Improve Array.shift() performance for small arrays.

src/ia32/lithium-codegen-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "v8.h"
 
 #if V8_TARGET_ARCH_IA32
 
 #include "ia32/lithium-codegen-ia32.h"
 #include "ic.h"
@@ skipping 4755 matching lines @@
     bool is_js_array = from_map->instance_type() == JS_ARRAY_TYPE;
     TransitionElementsKindStub stub(isolate(), from_kind, to_kind, is_js_array);
     __ CallStub(&stub);
     RecordSafepointWithLazyDeopt(instr,
         RECORD_SAFEPOINT_WITH_REGISTERS_AND_NO_ARGUMENTS);
   }
   __ bind(&not_applicable);
 }
 
 
+void LCodeGen::DoArrayShift(LArrayShift* instr) {
+  ASSERT(ToRegister(instr->context()).is(esi));
+  ASSERT(ToRegister(instr->object()).is(eax));
+  ASSERT(ToRegister(instr->result()).is(eax));
+  ArrayShiftStub stub(isolate(), instr->hydrogen()->kind());
+  CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
+}
+
+
 void LCodeGen::DoStringCharCodeAt(LStringCharCodeAt* instr) {
   class DeferredStringCharCodeAt V8_FINAL : public LDeferredCode {
    public:
     DeferredStringCharCodeAt(LCodeGen* codegen,
                              LStringCharCodeAt* instr,
                              const X87Stack& x87_stack)
         : LDeferredCode(codegen, x87_stack), instr_(instr) { }
     virtual void Generate() V8_OVERRIDE {
       codegen()->DoDeferredStringCharCodeAt(instr_);
     }
@@ skipping 1645 matching lines @@
   __ bind(deferred->exit());
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32