Ignore redundant parallel moves when checking if a block is empty.

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 1060 matching lines @@
   MoveOperands* AddMove(Location dest, Location src) {
     MoveOperands* move = new MoveOperands(dest, src);
     moves_.Add(move);
     return move;
   }
 
   MoveOperands* MoveOperandsAt(intptr_t index) const { return moves_[index]; }
 
   intptr_t NumMoves() const { return moves_.length(); }
 
+  bool IsRedundant() const;
+
   virtual void PrintTo(BufferFormatter* f) const;
 
   virtual bool MayThrow() const { return false; }
 
  private:
   GrowableArray<MoveOperands*> moves_;   // Elements cannot be null.
 
   DISALLOW_COPY_AND_ASSIGN(ParallelMoveInstr);
 };
 
@@ skipping 40 matching lines @@
   void set_last_instruction(Instruction* instr) { last_instruction_ = instr; }
 
   ParallelMoveInstr* parallel_move() const {
     return parallel_move_;
   }
 
   bool HasParallelMove() const {
     return parallel_move_ != NULL;
   }
 
+  bool HasNonRedundantParallelMove() const {
+    return HasParallelMove() && !parallel_move()->IsRedundant();
+  }
+
   ParallelMoveInstr* GetParallelMove() {
     if (parallel_move_ == NULL) {
       parallel_move_ = new ParallelMoveInstr();
     }
     return parallel_move_;
   }
 
   // Discover basic-block structure of the current block.  Must be called
   // on all graph blocks in preorder to yield valid results.  As a side effect,
   // the block entry instructions in the graph are assigned preorder numbers.
@@ skipping 1009 matching lines @@
   virtual EffectSet Effects() const { return EffectSet::None(); }
 
   ParallelMoveInstr* parallel_move() const {
     return parallel_move_;
   }
 
   bool HasParallelMove() const {
     return parallel_move_ != NULL;
   }
 
+  bool HasNonRedundantParallelMove() const {
+    return HasParallelMove() && !parallel_move()->IsRedundant();
+  }
+
   ParallelMoveInstr* GetParallelMove() {
     if (parallel_move_ == NULL) {
       parallel_move_ = new ParallelMoveInstr();
     }
     return parallel_move_;
   }
 
   virtual void PrintTo(BufferFormatter* f) const;
 
   virtual bool MayThrow() const { return false; }
@@ skipping 6260 matching lines @@
       Isolate* isolate, bool opt) const {                                     \
     UNIMPLEMENTED();                                                          \
     return NULL;                                                              \
   }                                                                           \
   void Name::EmitNativeCode(FlowGraphCompiler* compiler) { UNIMPLEMENTED(); }
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_