Revert of [regexp] Remove IsRegExp intrinsic

test/unittests/compiler/js-intrinsic-lowering-unittest.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/access-builder.h"
 #include "src/compiler/diamond.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/js-intrinsic-lowering.h"
 #include "src/compiler/js-operator.h"
 #include "test/unittests/compiler/graph-unittest.h"
@@ skipping 111 matching lines @@
                                                 effect, CaptureEq(&if_false)),
                                     effect, _),
                         IsNumberConstant(JS_TYPED_ARRAY_TYPE)),
           IsMerge(IsIfTrue(AllOf(CaptureEq(&branch),
                                  IsBranch(IsObjectIsSmi(input), control))),
                   AllOf(CaptureEq(&if_false), IsIfFalse(CaptureEq(&branch))))));
 }
 
 
 // -----------------------------------------------------------------------------
+// %_IsRegExp
+
+
+TEST_F(JSIntrinsicLoweringTest, InlineIsRegExp) {
+  Node* const input = Parameter(0);
+  Node* const context = Parameter(1);
+  Node* const effect = graph()->start();
+  Node* const control = graph()->start();
+  Reduction const r = Reduce(
+      graph()->NewNode(javascript()->CallRuntime(Runtime::kInlineIsRegExp, 1),
+                       input, context, effect, control));
+  ASSERT_TRUE(r.Changed());
+
+  Node* phi = r.replacement();
+  Capture<Node*> branch, if_false;
+  EXPECT_THAT(
+      phi,
+      IsPhi(
+          MachineRepresentation::kTagged, IsFalseConstant(),
+          IsNumberEqual(IsLoadField(AccessBuilder::ForMapInstanceType(),
+                                    IsLoadField(AccessBuilder::ForMap(), input,
+                                                effect, CaptureEq(&if_false)),
+                                    effect, _),
+                        IsNumberConstant(JS_REGEXP_TYPE)),
+          IsMerge(IsIfTrue(AllOf(CaptureEq(&branch),
+                                 IsBranch(IsObjectIsSmi(input), control))),
+                  AllOf(CaptureEq(&if_false), IsIfFalse(CaptureEq(&branch))))));
+}
+
+
+// -----------------------------------------------------------------------------
 // %_IsJSReceiver
 
 
 TEST_F(JSIntrinsicLoweringTest, InlineIsJSReceiver) {
   Node* const input = Parameter(0);
   Node* const context = Parameter(1);
   Node* const effect = graph()->start();
   Node* const control = graph()->start();
   Reduction const r = Reduce(graph()->NewNode(
       javascript()->CallRuntime(Runtime::kInlineIsJSReceiver, 1), input,
       context, effect, control));
   ASSERT_TRUE(r.Changed());
   EXPECT_THAT(r.replacement(), IsObjectIsReceiver(input));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8