gas: Add md_generic_table_relax_frag

[deliverable/binutils-gdb.git] / gas / doc / internals.texi

diff --git a/gas/doc/internals.texi b/gas/doc/internals.texi
index 7c6172c5f840fc67fb342ee33b12c8ff1055911a..cb86b5b3629ec64a48b3b2d21bd464e49b73fa4f 100644 (file)
--- a/gas/doc/internals.texi
+++ b/gas/doc/internals.texi
@@ -1,7 +1,5 @@
 \input texinfo
 \input texinfo

-@c  Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
-@c  2001, 2002, 2003, 2004, 2005, 2006
-@c  Free Software Foundation, Inc.
+@c  Copyright (C) 1991-2019 Free Software Foundation, Inc.

 @setfilename internals.info
 @node Top
 @top Assembler Internals
 @setfilename internals.info
 @node Top
 @top Assembler Internals


@@ -43,11 +41,10 @@ This section describes some fundamental GAS data types.
 @cindex symbolS structure
 
 The definition for the symbol structure, @code{symbolS}, is located in
 @cindex symbolS structure
 
 The definition for the symbol structure, @code{symbolS}, is located in

-@file{struc-symbol.h}.
+@file{symbols.c}.

 
 

-In general, the fields of this structure may not be referred to directly.
+The fields of this structure may not be referred to directly.

 Instead, you must use one of the accessor functions defined in @file{symbol.h}.
 Instead, you must use one of the accessor functions defined in @file{symbol.h}.

-These accessor functions should work for any GAS version.

 
 Symbol structures contain the following fields:
 
 
 Symbol structures contain the following fields:
 


@@ -153,10 +150,6 @@ Set the name of the symbol.
 @cindex S_IS_EXTERNAL
 Return non-zero if the symbol is externally visible.
 
 @cindex S_IS_EXTERNAL
 Return non-zero if the symbol is externally visible.
 

-@item S_IS_EXTERN
-@cindex S_IS_EXTERN
-A synonym for @code{S_IS_EXTERNAL}.  Don't use it.
-

 @item S_IS_WEAK
 @cindex S_IS_WEAK
 Return non-zero if the symbol is weak, or if it is a @code{weakref} alias or
 @item S_IS_WEAK
 @cindex S_IS_WEAK
 Return non-zero if the symbol is weak, or if it is a @code{weakref} alias or


@@ -252,8 +245,8 @@ Indicate that the symbol is a forward reference, that is its value must only
 be determined upon use.
 
 @item S_GET_TYPE
 be determined upon use.
 
 @item S_GET_TYPE

-@item S_GET_DESC
-@item S_GET_OTHER
+@itemx S_GET_DESC
+@itemx S_GET_OTHER

 @cindex S_GET_TYPE
 @cindex S_GET_DESC
 @cindex S_GET_OTHER
 @cindex S_GET_TYPE
 @cindex S_GET_DESC
 @cindex S_GET_OTHER


@@ -262,8 +255,8 @@ are only defined for object file formats for which they make sense (primarily
 a.out).
 
 @item S_SET_TYPE
 a.out).
 
 @item S_SET_TYPE

-@item S_SET_DESC
-@item S_SET_OTHER
+@itemx S_SET_DESC
+@itemx S_SET_OTHER

 @cindex S_SET_TYPE
 @cindex S_SET_DESC
 @cindex S_SET_OTHER
 @cindex S_SET_TYPE
 @cindex S_SET_DESC
 @cindex S_SET_OTHER


@@ -404,12 +397,6 @@ deal with local symbols.  @code{struct local_symbol} is much smaller than
 @code{symbolS} (which also automatically creates a bfd @code{asymbol}
 structure), so this saves space when assembling large files.
 
 @code{symbolS} (which also automatically creates a bfd @code{asymbol}
 structure), so this saves space when assembling large files.
 

-The first field of @code{symbolS} is @code{bsym}, the pointer to the BFD
-symbol.  The first field of @code{struct local_symbol} is a pointer which is
-always set to NULL.  This is how the symbol accessor functions can distinguish
-local symbols from ordinary symbols.  The symbol accessor functions
-automatically convert a local symbol into an ordinary symbol when necessary.
-

 @node Expressions
 @subsection Expressions
 @cindex internals, expressions
 @node Expressions
 @subsection Expressions
 @cindex internals, expressions


@@ -732,7 +719,7 @@ all the fixups (@code{fixup_segment}), resolves all the symbol values (using
 @cindex porting
 
 Each GAS target specifies two main things: the CPU file and the object format
 @cindex porting
 
 Each GAS target specifies two main things: the CPU file and the object format

-file.  Two main switches in the @file{configure.in} file handle this.  The
+file.  Two main switches in the @file{configure.ac} file handle this.  The

 first switches on CPU type to set the shell variable @code{cpu_type}.  The
 second switches on the entire target to set the shell variable @code{fmt}.
 
 first switches on CPU type to set the shell variable @code{cpu_type}.  The
 second switches on the entire target to set the shell variable @code{fmt}.
 


