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);
260 std::pair<MCSymbol *, MCSymbol *>
261 MCDwarfLineTableHeader::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
262 ArrayRef<char> StandardOpcodeLengths) const {
263 MCContext &context = MCOS->getContext();
265 // Create a symbol at the beginning of the line table.
266 MCSymbol *LineStartSym = Label;
268 LineStartSym = context.createTempSymbol();
269 // Set the value of the symbol, as we are at the start of the line table.
270 MCOS->EmitLabel(LineStartSym);
272 // Create a symbol for the end of the section (to be set when we get there).
273 MCSymbol *LineEndSym = context.createTempSymbol();
275 // The first 4 bytes is the total length of the information for this
276 // compilation unit (not including these 4 bytes for the length).
278 MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym, 4), 4);
280 // Next 2 bytes is the Version, which is Dwarf 2.
281 MCOS->EmitIntValue(2, 2);
283 // Create a symbol for the end of the prologue (to be set when we get there).
284 MCSymbol *ProEndSym = context.createTempSymbol(); // Lprologue_end
286 // Length of the prologue, is the next 4 bytes. Which is the start of the
287 // section to the end of the prologue. Not including the 4 bytes for the
288 // total length, the 2 bytes for the version, and these 4 bytes for the
289 // length of the prologue.
292 MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym, (4 + 2 + 4)), 4);
294 // Parameters of the state machine, are next.
295 MCOS->EmitIntValue(context.getAsmInfo()->getMinInstAlignment(), 1);
296 MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
297 MCOS->EmitIntValue(Params.DWARF2LineBase, 1);
298 MCOS->EmitIntValue(Params.DWARF2LineRange, 1);
299 MCOS->EmitIntValue(StandardOpcodeLengths.size() + 1, 1);
301 // Standard opcode lengths
302 for (char Length : StandardOpcodeLengths)
303 MCOS->EmitIntValue(Length, 1);
305 // Put out the directory and file tables.
307 // First the directory table.
308 for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
309 MCOS->EmitBytes(MCDwarfDirs[i]); // the DirectoryName
310 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
312 MCOS->EmitIntValue(0, 1); // Terminate the directory list
314 // Second the file table.
315 for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
316 assert(!MCDwarfFiles[i].Name.empty());
317 MCOS->EmitBytes(MCDwarfFiles[i].Name); // FileName
318 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
320 MCOS->EmitULEB128IntValue(MCDwarfFiles[i].DirIndex);
321 MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
322 MCOS->EmitIntValue(0, 1); // filesize (always 0)
324 MCOS->EmitIntValue(0, 1); // Terminate the file list
326 // This is the end of the prologue, so set the value of the symbol at the
327 // end of the prologue (that was used in a previous expression).
328 MCOS->EmitLabel(ProEndSym);
330 return std::make_pair(LineStartSym, LineEndSym);
333 void MCDwarfLineTable::EmitCU(MCObjectStreamer *MCOS,
334 MCDwarfLineTableParams Params) const {
335 MCSymbol *LineEndSym = Header.Emit(MCOS, Params).second;
337 // Put out the line tables.
338 for (const auto &LineSec : MCLineSections.getMCLineEntries())
339 EmitDwarfLineTable(MCOS, LineSec.first, LineSec.second);
341 // This is the end of the section, so set the value of the symbol at the end
342 // of this section (that was used in a previous expression).
343 MCOS->EmitLabel(LineEndSym);
346 unsigned MCDwarfLineTable::getFile(StringRef &Directory, StringRef &FileName,
347 unsigned FileNumber) {
348 return Header.getFile(Directory, FileName, FileNumber);
351 unsigned MCDwarfLineTableHeader::getFile(StringRef &Directory,
353 unsigned FileNumber) {
354 if (Directory == CompilationDir)
356 if (FileName.empty()) {
357 FileName = "<stdin>";
360 assert(!FileName.empty());
361 if (FileNumber == 0) {
362 // File numbers start with 1 and/or after any file numbers
363 // allocated by inline-assembler .file directives.
364 FileNumber = MCDwarfFiles.empty() ? 1 : MCDwarfFiles.size();
365 SmallString<256> Buffer;
366 auto IterBool = SourceIdMap.insert(
367 std::make_pair((Directory + Twine('\0') + FileName).toStringRef(Buffer),
369 if (!IterBool.second)
370 return IterBool.first->second;
372 // Make space for this FileNumber in the MCDwarfFiles vector if needed.
373 MCDwarfFiles.resize(FileNumber + 1);
375 // Get the new MCDwarfFile slot for this FileNumber.
376 MCDwarfFile &File = MCDwarfFiles[FileNumber];
378 // It is an error to use see the same number more than once.
379 if (!File.Name.empty())
382 if (Directory.empty()) {
383 // Separate the directory part from the basename of the FileName.
384 StringRef tFileName = sys::path::filename(FileName);
385 if (!tFileName.empty()) {
386 Directory = sys::path::parent_path(FileName);
387 if (!Directory.empty())
388 FileName = tFileName;
392 // Find or make an entry in the MCDwarfDirs vector for this Directory.
393 // Capture directory name.
395 if (Directory.empty()) {
396 // For FileNames with no directories a DirIndex of 0 is used.
400 for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
401 if (Directory == MCDwarfDirs[DirIndex])
404 if (DirIndex >= MCDwarfDirs.size())
405 MCDwarfDirs.push_back(Directory);
406 // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
407 // no directories. MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
408 // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
409 // are stored at MCDwarfFiles[FileNumber].Name .
413 File.Name = FileName;
414 File.DirIndex = DirIndex;
416 // return the allocated FileNumber.
420 /// Utility function to emit the encoding to a streamer.
421 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
422 int64_t LineDelta, uint64_t AddrDelta) {
423 MCContext &Context = MCOS->getContext();
424 SmallString<256> Tmp;
425 raw_svector_ostream OS(Tmp);
426 MCDwarfLineAddr::Encode(Context, Params, LineDelta, AddrDelta, OS);
427 MCOS->EmitBytes(OS.str());
430 /// Given a special op, return the address skip amount (in units of
431 /// DWARF2_LINE_MIN_INSN_LENGTH).
