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_CRANKSHAFT_IA32_LITHIUM_GAP_RESOLVER_IA32_H_
6 #define V8_CRANKSHAFT_IA32_LITHIUM_GAP_RESOLVER_IA32_H_
7 
8 #include "src/crankshaft/lithium.h"
9 
10 namespace v8 {
11 namespace internal {
12 
13 class LCodeGen;
14 class LGapResolver;
15 
16 class LGapResolver final BASE_EMBEDDED {
17  public:
18   explicit LGapResolver(LCodeGen* owner);
19 
20   // Resolve a set of parallel moves, emitting assembler instructions.
21   void Resolve(LParallelMove* parallel_move);
22 
23  private:
24   // Build the initial list of moves.
25   void BuildInitialMoveList(LParallelMove* parallel_move);
26 
27   // Perform the move at the moves_ index in question (possibly requiring
28   // other moves to satisfy dependencies).
29   void PerformMove(int index);
30 
31   // Emit any code necessary at the end of a gap move.
32   void Finish();
33 
34   // Add or delete a move from the move graph without emitting any code.
35   // Used to build up the graph and remove trivial moves.
36   void AddMove(LMoveOperands move);
37   void RemoveMove(int index);
38 
39   // Report the count of uses of operand as a source in a not-yet-performed
40   // move.  Used to rebuild use counts.
41   int CountSourceUses(LOperand* operand);
42 
43   // Emit a move and remove it from the move graph.
44   void EmitMove(int index);
45 
46   // Execute a move by emitting a swap of two operands.  The move from
47   // source to destination is removed from the move graph.
48   void EmitSwap(int index);
49 
50   // Ensure that the given operand is not spilled.
51   void EnsureRestored(LOperand* operand);
52 
53   // Return a register that can be used as a temp register, spilling
54   // something if necessary.
55   Register EnsureTempRegister();
56 
57   // Return a known free register different from the given one (which could
58   // be no_reg---returning any free register), or no_reg if there is no such
59   // register.
60   Register GetFreeRegisterNot(Register reg);
61 
62   // Verify that the state is the initial one, ready to resolve a single
63   // parallel move.
64   bool HasBeenReset();
65 
66   // Verify the move list before performing moves.
67   void Verify();
68 
69   LCodeGen* cgen_;
70 
71   // List of moves not yet resolved.
72   ZoneList<LMoveOperands> moves_;
73 
74   // Source and destination use counts for the general purpose registers.
75   int source_uses_[Register::kNumRegisters];
76   int destination_uses_[DoubleRegister::kMaxNumRegisters];
77 
78   // If we had to spill on demand, the currently spilled register's
79   // allocation index.
80   int spilled_register_;
81 };
82 
83 }  // namespace internal
84 }  // namespace v8
85 
86 #endif  // V8_CRANKSHAFT_IA32_LITHIUM_GAP_RESOLVER_IA32_H_
87