1 //===- lib/MC/MCDwarf.cpp - MCDwarf implementation ------------------------===// 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 #include "llvm/MC/MCDwarf.h" 10 #include "llvm/ADT/ArrayRef.h" 11 #include "llvm/ADT/DenseMap.h" 12 #include "llvm/ADT/Hashing.h" 13 #include "llvm/ADT/STLExtras.h" 14 #include "llvm/ADT/SmallString.h" 15 #include "llvm/ADT/SmallVector.h" 16 #include "llvm/ADT/StringRef.h" 17 #include "llvm/ADT/Twine.h" 18 #include "llvm/BinaryFormat/Dwarf.h" 19 #include "llvm/Config/config.h" 20 #include "llvm/MC/MCAsmInfo.h" 21 #include "llvm/MC/MCContext.h" 22 #include "llvm/MC/MCExpr.h" 23 #include "llvm/MC/MCObjectFileInfo.h" 24 #include "llvm/MC/MCObjectStreamer.h" 25 #include "llvm/MC/MCRegisterInfo.h" 26 #include "llvm/MC/MCSection.h" 27 #include "llvm/MC/MCStreamer.h" 28 #include "llvm/MC/MCSymbol.h" 29 #include "llvm/Support/Casting.h" 30 #include "llvm/Support/Endian.h" 31 #include "llvm/Support/EndianStream.h" 32 #include "llvm/Support/ErrorHandling.h" 33 #include "llvm/Support/LEB128.h" 34 #include "llvm/Support/MathExtras.h" 35 #include "llvm/Support/Path.h" 36 #include "llvm/Support/SourceMgr.h" 37 #include "llvm/Support/raw_ostream.h" 38 #include <cassert> 39 #include <cstdint> 40 #include <optional> 41 #include <string> 42 #include <utility> 43 #include <vector> 44 45 using namespace llvm; 46 47 MCSymbol *mcdwarf::emitListsTableHeaderStart(MCStreamer &S) { 48 MCSymbol *Start = S.getContext().createTempSymbol("debug_list_header_start"); 49 MCSymbol *End = S.getContext().createTempSymbol("debug_list_header_end"); 50 auto DwarfFormat = S.getContext().getDwarfFormat(); 51 if (DwarfFormat == dwarf::DWARF64) { 52 S.AddComment("DWARF64 mark"); 53 S.emitInt32(dwarf::DW_LENGTH_DWARF64); 54 } 55 S.AddComment("Length"); 56 S.emitAbsoluteSymbolDiff(End, Start, 57 dwarf::getDwarfOffsetByteSize(DwarfFormat)); 58 S.emitLabel(Start); 59 S.AddComment("Version"); 60 S.emitInt16(S.getContext().getDwarfVersion()); 61 S.AddComment("Address size"); 62 S.emitInt8(S.getContext().getAsmInfo()->getCodePointerSize()); 63 S.AddComment("Segment selector size"); 64 S.emitInt8(0); 65 return End; 66 } 67 68 static inline uint64_t ScaleAddrDelta(MCContext &Context, uint64_t AddrDelta) { 69 unsigned MinInsnLength = Context.getAsmInfo()->getMinInstAlignment(); 70 if (MinInsnLength == 1) 71 return AddrDelta; 72 if (AddrDelta % MinInsnLength != 0) { 73 // TODO: report this error, but really only once. 74 ; 75 } 76 return AddrDelta / MinInsnLength; 77 } 78 79 MCDwarfLineStr::MCDwarfLineStr(MCContext &Ctx) { 80 UseRelocs = Ctx.getAsmInfo()->doesDwarfUseRelocationsAcrossSections(); 81 if (UseRelocs) { 82 MCSection *DwarfLineStrSection = 83 Ctx.getObjectFileInfo()->getDwarfLineStrSection(); 84 assert(DwarfLineStrSection && "DwarfLineStrSection must not be NULL"); 85 LineStrLabel = DwarfLineStrSection->getBeginSymbol(); 86 } 87 } 88 89 // 90 // This is called when an instruction is assembled into the specified section 91 // and if there is information from the last .loc directive that has yet to have 92 // a line entry made for it is made. 93 // 94 void MCDwarfLineEntry::make(MCStreamer *MCOS, MCSection *Section) { 95 if (!MCOS->getContext().getDwarfLocSeen()) 96 return; 97 98 // Create a symbol at in the current section for use in the line entry. 99 MCSymbol *LineSym = MCOS->getContext().createTempSymbol(); 100 // Set the value of the symbol to use for the MCDwarfLineEntry. 101 MCOS->emitLabel(LineSym); 102 103 // Get the current .loc info saved in the context. 104 const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc(); 105 106 // Create a (local) line entry with the symbol and the current .loc info. 107 MCDwarfLineEntry LineEntry(LineSym, DwarfLoc); 108 109 // clear DwarfLocSeen saying the current .loc info is now used. 110 MCOS->getContext().clearDwarfLocSeen(); 111 112 // Add the line entry to this section's entries. 113 MCOS->getContext() 114 .getMCDwarfLineTable(MCOS->getContext().getDwarfCompileUnitID()) 115 .getMCLineSections() 116 .addLineEntry(LineEntry, Section); 117 } 118 119 // 120 // This helper routine returns an expression of End - Start - IntVal . 121 // 122 static inline const MCExpr *makeEndMinusStartExpr(MCContext &Ctx, 123 const MCSymbol &Start, 124 const MCSymbol &End, 125 int IntVal) { 126 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None; 127 const MCExpr *Res = MCSymbolRefExpr::create(&End, Variant, Ctx); 128 const MCExpr *RHS = MCSymbolRefExpr::create(&Start, Variant, Ctx); 129 const MCExpr *Res1 = MCBinaryExpr::create(MCBinaryExpr::Sub, Res, RHS, Ctx); 130 const MCExpr *Res2 = MCConstantExpr::create(IntVal, Ctx); 131 const MCExpr *Res3 = MCBinaryExpr::create(MCBinaryExpr::Sub, Res1, Res2, Ctx); 132 return Res3; 133 } 134 135 // 136 // This helper routine returns an expression of Start + IntVal . 137 // 138 static inline const MCExpr * 139 makeStartPlusIntExpr(MCContext &Ctx, const MCSymbol &Start, int IntVal) { 140 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None; 141 const MCExpr *LHS = MCSymbolRefExpr::create(&Start, Variant, Ctx); 142 const MCExpr *RHS = MCConstantExpr::create(IntVal, Ctx); 143 const MCExpr *Res = MCBinaryExpr::create(MCBinaryExpr::Add, LHS, RHS, Ctx); 144 return Res; 145 } 146 147 void MCLineSection::addEndEntry(MCSymbol *EndLabel) { 148 auto *Sec = &EndLabel->getSection(); 149 // The line table may be empty, which we should skip adding an end entry. 150 // There are two cases: 151 // (1) MCAsmStreamer - emitDwarfLocDirective emits a location directive in 152 // place instead of adding a line entry if the target has 153 // usesDwarfFileAndLocDirectives. 154 // (2) MCObjectStreamer - if a function has incomplete debug info where 155 // instructions don't have DILocations, the line entries are missing. 156 auto I = MCLineDivisions.find(Sec); 157 if (I != MCLineDivisions.end()) { 158 auto &Entries = I->second; 159 auto EndEntry = Entries.back(); 160 EndEntry.setEndLabel(EndLabel); 161 Entries.push_back(EndEntry); 162 } 163 } 164 165 // 166 // This emits the Dwarf line table for the specified section from the entries 167 // in the LineSection. 168 // 169 void MCDwarfLineTable::emitOne( 170 MCStreamer *MCOS, MCSection *Section, 171 const MCLineSection::MCDwarfLineEntryCollection &LineEntries) { 172 173 unsigned FileNum, LastLine, Column, Flags, Isa, Discriminator; 174 MCSymbol *LastLabel; 175 auto init = [&]() { 176 FileNum = 1; 177 LastLine = 1; 178 Column = 0; 179 Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0; 180 Isa = 0; 181 Discriminator = 0; 182 LastLabel = nullptr; 183 }; 184 init(); 185 186 // Loop through each MCDwarfLineEntry and encode the dwarf line number table. 187 bool EndEntryEmitted = false; 188 for (const MCDwarfLineEntry &LineEntry : LineEntries) { 189 MCSymbol *Label = LineEntry.getLabel(); 190 const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo(); 191 if (LineEntry.IsEndEntry) { 192 MCOS->emitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, Label, 193 asmInfo->getCodePointerSize()); 194 init(); 195 EndEntryEmitted = true; 196 continue; 197 } 198 199 int64_t LineDelta = static_cast<int64_t>(LineEntry.getLine()) - LastLine; 200 201 if (FileNum != LineEntry.getFileNum()) { 202 FileNum = LineEntry.getFileNum(); 203 MCOS->emitInt8(dwarf::DW_LNS_set_file); 204 MCOS->emitULEB128IntValue(FileNum); 205 } 206 if (Column != LineEntry.getColumn()) { 207 Column = LineEntry.getColumn(); 208 MCOS->emitInt8(dwarf::DW_LNS_set_column); 209 MCOS->emitULEB128IntValue(Column); 210 } 211 if (Discriminator != LineEntry.getDiscriminator() && 212 MCOS->getContext().getDwarfVersion() >= 4) { 213 Discriminator = LineEntry.getDiscriminator(); 214 unsigned Size = getULEB128Size(Discriminator); 215 MCOS->emitInt8(dwarf::DW_LNS_extended_op); 216 MCOS->emitULEB128IntValue(Size + 1); 217 MCOS->emitInt8(dwarf::DW_LNE_set_discriminator); 218 MCOS->emitULEB128IntValue(Discriminator); 219 } 220 if (Isa != LineEntry.getIsa()) { 221 Isa = LineEntry.getIsa(); 222 MCOS->emitInt8(dwarf::DW_LNS_set_isa); 223 MCOS->emitULEB128IntValue(Isa); 224 } 225 if ((LineEntry.getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) { 226 Flags = LineEntry.getFlags(); 227 MCOS->emitInt8(dwarf::DW_LNS_negate_stmt); 228 } 229 if (LineEntry.getFlags() & DWARF2_FLAG_BASIC_BLOCK) 230 MCOS->emitInt8(dwarf::DW_LNS_set_basic_block); 231 if (LineEntry.getFlags() & DWARF2_FLAG_PROLOGUE_END) 232 MCOS->emitInt8(dwarf::DW_LNS_set_prologue_end); 233 if (LineEntry.getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN) 234 MCOS->emitInt8(dwarf::DW_LNS_set_epilogue_begin); 235 236 // At this point we want to emit/create the sequence to encode the delta in 237 // line numbers and the increment of the address from the previous Label 238 // and the current Label. 239 MCOS->emitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label, 240 asmInfo->getCodePointerSize()); 241 242 Discriminator = 0; 243 LastLine = LineEntry.getLine(); 244 LastLabel = Label; 245 } 246 247 // Generate DWARF line end entry. 