* doc/internals.texi (Symbols): Describe changes in symbol
handling.
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Ian Lance Taylor
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1999-06-03 Ian Lance Taylor <ian@zembu.com>
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* doc/internals.texi (Symbols): Describe changes in symbol
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handling.
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1999-06-03 Richard Henderson <rth@cygnus.com>
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* dwarf2dbg.c (dwarf2_gen_line_info): Use section_symbol
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@ -115,9 +115,14 @@ This section describes some fundamental GAS data types.
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@cindex symbols, internal
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@cindex symbolS structure
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The definition for @code{struct symbol}, also known as @code{symbolS}, is
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located in @file{struc-symbol.h}. Symbol structures contain the following
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fields:
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The definition for the symbol structure, @code{symbolS}, is located in
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@file{struc-symbol.h}.
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In general, the fields of this structure may not be referred to directly.
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Instead, you must use one of the accessor functions defined in @file{symbol.h}.
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These accessor functions should work for any GAS version.
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Symbol structures contain the following fields:
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@table @code
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@item sy_value
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@ -188,16 +193,10 @@ that name is defined in @file{obj-format.h}, this field is not defined.
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This processor-specific data is of type @code{TC_SYMFIELD_TYPE}. If no macro
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by that name is defined in @file{targ-cpu.h}, this field is not defined.
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@item TARGET_SYMBOL_FIELDS
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If this macro is defined, it defines additional fields in the symbol structure.
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This macro is obsolete, and should be replaced when possible by uses of
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@code{OBJ_SYMFIELD_TYPE} and @code{TC_SYMFIELD_TYPE}.
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@end table
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There are a number of access routines used to extract the fields of a
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@code{symbolS} structure. When possible, these routines should be used rather
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than referring to the fields directly. These routines will work for any GAS
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version.
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Here is a description of the accessor functions. These should be used rather
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than referring to the fields of @code{symbolS} directly.
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@table @code
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@item S_SET_VALUE
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@ -302,8 +301,136 @@ which it makes sense (primarily ELF).
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@cindex S_SET_SIZE
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Set the size of a symbol. This is only defined for object file formats for
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which it makes sense (primarily ELF).
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@item symbol_get_value_expression
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@cindex symbol_get_value_expression
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Get a pointer to an @code{expressionS} structure which represents the value of
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the symbol as an expression.
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@item symbol_set_value_expression
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@cindex symbol_set_value_expression
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Set the value of a symbol to an expression.
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@item symbol_set_frag
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@cindex symbol_set_frag
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Set the frag where a symbol is defined.
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@item symbol_get_frag
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@cindex symbol_get_frag
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Get the frag where a symbol is defined.
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@item symbol_mark_used
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@cindex symbol_mark_used
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Mark a symbol as having been used in an expression.
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@item symbol_clear_used
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@cindex symbol_clear_used
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Clear the mark indicating that a symbol was used in an expression.
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@item symbol_used_p
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@cindex symbol_used_p
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Return whether a symbol was used in an expression.
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@item symbol_mark_used_in_reloc
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@cindex symbol_mark_used_in_reloc
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Mark a symbol as having been used by a relocation.
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@item symbol_clear_used_in_reloc
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@cindex symbol_clear_used_in_reloc
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Clear the mark indicating that a symbol was used in a relocation.
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@item symbol_used_in_reloc_p
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@cindex symbol_used_in_reloc_p
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Return whether a symbol was used in a relocation.
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@item symbol_mark_mri_common
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@cindex symbol_mark_mri_common
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Mark a symbol as an MRI common symbol.
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@item symbol_clear_mri_common
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@cindex symbol_clear_mri_common
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Clear the mark indicating that a symbol is an MRI common symbol.
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@item symbol_mri_common_p
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@cindex symbol_mri_common_p
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Return whether a symbol is an MRI common symbol.
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@item symbol_mark_written
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@cindex symbol_mark_written
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Mark a symbol as having been written.
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@item symbol_clear_written
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@cindex symbol_clear_written
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Clear the mark indicating that a symbol was written.
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@item symbol_written_p
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@cindex symbol_written_p
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Return whether a symbol was written.
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@item symbol_mark_resolved
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@cindex symbol_mark_resolved
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Mark a symbol as having been resolved.
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@item symbol_resolved_p
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@cindex symbol_resolved_p
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Return whether a symbol has been resolved.
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@item symbol_section_p
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@cindex symbol_section_p
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Return whether a symbol is a section symbol.
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@item symbol_equated_p
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@cindex symbol_equated_p
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Return whether a symbol is equated to another symbol.
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@item symbol_constant_p
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@cindex symbol_constant_p
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Return whether a symbol has a constant value, including being an offset within
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some frag.
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@item symbol_get_bfdsym
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@cindex symbol_get_bfdsym
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Return the BFD symbol associated with a symbol.
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@item symbol_set_bfdsym
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@cindex symbol_set_bfdsym
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Set the BFD symbol associated with a symbol.
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@item symbol_get_obj
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@cindex symbol_get_obj
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Return a pointer to the @code{OBJ_SYMFIELD_TYPE} field of a symbol.
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@item symbol_set_obj
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@cindex symbol_set_obj
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Set the @code{OBJ_SYMFIELD_TYPE} field of a symbol.
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@item symbol_get_tc
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@cindex symbol_get_tc
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Return a pointer to the @code{TC_SYMFIELD_TYPE} field of a symbol.
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@item symbol_set_tc
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@cindex symbol_set_tc
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Set the @code{TC_SYMFIELD_TYPE} field of a symbol.
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@end table
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When @code{BFD_ASSEMBLER} is defined, GAS attempts to store local
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symbols--symbols which will not be written to the output file--using a
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different structure, @code{struct local_symbol}. This structure can only
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represent symbols whose value is an offset within a frag.
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Code outside of the symbol handler will always deal with @code{symbolS}
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structures and use the accessor functions. The accessor functions correctly
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deal with local symbols. @code{struct local_symbol} is much smaller than
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@code{symbolS} (which also automatically creates a bfd @code{asymbol}
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structure), so this saves space when assembling large files.
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The first field of @code{symbolS} is @code{bsym}, the pointer to the BFD
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symbol. The first field of @code{struct local_symbol} is a pointer which is
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always set to NULL. This is how the symbol accessor functions can distinguish
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local symbols from ordinary symbols. The symbol accessor functions
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automatically convert a local symbol into an ordinary symbol when necessary.
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@node Expressions
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@subsection Expressions
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@cindex internals, expressions
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