432 static uint64_t SpecialAddr(MCDwarfLineTableParams Params, uint64_t op) {
433 return (op - Params.DWARF2LineOpcodeBase) / Params.DWARF2LineRange;
436 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
437 void MCDwarfLineAddr::Encode(MCContext &Context, MCDwarfLineTableParams Params,
438 int64_t LineDelta, uint64_t AddrDelta,
440 uint64_t Temp, Opcode;
441 bool NeedCopy = false;
443 // The maximum address skip amount that can be encoded with a special op.
444 uint64_t MaxSpecialAddrDelta = SpecialAddr(Params, 255);
446 // Scale the address delta by the minimum instruction length.
447 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
449 // A LineDelta of INT64_MAX is a signal that this is actually a
450 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
451 // end_sequence to emit the matrix entry.
452 if (LineDelta == INT64_MAX) {
453 if (AddrDelta == MaxSpecialAddrDelta)
454 OS << char(dwarf::DW_LNS_const_add_pc);
455 else if (AddrDelta) {
456 OS << char(dwarf::DW_LNS_advance_pc);
457 encodeULEB128(AddrDelta, OS);
459 OS << char(dwarf::DW_LNS_extended_op);
461 OS << char(dwarf::DW_LNE_end_sequence);
465 // Bias the line delta by the base.
466 Temp = LineDelta - Params.DWARF2LineBase;
468 // If the line increment is out of range of a special opcode, we must encode
469 // it with DW_LNS_advance_line.
470 if (Temp >= Params.DWARF2LineRange ||
471 Temp + Params.DWARF2LineOpcodeBase > 255) {
472 OS << char(dwarf::DW_LNS_advance_line);
473 encodeSLEB128(LineDelta, OS);
476 Temp = 0 - Params.DWARF2LineBase;
480 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
481 if (LineDelta == 0 && AddrDelta == 0) {
482 OS << char(dwarf::DW_LNS_copy);
486 // Bias the opcode by the special opcode base.
487 Temp += Params.DWARF2LineOpcodeBase;
489 // Avoid overflow when addr_delta is large.
490 if (AddrDelta < 256 + MaxSpecialAddrDelta) {
491 // Try using a special opcode.
492 Opcode = Temp + AddrDelta * Params.DWARF2LineRange;
498 // Try using DW_LNS_const_add_pc followed by special op.
499 Opcode = Temp + (AddrDelta - MaxSpecialAddrDelta) * Params.DWARF2LineRange;
501 OS << char(dwarf::DW_LNS_const_add_pc);
507 // Otherwise use DW_LNS_advance_pc.
508 OS << char(dwarf::DW_LNS_advance_pc);
509 encodeULEB128(AddrDelta, OS);
512 OS << char(dwarf::DW_LNS_copy);
514 assert(Temp <= 255 && "Buggy special opcode encoding.");
519 // Utility function to write a tuple for .debug_abbrev.
520 static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) {
521 MCOS->EmitULEB128IntValue(Name);
522 MCOS->EmitULEB128IntValue(Form);
525 // When generating dwarf for assembly source files this emits
526 // the data for .debug_abbrev section which contains three DIEs.
527 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
528 MCContext &context = MCOS->getContext();
529 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
531 // DW_TAG_compile_unit DIE abbrev (1).
532 MCOS->EmitULEB128IntValue(1);
533 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit);
534 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
535 EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, context.getDwarfVersion() >= 4
536 ? dwarf::DW_FORM_sec_offset
537 : dwarf::DW_FORM_data4);
538 if (context.getGenDwarfSectionSyms().size() > 1 &&
539 context.getDwarfVersion() >= 3) {
540 EmitAbbrev(MCOS, dwarf::DW_AT_ranges, context.getDwarfVersion() >= 4
541 ? dwarf::DW_FORM_sec_offset
542 : dwarf::DW_FORM_data4);
544 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
545 EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
547 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
548 if (!context.getCompilationDir().empty())
549 EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
550 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
551 if (!DwarfDebugFlags.empty())
552 EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
553 EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string);
554 EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2);
555 EmitAbbrev(MCOS, 0, 0);
557 // DW_TAG_label DIE abbrev (2).
558 MCOS->EmitULEB128IntValue(2);
559 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_label);
560 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
561 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
562 EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);
563 EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);
564 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
565 EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag);
566 EmitAbbrev(MCOS, 0, 0);
568 // DW_TAG_unspecified_parameters DIE abbrev (3).
569 MCOS->EmitULEB128IntValue(3);
570 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters);
571 MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1);
572 EmitAbbrev(MCOS, 0, 0);
574 // Terminate the abbreviations for this compilation unit.
575 MCOS->EmitIntValue(0, 1);
578 // When generating dwarf for assembly source files this emits the data for
579 // .debug_aranges section. This section contains a header and a table of pairs
580 // of PointerSize'ed values for the address and size of section(s) with line
582 static void EmitGenDwarfAranges(MCStreamer *MCOS,
583 const MCSymbol *InfoSectionSymbol) {
584 MCContext &context = MCOS->getContext();
586 auto &Sections = context.getGenDwarfSectionSyms();
588 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
590 // This will be the length of the .debug_aranges section, first account for
591 // the size of each item in the header (see below where we emit these items).
592 int Length = 4 + 2 + 4 + 1 + 1;
594 // Figure the padding after the header before the table of address and size
595 // pairs who's values are PointerSize'ed.
596 const MCAsmInfo *asmInfo = context.getAsmInfo();
597 int AddrSize = asmInfo->getCodePointerSize();
598 int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1));
599 if (Pad == 2 * AddrSize)
603 // Add the size of the pair of PointerSize'ed values for the address and size
604 // of each section we have in the table.
605 Length += 2 * AddrSize * Sections.size();
606 // And the pair of terminating zeros.
607 Length += 2 * AddrSize;
609 // Emit the header for this section.
610 // The 4 byte length not including the 4 byte value for the length.
611 MCOS->EmitIntValue(Length - 4, 4);
612 // The 2 byte version, which is 2.
