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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.
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     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
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     26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 
     28 #ifndef V8_IA32_LITHIUM_GAP_RESOLVER_IA32_H_
     29 #define V8_IA32_LITHIUM_GAP_RESOLVER_IA32_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   // Emit any code necessary at the end of a gap move.
     57   void Finish();
     58 
     59   // Add or delete a move from the move graph without emitting any code.
     60   // Used to build up the graph and remove trivial moves.
     61   void AddMove(LMoveOperands move);
     62   void RemoveMove(int index);
     63 
     64   // Report the count of uses of operand as a source in a not-yet-performed
     65   // move.  Used to rebuild use counts.
     66   int CountSourceUses(LOperand* operand);
     67 
     68   // Emit a move and remove it from the move graph.
     69   void EmitMove(int index);
     70 
     71   // Execute a move by emitting a swap of two operands.  The move from
     72   // source to destination is removed from the move graph.
     73   void EmitSwap(int index);
     74 
     75   // Ensure that the given operand is not spilled.
     76   void EnsureRestored(LOperand* operand);
     77 
     78   // Return a register that can be used as a temp register, spilling
     79   // something if necessary.
     80   Register EnsureTempRegister();
     81 
     82   // Return a known free register different from the given one (which could
     83   // be no_reg---returning any free register), or no_reg if there is no such
     84   // register.
     85   Register GetFreeRegisterNot(Register reg);
     86 
     87   // Verify that the state is the initial one, ready to resolve a single
     88   // parallel move.
     89   bool HasBeenReset();
     90 
     91   // Verify the move list before performing moves.
     92   void Verify();
     93 
     94   LCodeGen* cgen_;
     95 
     96   // List of moves not yet resolved.
     97   ZoneList<LMoveOperands> moves_;
     98 
     99   // Source and destination use counts for the general purpose registers.
    100   int source_uses_[Register::kNumAllocatableRegisters];
    101   int destination_uses_[Register::kNumAllocatableRegisters];
    102 
    103   // If we had to spill on demand, the currently spilled register's
    104   // allocation index.
    105   int spilled_register_;
    106 };
    107 
    108 } }  // namespace v8::internal
    109 
    110 #endif  // V8_IA32_LITHIUM_GAP_RESOLVER_IA32_H_
    111