1// Copyright 2011 the V8 project authors. All rights reserved.
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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
35namespace v8 {
36namespace internal {
37
38class LCodeGen;
39class LGapResolver;
40
41class 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