[ThinLTO] Indirect call promotion fixes for promoted local functions

Summary:
Fix a couple issues limiting the application of indirect call promotion
in ThinLTO mode:
- Invoke indirect call promotion before globalopt, since it may
  eliminate imported functions which appear unreferenced.
- Invoke indirect call promotion with InLTO=true so that the PGOFuncName
  metadata is used to get the name for locals which would have been
  renamed during promotion.

Reviewers: davidxl, mehdi_amini

Subscribers: Prazek, llvm-commits, mehdi_amini

Differential Revision: https://reviews.llvm.org/D24004

llvm-svn: 280024

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/ProfileData/InstrProf.cpp b/llvm/lib/ProfileData/InstrProf.cpp
index a0400721166..dac91950183 100644
--- a/llvm/lib/ProfileData/InstrProf.cpp
+++ b/llvm/lib/ProfileData/InstrProf.cpp
@@ -136,6 +136,9 @@ std::string getPGOFuncName(StringRef RawFuncName,
 // (when \c InLTO is true): LTO's internalization privatizes many global linkage
 // symbols. This happens after value profile annotation, but those internal
 // linkage functions should not have a source prefix.
+// Additionally, for ThinLTO mode, exported internal functions are promoted
+// and renamed. We need to ensure that the original internal PGO name is
+// used when computing the GUID that is compared against the profiled GUIDs.
 // To differentiate compiler generated internal symbols from original ones,
 // PGOFuncName meta data are created and attached to the original internal
 // symbols in the value profile annotation step