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/SmallString.h"
13 #include "llvm/ADT/Twine.h"
14 #include "llvm/Config/config.h"
15 #include "llvm/MC/MCAsmInfo.h"
16 #include "llvm/MC/MCContext.h"
17 #include "llvm/MC/MCExpr.h"
18 #include "llvm/MC/MCObjectFileInfo.h"
19 #include "llvm/MC/MCRegisterInfo.h"
20 #include "llvm/MC/MCStreamer.h"
21 #include "llvm/MC/MCSymbol.h"
22 #include "llvm/Support/Debug.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Support/LEB128.h"
25 #include "llvm/Support/Path.h"
26 #include "llvm/Support/SourceMgr.h"
27 #include "llvm/Support/raw_ostream.h"
30 // Given a special op, return the address skip amount (in units of
31 // DWARF2_LINE_MIN_INSN_LENGTH.
32 #define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE)
34 // The maximum address skip amount that can be encoded with a special op.
35 #define MAX_SPECIAL_ADDR_DELTA SPECIAL_ADDR(255)
37 // First special line opcode - leave room for the standard opcodes.
38 // Note: If you want to change this, you'll have to update the
39 // "standard_opcode_lengths" table that is emitted in DwarfFileTable::Emit().
40 #define DWARF2_LINE_OPCODE_BASE 13
42 // Minimum line offset in a special line info. opcode. This value
43 // was chosen to give a reasonable range of values.
44 #define DWARF2_LINE_BASE -5
46 // Range of line offsets in a special line info. opcode.
47 #define DWARF2_LINE_RANGE 14
49 static inline uint64_t ScaleAddrDelta(MCContext &Context, uint64_t AddrDelta) {
50 unsigned MinInsnLength = Context.getAsmInfo()->getMinInstAlignment();
51 if (MinInsnLength == 1)
53 if (AddrDelta % MinInsnLength != 0) {
54 // TODO: report this error, but really only once.
57 return AddrDelta / MinInsnLength;
61 // This is called when an instruction is assembled into the specified section
62 // and if there is information from the last .loc directive that has yet to have
63 // a line entry made for it is made.
65 void MCLineEntry::Make(MCStreamer *MCOS, const MCSection *Section) {
66 if (!MCOS->getContext().getDwarfLocSeen())
69 // Create a symbol at in the current section for use in the line entry.
70 MCSymbol *LineSym = MCOS->getContext().CreateTempSymbol();
71 // Set the value of the symbol to use for the MCLineEntry.
72 MCOS->EmitLabel(LineSym);
74 // Get the current .loc info saved in the context.
75 const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();
77 // Create a (local) line entry with the symbol and the current .loc info.
78 MCLineEntry LineEntry(LineSym, DwarfLoc);
80 // clear DwarfLocSeen saying the current .loc info is now used.
81 MCOS->getContext().ClearDwarfLocSeen();
83 // Add the line entry to this section's entries.
85 .getMCDwarfLineTable(MCOS->getContext().getDwarfCompileUnitID())
87 .addLineEntry(LineEntry, Section);
91 // This helper routine returns an expression of End - Start + IntVal .
93 static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS,
94 const MCSymbol &Start,
97 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
99 MCSymbolRefExpr::Create(&End, Variant, MCOS.getContext());
101 MCSymbolRefExpr::Create(&Start, Variant, MCOS.getContext());
103 MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext());
105 MCConstantExpr::Create(IntVal, MCOS.getContext());
107 MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext());
112 // This emits the Dwarf line table for the specified section from the entries
113 // in the LineSection.
116 EmitDwarfLineTable(MCStreamer *MCOS, const MCSection *Section,
117 const MCLineSection::MCLineEntryCollection &LineEntries) {
118 unsigned FileNum = 1;
119 unsigned LastLine = 1;
121 unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
123 unsigned Discriminator = 0;
124 MCSymbol *LastLabel = NULL;
126 // Loop through each MCLineEntry and encode the dwarf line number table.
127 for (auto it = LineEntries.begin(),
128 ie = LineEntries.end();
131 if (FileNum != it->getFileNum()) {
132 FileNum = it->getFileNum();
133 MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
134 MCOS->EmitULEB128IntValue(FileNum);
136 if (Column != it->getColumn()) {
137 Column = it->getColumn();
138 MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
139 MCOS->EmitULEB128IntValue(Column);
141 if (Discriminator != it->getDiscriminator()) {
142 Discriminator = it->getDiscriminator();
143 unsigned Size = getULEB128Size(Discriminator);
144 MCOS->EmitIntValue(dwarf::DW_LNS_extended_op, 1);
145 MCOS->EmitULEB128IntValue(Size + 1);
146 MCOS->EmitIntValue(dwarf::DW_LNE_set_discriminator, 1);
147 MCOS->EmitULEB128IntValue(Discriminator);
149 if (Isa != it->getIsa()) {
151 MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
152 MCOS->EmitULEB128IntValue(Isa);
154 if ((it->getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
155 Flags = it->getFlags();
156 MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
158 if (it->getFlags() & DWARF2_FLAG_BASIC_BLOCK)
159 MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
160 if (it->getFlags() & DWARF2_FLAG_PROLOGUE_END)
161 MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
162 if (it->getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
163 MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
165 int64_t LineDelta = static_cast<int64_t>(it->getLine()) - LastLine;
166 MCSymbol *Label = it->getLabel();
168 // At this point we want to emit/create the sequence to encode the delta in
169 // line numbers and the increment of the address from the previous Label
170 // and the current Label.
171 const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo();
172 MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label,
173 asmInfo->getPointerSize());
175 LastLine = it->getLine();
179 // Emit a DW_LNE_end_sequence for the end of the section.
180 // Using the pointer Section create a temporary label at the end of the
181 // section and use that and the LastLabel to compute the address delta
182 // and use INT64_MAX as the line delta which is the signal that this is
183 // actually a DW_LNE_end_sequence.
185 // Switch to the section to be able to create a symbol at its end.
186 // TODO: keep track of the last subsection so that this symbol appears in the
188 MCOS->SwitchSection(Section);
190 MCContext &context = MCOS->getContext();
191 // Create a symbol at the end of the section.
192 MCSymbol *SectionEnd = context.CreateTempSymbol();
193 // Set the value of the symbol, as we are at the end of the section.
194 MCOS->EmitLabel(SectionEnd);
196 // Switch back the dwarf line section.
197 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
199 const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo();
200 MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd,
201 asmInfo->getPointerSize());
205 // This emits the Dwarf file and the line tables.