248 // We do not need this for DwarfDebug that explicitly terminates the line 249 // table using ranges whenever CU or section changes. However, the MC path 250 // does not track ranges nor terminate the line table. In that case, 251 // conservatively use the section end symbol to end the line table. 252 if (!EndEntryEmitted) 253 MCOS->emitDwarfLineEndEntry(Section, LastLabel); 254 } 255 256 // 257 // This emits the Dwarf file and the line tables. 258 // 259 void MCDwarfLineTable::emit(MCStreamer *MCOS, MCDwarfLineTableParams Params) { 260 MCContext &context = MCOS->getContext(); 261 262 auto &LineTables = context.getMCDwarfLineTables(); 263 264 // Bail out early so we don't switch to the debug_line section needlessly and 265 // in doing so create an unnecessary (if empty) section. 266 if (LineTables.empty()) 267 return; 268 269 // In a v5 non-split line table, put the strings in a separate section. 270 std::optional<MCDwarfLineStr> LineStr; 271 if (context.getDwarfVersion() >= 5) 272 LineStr.emplace(context); 273 274 // Switch to the section where the table will be emitted into. 275 MCOS->switchSection(context.getObjectFileInfo()->getDwarfLineSection()); 276 277 // Handle the rest of the Compile Units. 278 for (const auto &CUIDTablePair : LineTables) { 279 CUIDTablePair.second.emitCU(MCOS, Params, LineStr); 280 } 281 282 if (LineStr) 283 LineStr->emitSection(MCOS); 284 } 285 286 void MCDwarfDwoLineTable::Emit(MCStreamer &MCOS, MCDwarfLineTableParams Params, 287 MCSection *Section) const { 288 if (!HasSplitLineTable) 289 return; 290 std::optional<MCDwarfLineStr> NoLineStr(std::nullopt); 291 MCOS.switchSection(Section); 292 MCOS.emitLabel(Header.Emit(&MCOS, Params, std::nullopt, NoLineStr).second); 293 } 294 295 std::pair<MCSymbol *, MCSymbol *> 296 MCDwarfLineTableHeader::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params, 297 std::optional<MCDwarfLineStr> &LineStr) const { 298 static const char StandardOpcodeLengths[] = { 299 0, // length of DW_LNS_copy 300 1, // length of DW_LNS_advance_pc 301 1, // length of DW_LNS_advance_line 302 1, // length of DW_LNS_set_file 303 1, // length of DW_LNS_set_column 304 0, // length of DW_LNS_negate_stmt 305 0, // length of DW_LNS_set_basic_block 306 0, // length of DW_LNS_const_add_pc 307 1, // length of DW_LNS_fixed_advance_pc 308 0, // length of DW_LNS_set_prologue_end 309 0, // length of DW_LNS_set_epilogue_begin 310 1 // DW_LNS_set_isa 311 }; 312 assert(std::size(StandardOpcodeLengths) >= 313 (Params.DWARF2LineOpcodeBase - 1U)); 314 return Emit(MCOS, Params, 315 ArrayRef(StandardOpcodeLengths, Params.DWARF2LineOpcodeBase - 1), 316 LineStr); 317 } 318 319 static const MCExpr *forceExpAbs(MCStreamer &OS, const MCExpr* Expr) { 320 MCContext &Context = OS.getContext(); 321 assert(!isa<MCSymbolRefExpr>(Expr)); 322 if (Context.getAsmInfo()->hasAggressiveSymbolFolding()) 323 return Expr; 324 325 MCSymbol *ABS = Context.createTempSymbol(); 326 OS.emitAssignment(ABS, Expr); 327 return MCSymbolRefExpr::create(ABS, Context); 328 } 329 330 static void emitAbsValue(MCStreamer &OS, const MCExpr *Value, unsigned Size) { 331 const MCExpr *ABS = forceExpAbs(OS, Value); 332 OS.emitValue(ABS, Size); 333 } 334 335 void MCDwarfLineStr::emitSection(MCStreamer *MCOS) { 336 // Switch to the .debug_line_str section. 337 MCOS->switchSection( 338 MCOS->getContext().getObjectFileInfo()->getDwarfLineStrSection()); 339 SmallString<0> Data = getFinalizedData(); 340 MCOS->emitBinaryData(Data.str()); 341 } 342 343 SmallString<0> MCDwarfLineStr::getFinalizedData() { 344 // Emit the strings without perturbing the offsets we used. 345 if (!LineStrings.isFinalized()) 346 LineStrings.finalizeInOrder(); 347 SmallString<0> Data; 348 Data.resize(LineStrings.getSize()); 349 LineStrings.write((uint8_t *)Data.data()); 350 return Data; 351 } 352 353 size_t MCDwarfLineStr::addString(StringRef Path) { 354 return LineStrings.add(Path); 355 } 356 357 void MCDwarfLineStr::emitRef(MCStreamer *MCOS, StringRef Path) { 358 int RefSize = 359 dwarf::getDwarfOffsetByteSize(MCOS->getContext().getDwarfFormat()); 360 size_t Offset = addString(Path); 361 if (UseRelocs) { 362 MCContext &Ctx = MCOS->getContext(); 363 MCOS->emitValue(makeStartPlusIntExpr(Ctx, *LineStrLabel, Offset), RefSize); 364 } else 365 MCOS->emitIntValue(Offset, RefSize); 366 } 367 368 void MCDwarfLineTableHeader::emitV2FileDirTables(MCStreamer *MCOS) const { 369 // First the directory table. 370 for (auto &Dir : MCDwarfDirs) { 371 MCOS->emitBytes(Dir); // The DirectoryName, and... 372 MCOS->emitBytes(StringRef("\0", 1)); // its null terminator. 373 } 374 MCOS->emitInt8(0); // Terminate the directory list. 375 376 // Second the file table. 377 for (unsigned i = 1; i < MCDwarfFiles.size(); i++) { 378 assert(!MCDwarfFiles[i].Name.empty()); 379 MCOS->emitBytes(MCDwarfFiles[i].Name); // FileName and... 380 MCOS->emitBytes(StringRef("\0", 1)); // its null terminator. 381 MCOS->emitULEB128IntValue(MCDwarfFiles[i].DirIndex); // Directory number. 382 MCOS->emitInt8(0); // Last modification timestamp (always 0). 383 MCOS->emitInt8(0); // File size (always 0). 384 } 385 MCOS->emitInt8(0); // Terminate the file list. 386 } 387 388 static void emitOneV5FileEntry(MCStreamer *MCOS, const MCDwarfFile &DwarfFile, 389 bool EmitMD5, bool HasAnySource, 390 std::optional<MCDwarfLineStr> &LineStr) { 391 assert(!DwarfFile.Name.empty()); 392 if (LineStr) 393 LineStr->emitRef(MCOS, DwarfFile.Name); 394 else { 395 MCOS->emitBytes(DwarfFile.Name); // FileName and... 396 MCOS->emitBytes(StringRef("\0", 1)); // its null terminator. 397 } 398 MCOS->emitULEB128IntValue(DwarfFile.DirIndex); // Directory number. 399 if (EmitMD5) { 400 const MD5::MD5Result &Cksum = *DwarfFile.Checksum; 401 MCOS->emitBinaryData( 402 StringRef(reinterpret_cast<const char *>(Cksum.data()), Cksum.size())); 403 } 404 if (HasAnySource) { 405 if (LineStr) 406 LineStr->emitRef(MCOS, DwarfFile.Source.value_or(StringRef())); 407 else { 408 MCOS->emitBytes(DwarfFile.Source.value_or(StringRef())); // Source and... 409 MCOS->emitBytes(StringRef("\0", 1)); // its null terminator. 410 } 411 } 412 } 413 414 void MCDwarfLineTableHeader::emitV5FileDirTables( 415 MCStreamer *MCOS, std::optional<MCDwarfLineStr> &LineStr) const { 416 // The directory format, which is just a list of the directory paths. In a 417 // non-split object, these are references to .debug_line_str; in a split 418 // object, they are inline strings. 419 MCOS->emitInt8(1); 420 MCOS->emitULEB128IntValue(dwarf::DW_LNCT_path); 421 MCOS->emitULEB128IntValue(LineStr ? dwarf::DW_FORM_line_strp 422 : dwarf::DW_FORM_string); 423 MCOS->emitULEB128IntValue(MCDwarfDirs.size() + 1); 424 // Try not to emit an empty compilation directory. 425 SmallString<256> Dir; 426 StringRef CompDir = MCOS->getContext().getCompilationDir(); 427 if (!CompilationDir.empty()) { 428 Dir = CompilationDir; 429 MCOS->getContext().remapDebugPath(Dir); 430 CompDir = Dir.str(); 431 if (LineStr) 432 CompDir = LineStr->getSaver().save(CompDir); 433 } 434 if (LineStr) { 435 // Record path strings, emit references here. 436 LineStr->emitRef(MCOS, CompDir); 437 for (const auto &Dir : MCDwarfDirs) 438 LineStr->emitRef(MCOS, Dir); 439 } else { 440 // The list of directory paths. Compilation directory comes first. 441 MCOS->emitBytes(CompDir); 442 MCOS->emitBytes(StringRef("\0", 1)); 443 for (const auto &Dir : MCDwarfDirs) { 444 MCOS->emitBytes(Dir); // The DirectoryName, and... 445 MCOS->emitBytes(StringRef("\0", 1)); // its null terminator. 446 } 447 } 448 449 // The file format, which is the inline null-terminated filename and a 450 // directory index. We don't track file size/timestamp so don't emit them 451 // in the v5 table. Emit MD5 checksums and source if we have them. 452 uint64_t Entries = 2; 453 if (HasAllMD5) 454 Entries += 1; 455 if (HasAnySource) 456 Entries += 1; 457 MCOS->emitInt8(Entries); 458 MCOS->emitULEB128IntValue(dwarf::DW_LNCT_path); 459 MCOS->emitULEB128IntValue(LineStr ? dwarf::DW_FORM_line_strp 460 : dwarf::DW_FORM_string); 461 MCOS->emitULEB128IntValue(dwarf::DW_LNCT_directory_index); 462 MCOS->emitULEB128IntValue(dwarf::DW_FORM_udata); 463 if (HasAllMD5) { 464 MCOS->emitULEB128IntValue(dwarf::DW_LNCT_MD5); 465 MCOS->emitULEB128IntValue(dwarf::DW_FORM_data16); 466 } 467 if (HasAnySource) { 468 MCOS->emitULEB128IntValue(dwarf::DW_LNCT_LLVM_source); 469 MCOS->emitULEB128IntValue(LineStr ? dwarf::DW_FORM_line_strp 470 : dwarf::DW_FORM_string); 471 } 472 // Then the counted list of files. The root file is file #0, then emit the 473 // files as provide by .file directives. 474 // MCDwarfFiles has an unused element [0] so use size() not size()+1. 475 // But sometimes MCDwarfFiles is empty, in which case we still emit one file. 476 MCOS->emitULEB128IntValue(MCDwarfFiles.empty() ? 1 : MCDwarfFiles.size()); 477 // To accommodate assembler source written for DWARF v4 but trying to emit 478 // v5: If we didn't see a root file explicitly, replicate file #1. 