tryMergingIntoMemset can only handle constant length memsets.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123090 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/lib/Transforms/Scalar/MemCpyOptimizer.cpp
index 4210f0d..76fab1c 100644
--- a/lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ b/lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -515,11 +515,12 @@
bool MemCpyOpt::processMemSet(MemSetInst *MSI, BasicBlock::iterator &BBI) {
// See if there is another memset or store neighboring this memset which
// allows us to widen out the memset to do a single larger store.
- if (Instruction *I = tryMergingIntoMemset(MSI, MSI->getDest(),
- MSI->getValue())) {
- BBI = I; // Don't invalidate iterator.
- return true;
- }
+ if (isa<ConstantInt>(MSI->getLength()) && !MSI->isVolatile())
+ if (Instruction *I = tryMergingIntoMemset(MSI, MSI->getDest(),
+ MSI->getValue())) {
+ BBI = I; // Don't invalidate iterator.
+ return true;
+ }
return false;
}