613 MCOS->EmitIntValue(2, 2);
614 // The 4 byte offset to the compile unit in the .debug_info from the start
615 // of the .debug_info.
616 if (InfoSectionSymbol)
617 MCOS->EmitSymbolValue(InfoSectionSymbol, 4,
618 asmInfo->needsDwarfSectionOffsetDirective());
620 MCOS->EmitIntValue(0, 4);
621 // The 1 byte size of an address.
622 MCOS->EmitIntValue(AddrSize, 1);
623 // The 1 byte size of a segment descriptor, we use a value of zero.
624 MCOS->EmitIntValue(0, 1);
625 // Align the header with the padding if needed, before we put out the table.
626 for(int i = 0; i < Pad; i++)
627 MCOS->EmitIntValue(0, 1);
629 // Now emit the table of pairs of PointerSize'ed values for the section
630 // addresses and sizes.
631 for (MCSection *Sec : Sections) {
632 const MCSymbol *StartSymbol = Sec->getBeginSymbol();
633 MCSymbol *EndSymbol = Sec->getEndSymbol(context);
634 assert(StartSymbol && "StartSymbol must not be NULL");
635 assert(EndSymbol && "EndSymbol must not be NULL");
637 const MCExpr *Addr = MCSymbolRefExpr::create(
638 StartSymbol, MCSymbolRefExpr::VK_None, context);
639 const MCExpr *Size = MakeStartMinusEndExpr(*MCOS,
640 *StartSymbol, *EndSymbol, 0);
641 MCOS->EmitValue(Addr, AddrSize);
642 emitAbsValue(*MCOS, Size, AddrSize);
645 // And finally the pair of terminating zeros.
646 MCOS->EmitIntValue(0, AddrSize);
647 MCOS->EmitIntValue(0, AddrSize);
650 // When generating dwarf for assembly source files this emits the data for
651 // .debug_info section which contains three parts. The header, the compile_unit
652 // DIE and a list of label DIEs.
653 static void EmitGenDwarfInfo(MCStreamer *MCOS,
654 const MCSymbol *AbbrevSectionSymbol,
655 const MCSymbol *LineSectionSymbol,
656 const MCSymbol *RangesSectionSymbol) {
657 MCContext &context = MCOS->getContext();
659 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
661 // Create a symbol at the start and end of this section used in here for the
662 // expression to calculate the length in the header.
663 MCSymbol *InfoStart = context.createTempSymbol();
664 MCOS->EmitLabel(InfoStart);
665 MCSymbol *InfoEnd = context.createTempSymbol();
667 // First part: the header.
669 // The 4 byte total length of the information for this compilation unit, not
670 // including these 4 bytes.
671 const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4);
672 emitAbsValue(*MCOS, Length, 4);
674 // The 2 byte DWARF version.
675 MCOS->EmitIntValue(context.getDwarfVersion(), 2);
677 // The DWARF v5 header has unit type, address size, abbrev offset.
678 // Earlier versions have abbrev offset, address size.
679 const MCAsmInfo &AsmInfo = *context.getAsmInfo();
680 int AddrSize = AsmInfo.getCodePointerSize();
681 if (context.getDwarfVersion() >= 5) {
682 MCOS->EmitIntValue(dwarf::DW_UT_compile, 1);
683 MCOS->EmitIntValue(AddrSize, 1);
685 // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev,
686 // it is at the start of that section so this is zero.
687 if (AbbrevSectionSymbol == nullptr)
688 MCOS->EmitIntValue(0, 4);
690 MCOS->EmitSymbolValue(AbbrevSectionSymbol, 4,
691 AsmInfo.needsDwarfSectionOffsetDirective());
692 if (context.getDwarfVersion() <= 4)
693 MCOS->EmitIntValue(AddrSize, 1);
695 // Second part: the compile_unit DIE.
697 // The DW_TAG_compile_unit DIE abbrev (1).
698 MCOS->EmitULEB128IntValue(1);
700 // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section,
701 // which is at the start of that section so this is zero.
702 if (LineSectionSymbol)
703 MCOS->EmitSymbolValue(LineSectionSymbol, 4,
704 AsmInfo.needsDwarfSectionOffsetDirective());
706 MCOS->EmitIntValue(0, 4);
708 if (RangesSectionSymbol) {
709 // There are multiple sections containing code, so we must use the
710 // .debug_ranges sections.
712 // AT_ranges, the 4 byte offset from the start of the .debug_ranges section
713 // to the address range list for this compilation unit.
714 MCOS->EmitSymbolValue(RangesSectionSymbol, 4);
716 // If we only have one non-empty code section, we can use the simpler
717 // AT_low_pc and AT_high_pc attributes.
719 // Find the first (and only) non-empty text section
720 auto &Sections = context.getGenDwarfSectionSyms();
721 const auto TextSection = Sections.begin();
722 assert(TextSection != Sections.end() && "No text section found");
724 MCSymbol *StartSymbol = (*TextSection)->getBeginSymbol();
725 MCSymbol *EndSymbol = (*TextSection)->getEndSymbol(context);
726 assert(StartSymbol && "StartSymbol must not be NULL");
727 assert(EndSymbol && "EndSymbol must not be NULL");
729 // AT_low_pc, the first address of the default .text section.
730 const MCExpr *Start = MCSymbolRefExpr::create(
731 StartSymbol, MCSymbolRefExpr::VK_None, context);
732 MCOS->EmitValue(Start, AddrSize);
734 // AT_high_pc, the last address of the default .text section.
735 const MCExpr *End = MCSymbolRefExpr::create(
736 EndSymbol, MCSymbolRefExpr::VK_None, context);
737 MCOS->EmitValue(End, AddrSize);
740 // AT_name, the name of the source file. Reconstruct from the first directory
741 // and file table entries.
742 const SmallVectorImpl<std::string> &MCDwarfDirs = context.getMCDwarfDirs();
743 if (MCDwarfDirs.size() > 0) {
744 MCOS->EmitBytes(MCDwarfDirs[0]);
745 MCOS->EmitBytes(sys::path::get_separator());
747 const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles =
748 MCOS->getContext().getMCDwarfFiles();
749 MCOS->EmitBytes(MCDwarfFiles[1].Name);
750 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
752 // AT_comp_dir, the working directory the assembly was done in.
