1 /* dwarf2dbg.c - DWARF2 debug support
2 Copyright (C) 1999 Hewlett-Packard Co
3 Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
5 This file is part of GAS, the GNU Assembler.
7 GAS is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GAS is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GAS; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 Logical line numbers can be controlled by the compiler via the
23 following two directives:
26 .loc FILENO LINENO [COLUMN]
28 FILENO is the filenumber. */
33 #include "dwarf2dbg.h"
36 #include <elf/dwarf2.h>
38 #define BYTES_PER_ADDRESS (BFD_ARCH_SIZE / 8)
40 /* Since we can't generate the prolog until the body is complete, we
41 use three different subsegments for .debug_line: one holding the
42 prolog, one for the directory and filename info, and one for the
43 body ("statement program"). */
48 /* First special line opcde - leave room for the standard opcodes.
49 Note: If you want to change this, you'll have to update the
50 "standard_opcode_lengths" table that is emitted below in
52 #define DWARF2_LINE_OPCODE_BASE 10
54 #ifndef DWARF2_LINE_BASE
55 /* Minimum line offset in a special line info. opcode. This value
56 was chosen to give a reasonable range of values. */
57 # define DWARF2_LINE_BASE -5
60 /* Range of line offsets in a special line info. opcode. */
61 #ifndef DWARF2_LINE_RANGE
62 # define DWARF2_LINE_RANGE 14
65 #ifndef DWARF2_LINE_MIN_INSN_LENGTH
66 /* Define the architecture-dependent minimum instruction length (in
67 bytes). This value should be rather too small than too big. */
68 # define DWARF2_LINE_MIN_INSN_LENGTH 4
71 /* Flag that indicates the initial value of the is_stmt_start flag.
72 In the present implementation, we do not mark any lines as
73 the beginning of a source statement, because that information
74 is not made available by the GCC front-end. */
75 #define DWARF2_LINE_DEFAULT_IS_STMT 1
77 /* Flag that indicates the initial value of the is_stmt_start flag.
78 In the present implementation, we do not mark any lines as
79 the beginning of a source statement, because that information
80 is not made available by the GCC front-end. */
81 #define DWARF2_LINE_DEFAULT_IS_STMT 1
83 /* Given a special op, return the line skip amount: */
84 #define SPECIAL_LINE(op) \
85 (((op) - DWARF2_LINE_OPCODE_BASE)%DWARF2_LINE_RANGE + DWARF2_LINE_BASE)
87 /* Given a special op, return the address skip amount (in units of
88 DWARF2_LINE_MIN_INSN_LENGTH. */
89 #define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE)
91 /* The maximum address skip amont that can be encoded with a special op: */
92 #define MAX_SPECIAL_ADDR_DELTA SPECIAL_ADDR(255)
94 #define INITIAL_STATE \
95 /* initialize as per DWARF2.0 standard: */ \
100 DWARF2_LINE_DEFAULT_IS_STMT, /* is_stmt */ \
101 0, /* basic_block */ \
102 1 /* empty_sequence */
106 /* state machine state as per DWARF2 manual: */
110 unsigned int filenum
;
116 empty_sequence
: 1; /* current code sequence has no DWARF2 directives? */
121 any_dwarf2_directives
: 1; /* did we emit any DWARF2 line debug directives? */
123 segT text_seg
; /* text segment "addr" is relative to */
125 segT line_seg
; /* ".debug_line" segment */
126 int last_filename
; /* index of last filename that was used */
127 int num_filenames
; /* index of last filename in use */
128 int filename_len
; /* length of the filename array */
131 int dir
; /* valid after gen_dir_list() only */
132 char *name
; /* full path before gen_dir_list(), filename afterwards */
136 struct dwarf2_line_info current
; /* current source info: */
138 /* counters for statistical purposes: */
139 unsigned int num_line_entries
;
140 unsigned int opcode_hist
[256]; /* histogram of opcode frequencies */
149 #define out_byte(byte) FRAG_APPEND_1_CHAR(byte)
150 #define out_opcode(opc) (out_byte ((opc)), ++ls.opcode_hist[(opc) & 0xff])
152 /* Output an unsigned "little-endian base 128" number. */
154 out_uleb128 (bfd_vma value
)
156 unsigned char byte
, more
= 0x80;
164 out_byte (more
| byte
);
169 /* Output a signed "little-endian base 128" number. */
171 out_sleb128 (bfd_signed_vma value
)
173 unsigned char byte
, more
= 0x80;
179 if (((value
== 0) && ((byte
& 0x40) == 0))
180 || ((value
== -1) && ((byte
& 0x40) != 0)))
182 out_byte (more
| byte
);
187 /* Encode a pair of line and address skips as efficiently as possible.
