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/MC/MCAsmInfo.h"
12 #include "llvm/MC/MCContext.h"
13 #include "llvm/MC/MCObjectFileInfo.h"
14 #include "llvm/MC/MCObjectWriter.h"
15 #include "llvm/MC/MCRegisterInfo.h"
16 #include "llvm/MC/MCStreamer.h"
17 #include "llvm/MC/MCSymbol.h"
18 #include "llvm/MC/MCExpr.h"
19 #include "llvm/Support/Debug.h"
20 #include "llvm/Support/ErrorHandling.h"
21 #include "llvm/Support/raw_ostream.h"
22 #include "llvm/Support/LEB128.h"
23 #include "llvm/Support/Path.h"
24 #include "llvm/Support/SourceMgr.h"
25 #include "llvm/ADT/Hashing.h"
26 #include "llvm/ADT/SmallString.h"
27 #include "llvm/ADT/Twine.h"
28 #include "llvm/Config/config.h"
31 // Given a special op, return the address skip amount (in units of
32 // DWARF2_LINE_MIN_INSN_LENGTH.
33 #define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE)
35 // The maximum address skip amount that can be encoded with a special op.
36 #define MAX_SPECIAL_ADDR_DELTA SPECIAL_ADDR(255)
38 // First special line opcode - leave room for the standard opcodes.
39 // Note: If you want to change this, you'll have to update the
40 // "standard_opcode_lengths" table that is emitted in DwarfFileTable::Emit().
41 #define DWARF2_LINE_OPCODE_BASE 13
43 // Minimum line offset in a special line info. opcode. This value
44 // was chosen to give a reasonable range of values.
45 #define DWARF2_LINE_BASE -5
47 // Range of line offsets in a special line info. opcode.
48 #define DWARF2_LINE_RANGE 14
50 // Define the architecture-dependent minimum instruction length (in bytes).
51 // This value should be rather too small than too big.
52 #define DWARF2_LINE_MIN_INSN_LENGTH 1
54 // Note: when DWARF2_LINE_MIN_INSN_LENGTH == 1 which is the current setting,
55 // this routine is a nop and will be optimized away.
56 static inline uint64_t ScaleAddrDelta(uint64_t AddrDelta) {
57 if (DWARF2_LINE_MIN_INSN_LENGTH == 1)
59 if (AddrDelta % DWARF2_LINE_MIN_INSN_LENGTH != 0) {
60 // TODO: report this error, but really only once.
63 return AddrDelta / DWARF2_LINE_MIN_INSN_LENGTH;
67 // This is called when an instruction is assembled into the specified section
68 // and if there is information from the last .loc directive that has yet to have
69 // a line entry made for it is made.
71 void MCLineEntry::Make(MCStreamer *MCOS, const MCSection *Section) {
72 if (!MCOS->getContext().getDwarfLocSeen())
75 // Create a symbol at in the current section for use in the line entry.
76 MCSymbol *LineSym = MCOS->getContext().CreateTempSymbol();
77 // Set the value of the symbol to use for the MCLineEntry.
78 MCOS->EmitLabel(LineSym);
80 // Get the current .loc info saved in the context.
81 const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();
83 // Create a (local) line entry with the symbol and the current .loc info.
84 MCLineEntry LineEntry(LineSym, DwarfLoc);
86 // clear DwarfLocSeen saying the current .loc info is now used.
87 MCOS->getContext().ClearDwarfLocSeen();
89 // Get the MCLineSection for this section, if one does not exist for this
91 const DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
92 MCOS->getContext().getMCLineSections();
93 MCLineSection *LineSection = MCLineSections.lookup(Section);
95 // Create a new MCLineSection. This will be deleted after the dwarf line
96 // table is created using it by iterating through the MCLineSections
98 LineSection = new MCLineSection;
99 // Save a pointer to the new LineSection into the MCLineSections DenseMap.
100 MCOS->getContext().addMCLineSection(Section, LineSection);
103 // Add the line entry to this section's entries.
104 LineSection->addLineEntry(LineEntry);
108 // This helper routine returns an expression of End - Start + IntVal .
