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"
32 // Given a special op, return the address skip amount (in units of
33 // DWARF2_LINE_MIN_INSN_LENGTH.
34 #define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE)
36 // The maximum address skip amount that can be encoded with a special op.
37 #define MAX_SPECIAL_ADDR_DELTA SPECIAL_ADDR(255)
39 // First special line opcode - leave room for the standard opcodes.
40 // Note: If you want to change this, you'll have to update the
41 // "standard_opcode_lengths" table that is emitted in DwarfFileTable::Emit().
42 #define DWARF2_LINE_OPCODE_BASE 13
44 // Minimum line offset in a special line info. opcode. This value
45 // was chosen to give a reasonable range of values.
46 #define DWARF2_LINE_BASE -5
48 // Range of line offsets in a special line info. opcode.
49 #define DWARF2_LINE_RANGE 14
51 static inline uint64_t ScaleAddrDelta(MCContext &Context, uint64_t AddrDelta) {
52 unsigned MinInsnLength = Context.getAsmInfo()->getMinInstAlignment();
53 if (MinInsnLength == 1)
55 if (AddrDelta % MinInsnLength != 0) {
56 // TODO: report this error, but really only once.
59 return AddrDelta / MinInsnLength;
63 // This is called when an instruction is assembled into the specified section
64 // and if there is information from the last .loc directive that has yet to have
65 // a line entry made for it is made.
67 void MCLineEntry::Make(MCObjectStreamer *MCOS, const MCSection *Section) {
68 if (!MCOS->getContext().getDwarfLocSeen())
71 // Create a symbol at in the current section for use in the line entry.
72 MCSymbol *LineSym = MCOS->getContext().CreateTempSymbol();
73 // Set the value of the symbol to use for the MCLineEntry.
74 MCOS->EmitLabel(LineSym);
76 // Get the current .loc info saved in the context.
77 const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();
79 // Create a (local) line entry with the symbol and the current .loc info.
80 MCLineEntry LineEntry(LineSym, DwarfLoc);
82 // clear DwarfLocSeen saying the current .loc info is now used.
83 MCOS->getContext().ClearDwarfLocSeen();
85 // Add the line entry to this section's entries.
87 .getMCDwarfLineTable(MCOS->getContext().getDwarfCompileUnitID())
89 .addLineEntry(LineEntry, Section);
93 // This helper routine returns an expression of End - Start + IntVal .
95 static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS,
96 const MCSymbol &Start,
99 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
101 MCSymbolRefExpr::Create(&End, Variant, MCOS.getContext());
103 MCSymbolRefExpr::Create(&Start, Variant, MCOS.getContext());
105 MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext());
107 MCConstantExpr::Create(IntVal, MCOS.getContext());
109 MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext());
114 // This emits the Dwarf line table for the specified section from the entries
115 // in the LineSection.
118 EmitDwarfLineTable(MCObjectStreamer *MCOS, const MCSection *Section,
119 const MCLineSection::MCLineEntryCollection &LineEntries) {
120 unsigned FileNum = 1;
121 unsigned LastLine = 1;
123 unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
125 unsigned Discriminator = 0;
126 MCSymbol *LastLabel = nullptr;
128 // Loop through each MCLineEntry and encode the dwarf line number table.
129 for (auto it = LineEntries.begin(),
130 ie = LineEntries.end();
133 if (FileNum != it->getFileNum()) {
134 FileNum = it->getFileNum();
135 MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
136 MCOS->EmitULEB128IntValue(FileNum);
138 if (Column != it->getColumn()) {
139 Column = it->getColumn();
140 MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
141 MCOS->EmitULEB128IntValue(Column);
143 if (Discriminator != it->getDiscriminator()) {
144 Discriminator = it->getDiscriminator();
145 unsigned Size = getULEB128Size(Discriminator);
146 MCOS->EmitIntValue(dwarf::DW_LNS_extended_op, 1);
147 MCOS->EmitULEB128IntValue(Size + 1);
148 MCOS->EmitIntValue(dwarf::DW_LNE_set_discriminator, 1);
149 MCOS->EmitULEB128IntValue(Discriminator);
151 if (Isa != it->getIsa()) {
153 MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
154 MCOS->EmitULEB128IntValue(Isa);
156 if ((it->getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
157 Flags = it->getFlags();
158 MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
160 if (it->getFlags() & DWARF2_FLAG_BASIC_BLOCK)
161 MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
162 if (it->getFlags() & DWARF2_FLAG_PROLOGUE_END)
163 MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
164 if (it->getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
165 MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
167 int64_t LineDelta = static_cast<int64_t>(it->getLine()) - LastLine;
168 MCSymbol *Label = it->getLabel();
170 // At this point we want to emit/create the sequence to encode the delta in
171 // line numbers and the increment of the address from the previous Label
172 // and the current Label.
173 const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo();
174 MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label,
175 asmInfo->getPointerSize());
177 LastLine = it->getLine();
181 // Emit a DW_LNE_end_sequence for the end of the section.
182 // Using the pointer Section create a temporary label at the end of the
183 // section and use that and the LastLabel to compute the address delta
184 // and use INT64_MAX as the line delta which is the signal that this is
185 // actually a DW_LNE_end_sequence.
187 // Switch to the section to be able to create a symbol at its end.
188 // TODO: keep track of the last subsection so that this symbol appears in the
190 MCOS->SwitchSection(Section);
192 MCContext &context = MCOS->getContext();
193 // Create a symbol at the end of the section.
194 MCSymbol *SectionEnd = context.CreateTempSymbol();
195 // Set the value of the symbol, as we are at the end of the section.
196 MCOS->EmitLabel(SectionEnd);
198 // Switch back the dwarf line section.
199 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
201 const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo();
202 MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd,
203 asmInfo->getPointerSize());
207 // This emits the Dwarf file and the line tables.
209 void MCDwarfLineTable::Emit(MCObjectStreamer *MCOS) {
210 MCContext &context = MCOS->getContext();
212 auto &LineTables = context.getMCDwarfLineTables();
214 // Bail out early so we don't switch to the debug_line section needlessly and
215 // in doing so create an unnecessary (if empty) section.
216 if (LineTables.empty())
219 // Switch to the section where the table will be emitted into.
220 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
222 // Handle the rest of the Compile Units.
223 for (const auto &CUIDTablePair : LineTables)
224 CUIDTablePair.second.EmitCU(MCOS);
227 void MCDwarfDwoLineTable::Emit(MCStreamer &MCOS) const {
228 MCOS.EmitLabel(Header.Emit(&MCOS, None).second);
231 std::pair<MCSymbol *, MCSymbol *> MCDwarfLineTableHeader::Emit(MCStreamer *MCOS) const {
232 static const char StandardOpcodeLengths[] = {
233 0, // length of DW_LNS_copy
234 1, // length of DW_LNS_advance_pc
235 1, // length of DW_LNS_advance_line
236 1, // length of DW_LNS_set_file
237 1, // length of DW_LNS_set_column
238 0, // length of DW_LNS_negate_stmt
239 0, // length of DW_LNS_set_basic_block
240 0, // length of DW_LNS_const_add_pc
241 1, // length of DW_LNS_fixed_advance_pc
242 0, // length of DW_LNS_set_prologue_end
243 0, // length of DW_LNS_set_epilogue_begin
246 assert(array_lengthof(StandardOpcodeLengths) == (DWARF2_LINE_OPCODE_BASE - 1));
247 return Emit(MCOS, StandardOpcodeLengths);
250 std::pair<MCSymbol *, MCSymbol *>
251 MCDwarfLineTableHeader::Emit(MCStreamer *MCOS,
252 ArrayRef<char> StandardOpcodeLengths) const {
254 MCContext &context = MCOS->getContext();
256 // Create a symbol at the beginning of the line table.