207 void MCDwarfLineTable::Emit(MCStreamer *MCOS) {
208 MCContext &context = MCOS->getContext();
210 auto &LineTables = context.getMCDwarfLineTables();
212 // Bail out early so we don't switch to the debug_line section needlessly and
213 // in doing so create an unnecessary (if empty) section.
214 if (LineTables.empty())
217 // Switch to the section where the table will be emitted into.
218 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
220 // Handle the rest of the Compile Units.
221 for (const auto &CUIDTablePair : LineTables)
222 CUIDTablePair.second.EmitCU(MCOS);
225 void MCDwarfDwoLineTable::Emit(MCStreamer &MCOS) const {
226 MCOS.EmitLabel(Header.Emit(&MCOS, None).second);
229 std::pair<MCSymbol *, MCSymbol *> MCDwarfLineTableHeader::Emit(MCStreamer *MCOS) const {
230 static const char StandardOpcodeLengths[] = {
231 0, // length of DW_LNS_copy
232 1, // length of DW_LNS_advance_pc
233 1, // length of DW_LNS_advance_line
234 1, // length of DW_LNS_set_file
235 1, // length of DW_LNS_set_column
236 0, // length of DW_LNS_negate_stmt
237 0, // length of DW_LNS_set_basic_block
238 0, // length of DW_LNS_const_add_pc
239 1, // length of DW_LNS_fixed_advance_pc
240 0, // length of DW_LNS_set_prologue_end
241 0, // length of DW_LNS_set_epilogue_begin
244 assert(array_lengthof(StandardOpcodeLengths) == (DWARF2_LINE_OPCODE_BASE - 1));
245 return Emit(MCOS, StandardOpcodeLengths);
248 std::pair<MCSymbol *, MCSymbol *>
249 MCDwarfLineTableHeader::Emit(MCStreamer *MCOS,
250 ArrayRef<char> StandardOpcodeLengths) const {
252 MCContext &context = MCOS->getContext();
254 // Create a symbol at the beginning of the line table.
255 MCSymbol *LineStartSym = Label;
257 LineStartSym = context.CreateTempSymbol();
258 // Set the value of the symbol, as we are at the start of the line table.
259 MCOS->EmitLabel(LineStartSym);
261 // Create a symbol for the end of the section (to be set when we get there).
262 MCSymbol *LineEndSym = context.CreateTempSymbol();
264 // The first 4 bytes is the total length of the information for this
265 // compilation unit (not including these 4 bytes for the length).
266 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym,4),
269 // Next 2 bytes is the Version, which is Dwarf 2.
270 MCOS->EmitIntValue(2, 2);
272 // Create a symbol for the end of the prologue (to be set when we get there).
273 MCSymbol *ProEndSym = context.CreateTempSymbol(); // Lprologue_end
275 // Length of the prologue, is the next 4 bytes. Which is the start of the
276 // section to the end of the prologue. Not including the 4 bytes for the
277 // total length, the 2 bytes for the version, and these 4 bytes for the
278 // length of the prologue.
279 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym,
282 // Parameters of the state machine, are next.
283 MCOS->EmitIntValue(context.getAsmInfo()->getMinInstAlignment(), 1);
284 MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
285 MCOS->EmitIntValue(DWARF2_LINE_BASE, 1);
286 MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1);
287 MCOS->EmitIntValue(StandardOpcodeLengths.size() + 1, 1);
289 // Standard opcode lengths
290 for (char Length : StandardOpcodeLengths)
291 MCOS->EmitIntValue(Length, 1);
293 // Put out the directory and file tables.
295 // First the directory table.
296 for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
297 MCOS->EmitBytes(MCDwarfDirs[i]); // the DirectoryName
298 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
300 MCOS->EmitIntValue(0, 1); // Terminate the directory list
302 // Second the file table.
303 for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
304 assert(!MCDwarfFiles[i].Name.empty());
305 MCOS->EmitBytes(MCDwarfFiles[i].Name); // FileName
306 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
308 MCOS->EmitULEB128IntValue(MCDwarfFiles[i].DirIndex);
309 MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
310 MCOS->EmitIntValue(0, 1); // filesize (always 0)
312 MCOS->EmitIntValue(0, 1); // Terminate the file list
314 // This is the end of the prologue, so set the value of the symbol at the
315 // end of the prologue (that was used in a previous expression).
316 MCOS->EmitLabel(ProEndSym);
318 return std::make_pair(LineStartSym, LineEndSym);
321 void MCDwarfLineTable::EmitCU(MCStreamer *MCOS) const {
322 MCSymbol *LineEndSym = Header.Emit(MCOS).second;
324 // Put out the line tables.
325 for (const auto &LineSec : MCLineSections.getMCLineEntries())
326 EmitDwarfLineTable(MCOS, LineSec.first, LineSec.second);
328 if (MCOS->getContext().getAsmInfo()->getLinkerRequiresNonEmptyDwarfLines() &&
329 MCLineSections.getMCLineEntries().empty()) {
330 // The darwin9 linker has a bug (see PR8715). For for 32-bit architectures
332 // total_length >= prologue_length + 10
333 // We are 4 bytes short, since we have total_length = 51 and
334 // prologue_length = 45
336 // The regular end_sequence should be sufficient.
337 MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
340 // This is the end of the section, so set the value of the symbol at the end
341 // of this section (that was used in a previous expression).
342 MCOS->EmitLabel(LineEndSym);
345 unsigned MCDwarfLineTable::getFile(StringRef &Directory, StringRef &FileName,
346 unsigned FileNumber) {
347 return Header.getFile(Directory, FileName, FileNumber);
350 unsigned MCDwarfLineTableHeader::getFile(StringRef &Directory,
352 unsigned FileNumber) {
353 if (Directory == CompilationDir)
355 if (FileName.empty()) {
356 FileName = "<stdin>";
359 assert(!FileName.empty());
360 if (FileNumber == 0) {
361 FileNumber = SourceIdMap.size() + 1;
362 assert((MCDwarfFiles.empty() || FileNumber == MCDwarfFiles.size()) &&
363 "Don't mix autonumbered and explicit numbered line table usage");
364 StringMapEntry<unsigned> &Ent = SourceIdMap.GetOrCreateValue(
365 (Directory + Twine('\0') + FileName).str(), FileNumber);
366 if (Ent.getValue() != FileNumber)
367 return Ent.getValue();
369 // Make space for this FileNumber in the MCDwarfFiles vector if needed.
370 MCDwarfFiles.resize(FileNumber + 1);
372 // Get the new MCDwarfFile slot for this FileNumber.
373 MCDwarfFile &File = MCDwarfFiles[FileNumber];
375 // It is an error to use see the same number more than once.
376 if (!File.Name.empty())
379 if (Directory.empty()) {
380 // Separate the directory part from the basename of the FileName.
