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 const MCSymbol *MCDwarfLineTable::Emit(MCStreamer *MCOS) {
208 MCContext &context = MCOS->getContext();
210 // CUID and MCLineTableSymbols are set in DwarfDebug, when DwarfDebug does
211 // not exist, CUID will be 0 and MCLineTableSymbols will be empty.
212 // Handle Compile Unit 0, the line table start symbol is the section symbol.
213 auto I = MCOS->getContext().getMCDwarfLineTables().begin(),
214 E = MCOS->getContext().getMCDwarfLineTables().end();
216 // Switch to the section where the table will be emitted into.
217 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
219 const MCSymbol *LineStartSym = I->second.EmitCU(MCOS);
220 // Handle the rest of the Compile Units.
221 for (++I; I != E; ++I)
222 I->second.EmitCU(MCOS);
227 std::pair<MCSymbol *, MCSymbol *> MCDwarfLineTableHeader::Emit(MCStreamer *MCOS) const {
228 MCContext &context = MCOS->getContext();
230 // Create a symbol at the beginning of the line table.
231 MCSymbol *LineStartSym = Label;
233 LineStartSym = context.CreateTempSymbol();
234 // Set the value of the symbol, as we are at the start of the line table.
235 MCOS->EmitLabel(LineStartSym);
237 // Create a symbol for the end of the section (to be set when we get there).
238 MCSymbol *LineEndSym = context.CreateTempSymbol();
240 // The first 4 bytes is the total length of the information for this
241 // compilation unit (not including these 4 bytes for the length).
242 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym,4),
245 // Next 2 bytes is the Version, which is Dwarf 2.
246 MCOS->EmitIntValue(2, 2);
248 // Create a symbol for the end of the prologue (to be set when we get there).
249 MCSymbol *ProEndSym = context.CreateTempSymbol(); // Lprologue_end
251 // Length of the prologue, is the next 4 bytes. Which is the start of the
252 // section to the end of the prologue. Not including the 4 bytes for the
253 // total length, the 2 bytes for the version, and these 4 bytes for the
254 // length of the prologue.
255 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym,
258 // Parameters of the state machine, are next.
259 MCOS->EmitIntValue(context.getAsmInfo()->getMinInstAlignment(), 1);
260 MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
261 MCOS->EmitIntValue(DWARF2_LINE_BASE, 1);
262 MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1);
263 MCOS->EmitIntValue(DWARF2_LINE_OPCODE_BASE, 1);
265 // Standard opcode lengths
266 MCOS->EmitIntValue(0, 1); // length of DW_LNS_copy
267 MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_pc
268 MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_line
269 MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_file
270 MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_column
271 MCOS->EmitIntValue(0, 1); // length of DW_LNS_negate_stmt
272 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_basic_block
273 MCOS->EmitIntValue(0, 1); // length of DW_LNS_const_add_pc
274 MCOS->EmitIntValue(1, 1); // length of DW_LNS_fixed_advance_pc
275 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_prologue_end
276 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_epilogue_begin
277 MCOS->EmitIntValue(1, 1); // DW_LNS_set_isa
279 // Put out the directory and file tables.
281 // First the directory table.
282 for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
283 MCOS->EmitBytes(MCDwarfDirs[i]); // the DirectoryName
284 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
286 MCOS->EmitIntValue(0, 1); // Terminate the directory list
288 // Second the file table.
289 for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
290 assert(!MCDwarfFiles[i].Name.empty());
291 MCOS->EmitBytes(MCDwarfFiles[i].Name); // FileName
292 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
294 MCOS->EmitULEB128IntValue(MCDwarfFiles[i].DirIndex);
295 MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
296 MCOS->EmitIntValue(0, 1); // filesize (always 0)
298 MCOS->EmitIntValue(0, 1); // Terminate the file list
300 // This is the end of the prologue, so set the value of the symbol at the
301 // end of the prologue (that was used in a previous expression).
302 MCOS->EmitLabel(ProEndSym);
304 return std::make_pair(LineStartSym, LineEndSym);
307 const MCSymbol *MCDwarfLineTable::EmitCU(MCStreamer *MCOS) const {
308 MCSymbol *LineStartSym;
309 MCSymbol *LineEndSym;
310 std::tie(LineStartSym, LineEndSym) = Header.Emit(MCOS);
312 // Put out the line tables.
313 for (const auto &LineSec : MCLineSections.getMCLineEntries())
314 EmitDwarfLineTable(MCOS, LineSec.first, LineSec.second);
316 if (MCOS->getContext().getAsmInfo()->getLinkerRequiresNonEmptyDwarfLines() &&
317 MCLineSections.getMCLineEntries().empty()) {
318 // The darwin9 linker has a bug (see PR8715). For for 32-bit architectures
320 // total_length >= prologue_length + 10
321 // We are 4 bytes short, since we have total_length = 51 and
322 // prologue_length = 45
324 // The regular end_sequence should be sufficient.
325 MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
328 // This is the end of the section, so set the value of the symbol at the end
329 // of this section (that was used in a previous expression).
330 MCOS->EmitLabel(LineEndSym);
335 unsigned MCDwarfLineTable::getFile(StringRef &Directory, StringRef &FileName,
336 unsigned FileNumber) {
337 return Header.getFile(Directory, FileName, FileNumber);
340 unsigned MCDwarfLineTableHeader::getFile(StringRef &Directory,
342 unsigned FileNumber) {
343 if (FileName.empty()) {
344 FileName = "<stdin>";
347 assert(!FileName.empty());
348 if (FileNumber == 0) {
349 FileNumber = SourceIdMap.size() + 1;
350 assert((MCDwarfFiles.empty() || FileNumber == MCDwarfFiles.size()) &&
351 "Don't mix autonumbered and explicit numbered line table usage");
352 StringMapEntry<unsigned> &Ent = SourceIdMap.GetOrCreateValue(
353 (Directory + Twine('\0') + FileName).str(), FileNumber);
354 if (Ent.getValue() != FileNumber)
355 return Ent.getValue();
357 // Make space for this FileNumber in the MCDwarfFiles vector if needed.
