PGO: preserve branch-weight metadata when simplifying a switch with a single
case to a conditional branch and when removing dead cases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163942 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index dc6b506..2d89516 100644
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -200,8 +200,20 @@
"cond");
// Insert the new branch.
- Builder.CreateCondBr(Cond, FirstCase.getCaseSuccessor(),
- SI->getDefaultDest());
+ BranchInst *NewBr = Builder.CreateCondBr(Cond,
+ FirstCase.getCaseSuccessor(),
+ SI->getDefaultDest());
+ MDNode* MD = SI->getMetadata(LLVMContext::MD_prof);
+ if (MD && MD->getNumOperands() == 3) {
+ ConstantInt *SICase = dyn_cast<ConstantInt>(MD->getOperand(2));
+ ConstantInt *SIDef = dyn_cast<ConstantInt>(MD->getOperand(1));
+ assert(SICase && SIDef);
+ // The TrueWeight should be the weight for the single case of SI.
+ NewBr->setMetadata(LLVMContext::MD_prof,
+ MDBuilder(BB->getContext()).
+ createBranchWeights(SICase->getValue().getZExtValue(),
+ SIDef->getValue().getZExtValue()));
+ }
// Delete the old switch.
SI->eraseFromParent();