\input texinfo
+@c Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
+@c 2001
+@c Free Software Foundation, Inc.
@setfilename internals.info
@node Top
@top Assembler Internals
An @code{operatorT} value of @code{O_big} indicates either a floating point
number, stored in the global variable @code{generic_floating_point_number}, or
-an integer to large to store in an @code{offsetT} type, stored in the global
+an integer too large to store in an @code{offsetT} type, stored in the global
array @code{generic_bignum}. This rather inflexible approach makes it
impossible to use floating point numbers or large expressions in complex
expressions.
have this type.
@item rs_leb128
-This state is used to implement the DWARF ``little endian base 128''
+This state is used to implement the DWARF ``little endian base 128''
variable length number format. The @code{fr_symbol} is always an expression
symbol, as constant expressions are emitted directly. The @code{fr_offset}
field is used during relaxation to hold the previous size of the number so
configuration process will create a file named @file{targ-env.h} in the build
directory which includes @file{te-@var{em}.h}.
+There is a special case for COFF. For historical reason, the GNU COFF
+assembler doesn't follow the documented behavior on certain debug symbols for
+the compatibility with other COFF assemblers. A port can define
+@code{STRICTCOFF} in the configure script to make the GNU COFF assembler
+to follow the documented behavior.
+
Porting GAS to a new CPU requires writing the @file{tc-@var{CPU}} files.
Porting GAS to a new object file format requires writing the
@file{obj-@var{fmt}} files. There is sometimes some interaction between these
If this macro is defined, GAS will call it with a @code{pseudo_typeS} argument.
It should return non-zero if the pseudo-op is a conditional which controls
whether code is assembled, such as @samp{.if}. GAS knows about the normal
-conditional pseudo-ops,and you should normally not have to define this macro.
+conditional pseudo-ops, and you should normally not have to define this macro.
@item comment_chars
@cindex comment_chars
@item NUMBERS_WITH_SUFFIX
@cindex NUMBERS_WITH_SUFFIX
When this macro is defined to be non-zero, the parser allows the radix of a
-constant to be indicated with a suffix. Valid suffixes are binary (B),
+constant to be indicated with a suffix. Valid suffixes are binary (B),
octal (Q), and hexadecimal (H). Case is not significant.
@item SINGLE_QUOTE_STRINGS
is a label, even if it does not have a colon.
@item TC_START_LABEL
+@itemx TC_START_LABEL_WITHOUT_COLON
@cindex TC_START_LABEL
You may define this macro to control what GAS considers to be a label. The
default definition is to accept any name followed by a colon character.
@item TC_START_LABEL_WITHOUT_COLON
@cindex TC_START_LABEL_WITHOUT_COLON
Same as TC_START_LABEL, but should be used instead of TC_START_LABEL when
-LABELS_WITHOUT_COLONS is defined.
+LABELS_WITHOUT_COLONS is defined.
@item NO_PSEUDO_DOT
@cindex NO_PSEUDO_DOT
@item md_relax_frag
@cindex md_relax_frag
-This macro may be defined to relax a frag. GAS will call this with the frag
-and the change in size of all previous frags; @code{md_relax_frag} should
-return the change in size of the frag. @xref{Relaxation}.
+This macro may be defined to relax a frag. GAS will call this with the
+segment, the frag, and the change in size of all previous frags;
+@code{md_relax_frag} should return the change in size of the frag.
+@xref{Relaxation}.
@item TC_GENERIC_RELAX_TABLE
@cindex TC_GENERIC_RELAX_TABLE
@samp{.align} directive will cause extra space to be allocated. The linker can
then discard this space when relaxing the section.
+@item TC_LINKRELAX_FIXUP (@var{segT})
+@cindex TC_LINKRELAX_FIXUP
+If defined, this macro allows control over whether fixups for a
+given section will be processed when the @var{linkrelax} variable is
+set. The macro is given the N_TYPE bits for the section in its
+@var{segT} argument. If the macro evaluates to a non-zero value
+then the fixups will be converted into relocs, otherwise they will
+be passed to @var{md_apply_fix3} as normal.
+
@item md_convert_frag
@cindex md_convert_frag
GAS will call this for each rs_machine_dependent fragment.
@cindex md_macro_start
If defined, GAS will call this macro when it starts to include a macro
expansion. @code{macro_nest} indicates the current macro nesting level, which
-includes the one being expanded.
+includes the one being expanded.
@item md_macro_info
@cindex md_macro_info
@item md_macro_end
@cindex md_macro_end
Complement to md_macro_start. If defined, it is called when finished
-processing an inserted macro expansion, just before decrementing macro_nest.
+processing an inserted macro expansion, just before decrementing macro_nest.
@item DOUBLEBAR_PARALLEL
@cindex DOUBLEBAR_PARALLEL
@item LISTING_RHS_WIDTH
The maximum number of characters to print from one line of the input file. The
default value is 100.
+
+@item TC_COFF_SECTION_DEFAULT_ATTRIBUTES
+@cindex TC_COFF_SECTION_DEFAULT_ATTRIBUTES
+The COFF @code{.section} directive will use the value of this macro to set
+a new section's attributes when a directive has no valid flags or when the
+flag is @code{w}. The default value of the macro is @code{SEC_LOAD | SEC_DATA}.
+
@end table
@node Object format backend
Sometimes changing addressing modes may also require rewriting the instruction.
It can be accessed via @code{fr_opcode} or @code{fr_fix}.
+If you generate frags separately for the basic insn opcode and any relaxable
+operands, do not call @code{fix_new} thinking you can emit fixups for the
+opcode field from the relaxable frag. It is not garanteed to be the same frag.
+If you need to emit fixups for the opcode field from inspection of the
+relaxable frag, then you need to generate a common frag for both the basic
+opcode and relaxable fields, or you need to provide the frag for the opcode to
+pass to @code{fix_new}. The latter can be done for example by defining
+@code{TC_FRAG_TYPE} to include a pointer to it and defining @code{TC_FRAG_INIT}
+to set the pointer.
+
Sometimes @code{fr_var} is increased instead, and @code{frag_wane} is not
called. I'm not sure, but I think this is to keep @code{fr_fix} referring to
an earlier byte, and @code{fr_subtype} set to @code{rs_machine_dependent} so
projects / deliverable / binutils-gdb.git / blobdiff