188 Note that the line skip is signed, whereas the address skip is
191 gen_addr_line (int line_delta
, bfd_vma addr_delta
)
193 unsigned int tmp
, opcode
;
195 tmp
= line_delta
- DWARF2_LINE_BASE
;
197 if (tmp
>= DWARF2_LINE_RANGE
)
199 out_opcode (DW_LNS_advance_line
);
200 out_sleb128 (line_delta
);
201 tmp
= 0 - DWARF2_LINE_BASE
;
205 tmp
+= DWARF2_LINE_OPCODE_BASE
;
207 /* try using a special opcode: */
208 opcode
= tmp
+ addr_delta
*DWARF2_LINE_RANGE
;
215 /* try using DW_LNS_const_add_pc followed by special op: */
216 opcode
= tmp
+ (addr_delta
- MAX_SPECIAL_ADDR_DELTA
)*DWARF2_LINE_RANGE
;
219 out_opcode (DW_LNS_const_add_pc
);
224 out_opcode (DW_LNS_advance_pc
);
225 out_uleb128 (addr_delta
);
228 out_opcode (tmp
); /* output line-delta */
230 out_opcode (DW_LNS_copy
); /* append new row with current info */
234 reset_state_machine (void)
236 static const struct dwarf2_sm initial_state
= { INITIAL_STATE
};
238 ls
.sm
= initial_state
;
241 /* Set an absolute address (may results in a relocation entry): */
243 out_set_addr (bfd_vma addr
)
245 subsegT saved_subseg
;
251 saved_subseg
= now_subseg
;
253 subseg_set (ls
.text_seg
, ls
.text_subseg
);
254 sym
= symbol_new (".L0\001", now_seg
, addr
, frag_now
);
256 subseg_set (saved_seg
, saved_subseg
);
258 out_opcode (DW_LNS_extended_op
);
259 out_uleb128 (BYTES_PER_ADDRESS
+ 1);
261 out_opcode (DW_LNE_set_address
);
262 expr
.X_op
= O_symbol
;
263 expr
.X_add_symbol
= sym
;
264 expr
.X_add_number
= 0;
265 emit_expr (&expr
, BYTES_PER_ADDRESS
);
268 /* Emit DW_LNS_end_sequence and reset state machine. Does not
269 preserve the current segment/sub-segment! */
271 out_end_sequence (void)
277 subseg_set (ls
.text_seg
, ls
.text_subseg
);
278 #ifdef md_current_text_addr
279 addr
= md_current_text_addr ();
281 addr
= frag_now_fix ();
283 subseg_set (ls
.line_seg
, DL_BODY
);
284 if (addr
< ls
.sm
.addr
)
291 delta
= addr
- ls
.sm
.addr
;
293 gen_addr_line (0, delta
/ DWARF2_LINE_MIN_INSN_LENGTH
);
297 subseg_set (ls
.line_seg
, DL_BODY
);
299 out_opcode (DW_LNS_extended_op
);
301 out_byte (DW_LNE_end_sequence
);
303 reset_state_machine ();
306 /* Look up a filenumber either by filename or by filenumber. If both
307 a filenumber and a filename are specified, lookup by filename takes
308 precedence. If the filename cannot be found, it is added to the
309 filetable the filenumber for the new entry is returned. */
311 get_filenum (int filenum
, char *file
)
313 int i
, last
= filenum
- 1;
314 char char0
= file
[0];
316 if ((unsigned) last
>= ls
.num_filenames
)
317 last
= ls
.last_filename
;
319 /* do a quick check against the previously used filename: */
320 if (ls
.num_filenames
> 0 && ls
.file
[last
].name
[0] == char0
321 && strcmp (ls
.file
[last
].name
+ 1, file
+ 1) == 0)
324 /* no match, fall back to simple linear scan: */
325 for (i
= 0; i
< ls
.num_filenames
; ++i
)
327 if (ls
.file
[i
].name
[0] == char0
328 && strcmp (ls
.file
[i
].name
+ 1, file
+ 1) == 0)
330 ls
.last_filename
= i
;
335 /* no match: enter new filename */
336 if (ls
.num_filenames
>= ls
.filename_len
)
338 ls
.filename_len
+= 13;
339 ls
.file
= xrealloc (ls
.file
, ls
.filename_len
* sizeof (ls
.file
[0]));
341 ls
.file
[ls
.num_filenames
].dir
= 0;
342 ls
.file
[ls
.num_filenames
].name
= file
;