257 MCSymbol *LineStartSym = Label;
259 LineStartSym = context.CreateTempSymbol();
260 // Set the value of the symbol, as we are at the start of the line table.
261 MCOS->EmitLabel(LineStartSym);
263 // Create a symbol for the end of the section (to be set when we get there).
264 MCSymbol *LineEndSym = context.CreateTempSymbol();
266 // The first 4 bytes is the total length of the information for this
267 // compilation unit (not including these 4 bytes for the length).
268 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym,4),
271 // Next 2 bytes is the Version, which is Dwarf 2.
272 MCOS->EmitIntValue(2, 2);
274 // Create a symbol for the end of the prologue (to be set when we get there).
275 MCSymbol *ProEndSym = context.CreateTempSymbol(); // Lprologue_end
277 // Length of the prologue, is the next 4 bytes. Which is the start of the
278 // section to the end of the prologue. Not including the 4 bytes for the
279 // total length, the 2 bytes for the version, and these 4 bytes for the
280 // length of the prologue.
281 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym,
284 // Parameters of the state machine, are next.
285 MCOS->EmitIntValue(context.getAsmInfo()->getMinInstAlignment(), 1);
286 MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
287 MCOS->EmitIntValue(DWARF2_LINE_BASE, 1);
288 MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1);
289 MCOS->EmitIntValue(StandardOpcodeLengths.size() + 1, 1);
291 // Standard opcode lengths
292 for (char Length : StandardOpcodeLengths)
293 MCOS->EmitIntValue(Length, 1);
295 // Put out the directory and file tables.
297 // First the directory table.
298 for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
299 MCOS->EmitBytes(MCDwarfDirs[i]); // the DirectoryName
300 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
302 MCOS->EmitIntValue(0, 1); // Terminate the directory list
304 // Second the file table.
305 for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
306 assert(!MCDwarfFiles[i].Name.empty());
307 MCOS->EmitBytes(MCDwarfFiles[i].Name); // FileName
308 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
310 MCOS->EmitULEB128IntValue(MCDwarfFiles[i].DirIndex);
311 MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
312 MCOS->EmitIntValue(0, 1); // filesize (always 0)
314 MCOS->EmitIntValue(0, 1); // Terminate the file list
316 // This is the end of the prologue, so set the value of the symbol at the
317 // end of the prologue (that was used in a previous expression).
318 MCOS->EmitLabel(ProEndSym);
320 return std::make_pair(LineStartSym, LineEndSym);
323 void MCDwarfLineTable::EmitCU(MCObjectStreamer *MCOS) const {
324 MCSymbol *LineEndSym = Header.Emit(MCOS).second;
326 // Put out the line tables.
327 for (const auto &LineSec : MCLineSections.getMCLineEntries())
328 EmitDwarfLineTable(MCOS, LineSec.first, LineSec.second);
330 if (MCOS->getContext().getAsmInfo()->getLinkerRequiresNonEmptyDwarfLines() &&
331 MCLineSections.getMCLineEntries().empty()) {
332 // The darwin9 linker has a bug (see PR8715). For for 32-bit architectures
334 // total_length >= prologue_length + 10
335 // We are 4 bytes short, since we have total_length = 51 and
336 // prologue_length = 45
338 // The regular end_sequence should be sufficient.
339 MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
342 // This is the end of the section, so set the value of the symbol at the end
343 // of this section (that was used in a previous expression).
344 MCOS->EmitLabel(LineEndSym);
347 unsigned MCDwarfLineTable::getFile(StringRef &Directory, StringRef &FileName,
348 unsigned FileNumber) {
349 return Header.getFile(Directory, FileName, FileNumber);
352 unsigned MCDwarfLineTableHeader::getFile(StringRef &Directory,
354 unsigned FileNumber) {
355 if (Directory == CompilationDir)
357 if (FileName.empty()) {
358 FileName = "<stdin>";
361 assert(!FileName.empty());
362 if (FileNumber == 0) {
363 FileNumber = SourceIdMap.size() + 1;
364 assert((MCDwarfFiles.empty() || FileNumber == MCDwarfFiles.size()) &&
365 "Don't mix autonumbered and explicit numbered line table usage");
366 StringMapEntry<unsigned> &Ent = SourceIdMap.GetOrCreateValue(
367 (Directory + Twine('\0') + FileName).str(), FileNumber);
368 if (Ent.getValue() != FileNumber)
369 return Ent.getValue();
371 // Make space for this FileNumber in the MCDwarfFiles vector if needed.
372 MCDwarfFiles.resize(FileNumber + 1);
374 // Get the new MCDwarfFile slot for this FileNumber.
375 MCDwarfFile &File = MCDwarfFiles[FileNumber];
377 // It is an error to use see the same number more than once.
378 if (!File.Name.empty())
381 if (Directory.empty()) {
382 // Separate the directory part from the basename of the FileName.
383 StringRef tFileName = sys::path::filename(FileName);
384 if (!tFileName.empty()) {
385 Directory = sys::path::parent_path(FileName);
386 if (!Directory.empty())
387 FileName = tFileName;
391 // Find or make an entry in the MCDwarfDirs vector for this Directory.
392 // Capture directory name.
394 if (Directory.empty()) {
395 // For FileNames with no directories a DirIndex of 0 is used.
399 for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
400 if (Directory == MCDwarfDirs[DirIndex])
403 if (DirIndex >= MCDwarfDirs.size())
404 MCDwarfDirs.push_back(Directory);
405 // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
406 // no directories. MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
407 // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
408 // are stored at MCDwarfFiles[FileNumber].Name .
412 File.Name = FileName;
413 File.DirIndex = DirIndex;
415 // return the allocated FileNumber.
419 /// Utility function to emit the encoding to a streamer.
420 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta,
421 uint64_t AddrDelta) {
422 MCContext &Context = MCOS->getContext();
423 SmallString<256> Tmp;
424 raw_svector_ostream OS(Tmp);
425 MCDwarfLineAddr::Encode(Context, LineDelta, AddrDelta, OS);
426 MCOS->EmitBytes(OS.str());
429 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
430 void MCDwarfLineAddr::Encode(MCContext &Context, int64_t LineDelta,
431 uint64_t AddrDelta, raw_ostream &OS) {
432 uint64_t Temp, Opcode;
433 bool NeedCopy = false;
435 // Scale the address delta by the minimum instruction length.
436 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
438 // A LineDelta of INT64_MAX is a signal that this is actually a
439 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
440 // end_sequence to emit the matrix entry.
