1 //===- lib/MC/MCDwarf.cpp - MCDwarf implementation ------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 #include "llvm/MC/MCDwarf.h" 11 #include "llvm/MC/MCAsmInfo.h" 12 #include "llvm/MC/MCContext.h" 13 #include "llvm/MC/MCObjectFileInfo.h" 14 #include "llvm/MC/MCObjectWriter.h" 15 #include "llvm/MC/MCRegisterInfo.h" 16 #include "llvm/MC/MCStreamer.h" 17 #include "llvm/MC/MCSymbol.h" 18 #include "llvm/MC/MCExpr.h" 19 #include "llvm/Support/Debug.h" 20 #include "llvm/Support/ErrorHandling.h" 21 #include "llvm/Support/raw_ostream.h" 22 #include "llvm/Support/LEB128.h" 23 #include "llvm/Support/Path.h" 24 #include "llvm/Support/SourceMgr.h" 25 #include "llvm/ADT/Hashing.h" 26 #include "llvm/ADT/SmallString.h" 27 #include "llvm/ADT/Twine.h" 28 #include "llvm/Config/config.h" 29 using namespace llvm; 30 31 // Given a special op, return the address skip amount (in units of 32 // DWARF2_LINE_MIN_INSN_LENGTH. 33 #define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE) 34 35 // The maximum address skip amount that can be encoded with a special op. 36 #define MAX_SPECIAL_ADDR_DELTA SPECIAL_ADDR(255) 37 38 // First special line opcode - leave room for the standard opcodes. 39 // Note: If you want to change this, you'll have to update the 40 // "standard_opcode_lengths" table that is emitted in DwarfFileTable::Emit(). 41 #define DWARF2_LINE_OPCODE_BASE 13 42 43 // Minimum line offset in a special line info. opcode. This value 44 // was chosen to give a reasonable range of values. 45 #define DWARF2_LINE_BASE -5 46 47 // Range of line offsets in a special line info. opcode. 48 #define DWARF2_LINE_RANGE 14 49 50 // Define the architecture-dependent minimum instruction length (in bytes). 51 // This value should be rather too small than too big. 52 #define DWARF2_LINE_MIN_INSN_LENGTH 1 53 54 // Note: when DWARF2_LINE_MIN_INSN_LENGTH == 1 which is the current setting, 55 // this routine is a nop and will be optimized away. 56 static inline uint64_t ScaleAddrDelta(uint64_t AddrDelta) { 57 if (DWARF2_LINE_MIN_INSN_LENGTH == 1) 58 return AddrDelta; 59 if (AddrDelta % DWARF2_LINE_MIN_INSN_LENGTH != 0) { 60 // TODO: report this error, but really only once. 61 ; 62 } 63 return AddrDelta / DWARF2_LINE_MIN_INSN_LENGTH; 64 } 65 66 // 67 // This is called when an instruction is assembled into the specified section 68 // and if there is information from the last .loc directive that has yet to have 69 // a line entry made for it is made. 70 // 71 void MCLineEntry::Make(MCStreamer *MCOS, const MCSection *Section) { 72 if (!MCOS->getContext().getDwarfLocSeen()) 73 return; 74 75 // Create a symbol at in the current section for use in the line entry. 76 MCSymbol *LineSym = MCOS->getContext().CreateTempSymbol(); 77 // Set the value of the symbol to use for the MCLineEntry. 78 MCOS->EmitLabel(LineSym); 79 80 // Get the current .loc info saved in the context. 81 const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc(); 82 83 // Create a (local) line entry with the symbol and the current .loc info. 84 MCLineEntry LineEntry(LineSym, DwarfLoc); 85 86 // clear DwarfLocSeen saying the current .loc info is now used. 87 MCOS->getContext().ClearDwarfLocSeen(); 88 89 // Get the MCLineSection for this section, if one does not exist for this 90 // section create it. 91 const DenseMap<const MCSection *, MCLineSection *> &MCLineSections = 92 MCOS->getContext().getMCLineSections(); 93 MCLineSection *LineSection = MCLineSections.lookup(Section); 94 if (!LineSection) { 95 // Create a new MCLineSection. This will be deleted after the dwarf line 96 // table is created using it by iterating through the MCLineSections 97 // DenseMap. 98 LineSection = new MCLineSection; 99 // Save a pointer to the new LineSection into the MCLineSections DenseMap. 100 MCOS->getContext().addMCLineSection(Section, LineSection); 101 } 102 103 // Add the line entry to this section's entries. 104 LineSection->addLineEntry(LineEntry); 105 } 106 107 // 108 // This helper routine returns an expression of End - Start + IntVal . 109 // 110 static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS, 111 const MCSymbol &Start, 112 const MCSymbol &End, 113 int IntVal) { 114 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None; 115 const MCExpr *Res = 116 MCSymbolRefExpr::Create(&End, Variant, MCOS.getContext()); 117 const MCExpr *RHS = 118 MCSymbolRefExpr::Create(&Start, Variant, MCOS.getContext()); 119 const MCExpr *Res1 = 120 MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext()); 121 const MCExpr *Res2 = 122 MCConstantExpr::Create(IntVal, MCOS.getContext()); 123 const MCExpr *Res3 = 124 MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext()); 125 return Res3; 126 } 127 128 // 129 // This emits the Dwarf line table for the specified section from the entries 130 // in the LineSection. 131 // 132 static inline void EmitDwarfLineTable(MCStreamer *MCOS, 133 const MCSection *Section, 134 const MCLineSection *LineSection) { 135 unsigned FileNum = 1; 136 unsigned LastLine = 1; 137 unsigned Column = 0; 138 unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0; 139 unsigned Isa = 0; 140 MCSymbol *LastLabel = NULL; 141 142 // Loop through each MCLineEntry and encode the dwarf line number table. 143 for (MCLineSection::const_iterator 144 it = LineSection->getMCLineEntries()->begin(), 145 ie = LineSection->getMCLineEntries()->end(); it != ie; ++it) { 146 147 if (FileNum != it->getFileNum()) { 148 FileNum = it->getFileNum(); 149 MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1); 150 MCOS->EmitULEB128IntValue(FileNum); 151 } 152 if (Column != it->getColumn()) { 153 Column = it->getColumn(); 154 MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1); 155 MCOS->EmitULEB128IntValue(Column); 156 } 157 if (Isa != it->getIsa()) { 158 Isa = it->getIsa(); 159 MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1); 160 MCOS->EmitULEB128IntValue(Isa); 161 } 162 if ((it->getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) { 163 Flags = it->getFlags(); 164 MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1); 165 } 166 if (it->getFlags() & DWARF2_FLAG_BASIC_BLOCK) 167 MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1); 168 if (it->getFlags() & DWARF2_FLAG_PROLOGUE_END) 169 MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1); 170 if (it->getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN) 171 MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1); 172 173 int64_t LineDelta = static_cast<int64_t>(it->getLine()) - LastLine; 174 MCSymbol *Label = it->getLabel(); 175 176 // At this point we want to emit/create the sequence to encode the delta in 177 // line numbers and the increment of the address from the previous Label 178 // and the current Label. 