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      1 // Copyright 2011 the V8 project authors. All rights reserved.
      2 // Redistribution and use in source and binary forms, with or without
      3 // modification, are permitted provided that the following conditions are
      4 // met:
      5 //
      6 //     * Redistributions of source code must retain the above copyright
      7 //       notice, this list of conditions and the following disclaimer.
      8 //     * Redistributions in binary form must reproduce the above
      9 //       copyright notice, this list of conditions and the following
     10 //       disclaimer in the documentation and/or other materials provided
     11 //       with the distribution.
     12 //     * Neither the name of Google Inc. nor the names of its
     13 //       contributors may be used to endorse or promote products derived
     14 //       from this software without specific prior written permission.
     15 //
     16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 
     28 #ifndef V8_ARM_LITHIUM_GAP_RESOLVER_ARM_H_
     29 #define V8_ARM_LITHIUM_GAP_RESOLVER_ARM_H_
     30 
     31 #include "v8.h"
     32 
     33 #include "lithium.h"
     34 
     35 namespace v8 {
     36 namespace internal {
     37 
     38 class LCodeGen;
     39 class LGapResolver;
     40 
     41 class LGapResolver BASE_EMBEDDED {
     42  public:
     43   explicit LGapResolver(LCodeGen* owner);
     44 
     45   // Resolve a set of parallel moves, emitting assembler instructions.
     46   void Resolve(LParallelMove* parallel_move);
     47 
     48  private:
     49   // Build the initial list of moves.
     50   void BuildInitialMoveList(LParallelMove* parallel_move);
     51 
     52   // Perform the move at the moves_ index in question (possibly requiring
     53   // other moves to satisfy dependencies).
     54   void PerformMove(int index);
     55 
     56   // If a cycle is found in the series of moves, save the blocking value to
     57   // a scratch register.  The cycle must be found by hitting the root of the
     58   // depth-first search.
     59   void BreakCycle(int index);
     60 
     61   // After a cycle has been resolved, restore the value from the scratch
     62   // register to its proper destination.
     63   void RestoreValue();
     64 
     65   // Emit a move and remove it from the move graph.
     66   void EmitMove(int index);
     67 
     68   // Verify the move list before performing moves.
     69   void Verify();
     70 
     71   LCodeGen* cgen_;
     72 
     73   // List of moves not yet resolved.
     74   ZoneList<LMoveOperands> moves_;
     75 
     76   int root_index_;
     77   bool in_cycle_;
     78   LOperand* saved_destination_;
     79 };
     80 
     81 } }  // namespace v8::internal
     82 
     83 #endif  // V8_ARM_LITHIUM_GAP_RESOLVER_ARM_H_
     84