Improve GVN dependency tracking by adding parameters to certain flags.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 6c516f2497e01ae6e63a9cca6f241d55d2929172..6a7623ff401f4bc21b2de84086d36ad8f6203a92 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -161,16 +161,18 @@ class LChunkBuilder;
   V(UnknownOSRValue)                           \
   V(ValueOf)
 
+// The list of GVN flags. To improve memory usage it should start with
+// the flags that allow parameters.
 #define GVN_FLAG_LIST(V)                       \
-  V(Calls)                                     \
   V(InobjectFields)                            \
   V(BackingStoreFields)                        \
+  V(GlobalVars)                                \
+  V(ContextSlots)                              \
+  V(Calls)                                     \
   V(ArrayElements)                             \
   V(PixelArrayElements)                        \
-  V(GlobalVars)                                \
   V(Maps)                                      \
   V(ArrayLengths)                              \
-  V(ContextSlots)                              \
   V(OsrEntries)
 
 #define DECLARE_INSTRUCTION(type)                   \
@@ -408,11 +410,13 @@ class HValue: public ZoneObject {
   #undef DECLARE_DO
     kFlexibleRepresentation,
     kUseGVN,
+    kHasGVNParameter,
     kCanOverflow,
     kBailoutOnMinusZero,
     kCanBeDivByZero,
     kIsArguments,
     kTruncatingToInt32,
+    kFirstNonGVNFlag = kFlexibleRepresentation,
     kLastFlag = kTruncatingToInt32
   };
 
@@ -436,6 +440,9 @@ class HValue: public ZoneObject {
   static int ConvertChangesToDependsFlags(int flags) {
     return flags << kChangesToDependsFlagsLeftShift;
   }
+  static int ConvertDependsToChangesFlags(int flags) {
+    return flags >> kChangesToDependsFlagsLeftShift;
+  }
 
   static HValue* cast(HValue* value) { return value; }
 
@@ -549,6 +556,11 @@ class HValue: public ZoneObject {
   bool Equals(HValue* other);
   virtual intptr_t Hashcode();
 
+  virtual intptr_t GetGVNParameter() {
+    UNREACHABLE();
+    return 0;
+  }
+
   // Printing support.
   virtual void PrintTo(StringStream* stream) = 0;
   void PrintNameTo(StringStream* stream);
@@ -2781,6 +2793,11 @@ class HLoadGlobal: public HTemplateInstruction<0> {
     set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
     SetFlag(kDependsOnGlobalVars);
+    SetFlag(kHasGVNParameter);
+  }
+
+  virtual intptr_t GetGVNParameter() {
+    return reinterpret_cast<intptr_t>(*cell_);
   }
 
   Handle<JSGlobalPropertyCell>  cell() const { return cell_; }
@@ -2820,6 +2837,11 @@ class HStoreGlobal: public HUnaryOperation {
         cell_(cell),
         check_hole_value_(check_hole_value) {
     SetFlag(kChangesGlobalVars);
+    SetFlag(kHasGVNParameter);
+  }
+
+  virtual intptr_t GetGVNParameter() {
+    return reinterpret_cast<intptr_t>(*cell_);
   }
 
   Handle<JSGlobalPropertyCell> cell() const { return cell_; }
@@ -2845,8 +2867,11 @@ class HLoadContextSlot: public HUnaryOperation {
     set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
     SetFlag(kDependsOnContextSlots);
+    SetFlag(kHasGVNParameter);
   }
 
+  virtual intptr_t GetGVNParameter() { return slot_index_; }
+
   int slot_index() const { return slot_index_; }
 
   virtual Representation RequiredInputRepresentation(int index) const {
@@ -2879,8 +2904,11 @@ class HStoreContextSlot: public HBinaryOperation {
   HStoreContextSlot(HValue* context, int slot_index, HValue* value)
       : HBinaryOperation(context, value), slot_index_(slot_index) {
     SetFlag(kChangesContextSlots);
+    SetFlag(kHasGVNParameter);
   }
 
+  virtual intptr_t GetGVNParameter() { return slot_index_; }
+
   HValue* context() { return OperandAt(0); }
   HValue* value() { return OperandAt(1); }
   int slot_index() const { return slot_index_; }
@@ -2915,6 +2943,11 @@ class HLoadNamedField: public HUnaryOperation {
     } else {
       SetFlag(kDependsOnBackingStoreFields);
     }
+    SetFlag(kHasGVNParameter);
+  }
+
+  virtual intptr_t GetGVNParameter() {
+    return (offset_ << 1) || (is_in_object_ ? 1 : 0);

[fschneider, 2011/03/16 15:43:28]

Shouldn't be this bitwise-or "|"?

   }
 
   HValue* object() { return OperandAt(0); }
@@ -3083,6 +3116,11 @@ class HStoreNamedField: public HBinaryOperation {
     } else {
       SetFlag(kChangesBackingStoreFields);
     }
+    SetFlag(kHasGVNParameter);
+  }
+
+  virtual intptr_t GetGVNParameter() {
+    return (offset_ << 1) || (is_in_object_ ? 1 : 0);

[fschneider, 2011/03/16 15:43:28]

-> use "|" here as well.

   }
 
   DECLARE_CONCRETE_INSTRUCTION(StoreNamedField, "store_named_field")
@@ -3099,7 +3137,15 @@ class HStoreNamedField: public HBinaryOperation {
   bool is_in_object() const { return is_in_object_; }
   int offset() const { return offset_; }
   Handle<Map> transition() const { return transition_; }
-  void set_transition(Handle<Map> map) { transition_ = map; }
+  void SetTransition(Handle<Map> map) {
+    transition_ = map;
+    // TODO(fschneider): Record the new map type of the object in the IR to
+    // enable elimination of redundant checks after the transition store.
+    SetFlag(kChangesMaps);
+    // TODO(vitalyr): GVN parameter is only supported for instructions
+    // that have a single GVN flag.
+    ClearFlag(kHasGVNParameter);
+  }
 
   bool NeedsWriteBarrier() {
     return StoringValueNeedsWriteBarrier(value());