VEMCCodeEmitter.cpp

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//===-- VEMCCodeEmitter.cpp - Convert VE code to machine code -------------===//
//
// 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 implements the VEMCCodeEmitter class.
//
//===----------------------------------------------------------------------===//

#include "MCTargetDesc/VEFixupKinds.h"
#include "VE.h"
#include "VEMCExpr.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCFixup.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/EndianStream.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <cstdint>

using namespace llvm;

#define DEBUG_TYPE "mccodeemitter"

STATISTIC(MCNumEmitted, "Number of MC instructions emitted");

namespace {

class VEMCCodeEmitter : public MCCodeEmitter {
  const MCInstrInfo &MCII;
  MCContext &Ctx;

public:
  VEMCCodeEmitter(const MCInstrInfo &mcii, MCContext &ctx)
      : MCII(mcii), Ctx(ctx) {}
  VEMCCodeEmitter(const VEMCCodeEmitter &) = delete;
  VEMCCodeEmitter &operator=(const VEMCCodeEmitter &) = delete;
  ~VEMCCodeEmitter() override = default;

  void encodeInstruction(const MCInst &MI, raw_ostream &OS,
                         SmallVectorImpl<MCFixup> &Fixups,
                         const MCSubtargetInfo &STI) const override;

  // getBinaryCodeForInstr - TableGen'erated function for getting the
  // binary encoding for an instruction.
  uint64_t getBinaryCodeForInstr(const MCInst &MI,
                                 SmallVectorImpl<MCFixup> &Fixups,
                                 const MCSubtargetInfo &STI) const;

  /// getMachineOpValue - Return binary encoding of operand. If the machine
  /// operand requires relocation, record the relocation and return zero.
  unsigned getMachineOpValue(const MCInst &MI, const MCOperand &MO,
                             SmallVectorImpl<MCFixup> &Fixups,
                             const MCSubtargetInfo &STI) const;

  uint64_t getBranchTargetOpValue(const MCInst &MI, unsigned OpNo,
                                  SmallVectorImpl<MCFixup> &Fixups,
                                  const MCSubtargetInfo &STI) const;
  uint64_t getCCOpValue(const MCInst &MI, unsigned OpNo,
                        SmallVectorImpl<MCFixup> &Fixups,
                        const MCSubtargetInfo &STI) const;
  uint64_t getRDOpValue(const MCInst &MI, unsigned OpNo,
                        SmallVectorImpl<MCFixup> &Fixups,
                        const MCSubtargetInfo &STI) const;

private:
  FeatureBitset computeAvailableFeatures(const FeatureBitset &FB) const;
  void
  verifyInstructionPredicates(const MCInst &MI,
                              const FeatureBitset &AvailableFeatures) const;
};

} // end anonymous namespace

void VEMCCodeEmitter::encodeInstruction(const MCInst &MI, raw_ostream &OS,
                                        SmallVectorImpl<MCFixup> &Fixups,
                                        const MCSubtargetInfo &STI) const {
  verifyInstructionPredicates(MI,
                              computeAvailableFeatures(STI.getFeatureBits()));

  uint64_t Bits = getBinaryCodeForInstr(MI, Fixups, STI);
  support::endian::write<uint64_t>(OS, Bits, support::little);

  ++MCNumEmitted; // Keep track of the # of mi's emitted.
}

unsigned VEMCCodeEmitter::getMachineOpValue(const MCInst &MI,
                                            const MCOperand &MO,
                                            SmallVectorImpl<MCFixup> &Fixups,
                                            const MCSubtargetInfo &STI) const {
  if (MO.isReg())
    return Ctx.getRegisterInfo()->getEncodingValue(MO.getReg());

  if (MO.isImm())
    return MO.getImm();

  assert(MO.isExpr());
  const MCExpr *Expr = MO.getExpr();
  if (const VEMCExpr *SExpr = dyn_cast<VEMCExpr>(Expr)) {
    MCFixupKind Kind = (MCFixupKind)SExpr->getFixupKind();
    Fixups.push_back(MCFixup::create(0, Expr, Kind));
    return 0;
  }

  int64_t Res;
  if (Expr->evaluateAsAbsolute(Res))
    return Res;

  llvm_unreachable("Unhandled expression!");
  return 0;
}

uint64_t
VEMCCodeEmitter::getBranchTargetOpValue(const MCInst &MI, unsigned OpNo,
                                        SmallVectorImpl<MCFixup> &Fixups,
                                        const MCSubtargetInfo &STI) const {
  const MCOperand &MO = MI.getOperand(OpNo);
  if (MO.isReg() || MO.isImm())
    return getMachineOpValue(MI, MO, Fixups, STI);

  Fixups.push_back(
      MCFixup::create(0, MO.getExpr(), (MCFixupKind)VE::fixup_ve_pc_lo32));
  return 0;
}

uint64_t VEMCCodeEmitter::getCCOpValue(const MCInst &MI, unsigned OpNo,
                                       SmallVectorImpl<MCFixup> &Fixups,
                                       const MCSubtargetInfo &STI) const {
  const MCOperand &MO = MI.getOperand(OpNo);
  if (MO.isImm())
    return VECondCodeToVal(
        static_cast<VECC::CondCode>(getMachineOpValue(MI, MO, Fixups, STI)));
  return 0;
}

uint64_t VEMCCodeEmitter::getRDOpValue(const MCInst &MI, unsigned OpNo,
                                       SmallVectorImpl<MCFixup> &Fixups,
                                       const MCSubtargetInfo &STI) const {
  const MCOperand &MO = MI.getOperand(OpNo);
  if (MO.isImm())
    return VERDToVal(static_cast<VERD::RoundingMode>(
        getMachineOpValue(MI, MO, Fixups, STI)));
  return 0;
}

#define ENABLE_INSTR_PREDICATE_VERIFIER
#include "VEGenMCCodeEmitter.inc"

MCCodeEmitter *llvm::createVEMCCodeEmitter(const MCInstrInfo &MCII,
                                           const MCRegisterInfo &MRI,
                                           MCContext &Ctx) {
  return new VEMCCodeEmitter(MCII, Ctx);
}