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/Hashing.h"
12 #include "llvm/ADT/STLExtras.h"
13 #include "llvm/ADT/SmallString.h"
14 #include "llvm/ADT/Twine.h"
15 #include "llvm/Config/config.h"
16 #include "llvm/MC/MCAsmInfo.h"
17 #include "llvm/MC/MCContext.h"
18 #include "llvm/MC/MCExpr.h"
19 #include "llvm/MC/MCObjectFileInfo.h"
20 #include "llvm/MC/MCObjectStreamer.h"
21 #include "llvm/MC/MCRegisterInfo.h"
22 #include "llvm/MC/MCSection.h"
23 #include "llvm/MC/MCSymbol.h"
24 #include "llvm/Support/Debug.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/LEB128.h"
27 #include "llvm/Support/Path.h"
28 #include "llvm/Support/SourceMgr.h"
29 #include "llvm/Support/raw_ostream.h"
33 static inline uint64_t ScaleAddrDelta(MCContext &Context, uint64_t AddrDelta) {
34 unsigned MinInsnLength = Context.getAsmInfo()->getMinInstAlignment();
35 if (MinInsnLength == 1)
37 if (AddrDelta % MinInsnLength != 0) {
38 // TODO: report this error, but really only once.
41 return AddrDelta / MinInsnLength;
45 // This is called when an instruction is assembled into the specified section
46 // and if there is information from the last .loc directive that has yet to have
47 // a line entry made for it is made.
49 void MCLineEntry::Make(MCObjectStreamer *MCOS, MCSection *Section) {
50 if (!MCOS->getContext().getDwarfLocSeen())
53 // Create a symbol at in the current section for use in the line entry.
54 MCSymbol *LineSym = MCOS->getContext().createTempSymbol();
55 // Set the value of the symbol to use for the MCLineEntry.
56 MCOS->EmitLabel(LineSym);
58 // Get the current .loc info saved in the context.
59 const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();
61 // Create a (local) line entry with the symbol and the current .loc info.
62 MCLineEntry LineEntry(LineSym, DwarfLoc);
64 // clear DwarfLocSeen saying the current .loc info is now used.
65 MCOS->getContext().clearDwarfLocSeen();
67 // Add the line entry to this section's entries.
69 .getMCDwarfLineTable(MCOS->getContext().getDwarfCompileUnitID())
71 .addLineEntry(LineEntry, Section);
75 // This helper routine returns an expression of End - Start + IntVal .
77 static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS,
78 const MCSymbol &Start,
81 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
83 MCSymbolRefExpr::create(&End, Variant, MCOS.getContext());
85 MCSymbolRefExpr::create(&Start, Variant, MCOS.getContext());
87 MCBinaryExpr::create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext());
89 MCConstantExpr::create(IntVal, MCOS.getContext());
91 MCBinaryExpr::create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext());
96 // This emits the Dwarf line table for the specified section from the entries
97 // in the LineSection.
100 EmitDwarfLineTable(MCObjectStreamer *MCOS, MCSection *Section,
101 const MCLineSection::MCLineEntryCollection &LineEntries) {
102 unsigned FileNum = 1;
103 unsigned LastLine = 1;
105 unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
107 unsigned Discriminator = 0;
108 MCSymbol *LastLabel = nullptr;
110 // Loop through each MCLineEntry and encode the dwarf line number table.
111 for (auto it = LineEntries.begin(),
112 ie = LineEntries.end();
115 if (FileNum != it->getFileNum()) {
116 FileNum = it->getFileNum();
117 MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
118 MCOS->EmitULEB128IntValue(FileNum);
120 if (Column != it->getColumn()) {
121 Column = it->getColumn();
122 MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
123 MCOS->EmitULEB128IntValue(Column);
125 if (Discriminator != it->getDiscriminator()) {
126 Discriminator = it->getDiscriminator();
127 unsigned Size = getULEB128Size(Discriminator);
128 MCOS->EmitIntValue(dwarf::DW_LNS_extended_op, 1);
129 MCOS->EmitULEB128IntValue(Size + 1);
130 MCOS->EmitIntValue(dwarf::DW_LNE_set_discriminator, 1);
131 MCOS->EmitULEB128IntValue(Discriminator);
133 if (Isa != it->getIsa()) {
135 MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
136 MCOS->EmitULEB128IntValue(Isa);
138 if ((it->getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
139 Flags = it->getFlags();
140 MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
142 if (it->getFlags() & DWARF2_FLAG_BASIC_BLOCK)
143 MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
144 if (it->getFlags() & DWARF2_FLAG_PROLOGUE_END)
145 MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
146 if (it->getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
147 MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
149 int64_t LineDelta = static_cast<int64_t>(it->getLine()) - LastLine;
150 MCSymbol *Label = it->getLabel();
152 // At this point we want to emit/create the sequence to encode the delta in
153 // line numbers and the increment of the address from the previous Label
154 // and the current Label.
155 const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo();
156 MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label,
157 asmInfo->getPointerSize());
159 LastLine = it->getLine();
163 // Emit a DW_LNE_end_sequence for the end of the section.
164 // Use the section end label to compute the address delta and use INT64_MAX
165 // as the line delta which is the signal that this is actually a
166 // DW_LNE_end_sequence.
167 MCSymbol *SectionEnd = MCOS->endSection(Section);
169 // Switch back the dwarf line section, in case endSection had to switch the
171 MCContext &Ctx = MCOS->getContext();
172 MCOS->SwitchSection(Ctx.getObjectFileInfo()->getDwarfLineSection());
174 const MCAsmInfo *AsmInfo = Ctx.getAsmInfo();
175 MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd,
176 AsmInfo->getPointerSize());
180 // This emits the Dwarf file and the line tables.
182 void MCDwarfLineTable::Emit(MCObjectStreamer *MCOS,
183 MCDwarfLineTableParams Params) {
184 MCContext &context = MCOS->getContext();
186 auto &LineTables = context.getMCDwarfLineTables();
188 // Bail out early so we don't switch to the debug_line section needlessly and
189 // in doing so create an unnecessary (if empty) section.
190 if (LineTables.empty())
193 // Switch to the section where the table will be emitted into.
194 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
196 // Handle the rest of the Compile Units.
