ES6 symbols: Implement Symbol intrinsic and basic functionality

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 c1d26cb462c6f51990294b021bbfedde310dd08b..30ca6c694a92a8fe9b0917986a8ca4c1d440b760 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -5896,6 +5896,61 @@ void ICCompareStub::GenerateInternalizedStrings(MacroAssembler* 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;