llvm-mc.cpp revision 360784 
1//===-- llvm-mc.cpp - Machine Code Hacking Driver ---------------*- C++ -*-===//
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 utility is a simple driver that allows command line hacking on machine
10// code.
11//
12//===----------------------------------------------------------------------===//
13
14#include "Disassembler.h"
15#include "llvm/MC/MCAsmBackend.h"
16#include "llvm/MC/MCAsmInfo.h"
17#include "llvm/MC/MCCodeEmitter.h"
18#include "llvm/MC/MCContext.h"
19#include "llvm/MC/MCInstPrinter.h"
20#include "llvm/MC/MCInstrInfo.h"
21#include "llvm/MC/MCObjectFileInfo.h"
22#include "llvm/MC/MCObjectWriter.h"
23#include "llvm/MC/MCParser/AsmLexer.h"
24#include "llvm/MC/MCParser/MCTargetAsmParser.h"
25#include "llvm/MC/MCRegisterInfo.h"
26#include "llvm/MC/MCStreamer.h"
27#include "llvm/MC/MCSubtargetInfo.h"
28#include "llvm/MC/MCTargetOptionsCommandFlags.inc"
29#include "llvm/Support/CommandLine.h"
30#include "llvm/Support/Compression.h"
31#include "llvm/Support/FileUtilities.h"
32#include "llvm/Support/FormattedStream.h"
33#include "llvm/Support/Host.h"
34#include "llvm/Support/InitLLVM.h"
35#include "llvm/Support/MemoryBuffer.h"
36#include "llvm/Support/SourceMgr.h"
37#include "llvm/Support/TargetRegistry.h"
38#include "llvm/Support/TargetSelect.h"
39#include "llvm/Support/ToolOutputFile.h"
40#include "llvm/Support/WithColor.h"
41
42using namespace llvm;
43
44static cl::opt<std::string>
45InputFilename(cl::Positional, cl::desc("<input file>"), cl::init("-"));
46
47static cl::opt<std::string> OutputFilename("o", cl::desc("Output filename"),
48                                           cl::value_desc("filename"),
49                                           cl::init("-"));
50
51static cl::opt<std::string> SplitDwarfFile("split-dwarf-file",
52                                           cl::desc("DWO output filename"),
53                                           cl::value_desc("filename"));
54
55static cl::opt<bool>
56ShowEncoding("show-encoding", cl::desc("Show instruction encodings"));
57
58static cl::opt<bool> RelaxELFRel(
59    "relax-relocations", cl::init(true),
60    cl::desc("Emit R_X86_64_GOTPCRELX instead of R_X86_64_GOTPCREL"));
61
62static cl::opt<DebugCompressionType> CompressDebugSections(
63    "compress-debug-sections", cl::ValueOptional,
64    cl::init(DebugCompressionType::None),
65    cl::desc("Choose DWARF debug sections compression:"),
66    cl::values(clEnumValN(DebugCompressionType::None, "none", "No compression"),
67               clEnumValN(DebugCompressionType::Z, "zlib",
68                          "Use zlib compression"),
69               clEnumValN(DebugCompressionType::GNU, "zlib-gnu",
70                          "Use zlib-gnu compression (deprecated)")));
71
72static cl::opt<bool>
73ShowInst("show-inst", cl::desc("Show internal instruction representation"));
74
75static cl::opt<bool>
76ShowInstOperands("show-inst-operands",
77                 cl::desc("Show instructions operands as parsed"));
78
79static cl::opt<unsigned>
80OutputAsmVariant("output-asm-variant",
81                 cl::desc("Syntax variant to use for output printing"));
82
83static cl::opt<bool>
84PrintImmHex("print-imm-hex", cl::init(false),
85            cl::desc("Prefer hex format for immediate values"));
86
87static cl::list<std::string>
88DefineSymbol("defsym", cl::desc("Defines a symbol to be an integer constant"));
89
90static cl::opt<bool>
91    PreserveComments("preserve-comments",
92                     cl::desc("Preserve Comments in outputted assembly"));
93
94enum OutputFileType {
95  OFT_Null,
96  OFT_AssemblyFile,
97  OFT_ObjectFile
98};
99static cl::opt<OutputFileType>
100FileType("filetype", cl::init(OFT_AssemblyFile),
101  cl::desc("Choose an output file type:"),
102  cl::values(
103       clEnumValN(OFT_AssemblyFile, "asm",
104                  "Emit an assembly ('.s') file"),
105       clEnumValN(OFT_Null, "null",
106                  "Don't emit anything (for timing purposes)"),