197 for (const auto &CUIDTablePair : LineTables)
198 CUIDTablePair.second.EmitCU(MCOS, Params);
201 void MCDwarfDwoLineTable::Emit(MCStreamer &MCOS,
202 MCDwarfLineTableParams Params) const {
203 MCOS.EmitLabel(Header.Emit(&MCOS, Params, None).second);
206 std::pair<MCSymbol *, MCSymbol *>
207 MCDwarfLineTableHeader::Emit(MCStreamer *MCOS,
208 MCDwarfLineTableParams Params) const {
209 static const char StandardOpcodeLengths[] = {
210 0, // length of DW_LNS_copy
211 1, // length of DW_LNS_advance_pc
212 1, // length of DW_LNS_advance_line
213 1, // length of DW_LNS_set_file
214 1, // length of DW_LNS_set_column
215 0, // length of DW_LNS_negate_stmt
216 0, // length of DW_LNS_set_basic_block
217 0, // length of DW_LNS_const_add_pc
218 1, // length of DW_LNS_fixed_advance_pc
219 0, // length of DW_LNS_set_prologue_end
220 0, // length of DW_LNS_set_epilogue_begin
223 assert(array_lengthof(StandardOpcodeLengths) >=
224 (Params.DWARF2LineOpcodeBase - 1U));
225 return Emit(MCOS, Params, makeArrayRef(StandardOpcodeLengths,
226 Params.DWARF2LineOpcodeBase - 1));
229 static const MCExpr *forceExpAbs(MCStreamer &OS, const MCExpr* Expr) {
230 MCContext &Context = OS.getContext();
231 assert(!isa<MCSymbolRefExpr>(Expr));
232 if (Context.getAsmInfo()->hasAggressiveSymbolFolding())
235 MCSymbol *ABS = Context.createTempSymbol();
236 OS.EmitAssignment(ABS, Expr);
237 return MCSymbolRefExpr::create(ABS, Context);
240 static void emitAbsValue(MCStreamer &OS, const MCExpr *Value, unsigned Size) {
241 const MCExpr *ABS = forceExpAbs(OS, Value);
242 OS.EmitValue(ABS, Size);
245 std::pair<MCSymbol *, MCSymbol *>
246 MCDwarfLineTableHeader::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
247 ArrayRef<char> StandardOpcodeLengths) const {
248 MCContext &context = MCOS->getContext();
250 // Create a symbol at the beginning of the line table.
251 MCSymbol *LineStartSym = Label;
253 LineStartSym = context.createTempSymbol();
254 // Set the value of the symbol, as we are at the start of the line table.
255 MCOS->EmitLabel(LineStartSym);
257 // Create a symbol for the end of the section (to be set when we get there).
258 MCSymbol *LineEndSym = context.createTempSymbol();
260 // The first 4 bytes is the total length of the information for this
261 // compilation unit (not including these 4 bytes for the length).
263 MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym, 4), 4);
265 // Next 2 bytes is the Version, which is Dwarf 2.
266 MCOS->EmitIntValue(2, 2);
268 // Create a symbol for the end of the prologue (to be set when we get there).
269 MCSymbol *ProEndSym = context.createTempSymbol(); // Lprologue_end
271 // Length of the prologue, is the next 4 bytes. Which is the start of the
272 // section to the end of the prologue. Not including the 4 bytes for the
273 // total length, the 2 bytes for the version, and these 4 bytes for the
274 // length of the prologue.
277 MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym, (4 + 2 + 4)), 4);
279 // Parameters of the state machine, are next.
280 MCOS->EmitIntValue(context.getAsmInfo()->getMinInstAlignment(), 1);
281 MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
282 MCOS->EmitIntValue(Params.DWARF2LineBase, 1);
283 MCOS->EmitIntValue(Params.DWARF2LineRange, 1);
284 MCOS->EmitIntValue(StandardOpcodeLengths.size() + 1, 1);
286 // Standard opcode lengths
287 for (char Length : StandardOpcodeLengths)
288 MCOS->EmitIntValue(Length, 1);
290 // Put out the directory and file tables.
292 // First the directory table.
293 for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
294 MCOS->EmitBytes(MCDwarfDirs[i]); // the DirectoryName
295 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
297 MCOS->EmitIntValue(0, 1); // Terminate the directory list
299 // Second the file table.
300 for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
301 assert(!MCDwarfFiles[i].Name.empty());
302 MCOS->EmitBytes(MCDwarfFiles[i].Name); // FileName
303 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
305 MCOS->EmitULEB128IntValue(MCDwarfFiles[i].DirIndex);
306 MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
307 MCOS->EmitIntValue(0, 1); // filesize (always 0)
309 MCOS->EmitIntValue(0, 1); // Terminate the file list
311 // This is the end of the prologue, so set the value of the symbol at the
312 // end of the prologue (that was used in a previous expression).
313 MCOS->EmitLabel(ProEndSym);
315 return std::make_pair(LineStartSym, LineEndSym);
318 void MCDwarfLineTable::EmitCU(MCObjectStreamer *MCOS,
319 MCDwarfLineTableParams Params) const {
320 MCSymbol *LineEndSym = Header.Emit(MCOS, Params).second;
322 // Put out the line tables.
323 for (const auto &LineSec : MCLineSections.getMCLineEntries())
324 EmitDwarfLineTable(MCOS, LineSec.first, LineSec.second);
326 // This is the end of the section, so set the value of the symbol at the end
327 // of this section (that was used in a previous expression).
328 MCOS->EmitLabel(LineEndSym);
331 unsigned MCDwarfLineTable::getFile(StringRef &Directory, StringRef &FileName,
332 unsigned FileNumber) {
333 return Header.getFile(Directory, FileName, FileNumber);
336 unsigned MCDwarfLineTableHeader::getFile(StringRef &Directory,
338 unsigned FileNumber) {
339 if (Directory == CompilationDir)
341 if (FileName.empty()) {
342 FileName = "<stdin>";
345 assert(!FileName.empty());
346 if (FileNumber == 0) {
347 FileNumber = SourceIdMap.size() + 1;
348 assert((MCDwarfFiles.empty() || FileNumber == MCDwarfFiles.size()) &&
349 "Don't mix autonumbered and explicit numbered line table usage");
350 SmallString<256> Buffer;
351 auto IterBool = SourceIdMap.insert(
352 std::make_pair((Directory + Twine('\0') + FileName).toStringRef(Buffer),
354 if (!IterBool.second)
355 return IterBool.first->second;
357 // Make space for this FileNumber in the MCDwarfFiles vector if needed.
358 MCDwarfFiles.resize(FileNumber + 1);
360 // Get the new MCDwarfFile slot for this FileNumber.
361 MCDwarfFile &File = MCDwarfFiles[FileNumber];
363 // It is an error to use see the same number more than once.
364 if (!File.Name.empty())
367 if (Directory.empty()) {
368 // Separate the directory part from the basename of the FileName.
369 StringRef tFileName = sys::path::filename(FileName);
370 if (!tFileName.empty()) {
371 Directory = sys::path::parent_path(FileName);
372 if (!Directory.empty())
373 FileName = tFileName;
377 // Find or make an entry in the MCDwarfDirs vector for this Directory.
378 // Capture directory name.
380 if (Directory.empty()) {
381 // For FileNames with no directories a DirIndex of 0 is used.
385 for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
386 if (Directory == MCDwarfDirs[DirIndex])
389 if (DirIndex >= MCDwarfDirs.size())
390 MCDwarfDirs.push_back(Directory);
391 // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
392 // no directories. MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
393 // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
394 // are stored at MCDwarfFiles[FileNumber].Name .
398 File.Name = FileName;
399 File.DirIndex = DirIndex;
401 // return the allocated FileNumber.
405 /// Utility function to emit the encoding to a streamer.