179 const MCAsmInfo &asmInfo = MCOS->getContext().getAsmInfo(); 180 MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label, 181 asmInfo.getPointerSize()); 182 183 LastLine = it->getLine(); 184 LastLabel = Label; 185 } 186 187 // Emit a DW_LNE_end_sequence for the end of the section. 188 // Using the pointer Section create a temporary label at the end of the 189 // section and use that and the LastLabel to compute the address delta 190 // and use INT64_MAX as the line delta which is the signal that this is 191 // actually a DW_LNE_end_sequence. 192 193 // Switch to the section to be able to create a symbol at its end. 194 MCOS->SwitchSection(Section); 195 196 MCContext &context = MCOS->getContext(); 197 // Create a symbol at the end of the section. 198 MCSymbol *SectionEnd = context.CreateTempSymbol(); 199 // Set the value of the symbol, as we are at the end of the section. 200 MCOS->EmitLabel(SectionEnd); 201 202 // Switch back the dwarf line section. 203 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection()); 204 205 const MCAsmInfo &asmInfo = MCOS->getContext().getAsmInfo(); 206 MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd, 207 asmInfo.getPointerSize()); 208 } 209 210 // 211 // This emits the Dwarf file and the line tables. 212 // 213 const MCSymbol *MCDwarfFileTable::Emit(MCStreamer *MCOS) { 214 MCContext &context = MCOS->getContext(); 215 // Switch to the section where the table will be emitted into. 216 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection()); 217 218 // Create a symbol at the beginning of this section. 219 MCSymbol *LineStartSym = context.CreateTempSymbol(); 220 // Set the value of the symbol, as we are at the start of the section. 221 MCOS->EmitLabel(LineStartSym); 222 223 // Create a symbol for the end of the section (to be set when we get there). 224 MCSymbol *LineEndSym = context.CreateTempSymbol(); 225 226 // The first 4 bytes is the total length of the information for this 227 // compilation unit (not including these 4 bytes for the length). 228 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym,4), 229 4); 230 231 // Next 2 bytes is the Version, which is Dwarf 2. 232 MCOS->EmitIntValue(2, 2); 233 234 // Create a symbol for the end of the prologue (to be set when we get there). 235 MCSymbol *ProEndSym = context.CreateTempSymbol(); // Lprologue_end 236 237 // Length of the prologue, is the next 4 bytes. Which is the start of the 238 // section to the end of the prologue. Not including the 4 bytes for the 239 // total length, the 2 bytes for the version, and these 4 bytes for the 240 // length of the prologue. 241 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym, 242 (4 + 2 + 4)), 243 4, 0); 244 245 // Parameters of the state machine, are next. 246 MCOS->EmitIntValue(DWARF2_LINE_MIN_INSN_LENGTH, 1); 247 MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1); 248 MCOS->EmitIntValue(DWARF2_LINE_BASE, 1); 249 MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1); 250 MCOS->EmitIntValue(DWARF2_LINE_OPCODE_BASE, 1); 251 252 // Standard opcode lengths 253 MCOS->EmitIntValue(0, 1); // length of DW_LNS_copy 254 MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_pc 255 MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_line 256 MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_file 257 MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_column 258 MCOS->EmitIntValue(0, 1); // length of DW_LNS_negate_stmt 259 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_basic_block 260 MCOS->EmitIntValue(0, 1); // length of DW_LNS_const_add_pc 261 MCOS->EmitIntValue(1, 1); // length of DW_LNS_fixed_advance_pc 262 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_prologue_end 263 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_epilogue_begin 264 MCOS->EmitIntValue(1, 1); // DW_LNS_set_isa 265 266 // Put out the directory and file tables. 267 268 // First the directory table. 269 const std::vector<StringRef> &MCDwarfDirs = 270 context.getMCDwarfDirs(); 271 for (unsigned i = 0; i < MCDwarfDirs.size(); i++) { 272 MCOS->EmitBytes(MCDwarfDirs[i], 0); // the DirectoryName 273 MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string 274 } 275 MCOS->EmitIntValue(0, 1); // Terminate the directory list 276 277 // Second the file table. 278 const std::vector<MCDwarfFile *> &MCDwarfFiles = 279 MCOS->getContext().getMCDwarfFiles(); 280 for (unsigned i = 1; i < MCDwarfFiles.size(); i++) { 281 MCOS->EmitBytes(MCDwarfFiles[i]->getName(), 0); // FileName 282 MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string 283 // the Directory num 284 MCOS->EmitULEB128IntValue(MCDwarfFiles[i]->getDirIndex()); 285 MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0) 286 MCOS->EmitIntValue(0, 1); // filesize (always 0) 287 } 288 MCOS->EmitIntValue(0, 1); // Terminate the file list 289 290 // This is the end of the prologue, so set the value of the symbol at the 291 // end of the prologue (that was used in a previous expression). 292 MCOS->EmitLabel(ProEndSym); 293 294 // Put out the line tables. 295 const DenseMap<const MCSection *, MCLineSection *> &MCLineSections = 296 MCOS->getContext().getMCLineSections(); 297 const std::vector<const MCSection *> &MCLineSectionOrder = 298 MCOS->getContext().getMCLineSectionOrder(); 299 for (std::vector<const MCSection*>::const_iterator it = 300 MCLineSectionOrder.begin(), ie = MCLineSectionOrder.end(); it != ie; 301 ++it) { 302 const MCSection *Sec = *it; 303 const MCLineSection *Line = MCLineSections.lookup(Sec); 304 EmitDwarfLineTable(MCOS, Sec, Line); 305 306 // Now delete the MCLineSections that were created in MCLineEntry::Make() 307 // and used to emit the line table. 308 delete Line; 309 } 310 311 if (MCOS->getContext().getAsmInfo().getLinkerRequiresNonEmptyDwarfLines() 312 && MCLineSectionOrder.begin() == MCLineSectionOrder.end()) { 313 // The darwin9 linker has a bug (see PR8715). For for 32-bit architectures 314 // it requires: 315 // total_length >= prologue_length + 10 316 // We are 4 bytes short, since we have total_length = 51 and 317 // prologue_length = 45 318 319 // The regular end_sequence should be sufficient. 320 MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0); 321 } 322 323 // This is the end of the section, so set the value of the symbol at the end 324 // of this section (that was used in a previous expression). 325 MCOS->EmitLabel(LineEndSym); 326 327 return LineStartSym; 328 } 329 330 /// Utility function to write the encoding to an object writer. 331 void MCDwarfLineAddr::Write(MCObjectWriter *OW, int64_t LineDelta, 332 uint64_t AddrDelta) { 333 SmallString<256> Tmp; 334 raw_svector_ostream OS(Tmp); 335 MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS); 336 OW->WriteBytes(OS.str()); 337 } 338 339 /// Utility function to emit the encoding to a streamer. 