Make ModRefBehavior a lattice. Use this to clean up AliasAnalysis

chaining and simplify FunctionAttrs' GetModRefBehavior logic.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118660 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/AliasAnalysis.cpp

@@ -179,7 +179,7 @@ AliasAnalysis::getModRefBehavior(ImmutableCallSite CS) {
 
   // Otherwise, fall back to the next AA in the chain. But we can merge
   // in any result we've managed to compute.
-  return std::min(AA->getModRefBehavior(CS), Min);
+  return ModRefBehavior(AA->getModRefBehavior(CS) & Min);
 }
 
 AliasAnalysis::ModRefBehavior

lib/Analysis/BasicAliasAnalysis.cpp

@@ -595,7 +595,7 @@ BasicAliasAnalysis::getModRefBehavior(ImmutableCallSite CS) {
     Min = OnlyReadsMemory;
 
   // The AliasAnalysis base class has some smarts, lets use them.
-  return std::min(AliasAnalysis::getModRefBehavior(CS), Min);
+  return ModRefBehavior(AliasAnalysis::getModRefBehavior(CS) & Min);
 }
 
 /// getModRefBehavior - Return the behavior when calling the given function.
@@ -613,12 +613,14 @@ BasicAliasAnalysis::getModRefBehavior(const Function *F) {
 #undef GET_INTRINSIC_MODREF_BEHAVIOR
   }
 
+  ModRefBehavior Min = UnknownModRefBehavior;
+
   // If the function declares it only reads memory, go with that.
   if (F->onlyReadsMemory())
-    return OnlyReadsMemory;
+    Min = OnlyReadsMemory;
 
   // Otherwise be conservative.
-  return AliasAnalysis::getModRefBehavior(F);
+  return ModRefBehavior(AliasAnalysis::getModRefBehavior(F) & Min);
 }
 
 /// getModRefInfo - Check to see if the specified callsite can clobber the
@@ -671,6 +673,8 @@ BasicAliasAnalysis::getModRefInfo(ImmutableCallSite CS,
       return NoModRef;
   }
 
+  ModRefResult Min = ModRef;
+
   // Finally, handle specific knowledge of intrinsics.
   const IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction());
   if (II != 0)
@@ -686,7 +690,7 @@ BasicAliasAnalysis::getModRefInfo(ImmutableCallSite CS,
       if (isNoAlias(Location(Dest, Len), Loc)) {
         if (isNoAlias(Location(Src, Len), Loc))
           return NoModRef;
-        return Ref;
+        Min = Ref;
       }
       break;
     }
@@ -745,7 +749,7 @@ BasicAliasAnalysis::getModRefInfo(ImmutableCallSite CS,
     }
 
   // The AliasAnalysis base class has some smarts, lets use them.
-  return AliasAnalysis::getModRefInfo(CS, Loc);
+  return ModRefResult(AliasAnalysis::getModRefInfo(CS, Loc) & Min);
 }
 
 /// aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP instruction

lib/Analysis/IPA/GlobalsModRef.cpp

@@ -120,28 +120,33 @@ namespace {
     /// called from the specified call site.  The call site may be null in which
     /// case the most generic behavior of this function should be returned.
     ModRefBehavior getModRefBehavior(const Function *F) {
+      ModRefBehavior Min = UnknownModRefBehavior;
+
       if (FunctionRecord *FR = getFunctionInfo(F)) {
         if (FR->FunctionEffect == 0)
-          return DoesNotAccessMemory;
+          Min = DoesNotAccessMemory;
         else if ((FR->FunctionEffect & Mod) == 0)
-          return OnlyReadsMemory;
+          Min = OnlyReadsMemory;
       }
-      return AliasAnalysis::getModRefBehavior(F);
+
+      return ModRefBehavior(AliasAnalysis::getModRefBehavior(F) & Min);
     }
     
     /// getModRefBehavior - Return the behavior of the specified function if
     /// called from the specified call site.  The call site may be null in which
     /// case the most generic behavior of this function should be returned.
     ModRefBehavior getModRefBehavior(ImmutableCallSite CS) {
-      const Function* F = CS.getCalledFunction();
-      if (!F) return AliasAnalysis::getModRefBehavior(CS);
-      if (FunctionRecord *FR = getFunctionInfo(F)) {
-        if (FR->FunctionEffect == 0)
-          return DoesNotAccessMemory;
-        else if ((FR->FunctionEffect & Mod) == 0)
-          return OnlyReadsMemory;
-      }
-      return AliasAnalysis::getModRefBehavior(CS);
+      ModRefBehavior Min = UnknownModRefBehavior;
+
+      if (const Function* F = CS.getCalledFunction())
+        if (FunctionRecord *FR = getFunctionInfo(F)) {
+          if (FR->FunctionEffect == 0)
+            Min = DoesNotAccessMemory;
+          else if ((FR->FunctionEffect & Mod) == 0)
+            Min = OnlyReadsMemory;
+        }
+
+      return ModRefBehavior(AliasAnalysis::getModRefBehavior(CS) & Min);
     }
 
     virtual void deleteValue(Value *V);

lib/Analysis/TypeBasedAliasAnalysis.cpp

@@ -256,11 +256,12 @@ TypeBasedAliasAnalysis::getModRefBehavior(ImmutableCallSite CS) {
     if (TBAANode(M).TypeIsImmutable())
       Min = OnlyReadsMemory;
 
-  return std::min(AliasAnalysis::getModRefBehavior(CS), Min);
+  return ModRefBehavior(AliasAnalysis::getModRefBehavior(CS) & Min);
 }
 
 AliasAnalysis::ModRefBehavior
 TypeBasedAliasAnalysis::getModRefBehavior(const Function *F) {
+  // Functions don't have metadata. Just chain to the next implementation.
   return AliasAnalysis::getModRefBehavior(F);
 }