406 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
407 int64_t LineDelta, uint64_t AddrDelta) {
408 MCContext &Context = MCOS->getContext();
409 SmallString<256> Tmp;
410 raw_svector_ostream OS(Tmp);
411 MCDwarfLineAddr::Encode(Context, Params, LineDelta, AddrDelta, OS);
412 MCOS->EmitBytes(OS.str());
415 /// Given a special op, return the address skip amount (in units of
416 /// DWARF2_LINE_MIN_INSN_LENGTH).
417 static uint64_t SpecialAddr(MCDwarfLineTableParams Params, uint64_t op) {
418 return (op - Params.DWARF2LineOpcodeBase) / Params.DWARF2LineRange;
421 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
422 void MCDwarfLineAddr::Encode(MCContext &Context, MCDwarfLineTableParams Params,
423 int64_t LineDelta, uint64_t AddrDelta,
425 uint64_t Temp, Opcode;
426 bool NeedCopy = false;
428 // The maximum address skip amount that can be encoded with a special op.
429 uint64_t MaxSpecialAddrDelta = SpecialAddr(Params, 255);
431 // Scale the address delta by the minimum instruction length.
432 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
434 // A LineDelta of INT64_MAX is a signal that this is actually a
435 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
436 // end_sequence to emit the matrix entry.
437 if (LineDelta == INT64_MAX) {
438 if (AddrDelta == MaxSpecialAddrDelta)
439 OS << char(dwarf::DW_LNS_const_add_pc);
440 else if (AddrDelta) {
441 OS << char(dwarf::DW_LNS_advance_pc);
442 encodeULEB128(AddrDelta, OS);
444 OS << char(dwarf::DW_LNS_extended_op);
446 OS << char(dwarf::DW_LNE_end_sequence);
450 // Bias the line delta by the base.
451 Temp = LineDelta - Params.DWARF2LineBase;
453 // If the line increment is out of range of a special opcode, we must encode
454 // it with DW_LNS_advance_line.
455 if (Temp >= Params.DWARF2LineRange) {
456 OS << char(dwarf::DW_LNS_advance_line);
457 encodeSLEB128(LineDelta, OS);
460 Temp = 0 - Params.DWARF2LineBase;
464 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
465 if (LineDelta == 0 && AddrDelta == 0) {
466 OS << char(dwarf::DW_LNS_copy);
470 // Bias the opcode by the special opcode base.
471 Temp += Params.DWARF2LineOpcodeBase;
473 // Avoid overflow when addr_delta is large.
474 if (AddrDelta < 256 + MaxSpecialAddrDelta) {
475 // Try using a special opcode.
476 Opcode = Temp + AddrDelta * Params.DWARF2LineRange;
482 // Try using DW_LNS_const_add_pc followed by special op.
483 Opcode = Temp + (AddrDelta - MaxSpecialAddrDelta) * Params.DWARF2LineRange;
485 OS << char(dwarf::DW_LNS_const_add_pc);
491 // Otherwise use DW_LNS_advance_pc.
492 OS << char(dwarf::DW_LNS_advance_pc);
493 encodeULEB128(AddrDelta, OS);
496 OS << char(dwarf::DW_LNS_copy);
501 // Utility function to write a tuple for .debug_abbrev.
502 static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) {
503 MCOS->EmitULEB128IntValue(Name);
504 MCOS->EmitULEB128IntValue(Form);
507 // When generating dwarf for assembly source files this emits
508 // the data for .debug_abbrev section which contains three DIEs.
509 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
510 MCContext &context = MCOS->getContext();
511 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
513 // DW_TAG_compile_unit DIE abbrev (1).
514 MCOS->EmitULEB128IntValue(1);
515 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit);
516 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
517 EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list,
518 context.getDwarfVersion() >= 4 ? dwarf::DW_FORM_sec_offset
519 : dwarf::DW_FORM_data4);
520 if (context.getGenDwarfSectionSyms().size() > 1 &&
521 context.getDwarfVersion() >= 3) {
522 EmitAbbrev(MCOS, dwarf::DW_AT_ranges,
523 context.getDwarfVersion() >= 4 ? dwarf::DW_FORM_sec_offset
524 : dwarf::DW_FORM_data4);
526 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
527 EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
529 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
530 if (!context.getCompilationDir().empty())
531 EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
532 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
533 if (!DwarfDebugFlags.empty())
534 EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
535 EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string);
536 EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2);
537 EmitAbbrev(MCOS, 0, 0);
539 // DW_TAG_label DIE abbrev (2).
540 MCOS->EmitULEB128IntValue(2);
541 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_label);
542 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
543 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
544 EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);
545 EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);
546 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
547 EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag);
548 EmitAbbrev(MCOS, 0, 0);
550 // DW_TAG_unspecified_parameters DIE abbrev (3).
551 MCOS->EmitULEB128IntValue(3);
552 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters);
553 MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1);
554 EmitAbbrev(MCOS, 0, 0);
556 // Terminate the abbreviations for this compilation unit.
557 MCOS->EmitIntValue(0, 1);
560 // When generating dwarf for assembly source files this emits the data for
561 // .debug_aranges section. This section contains a header and a table of pairs
562 // of PointerSize'ed values for the address and size of section(s) with line
564 static void EmitGenDwarfAranges(MCStreamer *MCOS,
565 const MCSymbol *InfoSectionSymbol) {
566 MCContext &context = MCOS->getContext();
568 auto &Sections = context.getGenDwarfSectionSyms();
570 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
572 // This will be the length of the .debug_aranges section, first account for
573 // the size of each item in the header (see below where we emit these items).
574 int Length = 4 + 2 + 4 + 1 + 1;
576 // Figure the padding after the header before the table of address and size
577 // pairs who's values are PointerSize'ed.
578 const MCAsmInfo *asmInfo = context.getAsmInfo();
579 int AddrSize = asmInfo->getPointerSize();
580 int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1));
581 if (Pad == 2 * AddrSize)
585 // Add the size of the pair of PointerSize'ed values for the address and size
586 // of each section we have in the table.
587 Length += 2 * AddrSize * Sections.size();
588 // And the pair of terminating zeros.
589 Length += 2 * AddrSize;
592 // Emit the header for this section.
593 // The 4 byte length not including the 4 byte value for the length.
594 MCOS->EmitIntValue(Length - 4, 4);
595 // The 2 byte version, which is 2.
596 MCOS->EmitIntValue(2, 2);
597 // The 4 byte offset to the compile unit in the .debug_info from the start
598 // of the .debug_info.
599 if (InfoSectionSymbol)
600 MCOS->EmitSymbolValue(InfoSectionSymbol, 4,
601 asmInfo->needsDwarfSectionOffsetDirective());
603 MCOS->EmitIntValue(0, 4);
604 // The 1 byte size of an address.
605 MCOS->EmitIntValue(AddrSize, 1);
606 // The 1 byte size of a segment descriptor, we use a value of zero.
607 MCOS->EmitIntValue(0, 1);
608 // Align the header with the padding if needed, before we put out the table.
609 for(int i = 0; i < Pad; i++)
610 MCOS->EmitIntValue(0, 1);
612 // Now emit the table of pairs of PointerSize'ed values for the section
613 // addresses and sizes.
