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History

Fangrui Song 2174d3b961 [LTO] Add SelectionKind to IRSymtab and use it in ld.lld/LLVMgold In PGO, a C++ external linkage function `foo` has a private counter `__profc_foo` and a private `__profd_foo` in a `comdat nodeduplicate`. A `__attribute__((weak))` function `foo` has a weak hidden counter `__profc_foo` and a private `__profd_foo` in a `comdat nodeduplicate`. In `ld.lld a.o b.o`, say a.o defines an external linkage `foo` and b.o defines a weak `foo`. Currently we treat `comdat nodeduplicate` as `comdat any`, ld.lld will incorrectly consider `b.o:__profc_foo` non-prevailing. In the worst case when `b.o:__profd_foo` is retained and `b.o:__profc_foo` isn't, there will be dangling reference causing an `undefined hidden symbol` error. Add SelectionKind to `Comdat` in IRSymtab and let linkers ignore nodeduplicate comdat. Differential Revision: https://reviews.llvm.org/D106228		2021-07-20 13:22:00 -07:00
..
CMakeLists.txt	cmake: Remove add_llvm_loadable_module()	2018-12-20 22:04:08 +00:00
gold-plugin.cpp	[LTO] Add SelectionKind to IRSymtab and use it in ld.lld/LLVMgold	2021-07-20 13:22:00 -07:00
gold.exports
README.txt

README.txt

The LLVM Gold LTO Plugin
========================

This directory contains a plugin that is designed to work with binutils
gold linker. At present time, this is not the default linker in
binutils, and the default build of gold does not support plugins.

See docs/GoldPlugin.html for complete build and usage instructions.

NOTE: libLTO and LLVMgold aren't built without PIC because they would fail
to link on x86-64 with a relocation error: PIC and non-PIC can't be combined.
As an alternative to passing --enable-pic, you can use 'make ENABLE_PIC=1' in
your entire LLVM build.