HSubAllocatedObject instruction allows hydrogen code to carve up

src/hydrogen-instructions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 153 matching lines @@
   V(Sar)                                       \
   V(SeqStringSetChar)                          \
   V(Shl)                                       \
   V(Shr)                                       \
   V(Simulate)                                  \
   V(SoftDeoptimize)                            \
   V(StackCheck)                                \
   V(StoreContextSlot)                          \
   V(StoreGlobalCell)                           \
   V(StoreGlobalGeneric)                        \
+  V(SubAllocatedObject)                        \

[Hannes Payer (out of office), 2013/03/13 08:48:39]

alphabetic order.

[mvstanton, 2013/03/13 10:14:40]

Done.

   V(StoreKeyed)                                \
   V(StoreKeyedGeneric)                         \
   V(StoreNamedField)                           \
   V(StoreNamedGeneric)                         \
   V(StringAdd)                                 \
   V(StringCharCodeAt)                          \
   V(StringCharFromCode)                        \
   V(StringCompareAndBranch)                    \
   V(StringLength)                              \
   V(Sub)                                       \
@@ skipping 4500 matching lines @@
 };
 
 
 inline bool StoringValueNeedsWriteBarrier(HValue* value) {
   return !value->type().IsBoolean()
       && !value->type().IsSmi()
       && !(value->IsConstant() && HConstant::cast(value)->ImmortalImmovable());
 }
 
 
-inline bool ReceiverObjectNeedsWriteBarrier(HValue* object,
-                                            HValue* new_space_dominator) {
-  if (object != new_space_dominator) return true;
-  if (object->IsFastLiteral()) return false;
-  if (object->IsAllocateObject()) return false;
-  if (object->IsAllocate()) {
-    return !HAllocate::cast(object)->GuaranteedInNewSpace();
-  }
-  return true;
-}
-
-
 class HStoreGlobalCell: public HUnaryOperation {
  public:
   HStoreGlobalCell(HValue* value,
                    Handle<JSGlobalPropertyCell> cell,
                    PropertyDetails details)
       : HUnaryOperation(value),
         cell_(cell),
         details_(details) {
     SetGVNFlag(kChangesGlobalVars);
   }
@@ skipping 492 matching lines @@
     // tagged[tagged]
     return Representation::Tagged();
   }
 
   virtual HValue* Canonicalize();
 
   DECLARE_CONCRETE_INSTRUCTION(LoadKeyedGeneric)
 };
 
 
+bool ReceiverObjectNeedsWriteBarrier(HValue* object,
+                                     HValue* new_space_dominator);
+

[Hannes Payer (out of office), 2013/03/13 08:48:39]

Can you move code around that you do not need this forward declaration? It would
be nice to keep ReceiverObjectNeedsWriteBarrier() where it was to have a clean
diff.

[mvstanton, 2013/03/13 10:14:40]

That is much better, thx...I was lazy :).

+
 class HStoreNamedField: public HTemplateInstruction<2> {
  public:
   HStoreNamedField(HValue* obj,
                    Handle<String> name,
                    HValue* val,
                    bool in_object,
                    int offset)
       : name_(name),
         is_in_object_(in_object),
         offset_(offset),
@@ skipping 76 matching lines @@
   }
 
   DECLARE_CONCRETE_INSTRUCTION(StoreNamedGeneric)
 
  private:
   Handle<String> name_;
   StrictModeFlag strict_mode_flag_;
 };
 
 
+class HSubAllocatedObject: public HTemplateInstruction<1> {
+ public:
+  HSubAllocatedObject(HValue* value, int offset)
+      : offset_(offset) {
+    ASSERT(value->IsAllocate());
+    SetOperandAt(0, value);
+    set_representation(Representation::Tagged());
+  }
+
+  HValue* base_object() { return OperandAt(0); }
+  int offset() { return offset_; }
+
+  virtual Representation RequiredInputRepresentation(int index) {
+    return Representation::Tagged();
+  }
+
+  virtual void PrintDataTo(StringStream* stream);
+
+  DECLARE_CONCRETE_INSTRUCTION(SubAllocatedObject)

[Michael Starzinger, 2013/03/13 09:12:35]

Empty newline before the "private:" block.

[mvstanton, 2013/03/13 10:14:40]

Done.

+ private:
+  int offset_;
+};
+
+
+inline bool ReceiverObjectNeedsWriteBarrier(HValue* object,
+                                            HValue* new_space_dominator) {
+  if (object->IsSubAllocatedObject()) {
+    return ReceiverObjectNeedsWriteBarrier(
+        HSubAllocatedObject::cast(object)->base_object(),
+        new_space_dominator);
+  }
+  if (object != new_space_dominator) return true;
+  if (object->IsFastLiteral()) return false;
+  if (object->IsAllocateObject()) return false;
+  if (object->IsAllocate()) {
+    return !HAllocate::cast(object)->GuaranteedInNewSpace();
+  }
+  return true;
+}
+
+
 class HStoreKeyed
     : public HTemplateInstruction<3>, public ArrayInstructionInterface {
  public:
   HStoreKeyed(HValue* obj, HValue* key, HValue* val,
               ElementsKind elements_kind)
       : elements_kind_(elements_kind),
       index_offset_(0),
       is_dehoisted_(false),
       new_space_dominator_(NULL) {
     SetOperandAt(0, obj);
@@ skipping 843 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_