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/None.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/Support/Casting.h"
32 #include "llvm/Support/Endian.h"
33 #include "llvm/Support/EndianStream.h"
34 #include "llvm/Support/ErrorHandling.h"
35 #include "llvm/Support/LEB128.h"
36 #include "llvm/Support/MathExtras.h"
37 #include "llvm/Support/Path.h"
38 #include "llvm/Support/SourceMgr.h"
39 #include "llvm/Support/raw_ostream.h"
48 static inline uint64_t ScaleAddrDelta(MCContext &Context, uint64_t AddrDelta) {
49 unsigned MinInsnLength = Context.getAsmInfo()->getMinInstAlignment();
50 if (MinInsnLength == 1)
52 if (AddrDelta % MinInsnLength != 0) {
53 // TODO: report this error, but really only once.
56 return AddrDelta / MinInsnLength;
60 // This is called when an instruction is assembled into the specified section
61 // and if there is information from the last .loc directive that has yet to have
62 // a line entry made for it is made.
64 void MCDwarfLineEntry::Make(MCObjectStreamer *MCOS, MCSection *Section) {
65 if (!MCOS->getContext().getDwarfLocSeen())
68 // Create a symbol at in the current section for use in the line entry.
69 MCSymbol *LineSym = MCOS->getContext().createTempSymbol();
70 // Set the value of the symbol to use for the MCDwarfLineEntry.
71 MCOS->EmitLabel(LineSym);
73 // Get the current .loc info saved in the context.
74 const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();
76 // Create a (local) line entry with the symbol and the current .loc info.
77 MCDwarfLineEntry LineEntry(LineSym, DwarfLoc);
79 // clear DwarfLocSeen saying the current .loc info is now used.
80 MCOS->getContext().clearDwarfLocSeen();
82 // Add the line entry to this section's entries.
84 .getMCDwarfLineTable(MCOS->getContext().getDwarfCompileUnitID())
86 .addLineEntry(LineEntry, Section);
90 // This helper routine returns an expression of End - Start + IntVal .
92 static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS,
93 const MCSymbol &Start,
96 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
98 MCSymbolRefExpr::create(&End, Variant, MCOS.getContext());
100 MCSymbolRefExpr::create(&Start, Variant, MCOS.getContext());
102 MCBinaryExpr::create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext());
104 MCConstantExpr::create(IntVal, MCOS.getContext());
106 MCBinaryExpr::create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext());
111 // This emits the Dwarf line table for the specified section from the entries
112 // in the LineSection.
115 EmitDwarfLineTable(MCObjectStreamer *MCOS, MCSection *Section,
116 const MCLineSection::MCDwarfLineEntryCollection &LineEntries) {
117 unsigned FileNum = 1;
118 unsigned LastLine = 1;
120 unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
122 unsigned Discriminator = 0;
123 MCSymbol *LastLabel = nullptr;
125 // Loop through each MCDwarfLineEntry and encode the dwarf line number table.
126 for (const MCDwarfLineEntry &LineEntry : LineEntries) {
127 int64_t LineDelta = static_cast<int64_t>(LineEntry.getLine()) - LastLine;
129 if (FileNum != LineEntry.getFileNum()) {
130 FileNum = LineEntry.getFileNum();
131 MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
132 MCOS->EmitULEB128IntValue(FileNum);
134 if (Column != LineEntry.getColumn()) {
135 Column = LineEntry.getColumn();
136 MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
137 MCOS->EmitULEB128IntValue(Column);
139 if (Discriminator != LineEntry.getDiscriminator() &&
140 MCOS->getContext().getDwarfVersion() >= 4) {
141 Discriminator = LineEntry.getDiscriminator();
142 unsigned Size = getULEB128Size(Discriminator);
143 MCOS->EmitIntValue(dwarf::DW_LNS_extended_op, 1);
144 MCOS->EmitULEB128IntValue(Size + 1);
145 MCOS->EmitIntValue(dwarf::DW_LNE_set_discriminator, 1);
146 MCOS->EmitULEB128IntValue(Discriminator);
148 if (Isa != LineEntry.getIsa()) {
149 Isa = LineEntry.getIsa();
150 MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
151 MCOS->EmitULEB128IntValue(Isa);
153 if ((LineEntry.getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
154 Flags = LineEntry.getFlags();
155 MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
157 if (LineEntry.getFlags() & DWARF2_FLAG_BASIC_BLOCK)
158 MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
159 if (LineEntry.getFlags() & DWARF2_FLAG_PROLOGUE_END)
160 MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
161 if (LineEntry.getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
162 MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
164 MCSymbol *Label = LineEntry.getLabel();
166 // At this point we want to emit/create the sequence to encode the delta in
167 // line numbers and the increment of the address from the previous Label
168 // and the current Label.
169 const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo();
170 MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label,
171 asmInfo->getCodePointerSize());
174 LastLine = LineEntry.getLine();
178 // Emit a DW_LNE_end_sequence for the end of the section.
179 // Use the section end label to compute the address delta and use INT64_MAX
180 // as the line delta which is the signal that this is actually a
181 // DW_LNE_end_sequence.
182 MCSymbol *SectionEnd = MCOS->endSection(Section);
184 // Switch back the dwarf line section, in case endSection had to switch the
186 MCContext &Ctx = MCOS->getContext();
187 MCOS->SwitchSection(Ctx.getObjectFileInfo()->getDwarfLineSection());
189 const MCAsmInfo *AsmInfo = Ctx.getAsmInfo();
190 MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd,
191 AsmInfo->getCodePointerSize());
195 // This emits the Dwarf file and the line tables.
197 void MCDwarfLineTable::Emit(MCObjectStreamer *MCOS,
198 MCDwarfLineTableParams Params) {
199 MCContext &context = MCOS->getContext();
201 auto &LineTables = context.getMCDwarfLineTables();
203 // Bail out early so we don't switch to the debug_line section needlessly and
204 // in doing so create an unnecessary (if empty) section.
205 if (LineTables.empty())
208 // Switch to the section where the table will be emitted into.
209 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
211 // Handle the rest of the Compile Units.
212 for (const auto &CUIDTablePair : LineTables)
213 CUIDTablePair.second.EmitCU(MCOS, Params);
216 void MCDwarfDwoLineTable::Emit(MCStreamer &MCOS,
217 MCDwarfLineTableParams Params) const {
218 MCOS.EmitLabel(Header.Emit(&MCOS, Params, None).second);
221 std::pair<MCSymbol *, MCSymbol *>
222 MCDwarfLineTableHeader::Emit(MCStreamer *MCOS,
223 MCDwarfLineTableParams Params) const {
224 static const char StandardOpcodeLengths[] = {
225 0, // length of DW_LNS_copy
226 1, // length of DW_LNS_advance_pc
227 1, // length of DW_LNS_advance_line
228 1, // length of DW_LNS_set_file
229 1, // length of DW_LNS_set_column
230 0, // length of DW_LNS_negate_stmt
231 0, // length of DW_LNS_set_basic_block
232 0, // length of DW_LNS_const_add_pc
233 1, // length of DW_LNS_fixed_advance_pc
234 0, // length of DW_LNS_set_prologue_end
235 0, // length of DW_LNS_set_epilogue_begin
238 assert(array_lengthof(StandardOpcodeLengths) >=
239 (Params.DWARF2LineOpcodeBase - 1U));
240 return Emit(MCOS, Params, makeArrayRef(StandardOpcodeLengths,
241 Params.DWARF2LineOpcodeBase - 1));
244 static const MCExpr *forceExpAbs(MCStreamer &OS, const MCExpr* Expr) {
245 MCContext &Context = OS.getContext();
246 assert(!isa<MCSymbolRefExpr>(Expr));
247 if (Context.getAsmInfo()->hasAggressiveSymbolFolding())
250 MCSymbol *ABS = Context.createTempSymbol();
251 OS.EmitAssignment(ABS, Expr);
252 return MCSymbolRefExpr::create(ABS, Context);
255 static void emitAbsValue(MCStreamer &OS, const MCExpr *Value, unsigned Size) {
256 const MCExpr *ABS = forceExpAbs(OS, Value);
257 OS.EmitValue(ABS, Size);
261 emitV2FileDirTables(MCStreamer *MCOS,
262 const SmallVectorImpl<std::string> &MCDwarfDirs,
263 const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles) {
264 // First the directory table.
