Improve Array.shift() performance for small arrays.

src/arm64/lithium-codegen-arm64.cc

 // Copyright 2013 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"
 
 #include "arm64/lithium-codegen-arm64.h"
 #include "arm64/lithium-gap-resolver-arm64.h"
 #include "code-stubs.h"
 #include "stub-cache.h"
@@ skipping 5726 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);
     RecordSafepointWithRegistersAndDoubles(
         instr->pointer_map(), 0, Safepoint::kLazyDeopt);
   }
   __ Bind(&not_applicable);
 }
 
 
+void LCodeGen::DoArrayShift(LArrayShift* instr) {
+  ASSERT(ToRegister(instr->context()).is(cp));
+  ASSERT(ToRegister(instr->object()).is(x0));
+  ASSERT(ToRegister(instr->result()).is(x0));
+  ArrayShiftStub stub(isolate(), instr->hydrogen()->kind());
+  CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
+}
+
+
 void LCodeGen::DoTrapAllocationMemento(LTrapAllocationMemento* instr) {
   Register object = ToRegister(instr->object());
   Register temp1 = ToRegister(instr->temp1());
   Register temp2 = ToRegister(instr->temp2());
 
   Label no_memento_found;
   __ TestJSArrayForAllocationMemento(object, temp1, temp2, &no_memento_found);
   DeoptimizeIf(eq, instr->environment());
   __ Bind(&no_memento_found);
 }
@@ skipping 236 matching lines @@
   __ Ldr(result, FieldMemOperand(object, JSObject::kPropertiesOffset));
   // Index is equal to negated out of object property index plus 1.
   __ Sub(result, result, Operand::UntagSmiAndScale(index, kPointerSizeLog2));
   __ Ldr(result, FieldMemOperand(result,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ Bind(deferred->exit());
   __ Bind(&done);
 }
 
 } }  // namespace v8::internal