[string] Add a fast path to String.p.replace

src/code-stub-assembler.cc

 // Copyright 2016 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/code-stub-assembler.h"
 #include "src/code-factory.h"
 #include "src/frames-inl.h"
 #include "src/frames.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 2991 matching lines @@
       Int32Constant(kOneByteStringTag));
 }
 
 Node* CodeStubAssembler::IsSequentialStringInstanceType(Node* instance_type) {
   CSA_ASSERT(this, IsStringInstanceType(instance_type));
   return Word32Equal(
       Word32And(instance_type, Int32Constant(kStringRepresentationMask)),
       Int32Constant(kSeqStringTag));
 }
 
+Node* CodeStubAssembler::IsConsStringInstanceType(Node* instance_type) {
+  CSA_ASSERT(this, IsStringInstanceType(instance_type));
+  return Word32Equal(
+      Word32And(instance_type, Int32Constant(kStringRepresentationMask)),
+      Int32Constant(kConsStringTag));
+}
+
 Node* CodeStubAssembler::IsExternalStringInstanceType(Node* instance_type) {
   CSA_ASSERT(this, IsStringInstanceType(instance_type));
   return Word32Equal(
       Word32And(instance_type, Int32Constant(kStringRepresentationMask)),
       Int32Constant(kExternalStringTag));
 }
 
 Node* CodeStubAssembler::IsShortExternalStringInstanceType(
     Node* instance_type) {
   CSA_ASSERT(this, IsStringInstanceType(instance_type));
@@ skipping 5487 matching lines @@
         formatted.c_str(), TENURED);
     CallRuntime(Runtime::kGlobalPrint, NoContextConstant(),
                 HeapConstant(string));
   }
   CallRuntime(Runtime::kDebugPrint, NoContextConstant(), tagged_value);
 #endif
 }
 
 }  // namespace internal
 }  // namespace v8