[InstCombine] Address review comments. NFC.

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -3996,10 +3996,12 @@ Instruction *InstCombinerImpl::visitCallBase(CallBase &Call) {
     if (V->getType()->isPointerTy()) {
       // Simplify the nonnull operand if the parameter is known to be nonnull.
       // Otherwise, try to infer nonnull for it.
-      if (Call.paramHasNonNullAttr(ArgNo, /*AllowUndefOrPoison=*/true)) {
-        if (Value *Res = simplifyNonNullOperand(
-                V, /*HasDereferenceable=*/Call.getParamDereferenceableBytes(
-                       ArgNo) > 0)) {
+      bool HasDereferenceable = Call.getParamDereferenceableBytes(ArgNo) > 0;
+      if (Call.paramHasAttr(ArgNo, Attribute::NonNull) ||
+          (HasDereferenceable &&
+           !NullPointerIsDefined(Call.getFunction(),
+                                 V->getType()->getPointerAddressSpace()))) {
+        if (Value *Res = simplifyNonNullOperand(V, HasDereferenceable)) {
           replaceOperand(Call, ArgNo, Res);
           Changed = true;
         }

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

@@ -3593,12 +3593,12 @@ Instruction *InstCombinerImpl::visitReturnInst(ReturnInst &RI) {
   Function *F = RI.getFunction();
   Type *RetTy = RetVal->getType();
   if (RetTy->isPointerTy()) {
+    bool HasDereferenceable =
+        F->getAttributes().getRetDereferenceableBytes() > 0;
     if (F->hasRetAttribute(Attribute::NonNull) ||
-        (F->getAttributes().getRetDereferenceableBytes() > 0 &&
+        (HasDereferenceable &&
          !NullPointerIsDefined(F, RetTy->getPointerAddressSpace()))) {
-      if (Value *V = simplifyNonNullOperand(
-              RetVal, /*HasDereferenceable=*/F->getAttributes()
-                              .getRetDereferenceableBytes() > 0))
+      if (Value *V = simplifyNonNullOperand(RetVal, HasDereferenceable))
         return replaceOperand(RI, 0, V);
     }
   }