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 
37 namespace 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;
LaneBitmaskLaneBitmask46     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; }
noneLaneBitmask51     constexpr bool none() const { return Mask == 0; }
anyLaneBitmask52     constexpr bool any()  const { return Mask != 0; }
allLaneBitmask53     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 
getAsIntegerLaneBitmask73     constexpr Type getAsInteger() const { return Mask; }
74 
getNumLanesLaneBitmask75     unsigned getNumLanes() const {
76       return countPopulation(Mask);
77     }
getHighestLaneLaneBitmask78     unsigned getHighestLane() const {
79       return Log2_32(Mask);
80     }
81 
getNoneLaneBitmask82     static constexpr LaneBitmask getNone() { return LaneBitmask(0); }
getAllLaneBitmask83     static constexpr LaneBitmask getAll() { return ~LaneBitmask(0); }
getLaneLaneBitmask84     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.
PrintLaneMask(LaneBitmask LaneMask)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