@@ -886,6 +873,8 @@ comment.
 @item tc_comment_chars
 @cindex tc_comment_chars
 If this macro is defined, GAS will use it instead of @code{comment_chars}.
 @item tc_comment_chars
 @cindex tc_comment_chars
 If this macro is defined, GAS will use it instead of @code{comment_chars}.

+This has the advantage that this macro does not have to refer to a constant
+array.

 
 @item tc_symbol_chars
 @cindex tc_symbol_chars
 
 @item tc_symbol_chars
 @cindex tc_symbol_chars


@@ -910,6 +899,13 @@ listed in this array).  Note that line_separator_chars do not separate lines
 if found in a comment, such as after a character in line_comment_chars or
 comment_chars.
 
 if found in a comment, such as after a character in line_comment_chars or
 comment_chars.
 

+@item tc_line_separator_chars
+@cindex tc_line_separator_chars
+If this macro is defined, GAS will use it instead of
+@code{line_separator_chars}.  This has the advantage that this macro does not
+have to refer to a constant array.
+
+

 @item EXP_CHARS
 @cindex EXP_CHARS
 This is a null terminated @code{const char} array of characters which may be
 @item EXP_CHARS
 @cindex EXP_CHARS
 This is a null terminated @code{const char} array of characters which may be


@@ -1093,11 +1089,6 @@ You may define this macro to parse an expression used in a data allocation
 pseudo-op such as @code{.word}.  You can use this to recognize relocation
 directives that may appear in such directives.
 
 pseudo-op such as @code{.word}.  You can use this to recognize relocation
 directives that may appear in such directives.
 

-@item BITFIELD_CONS_EXPRESSION
-@cindex BITFIELD_CONS_EXPRESSION
-If you define this macro, GAS will recognize bitfield instructions in data
-allocation pseudo-ops, as used on the i960.
-

 @item REPEAT_CONS_EXPRESSION
 @cindex REPEAT_CONS_EXPRESSION
 If you define this macro, GAS will recognize repeat counts in data allocation
 @item REPEAT_CONS_EXPRESSION
 @cindex REPEAT_CONS_EXPRESSION
 If you define this macro, GAS will recognize repeat counts in data allocation


@@ -1127,10 +1118,11 @@ These fields are defined with the @code{TC_FIX_TYPE} macro.
 A C statement to output target specific debugging information for
 fixup @var{fixp} to @var{stream}.  This macro is called by @code{print_fixup}.
 
 A C statement to output target specific debugging information for
 fixup @var{fixp} to @var{stream}.  This macro is called by @code{print_fixup}.
 

-@item TC_FRAG_INIT (@var{fragp})
+@item TC_FRAG_INIT (@var{fragp}, @var{max_bytes})

 @cindex TC_FRAG_INIT
 @cindex TC_FRAG_INIT

-A C statement to initialize the target specific fields of frag @var{fragp}.
-These fields are defined with the @code{TC_FRAG_TYPE} macro.
+A C statement to initialize the target specific fields of frag @var{fragp}
+with maximum number of bytes @var{max_bytes}.  These fields are defined
+with the @code{TC_FRAG_TYPE} macro.

 
 @item md_number_to_chars
 @cindex md_number_to_chars
 
 @item md_number_to_chars
 @cindex md_number_to_chars


@@ -1145,7 +1137,7 @@ simple macro.
 This function is called to convert an ASCII string into a floating point value
 in format used by the CPU.  It takes three arguments.  The first is @var{type}
 which is a byte describing the type of floating point number to be created.  It
 This function is called to convert an ASCII string into a floating point value
 in format used by the CPU.  It takes three arguments.  The first is @var{type}
 which is a byte describing the type of floating point number to be created.  It