265 for (auto Dir : MCDwarfDirs) {
266 MCOS->EmitBytes(Dir); // The DirectoryName, and...
267 MCOS->EmitBytes(StringRef("\0", 1)); // its null terminator.
269 MCOS->EmitIntValue(0, 1); // Terminate the directory list.
271 // Second the file table.
272 for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
273 assert(!MCDwarfFiles[i].Name.empty());
274 MCOS->EmitBytes(MCDwarfFiles[i].Name); // FileName and...
275 MCOS->EmitBytes(StringRef("\0", 1)); // its null terminator.
276 MCOS->EmitULEB128IntValue(MCDwarfFiles[i].DirIndex); // Directory number.
277 MCOS->EmitIntValue(0, 1); // Last modification timestamp (always 0).
278 MCOS->EmitIntValue(0, 1); // File size (always 0).
280 MCOS->EmitIntValue(0, 1); // Terminate the file list.
284 emitV5FileDirTables(MCStreamer *MCOS,
285 const SmallVectorImpl<std::string> &MCDwarfDirs,
286 const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles,
287 StringRef CompilationDir) {
288 // The directory format, which is just inline null-terminated strings.
289 MCOS->EmitIntValue(1, 1);
290 MCOS->EmitULEB128IntValue(dwarf::DW_LNCT_path);
291 MCOS->EmitULEB128IntValue(dwarf::DW_FORM_string);
292 // Then the list of directory paths. CompilationDir comes first.
293 MCOS->EmitULEB128IntValue(MCDwarfDirs.size() + 1);
294 MCOS->EmitBytes(CompilationDir);
295 MCOS->EmitBytes(StringRef("\0", 1));
296 for (auto Dir : MCDwarfDirs) {
297 MCOS->EmitBytes(Dir); // The DirectoryName, and...
298 MCOS->EmitBytes(StringRef("\0", 1)); // its null terminator.
301 // The file format, which is the inline null-terminated filename and a
302 // directory index. We don't track file size/timestamp so don't emit them
304 // FIXME: Arrange to emit MD5 signatures for the source files.
305 MCOS->EmitIntValue(2, 1);
306 MCOS->EmitULEB128IntValue(dwarf::DW_LNCT_path);
307 MCOS->EmitULEB128IntValue(dwarf::DW_FORM_string);
308 MCOS->EmitULEB128IntValue(dwarf::DW_LNCT_directory_index);
309 MCOS->EmitULEB128IntValue(dwarf::DW_FORM_udata);
310 // Then the list of file names. These start at 1 for some reason.
311 MCOS->EmitULEB128IntValue(MCDwarfFiles.size() - 1);
312 for (unsigned i = 1; i < MCDwarfFiles.size(); ++i) {
313 assert(!MCDwarfFiles[i].Name.empty());
314 MCOS->EmitBytes(MCDwarfFiles[i].Name); // FileName and...
315 MCOS->EmitBytes(StringRef("\0", 1)); // its null terminator.
316 MCOS->EmitULEB128IntValue(MCDwarfFiles[i].DirIndex); // Directory number.
320 std::pair<MCSymbol *, MCSymbol *>
321 MCDwarfLineTableHeader::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
322 ArrayRef<char> StandardOpcodeLengths) const {
323 MCContext &context = MCOS->getContext();
325 // Create a symbol at the beginning of the line table.
326 MCSymbol *LineStartSym = Label;
328 LineStartSym = context.createTempSymbol();
329 // Set the value of the symbol, as we are at the start of the line table.
330 MCOS->EmitLabel(LineStartSym);
332 // Create a symbol for the end of the section (to be set when we get there).
333 MCSymbol *LineEndSym = context.createTempSymbol();
335 // The first 4 bytes is the total length of the information for this
336 // compilation unit (not including these 4 bytes for the length).
338 MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym, 4), 4);
340 // Next 2 bytes is the Version.
341 // FIXME: On Darwin we still default to V2.
342 unsigned LineTableVersion = context.getDwarfVersion();
343 if (context.getObjectFileInfo()->getTargetTriple().isOSDarwin())
344 LineTableVersion = 2;
345 MCOS->EmitIntValue(LineTableVersion, 2);
347 // Keep track of the bytes between the very start and where the header length
349 unsigned PreHeaderLengthBytes = 4 + 2;
351 // In v5, we get address info next.
352 if (LineTableVersion >= 5) {
353 MCOS->EmitIntValue(context.getAsmInfo()->getCodePointerSize(), 1);
354 MCOS->EmitIntValue(0, 1); // Segment selector; same as EmitGenDwarfAranges.
355 PreHeaderLengthBytes += 2;
358 // Create a symbol for the end of the prologue (to be set when we get there).
359 MCSymbol *ProEndSym = context.createTempSymbol(); // Lprologue_end
361 // Length of the prologue, is the next 4 bytes. This is actually the length
362 // from after the length word, to the end of the prologue.
364 MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym,
365 (PreHeaderLengthBytes + 4)),
368 // Parameters of the state machine, are next.
369 MCOS->EmitIntValue(context.getAsmInfo()->getMinInstAlignment(), 1);
370 // maximum_operations_per_instruction
371 // For non-VLIW architectures this field is always 1.
372 // FIXME: VLIW architectures need to update this field accordingly.
373 if (LineTableVersion >= 4)
374 MCOS->EmitIntValue(1, 1);
375 MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
376 MCOS->EmitIntValue(Params.DWARF2LineBase, 1);
377 MCOS->EmitIntValue(Params.DWARF2LineRange, 1);
378 MCOS->EmitIntValue(StandardOpcodeLengths.size() + 1, 1);
380 // Standard opcode lengths
381 for (char Length : StandardOpcodeLengths)
382 MCOS->EmitIntValue(Length, 1);
384 // Put out the directory and file tables. The formats vary depending on
386 if (LineTableVersion >= 5)
387 emitV5FileDirTables(MCOS, MCDwarfDirs, MCDwarfFiles, CompilationDir);
389 emitV2FileDirTables(MCOS, MCDwarfDirs, MCDwarfFiles);
391 // This is the end of the prologue, so set the value of the symbol at the
392 // end of the prologue (that was used in a previous expression).
393 MCOS->EmitLabel(ProEndSym);
395 return std::make_pair(LineStartSym, LineEndSym);
398 void MCDwarfLineTable::EmitCU(MCObjectStreamer *MCOS,
399 MCDwarfLineTableParams Params) const {
400 MCSymbol *LineEndSym = Header.Emit(MCOS, Params).second;
402 // Put out the line tables.
403 for (const auto &LineSec : MCLineSections.getMCLineEntries())
404 EmitDwarfLineTable(MCOS, LineSec.first, LineSec.second);
406 // This is the end of the section, so set the value of the symbol at the end
407 // of this section (that was used in a previous expression).
