Reject noalias ptr argument case in SCCPSolver::mergeInValue

Author: choikwa

llvm/lib/Transforms/Utils/InlineFunction.cpp

@@ -1118,7 +1118,7 @@ static void AddAliasScopeMetadata(CallBase &CB, ValueToValueMapTy &VMap,
                                   ClonedCodeInfo &InlinedFunctionInfo) {
   if (!EnableNoAliasConversion)
     return;
-
+	LLVM_DEBUG(dbgs() << __func__ << "\n");
   const Function *CalledFunc = CB.getCalledFunction();
   SmallVector<const Argument *, 4> NoAliasArgs;
 
@@ -1246,8 +1246,12 @@ static void AddAliasScopeMetadata(CallBase &CB, ValueToValueMapTy &VMap,
 
       for (const Value *V : PtrArgs) {
         SmallVector<const Value *, 4> Objects;
+        LLVM_DEBUG(dbgs() << "Getting objects for V: " << *V << "\n");
         getUnderlyingObjects(V, Objects, /* LI = */ nullptr);
-
+        LLVM_DEBUG(
+        for (const auto *O : Objects) {
+          dbgs() << "  Obj: " << *O << "\n";
+        });
         ObjSet.insert_range(Objects);
       }
 
@@ -2603,6 +2607,12 @@ void llvm::InlineFunctionImpl(CallBase &CB, InlineFunctionInfo &IFI,
   assert(CalledFunc && !CalledFunc->isDeclaration() &&
          "CanInlineCallSite should have verified direct call to definition");
 
+  LLVM_DEBUG(
+	dbgs() << "Caller: " << Caller->getName() << "\n";
+  dbgs() << "<-- Callee: " << CalledFunc->getName() << "\n";
+  dbgs() << "Callee body:\n" << *CalledFunc << "\n";
+  );
+
   // Determine if we are dealing with a call in an EHPad which does not unwind
   // to caller.
   bool EHPadForCallUnwindsLocally = false;

llvm/lib/Transforms/Utils/SCCPSolver.cpp

@@ -1168,6 +1168,11 @@ void SCCPInstVisitor::visitInstruction(Instruction &I) {
 bool SCCPInstVisitor::mergeInValue(ValueLatticeElement &IV, Value *V,
                                    ValueLatticeElement MergeWithV,
                                    ValueLatticeElement::MergeOptions Opts) {
+  if (const auto *Arg = dyn_cast<Argument>(V)) {
+    if (isa<PointerType>(Arg->getType()) &&
+        Arg->hasNoAliasAttr())
+      return false;  // do not merge w/ noalias ptr.
+  }
   if (IV.mergeIn(MergeWithV, Opts)) {
     pushUsersToWorkList(V);
     LLVM_DEBUG(dbgs() << "Merged " << MergeWithV << " into " << *V << " : "