[builtins] Create StringToNumber helper.

src/builtins/builtins-conversion.cc

Index: src/builtins/builtins-conversion.cc
diff --git a/src/builtins/builtins-conversion.cc b/src/builtins/builtins-conversion.cc
index 0d04a02e241132e87aaea3ffb17add337002e901..9cb9eeadf7f329f9219f3ef08d7b44fff4c1a80e 100644
--- a/src/builtins/builtins-conversion.cc
+++ b/src/builtins/builtins-conversion.cc
@@ -109,15 +109,17 @@ void Builtins::Generate_NonPrimitiveToPrimitive_String(
   Generate_NonPrimitiveToPrimitive(assembler, ToPrimitiveHint::kString);
 }
 
-void Builtins::Generate_StringToNumber(CodeStubAssembler* assembler) {
+compiler::Node* Builtins::GenerateImpl_StringToNumber(
+    CodeStubAssembler* assembler, compiler::Node* input,
+    compiler::Node* context) {
   typedef CodeStubAssembler::Label Label;
   typedef compiler::Node Node;
-  typedef TypeConversionDescriptor Descriptor;
+  typedef CodeStubAssembler::Variable Variable;
 
-  Node* input = assembler->Parameter(Descriptor::kArgument);
-  Node* context = assembler->Parameter(Descriptor::kContext);
+  Label runtime(assembler, Label::kDeferred);
+  Label end(assembler);
 
-  Label runtime(assembler);
+  Variable var_result(assembler, MachineRepresentation::kTagged);
 
   // Check if string has a cached array index.
   Node* hash = assembler->LoadNameHashField(input);
@@ -126,8 +128,9 @@ void Builtins::Generate_StringToNumber(CodeStubAssembler* assembler) {
   assembler->GotoIf(assembler->Word32NotEqual(bit, assembler->Int32Constant(0)),
                     &runtime);
 
-  assembler->Return(assembler->SmiTag(
+  var_result.Bind(assembler->SmiTag(
       assembler->BitFieldDecode<String::ArrayIndexValueBits>(hash)));
+  assembler->Goto(&end);
 
   assembler->Bind(&runtime);
   {
@@ -135,10 +138,20 @@ void Builtins::Generate_StringToNumber(CodeStubAssembler* assembler) {
     // 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);
+    var_result.Bind(
+        assembler->CallRuntime(Runtime::kStringToNumber, context, input));
+    assembler->Goto(&end);
   }
+
+  assembler->Bind(&end);
+  return var_result.value();
+}
+
+void Builtins::Generate_StringToNumber(CodeStubAssembler* assembler) {
+  typedef TypeConversionDescriptor Descriptor;
+  assembler->Return(Builtins::GenerateImpl_StringToNumber(
+      assembler, assembler->Parameter(Descriptor::kArgument),
+      assembler->Parameter(Descriptor::kContext)));
 }
 
 // ES6 section 7.1.3 ToNumber ( argument )
@@ -183,9 +196,8 @@ void Builtins::Generate_NonNumberToNumber(CodeStubAssembler* assembler) {
     assembler->Bind(&if_inputisstring);
     {
       // The {input} is a String, use the fast stub to convert it to a Number.
-      // TODO(bmeurer): Consider inlining the StringToNumber logic here.
-      Callable callable = CodeFactory::StringToNumber(assembler->isolate());
-      assembler->TailCallStub(callable, context, input);
+      assembler->Return(
+          Builtins::GenerateImpl_StringToNumber(assembler, input, context));
     }
 
     assembler->Bind(&if_inputisoddball);