479 assert((!RootFile.Name.empty() || MCDwarfFiles.size() >= 1) && 480 "No root file and no .file directives"); 481 emitOneV5FileEntry(MCOS, RootFile.Name.empty() ? MCDwarfFiles[1] : RootFile, 482 HasAllMD5, HasAnySource, LineStr); 483 for (unsigned i = 1; i < MCDwarfFiles.size(); ++i) 484 emitOneV5FileEntry(MCOS, MCDwarfFiles[i], HasAllMD5, HasAnySource, LineStr); 485 } 486 487 std::pair<MCSymbol *, MCSymbol *> 488 MCDwarfLineTableHeader::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params, 489 ArrayRef<char> StandardOpcodeLengths, 490 std::optional<MCDwarfLineStr> &LineStr) const { 491 MCContext &context = MCOS->getContext(); 492 493 // Create a symbol at the beginning of the line table. 494 MCSymbol *LineStartSym = Label; 495 if (!LineStartSym) 496 LineStartSym = context.createTempSymbol(); 497 498 // Set the value of the symbol, as we are at the start of the line table. 499 MCOS->emitDwarfLineStartLabel(LineStartSym); 500 501 unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(context.getDwarfFormat()); 502 503 MCSymbol *LineEndSym = MCOS->emitDwarfUnitLength("debug_line", "unit length"); 504 505 // Next 2 bytes is the Version. 506 unsigned LineTableVersion = context.getDwarfVersion(); 507 MCOS->emitInt16(LineTableVersion); 508 509 // In v5, we get address info next. 510 if (LineTableVersion >= 5) { 511 MCOS->emitInt8(context.getAsmInfo()->getCodePointerSize()); 512 MCOS->emitInt8(0); // Segment selector; same as EmitGenDwarfAranges. 513 } 514 515 // Create symbols for the start/end of the prologue. 516 MCSymbol *ProStartSym = context.createTempSymbol("prologue_start"); 517 MCSymbol *ProEndSym = context.createTempSymbol("prologue_end"); 518 519 // Length of the prologue, is the next 4 bytes (8 bytes for DWARF64). This is 520 // actually the length from after the length word, to the end of the prologue. 521 MCOS->emitAbsoluteSymbolDiff(ProEndSym, ProStartSym, OffsetSize); 522 523 MCOS->emitLabel(ProStartSym); 524 525 // Parameters of the state machine, are next. 526 MCOS->emitInt8(context.getAsmInfo()->getMinInstAlignment()); 527 // maximum_operations_per_instruction 528 // For non-VLIW architectures this field is always 1. 529 // FIXME: VLIW architectures need to update this field accordingly. 530 if (LineTableVersion >= 4) 531 MCOS->emitInt8(1); 532 MCOS->emitInt8(DWARF2_LINE_DEFAULT_IS_STMT); 533 MCOS->emitInt8(Params.DWARF2LineBase); 534 MCOS->emitInt8(Params.DWARF2LineRange); 535 MCOS->emitInt8(StandardOpcodeLengths.size() + 1); 536 537 // Standard opcode lengths 538 for (char Length : StandardOpcodeLengths) 539 MCOS->emitInt8(Length); 540 541 // Put out the directory and file tables. The formats vary depending on 542 // the version. 543 if (LineTableVersion >= 5) 544 emitV5FileDirTables(MCOS, LineStr); 545 else 546 emitV2FileDirTables(MCOS); 547 548 // This is the end of the prologue, so set the value of the symbol at the 549 // end of the prologue (that was used in a previous expression). 550 MCOS->emitLabel(ProEndSym); 551 552 return std::make_pair(LineStartSym, LineEndSym); 553 } 554 555 void MCDwarfLineTable::emitCU(MCStreamer *MCOS, MCDwarfLineTableParams Params, 556 std::optional<MCDwarfLineStr> &LineStr) const { 557 MCSymbol *LineEndSym = Header.Emit(MCOS, Params, LineStr).second; 558 559 // Put out the line tables. 560 for (const auto &LineSec : MCLineSections.getMCLineEntries()) 561 emitOne(MCOS, LineSec.first, LineSec.second); 562 563 // This is the end of the section, so set the value of the symbol at the end 564 // of this section (that was used in a previous expression). 565 MCOS->emitLabel(LineEndSym); 566 } 567 568 Expected<unsigned> 569 MCDwarfLineTable::tryGetFile(StringRef &Directory, StringRef &FileName, 570 std::optional<MD5::MD5Result> Checksum, 571 std::optional<StringRef> Source, 572 uint16_t DwarfVersion, unsigned FileNumber) { 573 return Header.tryGetFile(Directory, FileName, Checksum, Source, DwarfVersion, 574 FileNumber); 575 } 576 577 static bool isRootFile(const MCDwarfFile &RootFile, StringRef &Directory, 578 StringRef &FileName, 579 std::optional<MD5::MD5Result> Checksum) { 580 if (RootFile.Name.empty() || StringRef(RootFile.Name) != FileName) 581 return false; 582 return RootFile.Checksum == Checksum; 583 } 584 585 Expected<unsigned> 586 MCDwarfLineTableHeader::tryGetFile(StringRef &Directory, StringRef &FileName, 587 std::optional<MD5::MD5Result> Checksum, 588 std::optional<StringRef> Source, 589 uint16_t DwarfVersion, unsigned FileNumber) { 590 if (Directory == CompilationDir) 591 Directory = ""; 592 if (FileName.empty()) { 593 FileName = "<stdin>"; 594 Directory = ""; 595 } 596 assert(!FileName.empty()); 597 // Keep track of whether any or all files have an MD5 checksum. 598 // If any files have embedded source, they all must. 599 if (MCDwarfFiles.empty()) { 600 trackMD5Usage(Checksum.has_value()); 601 HasAnySource |= Source.has_value(); 602 } 603 if (DwarfVersion >= 5 && isRootFile(RootFile, Directory, FileName, Checksum)) 604 return 0; 605 if (FileNumber == 0) { 606 // File numbers start with 1 and/or after any file numbers 607 // allocated by inline-assembler .file directives. 608 FileNumber = MCDwarfFiles.empty() ? 1 : MCDwarfFiles.size(); 609 SmallString<256> Buffer; 610 auto IterBool = SourceIdMap.insert( 611 std::make_pair((Directory + Twine('\0') + FileName).toStringRef(Buffer), 612 FileNumber)); 613 if (!IterBool.second) 614 return IterBool.first->second; 615 } 616 // Make space for this FileNumber in the MCDwarfFiles vector if needed. 617 if (FileNumber >= MCDwarfFiles.size()) 618 MCDwarfFiles.resize(FileNumber + 1); 619 620 // Get the new MCDwarfFile slot for this FileNumber. 621 MCDwarfFile &File = MCDwarfFiles[FileNumber]; 622 623 // It is an error to see the same number more than once. 624 if (!File.Name.empty()) 625 return make_error<StringError>("file number already allocated", 626 inconvertibleErrorCode()); 627 628 if (Directory.empty()) { 629 // Separate the directory part from the basename of the FileName. 630 StringRef tFileName = sys::path::filename(FileName); 631 if (!tFileName.empty()) { 632 Directory = sys::path::parent_path(FileName); 633 if (!Directory.empty()) 634 FileName = tFileName; 635 } 636 } 637 638 // Find or make an entry in the MCDwarfDirs vector for this Directory. 639 // Capture directory name. 640 unsigned DirIndex; 641 if (Directory.empty()) { 642 // For FileNames with no directories a DirIndex of 0 is used. 643 DirIndex = 0; 644 } else { 645 DirIndex = llvm::find(MCDwarfDirs, Directory) - MCDwarfDirs.begin(); 646 if (DirIndex >= MCDwarfDirs.size()) 647 MCDwarfDirs.push_back(std::string(Directory)); 648 // The DirIndex is one based, as DirIndex of 0 is used for FileNames with 649 // no directories. MCDwarfDirs[] is unlike MCDwarfFiles[] in that the 650 // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames 651 // are stored at MCDwarfFiles[FileNumber].Name . 652 DirIndex++; 653 } 654 655 File.Name = std::string(FileName); 656 File.DirIndex = DirIndex; 657 File.Checksum = Checksum; 658 trackMD5Usage(Checksum.has_value()); 659 File.Source = Source; 660 if (Source.has_value()) 661 HasAnySource = true; 662 663 // return the allocated FileNumber. 664 return FileNumber; 665 } 666 667 /// Utility function to emit the encoding to a streamer. 668 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params, 669 int64_t LineDelta, uint64_t AddrDelta) { 670 MCContext &Context = MCOS->getContext(); 671 SmallString<256> Tmp; 672 MCDwarfLineAddr::encode(Context, Params, LineDelta, AddrDelta, Tmp); 673 MCOS->emitBytes(Tmp); 674 } 675 676 /// Given a special op, return the address skip amount (in units of 677 /// DWARF2_LINE_MIN_INSN_LENGTH). 678 static uint64_t SpecialAddr(MCDwarfLineTableParams Params, uint64_t op) { 679 return (op - Params.DWARF2LineOpcodeBase) / Params.DWARF2LineRange; 680 } 681 682 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas. 683 void MCDwarfLineAddr::encode(MCContext &Context, MCDwarfLineTableParams Params, 684 int64_t LineDelta, uint64_t AddrDelta, 685 SmallVectorImpl<char> &Out) { 686 uint8_t Buf[16]; 687 uint64_t Temp, Opcode; 688 bool NeedCopy = false; 689 690 // The maximum address skip amount that can be encoded with a special op. 691 uint64_t MaxSpecialAddrDelta = SpecialAddr(Params, 255); 692 693 // Scale the address delta by the minimum instruction length. 694 AddrDelta = ScaleAddrDelta(Context, AddrDelta); 695 696 // A LineDelta of INT64_MAX is a signal that this is actually a 697 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the 698 // end_sequence to emit the matrix entry. 699 if (LineDelta == INT64_MAX) { 700 if (AddrDelta == MaxSpecialAddrDelta) 701 Out.push_back(dwarf::DW_LNS_const_add_pc); 702 else if (AddrDelta) { 703 Out.push_back(dwarf::DW_LNS_advance_pc); 704 Out.append(Buf, Buf + encodeULEB128(AddrDelta, Buf)); 705 } 706 Out.push_back(dwarf::DW_LNS_extended_op); 707 Out.push_back(1); 708 Out.push_back(dwarf::DW_LNE_end_sequence); 709 return; 710 } 711 712 // Bias the line delta by the base. 713 Temp = LineDelta - Params.DWARF2LineBase; 714 715 // If the line increment is out of range of a special opcode, we must encode 716 // it with DW_LNS_advance_line. 717 if (Temp >= Params.DWARF2LineRange || 718 Temp + Params.DWARF2LineOpcodeBase > 255) { 719 Out.push_back(dwarf::DW_LNS_advance_line); 720 Out.append(Buf, Buf + encodeSLEB128(LineDelta, Buf)); 721 722 LineDelta = 0; 723 Temp = 0 - Params.DWARF2LineBase; 724 NeedCopy = true; 725 } 726 727 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode. 728 if (LineDelta == 0 && AddrDelta == 0) { 729 Out.push_back(dwarf::DW_LNS_copy); 730 return; 731 } 732 733 // Bias the opcode by the special opcode base. 734 Temp += Params.DWARF2LineOpcodeBase; 735 736 // Avoid overflow when addr_delta is large. 