X64: implement DoHasCachedArrayIndex in lithium compiler.

src/x64/lithium-codegen-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 1614 matching lines @@
   Label* false_label = chunk_->GetAssemblyLabel(false_block);
 
   __ JumpIfSmi(input, false_label);
 
   __ CmpObjectType(input, TestType(instr->hydrogen()), kScratchRegister);
   EmitBranch(true_block, false_block, BranchCondition(instr->hydrogen()));
 }
 
 
 void LCodeGen::DoHasCachedArrayIndex(LHasCachedArrayIndex* instr) {
-  Abort("Unimplemented: %s", "DoHasCachedArrayIndex");
+  Register input = ToRegister(instr->InputAt(0));
+  Register result = ToRegister(instr->result());
+
+  ASSERT(instr->hydrogen()->value()->representation().IsTagged());
+  __ LoadRoot(result, Heap::kTrueValueRootIndex);
+  __ testl(FieldOperand(input, String::kHashFieldOffset),
+          Immediate(String::kContainsCachedArrayIndexMask));

[Lasse Reichstein, 2011/03/02 09:59:07]

Indentation.

[Rico, 2011/03/02 10:12:15]

Done.

+  NearLabel done;
+  __ j(not_zero, &done);
+  __ LoadRoot(result, Heap::kFalseValueRootIndex);

[Lasse Reichstein, 2011/03/02 09:59:07]

Could we do just one computed load from the root array here?
E.g.
  ASSERT(Heap::kTrueValueRootIndex + 1 == Heap::kFalseValueRootIndex);
  __ setcc(zero, result);
  __ movzxbl(result, result);
  __ LoadRoot(result, result, Heap::kTrueValueRootIndex);

(adding a 
  void LoadRoot(Register dst, Register dynIdx, int idx) {
    __ movq(dst, Operand(kRootRegister, dynIdx, times_pointer_size, idx *
kPointerSize);
  }
if it's not there already).

I think we use similar code elsewhere.

[Rico, 2011/03/02 10:12:15]

As discussed offline this will not really have any effect here, leaving it as is
to be consistent with the remainder of the lithium instructions.

+  __ bind(&done);
 }
 
 
 void LCodeGen::DoHasCachedArrayIndexAndBranch(
     LHasCachedArrayIndexAndBranch* instr) {
   Register input = ToRegister(instr->InputAt(0));
 
   int true_block = chunk_->LookupDestination(instr->true_block_id());
   int false_block = chunk_->LookupDestination(instr->false_block_id());
 
@@ skipping 1974 matching lines @@
   RegisterEnvironmentForDeoptimization(environment);
   ASSERT(osr_pc_offset_ == -1);
   osr_pc_offset_ = masm()->pc_offset();
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64