 441 | @end ifset |
| 442 | @ifset XTENSA |
| 443 | |
| 444 | @emph{Target Xtensa options:} |
| 445 | [@b{--[no-]text-section-literals}] [@b{--[no-]absolute-literals}] |
| 446 | [@b{--[no-]target-align}] [@b{--[no-]longcalls}] |
| 447 | [@b{--[no-]transform}] |
| 448 | [@b{--rename-section} @var{oldname}=@var{newname}] |
| 449 | @end ifset |
| 450 | @c man end |
| 451 | @end smallexample |
| 452 | |
| 453 | @c man begin OPTIONS |
| 454 | |
| 455 | @table @gcctabopt |
| 456 | @include at-file.texi |
| 457 | |
| 458 | @item -a[cdhlmns] |
| 459 | Turn on listings, in any of a variety of ways: |
| 460 | |
| 461 | @table @gcctabopt |
| 462 | @item -ac |
| 463 | omit false conditionals |
| 464 | |
| 465 | @item -ad |
| 466 | omit debugging directives |
| 467 | |
| 468 | @item -ah |
| 469 | include high-level source |
| 470 | |
| 471 | @item -al |
| 472 | include assembly |
| 473 | |
| 474 | @item -am |
| 475 | include macro expansions |
| 476 | |
| 477 | @item -an |
| 478 | omit forms processing |
| 479 | |
| 480 | @item -as |
| 481 | include symbols |
| 482 | |
| 483 | @item =file |
| 484 | set the name of the listing file |
| 485 | @end table |
| 486 | |
| 487 | You may combine these options; for example, use @samp{-aln} for assembly |
| 488 | listing without forms processing. The @samp{=file} option, if used, must be |
| 489 | the last one. By itself, @samp{-a} defaults to @samp{-ahls}. |
| 490 | |
| 491 | @item --alternate |
| 492 | Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}. |
| 493 | |
| 494 | @item -D |
| 495 | Ignored. This option is accepted for script compatibility with calls to |
| 496 | other assemblers. |
| 497 | |
| 498 | @item --defsym @var{sym}=@var{value} |
| 499 | Define the symbol @var{sym} to be @var{value} before assembling the input file. |
| 500 | @var{value} must be an integer constant. As in C, a leading @samp{0x} |
| 501 | indicates a hexadecimal value, and a leading @samp{0} indicates an octal value. |
| 502 | |
| 503 | @item -f |
| 504 | ``fast''---skip whitespace and comment preprocessing (assume source is |
| 505 | compiler output). |
| 506 | |
| 507 | @item -g |
| 508 | @itemx --gen-debug |
| 509 | Generate debugging information for each assembler source line using whichever |
| 510 | debug format is preferred by the target. This currently means either STABS, |
| 511 | ECOFF or DWARF2. |
| 512 | |
| 513 | @item --gstabs |
| 514 | Generate stabs debugging information for each assembler line. This |
| 515 | may help debugging assembler code, if the debugger can handle it. |
| 516 | |
| 517 | @item --gstabs+ |
| 518 | Generate stabs debugging information for each assembler line, with GNU |
| 519 | extensions that probably only gdb can handle, and that could make other |
| 520 | debuggers crash or refuse to read your program. This |
| 521 | may help debugging assembler code. Currently the only GNU extension is |
| 522 | the location of the current working directory at assembling time. |
| 523 | |
| 524 | @item --gdwarf-2 |
| 525 | Generate DWARF2 debugging information for each assembler line. This |
| 526 | may help debugging assembler code, if the debugger can handle it. Note---this |
| 527 | option is only supported by some targets, not all of them. |
| 528 | |
| 529 | @item --help |
| 530 | Print a summary of the command line options and exit. |
| 531 | |
| 532 | @item --target-help |
| 533 | Print a summary of all target specific options and exit. |
| 534 | |
| 535 | @item -I @var{dir} |
| 536 | Add directory @var{dir} to the search list for @code{.include} directives. |
| 537 | |
| 538 | @item -J |
| 539 | Don't warn about signed overflow. |
| 540 | |
| 541 | @item -K |
| 542 | @ifclear DIFF-TBL-KLUGE |
| 543 | This option is accepted but has no effect on the @value{TARGET} family. |
| 544 | @end ifclear |
| 545 | @ifset DIFF-TBL-KLUGE |
| 546 | Issue warnings when difference tables altered for long displacements. |
| 547 | @end ifset |
| 548 | |
| 549 | @item -L |
| 550 | @itemx --keep-locals |
| 551 | Keep (in the symbol table) local symbols. On traditional a.out systems |
| 552 | these start with @samp{L}, but different systems have different local |
| 553 | label prefixes. |
| 554 | |
| 555 | @item --listing-lhs-width=@var{number} |
| 556 | Set the maximum width, in words, of the output data column for an assembler |
| 557 | listing to @var{number}. |
| 558 | |
| 559 | @item --listing-lhs-width2=@var{number} |
| 560 | Set the maximum width, in words, of the output data column for continuation |
| 561 | lines in an assembler listing to @var{number}. |
| 562 | |
| 563 | @item --listing-rhs-width=@var{number} |
| 564 | Set the maximum width of an input source line, as displayed in a listing, to |
| 565 | @var{number} bytes. |
| 566 | |
| 567 | @item --listing-cont-lines=@var{number} |
| 568 | Set the maximum number of lines printed in a listing for a single line of input |
| 569 | to @var{number} + 1. |
| 570 | |
| 571 | @item -o @var{objfile} |
| 572 | Name the object-file output from @command{@value{AS}} @var{objfile}. |
| 573 | |
| 574 | @item -R |
| 575 | Fold the data section into the text section. |
| 576 | |
| 577 | @kindex --hash-size=@var{number} |
| 578 | Set the default size of GAS's hash tables to a prime number close to |
| 579 | @var{number}. Increasing this value can reduce the length of time it takes the |
| 580 | assembler to perform its tasks, at the expense of increasing the assembler's |
| 581 | memory requirements. Similarly reducing this value can reduce the memory |
| 582 | requirements at the expense of speed. |
| 583 | |
| 584 | @item --reduce-memory-overheads |
| 585 | This option reduces GAS's memory requirements, at the expense of making the |
| 586 | assembly processes slower. Currently this switch is a synonym for |
| 587 | @samp{--hash-size=4051}, but in the future it may have other effects as well. |
| 588 | |
| 589 | @item --statistics |
| 590 | Print the maximum space (in bytes) and total time (in seconds) used by |
| 591 | assembly. |
| 592 | |
| 593 | @item --strip-local-absolute |
| 594 | Remove local absolute symbols from the outgoing symbol table. |
| 595 | |
| 596 | @item -v |
| 597 | @itemx -version |
| 598 | Print the @command{as} version. |
| 599 | |
| 600 | @item --version |
| 601 | Print the @command{as} version and exit. |
| 602 | |
| 603 | @item -W |
| 604 | @itemx --no-warn |
| 605 | Suppress warning messages. |
| 606 | |
| 607 | @item --fatal-warnings |
| 608 | Treat warnings as errors. |
| 609 | |
| 610 | @item --warn |
| 611 | Don't suppress warning messages or treat them as errors. |
| 612 | |
| 613 | @item -w |
| 614 | Ignored. |
| 615 | |
| 616 | @item -x |
| 617 | Ignored. |
| 618 | |
| 619 | @item -Z |
| 620 | Generate an object file even after errors. |
| 621 | |
| 622 | @item -- | @var{files} @dots{} |
| 623 | Standard input, or source files to assemble. |
| 624 | |
| 625 | @end table |
| 626 | |
| 627 | @ifset ARC |
| 628 | The following options are available when @value{AS} is configured for |
| 629 | an ARC processor. |
| 630 | |
| 631 | @table @gcctabopt |
| 632 | @item -marc[5|6|7|8] |
| 633 | This option selects the core processor variant. |
| 634 | @item -EB | -EL |
| 635 | Select either big-endian (-EB) or little-endian (-EL) output. |
| 636 | @end table |
| 637 | @end ifset |
| 638 | |
| 639 | @ifset ARM |
| 640 | The following options are available when @value{AS} is configured for the ARM |
| 641 | processor family. |
| 642 | |
| 643 | @table @gcctabopt |
| 644 | @item -mcpu=@var{processor}[+@var{extension}@dots{}] |
| 645 | Specify which ARM processor variant is the target. |
| 646 | @item -march=@var{architecture}[+@var{extension}@dots{}] |
| 647 | Specify which ARM architecture variant is used by the target. |
| 648 | @item -mfpu=@var{floating-point-format} |
| 649 | Select which Floating Point architecture is the target. |
| 650 | @item -mfloat-abi=@var{abi} |
| 651 | Select which floating point ABI is in use. |
| 652 | @item -mthumb |
| 653 | Enable Thumb only instruction decoding. |
| 654 | @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant |
| 655 | Select which procedure calling convention is in use. |
| 656 | @item -EB | -EL |
| 657 | Select either big-endian (-EB) or little-endian (-EL) output. |
| 658 | @item -mthumb-interwork |
| 659 | Specify that the code has been generated with interworking between Thumb and |
| 660 | ARM code in mind. |
| 661 | @item -k |
| 662 | Specify that PIC code has been generated. |
| 663 | @end table |
| 664 | @end ifset |
| 665 | |
| 666 | @ifset CRIS |
| 667 | See the info pages for documentation of the CRIS-specific options. |
| 668 | @end ifset |
| 669 | |
| 670 | @ifset D10V |
| 671 | The following options are available when @value{AS} is configured for |
| 672 | a D10V processor. |
| 673 | @table @gcctabopt |
| 674 | @cindex D10V optimization |
| 675 | @cindex optimization, D10V |
| 676 | @item -O |
| 677 | Optimize output by parallelizing instructions. |
| 678 | @end table |
| 679 | @end ifset |
| 680 | |
| 681 | @ifset D30V |
| 682 | The following options are available when @value{AS} is configured for a D30V |
| 683 | processor. |
| 684 | @table @gcctabopt |
| 685 | @cindex D30V optimization |
| 686 | @cindex optimization, D30V |
| 687 | @item -O |
| 688 | Optimize output by parallelizing instructions. |
| 689 | |
| 690 | @cindex D30V nops |
| 691 | @item -n |
| 692 | Warn when nops are generated. |
| 693 | |
| 694 | @cindex D30V nops after 32-bit multiply |
| 695 | @item -N |
| 696 | Warn when a nop after a 32-bit multiply instruction is generated. |
| 697 | @end table |
| 698 | @end ifset |
| 699 | |
| 700 | @ifset I960 |
| 701 | The following options are available when @value{AS} is configured for the |
| 702 | Intel 80960 processor. |
| 703 | |
| 704 | @table @gcctabopt |
| 705 | @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC |
| 706 | Specify which variant of the 960 architecture is the target. |
| 707 | |
| 708 | @item -b |
| 709 | Add code to collect statistics about branches taken. |
| 710 | |
| 711 | @item -no-relax |
| 712 | Do not alter compare-and-branch instructions for long displacements; |
| 713 | error if necessary. |
| 714 | |
| 715 | @end table |
| 716 | @end ifset |
| 717 | |
| 718 | @ifset IP2K |
| 719 | The following options are available when @value{AS} is configured for the |
| 720 | Ubicom IP2K series. |
| 721 | |
| 722 | @table @gcctabopt |
| 723 | |
| 724 | @item -mip2022ext |
| 725 | Specifies that the extended IP2022 instructions are allowed. |
| 726 | |
| 727 | @item -mip2022 |
| 728 | Restores the default behaviour, which restricts the permitted instructions to |
| 729 | just the basic IP2022 ones. |
| 730 | |
| 731 | @end table |
| 732 | @end ifset |
| 733 | |
| 734 | @ifset M32C |
| 735 | The following options are available when @value{AS} is configured for the |
| 736 | Renesas M32C and M16C processors. |
| 737 | |
| 738 | @table @gcctabopt |
| 739 | |
| 740 | @item -m32c |
| 741 | Assemble M32C instructions. |
| 742 | |
| 743 | @item -m16c |
| 744 | Assemble M16C instructions (the default). |
| 745 | |
| 746 | @end table |
| 747 | @end ifset |
| 748 | |
| 749 | @ifset M32R |
| 750 | The following options are available when @value{AS} is configured for the |
| 751 | Renesas M32R (formerly Mitsubishi M32R) series. |
| 752 | |
| 753 | @table @gcctabopt |
| 754 | |
| 755 | @item --m32rx |
| 756 | Specify which processor in the M32R family is the target. The default |
| 757 | is normally the M32R, but this option changes it to the M32RX. |
| 758 | |
| 759 | @item --warn-explicit-parallel-conflicts or --Wp |
| 760 | Produce warning messages when questionable parallel constructs are |
| 761 | encountered. |
| 762 | |
| 763 | @item --no-warn-explicit-parallel-conflicts or --Wnp |
| 764 | Do not produce warning messages when questionable parallel constructs are |
| 765 | encountered. |
| 766 | |
| 767 | @end table |
| 768 | @end ifset |
| 769 | |
| 770 | @ifset M680X0 |
| 771 | The following options are available when @value{AS} is configured for the |
| 772 | Motorola 68000 series. |
| 773 | |
| 774 | @table @gcctabopt |
| 775 | |
| 776 | @item -l |
| 777 | Shorten references to undefined symbols, to one word instead of two. |
| 778 | |
| 779 | @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030 |
| 780 | @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332 |
| 781 | @itemx | -m68333 | -m68340 | -mcpu32 | -m5200 |
| 782 | Specify what processor in the 68000 family is the target. The default |
| 783 | is normally the 68020, but this can be changed at configuration time. |
| 784 | |
| 785 | @item -m68881 | -m68882 | -mno-68881 | -mno-68882 |
| 786 | The target machine does (or does not) have a floating-point coprocessor. |
| 787 | The default is to assume a coprocessor for 68020, 68030, and cpu32. Although |
| 788 | the basic 68000 is not compatible with the 68881, a combination of the |
| 789 | two can be specified, since it's possible to do emulation of the |
| 790 | coprocessor instructions with the main processor. |
| 791 | |
| 792 | @item -m68851 | -mno-68851 |
| 793 | The target machine does (or does not) have a memory-management |
| 794 | unit coprocessor. The default is to assume an MMU for 68020 and up. |
| 795 | |
| 796 | @end table |
| 797 | @end ifset |
| 798 | |
| 799 | @ifset PDP11 |
| 800 | |
| 801 | For details about the PDP-11 machine dependent features options, |
| 802 | see @ref{PDP-11-Options}. |
| 803 | |
| 804 | @table @gcctabopt |
| 805 | @item -mpic | -mno-pic |
| 806 | Generate position-independent (or position-dependent) code. The |
| 807 | default is @option{-mpic}. |
| 808 | |
| 809 | @item -mall |
| 810 | @itemx -mall-extensions |
| 811 | Enable all instruction set extensions. This is the default. |
| 812 | |
| 813 | @item -mno-extensions |
| 814 | Disable all instruction set extensions. |
| 815 | |
| 816 | @item -m@var{extension} | -mno-@var{extension} |
| 817 | Enable (or disable) a particular instruction set extension. |
| 818 | |
| 819 | @item -m@var{cpu} |
| 820 | Enable the instruction set extensions supported by a particular CPU, and |
| 821 | disable all other extensions. |
| 822 | |
| 823 | @item -m@var{machine} |
| 824 | Enable the instruction set extensions supported by a particular machine |
| 825 | model, and disable all other extensions. |
| 826 | @end table |
| 827 | |
| 828 | @end ifset |
| 829 | |
| 830 | @ifset PJ |
| 831 | The following options are available when @value{AS} is configured for |
| 832 | a picoJava processor. |
| 833 | |
| 834 | @table @gcctabopt |
| 835 | |
| 836 | @cindex PJ endianness |
| 837 | @cindex endianness, PJ |
| 838 | @cindex big endian output, PJ |
| 839 | @item -mb |
| 840 | Generate ``big endian'' format output. |
| 841 | |
| 842 | @cindex little endian output, PJ |
| 843 | @item -ml |
| 844 | Generate ``little endian'' format output. |
| 845 | |
| 846 | @end table |
| 847 | @end ifset |
| 848 | |
| 849 | @ifset M68HC11 |
| 850 | The following options are available when @value{AS} is configured for the |
| 851 | Motorola 68HC11 or 68HC12 series. |
| 852 | |
| 853 | @table @gcctabopt |
| 854 | |
| 855 | @item -m68hc11 | -m68hc12 | -m68hcs12 |
| 856 | Specify what processor is the target. The default is |
| 857 | defined by the configuration option when building the assembler. |
| 858 | |
| 859 | @item -mshort |
| 860 | Specify to use the 16-bit integer ABI. |
| 861 | |
| 862 | @item -mlong |
| 863 | Specify to use the 32-bit integer ABI. |
| 864 | |
| 865 | @item -mshort-double |
| 866 | Specify to use the 32-bit double ABI. |
| 867 | |
| 868 | @item -mlong-double |
| 869 | Specify to use the 64-bit double ABI. |
| 870 | |
| 871 | @item --force-long-branchs |
| 872 | Relative branches are turned into absolute ones. This concerns |
| 873 | conditional branches, unconditional branches and branches to a |
| 874 | sub routine. |
| 875 | |
| 876 | @item -S | --short-branchs |
| 877 | Do not turn relative branchs into absolute ones |
| 878 | when the offset is out of range. |
| 879 | |
| 880 | @item --strict-direct-mode |
| 881 | Do not turn the direct addressing mode into extended addressing mode |
| 882 | when the instruction does not support direct addressing mode. |
| 883 | |
| 884 | @item --print-insn-syntax |
| 885 | Print the syntax of instruction in case of error. |
| 886 | |
| 887 | @item --print-opcodes |
| 888 | print the list of instructions with syntax and then exit. |
| 889 | |
| 890 | @item --generate-example |
| 891 | print an example of instruction for each possible instruction and then exit. |
| 892 | This option is only useful for testing @command{@value{AS}}. |
| 893 | |
| 894 | @end table |
| 895 | @end ifset |
| 896 | |
| 897 | @ifset SPARC |
| 898 | The following options are available when @command{@value{AS}} is configured |
| 899 | for the SPARC architecture: |
| 900 | |
| 901 | @table @gcctabopt |
| 902 | @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite |
| 903 | @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a |
| 904 | Explicitly select a variant of the SPARC architecture. |
| 905 | |
| 906 | @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment. |
| 907 | @samp{-Av9} and @samp{-Av9a} select a 64 bit environment. |
| 908 | |
| 909 | @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with |
| 910 | UltraSPARC extensions. |
| 911 | |
| 912 | @item -xarch=v8plus | -xarch=v8plusa |
| 913 | For compatibility with the Solaris v9 assembler. These options are |
| 914 | equivalent to -Av8plus and -Av8plusa, respectively. |
| 915 | |
| 916 | @item -bump |
| 917 | Warn when the assembler switches to another architecture. |
| 918 | @end table |
| 919 | @end ifset |
| 920 | |
| 921 | @ifset TIC54X |
| 922 | The following options are available when @value{AS} is configured for the 'c54x |
| 923 | architecture. |
| 924 | |
| 925 | @table @gcctabopt |
| 926 | @item -mfar-mode |
| 927 | Enable extended addressing mode. All addresses and relocations will assume |
| 928 | extended addressing (usually 23 bits). |
| 929 | @item -mcpu=@var{CPU_VERSION} |
| 930 | Sets the CPU version being compiled for. |
| 931 | @item -merrors-to-file @var{FILENAME} |
| 932 | Redirect error output to a file, for broken systems which don't support such |
| 933 | behaviour in the shell. |
| 934 | @end table |
| 935 | @end ifset |
| 936 | |
| 937 | @ifset MIPS |
| 938 | The following options are available when @value{AS} is configured for |
| 939 | a @sc{mips} processor. |
| 940 | |
| 941 | @table @gcctabopt |
| 942 | @item -G @var{num} |
| 943 | This option sets the largest size of an object that can be referenced |
| 944 | implicitly with the @code{gp} register. It is only accepted for targets that |
| 945 | use ECOFF format, such as a DECstation running Ultrix. The default value is 8. |
| 946 | |
| 947 | @cindex MIPS endianness |
| 948 | @cindex endianness, MIPS |
| 949 | @cindex big endian output, MIPS |
| 950 | @item -EB |
| 951 | Generate ``big endian'' format output. |
| 952 | |
| 953 | @cindex little endian output, MIPS |
| 954 | @item -EL |
| 955 | Generate ``little endian'' format output. |
| 956 | |
| 957 | @cindex MIPS ISA |
| 958 | @item -mips1 |
| 959 | @itemx -mips2 |
| 960 | @itemx -mips3 |
| 961 | @itemx -mips4 |
| 962 | @itemx -mips5 |
| 963 | @itemx -mips32 |
| 964 | @itemx -mips32r2 |
| 965 | @itemx -mips64 |
| 966 | @itemx -mips64r2 |
| 967 | Generate code for a particular @sc{mips} Instruction Set Architecture level. |
| 968 | @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an |
| 969 | alias for @samp{-march=r6000}, @samp{-mips3} is an alias for |
| 970 | @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}. |
| 971 | @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips64}, and |
| 972 | @samp{-mips64r2} |
| 973 | correspond to generic |
| 974 | @samp{MIPS V}, @samp{MIPS32}, @samp{MIPS32 Release 2}, @samp{MIPS64}, |
| 975 | and @samp{MIPS64 Release 2} |
| 976 | ISA processors, respectively. |
| 977 | |
| 978 | @item -march=@var{CPU} |
| 979 | Generate code for a particular @sc{mips} cpu. |
| 980 | |
| 981 | @item -mtune=@var{cpu} |
| 982 | Schedule and tune for a particular @sc{mips} cpu. |
| 983 | |
| 984 | @item -mfix7000 |
| 985 | @itemx -mno-fix7000 |
| 986 | Cause nops to be inserted if the read of the destination register |
| 987 | of an mfhi or mflo instruction occurs in the following two instructions. |
| 988 | |
| 989 | @item -mdebug |
| 990 | @itemx -no-mdebug |
| 991 | Cause stabs-style debugging output to go into an ECOFF-style .mdebug |
| 992 | section instead of the standard ELF .stabs sections. |
| 993 | |
| 994 | @item -mpdr |
| 995 | @itemx -mno-pdr |
| 996 | Control generation of @code{.pdr} sections. |
| 997 | |
| 998 | @item -mgp32 |
| 999 | @itemx -mfp32 |
| 1000 | The register sizes are normally inferred from the ISA and ABI, but these |
| 1001 | flags force a certain group of registers to be treated as 32 bits wide at |
| 1002 | all times. @samp{-mgp32} controls the size of general-purpose registers |
| 1003 | and @samp{-mfp32} controls the size of floating-point registers. |
| 1004 | |
| 1005 | @item -mips16 |
| 1006 | @itemx -no-mips16 |
| 1007 | Generate code for the MIPS 16 processor. This is equivalent to putting |
| 1008 | @code{.set mips16} at the start of the assembly file. @samp{-no-mips16} |
| 1009 | turns off this option. |
| 1010 | |
| 1011 | @item -msmartmips |
| 1012 | @itemx -mno-smartmips |
| 1013 | Enables the SmartMIPS extension to the MIPS32 instruction set. This is |
| 1014 | equivalent to putting @code{.set smartmips} at the start of the assembly file. |
| 1015 | @samp{-mno-smartmips} turns off this option. |
| 1016 | |
| 1017 | @item -mips3d |
| 1018 | @itemx -no-mips3d |
| 1019 | Generate code for the MIPS-3D Application Specific Extension. |
| 1020 | This tells the assembler to accept MIPS-3D instructions. |
| 1021 | @samp{-no-mips3d} turns off this option. |
| 1022 | |
| 1023 | @item -mdmx |
| 1024 | @itemx -no-mdmx |
| 1025 | Generate code for the MDMX Application Specific Extension. |
| 1026 | This tells the assembler to accept MDMX instructions. |
| 1027 | @samp{-no-mdmx} turns off this option. |
| 1028 | |
| 1029 | @item -mdsp |
| 1030 | @itemx -mno-dsp |
| 1031 | Generate code for the DSP Application Specific Extension. |
| 1032 | This tells the assembler to accept DSP instructions. |
| 1033 | @samp{-mno-dsp} turns off this option. |
| 1034 | |
| 1035 | @item -mmt |
| 1036 | @itemx -mno-mt |
| 1037 | Generate code for the MT Application Specific Extension. |
| 1038 | This tells the assembler to accept MT instructions. |
| 1039 | @samp{-mno-mt} turns off this option. |
| 1040 | |
| 1041 | @item --construct-floats |
| 1042 | @itemx --no-construct-floats |
| 1043 | The @samp{--no-construct-floats} option disables the construction of |
| 1044 | double width floating point constants by loading the two halves of the |
| 1045 | value into the two single width floating point registers that make up |
| 1046 | the double width register. By default @samp{--construct-floats} is |
| 1047 | selected, allowing construction of these floating point constants. |
| 1048 | |
| 1049 | @cindex emulation |
| 1050 | @item --emulation=@var{name} |
| 1051 | This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured |
| 1052 | for some other target, in all respects, including output format (choosing |
| 1053 | between ELF and ECOFF only), handling of pseudo-opcodes which may generate |
| 1054 | debugging information or store symbol table information, and default |
| 1055 | endianness. The available configuration names are: @samp{mipsecoff}, |
| 1056 | @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf}, |
| 1057 | @samp{mipsbelf}. The first two do not alter the default endianness from that |
| 1058 | of the primary target for which the assembler was configured; the others change |
| 1059 | the default to little- or big-endian as indicated by the @samp{b} or @samp{l} |
| 1060 | in the name. Using @samp{-EB} or @samp{-EL} will override the endianness |
| 1061 | selection in any case. |
| 1062 | |
| 1063 | This option is currently supported only when the primary target |
| 1064 | @command{@value{AS}} is configured for is a @sc{mips} ELF or ECOFF target. |
| 1065 | Furthermore, the primary target or others specified with |
| 1066 | @samp{--enable-targets=@dots{}} at configuration time must include support for |
| 1067 | the other format, if both are to be available. For example, the Irix 5 |
| 1068 | configuration includes support for both. |
| 1069 | |
| 1070 | Eventually, this option will support more configurations, with more |
| 1071 | fine-grained control over the assembler's behavior, and will be supported for |
| 1072 | more processors. |
| 1073 | |
| 1074 | @item -nocpp |
| 1075 | @command{@value{AS}} ignores this option. It is accepted for compatibility with |
| 1076 | the native tools. |
| 1077 | |
| 1078 | @item --trap |
| 1079 | @itemx --no-trap |
| 1080 | @itemx --break |
| 1081 | @itemx --no-break |
| 1082 | Control how to deal with multiplication overflow and division by zero. |
| 1083 | @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception |
| 1084 | (and only work for Instruction Set Architecture level 2 and higher); |
| 1085 | @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a |
| 1086 | break exception. |
| 1087 | |
| 1088 | @item -n |
| 1089 | When this option is used, @command{@value{AS}} will issue a warning every |
| 1090 | time it generates a nop instruction from a macro. |
| 1091 | @end table |
| 1092 | @end ifset |
| 1093 | |
| 1094 | @ifset MCORE |
| 1095 | The following options are available when @value{AS} is configured for |
| 1096 | an MCore processor. |
| 1097 | |
| 1098 | @table @gcctabopt |
| 1099 | @item -jsri2bsr |
| 1100 | @itemx -nojsri2bsr |
| 1101 | Enable or disable the JSRI to BSR transformation. By default this is enabled. |
| 1102 | The command line option @samp{-nojsri2bsr} can be used to disable it. |
| 1103 | |
| 1104 | @item -sifilter |
| 1105 | @itemx -nosifilter |
| 1106 | Enable or disable the silicon filter behaviour. By default this is disabled. |
| 1107 | The default can be overridden by the @samp{-sifilter} command line option. |
| 1108 | |
| 1109 | @item -relax |
| 1110 | Alter jump instructions for long displacements. |
| 1111 | |
| 1112 | @item -mcpu=[210|340] |
| 1113 | Select the cpu type on the target hardware. This controls which instructions |
| 1114 | can be assembled. |
| 1115 | |
| 1116 | @item -EB |
| 1117 | Assemble for a big endian target. |
| 1118 | |
| 1119 | @item -EL |
| 1120 | Assemble for a little endian target. |
| 1121 | |
| 1122 | @end table |
| 1123 | @end ifset |
| 1124 | |
| 1125 | @ifset MMIX |
| 1126 | See the info pages for documentation of the MMIX-specific options. |
| 1127 | @end ifset |
| 1128 | |
| 1129 | @ifset XTENSA |
| 1130 | The following options are available when @value{AS} is configured for |
| 1131 | an Xtensa processor. |
| 1132 | |
| 1133 | @table @gcctabopt |
| 1134 | @item --text-section-literals | --no-text-section-literals |
| 1135 | With @option{--text-@-section-@-literals}, literal pools are interspersed |
| 1136 | in the text section. The default is |
| 1137 | @option{--no-@-text-@-section-@-literals}, which places literals in a |
| 1138 | separate section in the output file. These options only affect literals |
| 1139 | referenced via PC-relative @code{L32R} instructions; literals for |
| 1140 | absolute mode @code{L32R} instructions are handled separately. |
| 1141 | |
| 1142 | @item --absolute-literals | --no-absolute-literals |
| 1143 | Indicate to the assembler whether @code{L32R} instructions use absolute |
| 1144 | or PC-relative addressing. The default is to assume absolute addressing |
| 1145 | if the Xtensa processor includes the absolute @code{L32R} addressing |
| 1146 | option. Otherwise, only the PC-relative @code{L32R} mode can be used. |
| 1147 | |
| 1148 | @item --target-align | --no-target-align |
| 1149 | Enable or disable automatic alignment to reduce branch penalties at the |
| 1150 | expense of some code density. The default is @option{--target-@-align}. |
| 1151 | |
| 1152 | @item --longcalls | --no-longcalls |
| 1153 | Enable or disable transformation of call instructions to allow calls |
| 1154 | across a greater range of addresses. The default is |
| 1155 | @option{--no-@-longcalls}. |
| 1156 | |
| 1157 | @item --transform | --no-transform |
| 1158 | Enable or disable all assembler transformations of Xtensa instructions. |
| 1159 | The default is @option{--transform}; |
| 1160 | @option{--no-transform} should be used only in the rare cases when the |
| 1161 | instructions must be exactly as specified in the assembly source. |
| 1162 | @end table |
| 1163 | @end ifset |
| 1164 | |
| 1165 | @ifset Z80 |
| 1166 | The following options are available when @value{AS} is configured for |
| 1167 | a Z80 family processor. |
| 1168 | @table @gcctabopt |
| 1169 | @item -z80 |
| 1170 | Assemble for Z80 processor. |
| 1171 | @item -r800 |
| 1172 | Assemble for R800 processor. |
| 1173 | @item -ignore-undocumented-instructions |
| 1174 | @itemx -Wnud |
| 1175 | Assemble undocumented Z80 instructions that also work on R800 without warning. |
| 1176 | @item -ignore-unportable-instructions |
| 1177 | @itemx -Wnup |
| 1178 | Assemble all undocumented Z80 instructions without warning. |
| 1179 | @item -warn-undocumented-instructions |
| 1180 | @itemx -Wud |
| 1181 | Issue a warning for undocumented Z80 instructions that also work on R800. |
| 1182 | @item -warn-unportable-instructions |
| 1183 | @itemx -Wup |
| 1184 | Issue a warning for undocumented Z80 instructions that do notwork on R800. |
| 1185 | @item -forbid-undocumented-instructions |
| 1186 | @itemx -Fud |
| 1187 | Treat all undocumented instructions as errors. |
| 1188 | @item -forbid-unportable-instructions |
| 1189 | @itemx -Fup |
| 1190 | Treat undocumented Z80 intructions that do notwork on R800 as errors. |
| 1191 | @end table |
| 1192 | @end ifset |
| 1193 | |
| 1194 | @c man end |
| 1195 | |
| 1196 | @menu |
| 1197 | * Manual:: Structure of this Manual |
| 1198 | * GNU Assembler:: The GNU Assembler |
| 1199 | * Object Formats:: Object File Formats |
| 1200 | * Command Line:: Command Line |
| 1201 | * Input Files:: Input Files |
| 1202 | * Object:: Output (Object) File |
| 1203 | * Errors:: Error and Warning Messages |
| 1204 | @end menu |
| 1205 | |
| 1206 | @node Manual |
| 1207 | @section Structure of this Manual |
| 1208 | |
| 1209 | @cindex manual, structure and purpose |
| 1210 | This manual is intended to describe what you need to know to use |
| 1211 | @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including |
| 1212 | notation for symbols, constants, and expressions; the directives that |
| 1213 | @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}. |
| 1214 | |
| 1215 | @ifclear GENERIC |
| 1216 | We also cover special features in the @value{TARGET} |
| 1217 | configuration of @command{@value{AS}}, including assembler directives. |
| 1218 | @end ifclear |
| 1219 | @ifset GENERIC |
| 1220 | This manual also describes some of the machine-dependent features of |
| 1221 | various flavors of the assembler. |
| 1222 | @end ifset |
| 1223 | |
| 1224 | @cindex machine instructions (not covered) |
| 1225 | On the other hand, this manual is @emph{not} intended as an introduction |
| 1226 | to programming in assembly language---let alone programming in general! |
| 1227 | In a similar vein, we make no attempt to introduce the machine |
| 1228 | architecture; we do @emph{not} describe the instruction set, standard |
| 1229 | mnemonics, registers or addressing modes that are standard to a |
| 1230 | particular architecture. |
| 1231 | @ifset GENERIC |
| 1232 | You may want to consult the manufacturer's |
| 1233 | machine architecture manual for this information. |
| 1234 | @end ifset |
| 1235 | @ifclear GENERIC |
| 1236 | @ifset H8/300 |
| 1237 | For information on the H8/300 machine instruction set, see @cite{H8/300 |
| 1238 | Series Programming Manual}. For the H8/300H, see @cite{H8/300H Series |
| 1239 | Programming Manual} (Renesas). |
| 1240 | @end ifset |
| 1241 | @ifset SH |
| 1242 | For information on the Renesas (formerly Hitachi) / SuperH SH machine instruction set, |
| 1243 | see @cite{SH-Microcomputer User's Manual} (Renesas) or |
| 1244 | @cite{SH-4 32-bit CPU Core Architecture} (SuperH) and |
| 1245 | @cite{SuperH (SH) 64-Bit RISC Series} (SuperH). |
| 1246 | @end ifset |
| 1247 | @ifset Z8000 |
| 1248 | For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual} |
| 1249 | @end ifset |
| 1250 | @end ifclear |
| 1251 | |
| 1252 | @c I think this is premature---doc@cygnus.com, 17jan1991 |
| 1253 | @ignore |
| 1254 | Throughout this manual, we assume that you are running @dfn{GNU}, |
| 1255 | the portable operating system from the @dfn{Free Software |
| 1256 | Foundation, Inc.}. This restricts our attention to certain kinds of |
| 1257 | computer (in particular, the kinds of computers that @sc{gnu} can run on); |
| 1258 | once this assumption is granted examples and definitions need less |
| 1259 | qualification. |
| 1260 | |
| 1261 | @command{@value{AS}} is part of a team of programs that turn a high-level |
| 1262 | human-readable series of instructions into a low-level |
| 1263 | computer-readable series of instructions. Different versions of |
| 1264 | @command{@value{AS}} are used for different kinds of computer. |
| 1265 | @end ignore |
| 1266 | |
| 1267 | @c There used to be a section "Terminology" here, which defined |
| 1268 | @c "contents", "byte", "word", and "long". Defining "word" to any |
| 1269 | @c particular size is confusing when the .word directive may generate 16 |
| 1270 | @c bits on one machine and 32 bits on another; in general, for the user |
| 1271 | @c version of this manual, none of these terms seem essential to define. |
| 1272 | @c They were used very little even in the former draft of the manual; |
| 1273 | @c this draft makes an effort to avoid them (except in names of |
| 1274 | @c directives). |
| 1275 | |
| 1276 | @node GNU Assembler |
| 1277 | @section The GNU Assembler |
| 1278 | |
| 1279 | @c man begin DESCRIPTION |
| 1280 | |
| 1281 | @sc{gnu} @command{as} is really a family of assemblers. |
| 1282 | @ifclear GENERIC |
| 1283 | This manual describes @command{@value{AS}}, a member of that family which is |
| 1284 | configured for the @value{TARGET} architectures. |
| 1285 | @end ifclear |
| 1286 | If you use (or have used) the @sc{gnu} assembler on one architecture, you |
| 1287 | should find a fairly similar environment when you use it on another |
| 1288 | architecture. Each version has much in common with the others, |
| 1289 | including object file formats, most assembler directives (often called |
| 1290 | @dfn{pseudo-ops}) and assembler syntax.@refill |
| 1291 | |
| 1292 | @cindex purpose of @sc{gnu} assembler |
| 1293 | @command{@value{AS}} is primarily intended to assemble the output of the |
