Compare IC: add SYMBOLS state.

src/ia32/code-stubs-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 5836 matching lines @@
 
   CompareStub stub(GetCondition(), strict(), NO_COMPARE_FLAGS);
   __ bind(&generic_stub);
   __ jmp(stub.GetCode(), RelocInfo::CODE_TARGET);
 
   __ bind(&miss);
   GenerateMiss(masm);
 }
 
 
+void ICCompareStub::GenerateSymbols(MacroAssembler* masm) {
+  ASSERT(state_ == CompareIC::SYMBOLS);
+  ASSERT(GetCondition() == equal);
+
+  // Registers containing left and right operands respectively.
+  Register left = edx;
+  Register right = eax;
+  Register tmp1 = ecx;
+  Register tmp2 = ebx;
+
+  // Check that both operands are heap objects.
+  NearLabel miss;
+  __ mov(tmp1, Operand(left));
+  STATIC_ASSERT(kSmiTag == 0);
+  __ and_(tmp1, Operand(right));
+  __ test(tmp1, Immediate(kSmiTagMask));
+  __ j(zero, &miss);
+
+  // Check that both operands are symbols.
+  __ mov(tmp1, FieldOperand(left, HeapObject::kMapOffset));
+  __ mov(tmp2, FieldOperand(right, HeapObject::kMapOffset));
+  __ movzx_b(tmp1, FieldOperand(tmp1, Map::kInstanceTypeOffset));
+  __ movzx_b(tmp2, FieldOperand(tmp2, Map::kInstanceTypeOffset));
+  STATIC_ASSERT(kSymbolTag != 0);
+  __ and_(tmp1, Operand(tmp2));
+  __ test(tmp1, Immediate(kIsSymbolMask));
+  __ j(zero, &miss);
+
+  // Symbols are compared by identity.
+  NearLabel done;
+  __ cmp(left, Operand(right));
+  // Make sure eax is non-zero. At this point input operands are
+  // guaranteed to be non-zero.
+  ASSERT(right.is(eax));
+  __ j(not_equal, &done);
+  STATIC_ASSERT(EQUAL == 0);
+  STATIC_ASSERT(kSmiTag == 0);
+  __ Set(eax, Immediate(Smi::FromInt(EQUAL)));
+  __ bind(&done);
+  __ ret(0);
+
+  __ bind(&miss);
+  GenerateMiss(masm);
+}
+
+
 void ICCompareStub::GenerateStrings(MacroAssembler* masm) {
   ASSERT(state_ == CompareIC::STRINGS);
   ASSERT(GetCondition() == equal);
   Label miss;
 
   // Registers containing left and right operands respectively.
   Register left = edx;
   Register right = eax;
   Register tmp1 = ecx;
   Register tmp2 = ebx;
@@ skipping 324 matching lines @@
   __ Drop(1);
   __ ret(2 * kPointerSize);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32