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.h"
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
42 using namespace llvm;
43
44 static mc::RegisterMCTargetOptionsFlags MOF;
45
46 static cl::opt<std::string>
47 InputFilename(cl::Positional, cl::desc("<input file>"), cl::init("-"));
48
49 static cl::opt<std::string> OutputFilename("o", cl::desc("Output filename"),
50 cl::value_desc("filename"),
51 cl::init("-"));
52
53 static cl::opt<std::string> SplitDwarfFile("split-dwarf-file",
54 cl::desc("DWO output filename"),
55 cl::value_desc("filename"));
56
57 static cl::opt<bool>
58 ShowEncoding("show-encoding", cl::desc("Show instruction encodings"));
59
60 static cl::opt<bool> RelaxELFRel(
61 "relax-relocations", cl::init(true),
62 cl::desc("Emit R_X86_64_GOTPCRELX instead of R_X86_64_GOTPCREL"));
63
64 static cl::opt<DebugCompressionType> CompressDebugSections(
65 "compress-debug-sections", cl::ValueOptional,
66 cl::init(DebugCompressionType::None),
67 cl::desc("Choose DWARF debug sections compression:"),
68 cl::values(clEnumValN(DebugCompressionType::None, "none", "No compression"),
69 clEnumValN(DebugCompressionType::Z, "zlib",
70 "Use zlib compression"),
71 clEnumValN(DebugCompressionType::GNU, "zlib-gnu",
72 "Use zlib-gnu compression (deprecated)")));
73
74 static cl::opt<bool>
75 ShowInst("show-inst", cl::desc("Show internal instruction representation"));
76
77 static cl::opt<bool>
78 ShowInstOperands("show-inst-operands",
79 cl::desc("Show instructions operands as parsed"));
80
81 static cl::opt<unsigned>
82 OutputAsmVariant("output-asm-variant",
83 cl::desc("Syntax variant to use for output printing"));
84
85 static cl::opt<bool>
86 PrintImmHex("print-imm-hex", cl::init(false),
87 cl::desc("Prefer hex format for immediate values"));
88
89 static cl::list<std::string>
90 DefineSymbol("defsym", cl::desc("Defines a symbol to be an integer constant"));
91
92 static cl::opt<bool>
93 PreserveComments("preserve-comments",
94 cl::desc("Preserve Comments in outputted assembly"));
95
96 enum OutputFileType {
97 OFT_Null,
98 OFT_AssemblyFile,
99 OFT_ObjectFile
100 };
101 static cl::opt<OutputFileType>
102 FileType("filetype", cl::init(OFT_AssemblyFile),
103 cl::desc("Choose an output file type:"),
104 cl::values(
105 clEnumValN(OFT_AssemblyFile, "asm",
106 "Emit an assembly ('.s') file"),
107 clEnumValN(OFT_Null, "null",
108 "Don't emit anything (for timing purposes)"),
109 clEnumValN(OFT_ObjectFile, "obj",
110 "Emit a native object ('.o') file")));
111
112 static cl::list<std::string>
113 IncludeDirs("I", cl::desc("Directory of include files"),
114 cl::value_desc("directory"), cl::Prefix);
115
116 static cl::opt<std::string>
117 ArchName("arch", cl::desc("Target arch to assemble for, "
118 "see -version for available targets"));
119
120 static cl::opt<std::string>
121 TripleName("triple", cl::desc("Target triple to assemble for, "
122 "see -version for available targets"));
123
124 static cl::opt<std::string>
125 MCPU("mcpu",
126 cl::desc("Target a specific cpu type (-mcpu=help for details)"),
127 cl::value_desc("cpu-name"),
128 cl::init(""));
129
130 static cl::list<std::string>
131 MAttrs("mattr",
132 cl::CommaSeparated,
133 cl::desc("Target specific attributes (-mattr=help for details)"),
134 cl::value_desc("a1,+a2,-a3,..."));
135
136 static cl::opt<bool> PIC("position-independent",
137 cl::desc("Position independent"), cl::init(false));
138
139 static cl::opt<bool>
140 LargeCodeModel("large-code-model",
141 cl::desc("Create cfi directives that assume the code might "
142 "be more than 2gb away"));
143
144 static cl::opt<bool>
145 NoInitialTextSection("n", cl::desc("Don't assume assembly file starts "