441 if (LineDelta == INT64_MAX) {
442 if (AddrDelta == MAX_SPECIAL_ADDR_DELTA)
443 OS << char(dwarf::DW_LNS_const_add_pc);
445 OS << char(dwarf::DW_LNS_advance_pc);
446 encodeULEB128(AddrDelta, OS);
448 OS << char(dwarf::DW_LNS_extended_op);
450 OS << char(dwarf::DW_LNE_end_sequence);
454 // Bias the line delta by the base.
455 Temp = LineDelta - DWARF2_LINE_BASE;
457 // If the line increment is out of range of a special opcode, we must encode
458 // it with DW_LNS_advance_line.
459 if (Temp >= DWARF2_LINE_RANGE) {
460 OS << char(dwarf::DW_LNS_advance_line);
461 encodeSLEB128(LineDelta, OS);
464 Temp = 0 - DWARF2_LINE_BASE;
468 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
469 if (LineDelta == 0 && AddrDelta == 0) {
470 OS << char(dwarf::DW_LNS_copy);
474 // Bias the opcode by the special opcode base.
475 Temp += DWARF2_LINE_OPCODE_BASE;
477 // Avoid overflow when addr_delta is large.
478 if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) {
479 // Try using a special opcode.
480 Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE;
486 // Try using DW_LNS_const_add_pc followed by special op.
487 Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
489 OS << char(dwarf::DW_LNS_const_add_pc);
495 // Otherwise use DW_LNS_advance_pc.
496 OS << char(dwarf::DW_LNS_advance_pc);
497 encodeULEB128(AddrDelta, OS);
500 OS << char(dwarf::DW_LNS_copy);
505 // Utility function to write a tuple for .debug_abbrev.
506 static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) {
507 MCOS->EmitULEB128IntValue(Name);
508 MCOS->EmitULEB128IntValue(Form);
511 // When generating dwarf for assembly source files this emits
512 // the data for .debug_abbrev section which contains three DIEs.
513 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
514 MCContext &context = MCOS->getContext();
515 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
517 // DW_TAG_compile_unit DIE abbrev (1).
518 MCOS->EmitULEB128IntValue(1);
519 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit);
520 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
521 EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4);
522 if (MCOS->getContext().getGenDwarfSectionSyms().size() > 1) {
523 EmitAbbrev(MCOS, dwarf::DW_AT_ranges, dwarf::DW_FORM_data4);
525 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
526 EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
528 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
529 if (!context.getCompilationDir().empty())
530 EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
531 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
532 if (!DwarfDebugFlags.empty())
533 EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
534 EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string);
535 EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2);
536 EmitAbbrev(MCOS, 0, 0);
538 // DW_TAG_label DIE abbrev (2).
539 MCOS->EmitULEB128IntValue(2);
540 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_label);
541 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
542 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
543 EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);
544 EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);
545 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
546 EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag);
547 EmitAbbrev(MCOS, 0, 0);
549 // DW_TAG_unspecified_parameters DIE abbrev (3).
550 MCOS->EmitULEB128IntValue(3);
551 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters);
552 MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1);
553 EmitAbbrev(MCOS, 0, 0);
555 // Terminate the abbreviations for this compilation unit.
556 MCOS->EmitIntValue(0, 1);
559 // When generating dwarf for assembly source files this emits the data for
560 // .debug_aranges section. This section contains a header and a table of pairs
561 // of PointerSize'ed values for the address and size of section(s) with line
563 static void EmitGenDwarfAranges(MCStreamer *MCOS,
564 const MCSymbol *InfoSectionSymbol) {
565 MCContext &context = MCOS->getContext();
567 auto &Sections = context.getGenDwarfSectionSyms();
569 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
571 // This will be the length of the .debug_aranges section, first account for
572 // the size of each item in the header (see below where we emit these items).
573 int Length = 4 + 2 + 4 + 1 + 1;
575 // Figure the padding after the header before the table of address and size
576 // pairs who's values are PointerSize'ed.
577 const MCAsmInfo *asmInfo = context.getAsmInfo();
578 int AddrSize = asmInfo->getPointerSize();
579 int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1));
580 if (Pad == 2 * AddrSize)
584 // Add the size of the pair of PointerSize'ed values for the address and size
585 // of each section we have in the table.
586 Length += 2 * AddrSize * Sections.size();
587 // And the pair of terminating zeros.
588 Length += 2 * AddrSize;
591 // Emit the header for this section.
592 // The 4 byte length not including the 4 byte value for the length.
593 MCOS->EmitIntValue(Length - 4, 4);
594 // The 2 byte version, which is 2.
595 MCOS->EmitIntValue(2, 2);
596 // The 4 byte offset to the compile unit in the .debug_info from the start
597 // of the .debug_info.
598 if (InfoSectionSymbol)
599 MCOS->EmitSymbolValue(InfoSectionSymbol, 4);
601 MCOS->EmitIntValue(0, 4);
602 // The 1 byte size of an address.
603 MCOS->EmitIntValue(AddrSize, 1);
604 // The 1 byte size of a segment descriptor, we use a value of zero.
605 MCOS->EmitIntValue(0, 1);
606 // Align the header with the padding if needed, before we put out the table.
607 for(int i = 0; i < Pad; i++)
608 MCOS->EmitIntValue(0, 1);
610 // Now emit the table of pairs of PointerSize'ed values for the section
611 // addresses and sizes.
612 for (const auto &sec : Sections) {
613 MCSymbol *StartSymbol = sec.second.first;
614 MCSymbol *EndSymbol = sec.second.second;
615 assert(StartSymbol && "StartSymbol must not be NULL");
616 assert(EndSymbol && "EndSymbol must not be NULL");
618 const MCExpr *Addr = MCSymbolRefExpr::Create(
619 StartSymbol, MCSymbolRefExpr::VK_None, context);
620 const MCExpr *Size = MakeStartMinusEndExpr(*MCOS,
621 *StartSymbol, *EndSymbol, 0);
622 MCOS->EmitValue(Addr, AddrSize);
623 MCOS->EmitAbsValue(Size, AddrSize);
626 // And finally the pair of terminating zeros.
627 MCOS->EmitIntValue(0, AddrSize);
628 MCOS->EmitIntValue(0, AddrSize);
631 // When generating dwarf for assembly source files this emits the data for
632 // .debug_info section which contains three parts. The header, the compile_unit
633 // DIE and a list of label DIEs.
634 static void EmitGenDwarfInfo(MCStreamer *MCOS,
635 const MCSymbol *AbbrevSectionSymbol,
636 const MCSymbol *LineSectionSymbol,
637 const MCSymbol *RangesSectionSymbol) {
638 MCContext &context = MCOS->getContext();
640 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
642 // Create a symbol at the start and end of this section used in here for the
643 // expression to calculate the length in the header.
644 MCSymbol *InfoStart = context.CreateTempSymbol();
645 MCOS->EmitLabel(InfoStart);
646 MCSymbol *InfoEnd = context.CreateTempSymbol();
648 // First part: the header.
650 // The 4 byte total length of the information for this compilation unit, not
651 // including these 4 bytes.
652 const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4);
653 MCOS->EmitAbsValue(Length, 4);
655 // The 2 byte DWARF version.
656 MCOS->EmitIntValue(context.getDwarfVersion(), 2);
658 // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev,
659 // it is at the start of that section so this is zero.