340 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta, 341 uint64_t AddrDelta) { 342 SmallString<256> Tmp; 343 raw_svector_ostream OS(Tmp); 344 MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS); 345 MCOS->EmitBytes(OS.str(), /*AddrSpace=*/0); 346 } 347 348 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas. 349 void MCDwarfLineAddr::Encode(int64_t LineDelta, uint64_t AddrDelta, 350 raw_ostream &OS) { 351 uint64_t Temp, Opcode; 352 bool NeedCopy = false; 353 354 // Scale the address delta by the minimum instruction length. 355 AddrDelta = ScaleAddrDelta(AddrDelta); 356 357 // A LineDelta of INT64_MAX is a signal that this is actually a 358 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the 359 // end_sequence to emit the matrix entry. 360 if (LineDelta == INT64_MAX) { 361 if (AddrDelta == MAX_SPECIAL_ADDR_DELTA) 362 OS << char(dwarf::DW_LNS_const_add_pc); 363 else { 364 OS << char(dwarf::DW_LNS_advance_pc); 365 encodeULEB128(AddrDelta, OS); 366 } 367 OS << char(dwarf::DW_LNS_extended_op); 368 OS << char(1); 369 OS << char(dwarf::DW_LNE_end_sequence); 370 return; 371 } 372 373 // Bias the line delta by the base. 374 Temp = LineDelta - DWARF2_LINE_BASE; 375 376 // If the line increment is out of range of a special opcode, we must encode 377 // it with DW_LNS_advance_line. 378 if (Temp >= DWARF2_LINE_RANGE) { 379 OS << char(dwarf::DW_LNS_advance_line); 380 encodeSLEB128(LineDelta, OS); 381 382 LineDelta = 0; 383 Temp = 0 - DWARF2_LINE_BASE; 384 NeedCopy = true; 385 } 386 387 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode. 388 if (LineDelta == 0 && AddrDelta == 0) { 389 OS << char(dwarf::DW_LNS_copy); 390 return; 391 } 392 393 // Bias the opcode by the special opcode base. 394 Temp += DWARF2_LINE_OPCODE_BASE; 395 396 // Avoid overflow when addr_delta is large. 397 if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) { 398 // Try using a special opcode. 399 Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE; 400 if (Opcode <= 255) { 401 OS << char(Opcode); 402 return; 403 } 404 405 // Try using DW_LNS_const_add_pc followed by special op. 406 Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE; 407 if (Opcode <= 255) { 408 OS << char(dwarf::DW_LNS_const_add_pc); 409 OS << char(Opcode); 410 return; 411 } 412 } 413 414 // Otherwise use DW_LNS_advance_pc. 415 OS << char(dwarf::DW_LNS_advance_pc); 416 encodeULEB128(AddrDelta, OS); 417 418 if (NeedCopy) 419 OS << char(dwarf::DW_LNS_copy); 420 else 421 OS << char(Temp); 422 } 423 424 void MCDwarfFile::print(raw_ostream &OS) const { 425 OS << '"' << getName() << '"'; 426 } 427 428 #ifndef NDEBUG 429 void MCDwarfFile::dump() const { 430 print(dbgs()); 431 } 432 #endif 433 434 // Utility function to write a tuple for .debug_abbrev. 435 static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) { 436 MCOS->EmitULEB128IntValue(Name); 437 MCOS->EmitULEB128IntValue(Form); 438 } 439 440 // When generating dwarf for assembly source files this emits 441 // the data for .debug_abbrev section which contains three DIEs. 442 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) { 443 MCContext &context = MCOS->getContext(); 444 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection()); 445 446 // DW_TAG_compile_unit DIE abbrev (1). 447 MCOS->EmitULEB128IntValue(1); 448 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit); 449 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1); 450 EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4); 451 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr); 452 EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr); 453 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string); 454 EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string); 455 StringRef DwarfDebugFlags = context.getDwarfDebugFlags(); 456 if (!DwarfDebugFlags.empty()) 457 EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string); 458 EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string); 459 EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2); 460 EmitAbbrev(MCOS, 0, 0); 461 462 // DW_TAG_label DIE abbrev (2). 463 MCOS->EmitULEB128IntValue(2); 464 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_label); 465 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1); 466 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string); 467 EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4); 468 EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4); 469 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr); 470 EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag); 471 EmitAbbrev(MCOS, 0, 0); 472 473 // DW_TAG_unspecified_parameters DIE abbrev (3). 474 MCOS->EmitULEB128IntValue(3); 475 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters); 476 MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1); 477 EmitAbbrev(MCOS, 0, 0); 478 479 // Terminate the abbreviations for this compilation unit. 480 MCOS->EmitIntValue(0, 1); 481 } 482 483 // When generating dwarf for assembly source files this emits the data for 484 // .debug_aranges section. Which contains a header and a table of pairs of 485 // PointerSize'ed values for the address and size of section(s) with line table 486 // entries (just the default .text in our case) and a terminating pair of zeros. 487 static void EmitGenDwarfAranges(MCStreamer *MCOS) { 488 MCContext &context = MCOS->getContext(); 489 490 // Create a symbol at the end of the section that we are creating the dwarf 491 // debugging info to use later in here as part of the expression to calculate 492 // the size of the section for the table. 493 MCOS->SwitchSection(context.getGenDwarfSection()); 494 MCSymbol *SectionEndSym = context.CreateTempSymbol(); 495 MCOS->EmitLabel(SectionEndSym); 496 context.setGenDwarfSectionEndSym(SectionEndSym); 497 498 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection()); 499 500 // This will be the length of the .debug_aranges section, first account for 501 // the size of each item in the header (see below where we emit these items). 502 int Length = 4 + 2 + 4 + 1 + 1; 503 504 // Figure the padding after the header before the table of address and size 505 // pairs who's values are PointerSize'ed. 506 const MCAsmInfo &asmInfo = context.getAsmInfo(); 507 int AddrSize = asmInfo.getPointerSize(); 508 int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1)); 509 if (Pad == 2 * AddrSize) 510 Pad = 0; 511 Length += Pad; 512 513 // Add the size of the pair of PointerSize'ed values for the address and size 514 // of the one default .text section we have in the table. 515 Length += 2 * AddrSize; 516 // And the pair of terminating zeros. 517 Length += 2 * AddrSize; 518 519 520 // Emit the header for this section. 521 // The 4 byte length not including the 4 byte value for the length. 522 MCOS->EmitIntValue(Length - 4, 4); 523 // The 2 byte version, which is 2. 