[builtins] Migrate StringToNumber to TurboFan builtin.

src/builtins/builtins-conversion.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/builtins/builtins.h"
 #include "src/builtins/builtins-utils.h"
 #include "src/code-factory.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 91 matching lines @@
 void Builtins::Generate_NonPrimitiveToPrimitive_Number(
     CodeStubAssembler* assembler) {
   Generate_NonPrimitiveToPrimitive(assembler, ToPrimitiveHint::kNumber);
 }
 
 void Builtins::Generate_NonPrimitiveToPrimitive_String(
     CodeStubAssembler* assembler) {
   Generate_NonPrimitiveToPrimitive(assembler, ToPrimitiveHint::kString);
 }
 
+void Builtins::Generate_StringToNumber(CodeStubAssembler* assembler) {
+  typedef CodeStubAssembler::Label Label;
+  typedef compiler::Node Node;
+  typedef TypeConversionDescriptor Descriptor;
+
+  Node* input = assembler->Parameter(Descriptor::kArgument);
+  Node* context = assembler->Parameter(Descriptor::kContext);
+
+  Label runtime(assembler);
+
+  // Check if string has a cached array index.
+  Node* hash = assembler->LoadNameHashField(input);
+  Node* bit = assembler->Word32And(
+      hash, assembler->Int32Constant(String::kContainsCachedArrayIndexMask));
+  assembler->GotoIf(assembler->Word32NotEqual(bit, assembler->Int32Constant(0)),
+                    &runtime);
+
+  assembler->Return(assembler->SmiTag(
+      assembler->BitFieldDecode<String::ArrayIndexValueBits>(hash)));
+
+  assembler->Bind(&runtime);
+  {
+    // Note: We cannot tail call to the runtime here, as js-to-wasm
+    // trampolines also use this code currently, and they declare all
+    // outgoing parameters as untagged, while we would push a tagged
+    // object here.
+    Node* result =
+        assembler->CallRuntime(Runtime::kStringToNumber, context, input);
+    assembler->Return(result);
+  }
+}
+
 // ES6 section 7.1.3 ToNumber ( argument )
 void Builtins::Generate_NonNumberToNumber(CodeStubAssembler* assembler) {
   typedef CodeStubAssembler::Label Label;
   typedef compiler::Node Node;
   typedef CodeStubAssembler::Variable Variable;
   typedef TypeConversionDescriptor Descriptor;
 
   Node* input = assembler->Parameter(Descriptor::kArgument);
   Node* context = assembler->Parameter(Descriptor::kContext);
 
@@ skipping 194 matching lines @@
 
   assembler->Bind(&return_true);
   assembler->Return(assembler->BooleanConstant(true));
 
   assembler->Bind(&return_false);
   assembler->Return(assembler->BooleanConstant(false));
 }
 
 }  // namespace internal
 }  // namespace v8