llvm-project

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//===- Disassembler.cpp - Disassembler for hex strings --------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This class implements the disassembler of strings of bytes written in
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// hexadecimal, from standard input or from a file.
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//
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//===----------------------------------------------------------------------===//
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#include "Disassembler.h"
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#include "llvm/MC/MCAsmInfo.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCDisassembler/MCDisassembler.h"
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#include "llvm/MC/MCInst.h"
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#include "llvm/MC/MCRegisterInfo.h"
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#include "llvm/MC/MCStreamer.h"
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#include "llvm/MC/MCSubtargetInfo.h"
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#include "llvm/MC/TargetRegistry.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include "llvm/Support/SourceMgr.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/TargetParser/Triple.h"
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using namespace llvm;
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typedef std::pair<std::vector<unsigned char>, std::vector<const char *>>
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    ByteArrayTy;
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static bool PrintInsts(const MCDisassembler &DisAsm, const ByteArrayTy &Bytes,
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                       SourceMgr &SM, raw_ostream &Out, MCStreamer &Streamer,
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                       bool InAtomicBlock, const MCSubtargetInfo &STI) {
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  ArrayRef<uint8_t> Data(Bytes.first.data(), Bytes.first.size());
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  // Disassemble it to strings.
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  uint64_t Size;
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  uint64_t Index;
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  for (Index = 0; Index < Bytes.first.size(); Index += Size) {
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    MCInst Inst;
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    MCDisassembler::DecodeStatus S;
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    S = DisAsm.getInstruction(Inst, Size, Data.slice(Index), Index, nulls());
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    switch (S) {
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    case MCDisassembler::Fail:
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      SM.PrintMessage(SMLoc::getFromPointer(Bytes.second[Index]),
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                      SourceMgr::DK_Warning, "invalid instruction encoding");
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      // Don't try to resynchronise the stream in a block
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      if (InAtomicBlock)
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        return true;
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      if (Size == 0)
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        Size = 1;  // skip illegible bytes
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      break;
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    case MCDisassembler::SoftFail:
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      SM.PrintMessage(SMLoc::getFromPointer(Bytes.second[Index]),
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                      SourceMgr::DK_Warning,
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                      "potentially undefined instruction encoding");
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      [[fallthrough]];
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    case MCDisassembler::Success:
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      Streamer.emitInstruction(Inst, STI);
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      break;
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    }
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  }
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  return false;
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}
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static bool SkipToToken(StringRef &Str) {
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  for (;;) {
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    if (Str.empty())
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      return false;
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    // Strip horizontal whitespace and commas.
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    if (size_t Pos = Str.find_first_not_of(" \t\r\n,")) {
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      Str = Str.substr(Pos);
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      continue;
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    }
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    // If this is the start of a comment, remove the rest of the line.
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    if (Str[0] == '#') {
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      Str = Str.substr(Str.find_first_of('\n'));
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      continue;
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    }
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    return true;
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  }
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}
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static bool ByteArrayFromString(ByteArrayTy &ByteArray, StringRef &Str,
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                                SourceMgr &SM) {
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  while (SkipToToken(Str)) {
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    // Handled by higher level
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    if (Str[0] == '[' || Str[0] == ']')
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      return false;
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    // Get the current token.
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    size_t Next = Str.find_first_of(" \t\n\r,#[]");
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    StringRef Value = Str.substr(0, Next);
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    // Convert to a byte and add to the byte vector.
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    unsigned ByteVal;
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    if (Value.getAsInteger(0, ByteVal) || ByteVal > 255) {
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      // If we have an error, print it and skip to the end of line.
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      SM.PrintMessage(SMLoc::getFromPointer(Value.data()), SourceMgr::DK_Error,
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                      "invalid input token");
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      Str = Str.substr(Str.find('\n'));
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      ByteArray.first.clear();
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      ByteArray.second.clear();
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      continue;
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    }
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    ByteArray.first.push_back(ByteVal);
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    ByteArray.second.push_back(Value.data());
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    Str = Str.substr(Next);
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  }
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  return false;
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}
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int Disassembler::disassemble(const Target &T, const std::string &TripleName,
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                              MCSubtargetInfo &STI, MCStreamer &Streamer,
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                              MemoryBuffer &Buffer, SourceMgr &SM,
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                              raw_ostream &Out) {
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  std::unique_ptr<const MCRegisterInfo> MRI(T.createMCRegInfo(TripleName));
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  if (!MRI) {
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    errs() << "error: no register info for target " << TripleName << "\n";
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    return -1;
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  }
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  MCTargetOptions MCOptions;
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  std::unique_ptr<const MCAsmInfo> MAI(
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      T.createMCAsmInfo(*MRI, TripleName, MCOptions));
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  if (!MAI) {
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    errs() << "error: no assembly info for target " << TripleName << "\n";
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    return -1;
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  }
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  // Set up the MCContext for creating symbols and MCExpr's.
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  MCContext Ctx(Triple(TripleName), MAI.get(), MRI.get(), &STI);
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  std::unique_ptr<const MCDisassembler> DisAsm(
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      T.createMCDisassembler(STI, Ctx));
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  if (!DisAsm) {
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    errs() << "error: no disassembler for target " << TripleName << "\n";
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    return -1;
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  }
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  // Set up initial section manually here
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  Streamer.initSections(false, STI);
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  bool ErrorOccurred = false;
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  // Convert the input to a vector for disassembly.
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  ByteArrayTy ByteArray;
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  StringRef Str = Buffer.getBuffer();
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  bool InAtomicBlock = false;
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  while (SkipToToken(Str)) {
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    ByteArray.first.clear();
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    ByteArray.second.clear();
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    if (Str[0] == '[') {
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      if (InAtomicBlock) {
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        SM.PrintMessage(SMLoc::getFromPointer(Str.data()), SourceMgr::DK_Error,
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                        "nested atomic blocks make no sense");
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        ErrorOccurred = true;
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      }
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      InAtomicBlock = true;
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      Str = Str.drop_front();
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      continue;
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    } else if (Str[0] == ']') {
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      if (!InAtomicBlock) {
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        SM.PrintMessage(SMLoc::getFromPointer(Str.data()), SourceMgr::DK_Error,
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                        "attempt to close atomic block without opening");
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        ErrorOccurred = true;
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      }
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      InAtomicBlock = false;
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      Str = Str.drop_front();
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      continue;
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    }
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    // It's a real token, get the bytes and emit them
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    ErrorOccurred |= ByteArrayFromString(ByteArray, Str, SM);
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    if (!ByteArray.first.empty())
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      ErrorOccurred |=
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          PrintInsts(*DisAsm, ByteArray, SM, Out, Streamer, InAtomicBlock, STI);
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  }
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  if (InAtomicBlock) {
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    SM.PrintMessage(SMLoc::getFromPointer(Str.data()), SourceMgr::DK_Error,
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                    "unclosed atomic block");
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    ErrorOccurred = true;
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  }
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  return ErrorOccurred;
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}
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