llvm/tools/llvm-mc/Disassembler.cpp

   1 //===- Disassembler.cpp - Disassembler for hex strings --------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This class implements the disassembler of strings of bytes written in
  10 // hexadecimal, from standard input or from a file.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "Disassembler.h"
  15 #include "llvm/ADT/StringExtras.h"
  16 #include "llvm/MC/MCAsmInfo.h"
  17 #include "llvm/MC/MCContext.h"
  18 #include "llvm/MC/MCDisassembler/MCDisassembler.h"
  19 #include "llvm/MC/MCInst.h"
  20 #include "llvm/MC/MCObjectFileInfo.h"
  21 #include "llvm/MC/MCRegisterInfo.h"
  22 #include "llvm/MC/MCStreamer.h"
  23 #include "llvm/MC/MCSubtargetInfo.h"
  24 #include "llvm/MC/TargetRegistry.h"
  25 #include "llvm/Support/MemoryBuffer.h"
  26 #include "llvm/Support/SourceMgr.h"
  27 #include "llvm/Support/raw_ostream.h"
  28 #include "llvm/TargetParser/Triple.h"
  29
  30 using namespace llvm;
  31
  32 typedef std::pair<std::vector<unsigned char>, std::vector<const char *>>
  33     ByteArrayTy;
  34
  35 static bool PrintInsts(const MCDisassembler &DisAsm, const ByteArrayTy &Bytes,
  36                        SourceMgr &SM, MCStreamer &Streamer, bool InAtomicBlock,
  37                        const MCSubtargetInfo &STI) {
  38   ArrayRef<uint8_t> Data(Bytes.first.data(), Bytes.first.size());
  39
  40   // Disassemble it to strings.
  41   uint64_t Size;
  42   uint64_t Index;
  43
  44   for (Index = 0; Index < Bytes.first.size(); Index += Size) {
  45     MCInst Inst;
  46
  47     MCDisassembler::DecodeStatus S;
  48     S = DisAsm.getInstruction(Inst, Size, Data.slice(Index), Index, nulls());
  49     switch (S) {
  50     case MCDisassembler::Fail:
  51       SM.PrintMessage(SMLoc::getFromPointer(Bytes.second[Index]),
  52                       SourceMgr::DK_Warning,
  53                       "invalid instruction encoding");
  54       // Don't try to resynchronise the stream in a block
  55       if (InAtomicBlock)
  56         return true;
  57
  58       if (Size == 0)
  59         Size = 1; // skip illegible bytes
  60
  61       break;
  62
  63     case MCDisassembler::SoftFail:
  64       SM.PrintMessage(SMLoc::getFromPointer(Bytes.second[Index]),
  65                       SourceMgr::DK_Warning,
  66                       "potentially undefined instruction encoding");
  67       [[fallthrough]];
  68
  69     case MCDisassembler::Success:
  70       Streamer.emitInstruction(Inst, STI);
  71       break;
  72     }
  73   }
  74
  75   return false;
  76 }
  77
  78 static bool SkipToToken(StringRef &Str) {
  79   for (;;) {
  80     if (Str.empty())
  81       return false;
  82
  83     // Strip horizontal whitespace and commas.
  84     if (size_t Pos = Str.find_first_not_of(" \t\r\n,")) {
  85       Str = Str.substr(Pos);
  86       continue;
  87     }
  88
  89     // If this is the start of a comment, remove the rest of the line.
  90     if (Str[0] == '#') {
  91         Str = Str.substr(Str.find_first_of('\n'));
  92       continue;
  93     }
  94     return true;
  95   }
  96 }
  97
  98 static bool byteArrayFromString(ByteArrayTy &ByteArray, StringRef &Str,
  99                                 SourceMgr &SM, bool HexBytes) {
 100   while (SkipToToken(Str)) {
 101     // Handled by higher level
 102     if (Str[0] == '[' || Str[0] == ']')
 103       return false;
 104
 105     // Get the current token.
 106     size_t Next = Str.find_first_of(" \t\n\r,#[]");
 107     StringRef Value = Str.substr(0, Next);
 108
 109     // Convert to a byte and add to the byte vector.