107       clEnumValN(OFT_ObjectFile, "obj",
108                  "Emit a native object ('.o') file")));
109
110static cl::list<std::string>
111IncludeDirs("I", cl::desc("Directory of include files"),
112            cl::value_desc("directory"), cl::Prefix);
113
114static cl::opt<std::string>
115ArchName("arch", cl::desc("Target arch to assemble for, "
116                          "see -version for available targets"));
117
118static cl::opt<std::string>
119TripleName("triple", cl::desc("Target triple to assemble for, "
120                              "see -version for available targets"));
121
122static cl::opt<std::string>
123MCPU("mcpu",
124     cl::desc("Target a specific cpu type (-mcpu=help for details)"),
125     cl::value_desc("cpu-name"),
126     cl::init(""));
127
128static cl::list<std::string>
129MAttrs("mattr",
130  cl::CommaSeparated,
131  cl::desc("Target specific attributes (-mattr=help for details)"),
132  cl::value_desc("a1,+a2,-a3,..."));
133
134static cl::opt<bool> PIC("position-independent",
135                         cl::desc("Position independent"), cl::init(false));
136
137static cl::opt<bool>
138    LargeCodeModel("large-code-model",
139                   cl::desc("Create cfi directives that assume the code might "
140                            "be more than 2gb away"));
141
142static cl::opt<bool>
143NoInitialTextSection("n", cl::desc("Don't assume assembly file starts "
144                                   "in the text section"));
145
146static cl::opt<bool>
147GenDwarfForAssembly("g", cl::desc("Generate dwarf debugging info for assembly "
148                                  "source files"));
149
150static cl::opt<std::string>
151DebugCompilationDir("fdebug-compilation-dir",
152                    cl::desc("Specifies the debug info's compilation dir"));
153
154static cl::list<std::string>
155DebugPrefixMap("fdebug-prefix-map",
156               cl::desc("Map file source paths in debug info"),
157               cl::value_desc("= separated key-value pairs"));
158
159static cl::opt<std::string>
160MainFileName("main-file-name",
161             cl::desc("Specifies the name we should consider the input file"));
162
163static cl::opt<bool> SaveTempLabels("save-temp-labels",
164                                    cl::desc("Don't discard temporary labels"));
165
166static cl::opt<bool> LexMasmIntegers(
167    "masm-integers",
168    cl::desc("Enable binary and hex masm integers (0b110 and 0ABCh)"));
169
170static cl::opt<bool> NoExecStack("no-exec-stack",
171                                 cl::desc("File doesn't need an exec stack"));
172
173enum ActionType {
174  AC_AsLex,
175  AC_Assemble,
176  AC_Disassemble,
177  AC_MDisassemble,
178};
179
180static cl::opt<ActionType>
181Action(cl::desc("Action to perform:"),
182       cl::init(AC_Assemble),
183       cl::values(clEnumValN(AC_AsLex, "as-lex",
184                             "Lex tokens from a .s file"),
185                  clEnumValN(AC_Assemble, "assemble",
186                             "Assemble a .s file (default)"),
187                  clEnumValN(AC_Disassemble, "disassemble",
188                             "Disassemble strings of hex bytes"),
189                  clEnumValN(AC_MDisassemble, "mdis",
190                             "Marked up disassembly of strings of hex bytes")));
191
192static const Target *GetTarget(const char *ProgName) {
193  // Figure out the target triple.
194  if (TripleName.empty())
195    TripleName = sys::getDefaultTargetTriple();
196  Triple TheTriple(Triple::normalize(TripleName));
197
198  // Get the target specific parser.
199  std::string Error;
200  const Target *TheTarget = TargetRegistry::lookupTarget(ArchName, TheTriple,
201                                                         Error);
202  if (!TheTarget) {
203    WithColor::error(errs(), ProgName) << Error;
204    return nullptr;
205  }
206
207  // Update the triple name and return the found target.