110 static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS,
111 const MCSymbol &Start,
114 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
116 MCSymbolRefExpr::Create(&End, Variant, MCOS.getContext());
118 MCSymbolRefExpr::Create(&Start, Variant, MCOS.getContext());
120 MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext());
122 MCConstantExpr::Create(IntVal, MCOS.getContext());
124 MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext());
129 // This emits the Dwarf line table for the specified section from the entries
130 // in the LineSection.
132 static inline void EmitDwarfLineTable(MCStreamer *MCOS,
133 const MCSection *Section,
134 const MCLineSection *LineSection) {
135 unsigned FileNum = 1;
136 unsigned LastLine = 1;
138 unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
140 MCSymbol *LastLabel = NULL;
142 // Loop through each MCLineEntry and encode the dwarf line number table.
143 for (MCLineSection::const_iterator
144 it = LineSection->getMCLineEntries()->begin(),
145 ie = LineSection->getMCLineEntries()->end(); it != ie; ++it) {
147 if (FileNum != it->getFileNum()) {
148 FileNum = it->getFileNum();
149 MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
150 MCOS->EmitULEB128IntValue(FileNum);
152 if (Column != it->getColumn()) {
153 Column = it->getColumn();
154 MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
155 MCOS->EmitULEB128IntValue(Column);
157 if (Isa != it->getIsa()) {
159 MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
160 MCOS->EmitULEB128IntValue(Isa);
162 if ((it->getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
163 Flags = it->getFlags();
164 MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
166 if (it->getFlags() & DWARF2_FLAG_BASIC_BLOCK)
167 MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
168 if (it->getFlags() & DWARF2_FLAG_PROLOGUE_END)
169 MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
170 if (it->getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
171 MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
173 int64_t LineDelta = static_cast<int64_t>(it->getLine()) - LastLine;
174 MCSymbol *Label = it->getLabel();
176 // At this point we want to emit/create the sequence to encode the delta in
177 // line numbers and the increment of the address from the previous Label
178 // and the current Label.
179 const MCAsmInfo &asmInfo = MCOS->getContext().getAsmInfo();
180 MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label,
181 asmInfo.getPointerSize());
183 LastLine = it->getLine();
187 // Emit a DW_LNE_end_sequence for the end of the section.
188 // Using the pointer Section create a temporary label at the end of the
189 // section and use that and the LastLabel to compute the address delta
190 // and use INT64_MAX as the line delta which is the signal that this is
191 // actually a DW_LNE_end_sequence.
193 // Switch to the section to be able to create a symbol at its end.
194 MCOS->SwitchSection(Section);
196 MCContext &context = MCOS->getContext();
197 // Create a symbol at the end of the section.
198 MCSymbol *SectionEnd = context.CreateTempSymbol();
199 // Set the value of the symbol, as we are at the end of the section.
200 MCOS->EmitLabel(SectionEnd);
202 // Switch back the dwarf line section.
203 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
205 const MCAsmInfo &asmInfo = MCOS->getContext().getAsmInfo();
206 MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd,
207 asmInfo.getPointerSize());
211 // This emits the Dwarf file and the line tables.
213 const MCSymbol *MCDwarfFileTable::Emit(MCStreamer *MCOS) {
214 MCContext &context = MCOS->getContext();
215 // Switch to the section where the table will be emitted into.
216 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
218 // Create a symbol at the beginning of this section.
219 MCSymbol *LineStartSym = context.CreateTempSymbol();
220 // Set the value of the symbol, as we are at the start of the section.
221 MCOS->EmitLabel(LineStartSym);
223 // Create a symbol for the end of the section (to be set when we get there).
224 MCSymbol *LineEndSym = context.CreateTempSymbol();
226 // The first 4 bytes is the total length of the information for this
227 // compilation unit (not including these 4 bytes for the length).
228 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym,4),
231 // Next 2 bytes is the Version, which is Dwarf 2.
232 MCOS->EmitIntValue(2, 2);
234 // Create a symbol for the end of the prologue (to be set when we get there).
235 MCSymbol *ProEndSym = context.CreateTempSymbol(); // Lprologue_end
237 // Length of the prologue, is the next 4 bytes. Which is the start of the
238 // section to the end of the prologue. Not including the 4 bytes for the
239 // total length, the 2 bytes for the version, and these 4 bytes for the
240 // length of the prologue.
