Compare IC: add STRINGS state.

src/x64/code-stubs-x64.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 4667 matching lines @@
 
   CompareStub stub(GetCondition(), strict(), NO_COMPARE_FLAGS);
   __ bind(&generic_stub);
   __ jmp(stub.GetCode(), RelocInfo::CODE_TARGET);
 
   __ bind(&miss);
   GenerateMiss(masm);
 }
 
 
+void ICCompareStub::GenerateStrings(MacroAssembler* masm) {
+  ASSERT(state_ == CompareIC::STRINGS);
+  Label miss;
+
+  // Registers containing left and right operands respectively.
+  Register left = rdx;
+  Register right = rax;
+  Register tmp1 = rcx;
+  Register tmp2 = rbx;
+  Register tmp3 = rdi;
+  Register tmp4 = r8;
+
+  // Check that both operands are heap objects.
+  Condition cond = masm->CheckEitherSmi(left, right, tmp1);
+  __ j(cond, &miss);
+
+  // Check that both operands are strings. This leaves the instance
+  // types loaded in tmp1 and tmp2.
+  __ movq(tmp1, FieldOperand(left, HeapObject::kMapOffset));
+  __ movq(tmp2, FieldOperand(right, HeapObject::kMapOffset));
+  __ movzxbq(tmp1, FieldOperand(tmp1, Map::kInstanceTypeOffset));
+  __ movzxbq(tmp2, FieldOperand(tmp2, Map::kInstanceTypeOffset));
+  __ movq(tmp3, tmp1);
+  STATIC_ASSERT(kNotStringTag != 0);
+  __ or_(tmp3, tmp2);
+  __ testl(tmp3, Immediate(kIsNotStringMask));
+  __ j(not_zero, &miss);
+
+  // Fast check for identical strings.
+  NearLabel not_same;
+  __ cmpq(left, right);
+  __ j(not_equal, &not_same);
+  STATIC_ASSERT(EQUAL == 0);
+  STATIC_ASSERT(kSmiTag == 0);
+  __ Move(rax, Smi::FromInt(EQUAL));
+  __ ret(0);
+
+  // Handle not identical strings.
+  __ bind(&not_same);
+
+  // Check that both strings are symbols. If they are, we're done
+  // because we already know they are not identical.
+  NearLabel do_compare;
+  ASSERT(GetCondition() == equal);
+  STATIC_ASSERT(kSymbolTag != 0);
+  __ and_(tmp1, tmp2);
+  __ testl(tmp1, Immediate(kIsSymbolMask));
+  __ j(zero, &do_compare);
+  // Make sure rax is non-zero. At this point input operands are
+  // guaranteed to be non-zero.
+  ASSERT(right.is(rax));
+  __ ret(0);
+
+  // Check that both strings are sequential ASCII.
+  Label runtime;
+  __ bind(&do_compare);
+  __ JumpIfNotBothSequentialAsciiStrings(left, right, tmp1, tmp2, &runtime);
+
+  // Compare flat ASCII strings. Returns when done.
+  StringCompareStub::GenerateCompareFlatAsciiStrings(
+      masm, left, right, tmp1, tmp2, tmp3, tmp4);
+
+  // Handle more complex cases in runtime.
+  __ bind(&runtime);
+  __ pop(tmp1);  // Return address.
+  __ push(left);
+  __ push(right);
+  __ push(tmp1);
+  __ TailCallRuntime(Runtime::kStringCompare, 2, 1);
+
+  __ bind(&miss);
+  GenerateMiss(masm);
+}
+
+
 void ICCompareStub::GenerateObjects(MacroAssembler* masm) {
   ASSERT(state_ == CompareIC::OBJECTS);
   NearLabel miss;
   Condition either_smi = masm->CheckEitherSmi(rdx, rax);
   __ j(either_smi, &miss);
 
   __ CmpObjectType(rax, JS_OBJECT_TYPE, rcx);
   __ j(not_equal, &miss, not_taken);
   __ CmpObjectType(rdx, JS_OBJECT_TYPE, rcx);
   __ j(not_equal, &miss, not_taken);
@@ skipping 36 matching lines @@
   // Do a tail call to the rewritten stub.
   __ jmp(rdi);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64