753 if (!context.getCompilationDir().empty()) {
754 MCOS->EmitBytes(context.getCompilationDir());
755 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
758 // AT_APPLE_flags, the command line arguments of the assembler tool.
759 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
760 if (!DwarfDebugFlags.empty()){
761 MCOS->EmitBytes(DwarfDebugFlags);
762 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
765 // AT_producer, the version of the assembler tool.
766 StringRef DwarfDebugProducer = context.getDwarfDebugProducer();
767 if (!DwarfDebugProducer.empty())
768 MCOS->EmitBytes(DwarfDebugProducer);
770 MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM " PACKAGE_VERSION ")"));
771 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
773 // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2
774 // draft has no standard code for assembler.
775 MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2);
777 // Third part: the list of label DIEs.
779 // Loop on saved info for dwarf labels and create the DIEs for them.
780 const std::vector<MCGenDwarfLabelEntry> &Entries =
781 MCOS->getContext().getMCGenDwarfLabelEntries();
782 for (const auto &Entry : Entries) {
783 // The DW_TAG_label DIE abbrev (2).
784 MCOS->EmitULEB128IntValue(2);
786 // AT_name, of the label without any leading underbar.
787 MCOS->EmitBytes(Entry.getName());
788 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
790 // AT_decl_file, index into the file table.
791 MCOS->EmitIntValue(Entry.getFileNumber(), 4);
793 // AT_decl_line, source line number.
794 MCOS->EmitIntValue(Entry.getLineNumber(), 4);
796 // AT_low_pc, start address of the label.
797 const MCExpr *AT_low_pc = MCSymbolRefExpr::create(Entry.getLabel(),
798 MCSymbolRefExpr::VK_None, context);
799 MCOS->EmitValue(AT_low_pc, AddrSize);
801 // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype.
802 MCOS->EmitIntValue(0, 1);
804 // The DW_TAG_unspecified_parameters DIE abbrev (3).
805 MCOS->EmitULEB128IntValue(3);
807 // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's.
808 MCOS->EmitIntValue(0, 1);
811 // Add the NULL DIE terminating the Compile Unit DIE's.
812 MCOS->EmitIntValue(0, 1);
814 // Now set the value of the symbol at the end of the info section.
815 MCOS->EmitLabel(InfoEnd);
818 // When generating dwarf for assembly source files this emits the data for
819 // .debug_ranges section. We only emit one range list, which spans all of the
820 // executable sections of this file.
821 static void EmitGenDwarfRanges(MCStreamer *MCOS) {
822 MCContext &context = MCOS->getContext();
823 auto &Sections = context.getGenDwarfSectionSyms();
825 const MCAsmInfo *AsmInfo = context.getAsmInfo();
826 int AddrSize = AsmInfo->getCodePointerSize();
828 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection());
830 for (MCSection *Sec : Sections) {
831 const MCSymbol *StartSymbol = Sec->getBeginSymbol();
832 MCSymbol *EndSymbol = Sec->getEndSymbol(context);
833 assert(StartSymbol && "StartSymbol must not be NULL");
834 assert(EndSymbol && "EndSymbol must not be NULL");
836 // Emit a base address selection entry for the start of this section
837 const MCExpr *SectionStartAddr = MCSymbolRefExpr::create(
838 StartSymbol, MCSymbolRefExpr::VK_None, context);
839 MCOS->emitFill(AddrSize, 0xFF);
840 MCOS->EmitValue(SectionStartAddr, AddrSize);
842 // Emit a range list entry spanning this section
843 const MCExpr *SectionSize = MakeStartMinusEndExpr(*MCOS,
844 *StartSymbol, *EndSymbol, 0);
845 MCOS->EmitIntValue(0, AddrSize);
846 emitAbsValue(*MCOS, SectionSize, AddrSize);
849 // Emit end of list entry
850 MCOS->EmitIntValue(0, AddrSize);
851 MCOS->EmitIntValue(0, AddrSize);
855 // When generating dwarf for assembly source files this emits the Dwarf
858 void MCGenDwarfInfo::Emit(MCStreamer *MCOS) {
859 MCContext &context = MCOS->getContext();
861 // Create the dwarf sections in this order (.debug_line already created).
862 const MCAsmInfo *AsmInfo = context.getAsmInfo();
863 bool CreateDwarfSectionSymbols =
864 AsmInfo->doesDwarfUseRelocationsAcrossSections();
865 MCSymbol *LineSectionSymbol = nullptr;
866 if (CreateDwarfSectionSymbols)
867 LineSectionSymbol = MCOS->getDwarfLineTableSymbol(0);
868 MCSymbol *AbbrevSectionSymbol = nullptr;
869 MCSymbol *InfoSectionSymbol = nullptr;
870 MCSymbol *RangesSectionSymbol = nullptr;
872 // Create end symbols for each section, and remove empty sections
873 MCOS->getContext().finalizeDwarfSections(*MCOS);
875 // If there are no sections to generate debug info for, we don't need
877 if (MCOS->getContext().getGenDwarfSectionSyms().empty())
880 // We only use the .debug_ranges section if we have multiple code sections,
881 // and we are emitting a DWARF version which supports it.
882 const bool UseRangesSection =
883 MCOS->getContext().getGenDwarfSectionSyms().size() > 1 &&
884 MCOS->getContext().getDwarfVersion() >= 3;
885 CreateDwarfSectionSymbols |= UseRangesSection;
887 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
888 if (CreateDwarfSectionSymbols) {
889 InfoSectionSymbol = context.createTempSymbol();
890 MCOS->EmitLabel(InfoSectionSymbol);
892 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
893 if (CreateDwarfSectionSymbols) {
894 AbbrevSectionSymbol = context.createTempSymbol();
895 MCOS->EmitLabel(AbbrevSectionSymbol);
897 if (UseRangesSection) {
898 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection());
899 if (CreateDwarfSectionSymbols) {
900 RangesSectionSymbol = context.createTempSymbol();
901 MCOS->EmitLabel(RangesSectionSymbol);
905 assert((RangesSectionSymbol != nullptr) || !UseRangesSection);
907 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
909 // Output the data for .debug_aranges section.