737 if (AddrDelta < 256 + MaxSpecialAddrDelta) { 738 // Try using a special opcode. 739 Opcode = Temp + AddrDelta * Params.DWARF2LineRange; 740 if (Opcode <= 255) { 741 Out.push_back(Opcode); 742 return; 743 } 744 745 // Try using DW_LNS_const_add_pc followed by special op. 746 Opcode = Temp + (AddrDelta - MaxSpecialAddrDelta) * Params.DWARF2LineRange; 747 if (Opcode <= 255) { 748 Out.push_back(dwarf::DW_LNS_const_add_pc); 749 Out.push_back(Opcode); 750 return; 751 } 752 } 753 754 // Otherwise use DW_LNS_advance_pc. 755 Out.push_back(dwarf::DW_LNS_advance_pc); 756 Out.append(Buf, Buf + encodeULEB128(AddrDelta, Buf)); 757 758 if (NeedCopy) 759 Out.push_back(dwarf::DW_LNS_copy); 760 else { 761 assert(Temp <= 255 && "Buggy special opcode encoding."); 762 Out.push_back(Temp); 763 } 764 } 765 766 // Utility function to write a tuple for .debug_abbrev. 767 static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) { 768 MCOS->emitULEB128IntValue(Name); 769 MCOS->emitULEB128IntValue(Form); 770 } 771 772 // When generating dwarf for assembly source files this emits 773 // the data for .debug_abbrev section which contains three DIEs. 774 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) { 775 MCContext &context = MCOS->getContext(); 776 MCOS->switchSection(context.getObjectFileInfo()->getDwarfAbbrevSection()); 777 778 // DW_TAG_compile_unit DIE abbrev (1). 779 MCOS->emitULEB128IntValue(1); 780 MCOS->emitULEB128IntValue(dwarf::DW_TAG_compile_unit); 781 MCOS->emitInt8(dwarf::DW_CHILDREN_yes); 782 dwarf::Form SecOffsetForm = 783 context.getDwarfVersion() >= 4 784 ? dwarf::DW_FORM_sec_offset 785 : (context.getDwarfFormat() == dwarf::DWARF64 ? dwarf::DW_FORM_data8 786 : dwarf::DW_FORM_data4); 787 EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, SecOffsetForm); 788 if (context.getGenDwarfSectionSyms().size() > 1 && 789 context.getDwarfVersion() >= 3) { 790 EmitAbbrev(MCOS, dwarf::DW_AT_ranges, SecOffsetForm); 791 } else { 792 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr); 793 EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr); 794 } 795 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string); 796 if (!context.getCompilationDir().empty()) 797 EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string); 798 StringRef DwarfDebugFlags = context.getDwarfDebugFlags(); 799 if (!DwarfDebugFlags.empty()) 800 EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string); 801 EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string); 802 EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2); 803 EmitAbbrev(MCOS, 0, 0); 804 805 // DW_TAG_label DIE abbrev (2). 806 MCOS->emitULEB128IntValue(2); 807 MCOS->emitULEB128IntValue(dwarf::DW_TAG_label); 808 MCOS->emitInt8(dwarf::DW_CHILDREN_no); 809 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string); 810 EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4); 811 EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4); 812 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr); 813 EmitAbbrev(MCOS, 0, 0); 814 815 // Terminate the abbreviations for this compilation unit. 816 MCOS->emitInt8(0); 817 } 818 819 // When generating dwarf for assembly source files this emits the data for 820 // .debug_aranges section. This section contains a header and a table of pairs 821 // of PointerSize'ed values for the address and size of section(s) with line 822 // table entries. 823 static void EmitGenDwarfAranges(MCStreamer *MCOS, 824 const MCSymbol *InfoSectionSymbol) { 825 MCContext &context = MCOS->getContext(); 826 827 auto &Sections = context.getGenDwarfSectionSyms(); 828 829 MCOS->switchSection(context.getObjectFileInfo()->getDwarfARangesSection()); 830 831 unsigned UnitLengthBytes = 832 dwarf::getUnitLengthFieldByteSize(context.getDwarfFormat()); 833 unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(context.getDwarfFormat()); 834 835 // This will be the length of the .debug_aranges section, first account for 836 // the size of each item in the header (see below where we emit these items). 837 int Length = UnitLengthBytes + 2 + OffsetSize + 1 + 1; 838 839 // Figure the padding after the header before the table of address and size 840 // pairs who's values are PointerSize'ed. 841 const MCAsmInfo *asmInfo = context.getAsmInfo(); 842 int AddrSize = asmInfo->getCodePointerSize(); 843 int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1)); 844 if (Pad == 2 * AddrSize) 845 Pad = 0; 846 Length += Pad; 847 848 // Add the size of the pair of PointerSize'ed values for the address and size 849 // of each section we have in the table. 850 Length += 2 * AddrSize * Sections.size(); 851 // And the pair of terminating zeros. 852 Length += 2 * AddrSize; 853 854 // Emit the header for this section. 855 if (context.getDwarfFormat() == dwarf::DWARF64) 856 // The DWARF64 mark. 857 MCOS->emitInt32(dwarf::DW_LENGTH_DWARF64); 858 // The 4 (8 for DWARF64) byte length not including the length of the unit 859 // length field itself. 860 MCOS->emitIntValue(Length - UnitLengthBytes, OffsetSize); 861 // The 2 byte version, which is 2. 862 MCOS->emitInt16(2); 863 // The 4 (8 for DWARF64) byte offset to the compile unit in the .debug_info 864 // from the start of the .debug_info. 865 if (InfoSectionSymbol) 866 MCOS->emitSymbolValue(InfoSectionSymbol, OffsetSize, 867 asmInfo->needsDwarfSectionOffsetDirective()); 868 else 869 MCOS->emitIntValue(0, OffsetSize); 870 // The 1 byte size of an address. 871 MCOS->emitInt8(AddrSize); 872 // The 1 byte size of a segment descriptor, we use a value of zero. 873 MCOS->emitInt8(0); 874 // Align the header with the padding if needed, before we put out the table. 875 for(int i = 0; i < Pad; i++) 876 MCOS->emitInt8(0); 877 878 // Now emit the table of pairs of PointerSize'ed values for the section 879 // addresses and sizes. 880 for (MCSection *Sec : Sections) { 881 const MCSymbol *StartSymbol = Sec->getBeginSymbol(); 882 MCSymbol *EndSymbol = Sec->getEndSymbol(context); 883 assert(StartSymbol && "StartSymbol must not be NULL"); 884 assert(EndSymbol && "EndSymbol must not be NULL"); 885 886 const MCExpr *Addr = MCSymbolRefExpr::create( 887 StartSymbol, MCSymbolRefExpr::VK_None, context); 888 const MCExpr *Size = 889 makeEndMinusStartExpr(context, *StartSymbol, *EndSymbol, 0); 890 MCOS->emitValue(Addr, AddrSize); 891 emitAbsValue(*MCOS, Size, AddrSize); 892 } 893 894 // And finally the pair of terminating zeros. 895 MCOS->emitIntValue(0, AddrSize); 896 MCOS->emitIntValue(0, AddrSize); 897 } 898 899 // When generating dwarf for assembly source files this emits the data for 900 // .debug_info section which contains three parts. The header, the compile_unit 901 // DIE and a list of label DIEs. 902 static void EmitGenDwarfInfo(MCStreamer *MCOS, 903 const MCSymbol *AbbrevSectionSymbol, 904 const MCSymbol *LineSectionSymbol, 905 const MCSymbol *RangesSymbol) { 906 MCContext &context = MCOS->getContext(); 907 908 MCOS->switchSection(context.getObjectFileInfo()->getDwarfInfoSection()); 909 910 // Create a symbol at the start and end of this section used in here for the 911 // expression to calculate the length in the header. 912 MCSymbol *InfoStart = context.createTempSymbol(); 913 MCOS->emitLabel(InfoStart); 914 MCSymbol *InfoEnd = context.createTempSymbol(); 915 916 // First part: the header. 917 918 unsigned UnitLengthBytes = 919 dwarf::getUnitLengthFieldByteSize(context.getDwarfFormat()); 920 unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(context.getDwarfFormat()); 921 922 if (context.getDwarfFormat() == dwarf::DWARF64) 923 // Emit DWARF64 mark. 924 MCOS->emitInt32(dwarf::DW_LENGTH_DWARF64); 925 926 // The 4 (8 for DWARF64) byte total length of the information for this 927 // compilation unit, not including the unit length field itself. 928 const MCExpr *Length = 929 makeEndMinusStartExpr(context, *InfoStart, *InfoEnd, UnitLengthBytes); 930 emitAbsValue(*MCOS, Length, OffsetSize); 931 932 // The 2 byte DWARF version. 933 MCOS->emitInt16(context.getDwarfVersion()); 934 935 // The DWARF v5 header has unit type, address size, abbrev offset. 936 // Earlier versions have abbrev offset, address size. 937 const MCAsmInfo &AsmInfo = *context.getAsmInfo(); 938 int AddrSize = AsmInfo.getCodePointerSize(); 939 if (context.getDwarfVersion() >= 5) { 940 MCOS->emitInt8(dwarf::DW_UT_compile); 941 MCOS->emitInt8(AddrSize); 942 } 943 // The 4 (8 for DWARF64) byte offset to the debug abbrevs from the start of 944 // the .debug_abbrev. 945 if (AbbrevSectionSymbol) 946 MCOS->emitSymbolValue(AbbrevSectionSymbol, OffsetSize, 947 AsmInfo.needsDwarfSectionOffsetDirective()); 948 else 949 // Since the abbrevs are at the start of the section, the offset is zero. 950 MCOS->emitIntValue(0, OffsetSize); 951 if (context.getDwarfVersion() <= 4) 952 MCOS->emitInt8(AddrSize); 953 954 // Second part: the compile_unit DIE. 955 956 // The DW_TAG_compile_unit DIE abbrev (1). 