This patch uses ELF strtab with GC and suffix merging support to create
ELF .strtab section. There is some small memory overhead to use ELF
strtab:
==14928== HEAP SUMMARY:
==14928== in use at exit: 3,276,318 bytes in 679 blocks
==14928== total heap usage: 1,544 allocs, 865 frees, 15,259,146 bytes allocated
vs.
==14936== HEAP SUMMARY:
==14936== in use at exit: 3,276,318 bytes in 679 blocks
==14936== total heap usage: 1,532 allocs, 853 frees, 15,026,402 bytes allocated
when running:
./ld-new -m elf_x86_64 -o tmpdir/ld-partial.o -r ldgram.o ldlex-wrapper.o lexsup.o ldlang.o mri.o ldctor.o ldmain.o plugin.o ldwrite.o ldexp.o ldemul.o ldver.o ldmisc.o ldfile.o ldcref.o eelf_x86_64.o eelf32_x86_64.o eelf_i386.o eelf_iamcu.o ei386linux.o eelf_l1om.o eelf_k1om.o ldbuildid.o
The results are
[32] .strtab STRTAB 0+ 3beff8 00407a 00 0 0 1
vs
[32] .strtab STRTAB 0+ 3beff8 0041d8 00 0 0 1
It reduces the .strtab size by 350 bytes, about 2%
Saving on libc.so from glibc is much more since libc.so has many alias
symbols with the same suffix. For x32 glibc,
[82] .strtab STRTAB 0+ 81b348 0159e7 00 0 0 1
vs
[82] .strtab STRTAB 0+ 81b8bc 019e72 00 0 0 1
It reduces the .strtab size by 17547 bytes, about 16%.
bfd/
PR gas/18451
* elf-bfd.h (elf_sym_strtab): New.
(elf_link_hash_table): Add strtabcount, strtabsize and
strtab.
(_bfd_elf_stringtab_init): Removed.
* elf.c (_bfd_elf_stringtab_init): Removed.
(_bfd_elf_compute_section_file_positions): Replace
bfd_strtab_hash/_bfd_elf_stringtab_init/_bfd_stringtab_free/
_bfd_stringtab_size with
elf_strtab_hash/_bfd_elf_strtab_init/_bfd_elf_strtab_free/
_bfd_elf_strtab_size. Use _bfd_elf_strtab_add,
_bfd_elf_strtab_finalize and _bfd_elf_strtab_offset to get
st_name.
(swap_out_syms): Likewise.
* elflink.c (elf_final_link_info): Replace bfd_strtab_hash
with elf_strtab_hash. Remove symbuf, symbuf_count,
symbuf_size and shndxbuf_size.
(elf_link_flush_output_syms): Removed.
(elf_link_output_sym): Renamed to ...
(elf_link_output_symstrtab): This. Replace _bfd_stringtab_add
with _bfd_elf_strtab_add. Don't flush symbols to the file nor
swap out symbols.
(elf_link_swap_symbols_out): New.
(elf_link_output_extsym): Replace elf_link_output_sym with
elf_link_output_symstrtab.
(elf_link_input_bfd): Likewise.
(elf_final_link_free): Replace _bfd_stringtab_free with
_bfd_elf_strtab_free. Remove symbuf.
(bfd_elf_final_link): Replace _bfd_elf_stringtab_init with
_bfd_elf_strtab_init. Don't set symbuf, symbuf_count,
symbuf_size nor shndxbuf_size. Initialize strtabsize and
strtab. Initialize symshndxbuf to -1 when number of sections
>= 64K. Replace elf_link_output_sym/elf_link_output_sym with
elf_link_output_symstrtab/elf_link_output_symstrtab. Don't
call elf_link_flush_output_syms. Call _bfd_elf_strtab_finalize
and elf_link_swap_symbols_out. Replace _bfd_stringtab_size
and _bfd_stringtab_emit with _bfd_elf_strtab_size and
_bfd_elf_strtab_emit.
gas/testsuite/
PR gas/18451
* gas/elf/elf.exp: Run strtab.
* gas/elf/strtab.d: New file.
* gas/elf/strtab.s: Likewise.
ld/testsuite/
PR gas/18451
* ld-elf/strtab.d: New file.
* ld-elf/strtab.s: Likewise.
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