381 StringRef tFileName = sys::path::filename(FileName);
382 if (!tFileName.empty()) {
383 Directory = sys::path::parent_path(FileName);
384 if (!Directory.empty())
385 FileName = tFileName;
389 // Find or make an entry in the MCDwarfDirs vector for this Directory.
390 // Capture directory name.
392 if (Directory.empty()) {
393 // For FileNames with no directories a DirIndex of 0 is used.
397 for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
398 if (Directory == MCDwarfDirs[DirIndex])
401 if (DirIndex >= MCDwarfDirs.size())
402 MCDwarfDirs.push_back(Directory);
403 // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
404 // no directories. MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
405 // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
406 // are stored at MCDwarfFiles[FileNumber].Name .
410 File.Name = FileName;
411 File.DirIndex = DirIndex;
413 // return the allocated FileNumber.
417 /// Utility function to emit the encoding to a streamer.
418 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta,
419 uint64_t AddrDelta) {
420 MCContext &Context = MCOS->getContext();
421 SmallString<256> Tmp;
422 raw_svector_ostream OS(Tmp);
423 MCDwarfLineAddr::Encode(Context, LineDelta, AddrDelta, OS);
424 MCOS->EmitBytes(OS.str());
427 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
428 void MCDwarfLineAddr::Encode(MCContext &Context, int64_t LineDelta,
429 uint64_t AddrDelta, raw_ostream &OS) {
430 uint64_t Temp, Opcode;
431 bool NeedCopy = false;
433 // Scale the address delta by the minimum instruction length.
434 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
436 // A LineDelta of INT64_MAX is a signal that this is actually a
437 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
438 // end_sequence to emit the matrix entry.
439 if (LineDelta == INT64_MAX) {
440 if (AddrDelta == MAX_SPECIAL_ADDR_DELTA)
441 OS << char(dwarf::DW_LNS_const_add_pc);
443 OS << char(dwarf::DW_LNS_advance_pc);
444 encodeULEB128(AddrDelta, OS);
446 OS << char(dwarf::DW_LNS_extended_op);
448 OS << char(dwarf::DW_LNE_end_sequence);
452 // Bias the line delta by the base.
453 Temp = LineDelta - DWARF2_LINE_BASE;
455 // If the line increment is out of range of a special opcode, we must encode
456 // it with DW_LNS_advance_line.
457 if (Temp >= DWARF2_LINE_RANGE) {
458 OS << char(dwarf::DW_LNS_advance_line);
459 encodeSLEB128(LineDelta, OS);
462 Temp = 0 - DWARF2_LINE_BASE;
466 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
467 if (LineDelta == 0 && AddrDelta == 0) {
468 OS << char(dwarf::DW_LNS_copy);
472 // Bias the opcode by the special opcode base.
473 Temp += DWARF2_LINE_OPCODE_BASE;
475 // Avoid overflow when addr_delta is large.
476 if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) {
477 // Try using a special opcode.
478 Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE;
484 // Try using DW_LNS_const_add_pc followed by special op.
485 Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
487 OS << char(dwarf::DW_LNS_const_add_pc);
493 // Otherwise use DW_LNS_advance_pc.
494 OS << char(dwarf::DW_LNS_advance_pc);
495 encodeULEB128(AddrDelta, OS);
498 OS << char(dwarf::DW_LNS_copy);
503 // Utility function to write a tuple for .debug_abbrev.
504 static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) {
505 MCOS->EmitULEB128IntValue(Name);
506 MCOS->EmitULEB128IntValue(Form);
509 // When generating dwarf for assembly source files this emits
510 // the data for .debug_abbrev section which contains three DIEs.
511 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
512 MCContext &context = MCOS->getContext();
513 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
515 // DW_TAG_compile_unit DIE abbrev (1).
516 MCOS->EmitULEB128IntValue(1);
517 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit);
518 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
519 EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4);
520 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
521 EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
522 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
523 if (!context.getCompilationDir().empty())
524 EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
525 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
526 if (!DwarfDebugFlags.empty())
527 EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
528 EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string);
529 EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2);
530 EmitAbbrev(MCOS, 0, 0);
532 // DW_TAG_label DIE abbrev (2).
533 MCOS->EmitULEB128IntValue(2);
534 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_label);
535 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
536 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
537 EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);
538 EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);
539 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
540 EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag);
541 EmitAbbrev(MCOS, 0, 0);
543 // DW_TAG_unspecified_parameters DIE abbrev (3).
544 MCOS->EmitULEB128IntValue(3);
545 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters);
546 MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1);
547 EmitAbbrev(MCOS, 0, 0);
549 // Terminate the abbreviations for this compilation unit.
550 MCOS->EmitIntValue(0, 1);
553 // When generating dwarf for assembly source files this emits the data for
554 // .debug_aranges section. Which contains a header and a table of pairs of
555 // PointerSize'ed values for the address and size of section(s) with line table
556 // entries (just the default .text in our case) and a terminating pair of zeros.
557 static void EmitGenDwarfAranges(MCStreamer *MCOS,
558 const MCSymbol *InfoSectionSymbol) {
559 MCContext &context = MCOS->getContext();
561 // Create a symbol at the end of the section that we are creating the dwarf
562 // debugging info to use later in here as part of the expression to calculate
563 // the size of the section for the table.
564 MCOS->SwitchSection(context.getGenDwarfSection());
565 MCSymbol *SectionEndSym = context.CreateTempSymbol();
566 MCOS->EmitLabel(SectionEndSym);
567 context.setGenDwarfSectionEndSym(SectionEndSym);
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 the one default .text section we have in the table.
586 Length += 2 * AddrSize;
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(s)
611 // address and size, in our case just the one default .text section.
612 const MCExpr *Addr = MCSymbolRefExpr::Create(
613 context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
614 const MCExpr *Size = MakeStartMinusEndExpr(*MCOS,
615 *context.getGenDwarfSectionStartSym(), *SectionEndSym, 0);
616 MCOS->EmitValue(Addr, AddrSize);
617 MCOS->EmitAbsValue(Size, AddrSize);
619 // And finally the pair of terminating zeros.
620 MCOS->EmitIntValue(0, AddrSize);
621 MCOS->EmitIntValue(0, AddrSize);
624 // When generating dwarf for assembly source files this emits the data for
625 // .debug_info section which contains three parts. The header, the compile_unit
626 // DIE and a list of label DIEs.
627 static void EmitGenDwarfInfo(MCStreamer *MCOS,
628 const MCSymbol *AbbrevSectionSymbol,
629 const MCSymbol *LineSectionSymbol) {
630 MCContext &context = MCOS->getContext();
632 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
634 // Create a symbol at the start and end of this section used in here for the
635 // expression to calculate the length in the header.