660 if (AbbrevSectionSymbol) {
661 MCOS->EmitSymbolValue(AbbrevSectionSymbol, 4);
663 MCOS->EmitIntValue(0, 4);
666 const MCAsmInfo *asmInfo = context.getAsmInfo();
667 int AddrSize = asmInfo->getPointerSize();
668 // The 1 byte size of an address.
669 MCOS->EmitIntValue(AddrSize, 1);
671 // Second part: the compile_unit DIE.
673 // The DW_TAG_compile_unit DIE abbrev (1).
674 MCOS->EmitULEB128IntValue(1);
676 // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section,
677 // which is at the start of that section so this is zero.
678 if (LineSectionSymbol) {
679 MCOS->EmitSymbolValue(LineSectionSymbol, 4);
681 MCOS->EmitIntValue(0, 4);
684 if (RangesSectionSymbol) {
685 // There are multiple sections containing code, so we must use the
686 // .debug_ranges sections.
688 // AT_ranges, the 4 byte offset from the start of the .debug_ranges section
689 // to the address range list for this compilation unit.
690 MCOS->EmitSymbolValue(RangesSectionSymbol, 4);
692 // If we only have one non-empty code section, we can use the simpler
693 // AT_low_pc and AT_high_pc attributes.
695 // Find the first (and only) non-empty text section
696 auto &Sections = context.getGenDwarfSectionSyms();
697 const auto TextSection = Sections.begin();
698 assert(TextSection != Sections.end() && "No text section found");
700 MCSymbol *StartSymbol = TextSection->second.first;
701 MCSymbol *EndSymbol = TextSection->second.second;
702 assert(StartSymbol && "StartSymbol must not be NULL");
703 assert(EndSymbol && "EndSymbol must not be NULL");
705 // AT_low_pc, the first address of the default .text section.
706 const MCExpr *Start = MCSymbolRefExpr::Create(
707 StartSymbol, MCSymbolRefExpr::VK_None, context);
708 MCOS->EmitValue(Start, AddrSize);
710 // AT_high_pc, the last address of the default .text section.
711 const MCExpr *End = MCSymbolRefExpr::Create(
712 EndSymbol, MCSymbolRefExpr::VK_None, context);
713 MCOS->EmitValue(End, AddrSize);
716 // AT_name, the name of the source file. Reconstruct from the first directory
717 // and file table entries.
718 const SmallVectorImpl<std::string> &MCDwarfDirs = context.getMCDwarfDirs();
719 if (MCDwarfDirs.size() > 0) {
720 MCOS->EmitBytes(MCDwarfDirs[0]);
721 MCOS->EmitBytes(sys::path::get_separator());
723 const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles =
724 MCOS->getContext().getMCDwarfFiles();
725 MCOS->EmitBytes(MCDwarfFiles[1].Name);
726 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
728 // AT_comp_dir, the working directory the assembly was done in.
729 if (!context.getCompilationDir().empty()) {
730 MCOS->EmitBytes(context.getCompilationDir());
731 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
734 // AT_APPLE_flags, the command line arguments of the assembler tool.
735 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
736 if (!DwarfDebugFlags.empty()){
737 MCOS->EmitBytes(DwarfDebugFlags);
738 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
741 // AT_producer, the version of the assembler tool.
742 StringRef DwarfDebugProducer = context.getDwarfDebugProducer();
743 if (!DwarfDebugProducer.empty())
744 MCOS->EmitBytes(DwarfDebugProducer);
746 MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM " PACKAGE_VERSION ")"));
747 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
749 // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2
750 // draft has no standard code for assembler.
751 MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2);
753 // Third part: the list of label DIEs.
755 // Loop on saved info for dwarf labels and create the DIEs for them.
756 const std::vector<MCGenDwarfLabelEntry> &Entries =
757 MCOS->getContext().getMCGenDwarfLabelEntries();
758 for (const auto &Entry : Entries) {
759 // The DW_TAG_label DIE abbrev (2).
760 MCOS->EmitULEB128IntValue(2);
762 // AT_name, of the label without any leading underbar.
763 MCOS->EmitBytes(Entry.getName());
764 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
766 // AT_decl_file, index into the file table.
767 MCOS->EmitIntValue(Entry.getFileNumber(), 4);
769 // AT_decl_line, source line number.
770 MCOS->EmitIntValue(Entry.getLineNumber(), 4);
772 // AT_low_pc, start address of the label.
773 const MCExpr *AT_low_pc = MCSymbolRefExpr::Create(Entry.getLabel(),
774 MCSymbolRefExpr::VK_None, context);
775 MCOS->EmitValue(AT_low_pc, AddrSize);
777 // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype.
778 MCOS->EmitIntValue(0, 1);
780 // The DW_TAG_unspecified_parameters DIE abbrev (3).
781 MCOS->EmitULEB128IntValue(3);
783 // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's.
784 MCOS->EmitIntValue(0, 1);
787 // Add the NULL DIE terminating the Compile Unit DIE's.
788 MCOS->EmitIntValue(0, 1);
790 // Now set the value of the symbol at the end of the info section.
791 MCOS->EmitLabel(InfoEnd);
794 // When generating dwarf for assembly source files this emits the data for
795 // .debug_ranges section. We only emit one range list, which spans all of the
796 // executable sections of this file.
797 static void EmitGenDwarfRanges(MCStreamer *MCOS) {
798 MCContext &context = MCOS->getContext();
799 auto &Sections = context.getGenDwarfSectionSyms();
801 const MCAsmInfo *AsmInfo = context.getAsmInfo();
802 int AddrSize = AsmInfo->getPointerSize();
804 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection());
806 for (const auto sec : Sections) {
808 MCSymbol *StartSymbol = sec.second.first;
809 MCSymbol *EndSymbol = sec.second.second;
810 assert(StartSymbol && "StartSymbol must not be NULL");
811 assert(EndSymbol && "EndSymbol must not be NULL");
813 // Emit a base address selection entry for the start of this section
814 const MCExpr *SectionStartAddr = MCSymbolRefExpr::Create(
815 StartSymbol, MCSymbolRefExpr::VK_None, context);
816 MCOS->EmitFill(AddrSize, 0xFF);
817 MCOS->EmitValue(SectionStartAddr, AddrSize);
819 // Emit a range list entry spanning this section
820 const MCExpr *SectionSize = MakeStartMinusEndExpr(*MCOS,
821 *StartSymbol, *EndSymbol, 0);
822 MCOS->EmitIntValue(0, AddrSize);
823 MCOS->EmitAbsValue(SectionSize, AddrSize);
826 // Emit end of list entry
827 MCOS->EmitIntValue(0, AddrSize);
828 MCOS->EmitIntValue(0, AddrSize);
832 // When generating dwarf for assembly source files this emits the Dwarf
835 void MCGenDwarfInfo::Emit(MCStreamer *MCOS) {
836 MCContext &context = MCOS->getContext();
838 // Create the dwarf sections in this order (.debug_line already created).