 110     unsigned ByteVal;
 111     if (HexBytes) {
 112       if (Next < 2) {
 113         SM.PrintMessage(SMLoc::getFromPointer(Value.data()),
 114                         SourceMgr::DK_Error, "expected two hex digits");
 115         Str = Str.substr(Next);
 116         return true;
 117       }
 118       Next = 2;
 119       unsigned C0 = hexDigitValue(Value[0]);
 120       unsigned C1 = hexDigitValue(Value[1]);
 121       if (C0 == -1u || C1 == -1u) {
 122         SM.PrintMessage(SMLoc::getFromPointer(Value.data()),
 123                         SourceMgr::DK_Error, "invalid input token");
 124         Str = Str.substr(Next);
 125         return true;
 126       }
 127       ByteVal = C0 * 16 + C1;
 128     } else if (Value.getAsInteger(0, ByteVal) || ByteVal > 255) {
 129       // If we have an error, print it and skip to the end of line.
 130       SM.PrintMessage(SMLoc::getFromPointer(Value.data()), SourceMgr::DK_Error,
 131                       "invalid input token");
 132       Str = Str.substr(Str.find('\n'));
 133       ByteArray.first.clear();
 134       ByteArray.second.clear();
 135       continue;
 136     }
 137
 138     ByteArray.first.push_back(ByteVal);
 139     ByteArray.second.push_back(Value.data());
 140     Str = Str.substr(Next);
 141   }
 142
 143   return false;
 144 }
 145
 146 int Disassembler::disassemble(const Target &T, const std::string &Triple,
 147                               MCSubtargetInfo &STI, MCStreamer &Streamer,
 148                               MemoryBuffer &Buffer, SourceMgr &SM,
 149                               MCContext &Ctx, const MCTargetOptions &MCOptions,
 150                               bool HexBytes) {
 151   std::unique_ptr<const MCRegisterInfo> MRI(T.createMCRegInfo(Triple));
 152   if (!MRI) {
 153     errs() << "error: no register info for target " << Triple << "\n";
 154     return -1;
 155   }
 156
 157   std::unique_ptr<const MCAsmInfo> MAI(
 158       T.createMCAsmInfo(*MRI, Triple, MCOptions));
 159   if (!MAI) {
 160     errs() << "error: no assembly info for target " << Triple << "\n";
 161     return -1;
 162   }
 163
 164   std::unique_ptr<const MCDisassembler> DisAsm(
 165     T.createMCDisassembler(STI, Ctx));
 166   if (!DisAsm) {
 167     errs() << "error: no disassembler for target " << Triple << "\n";
 168     return -1;
 169   }
 170
 171   bool ErrorOccurred = false;
 172
 173   // Convert the input to a vector for disassembly.
 174   ByteArrayTy ByteArray;
 175   StringRef Str = Buffer.getBuffer();
 176   bool InAtomicBlock = false;
 177
 178   while (SkipToToken(Str)) {
 179     ByteArray.first.clear();
 180     ByteArray.second.clear();
 181
 182     if (Str[0] == '[') {
 183       if (InAtomicBlock) {
 184         SM.PrintMessage(SMLoc::getFromPointer(Str.data()), SourceMgr::DK_Error,
 185                         "nested atomic blocks make no sense");
 186         ErrorOccurred = true;
 187       }
 188       InAtomicBlock = true;
 189       Str = Str.drop_front();
 190       continue;
 191     } else if (Str[0] == ']') {
 192       if (!InAtomicBlock) {
 193         SM.PrintMessage(SMLoc::getFromPointer(Str.data()), SourceMgr::DK_Error,
 194                         "attempt to close atomic block without opening");
 195         ErrorOccurred = true;
 196       }
 197       InAtomicBlock = false;
 198       Str = Str.drop_front();
 199       continue;
 200     }
 201
 202     // It's a real token, get the bytes and emit them
 203     ErrorOccurred |= byteArrayFromString(ByteArray, Str, SM, HexBytes);
 204
 205     if (!ByteArray.first.empty())
 206       ErrorOccurred |=
 207           PrintInsts(*DisAsm, ByteArray, SM, Streamer, InAtomicBlock, STI);
 208   }
 209
 210   if (InAtomicBlock) {
 211     SM.PrintMessage(SMLoc::getFromPointer(Str.data()), SourceMgr::DK_Error,
 212                     "unclosed atomic block");
 213     ErrorOccurred = true;
 214   }
 215
 216   return ErrorOccurred;
 217 }