636 MCSymbol *InfoStart = context.CreateTempSymbol();
637 MCOS->EmitLabel(InfoStart);
638 MCSymbol *InfoEnd = context.CreateTempSymbol();
640 // First part: the header.
642 // The 4 byte total length of the information for this compilation unit, not
643 // including these 4 bytes.
644 const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4);
645 MCOS->EmitAbsValue(Length, 4);
647 // The 2 byte DWARF version, which is 2.
648 MCOS->EmitIntValue(2, 2);
650 // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev,
651 // it is at the start of that section so this is zero.
652 if (AbbrevSectionSymbol) {
653 MCOS->EmitSymbolValue(AbbrevSectionSymbol, 4);
655 MCOS->EmitIntValue(0, 4);
658 const MCAsmInfo *asmInfo = context.getAsmInfo();
659 int AddrSize = asmInfo->getPointerSize();
660 // The 1 byte size of an address.
661 MCOS->EmitIntValue(AddrSize, 1);
663 // Second part: the compile_unit DIE.
665 // The DW_TAG_compile_unit DIE abbrev (1).
666 MCOS->EmitULEB128IntValue(1);
668 // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section,
669 // which is at the start of that section so this is zero.
670 if (LineSectionSymbol) {
671 MCOS->EmitSymbolValue(LineSectionSymbol, 4);
673 MCOS->EmitIntValue(0, 4);
676 // AT_low_pc, the first address of the default .text section.
677 const MCExpr *Start = MCSymbolRefExpr::Create(
678 context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
679 MCOS->EmitValue(Start, AddrSize);
681 // AT_high_pc, the last address of the default .text section.
682 const MCExpr *End = MCSymbolRefExpr::Create(
683 context.getGenDwarfSectionEndSym(), MCSymbolRefExpr::VK_None, context);
684 MCOS->EmitValue(End, AddrSize);
686 // AT_name, the name of the source file. Reconstruct from the first directory
687 // and file table entries.
688 const SmallVectorImpl<std::string> &MCDwarfDirs = context.getMCDwarfDirs();
689 if (MCDwarfDirs.size() > 0) {
690 MCOS->EmitBytes(MCDwarfDirs[0]);
691 MCOS->EmitBytes("/");
693 const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles =
694 MCOS->getContext().getMCDwarfFiles();
695 MCOS->EmitBytes(MCDwarfFiles[1].Name);
696 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
698 // AT_comp_dir, the working directory the assembly was done in.
699 if (!context.getCompilationDir().empty()) {
700 MCOS->EmitBytes(context.getCompilationDir());
701 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
704 // AT_APPLE_flags, the command line arguments of the assembler tool.
705 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
706 if (!DwarfDebugFlags.empty()){
707 MCOS->EmitBytes(DwarfDebugFlags);
708 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
711 // AT_producer, the version of the assembler tool.
712 StringRef DwarfDebugProducer = context.getDwarfDebugProducer();
713 if (!DwarfDebugProducer.empty()){
714 MCOS->EmitBytes(DwarfDebugProducer);
717 MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM "));
718 MCOS->EmitBytes(StringRef(PACKAGE_VERSION));
719 MCOS->EmitBytes(StringRef(")"));
721 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
723 // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2
724 // draft has no standard code for assembler.
725 MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2);
727 // Third part: the list of label DIEs.
729 // Loop on saved info for dwarf labels and create the DIEs for them.
730 const std::vector<const MCGenDwarfLabelEntry *> &Entries =
731 MCOS->getContext().getMCGenDwarfLabelEntries();
732 for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it =
733 Entries.begin(), ie = Entries.end(); it != ie;
735 const MCGenDwarfLabelEntry *Entry = *it;
737 // The DW_TAG_label DIE abbrev (2).
738 MCOS->EmitULEB128IntValue(2);
740 // AT_name, of the label without any leading underbar.
741 MCOS->EmitBytes(Entry->getName());
742 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
744 // AT_decl_file, index into the file table.
745 MCOS->EmitIntValue(Entry->getFileNumber(), 4);
747 // AT_decl_line, source line number.
748 MCOS->EmitIntValue(Entry->getLineNumber(), 4);
750 // AT_low_pc, start address of the label.
751 const MCExpr *AT_low_pc = MCSymbolRefExpr::Create(Entry->getLabel(),
752 MCSymbolRefExpr::VK_None, context);
753 MCOS->EmitValue(AT_low_pc, AddrSize);
755 // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype.
756 MCOS->EmitIntValue(0, 1);
758 // The DW_TAG_unspecified_parameters DIE abbrev (3).
759 MCOS->EmitULEB128IntValue(3);
761 // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's.
762 MCOS->EmitIntValue(0, 1);
764 // Deallocate the MCGenDwarfLabelEntry classes that saved away the info
765 // for the dwarf labels.
766 for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it =
767 Entries.begin(), ie = Entries.end(); it != ie;
769 const MCGenDwarfLabelEntry *Entry = *it;
773 // Add the NULL DIE terminating the Compile Unit DIE's.
774 MCOS->EmitIntValue(0, 1);
776 // Now set the value of the symbol at the end of the info section.
777 MCOS->EmitLabel(InfoEnd);
781 // When generating dwarf for assembly source files this emits the Dwarf
784 void MCGenDwarfInfo::Emit(MCStreamer *MCOS) {
785 // Create the dwarf sections in this order (.debug_line already created).
786 MCContext &context = MCOS->getContext();
787 const MCAsmInfo *AsmInfo = context.getAsmInfo();
788 bool CreateDwarfSectionSymbols =
789 AsmInfo->doesDwarfUseRelocationsAcrossSections();
790 MCSymbol *LineSectionSymbol = nullptr;
791 if (CreateDwarfSectionSymbols) {
792 LineSectionSymbol = context.CreateTempSymbol();
793 context.setMCLineTableSymbol(LineSectionSymbol, 0);
795 MCSymbol *AbbrevSectionSymbol = NULL;
796 MCSymbol *InfoSectionSymbol = NULL;
797 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
798 if (CreateDwarfSectionSymbols) {
799 InfoSectionSymbol = context.CreateTempSymbol();
800 MCOS->EmitLabel(InfoSectionSymbol);
802 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
803 if (CreateDwarfSectionSymbols) {
804 AbbrevSectionSymbol = context.CreateTempSymbol();
805 MCOS->EmitLabel(AbbrevSectionSymbol);
807 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
809 // If there are no line table entries then do not emit any section contents.
810 if (!context.hasMCLineSections())
813 // Output the data for .debug_aranges section.
814 EmitGenDwarfAranges(MCOS, InfoSectionSymbol);
816 // Output the data for .debug_abbrev section.