146 "in the text section"));
147
148 static cl::opt<bool>
149 GenDwarfForAssembly("g", cl::desc("Generate dwarf debugging info for assembly "
150 "source files"));
151
152 static cl::opt<std::string>
153 DebugCompilationDir("fdebug-compilation-dir",
154 cl::desc("Specifies the debug info's compilation dir"));
155
156 static cl::list<std::string>
157 DebugPrefixMap("fdebug-prefix-map",
158 cl::desc("Map file source paths in debug info"),
159 cl::value_desc("= separated key-value pairs"));
160
161 static cl::opt<std::string>
162 MainFileName("main-file-name",
163 cl::desc("Specifies the name we should consider the input file"));
164
165 static cl::opt<bool> SaveTempLabels("save-temp-labels",
166 cl::desc("Don't discard temporary labels"));
167
168 static cl::opt<bool> LexMasmIntegers(
169 "masm-integers",
170 cl::desc("Enable binary and hex masm integers (0b110 and 0ABCh)"));
171
172 static cl::opt<bool> LexMasmHexFloats(
173 "masm-hexfloats",
174 cl::desc("Enable MASM-style hex float initializers (3F800000r)"));
175
176 static cl::opt<bool> LexMotorolaIntegers(
177 "motorola-integers",
178 cl::desc("Enable binary and hex Motorola integers (%110 and $ABC)"));
179
180 static cl::opt<bool> NoExecStack("no-exec-stack",
181 cl::desc("File doesn't need an exec stack"));
182
183 enum ActionType {
184 AC_AsLex,
185 AC_Assemble,
186 AC_Disassemble,
187 AC_MDisassemble,
188 };
189
190 static cl::opt<ActionType>
191 Action(cl::desc("Action to perform:"),
192 cl::init(AC_Assemble),
193 cl::values(clEnumValN(AC_AsLex, "as-lex",
194 "Lex tokens from a .s file"),
195 clEnumValN(AC_Assemble, "assemble",
196 "Assemble a .s file (default)"),
197 clEnumValN(AC_Disassemble, "disassemble",
198 "Disassemble strings of hex bytes"),
199 clEnumValN(AC_MDisassemble, "mdis",
200 "Marked up disassembly of strings of hex bytes")));
201
GetTarget(const char * ProgName)202 static const Target *GetTarget(const char *ProgName) {
203 // Figure out the target triple.
204 if (TripleName.empty())
205 TripleName = sys::getDefaultTargetTriple();
206 Triple TheTriple(Triple::normalize(TripleName));
207
208 // Get the target specific parser.
209 std::string Error;
210 const Target *TheTarget = TargetRegistry::lookupTarget(ArchName, TheTriple,
211 Error);
212 if (!TheTarget) {
213 WithColor::error(errs(), ProgName) << Error;
214 return nullptr;
215 }
216
217 // Update the triple name and return the found target.
218 TripleName = TheTriple.getTriple();
219 return TheTarget;
220 }
221
GetOutputStream(StringRef Path,sys::fs::OpenFlags Flags)222 static std::unique_ptr<ToolOutputFile> GetOutputStream(StringRef Path,
223 sys::fs::OpenFlags Flags) {
224 std::error_code EC;
225 auto Out = std::make_unique<ToolOutputFile>(Path, EC, Flags);
226 if (EC) {
227 WithColor::error() << EC.message() << '\n';
228 return nullptr;
229 }
230
231 return Out;
232 }
233
234 static std::string DwarfDebugFlags;
setDwarfDebugFlags(int argc,char ** argv)235 static void setDwarfDebugFlags(int argc, char **argv) {
236 if (!getenv("RC_DEBUG_OPTIONS"))
237 return;
238 for (int i = 0; i < argc; i++) {
239 DwarfDebugFlags += argv[i];
240 if (i + 1 < argc)
241 DwarfDebugFlags += " ";
242 }
243 }
244
245 static std::string DwarfDebugProducer;
setDwarfDebugProducer()246 static void setDwarfDebugProducer() {
247 if(!getenv("DEBUG_PRODUCER"))
248 return;
249 DwarfDebugProducer += getenv("DEBUG_PRODUCER");
250 }
251
AsLexInput(SourceMgr & SrcMgr,MCAsmInfo & MAI,raw_ostream & OS)252 static int AsLexInput(SourceMgr &SrcMgr, MCAsmInfo &MAI,
253 raw_ostream &OS) {
254
255 AsmLexer Lexer(MAI);
256 Lexer.setBuffer(SrcMgr.getMemoryBuffer(SrcMgr.getMainFileID())->getBuffer());