358 MCDwarfFiles.resize(FileNumber + 1);
360 // Get the new MCDwarfFile slot for this FileNumber.
361 MCDwarfFile &File = MCDwarfFiles[FileNumber];
363 // It is an error to use see the same number more than once.
364 if (!File.Name.empty())
367 if (Directory.empty()) {
368 // Separate the directory part from the basename of the FileName.
369 StringRef tFileName = sys::path::filename(FileName);
370 if (!tFileName.empty()) {
371 Directory = sys::path::parent_path(FileName);
372 if (!Directory.empty())
373 FileName = tFileName;
377 // Find or make an entry in the MCDwarfDirs vector for this Directory.
378 // Capture directory name.
380 if (Directory.empty()) {
381 // For FileNames with no directories a DirIndex of 0 is used.
385 for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
386 if (Directory == MCDwarfDirs[DirIndex])
389 if (DirIndex >= MCDwarfDirs.size())
390 MCDwarfDirs.push_back(Directory);
391 // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
392 // no directories. MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
393 // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
394 // are stored at MCDwarfFiles[FileNumber].Name .
398 File.Name = FileName;
399 File.DirIndex = DirIndex;
401 // return the allocated FileNumber.
405 /// Utility function to emit the encoding to a streamer.
406 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta,
407 uint64_t AddrDelta) {
408 MCContext &Context = MCOS->getContext();
409 SmallString<256> Tmp;
410 raw_svector_ostream OS(Tmp);
411 MCDwarfLineAddr::Encode(Context, LineDelta, AddrDelta, OS);
412 MCOS->EmitBytes(OS.str());
415 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
416 void MCDwarfLineAddr::Encode(MCContext &Context, int64_t LineDelta,
417 uint64_t AddrDelta, raw_ostream &OS) {
418 uint64_t Temp, Opcode;
419 bool NeedCopy = false;
421 // Scale the address delta by the minimum instruction length.
422 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
424 // A LineDelta of INT64_MAX is a signal that this is actually a
425 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
426 // end_sequence to emit the matrix entry.
427 if (LineDelta == INT64_MAX) {
428 if (AddrDelta == MAX_SPECIAL_ADDR_DELTA)
429 OS << char(dwarf::DW_LNS_const_add_pc);
431 OS << char(dwarf::DW_LNS_advance_pc);
432 encodeULEB128(AddrDelta, OS);
434 OS << char(dwarf::DW_LNS_extended_op);
436 OS << char(dwarf::DW_LNE_end_sequence);
440 // Bias the line delta by the base.
441 Temp = LineDelta - DWARF2_LINE_BASE;
443 // If the line increment is out of range of a special opcode, we must encode
444 // it with DW_LNS_advance_line.
445 if (Temp >= DWARF2_LINE_RANGE) {
446 OS << char(dwarf::DW_LNS_advance_line);
447 encodeSLEB128(LineDelta, OS);
450 Temp = 0 - DWARF2_LINE_BASE;
454 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
455 if (LineDelta == 0 && AddrDelta == 0) {
456 OS << char(dwarf::DW_LNS_copy);
460 // Bias the opcode by the special opcode base.
461 Temp += DWARF2_LINE_OPCODE_BASE;
463 // Avoid overflow when addr_delta is large.
464 if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) {
465 // Try using a special opcode.
466 Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE;
472 // Try using DW_LNS_const_add_pc followed by special op.
473 Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
475 OS << char(dwarf::DW_LNS_const_add_pc);
481 // Otherwise use DW_LNS_advance_pc.
482 OS << char(dwarf::DW_LNS_advance_pc);
483 encodeULEB128(AddrDelta, OS);
486 OS << char(dwarf::DW_LNS_copy);
491 // Utility function to write a tuple for .debug_abbrev.
492 static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) {
493 MCOS->EmitULEB128IntValue(Name);
494 MCOS->EmitULEB128IntValue(Form);
497 // When generating dwarf for assembly source files this emits
498 // the data for .debug_abbrev section which contains three DIEs.
499 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
500 MCContext &context = MCOS->getContext();
501 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
503 // DW_TAG_compile_unit DIE abbrev (1).
504 MCOS->EmitULEB128IntValue(1);
505 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit);
506 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
507 EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4);
508 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
509 EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
510 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
511 if (!context.getCompilationDir().empty())
512 EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
513 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
514 if (!DwarfDebugFlags.empty())
515 EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
516 EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string);
517 EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2);
518 EmitAbbrev(MCOS, 0, 0);
520 // DW_TAG_label DIE abbrev (2).
521 MCOS->EmitULEB128IntValue(2);
522 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_label);
523 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
524 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
525 EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);
526 EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);
527 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
528 EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag);
529 EmitAbbrev(MCOS, 0, 0);
531 // DW_TAG_unspecified_parameters DIE abbrev (3).
532 MCOS->EmitULEB128IntValue(3);
533 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters);
534 MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1);
535 EmitAbbrev(MCOS, 0, 0);
537 // Terminate the abbreviations for this compilation unit.
538 MCOS->EmitIntValue(0, 1);
541 // When generating dwarf for assembly source files this emits the data for
542 // .debug_aranges section. Which contains a header and a table of pairs of
543 // PointerSize'ed values for the address and size of section(s) with line table
544 // entries (just the default .text in our case) and a terminating pair of zeros.
545 static void EmitGenDwarfAranges(MCStreamer *MCOS,
546 const MCSymbol *InfoSectionSymbol) {
547 MCContext &context = MCOS->getContext();
549 // Create a symbol at the end of the section that we are creating the dwarf
550 // debugging info to use later in here as part of the expression to calculate
551 // the size of the section for the table.
