LLVM  6.0.0svn
AllocationOrder.h
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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_LIB_CODEGEN_ALLOCATIONORDER_H
18 #define LLVM_LIB_CODEGEN_ALLOCATIONORDER_H
19 
20 #include "llvm/ADT/ArrayRef.h"
21 #include "llvm/ADT/STLExtras.h"
22 #include "llvm/MC/MCRegisterInfo.h"
23 
24 namespace llvm {
25 
26 class RegisterClassInfo;
27 class VirtRegMap;
28 class LiveRegMatrix;
29 
32  ArrayRef<MCPhysReg> Order;
33  int Pos;
34 
35  // If HardHints is true, *only* Hints will be returned.
36  bool HardHints;
37 
38 public:
39 
40  /// Create a new AllocationOrder for VirtReg.
41  /// @param VirtReg Virtual register to allocate for.
42  /// @param VRM Virtual register map for function.
43  /// @param RegClassInfo Information about reserved and allocatable registers.
44  AllocationOrder(unsigned VirtReg,
45  const VirtRegMap &VRM,
46  const RegisterClassInfo &RegClassInfo,
47  const LiveRegMatrix *Matrix);
48 
49  /// Get the allocation order without reordered hints.
50  ArrayRef<MCPhysReg> getOrder() const { return Order; }
51 
52  /// Return the next physical register in the allocation order, or 0.
53  /// It is safe to call next() again after it returned 0, it will keep
54  /// returning 0 until rewind() is called.
55  unsigned next(unsigned Limit = 0) {
56  if (Pos < 0)
57  return Hints.end()[Pos++];
58  if (HardHints)
59  return 0;
60  if (!Limit)
61  Limit = Order.size();
62  while (Pos < int(Limit)) {
63  unsigned Reg = Order[Pos++];
64  if (!isHint(Reg))
65  return Reg;
66  }
67  return 0;
68  }
69 
70  /// As next(), but allow duplicates to be returned, and stop before the
71  /// Limit'th register in the RegisterClassInfo allocation order.
72  ///
73  /// This can produce more than Limit registers if there are hints.
74  unsigned nextWithDups(unsigned Limit) {
75  if (Pos < 0)
76  return Hints.end()[Pos++];
77  if (HardHints)
78  return 0;
79  if (Pos < int(Limit))
80  return Order[Pos++];
81  return 0;
82  }
83 
84  /// Start over from the beginning.
85  void rewind() { Pos = -int(Hints.size()); }
86 
87  /// Return true if the last register returned from next() was a preferred register.
88  bool isHint() const { return Pos <= 0; }
89 
90  /// Return true if PhysReg is a preferred register.
91  bool isHint(unsigned PhysReg) const { return is_contained(Hints, PhysReg); }
92 };
93 
94 } // end namespace llvm
95 
96 #endif
bool isHint() const
Return true if the last register returned from next() was a preferred register.
void rewind()
Start over from the beginning.
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
unsigned next(unsigned Limit=0)
Return the next physical register in the allocation order, or 0.
Live Register Matrix
unsigned nextWithDups(unsigned Limit)
As next(), but allow duplicates to be returned, and stop before the Limit&#39;th register in the Register...
Reg
All possible values of the reg field in the ModR/M byte.
bool isHint(unsigned PhysReg) const
Return true if PhysReg is a preferred register.
size_t size() const
size - Get the array size.
Definition: ArrayRef.h:149
ArrayRef< MCPhysReg > getOrder() const
Get the allocation order without reordered hints.
#define LLVM_LIBRARY_VISIBILITY
LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked into a shared library...
Definition: Compiler.h:105
bool is_contained(R &&Range, const E &Element)
Wrapper function around std::find to detect if an element exists in a container.
Definition: STLExtras.h:821