408 MCOS->EmitLabel(LineEndSym);
411 unsigned MCDwarfLineTable::getFile(StringRef &Directory, StringRef &FileName,
412 unsigned FileNumber) {
413 return Header.getFile(Directory, FileName, FileNumber);
416 unsigned MCDwarfLineTableHeader::getFile(StringRef &Directory,
418 unsigned FileNumber) {
419 if (Directory == CompilationDir)
421 if (FileName.empty()) {
422 FileName = "<stdin>";
425 assert(!FileName.empty());
426 if (FileNumber == 0) {
427 // File numbers start with 1 and/or after any file numbers
428 // allocated by inline-assembler .file directives.
429 FileNumber = MCDwarfFiles.empty() ? 1 : MCDwarfFiles.size();
430 SmallString<256> Buffer;
431 auto IterBool = SourceIdMap.insert(
432 std::make_pair((Directory + Twine('\0') + FileName).toStringRef(Buffer),
434 if (!IterBool.second)
435 return IterBool.first->second;
437 // Make space for this FileNumber in the MCDwarfFiles vector if needed.
438 if (FileNumber >= MCDwarfFiles.size())
439 MCDwarfFiles.resize(FileNumber + 1);
441 // Get the new MCDwarfFile slot for this FileNumber.
442 MCDwarfFile &File = MCDwarfFiles[FileNumber];
444 // It is an error to use see the same number more than once.
445 if (!File.Name.empty())
448 if (Directory.empty()) {
449 // Separate the directory part from the basename of the FileName.
450 StringRef tFileName = sys::path::filename(FileName);
451 if (!tFileName.empty()) {
452 Directory = sys::path::parent_path(FileName);
453 if (!Directory.empty())
454 FileName = tFileName;
458 // Find or make an entry in the MCDwarfDirs vector for this Directory.
459 // Capture directory name.
461 if (Directory.empty()) {
462 // For FileNames with no directories a DirIndex of 0 is used.
466 for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
467 if (Directory == MCDwarfDirs[DirIndex])
470 if (DirIndex >= MCDwarfDirs.size())
471 MCDwarfDirs.push_back(Directory);
472 // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
473 // no directories. MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
474 // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
475 // are stored at MCDwarfFiles[FileNumber].Name .
479 File.Name = FileName;
480 File.DirIndex = DirIndex;
482 // return the allocated FileNumber.
486 /// Utility function to emit the encoding to a streamer.
487 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
488 int64_t LineDelta, uint64_t AddrDelta) {
489 MCContext &Context = MCOS->getContext();
490 SmallString<256> Tmp;
491 raw_svector_ostream OS(Tmp);
492 MCDwarfLineAddr::Encode(Context, Params, LineDelta, AddrDelta, OS);
493 MCOS->EmitBytes(OS.str());
496 /// Given a special op, return the address skip amount (in units of
497 /// DWARF2_LINE_MIN_INSN_LENGTH).
498 static uint64_t SpecialAddr(MCDwarfLineTableParams Params, uint64_t op) {
499 return (op - Params.DWARF2LineOpcodeBase) / Params.DWARF2LineRange;
502 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
503 void MCDwarfLineAddr::Encode(MCContext &Context, MCDwarfLineTableParams Params,
504 int64_t LineDelta, uint64_t AddrDelta,
506 uint64_t Temp, Opcode;
507 bool NeedCopy = false;
509 // The maximum address skip amount that can be encoded with a special op.
510 uint64_t MaxSpecialAddrDelta = SpecialAddr(Params, 255);
512 // Scale the address delta by the minimum instruction length.
513 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
515 // A LineDelta of INT64_MAX is a signal that this is actually a
516 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
517 // end_sequence to emit the matrix entry.
518 if (LineDelta == INT64_MAX) {
519 if (AddrDelta == MaxSpecialAddrDelta)
520 OS << char(dwarf::DW_LNS_const_add_pc);
521 else if (AddrDelta) {
522 OS << char(dwarf::DW_LNS_advance_pc);
523 encodeULEB128(AddrDelta, OS);
525 OS << char(dwarf::DW_LNS_extended_op);
527 OS << char(dwarf::DW_LNE_end_sequence);
531 // Bias the line delta by the base.
532 Temp = LineDelta - Params.DWARF2LineBase;
534 // If the line increment is out of range of a special opcode, we must encode
535 // it with DW_LNS_advance_line.
536 if (Temp >= Params.DWARF2LineRange ||
537 Temp + Params.DWARF2LineOpcodeBase > 255) {
538 OS << char(dwarf::DW_LNS_advance_line);
539 encodeSLEB128(LineDelta, OS);
542 Temp = 0 - Params.DWARF2LineBase;
546 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
547 if (LineDelta == 0 && AddrDelta == 0) {
548 OS << char(dwarf::DW_LNS_copy);
552 // Bias the opcode by the special opcode base.
553 Temp += Params.DWARF2LineOpcodeBase;
555 // Avoid overflow when addr_delta is large.
556 if (AddrDelta < 256 + MaxSpecialAddrDelta) {
557 // Try using a special opcode.
558 Opcode = Temp + AddrDelta * Params.DWARF2LineRange;
564 // Try using DW_LNS_const_add_pc followed by special op.
565 Opcode = Temp + (AddrDelta - MaxSpecialAddrDelta) * Params.DWARF2LineRange;
567 OS << char(dwarf::DW_LNS_const_add_pc);
573 // Otherwise use DW_LNS_advance_pc.
574 OS << char(dwarf::DW_LNS_advance_pc);
575 encodeULEB128(AddrDelta, OS);
578 OS << char(dwarf::DW_LNS_copy);
580 assert(Temp <= 255 && "Buggy special opcode encoding.");
585 // Utility function to write a tuple for .debug_abbrev.
586 static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) {
587 MCOS->EmitULEB128IntValue(Name);
588 MCOS->EmitULEB128IntValue(Form);
591 // When generating dwarf for assembly source files this emits
592 // the data for .debug_abbrev section which contains three DIEs.
593 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
594 MCContext &context = MCOS->getContext();
595 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
597 // DW_TAG_compile_unit DIE abbrev (1).
598 MCOS->EmitULEB128IntValue(1);
599 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit);
600 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
601 EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, context.getDwarfVersion() >= 4
602 ? dwarf::DW_FORM_sec_offset
603 : dwarf::DW_FORM_data4);
604 if (context.getGenDwarfSectionSyms().size() > 1 &&
605 context.getDwarfVersion() >= 3) {
606 EmitAbbrev(MCOS, dwarf::DW_AT_ranges, context.getDwarfVersion() >= 4
607 ? dwarf::DW_FORM_sec_offset
608 : dwarf::DW_FORM_data4);
610 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
611 EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
613 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
614 if (!context.getCompilationDir().empty())
615 EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
616 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
617 if (!DwarfDebugFlags.empty())
618 EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
619 EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string);
620 EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2);
621 EmitAbbrev(MCOS, 0, 0);
623 // DW_TAG_label DIE abbrev (2).
624 MCOS->EmitULEB128IntValue(2);
625 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_label);
626 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
627 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
628 EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);
629 EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);
630 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
631 EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag);
632 EmitAbbrev(MCOS, 0, 0);
634 // DW_TAG_unspecified_parameters DIE abbrev (3).
635 MCOS->EmitULEB128IntValue(3);
636 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters);
637 MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1);
638 EmitAbbrev(MCOS, 0, 0);
640 // Terminate the abbreviations for this compilation unit.