257
258 bool Error = false;
259 while (Lexer.Lex().isNot(AsmToken::Eof)) {
260 Lexer.getTok().dump(OS);
261 OS << "\n";
262 if (Lexer.getTok().getKind() == AsmToken::Error)
263 Error = true;
264 }
265
266 return Error;
267 }
268
fillCommandLineSymbols(MCAsmParser & Parser)269 static int fillCommandLineSymbols(MCAsmParser &Parser) {
270 for (auto &I: DefineSymbol) {
271 auto Pair = StringRef(I).split('=');
272 auto Sym = Pair.first;
273 auto Val = Pair.second;
274
275 if (Sym.empty() || Val.empty()) {
276 WithColor::error() << "defsym must be of the form: sym=value: " << I
277 << "\n";
278 return 1;
279 }
280 int64_t Value;
281 if (Val.getAsInteger(0, Value)) {
282 WithColor::error() << "value is not an integer: " << Val << "\n";
283 return 1;
284 }
285 Parser.getContext().setSymbolValue(Parser.getStreamer(), Sym, Value);
286 }
287 return 0;
288 }
289
AssembleInput(const char * ProgName,const Target * TheTarget,SourceMgr & SrcMgr,MCContext & Ctx,MCStreamer & Str,MCAsmInfo & MAI,MCSubtargetInfo & STI,MCInstrInfo & MCII,MCTargetOptions const & MCOptions)290 static int AssembleInput(const char *ProgName, const Target *TheTarget,
291 SourceMgr &SrcMgr, MCContext &Ctx, MCStreamer &Str,
292 MCAsmInfo &MAI, MCSubtargetInfo &STI,
293 MCInstrInfo &MCII, MCTargetOptions const &MCOptions) {
294 std::unique_ptr<MCAsmParser> Parser(
295 createMCAsmParser(SrcMgr, Ctx, Str, MAI));
296 std::unique_ptr<MCTargetAsmParser> TAP(
297 TheTarget->createMCAsmParser(STI, *Parser, MCII, MCOptions));
298
299 if (!TAP) {
300 WithColor::error(errs(), ProgName)
301 << "this target does not support assembly parsing.\n";
302 return 1;
303 }
304
305 int SymbolResult = fillCommandLineSymbols(*Parser);
306 if(SymbolResult)
307 return SymbolResult;
308 Parser->setShowParsedOperands(ShowInstOperands);
309 Parser->setTargetParser(*TAP);
310 Parser->getLexer().setLexMasmIntegers(LexMasmIntegers);
311 Parser->getLexer().setLexMasmHexFloats(LexMasmHexFloats);
312 Parser->getLexer().setLexMotorolaIntegers(LexMotorolaIntegers);
313
314 int Res = Parser->Run(NoInitialTextSection);
315
316 return Res;
317 }
318
main(int argc,char ** argv)319 int main(int argc, char **argv) {
320 InitLLVM X(argc, argv);
321
322 // Initialize targets and assembly printers/parsers.
323 llvm::InitializeAllTargetInfos();
324 llvm::InitializeAllTargetMCs();
325 llvm::InitializeAllAsmParsers();
326 llvm::InitializeAllDisassemblers();
327
328 // Register the target printer for --version.
329 cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
330
331 cl::ParseCommandLineOptions(argc, argv, "llvm machine code playground\n");
332 const MCTargetOptions MCOptions = mc::InitMCTargetOptionsFromFlags();
333 setDwarfDebugFlags(argc, argv);
334
335 setDwarfDebugProducer();
336
337 const char *ProgName = argv[0];
338 const Target *TheTarget = GetTarget(ProgName);
339 if (!TheTarget)
340 return 1;
341 // Now that GetTarget() has (potentially) replaced TripleName, it's safe to
342 // construct the Triple object.
343 Triple TheTriple(TripleName);
344
345 ErrorOr<std::unique_ptr<MemoryBuffer>> BufferPtr =
346 MemoryBuffer::getFileOrSTDIN(InputFilename, /*IsText=*/true);
347 if (std::error_code EC = BufferPtr.getError()) {
348 WithColor::error(errs(), ProgName)
349 << InputFilename << ": " << EC.message() << '\n';
350 return 1;
351 }
352 MemoryBuffer *Buffer = BufferPtr->get();
353
354 SourceMgr SrcMgr;
355
356 // Tell SrcMgr about this buffer, which is what the parser will pick up.
357 SrcMgr.AddNewSourceBuffer(std::move(*BufferPtr), SMLoc());
358
359 // Record the location of the include directories so that the lexer can find
360 // it later.