552 MCOS->SwitchSection(context.getGenDwarfSection());
553 MCSymbol *SectionEndSym = context.CreateTempSymbol();
554 MCOS->EmitLabel(SectionEndSym);
555 context.setGenDwarfSectionEndSym(SectionEndSym);
557 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
559 // This will be the length of the .debug_aranges section, first account for
560 // the size of each item in the header (see below where we emit these items).
561 int Length = 4 + 2 + 4 + 1 + 1;
563 // Figure the padding after the header before the table of address and size
564 // pairs who's values are PointerSize'ed.
565 const MCAsmInfo *asmInfo = context.getAsmInfo();
566 int AddrSize = asmInfo->getPointerSize();
567 int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1));
568 if (Pad == 2 * AddrSize)
572 // Add the size of the pair of PointerSize'ed values for the address and size
573 // of the one default .text section we have in the table.
574 Length += 2 * AddrSize;
575 // And the pair of terminating zeros.
576 Length += 2 * AddrSize;
579 // Emit the header for this section.
580 // The 4 byte length not including the 4 byte value for the length.
581 MCOS->EmitIntValue(Length - 4, 4);
582 // The 2 byte version, which is 2.
583 MCOS->EmitIntValue(2, 2);
584 // The 4 byte offset to the compile unit in the .debug_info from the start
585 // of the .debug_info.
586 if (InfoSectionSymbol)
587 MCOS->EmitSymbolValue(InfoSectionSymbol, 4);
589 MCOS->EmitIntValue(0, 4);
590 // The 1 byte size of an address.
591 MCOS->EmitIntValue(AddrSize, 1);
592 // The 1 byte size of a segment descriptor, we use a value of zero.
593 MCOS->EmitIntValue(0, 1);
594 // Align the header with the padding if needed, before we put out the table.
595 for(int i = 0; i < Pad; i++)
596 MCOS->EmitIntValue(0, 1);
598 // Now emit the table of pairs of PointerSize'ed values for the section(s)
599 // address and size, in our case just the one default .text section.
600 const MCExpr *Addr = MCSymbolRefExpr::Create(
601 context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
602 const MCExpr *Size = MakeStartMinusEndExpr(*MCOS,
603 *context.getGenDwarfSectionStartSym(), *SectionEndSym, 0);
604 MCOS->EmitAbsValue(Addr, AddrSize);
605 MCOS->EmitAbsValue(Size, AddrSize);
607 // And finally the pair of terminating zeros.
608 MCOS->EmitIntValue(0, AddrSize);
609 MCOS->EmitIntValue(0, AddrSize);
612 // When generating dwarf for assembly source files this emits the data for
613 // .debug_info section which contains three parts. The header, the compile_unit
614 // DIE and a list of label DIEs.
615 static void EmitGenDwarfInfo(MCStreamer *MCOS,
616 const MCSymbol *AbbrevSectionSymbol,
617 const MCSymbol *LineSectionSymbol) {
618 MCContext &context = MCOS->getContext();
620 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
622 // Create a symbol at the start and end of this section used in here for the
623 // expression to calculate the length in the header.
624 MCSymbol *InfoStart = context.CreateTempSymbol();
625 MCOS->EmitLabel(InfoStart);
626 MCSymbol *InfoEnd = context.CreateTempSymbol();
628 // First part: the header.
630 // The 4 byte total length of the information for this compilation unit, not
631 // including these 4 bytes.
632 const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4);
633 MCOS->EmitAbsValue(Length, 4);
635 // The 2 byte DWARF version, which is 2.
636 MCOS->EmitIntValue(2, 2);
638 // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev,
639 // it is at the start of that section so this is zero.
640 if (AbbrevSectionSymbol) {
641 MCOS->EmitSymbolValue(AbbrevSectionSymbol, 4);
643 MCOS->EmitIntValue(0, 4);
646 const MCAsmInfo *asmInfo = context.getAsmInfo();
647 int AddrSize = asmInfo->getPointerSize();
648 // The 1 byte size of an address.
649 MCOS->EmitIntValue(AddrSize, 1);
651 // Second part: the compile_unit DIE.
653 // The DW_TAG_compile_unit DIE abbrev (1).
654 MCOS->EmitULEB128IntValue(1);
656 // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section,
657 // which is at the start of that section so this is zero.
658 if (LineSectionSymbol) {
659 MCOS->EmitSymbolValue(LineSectionSymbol, 4);
661 MCOS->EmitIntValue(0, 4);
664 // AT_low_pc, the first address of the default .text section.
665 const MCExpr *Start = MCSymbolRefExpr::Create(
666 context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
667 MCOS->EmitAbsValue(Start, AddrSize);
669 // AT_high_pc, the last address of the default .text section.
670 const MCExpr *End = MCSymbolRefExpr::Create(
671 context.getGenDwarfSectionEndSym(), MCSymbolRefExpr::VK_None, context);
672 MCOS->EmitAbsValue(End, AddrSize);
674 // AT_name, the name of the source file. Reconstruct from the first directory
675 // and file table entries.
676 const SmallVectorImpl<std::string> &MCDwarfDirs = context.getMCDwarfDirs();
677 if (MCDwarfDirs.size() > 0) {
678 MCOS->EmitBytes(MCDwarfDirs[0]);
679 MCOS->EmitBytes("/");
681 const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles =
682 MCOS->getContext().getMCDwarfFiles();
683 MCOS->EmitBytes(MCDwarfFiles[1].Name);
684 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
686 // AT_comp_dir, the working directory the assembly was done in.
687 if (!context.getCompilationDir().empty()) {
688 MCOS->EmitBytes(context.getCompilationDir());
689 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
692 // AT_APPLE_flags, the command line arguments of the assembler tool.
693 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
694 if (!DwarfDebugFlags.empty()){
695 MCOS->EmitBytes(DwarfDebugFlags);
696 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
699 // AT_producer, the version of the assembler tool.