641 MCOS->EmitIntValue(0, 1);
644 // When generating dwarf for assembly source files this emits the data for
645 // .debug_aranges section. This section contains a header and a table of pairs
646 // of PointerSize'ed values for the address and size of section(s) with line
648 static void EmitGenDwarfAranges(MCStreamer *MCOS,
649 const MCSymbol *InfoSectionSymbol) {
650 MCContext &context = MCOS->getContext();
652 auto &Sections = context.getGenDwarfSectionSyms();
654 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
656 // This will be the length of the .debug_aranges section, first account for
657 // the size of each item in the header (see below where we emit these items).
658 int Length = 4 + 2 + 4 + 1 + 1;
660 // Figure the padding after the header before the table of address and size
661 // pairs who's values are PointerSize'ed.
662 const MCAsmInfo *asmInfo = context.getAsmInfo();
663 int AddrSize = asmInfo->getCodePointerSize();
664 int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1));
665 if (Pad == 2 * AddrSize)
669 // Add the size of the pair of PointerSize'ed values for the address and size
670 // of each section we have in the table.
671 Length += 2 * AddrSize * Sections.size();
672 // And the pair of terminating zeros.
673 Length += 2 * AddrSize;
675 // Emit the header for this section.
676 // The 4 byte length not including the 4 byte value for the length.
677 MCOS->EmitIntValue(Length - 4, 4);
678 // The 2 byte version, which is 2.
679 MCOS->EmitIntValue(2, 2);
680 // The 4 byte offset to the compile unit in the .debug_info from the start
681 // of the .debug_info.
682 if (InfoSectionSymbol)
683 MCOS->EmitSymbolValue(InfoSectionSymbol, 4,
684 asmInfo->needsDwarfSectionOffsetDirective());
686 MCOS->EmitIntValue(0, 4);
687 // The 1 byte size of an address.
688 MCOS->EmitIntValue(AddrSize, 1);
689 // The 1 byte size of a segment descriptor, we use a value of zero.
690 MCOS->EmitIntValue(0, 1);
691 // Align the header with the padding if needed, before we put out the table.
692 for(int i = 0; i < Pad; i++)
693 MCOS->EmitIntValue(0, 1);
695 // Now emit the table of pairs of PointerSize'ed values for the section
696 // addresses and sizes.
697 for (MCSection *Sec : Sections) {
698 const MCSymbol *StartSymbol = Sec->getBeginSymbol();
699 MCSymbol *EndSymbol = Sec->getEndSymbol(context);
700 assert(StartSymbol && "StartSymbol must not be NULL");
701 assert(EndSymbol && "EndSymbol must not be NULL");
703 const MCExpr *Addr = MCSymbolRefExpr::create(
704 StartSymbol, MCSymbolRefExpr::VK_None, context);
705 const MCExpr *Size = MakeStartMinusEndExpr(*MCOS,
706 *StartSymbol, *EndSymbol, 0);
707 MCOS->EmitValue(Addr, AddrSize);
708 emitAbsValue(*MCOS, Size, AddrSize);
711 // And finally the pair of terminating zeros.
712 MCOS->EmitIntValue(0, AddrSize);
713 MCOS->EmitIntValue(0, AddrSize);
716 // When generating dwarf for assembly source files this emits the data for
717 // .debug_info section which contains three parts. The header, the compile_unit
718 // DIE and a list of label DIEs.
719 static void EmitGenDwarfInfo(MCStreamer *MCOS,
720 const MCSymbol *AbbrevSectionSymbol,
721 const MCSymbol *LineSectionSymbol,
722 const MCSymbol *RangesSectionSymbol) {
723 MCContext &context = MCOS->getContext();
725 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
727 // Create a symbol at the start and end of this section used in here for the
728 // expression to calculate the length in the header.
729 MCSymbol *InfoStart = context.createTempSymbol();
730 MCOS->EmitLabel(InfoStart);
731 MCSymbol *InfoEnd = context.createTempSymbol();
733 // First part: the header.
735 // The 4 byte total length of the information for this compilation unit, not
736 // including these 4 bytes.
737 const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4);
738 emitAbsValue(*MCOS, Length, 4);
740 // The 2 byte DWARF version.
741 MCOS->EmitIntValue(context.getDwarfVersion(), 2);
743 // The DWARF v5 header has unit type, address size, abbrev offset.
744 // Earlier versions have abbrev offset, address size.
745 const MCAsmInfo &AsmInfo = *context.getAsmInfo();
746 int AddrSize = AsmInfo.getCodePointerSize();
747 if (context.getDwarfVersion() >= 5) {
748 MCOS->EmitIntValue(dwarf::DW_UT_compile, 1);
749 MCOS->EmitIntValue(AddrSize, 1);
751 // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev,
752 // it is at the start of that section so this is zero.
753 if (AbbrevSectionSymbol == nullptr)
754 MCOS->EmitIntValue(0, 4);
756 MCOS->EmitSymbolValue(AbbrevSectionSymbol, 4,
757 AsmInfo.needsDwarfSectionOffsetDirective());
758 if (context.getDwarfVersion() <= 4)
759 MCOS->EmitIntValue(AddrSize, 1);
761 // Second part: the compile_unit DIE.
763 // The DW_TAG_compile_unit DIE abbrev (1).
764 MCOS->EmitULEB128IntValue(1);
766 // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section,
767 // which is at the start of that section so this is zero.
768 if (LineSectionSymbol)
769 MCOS->EmitSymbolValue(LineSectionSymbol, 4,
770 AsmInfo.needsDwarfSectionOffsetDirective());
772 MCOS->EmitIntValue(0, 4);
774 if (RangesSectionSymbol) {
775 // There are multiple sections containing code, so we must use the
776 // .debug_ranges sections.
778 // AT_ranges, the 4 byte offset from the start of the .debug_ranges section
779 // to the address range list for this compilation unit.
780 MCOS->EmitSymbolValue(RangesSectionSymbol, 4);
782 // If we only have one non-empty code section, we can use the simpler
783 // AT_low_pc and AT_high_pc attributes.
785 // Find the first (and only) non-empty text section
786 auto &Sections = context.getGenDwarfSectionSyms();
787 const auto TextSection = Sections.begin();
788 assert(TextSection != Sections.end() && "No text section found");
790 MCSymbol *StartSymbol = (*TextSection)->getBeginSymbol();
791 MCSymbol *EndSymbol = (*TextSection)->getEndSymbol(context);
792 assert(StartSymbol && "StartSymbol must not be NULL");
793 assert(EndSymbol && "EndSymbol must not be NULL");
795 // AT_low_pc, the first address of the default .text section.
796 const MCExpr *Start = MCSymbolRefExpr::create(
797 StartSymbol, MCSymbolRefExpr::VK_None, context);
798 MCOS->EmitValue(Start, AddrSize);
800 // AT_high_pc, the last address of the default .text section.
801 const MCExpr *End = MCSymbolRefExpr::create(
802 EndSymbol, MCSymbolRefExpr::VK_None, context);
803 MCOS->EmitValue(End, AddrSize);
806 // AT_name, the name of the source file. Reconstruct from the first directory
807 // and file table entries.
808 const SmallVectorImpl<std::string> &MCDwarfDirs = context.getMCDwarfDirs();
809 if (MCDwarfDirs.size() > 0) {
810 MCOS->EmitBytes(MCDwarfDirs[0]);
811 MCOS->EmitBytes(sys::path::get_separator());
813 const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles =
814 MCOS->getContext().getMCDwarfFiles();
815 MCOS->EmitBytes(MCDwarfFiles[1].Name);
816 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
818 // AT_comp_dir, the working directory the assembly was done in.