817 EmitGenDwarfAbbrev(MCOS);
819 // Output the data for .debug_info section.
820 EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol);
824 // When generating dwarf for assembly source files this is called when symbol
825 // for a label is created. If this symbol is not a temporary and is in the
826 // section that dwarf is being generated for, save the needed info to create
829 void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
830 SourceMgr &SrcMgr, SMLoc &Loc) {
831 // We won't create dwarf labels for temporary symbols or symbols not in
833 if (Symbol->isTemporary())
835 MCContext &context = MCOS->getContext();
836 if (context.getGenDwarfSection() != MCOS->getCurrentSection().first)
839 // The dwarf label's name does not have the symbol name's leading
841 StringRef Name = Symbol->getName();
842 if (Name.startswith("_"))
843 Name = Name.substr(1, Name.size()-1);
845 // Get the dwarf file number to be used for the dwarf label.
846 unsigned FileNumber = context.getGenDwarfFileNumber();
848 // Finding the line number is the expensive part which is why we just don't
849 // pass it in as for some symbols we won't create a dwarf label.
850 int CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
851 unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
853 // We create a temporary symbol for use for the AT_high_pc and AT_low_pc
854 // values so that they don't have things like an ARM thumb bit from the
855 // original symbol. So when used they won't get a low bit set after
857 MCSymbol *Label = context.CreateTempSymbol();
858 MCOS->EmitLabel(Label);
860 // Create and entry for the info and add it to the other entries.
861 MCGenDwarfLabelEntry *Entry =
862 new MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label);
863 MCOS->getContext().addMCGenDwarfLabelEntry(Entry);
866 static int getDataAlignmentFactor(MCStreamer &streamer) {
867 MCContext &context = streamer.getContext();
868 const MCAsmInfo *asmInfo = context.getAsmInfo();
869 int size = asmInfo->getCalleeSaveStackSlotSize();
870 if (asmInfo->isStackGrowthDirectionUp())
876 static unsigned getSizeForEncoding(MCStreamer &streamer,
877 unsigned symbolEncoding) {
878 MCContext &context = streamer.getContext();
879 unsigned format = symbolEncoding & 0x0f;
881 default: llvm_unreachable("Unknown Encoding");
882 case dwarf::DW_EH_PE_absptr:
883 case dwarf::DW_EH_PE_signed:
884 return context.getAsmInfo()->getPointerSize();
885 case dwarf::DW_EH_PE_udata2:
886 case dwarf::DW_EH_PE_sdata2:
888 case dwarf::DW_EH_PE_udata4:
889 case dwarf::DW_EH_PE_sdata4:
891 case dwarf::DW_EH_PE_udata8:
892 case dwarf::DW_EH_PE_sdata8:
897 static void EmitFDESymbol(MCStreamer &streamer, const MCSymbol &symbol,
898 unsigned symbolEncoding, bool isEH,
899 const char *comment = 0) {
900 MCContext &context = streamer.getContext();
901 const MCAsmInfo *asmInfo = context.getAsmInfo();
902 const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol,
905 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
906 if (streamer.isVerboseAsm() && comment) streamer.AddComment(comment);
907 if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH)
908 streamer.EmitAbsValue(v, size);
910 streamer.EmitValue(v, size);
913 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
914 unsigned symbolEncoding) {
915 MCContext &context = streamer.getContext();
916 const MCAsmInfo *asmInfo = context.getAsmInfo();
917 const MCExpr *v = asmInfo->getExprForPersonalitySymbol(&symbol,
920 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
921 streamer.EmitValue(v, size);
925 class FrameEmitterImpl {
930 const MCSymbol *SectionStart;
932 FrameEmitterImpl(bool usingCFI, bool isEH)
933 : CFAOffset(0), CIENum(0), UsingCFI(usingCFI), IsEH(isEH),
936 void setSectionStart(const MCSymbol *Label) { SectionStart = Label; }
938 /// EmitCompactUnwind - Emit the unwind information in a compact way.
939 void EmitCompactUnwind(MCStreamer &streamer,
940 const MCDwarfFrameInfo &frame);
942 const MCSymbol &EmitCIE(MCStreamer &streamer,
943 const MCSymbol *personality,
944 unsigned personalityEncoding,
945 const MCSymbol *lsda,
947 unsigned lsdaEncoding,
949 MCSymbol *EmitFDE(MCStreamer &streamer,
950 const MCSymbol &cieStart,
951 const MCDwarfFrameInfo &frame);
952 void EmitCFIInstructions(MCStreamer &streamer,
953 ArrayRef<MCCFIInstruction> Instrs,
954 MCSymbol *BaseLabel);
955 void EmitCFIInstruction(MCStreamer &Streamer,
956 const MCCFIInstruction &Instr);
959 } // end anonymous namespace
961 static void EmitEncodingByte(MCStreamer &Streamer, unsigned Encoding,
963 if (Streamer.isVerboseAsm()) {
966 default: EncStr = "<unknown encoding>"; break;
967 case dwarf::DW_EH_PE_absptr: EncStr = "absptr"; break;
968 case dwarf::DW_EH_PE_omit: EncStr = "omit"; break;
969 case dwarf::DW_EH_PE_pcrel: EncStr = "pcrel"; break;
970 case dwarf::DW_EH_PE_udata4: EncStr = "udata4"; break;
971 case dwarf::DW_EH_PE_udata8: EncStr = "udata8"; break;
972 case dwarf::DW_EH_PE_sdata4: EncStr = "sdata4"; break;
973 case dwarf::DW_EH_PE_sdata8: EncStr = "sdata8"; break;
974 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
975 EncStr = "pcrel udata4";
977 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
978 EncStr = "pcrel sdata4";
980 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
981 EncStr = "pcrel udata8";
983 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
984 EncStr = "screl sdata8";
986 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata4:
987 EncStr = "indirect pcrel udata4";
989 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata4:
990 EncStr = "indirect pcrel sdata4";
992 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata8:
993 EncStr = "indirect pcrel udata8";
995 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata8:
996 EncStr = "indirect pcrel sdata8";
1000 Streamer.AddComment(Twine(Prefix) + " = " + EncStr);
1003 Streamer.EmitIntValue(Encoding, 1);
1006 void FrameEmitterImpl::EmitCFIInstruction(MCStreamer &Streamer,
1007 const MCCFIInstruction &Instr) {
1008 int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
1009 bool VerboseAsm = Streamer.isVerboseAsm();
