Obey the isVolatile bit on memory intrinsics when analyzing uses of a global
variable. Noticed by inspection.
Simulate memset in EvaluateFunction where the target of the memset and the
value we're setting are both the null value. Fixes PR10047!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132288 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 9d98bb1..371500b 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -241,15 +241,15 @@
GS.HasPHIUser = true;
} else if (isa<CmpInst>(I)) {
GS.isCompared = true;
- } else if (isa<MemTransferInst>(I)) {
- const MemTransferInst *MTI = cast<MemTransferInst>(I);
+ } else if (const MemTransferInst *MTI = dyn_cast<MemTransferInst>(I)) {
+ if (MTI->isVolatile()) return true;
if (MTI->getArgOperand(0) == V)
GS.StoredType = GlobalStatus::isStored;
if (MTI->getArgOperand(1) == V)
GS.isLoaded = true;
- } else if (isa<MemSetInst>(I)) {
- assert(cast<MemSetInst>(I)->getArgOperand(0) == V &&
- "Memset only takes one pointer!");
+ } else if (const MemSetInst *MSI = dyn_cast<MemSetInst>(I)) {
+ assert(MSI->getArgOperand(0) == V && "Memset only takes one pointer!");
+ if (MSI->isVolatile()) return true;
GS.StoredType = GlobalStatus::isStored;
} else {
return true; // Any other non-load instruction might take address!
@@ -2438,6 +2438,20 @@
// Cannot handle inline asm.
if (isa<InlineAsm>(CI->getCalledValue())) return false;
+ if (MemSetInst *MSI = dyn_cast<MemSetInst>(CI)) {
+ if (MSI->isVolatile()) return false;
+ Constant *Ptr = getVal(Values, MSI->getDest());
+ Constant *Val = getVal(Values, MSI->getValue());
+ Constant *DestVal = ComputeLoadResult(getVal(Values, Ptr),
+ MutatedMemory);
+ if (Val->isNullValue() && DestVal->isNullValue()) {
+ // This memset is a no-op.
+ ++CurInst;
+ continue;
+ }
+ return false;
+ }
+
// Resolve function pointers.
Function *Callee = dyn_cast<Function>(getVal(Values,
CI->getCalledValue()));