Porting r10023 and r10054 to x64 (pointer cache for external strings).

src/x64/code-stubs-x64.cc

Index: src/x64/code-stubs-x64.cc
diff --git a/src/x64/code-stubs-x64.cc b/src/x64/code-stubs-x64.cc
index b8f820d7f5581e9727731f61fa8481a751258aa0..19326f2775ea2e7205015243eb96291c006d3107 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -4157,70 +4157,11 @@ void StringCharCodeAtGenerator::GenerateFast(MacroAssembler* masm) {
   __ SmiCompare(index_, FieldOperand(object_, String::kLengthOffset));
   __ j(above_equal, index_out_of_range_);
 
-  // We need special handling for non-flat strings.
-  STATIC_ASSERT(kSeqStringTag == 0);
-  __ testb(result_, Immediate(kStringRepresentationMask));
-  __ j(zero, &flat_string);
+  __ SmiToInteger32(index_, index_);
 
-  // Handle non-flat strings.
-  __ and_(result_, Immediate(kStringRepresentationMask));
-  STATIC_ASSERT(kConsStringTag < kExternalStringTag);
-  STATIC_ASSERT(kSlicedStringTag > kExternalStringTag);
-  __ cmpb(result_, Immediate(kExternalStringTag));
-  __ j(greater, &sliced_string);
-  __ j(equal, &call_runtime_);
-
-  // ConsString.
-  // Check whether the right hand side is the empty string (i.e. if
-  // this is really a flat string in a cons string). If that is not
-  // the case we would rather go to the runtime system now to flatten
-  // the string.
-  Label assure_seq_string;
-  __ CompareRoot(FieldOperand(object_, ConsString::kSecondOffset),
-                 Heap::kEmptyStringRootIndex);
-  __ j(not_equal, &call_runtime_);
-  // Get the first of the two parts.
-  __ movq(object_, FieldOperand(object_, ConsString::kFirstOffset));
-  __ jmp(&assure_seq_string, Label::kNear);
-
-  // SlicedString, unpack and add offset.
-  __ bind(&sliced_string);
-  __ addq(index_, FieldOperand(object_, SlicedString::kOffsetOffset));
-  __ movq(object_, FieldOperand(object_, SlicedString::kParentOffset));
-
-  // Assure that we are dealing with a sequential string. Go to runtime if not.
-  // Note that if the original string is a cons or slice with an external
-  // string as underlying string, we pass that unpacked underlying string with
-  // the adjusted index to the runtime function.
-  __ bind(&assure_seq_string);
-  __ movq(result_, FieldOperand(object_, HeapObject::kMapOffset));
-  __ movzxbl(result_, FieldOperand(result_, Map::kInstanceTypeOffset));
-  STATIC_ASSERT(kSeqStringTag == 0);
-  __ testb(result_, Immediate(kStringRepresentationMask));
-  __ j(not_zero, &call_runtime_);
+  StringCharLoadGenerator::Generate(
+      masm, object_, index_, result_, &call_runtime_);
 
-  // Check for 1-byte or 2-byte string.
-  __ bind(&flat_string);
-  STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
-  STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
-  __ SmiToInteger32(index_, index_);
-  __ testb(result_, Immediate(kStringEncodingMask));
-  __ j(not_zero, &ascii_string);
-
-  // 2-byte string.
-  // Load the 2-byte character code into the result register.
-  __ movzxwl(result_, FieldOperand(object_,
-                                   index_, times_2,
-                                   SeqTwoByteString::kHeaderSize));
-  __ jmp(&got_char_code);
-
-  // ASCII string.
-  // Load the byte into the result register.
-  __ bind(&ascii_string);
-  __ movzxbl(result_, FieldOperand(object_,
-                                   index_, times_1,
-                                   SeqAsciiString::kHeaderSize));
-  __ bind(&got_char_code);
   __ Integer32ToSmi(result_, result_);
   __ bind(&exit_);
 }
@@ -4270,6 +4211,7 @@ void StringCharCodeAtGenerator::GenerateSlow(
   __ bind(&call_runtime_);
   call_helper.BeforeCall(masm);
   __ push(object_);
+  __ Integer32ToSmi(index_, index_);
   __ push(index_);
   __ CallRuntime(Runtime::kStringCharCodeAt, 2);
   if (!result_.is(rax)) {