On Ia32 optimistically assume that results from int32 and uint32 array loads fit into Smi. Only if …

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 502 matching lines @@
   friend class MathSqrtInstr;
   friend class CheckClassInstr;
   friend class CheckSmiInstr;
   friend class CheckArrayBoundInstr;
   friend class CheckEitherNonSmiInstr;
   friend class LICM;
   friend class DoubleToSmiInstr;
   friend class DoubleToDoubleInstr;
   friend class InvokeMathCFunctionInstr;
   friend class FlowGraphOptimizer;
+  friend class LoadIndexedInstr;
 
   intptr_t deopt_id_;
   intptr_t lifetime_position_;  // Position used by register allocator.
   Instruction* previous_;
   Instruction* next_;
   Environment* env_;
   intptr_t expr_id_;
 
   DISALLOW_COPY_AND_ASSIGN(Instruction);
 };
@@ skipping 2155 matching lines @@
 
  private:
   const Field& field_;
 
   DISALLOW_COPY_AND_ASSIGN(StoreStaticFieldInstr);
 };
 
 
 class LoadIndexedInstr : public TemplateDefinition<2> {
  public:
-  LoadIndexedInstr(Value* array, Value* index, intptr_t class_id)
+  LoadIndexedInstr(Value* array,
+                   Value* index,
+                   intptr_t class_id,
+                   intptr_t deopt_id)
       : class_id_(class_id) {
     ASSERT(array != NULL);
     ASSERT(index != NULL);
     inputs_[0] = array;
     inputs_[1] = index;
+    deopt_id_ = deopt_id;
   }
 
   DECLARE_INSTRUCTION(LoadIndexed)
   virtual RawAbstractType* CompileType() const;
 
   Value* array() const { return inputs_[0]; }
   Value* index() const { return inputs_[1]; }
   intptr_t class_id() const { return class_id_; }
 
-  virtual bool CanDeoptimize() const { return false; }
+  virtual bool CanDeoptimize() const {
+    return deopt_id_ != Isolate::kNoDeoptId;
+  }
 
   virtual bool HasSideEffect() const { return false; }
 
   virtual intptr_t ResultCid() const;
 
   virtual Representation representation() const;
 
   virtual bool AttributesEqual(Instruction* other) const;
 
   virtual bool AffectedBySideEffect() const { return true; }
@@ skipping 1734 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_