614 for (MCSection *Sec : Sections) {
615 const MCSymbol *StartSymbol = Sec->getBeginSymbol();
616 MCSymbol *EndSymbol = Sec->getEndSymbol(context);
617 assert(StartSymbol && "StartSymbol must not be NULL");
618 assert(EndSymbol && "EndSymbol must not be NULL");
620 const MCExpr *Addr = MCSymbolRefExpr::create(
621 StartSymbol, MCSymbolRefExpr::VK_None, context);
622 const MCExpr *Size = MakeStartMinusEndExpr(*MCOS,
623 *StartSymbol, *EndSymbol, 0);
624 MCOS->EmitValue(Addr, AddrSize);
625 emitAbsValue(*MCOS, Size, AddrSize);
628 // And finally the pair of terminating zeros.
629 MCOS->EmitIntValue(0, AddrSize);
630 MCOS->EmitIntValue(0, AddrSize);
633 // When generating dwarf for assembly source files this emits the data for
634 // .debug_info section which contains three parts. The header, the compile_unit
635 // DIE and a list of label DIEs.
636 static void EmitGenDwarfInfo(MCStreamer *MCOS,
637 const MCSymbol *AbbrevSectionSymbol,
638 const MCSymbol *LineSectionSymbol,
639 const MCSymbol *RangesSectionSymbol) {
640 MCContext &context = MCOS->getContext();
642 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
644 // Create a symbol at the start and end of this section used in here for the
645 // expression to calculate the length in the header.
646 MCSymbol *InfoStart = context.createTempSymbol();
647 MCOS->EmitLabel(InfoStart);
648 MCSymbol *InfoEnd = context.createTempSymbol();
650 // First part: the header.
652 // The 4 byte total length of the information for this compilation unit, not
653 // including these 4 bytes.
654 const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4);
655 emitAbsValue(*MCOS, Length, 4);
657 // The 2 byte DWARF version.
658 MCOS->EmitIntValue(context.getDwarfVersion(), 2);
660 const MCAsmInfo &AsmInfo = *context.getAsmInfo();
661 // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev,
662 // it is at the start of that section so this is zero.
663 if (AbbrevSectionSymbol == nullptr)
664 MCOS->EmitIntValue(0, 4);
666 MCOS->EmitSymbolValue(AbbrevSectionSymbol, 4,
667 AsmInfo.needsDwarfSectionOffsetDirective());
669 const MCAsmInfo *asmInfo = context.getAsmInfo();
670 int AddrSize = asmInfo->getPointerSize();
671 // The 1 byte size of an address.
672 MCOS->EmitIntValue(AddrSize, 1);
674 // Second part: the compile_unit DIE.
676 // The DW_TAG_compile_unit DIE abbrev (1).
677 MCOS->EmitULEB128IntValue(1);
679 // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section,
680 // which is at the start of that section so this is zero.
681 if (LineSectionSymbol)
682 MCOS->EmitSymbolValue(LineSectionSymbol, 4,
683 AsmInfo.needsDwarfSectionOffsetDirective());
685 MCOS->EmitIntValue(0, 4);
687 if (RangesSectionSymbol) {
688 // There are multiple sections containing code, so we must use the
689 // .debug_ranges sections.
691 // AT_ranges, the 4 byte offset from the start of the .debug_ranges section
692 // to the address range list for this compilation unit.
693 MCOS->EmitSymbolValue(RangesSectionSymbol, 4);
695 // If we only have one non-empty code section, we can use the simpler
696 // AT_low_pc and AT_high_pc attributes.
698 // Find the first (and only) non-empty text section
699 auto &Sections = context.getGenDwarfSectionSyms();
700 const auto TextSection = Sections.begin();
701 assert(TextSection != Sections.end() && "No text section found");
703 MCSymbol *StartSymbol = (*TextSection)->getBeginSymbol();
704 MCSymbol *EndSymbol = (*TextSection)->getEndSymbol(context);
705 assert(StartSymbol && "StartSymbol must not be NULL");
706 assert(EndSymbol && "EndSymbol must not be NULL");
708 // AT_low_pc, the first address of the default .text section.
709 const MCExpr *Start = MCSymbolRefExpr::create(
710 StartSymbol, MCSymbolRefExpr::VK_None, context);
711 MCOS->EmitValue(Start, AddrSize);
713 // AT_high_pc, the last address of the default .text section.
714 const MCExpr *End = MCSymbolRefExpr::create(
715 EndSymbol, MCSymbolRefExpr::VK_None, context);
716 MCOS->EmitValue(End, AddrSize);
719 // AT_name, the name of the source file. Reconstruct from the first directory
720 // and file table entries.
721 const SmallVectorImpl<std::string> &MCDwarfDirs = context.getMCDwarfDirs();
722 if (MCDwarfDirs.size() > 0) {
723 MCOS->EmitBytes(MCDwarfDirs[0]);
724 MCOS->EmitBytes(sys::path::get_separator());
726 const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles =
727 MCOS->getContext().getMCDwarfFiles();
728 MCOS->EmitBytes(MCDwarfFiles[1].Name);
729 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
731 // AT_comp_dir, the working directory the assembly was done in.
732 if (!context.getCompilationDir().empty()) {
733 MCOS->EmitBytes(context.getCompilationDir());
734 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
737 // AT_APPLE_flags, the command line arguments of the assembler tool.
738 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
739 if (!DwarfDebugFlags.empty()){
740 MCOS->EmitBytes(DwarfDebugFlags);
741 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
744 // AT_producer, the version of the assembler tool.
745 StringRef DwarfDebugProducer = context.getDwarfDebugProducer();
746 if (!DwarfDebugProducer.empty())
747 MCOS->EmitBytes(DwarfDebugProducer);
749 MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM " PACKAGE_VERSION ")"));
750 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
752 // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2
753 // draft has no standard code for assembler.
754 MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2);
756 // Third part: the list of label DIEs.
758 // Loop on saved info for dwarf labels and create the DIEs for them.
759 const std::vector<MCGenDwarfLabelEntry> &Entries =
760 MCOS->getContext().getMCGenDwarfLabelEntries();
761 for (const auto &Entry : Entries) {
762 // The DW_TAG_label DIE abbrev (2).
763 MCOS->EmitULEB128IntValue(2);
765 // AT_name, of the label without any leading underbar.
766 MCOS->EmitBytes(Entry.getName());
767 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
769 // AT_decl_file, index into the file table.
770 MCOS->EmitIntValue(Entry.getFileNumber(), 4);
772 // AT_decl_line, source line number.
773 MCOS->EmitIntValue(Entry.getLineNumber(), 4);
775 // AT_low_pc, start address of the label.
776 const MCExpr *AT_low_pc = MCSymbolRefExpr::create(Entry.getLabel(),
777 MCSymbolRefExpr::VK_None, context);
778 MCOS->EmitValue(AT_low_pc, AddrSize);
780 // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype.
781 MCOS->EmitIntValue(0, 1);
783 // The DW_TAG_unspecified_parameters DIE abbrev (3).
