[turbofan] Initial support for keyed access to holey elements.

src/compiler/access-info.cc

 // Copyright 2015 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 <ostream>
 
 #include "src/accessors.h"
 #include "src/compilation-dependencies.h"
 #include "src/compiler/access-info.h"
 #include "src/field-index-inl.h"
 #include "src/objects-inl.h"  // TODO(mstarzinger): Temporary cycle breaker!
 #include "src/type-cache.h"
 #include "src/types-inl.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 namespace {
 
 bool CanInlineElementAccess(Handle<Map> map) {
-  // TODO(bmeurer): Add support for holey elements.
-  return map->IsJSObjectMap() &&
-         IsFastPackedElementsKind(map->elements_kind()) &&
-         !map->has_indexed_interceptor() && !map->is_access_check_needed();
+  if (!map->IsJSObjectMap()) return false;
+  if (map->is_access_check_needed()) return false;
+  if (map->has_indexed_interceptor()) return false;
+  ElementsKind const elements_kind = map->elements_kind();
+  if (IsFastElementsKind(elements_kind)) return true;
+  // TODO(bmeurer): Add support for other elements kind.
+  return false;
 }
 
 
 bool CanInlinePropertyAccess(Handle<Map> map) {
   // We can inline property access to prototypes of all primitives, except
   // the special Oddball ones that have no wrapper counterparts (i.e. Null,
   // Undefined and TheHole).
   STATIC_ASSERT(ODDBALL_TYPE == LAST_PRIMITIVE_TYPE);
   if (map->IsBooleanMap()) return true;
   if (map->instance_type() < LAST_PRIMITIVE_TYPE) return true;
@@ skipping 94 matching lines @@
       isolate_(native_context->GetIsolate()),
       type_cache_(TypeCache::Get()),
       zone_(zone) {}
 
 
 bool AccessInfoFactory::ComputeElementAccessInfo(
     Handle<Map> map, AccessMode access_mode, ElementAccessInfo* access_info) {
   // Check if it is safe to inline element access for the {map}.
   if (!CanInlineElementAccess(map)) return false;
 
-  ElementsKind elements_kind = map->elements_kind();
+  ElementsKind const elements_kind = map->elements_kind();
+  if (access_mode == AccessMode::kLoad &&
+      elements_kind == FAST_HOLEY_DOUBLE_ELEMENTS) {
+    // TODO(bmeurer): Add support for holey loads.
+    return false;
+  }
 
   // Certain (monomorphic) stores need a prototype chain check because shape
   // changes could allow callbacks on elements in the chain that are not
   // compatible with monomorphic keyed stores.
   MaybeHandle<JSObject> holder;
   if (access_mode == AccessMode::kStore && map->prototype()->IsJSObject()) {
     for (PrototypeIterator i(map); !i.IsAtEnd(); i.Advance()) {
       Handle<JSReceiver> prototype =
           PrototypeIterator::GetCurrent<JSReceiver>(i);
       if (!prototype->IsJSObject()) return false;
@@ skipping 293 matching lines @@
   }
   return false;
 }
 
 
 Factory* AccessInfoFactory::factory() const { return isolate()->factory(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8