700 StringRef DwarfDebugProducer = context.getDwarfDebugProducer();
701 if (!DwarfDebugProducer.empty()){
702 MCOS->EmitBytes(DwarfDebugProducer);
705 MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM "));
706 MCOS->EmitBytes(StringRef(PACKAGE_VERSION));
707 MCOS->EmitBytes(StringRef(")"));
709 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
711 // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2
712 // draft has no standard code for assembler.
713 MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2);
715 // Third part: the list of label DIEs.
717 // Loop on saved info for dwarf labels and create the DIEs for them.
718 const std::vector<const MCGenDwarfLabelEntry *> &Entries =
719 MCOS->getContext().getMCGenDwarfLabelEntries();
720 for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it =
721 Entries.begin(), ie = Entries.end(); it != ie;
723 const MCGenDwarfLabelEntry *Entry = *it;
725 // The DW_TAG_label DIE abbrev (2).
726 MCOS->EmitULEB128IntValue(2);
728 // AT_name, of the label without any leading underbar.
729 MCOS->EmitBytes(Entry->getName());
730 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
732 // AT_decl_file, index into the file table.
733 MCOS->EmitIntValue(Entry->getFileNumber(), 4);
735 // AT_decl_line, source line number.
736 MCOS->EmitIntValue(Entry->getLineNumber(), 4);
738 // AT_low_pc, start address of the label.
739 const MCExpr *AT_low_pc = MCSymbolRefExpr::Create(Entry->getLabel(),
740 MCSymbolRefExpr::VK_None, context);
741 MCOS->EmitAbsValue(AT_low_pc, AddrSize);
743 // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype.
744 MCOS->EmitIntValue(0, 1);
746 // The DW_TAG_unspecified_parameters DIE abbrev (3).
747 MCOS->EmitULEB128IntValue(3);
749 // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's.
750 MCOS->EmitIntValue(0, 1);
752 // Deallocate the MCGenDwarfLabelEntry classes that saved away the info
753 // for the dwarf labels.
754 for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it =
755 Entries.begin(), ie = Entries.end(); it != ie;
757 const MCGenDwarfLabelEntry *Entry = *it;
761 // Add the NULL DIE terminating the Compile Unit DIE's.
762 MCOS->EmitIntValue(0, 1);
764 // Now set the value of the symbol at the end of the info section.
765 MCOS->EmitLabel(InfoEnd);
769 // When generating dwarf for assembly source files this emits the Dwarf
772 void MCGenDwarfInfo::Emit(MCStreamer *MCOS, const MCSymbol *LineSectionSymbol) {
773 // Create the dwarf sections in this order (.debug_line already created).
774 MCContext &context = MCOS->getContext();
775 const MCAsmInfo *AsmInfo = context.getAsmInfo();
776 bool CreateDwarfSectionSymbols =
777 AsmInfo->doesDwarfUseRelocationsAcrossSections();
778 if (!CreateDwarfSectionSymbols)
779 LineSectionSymbol = NULL;
780 MCSymbol *AbbrevSectionSymbol = NULL;
781 MCSymbol *InfoSectionSymbol = NULL;
782 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
783 if (CreateDwarfSectionSymbols) {
784 InfoSectionSymbol = context.CreateTempSymbol();
785 MCOS->EmitLabel(InfoSectionSymbol);
787 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
788 if (CreateDwarfSectionSymbols) {
789 AbbrevSectionSymbol = context.CreateTempSymbol();
790 MCOS->EmitLabel(AbbrevSectionSymbol);
792 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
794 // If there are no line table entries then do not emit any section contents.
795 if (!context.hasMCLineSections())
798 // Output the data for .debug_aranges section.
799 EmitGenDwarfAranges(MCOS, InfoSectionSymbol);
801 // Output the data for .debug_abbrev section.
802 EmitGenDwarfAbbrev(MCOS);
804 // Output the data for .debug_info section.
805 EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol);
809 // When generating dwarf for assembly source files this is called when symbol
810 // for a label is created. If this symbol is not a temporary and is in the
811 // section that dwarf is being generated for, save the needed info to create
814 void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
815 SourceMgr &SrcMgr, SMLoc &Loc) {
816 // We won't create dwarf labels for temporary symbols or symbols not in
818 if (Symbol->isTemporary())
820 MCContext &context = MCOS->getContext();
821 if (context.getGenDwarfSection() != MCOS->getCurrentSection().first)
824 // The dwarf label's name does not have the symbol name's leading
826 StringRef Name = Symbol->getName();
827 if (Name.startswith("_"))
828 Name = Name.substr(1, Name.size()-1);
830 // Get the dwarf file number to be used for the dwarf label.
831 unsigned FileNumber = context.getGenDwarfFileNumber();
833 // Finding the line number is the expensive part which is why we just don't
834 // pass it in as for some symbols we won't create a dwarf label.
835 int CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
836 unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
838 // We create a temporary symbol for use for the AT_high_pc and AT_low_pc
839 // values so that they don't have things like an ARM thumb bit from the
840 // original symbol. So when used they won't get a low bit set after
842 MCSymbol *Label = context.CreateTempSymbol();
843 MCOS->EmitLabel(Label);
845 // Create and entry for the info and add it to the other entries.