957 MCOS->emitULEB128IntValue(1); 958 959 // DW_AT_stmt_list, a 4 (8 for DWARF64) byte offset from the start of the 960 // .debug_line section. 961 if (LineSectionSymbol) 962 MCOS->emitSymbolValue(LineSectionSymbol, OffsetSize, 963 AsmInfo.needsDwarfSectionOffsetDirective()); 964 else 965 // The line table is at the start of the section, so the offset is zero. 966 MCOS->emitIntValue(0, OffsetSize); 967 968 if (RangesSymbol) { 969 // There are multiple sections containing code, so we must use 970 // .debug_ranges/.debug_rnglists. AT_ranges, the 4/8 byte offset from the 971 // start of the .debug_ranges/.debug_rnglists. 972 MCOS->emitSymbolValue(RangesSymbol, OffsetSize); 973 } else { 974 // If we only have one non-empty code section, we can use the simpler 975 // AT_low_pc and AT_high_pc attributes. 976 977 // Find the first (and only) non-empty text section 978 auto &Sections = context.getGenDwarfSectionSyms(); 979 const auto TextSection = Sections.begin(); 980 assert(TextSection != Sections.end() && "No text section found"); 981 982 MCSymbol *StartSymbol = (*TextSection)->getBeginSymbol(); 983 MCSymbol *EndSymbol = (*TextSection)->getEndSymbol(context); 984 assert(StartSymbol && "StartSymbol must not be NULL"); 985 assert(EndSymbol && "EndSymbol must not be NULL"); 986 987 // AT_low_pc, the first address of the default .text section. 988 const MCExpr *Start = MCSymbolRefExpr::create( 989 StartSymbol, MCSymbolRefExpr::VK_None, context); 990 MCOS->emitValue(Start, AddrSize); 991 992 // AT_high_pc, the last address of the default .text section. 993 const MCExpr *End = MCSymbolRefExpr::create( 994 EndSymbol, MCSymbolRefExpr::VK_None, context); 995 MCOS->emitValue(End, AddrSize); 996 } 997 998 // AT_name, the name of the source file. Reconstruct from the first directory 999 // and file table entries. 1000 const SmallVectorImpl<std::string> &MCDwarfDirs = context.getMCDwarfDirs(); 1001 if (MCDwarfDirs.size() > 0) { 1002 MCOS->emitBytes(MCDwarfDirs[0]); 1003 MCOS->emitBytes(sys::path::get_separator()); 1004 } 1005 const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles = context.getMCDwarfFiles(); 1006 // MCDwarfFiles might be empty if we have an empty source file. 1007 // If it's not empty, [0] is unused and [1] is the first actual file. 1008 assert(MCDwarfFiles.empty() || MCDwarfFiles.size() >= 2); 1009 const MCDwarfFile &RootFile = 1010 MCDwarfFiles.empty() 1011 ? context.getMCDwarfLineTable(/*CUID=*/0).getRootFile() 1012 : MCDwarfFiles[1]; 1013 MCOS->emitBytes(RootFile.Name); 1014 MCOS->emitInt8(0); // NULL byte to terminate the string. 1015 1016 // AT_comp_dir, the working directory the assembly was done in. 1017 if (!context.getCompilationDir().empty()) { 1018 MCOS->emitBytes(context.getCompilationDir()); 1019 MCOS->emitInt8(0); // NULL byte to terminate the string. 1020 } 1021 1022 // AT_APPLE_flags, the command line arguments of the assembler tool. 1023 StringRef DwarfDebugFlags = context.getDwarfDebugFlags(); 1024 if (!DwarfDebugFlags.empty()){ 1025 MCOS->emitBytes(DwarfDebugFlags); 1026 MCOS->emitInt8(0); // NULL byte to terminate the string. 1027 } 1028 1029 // AT_producer, the version of the assembler tool. 1030 StringRef DwarfDebugProducer = context.getDwarfDebugProducer(); 1031 if (!DwarfDebugProducer.empty()) 1032 MCOS->emitBytes(DwarfDebugProducer); 1033 else 1034 MCOS->emitBytes(StringRef("llvm-mc (based on LLVM " PACKAGE_VERSION ")")); 1035 MCOS->emitInt8(0); // NULL byte to terminate the string. 1036 1037 // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2 1038 // draft has no standard code for assembler. 1039 MCOS->emitInt16(dwarf::DW_LANG_Mips_Assembler); 1040 1041 // Third part: the list of label DIEs. 1042 1043 // Loop on saved info for dwarf labels and create the DIEs for them. 1044 const std::vector<MCGenDwarfLabelEntry> &Entries = 1045 MCOS->getContext().getMCGenDwarfLabelEntries(); 1046 for (const auto &Entry : Entries) { 1047 // The DW_TAG_label DIE abbrev (2). 1048 MCOS->emitULEB128IntValue(2); 1049 1050 // AT_name, of the label without any leading underbar. 1051 MCOS->emitBytes(Entry.getName()); 1052 MCOS->emitInt8(0); // NULL byte to terminate the string. 1053 1054 // AT_decl_file, index into the file table. 1055 MCOS->emitInt32(Entry.getFileNumber()); 1056 1057 // AT_decl_line, source line number. 1058 MCOS->emitInt32(Entry.getLineNumber()); 1059 1060 // AT_low_pc, start address of the label. 1061 const MCExpr *AT_low_pc = MCSymbolRefExpr::create(Entry.getLabel(), 1062 MCSymbolRefExpr::VK_None, context); 1063 MCOS->emitValue(AT_low_pc, AddrSize); 1064 } 1065 1066 // Add the NULL DIE terminating the Compile Unit DIE's. 1067 MCOS->emitInt8(0); 1068 1069 // Now set the value of the symbol at the end of the info section. 1070 MCOS->emitLabel(InfoEnd); 1071 } 1072 1073 // When generating dwarf for assembly source files this emits the data for 1074 // .debug_ranges section. We only emit one range list, which spans all of the 1075 // executable sections of this file. 1076 static MCSymbol *emitGenDwarfRanges(MCStreamer *MCOS) { 1077 MCContext &context = MCOS->getContext(); 1078 auto &Sections = context.getGenDwarfSectionSyms(); 1079 1080 const MCAsmInfo *AsmInfo = context.getAsmInfo(); 1081 int AddrSize = AsmInfo->getCodePointerSize(); 1082 MCSymbol *RangesSymbol; 1083 1084 if (MCOS->getContext().getDwarfVersion() >= 5) { 1085 MCOS->switchSection(context.getObjectFileInfo()->getDwarfRnglistsSection()); 1086 MCSymbol *EndSymbol = mcdwarf::emitListsTableHeaderStart(*MCOS); 1087 MCOS->AddComment("Offset entry count"); 1088 MCOS->emitInt32(0); 1089 RangesSymbol = context.createTempSymbol("debug_rnglist0_start"); 1090 MCOS->emitLabel(RangesSymbol); 1091 for (MCSection *Sec : Sections) { 1092 const MCSymbol *StartSymbol = Sec->getBeginSymbol(); 1093 const MCSymbol *EndSymbol = Sec->getEndSymbol(context); 1094 const MCExpr *SectionStartAddr = MCSymbolRefExpr::create( 1095 StartSymbol, MCSymbolRefExpr::VK_None, context); 1096 const MCExpr *SectionSize = 1097 makeEndMinusStartExpr(context, *StartSymbol, *EndSymbol, 0); 1098 MCOS->emitInt8(dwarf::DW_RLE_start_length); 1099 MCOS->emitValue(SectionStartAddr, AddrSize); 1100 MCOS->emitULEB128Value(SectionSize); 1101 } 1102 MCOS->emitInt8(dwarf::DW_RLE_end_of_list); 1103 MCOS->emitLabel(EndSymbol); 1104 } else { 1105 MCOS->switchSection(context.getObjectFileInfo()->getDwarfRangesSection()); 1106 RangesSymbol = context.createTempSymbol("debug_ranges_start"); 1107 MCOS->emitLabel(RangesSymbol); 1108 for (MCSection *Sec : Sections) { 1109 const MCSymbol *StartSymbol = Sec->getBeginSymbol(); 1110 const MCSymbol *EndSymbol = Sec->getEndSymbol(context); 1111 1112 // Emit a base address selection entry for the section start. 1113 const MCExpr *SectionStartAddr = MCSymbolRefExpr::create( 1114 StartSymbol, MCSymbolRefExpr::VK_None, context); 1115 MCOS->emitFill(AddrSize, 0xFF); 1116 MCOS->emitValue(SectionStartAddr, AddrSize); 1117 1118 // Emit a range list entry spanning this section. 1119 const MCExpr *SectionSize = 1120 makeEndMinusStartExpr(context, *StartSymbol, *EndSymbol, 0); 1121 MCOS->emitIntValue(0, AddrSize); 1122 emitAbsValue(*MCOS, SectionSize, AddrSize); 1123 } 1124 1125 // Emit end of list entry 1126 MCOS->emitIntValue(0, AddrSize); 1127 MCOS->emitIntValue(0, AddrSize); 1128 } 1129 1130 return RangesSymbol; 1131 } 1132 1133 // 1134 // When generating dwarf for assembly source files this emits the Dwarf 1135 // sections. 1136 // 1137 void MCGenDwarfInfo::Emit(MCStreamer *MCOS) { 1138 MCContext &context = MCOS->getContext(); 1139 1140 // Create the dwarf sections in this order (.debug_line already created). 1141 const MCAsmInfo *AsmInfo = context.getAsmInfo(); 1142 bool CreateDwarfSectionSymbols = 1143 AsmInfo->doesDwarfUseRelocationsAcrossSections(); 1144 MCSymbol *LineSectionSymbol = nullptr; 1145 if (CreateDwarfSectionSymbols) 1146 LineSectionSymbol = MCOS->getDwarfLineTableSymbol(0); 1147 MCSymbol *AbbrevSectionSymbol = nullptr; 1148 MCSymbol *InfoSectionSymbol = nullptr; 1149 MCSymbol *RangesSymbol = nullptr; 1150 1151 // Create end symbols for each section, and remove empty sections 1152 MCOS->getContext().finalizeDwarfSections(*MCOS); 1153 1154 // If there are no sections to generate debug info for, we don't need 1155 // to do anything 1156 if (MCOS->getContext().getGenDwarfSectionSyms().empty()) 1157 return; 1158 1159 // We only use the .debug_ranges section if we have multiple code sections, 1160 // and we are emitting a DWARF version which supports it. 1161 const bool UseRangesSection = 1162 MCOS->getContext().getGenDwarfSectionSyms().size() > 1 && 1163 MCOS->getContext().getDwarfVersion() >= 3; 1164 CreateDwarfSectionSymbols |= UseRangesSection; 1165 1166 MCOS->switchSection(context.getObjectFileInfo()->getDwarfInfoSection()); 1167 if (CreateDwarfSectionSymbols) { 1168 InfoSectionSymbol = context.createTempSymbol(); 1169 MCOS->emitLabel(InfoSectionSymbol); 1170 } 1171 MCOS->switchSection(context.getObjectFileInfo()->getDwarfAbbrevSection()); 1172 if (CreateDwarfSectionSymbols) { 1173 AbbrevSectionSymbol = context.createTempSymbol(); 1174 MCOS->emitLabel(AbbrevSectionSymbol); 1175 } 1176 1177 MCOS->switchSection(context.getObjectFileInfo()->getDwarfARangesSection()); 1178 1179 // Output the data for .debug_aranges section. 