llvm/lib/Target/Mips/MipsISelDAGToDAG.h

//===---- MipsISelDAGToDAG.h - A Dag to Dag Inst Selector for Mips --------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file defines an instruction selector for the MIPS target.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_LIB_TARGET_MIPS_MIPSISELDAGTODAG_H
#define LLVM_LIB_TARGET_MIPS_MIPSISELDAGTODAG_H

#include "Mips.h"
#include "MipsSubtarget.h"
#include "MipsTargetMachine.h"
#include "llvm/CodeGen/SelectionDAGISel.h"

//===----------------------------------------------------------------------===//
// Instruction Selector Implementation
//===----------------------------------------------------------------------===//

//===----------------------------------------------------------------------===//
// MipsDAGToDAGISel - MIPS specific code to select MIPS machine
// instructions for SelectionDAG operations.
//===----------------------------------------------------------------------===//
namespace llvm {

class MipsDAGToDAGISel : public SelectionDAGISel {
public:
  MipsDAGToDAGISel() = delete;

  explicit MipsDAGToDAGISel(MipsTargetMachine &TM, CodeGenOptLevel OL)
      : SelectionDAGISel(TM, OL), Subtarget(nullptr) {}

  bool runOnMachineFunction(MachineFunction &MF) override;

protected:
  SDNode *getGlobalBaseReg();

  /// Keep a pointer to the MipsSubtarget around so that we can make the right
  /// decision when generating code for different targets.
  const MipsSubtarget *Subtarget;

private:
  // Include the pieces autogenerated from the target description.
  #include "MipsGenDAGISel.inc"

  // Complex Pattern.
  /// (reg + imm).
  virtual bool selectAddrRegImm(SDValue Addr, SDValue &Base,
                                SDValue &Offset) const;

  /// Fall back on this function if all else fails.
  virtual bool selectAddrDefault(SDValue Addr, SDValue &Base,
                                 SDValue &Offset) const;

  /// Match integer address pattern.
  virtual bool selectIntAddr(SDValue Addr, SDValue &Base,
                             SDValue &Offset) const;

  virtual bool selectIntAddr11MM(SDValue Addr, SDValue &Base,
                                 SDValue &Offset) const;

  virtual bool selectIntAddr12MM(SDValue Addr, SDValue &Base,
                               SDValue &Offset) const;

  virtual bool selectIntAddr16MM(SDValue Addr, SDValue &Base,
                                 SDValue &Offset) const;

  virtual bool selectIntAddrLSL2MM(SDValue Addr, SDValue &Base,
                                   SDValue &Offset) const;

  /// Match addr+simm10 and addr
  virtual bool selectIntAddrSImm10(SDValue Addr, SDValue &Base,
                                   SDValue &Offset) const;

  virtual bool selectIntAddrSImm10Lsl1(SDValue Addr, SDValue &Base,
                                       SDValue &Offset) const;

  virtual bool selectIntAddrSImm10Lsl2(SDValue Addr, SDValue &Base,
                                       SDValue &Offset) const;

  virtual bool selectIntAddrSImm10Lsl3(SDValue Addr, SDValue &Base,
                                       SDValue &Offset) const;

  virtual bool selectAddr16(SDValue Addr, SDValue &Base, SDValue &Offset);
  virtual bool selectAddr16SP(SDValue Addr, SDValue &Base, SDValue &Offset);

  /// Select constant vector splats.
  virtual bool selectVSplat(SDNode *N, APInt &Imm,
                            unsigned MinSizeInBits) const;
  virtual bool selectVSplatCommon(SDValue N, SDValue &Imm, bool Signed,
                                  unsigned ImmBitSize) const;
  /// Select constant vector splats whose value fits in a uimm<Bits>.
  template <unsigned Bits>
  bool selectVSplatUimm(SDValue N, SDValue &Imm) const {
    return selectVSplatCommon(N, Imm, false, Bits);
  }
  /// Select constant vector splats whose value fits in a simm<Bits>.
  template <unsigned Bits>
  bool selectVSplatSimm(SDValue N, SDValue &Imm) const {
    return selectVSplatCommon(N, Imm, true, Bits);
  }
  /// Select constant vector splats whose value is a power of 2.
  virtual bool selectVSplatUimmPow2(SDValue N, SDValue &Imm) const;
  /// Select constant vector splats whose value is the inverse of a
  /// power of 2.
  virtual bool selectVSplatUimmInvPow2(SDValue N, SDValue &Imm) const;
  /// Select constant vector splats whose value is a run of set bits
  /// ending at the most significant bit
  virtual bool selectVSplatMaskL(SDValue N, SDValue &Imm) const;
  /// Select constant vector splats whose value is a run of set bits
  /// starting at bit zero.
  virtual bool selectVSplatMaskR(SDValue N, SDValue &Imm) const;

  /// Select constant vector splats whose value is 1.
  virtual bool selectVSplatImmEq1(SDValue N) const;

  /// Convert vector addition with vector subtraction if that allows to encode
  /// constant as an immediate and thus avoid extra 'ldi' instruction.
  /// add X, <-1, -1...> --> sub X, <1, 1...>
  bool selectVecAddAsVecSubIfProfitable(SDNode *Node);

  void Select(SDNode *N) override;

  virtual bool trySelect(SDNode *Node) = 0;

  // getImm - Return a target constant with the specified value.
  inline SDValue getImm(const SDNode *Node, uint64_t Imm) {
    return CurDAG->getTargetConstant(Imm, SDLoc(Node), Node->getValueType(0));
  }

  inline SDValue getSignedImm(const SDNode *Node, int64_t Imm) {
    return CurDAG->getSignedTargetConstant(Imm, SDLoc(Node),
                                           Node->getValueType(0));
  }

  virtual void processFunctionAfterISel(MachineFunction &MF) = 0;

  bool SelectInlineAsmMemoryOperand(const SDValue &Op,
                                    InlineAsm::ConstraintCode ConstraintID,
                                    std::vector<SDValue> &OutOps) override;
  bool isUnneededShiftMask(SDNode *N, unsigned ShAmtBits) const;
};

class MipsDAGToDAGISelLegacy : public SelectionDAGISelLegacy {
public:
  static char ID;
  MipsDAGToDAGISelLegacy(std::unique_ptr<SelectionDAGISel> S);
  void getAnalysisUsage(AnalysisUsage &AU) const override;
};
}

#endif