Writing the symbol table - Untitled














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2.17.3.3 Writing the symbol table

The _bfd_final_link function must gather all the symbols
in the input files and write them out. It must also write out
all the symbols in the global hash table. This must be
controlled by the strip and discard fields of the
bfd_link_info structure.

The local symbols of the input files will not have been
entered into the linker hash table. The _bfd_final_link
routine must consider each input file and include the symbols
in the output file. It may be convenient to do this when
looking through the link_order structures, or it may be
done by stepping through the input_bfds list.

The _bfd_final_link routine must also traverse the global
hash table to gather all the externally visible symbols. It
is possible that most of the externally visible symbols may be
written out when considering the symbols of each input file,
but it is still necessary to traverse the hash table since the
linker script may have defined some symbols that are not in
any of the input files.

The strip field of the bfd_link_info structure
controls which symbols are written out. The possible values
are listed in bfdlink.h. If the value is strip_some,
then the keep_hash field of the bfd_link_info
structure is a hash table of symbols to keep; each symbol
should be looked up in this hash table, and only symbols which
are present should be included in the output file.

If the strip field of the bfd_link_info structure
permits local symbols to be written out, the discard field
is used to further controls which local symbols are included
in the output file. If the value is discard_l, then all
local symbols which begin with a certain prefix are discarded;
this is controlled by the bfd_is_local_label_name entry point.

The a.out backend handles symbols by calling
aout_link_write_symbols on each input BFD and then
traversing the global hash table with the function
aout_link_write_other_symbol. It builds a string table
while writing out the symbols, which is written to the output
file at the end of NAME(aout,final_link).



2.17.3.4 bfd_link_split_section

Synopsis
bfd_boolean bfd_link_split_section (bfd *abfd, asection *sec);

Description
Return nonzero if sec should be split during a
reloceatable or final link.
#define bfd_link_split_section(abfd, sec) \
BFD_SEND (abfd, _bfd_link_split_section, (abfd, sec))




2.17.3.5 bfd_section_already_linked

Synopsis
void bfd_section_already_linked (bfd *abfd, asection *sec,
struct bfd_link_info *info);

Description
Check if sec has been already linked during a reloceatable
or final link.
#define bfd_section_already_linked(abfd, sec, info) \
BFD_SEND (abfd, _section_already_linked, (abfd, sec, info))