839 const MCAsmInfo *AsmInfo = context.getAsmInfo();
840 bool CreateDwarfSectionSymbols =
841 AsmInfo->doesDwarfUseRelocationsAcrossSections();
842 MCSymbol *LineSectionSymbol = nullptr;
843 if (CreateDwarfSectionSymbols)
844 LineSectionSymbol = MCOS->getDwarfLineTableSymbol(0);
845 MCSymbol *AbbrevSectionSymbol = nullptr;
846 MCSymbol *InfoSectionSymbol = nullptr;
847 MCSymbol *RangesSectionSymbol = NULL;
849 // Create end symbols for each section, and remove empty sections
850 MCOS->getContext().finalizeDwarfSections(*MCOS);
852 // If there are no sections to generate debug info for, we don't need
854 if (MCOS->getContext().getGenDwarfSectionSyms().empty())
857 // We only need to use the .debug_ranges section if we have multiple
859 const bool UseRangesSection =
860 MCOS->getContext().getGenDwarfSectionSyms().size() > 1;
861 CreateDwarfSectionSymbols |= UseRangesSection;
863 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
864 if (CreateDwarfSectionSymbols) {
865 InfoSectionSymbol = context.CreateTempSymbol();
866 MCOS->EmitLabel(InfoSectionSymbol);
868 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
869 if (CreateDwarfSectionSymbols) {
870 AbbrevSectionSymbol = context.CreateTempSymbol();
871 MCOS->EmitLabel(AbbrevSectionSymbol);
873 if (UseRangesSection) {
874 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection());
875 if (CreateDwarfSectionSymbols) {
876 RangesSectionSymbol = context.CreateTempSymbol();
877 MCOS->EmitLabel(RangesSectionSymbol);
881 assert((RangesSectionSymbol != NULL) || !UseRangesSection);
883 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
885 // Output the data for .debug_aranges section.
886 EmitGenDwarfAranges(MCOS, InfoSectionSymbol);
888 if (UseRangesSection)
889 EmitGenDwarfRanges(MCOS);
891 // Output the data for .debug_abbrev section.
892 EmitGenDwarfAbbrev(MCOS);
894 // Output the data for .debug_info section.
895 EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol,
896 RangesSectionSymbol);
900 // When generating dwarf for assembly source files this is called when symbol
901 // for a label is created. If this symbol is not a temporary and is in the
902 // section that dwarf is being generated for, save the needed info to create
905 void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
906 SourceMgr &SrcMgr, SMLoc &Loc) {
907 // We won't create dwarf labels for temporary symbols.
908 if (Symbol->isTemporary())
910 MCContext &context = MCOS->getContext();
911 // We won't create dwarf labels for symbols in sections that we are not
912 // generating debug info for.
913 if (!context.getGenDwarfSectionSyms().count(MCOS->getCurrentSection().first))
916 // The dwarf label's name does not have the symbol name's leading
918 StringRef Name = Symbol->getName();
919 if (Name.startswith("_"))
920 Name = Name.substr(1, Name.size()-1);
922 // Get the dwarf file number to be used for the dwarf label.
923 unsigned FileNumber = context.getGenDwarfFileNumber();
925 // Finding the line number is the expensive part which is why we just don't
926 // pass it in as for some symbols we won't create a dwarf label.
927 unsigned CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
928 unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
930 // We create a temporary symbol for use for the AT_high_pc and AT_low_pc
931 // values so that they don't have things like an ARM thumb bit from the
932 // original symbol. So when used they won't get a low bit set after
934 MCSymbol *Label = context.CreateTempSymbol();
935 MCOS->EmitLabel(Label);
937 // Create and entry for the info and add it to the other entries.
938 MCOS->getContext().addMCGenDwarfLabelEntry(
939 MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label));
942 static int getDataAlignmentFactor(MCStreamer &streamer) {
943 MCContext &context = streamer.getContext();
944 const MCAsmInfo *asmInfo = context.getAsmInfo();
945 int size = asmInfo->getCalleeSaveStackSlotSize();
946 if (asmInfo->isStackGrowthDirectionUp())
952 static unsigned getSizeForEncoding(MCStreamer &streamer,
953 unsigned symbolEncoding) {
954 MCContext &context = streamer.getContext();
955 unsigned format = symbolEncoding & 0x0f;
957 default: llvm_unreachable("Unknown Encoding");
958 case dwarf::DW_EH_PE_absptr:
959 case dwarf::DW_EH_PE_signed:
960 return context.getAsmInfo()->getPointerSize();
961 case dwarf::DW_EH_PE_udata2:
962 case dwarf::DW_EH_PE_sdata2:
964 case dwarf::DW_EH_PE_udata4:
965 case dwarf::DW_EH_PE_sdata4:
967 case dwarf::DW_EH_PE_udata8:
968 case dwarf::DW_EH_PE_sdata8:
973 static void EmitFDESymbol(MCStreamer &streamer, const MCSymbol &symbol,
974 unsigned symbolEncoding, bool isEH,
975 const char *comment = nullptr) {
976 MCContext &context = streamer.getContext();
977 const MCAsmInfo *asmInfo = context.getAsmInfo();
978 const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol,
981 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
982 if (streamer.isVerboseAsm() && comment) streamer.AddComment(comment);
983 if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH)
984 streamer.EmitAbsValue(v, size);
986 streamer.EmitValue(v, size);
989 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
990 unsigned symbolEncoding) {
991 MCContext &context = streamer.getContext();
992 const MCAsmInfo *asmInfo = context.getAsmInfo();
993 const MCExpr *v = asmInfo->getExprForPersonalitySymbol(&symbol,
996 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
997 streamer.EmitValue(v, size);
1001 class FrameEmitterImpl {
1005 const MCSymbol *SectionStart;
1007 FrameEmitterImpl(bool isEH)
1008 : CFAOffset(0), CIENum(0), IsEH(isEH), SectionStart(nullptr) {}
1010 void setSectionStart(const MCSymbol *Label) { SectionStart = Label; }
1012 /// EmitCompactUnwind - Emit the unwind information in a compact way.
