tree 6e049555a54a9961bb2d4465146f3f6a08699fe4
parent 9ad08c674b6ad45695f2750a21d1b1dc8698200c
author Fangrui Song <maskray@google.com> 1566356528 +0000
committer Fangrui Song <maskray@google.com> 1566356528 +0000

[ELF] More dynamic relocation packing

Currently, with Android dynamic relocation packing, only relative
relocations are grouped together. This patch implements similar
packing for non-relative relocations.

The implementation groups non-relative relocations with the same
r_info and r_addend, if using RELA. By requiring a minimum group
size of 3, this achieves smaller relocation sections. Building Android
for an ARM32 device, I see the total size of /system/lib decrease by
392 KB.

Grouping by r_info also allows the runtime dynamic linker to implement
an 1-entry cache to reduce the number of symbol lookup required. With
such 1-entry cache implemented on Android, I'm seeing 10% to 20%
reduction in total time spent in runtime linker for several executables
that I tested.

As a simple correctness check, I've also built x86_64 Android and booted
successfully.

Differential Revision: https://reviews.llvm.org/D66491
Patch by Vic Yang!

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@369488 91177308-0d34-0410-b5e6-96231b3b80d8