fix a subtle volatile handling bug.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50428 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index c707e6e..86aca07 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -9432,16 +9432,21 @@
// Insert and return the new operation.
if (CastInst* FirstCI = dyn_cast<CastInst>(FirstInst))
return CastInst::create(FirstCI->getOpcode(), PhiVal, PN.getType());
- else if (isa<LoadInst>(FirstInst))
- return new LoadInst(PhiVal, "", isVolatile);
- else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
+ if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
- else if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
+ if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
return CmpInst::create(CIOp->getOpcode(), CIOp->getPredicate(),
PhiVal, ConstantOp);
- else
- assert(0 && "Unknown operation");
- return 0;
+ assert(isa<LoadInst>(FirstInst) && "Unknown operation");
+
+ // If this was a volatile load that we are merging, make sure to loop through
+ // and mark all the input loads as non-volatile. If we don't do this, we will
+ // insert a new volatile load and the old ones will not be deletable.
+ if (isVolatile)
+ for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
+ cast<LoadInst>(PN.getIncomingValue(i))->setVolatile(false);
+
+ return new LoadInst(PhiVal, "", isVolatile);
}
/// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle