Skip canonicalization of packed arrays in HStoreKeyedFastDoubleElement

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 0f6cb6e473d7454dd9cb1709f3b2faef1f1feaf3..f593bcbc647421dd058003b616ee7f6a6d555c5c 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -4302,8 +4302,11 @@ class HStoreKeyedFastDoubleElement
  public:
   HStoreKeyedFastDoubleElement(HValue* elements,
                                HValue* key,
-                               HValue* val)
-      : index_offset_(0), is_dehoisted_(false) {
+                               HValue* val,
+                               ElementsKind element_kind)

[Jakob Kummerow, 2012/06/05 09:05:40]

nit: for consistency, "elements_kind" (with 's') please.

+      : index_offset_(0), bit_field_(0) {
+    bit_field_ = IsDehoisted::encode(false) |
+        SkipCanonicalization::encode(IsFastPackedElementsKind(element_kind));
     SetOperandAt(0, elements);
     SetOperandAt(1, key);
     SetOperandAt(2, val);
@@ -4327,8 +4330,10 @@ class HStoreKeyedFastDoubleElement
   void SetIndexOffset(uint32_t index_offset) { index_offset_ = index_offset; }
   HValue* GetKey() { return key(); }
   void SetKey(HValue* key) { SetOperandAt(1, key); }
-  bool IsDehoisted() { return is_dehoisted_; }
-  void SetDehoisted(bool is_dehoisted) { is_dehoisted_ = is_dehoisted; }
+  bool IsDehoisted() { return IsDehoisted::decode(bit_field_); }
+  void SetDehoisted(bool is_dehoisted) {
+    bit_field_ = IsDehoisted::update(bit_field_, is_dehoisted);
+  }
 
   bool NeedsWriteBarrier() {
     return StoringValueNeedsWriteBarrier(value());
@@ -4341,8 +4346,11 @@ class HStoreKeyedFastDoubleElement
   DECLARE_CONCRETE_INSTRUCTION(StoreKeyedFastDoubleElement)
 
  private:
+  class IsDehoisted:           public BitField<bool, 0, 1> {};
+  class SkipCanonicalization:  public BitField<bool, 1, 2> {};

[Jakob Kummerow, 2012/06/05 09:05:40]

not that it matters, but why use two bits to store this bool?
(the syntax is Bitfield<type, shift, size>)

[Vyacheslav Egorov (Google), 2012/06/05 09:13:24]

why not 

bool is_dehoisted_ : 1;
bool skip_canonicalization_ : 1;

?

+
   uint32_t index_offset_;
-  bool is_dehoisted_;
+  uint32_t bit_field_;
 };