208  TripleName = TheTriple.getTriple();
209  return TheTarget;
210}
211
212static std::unique_ptr<ToolOutputFile> GetOutputStream(StringRef Path,
213    sys::fs::OpenFlags Flags) {
214  std::error_code EC;
215  auto Out = std::make_unique<ToolOutputFile>(Path, EC, Flags);
216  if (EC) {
217    WithColor::error() << EC.message() << '\n';
218    return nullptr;
219  }
220
221  return Out;
222}
223
224static std::string DwarfDebugFlags;
225static void setDwarfDebugFlags(int argc, char **argv) {
226  if (!getenv("RC_DEBUG_OPTIONS"))
227    return;
228  for (int i = 0; i < argc; i++) {
229    DwarfDebugFlags += argv[i];
230    if (i + 1 < argc)
231      DwarfDebugFlags += " ";
232  }
233}
234
235static std::string DwarfDebugProducer;
236static void setDwarfDebugProducer() {
237  if(!getenv("DEBUG_PRODUCER"))
238    return;
239  DwarfDebugProducer += getenv("DEBUG_PRODUCER");
240}
241
242static int AsLexInput(SourceMgr &SrcMgr, MCAsmInfo &MAI,
243                      raw_ostream &OS) {
244
245  AsmLexer Lexer(MAI);
246  Lexer.setBuffer(SrcMgr.getMemoryBuffer(SrcMgr.getMainFileID())->getBuffer());
247
248  bool Error = false;
249  while (Lexer.Lex().isNot(AsmToken::Eof)) {
250    Lexer.getTok().dump(OS);
251    OS << "\n";
252    if (Lexer.getTok().getKind() == AsmToken::Error)
253      Error = true;
254  }
255
256  return Error;
257}
258
259static int fillCommandLineSymbols(MCAsmParser &Parser) {
260  for (auto &I: DefineSymbol) {
261    auto Pair = StringRef(I).split('=');
262    auto Sym = Pair.first;
263    auto Val = Pair.second;
264
265    if (Sym.empty() || Val.empty()) {
266      WithColor::error() << "defsym must be of the form: sym=value: " << I
267                         << "\n";
268      return 1;
269    }
270    int64_t Value;
271    if (Val.getAsInteger(0, Value)) {
272      WithColor::error() << "value is not an integer: " << Val << "\n";
273      return 1;
274    }
275    Parser.getContext().setSymbolValue(Parser.getStreamer(), Sym, Value);
276  }
277  return 0;
278}
279
280static int AssembleInput(const char *ProgName, const Target *TheTarget,
281                         SourceMgr &SrcMgr, MCContext &Ctx, MCStreamer &Str,
282                         MCAsmInfo &MAI, MCSubtargetInfo &STI,
283                         MCInstrInfo &MCII, MCTargetOptions const &MCOptions) {
284  std::unique_ptr<MCAsmParser> Parser(
285      createMCAsmParser(SrcMgr, Ctx, Str, MAI));
286  std::unique_ptr<MCTargetAsmParser> TAP(
287      TheTarget->createMCAsmParser(STI, *Parser, MCII, MCOptions));
288
289  if (!TAP) {
290    WithColor::error(errs(), ProgName)
291        << "this target does not support assembly parsing.\n";
292    return 1;
293  }
294
295  int SymbolResult = fillCommandLineSymbols(*Parser);
296  if(SymbolResult)
297    return SymbolResult;
298  Parser->setShowParsedOperands(ShowInstOperands);
299  Parser->setTargetParser(*TAP);
300  Parser->getLexer().setLexMasmIntegers(LexMasmIntegers);
301
302  int Res = Parser->Run(NoInitialTextSection);
303
304  return Res;
305}
306
307int main(int argc, char **argv) {
308  InitLLVM X(argc, argv);
309
310  // Initialize targets and assembly printers/parsers.
311  llvm::InitializeAllTargetInfos();
312  llvm::InitializeAllTargetMCs();
313  llvm::InitializeAllAsmParsers();
314  llvm::InitializeAllDisassemblers();
315
316  // Register the target printer for --version.
317  cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
318
319  cl::ParseCommandLineOptions(argc, argv, "llvm machine code playground\n");
320  const MCTargetOptions MCOptions = InitMCTargetOptionsFromFlags();
321  setDwarfDebugFlags(argc, argv);
322
323  setDwarfDebugProducer();
324
325  const char *ProgName = argv[0];
326  const Target *TheTarget = GetTarget(ProgName);
327  if (!TheTarget)
328    return 1;
329  // Now that GetTarget() has (potentially) replaced TripleName, it's safe to
330  // construct the Triple object.