241 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym,
245 // Parameters of the state machine, are next.
246 MCOS->EmitIntValue(DWARF2_LINE_MIN_INSN_LENGTH, 1);
247 MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
248 MCOS->EmitIntValue(DWARF2_LINE_BASE, 1);
249 MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1);
250 MCOS->EmitIntValue(DWARF2_LINE_OPCODE_BASE, 1);
252 // Standard opcode lengths
253 MCOS->EmitIntValue(0, 1); // length of DW_LNS_copy
254 MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_pc
255 MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_line
256 MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_file
257 MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_column
258 MCOS->EmitIntValue(0, 1); // length of DW_LNS_negate_stmt
259 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_basic_block
260 MCOS->EmitIntValue(0, 1); // length of DW_LNS_const_add_pc
261 MCOS->EmitIntValue(1, 1); // length of DW_LNS_fixed_advance_pc
262 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_prologue_end
263 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_epilogue_begin
264 MCOS->EmitIntValue(1, 1); // DW_LNS_set_isa
266 // Put out the directory and file tables.
268 // First the directory table.
269 const std::vector<StringRef> &MCDwarfDirs =
270 context.getMCDwarfDirs();
271 for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
272 MCOS->EmitBytes(MCDwarfDirs[i], 0); // the DirectoryName
273 MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string
275 MCOS->EmitIntValue(0, 1); // Terminate the directory list
277 // Second the file table.
278 const std::vector<MCDwarfFile *> &MCDwarfFiles =
279 MCOS->getContext().getMCDwarfFiles();
280 for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
281 MCOS->EmitBytes(MCDwarfFiles[i]->getName(), 0); // FileName
282 MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string
284 MCOS->EmitULEB128IntValue(MCDwarfFiles[i]->getDirIndex());
285 MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
286 MCOS->EmitIntValue(0, 1); // filesize (always 0)
288 MCOS->EmitIntValue(0, 1); // Terminate the file list
290 // This is the end of the prologue, so set the value of the symbol at the
291 // end of the prologue (that was used in a previous expression).
292 MCOS->EmitLabel(ProEndSym);
294 // Put out the line tables.
295 const DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
296 MCOS->getContext().getMCLineSections();
297 const std::vector<const MCSection *> &MCLineSectionOrder =
298 MCOS->getContext().getMCLineSectionOrder();
299 for (std::vector<const MCSection*>::const_iterator it =
300 MCLineSectionOrder.begin(), ie = MCLineSectionOrder.end(); it != ie;
302 const MCSection *Sec = *it;
303 const MCLineSection *Line = MCLineSections.lookup(Sec);
304 EmitDwarfLineTable(MCOS, Sec, Line);
306 // Now delete the MCLineSections that were created in MCLineEntry::Make()
307 // and used to emit the line table.
311 if (MCOS->getContext().getAsmInfo().getLinkerRequiresNonEmptyDwarfLines()
312 && MCLineSectionOrder.begin() == MCLineSectionOrder.end()) {
313 // The darwin9 linker has a bug (see PR8715). For for 32-bit architectures
315 // total_length >= prologue_length + 10
316 // We are 4 bytes short, since we have total_length = 51 and
317 // prologue_length = 45
319 // The regular end_sequence should be sufficient.
320 MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
323 // This is the end of the section, so set the value of the symbol at the end
324 // of this section (that was used in a previous expression).
325 MCOS->EmitLabel(LineEndSym);
330 /// Utility function to write the encoding to an object writer.
331 void MCDwarfLineAddr::Write(MCObjectWriter *OW, int64_t LineDelta,
332 uint64_t AddrDelta) {
333 SmallString<256> Tmp;
334 raw_svector_ostream OS(Tmp);
335 MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
336 OW->WriteBytes(OS.str());
339 /// Utility function to emit the encoding to a streamer.
340 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta,
341 uint64_t AddrDelta) {
342 SmallString<256> Tmp;
343 raw_svector_ostream OS(Tmp);
344 MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
345 MCOS->EmitBytes(OS.str(), /*AddrSpace=*/0);
348 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
349 void MCDwarfLineAddr::Encode(int64_t LineDelta, uint64_t AddrDelta,
351 uint64_t Temp, Opcode;
352 bool NeedCopy = false;
354 // Scale the address delta by the minimum instruction length.