910 EmitGenDwarfAranges(MCOS, InfoSectionSymbol);
912 if (UseRangesSection)
913 EmitGenDwarfRanges(MCOS);
915 // Output the data for .debug_abbrev section.
916 EmitGenDwarfAbbrev(MCOS);
918 // Output the data for .debug_info section.
919 EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol,
920 RangesSectionSymbol);
924 // When generating dwarf for assembly source files this is called when symbol
925 // for a label is created. If this symbol is not a temporary and is in the
926 // section that dwarf is being generated for, save the needed info to create
929 void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
930 SourceMgr &SrcMgr, SMLoc &Loc) {
931 // We won't create dwarf labels for temporary symbols.
932 if (Symbol->isTemporary())
934 MCContext &context = MCOS->getContext();
935 // We won't create dwarf labels for symbols in sections that we are not
936 // generating debug info for.
937 if (!context.getGenDwarfSectionSyms().count(MCOS->getCurrentSectionOnly()))
940 // The dwarf label's name does not have the symbol name's leading
942 StringRef Name = Symbol->getName();
943 if (Name.startswith("_"))
944 Name = Name.substr(1, Name.size()-1);
946 // Get the dwarf file number to be used for the dwarf label.
947 unsigned FileNumber = context.getGenDwarfFileNumber();
949 // Finding the line number is the expensive part which is why we just don't
950 // pass it in as for some symbols we won't create a dwarf label.
951 unsigned CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
952 unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
954 // We create a temporary symbol for use for the AT_high_pc and AT_low_pc
955 // values so that they don't have things like an ARM thumb bit from the
956 // original symbol. So when used they won't get a low bit set after
958 MCSymbol *Label = context.createTempSymbol();
959 MCOS->EmitLabel(Label);
961 // Create and entry for the info and add it to the other entries.
962 MCOS->getContext().addMCGenDwarfLabelEntry(
963 MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label));
966 static int getDataAlignmentFactor(MCStreamer &streamer) {
967 MCContext &context = streamer.getContext();
968 const MCAsmInfo *asmInfo = context.getAsmInfo();
969 int size = asmInfo->getCalleeSaveStackSlotSize();
970 if (asmInfo->isStackGrowthDirectionUp())
976 static unsigned getSizeForEncoding(MCStreamer &streamer,
977 unsigned symbolEncoding) {
978 MCContext &context = streamer.getContext();
979 unsigned format = symbolEncoding & 0x0f;
981 default: llvm_unreachable("Unknown Encoding");
982 case dwarf::DW_EH_PE_absptr:
983 case dwarf::DW_EH_PE_signed:
984 return context.getAsmInfo()->getCodePointerSize();
985 case dwarf::DW_EH_PE_udata2:
986 case dwarf::DW_EH_PE_sdata2:
988 case dwarf::DW_EH_PE_udata4:
989 case dwarf::DW_EH_PE_sdata4:
991 case dwarf::DW_EH_PE_udata8:
992 case dwarf::DW_EH_PE_sdata8:
997 static void emitFDESymbol(MCObjectStreamer &streamer, const MCSymbol &symbol,
998 unsigned symbolEncoding, bool isEH) {
999 MCContext &context = streamer.getContext();
1000 const MCAsmInfo *asmInfo = context.getAsmInfo();
1001 const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol,
1004 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
1005 if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH)
1006 emitAbsValue(streamer, v, size);
1008 streamer.EmitValue(v, size);
1011 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
1012 unsigned symbolEncoding) {
1013 MCContext &context = streamer.getContext();
1014 const MCAsmInfo *asmInfo = context.getAsmInfo();
1015 const MCExpr *v = asmInfo->getExprForPersonalitySymbol(&symbol,
1018 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
1019 streamer.EmitValue(v, size);
1024 class FrameEmitterImpl {
1026 int InitialCFAOffset = 0;
1028 MCObjectStreamer &Streamer;
1031 FrameEmitterImpl(bool IsEH, MCObjectStreamer &Streamer)
1032 : IsEH(IsEH), Streamer(Streamer) {}
1034 /// Emit the unwind information in a compact way.
1035 void EmitCompactUnwind(const MCDwarfFrameInfo &frame);
1037 const MCSymbol &EmitCIE(const MCSymbol *personality,
1038 unsigned personalityEncoding, const MCSymbol *lsda,
1039 bool IsSignalFrame, unsigned lsdaEncoding,
1041 void EmitFDE(const MCSymbol &cieStart, const MCDwarfFrameInfo &frame,
1042 bool LastInSection, const MCSymbol &SectionStart);
1043 void EmitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs,
1044 MCSymbol *BaseLabel);
1045 void EmitCFIInstruction(const MCCFIInstruction &Instr);
1048 } // end anonymous namespace
1050 static void emitEncodingByte(MCObjectStreamer &Streamer, unsigned Encoding) {
1051 Streamer.EmitIntValue(Encoding, 1);
1054 void FrameEmitterImpl::EmitCFIInstruction(const MCCFIInstruction &Instr) {
1055 int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
1056 auto *MRI = Streamer.getContext().getRegisterInfo();
1058 switch (Instr.getOperation()) {
