gecko-dev

mirror of https://github.com/mozilla/gecko-dev.git synced 2024-10-21 17:25:36 +00:00

History

Jean-Luc Bonnafoux 5acf65c7fe Bug 1428629 - elfhack.cpp prefer prefix ++ operator for non primitive types r=froydnj MozReview-Commit-ID: C0L2NUsbmc4 --HG-- extra : rebase_source : b4b3dfbbabbd610384448169b10c3f9b5c27e621		2018-01-08 09:30:32 +01:00
..
inject	Bug 1407388 - Remove build/unix/elfhack/inject/Makefile.in and replace with generated files. r=mshal	2017-11-07 16:54:22 -08:00
dummy.c
elf.cpp	Bug 1423821 - Add a consistency check for section offsets to elfhack. r=froydnj	2017-12-07 15:34:58 +09:00
elfhack.cpp	Bug 1428629 - elfhack.cpp prefer prefix ++ operator for non primitive types r=froydnj	2018-01-08 09:30:32 +01:00
elfxx.h	Bug 1417215 - Prefer prefix ++ operator for non primitive types r=froydnj	2017-12-30 21:09:58 +01:00
inject.c	Bug 635961 - Allow elfhack to relocate data under the GNU_RELRO segment. r=froydnj	2017-07-11 07:41:07 +09:00
Makefile.in	Bug 1403346 - Implement cflags filtering for elfhack in mozbuild COMPILE_FLAGS r=glandium	2017-10-25 15:12:10 -07:00
moz.build	Bug 1403346 - Implement cflags filtering for elfhack in mozbuild COMPILE_FLAGS r=glandium	2017-10-25 15:12:10 -07:00
README
test-array.c
test-ctors.c
test.c	Bug 1385117 - Make the bss section of the elfhack testcase large enough. r=froydnj	2017-07-28 07:15:39 +09:00

README

Elfhack is a program to optimize ELF binaries for size and cold startup
speed.

Presently, it is quite experimental, though it works well for the target
it was created for: Firefox's libxul.so.

Elfhack currently only does one thing: packing dynamic relocations ;
which ends up being a quite complex task, that can be summarized this
way:
- Remove RELATIVE relocations from the .rel.dyn/.rela.dyn section.
- Inject a small code able to apply relative relocations "by hand"
  after the .rel.dyn/.rela.dyn section.
- Inject a section containing relocative relocations in a different
  and more packed format, after the small code.
- Register the small code as DT_INIT function. Make the small code call
  what was initially the DT_INIT function, if there was one.
- Remove the hole between the new section containing relative
  relocations and the following sections, adjusting offsets and base
  addresses accordingly.
- Adjust PT_LOAD entries to fit new offsets, and add an additional
  PT_LOAD entry when that is necessary to handle the discrepancy between
  offsets and base addresses, meaning the section offsets may yet again
  need adjustments.
- Adjust various DT_* dynamic tags to fit the new ELF layout.
- Adjust section headers.
- Adjust ELF headers.

See http://glandium.org/blog/?p=1177#relocations for some figures.