1013 void EmitCompactUnwind(MCStreamer &streamer,
1014 const MCDwarfFrameInfo &frame);
1016 const MCSymbol &EmitCIE(MCObjectStreamer &streamer,
1017 const MCSymbol *personality,
1018 unsigned personalityEncoding,
1019 const MCSymbol *lsda,
1021 unsigned lsdaEncoding,
1023 MCSymbol *EmitFDE(MCObjectStreamer &streamer,
1024 const MCSymbol &cieStart,
1025 const MCDwarfFrameInfo &frame);
1026 void EmitCFIInstructions(MCObjectStreamer &streamer,
1027 ArrayRef<MCCFIInstruction> Instrs,
1028 MCSymbol *BaseLabel);
1029 void EmitCFIInstruction(MCObjectStreamer &Streamer,
1030 const MCCFIInstruction &Instr);
1033 } // end anonymous namespace
1035 static void EmitEncodingByte(MCStreamer &Streamer, unsigned Encoding,
1037 if (Streamer.isVerboseAsm()) {
1040 default: EncStr = "<unknown encoding>"; break;
1041 case dwarf::DW_EH_PE_absptr: EncStr = "absptr"; break;
1042 case dwarf::DW_EH_PE_omit: EncStr = "omit"; break;
1043 case dwarf::DW_EH_PE_pcrel: EncStr = "pcrel"; break;
1044 case dwarf::DW_EH_PE_udata4: EncStr = "udata4"; break;
1045 case dwarf::DW_EH_PE_udata8: EncStr = "udata8"; break;
1046 case dwarf::DW_EH_PE_sdata4: EncStr = "sdata4"; break;
1047 case dwarf::DW_EH_PE_sdata8: EncStr = "sdata8"; break;
1048 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
1049 EncStr = "pcrel udata4";
1051 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
1052 EncStr = "pcrel sdata4";
1054 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
1055 EncStr = "pcrel udata8";
1057 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
1058 EncStr = "screl sdata8";
1060 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata4:
1061 EncStr = "indirect pcrel udata4";
1063 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata4:
1064 EncStr = "indirect pcrel sdata4";
1066 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata8:
1067 EncStr = "indirect pcrel udata8";
1069 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata8:
1070 EncStr = "indirect pcrel sdata8";
1074 Streamer.AddComment(Twine(Prefix) + " = " + EncStr);
1077 Streamer.EmitIntValue(Encoding, 1);
1080 void FrameEmitterImpl::EmitCFIInstruction(MCObjectStreamer &Streamer,
1081 const MCCFIInstruction &Instr) {
1082 int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
1083 bool VerboseAsm = Streamer.isVerboseAsm();
1085 switch (Instr.getOperation()) {
1086 case MCCFIInstruction::OpRegister: {
1087 unsigned Reg1 = Instr.getRegister();
1088 unsigned Reg2 = Instr.getRegister2();
1090 Streamer.AddComment("DW_CFA_register");
1091 Streamer.AddComment(Twine("Reg1 ") + Twine(Reg1));
1092 Streamer.AddComment(Twine("Reg2 ") + Twine(Reg2));
1094 Streamer.EmitIntValue(dwarf::DW_CFA_register, 1);
1095 Streamer.EmitULEB128IntValue(Reg1);
1096 Streamer.EmitULEB128IntValue(Reg2);
1099 case MCCFIInstruction::OpWindowSave: {
1100 Streamer.EmitIntValue(dwarf::DW_CFA_GNU_window_save, 1);
1103 case MCCFIInstruction::OpUndefined: {
1104 unsigned Reg = Instr.getRegister();
1106 Streamer.AddComment("DW_CFA_undefined");
1107 Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1109 Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1);
1110 Streamer.EmitULEB128IntValue(Reg);
1113 case MCCFIInstruction::OpAdjustCfaOffset:
1114 case MCCFIInstruction::OpDefCfaOffset: {
1115 const bool IsRelative =
1116 Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset;
1119 Streamer.AddComment("DW_CFA_def_cfa_offset");
1120 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
1123 CFAOffset += Instr.getOffset();
1125 CFAOffset = -Instr.getOffset();
1128 Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
1129 Streamer.EmitULEB128IntValue(CFAOffset);
1133 case MCCFIInstruction::OpDefCfa: {
1135 Streamer.AddComment("DW_CFA_def_cfa");
1136 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
1139 Streamer.AddComment(Twine("Reg ") + Twine(Instr.getRegister()));
1140 Streamer.EmitULEB128IntValue(Instr.getRegister());
1142 CFAOffset = -Instr.getOffset();
1145 Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
1146 Streamer.EmitULEB128IntValue(CFAOffset);
1151 case MCCFIInstruction::OpDefCfaRegister: {
1153 Streamer.AddComment("DW_CFA_def_cfa_register");
1154 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
1157 Streamer.AddComment(Twine("Reg ") + Twine(Instr.getRegister()));
1158 Streamer.EmitULEB128IntValue(Instr.getRegister());
1163 case MCCFIInstruction::OpOffset:
1164 case MCCFIInstruction::OpRelOffset: {
1165 const bool IsRelative =
1166 Instr.getOperation() == MCCFIInstruction::OpRelOffset;
1168 unsigned Reg = Instr.getRegister();
1169 int Offset = Instr.getOffset();
1171 Offset -= CFAOffset;
1172 Offset = Offset / dataAlignmentFactor;
1175 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended_sf");
1176 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
1177 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1178 Streamer.EmitULEB128IntValue(Reg);
1179 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1180 Streamer.EmitSLEB128IntValue(Offset);
1181 } else if (Reg < 64) {
1182 if (VerboseAsm) Streamer.AddComment(Twine("DW_CFA_offset + Reg(") +
1184 Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
1185 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1186 Streamer.EmitULEB128IntValue(Offset);
1188 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended");
1189 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
1190 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1191 Streamer.EmitULEB128IntValue(Reg);
1192 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1193 Streamer.EmitULEB128IntValue(Offset);
1197 case MCCFIInstruction::OpRememberState:
1198 if (VerboseAsm) Streamer.AddComment("DW_CFA_remember_state");
1199 Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
1201 case MCCFIInstruction::OpRestoreState:
1202 if (VerboseAsm) Streamer.AddComment("DW_CFA_restore_state");
1203 Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
1205 case MCCFIInstruction::OpSameValue: {
1206 unsigned Reg = Instr.getRegister();
1207 if (VerboseAsm) Streamer.AddComment("DW_CFA_same_value");
1208 Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
1209 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1210 Streamer.EmitULEB128IntValue(Reg);
1213 case MCCFIInstruction::OpRestore: {
1214 unsigned Reg = Instr.getRegister();
1216 Streamer.AddComment("DW_CFA_restore");
1217 Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1219 Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1);
1222 case MCCFIInstruction::OpEscape:
1223 if (VerboseAsm) Streamer.AddComment("Escape bytes");
1224 Streamer.EmitBytes(Instr.getValues());
1227 llvm_unreachable("Unhandled case in switch");
1230 /// EmitFrameMoves - Emit frame instructions to describe the layout of the
1232 void FrameEmitterImpl::EmitCFIInstructions(MCObjectStreamer &streamer,
1233 ArrayRef<MCCFIInstruction> Instrs,
1234 MCSymbol *BaseLabel) {
1235 for (unsigned i = 0, N = Instrs.size(); i < N; ++i) {
1236 const MCCFIInstruction &Instr = Instrs[i];
1237 MCSymbol *Label = Instr.getLabel();
1238 // Throw out move if the label is invalid.
1239 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
1241 // Advance row if new location.
1242 if (BaseLabel && Label) {
1243 MCSymbol *ThisSym = Label;
1244 if (ThisSym != BaseLabel) {
1245 if (streamer.isVerboseAsm()) streamer.AddComment("DW_CFA_advance_loc4");
1246 streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
1247 BaseLabel = ThisSym;
1251 EmitCFIInstruction(streamer, Instr);
1255 /// EmitCompactUnwind - Emit the unwind information in a compact way.
1256 void FrameEmitterImpl::EmitCompactUnwind(MCStreamer &Streamer,
1257 const MCDwarfFrameInfo &Frame) {
1258 MCContext &Context = Streamer.getContext();
1259 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1260 bool VerboseAsm = Streamer.isVerboseAsm();
1262 // range-start range-length compact-unwind-enc personality-func lsda
1263 // _foo LfooEnd-_foo 0x00000023 0 0
1264 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1
1266 // .section __LD,__compact_unwind,regular,debug
1268 // # compact unwind for _foo
1270 // .set L1,LfooEnd-_foo
1276 // # compact unwind for _bar
1278 // .set L2,LbarEnd-_bar
1281 // .quad __gxx_personality
1282 // .quad except_tab1
1284 uint32_t Encoding = Frame.CompactUnwindEncoding;
1285 if (!Encoding) return;
1286 bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly());
1288 // The encoding needs to know we have an LSDA.