1059 case MCCFIInstruction::OpRegister: {
1060 unsigned Reg1 = Instr.getRegister();
1061 unsigned Reg2 = Instr.getRegister2();
1063 Reg1 = MRI->getDwarfRegNum(MRI->getLLVMRegNum(Reg1, true), false);
1064 Reg2 = MRI->getDwarfRegNum(MRI->getLLVMRegNum(Reg2, true), false);
1066 Streamer.EmitIntValue(dwarf::DW_CFA_register, 1);
1067 Streamer.EmitULEB128IntValue(Reg1);
1068 Streamer.EmitULEB128IntValue(Reg2);
1071 case MCCFIInstruction::OpWindowSave:
1072 Streamer.EmitIntValue(dwarf::DW_CFA_GNU_window_save, 1);
1075 case MCCFIInstruction::OpUndefined: {
1076 unsigned Reg = Instr.getRegister();
1077 Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1);
1078 Streamer.EmitULEB128IntValue(Reg);
1081 case MCCFIInstruction::OpAdjustCfaOffset:
1082 case MCCFIInstruction::OpDefCfaOffset: {
1083 const bool IsRelative =
1084 Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset;
1086 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
1089 CFAOffset += Instr.getOffset();
1091 CFAOffset = -Instr.getOffset();
1093 Streamer.EmitULEB128IntValue(CFAOffset);
1097 case MCCFIInstruction::OpDefCfa: {
1098 unsigned Reg = Instr.getRegister();
1100 Reg = MRI->getDwarfRegNum(MRI->getLLVMRegNum(Reg, true), false);
1101 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
1102 Streamer.EmitULEB128IntValue(Reg);
1103 CFAOffset = -Instr.getOffset();
1104 Streamer.EmitULEB128IntValue(CFAOffset);
1108 case MCCFIInstruction::OpDefCfaRegister: {
1109 unsigned Reg = Instr.getRegister();
1111 Reg = MRI->getDwarfRegNum(MRI->getLLVMRegNum(Reg, true), false);
1112 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
1113 Streamer.EmitULEB128IntValue(Reg);
1117 case MCCFIInstruction::OpOffset:
1118 case MCCFIInstruction::OpRelOffset: {
1119 const bool IsRelative =
1120 Instr.getOperation() == MCCFIInstruction::OpRelOffset;
1122 unsigned Reg = Instr.getRegister();
1124 Reg = MRI->getDwarfRegNum(MRI->getLLVMRegNum(Reg, true), false);
1126 int Offset = Instr.getOffset();
1128 Offset -= CFAOffset;
1129 Offset = Offset / dataAlignmentFactor;
1132 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
1133 Streamer.EmitULEB128IntValue(Reg);
1134 Streamer.EmitSLEB128IntValue(Offset);
1135 } else if (Reg < 64) {
1136 Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
1137 Streamer.EmitULEB128IntValue(Offset);
1139 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
1140 Streamer.EmitULEB128IntValue(Reg);
1141 Streamer.EmitULEB128IntValue(Offset);
1145 case MCCFIInstruction::OpRememberState:
1146 Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
1148 case MCCFIInstruction::OpRestoreState:
1149 Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
1151 case MCCFIInstruction::OpSameValue: {
1152 unsigned Reg = Instr.getRegister();
1153 Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
1154 Streamer.EmitULEB128IntValue(Reg);
1157 case MCCFIInstruction::OpRestore: {
1158 unsigned Reg = Instr.getRegister();
1160 Reg = MRI->getDwarfRegNum(MRI->getLLVMRegNum(Reg, true), false);
1161 Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1);
1164 case MCCFIInstruction::OpGnuArgsSize:
1165 Streamer.EmitIntValue(dwarf::DW_CFA_GNU_args_size, 1);
1166 Streamer.EmitULEB128IntValue(Instr.getOffset());
1169 case MCCFIInstruction::OpEscape:
1170 Streamer.EmitBytes(Instr.getValues());
1173 llvm_unreachable("Unhandled case in switch");
1176 /// Emit frame instructions to describe the layout of the frame.
1177 void FrameEmitterImpl::EmitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs,
1178 MCSymbol *BaseLabel) {
1179 for (const MCCFIInstruction &Instr : Instrs) {
1180 MCSymbol *Label = Instr.getLabel();
1181 // Throw out move if the label is invalid.
1182 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
1184 // Advance row if new location.
1185 if (BaseLabel && Label) {
1186 MCSymbol *ThisSym = Label;
1187 if (ThisSym != BaseLabel) {
1188 Streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
1189 BaseLabel = ThisSym;
1193 EmitCFIInstruction(Instr);
1197 /// Emit the unwind information in a compact way.
1198 void FrameEmitterImpl::EmitCompactUnwind(const MCDwarfFrameInfo &Frame) {
1199 MCContext &Context = Streamer.getContext();
1200 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1202 // range-start range-length compact-unwind-enc personality-func lsda
1203 // _foo LfooEnd-_foo 0x00000023 0 0
1204 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1
1206 // .section __LD,__compact_unwind,regular,debug
1208 // # compact unwind for _foo
1210 // .set L1,LfooEnd-_foo
1216 // # compact unwind for _bar
1218 // .set L2,LbarEnd-_bar
1221 // .quad __gxx_personality
1222 // .quad except_tab1
1224 uint32_t Encoding = Frame.CompactUnwindEncoding;
1225 if (!Encoding) return;
1226 bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly());
1228 // The encoding needs to know we have an LSDA.