331  Triple TheTriple(TripleName);
332
333  ErrorOr<std::unique_ptr<MemoryBuffer>> BufferPtr =
334      MemoryBuffer::getFileOrSTDIN(InputFilename);
335  if (std::error_code EC = BufferPtr.getError()) {
336    WithColor::error(errs(), ProgName)
337        << InputFilename << ": " << EC.message() << '\n';
338    return 1;
339  }
340  MemoryBuffer *Buffer = BufferPtr->get();
341
342  SourceMgr SrcMgr;
343
344  // Tell SrcMgr about this buffer, which is what the parser will pick up.
345  SrcMgr.AddNewSourceBuffer(std::move(*BufferPtr), SMLoc());
346
347  // Record the location of the include directories so that the lexer can find
348  // it later.
349  SrcMgr.setIncludeDirs(IncludeDirs);
350
351  std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(TripleName));
352  assert(MRI && "Unable to create target register info!");
353
354  std::unique_ptr<MCAsmInfo> MAI(
355      TheTarget->createMCAsmInfo(*MRI, TripleName, MCOptions));
356  assert(MAI && "Unable to create target asm info!");
357
358  MAI->setRelaxELFRelocations(RelaxELFRel);
359
360  if (CompressDebugSections != DebugCompressionType::None) {
361    if (!zlib::isAvailable()) {
362      WithColor::error(errs(), ProgName)
363          << "build tools with zlib to enable -compress-debug-sections";
364      return 1;
365    }
366    MAI->setCompressDebugSections(CompressDebugSections);
367  }
368  MAI->setPreserveAsmComments(PreserveComments);
369
370  // FIXME: This is not pretty. MCContext has a ptr to MCObjectFileInfo and
371  // MCObjectFileInfo needs a MCContext reference in order to initialize itself.
372  MCObjectFileInfo MOFI;
373  MCContext Ctx(MAI.get(), MRI.get(), &MOFI, &SrcMgr, &MCOptions);
374  MOFI.InitMCObjectFileInfo(TheTriple, PIC, Ctx, LargeCodeModel);
375
376  if (SaveTempLabels)
377    Ctx.setAllowTemporaryLabels(false);
378
379  Ctx.setGenDwarfForAssembly(GenDwarfForAssembly);
380  // Default to 4 for dwarf version.
381  unsigned DwarfVersion = MCOptions.DwarfVersion ? MCOptions.DwarfVersion : 4;
382  if (DwarfVersion < 2 || DwarfVersion > 5) {
383    errs() << ProgName << ": Dwarf version " << DwarfVersion
384           << " is not supported." << '\n';
385    return 1;
386  }
387  Ctx.setDwarfVersion(DwarfVersion);
388  if (!DwarfDebugFlags.empty())
389    Ctx.setDwarfDebugFlags(StringRef(DwarfDebugFlags));
390  if (!DwarfDebugProducer.empty())
391    Ctx.setDwarfDebugProducer(StringRef(DwarfDebugProducer));
392  if (!DebugCompilationDir.empty())
393    Ctx.setCompilationDir(DebugCompilationDir);
394  else {
395    // If no compilation dir is set, try to use the current directory.