355 AddrDelta = ScaleAddrDelta(AddrDelta);
357 // A LineDelta of INT64_MAX is a signal that this is actually a
358 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
359 // end_sequence to emit the matrix entry.
360 if (LineDelta == INT64_MAX) {
361 if (AddrDelta == MAX_SPECIAL_ADDR_DELTA)
362 OS << char(dwarf::DW_LNS_const_add_pc);
364 OS << char(dwarf::DW_LNS_advance_pc);
365 encodeULEB128(AddrDelta, OS);
367 OS << char(dwarf::DW_LNS_extended_op);
369 OS << char(dwarf::DW_LNE_end_sequence);
373 // Bias the line delta by the base.
374 Temp = LineDelta - DWARF2_LINE_BASE;
376 // If the line increment is out of range of a special opcode, we must encode
377 // it with DW_LNS_advance_line.
378 if (Temp >= DWARF2_LINE_RANGE) {
379 OS << char(dwarf::DW_LNS_advance_line);
380 encodeSLEB128(LineDelta, OS);
383 Temp = 0 - DWARF2_LINE_BASE;
387 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
388 if (LineDelta == 0 && AddrDelta == 0) {
389 OS << char(dwarf::DW_LNS_copy);
393 // Bias the opcode by the special opcode base.
394 Temp += DWARF2_LINE_OPCODE_BASE;
396 // Avoid overflow when addr_delta is large.
397 if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) {
398 // Try using a special opcode.
399 Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE;
405 // Try using DW_LNS_const_add_pc followed by special op.
406 Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
408 OS << char(dwarf::DW_LNS_const_add_pc);
414 // Otherwise use DW_LNS_advance_pc.
415 OS << char(dwarf::DW_LNS_advance_pc);
416 encodeULEB128(AddrDelta, OS);
419 OS << char(dwarf::DW_LNS_copy);
424 void MCDwarfFile::print(raw_ostream &OS) const {
425 OS << '"' << getName() << '"';
428 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
429 void MCDwarfFile::dump() const {
434 // Utility function to write a tuple for .debug_abbrev.
435 static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) {
436 MCOS->EmitULEB128IntValue(Name);
437 MCOS->EmitULEB128IntValue(Form);
440 // When generating dwarf for assembly source files this emits
441 // the data for .debug_abbrev section which contains three DIEs.
442 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
443 MCContext &context = MCOS->getContext();
444 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
446 // DW_TAG_compile_unit DIE abbrev (1).
447 MCOS->EmitULEB128IntValue(1);
448 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit);
449 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
450 EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4);
451 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
452 EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
453 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
454 EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
455 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
456 if (!DwarfDebugFlags.empty())
457 EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
458 EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string);
459 EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2);
460 EmitAbbrev(MCOS, 0, 0);
462 // DW_TAG_label DIE abbrev (2).
463 MCOS->EmitULEB128IntValue(2);
464 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_label);
465 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
466 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
467 EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);
468 EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);
469 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
470 EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag);
471 EmitAbbrev(MCOS, 0, 0);
473 // DW_TAG_unspecified_parameters DIE abbrev (3).
474 MCOS->EmitULEB128IntValue(3);
475 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters);
476 MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1);
477 EmitAbbrev(MCOS, 0, 0);
479 // Terminate the abbreviations for this compilation unit.
480 MCOS->EmitIntValue(0, 1);
483 // When generating dwarf for assembly source files this emits the data for
484 // .debug_aranges section. Which contains a header and a table of pairs of
485 // PointerSize'ed values for the address and size of section(s) with line table
486 // entries (just the default .text in our case) and a terminating pair of zeros.
487 static void EmitGenDwarfAranges(MCStreamer *MCOS,
488 const MCSymbol *InfoSectionSymbol) {
489 MCContext &context = MCOS->getContext();
491 // Create a symbol at the end of the section that we are creating the dwarf
492 // debugging info to use later in here as part of the expression to calculate
493 // the size of the section for the table.
