[runtime] Port simple String.prototype.indexOf cases to TF Builtin

src/runtime/runtime-strings.cc

 // Copyright 2014 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/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/regexp/jsregexp-inl.h"
 #include "src/string-builder.h"
 #include "src/string-search.h"
@@ skipping 68 matching lines @@
   subject = String::Flatten(subject);
   if (StringReplaceOneCharWithString(isolate, subject, search, replace, &found,
                                      kRecursionLimit).ToHandle(&result)) {
     return *result;
   }
   if (isolate->has_pending_exception()) return isolate->heap()->exception();
   // In case of empty handle and no pending exception we have stack overflow.
   return isolate->StackOverflow();
 }
 
-
+// ES6 #sec-string.prototype.indexof
+// String.prototype.indexOf(searchString [, position])
 RUNTIME_FUNCTION(Runtime_StringIndexOf) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 3);
-  return String::IndexOf(isolate, args.at<Object>(0), args.at<Object>(1),
-                         args.at<Object>(2));
+  return String::IndexOf(isolate, args.at(0), args.at(1), args.at(2));
+}
+
+// ES6 #sec-string.prototype.indexof
+// String.prototype.indexOf(searchString, position)
+// Fast version that assumes that does not perform conversions of the incoming
+// arguments.
+RUNTIME_FUNCTION(Runtime_StringIndexOfUnchecked) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 3);
+  Handle<String> receiver_string = args.at<String>(0);
+  Handle<String> search_string = args.at<String>(1);
+  int index = std::min(std::max(args.smi_at(2), 0), receiver_string->length());
+
+  return Smi::FromInt(String::IndexOf(isolate, receiver_string, search_string,
+                                      static_cast<uint32_t>(index)));
 }
 
 RUNTIME_FUNCTION(Runtime_StringLastIndexOf) {
   HandleScope handle_scope(isolate);
-  return String::LastIndexOf(isolate, args.at<Object>(0), args.at<Object>(1),
+  return String::LastIndexOf(isolate, args.at(0), args.at(1),
                              isolate->factory()->undefined_value());
 }
 
 RUNTIME_FUNCTION(Runtime_SubString) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 3);
 
   CONVERT_ARG_HANDLE_CHECKED(String, string, 0);
   int start, end;
   // We have a fast integer-only case here to avoid a conversion to double in
@@ skipping 874 matching lines @@
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 2);
   if (!args[0]->IsString()) return isolate->heap()->undefined_value();
   if (!args[1]->IsNumber()) return isolate->heap()->undefined_value();
   if (std::isinf(args.number_at(1))) return isolate->heap()->nan_value();
   return __RT_impl_Runtime_StringCharCodeAtRT(args, isolate);
 }
 
 }  // namespace internal
 }  // namespace v8