1011 switch (Instr.getOperation()) {
1012 case MCCFIInstruction::OpRegister: {
1013 unsigned Reg1 = Instr.getRegister();
1014 unsigned Reg2 = Instr.getRegister2();
1016 Streamer.AddComment("DW_CFA_register");
1017 Streamer.AddComment(Twine("Reg1 ") + Twine(Reg1));
1018 Streamer.AddComment(Twine("Reg2 ") + Twine(Reg2));
1020 Streamer.EmitIntValue(dwarf::DW_CFA_register, 1);
1021 Streamer.EmitULEB128IntValue(Reg1);
1022 Streamer.EmitULEB128IntValue(Reg2);
1025 case MCCFIInstruction::OpWindowSave: {
1026 Streamer.EmitIntValue(dwarf::DW_CFA_GNU_window_save, 1);
1029 case MCCFIInstruction::OpUndefined: {
1030 unsigned Reg = Instr.getRegister();
1032 Streamer.AddComment("DW_CFA_undefined");
1033 Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1035 Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1);
1036 Streamer.EmitULEB128IntValue(Reg);
1039 case MCCFIInstruction::OpAdjustCfaOffset:
1040 case MCCFIInstruction::OpDefCfaOffset: {
1041 const bool IsRelative =
1042 Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset;
1045 Streamer.AddComment("DW_CFA_def_cfa_offset");
1046 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
1049 CFAOffset += Instr.getOffset();
1051 CFAOffset = -Instr.getOffset();
1054 Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
1055 Streamer.EmitULEB128IntValue(CFAOffset);
1059 case MCCFIInstruction::OpDefCfa: {
1061 Streamer.AddComment("DW_CFA_def_cfa");
1062 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
1065 Streamer.AddComment(Twine("Reg ") + Twine(Instr.getRegister()));
1066 Streamer.EmitULEB128IntValue(Instr.getRegister());
1068 CFAOffset = -Instr.getOffset();
1071 Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
1072 Streamer.EmitULEB128IntValue(CFAOffset);
1077 case MCCFIInstruction::OpDefCfaRegister: {
1079 Streamer.AddComment("DW_CFA_def_cfa_register");
1080 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
1083 Streamer.AddComment(Twine("Reg ") + Twine(Instr.getRegister()));
1084 Streamer.EmitULEB128IntValue(Instr.getRegister());
1089 case MCCFIInstruction::OpOffset:
1090 case MCCFIInstruction::OpRelOffset: {
1091 const bool IsRelative =
1092 Instr.getOperation() == MCCFIInstruction::OpRelOffset;
1094 unsigned Reg = Instr.getRegister();
1095 int Offset = Instr.getOffset();
1097 Offset -= CFAOffset;
1098 Offset = Offset / dataAlignmentFactor;
1101 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended_sf");
1102 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
1103 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1104 Streamer.EmitULEB128IntValue(Reg);
1105 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1106 Streamer.EmitSLEB128IntValue(Offset);
1107 } else if (Reg < 64) {
1108 if (VerboseAsm) Streamer.AddComment(Twine("DW_CFA_offset + Reg(") +
1110 Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
1111 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1112 Streamer.EmitULEB128IntValue(Offset);
1114 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended");
1115 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
1116 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1117 Streamer.EmitULEB128IntValue(Reg);
1118 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1119 Streamer.EmitULEB128IntValue(Offset);
1123 case MCCFIInstruction::OpRememberState:
1124 if (VerboseAsm) Streamer.AddComment("DW_CFA_remember_state");
1125 Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
1127 case MCCFIInstruction::OpRestoreState:
1128 if (VerboseAsm) Streamer.AddComment("DW_CFA_restore_state");
1129 Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
1131 case MCCFIInstruction::OpSameValue: {
1132 unsigned Reg = Instr.getRegister();
1133 if (VerboseAsm) Streamer.AddComment("DW_CFA_same_value");
1134 Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
1135 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1136 Streamer.EmitULEB128IntValue(Reg);
1139 case MCCFIInstruction::OpRestore: {
1140 unsigned Reg = Instr.getRegister();
1142 Streamer.AddComment("DW_CFA_restore");
1143 Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1145 Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1);
1148 case MCCFIInstruction::OpEscape:
1149 if (VerboseAsm) Streamer.AddComment("Escape bytes");
1150 Streamer.EmitBytes(Instr.getValues());
1153 llvm_unreachable("Unhandled case in switch");
1156 /// EmitFrameMoves - Emit frame instructions to describe the layout of the
1158 void FrameEmitterImpl::EmitCFIInstructions(MCStreamer &streamer,
1159 ArrayRef<MCCFIInstruction> Instrs,
1160 MCSymbol *BaseLabel) {
1161 for (unsigned i = 0, N = Instrs.size(); i < N; ++i) {
1162 const MCCFIInstruction &Instr = Instrs[i];
1163 MCSymbol *Label = Instr.getLabel();
1164 // Throw out move if the label is invalid.
1165 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
1167 // Advance row if new location.
1168 if (BaseLabel && Label) {
1169 MCSymbol *ThisSym = Label;
1170 if (ThisSym != BaseLabel) {
1171 if (streamer.isVerboseAsm()) streamer.AddComment("DW_CFA_advance_loc4");
1172 streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
1173 BaseLabel = ThisSym;
1177 EmitCFIInstruction(streamer, Instr);
1181 /// EmitCompactUnwind - Emit the unwind information in a compact way.
1182 void FrameEmitterImpl::EmitCompactUnwind(MCStreamer &Streamer,
1183 const MCDwarfFrameInfo &Frame) {
1184 MCContext &Context = Streamer.getContext();
1185 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1186 bool VerboseAsm = Streamer.isVerboseAsm();
1188 // range-start range-length compact-unwind-enc personality-func lsda
1189 // _foo LfooEnd-_foo 0x00000023 0 0
1190 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1
1192 // .section __LD,__compact_unwind,regular,debug
1194 // # compact unwind for _foo
1196 // .set L1,LfooEnd-_foo
1202 // # compact unwind for _bar
1204 // .set L2,LbarEnd-_bar
1207 // .quad __gxx_personality
1208 // .quad except_tab1
1210 uint32_t Encoding = Frame.CompactUnwindEncoding;
1211 if (!Encoding) return;
1212 bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly());
1214 // The encoding needs to know we have an LSDA.