1229 if (!DwarfEHFrameOnly && Frame.Lsda)
1230 Encoding |= 0x40000000;
1233 unsigned FDEEncoding = MOFI->getFDEEncoding();
1234 unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
1235 Streamer.EmitSymbolValue(Frame.Begin, Size);
1238 const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin,
1240 emitAbsValue(Streamer, Range, 4);
1243 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
1244 Streamer.EmitIntValue(Encoding, Size);
1246 // Personality Function
1247 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
1248 if (!DwarfEHFrameOnly && Frame.Personality)
1249 Streamer.EmitSymbolValue(Frame.Personality, Size);
1251 Streamer.EmitIntValue(0, Size); // No personality fn
1254 Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
1255 if (!DwarfEHFrameOnly && Frame.Lsda)
1256 Streamer.EmitSymbolValue(Frame.Lsda, Size);
1258 Streamer.EmitIntValue(0, Size); // No LSDA
1261 static unsigned getCIEVersion(bool IsEH, unsigned DwarfVersion) {
1264 switch (DwarfVersion) {
1273 llvm_unreachable("Unknown version");
1276 const MCSymbol &FrameEmitterImpl::EmitCIE(const MCSymbol *personality,
1277 unsigned personalityEncoding,
1278 const MCSymbol *lsda,
1280 unsigned lsdaEncoding,
1282 MCContext &context = Streamer.getContext();
1283 const MCRegisterInfo *MRI = context.getRegisterInfo();
1284 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1286 MCSymbol *sectionStart = context.createTempSymbol();
1287 Streamer.EmitLabel(sectionStart);
1289 MCSymbol *sectionEnd = context.createTempSymbol();
1292 const MCExpr *Length =
1293 MakeStartMinusEndExpr(Streamer, *sectionStart, *sectionEnd, 4);
1294 emitAbsValue(Streamer, Length, 4);
1297 unsigned CIE_ID = IsEH ? 0 : -1;
1298 Streamer.EmitIntValue(CIE_ID, 4);
1301 uint8_t CIEVersion = getCIEVersion(IsEH, context.getDwarfVersion());
1302 Streamer.EmitIntValue(CIEVersion, 1);
1304 // Augmentation String
1305 SmallString<8> Augmentation;
1307 Augmentation += "z";
1309 Augmentation += "P";
1311 Augmentation += "L";
1312 Augmentation += "R";
1314 Augmentation += "S";
1315 Streamer.EmitBytes(Augmentation);
1317 Streamer.EmitIntValue(0, 1);
1319 if (CIEVersion >= 4) {
1321 Streamer.EmitIntValue(context.getAsmInfo()->getCodePointerSize(), 1);
1323 // Segment Descriptor Size
1324 Streamer.EmitIntValue(0, 1);
1327 // Code Alignment Factor
1328 Streamer.EmitULEB128IntValue(context.getAsmInfo()->getMinInstAlignment());
1330 // Data Alignment Factor
1331 Streamer.EmitSLEB128IntValue(getDataAlignmentFactor(Streamer));
1333 // Return Address Register
1334 if (CIEVersion == 1) {
1335 assert(MRI->getRARegister() <= 255 &&
1336 "DWARF 2 encodes return_address_register in one byte");
1337 Streamer.EmitIntValue(MRI->getDwarfRegNum(MRI->getRARegister(), IsEH), 1);
1339 Streamer.EmitULEB128IntValue(
1340 MRI->getDwarfRegNum(MRI->getRARegister(), IsEH));
1343 // Augmentation Data Length (optional)
1345 unsigned augmentationLength = 0;
1348 // Personality Encoding
1349 augmentationLength += 1;
1351 augmentationLength += getSizeForEncoding(Streamer, personalityEncoding);
1354 augmentationLength += 1;
1355 // Encoding of the FDE pointers
1356 augmentationLength += 1;
1358 Streamer.EmitULEB128IntValue(augmentationLength);
1360 // Augmentation Data (optional)
1362 // Personality Encoding
1363 emitEncodingByte(Streamer, personalityEncoding);
1365 EmitPersonality(Streamer, *personality, personalityEncoding);
1369 emitEncodingByte(Streamer, lsdaEncoding);
1371 // Encoding of the FDE pointers
1372 emitEncodingByte(Streamer, MOFI->getFDEEncoding());
1375 // Initial Instructions
1377 const MCAsmInfo *MAI = context.getAsmInfo();
1379 const std::vector<MCCFIInstruction> &Instructions =
1380 MAI->getInitialFrameState();
1381 EmitCFIInstructions(Instructions, nullptr);
1384 InitialCFAOffset = CFAOffset;
1387 Streamer.EmitValueToAlignment(IsEH ? 4 : MAI->getCodePointerSize());
1389 Streamer.EmitLabel(sectionEnd);
1390 return *sectionStart;
1393 void FrameEmitterImpl::EmitFDE(const MCSymbol &cieStart,
1394 const MCDwarfFrameInfo &frame,
1396 const MCSymbol &SectionStart) {
1397 MCContext &context = Streamer.getContext();
1398 MCSymbol *fdeStart = context.createTempSymbol();
1399 MCSymbol *fdeEnd = context.createTempSymbol();
1400 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1402 CFAOffset = InitialCFAOffset;
1405 const MCExpr *Length = MakeStartMinusEndExpr(Streamer, *fdeStart, *fdeEnd, 0);
1406 emitAbsValue(Streamer, Length, 4);
1408 Streamer.EmitLabel(fdeStart);
1411 const MCAsmInfo *asmInfo = context.getAsmInfo();
1413 const MCExpr *offset =
1414 MakeStartMinusEndExpr(Streamer, cieStart, *fdeStart, 0);
1415 emitAbsValue(Streamer, offset, 4);
1416 } else if (!asmInfo->doesDwarfUseRelocationsAcrossSections()) {
1417 const MCExpr *offset =
1418 MakeStartMinusEndExpr(Streamer, SectionStart, cieStart, 0);
1419 emitAbsValue(Streamer, offset, 4);
1421 Streamer.EmitSymbolValue(&cieStart, 4);
1425 unsigned PCEncoding =
1426 IsEH ? MOFI->getFDEEncoding() : (unsigned)dwarf::DW_EH_PE_absptr;
1427 unsigned PCSize = getSizeForEncoding(Streamer, PCEncoding);
1428 emitFDESymbol(Streamer, *frame.Begin, PCEncoding, IsEH);
1431 const MCExpr *Range =
1432 MakeStartMinusEndExpr(Streamer, *frame.Begin, *frame.End, 0);
1433 emitAbsValue(Streamer, Range, PCSize);
1436 // Augmentation Data Length
1437 unsigned augmentationLength = 0;
1440 augmentationLength += getSizeForEncoding(Streamer, frame.LsdaEncoding);
1442 Streamer.EmitULEB128IntValue(augmentationLength);
1444 // Augmentation Data
1446 emitFDESymbol(Streamer, *frame.Lsda, frame.LsdaEncoding, true);
1449 // Call Frame Instructions
1450 EmitCFIInstructions(frame.Instructions, frame.Begin);
1453 // The size of a .eh_frame section has to be a multiple of the alignment
1454 // since a null CIE is interpreted as the end. Old systems overaligned
1455 // .eh_frame, so we do too and account for it in the last FDE.