396    SmallString<128> CWD;
397    if (!sys::fs::current_path(CWD))
398      Ctx.setCompilationDir(CWD);
399  }
400  for (const auto &Arg : DebugPrefixMap) {
401    const auto &KV = StringRef(Arg).split('=');
402    Ctx.addDebugPrefixMapEntry(KV.first, KV.second);
403  }
404  if (!MainFileName.empty())
405    Ctx.setMainFileName(MainFileName);
406  if (GenDwarfForAssembly)
407    Ctx.setGenDwarfRootFile(InputFilename, Buffer->getBuffer());
408
409  // Package up features to be passed to target/subtarget
410  std::string FeaturesStr;
411  if (MAttrs.size()) {
412    SubtargetFeatures Features;
413    for (unsigned i = 0; i != MAttrs.size(); ++i)
414      Features.AddFeature(MAttrs[i]);
415    FeaturesStr = Features.getString();
416  }
417
418  sys::fs::OpenFlags Flags = (FileType == OFT_AssemblyFile) ? sys::fs::OF_Text
419                                                            : sys::fs::OF_None;
420  std::unique_ptr<ToolOutputFile> Out = GetOutputStream(OutputFilename, Flags);
421  if (!Out)
422    return 1;
423
424  std::unique_ptr<ToolOutputFile> DwoOut;
425  if (!SplitDwarfFile.empty()) {
426    if (FileType != OFT_ObjectFile) {
427      WithColor::error() << "dwo output only supported with object files\n";
428      return 1;
429    }
430    DwoOut = GetOutputStream(SplitDwarfFile, sys::fs::OF_None);
431    if (!DwoOut)
432      return 1;
433  }
434
435  std::unique_ptr<buffer_ostream> BOS;
436  raw_pwrite_stream *OS = &Out->os();
437  std::unique_ptr<MCStreamer> Str;
438
439  std::unique_ptr<MCInstrInfo> MCII(TheTarget->createMCInstrInfo());
440  std::unique_ptr<MCSubtargetInfo> STI(
441      TheTarget->createMCSubtargetInfo(TripleName, MCPU, FeaturesStr));
442
443  MCInstPrinter *IP = nullptr;
444  if (FileType == OFT_AssemblyFile) {
445    IP = TheTarget->createMCInstPrinter(Triple(TripleName), OutputAsmVariant,
446                                        *MAI, *MCII, *MRI);
447
448    if (!IP) {
449      WithColor::error()
450          << "unable to create instruction printer for target triple '"
451          << TheTriple.normalize() << "' with assembly variant "
452          << OutputAsmVariant << ".\n";
453      return 1;
454    }
455
456    // Set the display preference for hex vs. decimal immediates.
457    IP->setPrintImmHex(PrintImmHex);
458
459    // Set up the AsmStreamer.
460    std::unique_ptr<MCCodeEmitter> CE;
461    if (ShowEncoding)
462      CE.reset(TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
463
464    std::unique_ptr<MCAsmBackend> MAB(
465        TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
466    auto FOut = std::make_unique<formatted_raw_ostream>(*OS);
467    Str.reset(
468        TheTarget->createAsmStreamer(Ctx, std::move(FOut), /*asmverbose*/ true,
469                                     /*useDwarfDirectory*/ true, IP,
470                                     std::move(CE), std::move(MAB), ShowInst));
471
472  } else if (FileType == OFT_Null) {
473    Str.reset(TheTarget->createNullStreamer(Ctx));
474  } else {
475    assert(FileType == OFT_ObjectFile && "Invalid file type!");
476
477    // Don't waste memory on names of temp labels.
478    Ctx.setUseNamesOnTempLabels(false);
479
480    if (!Out->os().supportsSeeking()) {
481      BOS = std::make_unique<buffer_ostream>(Out->os());
482      OS = BOS.get();
483    }
484
485    MCCodeEmitter *CE = TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx);
486    MCAsmBackend *MAB = TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions);
487    Str.reset(TheTarget->createMCObjectStreamer(
488        TheTriple, Ctx, std::unique_ptr<MCAsmBackend>(MAB),
489        DwoOut ? MAB->createDwoObjectWriter(*OS, DwoOut->os())
490               : MAB->createObjectWriter(*OS),
491        std::unique_ptr<MCCodeEmitter>(CE), *STI, MCOptions.MCRelaxAll,
492        MCOptions.MCIncrementalLinkerCompatible,
493        /*DWARFMustBeAtTheEnd*/ false));
494    if (NoExecStack)
495      Str->InitSections(true);
496  }
497
498  // Use Assembler information for parsing.
499  Str->setUseAssemblerInfoForParsing(true);
500
501  int Res = 1;
502  bool disassemble = false;
503  switch (Action) {
504  case AC_AsLex:
505    Res = AsLexInput(SrcMgr, *MAI, Out->os());
506    break;
507  case AC_Assemble:
508    Res = AssembleInput(ProgName, TheTarget, SrcMgr, Ctx, *Str, *MAI, *STI,
509                        *MCII, MCOptions);
510    break;
511  case AC_MDisassemble:
512    assert(IP && "Expected assembly output");
513    IP->setUseMarkup(true);
514    disassemble = true;
515    break;
516  case AC_Disassemble:
517    disassemble = true;
518    break;
519  }
520  if (disassemble)
521    Res = Disassembler::disassemble(*TheTarget, TripleName, *STI, *Str, *Buffer,
522                                    SrcMgr, Ctx, Out->os(), MCOptions);
523
524  // Keep output if no errors.
525  if (Res == 0) {
526    Out->keep();
527    if (DwoOut)
528      DwoOut->keep();
529  }
530  return Res;
531}
532