819 if (!context.getCompilationDir().empty()) {
820 MCOS->EmitBytes(context.getCompilationDir());
821 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
824 // AT_APPLE_flags, the command line arguments of the assembler tool.
825 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
826 if (!DwarfDebugFlags.empty()){
827 MCOS->EmitBytes(DwarfDebugFlags);
828 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
831 // AT_producer, the version of the assembler tool.
832 StringRef DwarfDebugProducer = context.getDwarfDebugProducer();
833 if (!DwarfDebugProducer.empty())
834 MCOS->EmitBytes(DwarfDebugProducer);
836 MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM " PACKAGE_VERSION ")"));
837 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
839 // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2
840 // draft has no standard code for assembler.
841 MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2);
843 // Third part: the list of label DIEs.
845 // Loop on saved info for dwarf labels and create the DIEs for them.
846 const std::vector<MCGenDwarfLabelEntry> &Entries =
847 MCOS->getContext().getMCGenDwarfLabelEntries();
848 for (const auto &Entry : Entries) {
849 // The DW_TAG_label DIE abbrev (2).
850 MCOS->EmitULEB128IntValue(2);
852 // AT_name, of the label without any leading underbar.
853 MCOS->EmitBytes(Entry.getName());
854 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
856 // AT_decl_file, index into the file table.
857 MCOS->EmitIntValue(Entry.getFileNumber(), 4);
859 // AT_decl_line, source line number.
860 MCOS->EmitIntValue(Entry.getLineNumber(), 4);
862 // AT_low_pc, start address of the label.
863 const MCExpr *AT_low_pc = MCSymbolRefExpr::create(Entry.getLabel(),
864 MCSymbolRefExpr::VK_None, context);
865 MCOS->EmitValue(AT_low_pc, AddrSize);
867 // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype.
868 MCOS->EmitIntValue(0, 1);
870 // The DW_TAG_unspecified_parameters DIE abbrev (3).
871 MCOS->EmitULEB128IntValue(3);
873 // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's.
874 MCOS->EmitIntValue(0, 1);
877 // Add the NULL DIE terminating the Compile Unit DIE's.
878 MCOS->EmitIntValue(0, 1);
880 // Now set the value of the symbol at the end of the info section.
881 MCOS->EmitLabel(InfoEnd);
884 // When generating dwarf for assembly source files this emits the data for
885 // .debug_ranges section. We only emit one range list, which spans all of the
886 // executable sections of this file.
887 static void EmitGenDwarfRanges(MCStreamer *MCOS) {
888 MCContext &context = MCOS->getContext();
889 auto &Sections = context.getGenDwarfSectionSyms();
891 const MCAsmInfo *AsmInfo = context.getAsmInfo();
892 int AddrSize = AsmInfo->getCodePointerSize();
894 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection());
896 for (MCSection *Sec : Sections) {
897 const MCSymbol *StartSymbol = Sec->getBeginSymbol();
898 MCSymbol *EndSymbol = Sec->getEndSymbol(context);
899 assert(StartSymbol && "StartSymbol must not be NULL");
900 assert(EndSymbol && "EndSymbol must not be NULL");
902 // Emit a base address selection entry for the start of this section
903 const MCExpr *SectionStartAddr = MCSymbolRefExpr::create(
904 StartSymbol, MCSymbolRefExpr::VK_None, context);
905 MCOS->emitFill(AddrSize, 0xFF);
906 MCOS->EmitValue(SectionStartAddr, AddrSize);
908 // Emit a range list entry spanning this section
909 const MCExpr *SectionSize = MakeStartMinusEndExpr(*MCOS,
910 *StartSymbol, *EndSymbol, 0);
911 MCOS->EmitIntValue(0, AddrSize);
912 emitAbsValue(*MCOS, SectionSize, AddrSize);
915 // Emit end of list entry
916 MCOS->EmitIntValue(0, AddrSize);
917 MCOS->EmitIntValue(0, AddrSize);
921 // When generating dwarf for assembly source files this emits the Dwarf
924 void MCGenDwarfInfo::Emit(MCStreamer *MCOS) {
925 MCContext &context = MCOS->getContext();
927 // Create the dwarf sections in this order (.debug_line already created).
928 const MCAsmInfo *AsmInfo = context.getAsmInfo();
929 bool CreateDwarfSectionSymbols =
930 AsmInfo->doesDwarfUseRelocationsAcrossSections();
931 MCSymbol *LineSectionSymbol = nullptr;
932 if (CreateDwarfSectionSymbols)
933 LineSectionSymbol = MCOS->getDwarfLineTableSymbol(0);
934 MCSymbol *AbbrevSectionSymbol = nullptr;
935 MCSymbol *InfoSectionSymbol = nullptr;
936 MCSymbol *RangesSectionSymbol = nullptr;
938 // Create end symbols for each section, and remove empty sections
939 MCOS->getContext().finalizeDwarfSections(*MCOS);
941 // If there are no sections to generate debug info for, we don't need
943 if (MCOS->getContext().getGenDwarfSectionSyms().empty())
946 // We only use the .debug_ranges section if we have multiple code sections,
947 // and we are emitting a DWARF version which supports it.
948 const bool UseRangesSection =
949 MCOS->getContext().getGenDwarfSectionSyms().size() > 1 &&
950 MCOS->getContext().getDwarfVersion() >= 3;
951 CreateDwarfSectionSymbols |= UseRangesSection;
953 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
954 if (CreateDwarfSectionSymbols) {
955 InfoSectionSymbol = context.createTempSymbol();
956 MCOS->EmitLabel(InfoSectionSymbol);
958 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
959 if (CreateDwarfSectionSymbols) {
960 AbbrevSectionSymbol = context.createTempSymbol();
961 MCOS->EmitLabel(AbbrevSectionSymbol);
963 if (UseRangesSection) {
964 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection());
965 if (CreateDwarfSectionSymbols) {
966 RangesSectionSymbol = context.createTempSymbol();
967 MCOS->EmitLabel(RangesSectionSymbol);
971 assert((RangesSectionSymbol != nullptr) || !UseRangesSection);
973 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
975 // Output the data for .debug_aranges section.
976 EmitGenDwarfAranges(MCOS, InfoSectionSymbol);
978 if (UseRangesSection)
979 EmitGenDwarfRanges(MCOS);
981 // Output the data for .debug_abbrev section.
982 EmitGenDwarfAbbrev(MCOS);
984 // Output the data for .debug_info section.
985 EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol,
986 RangesSectionSymbol);
990 // When generating dwarf for assembly source files this is called when symbol
991 // for a label is created. If this symbol is not a temporary and is in the
992 // section that dwarf is being generated for, save the needed info to create
995 void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
996 SourceMgr &SrcMgr, SMLoc &Loc) {
997 // We won't create dwarf labels for temporary symbols.
998 if (Symbol->isTemporary())
1000 MCContext &context = MCOS->getContext();
1001 // We won't create dwarf labels for symbols in sections that we are not
1002 // generating debug info for.
1003 if (!context.getGenDwarfSectionSyms().count(MCOS->getCurrentSectionOnly()))
1006 // The dwarf label's name does not have the symbol name's leading
1008 StringRef Name = Symbol->getName();
1009 if (Name.startswith("_"))
1010 Name = Name.substr(1, Name.size()-1);
1012 // Get the dwarf file number to be used for the dwarf label.
1013 unsigned FileNumber = context.getGenDwarfFileNumber();
1015 // Finding the line number is the expensive part which is why we just don't
1016 // pass it in as for some symbols we won't create a dwarf label.
