Fix crash during parallel moves.

runtime/vm/intermediate_language.h

 // Copyright (c) 2012, 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 2361 matching lines @@
   Value* left_;
   Value* right_;
   Token::Kind kind_;
   TargetEntryInstr* true_successor_;
   TargetEntryInstr* false_successor_;
 
   DISALLOW_COPY_AND_ASSIGN(BranchInstr);
 };
 
 
-// This class is often passed by value. Add additional fields with caution.
-class MoveOperands : public ValueObject {
+class MoveOperands : public ZoneAllocated {
  public:
   MoveOperands(Location dest, Location src) : dest_(dest), src_(src) { }
 
   Location src() const { return src_; }
   Location dest() const { return dest_; }
 
   Location* src_slot() { return &src_; }
   Location* dest_slot() { return &dest_; }
 
-  void set_src(Location src) { src_ = src; }
+  void set_src(const Location& value) { src_ = value; }
+  void set_dest(const Location& value) { dest_ = value; }
 
   // The parallel move resolver marks moves as "in-progress" by clearing the
   // destination (but not the source).
   Location MarkPending() {
     ASSERT(!IsPending());
     Location dest = dest_;
     dest_ = Location::NoLocation();
     return dest;
   }
 
@@ skipping 21 matching lines @@
   // We clear both operands to indicate move that's been eliminated.
   void Eliminate() { src_ = dest_ = Location::NoLocation(); }
   bool IsEliminated() const {
     ASSERT(!src_.IsInvalid() || dest_.IsInvalid());
     return src_.IsInvalid();
   }
 
  private:
   Location dest_;
   Location src_;
+
+  DISALLOW_COPY_AND_ASSIGN(MoveOperands);
 };
 
 
 class ParallelMoveInstr : public Instruction {
  public:
   explicit ParallelMoveInstr() : moves_(4) {
   }
 
   DECLARE_INSTRUCTION(ParallelMove)
 
   void AddMove(Location dest, Location src) {
-    moves_.Add(MoveOperands(dest, src));
+    moves_.Add(new MoveOperands(dest, src));
   }
 
-  const GrowableArray<MoveOperands>& moves() { return moves_; }
+  MoveOperands* MoveOperandsAt(intptr_t index) const { return moves_[index]; }
+
+  void SetSrcSlotAt(intptr_t index, const Location& loc);
+  void SetDestSlotAt(intptr_t index, const Location& loc);
+
+  intptr_t NumMoves() const { return moves_.length(); }
 
  private:
-  GrowableArray<MoveOperands> moves_;
+  GrowableArray<MoveOperands*> moves_;   // Elements cannot be null.
 
   DISALLOW_COPY_AND_ASSIGN(ParallelMoveInstr);
 };
 
 #undef DECLARE_INSTRUCTION
 
 
 class Environment : public ZoneAllocated {
  public:
   // Construct an environment by copying from an array of values.
@@ skipping 56 matching lines @@
   const GrowableArray<BlockEntryInstr*>& block_order_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_