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

src/arm/code-stubs-arm.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 5048 matching lines @@
 
   // If the index is non-smi trigger the non-smi case.
   __ JumpIfNotSmi(index_, &index_not_smi_);
   __ bind(&got_smi_index_);
 
   // Check for index out of range.
   __ ldr(ip, FieldMemOperand(object_, String::kLengthOffset));
   __ cmp(ip, Operand(index_));
   __ b(ls, index_out_of_range_);
 
-  // We need special handling for non-flat strings.
-  STATIC_ASSERT(kSeqStringTag == 0);
-  __ tst(result_, Operand(kStringRepresentationMask));
-  __ b(eq, &flat_string);
+  __ mov(index_, Operand(index_, ASR, kSmiTagSize));
 
-  // Handle non-flat strings.
-  __ and_(result_, result_, Operand(kStringRepresentationMask));
-  STATIC_ASSERT(kConsStringTag < kExternalStringTag);
-  STATIC_ASSERT(kSlicedStringTag > kExternalStringTag);
-  __ cmp(result_, Operand(kExternalStringTag));
-  __ b(gt, &sliced_string);
-  __ b(eq, &call_runtime_);
+  StringCharLoadGenerator::Generate(
+      masm, object_, index_, result_, &call_runtime_);

[Rico, 2011/11/24 06:55:15]

move masm up and put parameters on individual lines

[Yang, 2011/11/24 11:15:11]

Done.

 
-  // 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;
-  __ ldr(result_, FieldMemOperand(object_, ConsString::kSecondOffset));
-  __ LoadRoot(ip, Heap::kEmptyStringRootIndex);
-  __ cmp(result_, Operand(ip));
-  __ b(ne, &call_runtime_);
-  // Get the first of the two parts.
-  __ ldr(object_, FieldMemOperand(object_, ConsString::kFirstOffset));
-  __ jmp(&assure_seq_string);
-
-  // SlicedString, unpack and add offset.
-  __ bind(&sliced_string);
-  __ ldr(result_, FieldMemOperand(object_, SlicedString::kOffsetOffset));
-  __ add(index_, index_, result_);
-  __ ldr(object_, FieldMemOperand(object_, SlicedString::kParentOffset));
-
-  // Assure that we are dealing with a sequential string. Go to runtime if not.
-  __ bind(&assure_seq_string);
-  __ ldr(result_, FieldMemOperand(object_, HeapObject::kMapOffset));
-  __ ldrb(result_, FieldMemOperand(result_, Map::kInstanceTypeOffset));
-  // Check that parent is not an external string. Go to runtime otherwise.
-  // 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.
-  STATIC_ASSERT(kSeqStringTag == 0);
-  __ tst(result_, Operand(kStringRepresentationMask));
-  __ b(ne, &call_runtime_);
-
-  // Check for 1-byte or 2-byte string.
-  __ bind(&flat_string);
-  STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
-  STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
-  __ tst(result_, Operand(kStringEncodingMask));
-  __ b(ne, &ascii_string);
-
-  // 2-byte string.
-  // Load the 2-byte character code into the result register. We can
-  // add without shifting since the smi tag size is the log2 of the
-  // number of bytes in a two-byte character.
-  STATIC_ASSERT(kSmiTag == 0 && kSmiTagSize == 1 && kSmiShiftSize == 0);
-  __ add(index_, object_, Operand(index_));
-  __ ldrh(result_, FieldMemOperand(index_, SeqTwoByteString::kHeaderSize));
-  __ jmp(&got_char_code);
-
-  // ASCII string.
-  // Load the byte into the result register.
-  __ bind(&ascii_string);
-  __ add(index_, object_, Operand(index_, LSR, kSmiTagSize));
-  __ ldrb(result_, FieldMemOperand(index_, SeqAsciiString::kHeaderSize));
-
-  __ bind(&got_char_code);
   __ mov(result_, Operand(result_, LSL, kSmiTagSize));
   __ bind(&exit_);
 }
 
 
 void StringCharCodeAtGenerator::GenerateSlow(
     MacroAssembler* masm,
     const RuntimeCallHelper& call_helper) {
   __ Abort("Unexpected fallthrough to CharCodeAt slow case");
 
@@ skipping 26 matching lines @@
   // If index is still not a smi, it must be out of range.
   __ JumpIfNotSmi(index_, index_out_of_range_);
   // Otherwise, return to the fast path.
   __ jmp(&got_smi_index_);
 
   // Call runtime. We get here when the receiver is a string and the
   // index is a number, but the code of getting the actual character
   // is too complex (e.g., when the string needs to be flattened).
   __ bind(&call_runtime_);
   call_helper.BeforeCall(masm);
+  __ mov(index_, Operand(index_, LSL, kSmiTagSize));
   __ Push(object_, index_);
   __ CallRuntime(Runtime::kStringCharCodeAt, 2);
   __ Move(result_, r0);
   call_helper.AfterCall(masm);
   __ jmp(&exit_);
 
   __ Abort("Unexpected fallthrough from CharCodeAt slow case");
 }
 
 
@@ skipping 1986 matching lines @@
   __ StoreNumberToDoubleElements(r0, r3, r1, r5, r6, r7, r9, r10,
                                  &slow_elements);
   __ Ret();
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM