Add full TurboFan support for accessing SeqString contents.

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/v8.h"
 
 #include "src/arguments.h"
 #include "src/jsregexp-inl.h"
 #include "src/jsregexp.h"
 #include "src/runtime/runtime-utils.h"
@@ skipping 1247 matching lines @@
   DCHECK(args.length() == 2);
   if (!args[0]->IsString()) return Smi::FromInt(0);
   if (!args[1]->IsNumber()) return Smi::FromInt(0);
   if (std::isinf(args.number_at(1))) return isolate->heap()->empty_string();
   Object* code = __RT_impl_Runtime_StringCharCodeAtRT(args, isolate);
   if (code->IsNaN()) return isolate->heap()->empty_string();
   return __RT_impl_Runtime_CharFromCode(Arguments(1, &code), isolate);
 }
 
 
+RUNTIME_FUNCTION(Runtime_OneByteSeqStringGetChar) {
+  SealHandleScope shs(isolate);
+  DCHECK(args.length() == 2);
+  CONVERT_ARG_CHECKED(SeqOneByteString, string, 0);
+  CONVERT_INT32_ARG_CHECKED(index, 1);
+  return Smi::FromInt(string->SeqOneByteStringGet(index));
+}
+
+
 RUNTIME_FUNCTION(Runtime_OneByteSeqStringSetChar) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 3);
   CONVERT_INT32_ARG_CHECKED(index, 0);
   CONVERT_INT32_ARG_CHECKED(value, 1);
   CONVERT_ARG_CHECKED(SeqOneByteString, string, 2);
   string->SeqOneByteStringSet(index, value);
   return string;
 }
 
 
+RUNTIME_FUNCTION(Runtime_TwoByteSeqStringGetChar) {
+  SealHandleScope shs(isolate);
+  DCHECK(args.length() == 2);
+  CONVERT_ARG_CHECKED(SeqTwoByteString, string, 0);
+  CONVERT_INT32_ARG_CHECKED(index, 1);
+  return Smi::FromInt(string->SeqTwoByteStringGet(index));
+}
+
+
 RUNTIME_FUNCTION(Runtime_TwoByteSeqStringSetChar) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 3);
   CONVERT_INT32_ARG_CHECKED(index, 0);
   CONVERT_INT32_ARG_CHECKED(value, 1);
   CONVERT_ARG_CHECKED(SeqTwoByteString, string, 2);
   string->SeqTwoByteStringSet(index, value);
   return string;
 }
 
@@ skipping 15 matching lines @@
 
 
 RUNTIME_FUNCTION(Runtime_StringGetLength) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(String, s, 0);
   return Smi::FromInt(s->length());
 }
 }
 }  // namespace v8::internal