343 return ++ls
.num_filenames
;
347 dwarf2_gen_line_info (bfd_vma addr
, struct dwarf2_line_info
*l
)
349 unsigned int filenum
= l
->filenum
;
350 unsigned int any_output
= 0;
351 subsegT saved_subseg
;
356 fprintf (stderr
, "line: addr %llx file `%s' line %u col %u flags %lx\n",
357 (long long) addr
, l
->filename
, l
->line
, l
->column
, l
->flags
);
359 if (filenum
> 0 && !l
->filename
)
361 if (filenum
>= ls
.num_filenames
)
363 as_warn ("Encountered bad file number in line number debug info!");
367 else if (l
->filename
)
368 filenum
= get_filenum (filenum
, l
->filename
);
370 return; /* no filename, no filnum => no play */
374 ls
.line_seg
= subseg_new (".debug_line", 0);
375 bfd_set_section_flags (stdoutput
, ls
.line_seg
, SEC_READONLY
);
377 /* We're going to need this symbol. */
378 (void) section_symbol (ls
.line_seg
);
382 saved_subseg
= now_subseg
;
383 subseg_set (ls
.line_seg
, DL_BODY
);
385 if (ls
.text_seg
!= saved_seg
|| ls
.text_subseg
!= saved_subseg
)
387 if (!ls
.sm
.empty_sequence
)
389 out_end_sequence (); /* terminate previous sequence */
390 ls
.sm
.empty_sequence
= 1;
393 ls
.text_seg
= saved_seg
;
394 ls
.text_subseg
= saved_subseg
;
399 if (ls
.sm
.filenum
!= filenum
)
402 out_opcode (DW_LNS_set_file
);
403 out_uleb128 (filenum
);
404 ls
.sm
.filenum
= filenum
;
407 if (ls
.sm
.column
!= l
->column
)
410 out_opcode (DW_LNS_set_column
);
411 out_uleb128 (l
->column
);
412 ls
.sm
.column
= l
->column
;
415 if (((l
->flags
& DWARF2_FLAG_BEGIN_STMT
) != 0) != ls
.sm
.is_stmt
)
418 out_opcode (DW_LNS_negate_stmt
);
421 if (l
->flags
& DWARF2_FLAG_BEGIN_BLOCK
)
424 out_opcode (DW_LNS_set_basic_block
);
427 if (ls
.sm
.line
!= l
->line
)
430 if (addr
< ls
.sm
.addr
)
432 if (!ls
.sm
.empty_sequence
)
435 ls
.sm
.empty_sequence
= 1;
440 gen_addr_line (l
->line
- ls
.sm
.line
,
441 (addr
- ls
.sm
.addr
) / DWARF2_LINE_MIN_INSN_LENGTH
);
442 ls
.sm
.basic_block
= 0;
443 ls
.sm
.line
= l
->line
;
447 subseg_set (saved_seg
, saved_subseg
);
449 ls
.num_line_entries
+= any_output
;
451 ls
.sm
.empty_sequence
= 0;
457 char *str
, *slash
, *dir_list
, *dp
, *cp
;
460 dir_list
= frag_more (0);
463 for (i
= 0; i
< ls
.num_filenames
; ++i
)
465 str
= ls
.file
[i
].name
;
466 slash
= strrchr (str
, '/');
470 for (j
= 0, dp
= dir_list
; j
< num_dirs
; ++j
)
472 if (strcmp (str
, dp
) == 0)
481 /* didn't find this directory: append it to the list */
482 size_t size
= strlen (str
) + 1;
483 cp
= frag_more (size
);
484 memcpy (cp
, str
, size
);
485 ls
.file
[i
].dir
= ++num_dirs
;
488 ls
.file
[i
].name
= slash
+ 1;
491 out_byte ('\0'); /* terminate directory list */
501 for (i
= 0; i
< ls
.num_filenames
; ++i
)
503 size
= strlen (ls
.file
[i
].name
) + 1;
504 cp
= frag_more (size
);
505 memcpy (cp
, ls
.file
[i
].name
, size
);
507 out_uleb128 (ls
.file
[i
].dir
); /* directory number */
508 out_uleb128 (0); /* last modification timestamp */
509 out_uleb128 (0); /* filesize */
511 out_byte (0); /* terminate filename list */
515 print_stats (unsigned long total_size
)
517 static const char *opc_name
[] =
519 "extended", "copy", "advance_pc", "advance_line", "set_file",
520 "set_column", "negate_stmt", "set_basic_block", "const_add_pc",
525 fprintf (stderr
, "Average size: %g bytes/line\n",
526 total_size
/ (double) ls
