Compare IC: add SYMBOLS state.

src/arm/code-stubs-arm.cc

Index: src/arm/code-stubs-arm.cc
diff --git a/src/arm/code-stubs-arm.cc b/src/arm/code-stubs-arm.cc
index 10340b0db013c8ac7e99cdb6a856b2d3e825f8c5..0c4675eb46503ddf1a4e3f703f3fd52cca42a983 100644
--- a/src/arm/code-stubs-arm.cc
+++ b/src/arm/code-stubs-arm.cc
@@ -5961,6 +5961,44 @@ void ICCompareStub::GenerateHeapNumbers(MacroAssembler* masm) {
 }
 
 
+void ICCompareStub::GenerateSymbols(MacroAssembler* masm) {
+  ASSERT(state_ == CompareIC::SYMBOLS);
+  Label miss;
+
+  // Registers containing left and right operands respectively.
+  Register left = r1;
+  Register right = r0;
+  Register tmp1 = r2;
+  Register tmp2 = r3;
+
+  // Check that both operands are heap objects.
+  __ JumpIfEitherSmi(left, right, &miss);
+
+  // Check that both operands are symbols.
+  __ ldr(tmp1, FieldMemOperand(left, HeapObject::kMapOffset));
+  __ ldr(tmp2, FieldMemOperand(right, HeapObject::kMapOffset));
+  __ ldrb(tmp1, FieldMemOperand(tmp1, Map::kInstanceTypeOffset));
+  __ ldrb(tmp2, FieldMemOperand(tmp2, Map::kInstanceTypeOffset));
+  STATIC_ASSERT(kSymbolTag != 0);
+  __ and_(tmp1, tmp1, Operand(tmp2));
+  __ tst(tmp1, Operand(kIsSymbolMask));
+  __ b(eq, &miss);
+
+  // Symbols are compared by identity.
+  __ cmp(left, right);
+  // Make sure r0 is non-zero. At this point input operands are
+  // guaranteed to be non-zero.
+  ASSERT(right.is(r0));
+  STATIC_ASSERT(EQUAL == 0);
+  STATIC_ASSERT(kSmiTag == 0);
+  __ mov(r0, Operand(Smi::FromInt(EQUAL)), LeaveCC, eq);
+  __ Ret();
+
+  __ bind(&miss);
+  GenerateMiss(masm);
+}
+
+
 void ICCompareStub::GenerateStrings(MacroAssembler* masm) {
   ASSERT(state_ == CompareIC::STRINGS);
   Label miss;