846 MCGenDwarfLabelEntry *Entry =
847 new MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label);
848 MCOS->getContext().addMCGenDwarfLabelEntry(Entry);
851 static int getDataAlignmentFactor(MCStreamer &streamer) {
852 MCContext &context = streamer.getContext();
853 const MCAsmInfo *asmInfo = context.getAsmInfo();
854 int size = asmInfo->getCalleeSaveStackSlotSize();
855 if (asmInfo->isStackGrowthDirectionUp())
861 static unsigned getSizeForEncoding(MCStreamer &streamer,
862 unsigned symbolEncoding) {
863 MCContext &context = streamer.getContext();
864 unsigned format = symbolEncoding & 0x0f;
866 default: llvm_unreachable("Unknown Encoding");
867 case dwarf::DW_EH_PE_absptr:
868 case dwarf::DW_EH_PE_signed:
869 return context.getAsmInfo()->getPointerSize();
870 case dwarf::DW_EH_PE_udata2:
871 case dwarf::DW_EH_PE_sdata2:
873 case dwarf::DW_EH_PE_udata4:
874 case dwarf::DW_EH_PE_sdata4:
876 case dwarf::DW_EH_PE_udata8:
877 case dwarf::DW_EH_PE_sdata8:
882 static void EmitFDESymbol(MCStreamer &streamer, const MCSymbol &symbol,
883 unsigned symbolEncoding, bool isEH,
884 const char *comment = 0) {
885 MCContext &context = streamer.getContext();
886 const MCAsmInfo *asmInfo = context.getAsmInfo();
887 const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol,
890 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
891 if (streamer.isVerboseAsm() && comment) streamer.AddComment(comment);
892 if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH)
893 streamer.EmitAbsValue(v, size);
895 streamer.EmitValue(v, size);
898 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
899 unsigned symbolEncoding) {
900 MCContext &context = streamer.getContext();
901 const MCAsmInfo *asmInfo = context.getAsmInfo();
902 const MCExpr *v = asmInfo->getExprForPersonalitySymbol(&symbol,
905 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
906 streamer.EmitValue(v, size);
910 class FrameEmitterImpl {
915 const MCSymbol *SectionStart;
917 FrameEmitterImpl(bool usingCFI, bool isEH)
918 : CFAOffset(0), CIENum(0), UsingCFI(usingCFI), IsEH(isEH),
921 void setSectionStart(const MCSymbol *Label) { SectionStart = Label; }
923 /// EmitCompactUnwind - Emit the unwind information in a compact way.
924 void EmitCompactUnwind(MCStreamer &streamer,
925 const MCDwarfFrameInfo &frame);
927 const MCSymbol &EmitCIE(MCStreamer &streamer,
928 const MCSymbol *personality,
929 unsigned personalityEncoding,
930 const MCSymbol *lsda,
932 unsigned lsdaEncoding,
934 MCSymbol *EmitFDE(MCStreamer &streamer,
935 const MCSymbol &cieStart,
936 const MCDwarfFrameInfo &frame);
937 void EmitCFIInstructions(MCStreamer &streamer,
938 ArrayRef<MCCFIInstruction> Instrs,
939 MCSymbol *BaseLabel);
940 void EmitCFIInstruction(MCStreamer &Streamer,
941 const MCCFIInstruction &Instr);
944 } // end anonymous namespace
946 static void EmitEncodingByte(MCStreamer &Streamer, unsigned Encoding,
948 if (Streamer.isVerboseAsm()) {
951 default: EncStr = "<unknown encoding>"; break;
952 case dwarf::DW_EH_PE_absptr: EncStr = "absptr"; break;
953 case dwarf::DW_EH_PE_omit: EncStr = "omit"; break;
954 case dwarf::DW_EH_PE_pcrel: EncStr = "pcrel"; break;
955 case dwarf::DW_EH_PE_udata4: EncStr = "udata4"; break;
956 case dwarf::DW_EH_PE_udata8: EncStr = "udata8"; break;
957 case dwarf::DW_EH_PE_sdata4: EncStr = "sdata4"; break;
958 case dwarf::DW_EH_PE_sdata8: EncStr = "sdata8"; break;
959 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
960 EncStr = "pcrel udata4";
962 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
963 EncStr = "pcrel sdata4";
965 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
966 EncStr = "pcrel udata8";
968 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
969 EncStr = "screl sdata8";
971 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata4:
972 EncStr = "indirect pcrel udata4";
974 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata4:
975 EncStr = "indirect pcrel sdata4";
977 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata8:
978 EncStr = "indirect pcrel udata8";
980 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata8:
981 EncStr = "indirect pcrel sdata8";
985 Streamer.AddComment(Twine(Prefix) + " = " + EncStr);
988 Streamer.EmitIntValue(Encoding, 1);
991 void FrameEmitterImpl::EmitCFIInstruction(MCStreamer &Streamer,
992 const MCCFIInstruction &Instr) {
993 int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
994 bool VerboseAsm = Streamer.isVerboseAsm();
996 switch (Instr.getOperation()) {
997 case MCCFIInstruction::OpRegister: {
998 unsigned Reg1 = Instr.getRegister();
999 unsigned Reg2 = Instr.getRegister2();
1001 Streamer.AddComment("DW_CFA_register");
1002 Streamer.AddComment(Twine("Reg1 ") + Twine(Reg1));
1003 Streamer.AddComment(Twine("Reg2 ") + Twine(Reg2));
1005 Streamer.EmitIntValue(dwarf::DW_CFA_register, 1);
1006 Streamer.EmitULEB128IntValue(Reg1);
1007 Streamer.EmitULEB128IntValue(Reg2);
1010 case MCCFIInstruction::OpWindowSave: {
1011 Streamer.EmitIntValue(dwarf::DW_CFA_GNU_window_save, 1);
1014 case MCCFIInstruction::OpUndefined: {
1015 unsigned Reg = Instr.getRegister();
1017 Streamer.AddComment("DW_CFA_undefined");
1018 Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1020 Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1);
