X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FBasicAliasAnalysis.cpp;h=944d0e0d375669b205f0d67fc56b24bda1ef9fe8;hb=20d6f0982ad33818cfa141f80157ac13e36d5550;hp=1604374adaf8e87a4660ea95714028986282ed35;hpb=295d4e953a1214f60632220b9fcb31c1af8b0c27;p=oota-llvm.git

diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index 1604374adaf..944d0e0d375 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -264,10 +264,8 @@ namespace {
                       const Value *V2, unsigned V2Size);
 
     ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
-    ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
-      return NoAA::getModRefInfo(CS1,CS2);
-    }
-
+    ModRefResult getModRefInfo(CallSite CS1, CallSite CS2);
+    
     /// hasNoModRefInfoForCalls - We can provide mod/ref information against
     /// non-escaping allocations.
     virtual bool hasNoModRefInfoForCalls() const { return false; }
@@ -352,6 +350,24 @@ BasicAliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
 }
 
 
+AliasAnalysis::ModRefResult 
+BasicAliasAnalysis::getModRefInfo(CallSite CS1, CallSite CS2) {
+  // If CS1 or CS2 are readnone, they don't interact.
+  ModRefBehavior CS1B = AliasAnalysis::getModRefBehavior(CS1);
+  if (CS1B == DoesNotAccessMemory) return NoModRef;
+  
+  ModRefBehavior CS2B = AliasAnalysis::getModRefBehavior(CS2);
+  if (CS2B == DoesNotAccessMemory) return NoModRef;
+  
+  // If they both only read from memory, just return ref.
+  if (CS1B == OnlyReadsMemory && CS2B == OnlyReadsMemory)
+    return Ref;
+  
+  // Otherwise, fall back to NoAA (mod+ref).
+  return NoAA::getModRefInfo(CS1, CS2);
+}
+
+
 // alias - Provide a bunch of ad-hoc rules to disambiguate in common cases, such
 // as array references.  Note that this function is heavily tail recursive.
 // Hopefully we have a smart C++ compiler.  :)
@@ -530,7 +546,7 @@ BasicAliasAnalysis::alias(const Value *V1, unsigned V1Size,
   return MayAlias;
 }
 
-// This function is used to determin if the indices of two GEP instructions are
+// This function is used to determine if the indices of two GEP instructions are
 // equal. V1 and V2 are the indices.
 static bool IndexOperandsEqual(Value *V1, Value *V2) {
   if (V1->getType() == V2->getType())