AllocationOrder.h revision c9672cb8bea13fcbcbdb1cf26708d831c034c089 
1//===-- llvm/CodeGen/AllocationOrder.h - Allocation Order -*- C++ -*-------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements an allocation order for virtual registers.
11//
12// The preferred allocation order for a virtual register depends on allocation
13// hints and target hooks. The AllocationOrder class encapsulates all of that.
14//
15//===----------------------------------------------------------------------===//
16
17#ifndef LLVM_CODEGEN_ALLOCATIONORDER_H
18#define LLVM_CODEGEN_ALLOCATIONORDER_H
19
20namespace llvm {
21
22class BitVector;
23class VirtRegMap;
24
25class AllocationOrder {
26  const unsigned *Begin;
27  const unsigned *End;
28  const unsigned *Pos;
29  const BitVector &Reserved;
30  unsigned Hint;
31public:
32
33  /// AllocationOrder - Create a new AllocationOrder for VirtReg.
34  /// @param VirtReg      Virtual register to allocate for.
35  /// @param VRM          Virtual register map for function.
36  /// @param ReservedRegs Set of reserved registers as returned by
37  ///        TargetRegisterInfo::getReservedRegs().
38  AllocationOrder(unsigned VirtReg,
39                  const VirtRegMap &VRM,
40                  const BitVector &ReservedRegs);
41
42  /// next - Return the next physical register in the allocation order, or 0.
43  /// It is safe to call next again after it returned 0.
44  /// It will keep returning 0 until rewind() is called.
45  unsigned next();
46
47  /// rewind - Start over from the beginning.
48  void rewind() { Pos = 0; }
49
50};
51
52} // end namespace llvm
53
54#endif
55