1021 Streamer.EmitULEB128IntValue(Reg);
1024 case MCCFIInstruction::OpAdjustCfaOffset:
1025 case MCCFIInstruction::OpDefCfaOffset: {
1026 const bool IsRelative =
1027 Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset;
1030 Streamer.AddComment("DW_CFA_def_cfa_offset");
1031 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
1034 CFAOffset += Instr.getOffset();
1036 CFAOffset = -Instr.getOffset();
1039 Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
1040 Streamer.EmitULEB128IntValue(CFAOffset);
1044 case MCCFIInstruction::OpDefCfa: {
1046 Streamer.AddComment("DW_CFA_def_cfa");
1047 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
1050 Streamer.AddComment(Twine("Reg ") + Twine(Instr.getRegister()));
1051 Streamer.EmitULEB128IntValue(Instr.getRegister());
1053 CFAOffset = -Instr.getOffset();
1056 Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
1057 Streamer.EmitULEB128IntValue(CFAOffset);
1062 case MCCFIInstruction::OpDefCfaRegister: {
1064 Streamer.AddComment("DW_CFA_def_cfa_register");
1065 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
1068 Streamer.AddComment(Twine("Reg ") + Twine(Instr.getRegister()));
1069 Streamer.EmitULEB128IntValue(Instr.getRegister());
1074 case MCCFIInstruction::OpOffset:
1075 case MCCFIInstruction::OpRelOffset: {
1076 const bool IsRelative =
1077 Instr.getOperation() == MCCFIInstruction::OpRelOffset;
1079 unsigned Reg = Instr.getRegister();
1080 int Offset = Instr.getOffset();
1082 Offset -= CFAOffset;
1083 Offset = Offset / dataAlignmentFactor;
1086 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended_sf");
1087 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
1088 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1089 Streamer.EmitULEB128IntValue(Reg);
1090 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1091 Streamer.EmitSLEB128IntValue(Offset);
1092 } else if (Reg < 64) {
1093 if (VerboseAsm) Streamer.AddComment(Twine("DW_CFA_offset + Reg(") +
1095 Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
1096 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1097 Streamer.EmitULEB128IntValue(Offset);
1099 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended");
1100 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
1101 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1102 Streamer.EmitULEB128IntValue(Reg);
1103 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1104 Streamer.EmitULEB128IntValue(Offset);
1108 case MCCFIInstruction::OpRememberState:
1109 if (VerboseAsm) Streamer.AddComment("DW_CFA_remember_state");
1110 Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
1112 case MCCFIInstruction::OpRestoreState:
1113 if (VerboseAsm) Streamer.AddComment("DW_CFA_restore_state");
1114 Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
1116 case MCCFIInstruction::OpSameValue: {
1117 unsigned Reg = Instr.getRegister();
1118 if (VerboseAsm) Streamer.AddComment("DW_CFA_same_value");
1119 Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
1120 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1121 Streamer.EmitULEB128IntValue(Reg);
1124 case MCCFIInstruction::OpRestore: {
1125 unsigned Reg = Instr.getRegister();
1127 Streamer.AddComment("DW_CFA_restore");
1128 Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1130 Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1);
1133 case MCCFIInstruction::OpEscape:
1134 if (VerboseAsm) Streamer.AddComment("Escape bytes");
1135 Streamer.EmitBytes(Instr.getValues());
1138 llvm_unreachable("Unhandled case in switch");
1141 /// EmitFrameMoves - Emit frame instructions to describe the layout of the
1143 void FrameEmitterImpl::EmitCFIInstructions(MCStreamer &streamer,
1144 ArrayRef<MCCFIInstruction> Instrs,
1145 MCSymbol *BaseLabel) {
1146 for (unsigned i = 0, N = Instrs.size(); i < N; ++i) {
1147 const MCCFIInstruction &Instr = Instrs[i];
1148 MCSymbol *Label = Instr.getLabel();
1149 // Throw out move if the label is invalid.
1150 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
1152 // Advance row if new location.
1153 if (BaseLabel && Label) {
1154 MCSymbol *ThisSym = Label;
1155 if (ThisSym != BaseLabel) {
1156 if (streamer.isVerboseAsm()) streamer.AddComment("DW_CFA_advance_loc4");
1157 streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
1158 BaseLabel = ThisSym;
1162 EmitCFIInstruction(streamer, Instr);
1166 /// EmitCompactUnwind - Emit the unwind information in a compact way.
1167 void FrameEmitterImpl::EmitCompactUnwind(MCStreamer &Streamer,
1168 const MCDwarfFrameInfo &Frame) {
1169 MCContext &Context = Streamer.getContext();
1170 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1171 bool VerboseAsm = Streamer.isVerboseAsm();
1173 // range-start range-length compact-unwind-enc personality-func lsda
1174 // _foo LfooEnd-_foo 0x00000023 0 0
1175 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1
1177 // .section __LD,__compact_unwind,regular,debug
1179 // # compact unwind for _foo
1181 // .set L1,LfooEnd-_foo
1187 // # compact unwind for _bar
1189 // .set L2,LbarEnd-_bar
1192 // .quad __gxx_personality
1193 // .quad except_tab1
1195 uint32_t Encoding = Frame.CompactUnwindEncoding;
1196 if (!Encoding) return;
1197 bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly());
1199 // The encoding needs to know we have an LSDA.