1017 unsigned CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
1018 unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
1020 // We create a temporary symbol for use for the AT_high_pc and AT_low_pc
1021 // values so that they don't have things like an ARM thumb bit from the
1022 // original symbol. So when used they won't get a low bit set after
1024 MCSymbol *Label = context.createTempSymbol();
1025 MCOS->EmitLabel(Label);
1027 // Create and entry for the info and add it to the other entries.
1028 MCOS->getContext().addMCGenDwarfLabelEntry(
1029 MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label));
1032 static int getDataAlignmentFactor(MCStreamer &streamer) {
1033 MCContext &context = streamer.getContext();
1034 const MCAsmInfo *asmInfo = context.getAsmInfo();
1035 int size = asmInfo->getCalleeSaveStackSlotSize();
1036 if (asmInfo->isStackGrowthDirectionUp())
1042 static unsigned getSizeForEncoding(MCStreamer &streamer,
1043 unsigned symbolEncoding) {
1044 MCContext &context = streamer.getContext();
1045 unsigned format = symbolEncoding & 0x0f;
1047 default: llvm_unreachable("Unknown Encoding");
1048 case dwarf::DW_EH_PE_absptr:
1049 case dwarf::DW_EH_PE_signed:
1050 return context.getAsmInfo()->getCodePointerSize();
1051 case dwarf::DW_EH_PE_udata2:
1052 case dwarf::DW_EH_PE_sdata2:
1054 case dwarf::DW_EH_PE_udata4:
1055 case dwarf::DW_EH_PE_sdata4:
1057 case dwarf::DW_EH_PE_udata8:
1058 case dwarf::DW_EH_PE_sdata8:
1063 static void emitFDESymbol(MCObjectStreamer &streamer, const MCSymbol &symbol,
1064 unsigned symbolEncoding, bool isEH) {
1065 MCContext &context = streamer.getContext();
1066 const MCAsmInfo *asmInfo = context.getAsmInfo();
1067 const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol,
1070 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
1071 if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH)
1072 emitAbsValue(streamer, v, size);
1074 streamer.EmitValue(v, size);
1077 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
1078 unsigned symbolEncoding) {
1079 MCContext &context = streamer.getContext();
1080 const MCAsmInfo *asmInfo = context.getAsmInfo();
1081 const MCExpr *v = asmInfo->getExprForPersonalitySymbol(&symbol,
1084 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
1085 streamer.EmitValue(v, size);
1090 class FrameEmitterImpl {
1092 int InitialCFAOffset = 0;
1094 MCObjectStreamer &Streamer;
1097 FrameEmitterImpl(bool IsEH, MCObjectStreamer &Streamer)
1098 : IsEH(IsEH), Streamer(Streamer) {}
1100 /// Emit the unwind information in a compact way.
1101 void EmitCompactUnwind(const MCDwarfFrameInfo &frame);
1103 const MCSymbol &EmitCIE(const MCDwarfFrameInfo &F);
1104 void EmitFDE(const MCSymbol &cieStart, const MCDwarfFrameInfo &frame,
1105 bool LastInSection, const MCSymbol &SectionStart);
1106 void EmitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs,
1107 MCSymbol *BaseLabel);
1108 void EmitCFIInstruction(const MCCFIInstruction &Instr);
1111 } // end anonymous namespace
1113 static void emitEncodingByte(MCObjectStreamer &Streamer, unsigned Encoding) {
1114 Streamer.EmitIntValue(Encoding, 1);
1117 void FrameEmitterImpl::EmitCFIInstruction(const MCCFIInstruction &Instr) {
1118 int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
1119 auto *MRI = Streamer.getContext().getRegisterInfo();
1121 switch (Instr.getOperation()) {
1122 case MCCFIInstruction::OpRegister: {
1123 unsigned Reg1 = Instr.getRegister();
1124 unsigned Reg2 = Instr.getRegister2();
1126 Reg1 = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg1);
1127 Reg2 = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg2);
1129 Streamer.EmitIntValue(dwarf::DW_CFA_register, 1);
1130 Streamer.EmitULEB128IntValue(Reg1);
1131 Streamer.EmitULEB128IntValue(Reg2);
1134 case MCCFIInstruction::OpWindowSave:
1135 Streamer.EmitIntValue(dwarf::DW_CFA_GNU_window_save, 1);
1138 case MCCFIInstruction::OpUndefined: {
1139 unsigned Reg = Instr.getRegister();
1140 Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1);
1141 Streamer.EmitULEB128IntValue(Reg);
1144 case MCCFIInstruction::OpAdjustCfaOffset:
1145 case MCCFIInstruction::OpDefCfaOffset: {
1146 const bool IsRelative =
1147 Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset;
1149 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
1152 CFAOffset += Instr.getOffset();
1154 CFAOffset = -Instr.getOffset();
1156 Streamer.EmitULEB128IntValue(CFAOffset);
1160 case MCCFIInstruction::OpDefCfa: {
1161 unsigned Reg = Instr.getRegister();
1163 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
1164 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
1165 Streamer.EmitULEB128IntValue(Reg);
1166 CFAOffset = -Instr.getOffset();
1167 Streamer.EmitULEB128IntValue(CFAOffset);
1171 case MCCFIInstruction::OpDefCfaRegister: {
1172 unsigned Reg = Instr.getRegister();
1174 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
1175 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
1176 Streamer.EmitULEB128IntValue(Reg);
1180 case MCCFIInstruction::OpOffset:
1181 case MCCFIInstruction::OpRelOffset: {
1182 const bool IsRelative =
1183 Instr.getOperation() == MCCFIInstruction::OpRelOffset;
1185 unsigned Reg = Instr.getRegister();
1187 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
1189 int Offset = Instr.getOffset();
1191 Offset -= CFAOffset;
1192 Offset = Offset / dataAlignmentFactor;
1195 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
1196 Streamer.EmitULEB128IntValue(Reg);
1197 Streamer.EmitSLEB128IntValue(Offset);
1198 } else if (Reg < 64) {
1199 Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
1200 Streamer.EmitULEB128IntValue(Offset);
1202 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
1203 Streamer.EmitULEB128IntValue(Reg);
1204 Streamer.EmitULEB128IntValue(Offset);
1208 case MCCFIInstruction::OpRememberState:
1209 Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
1211 case MCCFIInstruction::OpRestoreState:
1212 Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
1214 case MCCFIInstruction::OpSameValue: {
1215 unsigned Reg = Instr.getRegister();
1216 Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
1217 Streamer.EmitULEB128IntValue(Reg);
1220 case MCCFIInstruction::OpRestore: {
1221 unsigned Reg = Instr.getRegister();
1223 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
1224 Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1);
1227 case MCCFIInstruction::OpGnuArgsSize:
1228 Streamer.EmitIntValue(dwarf::DW_CFA_GNU_args_size, 1);
1229 Streamer.EmitULEB128IntValue(Instr.getOffset());
1232 case MCCFIInstruction::OpEscape:
1233 Streamer.EmitBytes(Instr.getValues());
1236 llvm_unreachable("Unhandled case in switch");
1239 /// Emit frame instructions to describe the layout of the frame.
1240 void FrameEmitterImpl::EmitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs,
1241 MCSymbol *BaseLabel) {
1242 for (const MCCFIInstruction &Instr : Instrs) {
1243 MCSymbol *Label = Instr.getLabel();
1244 // Throw out move if the label is invalid.
1245 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
1247 // Advance row if new location.
1248 if (BaseLabel && Label) {
1249 MCSymbol *ThisSym = Label;
1250 if (ThisSym != BaseLabel) {
1251 Streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
1252 BaseLabel = ThisSym;
1256 EmitCFIInstruction(Instr);
1260 /// Emit the unwind information in a compact way.
1261 void FrameEmitterImpl::EmitCompactUnwind(const MCDwarfFrameInfo &Frame) {
1262 MCContext &Context = Streamer.getContext();
1263 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1265 // range-start range-length compact-unwind-enc personality-func lsda
1266 // _foo LfooEnd-_foo 0x00000023 0 0
1267 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1
1269 // .section __LD,__compact_unwind,regular,debug
1271 // # compact unwind for _foo
1273 // .set L1,LfooEnd-_foo
1279 // # compact unwind for _bar
1281 // .set L2,LbarEnd-_bar
1284 // .quad __gxx_personality
1285 // .quad except_tab1
1287 uint32_t Encoding = Frame.CompactUnwindEncoding;
1288 if (!Encoding) return;
1289 bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly());
1291 // The encoding needs to know we have an LSDA.
1292 if (!DwarfEHFrameOnly && Frame.Lsda)
1293 Encoding |= 0x40000000;
1296 unsigned FDEEncoding = MOFI->getFDEEncoding();
1297 unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
1298 Streamer.EmitSymbolValue(Frame.Begin, Size);
1301 const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin,
1303 emitAbsValue(Streamer, Range, 4);
1306 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
1307 Streamer.EmitIntValue(Encoding, Size);
1309 // Personality Function
1310 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
1311 if (!DwarfEHFrameOnly && Frame.Personality)
1312 Streamer.EmitSymbolValue(Frame.Personality, Size);
1314 Streamer.EmitIntValue(0, Size); // No personality fn
1317 Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
1318 if (!DwarfEHFrameOnly && Frame.Lsda)
1319 Streamer.EmitSymbolValue(Frame.Lsda, Size);
1321 Streamer.EmitIntValue(0, Size); // No LSDA
1324 static unsigned getCIEVersion(bool IsEH, unsigned DwarfVersion) {
1327 switch (DwarfVersion) {
1336 llvm_unreachable("Unknown version");
1339 const MCSymbol &FrameEmitterImpl::EmitCIE(const MCDwarfFrameInfo &Frame) {
1340 MCContext &context = Streamer.getContext();
1341 const MCRegisterInfo *MRI = context.getRegisterInfo();
1342 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1344 MCSymbol *sectionStart = context.createTempSymbol();
1345 Streamer.EmitLabel(sectionStart);
1347 MCSymbol *sectionEnd = context.createTempSymbol();
1350 const MCExpr *Length =
1351 MakeStartMinusEndExpr(Streamer, *sectionStart, *sectionEnd, 4);
1352 emitAbsValue(Streamer, Length, 4);
1355 unsigned CIE_ID = IsEH ? 0 : -1;
1356 Streamer.EmitIntValue(CIE_ID, 4);
1359 uint8_t CIEVersion = getCIEVersion(IsEH, context.getDwarfVersion());
1360 Streamer.EmitIntValue(CIEVersion, 1);
1362 // Augmentation String
1363 SmallString<8> Augmentation;
1365 Augmentation += "z";
1366 if (Frame.Personality)
1367 Augmentation += "P";
1369 Augmentation += "L";
1370 Augmentation += "R";
1371 if (Frame.IsSignalFrame)
1372 Augmentation += "S";
1373 Streamer.EmitBytes(Augmentation);
1375 Streamer.EmitIntValue(0, 1);
1377 if (CIEVersion >= 4) {
1379 Streamer.EmitIntValue(context.getAsmInfo()->getCodePointerSize(), 1);
1381 // Segment Descriptor Size
1382 Streamer.EmitIntValue(0, 1);
1385 // Code Alignment Factor
1386 Streamer.EmitULEB128IntValue(context.getAsmInfo()->getMinInstAlignment());
1388 // Data Alignment Factor
1389 Streamer.EmitSLEB128IntValue(getDataAlignmentFactor(Streamer));
1391 // Return Address Register
1392 unsigned RAReg = Frame.RAReg;
1393 if (RAReg == static_cast<unsigned>(INT_MAX))
1394 RAReg = MRI->getDwarfRegNum(MRI->getRARegister(), IsEH);
1396 if (CIEVersion == 1) {
1397 assert(RAReg <= 255 &&
1398 "DWARF 2 encodes return_address_register in one byte");
1399 Streamer.EmitIntValue(RAReg, 1);
1401 Streamer.EmitULEB128IntValue(RAReg);
1404 // Augmentation Data Length (optional)
1405 unsigned augmentationLength = 0;
1407 if (Frame.Personality) {
1408 // Personality Encoding
1409 augmentationLength += 1;
1411 augmentationLength +=
1412 getSizeForEncoding(Streamer, Frame.PersonalityEncoding);
1415 augmentationLength += 1;
1416 // Encoding of the FDE pointers
1417 augmentationLength += 1;
1419 Streamer.EmitULEB128IntValue(augmentationLength);
1421 // Augmentation Data (optional)
1422 if (Frame.Personality) {
1423 // Personality Encoding
1424 emitEncodingByte(Streamer, Frame.PersonalityEncoding);
1426 EmitPersonality(Streamer, *Frame.Personality, Frame.PersonalityEncoding);
1430 emitEncodingByte(Streamer, Frame.LsdaEncoding);
1432 // Encoding of the FDE pointers
1433 emitEncodingByte(Streamer, MOFI->getFDEEncoding());
1436 // Initial Instructions
1438 const MCAsmInfo *MAI = context.getAsmInfo();
1439 if (!Frame.IsSimple) {
1440 const std::vector<MCCFIInstruction> &Instructions =
1441 MAI->getInitialFrameState();
1442 EmitCFIInstructions(Instructions, nullptr);
1445 InitialCFAOffset = CFAOffset;
1448 Streamer.EmitValueToAlignment(IsEH ? 4 : MAI->getCodePointerSize());
1450 Streamer.EmitLabel(sectionEnd);
1451 return *sectionStart;
1454 void FrameEmitterImpl::EmitFDE(const MCSymbol &cieStart,
1455 const MCDwarfFrameInfo &frame,
1457 const MCSymbol &SectionStart) {
1458 MCContext &context = Streamer.getContext();
1459 MCSymbol *fdeStart = context.createTempSymbol();
1460 MCSymbol *fdeEnd = context.createTempSymbol();
1461 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1463 CFAOffset = InitialCFAOffset;
1466 const MCExpr *Length = MakeStartMinusEndExpr(Streamer, *fdeStart, *fdeEnd, 0);
1467 emitAbsValue(Streamer, Length, 4);
1469 Streamer.EmitLabel(fdeStart);
1472 const MCAsmInfo *asmInfo = context.getAsmInfo();
1474 const MCExpr *offset =
1475 MakeStartMinusEndExpr(Streamer, cieStart, *fdeStart, 0);
1476 emitAbsValue(Streamer, offset, 4);
1477 } else if (!asmInfo->doesDwarfUseRelocationsAcrossSections()) {
1478 const MCExpr *offset =
1479 MakeStartMinusEndExpr(Streamer, SectionStart, cieStart, 0);
1480 emitAbsValue(Streamer, offset, 4);
1482 Streamer.EmitSymbolValue(&cieStart, 4);
1486 unsigned PCEncoding =
1487 IsEH ? MOFI->getFDEEncoding() : (unsigned)dwarf::DW_EH_PE_absptr;
1488 unsigned PCSize = getSizeForEncoding(Streamer, PCEncoding);
1489 emitFDESymbol(Streamer, *frame.Begin, PCEncoding, IsEH);
1492 const MCExpr *Range =
1493 MakeStartMinusEndExpr(Streamer, *frame.Begin, *frame.End, 0);
1494 emitAbsValue(Streamer, Range, PCSize);
1497 // Augmentation Data Length
1498 unsigned augmentationLength = 0;
1501 augmentationLength += getSizeForEncoding(Streamer, frame.LsdaEncoding);
1503 Streamer.EmitULEB128IntValue(augmentationLength);
1505 // Augmentation Data
1507 emitFDESymbol(Streamer, *frame.Lsda, frame.LsdaEncoding, true);
1510 // Call Frame Instructions
1511 EmitCFIInstructions(frame.Instructions, frame.Begin);
1514 // The size of a .eh_frame section has to be a multiple of the alignment
1515 // since a null CIE is interpreted as the end. Old systems overaligned
1516 // .eh_frame, so we do too and account for it in the last FDE.
