LLVM  12.0.0git
AllocationOrder.h
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1 //===-- llvm/CodeGen/AllocationOrder.h - Allocation Order -*- C++ -*-------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements an allocation order for virtual registers.
10 //
11 // The preferred allocation order for a virtual register depends on allocation
12 // hints and target hooks. The AllocationOrder class encapsulates all of that.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #ifndef LLVM_LIB_CODEGEN_ALLOCATIONORDER_H
17 #define LLVM_LIB_CODEGEN_ALLOCATIONORDER_H
18 
19 #include "llvm/ADT/ArrayRef.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/ADT/STLExtras.h"
22 #include "llvm/MC/MCRegister.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.
This class represents lattice values for constants.
Definition: AllocatorList.h:23
unsigned Reg
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...
bool isHint(unsigned PhysReg) const
Return true if PhysReg is a preferred register.
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: APInt.h:32
size_t size() const
size - Get the array size.
Definition: ArrayRef.h:156
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:130
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:883
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:1549