.num_line_entries
);
528 fprintf (stderr
, "\nStandard opcode histogram:\n");
530 for (i
= 0; i
< sizeof (opc_name
)/sizeof (opc_name
[0]); ++i
)
532 fprintf (stderr
, "%s", opc_name
[i
]);
533 for (j
= strlen (opc_name
[i
]); j
< 16; ++j
)
534 fprintf (stderr
, " ");
535 fprintf (stderr
, ": %u\n", ls
.opcode_hist
[i
]);
538 fprintf (stderr
, "\nSpecial opcodes:\naddr\t\t\t\tline skip\n");
540 fprintf (stderr
, "skip: ");
541 for (j
= DWARF2_LINE_BASE
; j
< DWARF2_LINE_BASE
+ DWARF2_LINE_RANGE
; ++j
)
542 fprintf (stderr
, "%3d", j
);
543 fprintf (stderr
, "\n-----");
547 j
= SPECIAL_LINE (i
);
548 if (j
== DWARF2_LINE_BASE
)
549 fprintf (stderr
, "\n%4u: ",
550 DWARF2_LINE_MIN_INSN_LENGTH
*SPECIAL_ADDR (i
));
551 fprintf (stderr
, " %2u", ls
.opcode_hist
[i
]);
553 fprintf (stderr
, "\n");
559 bfd_vma addr
, body_size
, total_size
, prolog_size
;
560 subsegT saved_subseg
, line_prolog
;
565 /* no .debug_line segment, no work to do... */
569 saved_subseg
= now_subseg
;
571 if (!ls
.sm
.empty_sequence
)
573 total_size
= body_size
= frag_now_fix ();
575 /* now generate the directory and file lists: */
576 subseg_set (ls
.line_seg
, DL_FILES
);
579 total_size
+= frag_now_fix ();
581 /* and now the header ("statement program prolog", in DWARF2 lingo...) */
582 subseg_set (ls
.line_seg
, DL_PROLOG
);
584 cp
= frag_more (15 + DWARF2_LINE_OPCODE_BASE
- 1);
586 total_size
+= frag_now_fix ();
587 prolog_size
= total_size
- body_size
- 10;
589 # define STUFF(val,size) md_number_to_chars (cp, val, size); cp += size;
590 STUFF (total_size
- 4, 4); /* length */
591 STUFF (2, 2); /* version */
592 STUFF (prolog_size
, 4); /* prologue_length */
593 STUFF (DWARF2_LINE_MIN_INSN_LENGTH
, 1);
594 STUFF (DWARF2_LINE_DEFAULT_IS_STMT
, 1);
595 STUFF (DWARF2_LINE_BASE
, 1);
596 STUFF (DWARF2_LINE_RANGE
, 1);
597 STUFF (DWARF2_LINE_OPCODE_BASE
, 1);
599 /* standard_opcode_lengths: */
600 STUFF (0, 1); /* DW_LNS_copy */
601 STUFF (1, 1); /* DW_LNS_advance_pc */
602 STUFF (1, 1); /* DW_LNS_advance_line */
603 STUFF (1, 1); /* DW_LNS_set_file */
604 STUFF (1, 1); /* DW_LNS_set_column */
605 STUFF (0, 1); /* DW_LNS_negate_stmt */
606 STUFF (0, 1); /* DW_LNS_set_basic_block */
607 STUFF (0, 1); /* DW_LNS_const_add_pc */
608 STUFF (1, 1); /* DW_LNS_fixed_advance_pc */
610 subseg_set (saved_seg
, saved_subseg
);
613 print_stats (total_size
);
617 dwarf2_directive_file (int dummy
)
621 ls
.any_dwarf2_directives
= 1;
623 if (debug_type
== DEBUG_NONE
)
624 /* Automatically turn on DWARF2 debug info unless something else
625 has been selected. */
626 debug_type
= DEBUG_DWARF2
;
628 ls
.current
.filenum
= get_absolute_expression ();
629 ls
.current
.filename
= demand_copy_C_string (&len
);
631 demand_empty_rest_of_line ();
635 dwarf2_directive_loc (int dummy
)
637 ls
.any_dwarf2_directives
= 1;
639 ls
.current
.filenum
= get_absolute_expression ();
641 ls
.current
.line
= get_absolute_expression ();
643 ls
.current
.column
= get_absolute_expression ();
644 demand_empty_rest_of_line ();
646 ls
.current
.flags
= DWARF2_FLAG_BEGIN_STMT
;
650 listing_source_line (ls
.current
.line
);
655 dwarf2_where (struct dwarf2_line_info
*line
)
657 if (ls
.any_dwarf2_directives
)
663 as_where (&line
->filename
, &line
->line
);
666 line
->flags
= DWARF2_FLAG_BEGIN_STMT
;