ES6 symbols: Implement Symbol intrinsic and basic functionality

src/x64/code-stubs-x64.cc

 // Copyright 2012 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 5878 matching lines @@
   STATIC_ASSERT(kSmiTag == 0);
   __ Move(rax, Smi::FromInt(EQUAL));
   __ bind(&done);
   __ ret(0);
 
   __ bind(&miss);
   GenerateMiss(masm);
 }
 
 
+void ICCompareStub::GenerateUniqueNames(MacroAssembler* masm) {
+  ASSERT(state_ == CompareIC::UNIQUE_NAME);
+  ASSERT(GetCondition() == equal);
+
+  // Registers containing left and right operands respectively.
+  Register left = rdx;
+  Register right = rax;
+  Register tmp1 = rcx;
+  Register tmp2 = rbx;
+
+  // Check that both operands are heap objects.
+  Label miss;
+  Condition cond = masm->CheckEitherSmi(left, right, tmp1);
+  __ j(cond, &miss, Label::kNear);
+
+  // Check that both operands are unique names. This leaves the instance
+  // types loaded in tmp1 and tmp2.
+  STATIC_ASSERT(kInternalizedTag != 0);
+  __ movq(tmp1, FieldOperand(left, HeapObject::kMapOffset));
+  __ movq(tmp2, FieldOperand(right, HeapObject::kMapOffset));
+  __ movzxbq(tmp1, FieldOperand(tmp1, Map::kInstanceTypeOffset));
+  __ movzxbq(tmp2, FieldOperand(tmp2, Map::kInstanceTypeOffset));
+
+  Label succeed1;
+  __ testb(tmp1, Immediate(kIsInternalizedMask));
+  __ j(not_zero, &succeed1, Label::kNear);
+  __ cmpb(tmp1, Immediate(static_cast<int8_t>(SYMBOL_TYPE)));
+  __ j(not_equal, &miss, Label::kNear);
+  __ bind(&succeed1);
+
+  Label succeed2;
+  __ testb(tmp2, Immediate(kIsInternalizedMask));
+  __ j(not_zero, &succeed2, Label::kNear);
+  __ cmpb(tmp2, Immediate(static_cast<int8_t>(SYMBOL_TYPE)));
+  __ j(not_equal, &miss, Label::kNear);
+  __ bind(&succeed2);
+
+  // Unique names are compared by identity.
+  Label done;
+  __ cmpq(left, right);
+  // Make sure rax is non-zero. At this point input operands are
+  // guaranteed to be non-zero.
+  ASSERT(right.is(rax));
+  __ j(not_equal, &done, Label::kNear);
+  STATIC_ASSERT(EQUAL == 0);
+  STATIC_ASSERT(kSmiTag == 0);
+  __ Move(rax, Smi::FromInt(EQUAL));
+  __ bind(&done);
+  __ ret(0);
+
+  __ bind(&miss);
+  GenerateMiss(masm);
+}
+
+
 void ICCompareStub::GenerateStrings(MacroAssembler* masm) {
   ASSERT(state_ == CompareIC::STRING);
   Label miss;
 
   bool equality = Token::IsEqualityOp(op_);
 
   // Registers containing left and right operands respectively.
   Register left = rdx;
   Register right = rax;
   Register tmp1 = rcx;
@@ skipping 805 matching lines @@
 #endif
 
   __ Ret();
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64