forked from Imagelibrary/binutils-gdb
ef10c3ace0
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.
README for LD
This is the GNU linker. It is distributed with other "binary
utilities" which should be in ../binutils. See ../binutils/README for
more general notes, including where to send bug reports.
There are many features of the linker:
* The linker uses a Binary File Descriptor library (../bfd)
that it uses to read and write object files. This helps
insulate the linker itself from the format of object files.
* The linker supports a number of different object file
formats. It can even handle multiple formats at once:
Read two input formats and write a third.
* The linker can be configured for cross-linking.
* The linker supports a control language.
* There is a user manual (ld.texinfo), as well as the
beginnings of an internals manual (ldint.texinfo).
Installation
============
See ../binutils/README.
If you want to make a cross-linker, you may want to specify
a different search path of -lfoo libraries than the default.
You can do this by setting the LIB_PATH variable in ./Makefile
or using the --with-lib-path configure switch.
To build just the linker, make the target all-ld from the top level
directory (one directory above this one).
Porting to a new target
=======================
See the ldint.texinfo manual.
Reporting bugs etc
===========================
See ../binutils/README.
Known problems
==============
The Solaris linker normally exports all dynamic symbols from an
executable. The GNU linker does not do this by default. This is
because the GNU linker tries to present the same interface for all
similar targets (in this case, all native ELF targets). This does not
matter for normal programs, but it can make a difference for programs
which try to dlopen an executable, such as PERL or Tcl. You can make
the GNU linker export all dynamic symbols with the -E or
--export-dynamic command line option.
HP/UX 9.01 has a shell bug that causes the linker scripts to be
generated incorrectly. The symptom of this appears to be "fatal error
- scanner input buffer overflow" error messages. There are various
workarounds to this:
* Build and install bash, and build with "make SHELL=bash".
* Update to a version of HP/UX with a working shell (e.g., 9.05).
* Replace "(. ${srcdir}/scripttempl/${SCRIPT_NAME}.sc)" in
genscripts.sh with "sh ${srcdir}..." (no parens) and make sure the
emulparams script used exports any shell variables it sets.
Copyright (C) 2012-2015 Free Software Foundation, Inc.
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.