[turbofan] Properly rename receiver on CheckHeapObject.

src/compiler/js-builtin-reducer.cc

Index: src/compiler/js-builtin-reducer.cc
diff --git a/src/compiler/js-builtin-reducer.cc b/src/compiler/js-builtin-reducer.cc
index a09e6f1b2139b95677dc258b87dfe8187403d68b..8bc03fae6239b850a901aab90cc41bf09ee30983 100644
--- a/src/compiler/js-builtin-reducer.cc
+++ b/src/compiler/js-builtin-reducer.cc
@@ -107,6 +107,19 @@ JSBuiltinReducer::JSBuiltinReducer(Editor* editor, JSGraph* jsgraph,
 
 namespace {
 
+// TODO(turbofan): Shall we move this to the NodeProperties? Or some (untyped)
+// alias analyzer?
+bool IsSame(Node* a, Node* b) {
+  if (a == b) {
+    return true;
+  } else if (a->opcode() == IrOpcode::kCheckHeapObject) {
+    return IsSame(a->InputAt(0), b);
+  } else if (b->opcode() == IrOpcode::kCheckHeapObject) {
+    return IsSame(a, b->InputAt(0));
+  }
+  return false;
+}
+
 MaybeHandle<Map> GetMapWitness(Node* node) {
   Node* receiver = NodeProperties::GetValueInput(node, 1);
   Node* effect = NodeProperties::GetEffectInput(node);
@@ -114,7 +127,7 @@ MaybeHandle<Map> GetMapWitness(Node* node) {
   // for the {receiver}, and if so use that map for the lowering below.
   for (Node* dominator = effect;;) {
     if (dominator->opcode() == IrOpcode::kCheckMaps &&
-        dominator->InputAt(0) == receiver) {
+        IsSame(dominator->InputAt(0), receiver)) {
       if (dominator->op()->ValueInputCount() == 2) {
         HeapObjectMatcher m(dominator->InputAt(1));
         if (m.HasValue()) return Handle<Map>::cast(m.Value());
@@ -331,7 +344,7 @@ bool HasInstanceTypeWitness(Node* receiver, Node* effect,
                             InstanceType instance_type) {
   for (Node* dominator = effect;;) {
     if (dominator->opcode() == IrOpcode::kCheckMaps &&
-        dominator->InputAt(0) == receiver) {
+        IsSame(dominator->InputAt(0), receiver)) {
       // Check if all maps have the given {instance_type}.
       for (int i = 1; i < dominator->op()->ValueInputCount(); ++i) {
         Node* const map = NodeProperties::GetValueInput(dominator, i);
@@ -922,7 +935,7 @@ Node* GetStringWitness(Node* node) {
   // the lowering below.
   for (Node* dominator = effect;;) {
     if (dominator->opcode() == IrOpcode::kCheckString &&
-        dominator->InputAt(0) == receiver) {
+        IsSame(dominator->InputAt(0), receiver)) {
       return dominator;
     }
     if (dominator->op()->EffectInputCount() != 1) {