Porting r10252 to x64 (handle external strings in generated code when concatenating short strings).

src/ia32/code-stubs-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 5629 matching lines @@
   // edx: second string
   Label first_prepared, second_prepared;
   Label first_is_sequential, second_is_sequential;
   __ bind(&string_add_flat_result);
   __ mov(ecx, FieldOperand(eax, HeapObject::kMapOffset));
   __ movzx_b(ecx, FieldOperand(ecx, Map::kInstanceTypeOffset));
   // ecx: instance type of first string
   STATIC_ASSERT(kSeqStringTag == 0);
   __ test_b(ecx, kStringRepresentationMask);
   __ j(zero, &first_is_sequential, Label::kNear);
-  // Rule out short external string and prepare it so that offset-wise, it
-  // looks like a sequential string.
+  // Rule out short external string and load string resource.
   STATIC_ASSERT(kShortExternalStringTag != 0);
   __ test_b(ecx, kShortExternalStringMask);
   __ j(not_zero, &call_runtime);
   __ mov(eax, FieldOperand(eax, ExternalString::kResourceDataOffset));
   STATIC_ASSERT(SeqAsciiString::kHeaderSize == SeqTwoByteString::kHeaderSize);
   __ jmp(&first_prepared, Label::kNear);
   __ bind(&first_is_sequential);
   __ add(eax, Immediate(SeqAsciiString::kHeaderSize - kHeapObjectTag));
   __ bind(&first_prepared);
 
   __ mov(edi, FieldOperand(edx, HeapObject::kMapOffset));
   __ movzx_b(edi, FieldOperand(edi, Map::kInstanceTypeOffset));
   // Check whether both strings have same encoding.
   // edi: instance type of second string
   __ xor_(ecx, edi);
   __ test_b(ecx, kStringEncodingMask);
   __ j(not_zero, &call_runtime);
   STATIC_ASSERT(kSeqStringTag == 0);
   __ test_b(edi, kStringRepresentationMask);
   __ j(zero, &second_is_sequential, Label::kNear);
-  // Rule out short external string and prepare it so that offset-wise, it
-  // looks like a sequential string.
+  // Rule out short external string and load string resource.
   STATIC_ASSERT(kShortExternalStringTag != 0);
   __ test_b(edi, kShortExternalStringMask);
   __ j(not_zero, &call_runtime);
   __ mov(edx, FieldOperand(edx, ExternalString::kResourceDataOffset));
   STATIC_ASSERT(SeqAsciiString::kHeaderSize == SeqTwoByteString::kHeaderSize);
   __ jmp(&second_prepared, Label::kNear);
   __ bind(&second_is_sequential);
   __ add(edx, Immediate(SeqAsciiString::kHeaderSize - kHeapObjectTag));
   __ bind(&second_prepared);
 
@@ skipping 45 matching lines @@
   // eax: first string - known to be two byte
   // ebx: length of resulting flat string as a smi
   // edx: second string
   __ bind(&non_ascii_string_add_flat_result);
   // Both strings are two byte strings.
   __ SmiUntag(ebx);
   __ AllocateTwoByteString(eax, ebx, ecx, edx, edi, &call_runtime_drop_two);
   // eax: result string
   __ mov(ecx, eax);
   // Locate first character of result.
-  __ add(ecx,
-         Immediate(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
+  __ add(ecx, Immediate(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
   // Load second argument's length and first character location.  Account for
   // values currently on the stack when fetching arguments from it.
   __ mov(edx, Operand(esp, 4 * kPointerSize));
   __ mov(edi, FieldOperand(edx, String::kLengthOffset));
   __ SmiUntag(edi);
   __ pop(edx);
   // eax: result string
   // ecx: first character of result
   // edx: first char of first argument
   // edi: length of first argument
@@ skipping 1584 matching lines @@
                                  false);
   __ pop(edx);
   __ ret(0);
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32