VM: Avoid repeated deoptimizations from hoisted array bounds checks.

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 7918 matching lines @@
  private:
   intptr_t cid_;
 
   DISALLOW_COPY_AND_ASSIGN(CheckClassIdInstr);
 };
 
 
 class CheckArrayBoundInstr : public TemplateInstruction<2> {
  public:
   CheckArrayBoundInstr(Value* length, Value* index, intptr_t deopt_id)
-      : generalized_(false) {
+      : generalized_(false), licm_hoisted_(false) {
     SetInputAt(kLengthPos, length);
     SetInputAt(kIndexPos, index);
     // Override generated deopt-id.
     deopt_id_ = deopt_id;
   }
 
   Value* length() const { return inputs_[kLengthPos]; }
   Value* index() const { return inputs_[kIndexPos]; }
 
   DECLARE_INSTRUCTION(CheckArrayBound)
@@ skipping 15 matching lines @@
 
   static bool IsFixedLengthArrayType(intptr_t class_id);
 
   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; }
 
   virtual bool MayThrow() const { return false; }
 
+  void set_licm_hoisted(bool value) { licm_hoisted_ = value; }
+
   // Give a name to the location/input indices.
   enum {
     kLengthPos = 0,
     kIndexPos = 1
   };
 
  private:
   bool generalized_;
+  bool licm_hoisted_;
 
   DISALLOW_COPY_AND_ASSIGN(CheckArrayBoundInstr);
 };
 
 
 class BoxIntNInstr : public TemplateDefinition<1> {
  public:
   BoxIntNInstr(Representation representation, Value* value)
       : from_representation_(representation) {
     SetInputAt(0, value);
@@ skipping 453 matching lines @@
       Isolate* isolate, bool opt) const {                                     \
     UNIMPLEMENTED();                                                          \
     return NULL;                                                              \
   }                                                                           \
   void Name::EmitNativeCode(FlowGraphCompiler* compiler) { UNIMPLEMENTED(); }
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_