494 MCOS->SwitchSection(context.getGenDwarfSection());
495 MCSymbol *SectionEndSym = context.CreateTempSymbol();
496 MCOS->EmitLabel(SectionEndSym);
497 context.setGenDwarfSectionEndSym(SectionEndSym);
499 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
501 // This will be the length of the .debug_aranges section, first account for
502 // the size of each item in the header (see below where we emit these items).
503 int Length = 4 + 2 + 4 + 1 + 1;
505 // Figure the padding after the header before the table of address and size
506 // pairs who's values are PointerSize'ed.
507 const MCAsmInfo &asmInfo = context.getAsmInfo();
508 int AddrSize = asmInfo.getPointerSize();
509 int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1));
510 if (Pad == 2 * AddrSize)
514 // Add the size of the pair of PointerSize'ed values for the address and size
515 // of the one default .text section we have in the table.
516 Length += 2 * AddrSize;
517 // And the pair of terminating zeros.
518 Length += 2 * AddrSize;
521 // Emit the header for this section.
522 // The 4 byte length not including the 4 byte value for the length.
523 MCOS->EmitIntValue(Length - 4, 4);
524 // The 2 byte version, which is 2.
525 MCOS->EmitIntValue(2, 2);
526 // The 4 byte offset to the compile unit in the .debug_info from the start
527 // of the .debug_info.
528 if (InfoSectionSymbol)
529 MCOS->EmitSymbolValue(InfoSectionSymbol, 4);
531 MCOS->EmitIntValue(0, 4);
532 // The 1 byte size of an address.
533 MCOS->EmitIntValue(AddrSize, 1);
534 // The 1 byte size of a segment descriptor, we use a value of zero.
535 MCOS->EmitIntValue(0, 1);
536 // Align the header with the padding if needed, before we put out the table.
537 for(int i = 0; i < Pad; i++)
538 MCOS->EmitIntValue(0, 1);
540 // Now emit the table of pairs of PointerSize'ed values for the section(s)
541 // address and size, in our case just the one default .text section.
542 const MCExpr *Addr = MCSymbolRefExpr::Create(
543 context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
544 const MCExpr *Size = MakeStartMinusEndExpr(*MCOS,
545 *context.getGenDwarfSectionStartSym(), *SectionEndSym, 0);
546 MCOS->EmitAbsValue(Addr, AddrSize);
547 MCOS->EmitAbsValue(Size, AddrSize);
549 // And finally the pair of terminating zeros.
550 MCOS->EmitIntValue(0, AddrSize);
551 MCOS->EmitIntValue(0, AddrSize);
554 // When generating dwarf for assembly source files this emits the data for
555 // .debug_info section which contains three parts. The header, the compile_unit
556 // DIE and a list of label DIEs.
557 static void EmitGenDwarfInfo(MCStreamer *MCOS,
558 const MCSymbol *AbbrevSectionSymbol,
559 const MCSymbol *LineSectionSymbol) {
560 MCContext &context = MCOS->getContext();
562 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
564 // Create a symbol at the start and end of this section used in here for the
565 // expression to calculate the length in the header.
566 MCSymbol *InfoStart = context.CreateTempSymbol();
567 MCOS->EmitLabel(InfoStart);
568 MCSymbol *InfoEnd = context.CreateTempSymbol();
570 // First part: the header.
572 // The 4 byte total length of the information for this compilation unit, not
573 // including these 4 bytes.
574 const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4);
575 MCOS->EmitAbsValue(Length, 4);
577 // The 2 byte DWARF version, which is 2.
578 MCOS->EmitIntValue(2, 2);
580 // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev,
581 // it is at the start of that section so this is zero.
582 if (AbbrevSectionSymbol) {
583 MCOS->EmitSymbolValue(AbbrevSectionSymbol, 4);
585 MCOS->EmitIntValue(0, 4);
588 const MCAsmInfo &asmInfo = context.getAsmInfo();
589 int AddrSize = asmInfo.getPointerSize();
590 // The 1 byte size of an address.
591 MCOS->EmitIntValue(AddrSize, 1);
593 // Second part: the compile_unit DIE.
595 // The DW_TAG_compile_unit DIE abbrev (1).
596 MCOS->EmitULEB128IntValue(1);
598 // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section,
599 // which is at the start of that section so this is zero.