| 1294 | @sc{gnu} C compiler @code{@value{GCC}} for use by the linker |
| 1295 | @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}} |
| 1296 | assemble correctly everything that other assemblers for the same |
| 1297 | machine would assemble. |
| 1298 | @ifset VAX |
| 1299 | Any exceptions are documented explicitly (@pxref{Machine Dependencies}). |
| 1300 | @end ifset |
| 1301 | @ifset M680X0 |
| 1302 | @c This remark should appear in generic version of manual; assumption |
| 1303 | @c here is that generic version sets M680x0. |
| 1304 | This doesn't mean @command{@value{AS}} always uses the same syntax as another |
| 1305 | assembler for the same architecture; for example, we know of several |
| 1306 | incompatible versions of 680x0 assembly language syntax. |
| 1307 | @end ifset |
| 1308 | |
| 1309 | @c man end |
| 1310 | |
| 1311 | Unlike older assemblers, @command{@value{AS}} is designed to assemble a source |
| 1312 | program in one pass of the source file. This has a subtle impact on the |
| 1313 | @kbd{.org} directive (@pxref{Org,,@code{.org}}). |
| 1314 | |
| 1315 | @node Object Formats |
| 1316 | @section Object File Formats |
| 1317 | |
| 1318 | @cindex object file format |
| 1319 | The @sc{gnu} assembler can be configured to produce several alternative |
| 1320 | object file formats. For the most part, this does not affect how you |
| 1321 | write assembly language programs; but directives for debugging symbols |
| 1322 | are typically different in different file formats. @xref{Symbol |
| 1323 | Attributes,,Symbol Attributes}. |
| 1324 | @ifclear GENERIC |
| 1325 | @ifclear MULTI-OBJ |
| 1326 | For the @value{TARGET} target, @command{@value{AS}} is configured to produce |
| 1327 | @value{OBJ-NAME} format object files. |
| 1328 | @end ifclear |
| 1329 | @c The following should exhaust all configs that set MULTI-OBJ, ideally |
| 1330 | @ifset I960 |
| 1331 | On the @value{TARGET}, @command{@value{AS}} can be configured to produce either |
| 1332 | @code{b.out} or COFF format object files. |
| 1333 | @end ifset |
| 1334 | @ifset HPPA |
| 1335 | On the @value{TARGET}, @command{@value{AS}} can be configured to produce either |
| 1336 | SOM or ELF format object files. |
| 1337 | @end ifset |
| 1338 | @end ifclear |
| 1339 | |
| 1340 | @node Command Line |
| 1341 | @section Command Line |
| 1342 | |
| 1343 | @cindex command line conventions |
| 1344 | |
| 1345 | After the program name @command{@value{AS}}, the command line may contain |
| 1346 | options and file names. Options may appear in any order, and may be |
| 1347 | before, after, or between file names. The order of file names is |
| 1348 | significant. |
| 1349 | |
| 1350 | @cindex standard input, as input file |
| 1351 | @kindex -- |
| 1352 | @file{--} (two hyphens) by itself names the standard input file |
| 1353 | explicitly, as one of the files for @command{@value{AS}} to assemble. |
| 1354 | |
| 1355 | @cindex options, command line |
| 1356 | Except for @samp{--} any command line argument that begins with a |
| 1357 | hyphen (@samp{-}) is an option. Each option changes the behavior of |
| 1358 | @command{@value{AS}}. No option changes the way another option works. An |
| 1359 | option is a @samp{-} followed by one or more letters; the case of |
| 1360 | the letter is important. All options are optional. |
| 1361 | |
| 1362 | Some options expect exactly one file name to follow them. The file |
| 1363 | name may either immediately follow the option's letter (compatible |
| 1364 | with older assemblers) or it may be the next command argument (@sc{gnu} |
| 1365 | standard). These two command lines are equivalent: |
| 1366 | |
| 1367 | @smallexample |
| 1368 | @value{AS} -o my-object-file.o mumble.s |
| 1369 | @value{AS} -omy-object-file.o mumble.s |
| 1370 | @end smallexample |
| 1371 | |
| 1372 | @node Input Files |
| 1373 | @section Input Files |
| 1374 | |
| 1375 | @cindex input |
| 1376 | @cindex source program |
| 1377 | @cindex files, input |
| 1378 | We use the phrase @dfn{source program}, abbreviated @dfn{source}, to |
| 1379 | describe the program input to one run of @command{@value{AS}}. The program may |
| 1380 | be in one or more files; how the source is partitioned into files |
| 1381 | doesn't change the meaning of the source. |
| 1382 | |
| 1383 | @c I added "con" prefix to "catenation" just to prove I can overcome my |
| 1384 | @c APL training... doc@cygnus.com |
| 1385 | The source program is a concatenation of the text in all the files, in the |
| 1386 | order specified. |
| 1387 | |
| 1388 | @c man begin DESCRIPTION |
| 1389 | Each time you run @command{@value{AS}} it assembles exactly one source |
| 1390 | program. The source program is made up of one or more files. |
| 1391 | (The standard input is also a file.) |
| 1392 | |
| 1393 | You give @command{@value{AS}} a command line that has zero or more input file |
| 1394 | names. The input files are read (from left file name to right). A |
| 1395 | command line argument (in any position) that has no special meaning |
| 1396 | is taken to be an input file name. |
| 1397 | |
| 1398 | If you give @command{@value{AS}} no file names it attempts to read one input file |
| 1399 | from the @command{@value{AS}} standard input, which is normally your terminal. You |
| 1400 | may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program |
| 1401 | to assemble. |
| 1402 | |
| 1403 | Use @samp{--} if you need to explicitly name the standard input file |
| 1404 | in your command line. |
| 1405 | |
| 1406 | If the source is empty, @command{@value{AS}} produces a small, empty object |
| 1407 | file. |
| 1408 | |
| 1409 | @c man end |
| 1410 | |
| 1411 | @subheading Filenames and Line-numbers |
| 1412 | |
| 1413 | @cindex input file linenumbers |
| 1414 | @cindex line numbers, in input files |
| 1415 | There are two ways of locating a line in the input file (or files) and |
| 1416 | either may be used in reporting error messages. One way refers to a line |
| 1417 | number in a physical file; the other refers to a line number in a |
| 1418 | ``logical'' file. @xref{Errors, ,Error and Warning Messages}. |
| 1419 | |
| 1420 | @dfn{Physical files} are those files named in the command line given |
| 1421 | to @command{@value{AS}}. |
| 1422 | |
| 1423 | @dfn{Logical files} are simply names declared explicitly by assembler |
| 1424 | directives; they bear no relation to physical files. Logical file names help |
| 1425 | error messages reflect the original source file, when @command{@value{AS}} source |
| 1426 | is itself synthesized from other files. @command{@value{AS}} understands the |
| 1427 | @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also |
| 1428 | @ref{File,,@code{.file}}. |
| 1429 | |
| 1430 | @node Object |
| 1431 | @section Output (Object) File |
| 1432 | |
| 1433 | @cindex object file |
| 1434 | @cindex output file |
| 1435 | @kindex a.out |
| 1436 | @kindex .o |
| 1437 | Every time you run @command{@value{AS}} it produces an output file, which is |
| 1438 | your assembly language program translated into numbers. This file |
| 1439 | is the object file. Its default name is |
| 1440 | @ifclear BOUT |
| 1441 | @code{a.out}. |
| 1442 | @end ifclear |
| 1443 | @ifset BOUT |
| 1444 | @ifset GENERIC |
| 1445 | @code{a.out}, or |
| 1446 | @end ifset |
| 1447 | @code{b.out} when @command{@value{AS}} is configured for the Intel 80960. |
| 1448 | @end ifset |
| 1449 | You can give it another name by using the @option{-o} option. Conventionally, |
| 1450 | object file names end with @file{.o}. The default name is used for historical |
| 1451 | reasons: older assemblers were capable of assembling self-contained programs |
| 1452 | directly into a runnable program. (For some formats, this isn't currently |
| 1453 | possible, but it can be done for the @code{a.out} format.) |
| 1454 | |
| 1455 | @cindex linker |
| 1456 | @kindex ld |
| 1457 | The object file is meant for input to the linker @code{@value{LD}}. It contains |
| 1458 | assembled program code, information to help @code{@value{LD}} integrate |
| 1459 | the assembled program into a runnable file, and (optionally) symbolic |
| 1460 | information for the debugger. |
| 1461 | |
| 1462 | @c link above to some info file(s) like the description of a.out. |
| 1463 | @c don't forget to describe @sc{gnu} info as well as Unix lossage. |
| 1464 | |
| 1465 | @node Errors |
| 1466 | @section Error and Warning Messages |
| 1467 | |
| 1468 | @c man begin DESCRIPTION |
| 1469 | |
| 1470 | @cindex error messages |
| 1471 | @cindex warning messages |
| 1472 | @cindex messages from assembler |
| 1473 | @command{@value{AS}} may write warnings and error messages to the standard error |
| 1474 | file (usually your terminal). This should not happen when a compiler |
| 1475 | runs @command{@value{AS}} automatically. Warnings report an assumption made so |
| 1476 | that @command{@value{AS}} could keep assembling a flawed program; errors report a |
| 1477 | grave problem that stops the assembly. |
| 1478 | |
| 1479 | @c man end |
| 1480 | |
| 1481 | @cindex format of warning messages |
| 1482 | Warning messages have the format |
| 1483 | |
| 1484 | @smallexample |
| 1485 | file_name:@b{NNN}:Warning Message Text |
| 1486 | @end smallexample |
| 1487 | |
| 1488 | @noindent |
| 1489 | @cindex line numbers, in warnings/errors |
| 1490 | (where @b{NNN} is a line number). If a logical file name has been given |
| 1491 | (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of |
| 1492 | the current input file is used. If a logical line number was given |
| 1493 | @ifset GENERIC |
| 1494 | (@pxref{Line,,@code{.line}}) |
| 1495 | @end ifset |
| 1496 | then it is used to calculate the number printed, |
| 1497 | otherwise the actual line in the current source file is printed. The |
| 1498 | message text is intended to be self explanatory (in the grand Unix |
| 1499 | tradition). |
| 1500 | |
| 1501 | @cindex format of error messages |
| 1502 | Error messages have the format |
| 1503 | @smallexample |
| 1504 | file_name:@b{NNN}:FATAL:Error Message Text |
| 1505 | @end smallexample |
| 1506 | The file name and line number are derived as for warning |
| 1507 | messages. The actual message text may be rather less explanatory |
| 1508 | because many of them aren't supposed to happen. |
| 1509 | |
| 1510 | @node Invoking |
| 1511 | @chapter Command-Line Options |
| 1512 | |
| 1513 | @cindex options, all versions of assembler |
| 1514 | This chapter describes command-line options available in @emph{all} |
| 1515 | versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific |
| 1516 | @ifclear GENERIC |
| 1517 | to the @value{TARGET} target. |
| 1518 | @end ifclear |
| 1519 | @ifset GENERIC |
| 1520 | to particular machine architectures. |
| 1521 | @end ifset |
| 1522 | |
| 1523 | @c man begin DESCRIPTION |
| 1524 | |
| 1525 | If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler, |
| 1526 | you can use the @samp{-Wa} option to pass arguments through to the assembler. |
| 1527 | The assembler arguments must be separated from each other (and the @samp{-Wa}) |
| 1528 | by commas. For example: |
| 1529 | |
| 1530 | @smallexample |
| 1531 | gcc -c -g -O -Wa,-alh,-L file.c |
| 1532 | @end smallexample |
| 1533 | |
| 1534 | @noindent |
| 1535 | This passes two options to the assembler: @samp{-alh} (emit a listing to |
| 1536 | standard output with high-level and assembly source) and @samp{-L} (retain |
| 1537 | local symbols in the symbol table). |
| 1538 | |
| 1539 | Usually you do not need to use this @samp{-Wa} mechanism, since many compiler |
| 1540 | command-line options are automatically passed to the assembler by the compiler. |
| 1541 | (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see |
| 1542 | precisely what options it passes to each compilation pass, including the |
| 1543 | assembler.) |
| 1544 | |
| 1545 | @c man end |
| 1546 | |
| 1547 | @menu |
| 1548 | * a:: -a[cdhlns] enable listings |
| 1549 | * alternate:: --alternate enable alternate macro syntax |
| 1550 | * D:: -D for compatibility |
| 1551 | * f:: -f to work faster |
| 1552 | * I:: -I for .include search path |
| 1553 | @ifclear DIFF-TBL-KLUGE |
| 1554 | * K:: -K for compatibility |
| 1555 | @end ifclear |
| 1556 | @ifset DIFF-TBL-KLUGE |
| 1557 | * K:: -K for difference tables |
| 1558 | @end ifset |
| 1559 | |
| 1560 | * L:: -L to retain local labels |
| 1561 | * listing:: --listing-XXX to configure listing output |
| 1562 | * M:: -M or --mri to assemble in MRI compatibility mode |
| 1563 | * MD:: --MD for dependency tracking |
| 1564 | * o:: -o to name the object file |
| 1565 | * R:: -R to join data and text sections |
| 1566 | * statistics:: --statistics to see statistics about assembly |
| 1567 | * traditional-format:: --traditional-format for compatible output |
| 1568 | * v:: -v to announce version |
| 1569 | * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings |
| 1570 | * Z:: -Z to make object file even after errors |
| 1571 | @end menu |
| 1572 | |
| 1573 | @node a |
| 1574 | @section Enable Listings: @option{-a[cdhlns]} |
| 1575 | |
| 1576 | @kindex -a |
| 1577 | @kindex -ac |
| 1578 | @kindex -ad |
| 1579 | @kindex -ah |
| 1580 | @kindex -al |
| 1581 | @kindex -an |
| 1582 | @kindex -as |
| 1583 | @cindex listings, enabling |
| 1584 | @cindex assembly listings, enabling |
| 1585 | |
| 1586 | These options enable listing output from the assembler. By itself, |
| 1587 | @samp{-a} requests high-level, assembly, and symbols listing. |
| 1588 | You can use other letters to select specific options for the list: |
| 1589 | @samp{-ah} requests a high-level language listing, |
| 1590 | @samp{-al} requests an output-program assembly listing, and |
| 1591 | @samp{-as} requests a symbol table listing. |
| 1592 | High-level listings require that a compiler debugging option like |
| 1593 | @samp{-g} be used, and that assembly listings (@samp{-al}) be requested |
| 1594 | also. |
| 1595 | |
| 1596 | Use the @samp{-ac} option to omit false conditionals from a listing. Any lines |
| 1597 | which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any |
| 1598 | other conditional), or a true @code{.if} followed by an @code{.else}, will be |
| 1599 | omitted from the listing. |
| 1600 | |
| 1601 | Use the @samp{-ad} option to omit debugging directives from the |
| 1602 | listing. |
| 1603 | |
| 1604 | Once you have specified one of these options, you can further control |
| 1605 | listing output and its appearance using the directives @code{.list}, |
| 1606 | @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and |
| 1607 | @code{.sbttl}. |
| 1608 | The @samp{-an} option turns off all forms processing. |
| 1609 | If you do not request listing output with one of the @samp{-a} options, the |
| 1610 | listing-control directives have no effect. |
| 1611 | |
| 1612 | The letters after @samp{-a} may be combined into one option, |
| 1613 | @emph{e.g.}, @samp{-aln}. |
| 1614 | |
| 1615 | Note if the assembler source is coming from the standard input (eg because it |
| 1616 | is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch |
| 1617 | is being used) then the listing will not contain any comments or preprocessor |
| 1618 | directives. This is because the listing code buffers input source lines from |
| 1619 | stdin only after they have been preprocessed by the assembler. This reduces |
| 1620 | memory usage and makes the code more efficient. |
| 1621 | |
| 1622 | @node alternate |
| 1623 | @section @option{--alternate} |
| 1624 | |
| 1625 | @kindex --alternate |
| 1626 | Begin in alternate macro mode, see @ref{Altmacro,,@code{.altmacro}}. |
| 1627 | |
| 1628 | @node D |
| 1629 | @section @option{-D} |
| 1630 | |
| 1631 | @kindex -D |
| 1632 | This option has no effect whatsoever, but it is accepted to make it more |
| 1633 | likely that scripts written for other assemblers also work with |
| 1634 | @command{@value{AS}}. |
| 1635 | |
| 1636 | @node f |
| 1637 | @section Work Faster: @option{-f} |
| 1638 | |
| 1639 | @kindex -f |
| 1640 | @cindex trusted compiler |
| 1641 | @cindex faster processing (@option{-f}) |
| 1642 | @samp{-f} should only be used when assembling programs written by a |
| 1643 | (trusted) compiler. @samp{-f} stops the assembler from doing whitespace |
| 1644 | and comment preprocessing on |
| 1645 | the input file(s) before assembling them. @xref{Preprocessing, |
| 1646 | ,Preprocessing}. |
| 1647 | |
| 1648 | @quotation |
| 1649 | @emph{Warning:} if you use @samp{-f} when the files actually need to be |
| 1650 | preprocessed (if they contain comments, for example), @command{@value{AS}} does |
| 1651 | not work correctly. |
| 1652 | @end quotation |
| 1653 | |
| 1654 | @node I |
| 1655 | @section @code{.include} Search Path: @option{-I} @var{path} |
| 1656 | |
| 1657 | @kindex -I @var{path} |
| 1658 | @cindex paths for @code{.include} |
| 1659 | @cindex search path for @code{.include} |
| 1660 | @cindex @code{include} directive search path |
| 1661 | Use this option to add a @var{path} to the list of directories |
| 1662 | @command{@value{AS}} searches for files specified in @code{.include} |
| 1663 | directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as |
| 1664 | many times as necessary to include a variety of paths. The current |
| 1665 | working directory is always searched first; after that, @command{@value{AS}} |
| 1666 | searches any @samp{-I} directories in the same order as they were |
| 1667 | specified (left to right) on the command line. |
| 1668 | |
| 1669 | @node K |
| 1670 | @section Difference Tables: @option{-K} |
| 1671 | |
| 1672 | @kindex -K |
| 1673 | @ifclear DIFF-TBL-KLUGE |
| 1674 | On the @value{TARGET} family, this option is allowed, but has no effect. It is |
| 1675 | permitted for compatibility with the @sc{gnu} assembler on other platforms, |
| 1676 | where it can be used to warn when the assembler alters the machine code |
| 1677 | generated for @samp{.word} directives in difference tables. The @value{TARGET} |
| 1678 | family does not have the addressing limitations that sometimes lead to this |
| 1679 | alteration on other platforms. |
| 1680 | @end ifclear |
| 1681 | |
| 1682 | @ifset DIFF-TBL-KLUGE |
| 1683 | @cindex difference tables, warning |
| 1684 | @cindex warning for altered difference tables |
| 1685 | @command{@value{AS}} sometimes alters the code emitted for directives of the form |
| 1686 | @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}. |
| 1687 | You can use the @samp{-K} option if you want a warning issued when this |
| 1688 | is done. |
| 1689 | @end ifset |
| 1690 | |
| 1691 | @node L |
| 1692 | @section Include Local Labels: @option{-L} |
| 1693 | |
| 1694 | @kindex -L |
| 1695 | @cindex local labels, retaining in output |
| 1696 | Labels beginning with @samp{L} (upper case only) are called @dfn{local |
| 1697 | labels}. @xref{Symbol Names}. Normally you do not see such labels when |
| 1698 | debugging, because they are intended for the use of programs (like |
| 1699 | compilers) that compose assembler programs, not for your notice. |
| 1700 | Normally both @command{@value{AS}} and @code{@value{LD}} discard such labels, so you do not |
| 1701 | normally debug with them. |
| 1702 | |
| 1703 | This option tells @command{@value{AS}} to retain those @samp{L@dots{}} symbols |
| 1704 | in the object file. Usually if you do this you also tell the linker |
| 1705 | @code{@value{LD}} to preserve symbols whose names begin with @samp{L}. |
| 1706 | |
| 1707 | By default, a local label is any label beginning with @samp{L}, but each |
| 1708 | target is allowed to redefine the local label prefix. |
| 1709 | @ifset HPPA |
| 1710 | On the HPPA local labels begin with @samp{L$}. |
| 1711 | @end ifset |
| 1712 | |
| 1713 | @node listing |
| 1714 | @section Configuring listing output: @option{--listing} |
| 1715 | |
| 1716 | The listing feature of the assembler can be enabled via the command line switch |
| 1717 | @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a |
| 1718 | hex dump of the corresponding locations in the output object file, and displays |
| 1719 | them as a listing file. The format of this listing can be controlled by pseudo |
| 1720 | ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl} |
| 1721 | @pxref{Psize} @pxref{Eject}) and also by the following switches: |
| 1722 | |
| 1723 | @table @gcctabopt |
| 1724 | @item --listing-lhs-width=@samp{number} |
| 1725 | @kindex --listing-lhs-width |
| 1726 | @cindex Width of first line disassembly output |
| 1727 | Sets the maximum width, in words, of the first line of the hex byte dump. This |
| 1728 | dump appears on the left hand side of the listing output. |
| 1729 | |
| 1730 | @item --listing-lhs-width2=@samp{number} |
| 1731 | @kindex --listing-lhs-width2 |
| 1732 | @cindex Width of continuation lines of disassembly output |
| 1733 | Sets the maximum width, in words, of any further lines of the hex byte dump for |
| 1734 | a given input source line. If this value is not specified, it defaults to being |
| 1735 | the same as the value specified for @samp{--listing-lhs-width}. If neither |
| 1736 | switch is used the default is to one. |
| 1737 | |
| 1738 | @item --listing-rhs-width=@samp{number} |
| 1739 | @kindex --listing-rhs-width |
| 1740 | @cindex Width of source line output |
| 1741 | Sets the maximum width, in characters, of the source line that is displayed |
| 1742 | alongside the hex dump. The default value for this parameter is 100. The |
| 1743 | source line is displayed on the right hand side of the listing output. |
| 1744 | |
| 1745 | @item --listing-cont-lines=@samp{number} |
| 1746 | @kindex --listing-cont-lines |
| 1747 | @cindex Maximum number of continuation lines |
| 1748 | Sets the maximum number of continuation lines of hex dump that will be |
| 1749 | displayed for a given single line of source input. The default value is 4. |
| 1750 | @end table |
| 1751 | |
| 1752 | @node M |
| 1753 | @section Assemble in MRI Compatibility Mode: @option{-M} |
| 1754 | |
| 1755 | @kindex -M |
| 1756 | @cindex MRI compatibility mode |
| 1757 | The @option{-M} or @option{--mri} option selects MRI compatibility mode. This |
| 1758 | changes the syntax and pseudo-op handling of @command{@value{AS}} to make it |
| 1759 | compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the |
| 1760 | configured target) assembler from Microtec Research. The exact nature of the |
| 1761 | MRI syntax will not be documented here; see the MRI manuals for more |
| 1762 | information. Note in particular that the handling of macros and macro |
| 1763 | arguments is somewhat different. The purpose of this option is to permit |
| 1764 | assembling existing MRI assembler code using @command{@value{AS}}. |
| 1765 | |
| 1766 | The MRI compatibility is not complete. Certain operations of the MRI assembler |
| 1767 | depend upon its object file format, and can not be supported using other object |
| 1768 | file formats. Supporting these would require enhancing each object file format |
| 1769 | individually. These are: |
| 1770 | |
| 1771 | @itemize @bullet |
| 1772 | @item global symbols in common section |
| 1773 | |
| 1774 | The m68k MRI assembler supports common sections which are merged by the linker. |
| 1775 | Other object file formats do not support this. @command{@value{AS}} handles |
| 1776 | common sections by treating them as a single common symbol. It permits local |
| 1777 | symbols to be defined within a common section, but it can not support global |
| 1778 | symbols, since it has no way to describe them. |
| 1779 | |
| 1780 | @item complex relocations |
| 1781 | |
| 1782 | The MRI assemblers support relocations against a negated section address, and |
| 1783 | relocations which combine the start addresses of two or more sections. These |
| 1784 | are not support by other object file formats. |
| 1785 | |
| 1786 | @item @code{END} pseudo-op specifying start address |
| 1787 | |
| 1788 | The MRI @code{END} pseudo-op permits the specification of a start address. |
| 1789 | This is not supported by other object file formats. The start address may |
| 1790 | instead be specified using the @option{-e} option to the linker, or in a linker |
| 1791 | script. |
| 1792 | |
| 1793 | @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops |
| 1794 | |
| 1795 | The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module |
| 1796 | name to the output file. This is not supported by other object file formats. |
| 1797 | |
| 1798 | @item @code{ORG} pseudo-op |
| 1799 | |
| 1800 | The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given |
| 1801 | address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op, |
| 1802 | which changes the location within the current section. Absolute sections are |
| 1803 | not supported by other object file formats. The address of a section may be |
| 1804 | assigned within a linker script. |
| 1805 | @end itemize |
| 1806 | |
| 1807 | There are some other features of the MRI assembler which are not supported by |
| 1808 | @command{@value{AS}}, typically either because they are difficult or because they |
| 1809 | seem of little consequence. Some of these may be supported in future releases. |
| 1810 | |
| 1811 | @itemize @bullet |
| 1812 | |
| 1813 | @item EBCDIC strings |
| 1814 | |
| 1815 | EBCDIC strings are not supported. |
| 1816 | |
| 1817 | @item packed binary coded decimal |
| 1818 | |
| 1819 | Packed binary coded decimal is not supported. This means that the @code{DC.P} |
| 1820 | and @code{DCB.P} pseudo-ops are not supported. |
| 1821 | |
| 1822 | @item @code{FEQU} pseudo-op |
| 1823 | |
| 1824 | The m68k @code{FEQU} pseudo-op is not supported. |
| 1825 | |
| 1826 | @item @code{NOOBJ} pseudo-op |
| 1827 | |
| 1828 | The m68k @code{NOOBJ} pseudo-op is not supported. |
| 1829 | |
| 1830 | @item @code{OPT} branch control options |
| 1831 | |
| 1832 | The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB}, |
| 1833 | @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically |
| 1834 | relaxes all branches, whether forward or backward, to an appropriate size, so |
| 1835 | these options serve no purpose. |
| 1836 | |
| 1837 | @item @code{OPT} list control options |
| 1838 | |
| 1839 | The following m68k @code{OPT} list control options are ignored: @code{C}, |
| 1840 | @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M}, |
| 1841 | @code{MEX}, @code{MC}, @code{MD}, @code{X}. |
| 1842 | |
| 1843 | @item other @code{OPT} options |
| 1844 | |
| 1845 | The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O}, |
| 1846 | @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}. |
| 1847 | |
| 1848 | @item @code{OPT} @code{D} option is default |
| 1849 | |
| 1850 | The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler. |
| 1851 | @code{OPT NOD} may be used to turn it off. |
| 1852 | |
| 1853 | @item @code{XREF} pseudo-op. |
| 1854 | |
| 1855 | The m68k @code{XREF} pseudo-op is ignored. |
| 1856 | |
| 1857 | @item @code{.debug} pseudo-op |
| 1858 | |
| 1859 | The i960 @code{.debug} pseudo-op is not supported. |
| 1860 | |
| 1861 | @item @code{.extended} pseudo-op |
| 1862 | |
| 1863 | The i960 @code{.extended} pseudo-op is not supported. |
| 1864 | |
| 1865 | @item @code{.list} pseudo-op. |
| 1866 | |
| 1867 | The various options of the i960 @code{.list} pseudo-op are not supported. |
| 1868 | |
| 1869 | @item @code{.optimize} pseudo-op |
| 1870 | |
| 1871 | The i960 @code{.optimize} pseudo-op is not supported. |
| 1872 | |
| 1873 | @item @code{.output} pseudo-op |
| 1874 | |
| 1875 | The i960 @code{.output} pseudo-op is not supported. |
| 1876 | |
| 1877 | @item @code{.setreal} pseudo-op |
| 1878 | |
| 1879 | The i960 @code{.setreal} pseudo-op is not supported. |
| 1880 | |
| 1881 | @end itemize |
| 1882 | |
| 1883 | @node MD |
| 1884 | @section Dependency Tracking: @option{--MD} |
| 1885 | |
| 1886 | @kindex --MD |
| 1887 | @cindex dependency tracking |
| 1888 | @cindex make rules |
| 1889 | |
| 1890 | @command{@value{AS}} can generate a dependency file for the file it creates. This |
| 1891 | file consists of a single rule suitable for @code{make} describing the |
| 1892 | dependencies of the main source file. |
| 1893 | |
| 1894 | The rule is written to the file named in its argument. |
| 1895 | |
| 1896 | This feature is used in the automatic updating of makefiles. |
| 1897 | |
| 1898 | @node o |
| 1899 | @section Name the Object File: @option{-o} |
| 1900 | |
| 1901 | @kindex -o |
| 1902 | @cindex naming object file |
| 1903 | @cindex object file name |
| 1904 | There is always one object file output when you run @command{@value{AS}}. By |
| 1905 | default it has the name |
| 1906 | @ifset GENERIC |
| 1907 | @ifset I960 |
| 1908 | @file{a.out} (or @file{b.out}, for Intel 960 targets only). |
| 1909 | @end ifset |
| 1910 | @ifclear I960 |
| 1911 | @file{a.out}. |
| 1912 | @end ifclear |
| 1913 | @end ifset |
| 1914 | @ifclear GENERIC |
| 1915 | @ifset I960 |
| 1916 | @file{b.out}. |
| 1917 | @end ifset |
| 1918 | @ifclear I960 |
| 1919 | @file{a.out}. |
| 1920 | @end ifclear |
| 1921 | @end ifclear |
| 1922 | You use this option (which takes exactly one filename) to give the |
| 1923 | object file a different name. |
| 1924 | |
| 1925 | Whatever the object file is called, @command{@value{AS}} overwrites any |
| 1926 | existing file of the same name. |
| 1927 | |
| 1928 | @node R |
| 1929 | @section Join Data and Text Sections: @option{-R} |
| 1930 | |
| 1931 | @kindex -R |
| 1932 | @cindex data and text sections, joining |
| 1933 | @cindex text and data sections, joining |
| 1934 | @cindex joining text and data sections |
| 1935 | @cindex merging text and data sections |
| 1936 | @option{-R} tells @command{@value{AS}} to write the object file as if all |
| 1937 | data-section data lives in the text section. This is only done at |
| 1938 | the very last moment: your binary data are the same, but data |
| 1939 | section parts are relocated differently. The data section part of |
| 1940 | your object file is zero bytes long because all its bytes are |
| 1941 | appended to the text section. (@xref{Sections,,Sections and Relocation}.) |
| 1942 | |
| 1943 | When you specify @option{-R} it would be possible to generate shorter |
| 1944 | address displacements (because we do not have to cross between text and |
| 1945 | data section). We refrain from doing this simply for compatibility with |
| 1946 | older versions of @command{@value{AS}}. In future, @option{-R} may work this way. |
| 1947 | |
| 1948 | @ifset COFF-ELF |
| 1949 | When @command{@value{AS}} is configured for COFF or ELF output, |
| 1950 | this option is only useful if you use sections named @samp{.text} and |
| 1951 | @samp{.data}. |
| 1952 | @end ifset |
| 1953 | |
| 1954 | @ifset HPPA |
| 1955 | @option{-R} is not supported for any of the HPPA targets. Using |
| 1956 | @option{-R} generates a warning from @command{@value{AS}}. |
| 1957 | @end ifset |
| 1958 | |
| 1959 | @node statistics |
| 1960 | @section Display Assembly Statistics: @option{--statistics} |
| 1961 | |
| 1962 | @kindex --statistics |
| 1963 | @cindex statistics, about assembly |
| 1964 | @cindex time, total for assembly |
| 1965 | @cindex space used, maximum for assembly |
| 1966 | Use @samp{--statistics} to display two statistics about the resources used by |
| 1967 | @command{@value{AS}}: the maximum amount of space allocated during the assembly |
| 1968 | (in bytes), and the total execution time taken for the assembly (in @sc{cpu} |
| 1969 | seconds). |
| 1970 | |
| 1971 | @node traditional-format |
| 1972 | @section Compatible Output: @option{--traditional-format} |
| 1973 | |
| 1974 | @kindex --traditional-format |
| 1975 | For some targets, the output of @command{@value{AS}} is different in some ways |
| 1976 | from the output of some existing assembler. This switch requests |
| 1977 | @command{@value{AS}} to use the traditional format instead. |
| 1978 | |
| 1979 | For example, it disables the exception frame optimizations which |
| 1980 | @command{@value{AS}} normally does by default on @code{@value{GCC}} output. |
| 1981 | |
| 1982 | @node v |
| 1983 | @section Announce Version: @option{-v} |
| 1984 | |
| 1985 | @kindex -v |
| 1986 | @kindex -version |
| 1987 | @cindex assembler version |
| 1988 | @cindex version of assembler |
| 1989 | You can find out what version of as is running by including the |
| 1990 | option @samp{-v} (which you can also spell as @samp{-version}) on the |
| 1991 | command line. |
| 1992 | |
| 1993 | @node W |
| 1994 | @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings} |
| 1995 | |
| 1996 | @command{@value{AS}} should never give a warning or error message when |
| 1997 | assembling compiler output. But programs written by people often |
| 1998 | cause @command{@value{AS}} to give a warning that a particular assumption was |
| 1999 | made. All such warnings are directed to the standard error file. |
| 2000 | |
| 2001 | @kindex -W |
| 2002 | @kindex --no-warn |
| 2003 | @cindex suppressing warnings |
| 2004 | @cindex warnings, suppressing |
| 2005 | If you use the @option{-W} and @option{--no-warn} options, no warnings are issued. |
| 2006 | This only affects the warning messages: it does not change any particular of |
| 2007 | how @command{@value{AS}} assembles your file. Errors, which stop the assembly, |
| 2008 | are still reported. |
| 2009 | |
| 2010 | @kindex --fatal-warnings |
| 2011 | @cindex errors, caused by warnings |
| 2012 | @cindex warnings, causing error |
| 2013 | If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers |
| 2014 | files that generate warnings to be in error. |
| 2015 | |
| 2016 | @kindex --warn |
| 2017 | @cindex warnings, switching on |
| 2018 | You can switch these options off again by specifying @option{--warn}, which |
| 2019 | causes warnings to be output as usual. |
| 2020 | |
| 2021 | @node Z |
| 2022 | @section Generate Object File in Spite of Errors: @option{-Z} |
| 2023 | @cindex object file, after errors |
| 2024 | @cindex errors, continuing after |
| 2025 | After an error message, @command{@value{AS}} normally produces no output. If for |
| 2026 | some reason you are interested in object file output even after |
| 2027 | @command{@value{AS}} gives an error message on your program, use the @samp{-Z} |
| 2028 | option. If there are any errors, @command{@value{AS}} continues anyways, and |
| 2029 | writes an object file after a final warning message of the form @samp{@var{n} |
| 2030 | errors, @var{m} warnings, generating bad object file.} |
| 2031 | |
| 2032 | @node Syntax |
| 2033 | @chapter Syntax |
| 2034 | |
| 2035 | @cindex machine-independent syntax |
| 2036 | @cindex syntax, machine-independent |
| 2037 | This chapter describes the machine-independent syntax allowed in a |
| 2038 | source file. @command{@value{AS}} syntax is similar to what many other |
| 2039 | assemblers use; it is inspired by the BSD 4.2 |
| 2040 | @ifclear VAX |
| 2041 | assembler. |
| 2042 | @end ifclear |
| 2043 | @ifset VAX |