1289 if (!DwarfEHFrameOnly && Frame.Lsda)
1290 Encoding |= 0x40000000;
1293 unsigned FDEEncoding = MOFI->getFDEEncoding();
1294 unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
1295 if (VerboseAsm) Streamer.AddComment("Range Start");
1296 Streamer.EmitSymbolValue(Frame.Begin, Size);
1299 const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin,
1301 if (VerboseAsm) Streamer.AddComment("Range Length");
1302 Streamer.EmitAbsValue(Range, 4);
1305 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
1306 if (VerboseAsm) Streamer.AddComment("Compact Unwind Encoding: 0x" +
1307 Twine::utohexstr(Encoding));
1308 Streamer.EmitIntValue(Encoding, Size);
1310 // Personality Function
1311 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
1312 if (VerboseAsm) Streamer.AddComment("Personality Function");
1313 if (!DwarfEHFrameOnly && Frame.Personality)
1314 Streamer.EmitSymbolValue(Frame.Personality, Size);
1316 Streamer.EmitIntValue(0, Size); // No personality fn
1319 Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
1320 if (VerboseAsm) Streamer.AddComment("LSDA");
1321 if (!DwarfEHFrameOnly && Frame.Lsda)
1322 Streamer.EmitSymbolValue(Frame.Lsda, Size);
1324 Streamer.EmitIntValue(0, Size); // No LSDA
1327 const MCSymbol &FrameEmitterImpl::EmitCIE(MCObjectStreamer &streamer,
1328 const MCSymbol *personality,
1329 unsigned personalityEncoding,
1330 const MCSymbol *lsda,
1332 unsigned lsdaEncoding,
1334 MCContext &context = streamer.getContext();
1335 const MCRegisterInfo *MRI = context.getRegisterInfo();
1336 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1337 bool verboseAsm = streamer.isVerboseAsm();
1339 MCSymbol *sectionStart = context.CreateTempSymbol();
1340 streamer.EmitLabel(sectionStart);
1343 MCSymbol *sectionEnd = context.CreateTempSymbol();
1346 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *sectionStart,
1348 if (verboseAsm) streamer.AddComment("CIE Length");
1349 streamer.EmitAbsValue(Length, 4);
1352 unsigned CIE_ID = IsEH ? 0 : -1;
1353 if (verboseAsm) streamer.AddComment("CIE ID Tag");
1354 streamer.EmitIntValue(CIE_ID, 4);
1357 if (verboseAsm) streamer.AddComment("DW_CIE_VERSION");
1358 // For DWARF2, we use CIE version 1
1359 // For DWARF3+, we use CIE version 3
1360 uint8_t CIEVersion = context.getDwarfVersion() <= 2 ? 1 : 3;
1361 streamer.EmitIntValue(CIEVersion, 1);
1363 // Augmentation String
1364 SmallString<8> Augmentation;
1366 if (verboseAsm) streamer.AddComment("CIE Augmentation");
1367 Augmentation += "z";
1369 Augmentation += "P";
1371 Augmentation += "L";
1372 Augmentation += "R";
1374 Augmentation += "S";
1375 streamer.EmitBytes(Augmentation.str());
1377 streamer.EmitIntValue(0, 1);
1379 // Code Alignment Factor
1380 if (verboseAsm) streamer.AddComment("CIE Code Alignment Factor");
1381 streamer.EmitULEB128IntValue(context.getAsmInfo()->getMinInstAlignment());
1383 // Data Alignment Factor
1384 if (verboseAsm) streamer.AddComment("CIE Data Alignment Factor");
1385 streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer));
1387 // Return Address Register
1388 if (verboseAsm) streamer.AddComment("CIE Return Address Column");
1389 if (CIEVersion == 1) {
1390 assert(MRI->getRARegister() <= 255 &&
1391 "DWARF 2 encodes return_address_register in one byte");
1392 streamer.EmitIntValue(MRI->getDwarfRegNum(MRI->getRARegister(), true), 1);
1394 streamer.EmitULEB128IntValue(
1395 MRI->getDwarfRegNum(MRI->getRARegister(), true));
1398 // Augmentation Data Length (optional)
1400 unsigned augmentationLength = 0;
1403 // Personality Encoding
1404 augmentationLength += 1;
1406 augmentationLength += getSizeForEncoding(streamer, personalityEncoding);
1409 augmentationLength += 1;
1410 // Encoding of the FDE pointers
1411 augmentationLength += 1;
1413 if (verboseAsm) streamer.AddComment("Augmentation Size");
1414 streamer.EmitULEB128IntValue(augmentationLength);
1416 // Augmentation Data (optional)
1418 // Personality Encoding
1419 EmitEncodingByte(streamer, personalityEncoding,
1420 "Personality Encoding");
1422 if (verboseAsm) streamer.AddComment("Personality");
1423 EmitPersonality(streamer, *personality, personalityEncoding);
1427 EmitEncodingByte(streamer, lsdaEncoding, "LSDA Encoding");
1429 // Encoding of the FDE pointers
1430 EmitEncodingByte(streamer, MOFI->getFDEEncoding(), "FDE Encoding");
1433 // Initial Instructions
1435 const MCAsmInfo *MAI = context.getAsmInfo();
1437 const std::vector<MCCFIInstruction> &Instructions =
1438 MAI->getInitialFrameState();
1439 EmitCFIInstructions(streamer, Instructions, nullptr);
1443 streamer.EmitValueToAlignment(IsEH ? 4 : MAI->getPointerSize());
1445 streamer.EmitLabel(sectionEnd);
1446 return *sectionStart;
1449 MCSymbol *FrameEmitterImpl::EmitFDE(MCObjectStreamer &streamer,
1450 const MCSymbol &cieStart,
1451 const MCDwarfFrameInfo &frame) {
1452 MCContext &context = streamer.getContext();
1453 MCSymbol *fdeStart = context.CreateTempSymbol();
1454 MCSymbol *fdeEnd = context.CreateTempSymbol();
1455 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1456 bool verboseAsm = streamer.isVerboseAsm();
1459 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *fdeStart, *fdeEnd, 0);
1460 if (verboseAsm) streamer.AddComment("FDE Length");
1461 streamer.EmitAbsValue(Length, 4);
1463 streamer.EmitLabel(fdeStart);
1466 const MCAsmInfo *asmInfo = context.getAsmInfo();
1468 const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart,
1470 if (verboseAsm) streamer.AddComment("FDE CIE Offset");
1471 streamer.EmitAbsValue(offset, 4);
1472 } else if (!asmInfo->doesDwarfUseRelocationsAcrossSections()) {
1473 const MCExpr *offset = MakeStartMinusEndExpr(streamer, *SectionStart,
1475 streamer.EmitAbsValue(offset, 4);
1477 streamer.EmitSymbolValue(&cieStart, 4);
1481 unsigned PCEncoding =
1482 IsEH ? MOFI->getFDEEncoding() : (unsigned)dwarf::DW_EH_PE_absptr;
1483 unsigned PCSize = getSizeForEncoding(streamer, PCEncoding);