784 MCOS->EmitULEB128IntValue(3);
786 // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's.
787 MCOS->EmitIntValue(0, 1);
790 // Add the NULL DIE terminating the Compile Unit DIE's.
791 MCOS->EmitIntValue(0, 1);
793 // Now set the value of the symbol at the end of the info section.
794 MCOS->EmitLabel(InfoEnd);
797 // When generating dwarf for assembly source files this emits the data for
798 // .debug_ranges section. We only emit one range list, which spans all of the
799 // executable sections of this file.
800 static void EmitGenDwarfRanges(MCStreamer *MCOS) {
801 MCContext &context = MCOS->getContext();
802 auto &Sections = context.getGenDwarfSectionSyms();
804 const MCAsmInfo *AsmInfo = context.getAsmInfo();
805 int AddrSize = AsmInfo->getPointerSize();
807 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection());
809 for (MCSection *Sec : Sections) {
810 const MCSymbol *StartSymbol = Sec->getBeginSymbol();
811 MCSymbol *EndSymbol = Sec->getEndSymbol(context);
812 assert(StartSymbol && "StartSymbol must not be NULL");
813 assert(EndSymbol && "EndSymbol must not be NULL");
815 // Emit a base address selection entry for the start of this section
816 const MCExpr *SectionStartAddr = MCSymbolRefExpr::create(
817 StartSymbol, MCSymbolRefExpr::VK_None, context);
818 MCOS->EmitFill(AddrSize, 0xFF);
819 MCOS->EmitValue(SectionStartAddr, AddrSize);
821 // Emit a range list entry spanning this section
822 const MCExpr *SectionSize = MakeStartMinusEndExpr(*MCOS,
823 *StartSymbol, *EndSymbol, 0);
824 MCOS->EmitIntValue(0, AddrSize);
825 emitAbsValue(*MCOS, SectionSize, AddrSize);
828 // Emit end of list entry
829 MCOS->EmitIntValue(0, AddrSize);
830 MCOS->EmitIntValue(0, AddrSize);
834 // When generating dwarf for assembly source files this emits the Dwarf
837 void MCGenDwarfInfo::Emit(MCStreamer *MCOS) {
838 MCContext &context = MCOS->getContext();
840 // Create the dwarf sections in this order (.debug_line already created).
841 const MCAsmInfo *AsmInfo = context.getAsmInfo();
842 bool CreateDwarfSectionSymbols =
843 AsmInfo->doesDwarfUseRelocationsAcrossSections();
844 MCSymbol *LineSectionSymbol = nullptr;
845 if (CreateDwarfSectionSymbols)
846 LineSectionSymbol = MCOS->getDwarfLineTableSymbol(0);
847 MCSymbol *AbbrevSectionSymbol = nullptr;
848 MCSymbol *InfoSectionSymbol = nullptr;
849 MCSymbol *RangesSectionSymbol = nullptr;
851 // Create end symbols for each section, and remove empty sections
852 MCOS->getContext().finalizeDwarfSections(*MCOS);
854 // If there are no sections to generate debug info for, we don't need
856 if (MCOS->getContext().getGenDwarfSectionSyms().empty())
859 // We only use the .debug_ranges section if we have multiple code sections,
860 // and we are emitting a DWARF version which supports it.
861 const bool UseRangesSection =
862 MCOS->getContext().getGenDwarfSectionSyms().size() > 1 &&
863 MCOS->getContext().getDwarfVersion() >= 3;
864 CreateDwarfSectionSymbols |= UseRangesSection;
866 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
867 if (CreateDwarfSectionSymbols) {
868 InfoSectionSymbol = context.createTempSymbol();
869 MCOS->EmitLabel(InfoSectionSymbol);
871 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
872 if (CreateDwarfSectionSymbols) {
873 AbbrevSectionSymbol = context.createTempSymbol();
874 MCOS->EmitLabel(AbbrevSectionSymbol);
876 if (UseRangesSection) {
877 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection());
878 if (CreateDwarfSectionSymbols) {
879 RangesSectionSymbol = context.createTempSymbol();
880 MCOS->EmitLabel(RangesSectionSymbol);
884 assert((RangesSectionSymbol != NULL) || !UseRangesSection);
886 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
888 // Output the data for .debug_aranges section.
889 EmitGenDwarfAranges(MCOS, InfoSectionSymbol);
891 if (UseRangesSection)
892 EmitGenDwarfRanges(MCOS);
894 // Output the data for .debug_abbrev section.
895 EmitGenDwarfAbbrev(MCOS);
897 // Output the data for .debug_info section.
898 EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol,
899 RangesSectionSymbol);
903 // When generating dwarf for assembly source files this is called when symbol
904 // for a label is created. If this symbol is not a temporary and is in the
905 // section that dwarf is being generated for, save the needed info to create
908 void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
909 SourceMgr &SrcMgr, SMLoc &Loc) {
910 // We won't create dwarf labels for temporary symbols.
911 if (Symbol->isTemporary())
913 MCContext &context = MCOS->getContext();
914 // We won't create dwarf labels for symbols in sections that we are not
915 // generating debug info for.
916 if (!context.getGenDwarfSectionSyms().count(MCOS->getCurrentSection().first))
919 // The dwarf label's name does not have the symbol name's leading
921 StringRef Name = Symbol->getName();
922 if (Name.startswith("_"))
923 Name = Name.substr(1, Name.size()-1);
925 // Get the dwarf file number to be used for the dwarf label.
926 unsigned FileNumber = context.getGenDwarfFileNumber();
928 // Finding the line number is the expensive part which is why we just don't
929 // pass it in as for some symbols we won't create a dwarf label.
930 unsigned CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
931 unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
933 // We create a temporary symbol for use for the AT_high_pc and AT_low_pc
934 // values so that they don't have things like an ARM thumb bit from the
935 // original symbol. So when used they won't get a low bit set after
937 MCSymbol *Label = context.createTempSymbol();
938 MCOS->EmitLabel(Label);
940 // Create and entry for the info and add it to the other entries.