-is one of the characters defined in the @xref{FLT_CHARS} macro.  Possible
+is one of the characters defined in the @code{FLT_CHARS} macro.  Possible

 values are @var{'f'} or @var{'s'} for single precision, @var{'d'} or @var{'r'}
 for double precision and @var{'x'} or @var{'p'} for extended precision.  Either
 lower or upper case versions of these letters can be used.  Note: some targets
 values are @var{'f'} or @var{'s'} for single precision, @var{'d'} or @var{'r'}
 for double precision and @var{'x'} or @var{'p'} for extended precision.  Either
 lower or upper case versions of these letters can be used.  Note: some targets


@@ -1218,6 +1210,11 @@ If you do not define @code{md_relax_frag}, you may define
 machine independent code knows how to use such a table to relax PC relative
 references.  See @file{tc-m68k.c} for an example.  @xref{Relaxation}.
 
 machine independent code knows how to use such a table to relax PC relative
 references.  See @file{tc-m68k.c} for an example.  @xref{Relaxation}.
 

+@item md_generic_table_relax_frag
+@cindex md_generic_table_relax_frag
+If defined, it is a C statement that is invoked, instead of
+the default implementation, to scan @code{TC_GENERIC_RELAX_TABLE}.
+

 @item md_prepare_relax_scan
 @cindex md_prepare_relax_scan
 If defined, it is a C statement that is invoked prior to scanning
 @item md_prepare_relax_scan
 @cindex md_prepare_relax_scan
 If defined, it is a C statement that is invoked prior to scanning


@@ -1226,7 +1223,7 @@ the relax table.
 @item LINKER_RELAXING_SHRINKS_ONLY
 @cindex LINKER_RELAXING_SHRINKS_ONLY
 If you define this macro, and the global variable @samp{linkrelax} is set
 @item LINKER_RELAXING_SHRINKS_ONLY
 @cindex LINKER_RELAXING_SHRINKS_ONLY
 If you define this macro, and the global variable @samp{linkrelax} is set

-(because of a command line option, or unconditionally in @code{md_begin}), a
+(because of a command-line option, or unconditionally in @code{md_begin}), a

 @samp{.align} directive will cause extra space to be allocated.  The linker can
 then discard this space when relaxing the section.
 
 @samp{.align} directive will cause extra space to be allocated.  The linker can
 then discard this space when relaxing the section.
 


@@ -1250,7 +1247,7 @@ It may also create any necessary relocations.
 @cindex TC_FINALIZE_SYMS_BEFORE_SIZE_SEG
 Specifies the value to be assigned to @code{finalize_syms} before the function
 @code{size_segs} is called.  Since @code{size_segs} calls @code{cvt_frag_to_fill}
 @cindex TC_FINALIZE_SYMS_BEFORE_SIZE_SEG
 Specifies the value to be assigned to @code{finalize_syms} before the function
 @code{size_segs} is called.  Since @code{size_segs} calls @code{cvt_frag_to_fill}

-which can call @code{md_convert_frag}, this constant governs whether the symbols 
+which can call @code{md_convert_frag}, this constant governs whether the symbols

 accessed in @code{md_convert_frag} will be fully resolved.  In particular it
 governs whether local symbols will have been resolved, and had their frag
 information removed.  Depending upon the processing performed by
 accessed in @code{md_convert_frag} will be fully resolved.  In particular it
 governs whether local symbols will have been resolved, and had their frag
 information removed.  Depending upon the processing performed by


@@ -1306,15 +1303,14 @@ This macro controls resolution of fixup expressions involving the
 difference of two symbols in the same section.  If this macro returns zero,
 the subtrahend will be resolved and @code{fx_subsy} set to @code{NULL} for
 @code{md_apply_fix}.  If undefined, the default of
 difference of two symbols in the same section.  If this macro returns zero,
 the subtrahend will be resolved and @code{fx_subsy} set to @code{NULL} for
 @code{md_apply_fix}.  If undefined, the default of

-@w{@code{! SEG_NORMAL (@var{seg}) || TC_FORCE_RELOCATION (@var{fix})}} will
-be used.
+@w{@code{! SEG_NORMAL (@var{seg})}} will be used.

 
 

-@item TC_FORCE_RELOCATION_SUB_ABS (@var{fix}, @var{seg)
+@item TC_FORCE_RELOCATION_SUB_ABS (@var{fix}, @var{seg})

 @cindex TC_FORCE_RELOCATION_SUB_ABS
 Like @code{TC_FORCE_RELOCATION_SUB_SAME}, but used when the subtrahend is an
 absolute symbol.  If the macro is undefined a default of @code{0} is used.
 
