Improve load forwarding:

runtime/vm/intermediate_language.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 3407 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(InstanceOfInstr);
 };
 
 
 class AllocateObjectInstr : public TemplateDefinition<0> {
  public:
   AllocateObjectInstr(ConstructorCallNode* node,
                       ZoneGrowableArray<PushArgumentInstr*>* arguments)
       : ast_node_(*node),
         arguments_(arguments),
-        cid_(Class::Handle(node->constructor().Owner()).id()) {
+        cid_(Class::Handle(node->constructor().Owner()).id()),
+        identity_(kUnknown) {
     // Either no arguments or one type-argument and one instantiator.
     ASSERT(arguments->is_empty() || (arguments->length() == 2));
   }
 
   DECLARE_INSTRUCTION(AllocateObject)
   virtual CompileType ComputeType() const;
 
   virtual intptr_t ArgumentCount() const { return arguments_->length(); }
   virtual PushArgumentInstr* PushArgumentAt(intptr_t index) const {
     return (*arguments_)[index];
   }
 
   const Function& constructor() const { return ast_node_.constructor(); }
   intptr_t token_pos() const { return ast_node_.token_pos(); }
 
   virtual void PrintOperandsTo(BufferFormatter* f) const;
 
   virtual bool CanDeoptimize() const { return false; }
 
   virtual EffectSet Effects() const { return EffectSet::None(); }
 
+  // If the result of the allocation is not stored into any field, passed
+  // as an argument or used in a phi then it can't alias with any other
+  // SSA value.
+  enum Identity {
+    kUnknown,
+    kAliased,
+    kNotAliased
+  };
+
+  Identity identity() const { return identity_; }
+  void set_identity(Identity identity) { identity_ = identity; }
+
  private:
   const ConstructorCallNode& ast_node_;
   ZoneGrowableArray<PushArgumentInstr*>* const arguments_;
   const intptr_t cid_;
+  Identity identity_;
 
   DISALLOW_COPY_AND_ASSIGN(AllocateObjectInstr);
 };
 
 
 class AllocateObjectWithBoundsCheckInstr : public TemplateDefinition<2> {
  public:
   AllocateObjectWithBoundsCheckInstr(ConstructorCallNode* node,
                                      Value* type_arguments,
                                      Value* instantiator)
@@ skipping 121 matching lines @@
 
  private:
   intptr_t offset_;
 
   DISALLOW_COPY_AND_ASSIGN(LoadUntaggedInstr);
 };
 
 
 class LoadFieldInstr : public TemplateDefinition<1> {
  public:
-  LoadFieldInstr(Value* value,
+  LoadFieldInstr(Value* instance,
                  intptr_t offset_in_bytes,
                  const AbstractType& type,
                  bool immutable = false)
       : offset_in_bytes_(offset_in_bytes),
         type_(type),
         result_cid_(kDynamicCid),
         immutable_(immutable),
         recognized_kind_(MethodRecognizer::kUnknown),
         field_name_(NULL),
         field_(NULL) {
     ASSERT(type.IsZoneHandle());  // May be null if field is not an instance.
-    SetInputAt(0, value);
+    SetInputAt(0, instance);
   }
 
-  Value* value() const { return inputs_[0]; }
+  Value* instance() const { return inputs_[0]; }
   intptr_t offset_in_bytes() const { return offset_in_bytes_; }
   const AbstractType& type() const { return type_; }
   void set_result_cid(intptr_t value) { result_cid_ = value; }
   intptr_t result_cid() const { return result_cid_; }
 
   void set_field_name(const char* name) { field_name_ = name; }
   const char* field_name() const { return field_name_; }
 
-  Field* field() const { return field_; }
-  void set_field(Field* field) { field_ = field; }
+  const Field* field() const { return field_; }
+  void set_field(const Field* field) { field_ = field; }
 
   void set_recognized_kind(MethodRecognizer::Kind kind) {
     recognized_kind_ = kind;
   }
 
   MethodRecognizer::Kind recognized_kind() const {
     return recognized_kind_;
   }
 
   DECLARE_INSTRUCTION(LoadField)
@@ skipping 20 matching lines @@
 
  private:
   const intptr_t offset_in_bytes_;
   const AbstractType& type_;
   intptr_t result_cid_;
   const bool immutable_;
 
   MethodRecognizer::Kind recognized_kind_;
 
   const char* field_name_;
-  Field* field_;
+  const Field* field_;
 
   DISALLOW_COPY_AND_ASSIGN(LoadFieldInstr);
 };
 
 
 class StoreVMFieldInstr : public TemplateDefinition<2> {
  public:
   StoreVMFieldInstr(Value* dest,
                     intptr_t offset_in_bytes,
                     Value* value,
@@ skipping 277 matching lines @@
   virtual Representation RequiredInputRepresentation(intptr_t idx) const {
     ASSERT(idx == 0);
     return kUnboxedDouble;
   }
 
   virtual bool AllowsCSE() const { return true; }
   virtual EffectSet Effects() const { return EffectSet::None(); }
   virtual EffectSet Dependencies() const { return EffectSet::None(); }
   virtual bool AttributesEqual(Instruction* other) const { return true; }
 
+  Definition* Canonicalize(FlowGraphOptimizer* optimizer);
+
  private:
   DISALLOW_COPY_AND_ASSIGN(BoxDoubleInstr);
 };
 
 
 class BoxFloat32x4Instr : public TemplateDefinition<1> {
  public:
   explicit BoxFloat32x4Instr(Value* value) {
     SetInputAt(0, value);
   }
@@ skipping 95 matching lines @@
   }
 
   DECLARE_INSTRUCTION(UnboxDouble)
   virtual CompileType ComputeType() const;
 
   virtual bool AllowsCSE() const { return true; }
   virtual EffectSet Effects() const { return EffectSet::None(); }
   virtual EffectSet Dependencies() const { return EffectSet::None(); }
   virtual bool AttributesEqual(Instruction* other) const { return true; }
 
+  Definition* Canonicalize(FlowGraphOptimizer* optimizer);
+
  private:
   DISALLOW_COPY_AND_ASSIGN(UnboxDoubleInstr);
 };
 
 
 class UnboxFloat32x4Instr : public TemplateDefinition<1> {
  public:
   UnboxFloat32x4Instr(Value* value, intptr_t deopt_id) {
     SetInputAt(0, value);
     deopt_id_ = deopt_id;
@@ skipping 1620 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_