361 SrcMgr.setIncludeDirs(IncludeDirs);
362
363 std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(TripleName));
364 assert(MRI && "Unable to create target register info!");
365
366 std::unique_ptr<MCAsmInfo> MAI(
367 TheTarget->createMCAsmInfo(*MRI, TripleName, MCOptions));
368 assert(MAI && "Unable to create target asm info!");
369
370 MAI->setRelaxELFRelocations(RelaxELFRel);
371
372 if (CompressDebugSections != DebugCompressionType::None) {
373 if (!zlib::isAvailable()) {
374 WithColor::error(errs(), ProgName)
375 << "build tools with zlib to enable -compress-debug-sections";
376 return 1;
377 }
378 MAI->setCompressDebugSections(CompressDebugSections);
379 }
380 MAI->setPreserveAsmComments(PreserveComments);
381
382 // Package up features to be passed to target/subtarget
383 std::string FeaturesStr;
384 if (MAttrs.size()) {
385 SubtargetFeatures Features;
386 for (unsigned i = 0; i != MAttrs.size(); ++i)
387 Features.AddFeature(MAttrs[i]);
388 FeaturesStr = Features.getString();
389 }
390
391 std::unique_ptr<MCSubtargetInfo> STI(
392 TheTarget->createMCSubtargetInfo(TripleName, MCPU, FeaturesStr));
393 assert(STI && "Unable to create subtarget info!");
394
395 // FIXME: This is not pretty. MCContext has a ptr to MCObjectFileInfo and
396 // MCObjectFileInfo needs a MCContext reference in order to initialize itself.
397 MCContext Ctx(TheTriple, MAI.get(), MRI.get(), STI.get(), &SrcMgr,
398 &MCOptions);
399 std::unique_ptr<MCObjectFileInfo> MOFI(
400 TheTarget->createMCObjectFileInfo(Ctx, PIC, LargeCodeModel));
401 Ctx.setObjectFileInfo(MOFI.get());
402
403 if (SaveTempLabels)
404 Ctx.setAllowTemporaryLabels(false);
405
406 Ctx.setGenDwarfForAssembly(GenDwarfForAssembly);
407 // Default to 4 for dwarf version.
408 unsigned DwarfVersion = MCOptions.DwarfVersion ? MCOptions.DwarfVersion : 4;
409 if (DwarfVersion < 2 || DwarfVersion > 5) {
410 errs() << ProgName << ": Dwarf version " << DwarfVersion
411 << " is not supported." << '\n';
412 return 1;
413 }
414 Ctx.setDwarfVersion(DwarfVersion);
415 if (MCOptions.Dwarf64) {
416 // The 64-bit DWARF format was introduced in DWARFv3.
417 if (DwarfVersion < 3) {
418 errs() << ProgName
419 << ": the 64-bit DWARF format is not supported for DWARF versions "
420 "prior to 3\n";
421 return 1;
422 }
423 // 32-bit targets don't support DWARF64, which requires 64-bit relocations.
424 if (MAI->getCodePointerSize() < 8) {
425 errs() << ProgName
426 << ": the 64-bit DWARF format is only supported for 64-bit "
427 "targets\n";
428 return 1;
429 }
430 // If needsDwarfSectionOffsetDirective is true, we would eventually call
431 // MCStreamer::emitSymbolValue() with IsSectionRelative = true, but that
432 // is supported only for 4-byte long references.
433 if (MAI->needsDwarfSectionOffsetDirective()) {
434 errs() << ProgName << ": the 64-bit DWARF format is not supported for "
435 << TheTriple.normalize() << "\n";
436 return 1;
437 }
438 Ctx.setDwarfFormat(dwarf::DWARF64);
439 }
440 if (!DwarfDebugFlags.empty())
441 Ctx.setDwarfDebugFlags(StringRef(DwarfDebugFlags));
442 if (!DwarfDebugProducer.empty())
443 Ctx.setDwarfDebugProducer(StringRef(DwarfDebugProducer));
444 if (!DebugCompilationDir.empty())
445 Ctx.setCompilationDir(DebugCompilationDir);
446 else {
447 // If no compilation dir is set, try to use the current directory.