| 2044 | assembler, except that @command{@value{AS}} does not assemble Vax bit-fields. |
| 2045 | @end ifset |
| 2046 | |
| 2047 | @menu |
| 2048 | * Preprocessing:: Preprocessing |
| 2049 | * Whitespace:: Whitespace |
| 2050 | * Comments:: Comments |
| 2051 | * Symbol Intro:: Symbols |
| 2052 | * Statements:: Statements |
| 2053 | * Constants:: Constants |
| 2054 | @end menu |
| 2055 | |
| 2056 | @node Preprocessing |
| 2057 | @section Preprocessing |
| 2058 | |
| 2059 | @cindex preprocessing |
| 2060 | The @command{@value{AS}} internal preprocessor: |
| 2061 | @itemize @bullet |
| 2062 | @cindex whitespace, removed by preprocessor |
| 2063 | @item |
| 2064 | adjusts and removes extra whitespace. It leaves one space or tab before |
| 2065 | the keywords on a line, and turns any other whitespace on the line into |
| 2066 | a single space. |
| 2067 | |
| 2068 | @cindex comments, removed by preprocessor |
| 2069 | @item |
| 2070 | removes all comments, replacing them with a single space, or an |
| 2071 | appropriate number of newlines. |
| 2072 | |
| 2073 | @cindex constants, converted by preprocessor |
| 2074 | @item |
| 2075 | converts character constants into the appropriate numeric values. |
| 2076 | @end itemize |
| 2077 | |
| 2078 | It does not do macro processing, include file handling, or |
| 2079 | anything else you may get from your C compiler's preprocessor. You can |
| 2080 | do include file processing with the @code{.include} directive |
| 2081 | (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver |
| 2082 | to get other ``CPP'' style preprocessing by giving the input file a |
| 2083 | @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of |
| 2084 | Output, gcc.info, Using GNU CC}. |
| 2085 | |
| 2086 | Excess whitespace, comments, and character constants |
| 2087 | cannot be used in the portions of the input text that are not |
| 2088 | preprocessed. |
| 2089 | |
| 2090 | @cindex turning preprocessing on and off |
| 2091 | @cindex preprocessing, turning on and off |
| 2092 | @kindex #NO_APP |
| 2093 | @kindex #APP |
| 2094 | If the first line of an input file is @code{#NO_APP} or if you use the |
| 2095 | @samp{-f} option, whitespace and comments are not removed from the input file. |
| 2096 | Within an input file, you can ask for whitespace and comment removal in |
| 2097 | specific portions of the by putting a line that says @code{#APP} before the |
| 2098 | text that may contain whitespace or comments, and putting a line that says |
| 2099 | @code{#NO_APP} after this text. This feature is mainly intend to support |
| 2100 | @code{asm} statements in compilers whose output is otherwise free of comments |
| 2101 | and whitespace. |
| 2102 | |
| 2103 | @node Whitespace |
| 2104 | @section Whitespace |
| 2105 | |
| 2106 | @cindex whitespace |
| 2107 | @dfn{Whitespace} is one or more blanks or tabs, in any order. |
| 2108 | Whitespace is used to separate symbols, and to make programs neater for |
| 2109 | people to read. Unless within character constants |
| 2110 | (@pxref{Characters,,Character Constants}), any whitespace means the same |
| 2111 | as exactly one space. |
| 2112 | |
| 2113 | @node Comments |
| 2114 | @section Comments |
| 2115 | |
| 2116 | @cindex comments |
| 2117 | There are two ways of rendering comments to @command{@value{AS}}. In both |
| 2118 | cases the comment is equivalent to one space. |
| 2119 | |
| 2120 | Anything from @samp{/*} through the next @samp{*/} is a comment. |
| 2121 | This means you may not nest these comments. |
| 2122 | |
| 2123 | @smallexample |
| 2124 | /* |
| 2125 | The only way to include a newline ('\n') in a comment |
| 2126 | is to use this sort of comment. |
| 2127 | */ |
| 2128 | |
| 2129 | /* This sort of comment does not nest. */ |
| 2130 | @end smallexample |
| 2131 | |
| 2132 | @cindex line comment character |
| 2133 | Anything from the @dfn{line comment} character to the next newline |
| 2134 | is considered a comment and is ignored. The line comment character is |
| 2135 | @ifset ARC |
| 2136 | @samp{;} on the ARC; |
| 2137 | @end ifset |
| 2138 | @ifset ARM |
| 2139 | @samp{@@} on the ARM; |
| 2140 | @end ifset |
| 2141 | @ifset H8/300 |
| 2142 | @samp{;} for the H8/300 family; |
| 2143 | @end ifset |
| 2144 | @ifset HPPA |
| 2145 | @samp{;} for the HPPA; |
| 2146 | @end ifset |
| 2147 | @ifset I80386 |
| 2148 | @samp{#} on the i386 and x86-64; |
| 2149 | @end ifset |
| 2150 | @ifset I960 |
| 2151 | @samp{#} on the i960; |
| 2152 | @end ifset |
| 2153 | @ifset PDP11 |
| 2154 | @samp{;} for the PDP-11; |
| 2155 | @end ifset |
| 2156 | @ifset PJ |
| 2157 | @samp{;} for picoJava; |
| 2158 | @end ifset |
| 2159 | @ifset PPC |
| 2160 | @samp{#} for Motorola PowerPC; |
| 2161 | @end ifset |
| 2162 | @ifset SH |
| 2163 | @samp{!} for the Renesas / SuperH SH; |
| 2164 | @end ifset |
| 2165 | @ifset SPARC |
| 2166 | @samp{!} on the SPARC; |
| 2167 | @end ifset |
| 2168 | @ifset IP2K |
| 2169 | @samp{#} on the ip2k; |
| 2170 | @end ifset |
| 2171 | @ifset M32C |
| 2172 | @samp{#} on the m32c; |
| 2173 | @end ifset |
| 2174 | @ifset M32R |
| 2175 | @samp{#} on the m32r; |
| 2176 | @end ifset |
| 2177 | @ifset M680X0 |
| 2178 | @samp{|} on the 680x0; |
| 2179 | @end ifset |
| 2180 | @ifset M68HC11 |
| 2181 | @samp{#} on the 68HC11 and 68HC12; |
| 2182 | @end ifset |
| 2183 | @ifset VAX |
| 2184 | @samp{#} on the Vax; |
| 2185 | @end ifset |
| 2186 | @ifset Z80 |
| 2187 | @samp{;} for the Z80; |
| 2188 | @end ifset |
| 2189 | @ifset Z8000 |
| 2190 | @samp{!} for the Z8000; |
| 2191 | @end ifset |
| 2192 | @ifset V850 |
| 2193 | @samp{#} on the V850; |
| 2194 | @end ifset |
| 2195 | @ifset XTENSA |
| 2196 | @samp{#} for Xtensa systems; |
| 2197 | @end ifset |
| 2198 | see @ref{Machine Dependencies}. @refill |
| 2199 | @c FIXME What about i860? |
| 2200 | |
| 2201 | @ifset GENERIC |
| 2202 | On some machines there are two different line comment characters. One |
| 2203 | character only begins a comment if it is the first non-whitespace character on |
| 2204 | a line, while the other always begins a comment. |
| 2205 | @end ifset |
| 2206 | |
| 2207 | @ifset V850 |
| 2208 | The V850 assembler also supports a double dash as starting a comment that |
| 2209 | extends to the end of the line. |
| 2210 | |
| 2211 | @samp{--}; |
| 2212 | @end ifset |
| 2213 | |
| 2214 | @kindex # |
| 2215 | @cindex lines starting with @code{#} |
| 2216 | @cindex logical line numbers |
| 2217 | To be compatible with past assemblers, lines that begin with @samp{#} have a |
| 2218 | special interpretation. Following the @samp{#} should be an absolute |
| 2219 | expression (@pxref{Expressions}): the logical line number of the @emph{next} |
| 2220 | line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a |
| 2221 | new logical file name. The rest of the line, if any, should be whitespace. |
| 2222 | |
| 2223 | If the first non-whitespace characters on the line are not numeric, |
| 2224 | the line is ignored. (Just like a comment.) |
| 2225 | |
| 2226 | @smallexample |
| 2227 | # This is an ordinary comment. |
| 2228 | # 42-6 "new_file_name" # New logical file name |
| 2229 | # This is logical line # 36. |
| 2230 | @end smallexample |
| 2231 | This feature is deprecated, and may disappear from future versions |
| 2232 | of @command{@value{AS}}. |
| 2233 | |
| 2234 | @node Symbol Intro |
| 2235 | @section Symbols |
| 2236 | |
| 2237 | @cindex characters used in symbols |
| 2238 | @ifclear SPECIAL-SYMS |
| 2239 | A @dfn{symbol} is one or more characters chosen from the set of all |
| 2240 | letters (both upper and lower case), digits and the three characters |
| 2241 | @samp{_.$}. |
| 2242 | @end ifclear |
| 2243 | @ifset SPECIAL-SYMS |
| 2244 | @ifclear GENERIC |
| 2245 | @ifset H8 |
| 2246 | A @dfn{symbol} is one or more characters chosen from the set of all |
| 2247 | letters (both upper and lower case), digits and the three characters |
| 2248 | @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in |
| 2249 | symbol names.) |
| 2250 | @end ifset |
| 2251 | @end ifclear |
| 2252 | @end ifset |
| 2253 | @ifset GENERIC |
| 2254 | On most machines, you can also use @code{$} in symbol names; exceptions |
| 2255 | are noted in @ref{Machine Dependencies}. |
| 2256 | @end ifset |
| 2257 | No symbol may begin with a digit. Case is significant. |
| 2258 | There is no length limit: all characters are significant. Symbols are |
| 2259 | delimited by characters not in that set, or by the beginning of a file |
| 2260 | (since the source program must end with a newline, the end of a file is |
| 2261 | not a possible symbol delimiter). @xref{Symbols}. |
| 2262 | @cindex length of symbols |
| 2263 | |
| 2264 | @node Statements |
| 2265 | @section Statements |
| 2266 | |
| 2267 | @cindex statements, structure of |
| 2268 | @cindex line separator character |
| 2269 | @cindex statement separator character |
| 2270 | @ifclear GENERIC |
| 2271 | @ifclear abnormal-separator |
| 2272 | A @dfn{statement} ends at a newline character (@samp{\n}) or at a |
| 2273 | semicolon (@samp{;}). The newline or semicolon is considered part of |
| 2274 | the preceding statement. Newlines and semicolons within character |
| 2275 | constants are an exception: they do not end statements. |
| 2276 | @end ifclear |
| 2277 | @ifset abnormal-separator |
| 2278 | @ifset HPPA |
| 2279 | A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation |
| 2280 | point (@samp{!}). The newline or exclamation point is considered part of the |
| 2281 | preceding statement. Newlines and exclamation points within character |
| 2282 | constants are an exception: they do not end statements. |
| 2283 | @end ifset |
| 2284 | @ifset H8 |
| 2285 | A @dfn{statement} ends at a newline character (@samp{\n}); or (for the |
| 2286 | H8/300) a dollar sign (@samp{$}); or (for the Renesas-SH) a semicolon |
| 2287 | (@samp{;}). The newline or separator character is considered part of |
| 2288 | the preceding statement. Newlines and separators within character |
| 2289 | constants are an exception: they do not end statements. |
| 2290 | @end ifset |
| 2291 | @end ifset |
| 2292 | @end ifclear |
| 2293 | @ifset GENERIC |
| 2294 | A @dfn{statement} ends at a newline character (@samp{\n}) or line |
| 2295 | separator character. (The line separator is usually @samp{;}, unless |
| 2296 | this conflicts with the comment character; @pxref{Machine Dependencies}.) The |
| 2297 | newline or separator character is considered part of the preceding |
| 2298 | statement. Newlines and separators within character constants are an |
| 2299 | exception: they do not end statements. |
| 2300 | @end ifset |
| 2301 | |
| 2302 | @cindex newline, required at file end |
| 2303 | @cindex EOF, newline must precede |
| 2304 | It is an error to end any statement with end-of-file: the last |
| 2305 | character of any input file should be a newline.@refill |
| 2306 | |
| 2307 | An empty statement is allowed, and may include whitespace. It is ignored. |
| 2308 | |
| 2309 | @cindex instructions and directives |
| 2310 | @cindex directives and instructions |
| 2311 | @c "key symbol" is not used elsewhere in the document; seems pedantic to |
| 2312 | @c @defn{} it in that case, as was done previously... doc@cygnus.com, |
| 2313 | @c 13feb91. |
| 2314 | A statement begins with zero or more labels, optionally followed by a |
| 2315 | key symbol which determines what kind of statement it is. The key |
| 2316 | symbol determines the syntax of the rest of the statement. If the |
| 2317 | symbol begins with a dot @samp{.} then the statement is an assembler |
| 2318 | directive: typically valid for any computer. If the symbol begins with |
| 2319 | a letter the statement is an assembly language @dfn{instruction}: it |
| 2320 | assembles into a machine language instruction. |
| 2321 | @ifset GENERIC |
| 2322 | Different versions of @command{@value{AS}} for different computers |
| 2323 | recognize different instructions. In fact, the same symbol may |
| 2324 | represent a different instruction in a different computer's assembly |
| 2325 | language.@refill |
| 2326 | @end ifset |
| 2327 | |
| 2328 | @cindex @code{:} (label) |
| 2329 | @cindex label (@code{:}) |
| 2330 | A label is a symbol immediately followed by a colon (@code{:}). |
| 2331 | Whitespace before a label or after a colon is permitted, but you may not |
| 2332 | have whitespace between a label's symbol and its colon. @xref{Labels}. |
| 2333 | |
| 2334 | @ifset HPPA |
| 2335 | For HPPA targets, labels need not be immediately followed by a colon, but |
| 2336 | the definition of a label must begin in column zero. This also implies that |
| 2337 | only one label may be defined on each line. |
| 2338 | @end ifset |
| 2339 | |
| 2340 | @smallexample |
| 2341 | label: .directive followed by something |
| 2342 | another_label: # This is an empty statement. |
| 2343 | instruction operand_1, operand_2, @dots{} |
| 2344 | @end smallexample |
| 2345 | |
| 2346 | @node Constants |
| 2347 | @section Constants |
| 2348 | |
| 2349 | @cindex constants |
| 2350 | A constant is a number, written so that its value is known by |
| 2351 | inspection, without knowing any context. Like this: |
| 2352 | @smallexample |
| 2353 | @group |
| 2354 | .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value. |
| 2355 | .ascii "Ring the bell\7" # A string constant. |
| 2356 | .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum. |
| 2357 | .float 0f-314159265358979323846264338327\ |
| 2358 | 95028841971.693993751E-40 # - pi, a flonum. |
| 2359 | @end group |
| 2360 | @end smallexample |
| 2361 | |
| 2362 | @menu |
| 2363 | * Characters:: Character Constants |
| 2364 | * Numbers:: Number Constants |
| 2365 | @end menu |
| 2366 | |
| 2367 | @node Characters |
| 2368 | @subsection Character Constants |
| 2369 | |
| 2370 | @cindex character constants |
| 2371 | @cindex constants, character |
| 2372 | There are two kinds of character constants. A @dfn{character} stands |
| 2373 | for one character in one byte and its value may be used in |
| 2374 | numeric expressions. String constants (properly called string |
| 2375 | @emph{literals}) are potentially many bytes and their values may not be |
| 2376 | used in arithmetic expressions. |
| 2377 | |
| 2378 | @menu |
| 2379 | * Strings:: Strings |
| 2380 | * Chars:: Characters |
| 2381 | @end menu |
| 2382 | |
| 2383 | @node Strings |
| 2384 | @subsubsection Strings |
| 2385 | |
| 2386 | @cindex string constants |
| 2387 | @cindex constants, string |
| 2388 | A @dfn{string} is written between double-quotes. It may contain |
| 2389 | double-quotes or null characters. The way to get special characters |
| 2390 | into a string is to @dfn{escape} these characters: precede them with |
| 2391 | a backslash @samp{\} character. For example @samp{\\} represents |
| 2392 | one backslash: the first @code{\} is an escape which tells |
| 2393 | @command{@value{AS}} to interpret the second character literally as a backslash |
| 2394 | (which prevents @command{@value{AS}} from recognizing the second @code{\} as an |
| 2395 | escape character). The complete list of escapes follows. |
| 2396 | |
| 2397 | @cindex escape codes, character |
| 2398 | @cindex character escape codes |
| 2399 | @table @kbd |
| 2400 | @c @item \a |
| 2401 | @c Mnemonic for ACKnowledge; for ASCII this is octal code 007. |
| 2402 | @c |
| 2403 | @cindex @code{\b} (backspace character) |
| 2404 | @cindex backspace (@code{\b}) |
| 2405 | @item \b |
| 2406 | Mnemonic for backspace; for ASCII this is octal code 010. |
| 2407 | |
| 2408 | @c @item \e |
| 2409 | @c Mnemonic for EOText; for ASCII this is octal code 004. |
| 2410 | @c |
| 2411 | @cindex @code{\f} (formfeed character) |
| 2412 | @cindex formfeed (@code{\f}) |
| 2413 | @item \f |
| 2414 | Mnemonic for FormFeed; for ASCII this is octal code 014. |
| 2415 | |
| 2416 | @cindex @code{\n} (newline character) |
| 2417 | @cindex newline (@code{\n}) |
| 2418 | @item \n |
| 2419 | Mnemonic for newline; for ASCII this is octal code 012. |
| 2420 | |
| 2421 | @c @item \p |
| 2422 | @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}. |
| 2423 | @c |
| 2424 | @cindex @code{\r} (carriage return character) |
| 2425 | @cindex carriage return (@code{\r}) |
| 2426 | @item \r |
| 2427 | Mnemonic for carriage-Return; for ASCII this is octal code 015. |
| 2428 | |
| 2429 | @c @item \s |
| 2430 | @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with |
| 2431 | @c other assemblers. |
| 2432 | @c |
| 2433 | @cindex @code{\t} (tab) |
| 2434 | @cindex tab (@code{\t}) |
| 2435 | @item \t |
| 2436 | Mnemonic for horizontal Tab; for ASCII this is octal code 011. |
| 2437 | |
| 2438 | @c @item \v |
| 2439 | @c Mnemonic for Vertical tab; for ASCII this is octal code 013. |
| 2440 | @c @item \x @var{digit} @var{digit} @var{digit} |
| 2441 | @c A hexadecimal character code. The numeric code is 3 hexadecimal digits. |
| 2442 | @c |
| 2443 | @cindex @code{\@var{ddd}} (octal character code) |
| 2444 | @cindex octal character code (@code{\@var{ddd}}) |
| 2445 | @item \ @var{digit} @var{digit} @var{digit} |
| 2446 | An octal character code. The numeric code is 3 octal digits. |
| 2447 | For compatibility with other Unix systems, 8 and 9 are accepted as digits: |
| 2448 | for example, @code{\008} has the value 010, and @code{\009} the value 011. |
| 2449 | |
| 2450 | @cindex @code{\@var{xd...}} (hex character code) |
| 2451 | @cindex hex character code (@code{\@var{xd...}}) |
| 2452 | @item \@code{x} @var{hex-digits...} |
| 2453 | A hex character code. All trailing hex digits are combined. Either upper or |
| 2454 | lower case @code{x} works. |
| 2455 | |
| 2456 | @cindex @code{\\} (@samp{\} character) |
| 2457 | @cindex backslash (@code{\\}) |
| 2458 | @item \\ |
| 2459 | Represents one @samp{\} character. |
| 2460 | |
| 2461 | @c @item \' |
| 2462 | @c Represents one @samp{'} (accent acute) character. |
| 2463 | @c This is needed in single character literals |
| 2464 | @c (@xref{Characters,,Character Constants}.) to represent |
| 2465 | @c a @samp{'}. |
| 2466 | @c |
| 2467 | @cindex @code{\"} (doublequote character) |
| 2468 | @cindex doublequote (@code{\"}) |
| 2469 | @item \" |
| 2470 | Represents one @samp{"} character. Needed in strings to represent |
| 2471 | this character, because an unescaped @samp{"} would end the string. |
| 2472 | |
| 2473 | @item \ @var{anything-else} |
| 2474 | Any other character when escaped by @kbd{\} gives a warning, but |
| 2475 | assembles as if the @samp{\} was not present. The idea is that if |
| 2476 | you used an escape sequence you clearly didn't want the literal |
| 2477 | interpretation of the following character. However @command{@value{AS}} has no |
| 2478 | other interpretation, so @command{@value{AS}} knows it is giving you the wrong |
| 2479 | code and warns you of the fact. |
| 2480 | @end table |
| 2481 | |
| 2482 | Which characters are escapable, and what those escapes represent, |
| 2483 | varies widely among assemblers. The current set is what we think |
| 2484 | the BSD 4.2 assembler recognizes, and is a subset of what most C |
| 2485 | compilers recognize. If you are in doubt, do not use an escape |
| 2486 | sequence. |
| 2487 | |
| 2488 | @node Chars |
| 2489 | @subsubsection Characters |
| 2490 | |
| 2491 | @cindex single character constant |
| 2492 | @cindex character, single |
| 2493 | @cindex constant, single character |
| 2494 | A single character may be written as a single quote immediately |
| 2495 | followed by that character. The same escapes apply to characters as |
| 2496 | to strings. So if you want to write the character backslash, you |
| 2497 | must write @kbd{'\\} where the first @code{\} escapes the second |
| 2498 | @code{\}. As you can see, the quote is an acute accent, not a |
| 2499 | grave accent. A newline |
| 2500 | @ifclear GENERIC |
| 2501 | @ifclear abnormal-separator |
| 2502 | (or semicolon @samp{;}) |
| 2503 | @end ifclear |
| 2504 | @ifset abnormal-separator |
| 2505 | @ifset H8 |
| 2506 | (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the |
| 2507 | Renesas SH) |
| 2508 | @end ifset |
| 2509 | @end ifset |
| 2510 | @end ifclear |
| 2511 | immediately following an acute accent is taken as a literal character |
| 2512 | and does not count as the end of a statement. The value of a character |
| 2513 | constant in a numeric expression is the machine's byte-wide code for |
| 2514 | that character. @command{@value{AS}} assumes your character code is ASCII: |
| 2515 | @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill |
| 2516 | |
| 2517 | @node Numbers |
| 2518 | @subsection Number Constants |
| 2519 | |
| 2520 | @cindex constants, number |
| 2521 | @cindex number constants |
| 2522 | @command{@value{AS}} distinguishes three kinds of numbers according to how they |
| 2523 | are stored in the target machine. @emph{Integers} are numbers that |
| 2524 | would fit into an @code{int} in the C language. @emph{Bignums} are |
| 2525 | integers, but they are stored in more than 32 bits. @emph{Flonums} |
| 2526 | are floating point numbers, described below. |
| 2527 | |
| 2528 | @menu |
| 2529 | * Integers:: Integers |
| 2530 | * Bignums:: Bignums |
| 2531 | * Flonums:: Flonums |
| 2532 | @ifclear GENERIC |
| 2533 | @ifset I960 |
| 2534 | * Bit Fields:: Bit Fields |
| 2535 | @end ifset |
| 2536 | @end ifclear |
| 2537 | @end menu |
| 2538 | |
| 2539 | @node Integers |
| 2540 | @subsubsection Integers |
| 2541 | @cindex integers |
| 2542 | @cindex constants, integer |
| 2543 | |
| 2544 | @cindex binary integers |
| 2545 | @cindex integers, binary |
| 2546 | A binary integer is @samp{0b} or @samp{0B} followed by zero or more of |
| 2547 | the binary digits @samp{01}. |
| 2548 | |
| 2549 | @cindex octal integers |
| 2550 | @cindex integers, octal |
| 2551 | An octal integer is @samp{0} followed by zero or more of the octal |
| 2552 | digits (@samp{01234567}). |
| 2553 | |
| 2554 | @cindex decimal integers |
| 2555 | @cindex integers, decimal |
| 2556 | A decimal integer starts with a non-zero digit followed by zero or |
| 2557 | more digits (@samp{0123456789}). |
| 2558 | |
| 2559 | @cindex hexadecimal integers |
| 2560 | @cindex integers, hexadecimal |
| 2561 | A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or |
| 2562 | more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}. |
| 2563 | |
| 2564 | Integers have the usual values. To denote a negative integer, use |
| 2565 | the prefix operator @samp{-} discussed under expressions |
| 2566 | (@pxref{Prefix Ops,,Prefix Operators}). |
| 2567 | |
| 2568 | @node Bignums |
| 2569 | @subsubsection Bignums |
| 2570 | |
| 2571 | @cindex bignums |
| 2572 | @cindex constants, bignum |
| 2573 | A @dfn{bignum} has the same syntax and semantics as an integer |
| 2574 | except that the number (or its negative) takes more than 32 bits to |
| 2575 | represent in binary. The distinction is made because in some places |
| 2576 | integers are permitted while bignums are not. |
| 2577 | |
| 2578 | @node Flonums |
| 2579 | @subsubsection Flonums |
| 2580 | @cindex flonums |
| 2581 | @cindex floating point numbers |
| 2582 | @cindex constants, floating point |
| 2583 | |
| 2584 | @cindex precision, floating point |
| 2585 | A @dfn{flonum} represents a floating point number. The translation is |
| 2586 | indirect: a decimal floating point number from the text is converted by |
| 2587 | @command{@value{AS}} to a generic binary floating point number of more than |
| 2588 | sufficient precision. This generic floating point number is converted |
| 2589 | to a particular computer's floating point format (or formats) by a |
| 2590 | portion of @command{@value{AS}} specialized to that computer. |
| 2591 | |
| 2592 | A flonum is written by writing (in order) |
| 2593 | @itemize @bullet |
| 2594 | @item |
| 2595 | The digit @samp{0}. |
| 2596 | @ifset HPPA |
| 2597 | (@samp{0} is optional on the HPPA.) |
| 2598 | @end ifset |
| 2599 | |
| 2600 | @item |
| 2601 | A letter, to tell @command{@value{AS}} the rest of the number is a flonum. |
| 2602 | @ifset GENERIC |
| 2603 | @kbd{e} is recommended. Case is not important. |
| 2604 | @ignore |
| 2605 | @c FIXME: verify if flonum syntax really this vague for most cases |
| 2606 | (Any otherwise illegal letter works here, but that might be changed. Vax BSD |
| 2607 | 4.2 assembler seems to allow any of @samp{defghDEFGH}.) |
| 2608 | @end ignore |
| 2609 | |
| 2610 | On the H8/300, Renesas / SuperH SH, |
| 2611 | and AMD 29K architectures, the letter must be |
| 2612 | one of the letters @samp{DFPRSX} (in upper or lower case). |
| 2613 | |
| 2614 | On the ARC, the letter must be one of the letters @samp{DFRS} |
| 2615 | (in upper or lower case). |
| 2616 | |
| 2617 | On the Intel 960 architecture, the letter must be |
| 2618 | one of the letters @samp{DFT} (in upper or lower case). |
| 2619 | |
| 2620 | On the HPPA architecture, the letter must be @samp{E} (upper case only). |
| 2621 | @end ifset |
| 2622 | @ifclear GENERIC |
| 2623 | @ifset ARC |
| 2624 | One of the letters @samp{DFRS} (in upper or lower case). |
| 2625 | @end ifset |
| 2626 | @ifset H8 |
| 2627 | One of the letters @samp{DFPRSX} (in upper or lower case). |
| 2628 | @end ifset |
| 2629 | @ifset HPPA |
| 2630 | The letter @samp{E} (upper case only). |
| 2631 | @end ifset |
| 2632 | @ifset I960 |
| 2633 | One of the letters @samp{DFT} (in upper or lower case). |
| 2634 | @end ifset |
| 2635 | @end ifclear |
| 2636 | |
| 2637 | @item |
| 2638 | An optional sign: either @samp{+} or @samp{-}. |
| 2639 | |
| 2640 | @item |
| 2641 | An optional @dfn{integer part}: zero or more decimal digits. |
| 2642 | |
| 2643 | @item |
| 2644 | An optional @dfn{fractional part}: @samp{.} followed by zero |
| 2645 | or more decimal digits. |
| 2646 | |
| 2647 | @item |
| 2648 | An optional exponent, consisting of: |
| 2649 | |
| 2650 | @itemize @bullet |
| 2651 | @item |
| 2652 | An @samp{E} or @samp{e}. |
| 2653 | @c I can't find a config where "EXP_CHARS" is other than 'eE', but in |
| 2654 | @c principle this can perfectly well be different on different targets. |
| 2655 | @item |
| 2656 | Optional sign: either @samp{+} or @samp{-}. |
| 2657 | @item |
| 2658 | One or more decimal digits. |
| 2659 | @end itemize |
| 2660 | |
| 2661 | @end itemize |
| 2662 | |
| 2663 | At least one of the integer part or the fractional part must be |
| 2664 | present. The floating point number has the usual base-10 value. |
| 2665 | |
| 2666 | @command{@value{AS}} does all processing using integers. Flonums are computed |
| 2667 | independently of any floating point hardware in the computer running |
| 2668 | @command{@value{AS}}. |
| 2669 | |
| 2670 | @ifclear GENERIC |
| 2671 | @ifset I960 |
| 2672 | @c Bit fields are written as a general facility but are also controlled |
| 2673 | @c by a conditional-compilation flag---which is as of now (21mar91) |
| 2674 | @c turned on only by the i960 config of GAS. |
| 2675 | @node Bit Fields |
| 2676 | @subsubsection Bit Fields |
| 2677 | |
| 2678 | @cindex bit fields |
| 2679 | @cindex constants, bit field |
| 2680 | You can also define numeric constants as @dfn{bit fields}. |
| 2681 | specify two numbers separated by a colon--- |
| 2682 | @example |
| 2683 | @var{mask}:@var{value} |
| 2684 | @end example |
| 2685 | @noindent |
| 2686 | @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and |
| 2687 | @var{value}. |
| 2688 | |
| 2689 | The resulting number is then packed |
| 2690 | @ifset GENERIC |
| 2691 | @c this conditional paren in case bit fields turned on elsewhere than 960 |
| 2692 | (in host-dependent byte order) |
| 2693 | @end ifset |
| 2694 | into a field whose width depends on which assembler directive has the |
| 2695 | bit-field as its argument. Overflow (a result from the bitwise and |
| 2696 | requiring more binary digits to represent) is not an error; instead, |
| 2697 | more constants are generated, of the specified width, beginning with the |
| 2698 | least significant digits.@refill |
| 2699 | |
| 2700 | The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long}, |
| 2701 | @code{.short}, and @code{.word} accept bit-field arguments. |
| 2702 | @end ifset |
| 2703 | @end ifclear |
| 2704 | |
| 2705 | @node Sections |
| 2706 | @chapter Sections and Relocation |
| 2707 | @cindex sections |
| 2708 | @cindex relocation |
| 2709 | |
| 2710 | @menu |
| 2711 | * Secs Background:: Background |
| 2712 | * Ld Sections:: Linker Sections |
| 2713 | * As Sections:: Assembler Internal Sections |
| 2714 | * Sub-Sections:: Sub-Sections |
| 2715 | * bss:: bss Section |
| 2716 | @end menu |
| 2717 | |
| 2718 | @node Secs Background |
| 2719 | @section Background |
| 2720 | |
| 2721 | Roughly, a section is a range of addresses, with no gaps; all data |
| 2722 | ``in'' those addresses is treated the same for some particular purpose. |
| 2723 | For example there may be a ``read only'' section. |
| 2724 | |
| 2725 | @cindex linker, and assembler |
| 2726 | @cindex assembler, and linker |
| 2727 | The linker @code{@value{LD}} reads many object files (partial programs) and |
| 2728 | combines their contents to form a runnable program. When @command{@value{AS}} |
| 2729 | emits an object file, the partial program is assumed to start at address 0. |
| 2730 | @code{@value{LD}} assigns the final addresses for the partial program, so that |
| 2731 | different partial programs do not overlap. This is actually an |
| 2732 | oversimplification, but it suffices to explain how @command{@value{AS}} uses |
| 2733 | sections. |
| 2734 | |
| 2735 | @code{@value{LD}} moves blocks of bytes of your program to their run-time |
| 2736 | addresses. These blocks slide to their run-time addresses as rigid |
| 2737 | units; their length does not change and neither does the order of bytes |
| 2738 | within them. Such a rigid unit is called a @emph{section}. Assigning |
| 2739 | run-time addresses to sections is called @dfn{relocation}. It includes |
| 2740 | the task of adjusting mentions of object-file addresses so they refer to |
| 2741 | the proper run-time addresses. |
| 2742 | @ifset H8 |
| 2743 | For the H8/300, and for the Renesas / SuperH SH, |
| 2744 | @command{@value{AS}} pads sections if needed to |
| 2745 | ensure they end on a word (sixteen bit) boundary. |
| 2746 | @end ifset |
| 2747 | |
| 2748 | @cindex standard assembler sections |
| 2749 | An object file written by @command{@value{AS}} has at least three sections, any |
| 2750 | of which may be empty. These are named @dfn{text}, @dfn{data} and |
| 2751 | @dfn{bss} sections. |
| 2752 | |
| 2753 | @ifset COFF-ELF |
| 2754 | @ifset GENERIC |
| 2755 | When it generates COFF or ELF output, |
| 2756 | @end ifset |
| 2757 | @command{@value{AS}} can also generate whatever other named sections you specify |
| 2758 | using the @samp{.section} directive (@pxref{Section,,@code{.section}}). |
| 2759 | If you do not use any directives that place output in the @samp{.text} |
| 2760 | or @samp{.data} sections, these sections still exist, but are empty. |
| 2761 | @end ifset |
| 2762 | |
| 2763 | @ifset HPPA |
| 2764 | @ifset GENERIC |
| 2765 | When @command{@value{AS}} generates SOM or ELF output for the HPPA, |
| 2766 | @end ifset |
| 2767 | @command{@value{AS}} can also generate whatever other named sections you |
| 2768 | specify using the @samp{.space} and @samp{.subspace} directives. See |
| 2769 | @cite{HP9000 Series 800 Assembly Language Reference Manual} |
| 2770 | (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace} |
| 2771 | assembler directives. |
| 2772 | |
| 2773 | @ifset SOM |
| 2774 | Additionally, @command{@value{AS}} uses different names for the standard |
| 2775 | text, data, and bss sections when generating SOM output. Program text |
| 2776 | is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and |
| 2777 | BSS into @samp{$BSS$}. |
| 2778 | @end ifset |
| 2779 | @end ifset |
| 2780 | |
| 2781 | Within the object file, the text section starts at address @code{0}, the |
| 2782 | data section follows, and the bss section follows the data section. |
| 2783 | |
| 2784 | @ifset HPPA |
| 2785 | When generating either SOM or ELF output files on the HPPA, the text |
| 2786 | section starts at address @code{0}, the data section at address |
| 2787 | @code{0x4000000}, and the bss section follows the data section. |
| 2788 | @end ifset |
| 2789 | |
| 2790 | To let @code{@value{LD}} know which data changes when the sections are |
| 2791 | relocated, and how to change that data, @command{@value{AS}} also writes to the |
| 2792 | object file details of the relocation needed. To perform relocation |
| 2793 | @code{@value{LD}} must know, each time an address in the object |
| 2794 | file is mentioned: |
| 2795 | @itemize @bullet |
| 2796 | @item |
| 2797 | Where in the object file is the beginning of this reference to |
| 2798 | an address? |
| 2799 | @item |
| 2800 | How long (in bytes) is this reference? |
| 2801 | @item |
| 2802 | Which section does the address refer to? What is the numeric value of |
| 2803 | @display |
| 2804 | (@var{address}) @minus{} (@var{start-address of section})? |
| 2805 | @end display |
| 2806 | @item |
| 2807 | Is the reference to an address ``Program-Counter relative''? |
| 2808 | @end itemize |
| 2809 | |
| 2810 | @cindex addresses, format of |
| 2811 | @cindex section-relative addressing |
| 2812 | In fact, every address @command{@value{AS}} ever uses is expressed as |
| 2813 | @display |
| 2814 | (@var{section}) + (@var{offset into section}) |
| 2815 | @end display |
| 2816 | @noindent |
| 2817 | Further, most expressions @command{@value{AS}} computes have this section-relative |
| 2818 | nature. |
| 2819 | @ifset SOM |
| 2820 | (For some object formats, such as SOM for the HPPA, some expressions are |
| 2821 | symbol-relative instead.) |
| 2822 | @end ifset |
| 2823 | |
| 2824 | In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset |
| 2825 | @var{N} into section @var{secname}.'' |
| 2826 | |
| 2827 | Apart from text, data and bss sections you need to know about the |
| 2828 | @dfn{absolute} section. When @code{@value{LD}} mixes partial programs, |
| 2829 | addresses in the absolute section remain unchanged. For example, address |
| 2830 | @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by |
| 2831 | @code{@value{LD}}. Although the linker never arranges two partial programs' |
| 2832 | data sections with overlapping addresses after linking, @emph{by definition} |
| 2833 | their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one |
| 2834 | part of a program is always the same address when the program is running as |
| 2835 | address @code{@{absolute@ 239@}} in any other part of the program. |
| 2836 | |
| 2837 | The idea of sections is extended to the @dfn{undefined} section. Any |
| 2838 | address whose section is unknown at assembly time is by definition |
| 2839 | rendered @{undefined @var{U}@}---where @var{U} is filled in later. |
| 2840 | Since numbers are always defined, the only way to generate an undefined |