600 if (LineSectionSymbol) {
601 MCOS->EmitSymbolValue(LineSectionSymbol, 4);
603 MCOS->EmitIntValue(0, 4);
606 // AT_low_pc, the first address of the default .text section.
607 const MCExpr *Start = MCSymbolRefExpr::Create(
608 context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
609 MCOS->EmitAbsValue(Start, AddrSize);
611 // AT_high_pc, the last address of the default .text section.
612 const MCExpr *End = MCSymbolRefExpr::Create(
613 context.getGenDwarfSectionEndSym(), MCSymbolRefExpr::VK_None, context);
614 MCOS->EmitAbsValue(End, AddrSize);
616 // AT_name, the name of the source file. Reconstruct from the first directory
617 // and file table entries.
618 const std::vector<StringRef> &MCDwarfDirs =
619 context.getMCDwarfDirs();
620 if (MCDwarfDirs.size() > 0) {
621 MCOS->EmitBytes(MCDwarfDirs[0], 0);
622 MCOS->EmitBytes("/", 0);
624 const std::vector<MCDwarfFile *> &MCDwarfFiles =
625 MCOS->getContext().getMCDwarfFiles();
626 MCOS->EmitBytes(MCDwarfFiles[1]->getName(), 0);
627 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
629 // AT_comp_dir, the working directory the assembly was done in.
630 llvm::sys::Path CWD = llvm::sys::Path::GetCurrentDirectory();
631 MCOS->EmitBytes(StringRef(CWD.c_str()), 0);
632 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
634 // AT_APPLE_flags, the command line arguments of the assembler tool.
635 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
636 if (!DwarfDebugFlags.empty()){
637 MCOS->EmitBytes(DwarfDebugFlags, 0);
638 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
641 // AT_producer, the version of the assembler tool.
642 MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM "), 0);
643 MCOS->EmitBytes(StringRef(PACKAGE_VERSION), 0);
644 MCOS->EmitBytes(StringRef(")"), 0);
645 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
647 // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2
648 // draft has no standard code for assembler.
649 MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2);
651 // Third part: the list of label DIEs.
653 // Loop on saved info for dwarf labels and create the DIEs for them.
654 const std::vector<const MCGenDwarfLabelEntry *> &Entries =
655 MCOS->getContext().getMCGenDwarfLabelEntries();
656 for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it =
657 Entries.begin(), ie = Entries.end(); it != ie;
659 const MCGenDwarfLabelEntry *Entry = *it;
661 // The DW_TAG_label DIE abbrev (2).
662 MCOS->EmitULEB128IntValue(2);
664 // AT_name, of the label without any leading underbar.
665 MCOS->EmitBytes(Entry->getName(), 0);
666 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
668 // AT_decl_file, index into the file table.
669 MCOS->EmitIntValue(Entry->getFileNumber(), 4);
671 // AT_decl_line, source line number.
672 MCOS->EmitIntValue(Entry->getLineNumber(), 4);
674 // AT_low_pc, start address of the label.
675 const MCExpr *AT_low_pc = MCSymbolRefExpr::Create(Entry->getLabel(),
676 MCSymbolRefExpr::VK_None, context);
677 MCOS->EmitAbsValue(AT_low_pc, AddrSize);
679 // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype.
680 MCOS->EmitIntValue(0, 1);
682 // The DW_TAG_unspecified_parameters DIE abbrev (3).
683 MCOS->EmitULEB128IntValue(3);
685 // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's.
686 MCOS->EmitIntValue(0, 1);
688 // Deallocate the MCGenDwarfLabelEntry classes that saved away the info
689 // for the dwarf labels.
690 for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it =
691 Entries.begin(), ie = Entries.end(); it != ie;
693 const MCGenDwarfLabelEntry *Entry = *it;
697 // Add the NULL DIE terminating the Compile Unit DIE's.
698 MCOS->EmitIntValue(0, 1);
700 // Now set the value of the symbol at the end of the info section.
701 MCOS->EmitLabel(InfoEnd);
705 // When generating dwarf for assembly source files this emits the Dwarf
708 void MCGenDwarfInfo::Emit(MCStreamer *MCOS, const MCSymbol *LineSectionSymbol) {
709 // Create the dwarf sections in this order (.debug_line already created).