1484 EmitFDESymbol(streamer, *frame.Begin, PCEncoding, IsEH, "FDE initial location");
1487 const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin,
1489 if (verboseAsm) streamer.AddComment("FDE address range");
1490 streamer.EmitAbsValue(Range, PCSize);
1493 // Augmentation Data Length
1494 unsigned augmentationLength = 0;
1497 augmentationLength += getSizeForEncoding(streamer, frame.LsdaEncoding);
1499 if (verboseAsm) streamer.AddComment("Augmentation size");
1500 streamer.EmitULEB128IntValue(augmentationLength);
1502 // Augmentation Data
1504 EmitFDESymbol(streamer, *frame.Lsda, frame.LsdaEncoding, true,
1505 "Language Specific Data Area");
1508 // Call Frame Instructions
1509 EmitCFIInstructions(streamer, frame.Instructions, frame.Begin);
1512 streamer.EmitValueToAlignment(PCSize);
1519 static const CIEKey getEmptyKey() {
1520 return CIEKey(nullptr, 0, -1, false, false);
1522 static const CIEKey getTombstoneKey() {
1523 return CIEKey(nullptr, -1, 0, false, false);
1526 CIEKey(const MCSymbol *Personality_, unsigned PersonalityEncoding_,
1527 unsigned LsdaEncoding_, bool IsSignalFrame_, bool IsSimple_)
1528 : Personality(Personality_), PersonalityEncoding(PersonalityEncoding_),
1529 LsdaEncoding(LsdaEncoding_), IsSignalFrame(IsSignalFrame_),
1530 IsSimple(IsSimple_) {}
1531 const MCSymbol *Personality;
1532 unsigned PersonalityEncoding;
1533 unsigned LsdaEncoding;
1541 struct DenseMapInfo<CIEKey> {
1542 static CIEKey getEmptyKey() {
1543 return CIEKey::getEmptyKey();
1545 static CIEKey getTombstoneKey() {
1546 return CIEKey::getTombstoneKey();
1548 static unsigned getHashValue(const CIEKey &Key) {
1549 return static_cast<unsigned>(hash_combine(Key.Personality,
1550 Key.PersonalityEncoding,
1555 static bool isEqual(const CIEKey &LHS,
1556 const CIEKey &RHS) {
1557 return LHS.Personality == RHS.Personality &&
1558 LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
1559 LHS.LsdaEncoding == RHS.LsdaEncoding &&
1560 LHS.IsSignalFrame == RHS.IsSignalFrame &&
1561 LHS.IsSimple == RHS.IsSimple;
1566 void MCDwarfFrameEmitter::Emit(MCObjectStreamer &Streamer, MCAsmBackend *MAB,
1568 Streamer.generateCompactUnwindEncodings(MAB);
1570 MCContext &Context = Streamer.getContext();
1571 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1572 FrameEmitterImpl Emitter(IsEH);
1573 ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getDwarfFrameInfos();
1575 // Emit the compact unwind info if available.
1576 bool NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame();
1577 if (IsEH && MOFI->getCompactUnwindSection()) {
1578 bool SectionEmitted = false;
1579 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
1580 const MCDwarfFrameInfo &Frame = FrameArray[i];
1581 if (Frame.CompactUnwindEncoding == 0) continue;
1582 if (!SectionEmitted) {
1583 Streamer.SwitchSection(MOFI->getCompactUnwindSection());
1584 Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize());
1585 SectionEmitted = true;
1587 NeedsEHFrameSection |=
1588 Frame.CompactUnwindEncoding ==
1589 MOFI->getCompactUnwindDwarfEHFrameOnly();
1590 Emitter.EmitCompactUnwind(Streamer, Frame);
1594 if (!NeedsEHFrameSection) return;
1596 const MCSection &Section =
1597 IsEH ? *const_cast<MCObjectFileInfo*>(MOFI)->getEHFrameSection() :
1598 *MOFI->getDwarfFrameSection();
1600 Streamer.SwitchSection(&Section);
1601 MCSymbol *SectionStart = Context.CreateTempSymbol();
1602 Streamer.EmitLabel(SectionStart);
1603 Emitter.setSectionStart(SectionStart);
1605 MCSymbol *FDEEnd = nullptr;
1606 DenseMap<CIEKey, const MCSymbol *> CIEStarts;
1608 const MCSymbol *DummyDebugKey = nullptr;
1609 NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame();
1610 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
1611 const MCDwarfFrameInfo &Frame = FrameArray[i];
1613 // Emit the label from the previous iteration
1615 Streamer.EmitLabel(FDEEnd);
1619 if (!NeedsEHFrameSection && Frame.CompactUnwindEncoding !=
1620 MOFI->getCompactUnwindDwarfEHFrameOnly())
1621 // Don't generate an EH frame if we don't need one. I.e., it's taken care
1622 // of by the compact unwind encoding.
1625 CIEKey Key(Frame.Personality, Frame.PersonalityEncoding,
1626 Frame.LsdaEncoding, Frame.IsSignalFrame, Frame.IsSimple);
1627 const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
1629 CIEStart = &Emitter.EmitCIE(Streamer, Frame.Personality,
1630 Frame.PersonalityEncoding, Frame.Lsda,
1631 Frame.IsSignalFrame,
1635 FDEEnd = Emitter.EmitFDE(Streamer, *CIEStart, Frame);
1638 Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize());
1640 Streamer.EmitLabel(FDEEnd);
1643 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCObjectStreamer &Streamer,
1644 uint64_t AddrDelta) {
1645 MCContext &Context = Streamer.getContext();
1646 SmallString<256> Tmp;
1647 raw_svector_ostream OS(Tmp);
1648 MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OS);
1649 Streamer.EmitBytes(OS.str());
1652 void MCDwarfFrameEmitter::EncodeAdvanceLoc(MCContext &Context,
1655 // Scale the address delta by the minimum instruction length.
1656 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
1658 if (AddrDelta == 0) {
1659 } else if (isUIntN(6, AddrDelta)) {
1660 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
1662 } else if (isUInt<8>(AddrDelta)) {
1663 OS << uint8_t(dwarf::DW_CFA_advance_loc1);
1664 OS << uint8_t(AddrDelta);
1665 } else if (isUInt<16>(AddrDelta)) {
1666 // FIXME: check what is the correct behavior on a big endian machine.
1667 OS << uint8_t(dwarf::DW_CFA_advance_loc2);
1668 OS << uint8_t( AddrDelta & 0xff);
1669 OS << uint8_t((AddrDelta >> 8) & 0xff);
1671 // FIXME: check what is the correct behavior on a big endian machine.
1672 assert(isUInt<32>(AddrDelta));
1673 OS << uint8_t(dwarf::DW_CFA_advance_loc4);
1674 OS << uint8_t( AddrDelta & 0xff);
1675 OS << uint8_t((AddrDelta >> 8) & 0xff);
1676 OS << uint8_t((AddrDelta >> 16) & 0xff);
1677 OS << uint8_t((AddrDelta >> 24) & 0xff);