Add check for "branch_weights" with prof metadata

While we're here, fix the comment and variable names to make it
clear that these are raw weights, not percentages.

llvm-svn: 267491

1 files changed, 7 insertions, 3 deletions

diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index 0d5bd9e9429..d66ec8f8d45 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -1120,20 +1120,24 @@ void BranchInst::swapSuccessors() {
               MDNode::get(ProfileData->getContext(), Ops));
 }
 
-bool BranchInst::extractProfMetadata(uint64_t &ProbTrue, uint64_t &ProbFalse) {
+bool BranchInst::extractProfMetadata(uint64_t &TrueVal, uint64_t &FalseVal) {
   assert(isConditional() &&
          "Looking for probabilities on unconditional branch?");
   auto *ProfileData = getMetadata(LLVMContext::MD_prof);
   if (!ProfileData || ProfileData->getNumOperands() != 3)
     return false;
 
+  auto *ProfDataName = dyn_cast<MDString>(ProfileData->getOperand(0));
+  if (!ProfDataName || !ProfDataName->getString().equals("branch_weights"))
+    return false;
+
   auto *CITrue = mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(1));
   auto *CIFalse = mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(2));
   if (!CITrue || !CIFalse)
     return false;
 
-  ProbTrue = CITrue->getValue().getZExtValue();
-  ProbFalse = CIFalse->getValue().getZExtValue();
+  TrueVal = CITrue->getValue().getZExtValue();
+  FalseVal = CIFalse->getValue().getZExtValue();
 
   return true;
 }