Introduce a hydrogen value for contexts, support context slot assignment.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index ff8170012e6b025e0a0d7b6ded6652e6075beb6c..86a85c5bfafbfd054ac0e07ee6801057296d2dd8 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -97,6 +97,7 @@ class LChunkBuilder;
   V(CompareJSObjectEq)                         \
   V(CompareMap)                                \
   V(Constant)                                  \
+  V(Context)                                   \
   V(DeleteProperty)                            \
   V(Deoptimize)                                \
   V(Div)                                       \
@@ -128,6 +129,7 @@ class LChunkBuilder;
   V(Mul)                                       \
   V(ObjectLiteral)                             \
   V(OsrEntry)                                  \
+  V(OuterContext)                              \
   V(Parameter)                                 \
   V(Power)                                     \
   V(PushArgument)                              \
@@ -138,6 +140,7 @@ class LChunkBuilder;
   V(Shr)                                       \
   V(Simulate)                                  \
   V(StackCheck)                                \
+  V(StoreContextSlot)                          \
   V(StoreGlobal)                               \
   V(StoreKeyedFastElement)                     \
   V(StoreKeyedGeneric)                         \
@@ -162,6 +165,7 @@ class LChunkBuilder;
   V(GlobalVars)                                \
   V(Maps)                                      \
   V(ArrayLengths)                              \
+  V(ContextSlots)                              \
   V(OsrEntries)
 
 #define DECLARE_INSTRUCTION(type)                   \
@@ -1046,12 +1050,39 @@ class HPushArgument: public HUnaryOperation {
 };
 
 
-class HGlobalObject: public HInstruction {
+class HContext: public HInstruction {
  public:
-  HGlobalObject() {
+  HContext() {
+    set_representation(Representation::Tagged());
+    SetFlag(kUseGVN);
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(Context, "context");
+
+ protected:
+  virtual bool DataEquals(HValue* other) const { return true; }
+};
+
+
+class HOuterContext: public HUnaryOperation {
+ public:
+  explicit HOuterContext(HValue* inner) : HUnaryOperation(inner) {
+    set_representation(Representation::Tagged());
+    SetFlag(kUseGVN);
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(OuterContext, "outer_context");
+
+ protected:
+  virtual bool DataEquals(HValue* other) const { return true; }
+};
+
+
+class HGlobalObject: public HUnaryOperation {
+ public:
+  explicit HGlobalObject(HValue* context) : HUnaryOperation(context) {
     set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
-    SetFlag(kDependsOnCalls);
   }
 
   DECLARE_CONCRETE_INSTRUCTION(GlobalObject, "global_object")
@@ -1061,12 +1092,12 @@ class HGlobalObject: public HInstruction {
 };
 
 
-class HGlobalReceiver: public HInstruction {
+class HGlobalReceiver: public HUnaryOperation {
  public:
-  HGlobalReceiver() {
+  explicit HGlobalReceiver(HValue* global_object)
+      : HUnaryOperation(global_object) {
     set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
-    SetFlag(kDependsOnCalls);
   }
 
   DECLARE_CONCRETE_INSTRUCTION(GlobalReceiver, "global_receiver")
@@ -2600,35 +2631,56 @@ class HStoreGlobal: public HUnaryOperation {
 };
 
 
-class HLoadContextSlot: public HInstruction {
+class HLoadContextSlot: public HUnaryOperation {
  public:
-  HLoadContextSlot(int context_chain_length , int slot_index)
-      : context_chain_length_(context_chain_length), slot_index_(slot_index) {
+  HLoadContextSlot(HValue* context , int slot_index)
+      : HUnaryOperation(context), slot_index_(slot_index) {
     set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
-    SetFlag(kDependsOnCalls);
+    SetFlag(kDependsOnContextSlots);
   }
 
-  int context_chain_length() const { return context_chain_length_; }
   int slot_index() const { return slot_index_; }
 
-  virtual void PrintDataTo(StringStream* stream) const;
-
-  virtual intptr_t Hashcode() const {
-    return context_chain_length() * 29 + slot_index();
+  virtual Representation RequiredInputRepresentation(int index) const {

[fschneider, 2011/01/28 11:54:50]

I think we are not consistent with when to override this function. Until now we
left the default implementation (Representation::None) for cases where we don't
ever expect a conversion of the inputs. 

[Kevin Millikin (Chromium), 2011/02/03 08:37:23]

Do you think that's a good idea?  It seems like another unsafe default.

+    return Representation::Tagged();
   }
 
+  virtual void PrintDataTo(StringStream* stream) const;
+
   DECLARE_CONCRETE_INSTRUCTION(LoadContextSlot, "load_context_slot")
 
  protected:
   virtual bool DataEquals(HValue* other) const {
     HLoadContextSlot* b = HLoadContextSlot::cast(other);
-    return (context_chain_length() == b->context_chain_length())
-        && (slot_index() == b->slot_index());
+    return (slot_index() == b->slot_index());
   }
 
  private:
-  int context_chain_length_;
+  int slot_index_;
+};
+
+
+class HStoreContextSlot: public HBinaryOperation {
+ public:
+  HStoreContextSlot(HValue* context, int slot_index, HValue* value)
+      : HBinaryOperation(context, value), slot_index_(slot_index) {
+    SetFlag(kChangesContextSlots);
+  }
+
+  HValue* context() const { return OperandAt(0); }
+  HValue* value() const { return OperandAt(1); }
+  int slot_index() const { return slot_index_; }
+
+  virtual Representation RequiredInputRepresentation(int index) const {
+    return Representation::Tagged();
+  }
+
+  virtual void PrintDataTo(StringStream* stream) const;
+
+  DECLARE_CONCRETE_INSTRUCTION(StoreContextSlot, "store_context_slot")
+
+ private:
   int slot_index_;
 };
 
@@ -2818,7 +2870,7 @@ class HStoreNamedField: public HStoreNamed {
   DECLARE_CONCRETE_INSTRUCTION(StoreNamedField, "store_named_field")
 
   virtual Representation RequiredInputRepresentation(int index) const {
-    return  Representation::Tagged();
+    return Representation::Tagged();
   }
   virtual void PrintDataTo(StringStream* stream) const;