Reland "In-object double fields unboxing (for 64-bit only)."

src/code-stubs-hydrogen.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 "src/v8.h"
 
 #include "src/bailout-reason.h"
 #include "src/code-stubs.h"
 #include "src/field-index.h"
 #include "src/hydrogen.h"
@@ skipping 520 matching lines @@
 
 HLoadNamedField* CodeStubGraphBuilderBase::BuildLoadNamedField(
     HValue* object, FieldIndex index) {
   Representation representation = index.is_double()
       ? Representation::Double()
       : Representation::Tagged();
   int offset = index.offset();
   HObjectAccess access = index.is_inobject()
       ? HObjectAccess::ForObservableJSObjectOffset(offset, representation)
       : HObjectAccess::ForBackingStoreOffset(offset, representation);
-  if (index.is_double()) {
+  if (index.is_double() &&
+      (!FLAG_unbox_double_fields || !index.is_inobject())) {
     // Load the heap number.
     object = Add<HLoadNamedField>(
         object, static_cast<HValue*>(NULL),
         access.WithRepresentation(Representation::Tagged()));
     // Load the double value from it.
     access = HObjectAccess::ForHeapNumberValue();
   }
   return Add<HLoadNamedField>(object, static_cast<HValue*>(NULL), access);
 }
 
@@ skipping 146 matching lines @@
     HValue* object, HValue* value, FieldIndex index,
     Representation representation, bool transition_to_field) {
   DCHECK(!index.is_double() || representation.IsDouble());
   int offset = index.offset();
   HObjectAccess access =
       index.is_inobject()
           ? HObjectAccess::ForObservableJSObjectOffset(offset, representation)
           : HObjectAccess::ForBackingStoreOffset(offset, representation);
 
   if (representation.IsDouble()) {
-    HObjectAccess heap_number_access =
-        access.WithRepresentation(Representation::Tagged());
-    if (transition_to_field) {
-      // The store requires a mutable HeapNumber to be allocated.
-      NoObservableSideEffectsScope no_side_effects(this);
-      HInstruction* heap_number_size = Add<HConstant>(HeapNumber::kSize);
+    if (!FLAG_unbox_double_fields || !index.is_inobject()) {
+      HObjectAccess heap_number_access =
+          access.WithRepresentation(Representation::Tagged());
+      if (transition_to_field) {
+        // The store requires a mutable HeapNumber to be allocated.
+        NoObservableSideEffectsScope no_side_effects(this);
+        HInstruction* heap_number_size = Add<HConstant>(HeapNumber::kSize);
 
-      // TODO(hpayer): Allocation site pretenuring support.
-      HInstruction* heap_number =
-          Add<HAllocate>(heap_number_size, HType::HeapObject(), NOT_TENURED,
-                         MUTABLE_HEAP_NUMBER_TYPE);
-      AddStoreMapConstant(heap_number,
-                          isolate()->factory()->mutable_heap_number_map());
-      Add<HStoreNamedField>(heap_number, HObjectAccess::ForHeapNumberValue(),
-                            value);
-      // Store the new mutable heap number into the object.
-      access = heap_number_access;
-      value = heap_number;
-    } else {
-      // Load the heap number.
-      object = Add<HLoadNamedField>(object, static_cast<HValue*>(NULL),
-                                    heap_number_access);
-      // Store the double value into it.
-      access = HObjectAccess::ForHeapNumberValue();
+        // TODO(hpayer): Allocation site pretenuring support.
+        HInstruction* heap_number =
+            Add<HAllocate>(heap_number_size, HType::HeapObject(), NOT_TENURED,
+                           MUTABLE_HEAP_NUMBER_TYPE);
+        AddStoreMapConstant(heap_number,
+                            isolate()->factory()->mutable_heap_number_map());
+        Add<HStoreNamedField>(heap_number, HObjectAccess::ForHeapNumberValue(),
+                              value);
+        // Store the new mutable heap number into the object.
+        access = heap_number_access;
+        value = heap_number;
+      } else {
+        // Load the heap number.
+        object = Add<HLoadNamedField>(object, static_cast<HValue*>(NULL),
+                                      heap_number_access);
+        // Store the double value into it.
+        access = HObjectAccess::ForHeapNumberValue();
+      }
     }
   } else if (representation.IsHeapObject()) {
     BuildCheckHeapObject(value);
   }
 
   Add<HStoreNamedField>(object, access, value, INITIALIZING_STORE);
 }
 
 
 template <>
@@ skipping 1262 matching lines @@
 
   // Probe the stub cache.
   Code::Flags flags = Code::RemoveTypeAndHolderFromFlags(
       Code::ComputeHandlerFlags(Code::LOAD_IC));
   Add<HTailCallThroughMegamorphicCache>(receiver, name, flags);
 
   // We never continue.
   return graph()->GetConstant0();
 }
 } }  // namespace v8::internal