1180 EmitGenDwarfAranges(MCOS, InfoSectionSymbol); 1181 1182 if (UseRangesSection) { 1183 RangesSymbol = emitGenDwarfRanges(MCOS); 1184 assert(RangesSymbol); 1185 } 1186 1187 // Output the data for .debug_abbrev section. 1188 EmitGenDwarfAbbrev(MCOS); 1189 1190 // Output the data for .debug_info section. 1191 EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol, RangesSymbol); 1192 } 1193 1194 // 1195 // When generating dwarf for assembly source files this is called when symbol 1196 // for a label is created. If this symbol is not a temporary and is in the 1197 // section that dwarf is being generated for, save the needed info to create 1198 // a dwarf label. 1199 // 1200 void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS, 1201 SourceMgr &SrcMgr, SMLoc &Loc) { 1202 // We won't create dwarf labels for temporary symbols. 1203 if (Symbol->isTemporary()) 1204 return; 1205 MCContext &context = MCOS->getContext(); 1206 // We won't create dwarf labels for symbols in sections that we are not 1207 // generating debug info for. 1208 if (!context.getGenDwarfSectionSyms().count(MCOS->getCurrentSectionOnly())) 1209 return; 1210 1211 // The dwarf label's name does not have the symbol name's leading 1212 // underbar if any. 1213 StringRef Name = Symbol->getName(); 1214 if (Name.starts_with("_")) 1215 Name = Name.substr(1, Name.size()-1); 1216 1217 // Get the dwarf file number to be used for the dwarf label. 1218 unsigned FileNumber = context.getGenDwarfFileNumber(); 1219 1220 // Finding the line number is the expensive part which is why we just don't 1221 // pass it in as for some symbols we won't create a dwarf label. 1222 unsigned CurBuffer = SrcMgr.FindBufferContainingLoc(Loc); 1223 unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer); 1224 1225 // We create a temporary symbol for use for the AT_high_pc and AT_low_pc 1226 // values so that they don't have things like an ARM thumb bit from the 1227 // original symbol. So when used they won't get a low bit set after 1228 // relocation. 1229 MCSymbol *Label = context.createTempSymbol(); 1230 MCOS->emitLabel(Label); 1231 1232 // Create and entry for the info and add it to the other entries. 1233 MCOS->getContext().addMCGenDwarfLabelEntry( 1234 MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label)); 1235 } 1236 1237 static int getDataAlignmentFactor(MCStreamer &streamer) { 1238 MCContext &context = streamer.getContext(); 1239 const MCAsmInfo *asmInfo = context.getAsmInfo(); 1240 int size = asmInfo->getCalleeSaveStackSlotSize(); 1241 if (asmInfo->isStackGrowthDirectionUp()) 1242 return size; 1243 else 1244 return -size; 1245 } 1246 1247 static unsigned getSizeForEncoding(MCStreamer &streamer, 1248 unsigned symbolEncoding) { 1249 MCContext &context = streamer.getContext(); 1250 unsigned format = symbolEncoding & 0x0f; 1251 switch (format) { 1252 default: llvm_unreachable("Unknown Encoding"); 1253 case dwarf::DW_EH_PE_absptr: 1254 case dwarf::DW_EH_PE_signed: 1255 return context.getAsmInfo()->getCodePointerSize(); 1256 case dwarf::DW_EH_PE_udata2: 1257 case dwarf::DW_EH_PE_sdata2: 1258 return 2; 1259 case dwarf::DW_EH_PE_udata4: 1260 case dwarf::DW_EH_PE_sdata4: 1261 return 4; 1262 case dwarf::DW_EH_PE_udata8: 1263 case dwarf::DW_EH_PE_sdata8: 1264 return 8; 1265 } 1266 } 1267 1268 static void emitFDESymbol(MCObjectStreamer &streamer, const MCSymbol &symbol, 1269 unsigned symbolEncoding, bool isEH) { 1270 MCContext &context = streamer.getContext(); 1271 const MCAsmInfo *asmInfo = context.getAsmInfo(); 1272 const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol, 1273 symbolEncoding, 1274 streamer); 1275 unsigned size = getSizeForEncoding(streamer, symbolEncoding); 1276 if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH) 1277 emitAbsValue(streamer, v, size); 1278 else 1279 streamer.emitValue(v, size); 1280 } 1281 1282 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol, 1283 unsigned symbolEncoding) { 1284 MCContext &context = streamer.getContext(); 1285 const MCAsmInfo *asmInfo = context.getAsmInfo(); 1286 const MCExpr *v = asmInfo->getExprForPersonalitySymbol(&symbol, 1287 symbolEncoding, 1288 streamer); 1289 unsigned size = getSizeForEncoding(streamer, symbolEncoding); 1290 streamer.emitValue(v, size); 1291 } 1292 1293 namespace { 1294 1295 class FrameEmitterImpl { 1296 int CFAOffset = 0; 1297 int InitialCFAOffset = 0; 1298 bool IsEH; 1299 MCObjectStreamer &Streamer; 1300 1301 public: 1302 FrameEmitterImpl(bool IsEH, MCObjectStreamer &Streamer) 1303 : IsEH(IsEH), Streamer(Streamer) {} 1304 1305 /// Emit the unwind information in a compact way. 1306 void EmitCompactUnwind(const MCDwarfFrameInfo &frame); 1307 1308 const MCSymbol &EmitCIE(const MCDwarfFrameInfo &F); 1309 void EmitFDE(const MCSymbol &cieStart, const MCDwarfFrameInfo &frame, 1310 bool LastInSection, const MCSymbol &SectionStart); 1311 void emitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs, 1312 MCSymbol *BaseLabel); 1313 void emitCFIInstruction(const MCCFIInstruction &Instr); 1314 }; 1315 1316 } // end anonymous namespace 1317 1318 static void emitEncodingByte(MCObjectStreamer &Streamer, unsigned Encoding) { 1319 Streamer.emitInt8(Encoding); 1320 } 1321 1322 void FrameEmitterImpl::emitCFIInstruction(const MCCFIInstruction &Instr) { 1323 int dataAlignmentFactor = getDataAlignmentFactor(Streamer); 1324 auto *MRI = Streamer.getContext().getRegisterInfo(); 1325 1326 switch (Instr.getOperation()) { 1327 case MCCFIInstruction::OpRegister: { 1328 unsigned Reg1 = Instr.getRegister(); 1329 unsigned Reg2 = Instr.getRegister2(); 1330 if (!IsEH) { 1331 Reg1 = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg1); 1332 Reg2 = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg2); 1333 } 1334 Streamer.emitInt8(dwarf::DW_CFA_register); 1335 Streamer.emitULEB128IntValue(Reg1); 1336 Streamer.emitULEB128IntValue(Reg2); 1337 return; 1338 } 1339 case MCCFIInstruction::OpWindowSave: 1340 Streamer.emitInt8(dwarf::DW_CFA_GNU_window_save); 1341 return; 1342 1343 case MCCFIInstruction::OpNegateRAState: 1344 Streamer.emitInt8(dwarf::DW_CFA_AARCH64_negate_ra_state); 1345 return; 1346 1347 case MCCFIInstruction::OpUndefined: { 1348 unsigned Reg = Instr.getRegister(); 1349 Streamer.emitInt8(dwarf::DW_CFA_undefined); 1350 Streamer.emitULEB128IntValue(Reg); 1351 return; 1352 } 1353 case MCCFIInstruction::OpAdjustCfaOffset: 1354 case MCCFIInstruction::OpDefCfaOffset: { 1355 const bool IsRelative = 1356 Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset; 1357 1358 Streamer.emitInt8(dwarf::DW_CFA_def_cfa_offset); 1359 1360 if (IsRelative) 1361 CFAOffset += Instr.getOffset(); 1362 else 1363 CFAOffset = Instr.getOffset(); 1364 1365 Streamer.emitULEB128IntValue(CFAOffset); 1366 1367 return; 1368 } 1369 case MCCFIInstruction::OpDefCfa: { 1370 unsigned Reg = Instr.getRegister(); 1371 if (!IsEH) 1372 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg); 1373 Streamer.emitInt8(dwarf::DW_CFA_def_cfa); 1374 Streamer.emitULEB128IntValue(Reg); 1375 CFAOffset = Instr.getOffset(); 1376 Streamer.emitULEB128IntValue(CFAOffset); 1377 1378 return; 1379 } 1380 case MCCFIInstruction::OpDefCfaRegister: { 1381 unsigned Reg = Instr.getRegister(); 1382 if (!IsEH) 1383 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg); 1384 Streamer.emitInt8(dwarf::DW_CFA_def_cfa_register); 1385 Streamer.emitULEB128IntValue(Reg); 1386 1387 return; 1388 } 1389 // TODO: Implement `_sf` variants if/when they need to be emitted. 1390 case MCCFIInstruction::OpLLVMDefAspaceCfa: { 1391 unsigned Reg = Instr.getRegister(); 1392 if (!IsEH) 1393 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg); 1394 Streamer.emitIntValue(dwarf::DW_CFA_LLVM_def_aspace_cfa, 1); 1395 Streamer.emitULEB128IntValue(Reg); 1396 CFAOffset = Instr.getOffset(); 1397 Streamer.emitULEB128IntValue(CFAOffset); 1398 Streamer.emitULEB128IntValue(Instr.getAddressSpace()); 1399 1400 return; 1401 } 1402 case MCCFIInstruction::OpOffset: 1403 case MCCFIInstruction::OpRelOffset: { 1404 const bool IsRelative = 1405 Instr.getOperation() == MCCFIInstruction::OpRelOffset; 1406 1407 unsigned Reg = Instr.getRegister(); 1408 if (!IsEH) 1409 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg); 1410 1411 int Offset = Instr.getOffset(); 1412 if (IsRelative) 1413 Offset -= CFAOffset; 1414 Offset = Offset / dataAlignmentFactor; 1415 1416 if (Offset < 0) { 1417 Streamer.emitInt8(dwarf::DW_CFA_offset_extended_sf); 1418 Streamer.emitULEB128IntValue(Reg); 1419 Streamer.emitSLEB128IntValue(Offset); 1420 } else if (Reg < 64) { 1421 Streamer.emitInt8(dwarf::DW_CFA_offset + Reg); 1422 Streamer.emitULEB128IntValue(Offset); 1423 } else { 1424 Streamer.emitInt8(dwarf::DW_CFA_offset_extended); 1425 Streamer.emitULEB128IntValue(Reg); 1426 Streamer.emitULEB128IntValue(Offset); 1427 } 1428 return; 1429 } 1430 case MCCFIInstruction::OpRememberState: 1431 Streamer.emitInt8(dwarf::DW_CFA_remember_state); 1432 return; 1433 case MCCFIInstruction::OpRestoreState: 1434 Streamer.emitInt8(dwarf::DW_CFA_restore_state); 1435 return; 1436 case MCCFIInstruction::OpSameValue: { 1437 unsigned Reg = Instr.getRegister(); 1438 Streamer.emitInt8(dwarf::DW_CFA_same_value); 1439 Streamer.emitULEB128IntValue(Reg); 1440 return; 1441 } 1442 case MCCFIInstruction::OpRestore: { 1443 unsigned Reg = Instr.getRegister(); 1444 if (!IsEH) 1445 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg); 1446 if (Reg < 64) { 1447 Streamer.emitInt8(dwarf::DW_CFA_restore | Reg); 1448 } else { 1449 Streamer.emitInt8(dwarf::DW_CFA_restore_extended); 1450 Streamer.emitULEB128IntValue(Reg); 1451 } 1452 return; 1453 } 1454 case MCCFIInstruction::OpGnuArgsSize: 1455 Streamer.emitInt8(dwarf::DW_CFA_GNU_args_size); 1456 Streamer.emitULEB128IntValue(Instr.getOffset()); 1457 return; 1458 1459 case MCCFIInstruction::OpEscape: 1460 Streamer.emitBytes(Instr.getValues()); 1461 return; 1462 } 1463 llvm_unreachable("Unhandled case in switch"); 1464 } 1465 1466 /// Emit frame instructions to describe the layout of the frame. 