941 MCOS->getContext().addMCGenDwarfLabelEntry(
942 MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label));
945 static int getDataAlignmentFactor(MCStreamer &streamer) {
946 MCContext &context = streamer.getContext();
947 const MCAsmInfo *asmInfo = context.getAsmInfo();
948 int size = asmInfo->getCalleeSaveStackSlotSize();
949 if (asmInfo->isStackGrowthDirectionUp())
955 static unsigned getSizeForEncoding(MCStreamer &streamer,
956 unsigned symbolEncoding) {
957 MCContext &context = streamer.getContext();
958 unsigned format = symbolEncoding & 0x0f;
960 default: llvm_unreachable("Unknown Encoding");
961 case dwarf::DW_EH_PE_absptr:
962 case dwarf::DW_EH_PE_signed:
963 return context.getAsmInfo()->getPointerSize();
964 case dwarf::DW_EH_PE_udata2:
965 case dwarf::DW_EH_PE_sdata2:
967 case dwarf::DW_EH_PE_udata4:
968 case dwarf::DW_EH_PE_sdata4:
970 case dwarf::DW_EH_PE_udata8:
971 case dwarf::DW_EH_PE_sdata8:
976 static void emitFDESymbol(MCObjectStreamer &streamer, const MCSymbol &symbol,
977 unsigned symbolEncoding, bool isEH) {
978 MCContext &context = streamer.getContext();
979 const MCAsmInfo *asmInfo = context.getAsmInfo();
980 const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol,
983 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
984 if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH)
985 emitAbsValue(streamer, v, size);
987 streamer.EmitValue(v, size);
990 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
991 unsigned symbolEncoding) {
992 MCContext &context = streamer.getContext();
993 const MCAsmInfo *asmInfo = context.getAsmInfo();
994 const MCExpr *v = asmInfo->getExprForPersonalitySymbol(&symbol,
997 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
998 streamer.EmitValue(v, size);
1002 class FrameEmitterImpl {
1004 int InitialCFAOffset = 0;
1006 MCObjectStreamer &Streamer;
1009 FrameEmitterImpl(bool IsEH, MCObjectStreamer &Streamer)
1010 : IsEH(IsEH), Streamer(Streamer) {}
1012 /// Emit the unwind information in a compact way.
1013 void EmitCompactUnwind(const MCDwarfFrameInfo &frame);
1015 const MCSymbol &EmitCIE(const MCSymbol *personality,
1016 unsigned personalityEncoding, const MCSymbol *lsda,
1017 bool IsSignalFrame, unsigned lsdaEncoding,
1019 void EmitFDE(const MCSymbol &cieStart, const MCDwarfFrameInfo &frame,
1020 bool LastInSection, const MCSymbol &SectionStart);
1021 void EmitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs,
1022 MCSymbol *BaseLabel);
1023 void EmitCFIInstruction(const MCCFIInstruction &Instr);
1026 } // end anonymous namespace
1028 static void emitEncodingByte(MCObjectStreamer &Streamer, unsigned Encoding) {
1029 Streamer.EmitIntValue(Encoding, 1);
1032 void FrameEmitterImpl::EmitCFIInstruction(const MCCFIInstruction &Instr) {
1033 int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
1034 auto *MRI = Streamer.getContext().getRegisterInfo();
1036 switch (Instr.getOperation()) {
1037 case MCCFIInstruction::OpRegister: {
1038 unsigned Reg1 = Instr.getRegister();
1039 unsigned Reg2 = Instr.getRegister2();
1041 Reg1 = MRI->getDwarfRegNum(MRI->getLLVMRegNum(Reg1, true), false);
1042 Reg2 = MRI->getDwarfRegNum(MRI->getLLVMRegNum(Reg2, true), false);
1044 Streamer.EmitIntValue(dwarf::DW_CFA_register, 1);
1045 Streamer.EmitULEB128IntValue(Reg1);
1046 Streamer.EmitULEB128IntValue(Reg2);
1049 case MCCFIInstruction::OpWindowSave: {
1050 Streamer.EmitIntValue(dwarf::DW_CFA_GNU_window_save, 1);
1053 case MCCFIInstruction::OpUndefined: {
1054 unsigned Reg = Instr.getRegister();
1055 Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1);
1056 Streamer.EmitULEB128IntValue(Reg);
1059 case MCCFIInstruction::OpAdjustCfaOffset:
1060 case MCCFIInstruction::OpDefCfaOffset: {
1061 const bool IsRelative =
1062 Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset;
1064 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
1067 CFAOffset += Instr.getOffset();
1069 CFAOffset = -Instr.getOffset();
1071 Streamer.EmitULEB128IntValue(CFAOffset);
1075 case MCCFIInstruction::OpDefCfa: {
1076 unsigned Reg = Instr.getRegister();
1078 Reg = MRI->getDwarfRegNum(MRI->getLLVMRegNum(Reg, true), false);
1079 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
1080 Streamer.EmitULEB128IntValue(Reg);
1081 CFAOffset = -Instr.getOffset();
1082 Streamer.EmitULEB128IntValue(CFAOffset);
1087 case MCCFIInstruction::OpDefCfaRegister: {
1088 unsigned Reg = Instr.getRegister();
1090 Reg = MRI->getDwarfRegNum(MRI->getLLVMRegNum(Reg, true), false);
1091 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
1092 Streamer.EmitULEB128IntValue(Reg);
1097 case MCCFIInstruction::OpOffset:
1098 case MCCFIInstruction::OpRelOffset: {
1099 const bool IsRelative =
1100 Instr.getOperation() == MCCFIInstruction::OpRelOffset;
1102 unsigned Reg = Instr.getRegister();
1104 Reg = MRI->getDwarfRegNum(MRI->getLLVMRegNum(Reg, true), false);
1106 int Offset = Instr.getOffset();
1108 Offset -= CFAOffset;
1109 Offset = Offset / dataAlignmentFactor;
1112 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
1113 Streamer.EmitULEB128IntValue(Reg);
1114 Streamer.EmitSLEB128IntValue(Offset);
1115 } else if (Reg < 64) {
1116 Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
1117 Streamer.EmitULEB128IntValue(Offset);
1119 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
1120 Streamer.EmitULEB128IntValue(Reg);
1121 Streamer.EmitULEB128IntValue(Offset);
1125 case MCCFIInstruction::OpRememberState:
1126 Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
1128 case MCCFIInstruction::OpRestoreState:
1129 Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
1131 case MCCFIInstruction::OpSameValue: {
1132 unsigned Reg = Instr.getRegister();
1133 Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
1134 Streamer.EmitULEB128IntValue(Reg);
1137 case MCCFIInstruction::OpRestore: {
1138 unsigned Reg = Instr.getRegister();
1140 Reg = MRI->getDwarfRegNum(MRI->getLLVMRegNum(Reg, true), false);
1141 Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1);
1144 case MCCFIInstruction::OpGnuArgsSize: {
1145 Streamer.EmitIntValue(dwarf::DW_CFA_GNU_args_size, 1);
1146 Streamer.EmitULEB128IntValue(Instr.getOffset());
1149 case MCCFIInstruction::OpEscape:
1150 Streamer.EmitBytes(Instr.getValues());
1153 llvm_unreachable("Unhandled case in switch");
1156 /// Emit frame instructions to describe the layout of the frame.
1157 void FrameEmitterImpl::EmitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs,
1158 MCSymbol *BaseLabel) {
1159 for (unsigned i = 0, N = Instrs.size(); i < N; ++i) {
1160 const MCCFIInstruction &Instr = Instrs[i];
1161 MCSymbol *Label = Instr.getLabel();
1162 // Throw out move if the label is invalid.
1163 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
1165 // Advance row if new location.
1166 if (BaseLabel && Label) {
1167 MCSymbol *ThisSym = Label;
1168 if (ThisSym != BaseLabel) {
1169 Streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
1170 BaseLabel = ThisSym;
1174 EmitCFIInstruction(Instr);
1178 /// Emit the unwind information in a compact way.