448 SmallString<128> CWD;
449 if (!sys::fs::current_path(CWD))
450 Ctx.setCompilationDir(CWD);
451 }
452 for (const auto &Arg : DebugPrefixMap) {
453 const auto &KV = StringRef(Arg).split('=');
454 Ctx.addDebugPrefixMapEntry(std::string(KV.first), std::string(KV.second));
455 }
456 if (!MainFileName.empty())
457 Ctx.setMainFileName(MainFileName);
458 if (GenDwarfForAssembly)
459 Ctx.setGenDwarfRootFile(InputFilename, Buffer->getBuffer());
460
461 sys::fs::OpenFlags Flags = (FileType == OFT_AssemblyFile)
462 ? sys::fs::OF_TextWithCRLF
463 : sys::fs::OF_None;
464 std::unique_ptr<ToolOutputFile> Out = GetOutputStream(OutputFilename, Flags);
465 if (!Out)
466 return 1;
467
468 std::unique_ptr<ToolOutputFile> DwoOut;
469 if (!SplitDwarfFile.empty()) {
470 if (FileType != OFT_ObjectFile) {
471 WithColor::error() << "dwo output only supported with object files\n";
472 return 1;
473 }
474 DwoOut = GetOutputStream(SplitDwarfFile, sys::fs::OF_None);
475 if (!DwoOut)
476 return 1;
477 }
478
479 std::unique_ptr<buffer_ostream> BOS;
480 raw_pwrite_stream *OS = &Out->os();
481 std::unique_ptr<MCStreamer> Str;
482
483 std::unique_ptr<MCInstrInfo> MCII(TheTarget->createMCInstrInfo());
484 assert(MCII && "Unable to create instruction info!");
485
486 MCInstPrinter *IP = nullptr;
487 if (FileType == OFT_AssemblyFile) {
488 IP = TheTarget->createMCInstPrinter(Triple(TripleName), OutputAsmVariant,
489 *MAI, *MCII, *MRI);
490
491 if (!IP) {
492 WithColor::error()
493 << "unable to create instruction printer for target triple '"
494 << TheTriple.normalize() << "' with assembly variant "
495 << OutputAsmVariant << ".\n";
496 return 1;
497 }
498
499 // Set the display preference for hex vs. decimal immediates.
500 IP->setPrintImmHex(PrintImmHex);
501
502 // Set up the AsmStreamer.
503 std::unique_ptr<MCCodeEmitter> CE;
504 if (ShowEncoding)
505 CE.reset(TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
506
507 std::unique_ptr<MCAsmBackend> MAB(
508 TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
509 auto FOut = std::make_unique<formatted_raw_ostream>(*OS);
510 Str.reset(
511 TheTarget->createAsmStreamer(Ctx, std::move(FOut), /*asmverbose*/ true,
512 /*useDwarfDirectory*/ true, IP,
513 std::move(CE), std::move(MAB), ShowInst));
514
515 } else if (FileType == OFT_Null) {
516 Str.reset(TheTarget->createNullStreamer(Ctx));
517 } else {
518 assert(FileType == OFT_ObjectFile && "Invalid file type!");
519
520 if (!Out->os().supportsSeeking()) {
521 BOS = std::make_unique<buffer_ostream>(Out->os());
522 OS = BOS.get();
523 }
524
525 MCCodeEmitter *CE = TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx);
526 MCAsmBackend *MAB = TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions);
527 Str.reset(TheTarget->createMCObjectStreamer(
528 TheTriple, Ctx, std::unique_ptr<MCAsmBackend>(MAB),
529 DwoOut ? MAB->createDwoObjectWriter(*OS, DwoOut->os())
530 : MAB->createObjectWriter(*OS),
531 std::unique_ptr<MCCodeEmitter>(CE), *STI, MCOptions.MCRelaxAll,
532 MCOptions.MCIncrementalLinkerCompatible,
533 /*DWARFMustBeAtTheEnd*/ false));
534 if (NoExecStack)
535 Str->InitSections(true);
536 }
537
538 // Use Assembler information for parsing.
539 Str->setUseAssemblerInfoForParsing(true);
540
541 int Res = 1;
542 bool disassemble = false;
543 switch (Action) {
544 case AC_AsLex:
545 Res = AsLexInput(SrcMgr, *MAI, Out->os());
546 break;
547 case AC_Assemble:
548 Res = AssembleInput(ProgName, TheTarget, SrcMgr, Ctx, *Str, *MAI, *STI,
549 *MCII, MCOptions);
550 break;
551 case AC_MDisassemble:
552 assert(IP && "Expected assembly output");
553 IP->setUseMarkup(true);
554 disassemble = true;
555 break;
556 case AC_Disassemble:
557 disassemble = true;
558 break;
559 }
560 if (disassemble)
561 Res = Disassembler::disassemble(*TheTarget, TripleName, *STI, *Str, *Buffer,
562 SrcMgr, Ctx, Out->os(), MCOptions);
563
564 // Keep output if no errors.
565 if (Res == 0) {
566 Out->keep();
567 if (DwoOut)
568 DwoOut->keep();
569 }
570 return Res;
571 }
572