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 
12 namespace v8 {
13 namespace internal {
14 
15 class LCodeGen;
16 class LGapResolver;
17 
18 class 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