tree 07f99696be6d39d4be8b30115d0f63b1ae16804d
parent d5cf0c957e9b64b1bf65f5aa3e866378aec2639b
author Reid Kleckner <rnk@google.com> 1549652630 +0000
committer Reid Kleckner <rnk@google.com> 1549652630 +0000

[InstrProf] Implement static profdata registration

Summary:
The motivating use case is eliminating duplicate profile data registered
for the same inline function in two object files. Before this change,
users would observe multiple symbol definition errors with VC link, but
links with LLD would succeed.

Users (Mozilla) have reported that PGO works well with clang-cl and LLD,
but when using LLD without this static registration, we would get into a
"relocation against a discarded section" situation. I'm not sure what
happens in that situation, but I suspect that duplicate, unused profile
information was retained. If so, this change will reduce the size of
such binaries with LLD.

Now, Windows uses static registration and is in line with all the other
platforms.

Reviewers: davidxl, wmi, inglorion, void, calixte

Subscribers: mgorny, krytarowski, eraman, fedor.sergeev, hiraditya, #sanitizers, dmajor, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D57929

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@353547 91177308-0d34-0410-b5e6-96231b3b80d8