LaneBitmask.h revision 360660 
1//===- llvm/MC/LaneBitmask.h ------------------------------------*- 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/// \file
10/// A common definition of LaneBitmask for use in TableGen and CodeGen.
11///
12/// A lane mask is a bitmask representing the covering of a register with
13/// sub-registers.
14///
15/// This is typically used to track liveness at sub-register granularity.
16/// Lane masks for sub-register indices are similar to register units for
17/// physical registers. The individual bits in a lane mask can't be assigned
18/// any specific meaning. They can be used to check if two sub-register
19/// indices overlap.
20///
21/// Iff the target has a register such that:
22///
23///   getSubReg(Reg, A) overlaps getSubReg(Reg, B)
24///
25/// then:
26///
27///   (getSubRegIndexLaneMask(A) & getSubRegIndexLaneMask(B)) != 0
28
29#ifndef LLVM_MC_LANEBITMASK_H
30#define LLVM_MC_LANEBITMASK_H
31
32#include "llvm/Support/Compiler.h"
33#include "llvm/Support/Format.h"
34#include "llvm/Support/Printable.h"
35#include "llvm/Support/raw_ostream.h"
36
37namespace llvm {
38
39  struct LaneBitmask {
40    // When changing the underlying type, change the format string as well.
41    using Type = unsigned;
42    enum : unsigned { BitWidth = 8*sizeof(Type) };
43    constexpr static const char *const FormatStr = "%08X";
44
45    constexpr LaneBitmask() = default;
46    explicit constexpr LaneBitmask(Type V) : Mask(V) {}
47
48    constexpr bool operator== (LaneBitmask M) const { return Mask == M.Mask; }
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 none() const { return Mask == 0; }
52    constexpr bool any()  const { return Mask != 0; }
53    constexpr bool all()  const { return ~Mask == 0; }
54
55    constexpr LaneBitmask operator~() const {
56      return LaneBitmask(~Mask);
57    }
58    constexpr LaneBitmask operator|(LaneBitmask M) const {
59      return LaneBitmask(Mask | M.Mask);
60    }
61    constexpr LaneBitmask operator&(LaneBitmask M) const {
62      return LaneBitmask(Mask & M.Mask);
63    }
64    LaneBitmask &operator|=(LaneBitmask M) {
65      Mask |= M.Mask;
66      return *this;
67    }
68    LaneBitmask &operator&=(LaneBitmask M) {
69      Mask &= M.Mask;
70      return *this;
71    }
72
73    constexpr Type getAsInteger() const { return Mask; }
74
75    unsigned getNumLanes() const {
76      return countPopulation(Mask);
77    }
78    unsigned getHighestLane() const {
79      return Log2_32(Mask);
80    }
81
82    static constexpr LaneBitmask getNone() { return LaneBitmask(0); }
83    static constexpr LaneBitmask getAll() { return ~LaneBitmask(0); }
84    static constexpr LaneBitmask getLane(unsigned Lane) {
85      return LaneBitmask(Type(1) << Lane);
86    }
87
88  private:
89    Type Mask = 0;
90  };
91
92  /// Create Printable object to print LaneBitmasks on a \ref raw_ostream.
93  inline Printable PrintLaneMask(LaneBitmask LaneMask) {
94    return Printable([LaneMask](raw_ostream &OS) {
95      OS << format(LaneBitmask::FormatStr, LaneMask.getAsInteger());
96    });
97  }
98
99} // end namespace llvm
100
101#endif // LLVM_MC_LANEBITMASK_H
102