| 2841 | address is to mention an undefined symbol. A reference to a named |
| 2842 | common block would be such a symbol: its value is unknown at assembly |
| 2843 | time so it has section @emph{undefined}. |
| 2844 | |
| 2845 | By analogy the word @emph{section} is used to describe groups of sections in |
| 2846 | the linked program. @code{@value{LD}} puts all partial programs' text |
| 2847 | sections in contiguous addresses in the linked program. It is |
| 2848 | customary to refer to the @emph{text section} of a program, meaning all |
| 2849 | the addresses of all partial programs' text sections. Likewise for |
| 2850 | data and bss sections. |
| 2851 | |
| 2852 | Some sections are manipulated by @code{@value{LD}}; others are invented for |
| 2853 | use of @command{@value{AS}} and have no meaning except during assembly. |
| 2854 | |
| 2855 | @node Ld Sections |
| 2856 | @section Linker Sections |
| 2857 | @code{@value{LD}} deals with just four kinds of sections, summarized below. |
| 2858 | |
| 2859 | @table @strong |
| 2860 | |
| 2861 | @ifset COFF-ELF |
| 2862 | @cindex named sections |
| 2863 | @cindex sections, named |
| 2864 | @item named sections |
| 2865 | @end ifset |
| 2866 | @ifset aout-bout |
| 2867 | @cindex text section |
| 2868 | @cindex data section |
| 2869 | @itemx text section |
| 2870 | @itemx data section |
| 2871 | @end ifset |
| 2872 | These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as |
| 2873 | separate but equal sections. Anything you can say of one section is |
| 2874 | true of another. |
| 2875 | @c @ifset aout-bout |
| 2876 | When the program is running, however, it is |
| 2877 | customary for the text section to be unalterable. The |
| 2878 | text section is often shared among processes: it contains |
| 2879 | instructions, constants and the like. The data section of a running |
| 2880 | program is usually alterable: for example, C variables would be stored |
| 2881 | in the data section. |
| 2882 | @c @end ifset |
| 2883 | |
| 2884 | @cindex bss section |
| 2885 | @item bss section |
| 2886 | This section contains zeroed bytes when your program begins running. It |
| 2887 | is used to hold uninitialized variables or common storage. The length of |
| 2888 | each partial program's bss section is important, but because it starts |
| 2889 | out containing zeroed bytes there is no need to store explicit zero |
| 2890 | bytes in the object file. The bss section was invented to eliminate |
| 2891 | those explicit zeros from object files. |
| 2892 | |
| 2893 | @cindex absolute section |
| 2894 | @item absolute section |
| 2895 | Address 0 of this section is always ``relocated'' to runtime address 0. |
| 2896 | This is useful if you want to refer to an address that @code{@value{LD}} must |
| 2897 | not change when relocating. In this sense we speak of absolute |
| 2898 | addresses being ``unrelocatable'': they do not change during relocation. |
| 2899 | |
| 2900 | @cindex undefined section |
| 2901 | @item undefined section |
| 2902 | This ``section'' is a catch-all for address references to objects not in |
| 2903 | the preceding sections. |
| 2904 | @c FIXME: ref to some other doc on obj-file formats could go here. |
| 2905 | @end table |
| 2906 | |
| 2907 | @cindex relocation example |
| 2908 | An idealized example of three relocatable sections follows. |
| 2909 | @ifset COFF-ELF |
| 2910 | The example uses the traditional section names @samp{.text} and @samp{.data}. |
| 2911 | @end ifset |
| 2912 | Memory addresses are on the horizontal axis. |
| 2913 | |
| 2914 | @c TEXI2ROFF-KILL |
| 2915 | @ifnottex |
| 2916 | @c END TEXI2ROFF-KILL |
| 2917 | @smallexample |
| 2918 | +-----+----+--+ |
| 2919 | partial program # 1: |ttttt|dddd|00| |
| 2920 | +-----+----+--+ |
| 2921 | |
| 2922 | text data bss |
| 2923 | seg. seg. seg. |
| 2924 | |
| 2925 | +---+---+---+ |
| 2926 | partial program # 2: |TTT|DDD|000| |
| 2927 | +---+---+---+ |
| 2928 | |
| 2929 | +--+---+-----+--+----+---+-----+~~ |
| 2930 | linked program: | |TTT|ttttt| |dddd|DDD|00000| |
| 2931 | +--+---+-----+--+----+---+-----+~~ |
| 2932 | |
| 2933 | addresses: 0 @dots{} |
| 2934 | @end smallexample |
| 2935 | @c TEXI2ROFF-KILL |
| 2936 | @end ifnottex |
| 2937 | @need 5000 |
| 2938 | @tex |
| 2939 | \bigskip |
| 2940 | \line{\it Partial program \#1: \hfil} |
| 2941 | \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil} |
| 2942 | \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil} |
| 2943 | |
| 2944 | \line{\it Partial program \#2: \hfil} |
| 2945 | \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil} |
| 2946 | \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil} |
| 2947 | |
| 2948 | \line{\it linked program: \hfil} |
| 2949 | \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil} |
| 2950 | \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt |
| 2951 | ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt |
| 2952 | DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil} |
| 2953 | |
| 2954 | \line{\it addresses: \hfil} |
| 2955 | \line{0\dots\hfil} |
| 2956 | |
| 2957 | @end tex |
| 2958 | @c END TEXI2ROFF-KILL |
| 2959 | |
| 2960 | @node As Sections |
| 2961 | @section Assembler Internal Sections |
| 2962 | |
| 2963 | @cindex internal assembler sections |
| 2964 | @cindex sections in messages, internal |
| 2965 | These sections are meant only for the internal use of @command{@value{AS}}. They |
| 2966 | have no meaning at run-time. You do not really need to know about these |
| 2967 | sections for most purposes; but they can be mentioned in @command{@value{AS}} |
| 2968 | warning messages, so it might be helpful to have an idea of their |
| 2969 | meanings to @command{@value{AS}}. These sections are used to permit the |
| 2970 | value of every expression in your assembly language program to be a |
| 2971 | section-relative address. |
| 2972 | |
| 2973 | @table @b |
| 2974 | @cindex assembler internal logic error |
| 2975 | @item ASSEMBLER-INTERNAL-LOGIC-ERROR! |
| 2976 | An internal assembler logic error has been found. This means there is a |
| 2977 | bug in the assembler. |
| 2978 | |
| 2979 | @cindex expr (internal section) |
| 2980 | @item expr section |
| 2981 | The assembler stores complex expression internally as combinations of |
| 2982 | symbols. When it needs to represent an expression as a symbol, it puts |
| 2983 | it in the expr section. |
| 2984 | @c FIXME item debug |
| 2985 | @c FIXME item transfer[t] vector preload |
| 2986 | @c FIXME item transfer[t] vector postload |
| 2987 | @c FIXME item register |
| 2988 | @end table |
| 2989 | |
| 2990 | @node Sub-Sections |
| 2991 | @section Sub-Sections |
| 2992 | |
| 2993 | @cindex numbered subsections |
| 2994 | @cindex grouping data |
| 2995 | @ifset aout-bout |
| 2996 | Assembled bytes |
| 2997 | @ifset COFF-ELF |
| 2998 | conventionally |
| 2999 | @end ifset |
| 3000 | fall into two sections: text and data. |
| 3001 | @end ifset |
| 3002 | You may have separate groups of |
| 3003 | @ifset GENERIC |
| 3004 | data in named sections |
| 3005 | @end ifset |
| 3006 | @ifclear GENERIC |
| 3007 | @ifclear aout-bout |
| 3008 | data in named sections |
| 3009 | @end ifclear |
| 3010 | @ifset aout-bout |
| 3011 | text or data |
| 3012 | @end ifset |
| 3013 | @end ifclear |
| 3014 | that you want to end up near to each other in the object file, even though they |
| 3015 | are not contiguous in the assembler source. @command{@value{AS}} allows you to |
| 3016 | use @dfn{subsections} for this purpose. Within each section, there can be |
| 3017 | numbered subsections with values from 0 to 8192. Objects assembled into the |
| 3018 | same subsection go into the object file together with other objects in the same |
| 3019 | subsection. For example, a compiler might want to store constants in the text |
| 3020 | section, but might not want to have them interspersed with the program being |
| 3021 | assembled. In this case, the compiler could issue a @samp{.text 0} before each |
| 3022 | section of code being output, and a @samp{.text 1} before each group of |
| 3023 | constants being output. |
| 3024 | |
| 3025 | Subsections are optional. If you do not use subsections, everything |
| 3026 | goes in subsection number zero. |
| 3027 | |
| 3028 | @ifset GENERIC |
| 3029 | Each subsection is zero-padded up to a multiple of four bytes. |
| 3030 | (Subsections may be padded a different amount on different flavors |
| 3031 | of @command{@value{AS}}.) |
| 3032 | @end ifset |
| 3033 | @ifclear GENERIC |
| 3034 | @ifset H8 |
| 3035 | On the H8/300 platform, each subsection is zero-padded to a word |
| 3036 | boundary (two bytes). |
| 3037 | The same is true on the Renesas SH. |
| 3038 | @end ifset |
| 3039 | @ifset I960 |
| 3040 | @c FIXME section padding (alignment)? |
| 3041 | @c Rich Pixley says padding here depends on target obj code format; that |
| 3042 | @c doesn't seem particularly useful to say without further elaboration, |
| 3043 | @c so for now I say nothing about it. If this is a generic BFD issue, |
| 3044 | @c these paragraphs might need to vanish from this manual, and be |
| 3045 | @c discussed in BFD chapter of binutils (or some such). |
| 3046 | @end ifset |
| 3047 | @end ifclear |
| 3048 | |
| 3049 | Subsections appear in your object file in numeric order, lowest numbered |
| 3050 | to highest. (All this to be compatible with other people's assemblers.) |
| 3051 | The object file contains no representation of subsections; @code{@value{LD}} and |
| 3052 | other programs that manipulate object files see no trace of them. |
| 3053 | They just see all your text subsections as a text section, and all your |
| 3054 | data subsections as a data section. |
| 3055 | |
| 3056 | To specify which subsection you want subsequent statements assembled |
| 3057 | into, use a numeric argument to specify it, in a @samp{.text |
| 3058 | @var{expression}} or a @samp{.data @var{expression}} statement. |
| 3059 | @ifset COFF |
| 3060 | @ifset GENERIC |
| 3061 | When generating COFF output, you |
| 3062 | @end ifset |
| 3063 | @ifclear GENERIC |
| 3064 | You |
| 3065 | @end ifclear |
| 3066 | can also use an extra subsection |
| 3067 | argument with arbitrary named sections: @samp{.section @var{name}, |
| 3068 | @var{expression}}. |
| 3069 | @end ifset |
| 3070 | @ifset ELF |
| 3071 | @ifset GENERIC |
| 3072 | When generating ELF output, you |
| 3073 | @end ifset |
| 3074 | @ifclear GENERIC |
| 3075 | You |
| 3076 | @end ifclear |
| 3077 | can also use the @code{.subsection} directive (@pxref{SubSection}) |
| 3078 | to specify a subsection: @samp{.subsection @var{expression}}. |
| 3079 | @end ifset |
| 3080 | @var{Expression} should be an absolute expression. |
| 3081 | (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0} |
| 3082 | is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly |
| 3083 | begins in @code{text 0}. For instance: |
| 3084 | @smallexample |
| 3085 | .text 0 # The default subsection is text 0 anyway. |
| 3086 | .ascii "This lives in the first text subsection. *" |
| 3087 | .text 1 |
| 3088 | .ascii "But this lives in the second text subsection." |
| 3089 | .data 0 |
| 3090 | .ascii "This lives in the data section," |
| 3091 | .ascii "in the first data subsection." |
| 3092 | .text 0 |
| 3093 | .ascii "This lives in the first text section," |
| 3094 | .ascii "immediately following the asterisk (*)." |
| 3095 | @end smallexample |
| 3096 | |
| 3097 | Each section has a @dfn{location counter} incremented by one for every byte |
| 3098 | assembled into that section. Because subsections are merely a convenience |
| 3099 | restricted to @command{@value{AS}} there is no concept of a subsection location |
| 3100 | counter. There is no way to directly manipulate a location counter---but the |
| 3101 | @code{.align} directive changes it, and any label definition captures its |
| 3102 | current value. The location counter of the section where statements are being |
| 3103 | assembled is said to be the @dfn{active} location counter. |
| 3104 | |
| 3105 | @node bss |
| 3106 | @section bss Section |
| 3107 | |
| 3108 | @cindex bss section |
| 3109 | @cindex common variable storage |
| 3110 | The bss section is used for local common variable storage. |
| 3111 | You may allocate address space in the bss section, but you may |
| 3112 | not dictate data to load into it before your program executes. When |
| 3113 | your program starts running, all the contents of the bss |
| 3114 | section are zeroed bytes. |
| 3115 | |
| 3116 | The @code{.lcomm} pseudo-op defines a symbol in the bss section; see |
| 3117 | @ref{Lcomm,,@code{.lcomm}}. |
| 3118 | |
| 3119 | The @code{.comm} pseudo-op may be used to declare a common symbol, which is |
| 3120 | another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}. |
| 3121 | |
| 3122 | @ifset GENERIC |
| 3123 | When assembling for a target which supports multiple sections, such as ELF or |
| 3124 | COFF, you may switch into the @code{.bss} section and define symbols as usual; |
| 3125 | see @ref{Section,,@code{.section}}. You may only assemble zero values into the |
| 3126 | section. Typically the section will only contain symbol definitions and |
| 3127 | @code{.skip} directives (@pxref{Skip,,@code{.skip}}). |
| 3128 | @end ifset |
| 3129 | |
| 3130 | @node Symbols |
| 3131 | @chapter Symbols |
| 3132 | |
| 3133 | @cindex symbols |
| 3134 | Symbols are a central concept: the programmer uses symbols to name |
| 3135 | things, the linker uses symbols to link, and the debugger uses symbols |
| 3136 | to debug. |
| 3137 | |
| 3138 | @quotation |
| 3139 | @cindex debuggers, and symbol order |
| 3140 | @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in |
| 3141 | the same order they were declared. This may break some debuggers. |
| 3142 | @end quotation |
| 3143 | |
| 3144 | @menu |
| 3145 | * Labels:: Labels |
| 3146 | * Setting Symbols:: Giving Symbols Other Values |
| 3147 | * Symbol Names:: Symbol Names |
| 3148 | * Dot:: The Special Dot Symbol |
| 3149 | * Symbol Attributes:: Symbol Attributes |
| 3150 | @end menu |
| 3151 | |
| 3152 | @node Labels |
| 3153 | @section Labels |
| 3154 | |
| 3155 | @cindex labels |
| 3156 | A @dfn{label} is written as a symbol immediately followed by a colon |
| 3157 | @samp{:}. The symbol then represents the current value of the |
| 3158 | active location counter, and is, for example, a suitable instruction |
| 3159 | operand. You are warned if you use the same symbol to represent two |
| 3160 | different locations: the first definition overrides any other |
| 3161 | definitions. |
| 3162 | |
| 3163 | @ifset HPPA |
| 3164 | On the HPPA, the usual form for a label need not be immediately followed by a |
| 3165 | colon, but instead must start in column zero. Only one label may be defined on |
| 3166 | a single line. To work around this, the HPPA version of @command{@value{AS}} also |
| 3167 | provides a special directive @code{.label} for defining labels more flexibly. |
| 3168 | @end ifset |
| 3169 | |
| 3170 | @node Setting Symbols |
| 3171 | @section Giving Symbols Other Values |
| 3172 | |
| 3173 | @cindex assigning values to symbols |
| 3174 | @cindex symbol values, assigning |
| 3175 | A symbol can be given an arbitrary value by writing a symbol, followed |
| 3176 | by an equals sign @samp{=}, followed by an expression |
| 3177 | (@pxref{Expressions}). This is equivalent to using the @code{.set} |
| 3178 | directive. @xref{Set,,@code{.set}}. In the same way, using a double |
| 3179 | equals sign @samp{=}@samp{=} here represents an equivalent of the |
| 3180 | @code{.eqv} directive. @xref{Eqv,,@code{.eqv}}. |
| 3181 | |
| 3182 | @node Symbol Names |
| 3183 | @section Symbol Names |
| 3184 | |
| 3185 | @cindex symbol names |
| 3186 | @cindex names, symbol |
| 3187 | @ifclear SPECIAL-SYMS |
| 3188 | Symbol names begin with a letter or with one of @samp{._}. On most |
| 3189 | machines, you can also use @code{$} in symbol names; exceptions are |
| 3190 | noted in @ref{Machine Dependencies}. That character may be followed by any |
| 3191 | string of digits, letters, dollar signs (unless otherwise noted in |
| 3192 | @ref{Machine Dependencies}), and underscores. |
| 3193 | @end ifclear |
| 3194 | @ifset SPECIAL-SYMS |
| 3195 | @ifset H8 |
| 3196 | Symbol names begin with a letter or with one of @samp{._}. On the |
| 3197 | Renesas SH you can also use @code{$} in symbol names. That |
| 3198 | character may be followed by any string of digits, letters, dollar signs (save |
| 3199 | on the H8/300), and underscores. |
| 3200 | @end ifset |
| 3201 | @end ifset |
| 3202 | |
| 3203 | Case of letters is significant: @code{foo} is a different symbol name |
| 3204 | than @code{Foo}. |
| 3205 | |
| 3206 | Each symbol has exactly one name. Each name in an assembly language program |
| 3207 | refers to exactly one symbol. You may use that symbol name any number of times |
| 3208 | in a program. |
| 3209 | |
| 3210 | @subheading Local Symbol Names |
| 3211 | |
| 3212 | @cindex local symbol names |
| 3213 | @cindex symbol names, local |
| 3214 | @cindex temporary symbol names |
| 3215 | @cindex symbol names, temporary |
| 3216 | Local symbols help compilers and programmers use names temporarily. |
| 3217 | They create symbols which are guaranteed to be unique over the entire scope of |
| 3218 | the input source code and which can be referred to by a simple notation. |
| 3219 | To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N} |
| 3220 | represents any positive integer). To refer to the most recent previous |
| 3221 | definition of that symbol write @samp{@b{N}b}, using the same number as when |
| 3222 | you defined the label. To refer to the next definition of a local label, write |
| 3223 | @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands |
| 3224 | for ``forwards''. |
| 3225 | |
| 3226 | There is no restriction on how you can use these labels, and you can reuse them |
| 3227 | too. So that it is possible to repeatedly define the same local label (using |
| 3228 | the same number @samp{@b{N}}), although you can only refer to the most recently |
| 3229 | defined local label of that number (for a backwards reference) or the next |
| 3230 | definition of a specific local label for a forward reference. It is also worth |
| 3231 | noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are |
| 3232 | implemented in a slightly more efficient manner than the others. |
| 3233 | |
| 3234 | Here is an example: |
| 3235 | |
| 3236 | @smallexample |
| 3237 | 1: branch 1f |
| 3238 | 2: branch 1b |
| 3239 | 1: branch 2f |
| 3240 | 2: branch 1b |
| 3241 | @end smallexample |
| 3242 | |
| 3243 | Which is the equivalent of: |
| 3244 | |
| 3245 | @smallexample |
| 3246 | label_1: branch label_3 |
| 3247 | label_2: branch label_1 |
| 3248 | label_3: branch label_4 |
| 3249 | label_4: branch label_3 |
| 3250 | @end smallexample |
| 3251 | |
| 3252 | Local symbol names are only a notational device. They are immediately |
| 3253 | transformed into more conventional symbol names before the assembler uses them. |
| 3254 | The symbol names stored in the symbol table, appearing in error messages and |
| 3255 | optionally emitted to the object file. The names are constructed using these |
| 3256 | parts: |
| 3257 | |
| 3258 | @table @code |
| 3259 | @item L |
| 3260 | All local labels begin with @samp{L}. Normally both @command{@value{AS}} and |
| 3261 | @code{@value{LD}} forget symbols that start with @samp{L}. These labels are |
| 3262 | used for symbols you are never intended to see. If you use the |
| 3263 | @samp{-L} option then @command{@value{AS}} retains these symbols in the |
| 3264 | object file. If you also instruct @code{@value{LD}} to retain these symbols, |
| 3265 | you may use them in debugging. |
| 3266 | |
| 3267 | @item @var{number} |
| 3268 | This is the number that was used in the local label definition. So if the |
| 3269 | label is written @samp{55:} then the number is @samp{55}. |
| 3270 | |
| 3271 | @item @kbd{C-B} |
| 3272 | This unusual character is included so you do not accidentally invent a symbol |
| 3273 | of the same name. The character has ASCII value of @samp{\002} (control-B). |
| 3274 | |
| 3275 | @item @emph{ordinal number} |
| 3276 | This is a serial number to keep the labels distinct. The first definition of |
| 3277 | @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the |
| 3278 | number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets |
| 3279 | the number @samp{1} and its 15th defintion gets @samp{15} as well. |
| 3280 | @end table |
| 3281 | |
| 3282 | So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th |
| 3283 | @code{3:} is named @code{L3@kbd{C-B}44}. |
| 3284 | |
| 3285 | @subheading Dollar Local Labels |
| 3286 | @cindex dollar local symbols |
| 3287 | |
| 3288 | @code{@value{AS}} also supports an even more local form of local labels called |
| 3289 | dollar labels. These labels go out of scope (ie they become undefined) as soon |
| 3290 | as a non-local label is defined. Thus they remain valid for only a small |
| 3291 | region of the input source code. Normal local labels, by contrast, remain in |
| 3292 | scope for the entire file, or until they are redefined by another occurrence of |
| 3293 | the same local label. |
| 3294 | |
| 3295 | Dollar labels are defined in exactly the same way as ordinary local labels, |
| 3296 | except that instead of being terminated by a colon, they are terminated by a |
| 3297 | dollar sign. eg @samp{@b{55$}}. |
| 3298 | |
| 3299 | They can also be distinguished from ordinary local labels by their transformed |
| 3300 | name which uses ASCII character @samp{\001} (control-A) as the magic character |
| 3301 | to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$} |
| 3302 | is named @samp{L6@kbd{C-A}5}. |
| 3303 | |
| 3304 | @node Dot |
| 3305 | @section The Special Dot Symbol |
| 3306 | |
| 3307 | @cindex dot (symbol) |
| 3308 | @cindex @code{.} (symbol) |
| 3309 | @cindex current address |
| 3310 | @cindex location counter |
| 3311 | The special symbol @samp{.} refers to the current address that |
| 3312 | @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin: |
| 3313 | .long .} defines @code{melvin} to contain its own address. |
| 3314 | Assigning a value to @code{.} is treated the same as a @code{.org} |
| 3315 | directive. Thus, the expression @samp{.=.+4} is the same as saying |
| 3316 | @ifclear no-space-dir |
| 3317 | @samp{.space 4}. |
| 3318 | @end ifclear |
| 3319 | |
| 3320 | @node Symbol Attributes |
| 3321 | @section Symbol Attributes |
| 3322 | |
| 3323 | @cindex symbol attributes |
| 3324 | @cindex attributes, symbol |
| 3325 | Every symbol has, as well as its name, the attributes ``Value'' and |
| 3326 | ``Type''. Depending on output format, symbols can also have auxiliary |
| 3327 | attributes. |
| 3328 | @ifset INTERNALS |
| 3329 | The detailed definitions are in @file{a.out.h}. |
| 3330 | @end ifset |
| 3331 | |
| 3332 | If you use a symbol without defining it, @command{@value{AS}} assumes zero for |
| 3333 | all these attributes, and probably won't warn you. This makes the |
| 3334 | symbol an externally defined symbol, which is generally what you |
| 3335 | would want. |
| 3336 | |
| 3337 | @menu |
| 3338 | * Symbol Value:: Value |
| 3339 | * Symbol Type:: Type |
| 3340 | @ifset aout-bout |
| 3341 | @ifset GENERIC |
| 3342 | * a.out Symbols:: Symbol Attributes: @code{a.out} |
| 3343 | @end ifset |
| 3344 | @ifclear GENERIC |
| 3345 | @ifclear BOUT |
| 3346 | * a.out Symbols:: Symbol Attributes: @code{a.out} |
| 3347 | @end ifclear |
| 3348 | @ifset BOUT |
| 3349 | * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out} |
| 3350 | @end ifset |
| 3351 | @end ifclear |
| 3352 | @end ifset |
| 3353 | @ifset COFF |
| 3354 | * COFF Symbols:: Symbol Attributes for COFF |
| 3355 | @end ifset |
| 3356 | @ifset SOM |
| 3357 | * SOM Symbols:: Symbol Attributes for SOM |
| 3358 | @end ifset |
| 3359 | @end menu |
| 3360 | |
| 3361 | @node Symbol Value |
| 3362 | @subsection Value |
| 3363 | |
| 3364 | @cindex value of a symbol |
| 3365 | @cindex symbol value |
| 3366 | The value of a symbol is (usually) 32 bits. For a symbol which labels a |
| 3367 | location in the text, data, bss or absolute sections the value is the |
| 3368 | number of addresses from the start of that section to the label. |
| 3369 | Naturally for text, data and bss sections the value of a symbol changes |
| 3370 | as @code{@value{LD}} changes section base addresses during linking. Absolute |
| 3371 | symbols' values do not change during linking: that is why they are |
| 3372 | called absolute. |
| 3373 | |
| 3374 | The value of an undefined symbol is treated in a special way. If it is |
| 3375 | 0 then the symbol is not defined in this assembler source file, and |
| 3376 | @code{@value{LD}} tries to determine its value from other files linked into the |
| 3377 | same program. You make this kind of symbol simply by mentioning a symbol |
| 3378 | name without defining it. A non-zero value represents a @code{.comm} |
| 3379 | common declaration. The value is how much common storage to reserve, in |
| 3380 | bytes (addresses). The symbol refers to the first address of the |
| 3381 | allocated storage. |
| 3382 | |
| 3383 | @node Symbol Type |
| 3384 | @subsection Type |
| 3385 | |
| 3386 | @cindex type of a symbol |
| 3387 | @cindex symbol type |
| 3388 | The type attribute of a symbol contains relocation (section) |
| 3389 | information, any flag settings indicating that a symbol is external, and |
| 3390 | (optionally), other information for linkers and debuggers. The exact |
| 3391 | format depends on the object-code output format in use. |
| 3392 | |
| 3393 | @ifset aout-bout |
| 3394 | @ifclear GENERIC |
| 3395 | @ifset BOUT |
| 3396 | @c The following avoids a "widow" subsection title. @group would be |
| 3397 | @c better if it were available outside examples. |
| 3398 | @need 1000 |
| 3399 | @node a.out Symbols |
| 3400 | @subsection Symbol Attributes: @code{a.out}, @code{b.out} |
| 3401 | |
| 3402 | @cindex @code{b.out} symbol attributes |
| 3403 | @cindex symbol attributes, @code{b.out} |
| 3404 | These symbol attributes appear only when @command{@value{AS}} is configured for |
| 3405 | one of the Berkeley-descended object output formats---@code{a.out} or |
| 3406 | @code{b.out}. |
| 3407 | |
| 3408 | @end ifset |
| 3409 | @ifclear BOUT |
| 3410 | @node a.out Symbols |
| 3411 | @subsection Symbol Attributes: @code{a.out} |
| 3412 | |
| 3413 | @cindex @code{a.out} symbol attributes |
| 3414 | @cindex symbol attributes, @code{a.out} |
| 3415 | |
| 3416 | @end ifclear |
| 3417 | @end ifclear |
| 3418 | @ifset GENERIC |
| 3419 | @node a.out Symbols |
| 3420 | @subsection Symbol Attributes: @code{a.out} |
| 3421 | |
| 3422 | @cindex @code{a.out} symbol attributes |
| 3423 | @cindex symbol attributes, @code{a.out} |
| 3424 | |
| 3425 | @end ifset |
| 3426 | @menu |
| 3427 | * Symbol Desc:: Descriptor |
| 3428 | * Symbol Other:: Other |
| 3429 | @end menu |
| 3430 | |
| 3431 | @node Symbol Desc |
| 3432 | @subsubsection Descriptor |
| 3433 | |
| 3434 | @cindex descriptor, of @code{a.out} symbol |
| 3435 | This is an arbitrary 16-bit value. You may establish a symbol's |
| 3436 | descriptor value by using a @code{.desc} statement |
| 3437 | (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to |
| 3438 | @command{@value{AS}}. |
| 3439 | |
| 3440 | @node Symbol Other |
| 3441 | @subsubsection Other |
| 3442 | |
| 3443 | @cindex other attribute, of @code{a.out} symbol |
| 3444 | This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}. |
| 3445 | @end ifset |
| 3446 | |
| 3447 | @ifset COFF |
| 3448 | @node COFF Symbols |
| 3449 | @subsection Symbol Attributes for COFF |
| 3450 | |
| 3451 | @cindex COFF symbol attributes |
| 3452 | @cindex symbol attributes, COFF |
| 3453 | |
| 3454 | The COFF format supports a multitude of auxiliary symbol attributes; |
| 3455 | like the primary symbol attributes, they are set between @code{.def} and |
| 3456 | @code{.endef} directives. |
| 3457 | |
| 3458 | @subsubsection Primary Attributes |
| 3459 | |
| 3460 | @cindex primary attributes, COFF symbols |
| 3461 | The symbol name is set with @code{.def}; the value and type, |
| 3462 | respectively, with @code{.val} and @code{.type}. |
| 3463 | |
| 3464 | @subsubsection Auxiliary Attributes |
| 3465 | |
| 3466 | @cindex auxiliary attributes, COFF symbols |
| 3467 | The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl}, |
| 3468 | @code{.size}, @code{.tag}, and @code{.weak} can generate auxiliary symbol |
| 3469 | table information for COFF. |
| 3470 | @end ifset |
| 3471 | |
| 3472 | @ifset SOM |
| 3473 | @node SOM Symbols |
| 3474 | @subsection Symbol Attributes for SOM |
| 3475 | |
| 3476 | @cindex SOM symbol attributes |
| 3477 | @cindex symbol attributes, SOM |
| 3478 | |
| 3479 | The SOM format for the HPPA supports a multitude of symbol attributes set with |
| 3480 | the @code{.EXPORT} and @code{.IMPORT} directives. |
| 3481 | |
| 3482 | The attributes are described in @cite{HP9000 Series 800 Assembly |
| 3483 | Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and |
| 3484 | @code{EXPORT} assembler directive documentation. |
| 3485 | @end ifset |
| 3486 | |
| 3487 | @node Expressions |
| 3488 | @chapter Expressions |
| 3489 | |
| 3490 | @cindex expressions |
| 3491 | @cindex addresses |
| 3492 | @cindex numeric values |
| 3493 | An @dfn{expression} specifies an address or numeric value. |
| 3494 | Whitespace may precede and/or follow an expression. |
| 3495 | |
| 3496 | The result of an expression must be an absolute number, or else an offset into |
| 3497 | a particular section. If an expression is not absolute, and there is not |
| 3498 | enough information when @command{@value{AS}} sees the expression to know its |
| 3499 | section, a second pass over the source program might be necessary to interpret |
| 3500 | the expression---but the second pass is currently not implemented. |
| 3501 | @command{@value{AS}} aborts with an error message in this situation. |
| 3502 | |
| 3503 | @menu |
| 3504 | * Empty Exprs:: Empty Expressions |
| 3505 | * Integer Exprs:: Integer Expressions |
| 3506 | @end menu |
| 3507 | |
| 3508 | @node Empty Exprs |
| 3509 | @section Empty Expressions |
| 3510 | |
| 3511 | @cindex empty expressions |
| 3512 | @cindex expressions, empty |
| 3513 | An empty expression has no value: it is just whitespace or null. |
| 3514 | Wherever an absolute expression is required, you may omit the |
| 3515 | expression, and @command{@value{AS}} assumes a value of (absolute) 0. This |
| 3516 | is compatible with other assemblers. |
| 3517 | |
| 3518 | @node Integer Exprs |
| 3519 | @section Integer Expressions |
| 3520 | |
| 3521 | @cindex integer expressions |
| 3522 | @cindex expressions, integer |
| 3523 | An @dfn{integer expression} is one or more @emph{arguments} delimited |
| 3524 | by @emph{operators}. |
| 3525 | |
| 3526 | @menu |
| 3527 | * Arguments:: Arguments |
| 3528 | * Operators:: Operators |
| 3529 | * Prefix Ops:: Prefix Operators |
| 3530 | * Infix Ops:: Infix Operators |
| 3531 | @end menu |
| 3532 | |
| 3533 | @node Arguments |
| 3534 | @subsection Arguments |
| 3535 | |
| 3536 | @cindex expression arguments |
| 3537 | @cindex arguments in expressions |
| 3538 | @cindex operands in expressions |
| 3539 | @cindex arithmetic operands |
| 3540 | @dfn{Arguments} are symbols, numbers or subexpressions. In other |
| 3541 | contexts arguments are sometimes called ``arithmetic operands''. In |
| 3542 | this manual, to avoid confusing them with the ``instruction operands'' of |
| 3543 | the machine language, we use the term ``argument'' to refer to parts of |
| 3544 | expressions only, reserving the word ``operand'' to refer only to machine |
| 3545 | instruction operands. |
| 3546 | |
| 3547 | Symbols are evaluated to yield @{@var{section} @var{NNN}@} where |
| 3548 | @var{section} is one of text, data, bss, absolute, |
| 3549 | or undefined. @var{NNN} is a signed, 2's complement 32 bit |
| 3550 | integer. |
| 3551 | |
| 3552 | Numbers are usually integers. |
| 3553 | |
| 3554 | A number can be a flonum or bignum. In this case, you are warned |
| 3555 | that only the low order 32 bits are used, and @command{@value{AS}} pretends |
| 3556 | these 32 bits are an integer. You may write integer-manipulating |
| 3557 | instructions that act on exotic constants, compatible with other |
| 3558 | assemblers. |
| 3559 | |
| 3560 | @cindex subexpressions |
| 3561 | Subexpressions are a left parenthesis @samp{(} followed by an integer |
| 3562 | expression, followed by a right parenthesis @samp{)}; or a prefix |
| 3563 | operator followed by an argument. |
| 3564 | |
| 3565 | @node Operators |
| 3566 | @subsection Operators |
| 3567 | |
| 3568 | @cindex operators, in expressions |
| 3569 | @cindex arithmetic functions |
| 3570 | @cindex functions, in expressions |
| 3571 | @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix |
| 3572 | operators are followed by an argument. Infix operators appear |
| 3573 | between their arguments. Operators may be preceded and/or followed by |
| 3574 | whitespace. |
| 3575 | |
| 3576 | @node Prefix Ops |
| 3577 | @subsection Prefix Operator |
| 3578 | |
| 3579 | @cindex prefix operators |
| 3580 | @command{@value{AS}} has the following @dfn{prefix operators}. They each take |
| 3581 | one argument, which must be absolute. |
| 3582 | |
| 3583 | @c the tex/end tex stuff surrounding this small table is meant to make |
| 3584 | @c it align, on the printed page, with the similar table in the next |
| 3585 | @c section (which is inside an enumerate). |
| 3586 | @tex |
| 3587 | \global\advance\leftskip by \itemindent |
| 3588 | @end tex |
| 3589 | |
| 3590 | @table @code |
| 3591 | @item - |
| 3592 | @dfn{Negation}. Two's complement negation. |
| 3593 | @item ~ |
| 3594 | @dfn{Complementation}. Bitwise not. |
| 3595 | @end table |
| 3596 | |
| 3597 | @tex |
| 3598 | \global\advance\leftskip by -\itemindent |
| 3599 | @end tex |
| 3600 | |
| 3601 | @node Infix Ops |
| 3602 | @subsection Infix Operators |
| 3603 | |
| 3604 | @cindex infix operators |
| 3605 | @cindex operators, permitted arguments |
| 3606 | @dfn{Infix operators} take two arguments, one on either side. Operators |
| 3607 | have precedence, but operations with equal precedence are performed left |
| 3608 | to right. Apart from @code{+} or @option{-}, both arguments must be |
| 3609 | absolute, and the result is absolute. |
| 3610 | |
| 3611 | @enumerate |
| 3612 | @cindex operator precedence |
| 3613 | @cindex precedence of operators |
| 3614 | |
| 3615 | @item |
| 3616 | Highest Precedence |
| 3617 | |
| 3618 | @table @code |
| 3619 | @item * |
| 3620 | @dfn{Multiplication}. |
| 3621 | |
| 3622 | @item / |
| 3623 | @dfn{Division}. Truncation is the same as the C operator @samp{/} |
| 3624 | |
| 3625 | @item % |
| 3626 | @dfn{Remainder}. |
| 3627 | |
| 3628 | @item << |
