Introduce read buffer for external strings when using charAt (ia32).

src/ia32/lithium-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 3387 matching lines @@
   class DeferredStringCharCodeAt: public LDeferredCode {
    public:
     DeferredStringCharCodeAt(LCodeGen* codegen, LStringCharCodeAt* instr)
         : LDeferredCode(codegen), instr_(instr) { }
     virtual void Generate() { codegen()->DoDeferredStringCharCodeAt(instr_); }
     virtual LInstruction* instr() { return instr_; }
    private:
     LStringCharCodeAt* instr_;
   };
 
-  Register string = ToRegister(instr->string());
-  Register index = ToRegister(instr->index());
-  Register result = ToRegister(instr->result());
-
   DeferredStringCharCodeAt* deferred =
       new DeferredStringCharCodeAt(this, instr);
 
-  // Fetch the instance type of the receiver into result register.
-  __ mov(result, FieldOperand(string, HeapObject::kMapOffset));
-  __ movzx_b(result, FieldOperand(result, Map::kInstanceTypeOffset));
-
-  // We need special handling for indirect strings.
-  Label check_sequential;
-  __ test(result, Immediate(kIsIndirectStringMask));
-  __ j(zero, &check_sequential, Label::kNear);
-
-  // Dispatch on the indirect string shape: slice or cons.
-  Label cons_string;
-  __ test(result, Immediate(kSlicedNotConsMask));
-  __ j(zero, &cons_string, Label::kNear);
-
-  // Handle slices.
-  Label indirect_string_loaded;
-  __ mov(result, FieldOperand(string, SlicedString::kOffsetOffset));
-  __ SmiUntag(result);
-  __ add(index, Operand(result));
-  __ mov(string, FieldOperand(string, SlicedString::kParentOffset));
-  __ jmp(&indirect_string_loaded, Label::kNear);
-
-  // Handle conses.
-  // 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.
-  __ bind(&cons_string);
-  __ cmp(FieldOperand(string, ConsString::kSecondOffset),
-         Immediate(factory()->empty_string()));
-  __ j(not_equal, deferred->entry());
-  __ mov(string, FieldOperand(string, ConsString::kFirstOffset));
-
-  __ bind(&indirect_string_loaded);
-  __ mov(result, FieldOperand(string, HeapObject::kMapOffset));
-  __ movzx_b(result, FieldOperand(result, Map::kInstanceTypeOffset));
-
-  // Check whether the string is sequential. The only non-sequential
-  // shapes we support have just been unwrapped above.
-  // 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(&check_sequential);
-  STATIC_ASSERT(kSeqStringTag == 0);
-  __ test(result, Immediate(kStringRepresentationMask));
-  __ j(not_zero, deferred->entry());
-
-  // Dispatch on the encoding: ASCII or two-byte.
-  Label ascii_string;
-  STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
-  STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
-  __ test(result, Immediate(kStringEncodingMask));
-  __ j(not_zero, &ascii_string, Label::kNear);
-
-  // Two-byte string.
-  // Load the two-byte character code into the result register.
-  Label done;
-  STATIC_ASSERT(kSmiTag == 0 && kSmiTagSize == 1);
-  __ movzx_w(result, FieldOperand(string,
-                                  index,
-                                  times_2,
-                                  SeqTwoByteString::kHeaderSize));
-  __ jmp(&done, Label::kNear);
-
-  // ASCII string.
-  // Load the byte into the result register.
-  __ bind(&ascii_string);
-  __ movzx_b(result, FieldOperand(string,
-                                  index,
-                                  times_1,
-                                  SeqAsciiString::kHeaderSize));
-  __ bind(&done);
+  StringCharCodeAtGenerator::GenerateCharLoad(masm(),
+                                              factory(),
+                                              ToRegister(instr->string()),
+                                              ToRegister(instr->index()),
+                                              ToRegister(instr->result()),
+                                              deferred->entry());
   __ bind(deferred->exit());
 }
 
 
 void LCodeGen::DoDeferredStringCharCodeAt(LStringCharCodeAt* instr) {
   Register string = ToRegister(instr->string());
   Register result = ToRegister(instr->result());
 
   // TODO(3095996): Get rid of this. For now, we need to make the
   // result register contain a valid pointer because it is already
@@ skipping 1089 matching lines @@
                                          env->deoptimization_index());
   __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION, safepoint_generator);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32