From e26a7b5e21a49543a727b1b2524a934e73c89772 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Fri, 6 Aug 2010 18:24:38 +0000 Subject: Implement a proper getModRefInfo for va_arg. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110458 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/AliasAnalysis.cpp | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'lib/Analysis/AliasAnalysis.cpp') diff --git a/lib/Analysis/AliasAnalysis.cpp b/lib/Analysis/AliasAnalysis.cpp index 0b15334e14..1f2528fa56 100644 --- a/lib/Analysis/AliasAnalysis.cpp +++ b/lib/Analysis/AliasAnalysis.cpp @@ -229,6 +229,23 @@ AliasAnalysis::getModRefInfo(const StoreInst *S, const Value *P, unsigned Size) 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 -- cgit v1.2.3