| 3629 | @dfn{Shift Left}. Same as the C operator @samp{<<}. |
| 3630 | |
| 3631 | @item >> |
| 3632 | @dfn{Shift Right}. Same as the C operator @samp{>>}. |
| 3633 | @end table |
| 3634 | |
| 3635 | @item |
| 3636 | Intermediate precedence |
| 3637 | |
| 3638 | @table @code |
| 3639 | @item | |
| 3640 | |
| 3641 | @dfn{Bitwise Inclusive Or}. |
| 3642 | |
| 3643 | @item & |
| 3644 | @dfn{Bitwise And}. |
| 3645 | |
| 3646 | @item ^ |
| 3647 | @dfn{Bitwise Exclusive Or}. |
| 3648 | |
| 3649 | @item ! |
| 3650 | @dfn{Bitwise Or Not}. |
| 3651 | @end table |
| 3652 | |
| 3653 | @item |
| 3654 | Low Precedence |
| 3655 | |
| 3656 | @table @code |
| 3657 | @cindex addition, permitted arguments |
| 3658 | @cindex plus, permitted arguments |
| 3659 | @cindex arguments for addition |
| 3660 | @item + |
| 3661 | @dfn{Addition}. If either argument is absolute, the result has the section of |
| 3662 | the other argument. You may not add together arguments from different |
| 3663 | sections. |
| 3664 | |
| 3665 | @cindex subtraction, permitted arguments |
| 3666 | @cindex minus, permitted arguments |
| 3667 | @cindex arguments for subtraction |
| 3668 | @item - |
| 3669 | @dfn{Subtraction}. If the right argument is absolute, the |
| 3670 | result has the section of the left argument. |
| 3671 | If both arguments are in the same section, the result is absolute. |
| 3672 | You may not subtract arguments from different sections. |
| 3673 | @c FIXME is there still something useful to say about undefined - undefined ? |
| 3674 | |
| 3675 | @cindex comparison expressions |
| 3676 | @cindex expressions, comparison |
| 3677 | @item == |
| 3678 | @dfn{Is Equal To} |
| 3679 | @item <> |
| 3680 | @itemx != |
| 3681 | @dfn{Is Not Equal To} |
| 3682 | @item < |
| 3683 | @dfn{Is Less Than} |
| 3684 | @item > |
| 3685 | @dfn{Is Greater Than} |
| 3686 | @item >= |
| 3687 | @dfn{Is Greater Than Or Equal To} |
| 3688 | @item <= |
| 3689 | @dfn{Is Less Than Or Equal To} |
| 3690 | |
| 3691 | The comparison operators can be used as infix operators. A true results has a |
| 3692 | value of -1 whereas a false result has a value of 0. Note, these operators |
| 3693 | perform signed comparisons. |
| 3694 | @end table |
| 3695 | |
| 3696 | @item Lowest Precedence |
| 3697 | |
| 3698 | @table @code |
| 3699 | @item && |
| 3700 | @dfn{Logical And}. |
| 3701 | |
| 3702 | @item || |
| 3703 | @dfn{Logical Or}. |
| 3704 | |
| 3705 | These two logical operations can be used to combine the results of sub |
| 3706 | expressions. Note, unlike the comparison operators a true result returns a |
| 3707 | value of 1 but a false results does still return 0. Also note that the logical |
| 3708 | or operator has a slightly lower precedence than logical and. |
| 3709 | |
| 3710 | @end table |
| 3711 | @end enumerate |
| 3712 | |
| 3713 | In short, it's only meaningful to add or subtract the @emph{offsets} in an |
| 3714 | address; you can only have a defined section in one of the two arguments. |
| 3715 | |
| 3716 | @node Pseudo Ops |
| 3717 | @chapter Assembler Directives |
| 3718 | |
| 3719 | @cindex directives, machine independent |
| 3720 | @cindex pseudo-ops, machine independent |
| 3721 | @cindex machine independent directives |
| 3722 | All assembler directives have names that begin with a period (@samp{.}). |
| 3723 | The rest of the name is letters, usually in lower case. |
| 3724 | |
| 3725 | This chapter discusses directives that are available regardless of the |
| 3726 | target machine configuration for the @sc{gnu} assembler. |
| 3727 | @ifset GENERIC |
| 3728 | Some machine configurations provide additional directives. |
| 3729 | @xref{Machine Dependencies}. |
| 3730 | @end ifset |
| 3731 | @ifclear GENERIC |
| 3732 | @ifset machine-directives |
| 3733 | @xref{Machine Dependencies} for additional directives. |
| 3734 | @end ifset |
| 3735 | @end ifclear |
| 3736 | |
| 3737 | @menu |
| 3738 | * Abort:: @code{.abort} |
| 3739 | @ifset COFF |
| 3740 | * ABORT (COFF):: @code{.ABORT} |
| 3741 | @end ifset |
| 3742 | |
| 3743 | * Align:: @code{.align @var{abs-expr} , @var{abs-expr}} |
| 3744 | * Altmacro:: @code{.altmacro} |
| 3745 | * Ascii:: @code{.ascii "@var{string}"}@dots{} |
| 3746 | * Asciz:: @code{.asciz "@var{string}"}@dots{} |
| 3747 | * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}} |
| 3748 | * Byte:: @code{.byte @var{expressions}} |
| 3749 | * Comm:: @code{.comm @var{symbol} , @var{length} } |
| 3750 | |
| 3751 | * CFI directives:: @code{.cfi_startproc}, @code{.cfi_endproc}, etc. |
| 3752 | |
| 3753 | * Data:: @code{.data @var{subsection}} |
| 3754 | @ifset COFF |
| 3755 | * Def:: @code{.def @var{name}} |
| 3756 | @end ifset |
| 3757 | @ifset aout-bout |
| 3758 | * Desc:: @code{.desc @var{symbol}, @var{abs-expression}} |
| 3759 | @end ifset |
| 3760 | @ifset COFF |
| 3761 | * Dim:: @code{.dim} |
| 3762 | @end ifset |
| 3763 | |
| 3764 | * Double:: @code{.double @var{flonums}} |
| 3765 | * Eject:: @code{.eject} |
| 3766 | * Else:: @code{.else} |
| 3767 | * Elseif:: @code{.elseif} |
| 3768 | * End:: @code{.end} |
| 3769 | @ifset COFF |
| 3770 | * Endef:: @code{.endef} |
| 3771 | @end ifset |
| 3772 | |
| 3773 | * Endfunc:: @code{.endfunc} |
| 3774 | * Endif:: @code{.endif} |
| 3775 | * Equ:: @code{.equ @var{symbol}, @var{expression}} |
| 3776 | * Equiv:: @code{.equiv @var{symbol}, @var{expression}} |
| 3777 | * Eqv:: @code{.eqv @var{symbol}, @var{expression}} |
| 3778 | * Err:: @code{.err} |
| 3779 | * Error:: @code{.error @var{string}} |
| 3780 | * Exitm:: @code{.exitm} |
| 3781 | * Extern:: @code{.extern} |
| 3782 | * Fail:: @code{.fail} |
| 3783 | @ifclear no-file-dir |
| 3784 | * File:: @code{.file @var{string}} |
| 3785 | @end ifclear |
| 3786 | |
| 3787 | * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}} |
| 3788 | * Float:: @code{.float @var{flonums}} |
| 3789 | * Func:: @code{.func} |
| 3790 | * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}} |
| 3791 | @ifset ELF |
| 3792 | * Hidden:: @code{.hidden @var{names}} |
| 3793 | @end ifset |
| 3794 | |
| 3795 | * hword:: @code{.hword @var{expressions}} |
| 3796 | * Ident:: @code{.ident} |
| 3797 | * If:: @code{.if @var{absolute expression}} |
| 3798 | * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]} |
| 3799 | * Include:: @code{.include "@var{file}"} |
| 3800 | * Int:: @code{.int @var{expressions}} |
| 3801 | @ifset ELF |
| 3802 | * Internal:: @code{.internal @var{names}} |
| 3803 | @end ifset |
| 3804 | |
| 3805 | * Irp:: @code{.irp @var{symbol},@var{values}}@dots{} |
| 3806 | * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{} |
| 3807 | * Lcomm:: @code{.lcomm @var{symbol} , @var{length}} |
| 3808 | * Lflags:: @code{.lflags} |
| 3809 | @ifclear no-line-dir |
| 3810 | * Line:: @code{.line @var{line-number}} |
| 3811 | @end ifclear |
| 3812 | |
| 3813 | * Linkonce:: @code{.linkonce [@var{type}]} |
| 3814 | * List:: @code{.list} |
| 3815 | * Ln:: @code{.ln @var{line-number}} |
| 3816 | |
| 3817 | * LNS directives:: @code{.file}, @code{.loc}, etc. |
| 3818 | |
| 3819 | * Long:: @code{.long @var{expressions}} |
| 3820 | @ignore |
| 3821 | * Lsym:: @code{.lsym @var{symbol}, @var{expression}} |
| 3822 | @end ignore |
| 3823 | |
| 3824 | * Macro:: @code{.macro @var{name} @var{args}}@dots{} |
| 3825 | * MRI:: @code{.mri @var{val}} |
| 3826 | * Noaltmacro:: @code{.noaltmacro} |
| 3827 | * Nolist:: @code{.nolist} |
| 3828 | * Octa:: @code{.octa @var{bignums}} |
| 3829 | * Org:: @code{.org @var{new-lc}, @var{fill}} |
| 3830 | * P2align:: @code{.p2align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} |
| 3831 | @ifset ELF |
| 3832 | * PopSection:: @code{.popsection} |
| 3833 | * Previous:: @code{.previous} |
| 3834 | @end ifset |
| 3835 | |
| 3836 | * Print:: @code{.print @var{string}} |
| 3837 | @ifset ELF |
| 3838 | * Protected:: @code{.protected @var{names}} |
| 3839 | @end ifset |
| 3840 | |
| 3841 | * Psize:: @code{.psize @var{lines}, @var{columns}} |
| 3842 | * Purgem:: @code{.purgem @var{name}} |
| 3843 | @ifset ELF |
| 3844 | * PushSection:: @code{.pushsection @var{name}} |
| 3845 | @end ifset |
| 3846 | |
| 3847 | * Quad:: @code{.quad @var{bignums}} |
| 3848 | * Rept:: @code{.rept @var{count}} |
| 3849 | * Sbttl:: @code{.sbttl "@var{subheading}"} |
| 3850 | @ifset COFF |
| 3851 | * Scl:: @code{.scl @var{class}} |
| 3852 | @end ifset |
| 3853 | @ifset COFF-ELF |
| 3854 | * Section:: @code{.section @var{name}} |
| 3855 | @end ifset |
| 3856 | |
| 3857 | * Set:: @code{.set @var{symbol}, @var{expression}} |
| 3858 | * Short:: @code{.short @var{expressions}} |
| 3859 | * Single:: @code{.single @var{flonums}} |
| 3860 | @ifset COFF-ELF |
| 3861 | * Size:: @code{.size [@var{name} , @var{expression}]} |
| 3862 | @end ifset |
| 3863 | |
| 3864 | * Skip:: @code{.skip @var{size} , @var{fill}} |
| 3865 | * Sleb128:: @code{.sleb128 @var{expressions}} |
| 3866 | * Space:: @code{.space @var{size} , @var{fill}} |
| 3867 | @ifset have-stabs |
| 3868 | * Stab:: @code{.stabd, .stabn, .stabs} |
| 3869 | @end ifset |
| 3870 | |
| 3871 | * String:: @code{.string "@var{str}"} |
| 3872 | * Struct:: @code{.struct @var{expression}} |
| 3873 | @ifset ELF |
| 3874 | * SubSection:: @code{.subsection} |
| 3875 | * Symver:: @code{.symver @var{name},@var{name2@@nodename}} |
| 3876 | @end ifset |
| 3877 | |
| 3878 | @ifset COFF |
| 3879 | * Tag:: @code{.tag @var{structname}} |
| 3880 | @end ifset |
| 3881 | |
| 3882 | * Text:: @code{.text @var{subsection}} |
| 3883 | * Title:: @code{.title "@var{heading}"} |
| 3884 | @ifset COFF-ELF |
| 3885 | * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>} |
| 3886 | @end ifset |
| 3887 | |
| 3888 | * Uleb128:: @code{.uleb128 @var{expressions}} |
| 3889 | @ifset COFF |
| 3890 | * Val:: @code{.val @var{addr}} |
| 3891 | @end ifset |
| 3892 | |
| 3893 | @ifset ELF |
| 3894 | * Version:: @code{.version "@var{string}"} |
| 3895 | * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}} |
| 3896 | * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}} |
| 3897 | @end ifset |
| 3898 | |
| 3899 | * Warning:: @code{.warning @var{string}} |
| 3900 | * Weak:: @code{.weak @var{names}} |
| 3901 | * Weakref:: @code{.weakref @var{alias}, @var{symbol}} |
| 3902 | * Word:: @code{.word @var{expressions}} |
| 3903 | * Deprecated:: Deprecated Directives |
| 3904 | @end menu |
| 3905 | |
| 3906 | @node Abort |
| 3907 | @section @code{.abort} |
| 3908 | |
| 3909 | @cindex @code{abort} directive |
| 3910 | @cindex stopping the assembly |
| 3911 | This directive stops the assembly immediately. It is for |
| 3912 | compatibility with other assemblers. The original idea was that the |
| 3913 | assembly language source would be piped into the assembler. If the sender |
| 3914 | of the source quit, it could use this directive tells @command{@value{AS}} to |
| 3915 | quit also. One day @code{.abort} will not be supported. |
| 3916 | |
| 3917 | @ifset COFF |
| 3918 | @node ABORT (COFF) |
| 3919 | @section @code{.ABORT} (COFF) |
| 3920 | |
| 3921 | @cindex @code{ABORT} directive |
| 3922 | When producing COFF output, @command{@value{AS}} accepts this directive as a |
| 3923 | synonym for @samp{.abort}. |
| 3924 | |
| 3925 | @ifset BOUT |
| 3926 | When producing @code{b.out} output, @command{@value{AS}} accepts this directive, |
| 3927 | but ignores it. |
| 3928 | @end ifset |
| 3929 | @end ifset |
| 3930 | |
| 3931 | @node Align |
| 3932 | @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} |
| 3933 | |
| 3934 | @cindex padding the location counter |
| 3935 | @cindex @code{align} directive |
| 3936 | Pad the location counter (in the current subsection) to a particular storage |
| 3937 | boundary. The first expression (which must be absolute) is the alignment |
| 3938 | required, as described below. |
| 3939 | |
| 3940 | The second expression (also absolute) gives the fill value to be stored in the |
| 3941 | padding bytes. It (and the comma) may be omitted. If it is omitted, the |
| 3942 | padding bytes are normally zero. However, on some systems, if the section is |
| 3943 | marked as containing code and the fill value is omitted, the space is filled |
| 3944 | with no-op instructions. |
| 3945 | |
| 3946 | The third expression is also absolute, and is also optional. If it is present, |
| 3947 | it is the maximum number of bytes that should be skipped by this alignment |
| 3948 | directive. If doing the alignment would require skipping more bytes than the |
| 3949 | specified maximum, then the alignment is not done at all. You can omit the |
| 3950 | fill value (the second argument) entirely by simply using two commas after the |
| 3951 | required alignment; this can be useful if you want the alignment to be filled |
| 3952 | with no-op instructions when appropriate. |
| 3953 | |
| 3954 | The way the required alignment is specified varies from system to system. |
| 3955 | For the arc, hppa, i386 using ELF, i860, iq2000, m68k, or32, |
| 3956 | s390, sparc, tic4x, tic80 and xtensa, the first expression is the |
| 3957 | alignment request in bytes. For example @samp{.align 8} advances |
| 3958 | the location counter until it is a multiple of 8. If the location counter |
| 3959 | is already a multiple of 8, no change is needed. For the tic54x, the |
| 3960 | first expression is the alignment request in words. |
| 3961 | |
| 3962 | For other systems, including the i386 using a.out format, and the arm and |
| 3963 | strongarm, it is the |
| 3964 | number of low-order zero bits the location counter must have after |
| 3965 | advancement. For example @samp{.align 3} advances the location |
| 3966 | counter until it a multiple of 8. If the location counter is already a |
| 3967 | multiple of 8, no change is needed. |
| 3968 | |
| 3969 | This inconsistency is due to the different behaviors of the various |
| 3970 | native assemblers for these systems which GAS must emulate. |
| 3971 | GAS also provides @code{.balign} and @code{.p2align} directives, |
| 3972 | described later, which have a consistent behavior across all |
| 3973 | architectures (but are specific to GAS). |
| 3974 | |
| 3975 | @node Ascii |
| 3976 | @section @code{.ascii "@var{string}"}@dots{} |
| 3977 | |
| 3978 | @cindex @code{ascii} directive |
| 3979 | @cindex string literals |
| 3980 | @code{.ascii} expects zero or more string literals (@pxref{Strings}) |
| 3981 | separated by commas. It assembles each string (with no automatic |
| 3982 | trailing zero byte) into consecutive addresses. |
| 3983 | |
| 3984 | @node Asciz |
| 3985 | @section @code{.asciz "@var{string}"}@dots{} |
| 3986 | |
| 3987 | @cindex @code{asciz} directive |
| 3988 | @cindex zero-terminated strings |
| 3989 | @cindex null-terminated strings |
| 3990 | @code{.asciz} is just like @code{.ascii}, but each string is followed by |
| 3991 | a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''. |
| 3992 | |
| 3993 | @node Balign |
| 3994 | @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} |
| 3995 | |
| 3996 | @cindex padding the location counter given number of bytes |
| 3997 | @cindex @code{balign} directive |
| 3998 | Pad the location counter (in the current subsection) to a particular |
| 3999 | storage boundary. The first expression (which must be absolute) is the |
| 4000 | alignment request in bytes. For example @samp{.balign 8} advances |
| 4001 | the location counter until it is a multiple of 8. If the location counter |
| 4002 | is already a multiple of 8, no change is needed. |
| 4003 | |
| 4004 | The second expression (also absolute) gives the fill value to be stored in the |
| 4005 | padding bytes. It (and the comma) may be omitted. If it is omitted, the |
| 4006 | padding bytes are normally zero. However, on some systems, if the section is |
| 4007 | marked as containing code and the fill value is omitted, the space is filled |
| 4008 | with no-op instructions. |
| 4009 | |
| 4010 | The third expression is also absolute, and is also optional. If it is present, |
| 4011 | it is the maximum number of bytes that should be skipped by this alignment |
| 4012 | directive. If doing the alignment would require skipping more bytes than the |
| 4013 | specified maximum, then the alignment is not done at all. You can omit the |
| 4014 | fill value (the second argument) entirely by simply using two commas after the |
| 4015 | required alignment; this can be useful if you want the alignment to be filled |
| 4016 | with no-op instructions when appropriate. |
| 4017 | |
| 4018 | @cindex @code{balignw} directive |
| 4019 | @cindex @code{balignl} directive |
| 4020 | The @code{.balignw} and @code{.balignl} directives are variants of the |
| 4021 | @code{.balign} directive. The @code{.balignw} directive treats the fill |
| 4022 | pattern as a two byte word value. The @code{.balignl} directives treats the |
| 4023 | fill pattern as a four byte longword value. For example, @code{.balignw |
| 4024 | 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be |
| 4025 | filled in with the value 0x368d (the exact placement of the bytes depends upon |
| 4026 | the endianness of the processor). If it skips 1 or 3 bytes, the fill value is |
| 4027 | undefined. |
| 4028 | |
| 4029 | @node Byte |
| 4030 | @section @code{.byte @var{expressions}} |
| 4031 | |
| 4032 | @cindex @code{byte} directive |
| 4033 | @cindex integers, one byte |
| 4034 | @code{.byte} expects zero or more expressions, separated by commas. |
| 4035 | Each expression is assembled into the next byte. |
| 4036 | |
| 4037 | @node Comm |
| 4038 | @section @code{.comm @var{symbol} , @var{length} } |
| 4039 | |
| 4040 | @cindex @code{comm} directive |
| 4041 | @cindex symbol, common |
| 4042 | @code{.comm} declares a common symbol named @var{symbol}. When linking, a |
| 4043 | common symbol in one object file may be merged with a defined or common symbol |
| 4044 | of the same name in another object file. If @code{@value{LD}} does not see a |
| 4045 | definition for the symbol--just one or more common symbols--then it will |
| 4046 | allocate @var{length} bytes of uninitialized memory. @var{length} must be an |
| 4047 | absolute expression. If @code{@value{LD}} sees multiple common symbols with |
| 4048 | the same name, and they do not all have the same size, it will allocate space |
| 4049 | using the largest size. |
| 4050 | |
| 4051 | @ifset ELF |
| 4052 | When using ELF, the @code{.comm} directive takes an optional third argument. |
| 4053 | This is the desired alignment of the symbol, specified as a byte boundary (for |
| 4054 | example, an alignment of 16 means that the least significant 4 bits of the |
| 4055 | address should be zero). The alignment must be an absolute expression, and it |
| 4056 | must be a power of two. If @code{@value{LD}} allocates uninitialized memory |
| 4057 | for the common symbol, it will use the alignment when placing the symbol. If |
| 4058 | no alignment is specified, @command{@value{AS}} will set the alignment to the |
| 4059 | largest power of two less than or equal to the size of the symbol, up to a |
| 4060 | maximum of 16. |
| 4061 | @end ifset |
| 4062 | |
| 4063 | @ifset HPPA |
| 4064 | The syntax for @code{.comm} differs slightly on the HPPA. The syntax is |
| 4065 | @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional. |
| 4066 | @end ifset |
| 4067 | |
| 4068 | @node CFI directives |
| 4069 | @section @code{.cfi_startproc} |
| 4070 | @cindex @code{cfi_startproc} directive |
| 4071 | @code{.cfi_startproc} is used at the beginning of each function that |
| 4072 | should have an entry in @code{.eh_frame}. It initializes some internal |
| 4073 | data structures and emits architecture dependent initial CFI instructions. |
| 4074 | Don't forget to close the function by |
| 4075 | @code{.cfi_endproc}. |
| 4076 | |
| 4077 | @section @code{.cfi_endproc} |
| 4078 | @cindex @code{cfi_endproc} directive |
| 4079 | @code{.cfi_endproc} is used at the end of a function where it closes its |
| 4080 | unwind entry previously opened by |
| 4081 | @code{.cfi_startproc}. and emits it to @code{.eh_frame}. |
| 4082 | |
| 4083 | @section @code{.cfi_def_cfa @var{register}, @var{offset}} |
| 4084 | @code{.cfi_def_cfa} defines a rule for computing CFA as: @i{take |
| 4085 | address from @var{register} and add @var{offset} to it}. |
| 4086 | |
| 4087 | @section @code{.cfi_def_cfa_register @var{register}} |
| 4088 | @code{.cfi_def_cfa_register} modifies a rule for computing CFA. From |
| 4089 | now on @var{register} will be used instead of the old one. Offset |
| 4090 | remains the same. |
| 4091 | |
| 4092 | @section @code{.cfi_def_cfa_offset @var{offset}} |
| 4093 | @code{.cfi_def_cfa_offset} modifies a rule for computing CFA. Register |
| 4094 | remains the same, but @var{offset} is new. Note that it is the |
| 4095 | absolute offset that will be added to a defined register to compute |
| 4096 | CFA address. |
| 4097 | |
| 4098 | @section @code{.cfi_adjust_cfa_offset @var{offset}} |
| 4099 | Same as @code{.cfi_def_cfa_offset} but @var{offset} is a relative |
| 4100 | value that is added/substracted from the previous offset. |
| 4101 | |
| 4102 | @section @code{.cfi_offset @var{register}, @var{offset}} |
| 4103 | Previous value of @var{register} is saved at offset @var{offset} from |
| 4104 | CFA. |
| 4105 | |
| 4106 | @section @code{.cfi_rel_offset @var{register}, @var{offset}} |
| 4107 | Previous value of @var{register} is saved at offset @var{offset} from |
| 4108 | the current CFA register. This is transformed to @code{.cfi_offset} |
| 4109 | using the known displacement of the CFA register from the CFA. |
| 4110 | This is often easier to use, because the number will match the |
| 4111 | code it's annotating. |
| 4112 | |
| 4113 | @section @code{.cfi_signal_frame} |
| 4114 | Mark current function as signal trampoline. |
| 4115 | |
| 4116 | @section @code{.cfi_window_save} |
| 4117 | SPARC register window has been saved. |
| 4118 | |
| 4119 | @section @code{.cfi_escape} @var{expression}[, @dots{}] |
| 4120 | Allows the user to add arbitrary bytes to the unwind info. One |
| 4121 | might use this to add OS-specific CFI opcodes, or generic CFI |
| 4122 | opcodes that GAS does not yet support. |
| 4123 | |
| 4124 | @node LNS directives |
| 4125 | @section @code{.file @var{fileno} @var{filename}} |
| 4126 | @cindex @code{file} directive |
| 4127 | When emitting dwarf2 line number information @code{.file} assigns filenames |
| 4128 | to the @code{.debug_line} file name table. The @var{fileno} operand should |
| 4129 | be a unique positive integer to use as the index of the entry in the table. |
| 4130 | The @var{filename} operand is a C string literal. |
| 4131 | |
| 4132 | The detail of filename indicies is exposed to the user because the filename |
| 4133 | table is shared with the @code{.debug_info} section of the dwarf2 debugging |
| 4134 | information, and thus the user must know the exact indicies that table |
| 4135 | entries will have. |
| 4136 | |
| 4137 | @section @code{.loc @var{fileno} @var{lineno} [@var{column}] [@var{options}]} |
| 4138 | @cindex @code{loc} directive |
| 4139 | The @code{.loc} directive will add row to the @code{.debug_line} line |
| 4140 | number matrix corresponding to the immediately following assembly |
| 4141 | instruction. The @var{fileno}, @var{lineno}, and optional @var{column} |
| 4142 | arguments will be applied to the @code{.debug_line} state machine before |
| 4143 | the row is added. |
| 4144 | |
| 4145 | The @var{options} are a sequence of the following tokens in any order: |
| 4146 | |
| 4147 | @table @code |
| 4148 | @item basic_block |
| 4149 | This option will set the @code{basic_block} register in the |
| 4150 | @code{.debug_line} state machine to @code{true}. |
| 4151 | |
| 4152 | @item prologue_end |
| 4153 | This option will set the @code{prologue_end} register in the |
| 4154 | @code{.debug_line} state machine to @code{true}. |
| 4155 | |
| 4156 | @item epilogue_begin |
| 4157 | This option will set the @code{epilogue_begin} register in the |
| 4158 | @code{.debug_line} state machine to @code{true}. |
| 4159 | |
| 4160 | @item is_stmt @var{value} |
| 4161 | This option will set the @code{is_stmt} register in the |
| 4162 | @code{.debug_line} state machine to @code{value}, which must be |
| 4163 | either 0 or 1. |
| 4164 | |
| 4165 | @item isa @var{value} |
| 4166 | This directive will set the @code{isa} register in the @code{.debug_line} |
| 4167 | state machine to @var{value}, which must be an unsigned integer. |
| 4168 | |
| 4169 | @end table |
| 4170 | |
| 4171 | @section @code{.loc_mark_blocks @var{enable}} |
| 4172 | @cindex @code{loc_mark_blocks} directive |
| 4173 | The @code{.loc_mark_blocks} directive makes the assembler emit an entry |
| 4174 | to the @code{.debug_line} line number matrix with the @code{basic_block} |
| 4175 | register in the state machine set whenever a code label is seen. |
| 4176 | The @var{enable} argument should be either 1 or 0, to enable or disable |
| 4177 | this function respectively. |
| 4178 | |
| 4179 | @node Data |
| 4180 | @section @code{.data @var{subsection}} |
| 4181 | |
| 4182 | @cindex @code{data} directive |
| 4183 | @code{.data} tells @command{@value{AS}} to assemble the following statements onto the |
| 4184 | end of the data subsection numbered @var{subsection} (which is an |
| 4185 | absolute expression). If @var{subsection} is omitted, it defaults |
| 4186 | to zero. |
| 4187 | |
| 4188 | @ifset COFF |
| 4189 | @node Def |
| 4190 | @section @code{.def @var{name}} |
| 4191 | |
| 4192 | @cindex @code{def} directive |
| 4193 | @cindex COFF symbols, debugging |
| 4194 | @cindex debugging COFF symbols |
| 4195 | Begin defining debugging information for a symbol @var{name}; the |
| 4196 | definition extends until the @code{.endef} directive is encountered. |
| 4197 | @ifset BOUT |
| 4198 | |
| 4199 | This directive is only observed when @command{@value{AS}} is configured for COFF |
| 4200 | format output; when producing @code{b.out}, @samp{.def} is recognized, |
| 4201 | but ignored. |
| 4202 | @end ifset |
| 4203 | @end ifset |
| 4204 | |
| 4205 | @ifset aout-bout |
| 4206 | @node Desc |
| 4207 | @section @code{.desc @var{symbol}, @var{abs-expression}} |
| 4208 | |
| 4209 | @cindex @code{desc} directive |
| 4210 | @cindex COFF symbol descriptor |
| 4211 | @cindex symbol descriptor, COFF |
| 4212 | This directive sets the descriptor of the symbol (@pxref{Symbol Attributes}) |
| 4213 | to the low 16 bits of an absolute expression. |
| 4214 | |
| 4215 | @ifset COFF |
| 4216 | The @samp{.desc} directive is not available when @command{@value{AS}} is |
| 4217 | configured for COFF output; it is only for @code{a.out} or @code{b.out} |
| 4218 | object format. For the sake of compatibility, @command{@value{AS}} accepts |
| 4219 | it, but produces no output, when configured for COFF. |
| 4220 | @end ifset |
| 4221 | @end ifset |
| 4222 | |
| 4223 | @ifset COFF |
| 4224 | @node Dim |
| 4225 | @section @code{.dim} |
| 4226 | |
| 4227 | @cindex @code{dim} directive |
| 4228 | @cindex COFF auxiliary symbol information |
| 4229 | @cindex auxiliary symbol information, COFF |
| 4230 | This directive is generated by compilers to include auxiliary debugging |
| 4231 | information in the symbol table. It is only permitted inside |
| 4232 | @code{.def}/@code{.endef} pairs. |
| 4233 | @ifset BOUT |
| 4234 | |
| 4235 | @samp{.dim} is only meaningful when generating COFF format output; when |
| 4236 | @command{@value{AS}} is generating @code{b.out}, it accepts this directive but |
| 4237 | ignores it. |
| 4238 | @end ifset |
| 4239 | @end ifset |
| 4240 | |
| 4241 | @node Double |
| 4242 | @section @code{.double @var{flonums}} |
| 4243 | |
| 4244 | @cindex @code{double} directive |
| 4245 | @cindex floating point numbers (double) |
| 4246 | @code{.double} expects zero or more flonums, separated by commas. It |
| 4247 | assembles floating point numbers. |
| 4248 | @ifset GENERIC |
| 4249 | The exact kind of floating point numbers emitted depends on how |
| 4250 | @command{@value{AS}} is configured. @xref{Machine Dependencies}. |
| 4251 | @end ifset |
| 4252 | @ifclear GENERIC |
| 4253 | @ifset IEEEFLOAT |
| 4254 | On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers |
| 4255 | in @sc{ieee} format. |
| 4256 | @end ifset |
| 4257 | @end ifclear |
| 4258 | |
| 4259 | @node Eject |
| 4260 | @section @code{.eject} |
| 4261 | |
| 4262 | @cindex @code{eject} directive |
| 4263 | @cindex new page, in listings |
| 4264 | @cindex page, in listings |
| 4265 | @cindex listing control: new page |
| 4266 | Force a page break at this point, when generating assembly listings. |
| 4267 | |
| 4268 | @node Else |
| 4269 | @section @code{.else} |
| 4270 | |
| 4271 | @cindex @code{else} directive |
| 4272 | @code{.else} is part of the @command{@value{AS}} support for conditional |
| 4273 | assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section |
| 4274 | of code to be assembled if the condition for the preceding @code{.if} |
| 4275 | was false. |
| 4276 | |
| 4277 | @node Elseif |
| 4278 | @section @code{.elseif} |
| 4279 | |
| 4280 | @cindex @code{elseif} directive |
| 4281 | @code{.elseif} is part of the @command{@value{AS}} support for conditional |
| 4282 | assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new |
| 4283 | @code{.if} block that would otherwise fill the entire @code{.else} section. |
| 4284 | |
| 4285 | @node End |
| 4286 | @section @code{.end} |
| 4287 | |
| 4288 | @cindex @code{end} directive |
| 4289 | @code{.end} marks the end of the assembly file. @command{@value{AS}} does not |
| 4290 | process anything in the file past the @code{.end} directive. |
| 4291 | |
| 4292 | @ifset COFF |
| 4293 | @node Endef |
| 4294 | @section @code{.endef} |
| 4295 | |
| 4296 | @cindex @code{endef} directive |
| 4297 | This directive flags the end of a symbol definition begun with |
| 4298 | @code{.def}. |
| 4299 | @ifset BOUT |
| 4300 | |
| 4301 | @samp{.endef} is only meaningful when generating COFF format output; if |
| 4302 | @command{@value{AS}} is configured to generate @code{b.out}, it accepts this |
| 4303 | directive but ignores it. |
| 4304 | @end ifset |
| 4305 | @end ifset |
| 4306 | |
| 4307 | @node Endfunc |
| 4308 | @section @code{.endfunc} |
| 4309 | @cindex @code{endfunc} directive |
| 4310 | @code{.endfunc} marks the end of a function specified with @code{.func}. |
| 4311 | |
| 4312 | @node Endif |
| 4313 | @section @code{.endif} |
| 4314 | |
| 4315 | @cindex @code{endif} directive |
| 4316 | @code{.endif} is part of the @command{@value{AS}} support for conditional assembly; |
| 4317 | it marks the end of a block of code that is only assembled |
| 4318 | conditionally. @xref{If,,@code{.if}}. |
| 4319 | |
| 4320 | @node Equ |
| 4321 | @section @code{.equ @var{symbol}, @var{expression}} |
| 4322 | |
| 4323 | @cindex @code{equ} directive |
| 4324 | @cindex assigning values to symbols |
| 4325 | @cindex symbols, assigning values to |
| 4326 | This directive sets the value of @var{symbol} to @var{expression}. |
| 4327 | It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}. |
| 4328 | |
| 4329 | @ifset HPPA |
| 4330 | The syntax for @code{equ} on the HPPA is |
| 4331 | @samp{@var{symbol} .equ @var{expression}}. |
| 4332 | @end ifset |
| 4333 | |
| 4334 | @ifset Z80 |
| 4335 | The syntax for @code{equ} on the Z80 is |
| 4336 | @samp{@var{symbol} equ @var{expression}}. |
| 4337 | On the Z80 it is an eror if @var{symbol} is already defined, |
| 4338 | but the symbol is not protected from later redefinition, |
| 4339 | compare @xref{Equiv}. |
| 4340 | @end ifset |
| 4341 | |
| 4342 | @node Equiv |
| 4343 | @section @code{.equiv @var{symbol}, @var{expression}} |
| 4344 | @cindex @code{equiv} directive |
| 4345 | The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that |
| 4346 | the assembler will signal an error if @var{symbol} is already defined. Note a |
| 4347 | symbol which has been referenced but not actually defined is considered to be |
| 4348 | undefined. |
| 4349 | |
| 4350 | Except for the contents of the error message, this is roughly equivalent to |
| 4351 | @smallexample |
| 4352 | .ifdef SYM |
| 4353 | .err |
| 4354 | .endif |
| 4355 | .equ SYM,VAL |
| 4356 | @end smallexample |
| 4357 | plus it protects the symbol from later redefinition. |
| 4358 | |
| 4359 | @node Eqv |
| 4360 | @section @code{.eqv @var{symbol}, @var{expression}} |
| 4361 | @cindex @code{eqv} directive |
| 4362 | The @code{.eqv} directive is like @code{.equiv}, but no attempt is made to |
| 4363 | evaluate the expression or any part of it immediately. Instead each time |
| 4364 | the resulting symbol is used in an expression, a snapshot of its current |
| 4365 | value is taken. |
| 4366 | |
| 4367 | @node Err |
| 4368 | @section @code{.err} |
| 4369 | @cindex @code{err} directive |
| 4370 | If @command{@value{AS}} assembles a @code{.err} directive, it will print an error |
| 4371 | message and, unless the @option{-Z} option was used, it will not generate an |
| 4372 | object file. This can be used to signal an error in conditionally compiled code. |
| 4373 | |
| 4374 | @node Error |
| 4375 | @section @code{.error "@var{string}"} |
| 4376 | @cindex error directive |
| 4377 | |
| 4378 | Similarly to @code{.err}, this directive emits an error, but you can specify a |
| 4379 | string that will be emitted as the error message. If you don't specify the |
| 4380 | message, it defaults to @code{".error directive invoked in source file"}. |
| 4381 | @xref{Errors, ,Error and Warning Messages}. |
| 4382 | |
| 4383 | @smallexample |
| 4384 | .error "This code has not been assembled and tested." |
| 4385 | @end smallexample |
| 4386 | |
| 4387 | @node Exitm |
| 4388 | @section @code{.exitm} |
| 4389 | Exit early from the current macro definition. @xref{Macro}. |
| 4390 | |
| 4391 | @node Extern |
| 4392 | @section @code{.extern} |
| 4393 | |
| 4394 | @cindex @code{extern} directive |
| 4395 | @code{.extern} is accepted in the source program---for compatibility |
| 4396 | with other assemblers---but it is ignored. @command{@value{AS}} treats |
| 4397 | all undefined symbols as external. |
| 4398 | |
| 4399 | @node Fail |
| 4400 | @section @code{.fail @var{expression}} |
| 4401 | |
| 4402 | @cindex @code{fail} directive |
| 4403 | Generates an error or a warning. If the value of the @var{expression} is 500 |
| 4404 | or more, @command{@value{AS}} will print a warning message. If the value is less |
| 4405 | than 500, @command{@value{AS}} will print an error message. The message will |
| 4406 | include the value of @var{expression}. This can occasionally be useful inside |
| 4407 | complex nested macros or conditional assembly. |
| 4408 | |
| 4409 | @ifclear no-file-dir |
| 4410 | @node File |
| 4411 | @section @code{.file @var{string}} |
| 4412 | |
| 4413 | @cindex @code{file} directive |
| 4414 | @cindex logical file name |
| 4415 | @cindex file name, logical |
| 4416 | @code{.file} tells @command{@value{AS}} that we are about to start a new logical |
| 4417 | file. @var{string} is the new file name. In general, the filename is |
