[llvm-commits] [llvm] r64463 - /llvm/trunk/lib/Analysis/AliasAnalysis.cpp

[Duncan Sands]

Author: baldrick
Date: Fri Feb 13 11:32:26 2009
New Revision: 64463

URL: http://llvm.org/viewvc/llvm-project?rev=64463&view=rev
Log:
If a function only reads memory, then we know that...
it only reads memory!  The other change has no
functional effect, it just seems more logical to
go in order of decreasing knowledge.

Modified:
    llvm/trunk/lib/Analysis/AliasAnalysis.cpp

Modified: llvm/trunk/lib/Analysis/AliasAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/AliasAnalysis.cpp?rev=64463&r1=64462&r2=64463&view=diff

==============================================================================
--- llvm/trunk/lib/Analysis/AliasAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/AliasAnalysis.cpp Fri Feb 13 11:32:26 2009
@@ -120,9 +120,13 @@
 AliasAnalysis::ModRefBehavior
 AliasAnalysis::getModRefBehavior(Function *F,
                                  std::vector<PointerAccessInfo> *Info) {
-  if (F && F->doesNotAccessMemory())
-    // Can't do better than this.
-    return DoesNotAccessMemory;
+  if (F) {
+    if (F->doesNotAccessMemory())
+      // Can't do better than this.
+      return DoesNotAccessMemory;
+    else if (F->onlyReadsMemory())
+      return OnlyReadsMemory;
+  }
   return UnknownModRefBehavior;
 }
 
@@ -130,10 +134,10 @@
 AliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
   ModRefResult Mask = ModRef;
   ModRefBehavior MRB = getModRefBehavior(CS);
-  if (MRB == OnlyReadsMemory)
-    Mask = Ref;
-  else if (MRB == DoesNotAccessMemory)
+  if (MRB == DoesNotAccessMemory)
     return NoModRef;
+  else if (MRB == OnlyReadsMemory)
+    Mask = Ref;
   else if (MRB == AliasAnalysis::AccessesArguments) {
     bool doesAlias = false;
     for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
@@ -142,7 +146,7 @@
         doesAlias = true;
         break;
       }
-    
+
     if (!doesAlias)
       return NoModRef;
   }