[stubs] Port SubStringStub to TurboFan

src/code-stubs.h

Index: src/code-stubs.h
diff --git a/src/code-stubs.h b/src/code-stubs.h
index 92bc298ebdc9fa495042b914edf7e13864bd0d43..7b9d76bfdb74760e3b79a844cbe70cabdc38c767 100644
--- a/src/code-stubs.h
+++ b/src/code-stubs.h
@@ -3094,13 +3094,24 @@ class StoreBufferOverflowStub : public PlatformCodeStub {
   DEFINE_PLATFORM_CODE_STUB(StoreBufferOverflow, PlatformCodeStub);
 };
 
-
-class SubStringStub : public PlatformCodeStub {
+class SubStringStub : public TurboFanCodeStub {
  public:
-  explicit SubStringStub(Isolate* isolate) : PlatformCodeStub(isolate) {}
+  explicit SubStringStub(Isolate* isolate) : TurboFanCodeStub(isolate) {}
+
+  static compiler::Node* Generate(CodeStubAssembler* assembler,
+                                  compiler::Node* string, compiler::Node* from,
+                                  compiler::Node* to, compiler::Node* context);
+
+  void GenerateAssembly(CodeStubAssembler* assembler) const override {
+    assembler->Return(Generate(assembler,
+                               assembler->Parameter(Descriptor::kString),
+                               assembler->Parameter(Descriptor::kFrom),
+                               assembler->Parameter(Descriptor::kTo),
+                               assembler->Parameter(Descriptor::kContext)));
+  }
 
   DEFINE_CALL_INTERFACE_DESCRIPTOR(SubString);
-  DEFINE_PLATFORM_CODE_STUB(SubString, PlatformCodeStub);
+  DEFINE_CODE_STUB(SubString, TurboFanCodeStub);
 };
 
 class ToStringStub final : public PlatformCodeStub {