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/Triple.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/MCRegisterInfo.h"
  21 #include "llvm/MC/MCStreamer.h"
  22 #include "llvm/MC/MCSubtargetInfo.h"
  23 #include "llvm/Support/MemoryBuffer.h"
  24 #include "llvm/Support/SourceMgr.h"
  25 #include "llvm/Support/TargetRegistry.h"
  26 #include "llvm/Support/raw_ostream.h"
  27
  28 using namespace llvm;
  29
  30 typedef std::pair<std::vector<unsigned char>, std::vector<const char *>>
  31     ByteArrayTy;
  32
  33 static bool PrintInsts(const MCDisassembler &DisAsm,
  34                        const ByteArrayTy &Bytes,
  35                        SourceMgr &SM, raw_ostream &Out,
  36                        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,
  49                               /*REMOVE*/ nulls(), nulls());
  50     switch (S) {
  51     case MCDisassembler::Fail:
  52       SM.PrintMessage(SMLoc::getFromPointer(Bytes.second[Index]),
  53                       SourceMgr::DK_Warning,
  54                       "invalid instruction encoding");
  55       // Don't try to resynchronise the stream in a block
  56       if (InAtomicBlock)
  57         return true;
  58
  59       if (Size == 0)
  60         Size = 1; // skip illegible bytes
  61
  62       break;
  63
  64     case MCDisassembler::SoftFail:
  65       SM.PrintMessage(SMLoc::getFromPointer(Bytes.second[Index]),
  66                       SourceMgr::DK_Warning,
  67                       "potentially undefined instruction encoding");
  68       LLVM_FALLTHROUGH;
  69
  70     case MCDisassembler::Success:
  71       Streamer.EmitInstruction(Inst, STI);
  72       break;
  73     }
  74   }
  75
  76   return false;
  77 }
  78
  79 static bool SkipToToken(StringRef &Str) {
  80   for (;;) {
  81     if (Str.empty())
  82       return false;
  83
  84     // Strip horizontal whitespace and commas.
  85     if (size_t Pos = Str.find_first_not_of(" \t\r\n,")) {
  86       Str = Str.substr(Pos);
  87       continue;
  88     }
  89
  90     // If this is the start of a comment, remove the rest of the line.
  91     if (Str[0] == '#') {
  92         Str = Str.substr(Str.find_first_of('\n'));
  93       continue;
  94     }
  95     return true;
  96   }
  97 }
  98
  99
 100 static bool ByteArrayFromString(ByteArrayTy &ByteArray,
 101                                 StringRef &Str,
 102                                 SourceMgr &SM) {
 103   while (SkipToToken(Str)) {
 104     // Handled by higher level
 105     if (Str[0] == '[' || Str[0] == ']')
 106       return false;
 107
 108     // Get the current token.
 109     size_t Next = Str.find_first_of(" \t\n\r,#[]");
 110     StringRef Value = Str.substr(0, Next);
 111
 112     // Convert to a byte and add to the byte vector.
 113     unsigned ByteVal;
 114     if (Value.getAsInteger(0, ByteVal) || ByteVal > 255) {
 115       // If we have an error, print it and skip to the end of line.
 116       SM.PrintMessage(SMLoc::getFromPointer(Value.data()), SourceMgr::DK_Error,
 117                       "invalid input token");
 118       Str = Str.substr(Str.find('\n'));
 119       ByteArray.first.clear();
 120       ByteArray.second.clear();
 121       continue;
 122     }
 123
 124     ByteArray.first.push_back(ByteVal);
 125     ByteArray.second.push_back(Value.data());
 126     Str = Str.substr(Next);
 127   }
 128
 129   return false;
 130 }
 131
 132 int Disassembler::disassemble(const Target &T,
 133                               const std::string &Triple,
 134                               MCSubtargetInfo &STI,
 135                               MCStreamer &Streamer,
 136                               MemoryBuffer &Buffer,
 137                               SourceMgr &SM,
 138                               raw_ostream &Out) {
 139
 140   std::unique_ptr<const MCRegisterInfo> MRI(T.createMCRegInfo(Triple));
 141   if (!MRI) {
 142     errs() << "error: no register info for target " << Triple << "\n";
 143     return -1;
 144   }
 145
 146   std::unique_ptr<const MCAsmInfo> MAI(T.createMCAsmInfo(*MRI, Triple));
 147   if (!MAI) {
 148     errs() << "error: no assembly info for target " << Triple << "\n";
 149     return -1;
 150   }
 151
 152   // Set up the MCContext for creating symbols and MCExpr's.
 153   MCContext Ctx(MAI.get(), MRI.get(), nullptr);
 154
 155   std::unique_ptr<const MCDisassembler> DisAsm(
 156     T.createMCDisassembler(STI, Ctx));
 157   if (!DisAsm) {
 158     errs() << "error: no disassembler for target " << Triple << "\n";
 159     return -1;
 160   }
 161
 162   // Set up initial section manually here
 163   Streamer.InitSections(false);
 164
 165   bool ErrorOccurred = false;
 166
 167   // Convert the input to a vector for disassembly.
 168   ByteArrayTy ByteArray;
 169   StringRef Str = Buffer.getBuffer();
 170   bool InAtomicBlock = false;
 171
 172   while (SkipToToken(Str)) {
 173     ByteArray.first.clear();
 174     ByteArray.second.clear();
 175
 176     if (Str[0] == '[') {
 177       if (InAtomicBlock) {
 178         SM.PrintMessage(SMLoc::getFromPointer(Str.data()), SourceMgr::DK_Error,
 179                         "nested atomic blocks make no sense");
 180         ErrorOccurred = true;
 181       }
 182       InAtomicBlock = true;
 183       Str = Str.drop_front();
 184       continue;
 185     } else if (Str[0] == ']') {
 186       if (!InAtomicBlock) {
 187         SM.PrintMessage(SMLoc::getFromPointer(Str.data()), SourceMgr::DK_Error,
 188                         "attempt to close atomic block without opening");
 189         ErrorOccurred = true;
 190       }
 191       InAtomicBlock = false;
 192       Str = Str.drop_front();
 193       continue;
 194     }
 195
 196     // It's a real token, get the bytes and emit them
 197     ErrorOccurred |= ByteArrayFromString(ByteArray, Str, SM);
 198
 199     if (!ByteArray.first.empty())
 200       ErrorOccurred |= PrintInsts(*DisAsm, ByteArray, SM, Out, Streamer,
 201                                   InAtomicBlock, STI);
 202   }
 203
 204   if (InAtomicBlock) {
 205     SM.PrintMessage(SMLoc::getFromPointer(Str.data()), SourceMgr::DK_Error,
 206                     "unclosed atomic block");
 207     ErrorOccurred = true;
 208   }
 209
 210   return ErrorOccurred;
 211 }