1215 if (!DwarfEHFrameOnly && Frame.Lsda)
1216 Encoding |= 0x40000000;
1219 unsigned FDEEncoding = MOFI->getFDEEncoding(UsingCFI);
1220 unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
1221 if (VerboseAsm) Streamer.AddComment("Range Start");
1222 Streamer.EmitSymbolValue(Frame.Function, Size);
1225 const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin,
1227 if (VerboseAsm) Streamer.AddComment("Range Length");
1228 Streamer.EmitAbsValue(Range, 4);
1231 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
1232 if (VerboseAsm) Streamer.AddComment("Compact Unwind Encoding: 0x" +
1233 Twine::utohexstr(Encoding));
1234 Streamer.EmitIntValue(Encoding, Size);
1236 // Personality Function
1237 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
1238 if (VerboseAsm) Streamer.AddComment("Personality Function");
1239 if (!DwarfEHFrameOnly && Frame.Personality)
1240 Streamer.EmitSymbolValue(Frame.Personality, Size);
1242 Streamer.EmitIntValue(0, Size); // No personality fn
1245 Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
1246 if (VerboseAsm) Streamer.AddComment("LSDA");
1247 if (!DwarfEHFrameOnly && Frame.Lsda)
1248 Streamer.EmitSymbolValue(Frame.Lsda, Size);
1250 Streamer.EmitIntValue(0, Size); // No LSDA
1253 const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
1254 const MCSymbol *personality,
1255 unsigned personalityEncoding,
1256 const MCSymbol *lsda,
1258 unsigned lsdaEncoding,
1260 MCContext &context = streamer.getContext();
1261 const MCRegisterInfo *MRI = context.getRegisterInfo();
1262 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1263 bool verboseAsm = streamer.isVerboseAsm();
1265 MCSymbol *sectionStart;
1266 if (MOFI->isFunctionEHFrameSymbolPrivate() || !IsEH)
1267 sectionStart = context.CreateTempSymbol();
1269 sectionStart = context.GetOrCreateSymbol(Twine("EH_frame") + Twine(CIENum));
1271 streamer.EmitLabel(sectionStart);
1274 MCSymbol *sectionEnd = context.CreateTempSymbol();
1277 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *sectionStart,
1279 if (verboseAsm) streamer.AddComment("CIE Length");
1280 streamer.EmitAbsValue(Length, 4);
1283 unsigned CIE_ID = IsEH ? 0 : -1;
1284 if (verboseAsm) streamer.AddComment("CIE ID Tag");
1285 streamer.EmitIntValue(CIE_ID, 4);
1288 if (verboseAsm) streamer.AddComment("DW_CIE_VERSION");
1289 streamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1);
1291 // Augmentation String
1292 SmallString<8> Augmentation;
1294 if (verboseAsm) streamer.AddComment("CIE Augmentation");
1295 Augmentation += "z";
1297 Augmentation += "P";
1299 Augmentation += "L";
1300 Augmentation += "R";
1302 Augmentation += "S";
1303 streamer.EmitBytes(Augmentation.str());
1305 streamer.EmitIntValue(0, 1);
1307 // Code Alignment Factor
1308 if (verboseAsm) streamer.AddComment("CIE Code Alignment Factor");
1309 streamer.EmitULEB128IntValue(context.getAsmInfo()->getMinInstAlignment());
1311 // Data Alignment Factor
1312 if (verboseAsm) streamer.AddComment("CIE Data Alignment Factor");
1313 streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer));
1315 // Return Address Register
1316 if (verboseAsm) streamer.AddComment("CIE Return Address Column");
1317 streamer.EmitULEB128IntValue(MRI->getDwarfRegNum(MRI->getRARegister(), true));
1319 // Augmentation Data Length (optional)
1321 unsigned augmentationLength = 0;
1324 // Personality Encoding
1325 augmentationLength += 1;
1327 augmentationLength += getSizeForEncoding(streamer, personalityEncoding);
1330 augmentationLength += 1;
1331 // Encoding of the FDE pointers
1332 augmentationLength += 1;
1334 if (verboseAsm) streamer.AddComment("Augmentation Size");
1335 streamer.EmitULEB128IntValue(augmentationLength);
1337 // Augmentation Data (optional)
1339 // Personality Encoding
1340 EmitEncodingByte(streamer, personalityEncoding,
1341 "Personality Encoding");
1343 if (verboseAsm) streamer.AddComment("Personality");
1344 EmitPersonality(streamer, *personality, personalityEncoding);
1348 EmitEncodingByte(streamer, lsdaEncoding, "LSDA Encoding");
1350 // Encoding of the FDE pointers
1351 EmitEncodingByte(streamer, MOFI->getFDEEncoding(UsingCFI),
1355 // Initial Instructions
1357 const MCAsmInfo *MAI = context.getAsmInfo();
1359 const std::vector<MCCFIInstruction> &Instructions =
1360 MAI->getInitialFrameState();
1361 EmitCFIInstructions(streamer, Instructions, NULL);
1365 streamer.EmitValueToAlignment(IsEH ? 4 : MAI->getPointerSize());
1367 streamer.EmitLabel(sectionEnd);
1368 return *sectionStart;
1371 MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
1372 const MCSymbol &cieStart,
1373 const MCDwarfFrameInfo &frame) {
1374 MCContext &context = streamer.getContext();
1375 MCSymbol *fdeStart = context.CreateTempSymbol();
1376 MCSymbol *fdeEnd = context.CreateTempSymbol();
1377 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1378 bool verboseAsm = streamer.isVerboseAsm();
1380 if (IsEH && frame.Function && !MOFI->isFunctionEHFrameSymbolPrivate()) {
1382 context.GetOrCreateSymbol(frame.Function->getName() + Twine(".eh"));
1383 streamer.EmitEHSymAttributes(frame.Function, EHSym);
1384 streamer.EmitLabel(EHSym);
1388 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *fdeStart, *fdeEnd, 0);
1389 if (verboseAsm) streamer.AddComment("FDE Length");
1390 streamer.EmitAbsValue(Length, 4);
1392 streamer.EmitLabel(fdeStart);
1395 const MCAsmInfo *asmInfo = context.getAsmInfo();
1397 const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart,
1399 if (verboseAsm) streamer.AddComment("FDE CIE Offset");
1400 streamer.EmitAbsValue(offset, 4);
1401 } else if (!asmInfo->doesDwarfUseRelocationsAcrossSections()) {
1402 const MCExpr *offset = MakeStartMinusEndExpr(streamer, *SectionStart,
1404 streamer.EmitAbsValue(offset, 4);
1406 streamer.EmitSymbolValue(&cieStart, 4);
1410 unsigned PCEncoding = IsEH ? MOFI->getFDEEncoding(UsingCFI)
1411 : (unsigned)dwarf::DW_EH_PE_absptr;
1412 unsigned PCSize = getSizeForEncoding(streamer, PCEncoding);