524 MCOS->EmitIntValue(2, 2); 525 // The 4 byte offset to the compile unit in the .debug_info from the start 526 // of the .debug_info, it is at the start of that section so this is zero. 527 MCOS->EmitIntValue(0, 4); 528 // The 1 byte size of an address. 529 MCOS->EmitIntValue(AddrSize, 1); 530 // The 1 byte size of a segment descriptor, we use a value of zero. 531 MCOS->EmitIntValue(0, 1); 532 // Align the header with the padding if needed, before we put out the table. 533 for(int i = 0; i < Pad; i++) 534 MCOS->EmitIntValue(0, 1); 535 536 // Now emit the table of pairs of PointerSize'ed values for the section(s) 537 // address and size, in our case just the one default .text section. 538 const MCExpr *Addr = MCSymbolRefExpr::Create( 539 context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context); 540 const MCExpr *Size = MakeStartMinusEndExpr(*MCOS, 541 *context.getGenDwarfSectionStartSym(), *SectionEndSym, 0); 542 MCOS->EmitAbsValue(Addr, AddrSize); 543 MCOS->EmitAbsValue(Size, AddrSize); 544 545 // And finally the pair of terminating zeros. 546 MCOS->EmitIntValue(0, AddrSize); 547 MCOS->EmitIntValue(0, AddrSize); 548 } 549 550 // When generating dwarf for assembly source files this emits the data for 551 // .debug_info section which contains three parts. The header, the compile_unit 552 // DIE and a list of label DIEs. 553 static void EmitGenDwarfInfo(MCStreamer *MCOS, 554 const MCSymbol *AbbrevSectionSymbol, 555 const MCSymbol *LineSectionSymbol) { 556 MCContext &context = MCOS->getContext(); 557 558 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection()); 559 560 // Create a symbol at the start and end of this section used in here for the 561 // expression to calculate the length in the header. 562 MCSymbol *InfoStart = context.CreateTempSymbol(); 563 MCOS->EmitLabel(InfoStart); 564 MCSymbol *InfoEnd = context.CreateTempSymbol(); 565 566 // First part: the header. 567 568 // The 4 byte total length of the information for this compilation unit, not 569 // including these 4 bytes. 570 const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4); 571 MCOS->EmitAbsValue(Length, 4); 572 573 // The 2 byte DWARF version, which is 2. 574 MCOS->EmitIntValue(2, 2); 575 576 // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev, 577 // it is at the start of that section so this is zero. 578 if (AbbrevSectionSymbol) { 579 MCOS->EmitSymbolValue(AbbrevSectionSymbol, 4); 580 } else { 581 MCOS->EmitIntValue(0, 4); 582 } 583 584 const MCAsmInfo &asmInfo = context.getAsmInfo(); 585 int AddrSize = asmInfo.getPointerSize(); 586 // The 1 byte size of an address. 587 MCOS->EmitIntValue(AddrSize, 1); 588 589 // Second part: the compile_unit DIE. 590 591 // The DW_TAG_compile_unit DIE abbrev (1). 592 MCOS->EmitULEB128IntValue(1); 593 594 // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section, 595 // which is at the start of that section so this is zero. 596 if (LineSectionSymbol) { 597 MCOS->EmitSymbolValue(LineSectionSymbol, 4); 598 } else { 599 MCOS->EmitIntValue(0, 4); 600 } 601 602 // AT_low_pc, the first address of the default .text section. 603 const MCExpr *Start = MCSymbolRefExpr::Create( 604 context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context); 605 MCOS->EmitAbsValue(Start, AddrSize); 606 607 // AT_high_pc, the last address of the default .text section. 608 const MCExpr *End = MCSymbolRefExpr::Create( 609 context.getGenDwarfSectionEndSym(), MCSymbolRefExpr::VK_None, context); 610 MCOS->EmitAbsValue(End, AddrSize); 611 612 // AT_name, the name of the source file. Reconstruct from the first directory 613 // and file table entries. 614 const std::vector<StringRef> &MCDwarfDirs = 615 context.getMCDwarfDirs(); 616 if (MCDwarfDirs.size() > 0) { 617 MCOS->EmitBytes(MCDwarfDirs[0], 0); 618 MCOS->EmitBytes("/", 0); 619 } 620 const std::vector<MCDwarfFile *> &MCDwarfFiles = 621 MCOS->getContext().getMCDwarfFiles(); 622 MCOS->EmitBytes(MCDwarfFiles[1]->getName(), 0); 623 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. 624 625 // AT_comp_dir, the working directory the assembly was done in. 626 llvm::sys::Path CWD = llvm::sys::Path::GetCurrentDirectory(); 627 MCOS->EmitBytes(StringRef(CWD.c_str()), 0); 628 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. 629 630 // AT_APPLE_flags, the command line arguments of the assembler tool. 631 StringRef DwarfDebugFlags = context.getDwarfDebugFlags(); 632 if (!DwarfDebugFlags.empty()){ 633 MCOS->EmitBytes(DwarfDebugFlags, 0); 634 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. 635 } 636 637 // AT_producer, the version of the assembler tool. 638 MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM "), 0); 639 MCOS->EmitBytes(StringRef(PACKAGE_VERSION), 0); 640 MCOS->EmitBytes(StringRef(")"), 0); 641 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. 642 643 // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2 644 // draft has no standard code for assembler. 645 MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2); 646 647 // Third part: the list of label DIEs. 648 649 // Loop on saved info for dwarf labels and create the DIEs for them. 650 const std::vector<const MCGenDwarfLabelEntry *> &Entries = 651 MCOS->getContext().getMCGenDwarfLabelEntries(); 652 for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it = 653 Entries.begin(), ie = Entries.end(); it != ie; 654 ++it) { 655 const MCGenDwarfLabelEntry *Entry = *it; 656 657 // The DW_TAG_label DIE abbrev (2). 658 MCOS->EmitULEB128IntValue(2); 659 660 // AT_name, of the label without any leading underbar. 661 MCOS->EmitBytes(Entry->getName(), 0); 662 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. 663 664 // AT_decl_file, index into the file table. 665 MCOS->EmitIntValue(Entry->getFileNumber(), 4); 666 667 // AT_decl_line, source line number. 668 MCOS->EmitIntValue(Entry->getLineNumber(), 4); 669 670 // AT_low_pc, start address of the label. 671 const MCExpr *AT_low_pc = MCSymbolRefExpr::Create(Entry->getLabel(), 672 MCSymbolRefExpr::VK_None, context); 673 MCOS->EmitAbsValue(AT_low_pc, AddrSize); 674 675 // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype. 676 MCOS->EmitIntValue(0, 1); 677 678 // The DW_TAG_unspecified_parameters DIE abbrev (3). 679 MCOS->EmitULEB128IntValue(3); 680 681 // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's. 682 MCOS->EmitIntValue(0, 1); 683 } 684 // Deallocate the MCGenDwarfLabelEntry classes that saved away the info 685 // for the dwarf labels. 686 for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it = 687 Entries.begin(), ie = Entries.end(); it != ie; 688 ++it) { 689 const MCGenDwarfLabelEntry *Entry = *it; 690 delete Entry; 691 } 692 693 // Add the NULL DIE terminating the Compile Unit DIE's. 694 MCOS->EmitIntValue(0, 1); 695 696 // Now set the value of the symbol at the end of the info section. 