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[PGO] Create weak alias for the renamed Comdat function 

Add a weak alias to the renamed Comdat function in IR level instrumentation,
using it's original name. This ensures the same behavior w/ and w/o IR
instrumentation, even for non standard conforming code.

Differential Revision: http://reviews.llvm.org/D25339

llvm-svn: 283490
This commit is contained in:
Rong Xu 2016-10-06 20:38:13 +00:00
parent c26d97401c
commit 0e79f7d11d
2 changed files with 10 additions and 0 deletions
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4
llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
View File

@ -439,9 +439,11 @@ template <class Edge, class BBInfo>
void FuncPGOInstrumentation<Edge, BBInfo>::renameComdatFunction() {
if (!canRenameComdat(F, ComdatMembers))
return;
std::string OrigName = F.getName().str();
std::string NewFuncName =
Twine(F.getName() + "." + Twine(FunctionHash)).str();
F.setName(Twine(NewFuncName));
GlobalAlias::create(GlobalValue::WeakAnyLinkage, OrigName, &F);
FuncName = Twine(FuncName + "." + Twine(FunctionHash)).str();
Comdat *NewComdat;
Module *M = F.getParent();
@ -467,7 +469,9 @@ void FuncPGOInstrumentation<Edge, BBInfo>::renameComdatFunction() {
if (GlobalAlias *GA = dyn_cast<GlobalAlias>(CM.second)) {
// For aliases, change the name directly.
assert(dyn_cast<Function>(GA->getAliasee()->stripPointerCasts()) == &F);
std::string OrigGAName = GA->getName().str();
GA->setName(Twine(GA->getName() + "." + Twine(FunctionHash)));
GlobalAlias::create(GlobalValue::WeakAnyLinkage, OrigGAName, GA);
continue;
}
// Must be a function.

6
llvm/test/Transforms/PGOProfile/comdat_rename.ll
View File

@ -50,6 +50,12 @@ define linkonce_odr void @f_with_alias() comdat($f_with_alias) {
; Rename AvailableExternallyLinkage functions
; ELFONLY-DAG: $aef.[[SINGLEBB_HASH]] = comdat any
; ELFONLY: @f = weak alias void (), void ()* @f.[[SINGLEBB_HASH]]
; ELFONLY: @f_with_alias = weak alias void (), void ()* @f_with_alias.[[SINGLEBB_HASH]]
; ELFONLY: @af = weak alias void (...), void (...)* @af.[[SINGLEBB_HASH]]
; ELFONLY: @aef = weak alias void (), void ()* @aef.[[SINGLEBB_HASH]]
define available_externally void @aef() {
; ELFONLY: define linkonce_odr void @aef.[[SINGLEBB_HASH]]() comdat {
; COFFONLY: define available_externally void @aef() {