BPFMCTargetDesc.cpp

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//===-- BPFMCTargetDesc.cpp - BPF Target Descriptions ---------------------===//
//
// 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 provides BPF specific target descriptions.
//
//===----------------------------------------------------------------------===//
 
#include "MCTargetDesc/BPFMCTargetDesc.h"
#include "MCTargetDesc/BPFInstPrinter.h"
#include "MCTargetDesc/BPFMCAsmInfo.h"
#include "TargetInfo/BPFTargetInfo.h"
#include "llvm/MC/MCInstrAnalysis.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Support/Compiler.h"
#include "llvm/TargetParser/Host.h"
 
#define GET_INSTRINFO_MC_DESC
#define ENABLE_INSTR_PREDICATE_VERIFIER
#include "BPFGenInstrInfo.inc"
 
#define GET_SUBTARGETINFO_MC_DESC
#include "BPFGenSubtargetInfo.inc"
 
#define GET_REGINFO_MC_DESC
#include "BPFGenRegisterInfo.inc"
 
using namespace llvm;
 
static MCInstrInfo *createBPFMCInstrInfo() {
  MCInstrInfo *X = new MCInstrInfo();
  InitBPFMCInstrInfo(X);
  return X;
}
 
static MCRegisterInfo *createBPFMCRegisterInfo(const Triple &TT) {
  MCRegisterInfo *X = new MCRegisterInfo();
  InitBPFMCRegisterInfo(X, BPF::R11 /* RAReg doesn't exist */);
  return X;
}
 
static MCSubtargetInfo *createBPFMCSubtargetInfo(const Triple &TT,
                                                 StringRef CPU, StringRef FS) {
  return createBPFMCSubtargetInfoImpl(TT, CPU, /*TuneCPU*/ CPU, FS);
}
 
static MCStreamer *
createBPFMCStreamer(const Triple &T, MCContext &Ctx,
                    std::unique_ptr<MCAsmBackend> &&MAB,
                    std::unique_ptr<MCObjectWriter> &&OW,
                    std::unique_ptr<MCCodeEmitter> &&Emitter) {
  return createELFStreamer(Ctx, std::move(MAB), std::move(OW),
                           std::move(Emitter));
}
 
static MCInstPrinter *createBPFMCInstPrinter(const Triple &T,
                                             unsigned SyntaxVariant,
                                             const MCAsmInfo &MAI,
                                             const MCInstrInfo &MII,
                                             const MCRegisterInfo &MRI) {
  if (SyntaxVariant == 0)
    return new BPFInstPrinter(MAI, MII, MRI);
  return nullptr;
}
 
namespace {
 
class BPFMCInstrAnalysis : public MCInstrAnalysis {
public:
  explicit BPFMCInstrAnalysis(const MCInstrInfo *Info)
      : MCInstrAnalysis(Info) {}
 
  bool evaluateBranch(const MCInst &Inst, uint64_t Addr, uint64_t Size,
                      uint64_t &Target) const override {
    // The target is the 3rd operand of cond inst and the 1st of uncond inst.
    int32_t Imm;
    if (isConditionalBranch(Inst)) {
      if (Inst.getOpcode() == BPF::JCOND ||
          Inst.getOpcode() == BPF::UNWIND_GOTO)
        Imm = (short)Inst.getOperand(0).getImm();
      else
        Imm = (short)Inst.getOperand(2).getImm();
    } else if (isUnconditionalBranch(Inst)) {
      if (Inst.getOpcode() == BPF::JMP)
        Imm = (short)Inst.getOperand(0).getImm();
      else
        Imm = (int)Inst.getOperand(0).getImm();
    } else
      return false;
 
    Target = Addr + Size + Imm * Size;
    return true;
  }
};
 
} // end anonymous namespace
 
static MCTargetStreamer *createNullTargetStreamer(MCStreamer &S) {
  return new MCTargetStreamer(S);
}
 
static MCInstrAnalysis *createBPFInstrAnalysis(const MCInstrInfo *Info) {
  return new BPFMCInstrAnalysis(Info);
}
 
extern "C" LLVM_ABI LLVM_EXTERNAL_VISIBILITY void LLVMInitializeBPFTargetMC() {
  for (Target *T :
       {&getTheBPFleTarget(), &getTheBPFbeTarget(), &getTheBPFTarget()}) {
    // Register the MC asm info.
    RegisterMCAsmInfo<BPFMCAsmInfo> X(*T);
 
    // Register the MC instruction info.
    TargetRegistry::RegisterMCInstrInfo(*T, createBPFMCInstrInfo);
 
    // Register the MC register info.
    TargetRegistry::RegisterMCRegInfo(*T, createBPFMCRegisterInfo);
 
    // Register the MC subtarget info.
    TargetRegistry::RegisterMCSubtargetInfo(*T,
                                            createBPFMCSubtargetInfo);
 
    // Register the object streamer
    TargetRegistry::RegisterELFStreamer(*T, createBPFMCStreamer);
 
    TargetRegistry::RegisterNullTargetStreamer(*T, createNullTargetStreamer);
 
    // Register the MCInstPrinter.
    TargetRegistry::RegisterMCInstPrinter(*T, createBPFMCInstPrinter);
 
    // Register the MC instruction analyzer.
    TargetRegistry::RegisterMCInstrAnalysis(*T, createBPFInstrAnalysis);
  }
 
  // Register the MC code emitter
  TargetRegistry::RegisterMCCodeEmitter(getTheBPFleTarget(),
                                        createBPFMCCodeEmitter);
  TargetRegistry::RegisterMCCodeEmitter(getTheBPFbeTarget(),
                                        createBPFbeMCCodeEmitter);
 
  // Register the ASM Backend
  TargetRegistry::RegisterMCAsmBackend(getTheBPFleTarget(),
                                       createBPFAsmBackend);
  TargetRegistry::RegisterMCAsmBackend(getTheBPFbeTarget(),
                                       createBPFbeAsmBackend);
 
  if (sys::IsLittleEndianHost) {
    TargetRegistry::RegisterMCCodeEmitter(getTheBPFTarget(),
                                          createBPFMCCodeEmitter);
    TargetRegistry::RegisterMCAsmBackend(getTheBPFTarget(),
                                         createBPFAsmBackend);
  } else {
    TargetRegistry::RegisterMCCodeEmitter(getTheBPFTarget(),
                                          createBPFbeMCCodeEmitter);
    TargetRegistry::RegisterMCAsmBackend(getTheBPFTarget(),
                                         createBPFbeAsmBackend);
  }
}