Implement a proper getModRefInfo for va_arg.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110458 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/AliasAnalysis.cpp b/lib/Analysis/AliasAnalysis.cpp
index 0b15334..1f2528f 100644
--- a/lib/Analysis/AliasAnalysis.cpp
+++ b/lib/Analysis/AliasAnalysis.cpp
@@ -229,6 +229,23 @@
return Mod;
}
+AliasAnalysis::ModRefResult
+AliasAnalysis::getModRefInfo(const VAArgInst *V, const Value *P, unsigned Size) {
+ // If the va_arg address cannot alias the pointer in question, then the
+ // specified memory cannot be accessed by the va_arg.
+ if (!alias(V->getOperand(0), UnknownSize, P, Size))
+ return NoModRef;
+
+ // If the pointer is a pointer to constant memory, then it could not have been
+ // modified by this va_arg.
+ if (pointsToConstantMemory(P))
+ return NoModRef;
+
+ // Otherwise, a va_arg reads and writes.
+ return ModRef;
+}
+
+
AliasAnalysis::ModRefBehavior
AliasAnalysis::getIntrinsicModRefBehavior(unsigned iid) {
#define GET_INTRINSIC_MODREF_BEHAVIOR