1179 void FrameEmitterImpl::EmitCompactUnwind(const MCDwarfFrameInfo &Frame) {
1180 MCContext &Context = Streamer.getContext();
1181 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1183 // range-start range-length compact-unwind-enc personality-func lsda
1184 // _foo LfooEnd-_foo 0x00000023 0 0
1185 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1
1187 // .section __LD,__compact_unwind,regular,debug
1189 // # compact unwind for _foo
1191 // .set L1,LfooEnd-_foo
1197 // # compact unwind for _bar
1199 // .set L2,LbarEnd-_bar
1202 // .quad __gxx_personality
1203 // .quad except_tab1
1205 uint32_t Encoding = Frame.CompactUnwindEncoding;
1206 if (!Encoding) return;
1207 bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly());
1209 // The encoding needs to know we have an LSDA.
1210 if (!DwarfEHFrameOnly && Frame.Lsda)
1211 Encoding |= 0x40000000;
1214 unsigned FDEEncoding = MOFI->getFDEEncoding();
1215 unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
1216 Streamer.EmitSymbolValue(Frame.Begin, Size);
1219 const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin,
1221 emitAbsValue(Streamer, Range, 4);
1224 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
1225 Streamer.EmitIntValue(Encoding, Size);
1227 // Personality Function
1228 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
1229 if (!DwarfEHFrameOnly && Frame.Personality)
1230 Streamer.EmitSymbolValue(Frame.Personality, Size);
1232 Streamer.EmitIntValue(0, Size); // No personality fn
1235 Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
1236 if (!DwarfEHFrameOnly && Frame.Lsda)
1237 Streamer.EmitSymbolValue(Frame.Lsda, Size);
1239 Streamer.EmitIntValue(0, Size); // No LSDA
1242 static unsigned getCIEVersion(bool IsEH, unsigned DwarfVersion) {
1245 switch (DwarfVersion) {
1253 llvm_unreachable("Unknown version");
1256 const MCSymbol &FrameEmitterImpl::EmitCIE(const MCSymbol *personality,
1257 unsigned personalityEncoding,
1258 const MCSymbol *lsda,
1260 unsigned lsdaEncoding,
1262 MCContext &context = Streamer.getContext();
1263 const MCRegisterInfo *MRI = context.getRegisterInfo();
1264 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1266 MCSymbol *sectionStart = context.createTempSymbol();
1267 Streamer.EmitLabel(sectionStart);
1269 MCSymbol *sectionEnd = context.createTempSymbol();
1272 const MCExpr *Length =
1273 MakeStartMinusEndExpr(Streamer, *sectionStart, *sectionEnd, 4);
1274 emitAbsValue(Streamer, Length, 4);
1277 unsigned CIE_ID = IsEH ? 0 : -1;
1278 Streamer.EmitIntValue(CIE_ID, 4);
1281 uint8_t CIEVersion = getCIEVersion(IsEH, context.getDwarfVersion());
1282 Streamer.EmitIntValue(CIEVersion, 1);
1284 // Augmentation String
1285 SmallString<8> Augmentation;
1287 Augmentation += "z";
1289 Augmentation += "P";
1291 Augmentation += "L";
1292 Augmentation += "R";
1294 Augmentation += "S";
1295 Streamer.EmitBytes(Augmentation);
1297 Streamer.EmitIntValue(0, 1);
1299 if (CIEVersion >= 4) {
1301 Streamer.EmitIntValue(context.getAsmInfo()->getPointerSize(), 1);
1303 // Segment Descriptor Size
1304 Streamer.EmitIntValue(0, 1);
1307 // Code Alignment Factor
1308 Streamer.EmitULEB128IntValue(context.getAsmInfo()->getMinInstAlignment());
1310 // Data Alignment Factor
1311 Streamer.EmitSLEB128IntValue(getDataAlignmentFactor(Streamer));
1313 // Return Address Register
1314 if (CIEVersion == 1) {
1315 assert(MRI->getRARegister() <= 255 &&
1316 "DWARF 2 encodes return_address_register in one byte");
1317 Streamer.EmitIntValue(MRI->getDwarfRegNum(MRI->getRARegister(), IsEH), 1);
1319 Streamer.EmitULEB128IntValue(
1320 MRI->getDwarfRegNum(MRI->getRARegister(), IsEH));
1323 // Augmentation Data Length (optional)
1325 unsigned augmentationLength = 0;
1328 // Personality Encoding
1329 augmentationLength += 1;
1331 augmentationLength += getSizeForEncoding(Streamer, personalityEncoding);
1334 augmentationLength += 1;
1335 // Encoding of the FDE pointers
1336 augmentationLength += 1;
1338 Streamer.EmitULEB128IntValue(augmentationLength);
1340 // Augmentation Data (optional)
1342 // Personality Encoding
1343 emitEncodingByte(Streamer, personalityEncoding);
1345 EmitPersonality(Streamer, *personality, personalityEncoding);
1349 emitEncodingByte(Streamer, lsdaEncoding);
1351 // Encoding of the FDE pointers
1352 emitEncodingByte(Streamer, MOFI->getFDEEncoding());
1355 // Initial Instructions
1357 const MCAsmInfo *MAI = context.getAsmInfo();
1359 const std::vector<MCCFIInstruction> &Instructions =
1360 MAI->getInitialFrameState();
1361 EmitCFIInstructions(Instructions, nullptr);
1364 InitialCFAOffset = CFAOffset;
1367 Streamer.EmitValueToAlignment(IsEH ? 4 : MAI->getPointerSize());
1369 Streamer.EmitLabel(sectionEnd);
1370 return *sectionStart;
1373 void FrameEmitterImpl::EmitFDE(const MCSymbol &cieStart,
1374 const MCDwarfFrameInfo &frame,
1376 const MCSymbol &SectionStart) {
1377 MCContext &context = Streamer.getContext();
1378 MCSymbol *fdeStart = context.createTempSymbol();
1379 MCSymbol *fdeEnd = context.createTempSymbol();
1380 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1382 CFAOffset = InitialCFAOffset;
1385 const MCExpr *Length = MakeStartMinusEndExpr(Streamer, *fdeStart, *fdeEnd, 0);
1386 emitAbsValue(Streamer, Length, 4);
1388 Streamer.EmitLabel(fdeStart);
1391 const MCAsmInfo *asmInfo = context.getAsmInfo();
1393 const MCExpr *offset =
1394 MakeStartMinusEndExpr(Streamer, cieStart, *fdeStart, 0);
1395 emitAbsValue(Streamer, offset, 4);
1396 } else if (!asmInfo->doesDwarfUseRelocationsAcrossSections()) {
1397 const MCExpr *offset =
1398 MakeStartMinusEndExpr(Streamer, SectionStart, cieStart, 0);
1399 emitAbsValue(Streamer, offset, 4);
1401 Streamer.EmitSymbolValue(&cieStart, 4);
1405 unsigned PCEncoding =
1406 IsEH ? MOFI->getFDEEncoding() : (unsigned)dwarf::DW_EH_PE_absptr;
1407 unsigned PCSize = getSizeForEncoding(Streamer, PCEncoding);
1408 emitFDESymbol(Streamer, *frame.Begin, PCEncoding, IsEH);
1411 const MCExpr *Range =
1412 MakeStartMinusEndExpr(Streamer, *frame.Begin, *frame.End, 0);
1413 emitAbsValue(Streamer, Range, PCSize);
1416 // Augmentation Data Length
1417 unsigned augmentationLength = 0;
1420 augmentationLength += getSizeForEncoding(Streamer, frame.LsdaEncoding);
1422 Streamer.EmitULEB128IntValue(augmentationLength);
1424 // Augmentation Data
1426 emitFDESymbol(Streamer, *frame.Lsda, frame.LsdaEncoding, true);
1429 // Call Frame Instructions
1430 EmitCFIInstructions(frame.Instructions, frame.Begin);
1433 // The size of a .eh_frame section has to be a multiple of the alignment
1434 // since a null CIE is interpreted as the end. Old systems overaligned
1435 // .eh_frame, so we do too and account for it in the last FDE.