1456 unsigned Align = LastInSection ? asmInfo->getCodePointerSize() : PCSize;
1457 Streamer.EmitValueToAlignment(Align);
1459 Streamer.EmitLabel(fdeEnd);
1465 static const CIEKey getEmptyKey() {
1466 return CIEKey(nullptr, 0, -1, false, false);
1469 static const CIEKey getTombstoneKey() {
1470 return CIEKey(nullptr, -1, 0, false, false);
1473 CIEKey(const MCSymbol *Personality, unsigned PersonalityEncoding,
1474 unsigned LsdaEncoding, bool IsSignalFrame, bool IsSimple)
1475 : Personality(Personality), PersonalityEncoding(PersonalityEncoding),
1476 LsdaEncoding(LsdaEncoding), IsSignalFrame(IsSignalFrame),
1477 IsSimple(IsSimple) {}
1479 const MCSymbol *Personality;
1480 unsigned PersonalityEncoding;
1481 unsigned LsdaEncoding;
1486 } // end anonymous namespace
1490 template <> struct DenseMapInfo<CIEKey> {
1491 static CIEKey getEmptyKey() { return CIEKey::getEmptyKey(); }
1492 static CIEKey getTombstoneKey() { return CIEKey::getTombstoneKey(); }
1494 static unsigned getHashValue(const CIEKey &Key) {
1495 return static_cast<unsigned>(
1496 hash_combine(Key.Personality, Key.PersonalityEncoding, Key.LsdaEncoding,
1497 Key.IsSignalFrame, Key.IsSimple));
1500 static bool isEqual(const CIEKey &LHS, const CIEKey &RHS) {
1501 return LHS.Personality == RHS.Personality &&
1502 LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
1503 LHS.LsdaEncoding == RHS.LsdaEncoding &&
1504 LHS.IsSignalFrame == RHS.IsSignalFrame &&
1505 LHS.IsSimple == RHS.IsSimple;
1509 } // end namespace llvm
1511 void MCDwarfFrameEmitter::Emit(MCObjectStreamer &Streamer, MCAsmBackend *MAB,
1513 Streamer.generateCompactUnwindEncodings(MAB);
1515 MCContext &Context = Streamer.getContext();
1516 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1517 const MCAsmInfo *AsmInfo = Context.getAsmInfo();
1518 FrameEmitterImpl Emitter(IsEH, Streamer);
1519 ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getDwarfFrameInfos();
1521 // Emit the compact unwind info if available.
1522 bool NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame();
1523 if (IsEH && MOFI->getCompactUnwindSection()) {
1524 bool SectionEmitted = false;
1525 for (const MCDwarfFrameInfo &Frame : FrameArray) {
1526 if (Frame.CompactUnwindEncoding == 0) continue;
1527 if (!SectionEmitted) {
1528 Streamer.SwitchSection(MOFI->getCompactUnwindSection());
1529 Streamer.EmitValueToAlignment(AsmInfo->getCodePointerSize());
1530 SectionEmitted = true;
1532 NeedsEHFrameSection |=
1533 Frame.CompactUnwindEncoding ==
1534 MOFI->getCompactUnwindDwarfEHFrameOnly();
1535 Emitter.EmitCompactUnwind(Frame);
1539 if (!NeedsEHFrameSection) return;
1541 MCSection &Section =
1542 IsEH ? *const_cast<MCObjectFileInfo *>(MOFI)->getEHFrameSection()
1543 : *MOFI->getDwarfFrameSection();
1545 Streamer.SwitchSection(&Section);
1546 MCSymbol *SectionStart = Context.createTempSymbol();
1547 Streamer.EmitLabel(SectionStart);
1549 DenseMap<CIEKey, const MCSymbol *> CIEStarts;
1551 const MCSymbol *DummyDebugKey = nullptr;
1552 bool CanOmitDwarf = MOFI->getOmitDwarfIfHaveCompactUnwind();
1553 for (auto I = FrameArray.begin(), E = FrameArray.end(); I != E;) {
1554 const MCDwarfFrameInfo &Frame = *I;
1556 if (CanOmitDwarf && Frame.CompactUnwindEncoding !=
1557 MOFI->getCompactUnwindDwarfEHFrameOnly())
1558 // Don't generate an EH frame if we don't need one. I.e., it's taken care
1559 // of by the compact unwind encoding.
1562 CIEKey Key(Frame.Personality, Frame.PersonalityEncoding,
1563 Frame.LsdaEncoding, Frame.IsSignalFrame, Frame.IsSimple);
1564 const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
1566 CIEStart = &Emitter.EmitCIE(Frame.Personality, Frame.PersonalityEncoding,
1567 Frame.Lsda, Frame.IsSignalFrame,
1568 Frame.LsdaEncoding, Frame.IsSimple);
1570 Emitter.EmitFDE(*CIEStart, Frame, I == E, *SectionStart);
1574 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCObjectStreamer &Streamer,
1575 uint64_t AddrDelta) {
1576 MCContext &Context = Streamer.getContext();
1577 SmallString<256> Tmp;
1578 raw_svector_ostream OS(Tmp);
1579 MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OS);
1580 Streamer.EmitBytes(OS.str());
1583 void MCDwarfFrameEmitter::EncodeAdvanceLoc(MCContext &Context,
1586 // Scale the address delta by the minimum instruction length.
1587 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
1589 if (AddrDelta == 0) {
1590 } else if (isUIntN(6, AddrDelta)) {
1591 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
1593 } else if (isUInt<8>(AddrDelta)) {
1594 OS << uint8_t(dwarf::DW_CFA_advance_loc1);
1595 OS << uint8_t(AddrDelta);
1596 } else if (isUInt<16>(AddrDelta)) {
1597 OS << uint8_t(dwarf::DW_CFA_advance_loc2);
1598 if (Context.getAsmInfo()->isLittleEndian())
1599 support::endian::Writer<support::little>(OS).write<uint16_t>(AddrDelta);
1601 support::endian::Writer<support::big>(OS).write<uint16_t>(AddrDelta);
1603 assert(isUInt<32>(AddrDelta));
1604 OS << uint8_t(dwarf::DW_CFA_advance_loc4);
1605 if (Context.getAsmInfo()->isLittleEndian())
1606 support::endian::Writer<support::little>(OS).write<uint32_t>(AddrDelta);
1608 support::endian::Writer<support::big>(OS).write<uint32_t>(AddrDelta);