include/llvm/MC/LaneBitmask.h

   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;
  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