1436 unsigned Align = LastInSection ? asmInfo->getPointerSize() : PCSize;
1437 Streamer.EmitValueToAlignment(Align);
1439 Streamer.EmitLabel(fdeEnd);
1444 static const CIEKey getEmptyKey() {
1445 return CIEKey(nullptr, 0, -1, false, false);
1447 static const CIEKey getTombstoneKey() {
1448 return CIEKey(nullptr, -1, 0, false, false);
1451 CIEKey(const MCSymbol *Personality, unsigned PersonalityEncoding,
1452 unsigned LsdaEncoding, bool IsSignalFrame, bool IsSimple)
1453 : Personality(Personality), PersonalityEncoding(PersonalityEncoding),
1454 LsdaEncoding(LsdaEncoding), IsSignalFrame(IsSignalFrame),
1455 IsSimple(IsSimple) {}
1456 const MCSymbol *Personality;
1457 unsigned PersonalityEncoding;
1458 unsigned LsdaEncoding;
1462 } // anonymous namespace
1465 template <> struct DenseMapInfo<CIEKey> {
1466 static CIEKey getEmptyKey() { return CIEKey::getEmptyKey(); }
1467 static CIEKey getTombstoneKey() { return CIEKey::getTombstoneKey(); }
1468 static unsigned getHashValue(const CIEKey &Key) {
1469 return static_cast<unsigned>(
1470 hash_combine(Key.Personality, Key.PersonalityEncoding, Key.LsdaEncoding,
1471 Key.IsSignalFrame, Key.IsSimple));
1473 static bool isEqual(const CIEKey &LHS, const CIEKey &RHS) {
1474 return LHS.Personality == RHS.Personality &&
1475 LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
1476 LHS.LsdaEncoding == RHS.LsdaEncoding &&
1477 LHS.IsSignalFrame == RHS.IsSignalFrame &&
1478 LHS.IsSimple == RHS.IsSimple;
1483 void MCDwarfFrameEmitter::Emit(MCObjectStreamer &Streamer, MCAsmBackend *MAB,
1485 Streamer.generateCompactUnwindEncodings(MAB);
1487 MCContext &Context = Streamer.getContext();
1488 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1489 FrameEmitterImpl Emitter(IsEH, Streamer);
1490 ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getDwarfFrameInfos();
1492 // Emit the compact unwind info if available.
1493 bool NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame();
1494 if (IsEH && MOFI->getCompactUnwindSection()) {
1495 bool SectionEmitted = false;
1496 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
1497 const MCDwarfFrameInfo &Frame = FrameArray[i];
1498 if (Frame.CompactUnwindEncoding == 0) continue;
1499 if (!SectionEmitted) {
1500 Streamer.SwitchSection(MOFI->getCompactUnwindSection());
1501 Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize());
1502 SectionEmitted = true;
1504 NeedsEHFrameSection |=
1505 Frame.CompactUnwindEncoding ==
1506 MOFI->getCompactUnwindDwarfEHFrameOnly();
1507 Emitter.EmitCompactUnwind(Frame);
1511 if (!NeedsEHFrameSection) return;
1513 MCSection &Section =
1514 IsEH ? *const_cast<MCObjectFileInfo *>(MOFI)->getEHFrameSection()
1515 : *MOFI->getDwarfFrameSection();
1517 Streamer.SwitchSection(&Section);
1518 MCSymbol *SectionStart = Context.createTempSymbol();
1519 Streamer.EmitLabel(SectionStart);
1521 DenseMap<CIEKey, const MCSymbol *> CIEStarts;
1523 const MCSymbol *DummyDebugKey = nullptr;
1524 bool CanOmitDwarf = MOFI->getOmitDwarfIfHaveCompactUnwind();
1525 for (auto I = FrameArray.begin(), E = FrameArray.end(); I != E;) {
1526 const MCDwarfFrameInfo &Frame = *I;
1528 if (CanOmitDwarf && Frame.CompactUnwindEncoding !=
1529 MOFI->getCompactUnwindDwarfEHFrameOnly())
1530 // Don't generate an EH frame if we don't need one. I.e., it's taken care
1531 // of by the compact unwind encoding.
1534 CIEKey Key(Frame.Personality, Frame.PersonalityEncoding,
1535 Frame.LsdaEncoding, Frame.IsSignalFrame, Frame.IsSimple);
1536 const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
1538 CIEStart = &Emitter.EmitCIE(Frame.Personality, Frame.PersonalityEncoding,
1539 Frame.Lsda, Frame.IsSignalFrame,
1540 Frame.LsdaEncoding, Frame.IsSimple);
1542 Emitter.EmitFDE(*CIEStart, Frame, I == E, *SectionStart);
1546 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCObjectStreamer &Streamer,
1547 uint64_t AddrDelta) {
1548 MCContext &Context = Streamer.getContext();
1549 SmallString<256> Tmp;
1550 raw_svector_ostream OS(Tmp);
1551 MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OS);
1552 Streamer.EmitBytes(OS.str());
1555 void MCDwarfFrameEmitter::EncodeAdvanceLoc(MCContext &Context,
1558 // Scale the address delta by the minimum instruction length.
1559 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
1561 if (AddrDelta == 0) {
1562 } else if (isUIntN(6, AddrDelta)) {
1563 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
1565 } else if (isUInt<8>(AddrDelta)) {
1566 OS << uint8_t(dwarf::DW_CFA_advance_loc1);
1567 OS << uint8_t(AddrDelta);
1568 } else if (isUInt<16>(AddrDelta)) {
1569 OS << uint8_t(dwarf::DW_CFA_advance_loc2);
1570 if (Context.getAsmInfo()->isLittleEndian())
1571 support::endian::Writer<support::little>(OS).write<uint16_t>(AddrDelta);
1573 support::endian::Writer<support::big>(OS).write<uint16_t>(AddrDelta);
1575 assert(isUInt<32>(AddrDelta));
1576 OS << uint8_t(dwarf::DW_CFA_advance_loc4);
1577 if (Context.getAsmInfo()->isLittleEndian())
1578 support::endian::Writer<support::little>(OS).write<uint32_t>(AddrDelta);
1580 support::endian::Writer<support::big>(OS).write<uint32_t>(AddrDelta);