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