VM: Constant fold more loads from constants in the optimizer.

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 RUNTIME_VM_INTERMEDIATE_LANGUAGE_H_
 #define RUNTIME_VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 4467 matching lines @@
 
   DECLARE_INSTRUCTION(LoadField)
   virtual CompileType ComputeType() const;
 
   virtual bool ComputeCanDeoptimize() const { return false; }
 
   virtual void InferRange(RangeAnalysis* analysis, Range* range);
 
   bool IsImmutableLengthLoad() const;
 
+  // Try evaluating this load against the given constant value of
+  // the instance. Returns true if evaluation succeeded and
+  // puts result into result.
+  // Note: we only evaluate loads when we can ensure that
+  // instance has the field.
+  bool Evaluate(const Object& instance_value, Object* result);
+
   virtual Definition* Canonicalize(FlowGraph* flow_graph);
 
   static MethodRecognizer::Kind RecognizedKindFromArrayCid(intptr_t cid);
 
   static bool IsFixedLengthArrayCid(intptr_t cid);
 
   virtual bool AllowsCSE() const { return immutable_; }
   virtual EffectSet Effects() const { return EffectSet::None(); }
   virtual EffectSet Dependencies() const;
   virtual bool AttributesEqual(Instruction* other) const;
@@ skipping 3672 matching lines @@
   LocationSummary* Name::MakeLocationSummary(Zone* zone, bool opt) const {     \
     UNIMPLEMENTED();                                                           \
     return NULL;                                                               \
   }                                                                            \
   void Name::EmitNativeCode(FlowGraphCompiler* compiler) { UNIMPLEMENTED(); }
 
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_INTERMEDIATE_LANGUAGE_H_