697 MCOS->EmitLabel(InfoEnd); 698 } 699 700 // 701 // When generating dwarf for assembly source files this emits the Dwarf 702 // sections. 703 // 704 void MCGenDwarfInfo::Emit(MCStreamer *MCOS, const MCSymbol *LineSectionSymbol) { 705 // Create the dwarf sections in this order (.debug_line already created). 706 MCContext &context = MCOS->getContext(); 707 const MCAsmInfo &AsmInfo = context.getAsmInfo(); 708 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection()); 709 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection()); 710 MCSymbol *AbbrevSectionSymbol; 711 if (AsmInfo.doesDwarfUseRelocationsAcrossSections()) { 712 AbbrevSectionSymbol = context.CreateTempSymbol(); 713 MCOS->EmitLabel(AbbrevSectionSymbol); 714 } else { 715 AbbrevSectionSymbol = NULL; 716 LineSectionSymbol = NULL; 717 } 718 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection()); 719 720 // If there are no line table entries then do not emit any section contents. 721 if (context.getMCLineSections().empty()) 722 return; 723 724 // Output the data for .debug_aranges section. 725 EmitGenDwarfAranges(MCOS); 726 727 // Output the data for .debug_abbrev section. 728 EmitGenDwarfAbbrev(MCOS); 729 730 // Output the data for .debug_info section. 731 EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol); 732 } 733 734 // 735 // When generating dwarf for assembly source files this is called when symbol 736 // for a label is created. If this symbol is not a temporary and is in the 737 // section that dwarf is being generated for, save the needed info to create 738 // a dwarf label. 739 // 740 void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS, 741 SourceMgr &SrcMgr, SMLoc &Loc) { 742 // We won't create dwarf labels for temporary symbols or symbols not in 743 // the default text. 744 if (Symbol->isTemporary()) 745 return; 746 MCContext &context = MCOS->getContext(); 747 if (context.getGenDwarfSection() != MCOS->getCurrentSection()) 748 return; 749 750 // The dwarf label's name does not have the symbol name's leading 751 // underbar if any. 752 StringRef Name = Symbol->getName(); 753 if (Name.startswith("_")) 754 Name = Name.substr(1, Name.size()-1); 755 756 // Get the dwarf file number to be used for the dwarf label. 757 unsigned FileNumber = context.getGenDwarfFileNumber(); 758 759 // Finding the line number is the expensive part which is why we just don't 760 // pass it in as for some symbols we won't create a dwarf label. 761 int CurBuffer = SrcMgr.FindBufferContainingLoc(Loc); 762 unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer); 763 764 // We create a temporary symbol for use for the AT_high_pc and AT_low_pc 765 // values so that they don't have things like an ARM thumb bit from the 766 // original symbol. So when used they won't get a low bit set after 767 // relocation. 768 MCSymbol *Label = context.CreateTempSymbol(); 769 MCOS->EmitLabel(Label); 770 771 // Create and entry for the info and add it to the other entries. 772 MCGenDwarfLabelEntry *Entry = 773 new MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label); 774 MCOS->getContext().addMCGenDwarfLabelEntry(Entry); 775 } 776 777 static int getDataAlignmentFactor(MCStreamer &streamer) { 778 MCContext &context = streamer.getContext(); 779 const MCAsmInfo &asmInfo = context.getAsmInfo(); 780 int size = asmInfo.getPointerSize(); 781 if (asmInfo.isStackGrowthDirectionUp()) 782 return size; 783 else 784 return -size; 785 } 786 787 static unsigned getSizeForEncoding(MCStreamer &streamer, 788 unsigned symbolEncoding) { 789 MCContext &context = streamer.getContext(); 790 unsigned format = symbolEncoding & 0x0f; 791 switch (format) { 792 default: llvm_unreachable("Unknown Encoding"); 793 case dwarf::DW_EH_PE_absptr: 794 case dwarf::DW_EH_PE_signed: 795 return context.getAsmInfo().getPointerSize(); 796 case dwarf::DW_EH_PE_udata2: 797 case dwarf::DW_EH_PE_sdata2: 798 return 2; 799 case dwarf::DW_EH_PE_udata4: 800 case dwarf::DW_EH_PE_sdata4: 801 return 4; 802 case dwarf::DW_EH_PE_udata8: 803 case dwarf::DW_EH_PE_sdata8: 804 return 8; 805 } 806 } 807 808 static void EmitSymbol(MCStreamer &streamer, const MCSymbol &symbol, 809 unsigned symbolEncoding, const char *comment = 0) { 810 MCContext &context = streamer.getContext(); 811 const MCAsmInfo &asmInfo = context.getAsmInfo(); 812 const MCExpr *v = asmInfo.getExprForFDESymbol(&symbol, 813 symbolEncoding, 814 streamer); 815 unsigned size = getSizeForEncoding(streamer, symbolEncoding); 816 if (streamer.isVerboseAsm() && comment) streamer.AddComment(comment); 817 streamer.EmitAbsValue(v, size); 818 } 819 820 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol, 821 unsigned symbolEncoding) { 822 MCContext &context = streamer.getContext(); 823 const MCAsmInfo &asmInfo = context.getAsmInfo(); 824 const MCExpr *v = asmInfo.getExprForPersonalitySymbol(&symbol, 825 symbolEncoding, 826 streamer); 827 unsigned size = getSizeForEncoding(streamer, symbolEncoding); 828 streamer.EmitValue(v, size); 829 } 830 831 static const MachineLocation TranslateMachineLocation( 832 const MCRegisterInfo &MRI, 833 const MachineLocation &Loc) { 834 unsigned Reg = Loc.getReg() == MachineLocation::VirtualFP ? 835 MachineLocation::VirtualFP : 836 unsigned(MRI.getDwarfRegNum(Loc.getReg(), true)); 837 const MachineLocation &NewLoc = Loc.isReg() ? 838 MachineLocation(Reg) : MachineLocation(Reg, Loc.getOffset()); 839 return NewLoc; 840 } 841 842 namespace { 843 class FrameEmitterImpl { 844 int CFAOffset; 845 int CIENum; 846 bool UsingCFI; 847 bool IsEH; 848 const MCSymbol *SectionStart; 849 public: 850 FrameEmitterImpl(bool usingCFI, bool isEH) 851 : CFAOffset(0), CIENum(0), UsingCFI(usingCFI), IsEH(isEH), 852 SectionStart(0) {} 853 854 void setSectionStart(const MCSymbol *Label) { SectionStart = Label; } 855 856 /// EmitCompactUnwind - Emit the unwind information in a compact way. If 857 /// we're successful, return 'true'. Otherwise, return 'false' and it will 858 /// emit the normal CIE and FDE. 859 bool EmitCompactUnwind(MCStreamer &streamer, 860 const MCDwarfFrameInfo &frame); 861 862 const MCSymbol &EmitCIE(MCStreamer &streamer, 863 const MCSymbol *personality, 864 unsigned personalityEncoding, 865 const MCSymbol *lsda, 866 bool IsSignalFrame, 867 unsigned lsdaEncoding); 868 MCSymbol *EmitFDE(MCStreamer &streamer, 869 const MCSymbol &cieStart, 870 const MCDwarfFrameInfo &frame); 871 void EmitCFIInstructions(MCStreamer &streamer, 872 const std::vector<MCCFIInstruction> &Instrs, 873 MCSymbol *BaseLabel); 874 void EmitCFIInstruction(MCStreamer &Streamer, 875 const MCCFIInstruction &Instr); 876 }; 877 878 } // end anonymous namespace 879 880 static void EmitEncodingByte(MCStreamer &Streamer, unsigned Encoding, 881 StringRef Prefix) { 882 if (Streamer.isVerboseAsm()) { 883 const char *EncStr; 884 switch (Encoding) { 885 default: EncStr = "<unknown encoding>"; break; 886 case dwarf::DW_EH_PE_absptr: EncStr = "absptr"; break; 887 case dwarf::DW_EH_PE_omit: EncStr = "omit"; break; 888 case dwarf::DW_EH_PE_pcrel: EncStr = "pcrel"; break; 889 case dwarf::DW_EH_PE_udata4: EncStr = "udata4"; break; 890 case dwarf::DW_EH_PE_udata8: EncStr = "udata8"; break; 891 case dwarf::DW_EH_PE_sdata4: EncStr = "sdata4"; break; 892 case dwarf::DW_EH_PE_sdata8: EncStr = "sdata8"; break; 893 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4: 894 EncStr = "pcrel udata4"; 895 break; 896 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4: 897 EncStr = "pcrel sdata4"; 898 break; 899 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8: 900 EncStr = "pcrel udata8"; 901 break; 902 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8: 903 EncStr = "screl sdata8"; 904 break; 905 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata4: 906 EncStr = "indirect pcrel udata4"; 907 break; 908 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata4: 909 EncStr = "indirect pcrel sdata4"; 910 break; 911 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata8: 912 EncStr = "indirect pcrel udata8"; 913 break; 914 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata8: 915 EncStr = "indirect pcrel sdata8"; 916 break; 917 } 918 919 Streamer.AddComment(Twine(Prefix) + " = " + EncStr); 920 } 921 922 Streamer.EmitIntValue(Encoding, 1); 923 } 924 925 void FrameEmitterImpl::EmitCFIInstruction(MCStreamer &Streamer, 926 const MCCFIInstruction &Instr) { 927 int dataAlignmentFactor = getDataAlignmentFactor(Streamer); 928 bool VerboseAsm = Streamer.isVerboseAsm(); 929 930 switch (Instr.getOperation()) { 931 case MCCFIInstruction::Move: 932 case MCCFIInstruction::RelMove: { 933 const MachineLocation &Dst = Instr.getDestination(); 934 const MachineLocation &Src = Instr.getSource(); 935 const bool IsRelative = Instr.getOperation() == MCCFIInstruction::RelMove; 936 937 // If advancing cfa. 938 if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) { 939 if (Src.getReg() == MachineLocation::VirtualFP) { 940 if (VerboseAsm) Streamer.AddComment("DW_CFA_def_cfa_offset"); 941 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1); 942 } else { 943 if (VerboseAsm) Streamer.AddComment("DW_CFA_def_cfa"); 944 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1); 945 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + 946 Twine(Src.getReg())); 947 Streamer.EmitULEB128IntValue(Src.getReg()); 948 } 949 950 if (IsRelative) 951 CFAOffset += Src.getOffset(); 952 else 953 CFAOffset = -Src.getOffset(); 954 955 if (VerboseAsm) Streamer.AddComment(Twine("Offset " + Twine(CFAOffset))); 956 Streamer.EmitULEB128IntValue(CFAOffset); 957 return; 958 } 959 960 if (Src.isReg() && Src.getReg() == MachineLocation::VirtualFP) { 961 assert(Dst.isReg() && "Machine move not supported yet."); 962 if (VerboseAsm) Streamer.AddComment("DW_CFA_def_cfa_register"); 963 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1); 964 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Dst.getReg())); 965 Streamer.EmitULEB128IntValue(Dst.getReg()); 966 return; 967 } 968 969 unsigned Reg = Src.getReg(); 970 int Offset = Dst.getOffset(); 971 if (IsRelative) 972 Offset -= CFAOffset; 973 Offset = Offset / dataAlignmentFactor; 974 975 if (Offset < 0) { 976 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended_sf"); 977 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1); 978 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg)); 979 Streamer.EmitULEB128IntValue(Reg); 980 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset)); 981 Streamer.EmitSLEB128IntValue(Offset); 982 } else if (Reg < 64) { 983 if (VerboseAsm) Streamer.AddComment(Twine("DW_CFA_offset + Reg(") + 984 Twine(Reg) + ")"); 985 Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1); 986 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset)); 987 Streamer.EmitULEB128IntValue(Offset); 988 } else { 989 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended"); 990 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1); 991 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg)); 992 Streamer.EmitULEB128IntValue(Reg); 993 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset)); 994 Streamer.EmitULEB128IntValue(Offset); 995 } 996 return; 997 } 998 case MCCFIInstruction::RememberState: 999 if (VerboseAsm) Streamer.AddComment("DW_CFA_remember_state"); 1000 Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1); 1001 return; 1002 case MCCFIInstruction::RestoreState: 1003 if (VerboseAsm) Streamer.AddComment("DW_CFA_restore_state"); 1004 Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1); 1005 return; 1006 case MCCFIInstruction::SameValue: { 1007 unsigned Reg = Instr.getDestination().getReg(); 1008 if (VerboseAsm) Streamer.AddComment("DW_CFA_same_value"); 1009 Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1); 1010 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg)); 1011 Streamer.EmitULEB128IntValue(Reg); 1012 return; 1013 } 1014 case MCCFIInstruction::Restore: { 1015 unsigned Reg = Instr.getDestination().getReg(); 1016 if (VerboseAsm) { 1017 Streamer.AddComment("DW_CFA_restore"); 1018 Streamer.AddComment(Twine("Reg ") + Twine(Reg)); 1019 } 1020 Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1); 1021 return; 1022 } 1023 case MCCFIInstruction::Escape: 1024 if (VerboseAsm) Streamer.AddComment("Escape bytes"); 1025 Streamer.EmitBytes(Instr.getValues(), 0); 1026 return; 1027 } 1028 llvm_unreachable("Unhandled case in switch"); 1029 } 1030 1031 /// EmitFrameMoves - Emit frame instructions to describe the layout of the 1032 /// frame. 1033 void FrameEmitterImpl::EmitCFIInstructions(MCStreamer &streamer, 1034 const std::vector<MCCFIInstruction> &Instrs, 1035 MCSymbol *BaseLabel) { 1036 for (unsigned i = 0, N = Instrs.size(); i < N; ++i) { 1037 const MCCFIInstruction &Instr = Instrs[i]; 1038 MCSymbol *Label = Instr.getLabel(); 1039 // Throw out move if the label is invalid. 1040 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code. 1041 1042 // Advance row if new location. 1043 if (BaseLabel && Label) { 1044 MCSymbol *ThisSym = Label; 1045 if (ThisSym != BaseLabel) { 1046 if (streamer.isVerboseAsm()) streamer.AddComment("DW_CFA_advance_loc4"); 1047 streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym); 1048 BaseLabel = ThisSym; 1049 } 1050 } 1051 1052 EmitCFIInstruction(streamer, Instr); 1053 } 1054 } 1055 1056 /// EmitCompactUnwind - Emit the unwind information in a compact way. If we're 1057 /// successful, return 'true'. Otherwise, return 'false' and it will emit the 1058 /// normal CIE and FDE. 1059 bool FrameEmitterImpl::EmitCompactUnwind(MCStreamer &Streamer, 1060 const MCDwarfFrameInfo &Frame) { 1061 MCContext &Context = Streamer.getContext(); 1062 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo(); 1063 bool VerboseAsm = Streamer.isVerboseAsm(); 1064 1065 // range-start range-length compact-unwind-enc personality-func lsda 1066 // _foo LfooEnd-_foo 0x00000023 0 0 1067 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1 1068 // 1069 // .section __LD,__compact_unwind,regular,debug 1070 // 1071 // # compact unwind for _foo 1072 // .quad _foo 1073 // .set L1,LfooEnd-_foo 1074 // .long L1 1075 // .long 0x01010001 1076 // .quad 0 1077 // .quad 0 1078 // 1079 // # compact unwind for _bar 1080 // .quad _bar 1081 // .set L2,LbarEnd-_bar 1082 // .long L2 1083 // .long 0x01020011 1084 // .quad __gxx_personality 1085 // .quad except_tab1 1086 1087 uint32_t Encoding = Frame.CompactUnwindEncoding; 1088 if (!Encoding) return false; 1089 1090 // The encoding needs to know we have an LSDA. 1091 if (Frame.Lsda) 1092 Encoding |= 0x40000000; 1093 1094 Streamer.SwitchSection(MOFI->getCompactUnwindSection()); 1095 1096 // Range Start 1097 unsigned FDEEncoding = MOFI->getFDEEncoding(UsingCFI); 1098 unsigned Size = getSizeForEncoding(Streamer, FDEEncoding); 1099 if (VerboseAsm) Streamer.AddComment("Range Start"); 1100 Streamer.EmitSymbolValue(Frame.Function, Size); 1101 1102 // Range Length 1103 const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin, 1104 *Frame.End, 0); 1105 if (VerboseAsm) Streamer.AddComment("Range Length"); 1106 Streamer.EmitAbsValue(Range, 4); 1107 1108 // Compact Encoding 1109 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4); 1110 if (VerboseAsm) Streamer.AddComment("Compact Unwind Encoding: 0x" + 1111 Twine::utohexstr(Encoding)); 1112 Streamer.EmitIntValue(Encoding, Size); 1113 1114 1115 // Personality Function 1116 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr); 1117 if (VerboseAsm) Streamer.AddComment("Personality Function"); 1118 if (Frame.Personality) 1119 Streamer.EmitSymbolValue(Frame.Personality, Size); 1120 else 1121 Streamer.EmitIntValue(0, Size); // No personality fn 1122 1123 // LSDA 1124 Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding); 1125 if (VerboseAsm) Streamer.AddComment("LSDA"); 1126 if (Frame.Lsda) 1127 Streamer.EmitSymbolValue(Frame.Lsda, Size); 1128 else 1129 Streamer.EmitIntValue(0, Size); // No LSDA 1130 1131 return true; 1132 } 1133 1134 const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer, 1135 const MCSymbol *personality, 1136 unsigned personalityEncoding, 1137 const MCSymbol *lsda, 1138 bool IsSignalFrame, 1139 unsigned lsdaEncoding) { 1140 MCContext &context = streamer.getContext(); 1141 const MCRegisterInfo &MRI = context.getRegisterInfo(); 1142 const MCObjectFileInfo *MOFI = context.getObjectFileInfo(); 1143 bool verboseAsm = streamer.isVerboseAsm(); 1144 1145 MCSymbol *sectionStart; 1146 if (MOFI->isFunctionEHFrameSymbolPrivate() || !IsEH) 1147 sectionStart = context.CreateTempSymbol(); 1148 else 1149 sectionStart = context.GetOrCreateSymbol(Twine("EH_frame") + Twine(CIENum)); 1150 1151 streamer.EmitLabel(sectionStart); 1152 CIENum++; 1153 1154 MCSymbol *sectionEnd = context.CreateTempSymbol(); 1155 1156 // Length 1157 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *sectionStart, 1158 *sectionEnd, 4); 1159 if (verboseAsm) streamer.AddComment("CIE Length"); 1160 streamer.EmitAbsValue(Length, 4); 1161 1162 // CIE ID 1163 unsigned CIE_ID = IsEH ? 0 : -1; 1164 if (verboseAsm) streamer.AddComment("CIE ID Tag"); 1165 streamer.EmitIntValue(CIE_ID, 4); 1166 1167 // Version 1168 if (verboseAsm) streamer.AddComment("DW_CIE_VERSION"); 1169 streamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1); 1170 1171 // Augmentation String 1172 SmallString<8> Augmentation; 1173 if (IsEH) { 1174 if (verboseAsm) streamer.AddComment("CIE Augmentation"); 1175 Augmentation += "z"; 1176 if (personality) 1177 Augmentation += "P"; 1178 if (lsda) 1179 Augmentation += "L"; 1180 Augmentation += "R"; 1181 if (IsSignalFrame) 1182 Augmentation += "S"; 1183 streamer.EmitBytes(Augmentation.str(), 0); 1184 } 1185 streamer.EmitIntValue(0, 1); 1186 1187 // Code Alignment Factor 1188 if (verboseAsm) streamer.AddComment("CIE Code Alignment Factor"); 1189 streamer.EmitULEB128IntValue(1); 1190 1191 // Data Alignment Factor 1192 if (verboseAsm) streamer.AddComment("CIE Data Alignment Factor"); 1193 streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer)); 1194 1195 // Return Address Register 1196 if (verboseAsm) streamer.AddComment("CIE Return Address Column"); 1197 streamer.EmitULEB128IntValue(MRI.getDwarfRegNum(MRI.getRARegister(), true)); 1198 1199 // Augmentation Data Length (optional) 1200 1201 unsigned augmentationLength = 0; 1202 if (IsEH) { 1203 if (personality) { 1204 // Personality Encoding 1205 augmentationLength += 1; 1206 // Personality 1207 augmentationLength += getSizeForEncoding(streamer, personalityEncoding); 1208 } 1209 if (lsda) 1210 augmentationLength += 1; 1211 // Encoding of the FDE pointers 1212 augmentationLength += 1; 1213 1214 if (verboseAsm) streamer.AddComment("Augmentation Size"); 1215 streamer.EmitULEB128IntValue(augmentationLength); 1216 1217 // Augmentation Data (optional) 1218 if (personality) { 1219 // Personality Encoding 1220 EmitEncodingByte(streamer, personalityEncoding, 1221 "Personality Encoding"); 1222 // Personality 1223 if (verboseAsm) streamer.AddComment("Personality"); 1224 EmitPersonality(streamer, *personality, personalityEncoding); 1225 } 1226 1227 if (lsda) 1228 EmitEncodingByte(streamer, lsdaEncoding, "LSDA Encoding"); 1229 1230 // Encoding of the FDE pointers 1231 EmitEncodingByte(streamer, MOFI->getFDEEncoding(UsingCFI), 1232 "FDE Encoding"); 1233 } 1234 1235 // Initial Instructions 1236 1237 const MCAsmInfo &MAI = context.getAsmInfo(); 1238 const std::vector<MachineMove> &Moves = MAI.getInitialFrameState(); 1239 std::vector<MCCFIInstruction> Instructions; 1240 1241 for (int i = 0, n = Moves.size(); i != n; ++i) { 1242 MCSymbol *Label = Moves[i].getLabel(); 1243 const MachineLocation &Dst = 1244 TranslateMachineLocation(MRI, Moves[i].getDestination()); 1245 const MachineLocation &Src = 1246 TranslateMachineLocation(MRI, Moves[i].getSource()); 1247 MCCFIInstruction Inst(Label, Dst, Src); 1248 Instructions.push_back(Inst); 1249 } 1250 1251 EmitCFIInstructions(streamer, Instructions, NULL); 1252 1253 // Padding 1254 streamer.EmitValueToAlignment(IsEH 1255 ? 4 : context.getAsmInfo().getPointerSize()); 1256 1257 streamer.EmitLabel(sectionEnd); 1258 return *sectionStart; 1259 } 1260 1261 MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer, 1262 const MCSymbol &cieStart, 1263 const MCDwarfFrameInfo &frame) { 1264 MCContext &context = streamer.getContext(); 1265 MCSymbol *fdeStart = context.CreateTempSymbol(); 1266 MCSymbol *fdeEnd = context.CreateTempSymbol(); 1267 const MCObjectFileInfo *MOFI = context.getObjectFileInfo(); 1268 bool verboseAsm = streamer.isVerboseAsm(); 1269 1270 if (IsEH && frame.Function && !MOFI->isFunctionEHFrameSymbolPrivate()) { 1271 MCSymbol *EHSym = 1272 context.GetOrCreateSymbol(frame.Function->getName() + Twine(".eh")); 1273 streamer.EmitEHSymAttributes(frame.Function, EHSym); 1274 streamer.EmitLabel(EHSym); 1275 } 1276 1277 // Length 1278 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *fdeStart, *fdeEnd, 0); 1279 if (verboseAsm) streamer.AddComment("FDE Length"); 1280 streamer.EmitAbsValue(Length, 4); 1281 1282 streamer.EmitLabel(fdeStart); 1283 1284 // CIE Pointer 1285 const MCAsmInfo &asmInfo = context.getAsmInfo(); 1286 if (IsEH) { 1287 const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart, 1288 0); 1289 if (verboseAsm) streamer.AddComment("FDE CIE Offset"); 1290 streamer.EmitAbsValue(offset, 4); 1291 } else if (!asmInfo.doesDwarfUseRelocationsAcrossSections()) { 1292 const MCExpr *offset = MakeStartMinusEndExpr(streamer, *SectionStart, 1293 cieStart, 0); 1294 streamer.EmitAbsValue(offset, 4); 1295 } else { 1296 streamer.EmitSymbolValue(&cieStart, 4); 1297 } 1298 1299 // PC Begin 1300 unsigned PCEncoding = IsEH ? MOFI->getFDEEncoding(UsingCFI) 1301 : (unsigned)dwarf::DW_EH_PE_absptr; 1302 unsigned PCSize = getSizeForEncoding(streamer, PCEncoding); 1303 EmitSymbol(streamer, *frame.Begin, PCEncoding, "FDE initial location"); 1304 1305 // PC Range 1306 const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin, 1307 *frame.End, 0); 1308 if (verboseAsm) streamer.AddComment("FDE address range"); 1309 streamer.EmitAbsValue(Range, PCSize); 1310 1311 if (IsEH) { 1312 // Augmentation Data Length 1313 unsigned augmentationLength = 0; 1314 1315 if (frame.Lsda) 1316 augmentationLength += getSizeForEncoding(streamer, frame.LsdaEncoding); 1317 1318 if (verboseAsm) streamer.AddComment("Augmentation size"); 1319 streamer.EmitULEB128IntValue(augmentationLength); 1320 1321 // Augmentation Data 1322 if (frame.Lsda) 1323 EmitSymbol(streamer, *frame.Lsda, frame.LsdaEncoding, 1324 "Language Specific Data Area"); 1325 } 1326 1327 // Call Frame Instructions 1328 1329 EmitCFIInstructions(streamer, frame.Instructions, frame.Begin); 1330 1331 // Padding 1332 streamer.EmitValueToAlignment(PCSize); 1333 1334 return fdeEnd; 1335 } 1336 1337 namespace { 1338 struct CIEKey { 1339 static const CIEKey getEmptyKey() { return CIEKey(0, 0, -1, false); } 1340 static const CIEKey getTombstoneKey() { return CIEKey(0, -1, 0, false); } 1341 1342 CIEKey(const MCSymbol* Personality_, unsigned PersonalityEncoding_, 1343 unsigned LsdaEncoding_, bool IsSignalFrame_) : 1344 Personality(Personality_), PersonalityEncoding(PersonalityEncoding_), 1345 LsdaEncoding(LsdaEncoding_), IsSignalFrame(IsSignalFrame_) { 1346 } 1347 const MCSymbol* Personality; 1348 unsigned PersonalityEncoding; 1349 unsigned LsdaEncoding; 1350 bool IsSignalFrame; 1351 }; 1352 } 1353 1354 namespace llvm { 1355 template <> 1356 struct DenseMapInfo<CIEKey> { 1357 static CIEKey getEmptyKey() { 1358 return CIEKey::getEmptyKey(); 1359 } 1360 static CIEKey getTombstoneKey() { 1361 return CIEKey::getTombstoneKey(); 1362 } 1363 static unsigned getHashValue(const CIEKey &Key) { 1364 return static_cast<unsigned>(hash_combine(Key.Personality, 1365 Key.PersonalityEncoding, 1366 Key.LsdaEncoding, 1367 Key.IsSignalFrame)); 1368 } 1369 static bool isEqual(const CIEKey &LHS, 1370 const CIEKey &RHS) { 1371 return LHS.Personality == RHS.Personality && 1372 LHS.PersonalityEncoding == RHS.PersonalityEncoding && 1373 LHS.LsdaEncoding == RHS.LsdaEncoding && 1374 LHS.IsSignalFrame == RHS.IsSignalFrame; 1375 } 1376 }; 1377 } 1378 1379 void MCDwarfFrameEmitter::Emit(MCStreamer &Streamer, 1380 bool UsingCFI, 1381 bool IsEH) { 1382 MCContext &Context = Streamer.getContext(); 1383 MCObjectFileInfo *MOFI = 1384 const_cast<MCObjectFileInfo*>(Context.getObjectFileInfo()); 1385 FrameEmitterImpl Emitter(UsingCFI, IsEH); 1386 ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getFrameInfos(); 1387 1388 // Emit the compact unwind info if available. 1389 if (IsEH && MOFI->getCompactUnwindSection()) 1390 for (unsigned i = 0, n = Streamer.getNumFrameInfos(); i < n; ++i) { 1391 const MCDwarfFrameInfo &Frame = Streamer.getFrameInfo(i); 1392 if (Frame.CompactUnwindEncoding) 1393 Emitter.EmitCompactUnwind(Streamer, Frame); 1394 } 1395 1396 const MCSection &Section = IsEH ? *MOFI->getEHFrameSection() : 1397 *MOFI->getDwarfFrameSection(); 1398 Streamer.SwitchSection(&Section); 1399 MCSymbol *SectionStart = Context.CreateTempSymbol(); 1400 Streamer.EmitLabel(SectionStart); 1401 Emitter.setSectionStart(SectionStart); 1402 1403 MCSymbol *FDEEnd = NULL; 1404 DenseMap<CIEKey, const MCSymbol*> CIEStarts; 1405 1406 const MCSymbol *DummyDebugKey = NULL; 1407 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) { 1408 const MCDwarfFrameInfo &Frame = FrameArray[i]; 1409 CIEKey Key(Frame.Personality, Frame.PersonalityEncoding, 1410 Frame.LsdaEncoding, Frame.IsSignalFrame); 1411 const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey; 1412 if (!CIEStart) 1413 CIEStart = &Emitter.EmitCIE(Streamer, Frame.Personality, 1414 Frame.PersonalityEncoding, Frame.Lsda, 1415 Frame.IsSignalFrame, 1416 Frame.LsdaEncoding); 1417 1418 FDEEnd = Emitter.EmitFDE(Streamer, *CIEStart, Frame); 1419 1420 if (i != n - 1) 1421 Streamer.EmitLabel(FDEEnd); 1422 } 1423 1424 Streamer.EmitValueToAlignment(Context.getAsmInfo().getPointerSize()); 1425 if (FDEEnd) 1426 Streamer.EmitLabel(FDEEnd); 1427 } 1428 1429 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCStreamer &Streamer, 1430 uint64_t AddrDelta) { 1431 SmallString<256> Tmp; 1432 raw_svector_ostream OS(Tmp); 1433 MCDwarfFrameEmitter::EncodeAdvanceLoc(AddrDelta, OS); 1434 Streamer.EmitBytes(OS.str(), /*AddrSpace=*/0); 1435 } 1436 1437 void MCDwarfFrameEmitter::EncodeAdvanceLoc(uint64_t AddrDelta, 1438 raw_ostream &OS) { 1439 // FIXME: Assumes the code alignment factor is 1. 1440 if (AddrDelta == 0) { 1441 } else if (isUIntN(6, AddrDelta)) { 1442 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta; 1443 OS << Opcode; 1444 } else if (isUInt<8>(AddrDelta)) { 1445 OS << uint8_t(dwarf::DW_CFA_advance_loc1); 1446 OS << uint8_t(AddrDelta); 1447 } else if (isUInt<16>(AddrDelta)) { 1448 // FIXME: check what is the correct behavior on a big endian machine. 1449 OS << uint8_t(dwarf::DW_CFA_advance_loc2); 1450 OS << uint8_t( AddrDelta & 0xff); 1451 OS << uint8_t((AddrDelta >> 8) & 0xff); 1452 } else { 1453 // FIXME: check what is the correct behavior on a big endian machine. 1454 assert(isUInt<32>(AddrDelta)); 1455 OS << uint8_t(dwarf::DW_CFA_advance_loc4); 1456 OS << uint8_t( AddrDelta & 0xff); 1457 OS << uint8_t((AddrDelta >> 8) & 0xff); 1458 OS << uint8_t((AddrDelta >> 16) & 0xff); 1459 OS << uint8_t((AddrDelta >> 24) & 0xff); 1460 1461 } 1462 } 1463