| 4418 | recognized whether or not it is surrounded by quotes @samp{"}; but if you wish |
| 4419 | to specify an empty file name, you must give the quotes--@code{""}. This |
| 4420 | statement may go away in future: it is only recognized to be compatible with |
| 4421 | old @command{@value{AS}} programs. |
| 4422 | @end ifclear |
| 4423 | |
| 4424 | @node Fill |
| 4425 | @section @code{.fill @var{repeat} , @var{size} , @var{value}} |
| 4426 | |
| 4427 | @cindex @code{fill} directive |
| 4428 | @cindex writing patterns in memory |
| 4429 | @cindex patterns, writing in memory |
| 4430 | @var{repeat}, @var{size} and @var{value} are absolute expressions. |
| 4431 | This emits @var{repeat} copies of @var{size} bytes. @var{Repeat} |
| 4432 | may be zero or more. @var{Size} may be zero or more, but if it is |
| 4433 | more than 8, then it is deemed to have the value 8, compatible with |
| 4434 | other people's assemblers. The contents of each @var{repeat} bytes |
| 4435 | is taken from an 8-byte number. The highest order 4 bytes are |
| 4436 | zero. The lowest order 4 bytes are @var{value} rendered in the |
| 4437 | byte-order of an integer on the computer @command{@value{AS}} is assembling for. |
| 4438 | Each @var{size} bytes in a repetition is taken from the lowest order |
| 4439 | @var{size} bytes of this number. Again, this bizarre behavior is |
| 4440 | compatible with other people's assemblers. |
| 4441 | |
| 4442 | @var{size} and @var{value} are optional. |
| 4443 | If the second comma and @var{value} are absent, @var{value} is |
| 4444 | assumed zero. If the first comma and following tokens are absent, |
| 4445 | @var{size} is assumed to be 1. |
| 4446 | |
| 4447 | @node Float |
| 4448 | @section @code{.float @var{flonums}} |
| 4449 | |
| 4450 | @cindex floating point numbers (single) |
| 4451 | @cindex @code{float} directive |
| 4452 | This directive assembles zero or more flonums, separated by commas. It |
| 4453 | has the same effect as @code{.single}. |
| 4454 | @ifset GENERIC |
| 4455 | The exact kind of floating point numbers emitted depends on how |
| 4456 | @command{@value{AS}} is configured. |
| 4457 | @xref{Machine Dependencies}. |
| 4458 | @end ifset |
| 4459 | @ifclear GENERIC |
| 4460 | @ifset IEEEFLOAT |
| 4461 | On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers |
| 4462 | in @sc{ieee} format. |
| 4463 | @end ifset |
| 4464 | @end ifclear |
| 4465 | |
| 4466 | @node Func |
| 4467 | @section @code{.func @var{name}[,@var{label}]} |
| 4468 | @cindex @code{func} directive |
| 4469 | @code{.func} emits debugging information to denote function @var{name}, and |
| 4470 | is ignored unless the file is assembled with debugging enabled. |
| 4471 | Only @samp{--gstabs[+]} is currently supported. |
| 4472 | @var{label} is the entry point of the function and if omitted @var{name} |
| 4473 | prepended with the @samp{leading char} is used. |
| 4474 | @samp{leading char} is usually @code{_} or nothing, depending on the target. |
| 4475 | All functions are currently defined to have @code{void} return type. |
| 4476 | The function must be terminated with @code{.endfunc}. |
| 4477 | |
| 4478 | @node Global |
| 4479 | @section @code{.global @var{symbol}}, @code{.globl @var{symbol}} |
| 4480 | |
| 4481 | @cindex @code{global} directive |
| 4482 | @cindex symbol, making visible to linker |
| 4483 | @code{.global} makes the symbol visible to @code{@value{LD}}. If you define |
| 4484 | @var{symbol} in your partial program, its value is made available to |
| 4485 | other partial programs that are linked with it. Otherwise, |
| 4486 | @var{symbol} takes its attributes from a symbol of the same name |
| 4487 | from another file linked into the same program. |
| 4488 | |
| 4489 | Both spellings (@samp{.globl} and @samp{.global}) are accepted, for |
| 4490 | compatibility with other assemblers. |
| 4491 | |
| 4492 | @ifset HPPA |
| 4493 | On the HPPA, @code{.global} is not always enough to make it accessible to other |
| 4494 | partial programs. You may need the HPPA-only @code{.EXPORT} directive as well. |
| 4495 | @xref{HPPA Directives,, HPPA Assembler Directives}. |
| 4496 | @end ifset |
| 4497 | |
| 4498 | @ifset ELF |
| 4499 | @node Hidden |
| 4500 | @section @code{.hidden @var{names}} |
| 4501 | |
| 4502 | @cindex @code{hidden} directive |
| 4503 | @cindex visibility |
| 4504 | This is one of the ELF visibility directives. The other two are |
| 4505 | @code{.internal} (@pxref{Internal,,@code{.internal}}) and |
| 4506 | @code{.protected} (@pxref{Protected,,@code{.protected}}). |
| 4507 | |
| 4508 | This directive overrides the named symbols default visibility (which is set by |
| 4509 | their binding: local, global or weak). The directive sets the visibility to |
| 4510 | @code{hidden} which means that the symbols are not visible to other components. |
| 4511 | Such symbols are always considered to be @code{protected} as well. |
| 4512 | @end ifset |
| 4513 | |
| 4514 | @node hword |
| 4515 | @section @code{.hword @var{expressions}} |
| 4516 | |
| 4517 | @cindex @code{hword} directive |
| 4518 | @cindex integers, 16-bit |
| 4519 | @cindex numbers, 16-bit |
| 4520 | @cindex sixteen bit integers |
| 4521 | This expects zero or more @var{expressions}, and emits |
| 4522 | a 16 bit number for each. |
| 4523 | |
| 4524 | @ifset GENERIC |
| 4525 | This directive is a synonym for @samp{.short}; depending on the target |
| 4526 | architecture, it may also be a synonym for @samp{.word}. |
| 4527 | @end ifset |
| 4528 | @ifclear GENERIC |
| 4529 | @ifset W32 |
| 4530 | This directive is a synonym for @samp{.short}. |
| 4531 | @end ifset |
| 4532 | @ifset W16 |
| 4533 | This directive is a synonym for both @samp{.short} and @samp{.word}. |
| 4534 | @end ifset |
| 4535 | @end ifclear |
| 4536 | |
| 4537 | @node Ident |
| 4538 | @section @code{.ident} |
| 4539 | |
| 4540 | @cindex @code{ident} directive |
| 4541 | |
| 4542 | This directive is used by some assemblers to place tags in object files. The |
| 4543 | behavior of this directive varies depending on the target. When using the |
| 4544 | a.out object file format, @command{@value{AS}} simply accepts the directive for |
| 4545 | source-file compatibility with existing assemblers, but does not emit anything |
| 4546 | for it. When using COFF, comments are emitted to the @code{.comment} or |
| 4547 | @code{.rdata} section, depending on the target. When using ELF, comments are |
| 4548 | emitted to the @code{.comment} section. |
| 4549 | |
| 4550 | @node If |
| 4551 | @section @code{.if @var{absolute expression}} |
| 4552 | |
| 4553 | @cindex conditional assembly |
| 4554 | @cindex @code{if} directive |
| 4555 | @code{.if} marks the beginning of a section of code which is only |
| 4556 | considered part of the source program being assembled if the argument |
| 4557 | (which must be an @var{absolute expression}) is non-zero. The end of |
| 4558 | the conditional section of code must be marked by @code{.endif} |
| 4559 | (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the |
| 4560 | alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}). |
| 4561 | If you have several conditions to check, @code{.elseif} may be used to avoid |
| 4562 | nesting blocks if/else within each subsequent @code{.else} block. |
| 4563 | |
| 4564 | The following variants of @code{.if} are also supported: |
| 4565 | @table @code |
| 4566 | @cindex @code{ifdef} directive |
| 4567 | @item .ifdef @var{symbol} |
| 4568 | Assembles the following section of code if the specified @var{symbol} |
| 4569 | has been defined. Note a symbol which has been referenced but not yet defined |
| 4570 | is considered to be undefined. |
| 4571 | |
| 4572 | @cindex @code{ifb} directive |
| 4573 | @item .ifb @var{text} |
| 4574 | Assembles the following section of code if the operand is blank (empty). |
| 4575 | |
| 4576 | @cindex @code{ifc} directive |
| 4577 | @item .ifc @var{string1},@var{string2} |
| 4578 | Assembles the following section of code if the two strings are the same. The |
| 4579 | strings may be optionally quoted with single quotes. If they are not quoted, |
| 4580 | the first string stops at the first comma, and the second string stops at the |
| 4581 | end of the line. Strings which contain whitespace should be quoted. The |
| 4582 | string comparison is case sensitive. |
| 4583 | |
| 4584 | @cindex @code{ifeq} directive |
| 4585 | @item .ifeq @var{absolute expression} |
| 4586 | Assembles the following section of code if the argument is zero. |
| 4587 | |
| 4588 | @cindex @code{ifeqs} directive |
| 4589 | @item .ifeqs @var{string1},@var{string2} |
| 4590 | Another form of @code{.ifc}. The strings must be quoted using double quotes. |
| 4591 | |
| 4592 | @cindex @code{ifge} directive |
| 4593 | @item .ifge @var{absolute expression} |
| 4594 | Assembles the following section of code if the argument is greater than or |
| 4595 | equal to zero. |
| 4596 | |
| 4597 | @cindex @code{ifgt} directive |
| 4598 | @item .ifgt @var{absolute expression} |
| 4599 | Assembles the following section of code if the argument is greater than zero. |
| 4600 | |
| 4601 | @cindex @code{ifle} directive |
| 4602 | @item .ifle @var{absolute expression} |
| 4603 | Assembles the following section of code if the argument is less than or equal |
| 4604 | to zero. |
| 4605 | |
| 4606 | @cindex @code{iflt} directive |
| 4607 | @item .iflt @var{absolute expression} |
| 4608 | Assembles the following section of code if the argument is less than zero. |
| 4609 | |
| 4610 | @cindex @code{ifnb} directive |
| 4611 | @item .ifnb @var{text} |
| 4612 | Like @code{.ifb}, but the sense of the test is reversed: this assembles the |
| 4613 | following section of code if the operand is non-blank (non-empty). |
| 4614 | |
| 4615 | @cindex @code{ifnc} directive |
| 4616 | @item .ifnc @var{string1},@var{string2}. |
| 4617 | Like @code{.ifc}, but the sense of the test is reversed: this assembles the |
| 4618 | following section of code if the two strings are not the same. |
| 4619 | |
| 4620 | @cindex @code{ifndef} directive |
| 4621 | @cindex @code{ifnotdef} directive |
| 4622 | @item .ifndef @var{symbol} |
| 4623 | @itemx .ifnotdef @var{symbol} |
| 4624 | Assembles the following section of code if the specified @var{symbol} |
| 4625 | has not been defined. Both spelling variants are equivalent. Note a symbol |
| 4626 | which has been referenced but not yet defined is considered to be undefined. |
| 4627 | |
| 4628 | @cindex @code{ifne} directive |
| 4629 | @item .ifne @var{absolute expression} |
| 4630 | Assembles the following section of code if the argument is not equal to zero |
| 4631 | (in other words, this is equivalent to @code{.if}). |
| 4632 | |
| 4633 | @cindex @code{ifnes} directive |
| 4634 | @item .ifnes @var{string1},@var{string2} |
| 4635 | Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the |
| 4636 | following section of code if the two strings are not the same. |
| 4637 | @end table |
| 4638 | |
| 4639 | @node Incbin |
| 4640 | @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]} |
| 4641 | |
| 4642 | @cindex @code{incbin} directive |
| 4643 | @cindex binary files, including |
| 4644 | The @code{incbin} directive includes @var{file} verbatim at the current |
| 4645 | location. You can control the search paths used with the @samp{-I} command-line |
| 4646 | option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required |
| 4647 | around @var{file}. |
| 4648 | |
| 4649 | The @var{skip} argument skips a number of bytes from the start of the |
| 4650 | @var{file}. The @var{count} argument indicates the maximum number of bytes to |
| 4651 | read. Note that the data is not aligned in any way, so it is the user's |
| 4652 | responsibility to make sure that proper alignment is provided both before and |
| 4653 | after the @code{incbin} directive. |
| 4654 | |
| 4655 | @node Include |
| 4656 | @section @code{.include "@var{file}"} |
| 4657 | |
| 4658 | @cindex @code{include} directive |
| 4659 | @cindex supporting files, including |
| 4660 | @cindex files, including |
| 4661 | This directive provides a way to include supporting files at specified |
| 4662 | points in your source program. The code from @var{file} is assembled as |
| 4663 | if it followed the point of the @code{.include}; when the end of the |
| 4664 | included file is reached, assembly of the original file continues. You |
| 4665 | can control the search paths used with the @samp{-I} command-line option |
| 4666 | (@pxref{Invoking,,Command-Line Options}). Quotation marks are required |
| 4667 | around @var{file}. |
| 4668 | |
| 4669 | @node Int |
| 4670 | @section @code{.int @var{expressions}} |
| 4671 | |
| 4672 | @cindex @code{int} directive |
| 4673 | @cindex integers, 32-bit |
| 4674 | Expect zero or more @var{expressions}, of any section, separated by commas. |
| 4675 | For each expression, emit a number that, at run time, is the value of that |
| 4676 | expression. The byte order and bit size of the number depends on what kind |
| 4677 | of target the assembly is for. |
| 4678 | |
| 4679 | @ifclear GENERIC |
| 4680 | @ifset H8 |
| 4681 | On most forms of the H8/300, @code{.int} emits 16-bit |
| 4682 | integers. On the H8/300H and the Renesas SH, however, @code{.int} emits |
| 4683 | 32-bit integers. |
| 4684 | @end ifset |
| 4685 | @end ifclear |
| 4686 | |
| 4687 | @ifset ELF |
| 4688 | @node Internal |
| 4689 | @section @code{.internal @var{names}} |
| 4690 | |
| 4691 | @cindex @code{internal} directive |
| 4692 | @cindex visibility |
| 4693 | This is one of the ELF visibility directives. The other two are |
| 4694 | @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and |
| 4695 | @code{.protected} (@pxref{Protected,,@code{.protected}}). |
| 4696 | |
| 4697 | This directive overrides the named symbols default visibility (which is set by |
| 4698 | their binding: local, global or weak). The directive sets the visibility to |
| 4699 | @code{internal} which means that the symbols are considered to be @code{hidden} |
| 4700 | (i.e., not visible to other components), and that some extra, processor specific |
| 4701 | processing must also be performed upon the symbols as well. |
| 4702 | @end ifset |
| 4703 | |
| 4704 | @node Irp |
| 4705 | @section @code{.irp @var{symbol},@var{values}}@dots{} |
| 4706 | |
| 4707 | @cindex @code{irp} directive |
| 4708 | Evaluate a sequence of statements assigning different values to @var{symbol}. |
| 4709 | The sequence of statements starts at the @code{.irp} directive, and is |
| 4710 | terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is |
| 4711 | set to @var{value}, and the sequence of statements is assembled. If no |
| 4712 | @var{value} is listed, the sequence of statements is assembled once, with |
| 4713 | @var{symbol} set to the null string. To refer to @var{symbol} within the |
| 4714 | sequence of statements, use @var{\symbol}. |
| 4715 | |
| 4716 | For example, assembling |
| 4717 | |
| 4718 | @example |
| 4719 | .irp param,1,2,3 |
| 4720 | move d\param,sp@@- |
| 4721 | .endr |
| 4722 | @end example |
| 4723 | |
| 4724 | is equivalent to assembling |
| 4725 | |
| 4726 | @example |
| 4727 | move d1,sp@@- |
| 4728 | move d2,sp@@- |
| 4729 | move d3,sp@@- |
| 4730 | @end example |
| 4731 | |
| 4732 | For some caveats with the spelling of @var{symbol}, see also the discussion |
| 4733 | at @xref{Macro}. |
| 4734 | |
| 4735 | @node Irpc |
| 4736 | @section @code{.irpc @var{symbol},@var{values}}@dots{} |
| 4737 | |
| 4738 | @cindex @code{irpc} directive |
| 4739 | Evaluate a sequence of statements assigning different values to @var{symbol}. |
| 4740 | The sequence of statements starts at the @code{.irpc} directive, and is |
| 4741 | terminated by an @code{.endr} directive. For each character in @var{value}, |
| 4742 | @var{symbol} is set to the character, and the sequence of statements is |
| 4743 | assembled. If no @var{value} is listed, the sequence of statements is |
| 4744 | assembled once, with @var{symbol} set to the null string. To refer to |
| 4745 | @var{symbol} within the sequence of statements, use @var{\symbol}. |
| 4746 | |
| 4747 | For example, assembling |
| 4748 | |
| 4749 | @example |
| 4750 | .irpc param,123 |
| 4751 | move d\param,sp@@- |
| 4752 | .endr |
| 4753 | @end example |
| 4754 | |
| 4755 | is equivalent to assembling |
| 4756 | |
| 4757 | @example |
| 4758 | move d1,sp@@- |
| 4759 | move d2,sp@@- |
| 4760 | move d3,sp@@- |
| 4761 | @end example |
| 4762 | |
| 4763 | For some caveats with the spelling of @var{symbol}, see also the discussion |
| 4764 | at @xref{Macro}. |
| 4765 | |
| 4766 | @node Lcomm |
| 4767 | @section @code{.lcomm @var{symbol} , @var{length}} |
| 4768 | |
| 4769 | @cindex @code{lcomm} directive |
| 4770 | @cindex local common symbols |
| 4771 | @cindex symbols, local common |
| 4772 | Reserve @var{length} (an absolute expression) bytes for a local common |
| 4773 | denoted by @var{symbol}. The section and value of @var{symbol} are |
| 4774 | those of the new local common. The addresses are allocated in the bss |
| 4775 | section, so that at run-time the bytes start off zeroed. @var{Symbol} |
| 4776 | is not declared global (@pxref{Global,,@code{.global}}), so is normally |
| 4777 | not visible to @code{@value{LD}}. |
| 4778 | |
| 4779 | @ifset GENERIC |
| 4780 | Some targets permit a third argument to be used with @code{.lcomm}. This |
| 4781 | argument specifies the desired alignment of the symbol in the bss section. |
| 4782 | @end ifset |
| 4783 | |
| 4784 | @ifset HPPA |
| 4785 | The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is |
| 4786 | @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional. |
| 4787 | @end ifset |
| 4788 | |
| 4789 | @node Lflags |
| 4790 | @section @code{.lflags} |
| 4791 | |
| 4792 | @cindex @code{lflags} directive (ignored) |
| 4793 | @command{@value{AS}} accepts this directive, for compatibility with other |
| 4794 | assemblers, but ignores it. |
| 4795 | |
| 4796 | @ifclear no-line-dir |
| 4797 | @node Line |
| 4798 | @section @code{.line @var{line-number}} |
| 4799 | |
| 4800 | @cindex @code{line} directive |
| 4801 | @end ifclear |
| 4802 | @ifset no-line-dir |
| 4803 | @node Ln |
| 4804 | @section @code{.ln @var{line-number}} |
| 4805 | |
| 4806 | @cindex @code{ln} directive |
| 4807 | @end ifset |
| 4808 | @cindex logical line number |
| 4809 | @ifset aout-bout |
| 4810 | Change the logical line number. @var{line-number} must be an absolute |
| 4811 | expression. The next line has that logical line number. Therefore any other |
| 4812 | statements on the current line (after a statement separator character) are |
| 4813 | reported as on logical line number @var{line-number} @minus{} 1. One day |
| 4814 | @command{@value{AS}} will no longer support this directive: it is recognized only |
| 4815 | for compatibility with existing assembler programs. |
| 4816 | |
| 4817 | @end ifset |
| 4818 | |
| 4819 | @ifclear no-line-dir |
| 4820 | Even though this is a directive associated with the @code{a.out} or |
| 4821 | @code{b.out} object-code formats, @command{@value{AS}} still recognizes it |
| 4822 | when producing COFF output, and treats @samp{.line} as though it |
| 4823 | were the COFF @samp{.ln} @emph{if} it is found outside a |
| 4824 | @code{.def}/@code{.endef} pair. |
| 4825 | |
| 4826 | Inside a @code{.def}, @samp{.line} is, instead, one of the directives |
| 4827 | used by compilers to generate auxiliary symbol information for |
| 4828 | debugging. |
| 4829 | @end ifclear |
| 4830 | |
| 4831 | @node Linkonce |
| 4832 | @section @code{.linkonce [@var{type}]} |
| 4833 | @cindex COMDAT |
| 4834 | @cindex @code{linkonce} directive |
| 4835 | @cindex common sections |
| 4836 | Mark the current section so that the linker only includes a single copy of it. |
| 4837 | This may be used to include the same section in several different object files, |
| 4838 | but ensure that the linker will only include it once in the final output file. |
| 4839 | The @code{.linkonce} pseudo-op must be used for each instance of the section. |
| 4840 | Duplicate sections are detected based on the section name, so it should be |
| 4841 | unique. |
| 4842 | |
| 4843 | This directive is only supported by a few object file formats; as of this |
| 4844 | writing, the only object file format which supports it is the Portable |
| 4845 | Executable format used on Windows NT. |
| 4846 | |
| 4847 | The @var{type} argument is optional. If specified, it must be one of the |
| 4848 | following strings. For example: |
| 4849 | @smallexample |
| 4850 | .linkonce same_size |
| 4851 | @end smallexample |
| 4852 | Not all types may be supported on all object file formats. |
| 4853 | |
| 4854 | @table @code |
| 4855 | @item discard |
| 4856 | Silently discard duplicate sections. This is the default. |
| 4857 | |
| 4858 | @item one_only |
| 4859 | Warn if there are duplicate sections, but still keep only one copy. |
| 4860 | |
| 4861 | @item same_size |
| 4862 | Warn if any of the duplicates have different sizes. |
| 4863 | |
| 4864 | @item same_contents |
| 4865 | Warn if any of the duplicates do not have exactly the same contents. |
| 4866 | @end table |
| 4867 | |
| 4868 | @node Ln |
| 4869 | @section @code{.ln @var{line-number}} |
| 4870 | |
| 4871 | @cindex @code{ln} directive |
| 4872 | @ifclear no-line-dir |
| 4873 | @samp{.ln} is a synonym for @samp{.line}. |
| 4874 | @end ifclear |
| 4875 | @ifset no-line-dir |
| 4876 | Tell @command{@value{AS}} to change the logical line number. @var{line-number} |
| 4877 | must be an absolute expression. The next line has that logical |
| 4878 | line number, so any other statements on the current line (after a |
| 4879 | statement separator character @code{;}) are reported as on logical |
| 4880 | line number @var{line-number} @minus{} 1. |
| 4881 | @ifset BOUT |
| 4882 | |
| 4883 | This directive is accepted, but ignored, when @command{@value{AS}} is |
| 4884 | configured for @code{b.out}; its effect is only associated with COFF |
| 4885 | output format. |
| 4886 | @end ifset |
| 4887 | @end ifset |
| 4888 | |
| 4889 | @node MRI |
| 4890 | @section @code{.mri @var{val}} |
| 4891 | |
| 4892 | @cindex @code{mri} directive |
| 4893 | @cindex MRI mode, temporarily |
| 4894 | If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If |
| 4895 | @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change |
| 4896 | affects code assembled until the next @code{.mri} directive, or until the end |
| 4897 | of the file. @xref{M, MRI mode, MRI mode}. |
| 4898 | |
| 4899 | @node List |
| 4900 | @section @code{.list} |
| 4901 | |
| 4902 | @cindex @code{list} directive |
| 4903 | @cindex listing control, turning on |
| 4904 | Control (in conjunction with the @code{.nolist} directive) whether or |
| 4905 | not assembly listings are generated. These two directives maintain an |
| 4906 | internal counter (which is zero initially). @code{.list} increments the |
| 4907 | counter, and @code{.nolist} decrements it. Assembly listings are |
| 4908 | generated whenever the counter is greater than zero. |
| 4909 | |
| 4910 | By default, listings are disabled. When you enable them (with the |
| 4911 | @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}), |
| 4912 | the initial value of the listing counter is one. |
| 4913 | |
| 4914 | @node Long |
| 4915 | @section @code{.long @var{expressions}} |
| 4916 | |
| 4917 | @cindex @code{long} directive |
| 4918 | @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}. |
| 4919 | |
| 4920 | @ignore |
| 4921 | @c no one seems to know what this is for or whether this description is |
| 4922 | @c what it really ought to do |
| 4923 | @node Lsym |
| 4924 | @section @code{.lsym @var{symbol}, @var{expression}} |
| 4925 | |
| 4926 | @cindex @code{lsym} directive |
| 4927 | @cindex symbol, not referenced in assembly |
| 4928 | @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in |
| 4929 | the hash table, ensuring it cannot be referenced by name during the |
| 4930 | rest of the assembly. This sets the attributes of the symbol to be |
| 4931 | the same as the expression value: |
| 4932 | @smallexample |
| 4933 | @var{other} = @var{descriptor} = 0 |
| 4934 | @var{type} = @r{(section of @var{expression})} |
| 4935 | @var{value} = @var{expression} |
| 4936 | @end smallexample |
| 4937 | @noindent |
| 4938 | The new symbol is not flagged as external. |
| 4939 | @end ignore |
| 4940 | |
| 4941 | @node Macro |
| 4942 | @section @code{.macro} |
| 4943 | |
| 4944 | @cindex macros |
| 4945 | The commands @code{.macro} and @code{.endm} allow you to define macros that |
| 4946 | generate assembly output. For example, this definition specifies a macro |
| 4947 | @code{sum} that puts a sequence of numbers into memory: |
| 4948 | |
| 4949 | @example |
| 4950 | .macro sum from=0, to=5 |
| 4951 | .long \from |
| 4952 | .if \to-\from |
| 4953 | sum "(\from+1)",\to |
| 4954 | .endif |
| 4955 | .endm |
| 4956 | @end example |
| 4957 | |
| 4958 | @noindent |
| 4959 | With that definition, @samp{SUM 0,5} is equivalent to this assembly input: |
| 4960 | |
| 4961 | @example |
| 4962 | .long 0 |
| 4963 | .long 1 |
| 4964 | .long 2 |
| 4965 | .long 3 |
| 4966 | .long 4 |
| 4967 | .long 5 |
| 4968 | @end example |
| 4969 | |
| 4970 | @ftable @code |
| 4971 | @item .macro @var{macname} |
| 4972 | @itemx .macro @var{macname} @var{macargs} @dots{} |
| 4973 | @cindex @code{macro} directive |
| 4974 | Begin the definition of a macro called @var{macname}. If your macro |
| 4975 | definition requires arguments, specify their names after the macro name, |
| 4976 | separated by commas or spaces. You can qualify the macro argument to |
| 4977 | indicate whether all invocations must specify a non-blank value (through |
| 4978 | @samp{:@code{req}}), or whether it takes all of the remaining arguments |
| 4979 | (through @samp{:@code{vararg}}). You can supply a default value for any |
| 4980 | macro argument by following the name with @samp{=@var{deflt}}. You |
| 4981 | cannot define two macros with the same @var{macname} unless it has been |
| 4982 | subject to the @code{.purgem} directive (@xref{Purgem}.) between the two |
| 4983 | definitions. For example, these are all valid @code{.macro} statements: |
| 4984 | |
| 4985 | @table @code |
| 4986 | @item .macro comm |
| 4987 | Begin the definition of a macro called @code{comm}, which takes no |
| 4988 | arguments. |
| 4989 | |
| 4990 | @item .macro plus1 p, p1 |
| 4991 | @itemx .macro plus1 p p1 |
| 4992 | Either statement begins the definition of a macro called @code{plus1}, |
| 4993 | which takes two arguments; within the macro definition, write |
| 4994 | @samp{\p} or @samp{\p1} to evaluate the arguments. |
| 4995 | |
| 4996 | @item .macro reserve_str p1=0 p2 |
| 4997 | Begin the definition of a macro called @code{reserve_str}, with two |
| 4998 | arguments. The first argument has a default value, but not the second. |
| 4999 | After the definition is complete, you can call the macro either as |
| 5000 | @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to |
| 5001 | @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str |
| 5002 | ,@var{b}} (with @samp{\p1} evaluating as the default, in this case |
| 5003 | @samp{0}, and @samp{\p2} evaluating to @var{b}). |
| 5004 | @end table |
| 5005 | |
| 5006 | @item .macro m p1:req, p2=0, p3:vararg |
| 5007 | Begin the definition of a macro called @code{m}, with at least three |
| 5008 | arguments. The first argument must always have a value specified, but |
| 5009 | not the second, which instead has a default value. The third formal |
| 5010 | will get assigned all remaining arguments specified at invocation time. |
| 5011 | |
| 5012 | When you call a macro, you can specify the argument values either by |
| 5013 | position, or by keyword. For example, @samp{sum 9,17} is equivalent to |
| 5014 | @samp{sum to=17, from=9}. |
| 5015 | |
| 5016 | Note that since each of the @var{macargs} can be an identifier exactly |
| 5017 | as any other one permitted by the target architecture, there may be |
| 5018 | occasional problems if the target hand-crafts special meanings to certain |
| 5019 | characters when they occur in a special position. For example, if colon |
| 5020 | (@code{:}) is generally permitted to be part of a symbol name, but the |
| 5021 | architecture specific code special-cases it when occuring as the final |
| 5022 | character of a symbol (to denote a label), then the macro parameter |
| 5023 | replacement code will have no way of knowing that and consider the whole |
| 5024 | construct (including the colon) an identifier, and check only this |
| 5025 | identifier for being the subject to parameter substitution. In this |
| 5026 | example, besides the potential of just separating identifier and colon |
| 5027 | by white space, using alternate macro syntax (@xref{Altmacro}.) and |
| 5028 | ampersand (@code{&}) as the character to separate literal text from macro |
| 5029 | parameters (or macro parameters from one another) would provide a way to |
| 5030 | achieve the same effect: |
| 5031 | |
| 5032 | @example |
| 5033 | .altmacro |
| 5034 | .macro label l |
| 5035 | l&: |
| 5036 | .endm |
| 5037 | @end example |
| 5038 | |
| 5039 | This applies identically to the identifiers used in @code{.irp} (@xref{Irp}.) |
| 5040 | and @code{.irpc} (@xref{Irpc}.). |
| 5041 | |
| 5042 | @item .endm |
| 5043 | @cindex @code{endm} directive |
| 5044 | Mark the end of a macro definition. |
| 5045 | |
| 5046 | @item .exitm |
| 5047 | @cindex @code{exitm} directive |
| 5048 | Exit early from the current macro definition. |
| 5049 | |
| 5050 | @cindex number of macros executed |
| 5051 | @cindex macros, count executed |
| 5052 | @item \@@ |
| 5053 | @command{@value{AS}} maintains a counter of how many macros it has |
| 5054 | executed in this pseudo-variable; you can copy that number to your |
| 5055 | output with @samp{\@@}, but @emph{only within a macro definition}. |
| 5056 | |
| 5057 | @item LOCAL @var{name} [ , @dots{} ] |
| 5058 | @emph{Warning: @code{LOCAL} is only available if you select ``alternate |
| 5059 | macro syntax'' with @samp{--alternate} or @code{.altmacro}.} |
| 5060 | @xref{Altmacro,,@code{.altmacro}}. |
| 5061 | @end ftable |
| 5062 | |
| 5063 | @node Altmacro |
| 5064 | @section @code{.altmacro} |
| 5065 | Enable alternate macro mode, enabling: |
| 5066 | |
| 5067 | @ftable @code |
| 5068 | @item LOCAL @var{name} [ , @dots{} ] |
| 5069 | One additional directive, @code{LOCAL}, is available. It is used to |
| 5070 | generate a string replacement for each of the @var{name} arguments, and |
| 5071 | replace any instances of @var{name} in each macro expansion. The |
| 5072 | replacement string is unique in the assembly, and different for each |
| 5073 | separate macro expansion. @code{LOCAL} allows you to write macros that |
| 5074 | define symbols, without fear of conflict between separate macro expansions. |
| 5075 | |
| 5076 | @item String delimiters |
| 5077 | You can write strings delimited in these other ways besides |
| 5078 | @code{"@var{string}"}: |
| 5079 | |
| 5080 | @table @code |
| 5081 | @item '@var{string}' |
| 5082 | You can delimit strings with single-quote charaters. |
| 5083 | |
| 5084 | @item <@var{string}> |
| 5085 | You can delimit strings with matching angle brackets. |
| 5086 | @end table |
| 5087 | |
| 5088 | @item single-character string escape |
| 5089 | To include any single character literally in a string (even if the |
| 5090 | character would otherwise have some special meaning), you can prefix the |
| 5091 | character with @samp{!} (an exclamation mark). For example, you can |
| 5092 | write @samp{<4.3 !> 5.4!!>} to get the literal text @samp{4.3 > 5.4!}. |
| 5093 | |
| 5094 | @item Expression results as strings |
| 5095 | You can write @samp{%@var{expr}} to evaluate the expression @var{expr} |
| 5096 | and use the result as a string. |
| 5097 | @end ftable |
| 5098 | |
| 5099 | @node Noaltmacro |
| 5100 | @section @code{.noaltmacro} |
| 5101 | Disable alternate macro mode. @ref{Altmacro} |
| 5102 | |
| 5103 | @node Nolist |
| 5104 | @section @code{.nolist} |
| 5105 | |
| 5106 | @cindex @code{nolist} directive |
| 5107 | @cindex listing control, turning off |
| 5108 | Control (in conjunction with the @code{.list} directive) whether or |
| 5109 | not assembly listings are generated. These two directives maintain an |
| 5110 | internal counter (which is zero initially). @code{.list} increments the |
| 5111 | counter, and @code{.nolist} decrements it. Assembly listings are |
| 5112 | generated whenever the counter is greater than zero. |
| 5113 | |
| 5114 | @node Octa |
| 5115 | @section @code{.octa @var{bignums}} |
| 5116 | |
| 5117 | @c FIXME: double size emitted for "octa" on i960, others? Or warn? |
| 5118 | @cindex @code{octa} directive |
| 5119 | @cindex integer, 16-byte |
| 5120 | @cindex sixteen byte integer |
| 5121 | This directive expects zero or more bignums, separated by commas. For each |
| 5122 | bignum, it emits a 16-byte integer. |
| 5123 | |
| 5124 | The term ``octa'' comes from contexts in which a ``word'' is two bytes; |
| 5125 | hence @emph{octa}-word for 16 bytes. |
| 5126 | |
| 5127 | @node Org |
| 5128 | @section @code{.org @var{new-lc} , @var{fill}} |
| 5129 | |
| 5130 | @cindex @code{org} directive |
| 5131 | @cindex location counter, advancing |
| 5132 | @cindex advancing location counter |
| 5133 | @cindex current address, advancing |
| 5134 | Advance the location counter of the current section to |
| 5135 | @var{new-lc}. @var{new-lc} is either an absolute expression or an |
| 5136 | expression with the same section as the current subsection. That is, |
| 5137 | you can't use @code{.org} to cross sections: if @var{new-lc} has the |
| 5138 | wrong section, the @code{.org} directive is ignored. To be compatible |
| 5139 | with former assemblers, if the section of @var{new-lc} is absolute, |
| 5140 | @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc} |
| 5141 | is the same as the current subsection. |
| 5142 | |
| 5143 | @code{.org} may only increase the location counter, or leave it |
| 5144 | unchanged; you cannot use @code{.org} to move the location counter |
| 5145 | backwards. |
| 5146 | |
| 5147 | @c double negative used below "not undefined" because this is a specific |
| 5148 | @c reference to "undefined" (as SEG_UNKNOWN is called in this manual) |
| 5149 | @c section. doc@cygnus.com 18feb91 |
| 5150 | Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc} |
| 5151 | may not be undefined. If you really detest this restriction we eagerly await |
| 5152 | a chance to share your improved assembler. |
| 5153 | |
| 5154 | Beware that the origin is relative to the start of the section, not |
| 5155 | to the start of the subsection. This is compatible with other |
| 5156 | people's assemblers. |
| 5157 | |
| 5158 | When the location counter (of the current subsection) is advanced, the |
| 5159 | intervening bytes are filled with @var{fill} which should be an |
