Don't assume a tail call can't reference a byval
argument to the outer function, this isn't correct.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@49731 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index b696a80..ad46207 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -273,8 +273,10 @@
// If this is a tail call and P points to a stack location, we know that
// the tail call cannot access or modify the local stack.
- if (isa<AllocaInst>(Object) ||
- (isa<Argument>(Object) && cast<Argument>(Object)->hasByValAttr()))
+ // We cannot exclude byval arguments here; these belong to the caller of
+ // the current function not to the current function, and a tail callee
+ // may reference them.
+ if (isa<AllocaInst>(Object))
if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction()))
if (CI->isTailCall())
return NoModRef;