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      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 = uint64_t;
     42     enum : unsigned { BitWidth = 8*sizeof(Type) };
     43     constexpr static const char *const FormatStr = "%016llX";
     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_64(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