Make getModRefInfo(Instruction *) not crash on certain types of instructions

llvm-svn: 236023

1 files changed, 13 insertions, 10 deletions

diff --git a/llvm/lib/Analysis/AliasAnalysis.cpp b/llvm/lib/Analysis/AliasAnalysis.cpp
index 43db1763bbb..1ee60ff1a30 100644
--- a/llvm/lib/Analysis/AliasAnalysis.cpp
+++ b/llvm/lib/Analysis/AliasAnalysis.cpp
@@ -379,15 +379,18 @@ AliasAnalysis::getModRefInfo(const StoreInst *S, const Location &Loc) {
 
 AliasAnalysis::ModRefResult
 AliasAnalysis::getModRefInfo(const VAArgInst *V, const Location &Loc) {
-  // If the va_arg address cannot alias the pointer in question, then the
-  // specified memory cannot be accessed by the va_arg.
-  if (!alias(getLocation(V), Loc))
-    return NoModRef;
 
-  // If the pointer is a pointer to constant memory, then it could not have been
-  // modified by this va_arg.
-  if (pointsToConstantMemory(Loc))
-    return NoModRef;
+  if (Loc.Ptr) {
+    // If the va_arg address cannot alias the pointer in question, then the
+    // specified memory cannot be accessed by the va_arg.
+    if (!alias(getLocation(V), Loc))
+      return NoModRef;
+
+    // If the pointer is a pointer to constant memory, then it could not have
+    // been modified by this va_arg.
+    if (pointsToConstantMemory(Loc))
+      return NoModRef;
+  }
 
   // Otherwise, a va_arg reads and writes.
   return ModRef;
@@ -400,7 +403,7 @@ AliasAnalysis::getModRefInfo(const AtomicCmpXchgInst *CX, const Location &Loc) {
     return ModRef;
 
   // If the cmpxchg address does not alias the location, it does not access it.
-  if (!alias(getLocation(CX), Loc))
+  if (Loc.Ptr && !alias(getLocation(CX), Loc))
     return NoModRef;
 
   return ModRef;
@@ -413,7 +416,7 @@ AliasAnalysis::getModRefInfo(const AtomicRMWInst *RMW, const Location &Loc) {
     return ModRef;
 
   // If the atomicrmw address does not alias the location, it does not access it.
-  if (!alias(getLocation(RMW), Loc))
+  if (Loc.Ptr && !alias(getLocation(RMW), Loc))
     return NoModRef;
 
   return ModRef;