Improve Array.shift() performance for small arrays.

src/hydrogen-instructions.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"
 
 #include "double.h"
 #include "factory.h"
 #include "hydrogen-infer-representation.h"
 #include "property-details-inl.h"
@@ skipping 799 matching lines @@
 
 bool HInstruction::CanDeoptimize() {
   // TODO(titzer): make this a virtual method?
   switch (opcode()) {
     case HValue::kAbnormalExit:
     case HValue::kAccessArgumentsAt:
     case HValue::kAllocate:
     case HValue::kArgumentsElements:
     case HValue::kArgumentsLength:
     case HValue::kArgumentsObject:
+    case HValue::kArrayShift:
     case HValue::kBlockEntry:
     case HValue::kBoundsCheckBaseIndexInformation:
     case HValue::kCallFunction:
     case HValue::kCallJSFunction:
     case HValue::kCallNew:
     case HValue::kCallNewArray:
     case HValue::kCallStub:
     case HValue::kCallWithDescriptor:
     case HValue::kCapturedObject:
     case HValue::kClassOfTestAndBranch:
@@ skipping 2800 matching lines @@
   ElementsKind to_kind = transitioned_map().handle()->elements_kind();
   stream->Add(" %p [%s] -> %p [%s]",
               *original_map().handle(),
               ElementsAccessor::ForKind(from_kind)->name(),
               *transitioned_map().handle(),
               ElementsAccessor::ForKind(to_kind)->name());
   if (IsSimpleMapChangeTransition(from_kind, to_kind)) stream->Add(" (simple)");
 }
 
 
+void HArrayShift::PrintDataTo(StringStream* stream) {
+  object()->PrintNameTo(stream);
+  stream->Add(" [%s]", ElementsAccessor::ForKind(kind())->name());
+}
+
+
 void HLoadGlobalCell::PrintDataTo(StringStream* stream) {
   stream->Add("[%p]", *cell().handle());
   if (!details_.IsDontDelete()) stream->Add(" (deleteable)");
   if (details_.IsReadOnly()) stream->Add(" (read-only)");
 }
 
 
 bool HLoadGlobalCell::RequiresHoleCheck() const {
   if (details_.IsDontDelete() && !details_.IsReadOnly()) return false;
   for (HUseIterator it(uses()); !it.Done(); it.Advance()) {
@@ skipping 1126 matching lines @@
       break;
     case kExternalMemory:
       stream->Add("[external-memory]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal