1 //===- lib/MC/MCDwarf.cpp - MCDwarf implementation ------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "llvm/MC/MCDwarf.h"
11 #include "llvm/ADT/ArrayRef.h"
12 #include "llvm/ADT/DenseMap.h"
13 #include "llvm/ADT/Hashing.h"
14 #include "llvm/ADT/Optional.h"
15 #include "llvm/ADT/STLExtras.h"
16 #include "llvm/ADT/SmallString.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/ADT/StringRef.h"
19 #include "llvm/ADT/Twine.h"
20 #include "llvm/BinaryFormat/Dwarf.h"
21 #include "llvm/Config/config.h"
22 #include "llvm/MC/MCAsmInfo.h"
23 #include "llvm/MC/MCContext.h"
24 #include "llvm/MC/MCExpr.h"
25 #include "llvm/MC/MCObjectFileInfo.h"
26 #include "llvm/MC/MCObjectStreamer.h"
27 #include "llvm/MC/MCRegisterInfo.h"
28 #include "llvm/MC/MCSection.h"
29 #include "llvm/MC/MCStreamer.h"
30 #include "llvm/MC/MCSymbol.h"
31 #include "llvm/MC/StringTableBuilder.h"
32 #include "llvm/Support/Casting.h"
33 #include "llvm/Support/Endian.h"
34 #include "llvm/Support/EndianStream.h"
35 #include "llvm/Support/ErrorHandling.h"
36 #include "llvm/Support/LEB128.h"
37 #include "llvm/Support/MathExtras.h"
38 #include "llvm/Support/Path.h"
39 #include "llvm/Support/SourceMgr.h"
40 #include "llvm/Support/raw_ostream.h"
49 /// Manage the .debug_line_str section contents, if we use it.
50 class llvm::MCDwarfLineStr {
51 MCSymbol *LineStrLabel = nullptr;
52 StringTableBuilder LineStrings{StringTableBuilder::DWARF};
53 bool UseRelocs = false;
56 /// Construct an instance that can emit .debug_line_str (for use in a normal
58 explicit MCDwarfLineStr(MCContext &Ctx) {
59 UseRelocs = Ctx.getAsmInfo()->doesDwarfUseRelocationsAcrossSections();
62 Ctx.getObjectFileInfo()->getDwarfLineStrSection()->getBeginSymbol();
65 /// Emit a reference to the string.
66 void emitRef(MCStreamer *MCOS, StringRef Path);
68 /// Emit the .debug_line_str section if appropriate.
69 void emitSection(MCStreamer *MCOS);
72 static inline uint64_t ScaleAddrDelta(MCContext &Context, uint64_t AddrDelta) {
73 unsigned MinInsnLength = Context.getAsmInfo()->getMinInstAlignment();
74 if (MinInsnLength == 1)
76 if (AddrDelta % MinInsnLength != 0) {
77 // TODO: report this error, but really only once.
80 return AddrDelta / MinInsnLength;
84 // This is called when an instruction is assembled into the specified section
85 // and if there is information from the last .loc directive that has yet to have
86 // a line entry made for it is made.
88 void MCDwarfLineEntry::Make(MCObjectStreamer *MCOS, MCSection *Section) {
89 if (!MCOS->getContext().getDwarfLocSeen())
92 // Create a symbol at in the current section for use in the line entry.
93 MCSymbol *LineSym = MCOS->getContext().createTempSymbol();
94 // Set the value of the symbol to use for the MCDwarfLineEntry.
95 MCOS->EmitLabel(LineSym);
97 // Get the current .loc info saved in the context.
98 const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();
100 // Create a (local) line entry with the symbol and the current .loc info.
101 MCDwarfLineEntry LineEntry(LineSym, DwarfLoc);
103 // clear DwarfLocSeen saying the current .loc info is now used.
104 MCOS->getContext().clearDwarfLocSeen();
106 // Add the line entry to this section's entries.
108 .getMCDwarfLineTable(MCOS->getContext().getDwarfCompileUnitID())
110 .addLineEntry(LineEntry, Section);
114 // This helper routine returns an expression of End - Start + IntVal .
116 static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS,
117 const MCSymbol &Start,
120 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
122 MCSymbolRefExpr::create(&End, Variant, MCOS.getContext());
124 MCSymbolRefExpr::create(&Start, Variant, MCOS.getContext());
126 MCBinaryExpr::create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext());
128 MCConstantExpr::create(IntVal, MCOS.getContext());
130 MCBinaryExpr::create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext());
135 // This helper routine returns an expression of Start + IntVal .
137 static inline const MCExpr *
138 makeStartPlusIntExpr(MCContext &Ctx, const MCSymbol &Start, int IntVal) {
139 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
140 const MCExpr *LHS = MCSymbolRefExpr::create(&Start, Variant, Ctx);
141 const MCExpr *RHS = MCConstantExpr::create(IntVal, Ctx);
142 const MCExpr *Res = MCBinaryExpr::create(MCBinaryExpr::Add, LHS, RHS, Ctx);
147 // This emits the Dwarf line table for the specified section from the entries
148 // in the LineSection.
151 EmitDwarfLineTable(MCObjectStreamer *MCOS, MCSection *Section,
152 const MCLineSection::MCDwarfLineEntryCollection &LineEntries) {
153 unsigned FileNum = 1;
154 unsigned LastLine = 1;
156 unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
158 unsigned Discriminator = 0;
159 MCSymbol *LastLabel = nullptr;
161 // Loop through each MCDwarfLineEntry and encode the dwarf line number table.
162 for (const MCDwarfLineEntry &LineEntry : LineEntries) {
163 int64_t LineDelta = static_cast<int64_t>(LineEntry.getLine()) - LastLine;
165 if (FileNum != LineEntry.getFileNum()) {
166 FileNum = LineEntry.getFileNum();
167 MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
168 MCOS->EmitULEB128IntValue(FileNum);
170 if (Column != LineEntry.getColumn()) {
171 Column = LineEntry.getColumn();
172 MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
173 MCOS->EmitULEB128IntValue(Column);
175 if (Discriminator != LineEntry.getDiscriminator() &&
176 MCOS->getContext().getDwarfVersion() >= 4) {
177 Discriminator = LineEntry.getDiscriminator();
178 unsigned Size = getULEB128Size(Discriminator);
179 MCOS->EmitIntValue(dwarf::DW_LNS_extended_op, 1);
180 MCOS->EmitULEB128IntValue(Size + 1);
181 MCOS->EmitIntValue(dwarf::DW_LNE_set_discriminator, 1);
182 MCOS->EmitULEB128IntValue(Discriminator);
184 if (Isa != LineEntry.getIsa()) {
185 Isa = LineEntry.getIsa();
186 MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
187 MCOS->EmitULEB128IntValue(Isa);
189 if ((LineEntry.getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
190 Flags = LineEntry.getFlags();
191 MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
193 if (LineEntry.getFlags() & DWARF2_FLAG_BASIC_BLOCK)
194 MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
195 if (LineEntry.getFlags() & DWARF2_FLAG_PROLOGUE_END)
196 MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
197 if (LineEntry.getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
198 MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
200 MCSymbol *Label = LineEntry.getLabel();
202 // At this point we want to emit/create the sequence to encode the delta in
203 // line numbers and the increment of the address from the previous Label
204 // and the current Label.
205 const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo();
206 MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label,
207 asmInfo->getCodePointerSize());
210 LastLine = LineEntry.getLine();
214 // Emit a DW_LNE_end_sequence for the end of the section.
215 // Use the section end label to compute the address delta and use INT64_MAX
216 // as the line delta which is the signal that this is actually a
217 // DW_LNE_end_sequence.
218 MCSymbol *SectionEnd = MCOS->endSection(Section);
220 // Switch back the dwarf line section, in case endSection had to switch the
222 MCContext &Ctx = MCOS->getContext();
223 MCOS->SwitchSection(Ctx.getObjectFileInfo()->getDwarfLineSection());
225 const MCAsmInfo *AsmInfo = Ctx.getAsmInfo();
226 MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd,
227 AsmInfo->getCodePointerSize());
231 // This emits the Dwarf file and the line tables.
233 void MCDwarfLineTable::Emit(MCObjectStreamer *MCOS,
234 MCDwarfLineTableParams Params) {
235 MCContext &context = MCOS->getContext();
237 auto &LineTables = context.getMCDwarfLineTables();
239 // Bail out early so we don't switch to the debug_line section needlessly and
240 // in doing so create an unnecessary (if empty) section.
241 if (LineTables.empty())
244 // In a v5 non-split line table, put the strings in a separate section.
245 Optional<MCDwarfLineStr> LineStr;
246 if (context.getDwarfVersion() >= 5)
247 LineStr = MCDwarfLineStr(context);
249 // Switch to the section where the table will be emitted into.
250 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
252 // Handle the rest of the Compile Units.
253 for (const auto &CUIDTablePair : LineTables)
254 CUIDTablePair.second.EmitCU(MCOS, Params, LineStr);
257 LineStr->emitSection(MCOS);
260 void MCDwarfDwoLineTable::Emit(MCStreamer &MCOS, MCDwarfLineTableParams Params,
261 MCSection *Section) const {
262 if (Header.MCDwarfFiles.empty())
264 Optional<MCDwarfLineStr> NoLineStr(None);
265 MCOS.SwitchSection(Section);
266 MCOS.EmitLabel(Header.Emit(&MCOS, Params, None, NoLineStr).second);
269 std::pair<MCSymbol *, MCSymbol *>
270 MCDwarfLineTableHeader::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
271 Optional<MCDwarfLineStr> &LineStr) const {
272 static const char StandardOpcodeLengths[] = {
273 0, // length of DW_LNS_copy
274 1, // length of DW_LNS_advance_pc
275 1, // length of DW_LNS_advance_line
276 1, // length of DW_LNS_set_file
277 1, // length of DW_LNS_set_column
278 0, // length of DW_LNS_negate_stmt
279 0, // length of DW_LNS_set_basic_block
280 0, // length of DW_LNS_const_add_pc
281 1, // length of DW_LNS_fixed_advance_pc
282 0, // length of DW_LNS_set_prologue_end
283 0, // length of DW_LNS_set_epilogue_begin
286 assert(array_lengthof(StandardOpcodeLengths) >=
287 (Params.DWARF2LineOpcodeBase - 1U));
290 makeArrayRef(StandardOpcodeLengths, Params.DWARF2LineOpcodeBase - 1),
294 static const MCExpr *forceExpAbs(MCStreamer &OS, const MCExpr* Expr) {
295 MCContext &Context = OS.getContext();
296 assert(!isa<MCSymbolRefExpr>(Expr));
297 if (Context.getAsmInfo()->hasAggressiveSymbolFolding())
300 MCSymbol *ABS = Context.createTempSymbol();
301 OS.EmitAssignment(ABS, Expr);
302 return MCSymbolRefExpr::create(ABS, Context);
305 static void emitAbsValue(MCStreamer &OS, const MCExpr *Value, unsigned Size) {
306 const MCExpr *ABS = forceExpAbs(OS, Value);
307 OS.EmitValue(ABS, Size);
310 void MCDwarfLineStr::emitSection(MCStreamer *MCOS) {
311 // Switch to the .debug_line_str section.
313 MCOS->getContext().getObjectFileInfo()->getDwarfLineStrSection());
314 // Emit the strings without perturbing the offsets we used.
315 LineStrings.finalizeInOrder();
317 Data.resize(LineStrings.getSize());
318 LineStrings.write((uint8_t *)Data.data());
319 MCOS->EmitBinaryData(Data.str());
322 void MCDwarfLineStr::emitRef(MCStreamer *MCOS, StringRef Path) {
323 int RefSize = 4; // FIXME: Support DWARF-64
324 size_t Offset = LineStrings.add(Path);
326 MCContext &Ctx = MCOS->getContext();
327 MCOS->EmitValue(makeStartPlusIntExpr(Ctx, *LineStrLabel, Offset), RefSize);
329 MCOS->EmitIntValue(Offset, RefSize);
332 void MCDwarfLineTableHeader::emitV2FileDirTables(MCStreamer *MCOS) const {
333 // First the directory table.
334 for (auto &Dir : MCDwarfDirs) {
335 MCOS->EmitBytes(Dir); // The DirectoryName, and...
336 MCOS->EmitBytes(StringRef("\0", 1)); // its null terminator.
338 MCOS->EmitIntValue(0, 1); // Terminate the directory list.
340 // Second the file table.
341 for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
342 assert(!MCDwarfFiles[i].Name.empty());
343 MCOS->EmitBytes(MCDwarfFiles[i].Name); // FileName and...
344 MCOS->EmitBytes(StringRef("\0", 1)); // its null terminator.
345 MCOS->EmitULEB128IntValue(MCDwarfFiles[i].DirIndex); // Directory number.
346 MCOS->EmitIntValue(0, 1); // Last modification timestamp (always 0).
347 MCOS->EmitIntValue(0, 1); // File size (always 0).
349 MCOS->EmitIntValue(0, 1); // Terminate the file list.
352 void MCDwarfLineTableHeader::emitV5FileDirTables(
353 MCStreamer *MCOS, Optional<MCDwarfLineStr> &LineStr) const {
354 // The directory format, which is just a list of the directory paths. In a
355 // non-split object, these are references to .debug_line_str; in a split
356 // object, they are inline strings.
357 MCOS->EmitIntValue(1, 1);
358 MCOS->EmitULEB128IntValue(dwarf::DW_LNCT_path);
359 MCOS->EmitULEB128IntValue(LineStr ? dwarf::DW_FORM_line_strp
360 : dwarf::DW_FORM_string);
361 MCOS->EmitULEB128IntValue(MCDwarfDirs.size() + 1);
363 // Record path strings, emit references here.
364 LineStr->emitRef(MCOS, CompilationDir);
365 for (auto &Dir : MCDwarfDirs)
366 LineStr->emitRef(MCOS, Dir);
368 // The list of directory paths. CompilationDir comes first.
369 MCOS->EmitBytes(CompilationDir);
370 MCOS->EmitBytes(StringRef("\0", 1));
371 for (auto &Dir : MCDwarfDirs) {
372 MCOS->EmitBytes(Dir); // The DirectoryName, and...
373 MCOS->EmitBytes(StringRef("\0", 1)); // its null terminator.
377 // The file format, which is the inline null-terminated filename and a
378 // directory index. We don't track file size/timestamp so don't emit them
379 // in the v5 table. Emit MD5 checksums and source if we have them.
380 uint64_t Entries = 2;
385 MCOS->EmitIntValue(Entries, 1);
386 MCOS->EmitULEB128IntValue(dwarf::DW_LNCT_path);
387 MCOS->EmitULEB128IntValue(LineStr ? dwarf::DW_FORM_line_strp
388 : dwarf::DW_FORM_string);
389 MCOS->EmitULEB128IntValue(dwarf::DW_LNCT_directory_index);
390 MCOS->EmitULEB128IntValue(dwarf::DW_FORM_udata);
392 MCOS->EmitULEB128IntValue(dwarf::DW_LNCT_MD5);
393 MCOS->EmitULEB128IntValue(dwarf::DW_FORM_data16);
396 MCOS->EmitULEB128IntValue(dwarf::DW_LNCT_LLVM_source);
397 MCOS->EmitULEB128IntValue(LineStr ? dwarf::DW_FORM_line_strp
398 : dwarf::DW_FORM_string);
400 // Then the list of file names. These start at 1.
401 MCOS->EmitULEB128IntValue(MCDwarfFiles.size() - 1);
402 for (unsigned i = 1; i < MCDwarfFiles.size(); ++i) {
403 assert(!MCDwarfFiles[i].Name.empty());
405 LineStr->emitRef(MCOS, MCDwarfFiles[i].Name);
407 MCOS->EmitBytes(MCDwarfFiles[i].Name); // FileName and...
408 MCOS->EmitBytes(StringRef("\0", 1)); // its null terminator.
410 MCOS->EmitULEB128IntValue(MCDwarfFiles[i].DirIndex); // Directory number.
412 MD5::MD5Result *Cksum = MCDwarfFiles[i].Checksum;
413 MCOS->EmitBinaryData(
414 StringRef(reinterpret_cast<const char *>(Cksum->Bytes.data()),
415 Cksum->Bytes.size()));
419 LineStr->emitRef(MCOS, MCDwarfFiles[i].Source.getValueOr(StringRef()));
422 MCDwarfFiles[i].Source.getValueOr(StringRef())); // Source and...
423 MCOS->EmitBytes(StringRef("\0", 1)); // its null terminator.
429 std::pair<MCSymbol *, MCSymbol *>
430 MCDwarfLineTableHeader::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
431 ArrayRef<char> StandardOpcodeLengths,
432 Optional<MCDwarfLineStr> &LineStr) const {
433 MCContext &context = MCOS->getContext();
435 // Create a symbol at the beginning of the line table.
436 MCSymbol *LineStartSym = Label;
438 LineStartSym = context.createTempSymbol();
439 // Set the value of the symbol, as we are at the start of the line table.
440 MCOS->EmitLabel(LineStartSym);
442 // Create a symbol for the end of the section (to be set when we get there).
443 MCSymbol *LineEndSym = context.createTempSymbol();
445 // The first 4 bytes is the total length of the information for this
446 // compilation unit (not including these 4 bytes for the length).
448 MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym, 4), 4);
450 // Next 2 bytes is the Version.
451 // FIXME: On Darwin we still default to V2.
452 unsigned LineTableVersion = context.getDwarfVersion();
453 if (context.getObjectFileInfo()->getTargetTriple().isOSDarwin())
454 LineTableVersion = 2;
455 MCOS->EmitIntValue(LineTableVersion, 2);
457 // Keep track of the bytes between the very start and where the header length
459 unsigned PreHeaderLengthBytes = 4 + 2;
461 // In v5, we get address info next.
462 if (LineTableVersion >= 5) {
463 MCOS->EmitIntValue(context.getAsmInfo()->getCodePointerSize(), 1);
464 MCOS->EmitIntValue(0, 1); // Segment selector; same as EmitGenDwarfAranges.
465 PreHeaderLengthBytes += 2;
468 // Create a symbol for the end of the prologue (to be set when we get there).
469 MCSymbol *ProEndSym = context.createTempSymbol(); // Lprologue_end
471 // Length of the prologue, is the next 4 bytes. This is actually the length
472 // from after the length word, to the end of the prologue.
474 MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym,
475 (PreHeaderLengthBytes + 4)),
478 // Parameters of the state machine, are next.
479 MCOS->EmitIntValue(context.getAsmInfo()->getMinInstAlignment(), 1);
480 // maximum_operations_per_instruction
481 // For non-VLIW architectures this field is always 1.
482 // FIXME: VLIW architectures need to update this field accordingly.
483 if (LineTableVersion >= 4)
484 MCOS->EmitIntValue(1, 1);
485 MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
486 MCOS->EmitIntValue(Params.DWARF2LineBase, 1);
487 MCOS->EmitIntValue(Params.DWARF2LineRange, 1);
488 MCOS->EmitIntValue(StandardOpcodeLengths.size() + 1, 1);
490 // Standard opcode lengths
491 for (char Length : StandardOpcodeLengths)
492 MCOS->EmitIntValue(Length, 1);
494 // Put out the directory and file tables. The formats vary depending on
496 if (LineTableVersion >= 5)
497 emitV5FileDirTables(MCOS, LineStr);
499 emitV2FileDirTables(MCOS);
501 // This is the end of the prologue, so set the value of the symbol at the
502 // end of the prologue (that was used in a previous expression).
503 MCOS->EmitLabel(ProEndSym);
505 return std::make_pair(LineStartSym, LineEndSym);
508 void MCDwarfLineTable::EmitCU(MCObjectStreamer *MCOS,
509 MCDwarfLineTableParams Params,
510 Optional<MCDwarfLineStr> &LineStr) const {
511 MCSymbol *LineEndSym = Header.Emit(MCOS, Params, LineStr).second;
513 // Put out the line tables.
514 for (const auto &LineSec : MCLineSections.getMCLineEntries())
515 EmitDwarfLineTable(MCOS, LineSec.first, LineSec.second);
517 // This is the end of the section, so set the value of the symbol at the end
518 // of this section (that was used in a previous expression).
519 MCOS->EmitLabel(LineEndSym);
522 Expected<unsigned> MCDwarfLineTable::tryGetFile(StringRef &Directory,
524 MD5::MD5Result *Checksum,
525 Optional<StringRef> Source,
526 unsigned FileNumber) {
527 return Header.tryGetFile(Directory, FileName, Checksum, Source, FileNumber);
531 MCDwarfLineTableHeader::tryGetFile(StringRef &Directory,
533 MD5::MD5Result *Checksum,
534 Optional<StringRef> &Source,
535 unsigned FileNumber) {
536 if (Directory == CompilationDir)
538 if (FileName.empty()) {
539 FileName = "<stdin>";
542 assert(!FileName.empty());
543 // If any files have an MD5 checksum or embedded source, they all must.
544 if (MCDwarfFiles.empty()) {
545 HasMD5 = (Checksum != nullptr);
546 HasSource = (Source != None);
548 if (FileNumber == 0) {
549 // File numbers start with 1 and/or after any file numbers
550 // allocated by inline-assembler .file directives.
551 FileNumber = MCDwarfFiles.empty() ? 1 : MCDwarfFiles.size();
552 SmallString<256> Buffer;
553 auto IterBool = SourceIdMap.insert(
554 std::make_pair((Directory + Twine('\0') + FileName).toStringRef(Buffer),
556 if (!IterBool.second)
557 return IterBool.first->second;
559 // Make space for this FileNumber in the MCDwarfFiles vector if needed.
560 if (FileNumber >= MCDwarfFiles.size())
561 MCDwarfFiles.resize(FileNumber + 1);
563 // Get the new MCDwarfFile slot for this FileNumber.
564 MCDwarfFile &File = MCDwarfFiles[FileNumber];
566 // It is an error to see the same number more than once.
567 if (!File.Name.empty())
568 return make_error<StringError>("file number already allocated",
569 inconvertibleErrorCode());
571 // If any files have an MD5 checksum, they all must.
572 if (HasMD5 != (Checksum != nullptr))
573 return make_error<StringError>("inconsistent use of MD5 checksums",
574 inconvertibleErrorCode());
575 // If any files have embedded source, they all must.
576 if (HasSource != (Source != None))
577 return make_error<StringError>("inconsistent use of embedded source",
578 inconvertibleErrorCode());
580 if (Directory.empty()) {
581 // Separate the directory part from the basename of the FileName.
582 StringRef tFileName = sys::path::filename(FileName);
583 if (!tFileName.empty()) {
584 Directory = sys::path::parent_path(FileName);
585 if (!Directory.empty())
586 FileName = tFileName;
590 // Find or make an entry in the MCDwarfDirs vector for this Directory.
591 // Capture directory name.
593 if (Directory.empty()) {
594 // For FileNames with no directories a DirIndex of 0 is used.
598 for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
599 if (Directory == MCDwarfDirs[DirIndex])
602 if (DirIndex >= MCDwarfDirs.size())
603 MCDwarfDirs.push_back(Directory);
604 // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
605 // no directories. MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
606 // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
607 // are stored at MCDwarfFiles[FileNumber].Name .
611 File.Name = FileName;
612 File.DirIndex = DirIndex;
613 File.Checksum = Checksum;
616 File.Source = Source;
620 // return the allocated FileNumber.
624 /// Utility function to emit the encoding to a streamer.
625 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
626 int64_t LineDelta, uint64_t AddrDelta) {
627 MCContext &Context = MCOS->getContext();
628 SmallString<256> Tmp;
629 raw_svector_ostream OS(Tmp);
630 MCDwarfLineAddr::Encode(Context, Params, LineDelta, AddrDelta, OS);
631 MCOS->EmitBytes(OS.str());
634 /// Given a special op, return the address skip amount (in units of
635 /// DWARF2_LINE_MIN_INSN_LENGTH).
636 static uint64_t SpecialAddr(MCDwarfLineTableParams Params, uint64_t op) {
637 return (op - Params.DWARF2LineOpcodeBase) / Params.DWARF2LineRange;
640 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
641 void MCDwarfLineAddr::Encode(MCContext &Context, MCDwarfLineTableParams Params,
642 int64_t LineDelta, uint64_t AddrDelta,
644 uint64_t Temp, Opcode;
645 bool NeedCopy = false;
647 // The maximum address skip amount that can be encoded with a special op.
648 uint64_t MaxSpecialAddrDelta = SpecialAddr(Params, 255);
650 // Scale the address delta by the minimum instruction length.
651 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
653 // A LineDelta of INT64_MAX is a signal that this is actually a
654 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
655 // end_sequence to emit the matrix entry.
656 if (LineDelta == INT64_MAX) {
657 if (AddrDelta == MaxSpecialAddrDelta)
658 OS << char(dwarf::DW_LNS_const_add_pc);
659 else if (AddrDelta) {
660 OS << char(dwarf::DW_LNS_advance_pc);
661 encodeULEB128(AddrDelta, OS);
663 OS << char(dwarf::DW_LNS_extended_op);
665 OS << char(dwarf::DW_LNE_end_sequence);
669 // Bias the line delta by the base.
670 Temp = LineDelta - Params.DWARF2LineBase;
672 // If the line increment is out of range of a special opcode, we must encode
673 // it with DW_LNS_advance_line.
674 if (Temp >= Params.DWARF2LineRange ||
675 Temp + Params.DWARF2LineOpcodeBase > 255) {
676 OS << char(dwarf::DW_LNS_advance_line);
677 encodeSLEB128(LineDelta, OS);
680 Temp = 0 - Params.DWARF2LineBase;
684 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
685 if (LineDelta == 0 && AddrDelta == 0) {
686 OS << char(dwarf::DW_LNS_copy);
690 // Bias the opcode by the special opcode base.
691 Temp += Params.DWARF2LineOpcodeBase;
693 // Avoid overflow when addr_delta is large.
694 if (AddrDelta < 256 + MaxSpecialAddrDelta) {
695 // Try using a special opcode.
696 Opcode = Temp + AddrDelta * Params.DWARF2LineRange;
702 // Try using DW_LNS_const_add_pc followed by special op.
703 Opcode = Temp + (AddrDelta - MaxSpecialAddrDelta) * Params.DWARF2LineRange;
705 OS << char(dwarf::DW_LNS_const_add_pc);
711 // Otherwise use DW_LNS_advance_pc.
712 OS << char(dwarf::DW_LNS_advance_pc);
713 encodeULEB128(AddrDelta, OS);
716 OS << char(dwarf::DW_LNS_copy);
718 assert(Temp <= 255 && "Buggy special opcode encoding.");
723 // Utility function to write a tuple for .debug_abbrev.
724 static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) {
725 MCOS->EmitULEB128IntValue(Name);
726 MCOS->EmitULEB128IntValue(Form);
729 // When generating dwarf for assembly source files this emits
730 // the data for .debug_abbrev section which contains three DIEs.
731 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
732 MCContext &context = MCOS->getContext();
733 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
735 // DW_TAG_compile_unit DIE abbrev (1).
736 MCOS->EmitULEB128IntValue(1);
737 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit);
738 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
739 EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, context.getDwarfVersion() >= 4
740 ? dwarf::DW_FORM_sec_offset
741 : dwarf::DW_FORM_data4);
742 if (context.getGenDwarfSectionSyms().size() > 1 &&
743 context.getDwarfVersion() >= 3) {
744 EmitAbbrev(MCOS, dwarf::DW_AT_ranges, context.getDwarfVersion() >= 4
745 ? dwarf::DW_FORM_sec_offset
746 : dwarf::DW_FORM_data4);
748 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
749 EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
751 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
752 if (!context.getCompilationDir().empty())
753 EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
754 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
755 if (!DwarfDebugFlags.empty())
756 EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
757 EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string);
758 EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2);
759 EmitAbbrev(MCOS, 0, 0);
761 // DW_TAG_label DIE abbrev (2).
762 MCOS->EmitULEB128IntValue(2);
763 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_label);
764 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
765 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
766 EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);
767 EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);
768 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
769 EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag);
770 EmitAbbrev(MCOS, 0, 0);
772 // DW_TAG_unspecified_parameters DIE abbrev (3).
773 MCOS->EmitULEB128IntValue(3);
774 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters);
775 MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1);
776 EmitAbbrev(MCOS, 0, 0);
778 // Terminate the abbreviations for this compilation unit.
779 MCOS->EmitIntValue(0, 1);
782 // When generating dwarf for assembly source files this emits the data for
783 // .debug_aranges section. This section contains a header and a table of pairs
784 // of PointerSize'ed values for the address and size of section(s) with line
786 static void EmitGenDwarfAranges(MCStreamer *MCOS,
787 const MCSymbol *InfoSectionSymbol) {
788 MCContext &context = MCOS->getContext();
790 auto &Sections = context.getGenDwarfSectionSyms();
792 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
794 // This will be the length of the .debug_aranges section, first account for
795 // the size of each item in the header (see below where we emit these items).
796 int Length = 4 + 2 + 4 + 1 + 1;
798 // Figure the padding after the header before the table of address and size
799 // pairs who's values are PointerSize'ed.
800 const MCAsmInfo *asmInfo = context.getAsmInfo();
801 int AddrSize = asmInfo->getCodePointerSize();
802 int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1));
803 if (Pad == 2 * AddrSize)
807 // Add the size of the pair of PointerSize'ed values for the address and size
808 // of each section we have in the table.
809 Length += 2 * AddrSize * Sections.size();
810 // And the pair of terminating zeros.
811 Length += 2 * AddrSize;
813 // Emit the header for this section.
814 // The 4 byte length not including the 4 byte value for the length.
815 MCOS->EmitIntValue(Length - 4, 4);
816 // The 2 byte version, which is 2.
817 MCOS->EmitIntValue(2, 2);
818 // The 4 byte offset to the compile unit in the .debug_info from the start
819 // of the .debug_info.
820 if (InfoSectionSymbol)
821 MCOS->EmitSymbolValue(InfoSectionSymbol, 4,
822 asmInfo->needsDwarfSectionOffsetDirective());
824 MCOS->EmitIntValue(0, 4);
825 // The 1 byte size of an address.
826 MCOS->EmitIntValue(AddrSize, 1);
827 // The 1 byte size of a segment descriptor, we use a value of zero.
828 MCOS->EmitIntValue(0, 1);
829 // Align the header with the padding if needed, before we put out the table.
830 for(int i = 0; i < Pad; i++)
831 MCOS->EmitIntValue(0, 1);
833 // Now emit the table of pairs of PointerSize'ed values for the section
834 // addresses and sizes.
835 for (MCSection *Sec : Sections) {
836 const MCSymbol *StartSymbol = Sec->getBeginSymbol();
837 MCSymbol *EndSymbol = Sec->getEndSymbol(context);
838 assert(StartSymbol && "StartSymbol must not be NULL");
839 assert(EndSymbol && "EndSymbol must not be NULL");
841 const MCExpr *Addr = MCSymbolRefExpr::create(
842 StartSymbol, MCSymbolRefExpr::VK_None, context);
843 const MCExpr *Size = MakeStartMinusEndExpr(*MCOS,
844 *StartSymbol, *EndSymbol, 0);
845 MCOS->EmitValue(Addr, AddrSize);
846 emitAbsValue(*MCOS, Size, AddrSize);
849 // And finally the pair of terminating zeros.
850 MCOS->EmitIntValue(0, AddrSize);
851 MCOS->EmitIntValue(0, AddrSize);
854 // When generating dwarf for assembly source files this emits the data for
855 // .debug_info section which contains three parts. The header, the compile_unit
856 // DIE and a list of label DIEs.
857 static void EmitGenDwarfInfo(MCStreamer *MCOS,
858 const MCSymbol *AbbrevSectionSymbol,
859 const MCSymbol *LineSectionSymbol,
860 const MCSymbol *RangesSectionSymbol) {
861 MCContext &context = MCOS->getContext();
863 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
865 // Create a symbol at the start and end of this section used in here for the
866 // expression to calculate the length in the header.
867 MCSymbol *InfoStart = context.createTempSymbol();
868 MCOS->EmitLabel(InfoStart);
869 MCSymbol *InfoEnd = context.createTempSymbol();
871 // First part: the header.
873 // The 4 byte total length of the information for this compilation unit, not
874 // including these 4 bytes.
875 const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4);
876 emitAbsValue(*MCOS, Length, 4);
878 // The 2 byte DWARF version.
879 MCOS->EmitIntValue(context.getDwarfVersion(), 2);
881 // The DWARF v5 header has unit type, address size, abbrev offset.
882 // Earlier versions have abbrev offset, address size.
883 const MCAsmInfo &AsmInfo = *context.getAsmInfo();
884 int AddrSize = AsmInfo.getCodePointerSize();
885 if (context.getDwarfVersion() >= 5) {
886 MCOS->EmitIntValue(dwarf::DW_UT_compile, 1);
887 MCOS->EmitIntValue(AddrSize, 1);
889 // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev,
890 // it is at the start of that section so this is zero.
891 if (AbbrevSectionSymbol == nullptr)
892 MCOS->EmitIntValue(0, 4);
894 MCOS->EmitSymbolValue(AbbrevSectionSymbol, 4,
895 AsmInfo.needsDwarfSectionOffsetDirective());
896 if (context.getDwarfVersion() <= 4)
897 MCOS->EmitIntValue(AddrSize, 1);
899 // Second part: the compile_unit DIE.
901 // The DW_TAG_compile_unit DIE abbrev (1).
902 MCOS->EmitULEB128IntValue(1);
904 // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section,
905 // which is at the start of that section so this is zero.
906 if (LineSectionSymbol)
907 MCOS->EmitSymbolValue(LineSectionSymbol, 4,
908 AsmInfo.needsDwarfSectionOffsetDirective());
910 MCOS->EmitIntValue(0, 4);
912 if (RangesSectionSymbol) {
913 // There are multiple sections containing code, so we must use the
914 // .debug_ranges sections.
916 // AT_ranges, the 4 byte offset from the start of the .debug_ranges section
917 // to the address range list for this compilation unit.
918 MCOS->EmitSymbolValue(RangesSectionSymbol, 4);
920 // If we only have one non-empty code section, we can use the simpler
921 // AT_low_pc and AT_high_pc attributes.
923 // Find the first (and only) non-empty text section
924 auto &Sections = context.getGenDwarfSectionSyms();
925 const auto TextSection = Sections.begin();
926 assert(TextSection != Sections.end() && "No text section found");
928 MCSymbol *StartSymbol = (*TextSection)->getBeginSymbol();
929 MCSymbol *EndSymbol = (*TextSection)->getEndSymbol(context);
930 assert(StartSymbol && "StartSymbol must not be NULL");
931 assert(EndSymbol && "EndSymbol must not be NULL");
933 // AT_low_pc, the first address of the default .text section.
934 const MCExpr *Start = MCSymbolRefExpr::create(
935 StartSymbol, MCSymbolRefExpr::VK_None, context);
936 MCOS->EmitValue(Start, AddrSize);
938 // AT_high_pc, the last address of the default .text section.
939 const MCExpr *End = MCSymbolRefExpr::create(
940 EndSymbol, MCSymbolRefExpr::VK_None, context);
941 MCOS->EmitValue(End, AddrSize);
944 // AT_name, the name of the source file. Reconstruct from the first directory
945 // and file table entries.
946 const SmallVectorImpl<std::string> &MCDwarfDirs = context.getMCDwarfDirs();
947 if (MCDwarfDirs.size() > 0) {
948 MCOS->EmitBytes(MCDwarfDirs[0]);
949 MCOS->EmitBytes(sys::path::get_separator());
951 const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles =
952 MCOS->getContext().getMCDwarfFiles();
953 MCOS->EmitBytes(MCDwarfFiles[1].Name);
954 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
956 // AT_comp_dir, the working directory the assembly was done in.
957 if (!context.getCompilationDir().empty()) {
958 MCOS->EmitBytes(context.getCompilationDir());
959 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
962 // AT_APPLE_flags, the command line arguments of the assembler tool.
963 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
964 if (!DwarfDebugFlags.empty()){
965 MCOS->EmitBytes(DwarfDebugFlags);
966 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
969 // AT_producer, the version of the assembler tool.
970 StringRef DwarfDebugProducer = context.getDwarfDebugProducer();
971 if (!DwarfDebugProducer.empty())
972 MCOS->EmitBytes(DwarfDebugProducer);
974 MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM " PACKAGE_VERSION ")"));
975 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
977 // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2
978 // draft has no standard code for assembler.
979 MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2);
981 // Third part: the list of label DIEs.
983 // Loop on saved info for dwarf labels and create the DIEs for them.
984 const std::vector<MCGenDwarfLabelEntry> &Entries =
985 MCOS->getContext().getMCGenDwarfLabelEntries();
986 for (const auto &Entry : Entries) {
987 // The DW_TAG_label DIE abbrev (2).
988 MCOS->EmitULEB128IntValue(2);
990 // AT_name, of the label without any leading underbar.
991 MCOS->EmitBytes(Entry.getName());
992 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
994 // AT_decl_file, index into the file table.
995 MCOS->EmitIntValue(Entry.getFileNumber(), 4);
997 // AT_decl_line, source line number.
998 MCOS->EmitIntValue(Entry.getLineNumber(), 4);
1000 // AT_low_pc, start address of the label.
1001 const MCExpr *AT_low_pc = MCSymbolRefExpr::create(Entry.getLabel(),
1002 MCSymbolRefExpr::VK_None, context);
1003 MCOS->EmitValue(AT_low_pc, AddrSize);
1005 // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype.
1006 MCOS->EmitIntValue(0, 1);
1008 // The DW_TAG_unspecified_parameters DIE abbrev (3).
1009 MCOS->EmitULEB128IntValue(3);
1011 // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's.
1012 MCOS->EmitIntValue(0, 1);
1015 // Add the NULL DIE terminating the Compile Unit DIE's.
1016 MCOS->EmitIntValue(0, 1);
1018 // Now set the value of the symbol at the end of the info section.
1019 MCOS->EmitLabel(InfoEnd);
1022 // When generating dwarf for assembly source files this emits the data for
1023 // .debug_ranges section. We only emit one range list, which spans all of the
1024 // executable sections of this file.
1025 static void EmitGenDwarfRanges(MCStreamer *MCOS) {
1026 MCContext &context = MCOS->getContext();
1027 auto &Sections = context.getGenDwarfSectionSyms();
1029 const MCAsmInfo *AsmInfo = context.getAsmInfo();
1030 int AddrSize = AsmInfo->getCodePointerSize();
1032 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection());
1034 for (MCSection *Sec : Sections) {
1035 const MCSymbol *StartSymbol = Sec->getBeginSymbol();
1036 MCSymbol *EndSymbol = Sec->getEndSymbol(context);
1037 assert(StartSymbol && "StartSymbol must not be NULL");
1038 assert(EndSymbol && "EndSymbol must not be NULL");
1040 // Emit a base address selection entry for the start of this section
1041 const MCExpr *SectionStartAddr = MCSymbolRefExpr::create(
1042 StartSymbol, MCSymbolRefExpr::VK_None, context);
1043 MCOS->emitFill(AddrSize, 0xFF);
1044 MCOS->EmitValue(SectionStartAddr, AddrSize);
1046 // Emit a range list entry spanning this section
1047 const MCExpr *SectionSize = MakeStartMinusEndExpr(*MCOS,
1048 *StartSymbol, *EndSymbol, 0);
1049 MCOS->EmitIntValue(0, AddrSize);
1050 emitAbsValue(*MCOS, SectionSize, AddrSize);
1053 // Emit end of list entry
1054 MCOS->EmitIntValue(0, AddrSize);
1055 MCOS->EmitIntValue(0, AddrSize);
1059 // When generating dwarf for assembly source files this emits the Dwarf
1062 void MCGenDwarfInfo::Emit(MCStreamer *MCOS) {
1063 MCContext &context = MCOS->getContext();
1065 // Create the dwarf sections in this order (.debug_line already created).
1066 const MCAsmInfo *AsmInfo = context.getAsmInfo();
1067 bool CreateDwarfSectionSymbols =
1068 AsmInfo->doesDwarfUseRelocationsAcrossSections();
1069 MCSymbol *LineSectionSymbol = nullptr;
1070 if (CreateDwarfSectionSymbols)
1071 LineSectionSymbol = MCOS->getDwarfLineTableSymbol(0);
1072 MCSymbol *AbbrevSectionSymbol = nullptr;
1073 MCSymbol *InfoSectionSymbol = nullptr;
1074 MCSymbol *RangesSectionSymbol = nullptr;
1076 // Create end symbols for each section, and remove empty sections
1077 MCOS->getContext().finalizeDwarfSections(*MCOS);
1079 // If there are no sections to generate debug info for, we don't need
1081 if (MCOS->getContext().getGenDwarfSectionSyms().empty())
1084 // We only use the .debug_ranges section if we have multiple code sections,
1085 // and we are emitting a DWARF version which supports it.
1086 const bool UseRangesSection =
1087 MCOS->getContext().getGenDwarfSectionSyms().size() > 1 &&
1088 MCOS->getContext().getDwarfVersion() >= 3;
1089 CreateDwarfSectionSymbols |= UseRangesSection;
1091 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
1092 if (CreateDwarfSectionSymbols) {
1093 InfoSectionSymbol = context.createTempSymbol();
1094 MCOS->EmitLabel(InfoSectionSymbol);
1096 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
1097 if (CreateDwarfSectionSymbols) {
1098 AbbrevSectionSymbol = context.createTempSymbol();
1099 MCOS->EmitLabel(AbbrevSectionSymbol);
1101 if (UseRangesSection) {
1102 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection());
1103 if (CreateDwarfSectionSymbols) {
1104 RangesSectionSymbol = context.createTempSymbol();
1105 MCOS->EmitLabel(RangesSectionSymbol);
1109 assert((RangesSectionSymbol != nullptr) || !UseRangesSection);
1111 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
1113 // Output the data for .debug_aranges section.
1114 EmitGenDwarfAranges(MCOS, InfoSectionSymbol);
1116 if (UseRangesSection)
1117 EmitGenDwarfRanges(MCOS);
1119 // Output the data for .debug_abbrev section.
1120 EmitGenDwarfAbbrev(MCOS);
1122 // Output the data for .debug_info section.
1123 EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol,
1124 RangesSectionSymbol);
1128 // When generating dwarf for assembly source files this is called when symbol
1129 // for a label is created. If this symbol is not a temporary and is in the
1130 // section that dwarf is being generated for, save the needed info to create
1133 void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
1134 SourceMgr &SrcMgr, SMLoc &Loc) {
1135 // We won't create dwarf labels for temporary symbols.
1136 if (Symbol->isTemporary())
1138 MCContext &context = MCOS->getContext();
1139 // We won't create dwarf labels for symbols in sections that we are not
1140 // generating debug info for.
1141 if (!context.getGenDwarfSectionSyms().count(MCOS->getCurrentSectionOnly()))
1144 // The dwarf label's name does not have the symbol name's leading
1146 StringRef Name = Symbol->getName();
1147 if (Name.startswith("_"))
1148 Name = Name.substr(1, Name.size()-1);
1150 // Get the dwarf file number to be used for the dwarf label.
1151 unsigned FileNumber = context.getGenDwarfFileNumber();
1153 // Finding the line number is the expensive part which is why we just don't
1154 // pass it in as for some symbols we won't create a dwarf label.
1155 unsigned CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
1156 unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
1158 // We create a temporary symbol for use for the AT_high_pc and AT_low_pc
1159 // values so that they don't have things like an ARM thumb bit from the
1160 // original symbol. So when used they won't get a low bit set after
1162 MCSymbol *Label = context.createTempSymbol();
1163 MCOS->EmitLabel(Label);
1165 // Create and entry for the info and add it to the other entries.
1166 MCOS->getContext().addMCGenDwarfLabelEntry(
1167 MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label));
1170 static int getDataAlignmentFactor(MCStreamer &streamer) {
1171 MCContext &context = streamer.getContext();
1172 const MCAsmInfo *asmInfo = context.getAsmInfo();
1173 int size = asmInfo->getCalleeSaveStackSlotSize();
1174 if (asmInfo->isStackGrowthDirectionUp())
1180 static unsigned getSizeForEncoding(MCStreamer &streamer,
1181 unsigned symbolEncoding) {
1182 MCContext &context = streamer.getContext();
1183 unsigned format = symbolEncoding & 0x0f;
1185 default: llvm_unreachable("Unknown Encoding");
1186 case dwarf::DW_EH_PE_absptr:
1187 case dwarf::DW_EH_PE_signed:
1188 return context.getAsmInfo()->getCodePointerSize();
1189 case dwarf::DW_EH_PE_udata2:
1190 case dwarf::DW_EH_PE_sdata2:
1192 case dwarf::DW_EH_PE_udata4:
1193 case dwarf::DW_EH_PE_sdata4:
1195 case dwarf::DW_EH_PE_udata8:
1196 case dwarf::DW_EH_PE_sdata8:
1201 static void emitFDESymbol(MCObjectStreamer &streamer, const MCSymbol &symbol,
1202 unsigned symbolEncoding, bool isEH) {
1203 MCContext &context = streamer.getContext();
1204 const MCAsmInfo *asmInfo = context.getAsmInfo();
1205 const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol,
1208 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
1209 if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH)
1210 emitAbsValue(streamer, v, size);
1212 streamer.EmitValue(v, size);
1215 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
1216 unsigned symbolEncoding) {
1217 MCContext &context = streamer.getContext();
1218 const MCAsmInfo *asmInfo = context.getAsmInfo();
1219 const MCExpr *v = asmInfo->getExprForPersonalitySymbol(&symbol,
1222 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
1223 streamer.EmitValue(v, size);
1228 class FrameEmitterImpl {
1230 int InitialCFAOffset = 0;
1232 MCObjectStreamer &Streamer;
1235 FrameEmitterImpl(bool IsEH, MCObjectStreamer &Streamer)
1236 : IsEH(IsEH), Streamer(Streamer) {}
1238 /// Emit the unwind information in a compact way.
1239 void EmitCompactUnwind(const MCDwarfFrameInfo &frame);
1241 const MCSymbol &EmitCIE(const MCDwarfFrameInfo &F);
1242 void EmitFDE(const MCSymbol &cieStart, const MCDwarfFrameInfo &frame,
1243 bool LastInSection, const MCSymbol &SectionStart);
1244 void EmitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs,
1245 MCSymbol *BaseLabel);
1246 void EmitCFIInstruction(const MCCFIInstruction &Instr);
1249 } // end anonymous namespace
1251 static void emitEncodingByte(MCObjectStreamer &Streamer, unsigned Encoding) {
1252 Streamer.EmitIntValue(Encoding, 1);
1255 void FrameEmitterImpl::EmitCFIInstruction(const MCCFIInstruction &Instr) {
1256 int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
1257 auto *MRI = Streamer.getContext().getRegisterInfo();
1259 switch (Instr.getOperation()) {
1260 case MCCFIInstruction::OpRegister: {
1261 unsigned Reg1 = Instr.getRegister();
1262 unsigned Reg2 = Instr.getRegister2();
1264 Reg1 = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg1);
1265 Reg2 = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg2);
1267 Streamer.EmitIntValue(dwarf::DW_CFA_register, 1);
1268 Streamer.EmitULEB128IntValue(Reg1);
1269 Streamer.EmitULEB128IntValue(Reg2);
1272 case MCCFIInstruction::OpWindowSave:
1273 Streamer.EmitIntValue(dwarf::DW_CFA_GNU_window_save, 1);
1276 case MCCFIInstruction::OpUndefined: {
1277 unsigned Reg = Instr.getRegister();
1278 Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1);
1279 Streamer.EmitULEB128IntValue(Reg);
1282 case MCCFIInstruction::OpAdjustCfaOffset:
1283 case MCCFIInstruction::OpDefCfaOffset: {
1284 const bool IsRelative =
1285 Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset;
1287 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
1290 CFAOffset += Instr.getOffset();
1292 CFAOffset = -Instr.getOffset();
1294 Streamer.EmitULEB128IntValue(CFAOffset);
1298 case MCCFIInstruction::OpDefCfa: {
1299 unsigned Reg = Instr.getRegister();
1301 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
1302 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
1303 Streamer.EmitULEB128IntValue(Reg);
1304 CFAOffset = -Instr.getOffset();
1305 Streamer.EmitULEB128IntValue(CFAOffset);
1309 case MCCFIInstruction::OpDefCfaRegister: {
1310 unsigned Reg = Instr.getRegister();
1312 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
1313 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
1314 Streamer.EmitULEB128IntValue(Reg);
1318 case MCCFIInstruction::OpOffset:
1319 case MCCFIInstruction::OpRelOffset: {
1320 const bool IsRelative =
1321 Instr.getOperation() == MCCFIInstruction::OpRelOffset;
1323 unsigned Reg = Instr.getRegister();
1325 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
1327 int Offset = Instr.getOffset();
1329 Offset -= CFAOffset;
1330 Offset = Offset / dataAlignmentFactor;
1333 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
1334 Streamer.EmitULEB128IntValue(Reg);
1335 Streamer.EmitSLEB128IntValue(Offset);
1336 } else if (Reg < 64) {
1337 Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
1338 Streamer.EmitULEB128IntValue(Offset);
1340 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
1341 Streamer.EmitULEB128IntValue(Reg);
1342 Streamer.EmitULEB128IntValue(Offset);
1346 case MCCFIInstruction::OpRememberState:
1347 Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
1349 case MCCFIInstruction::OpRestoreState:
1350 Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
1352 case MCCFIInstruction::OpSameValue: {
1353 unsigned Reg = Instr.getRegister();
1354 Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
1355 Streamer.EmitULEB128IntValue(Reg);
1358 case MCCFIInstruction::OpRestore: {
1359 unsigned Reg = Instr.getRegister();
1361 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
1362 Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1);
1365 case MCCFIInstruction::OpGnuArgsSize:
1366 Streamer.EmitIntValue(dwarf::DW_CFA_GNU_args_size, 1);
1367 Streamer.EmitULEB128IntValue(Instr.getOffset());
1370 case MCCFIInstruction::OpEscape:
1371 Streamer.EmitBytes(Instr.getValues());
1374 llvm_unreachable("Unhandled case in switch");
1377 /// Emit frame instructions to describe the layout of the frame.
1378 void FrameEmitterImpl::EmitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs,
1379 MCSymbol *BaseLabel) {
1380 for (const MCCFIInstruction &Instr : Instrs) {
1381 MCSymbol *Label = Instr.getLabel();
1382 // Throw out move if the label is invalid.
1383 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
1385 // Advance row if new location.
1386 if (BaseLabel && Label) {
1387 MCSymbol *ThisSym = Label;
1388 if (ThisSym != BaseLabel) {
1389 Streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
1390 BaseLabel = ThisSym;
1394 EmitCFIInstruction(Instr);
1398 /// Emit the unwind information in a compact way.
1399 void FrameEmitterImpl::EmitCompactUnwind(const MCDwarfFrameInfo &Frame) {
1400 MCContext &Context = Streamer.getContext();
1401 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1403 // range-start range-length compact-unwind-enc personality-func lsda
1404 // _foo LfooEnd-_foo 0x00000023 0 0
1405 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1
1407 // .section __LD,__compact_unwind,regular,debug
1409 // # compact unwind for _foo
1411 // .set L1,LfooEnd-_foo
1417 // # compact unwind for _bar
1419 // .set L2,LbarEnd-_bar
1422 // .quad __gxx_personality
1423 // .quad except_tab1
1425 uint32_t Encoding = Frame.CompactUnwindEncoding;
1426 if (!Encoding) return;
1427 bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly());
1429 // The encoding needs to know we have an LSDA.
1430 if (!DwarfEHFrameOnly && Frame.Lsda)
1431 Encoding |= 0x40000000;
1434 unsigned FDEEncoding = MOFI->getFDEEncoding();
1435 unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
1436 Streamer.EmitSymbolValue(Frame.Begin, Size);
1439 const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin,
1441 emitAbsValue(Streamer, Range, 4);
1444 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
1445 Streamer.EmitIntValue(Encoding, Size);
1447 // Personality Function
1448 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
1449 if (!DwarfEHFrameOnly && Frame.Personality)
1450 Streamer.EmitSymbolValue(Frame.Personality, Size);
1452 Streamer.EmitIntValue(0, Size); // No personality fn
1455 Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
1456 if (!DwarfEHFrameOnly && Frame.Lsda)
1457 Streamer.EmitSymbolValue(Frame.Lsda, Size);
1459 Streamer.EmitIntValue(0, Size); // No LSDA
1462 static unsigned getCIEVersion(bool IsEH, unsigned DwarfVersion) {
1465 switch (DwarfVersion) {
1474 llvm_unreachable("Unknown version");
1477 const MCSymbol &FrameEmitterImpl::EmitCIE(const MCDwarfFrameInfo &Frame) {
1478 MCContext &context = Streamer.getContext();
1479 const MCRegisterInfo *MRI = context.getRegisterInfo();
1480 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1482 MCSymbol *sectionStart = context.createTempSymbol();
1483 Streamer.EmitLabel(sectionStart);
1485 MCSymbol *sectionEnd = context.createTempSymbol();
1488 const MCExpr *Length =
1489 MakeStartMinusEndExpr(Streamer, *sectionStart, *sectionEnd, 4);
1490 emitAbsValue(Streamer, Length, 4);
1493 unsigned CIE_ID = IsEH ? 0 : -1;
1494 Streamer.EmitIntValue(CIE_ID, 4);
1497 uint8_t CIEVersion = getCIEVersion(IsEH, context.getDwarfVersion());
1498 Streamer.EmitIntValue(CIEVersion, 1);
1500 // Augmentation String
1501 SmallString<8> Augmentation;
1503 Augmentation += "z";
1504 if (Frame.Personality)
1505 Augmentation += "P";
1507 Augmentation += "L";
1508 Augmentation += "R";
1509 if (Frame.IsSignalFrame)
1510 Augmentation += "S";
1511 Streamer.EmitBytes(Augmentation);
1513 Streamer.EmitIntValue(0, 1);
1515 if (CIEVersion >= 4) {
1517 Streamer.EmitIntValue(context.getAsmInfo()->getCodePointerSize(), 1);
1519 // Segment Descriptor Size
1520 Streamer.EmitIntValue(0, 1);
1523 // Code Alignment Factor
1524 Streamer.EmitULEB128IntValue(context.getAsmInfo()->getMinInstAlignment());
1526 // Data Alignment Factor
1527 Streamer.EmitSLEB128IntValue(getDataAlignmentFactor(Streamer));
1529 // Return Address Register
1530 unsigned RAReg = Frame.RAReg;
1531 if (RAReg == static_cast<unsigned>(INT_MAX))
1532 RAReg = MRI->getDwarfRegNum(MRI->getRARegister(), IsEH);
1534 if (CIEVersion == 1) {
1535 assert(RAReg <= 255 &&
1536 "DWARF 2 encodes return_address_register in one byte");
1537 Streamer.EmitIntValue(RAReg, 1);
1539 Streamer.EmitULEB128IntValue(RAReg);
1542 // Augmentation Data Length (optional)
1543 unsigned augmentationLength = 0;
1545 if (Frame.Personality) {
1546 // Personality Encoding
1547 augmentationLength += 1;
1549 augmentationLength +=
1550 getSizeForEncoding(Streamer, Frame.PersonalityEncoding);
1553 augmentationLength += 1;
1554 // Encoding of the FDE pointers
1555 augmentationLength += 1;
1557 Streamer.EmitULEB128IntValue(augmentationLength);
1559 // Augmentation Data (optional)
1560 if (Frame.Personality) {
1561 // Personality Encoding
1562 emitEncodingByte(Streamer, Frame.PersonalityEncoding);
1564 EmitPersonality(Streamer, *Frame.Personality, Frame.PersonalityEncoding);
1568 emitEncodingByte(Streamer, Frame.LsdaEncoding);
1570 // Encoding of the FDE pointers
1571 emitEncodingByte(Streamer, MOFI->getFDEEncoding());
1574 // Initial Instructions
1576 const MCAsmInfo *MAI = context.getAsmInfo();
1577 if (!Frame.IsSimple) {
1578 const std::vector<MCCFIInstruction> &Instructions =
1579 MAI->getInitialFrameState();
1580 EmitCFIInstructions(Instructions, nullptr);
1583 InitialCFAOffset = CFAOffset;
1586 Streamer.EmitValueToAlignment(IsEH ? 4 : MAI->getCodePointerSize());
1588 Streamer.EmitLabel(sectionEnd);
1589 return *sectionStart;
1592 void FrameEmitterImpl::EmitFDE(const MCSymbol &cieStart,
1593 const MCDwarfFrameInfo &frame,
1595 const MCSymbol &SectionStart) {
1596 MCContext &context = Streamer.getContext();
1597 MCSymbol *fdeStart = context.createTempSymbol();
1598 MCSymbol *fdeEnd = context.createTempSymbol();
1599 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1601 CFAOffset = InitialCFAOffset;
1604 const MCExpr *Length = MakeStartMinusEndExpr(Streamer, *fdeStart, *fdeEnd, 0);
1605 emitAbsValue(Streamer, Length, 4);
1607 Streamer.EmitLabel(fdeStart);
1610 const MCAsmInfo *asmInfo = context.getAsmInfo();
1612 const MCExpr *offset =
1613 MakeStartMinusEndExpr(Streamer, cieStart, *fdeStart, 0);
1614 emitAbsValue(Streamer, offset, 4);
1615 } else if (!asmInfo->doesDwarfUseRelocationsAcrossSections()) {
1616 const MCExpr *offset =
1617 MakeStartMinusEndExpr(Streamer, SectionStart, cieStart, 0);
1618 emitAbsValue(Streamer, offset, 4);
1620 Streamer.EmitSymbolValue(&cieStart, 4);
1624 unsigned PCEncoding =
1625 IsEH ? MOFI->getFDEEncoding() : (unsigned)dwarf::DW_EH_PE_absptr;
1626 unsigned PCSize = getSizeForEncoding(Streamer, PCEncoding);
1627 emitFDESymbol(Streamer, *frame.Begin, PCEncoding, IsEH);
1630 const MCExpr *Range =
1631 MakeStartMinusEndExpr(Streamer, *frame.Begin, *frame.End, 0);
1632 emitAbsValue(Streamer, Range, PCSize);
1635 // Augmentation Data Length
1636 unsigned augmentationLength = 0;
1639 augmentationLength += getSizeForEncoding(Streamer, frame.LsdaEncoding);
1641 Streamer.EmitULEB128IntValue(augmentationLength);
1643 // Augmentation Data
1645 emitFDESymbol(Streamer, *frame.Lsda, frame.LsdaEncoding, true);
1648 // Call Frame Instructions
1649 EmitCFIInstructions(frame.Instructions, frame.Begin);
1652 // The size of a .eh_frame section has to be a multiple of the alignment
1653 // since a null CIE is interpreted as the end. Old systems overaligned
1654 // .eh_frame, so we do too and account for it in the last FDE.
1655 unsigned Align = LastInSection ? asmInfo->getCodePointerSize() : PCSize;
1656 Streamer.EmitValueToAlignment(Align);
1658 Streamer.EmitLabel(fdeEnd);
1664 static const CIEKey getEmptyKey() {
1665 return CIEKey(nullptr, 0, -1, false, false, static_cast<unsigned>(INT_MAX));
1668 static const CIEKey getTombstoneKey() {
1669 return CIEKey(nullptr, -1, 0, false, false, static_cast<unsigned>(INT_MAX));
1672 CIEKey(const MCSymbol *Personality, unsigned PersonalityEncoding,
1673 unsigned LSDAEncoding, bool IsSignalFrame, bool IsSimple,
1675 : Personality(Personality), PersonalityEncoding(PersonalityEncoding),
1676 LsdaEncoding(LSDAEncoding), IsSignalFrame(IsSignalFrame),
1677 IsSimple(IsSimple), RAReg(RAReg) {}
1679 explicit CIEKey(const MCDwarfFrameInfo &Frame)
1680 : Personality(Frame.Personality),
1681 PersonalityEncoding(Frame.PersonalityEncoding),
1682 LsdaEncoding(Frame.LsdaEncoding), IsSignalFrame(Frame.IsSignalFrame),
1683 IsSimple(Frame.IsSimple), RAReg(Frame.RAReg) {}
1685 const MCSymbol *Personality;
1686 unsigned PersonalityEncoding;
1687 unsigned LsdaEncoding;
1693 } // end anonymous namespace
1697 template <> struct DenseMapInfo<CIEKey> {
1698 static CIEKey getEmptyKey() { return CIEKey::getEmptyKey(); }
1699 static CIEKey getTombstoneKey() { return CIEKey::getTombstoneKey(); }
1701 static unsigned getHashValue(const CIEKey &Key) {
1702 return static_cast<unsigned>(
1703 hash_combine(Key.Personality, Key.PersonalityEncoding, Key.LsdaEncoding,
1704 Key.IsSignalFrame, Key.IsSimple, Key.RAReg));
1707 static bool isEqual(const CIEKey &LHS, const CIEKey &RHS) {
1708 return LHS.Personality == RHS.Personality &&
1709 LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
1710 LHS.LsdaEncoding == RHS.LsdaEncoding &&
1711 LHS.IsSignalFrame == RHS.IsSignalFrame &&
1712 LHS.IsSimple == RHS.IsSimple &&
1713 LHS.RAReg == RHS.RAReg;
1717 } // end namespace llvm
1719 void MCDwarfFrameEmitter::Emit(MCObjectStreamer &Streamer, MCAsmBackend *MAB,
1721 Streamer.generateCompactUnwindEncodings(MAB);
1723 MCContext &Context = Streamer.getContext();
1724 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1725 const MCAsmInfo *AsmInfo = Context.getAsmInfo();
1726 FrameEmitterImpl Emitter(IsEH, Streamer);
1727 ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getDwarfFrameInfos();
1729 // Emit the compact unwind info if available.
1730 bool NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame();
1731 if (IsEH && MOFI->getCompactUnwindSection()) {
1732 bool SectionEmitted = false;
1733 for (const MCDwarfFrameInfo &Frame : FrameArray) {
1734 if (Frame.CompactUnwindEncoding == 0) continue;
1735 if (!SectionEmitted) {
1736 Streamer.SwitchSection(MOFI->getCompactUnwindSection());
1737 Streamer.EmitValueToAlignment(AsmInfo->getCodePointerSize());
1738 SectionEmitted = true;
1740 NeedsEHFrameSection |=
1741 Frame.CompactUnwindEncoding ==
1742 MOFI->getCompactUnwindDwarfEHFrameOnly();
1743 Emitter.EmitCompactUnwind(Frame);
1747 if (!NeedsEHFrameSection) return;
1749 MCSection &Section =
1750 IsEH ? *const_cast<MCObjectFileInfo *>(MOFI)->getEHFrameSection()
1751 : *MOFI->getDwarfFrameSection();
1753 Streamer.SwitchSection(&Section);
1754 MCSymbol *SectionStart = Context.createTempSymbol();
1755 Streamer.EmitLabel(SectionStart);
1757 DenseMap<CIEKey, const MCSymbol *> CIEStarts;
1759 const MCSymbol *DummyDebugKey = nullptr;
1760 bool CanOmitDwarf = MOFI->getOmitDwarfIfHaveCompactUnwind();
1761 for (auto I = FrameArray.begin(), E = FrameArray.end(); I != E;) {
1762 const MCDwarfFrameInfo &Frame = *I;
1764 if (CanOmitDwarf && Frame.CompactUnwindEncoding !=
1765 MOFI->getCompactUnwindDwarfEHFrameOnly())
1766 // Don't generate an EH frame if we don't need one. I.e., it's taken care
1767 // of by the compact unwind encoding.
1771 const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
1773 CIEStart = &Emitter.EmitCIE(Frame);
1775 Emitter.EmitFDE(*CIEStart, Frame, I == E, *SectionStart);
1779 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCObjectStreamer &Streamer,
1780 uint64_t AddrDelta) {
1781 MCContext &Context = Streamer.getContext();
1782 SmallString<256> Tmp;
1783 raw_svector_ostream OS(Tmp);
1784 MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OS);
1785 Streamer.EmitBytes(OS.str());
1788 void MCDwarfFrameEmitter::EncodeAdvanceLoc(MCContext &Context,
1791 // Scale the address delta by the minimum instruction length.
1792 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
1794 if (AddrDelta == 0) {
1795 } else if (isUIntN(6, AddrDelta)) {
1796 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
1798 } else if (isUInt<8>(AddrDelta)) {
1799 OS << uint8_t(dwarf::DW_CFA_advance_loc1);
1800 OS << uint8_t(AddrDelta);
1801 } else if (isUInt<16>(AddrDelta)) {
1802 OS << uint8_t(dwarf::DW_CFA_advance_loc2);
1803 if (Context.getAsmInfo()->isLittleEndian())
1804 support::endian::Writer<support::little>(OS).write<uint16_t>(AddrDelta);
1806 support::endian::Writer<support::big>(OS).write<uint16_t>(AddrDelta);
1808 assert(isUInt<32>(AddrDelta));
1809 OS << uint8_t(dwarf::DW_CFA_advance_loc4);
1810 if (Context.getAsmInfo()->isLittleEndian())
1811 support::endian::Writer<support::little>(OS).write<uint32_t>(AddrDelta);
1813 support::endian::Writer<support::big>(OS).write<uint32_t>(AddrDelta);