1200 if (!DwarfEHFrameOnly && Frame.Lsda)
1201 Encoding |= 0x40000000;
1204 unsigned FDEEncoding = MOFI->getFDEEncoding(UsingCFI);
1205 unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
1206 if (VerboseAsm) Streamer.AddComment("Range Start");
1207 Streamer.EmitSymbolValue(Frame.Function, Size);
1210 const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin,
1212 if (VerboseAsm) Streamer.AddComment("Range Length");
1213 Streamer.EmitAbsValue(Range, 4);
1216 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
1217 if (VerboseAsm) Streamer.AddComment("Compact Unwind Encoding: 0x" +
1218 Twine::utohexstr(Encoding));
1219 Streamer.EmitIntValue(Encoding, Size);
1221 // Personality Function
1222 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
1223 if (VerboseAsm) Streamer.AddComment("Personality Function");
1224 if (!DwarfEHFrameOnly && Frame.Personality)
1225 Streamer.EmitSymbolValue(Frame.Personality, Size);
1227 Streamer.EmitIntValue(0, Size); // No personality fn
1230 Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
1231 if (VerboseAsm) Streamer.AddComment("LSDA");
1232 if (!DwarfEHFrameOnly && Frame.Lsda)
1233 Streamer.EmitSymbolValue(Frame.Lsda, Size);
1235 Streamer.EmitIntValue(0, Size); // No LSDA
1238 const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
1239 const MCSymbol *personality,
1240 unsigned personalityEncoding,
1241 const MCSymbol *lsda,
1243 unsigned lsdaEncoding,
1245 MCContext &context = streamer.getContext();
1246 const MCRegisterInfo *MRI = context.getRegisterInfo();
1247 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1248 bool verboseAsm = streamer.isVerboseAsm();
1250 MCSymbol *sectionStart;
1251 if (MOFI->isFunctionEHFrameSymbolPrivate() || !IsEH)
1252 sectionStart = context.CreateTempSymbol();
1254 sectionStart = context.GetOrCreateSymbol(Twine("EH_frame") + Twine(CIENum));
1256 streamer.EmitLabel(sectionStart);
1259 MCSymbol *sectionEnd = context.CreateTempSymbol();
1262 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *sectionStart,
1264 if (verboseAsm) streamer.AddComment("CIE Length");
1265 streamer.EmitAbsValue(Length, 4);
1268 unsigned CIE_ID = IsEH ? 0 : -1;
1269 if (verboseAsm) streamer.AddComment("CIE ID Tag");
1270 streamer.EmitIntValue(CIE_ID, 4);
1273 if (verboseAsm) streamer.AddComment("DW_CIE_VERSION");
1274 streamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1);
1276 // Augmentation String
1277 SmallString<8> Augmentation;
1279 if (verboseAsm) streamer.AddComment("CIE Augmentation");
1280 Augmentation += "z";
1282 Augmentation += "P";
1284 Augmentation += "L";
1285 Augmentation += "R";
1287 Augmentation += "S";
1288 streamer.EmitBytes(Augmentation.str());
1290 streamer.EmitIntValue(0, 1);
1292 // Code Alignment Factor
1293 if (verboseAsm) streamer.AddComment("CIE Code Alignment Factor");
1294 streamer.EmitULEB128IntValue(context.getAsmInfo()->getMinInstAlignment());
1296 // Data Alignment Factor
1297 if (verboseAsm) streamer.AddComment("CIE Data Alignment Factor");
1298 streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer));
1300 // Return Address Register
1301 if (verboseAsm) streamer.AddComment("CIE Return Address Column");
1302 streamer.EmitULEB128IntValue(MRI->getDwarfRegNum(MRI->getRARegister(), true));
1304 // Augmentation Data Length (optional)
1306 unsigned augmentationLength = 0;
1309 // Personality Encoding
1310 augmentationLength += 1;
1312 augmentationLength += getSizeForEncoding(streamer, personalityEncoding);
1315 augmentationLength += 1;
1316 // Encoding of the FDE pointers
1317 augmentationLength += 1;
1319 if (verboseAsm) streamer.AddComment("Augmentation Size");
1320 streamer.EmitULEB128IntValue(augmentationLength);
1322 // Augmentation Data (optional)
1324 // Personality Encoding
1325 EmitEncodingByte(streamer, personalityEncoding,
1326 "Personality Encoding");
1328 if (verboseAsm) streamer.AddComment("Personality");
1329 EmitPersonality(streamer, *personality, personalityEncoding);
1333 EmitEncodingByte(streamer, lsdaEncoding, "LSDA Encoding");
1335 // Encoding of the FDE pointers
1336 EmitEncodingByte(streamer, MOFI->getFDEEncoding(UsingCFI),
1340 // Initial Instructions
1342 const MCAsmInfo *MAI = context.getAsmInfo();
1344 const std::vector<MCCFIInstruction> &Instructions =
1345 MAI->getInitialFrameState();
1346 EmitCFIInstructions(streamer, Instructions, NULL);
1350 streamer.EmitValueToAlignment(IsEH ? 4 : MAI->getPointerSize());
1352 streamer.EmitLabel(sectionEnd);
1353 return *sectionStart;
1356 MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
1357 const MCSymbol &cieStart,
1358 const MCDwarfFrameInfo &frame) {
1359 MCContext &context = streamer.getContext();
1360 MCSymbol *fdeStart = context.CreateTempSymbol();
1361 MCSymbol *fdeEnd = context.CreateTempSymbol();
1362 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1363 bool verboseAsm = streamer.isVerboseAsm();
1365 if (IsEH && frame.Function && !MOFI->isFunctionEHFrameSymbolPrivate()) {
1367 context.GetOrCreateSymbol(frame.Function->getName() + Twine(".eh"));
1368 streamer.EmitEHSymAttributes(frame.Function, EHSym);
1369 streamer.EmitLabel(EHSym);
1373 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *fdeStart, *fdeEnd, 0);
1374 if (verboseAsm) streamer.AddComment("FDE Length");
1375 streamer.EmitAbsValue(Length, 4);
1377 streamer.EmitLabel(fdeStart);
1380 const MCAsmInfo *asmInfo = context.getAsmInfo();
1382 const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart,
1384 if (verboseAsm) streamer.AddComment("FDE CIE Offset");
1385 streamer.EmitAbsValue(offset, 4);
1386 } else if (!asmInfo->doesDwarfUseRelocationsAcrossSections()) {
