1// Copyright 2011 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef V8_IA32_LITHIUM_GAP_RESOLVER_IA32_H_
6#define V8_IA32_LITHIUM_GAP_RESOLVER_IA32_H_
7
8#include "src/v8.h"
9
10#include "src/lithium.h"
11
12namespace v8 {
13namespace internal {
14
15class LCodeGen;
16class LGapResolver;
17
18class LGapResolver FINAL BASE_EMBEDDED {
19 public:
20  explicit LGapResolver(LCodeGen* owner);
21
22  // Resolve a set of parallel moves, emitting assembler instructions.
23  void Resolve(LParallelMove* parallel_move);
24
25 private:
26  // Build the initial list of moves.
27  void BuildInitialMoveList(LParallelMove* parallel_move);
28
29  // Perform the move at the moves_ index in question (possibly requiring
30  // other moves to satisfy dependencies).
31  void PerformMove(int index);
32
33  // Emit any code necessary at the end of a gap move.
34  void Finish();
35
36  // Add or delete a move from the move graph without emitting any code.
37  // Used to build up the graph and remove trivial moves.
38  void AddMove(LMoveOperands move);
39  void RemoveMove(int index);
40
41  // Report the count of uses of operand as a source in a not-yet-performed
42  // move.  Used to rebuild use counts.
43  int CountSourceUses(LOperand* operand);
44
45  // Emit a move and remove it from the move graph.
46  void EmitMove(int index);
47
48  // Execute a move by emitting a swap of two operands.  The move from
49  // source to destination is removed from the move graph.
50  void EmitSwap(int index);
51
52  // Ensure that the given operand is not spilled.
53  void EnsureRestored(LOperand* operand);
54
55  // Return a register that can be used as a temp register, spilling
56  // something if necessary.
57  Register EnsureTempRegister();
58
59  // Return a known free register different from the given one (which could
60  // be no_reg---returning any free register), or no_reg if there is no such
61  // register.
62  Register GetFreeRegisterNot(Register reg);
63
64  // Verify that the state is the initial one, ready to resolve a single
65  // parallel move.
66  bool HasBeenReset();
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  // Source and destination use counts for the general purpose registers.
77  int source_uses_[Register::kMaxNumAllocatableRegisters];
78  int destination_uses_[Register::kMaxNumAllocatableRegisters];
79
80  // If we had to spill on demand, the currently spilled register's
81  // allocation index.
82  int spilled_register_;
83};
84
85} }  // namespace v8::internal
86
87#endif  // V8_IA32_LITHIUM_GAP_RESOLVER_IA32_H_
88