[turbofan ] Simplify reference equal if both inputs are constants

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/1532063002

Cr-Commit-Position: refs/heads/master@{#32950}

src/compiler/simplified-operator-reducer.cc

@@ -89,6 +89,8 @@ Reduction SimplifiedOperatorReducer::Reduce(Node* node) {
       if (m.HasValue()) return ReplaceNumber(FastUI2D(m.Value()));
       break;
     }
+    case IrOpcode::kReferenceEqual:
+      return ReduceReferenceEqual(node);
     default:
       break;
   }
@@ -96,6 +98,23 @@ Reduction SimplifiedOperatorReducer::Reduce(Node* node) {
 }
 
 
+Reduction SimplifiedOperatorReducer::ReduceReferenceEqual(Node* node) {
+  DCHECK_EQ(IrOpcode::kReferenceEqual, node->opcode());
+  Node* const left = NodeProperties::GetValueInput(node, 0);
+  Node* const right = NodeProperties::GetValueInput(node, 1);
+  HeapObjectMatcher match_left(left);
+  HeapObjectMatcher match_right(right);
+  if (match_left.HasValue() && match_right.HasValue()) {
+    if (match_left.Value().is_identical_to(match_right.Value())) {
+      return Replace(jsgraph()->TrueConstant());
+    } else {
+      return Replace(jsgraph()->FalseConstant());
+    }
+  }
+  return NoChange();
+}
+
+
 Reduction SimplifiedOperatorReducer::Change(Node* node, const Operator* op,
                                             Node* a) {
   DCHECK_EQ(node->InputCount(), OperatorProperties::GetTotalInputCount(op));

src/compiler/simplified-operator-reducer.h

@@ -25,6 +25,8 @@ class SimplifiedOperatorReducer final : public Reducer {
   Reduction Reduce(Node* node) final;
 
  private:
+  Reduction ReduceReferenceEqual(Node* node);
+
   Reduction Change(Node* node, const Operator* op, Node* a);
   Reduction ReplaceFloat64(double value);
   Reduction ReplaceInt32(int32_t value);