LaneBitmask.h revision 321369 
1//===- llvm/MC/LaneBitmask.h ------------------------------------*- 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/// \file
11/// A common definition of LaneBitmask for use in TableGen and CodeGen.
12///
13/// A lane mask is a bitmask representing the covering of a register with
14/// sub-registers.
15///
16/// This is typically used to track liveness at sub-register granularity.
17/// Lane masks for sub-register indices are similar to register units for
18/// physical registers. The individual bits in a lane mask can't be assigned
19/// any specific meaning. They can be used to check if two sub-register
20/// indices overlap.
21///
22/// Iff the target has a register such that:
23///
24///   getSubReg(Reg, A) overlaps getSubReg(Reg, B)
25///
26/// then:
27///
28///   (getSubRegIndexLaneMask(A) & getSubRegIndexLaneMask(B)) != 0
29
30#ifndef LLVM_MC_LANEBITMASK_H
31#define LLVM_MC_LANEBITMASK_H
32
33#include "llvm/Support/Compiler.h"
34#include "llvm/Support/Format.h"
35#include "llvm/Support/Printable.h"
36#include "llvm/Support/raw_ostream.h"
37
38namespace llvm {
39
40  struct LaneBitmask {
41    // When changing the underlying type, change the format string as well.
42    using Type = unsigned;
43    enum : unsigned { BitWidth = 8*sizeof(Type) };
44    constexpr static const char *const FormatStr = "%08X";
45
46    constexpr LaneBitmask() = default;
47    explicit constexpr LaneBitmask(Type V) : Mask(V) {}
48
49    constexpr bool operator== (LaneBitmask M) const { return Mask == M.Mask; }
50    constexpr bool operator!= (LaneBitmask M) const { return Mask != M.Mask; }
51    constexpr bool operator< (LaneBitmask M)  const { return Mask < M.Mask; }
52    constexpr bool none() const { return Mask == 0; }
53    constexpr bool any()  const { return Mask != 0; }
54    constexpr bool all()  const { return ~Mask == 0; }
55
56    constexpr LaneBitmask operator~() const {
57      return LaneBitmask(~Mask);
58    }
59    constexpr LaneBitmask operator|(LaneBitmask M) const {
60      return LaneBitmask(Mask | M.Mask);
61    }
62    constexpr LaneBitmask operator&(LaneBitmask M) const {
63      return LaneBitmask(Mask & M.Mask);
64    }
65    LaneBitmask &operator|=(LaneBitmask M) {
66      Mask |= M.Mask;
67      return *this;
68    }
69    LaneBitmask &operator&=(LaneBitmask M) {
70      Mask &= M.Mask;
71      return *this;
72    }
73
74    constexpr Type getAsInteger() const { return Mask; }
75
76    static LaneBitmask getNone() { return LaneBitmask(0); }
77    static LaneBitmask getAll()  { return ~LaneBitmask(0); }
78    static LaneBitmask getLane(unsigned Lane) {
79      return LaneBitmask(Type(1) << Lane);
80    }
81
82  private:
83    Type Mask = 0;
84  };
85
86  /// Create Printable object to print LaneBitmasks on a \ref raw_ostream.
87  static LLVM_ATTRIBUTE_UNUSED Printable PrintLaneMask(LaneBitmask LaneMask) {
88    return Printable([LaneMask](raw_ostream &OS) {
89      OS << format(LaneBitmask::FormatStr, LaneMask.getAsInteger());
90    });
91  }
92
93} // end namespace llvm
94
95#endif // LLVM_MC_LANEBITMASK_H
96