Port r10023 to x64 (Add pointer cache field to external string).

src/ia32/codegen-ia32.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 545 matching lines @@
   // Handle external strings.
   Label external_string, ascii_external, done;
   __ bind(&external_string);
   if (FLAG_debug_code) {
     // Assert that we do not have a cons or slice (indirect strings) here.
     // Sequential strings have already been ruled out.
     __ test(result, Immediate(kIsIndirectStringMask));
     __ Assert(zero, "external string expected, but not found");
   }
   __ mov(result, FieldOperand(string, ExternalString::kResourceDataOffset));
-  // Assert that the external string has not been finalized yet.
+  // Assert that the data pointer cache is valid.

[Lasse Reichstein, 2011/11/24 09:21:42]

This shouldn't be necessary any more, right?
The cache, if it is there, is always valid.
Perhaps put this inside 'if (FLAG_debug_code) {' and make it a real Assert.

   __ test(result, result);
   __ j(zero, call_runtime);
   Register scratch = string;
   __ mov(scratch, FieldOperand(string, HeapObject::kMapOffset));
   __ cmp(scratch, Immediate(factory->external_ascii_string_map()));
   __ j(equal, &ascii_external, Label::kNear);
   __ cmp(scratch, Immediate(factory->external_ascii_symbol_map()));
   __ j(equal, &ascii_external, Label::kNear);
   // Two-byte string.
   __ movzx_w(result, Operand(result, index, times_2, 0));
@@ skipping 52 matching lines @@
                                   times_1,
                                   SeqAsciiString::kHeaderSize));
   __ bind(&done);
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32