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/MathExtras.h"
35 #include "llvm/Support/Printable.h"
36 #include "llvm/Support/raw_ostream.h"
37 
38 namespace llvm {
39 
40   struct LaneBitmask {
41     // When changing the underlying type, change the format string as well.
42     using Type = uint64_t;
43     enum : unsigned { BitWidth = 8*sizeof(Type) };
44     constexpr static const char *const FormatStr = "%016llX";
45 
46     constexpr LaneBitmask() = default;
LaneBitmaskLaneBitmask47     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; }
noneLaneBitmask52     constexpr bool none() const { return Mask == 0; }
anyLaneBitmask53     constexpr bool any()  const { return Mask != 0; }
allLaneBitmask54     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 
getAsIntegerLaneBitmask74     constexpr Type getAsInteger() const { return Mask; }
75 
getNumLanesLaneBitmask76     unsigned getNumLanes() const {
77       return countPopulation(Mask);
78     }
getHighestLaneLaneBitmask79     unsigned getHighestLane() const {
80       return Log2_64(Mask);
81     }
82 
getNoneLaneBitmask83     static constexpr LaneBitmask getNone() { return LaneBitmask(0); }
getAllLaneBitmask84     static constexpr LaneBitmask getAll() { return ~LaneBitmask(0); }
getLaneLaneBitmask85     static constexpr LaneBitmask getLane(unsigned Lane) {
86       return LaneBitmask(Type(1) << Lane);
87     }
88 
89   private:
90     Type Mask = 0;
91   };
92 
93   /// Create Printable object to print LaneBitmasks on a \ref raw_ostream.
PrintLaneMask(LaneBitmask LaneMask)94   inline Printable PrintLaneMask(LaneBitmask LaneMask) {
95     return Printable([LaneMask](raw_ostream &OS) {
96       OS << format(LaneBitmask::FormatStr, LaneMask.getAsInteger());
97     });
98   }
99 
100 } // end namespace llvm
101 
102 #endif // LLVM_MC_LANEBITMASK_H
103