| 5160 | absolute expression. If the comma and @var{fill} are omitted, |
| 5161 | @var{fill} defaults to zero. |
| 5162 | |
| 5163 | @node P2align |
| 5164 | @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} |
| 5165 | |
| 5166 | @cindex padding the location counter given a power of two |
| 5167 | @cindex @code{p2align} directive |
| 5168 | Pad the location counter (in the current subsection) to a particular |
| 5169 | storage boundary. The first expression (which must be absolute) is the |
| 5170 | number of low-order zero bits the location counter must have after |
| 5171 | advancement. For example @samp{.p2align 3} advances the location |
| 5172 | counter until it a multiple of 8. If the location counter is already a |
| 5173 | multiple of 8, no change is needed. |
| 5174 | |
| 5175 | The second expression (also absolute) gives the fill value to be stored in the |
| 5176 | padding bytes. It (and the comma) may be omitted. If it is omitted, the |
| 5177 | padding bytes are normally zero. However, on some systems, if the section is |
| 5178 | marked as containing code and the fill value is omitted, the space is filled |
| 5179 | with no-op instructions. |
| 5180 | |
| 5181 | The third expression is also absolute, and is also optional. If it is present, |
| 5182 | it is the maximum number of bytes that should be skipped by this alignment |
| 5183 | directive. If doing the alignment would require skipping more bytes than the |
| 5184 | specified maximum, then the alignment is not done at all. You can omit the |
| 5185 | fill value (the second argument) entirely by simply using two commas after the |
| 5186 | required alignment; this can be useful if you want the alignment to be filled |
| 5187 | with no-op instructions when appropriate. |
| 5188 | |
| 5189 | @cindex @code{p2alignw} directive |
| 5190 | @cindex @code{p2alignl} directive |
| 5191 | The @code{.p2alignw} and @code{.p2alignl} directives are variants of the |
| 5192 | @code{.p2align} directive. The @code{.p2alignw} directive treats the fill |
| 5193 | pattern as a two byte word value. The @code{.p2alignl} directives treats the |
| 5194 | fill pattern as a four byte longword value. For example, @code{.p2alignw |
| 5195 | 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be |
| 5196 | filled in with the value 0x368d (the exact placement of the bytes depends upon |
| 5197 | the endianness of the processor). If it skips 1 or 3 bytes, the fill value is |
| 5198 | undefined. |
| 5199 | |
| 5200 | @ifset ELF |
| 5201 | @node Previous |
| 5202 | @section @code{.previous} |
| 5203 | |
| 5204 | @cindex @code{previous} directive |
| 5205 | @cindex Section Stack |
| 5206 | This is one of the ELF section stack manipulation directives. The others are |
| 5207 | @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}), |
| 5208 | @code{.pushsection} (@pxref{PushSection}), and @code{.popsection} |
| 5209 | (@pxref{PopSection}). |
| 5210 | |
| 5211 | This directive swaps the current section (and subsection) with most recently |
| 5212 | referenced section (and subsection) prior to this one. Multiple |
| 5213 | @code{.previous} directives in a row will flip between two sections (and their |
| 5214 | subsections). |
| 5215 | |
| 5216 | In terms of the section stack, this directive swaps the current section with |
| 5217 | the top section on the section stack. |
| 5218 | @end ifset |
| 5219 | |
| 5220 | @ifset ELF |
| 5221 | @node PopSection |
| 5222 | @section @code{.popsection} |
| 5223 | |
| 5224 | @cindex @code{popsection} directive |
| 5225 | @cindex Section Stack |
| 5226 | This is one of the ELF section stack manipulation directives. The others are |
| 5227 | @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}), |
| 5228 | @code{.pushsection} (@pxref{PushSection}), and @code{.previous} |
| 5229 | (@pxref{Previous}). |
| 5230 | |
| 5231 | This directive replaces the current section (and subsection) with the top |
| 5232 | section (and subsection) on the section stack. This section is popped off the |
| 5233 | stack. |
| 5234 | @end ifset |
| 5235 | |
| 5236 | @node Print |
| 5237 | @section @code{.print @var{string}} |
| 5238 | |
| 5239 | @cindex @code{print} directive |
| 5240 | @command{@value{AS}} will print @var{string} on the standard output during |
| 5241 | assembly. You must put @var{string} in double quotes. |
| 5242 | |
| 5243 | @ifset ELF |
| 5244 | @node Protected |
| 5245 | @section @code{.protected @var{names}} |
| 5246 | |
| 5247 | @cindex @code{protected} directive |
| 5248 | @cindex visibility |
| 5249 | This is one of the ELF visibility directives. The other two are |
| 5250 | @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}). |
| 5251 | |
| 5252 | This directive overrides the named symbols default visibility (which is set by |
| 5253 | their binding: local, global or weak). The directive sets the visibility to |
| 5254 | @code{protected} which means that any references to the symbols from within the |
| 5255 | components that defines them must be resolved to the definition in that |
| 5256 | component, even if a definition in another component would normally preempt |
| 5257 | this. |
| 5258 | @end ifset |
| 5259 | |
| 5260 | @node Psize |
| 5261 | @section @code{.psize @var{lines} , @var{columns}} |
| 5262 | |
| 5263 | @cindex @code{psize} directive |
| 5264 | @cindex listing control: paper size |
| 5265 | @cindex paper size, for listings |
| 5266 | Use this directive to declare the number of lines---and, optionally, the |
| 5267 | number of columns---to use for each page, when generating listings. |
| 5268 | |
| 5269 | If you do not use @code{.psize}, listings use a default line-count |
| 5270 | of 60. You may omit the comma and @var{columns} specification; the |
| 5271 | default width is 200 columns. |
| 5272 | |
| 5273 | @command{@value{AS}} generates formfeeds whenever the specified number of |
| 5274 | lines is exceeded (or whenever you explicitly request one, using |
| 5275 | @code{.eject}). |
| 5276 | |
| 5277 | If you specify @var{lines} as @code{0}, no formfeeds are generated save |
| 5278 | those explicitly specified with @code{.eject}. |
| 5279 | |
| 5280 | @node Purgem |
| 5281 | @section @code{.purgem @var{name}} |
| 5282 | |
| 5283 | @cindex @code{purgem} directive |
| 5284 | Undefine the macro @var{name}, so that later uses of the string will not be |
| 5285 | expanded. @xref{Macro}. |
| 5286 | |
| 5287 | @ifset ELF |
| 5288 | @node PushSection |
| 5289 | @section @code{.pushsection @var{name} , @var{subsection}} |
| 5290 | |
| 5291 | @cindex @code{pushsection} directive |
| 5292 | @cindex Section Stack |
| 5293 | This is one of the ELF section stack manipulation directives. The others are |
| 5294 | @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}), |
| 5295 | @code{.popsection} (@pxref{PopSection}), and @code{.previous} |
| 5296 | (@pxref{Previous}). |
| 5297 | |
| 5298 | This directive pushes the current section (and subsection) onto the |
| 5299 | top of the section stack, and then replaces the current section and |
| 5300 | subsection with @code{name} and @code{subsection}. |
| 5301 | @end ifset |
| 5302 | |
| 5303 | @node Quad |
| 5304 | @section @code{.quad @var{bignums}} |
| 5305 | |
| 5306 | @cindex @code{quad} directive |
| 5307 | @code{.quad} expects zero or more bignums, separated by commas. For |
| 5308 | each bignum, it emits |
| 5309 | @ifclear bignum-16 |
| 5310 | an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a |
| 5311 | warning message; and just takes the lowest order 8 bytes of the bignum. |
| 5312 | @cindex eight-byte integer |
| 5313 | @cindex integer, 8-byte |
| 5314 | |
| 5315 | The term ``quad'' comes from contexts in which a ``word'' is two bytes; |
| 5316 | hence @emph{quad}-word for 8 bytes. |
| 5317 | @end ifclear |
| 5318 | @ifset bignum-16 |
| 5319 | a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a |
| 5320 | warning message; and just takes the lowest order 16 bytes of the bignum. |
| 5321 | @cindex sixteen-byte integer |
| 5322 | @cindex integer, 16-byte |
| 5323 | @end ifset |
| 5324 | |
| 5325 | @node Rept |
| 5326 | @section @code{.rept @var{count}} |
| 5327 | |
| 5328 | @cindex @code{rept} directive |
| 5329 | Repeat the sequence of lines between the @code{.rept} directive and the next |
| 5330 | @code{.endr} directive @var{count} times. |
| 5331 | |
| 5332 | For example, assembling |
| 5333 | |
| 5334 | @example |
| 5335 | .rept 3 |
| 5336 | .long 0 |
| 5337 | .endr |
| 5338 | @end example |
| 5339 | |
| 5340 | is equivalent to assembling |
| 5341 | |
| 5342 | @example |
| 5343 | .long 0 |
| 5344 | .long 0 |
| 5345 | .long 0 |
| 5346 | @end example |
| 5347 | |
| 5348 | @node Sbttl |
| 5349 | @section @code{.sbttl "@var{subheading}"} |
| 5350 | |
| 5351 | @cindex @code{sbttl} directive |
| 5352 | @cindex subtitles for listings |
| 5353 | @cindex listing control: subtitle |
| 5354 | Use @var{subheading} as the title (third line, immediately after the |
| 5355 | title line) when generating assembly listings. |
| 5356 | |
| 5357 | This directive affects subsequent pages, as well as the current page if |
| 5358 | it appears within ten lines of the top of a page. |
| 5359 | |
| 5360 | @ifset COFF |
| 5361 | @node Scl |
| 5362 | @section @code{.scl @var{class}} |
| 5363 | |
| 5364 | @cindex @code{scl} directive |
| 5365 | @cindex symbol storage class (COFF) |
| 5366 | @cindex COFF symbol storage class |
| 5367 | Set the storage-class value for a symbol. This directive may only be |
| 5368 | used inside a @code{.def}/@code{.endef} pair. Storage class may flag |
| 5369 | whether a symbol is static or external, or it may record further |
| 5370 | symbolic debugging information. |
| 5371 | @ifset BOUT |
| 5372 | |
| 5373 | The @samp{.scl} directive is primarily associated with COFF output; when |
| 5374 | configured to generate @code{b.out} output format, @command{@value{AS}} |
| 5375 | accepts this directive but ignores it. |
| 5376 | @end ifset |
| 5377 | @end ifset |
| 5378 | |
| 5379 | @ifset COFF-ELF |
| 5380 | @node Section |
| 5381 | @section @code{.section @var{name}} |
| 5382 | |
| 5383 | @cindex named section |
| 5384 | Use the @code{.section} directive to assemble the following code into a section |
| 5385 | named @var{name}. |
| 5386 | |
| 5387 | This directive is only supported for targets that actually support arbitrarily |
| 5388 | named sections; on @code{a.out} targets, for example, it is not accepted, even |
| 5389 | with a standard @code{a.out} section name. |
| 5390 | |
| 5391 | @ifset COFF |
| 5392 | @ifset ELF |
| 5393 | @c only print the extra heading if both COFF and ELF are set |
| 5394 | @subheading COFF Version |
| 5395 | @end ifset |
| 5396 | |
| 5397 | @cindex @code{section} directive (COFF version) |
| 5398 | For COFF targets, the @code{.section} directive is used in one of the following |
| 5399 | ways: |
| 5400 | |
| 5401 | @smallexample |
| 5402 | .section @var{name}[, "@var{flags}"] |
| 5403 | .section @var{name}[, @var{subsegment}] |
| 5404 | @end smallexample |
| 5405 | |
| 5406 | If the optional argument is quoted, it is taken as flags to use for the |
| 5407 | section. Each flag is a single character. The following flags are recognized: |
| 5408 | @table @code |
| 5409 | @item b |
| 5410 | bss section (uninitialized data) |
| 5411 | @item n |
| 5412 | section is not loaded |
| 5413 | @item w |
| 5414 | writable section |
| 5415 | @item d |
| 5416 | data section |
| 5417 | @item r |
| 5418 | read-only section |
| 5419 | @item x |
| 5420 | executable section |
| 5421 | @item s |
| 5422 | shared section (meaningful for PE targets) |
| 5423 | @item a |
| 5424 | ignored. (For compatibility with the ELF version) |
| 5425 | @end table |
| 5426 | |
| 5427 | If no flags are specified, the default flags depend upon the section name. If |
| 5428 | the section name is not recognized, the default will be for the section to be |
| 5429 | loaded and writable. Note the @code{n} and @code{w} flags remove attributes |
| 5430 | from the section, rather than adding them, so if they are used on their own it |
| 5431 | will be as if no flags had been specified at all. |
| 5432 | |
| 5433 | If the optional argument to the @code{.section} directive is not quoted, it is |
| 5434 | taken as a subsegment number (@pxref{Sub-Sections}). |
| 5435 | @end ifset |
| 5436 | |
| 5437 | @ifset ELF |
| 5438 | @ifset COFF |
| 5439 | @c only print the extra heading if both COFF and ELF are set |
| 5440 | @subheading ELF Version |
| 5441 | @end ifset |
| 5442 | |
| 5443 | @cindex Section Stack |
| 5444 | This is one of the ELF section stack manipulation directives. The others are |
| 5445 | @code{.subsection} (@pxref{SubSection}), @code{.pushsection} |
| 5446 | (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and |
| 5447 | @code{.previous} (@pxref{Previous}). |
| 5448 | |
| 5449 | @cindex @code{section} directive (ELF version) |
| 5450 | For ELF targets, the @code{.section} directive is used like this: |
| 5451 | |
| 5452 | @smallexample |
| 5453 | .section @var{name} [, "@var{flags}"[, @@@var{type}[,@var{flag_specific_arguments}]]] |
| 5454 | @end smallexample |
| 5455 | |
| 5456 | The optional @var{flags} argument is a quoted string which may contain any |
| 5457 | combination of the following characters: |
| 5458 | @table @code |
| 5459 | @item a |
| 5460 | section is allocatable |
| 5461 | @item w |
| 5462 | section is writable |
| 5463 | @item x |
| 5464 | section is executable |
| 5465 | @item M |
| 5466 | section is mergeable |
| 5467 | @item S |
| 5468 | section contains zero terminated strings |
| 5469 | @item G |
| 5470 | section is a member of a section group |
| 5471 | @item T |
| 5472 | section is used for thread-local-storage |
| 5473 | @end table |
| 5474 | |
| 5475 | The optional @var{type} argument may contain one of the following constants: |
| 5476 | @table @code |
| 5477 | @item @@progbits |
| 5478 | section contains data |
| 5479 | @item @@nobits |
| 5480 | section does not contain data (i.e., section only occupies space) |
| 5481 | @item @@note |
| 5482 | section contains data which is used by things other than the program |
| 5483 | @item @@init_array |
| 5484 | section contains an array of pointers to init functions |
| 5485 | @item @@fini_array |
| 5486 | section contains an array of pointers to finish functions |
| 5487 | @item @@preinit_array |
| 5488 | section contains an array of pointers to pre-init functions |
| 5489 | @end table |
| 5490 | |
| 5491 | Many targets only support the first three section types. |
| 5492 | |
| 5493 | Note on targets where the @code{@@} character is the start of a comment (eg |
| 5494 | ARM) then another character is used instead. For example the ARM port uses the |
| 5495 | @code{%} character. |
| 5496 | |
| 5497 | If @var{flags} contains the @code{M} symbol then the @var{type} argument must |
| 5498 | be specified as well as an extra argument - @var{entsize} - like this: |
| 5499 | |
| 5500 | @smallexample |
| 5501 | .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize} |
| 5502 | @end smallexample |
| 5503 | |
| 5504 | Sections with the @code{M} flag but not @code{S} flag must contain fixed size |
| 5505 | constants, each @var{entsize} octets long. Sections with both @code{M} and |
| 5506 | @code{S} must contain zero terminated strings where each character is |
| 5507 | @var{entsize} bytes long. The linker may remove duplicates within sections with |
| 5508 | the same name, same entity size and same flags. @var{entsize} must be an |
| 5509 | absolute expression. |
| 5510 | |
| 5511 | If @var{flags} contains the @code{G} symbol then the @var{type} argument must |
| 5512 | be present along with an additional field like this: |
| 5513 | |
| 5514 | @smallexample |
| 5515 | .section @var{name} , "@var{flags}"G, @@@var{type}, @var{GroupName}[, @var{linkage}] |
| 5516 | @end smallexample |
| 5517 | |
| 5518 | The @var{GroupName} field specifies the name of the section group to which this |
| 5519 | particular section belongs. The optional linkage field can contain: |
| 5520 | @table @code |
| 5521 | @item comdat |
| 5522 | indicates that only one copy of this section should be retained |
| 5523 | @item .gnu.linkonce |
| 5524 | an alias for comdat |
| 5525 | @end table |
| 5526 | |
| 5527 | Note - if both the @var{M} and @var{G} flags are present then the fields for |
| 5528 | the Merge flag should come first, like this: |
| 5529 | |
| 5530 | @smallexample |
| 5531 | .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}] |
| 5532 | @end smallexample |
| 5533 | |
| 5534 | If no flags are specified, the default flags depend upon the section name. If |
| 5535 | the section name is not recognized, the default will be for the section to have |
| 5536 | none of the above flags: it will not be allocated in memory, nor writable, nor |
| 5537 | executable. The section will contain data. |
| 5538 | |
| 5539 | For ELF targets, the assembler supports another type of @code{.section} |
| 5540 | directive for compatibility with the Solaris assembler: |
| 5541 | |
| 5542 | @smallexample |
| 5543 | .section "@var{name}"[, @var{flags}...] |
| 5544 | @end smallexample |
| 5545 | |
| 5546 | Note that the section name is quoted. There may be a sequence of comma |
| 5547 | separated flags: |
| 5548 | @table @code |
| 5549 | @item #alloc |
| 5550 | section is allocatable |
| 5551 | @item #write |
| 5552 | section is writable |
| 5553 | @item #execinstr |
| 5554 | section is executable |
| 5555 | @item #tls |
| 5556 | section is used for thread local storage |
| 5557 | @end table |
| 5558 | |
| 5559 | This directive replaces the current section and subsection. See the |
| 5560 | contents of the gas testsuite directory @code{gas/testsuite/gas/elf} for |
| 5561 | some examples of how this directive and the other section stack directives |
| 5562 | work. |
| 5563 | @end ifset |
| 5564 | @end ifset |
| 5565 | |
| 5566 | @node Set |
| 5567 | @section @code{.set @var{symbol}, @var{expression}} |
| 5568 | |
| 5569 | @cindex @code{set} directive |
| 5570 | @cindex symbol value, setting |
| 5571 | Set the value of @var{symbol} to @var{expression}. This |
| 5572 | changes @var{symbol}'s value and type to conform to |
| 5573 | @var{expression}. If @var{symbol} was flagged as external, it remains |
| 5574 | flagged (@pxref{Symbol Attributes}). |
| 5575 | |
| 5576 | You may @code{.set} a symbol many times in the same assembly. |
| 5577 | |
| 5578 | If you @code{.set} a global symbol, the value stored in the object |
| 5579 | file is the last value stored into it. |
| 5580 | |
| 5581 | @ifset HPPA |
| 5582 | The syntax for @code{set} on the HPPA is |
| 5583 | @samp{@var{symbol} .set @var{expression}}. |
| 5584 | @end ifset |
| 5585 | |
| 5586 | @ifset Z80 |
| 5587 | On Z80 @code{set} is a real instruction, use |
| 5588 | @samp{@var{symbol} defl @var{expression}} instead. |
| 5589 | @end ifset |
| 5590 | |
| 5591 | @node Short |
| 5592 | @section @code{.short @var{expressions}} |
| 5593 | |
| 5594 | @cindex @code{short} directive |
| 5595 | @ifset GENERIC |
| 5596 | @code{.short} is normally the same as @samp{.word}. |
| 5597 | @xref{Word,,@code{.word}}. |
| 5598 | |
| 5599 | In some configurations, however, @code{.short} and @code{.word} generate |
| 5600 | numbers of different lengths; @pxref{Machine Dependencies}. |
| 5601 | @end ifset |
| 5602 | @ifclear GENERIC |
| 5603 | @ifset W16 |
| 5604 | @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}. |
| 5605 | @end ifset |
| 5606 | @ifset W32 |
| 5607 | This expects zero or more @var{expressions}, and emits |
| 5608 | a 16 bit number for each. |
| 5609 | @end ifset |
| 5610 | @end ifclear |
| 5611 | |
| 5612 | @node Single |
| 5613 | @section @code{.single @var{flonums}} |
| 5614 | |
| 5615 | @cindex @code{single} directive |
| 5616 | @cindex floating point numbers (single) |
| 5617 | This directive assembles zero or more flonums, separated by commas. It |
| 5618 | has the same effect as @code{.float}. |
| 5619 | @ifset GENERIC |
| 5620 | The exact kind of floating point numbers emitted depends on how |
| 5621 | @command{@value{AS}} is configured. @xref{Machine Dependencies}. |
| 5622 | @end ifset |
| 5623 | @ifclear GENERIC |
| 5624 | @ifset IEEEFLOAT |
| 5625 | On the @value{TARGET} family, @code{.single} emits 32-bit floating point |
| 5626 | numbers in @sc{ieee} format. |
| 5627 | @end ifset |
| 5628 | @end ifclear |
| 5629 | |
| 5630 | @ifset COFF-ELF |
| 5631 | @node Size |
| 5632 | @section @code{.size} |
| 5633 | |
| 5634 | This directive is used to set the size associated with a symbol. |
| 5635 | |
| 5636 | @ifset COFF |
| 5637 | @ifset ELF |
| 5638 | @c only print the extra heading if both COFF and ELF are set |
| 5639 | @subheading COFF Version |
| 5640 | @end ifset |
| 5641 | |
| 5642 | @cindex @code{size} directive (COFF version) |
| 5643 | For COFF targets, the @code{.size} directive is only permitted inside |
| 5644 | @code{.def}/@code{.endef} pairs. It is used like this: |
| 5645 | |
| 5646 | @smallexample |
| 5647 | .size @var{expression} |
| 5648 | @end smallexample |
| 5649 | |
| 5650 | @ifset BOUT |
| 5651 | @samp{.size} is only meaningful when generating COFF format output; when |
| 5652 | @command{@value{AS}} is generating @code{b.out}, it accepts this directive but |
| 5653 | ignores it. |
| 5654 | @end ifset |
| 5655 | @end ifset |
| 5656 | |
| 5657 | @ifset ELF |
| 5658 | @ifset COFF |
| 5659 | @c only print the extra heading if both COFF and ELF are set |
| 5660 | @subheading ELF Version |
| 5661 | @end ifset |
| 5662 | |
| 5663 | @cindex @code{size} directive (ELF version) |
| 5664 | For ELF targets, the @code{.size} directive is used like this: |
| 5665 | |
| 5666 | @smallexample |
| 5667 | .size @var{name} , @var{expression} |
| 5668 | @end smallexample |
| 5669 | |
| 5670 | This directive sets the size associated with a symbol @var{name}. |
| 5671 | The size in bytes is computed from @var{expression} which can make use of label |
| 5672 | arithmetic. This directive is typically used to set the size of function |
| 5673 | symbols. |
| 5674 | @end ifset |
| 5675 | @end ifset |
| 5676 | |
| 5677 | @node Sleb128 |
| 5678 | @section @code{.sleb128 @var{expressions}} |
| 5679 | |
| 5680 | @cindex @code{sleb128} directive |
| 5681 | @var{sleb128} stands for ``signed little endian base 128.'' This is a |
| 5682 | compact, variable length representation of numbers used by the DWARF |
| 5683 | symbolic debugging format. @xref{Uleb128,@code{.uleb128}}. |
| 5684 | |
| 5685 | @ifclear no-space-dir |
| 5686 | @node Skip |
| 5687 | @section @code{.skip @var{size} , @var{fill}} |
| 5688 | |
| 5689 | @cindex @code{skip} directive |
| 5690 | @cindex filling memory |
| 5691 | This directive emits @var{size} bytes, each of value @var{fill}. Both |
| 5692 | @var{size} and @var{fill} are absolute expressions. If the comma and |
| 5693 | @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as |
| 5694 | @samp{.space}. |
| 5695 | |
| 5696 | @node Space |
| 5697 | @section @code{.space @var{size} , @var{fill}} |
| 5698 | |
| 5699 | @cindex @code{space} directive |
| 5700 | @cindex filling memory |
| 5701 | This directive emits @var{size} bytes, each of value @var{fill}. Both |
| 5702 | @var{size} and @var{fill} are absolute expressions. If the comma |
| 5703 | and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same |
| 5704 | as @samp{.skip}. |
| 5705 | |
| 5706 | @ifset HPPA |
| 5707 | @quotation |
| 5708 | @emph{Warning:} @code{.space} has a completely different meaning for HPPA |
| 5709 | targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800 |
| 5710 | Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the |
| 5711 | @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives}, |
| 5712 | for a summary. |
| 5713 | @end quotation |
| 5714 | @end ifset |
| 5715 | @end ifclear |
| 5716 | |
| 5717 | @ifset have-stabs |
| 5718 | @node Stab |
| 5719 | @section @code{.stabd, .stabn, .stabs} |
| 5720 | |
| 5721 | @cindex symbolic debuggers, information for |
| 5722 | @cindex @code{stab@var{x}} directives |
| 5723 | There are three directives that begin @samp{.stab}. |
| 5724 | All emit symbols (@pxref{Symbols}), for use by symbolic debuggers. |
| 5725 | The symbols are not entered in the @command{@value{AS}} hash table: they |
| 5726 | cannot be referenced elsewhere in the source file. |
| 5727 | Up to five fields are required: |
| 5728 | |
| 5729 | @table @var |
| 5730 | @item string |
| 5731 | This is the symbol's name. It may contain any character except |
| 5732 | @samp{\000}, so is more general than ordinary symbol names. Some |
| 5733 | debuggers used to code arbitrarily complex structures into symbol names |
| 5734 | using this field. |
| 5735 | |
| 5736 | @item type |
| 5737 | An absolute expression. The symbol's type is set to the low 8 bits of |
| 5738 | this expression. Any bit pattern is permitted, but @code{@value{LD}} |
| 5739 | and debuggers choke on silly bit patterns. |
| 5740 | |
| 5741 | @item other |
| 5742 | An absolute expression. The symbol's ``other'' attribute is set to the |
| 5743 | low 8 bits of this expression. |
| 5744 | |
| 5745 | @item desc |
| 5746 | An absolute expression. The symbol's descriptor is set to the low 16 |
| 5747 | bits of this expression. |
| 5748 | |
| 5749 | @item value |
| 5750 | An absolute expression which becomes the symbol's value. |
| 5751 | @end table |
| 5752 | |
| 5753 | If a warning is detected while reading a @code{.stabd}, @code{.stabn}, |
| 5754 | or @code{.stabs} statement, the symbol has probably already been created; |
| 5755 | you get a half-formed symbol in your object file. This is |
| 5756 | compatible with earlier assemblers! |
| 5757 | |
| 5758 | @table @code |
| 5759 | @cindex @code{stabd} directive |
| 5760 | @item .stabd @var{type} , @var{other} , @var{desc} |
| 5761 | |
| 5762 | The ``name'' of the symbol generated is not even an empty string. |
| 5763 | It is a null pointer, for compatibility. Older assemblers used a |
| 5764 | null pointer so they didn't waste space in object files with empty |
| 5765 | strings. |
| 5766 | |
| 5767 | The symbol's value is set to the location counter, |
| 5768 | relocatably. When your program is linked, the value of this symbol |
| 5769 | is the address of the location counter when the @code{.stabd} was |
| 5770 | assembled. |
| 5771 | |
| 5772 | @cindex @code{stabn} directive |
| 5773 | @item .stabn @var{type} , @var{other} , @var{desc} , @var{value} |
| 5774 | The name of the symbol is set to the empty string @code{""}. |
| 5775 | |
| 5776 | @cindex @code{stabs} directive |
| 5777 | @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value} |
| 5778 | All five fields are specified. |
| 5779 | @end table |
| 5780 | @end ifset |
| 5781 | @c end have-stabs |
| 5782 | |
| 5783 | @node String |
| 5784 | @section @code{.string} "@var{str}" |
| 5785 | |
| 5786 | @cindex string, copying to object file |
| 5787 | @cindex @code{string} directive |
| 5788 | |
| 5789 | Copy the characters in @var{str} to the object file. You may specify more than |
| 5790 | one string to copy, separated by commas. Unless otherwise specified for a |
| 5791 | particular machine, the assembler marks the end of each string with a 0 byte. |
| 5792 | You can use any of the escape sequences described in @ref{Strings,,Strings}. |
| 5793 | |
| 5794 | @node Struct |
| 5795 | @section @code{.struct @var{expression}} |
| 5796 | |
| 5797 | @cindex @code{struct} directive |
| 5798 | Switch to the absolute section, and set the section offset to @var{expression}, |
| 5799 | which must be an absolute expression. You might use this as follows: |
| 5800 | @smallexample |
| 5801 | .struct 0 |
| 5802 | field1: |
| 5803 | .struct field1 + 4 |
| 5804 | field2: |
| 5805 | .struct field2 + 4 |
| 5806 | field3: |
| 5807 | @end smallexample |
| 5808 | This would define the symbol @code{field1} to have the value 0, the symbol |
| 5809 | @code{field2} to have the value 4, and the symbol @code{field3} to have the |
| 5810 | value 8. Assembly would be left in the absolute section, and you would need to |
| 5811 | use a @code{.section} directive of some sort to change to some other section |
| 5812 | before further assembly. |
| 5813 | |
| 5814 | @ifset ELF |
| 5815 | @node SubSection |
| 5816 | @section @code{.subsection @var{name}} |
| 5817 | |
| 5818 | @cindex @code{subsection} directive |
| 5819 | @cindex Section Stack |
| 5820 | This is one of the ELF section stack manipulation directives. The others are |
| 5821 | @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}), |
| 5822 | @code{.popsection} (@pxref{PopSection}), and @code{.previous} |
| 5823 | (@pxref{Previous}). |
| 5824 | |
| 5825 | This directive replaces the current subsection with @code{name}. The current |
| 5826 | section is not changed. The replaced subsection is put onto the section stack |
| 5827 | in place of the then current top of stack subsection. |
| 5828 | @end ifset |
| 5829 | |
| 5830 | @ifset ELF |
| 5831 | @node Symver |
| 5832 | @section @code{.symver} |
| 5833 | @cindex @code{symver} directive |
| 5834 | @cindex symbol versioning |
| 5835 | @cindex versions of symbols |
| 5836 | Use the @code{.symver} directive to bind symbols to specific version nodes |
| 5837 | within a source file. This is only supported on ELF platforms, and is |
| 5838 | typically used when assembling files to be linked into a shared library. |
| 5839 | There are cases where it may make sense to use this in objects to be bound |
| 5840 | into an application itself so as to override a versioned symbol from a |
| 5841 | shared library. |
| 5842 | |
| 5843 | For ELF targets, the @code{.symver} directive can be used like this: |
| 5844 | @smallexample |
| 5845 | .symver @var{name}, @var{name2@@nodename} |
| 5846 | @end smallexample |
| 5847 | If the symbol @var{name} is defined within the file |
| 5848 | being assembled, the @code{.symver} directive effectively creates a symbol |
| 5849 | alias with the name @var{name2@@nodename}, and in fact the main reason that we |
| 5850 | just don't try and create a regular alias is that the @var{@@} character isn't |
| 5851 | permitted in symbol names. The @var{name2} part of the name is the actual name |
| 5852 | of the symbol by which it will be externally referenced. The name @var{name} |
| 5853 | itself is merely a name of convenience that is used so that it is possible to |
| 5854 | have definitions for multiple versions of a function within a single source |
| 5855 | file, and so that the compiler can unambiguously know which version of a |
| 5856 | function is being mentioned. The @var{nodename} portion of the alias should be |
| 5857 | the name of a node specified in the version script supplied to the linker when |
| 5858 | building a shared library. If you are attempting to override a versioned |
| 5859 | symbol from a shared library, then @var{nodename} should correspond to the |
| 5860 | nodename of the symbol you are trying to override. |
| 5861 | |
| 5862 | If the symbol @var{name} is not defined within the file being assembled, all |
| 5863 | references to @var{name} will be changed to @var{name2@@nodename}. If no |
| 5864 | reference to @var{name} is made, @var{name2@@nodename} will be removed from the |
| 5865 | symbol table. |
| 5866 | |
| 5867 | Another usage of the @code{.symver} directive is: |
| 5868 | @smallexample |
| 5869 | .symver @var{name}, @var{name2@@@@nodename} |
| 5870 | @end smallexample |
| 5871 | In this case, the symbol @var{name} must exist and be defined within |
| 5872 | the file being assembled. It is similar to @var{name2@@nodename}. The |
| 5873 | difference is @var{name2@@@@nodename} will also be used to resolve |
| 5874 | references to @var{name2} by the linker. |
| 5875 | |
| 5876 | The third usage of the @code{.symver} directive is: |
| 5877 | @smallexample |
| 5878 | .symver @var{name}, @var{name2@@@@@@nodename} |
| 5879 | @end smallexample |
| 5880 | When @var{name} is not defined within the |
| 5881 | file being assembled, it is treated as @var{name2@@nodename}. When |
| 5882 | @var{name} is defined within the file being assembled, the symbol |
| 5883 | name, @var{name}, will be changed to @var{name2@@@@nodename}. |
| 5884 | @end ifset |
| 5885 | |
| 5886 | @ifset COFF |
| 5887 | @node Tag |
| 5888 | @section @code{.tag @var{structname}} |
| 5889 | |
| 5890 | @cindex COFF structure debugging |
| 5891 | @cindex structure debugging, COFF |
| 5892 | @cindex @code{tag} directive |
| 5893 | This directive is generated by compilers to include auxiliary debugging |
| 5894 | information in the symbol table. It is only permitted inside |
| 5895 | @code{.def}/@code{.endef} pairs. Tags are used to link structure |
| 5896 | definitions in the symbol table with instances of those structures. |
| 5897 | @ifset BOUT |
| 5898 | |
| 5899 | @samp{.tag} is only used when generating COFF format output; when |
| 5900 | @command{@value{AS}} is generating @code{b.out}, it accepts this directive but |
| 5901 | ignores it. |
| 5902 | @end ifset |
| 5903 | @end ifset |
| 5904 | |
| 5905 | @node Text |
| 5906 | @section @code{.text @var{subsection}} |
| 5907 | |
| 5908 | @cindex @code{text} directive |
| 5909 | Tells @command{@value{AS}} to assemble the following statements onto the end of |
| 5910 | the text subsection numbered @var{subsection}, which is an absolute |
| 5911 | expression. If @var{subsection} is omitted, subsection number zero |
| 5912 | is used. |
| 5913 | |
| 5914 | @node Title |
| 5915 | @section @code{.title "@var{heading}"} |
| 5916 | |
| 5917 | @cindex @code{title} directive |
| 5918 | @cindex listing control: title line |
| 5919 | Use @var{heading} as the title (second line, immediately after the |
| 5920 | source file name and pagenumber) when generating assembly listings. |
| 5921 | |
| 5922 | This directive affects subsequent pages, as well as the current page if |
| 5923 | it appears within ten lines of the top of a page. |
| 5924 | |
| 5925 | @ifset COFF-ELF |
| 5926 | @node Type |
| 5927 | @section @code{.type} |
| 5928 | |
| 5929 | This directive is used to set the type of a symbol. |
| 5930 | |
| 5931 | @ifset COFF |
| 5932 | @ifset ELF |
| 5933 | @c only print the extra heading if both COFF and ELF are set |
| 5934 | @subheading COFF Version |
| 5935 | @end ifset |
| 5936 | |
| 5937 | @cindex COFF symbol type |
| 5938 | @cindex symbol type, COFF |
| 5939 | @cindex @code{type} directive (COFF version) |
| 5940 | For COFF targets, this directive is permitted only within |
| 5941 | @code{.def}/@code{.endef} pairs. It is used like this: |
| 5942 | |
| 5943 | @smallexample |
| 5944 | .type @var{int} |
| 5945 | @end smallexample |
| 5946 | |
| 5947 | This records the integer @var{int} as the type attribute of a symbol table |
| 5948 | entry. |
| 5949 | |
| 5950 | @ifset BOUT |
| 5951 | @samp{.type} is associated only with COFF format output; when |
| 5952 | @command{@value{AS}} is configured for @code{b.out} output, it accepts this |
| 5953 | directive but ignores it. |
| 5954 | @end ifset |
