llvm/lib/Target/AMDGPU/Utils/SIDefinesUtils.h

//===-- SIDefines.h - SI Helper Functions -----------------------*- 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 - utility functions for the SIDefines and its common uses.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_LIB_TARGET_AMDGPU_UTILS_SIDEFINESUTILS_H
#define LLVM_LIB_TARGET_AMDGPU_UTILS_SIDEFINESUTILS_H

#include "llvm/MC/MCExpr.h"
#include <utility>

namespace llvm {
class MCContext;
namespace AMDGPU {

/// Deduce the least significant bit aligned shift and mask values for a binary
/// Complement \p Value (as they're defined in SIDefines.h as C_*) as a returned
/// pair<shift, mask>. That is to say \p Value == ~(mask << shift)
///
/// For example, given C_00B848_FWD_PROGRESS (i.e., 0x7FFFFFFF) from
/// SIDefines.h, this will return the pair as (31,1).
constexpr std::pair<unsigned, unsigned> getShiftMask(unsigned Value) {
  unsigned Shift = 0;
  unsigned Mask = 0;

  Mask = ~Value;
  for (; !(Mask & 1); Shift++, Mask >>= 1) {
  }

  return std::make_pair(Shift, Mask);
}

/// Provided with the MCExpr * \p Val, uint32 \p Mask and \p Shift, will return
/// the masked and left shifted, in said order of operations, MCExpr * created
/// within the MCContext \p Ctx.
///
/// For example, given MCExpr *Val, Mask == 0xf, Shift == 6 the returned MCExpr
/// * will be the equivalent of (Val & 0xf) << 6
inline const MCExpr *maskShiftSet(const MCExpr *Val, uint32_t Mask,
                                  uint32_t Shift, MCContext &Ctx) {
  if (Mask) {
    const MCExpr *MaskExpr = MCConstantExpr::create(Mask, Ctx);
    Val = MCBinaryExpr::createAnd(Val, MaskExpr, Ctx);
  }
  if (Shift) {
    const MCExpr *ShiftExpr = MCConstantExpr::create(Shift, Ctx);
    Val = MCBinaryExpr::createShl(Val, ShiftExpr, Ctx);
  }
  return Val;
}

/// Provided with the MCExpr * \p Val, uint32 \p Mask and \p Shift, will return
/// the right shifted and masked, in said order of operations, MCExpr * created
/// within the MCContext \p Ctx.
///
/// For example, given MCExpr *Val, Mask == 0xf, Shift == 6 the returned MCExpr
/// * will be the equivalent of (Val >> 6) & 0xf
inline const MCExpr *maskShiftGet(const MCExpr *Val, uint32_t Mask,
                                  uint32_t Shift, MCContext &Ctx) {
  if (Shift) {
    const MCExpr *ShiftExpr = MCConstantExpr::create(Shift, Ctx);
    Val = MCBinaryExpr::createLShr(Val, ShiftExpr, Ctx);
  }
  if (Mask) {
    const MCExpr *MaskExpr = MCConstantExpr::create(Mask, Ctx);
    Val = MCBinaryExpr::createAnd(Val, MaskExpr, Ctx);
  }
  return Val;
}

} // end namespace AMDGPU
} // end namespace llvm

#endif // LLVM_LIB_TARGET_AMDGPU_UTILS_SIDEFINESUTILS_H