1517 unsigned Align = LastInSection ? asmInfo->getCodePointerSize() : PCSize;
1518 Streamer.EmitValueToAlignment(Align);
1520 Streamer.EmitLabel(fdeEnd);
1526 static const CIEKey getEmptyKey() {
1527 return CIEKey(nullptr, 0, -1, false, false, static_cast<unsigned>(INT_MAX));
1530 static const CIEKey getTombstoneKey() {
1531 return CIEKey(nullptr, -1, 0, false, false, static_cast<unsigned>(INT_MAX));
1534 CIEKey(const MCSymbol *Personality, unsigned PersonalityEncoding,
1535 unsigned LSDAEncoding, bool IsSignalFrame, bool IsSimple,
1537 : Personality(Personality), PersonalityEncoding(PersonalityEncoding),
1538 LsdaEncoding(LSDAEncoding), IsSignalFrame(IsSignalFrame),
1539 IsSimple(IsSimple), RAReg(RAReg) {}
1541 explicit CIEKey(const MCDwarfFrameInfo &Frame)
1542 : Personality(Frame.Personality),
1543 PersonalityEncoding(Frame.PersonalityEncoding),
1544 LsdaEncoding(Frame.LsdaEncoding), IsSignalFrame(Frame.IsSignalFrame),
1545 IsSimple(Frame.IsSimple), RAReg(Frame.RAReg) {}
1547 const MCSymbol *Personality;
1548 unsigned PersonalityEncoding;
1549 unsigned LsdaEncoding;
1555 } // end anonymous namespace
1559 template <> struct DenseMapInfo<CIEKey> {
1560 static CIEKey getEmptyKey() { return CIEKey::getEmptyKey(); }
1561 static CIEKey getTombstoneKey() { return CIEKey::getTombstoneKey(); }
1563 static unsigned getHashValue(const CIEKey &Key) {
1564 return static_cast<unsigned>(
1565 hash_combine(Key.Personality, Key.PersonalityEncoding, Key.LsdaEncoding,
1566 Key.IsSignalFrame, Key.IsSimple, Key.RAReg));
1569 static bool isEqual(const CIEKey &LHS, const CIEKey &RHS) {
1570 return LHS.Personality == RHS.Personality &&
1571 LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
1572 LHS.LsdaEncoding == RHS.LsdaEncoding &&
1573 LHS.IsSignalFrame == RHS.IsSignalFrame &&
1574 LHS.IsSimple == RHS.IsSimple &&
1575 LHS.RAReg == RHS.RAReg;
1579 } // end namespace llvm
1581 void MCDwarfFrameEmitter::Emit(MCObjectStreamer &Streamer, MCAsmBackend *MAB,
1583 Streamer.generateCompactUnwindEncodings(MAB);
1585 MCContext &Context = Streamer.getContext();
1586 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1587 const MCAsmInfo *AsmInfo = Context.getAsmInfo();
1588 FrameEmitterImpl Emitter(IsEH, Streamer);
1589 ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getDwarfFrameInfos();
1591 // Emit the compact unwind info if available.
1592 bool NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame();
1593 if (IsEH && MOFI->getCompactUnwindSection()) {
1594 bool SectionEmitted = false;
1595 for (const MCDwarfFrameInfo &Frame : FrameArray) {
1596 if (Frame.CompactUnwindEncoding == 0) continue;
1597 if (!SectionEmitted) {
1598 Streamer.SwitchSection(MOFI->getCompactUnwindSection());
1599 Streamer.EmitValueToAlignment(AsmInfo->getCodePointerSize());
1600 SectionEmitted = true;
1602 NeedsEHFrameSection |=
1603 Frame.CompactUnwindEncoding ==
1604 MOFI->getCompactUnwindDwarfEHFrameOnly();
1605 Emitter.EmitCompactUnwind(Frame);
1609 if (!NeedsEHFrameSection) return;
1611 MCSection &Section =
1612 IsEH ? *const_cast<MCObjectFileInfo *>(MOFI)->getEHFrameSection()
1613 : *MOFI->getDwarfFrameSection();
1615 Streamer.SwitchSection(&Section);
1616 MCSymbol *SectionStart = Context.createTempSymbol();
1617 Streamer.EmitLabel(SectionStart);
1619 DenseMap<CIEKey, const MCSymbol *> CIEStarts;
1621 const MCSymbol *DummyDebugKey = nullptr;
1622 bool CanOmitDwarf = MOFI->getOmitDwarfIfHaveCompactUnwind();
1623 for (auto I = FrameArray.begin(), E = FrameArray.end(); I != E;) {
1624 const MCDwarfFrameInfo &Frame = *I;
1626 if (CanOmitDwarf && Frame.CompactUnwindEncoding !=
1627 MOFI->getCompactUnwindDwarfEHFrameOnly())
1628 // Don't generate an EH frame if we don't need one. I.e., it's taken care
1629 // of by the compact unwind encoding.
1633 const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
1635 CIEStart = &Emitter.EmitCIE(Frame);
1637 Emitter.EmitFDE(*CIEStart, Frame, I == E, *SectionStart);
1641 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCObjectStreamer &Streamer,
1642 uint64_t AddrDelta) {
1643 MCContext &Context = Streamer.getContext();
1644 SmallString<256> Tmp;
1645 raw_svector_ostream OS(Tmp);
1646 MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OS);
1647 Streamer.EmitBytes(OS.str());
1650 void MCDwarfFrameEmitter::EncodeAdvanceLoc(MCContext &Context,
1653 // Scale the address delta by the minimum instruction length.
1654 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
1656 if (AddrDelta == 0) {
1657 } else if (isUIntN(6, AddrDelta)) {
1658 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
1660 } else if (isUInt<8>(AddrDelta)) {
1661 OS << uint8_t(dwarf::DW_CFA_advance_loc1);
1662 OS << uint8_t(AddrDelta);
1663 } else if (isUInt<16>(AddrDelta)) {
1664 OS << uint8_t(dwarf::DW_CFA_advance_loc2);
1665 if (Context.getAsmInfo()->isLittleEndian())
1666 support::endian::Writer<support::little>(OS).write<uint16_t>(AddrDelta);
1668 support::endian::Writer<support::big>(OS).write<uint16_t>(AddrDelta);
1670 assert(isUInt<32>(AddrDelta));
1671 OS << uint8_t(dwarf::DW_CFA_advance_loc4);
1672 if (Context.getAsmInfo()->isLittleEndian())
1673 support::endian::Writer<support::little>(OS).write<uint32_t>(AddrDelta);
1675 support::endian::Writer<support::big>(OS).write<uint32_t>(AddrDelta);