Fix PR2346 by marking vaarg as volatile so that licm doesn't try to
hoist them.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51356 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/AliasSetTracker.cpp b/lib/Analysis/AliasSetTracker.cpp
index 68603e5..228bb80 100644
--- a/lib/Analysis/AliasSetTracker.cpp
+++ b/lib/Analysis/AliasSetTracker.cpp
@@ -294,7 +294,10 @@
 
 bool AliasSetTracker::add(VAArgInst *VAAI) {
   bool NewPtr;
-  addPointer(VAAI->getOperand(0), ~0, AliasSet::ModRef, NewPtr);
+  AliasSet &AS = addPointer(VAAI->getOperand(0), ~0, AliasSet::ModRef, NewPtr);
+  
+  // Treat vaarg instructions as volatile (not to be moved).
+  AS.setVolatile();
   return NewPtr;
 }