| 5955 | @end ifset |
| 5956 | |
| 5957 | @ifset ELF |
| 5958 | @ifset COFF |
| 5959 | @c only print the extra heading if both COFF and ELF are set |
| 5960 | @subheading ELF Version |
| 5961 | @end ifset |
| 5962 | |
| 5963 | @cindex ELF symbol type |
| 5964 | @cindex symbol type, ELF |
| 5965 | @cindex @code{type} directive (ELF version) |
| 5966 | For ELF targets, the @code{.type} directive is used like this: |
| 5967 | |
| 5968 | @smallexample |
| 5969 | .type @var{name} , @var{type description} |
| 5970 | @end smallexample |
| 5971 | |
| 5972 | This sets the type of symbol @var{name} to be either a |
| 5973 | function symbol or an object symbol. There are five different syntaxes |
| 5974 | supported for the @var{type description} field, in order to provide |
| 5975 | compatibility with various other assemblers. |
| 5976 | |
| 5977 | Because some of the characters used in these syntaxes (such as @samp{@@} and |
| 5978 | @samp{#}) are comment characters for some architectures, some of the syntaxes |
| 5979 | below do not work on all architectures. The first variant will be accepted by |
| 5980 | the GNU assembler on all architectures so that variant should be used for |
| 5981 | maximum portability, if you do not need to assemble your code with other |
| 5982 | assemblers. |
| 5983 | |
| 5984 | The syntaxes supported are: |
| 5985 | |
| 5986 | @smallexample |
| 5987 | .type <name> STT_FUNCTION |
| 5988 | .type <name> STT_OBJECT |
| 5989 | |
| 5990 | .type <name>,#function |
| 5991 | .type <name>,#object |
| 5992 | |
| 5993 | .type <name>,@@function |
| 5994 | .type <name>,@@object |
| 5995 | |
| 5996 | .type <name>,%function |
| 5997 | .type <name>,%object |
| 5998 | |
| 5999 | .type <name>,"function" |
| 6000 | .type <name>,"object" |
| 6001 | @end smallexample |
| 6002 | @end ifset |
| 6003 | @end ifset |
| 6004 | |
| 6005 | @node Uleb128 |
| 6006 | @section @code{.uleb128 @var{expressions}} |
| 6007 | |
| 6008 | @cindex @code{uleb128} directive |
| 6009 | @var{uleb128} stands for ``unsigned little endian base 128.'' This is a |
| 6010 | compact, variable length representation of numbers used by the DWARF |
| 6011 | symbolic debugging format. @xref{Sleb128,@code{.sleb128}}. |
| 6012 | |
| 6013 | @ifset COFF |
| 6014 | @node Val |
| 6015 | @section @code{.val @var{addr}} |
| 6016 | |
| 6017 | @cindex @code{val} directive |
| 6018 | @cindex COFF value attribute |
| 6019 | @cindex value attribute, COFF |
| 6020 | This directive, permitted only within @code{.def}/@code{.endef} pairs, |
| 6021 | records the address @var{addr} as the value attribute of a symbol table |
| 6022 | entry. |
| 6023 | @ifset BOUT |
| 6024 | |
| 6025 | @samp{.val} is used only for COFF output; when @command{@value{AS}} is |
| 6026 | configured for @code{b.out}, it accepts this directive but ignores it. |
| 6027 | @end ifset |
| 6028 | @end ifset |
| 6029 | |
| 6030 | @ifset ELF |
| 6031 | @node Version |
| 6032 | @section @code{.version "@var{string}"} |
| 6033 | |
| 6034 | @cindex @code{version} directive |
| 6035 | This directive creates a @code{.note} section and places into it an ELF |
| 6036 | formatted note of type NT_VERSION. The note's name is set to @code{string}. |
| 6037 | @end ifset |
| 6038 | |
| 6039 | @ifset ELF |
| 6040 | @node VTableEntry |
| 6041 | @section @code{.vtable_entry @var{table}, @var{offset}} |
| 6042 | |
| 6043 | @cindex @code{vtable_entry} directive |
| 6044 | This directive finds or creates a symbol @code{table} and creates a |
| 6045 | @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}. |
| 6046 | |
| 6047 | @node VTableInherit |
| 6048 | @section @code{.vtable_inherit @var{child}, @var{parent}} |
| 6049 | |
| 6050 | @cindex @code{vtable_inherit} directive |
| 6051 | This directive finds the symbol @code{child} and finds or creates the symbol |
| 6052 | @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the |
| 6053 | parent whose addend is the value of the child symbol. As a special case the |
| 6054 | parent name of @code{0} is treated as refering the @code{*ABS*} section. |
| 6055 | @end ifset |
| 6056 | |
| 6057 | @node Warning |
| 6058 | @section @code{.warning "@var{string}"} |
| 6059 | @cindex warning directive |
| 6060 | Similar to the directive @code{.error} |
| 6061 | (@pxref{Error,,@code{.error "@var{string}"}}), but just emits a warning. |
| 6062 | |
| 6063 | @node Weak |
| 6064 | @section @code{.weak @var{names}} |
| 6065 | |
| 6066 | @cindex @code{weak} directive |
| 6067 | This directive sets the weak attribute on the comma separated list of symbol |
| 6068 | @code{names}. If the symbols do not already exist, they will be created. |
| 6069 | |
| 6070 | On COFF targets other than PE, weak symbols are a GNU extension. This |
| 6071 | directive sets the weak attribute on the comma separated list of symbol |
| 6072 | @code{names}. If the symbols do not already exist, they will be created. |
| 6073 | |
| 6074 | On the PE target, weak symbols are supported natively as weak aliases. |
| 6075 | When a weak symbol is created that is not an alias, GAS creates an |
| 6076 | alternate symbol to hold the default value. |
| 6077 | |
| 6078 | @node Weakref |
| 6079 | @section @code{.weakref @var{alias}, @var{target}} |
| 6080 | |
| 6081 | @cindex @code{weakref} directive |
| 6082 | This directive creates an alias to the target symbol that enables the symbol to |
| 6083 | be referenced with weak-symbol semantics, but without actually making it weak. |
| 6084 | If direct references or definitions of the symbol are present, then the symbol |
| 6085 | will not be weak, but if all references to it are through weak references, the |
| 6086 | symbol will be marked as weak in the symbol table. |
| 6087 | |
| 6088 | The effect is equivalent to moving all references to the alias to a separate |
| 6089 | assembly source file, renaming the alias to the symbol in it, declaring the |
| 6090 | symbol as weak there, and running a reloadable link to merge the object files |
| 6091 | resulting from the assembly of the new source file and the old source file that |
| 6092 | had the references to the alias removed. |
| 6093 | |
| 6094 | The alias itself never makes to the symbol table, and is entirely handled |
| 6095 | within the assembler. |
| 6096 | |
| 6097 | @node Word |
| 6098 | @section @code{.word @var{expressions}} |
| 6099 | |
| 6100 | @cindex @code{word} directive |
| 6101 | This directive expects zero or more @var{expressions}, of any section, |
| 6102 | separated by commas. |
| 6103 | @ifclear GENERIC |
| 6104 | @ifset W32 |
| 6105 | For each expression, @command{@value{AS}} emits a 32-bit number. |
| 6106 | @end ifset |
| 6107 | @ifset W16 |
| 6108 | For each expression, @command{@value{AS}} emits a 16-bit number. |
| 6109 | @end ifset |
| 6110 | @end ifclear |
| 6111 | @ifset GENERIC |
| 6112 | |
| 6113 | The size of the number emitted, and its byte order, |
| 6114 | depend on what target computer the assembly is for. |
| 6115 | @end ifset |
| 6116 | |
| 6117 | @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't |
| 6118 | @c happen---32-bit addressability, period; no long/short jumps. |
| 6119 | @ifset DIFF-TBL-KLUGE |
| 6120 | @cindex difference tables altered |
| 6121 | @cindex altered difference tables |
| 6122 | @quotation |
| 6123 | @emph{Warning: Special Treatment to support Compilers} |
| 6124 | @end quotation |
| 6125 | |
| 6126 | @ifset GENERIC |
| 6127 | Machines with a 32-bit address space, but that do less than 32-bit |
| 6128 | addressing, require the following special treatment. If the machine of |
| 6129 | interest to you does 32-bit addressing (or doesn't require it; |
| 6130 | @pxref{Machine Dependencies}), you can ignore this issue. |
| 6131 | |
| 6132 | @end ifset |
| 6133 | In order to assemble compiler output into something that works, |
| 6134 | @command{@value{AS}} occasionally does strange things to @samp{.word} directives. |
| 6135 | Directives of the form @samp{.word sym1-sym2} are often emitted by |
| 6136 | compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a |
| 6137 | directive of the form @samp{.word sym1-sym2}, and the difference between |
| 6138 | @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}} |
| 6139 | creates a @dfn{secondary jump table}, immediately before the next label. |
| 6140 | This secondary jump table is preceded by a short-jump to the |
| 6141 | first byte after the secondary table. This short-jump prevents the flow |
| 6142 | of control from accidentally falling into the new table. Inside the |
| 6143 | table is a long-jump to @code{sym2}. The original @samp{.word} |
| 6144 | contains @code{sym1} minus the address of the long-jump to |
| 6145 | @code{sym2}. |
| 6146 | |
| 6147 | If there were several occurrences of @samp{.word sym1-sym2} before the |
| 6148 | secondary jump table, all of them are adjusted. If there was a |
| 6149 | @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a |
| 6150 | long-jump to @code{sym4} is included in the secondary jump table, |
| 6151 | and the @code{.word} directives are adjusted to contain @code{sym3} |
| 6152 | minus the address of the long-jump to @code{sym4}; and so on, for as many |
| 6153 | entries in the original jump table as necessary. |
| 6154 | |
| 6155 | @ifset INTERNALS |
| 6156 | @emph{This feature may be disabled by compiling @command{@value{AS}} with the |
| 6157 | @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse |
| 6158 | assembly language programmers. |
| 6159 | @end ifset |
| 6160 | @end ifset |
| 6161 | @c end DIFF-TBL-KLUGE |
| 6162 | |
| 6163 | @node Deprecated |
| 6164 | @section Deprecated Directives |
| 6165 | |
| 6166 | @cindex deprecated directives |
| 6167 | @cindex obsolescent directives |
| 6168 | One day these directives won't work. |
| 6169 | They are included for compatibility with older assemblers. |
| 6170 | @table @t |
| 6171 | @item .abort |
| 6172 | @item .line |
| 6173 | @end table |
| 6174 | |
| 6175 | @ifset GENERIC |
| 6176 | @node Machine Dependencies |
| 6177 | @chapter Machine Dependent Features |
| 6178 | |
| 6179 | @cindex machine dependencies |
| 6180 | The machine instruction sets are (almost by definition) different on |
| 6181 | each machine where @command{@value{AS}} runs. Floating point representations |
| 6182 | vary as well, and @command{@value{AS}} often supports a few additional |
| 6183 | directives or command-line options for compatibility with other |
| 6184 | assemblers on a particular platform. Finally, some versions of |
| 6185 | @command{@value{AS}} support special pseudo-instructions for branch |
| 6186 | optimization. |
| 6187 | |
| 6188 | This chapter discusses most of these differences, though it does not |
| 6189 | include details on any machine's instruction set. For details on that |
| 6190 | subject, see the hardware manufacturer's manual. |
| 6191 | |
| 6192 | @menu |
| 6193 | @ifset ALPHA |
| 6194 | * Alpha-Dependent:: Alpha Dependent Features |
| 6195 | @end ifset |
| 6196 | @ifset ARC |
| 6197 | * ARC-Dependent:: ARC Dependent Features |
| 6198 | @end ifset |
| 6199 | @ifset ARM |
| 6200 | * ARM-Dependent:: ARM Dependent Features |
| 6201 | @end ifset |
| 6202 | @ifset AVR |
| 6203 | * AVR-Dependent:: AVR Dependent Features |
| 6204 | @end ifset |
| 6205 | @ifset BFIN |
| 6206 | * BFIN-Dependent:: BFIN Dependent Features |
| 6207 | @end ifset |
| 6208 | @ifset CRIS |
| 6209 | * CRIS-Dependent:: CRIS Dependent Features |
| 6210 | @end ifset |
| 6211 | @ifset D10V |
| 6212 | * D10V-Dependent:: D10V Dependent Features |
| 6213 | @end ifset |
| 6214 | @ifset D30V |
| 6215 | * D30V-Dependent:: D30V Dependent Features |
| 6216 | @end ifset |
| 6217 | @ifset H8/300 |
| 6218 | * H8/300-Dependent:: Renesas H8/300 Dependent Features |
| 6219 | @end ifset |
| 6220 | @ifset HPPA |
| 6221 | * HPPA-Dependent:: HPPA Dependent Features |
| 6222 | @end ifset |
| 6223 | @ifset I370 |
| 6224 | * ESA/390-Dependent:: IBM ESA/390 Dependent Features |
| 6225 | @end ifset |
| 6226 | @ifset I80386 |
| 6227 | * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features |
| 6228 | @end ifset |
| 6229 | @ifset I860 |
| 6230 | * i860-Dependent:: Intel 80860 Dependent Features |
| 6231 | @end ifset |
| 6232 | @ifset I960 |
| 6233 | * i960-Dependent:: Intel 80960 Dependent Features |
| 6234 | @end ifset |
| 6235 | @ifset IA64 |
| 6236 | * IA-64-Dependent:: Intel IA-64 Dependent Features |
| 6237 | @end ifset |
| 6238 | @ifset IP2K |
| 6239 | * IP2K-Dependent:: IP2K Dependent Features |
| 6240 | @end ifset |
| 6241 | @ifset M32C |
| 6242 | * M32C-Dependent:: M32C Dependent Features |
| 6243 | @end ifset |
| 6244 | @ifset M32R |
| 6245 | * M32R-Dependent:: M32R Dependent Features |
| 6246 | @end ifset |
| 6247 | @ifset M680X0 |
| 6248 | * M68K-Dependent:: M680x0 Dependent Features |
| 6249 | @end ifset |
| 6250 | @ifset M68HC11 |
| 6251 | * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features |
| 6252 | @end ifset |
| 6253 | @ifset MIPS |
| 6254 | * MIPS-Dependent:: MIPS Dependent Features |
| 6255 | @end ifset |
| 6256 | @ifset MMIX |
| 6257 | * MMIX-Dependent:: MMIX Dependent Features |
| 6258 | @end ifset |
| 6259 | @ifset MSP430 |
| 6260 | * MSP430-Dependent:: MSP430 Dependent Features |
| 6261 | @end ifset |
| 6262 | @ifset SH |
| 6263 | * SH-Dependent:: Renesas / SuperH SH Dependent Features |
| 6264 | * SH64-Dependent:: SuperH SH64 Dependent Features |
| 6265 | @end ifset |
| 6266 | @ifset PDP11 |
| 6267 | * PDP-11-Dependent:: PDP-11 Dependent Features |
| 6268 | @end ifset |
| 6269 | @ifset PJ |
| 6270 | * PJ-Dependent:: picoJava Dependent Features |
| 6271 | @end ifset |
| 6272 | @ifset PPC |
| 6273 | * PPC-Dependent:: PowerPC Dependent Features |
| 6274 | @end ifset |
| 6275 | @ifset SPARC |
| 6276 | * Sparc-Dependent:: SPARC Dependent Features |
| 6277 | @end ifset |
| 6278 | @ifset TIC54X |
| 6279 | * TIC54X-Dependent:: TI TMS320C54x Dependent Features |
| 6280 | @end ifset |
| 6281 | @ifset V850 |
| 6282 | * V850-Dependent:: V850 Dependent Features |
| 6283 | @end ifset |
| 6284 | @ifset XTENSA |
| 6285 | * Xtensa-Dependent:: Xtensa Dependent Features |
| 6286 | @end ifset |
| 6287 | @ifset Z80 |
| 6288 | * Z80-Dependent:: Z80 Dependent Features |
| 6289 | @end ifset |
| 6290 | @ifset Z8000 |
| 6291 | * Z8000-Dependent:: Z8000 Dependent Features |
| 6292 | @end ifset |
| 6293 | @ifset VAX |
| 6294 | * Vax-Dependent:: VAX Dependent Features |
| 6295 | @end ifset |
| 6296 | @end menu |
| 6297 | |
| 6298 | @lowersections |
| 6299 | @end ifset |
| 6300 | |
| 6301 | @c The following major nodes are *sections* in the GENERIC version, *chapters* |
| 6302 | @c in single-cpu versions. This is mainly achieved by @lowersections. There is a |
| 6303 | @c peculiarity: to preserve cross-references, there must be a node called |
| 6304 | @c "Machine Dependencies". Hence the conditional nodenames in each |
| 6305 | @c major node below. Node defaulting in makeinfo requires adjacency of |
| 6306 | @c node and sectioning commands; hence the repetition of @chapter BLAH |
| 6307 | @c in both conditional blocks. |
| 6308 | |
| 6309 | @ifset ALPHA |
| 6310 | @include c-alpha.texi |
| 6311 | @end ifset |
| 6312 | |
| 6313 | @ifset ARC |
| 6314 | @include c-arc.texi |
| 6315 | @end ifset |
| 6316 | |
| 6317 | @ifset ARM |
| 6318 | @include c-arm.texi |
| 6319 | @end ifset |
| 6320 | |
| 6321 | @ifset AVR |
| 6322 | @include c-avr.texi |
| 6323 | @end ifset |
| 6324 | |
| 6325 | @ifset BFIN |
| 6326 | @include c-bfin.texi |
| 6327 | @end ifset |
| 6328 | |
| 6329 | @ifset CRIS |
| 6330 | @include c-cris.texi |
| 6331 | @end ifset |
| 6332 | |
| 6333 | @ifset Renesas-all |
| 6334 | @ifclear GENERIC |
| 6335 | @node Machine Dependencies |
| 6336 | @chapter Machine Dependent Features |
| 6337 | |
| 6338 | The machine instruction sets are different on each Renesas chip family, |
| 6339 | and there are also some syntax differences among the families. This |
| 6340 | chapter describes the specific @command{@value{AS}} features for each |
| 6341 | family. |
| 6342 | |
| 6343 | @menu |
| 6344 | * H8/300-Dependent:: Renesas H8/300 Dependent Features |
| 6345 | * SH-Dependent:: Renesas SH Dependent Features |
| 6346 | @end menu |
| 6347 | @lowersections |
| 6348 | @end ifclear |
| 6349 | @end ifset |
| 6350 | |
| 6351 | @ifset D10V |
| 6352 | @include c-d10v.texi |
| 6353 | @end ifset |
| 6354 | |
| 6355 | @ifset D30V |
| 6356 | @include c-d30v.texi |
| 6357 | @end ifset |
| 6358 | |
| 6359 | @ifset H8/300 |
| 6360 | @include c-h8300.texi |
| 6361 | @end ifset |
| 6362 | |
| 6363 | @ifset HPPA |
| 6364 | @include c-hppa.texi |
| 6365 | @end ifset |
| 6366 | |
| 6367 | @ifset I370 |
| 6368 | @include c-i370.texi |
| 6369 | @end ifset |
| 6370 | |
| 6371 | @ifset I80386 |
| 6372 | @include c-i386.texi |
| 6373 | @end ifset |
| 6374 | |
| 6375 | @ifset I860 |
| 6376 | @include c-i860.texi |
| 6377 | @end ifset |
| 6378 | |
| 6379 | @ifset I960 |
| 6380 | @include c-i960.texi |
| 6381 | @end ifset |
| 6382 | |
| 6383 | @ifset IA64 |
| 6384 | @include c-ia64.texi |
| 6385 | @end ifset |
| 6386 | |
| 6387 | @ifset IP2K |
| 6388 | @include c-ip2k.texi |
| 6389 | @end ifset |
| 6390 | |
| 6391 | @ifset M32C |
| 6392 | @include c-m32c.texi |
| 6393 | @end ifset |
| 6394 | |
| 6395 | @ifset M32R |
| 6396 | @include c-m32r.texi |
| 6397 | @end ifset |
| 6398 | |
| 6399 | @ifset M680X0 |
| 6400 | @include c-m68k.texi |
| 6401 | @end ifset |
| 6402 | |
| 6403 | @ifset M68HC11 |
| 6404 | @include c-m68hc11.texi |
| 6405 | @end ifset |
| 6406 | |
| 6407 | @ifset MIPS |
| 6408 | @include c-mips.texi |
| 6409 | @end ifset |
| 6410 | |
| 6411 | @ifset MMIX |
| 6412 | @include c-mmix.texi |
| 6413 | @end ifset |
| 6414 | |
| 6415 | @ifset MSP430 |
| 6416 | @include c-msp430.texi |
| 6417 | @end ifset |
| 6418 | |
| 6419 | @ifset NS32K |
| 6420 | @include c-ns32k.texi |
| 6421 | @end ifset |
| 6422 | |
| 6423 | @ifset PDP11 |
| 6424 | @include c-pdp11.texi |
| 6425 | @end ifset |
| 6426 | |
| 6427 | @ifset PJ |
| 6428 | @include c-pj.texi |
| 6429 | @end ifset |
| 6430 | |
| 6431 | @ifset PPC |
| 6432 | @include c-ppc.texi |
| 6433 | @end ifset |
| 6434 | |
| 6435 | @ifset SH |
| 6436 | @include c-sh.texi |
| 6437 | @include c-sh64.texi |
| 6438 | @end ifset |
| 6439 | |
| 6440 | @ifset SPARC |
| 6441 | @include c-sparc.texi |
| 6442 | @end ifset |
| 6443 | |
| 6444 | @ifset TIC54X |
| 6445 | @include c-tic54x.texi |
| 6446 | @end ifset |
| 6447 | |
| 6448 | @ifset Z80 |
| 6449 | @include c-z80.texi |
| 6450 | @end ifset |
| 6451 | |
| 6452 | @ifset Z8000 |
| 6453 | @include c-z8k.texi |
| 6454 | @end ifset |
| 6455 | |
| 6456 | @ifset VAX |
| 6457 | @include c-vax.texi |
| 6458 | @end ifset |
| 6459 | |
| 6460 | @ifset V850 |
| 6461 | @include c-v850.texi |
| 6462 | @end ifset |
| 6463 | |
| 6464 | @ifset XTENSA |
| 6465 | @include c-xtensa.texi |
| 6466 | @end ifset |
| 6467 | |
| 6468 | @ifset GENERIC |
| 6469 | @c reverse effect of @down at top of generic Machine-Dep chapter |
| 6470 | @raisesections |
| 6471 | @end ifset |
| 6472 | |
| 6473 | @node Reporting Bugs |
| 6474 | @chapter Reporting Bugs |
| 6475 | @cindex bugs in assembler |
| 6476 | @cindex reporting bugs in assembler |
| 6477 | |
| 6478 | Your bug reports play an essential role in making @command{@value{AS}} reliable. |
| 6479 | |
| 6480 | Reporting a bug may help you by bringing a solution to your problem, or it may |
| 6481 | not. But in any case the principal function of a bug report is to help the |
| 6482 | entire community by making the next version of @command{@value{AS}} work better. |
| 6483 | Bug reports are your contribution to the maintenance of @command{@value{AS}}. |
| 6484 | |
| 6485 | In order for a bug report to serve its purpose, you must include the |
| 6486 | information that enables us to fix the bug. |
| 6487 | |
| 6488 | @menu |
| 6489 | * Bug Criteria:: Have you found a bug? |
| 6490 | * Bug Reporting:: How to report bugs |
| 6491 | @end menu |
| 6492 | |
| 6493 | @node Bug Criteria |
| 6494 | @section Have You Found a Bug? |
| 6495 | @cindex bug criteria |
| 6496 | |
| 6497 | If you are not sure whether you have found a bug, here are some guidelines: |
| 6498 | |
| 6499 | @itemize @bullet |
| 6500 | @cindex fatal signal |
| 6501 | @cindex assembler crash |
| 6502 | @cindex crash of assembler |
| 6503 | @item |
| 6504 | If the assembler gets a fatal signal, for any input whatever, that is a |
| 6505 | @command{@value{AS}} bug. Reliable assemblers never crash. |
| 6506 | |
| 6507 | @cindex error on valid input |
| 6508 | @item |
| 6509 | If @command{@value{AS}} produces an error message for valid input, that is a bug. |
| 6510 | |
| 6511 | @cindex invalid input |
| 6512 | @item |
| 6513 | If @command{@value{AS}} does not produce an error message for invalid input, that |
| 6514 | is a bug. However, you should note that your idea of ``invalid input'' might |
| 6515 | be our idea of ``an extension'' or ``support for traditional practice''. |
| 6516 | |
| 6517 | @item |
| 6518 | If you are an experienced user of assemblers, your suggestions for improvement |
| 6519 | of @command{@value{AS}} are welcome in any case. |
| 6520 | @end itemize |
| 6521 | |
| 6522 | @node Bug Reporting |
| 6523 | @section How to Report Bugs |
| 6524 | @cindex bug reports |
| 6525 | @cindex assembler bugs, reporting |
| 6526 | |
| 6527 | A number of companies and individuals offer support for @sc{gnu} products. If |
| 6528 | you obtained @command{@value{AS}} from a support organization, we recommend you |
| 6529 | contact that organization first. |
| 6530 | |
| 6531 | You can find contact information for many support companies and |
| 6532 | individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs |
| 6533 | distribution. |
| 6534 | |
| 6535 | In any event, we also recommend that you send bug reports for @command{@value{AS}} |
| 6536 | to @samp{bug-binutils@@gnu.org}. |
| 6537 | |
| 6538 | The fundamental principle of reporting bugs usefully is this: |
| 6539 | @strong{report all the facts}. If you are not sure whether to state a |
| 6540 | fact or leave it out, state it! |
| 6541 | |
| 6542 | Often people omit facts because they think they know what causes the problem |
| 6543 | and assume that some details do not matter. Thus, you might assume that the |
| 6544 | name of a symbol you use in an example does not matter. Well, probably it does |
| 6545 | not, but one cannot be sure. Perhaps the bug is a stray memory reference which |
| 6546 | happens to fetch from the location where that name is stored in memory; |
| 6547 | perhaps, if the name were different, the contents of that location would fool |
| 6548 | the assembler into doing the right thing despite the bug. Play it safe and |
| 6549 | give a specific, complete example. That is the easiest thing for you to do, |
| 6550 | and the most helpful. |
| 6551 | |
| 6552 | Keep in mind that the purpose of a bug report is to enable us to fix the bug if |
| 6553 | it is new to us. Therefore, always write your bug reports on the assumption |
| 6554 | that the bug has not been reported previously. |
| 6555 | |
| 6556 | Sometimes people give a few sketchy facts and ask, ``Does this ring a |
| 6557 | bell?'' This cannot help us fix a bug, so it is basically useless. We |
| 6558 | respond by asking for enough details to enable us to investigate. |
| 6559 | You might as well expedite matters by sending them to begin with. |
| 6560 | |
| 6561 | To enable us to fix the bug, you should include all these things: |
| 6562 | |
| 6563 | @itemize @bullet |
| 6564 | @item |
| 6565 | The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start |
| 6566 | it with the @samp{--version} argument. |
| 6567 | |
| 6568 | Without this, we will not know whether there is any point in looking for |
| 6569 | the bug in the current version of @command{@value{AS}}. |
| 6570 | |
| 6571 | @item |
| 6572 | Any patches you may have applied to the @command{@value{AS}} source. |
| 6573 | |
| 6574 | @item |
| 6575 | The type of machine you are using, and the operating system name and |
| 6576 | version number. |
| 6577 | |
| 6578 | @item |
| 6579 | What compiler (and its version) was used to compile @command{@value{AS}}---e.g. |
| 6580 | ``@code{gcc-2.7}''. |
| 6581 | |
| 6582 | @item |
| 6583 | The command arguments you gave the assembler to assemble your example and |
| 6584 | observe the bug. To guarantee you will not omit something important, list them |
| 6585 | all. A copy of the Makefile (or the output from make) is sufficient. |
| 6586 | |
| 6587 | If we were to try to guess the arguments, we would probably guess wrong |
| 6588 | and then we might not encounter the bug. |
| 6589 | |
| 6590 | @item |
| 6591 | A complete input file that will reproduce the bug. If the bug is observed when |
| 6592 | the assembler is invoked via a compiler, send the assembler source, not the |
| 6593 | high level language source. Most compilers will produce the assembler source |
| 6594 | when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use |
| 6595 | the options @samp{-v --save-temps}; this will save the assembler source in a |
| 6596 | file with an extension of @file{.s}, and also show you exactly how |
| 6597 | @command{@value{AS}} is being run. |
| 6598 | |
| 6599 | @item |
| 6600 | A description of what behavior you observe that you believe is |
| 6601 | incorrect. For example, ``It gets a fatal signal.'' |
| 6602 | |
| 6603 | Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we |
| 6604 | will certainly notice it. But if the bug is incorrect output, we might not |
| 6605 | notice unless it is glaringly wrong. You might as well not give us a chance to |
| 6606 | make a mistake. |
| 6607 | |
| 6608 | Even if the problem you experience is a fatal signal, you should still say so |
| 6609 | explicitly. Suppose something strange is going on, such as, your copy of |
| 6610 | @command{@value{AS}} is out of synch, or you have encountered a bug in the C |
| 6611 | library on your system. (This has happened!) Your copy might crash and ours |
| 6612 | would not. If you told us to expect a crash, then when ours fails to crash, we |
| 6613 | would know that the bug was not happening for us. If you had not told us to |
| 6614 | expect a crash, then we would not be able to draw any conclusion from our |
| 6615 | observations. |
| 6616 | |
| 6617 | @item |
| 6618 | If you wish to suggest changes to the @command{@value{AS}} source, send us context |
| 6619 | diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p} |
| 6620 | option. Always send diffs from the old file to the new file. If you even |
| 6621 | discuss something in the @command{@value{AS}} source, refer to it by context, not |
| 6622 | by line number. |
| 6623 | |
| 6624 | The line numbers in our development sources will not match those in your |
| 6625 | sources. Your line numbers would convey no useful information to us. |
| 6626 | @end itemize |
| 6627 | |
| 6628 | Here are some things that are not necessary: |
| 6629 | |
| 6630 | @itemize @bullet |
| 6631 | @item |
| 6632 | A description of the envelope of the bug. |
| 6633 | |
| 6634 | Often people who encounter a bug spend a lot of time investigating |
| 6635 | which changes to the input file will make the bug go away and which |
| 6636 | changes will not affect it. |
| 6637 | |
| 6638 | This is often time consuming and not very useful, because the way we |
| 6639 | will find the bug is by running a single example under the debugger |
| 6640 | with breakpoints, not by pure deduction from a series of examples. |
| 6641 | We recommend that you save your time for something else. |
| 6642 | |
| 6643 | Of course, if you can find a simpler example to report @emph{instead} |
| 6644 | of the original one, that is a convenience for us. Errors in the |
| 6645 | output will be easier to spot, running under the debugger will take |
| 6646 | less time, and so on. |
| 6647 | |
| 6648 | However, simplification is not vital; if you do not want to do this, |
| 6649 | report the bug anyway and send us the entire test case you used. |
| 6650 | |
| 6651 | @item |
| 6652 | A patch for the bug. |
| 6653 | |
| 6654 | A patch for the bug does help us if it is a good one. But do not omit |
| 6655 | the necessary information, such as the test case, on the assumption that |
| 6656 | a patch is all we need. We might see problems with your patch and decide |
| 6657 | to fix the problem another way, or we might not understand it at all. |
| 6658 | |
| 6659 | Sometimes with a program as complicated as @command{@value{AS}} it is very hard to |
| 6660 | construct an example that will make the program follow a certain path through |
| 6661 | the code. If you do not send us the example, we will not be able to construct |
| 6662 | one, so we will not be able to verify that the bug is fixed. |
| 6663 | |
| 6664 | And if we cannot understand what bug you are trying to fix, or why your |
| 6665 | patch should be an improvement, we will not install it. A test case will |
| 6666 | help us to understand. |
| 6667 | |
| 6668 | @item |
| 6669 | A guess about what the bug is or what it depends on. |
| 6670 | |
| 6671 | Such guesses are usually wrong. Even we cannot guess right about such |
| 6672 | things without first using the debugger to find the facts. |
| 6673 | @end itemize |
| 6674 | |
| 6675 | @node Acknowledgements |
| 6676 | @chapter Acknowledgements |
| 6677 | |
| 6678 | If you have contributed to GAS and your name isn't listed here, |
| 6679 | it is not meant as a slight. We just don't know about it. Send mail to the |
| 6680 | maintainer, and we'll correct the situation. Currently |
| 6681 | @c (January 1994), |
| 6682 | the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}). |
| 6683 | |
| 6684 | Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any |
| 6685 | more details?} |
| 6686 | |
| 6687 | Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug |
| 6688 | information and the 68k series machines, most of the preprocessing pass, and |
| 6689 | extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}. |
| 6690 | |
| 6691 | K. Richard Pixley maintained GAS for a while, adding various enhancements and |
| 6692 | many bug fixes, including merging support for several processors, breaking GAS |
| 6693 | up to handle multiple object file format back ends (including heavy rewrite, |
| 6694 | testing, an integration of the coff and b.out back ends), adding configuration |
| 6695 | including heavy testing and verification of cross assemblers and file splits |
| 6696 | and renaming, converted GAS to strictly ANSI C including full prototypes, added |
| 6697 | support for m680[34]0 and cpu32, did considerable work on i960 including a COFF |
| 6698 | port (including considerable amounts of reverse engineering), a SPARC opcode |
| 6699 | file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know'' |
| 6700 | assertions and made them work, much other reorganization, cleanup, and lint. |
| 6701 | |
| 6702 | Ken Raeburn wrote the high-level BFD interface code to replace most of the code |
| 6703 | in format-specific I/O modules. |
| 6704 | |
| 6705 | The original VMS support was contributed by David L. Kashtan. Eric Youngdale |
| 6706 | has done much work with it since. |
| 6707 | |
| 6708 | The Intel 80386 machine description was written by Eliot Dresselhaus. |
| 6709 | |
| 6710 | Minh Tran-Le at IntelliCorp contributed some AIX 386 support. |
| 6711 | |
| 6712 | The Motorola 88k machine description was contributed by Devon Bowen of Buffalo |
| 6713 | University and Torbjorn Granlund of the Swedish Institute of Computer Science. |
| 6714 | |
| 6715 | Keith Knowles at the Open Software Foundation wrote the original MIPS back end |
| 6716 | (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support |
| 6717 | (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to |
| 6718 | support a.out format. |
| 6719 | |
| 6720 | Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k, |
| 6721 | tc-h8300), and IEEE 695 object file format (obj-ieee), was written by |
| 6722 | Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to |
| 6723 | use BFD for some low-level operations, for use with the H8/300 and AMD 29k |
| 6724 | targets. |
| 6725 | |
| 6726 | John Gilmore built the AMD 29000 support, added @code{.include} support, and |
| 6727 | simplified the configuration of which versions accept which directives. He |
| 6728 | updated the 68k machine description so that Motorola's opcodes always produced |
| 6729 | fixed-size instructions (e.g., @code{jsr}), while synthetic instructions |
| 6730 | remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested |
| 6731 | cross-compilation support, and one bug in relaxation that took a week and |
| 6732 | required the proverbial one-bit fix. |
| 6733 | |
| 6734 | Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the |
| 6735 | 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix), |
| 6736 | added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and |
| 6737 | PowerPC assembler, and made a few other minor patches. |
| 6738 | |
| 6739 | Steve Chamberlain made GAS able to generate listings. |
| 6740 | |
| 6741 | Hewlett-Packard contributed support for the HP9000/300. |
| 6742 | |
| 6743 | Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM) |
| 6744 | along with a fairly extensive HPPA testsuite (for both SOM and ELF object |
| 6745 | formats). This work was supported by both the Center for Software Science at |
| 6746 | the University of Utah and Cygnus Support. |
| 6747 | |
| 6748 | Support for ELF format files has been worked on by Mark Eichin of Cygnus |
| 6749 | Support (original, incomplete implementation for SPARC), Pete Hoogenboom and |
| 6750 | Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open |
| 6751 | Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc, |
| 6752 | and some initial 64-bit support). |
| 6753 | |
| 6754 | Linas Vepstas added GAS support for the ESA/390 ``IBM 370'' architecture. |
| 6755 | |
| 6756 | Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD |
| 6757 | support for openVMS/Alpha. |
| 6758 | |
| 6759 | Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic* |
| 6760 | flavors. |
| 6761 | |
| 6762 | David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from Tensilica, |
| 6763 | Inc. added support for Xtensa processors. |
| 6764 | |
| 6765 | Several engineers at Cygnus Support have also provided many small bug fixes and |
| 6766 | configuration enhancements. |
| 6767 | |
| 6768 | Many others have contributed large or small bugfixes and enhancements. If |
| 6769 | you have contributed significant work and are not mentioned on this list, and |
| 6770 | want to be, let us know. Some of the history has been lost; we are not |
| 6771 | intentionally leaving anyone out. |
| 6772 | |
| 6773 | @include fdl.texi |
| 6774 | |
| 6775 | @node AS Index |
| 6776 | @unnumbered AS Index |
| 6777 | |
| 6778 | @printindex cp |
| 6779 | |
| 6780 | @contents |
| 6781 | @bye |
| 6782 | @c Local Variables: |
| 6783 | @c fill-column: 79 |
| 6784 | @c End: |