1467 void FrameEmitterImpl::emitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs, 1468 MCSymbol *BaseLabel) { 1469 for (const MCCFIInstruction &Instr : Instrs) { 1470 MCSymbol *Label = Instr.getLabel(); 1471 // Throw out move if the label is invalid. 1472 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code. 1473 1474 // Advance row if new location. 1475 if (BaseLabel && Label) { 1476 MCSymbol *ThisSym = Label; 1477 if (ThisSym != BaseLabel) { 1478 Streamer.emitDwarfAdvanceFrameAddr(BaseLabel, ThisSym, Instr.getLoc()); 1479 BaseLabel = ThisSym; 1480 } 1481 } 1482 1483 emitCFIInstruction(Instr); 1484 } 1485 } 1486 1487 /// Emit the unwind information in a compact way. 1488 void FrameEmitterImpl::EmitCompactUnwind(const MCDwarfFrameInfo &Frame) { 1489 MCContext &Context = Streamer.getContext(); 1490 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo(); 1491 1492 // range-start range-length compact-unwind-enc personality-func lsda 1493 // _foo LfooEnd-_foo 0x00000023 0 0 1494 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1 1495 // 1496 // .section __LD,__compact_unwind,regular,debug 1497 // 1498 // # compact unwind for _foo 1499 // .quad _foo 1500 // .set L1,LfooEnd-_foo 1501 // .long L1 1502 // .long 0x01010001 1503 // .quad 0 1504 // .quad 0 1505 // 1506 // # compact unwind for _bar 1507 // .quad _bar 1508 // .set L2,LbarEnd-_bar 1509 // .long L2 1510 // .long 0x01020011 1511 // .quad __gxx_personality 1512 // .quad except_tab1 1513 1514 uint32_t Encoding = Frame.CompactUnwindEncoding; 1515 if (!Encoding) return; 1516 bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly()); 1517 1518 // The encoding needs to know we have an LSDA. 1519 if (!DwarfEHFrameOnly && Frame.Lsda) 1520 Encoding |= 0x40000000; 1521 1522 // Range Start 1523 unsigned FDEEncoding = MOFI->getFDEEncoding(); 1524 unsigned Size = getSizeForEncoding(Streamer, FDEEncoding); 1525 Streamer.emitSymbolValue(Frame.Begin, Size); 1526 1527 // Range Length 1528 const MCExpr *Range = 1529 makeEndMinusStartExpr(Context, *Frame.Begin, *Frame.End, 0); 1530 emitAbsValue(Streamer, Range, 4); 1531 1532 // Compact Encoding 1533 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4); 1534 Streamer.emitIntValue(Encoding, Size); 1535 1536 // Personality Function 1537 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr); 1538 if (!DwarfEHFrameOnly && Frame.Personality) 1539 Streamer.emitSymbolValue(Frame.Personality, Size); 1540 else 1541 Streamer.emitIntValue(0, Size); // No personality fn 1542 1543 // LSDA 1544 Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding); 1545 if (!DwarfEHFrameOnly && Frame.Lsda) 1546 Streamer.emitSymbolValue(Frame.Lsda, Size); 1547 else 1548 Streamer.emitIntValue(0, Size); // No LSDA 1549 } 1550 1551 static unsigned getCIEVersion(bool IsEH, unsigned DwarfVersion) { 1552 if (IsEH) 1553 return 1; 1554 switch (DwarfVersion) { 1555 case 2: 1556 return 1; 1557 case 3: 1558 return 3; 1559 case 4: 1560 case 5: 1561 return 4; 1562 } 1563 llvm_unreachable("Unknown version"); 1564 } 1565 1566 const MCSymbol &FrameEmitterImpl::EmitCIE(const MCDwarfFrameInfo &Frame) { 1567 MCContext &context = Streamer.getContext(); 1568 const MCRegisterInfo *MRI = context.getRegisterInfo(); 1569 const MCObjectFileInfo *MOFI = context.getObjectFileInfo(); 1570 1571 MCSymbol *sectionStart = context.createTempSymbol(); 1572 Streamer.emitLabel(sectionStart); 1573 1574 MCSymbol *sectionEnd = context.createTempSymbol(); 1575 1576 dwarf::DwarfFormat Format = IsEH ? dwarf::DWARF32 : context.getDwarfFormat(); 1577 unsigned UnitLengthBytes = dwarf::getUnitLengthFieldByteSize(Format); 1578 unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(Format); 1579 bool IsDwarf64 = Format == dwarf::DWARF64; 1580 1581 if (IsDwarf64) 1582 // DWARF64 mark 1583 Streamer.emitInt32(dwarf::DW_LENGTH_DWARF64); 1584 1585 // Length 1586 const MCExpr *Length = makeEndMinusStartExpr(context, *sectionStart, 1587 *sectionEnd, UnitLengthBytes); 1588 emitAbsValue(Streamer, Length, OffsetSize); 1589 1590 // CIE ID 1591 uint64_t CIE_ID = 1592 IsEH ? 0 : (IsDwarf64 ? dwarf::DW64_CIE_ID : dwarf::DW_CIE_ID); 1593 Streamer.emitIntValue(CIE_ID, OffsetSize); 1594 1595 // Version 1596 uint8_t CIEVersion = getCIEVersion(IsEH, context.getDwarfVersion()); 1597 Streamer.emitInt8(CIEVersion); 1598 1599 if (IsEH) { 1600 SmallString<8> Augmentation; 1601 Augmentation += "z"; 1602 if (Frame.Personality) 1603 Augmentation += "P"; 1604 if (Frame.Lsda) 1605 Augmentation += "L"; 1606 Augmentation += "R"; 1607 if (Frame.IsSignalFrame) 1608 Augmentation += "S"; 1609 if (Frame.IsBKeyFrame) 1610 Augmentation += "B"; 1611 if (Frame.IsMTETaggedFrame) 1612 Augmentation += "G"; 1613 Streamer.emitBytes(Augmentation); 1614 } 1615 Streamer.emitInt8(0); 1616 1617 if (CIEVersion >= 4) { 1618 // Address Size 1619 Streamer.emitInt8(context.getAsmInfo()->getCodePointerSize()); 1620 1621 // Segment Descriptor Size 1622 Streamer.emitInt8(0); 1623 } 1624 1625 // Code Alignment Factor 1626 Streamer.emitULEB128IntValue(context.getAsmInfo()->getMinInstAlignment()); 1627 1628 // Data Alignment Factor 1629 Streamer.emitSLEB128IntValue(getDataAlignmentFactor(Streamer)); 1630 1631 // Return Address Register 1632 unsigned RAReg = Frame.RAReg; 1633 if (RAReg == static_cast<unsigned>(INT_MAX)) 1634 RAReg = MRI->getDwarfRegNum(MRI->getRARegister(), IsEH); 1635 1636 if (CIEVersion == 1) { 1637 assert(RAReg <= 255 && 1638 "DWARF 2 encodes return_address_register in one byte"); 1639 Streamer.emitInt8(RAReg); 1640 } else { 1641 Streamer.emitULEB128IntValue(RAReg); 1642 } 1643 1644 // Augmentation Data Length (optional) 1645 unsigned augmentationLength = 0; 1646 if (IsEH) { 1647 if (Frame.Personality) { 1648 // Personality Encoding 1649 augmentationLength += 1; 1650 // Personality 1651 augmentationLength += 1652 getSizeForEncoding(Streamer, Frame.PersonalityEncoding); 1653 } 1654 if (Frame.Lsda) 1655 augmentationLength += 1; 1656 // Encoding of the FDE pointers 1657 augmentationLength += 1; 1658 1659 Streamer.emitULEB128IntValue(augmentationLength); 1660 1661 // Augmentation Data (optional) 1662 if (Frame.Personality) { 1663 // Personality Encoding 1664 emitEncodingByte(Streamer, Frame.PersonalityEncoding); 1665 // Personality 1666 EmitPersonality(Streamer, *Frame.Personality, Frame.PersonalityEncoding); 1667 } 1668 1669 if (Frame.Lsda) 1670 emitEncodingByte(Streamer, Frame.LsdaEncoding); 1671 1672 // Encoding of the FDE pointers 1673 emitEncodingByte(Streamer, MOFI->getFDEEncoding()); 1674 } 1675 1676 // Initial Instructions 1677 1678 const MCAsmInfo *MAI = context.getAsmInfo(); 1679 if (!Frame.IsSimple) { 1680 const std::vector<MCCFIInstruction> &Instructions = 1681 MAI->getInitialFrameState(); 1682 emitCFIInstructions(Instructions, nullptr); 1683 } 1684 1685 InitialCFAOffset = CFAOffset; 1686 1687 // Padding 1688 Streamer.emitValueToAlignment(Align(IsEH ? 