1413 EmitFDESymbol(streamer, *frame.Begin, PCEncoding, IsEH, "FDE initial location");
1416 const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin,
1418 if (verboseAsm) streamer.AddComment("FDE address range");
1419 streamer.EmitAbsValue(Range, PCSize);
1422 // Augmentation Data Length
1423 unsigned augmentationLength = 0;
1426 augmentationLength += getSizeForEncoding(streamer, frame.LsdaEncoding);
1428 if (verboseAsm) streamer.AddComment("Augmentation size");
1429 streamer.EmitULEB128IntValue(augmentationLength);
1431 // Augmentation Data
1433 EmitFDESymbol(streamer, *frame.Lsda, frame.LsdaEncoding, true,
1434 "Language Specific Data Area");
1437 // Call Frame Instructions
1438 EmitCFIInstructions(streamer, frame.Instructions, frame.Begin);
1441 streamer.EmitValueToAlignment(PCSize);
1448 static const CIEKey getEmptyKey() { return CIEKey(0, 0, -1, false, false); }
1449 static const CIEKey getTombstoneKey() { return CIEKey(0, -1, 0, false, false); }
1451 CIEKey(const MCSymbol* Personality_, unsigned PersonalityEncoding_,
1452 unsigned LsdaEncoding_, bool IsSignalFrame_, bool IsSimple_) :
1453 Personality(Personality_), PersonalityEncoding(PersonalityEncoding_),
1454 LsdaEncoding(LsdaEncoding_), IsSignalFrame(IsSignalFrame_),
1455 IsSimple(IsSimple_) {
1457 const MCSymbol* Personality;
1458 unsigned PersonalityEncoding;
1459 unsigned LsdaEncoding;
1467 struct DenseMapInfo<CIEKey> {
1468 static CIEKey getEmptyKey() {
1469 return CIEKey::getEmptyKey();
1471 static CIEKey getTombstoneKey() {
1472 return CIEKey::getTombstoneKey();
1474 static unsigned getHashValue(const CIEKey &Key) {
1475 return static_cast<unsigned>(hash_combine(Key.Personality,
1476 Key.PersonalityEncoding,
1481 static bool isEqual(const CIEKey &LHS,
1482 const CIEKey &RHS) {
1483 return LHS.Personality == RHS.Personality &&
1484 LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
1485 LHS.LsdaEncoding == RHS.LsdaEncoding &&
1486 LHS.IsSignalFrame == RHS.IsSignalFrame &&
1487 LHS.IsSimple == RHS.IsSimple;
1492 void MCDwarfFrameEmitter::Emit(MCStreamer &Streamer, MCAsmBackend *MAB,
1493 bool UsingCFI, bool IsEH) {
1494 Streamer.generateCompactUnwindEncodings(MAB);
1496 MCContext &Context = Streamer.getContext();
1497 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1498 FrameEmitterImpl Emitter(UsingCFI, IsEH);
1499 ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getFrameInfos();
1501 // Emit the compact unwind info if available.
1502 bool NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame();
1503 if (IsEH && MOFI->getCompactUnwindSection()) {
1504 bool SectionEmitted = false;
1505 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
1506 const MCDwarfFrameInfo &Frame = FrameArray[i];
1507 if (Frame.CompactUnwindEncoding == 0) continue;
1508 if (!SectionEmitted) {
1509 Streamer.SwitchSection(MOFI->getCompactUnwindSection());
1510 Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize());
1511 SectionEmitted = true;
1513 NeedsEHFrameSection |=
1514 Frame.CompactUnwindEncoding ==
1515 MOFI->getCompactUnwindDwarfEHFrameOnly();
1516 Emitter.EmitCompactUnwind(Streamer, Frame);
1520 if (!NeedsEHFrameSection) return;
1522 const MCSection &Section =
1523 IsEH ? *const_cast<MCObjectFileInfo*>(MOFI)->getEHFrameSection() :
1524 *MOFI->getDwarfFrameSection();
1526 Streamer.SwitchSection(&Section);
1527 MCSymbol *SectionStart = Context.CreateTempSymbol();
1528 Streamer.EmitLabel(SectionStart);
1529 Emitter.setSectionStart(SectionStart);
1531 MCSymbol *FDEEnd = NULL;
1532 DenseMap<CIEKey, const MCSymbol*> CIEStarts;
1534 const MCSymbol *DummyDebugKey = NULL;
1535 NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame();
1536 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
1537 const MCDwarfFrameInfo &Frame = FrameArray[i];
1539 // Emit the label from the previous iteration
1541 Streamer.EmitLabel(FDEEnd);
1545 if (!NeedsEHFrameSection && Frame.CompactUnwindEncoding !=
1546 MOFI->getCompactUnwindDwarfEHFrameOnly())
1547 // Don't generate an EH frame if we don't need one. I.e., it's taken care
1548 // of by the compact unwind encoding.
1551 CIEKey Key(Frame.Personality, Frame.PersonalityEncoding,
1552 Frame.LsdaEncoding, Frame.IsSignalFrame, Frame.IsSimple);
1553 const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
1555 CIEStart = &Emitter.EmitCIE(Streamer, Frame.Personality,
1556 Frame.PersonalityEncoding, Frame.Lsda,
1557 Frame.IsSignalFrame,
1561 FDEEnd = Emitter.EmitFDE(Streamer, *CIEStart, Frame);
1564 Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize());
1566 Streamer.EmitLabel(FDEEnd);
1569 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCStreamer &Streamer,
1570 uint64_t AddrDelta) {
1571 MCContext &Context = Streamer.getContext();
1572 SmallString<256> Tmp;
1573 raw_svector_ostream OS(Tmp);
1574 MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OS);
1575 Streamer.EmitBytes(OS.str());
1578 void MCDwarfFrameEmitter::EncodeAdvanceLoc(MCContext &Context,
1581 // Scale the address delta by the minimum instruction length.
1582 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
1584 if (AddrDelta == 0) {
1585 } else if (isUIntN(6, AddrDelta)) {
1586 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
1588 } else if (isUInt<8>(AddrDelta)) {
1589 OS << uint8_t(dwarf::DW_CFA_advance_loc1);
1590 OS << uint8_t(AddrDelta);
1591 } else if (isUInt<16>(AddrDelta)) {
1592 // FIXME: check what is the correct behavior on a big endian machine.
1593 OS << uint8_t(dwarf::DW_CFA_advance_loc2);
1594 OS << uint8_t( AddrDelta & 0xff);
1595 OS << uint8_t((AddrDelta >> 8) & 0xff);
1597 // FIXME: check what is the correct behavior on a big endian machine.
1598 assert(isUInt<32>(AddrDelta));
1599 OS << uint8_t(dwarf::DW_CFA_advance_loc4);
1600 OS << uint8_t( AddrDelta & 0xff);
1601 OS << uint8_t((AddrDelta >> 8) & 0xff);
1602 OS << uint8_t((AddrDelta >> 16) & 0xff);
1603 OS << uint8_t((AddrDelta >> 24) & 0xff);