//===- llvm/MC/LaneBitmask.h ------------------------------------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

///

/// \file

/// A common definition of LaneBitmask for use in TableGen and CodeGen.

///

/// A lane mask is a bitmask representing the covering of a register with

/// sub-registers.

///

/// This is typically used to track liveness at sub-register granularity.

/// Lane masks for sub-register indices are similar to register units for

/// physical registers. The individual bits in a lane mask can't be assigned

/// any specific meaning. They can be used to check if two sub-register

/// indices overlap.

///

/// Iff the target has a register such that:

///

///   getSubReg(Reg, A) overlaps getSubReg(Reg, B)

///

/// then:

///

///   (getSubRegIndexLaneMask(A) & getSubRegIndexLaneMask(B)) != 0

#ifndef LLVM_MC_LANEBITMASK_H

#define LLVM_MC_LANEBITMASK_H

#include "llvm/Support/Compiler.h"

#include "llvm/Support/Format.h"

#include "llvm/Support/Printable.h"

#include "llvm/Support/raw_ostream.h"

namespace llvm {

  struct LaneBitmask {

    // When changing the underlying type, change the format string as well.

    using Type = unsigned;

    enum : unsigned { BitWidth = 8*sizeof(Type) };

    constexpr static const char *const FormatStr = "%08X";

    constexpr LaneBitmask() = default;

    explicit constexpr LaneBitmask(Type V) : Mask(V) {}

    constexpr bool operator== (LaneBitmask M) const { return Mask == M.Mask; }

    constexpr bool operator!= (LaneBitmask M) const { return Mask != M.Mask; }

    constexpr bool operator< (LaneBitmask M)  const { return Mask < M.Mask; }

    constexpr bool none() const { return Mask == 0; }

    constexpr bool any()  const { return Mask != 0; }

    constexpr bool all()  const { return ~Mask == 0; }

    constexpr LaneBitmask operator~() const {

      return LaneBitmask(~Mask);

    }

    constexpr LaneBitmask operator|(LaneBitmask M) const {

      return LaneBitmask(Mask | M.Mask);

    }

    constexpr LaneBitmask operator&(LaneBitmask M) const {

      return LaneBitmask(Mask & M.Mask);

    }

    LaneBitmask &operator|=(LaneBitmask M) {

      Mask |= M.Mask;

      return *this;

    }

    LaneBitmask &operator&=(LaneBitmask M) {

      Mask &= M.Mask;

      return *this;

    }

    constexpr Type getAsInteger() const { return Mask; }

    unsigned getNumLanes() const {

      return countPopulation(Mask);

    }

    unsigned getHighestLane() const {

      return Log2_32(Mask);

    }

    static constexpr LaneBitmask getNone() { return LaneBitmask(0); }

    static constexpr LaneBitmask getAll() { return ~LaneBitmask(0); }

    static constexpr LaneBitmask getLane(unsigned Lane) {

      return LaneBitmask(Type(1) << Lane);

    }

  private:

    Type Mask = 0;

  };

  /// Create Printable object to print LaneBitmasks on a \ref raw_ostream.

  inline Printable PrintLaneMask(LaneBitmask LaneMask) {

    return Printable([LaneMask](raw_ostream &OS) {

      OS << format(LaneBitmask::FormatStr, LaneMask.getAsInteger());

    });

  }

} // end namespace llvm

#endif // LLVM_MC_LANEBITMASK_H