 @cindex TC_FORCE_RELOCATION_SUB_ABS
 Like @code{TC_FORCE_RELOCATION_SUB_SAME}, but used when the subtrahend is an
 absolute symbol.  If the macro is undefined a default of @code{0} is used.
 

-@item TC_FORCE_RELOCATION_SUB_LOCAL (@var{fix}, @var{seg)
+@item TC_FORCE_RELOCATION_SUB_LOCAL (@var{fix}, @var{seg})

 @cindex TC_FORCE_RELOCATION_SUB_LOCAL
 Like @code{TC_FORCE_RELOCATION_SUB_ABS}, but the subtrahend is a symbol in the
 same section as the fixup.
 @cindex TC_FORCE_RELOCATION_SUB_LOCAL
 Like @code{TC_FORCE_RELOCATION_SUB_ABS}, but the subtrahend is a symbol in the
 same section as the fixup.


@@ -1325,6 +1321,11 @@ This macro is evaluated for any fixup with a @code{fx_subsy} that
 @code{fixup_segment} cannot reduce to a number.  If the macro returns
 @code{false} an error will be reported.
 
 @code{fixup_segment} cannot reduce to a number.  If the macro returns
 @code{false} an error will be reported.
 

+@item TC_GLOBAL_REGISTER_SYMBOL_OK
+@cindex TC_GLOBAL_REGISTER_SYMBOL_OK
+Define this macro if global register symbols are supported. The default
+is to disallow global register symbols.
+

 @item MD_APPLY_SYM_VALUE (@var{fix})
 @cindex MD_APPLY_SYM_VALUE
 This macro controls whether the symbol value becomes part of the value passed
 @item MD_APPLY_SYM_VALUE (@var{fix})
 @cindex MD_APPLY_SYM_VALUE
 This macro controls whether the symbol value becomes part of the value passed


@@ -1390,6 +1391,11 @@ that @code{md_pcrel_from} does not take a section argument.
 @cindex tc_frob_label
 If you define this macro, GAS will call it each time a label is defined.
 
 @cindex tc_frob_label
 If you define this macro, GAS will call it each time a label is defined.
 

+@item tc_new_dot_label
+@cindex tc_new_dot_label
+If you define this macro, GAS will call it each time a fake label is created
+off the special dot symbol.
+

 @item md_section_align
 @cindex md_section_align
 GAS will call this function for each section at the end of the assembly, to
 @item md_section_align
 @cindex md_section_align
 GAS will call this function for each section at the end of the assembly, to


@@ -1457,6 +1463,12 @@ completed, but before the relocations have been generated.
 If you define this macro, GAS will call it after the relocs have been
 generated.
 
 If you define this macro, GAS will call it after the relocs have been
 generated.
 

+@item tc_cfi_reloc_for_encoding
+@cindex tc_cfi_reloc_for_encoding
+This macro is used to indicate whether a cfi encoding requires a relocation.
+It should return the required relocation type.  Defining this macro implies
+that Compact EH is supported.
+

 @item md_post_relax_hook
 If you define this macro, GAS will call it after relaxing and sizing the
 segments.
 @item md_post_relax_hook
 If you define this macro, GAS will call it after relaxing and sizing the
 segments.


@@ -1575,7 +1587,7 @@ if it is necessary to add object file format specific code to the CPU file.
 
 @item obj_begin
 If you define this macro, GAS will call it at the start of the assembly, after
 
 @item obj_begin
 If you define this macro, GAS will call it at the start of the assembly, after

-the command line arguments have been parsed and all the machine independent
+the command-line arguments have been parsed and all the machine independent

 initializations have been completed.
 
 @item obj_app_file
 initializations have been completed.
 
 @item obj_app_file


@@ -1735,12 +1747,6 @@ no-op instructions, it must be able to expand or shrink the section contents
 while still preserving intra-section references and meeting alignment
 requirements.
 
 while still preserving intra-section references and meeting alignment
 requirements.
 

-For the i960 using b.out format, no expansion is done; instead, each
-@samp{.align} directive causes extra space to be allocated, enough that when
-the linker is relaxing a section and removing unneeded space, it can discard
-some or all of this extra padding and cause the following data to be correctly
-aligned.
-

 For the H8/300, I think the linker expands calls that can't reach, and doesn't
 worry about alignment issues; the cpu probably never needs any significant
 alignment beyond the instruction size.
 For the H8/300, I think the linker expands calls that can't reach, and doesn't
 worry about alignment issues; the cpu probably never needs any significant
 alignment beyond the instruction size.