Allow GVN to eliminate read-only function calls when it can detect that they are redundant.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44323 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp
index 5375d52..68366f6 100644
--- a/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -79,9 +79,6 @@
if (StoreInst* S = dyn_cast<StoreInst>(QI)) {
pointer = S->getPointerOperand();
pointerSize = TD.getTypeStoreSize(S->getOperand(0)->getType());
- } else if (LoadInst* L = dyn_cast<LoadInst>(QI)) {
- pointer = L->getPointerOperand();
- pointerSize = TD.getTypeStoreSize(L->getType());
} else if (AllocationInst* AI = dyn_cast<AllocationInst>(QI)) {
pointer = AI;
if (ConstantInt* C = dyn_cast<ConstantInt>(AI->getArraySize()))
@@ -98,7 +95,11 @@
// FreeInsts erase the entire structure
pointerSize = ~0UL;
} else if (CallSite::get(QI).getInstruction() != 0) {
- if (AA.getModRefInfo(C, CallSite::get(QI)) != AliasAnalysis::NoModRef) {
+ AliasAnalysis::ModRefBehavior result =
+ AA.getModRefBehavior(cast<CallInst>(QI)->getCalledFunction(),
+ CallSite::get(QI));
+ if (result != AliasAnalysis::DoesNotAccessMemory &&
+ result != AliasAnalysis::OnlyReadsMemory) {
if (!start && !block) {
depGraphLocal.insert(std::make_pair(C.getInstruction(),
std::make_pair(QI, true)));