4 : MAI->getCodePointerSize())); 1689 1690 Streamer.emitLabel(sectionEnd); 1691 return *sectionStart; 1692 } 1693 1694 void FrameEmitterImpl::EmitFDE(const MCSymbol &cieStart, 1695 const MCDwarfFrameInfo &frame, 1696 bool LastInSection, 1697 const MCSymbol &SectionStart) { 1698 MCContext &context = Streamer.getContext(); 1699 MCSymbol *fdeStart = context.createTempSymbol(); 1700 MCSymbol *fdeEnd = context.createTempSymbol(); 1701 const MCObjectFileInfo *MOFI = context.getObjectFileInfo(); 1702 1703 CFAOffset = InitialCFAOffset; 1704 1705 dwarf::DwarfFormat Format = IsEH ? dwarf::DWARF32 : context.getDwarfFormat(); 1706 unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(Format); 1707 1708 if (Format == dwarf::DWARF64) 1709 // DWARF64 mark 1710 Streamer.emitInt32(dwarf::DW_LENGTH_DWARF64); 1711 1712 // Length 1713 const MCExpr *Length = makeEndMinusStartExpr(context, *fdeStart, *fdeEnd, 0); 1714 emitAbsValue(Streamer, Length, OffsetSize); 1715 1716 Streamer.emitLabel(fdeStart); 1717 1718 // CIE Pointer 1719 const MCAsmInfo *asmInfo = context.getAsmInfo(); 1720 if (IsEH) { 1721 const MCExpr *offset = 1722 makeEndMinusStartExpr(context, cieStart, *fdeStart, 0); 1723 emitAbsValue(Streamer, offset, OffsetSize); 1724 } else if (!asmInfo->doesDwarfUseRelocationsAcrossSections()) { 1725 const MCExpr *offset = 1726 makeEndMinusStartExpr(context, SectionStart, cieStart, 0); 1727 emitAbsValue(Streamer, offset, OffsetSize); 1728 } else { 1729 Streamer.emitSymbolValue(&cieStart, OffsetSize, 1730 asmInfo->needsDwarfSectionOffsetDirective()); 1731 } 1732 1733 // PC Begin 1734 unsigned PCEncoding = 1735 IsEH ? MOFI->getFDEEncoding() : (unsigned)dwarf::DW_EH_PE_absptr; 1736 unsigned PCSize = getSizeForEncoding(Streamer, PCEncoding); 1737 emitFDESymbol(Streamer, *frame.Begin, PCEncoding, IsEH); 1738 1739 // PC Range 1740 const MCExpr *Range = 1741 makeEndMinusStartExpr(context, *frame.Begin, *frame.End, 0); 1742 emitAbsValue(Streamer, Range, PCSize); 1743 1744 if (IsEH) { 1745 // Augmentation Data Length 1746 unsigned augmentationLength = 0; 1747 1748 if (frame.Lsda) 1749 augmentationLength += getSizeForEncoding(Streamer, frame.LsdaEncoding); 1750 1751 Streamer.emitULEB128IntValue(augmentationLength); 1752 1753 // Augmentation Data 1754 if (frame.Lsda) 1755 emitFDESymbol(Streamer, *frame.Lsda, frame.LsdaEncoding, true); 1756 } 1757 1758 // Call Frame Instructions 1759 emitCFIInstructions(frame.Instructions, frame.Begin); 1760 1761 // Padding 1762 // The size of a .eh_frame section has to be a multiple of the alignment 1763 // since a null CIE is interpreted as the end. Old systems overaligned 1764 // .eh_frame, so we do too and account for it in the last FDE. 1765 unsigned Alignment = LastInSection ? asmInfo->getCodePointerSize() : PCSize; 1766 Streamer.emitValueToAlignment(Align(Alignment)); 1767 1768 Streamer.emitLabel(fdeEnd); 1769 } 1770 1771 namespace { 1772 1773 struct CIEKey { 1774 static const CIEKey getEmptyKey() { 1775 return CIEKey(nullptr, 0, -1, false, false, static_cast<unsigned>(INT_MAX), 1776 false, false); 1777 } 1778 1779 static const CIEKey getTombstoneKey() { 1780 return CIEKey(nullptr, -1, 0, false, false, static_cast<unsigned>(INT_MAX), 1781 false, false); 1782 } 1783 1784 CIEKey(const MCSymbol *Personality, unsigned PersonalityEncoding, 1785 unsigned LSDAEncoding, bool IsSignalFrame, bool IsSimple, 1786 unsigned RAReg, bool IsBKeyFrame, bool IsMTETaggedFrame) 1787 : Personality(Personality), PersonalityEncoding(PersonalityEncoding), 1788 LsdaEncoding(LSDAEncoding), IsSignalFrame(IsSignalFrame), 1789 IsSimple(IsSimple), RAReg(RAReg), IsBKeyFrame(IsBKeyFrame), 1790 IsMTETaggedFrame(IsMTETaggedFrame) {} 1791 1792 explicit CIEKey(const MCDwarfFrameInfo &Frame) 1793 : Personality(Frame.Personality), 1794 PersonalityEncoding(Frame.PersonalityEncoding), 1795 LsdaEncoding(Frame.LsdaEncoding), IsSignalFrame(Frame.IsSignalFrame), 1796 IsSimple(Frame.IsSimple), RAReg(Frame.RAReg), 1797 IsBKeyFrame(Frame.IsBKeyFrame), 1798 IsMTETaggedFrame(Frame.IsMTETaggedFrame) {} 1799 1800 StringRef PersonalityName() const { 1801 if (!Personality) 1802 return StringRef(); 1803 return Personality->getName(); 1804 } 1805 1806 bool operator<(const CIEKey &Other) const { 1807 return std::make_tuple(PersonalityName(), PersonalityEncoding, LsdaEncoding, 1808 IsSignalFrame, IsSimple, RAReg, IsBKeyFrame, 1809 IsMTETaggedFrame) < 1810 std::make_tuple(Other.PersonalityName(), Other.PersonalityEncoding, 1811 Other.LsdaEncoding, Other.IsSignalFrame, 1812 Other.IsSimple, Other.RAReg, Other.IsBKeyFrame, 1813 Other.IsMTETaggedFrame); 1814 } 1815 1816 const MCSymbol *Personality; 1817 unsigned PersonalityEncoding; 1818 unsigned LsdaEncoding; 1819 bool IsSignalFrame; 1820 bool IsSimple; 1821 unsigned RAReg; 1822 bool IsBKeyFrame; 1823 bool IsMTETaggedFrame; 1824 }; 1825 1826 } // end anonymous namespace 1827 1828 namespace llvm { 1829 1830 template <> struct DenseMapInfo<CIEKey> { 1831 static CIEKey getEmptyKey() { return CIEKey::getEmptyKey(); } 1832 static CIEKey getTombstoneKey() { return CIEKey::getTombstoneKey(); } 1833 1834 static unsigned getHashValue(const CIEKey &Key) { 1835 return static_cast<unsigned>( 1836 hash_combine(Key.Personality, Key.PersonalityEncoding, Key.LsdaEncoding, 1837 Key.IsSignalFrame, Key.IsSimple, Key.RAReg, 1838 Key.IsBKeyFrame, Key.IsMTETaggedFrame)); 1839 } 1840 1841 static bool isEqual(const CIEKey &LHS, const CIEKey &RHS) { 1842 return LHS.Personality == RHS.Personality && 1843 LHS.PersonalityEncoding == RHS.PersonalityEncoding && 1844 LHS.LsdaEncoding == RHS.LsdaEncoding && 1845 LHS.IsSignalFrame == RHS.IsSignalFrame && 1846 LHS.IsSimple == RHS.IsSimple && LHS.RAReg == RHS.RAReg && 1847 LHS.IsBKeyFrame == RHS.IsBKeyFrame && 1848 LHS.IsMTETaggedFrame == RHS.IsMTETaggedFrame; 1849 } 1850 }; 1851 1852 } // end namespace llvm 1853 1854 void MCDwarfFrameEmitter::Emit(MCObjectStreamer &Streamer, MCAsmBackend *MAB, 1855 bool IsEH) { 1856 MCContext &Context = Streamer.getContext(); 1857 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo(); 1858 const MCAsmInfo *AsmInfo = Context.getAsmInfo(); 1859 FrameEmitterImpl Emitter(IsEH, Streamer); 1860 ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getDwarfFrameInfos(); 1861 1862 // Emit the compact unwind info if available. 1863 bool NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame(); 1864 if (IsEH && MOFI->getCompactUnwindSection()) { 1865 Streamer.generateCompactUnwindEncodings(MAB); 1866 bool SectionEmitted = false; 1867 for (const MCDwarfFrameInfo &Frame : FrameArray) { 1868 if (Frame.CompactUnwindEncoding == 0) continue; 1869 if (!SectionEmitted) { 1870 Streamer.switchSection(MOFI->getCompactUnwindSection()); 1871 Streamer.emitValueToAlignment(Align(AsmInfo->getCodePointerSize())); 1872 SectionEmitted = true; 1873 } 1874 NeedsEHFrameSection |= 1875 Frame.CompactUnwindEncoding == 1876 MOFI->getCompactUnwindDwarfEHFrameOnly(); 1877 Emitter.EmitCompactUnwind(Frame); 1878 } 1879 } 1880 1881 // Compact unwind information can be emitted in the eh_frame section or the 1882 // debug_frame section. Skip emitting FDEs and CIEs when the compact unwind 1883 // doesn't need an eh_frame section and the emission location is the eh_frame 1884 // section. 1885 if (!NeedsEHFrameSection && IsEH) return; 1886 1887 MCSection &Section = 1888 IsEH ? *const_cast<MCObjectFileInfo *>(MOFI)->getEHFrameSection() 1889 : *MOFI->getDwarfFrameSection(); 1890 1891 Streamer.switchSection(&Section); 1892 MCSymbol *SectionStart = Context.createTempSymbol(); 1893 Streamer.emitLabel(SectionStart); 1894 1895 DenseMap<CIEKey, const MCSymbol *> CIEStarts; 1896 1897 const MCSymbol *DummyDebugKey = nullptr; 1898 bool CanOmitDwarf = MOFI->getOmitDwarfIfHaveCompactUnwind(); 1899 // Sort the FDEs by their corresponding CIE before we emit them. 1900 // This isn't technically necessary according to the DWARF standard, 1901 // but the Android libunwindstack rejects eh_frame sections where 1902 // an FDE refers to a CIE other than the closest previous CIE. 1903 std::vector<MCDwarfFrameInfo> FrameArrayX(FrameArray.begin(), FrameArray.end()); 1904 llvm::stable_sort(FrameArrayX, 1905 [](const MCDwarfFrameInfo &X, const MCDwarfFrameInfo &Y) { 1906 return CIEKey(X) < CIEKey(Y); 1907 }); 1908 for (auto I = FrameArrayX.begin(), E = FrameArrayX.end(); I != E;) { 1909 const MCDwarfFrameInfo &Frame = *I; 1910 ++I; 1911 if (CanOmitDwarf && Frame.CompactUnwindEncoding != 1912 MOFI->getCompactUnwindDwarfEHFrameOnly() && IsEH) 1913 // CIEs and FDEs can be emitted in either the eh_frame section or the 1914 // debug_frame section, on some platforms (e.g. AArch64) the target object 1915 // file supports emitting a compact_unwind section without an associated 1916 // eh_frame section. If the eh_frame section is not needed, and the 1917 // location where the CIEs and FDEs are to be emitted is the eh_frame 1918 // section, do not emit anything. 1919 continue; 1920 1921 CIEKey Key(Frame); 1922 const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey; 1923 if (!CIEStart) 1924 CIEStart = &Emitter.EmitCIE(Frame); 1925 1926 Emitter.EmitFDE(*CIEStart, Frame, I == E, *SectionStart); 1927 } 1928 } 1929 1930 void MCDwarfFrameEmitter::encodeAdvanceLoc(MCContext &Context, 1931 uint64_t AddrDelta, 1932 SmallVectorImpl<char> &Out) { 1933 // Scale the address delta by the minimum instruction length. 1934 AddrDelta = ScaleAddrDelta(Context, AddrDelta); 1935 if (AddrDelta == 0) 1936 return; 1937 1938 llvm::endianness E = Context.getAsmInfo()->isLittleEndian() 1939 ? llvm::endianness::little 1940 : llvm::endianness::big; 1941 1942 if (isUIntN(6, AddrDelta)) { 1943 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta; 1944 Out.push_back(Opcode); 1945 } else if (isUInt<8>(AddrDelta)) { 1946 Out.push_back(dwarf::DW_CFA_advance_loc1); 1947 Out.push_back(AddrDelta); 1948 } else if (isUInt<16>(AddrDelta)) { 1949 Out.push_back(dwarf::DW_CFA_advance_loc2); 1950 support::endian::write<uint16_t>(Out, AddrDelta, E); 1951 } else { 1952 assert(isUInt<32>(AddrDelta)); 1953 Out.push_back(dwarf::DW_CFA_advance_loc4); 1954 support::endian::write<uint32_t>(Out, AddrDelta, E); 1955 } 1956 } 1957