1387 const MCExpr *offset = MakeStartMinusEndExpr(streamer, *SectionStart,
1389 streamer.EmitAbsValue(offset, 4);
1391 streamer.EmitSymbolValue(&cieStart, 4);
1395 unsigned PCEncoding = IsEH ? MOFI->getFDEEncoding(UsingCFI)
1396 : (unsigned)dwarf::DW_EH_PE_absptr;
1397 unsigned PCSize = getSizeForEncoding(streamer, PCEncoding);
1398 EmitFDESymbol(streamer, *frame.Begin, PCEncoding, IsEH, "FDE initial location");
1401 const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin,
1403 if (verboseAsm) streamer.AddComment("FDE address range");
1404 streamer.EmitAbsValue(Range, PCSize);
1407 // Augmentation Data Length
1408 unsigned augmentationLength = 0;
1411 augmentationLength += getSizeForEncoding(streamer, frame.LsdaEncoding);
1413 if (verboseAsm) streamer.AddComment("Augmentation size");
1414 streamer.EmitULEB128IntValue(augmentationLength);
1416 // Augmentation Data
1418 EmitFDESymbol(streamer, *frame.Lsda, frame.LsdaEncoding, true,
1419 "Language Specific Data Area");
1422 // Call Frame Instructions
1423 EmitCFIInstructions(streamer, frame.Instructions, frame.Begin);
1426 streamer.EmitValueToAlignment(PCSize);
1433 static const CIEKey getEmptyKey() { return CIEKey(0, 0, -1, false, false); }
1434 static const CIEKey getTombstoneKey() { return CIEKey(0, -1, 0, false, false); }
1436 CIEKey(const MCSymbol* Personality_, unsigned PersonalityEncoding_,
1437 unsigned LsdaEncoding_, bool IsSignalFrame_, bool IsSimple_) :
1438 Personality(Personality_), PersonalityEncoding(PersonalityEncoding_),
1439 LsdaEncoding(LsdaEncoding_), IsSignalFrame(IsSignalFrame_),
1440 IsSimple(IsSimple_) {
1442 const MCSymbol* Personality;
1443 unsigned PersonalityEncoding;
1444 unsigned LsdaEncoding;
1452 struct DenseMapInfo<CIEKey> {
1453 static CIEKey getEmptyKey() {
1454 return CIEKey::getEmptyKey();
1456 static CIEKey getTombstoneKey() {
1457 return CIEKey::getTombstoneKey();
1459 static unsigned getHashValue(const CIEKey &Key) {
1460 return static_cast<unsigned>(hash_combine(Key.Personality,
1461 Key.PersonalityEncoding,
1466 static bool isEqual(const CIEKey &LHS,
1467 const CIEKey &RHS) {
1468 return LHS.Personality == RHS.Personality &&
1469 LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
1470 LHS.LsdaEncoding == RHS.LsdaEncoding &&
1471 LHS.IsSignalFrame == RHS.IsSignalFrame &&
1472 LHS.IsSimple == RHS.IsSimple;
1477 void MCDwarfFrameEmitter::Emit(MCStreamer &Streamer, MCAsmBackend *MAB,
1478 bool UsingCFI, bool IsEH) {
1479 Streamer.generateCompactUnwindEncodings(MAB);
1481 MCContext &Context = Streamer.getContext();
1482 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1483 FrameEmitterImpl Emitter(UsingCFI, IsEH);
1484 ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getFrameInfos();
1486 // Emit the compact unwind info if available.
1487 if (IsEH && MOFI->getCompactUnwindSection()) {
1488 bool SectionEmitted = false;
1489 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
1490 const MCDwarfFrameInfo &Frame = FrameArray[i];
1491 if (Frame.CompactUnwindEncoding == 0) continue;
1492 if (!SectionEmitted) {
1493 Streamer.SwitchSection(MOFI->getCompactUnwindSection());
1494 Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize());
1495 SectionEmitted = true;
1497 Emitter.EmitCompactUnwind(Streamer, Frame);
1501 const MCSection &Section =
1502 IsEH ? *const_cast<MCObjectFileInfo*>(MOFI)->getEHFrameSection() :
1503 *MOFI->getDwarfFrameSection();
1504 Streamer.SwitchSection(&Section);
1505 MCSymbol *SectionStart = Context.CreateTempSymbol();
1506 Streamer.EmitLabel(SectionStart);
1507 Emitter.setSectionStart(SectionStart);
1509 MCSymbol *FDEEnd = NULL;
1510 DenseMap<CIEKey, const MCSymbol*> CIEStarts;
1512 const MCSymbol *DummyDebugKey = NULL;
1513 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
1514 const MCDwarfFrameInfo &Frame = FrameArray[i];
1515 CIEKey Key(Frame.Personality, Frame.PersonalityEncoding,
1516 Frame.LsdaEncoding, Frame.IsSignalFrame, Frame.IsSimple);
1517 const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
1519 CIEStart = &Emitter.EmitCIE(Streamer, Frame.Personality,
1520 Frame.PersonalityEncoding, Frame.Lsda,
1521 Frame.IsSignalFrame,
1525 FDEEnd = Emitter.EmitFDE(Streamer, *CIEStart, Frame);
1528 Streamer.EmitLabel(FDEEnd);
1531 Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize());
1533 Streamer.EmitLabel(FDEEnd);
1536 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCStreamer &Streamer,
1537 uint64_t AddrDelta) {
1538 MCContext &Context = Streamer.getContext();
1539 SmallString<256> Tmp;
1540 raw_svector_ostream OS(Tmp);
1541 MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OS);
1542 Streamer.EmitBytes(OS.str());
1545 void MCDwarfFrameEmitter::EncodeAdvanceLoc(MCContext &Context,
1548 // Scale the address delta by the minimum instruction length.
1549 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
1551 if (AddrDelta == 0) {
1552 } else if (isUIntN(6, AddrDelta)) {
1553 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
1555 } else if (isUInt<8>(AddrDelta)) {
1556 OS << uint8_t(dwarf::DW_CFA_advance_loc1);
1557 OS << uint8_t(AddrDelta);
1558 } else if (isUInt<16>(AddrDelta)) {
1559 // FIXME: check what is the correct behavior on a big endian machine.
1560 OS << uint8_t(dwarf::DW_CFA_advance_loc2);
1561 OS << uint8_t( AddrDelta & 0xff);
1562 OS << uint8_t((AddrDelta >> 8) & 0xff);
1564 // FIXME: check what is the correct behavior on a big endian machine.
1565 assert(isUInt<32>(AddrDelta));
1566 OS << uint8_t(dwarf::DW_CFA_advance_loc4);
1567 OS << uint8_t( AddrDelta & 0xff);
1568 OS << uint8_t((AddrDelta >> 8) & 0xff);
1569 OS << uint8_t((AddrDelta >> 16) & 0xff);
1570 OS << uint8_t((AddrDelta >> 24) & 0xff);