710 MCContext &context = MCOS->getContext();
711 const MCAsmInfo &AsmInfo = context.getAsmInfo();
712 bool CreateDwarfSectionSymbols =
713 AsmInfo.doesDwarfUseRelocationsAcrossSections();
714 if (!CreateDwarfSectionSymbols)
715 LineSectionSymbol = NULL;
716 MCSymbol *AbbrevSectionSymbol = NULL;
717 MCSymbol *InfoSectionSymbol = NULL;
718 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
719 if (CreateDwarfSectionSymbols) {
720 InfoSectionSymbol = context.CreateTempSymbol();
721 MCOS->EmitLabel(InfoSectionSymbol);
723 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
724 if (CreateDwarfSectionSymbols) {
725 AbbrevSectionSymbol = context.CreateTempSymbol();
726 MCOS->EmitLabel(AbbrevSectionSymbol);
728 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
730 // If there are no line table entries then do not emit any section contents.
731 if (context.getMCLineSections().empty())
734 // Output the data for .debug_aranges section.
735 EmitGenDwarfAranges(MCOS, InfoSectionSymbol);
737 // Output the data for .debug_abbrev section.
738 EmitGenDwarfAbbrev(MCOS);
740 // Output the data for .debug_info section.
741 EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol);
745 // When generating dwarf for assembly source files this is called when symbol
746 // for a label is created. If this symbol is not a temporary and is in the
747 // section that dwarf is being generated for, save the needed info to create
750 void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
751 SourceMgr &SrcMgr, SMLoc &Loc) {
752 // We won't create dwarf labels for temporary symbols or symbols not in
754 if (Symbol->isTemporary())
756 MCContext &context = MCOS->getContext();
757 if (context.getGenDwarfSection() != MCOS->getCurrentSection())
760 // The dwarf label's name does not have the symbol name's leading
762 StringRef Name = Symbol->getName();
763 if (Name.startswith("_"))
764 Name = Name.substr(1, Name.size()-1);
766 // Get the dwarf file number to be used for the dwarf label.
767 unsigned FileNumber = context.getGenDwarfFileNumber();
769 // Finding the line number is the expensive part which is why we just don't
770 // pass it in as for some symbols we won't create a dwarf label.
771 int CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
772 unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
774 // We create a temporary symbol for use for the AT_high_pc and AT_low_pc
775 // values so that they don't have things like an ARM thumb bit from the
776 // original symbol. So when used they won't get a low bit set after
778 MCSymbol *Label = context.CreateTempSymbol();
779 MCOS->EmitLabel(Label);
781 // Create and entry for the info and add it to the other entries.
782 MCGenDwarfLabelEntry *Entry =
783 new MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label);
784 MCOS->getContext().addMCGenDwarfLabelEntry(Entry);
787 static int getDataAlignmentFactor(MCStreamer &streamer) {
788 MCContext &context = streamer.getContext();
789 const MCAsmInfo &asmInfo = context.getAsmInfo();
790 int size = asmInfo.getPointerSize();
791 if (asmInfo.isStackGrowthDirectionUp())
797 static unsigned getSizeForEncoding(MCStreamer &streamer,
798 unsigned symbolEncoding) {
799 MCContext &context = streamer.getContext();
800 unsigned format = symbolEncoding & 0x0f;
802 default: llvm_unreachable("Unknown Encoding");
803 case dwarf::DW_EH_PE_absptr:
804 case dwarf::DW_EH_PE_signed:
805 return context.getAsmInfo().getPointerSize();
806 case dwarf::DW_EH_PE_udata2:
807 case dwarf::DW_EH_PE_sdata2:
809 case dwarf::DW_EH_PE_udata4:
810 case dwarf::DW_EH_PE_sdata4:
812 case dwarf::DW_EH_PE_udata8:
813 case dwarf::DW_EH_PE_sdata8:
818 static void EmitSymbol(MCStreamer &streamer, const MCSymbol &symbol,
819 unsigned symbolEncoding, const char *comment = 0) {
820 MCContext &context = streamer.getContext();
821 const MCAsmInfo &asmInfo = context.getAsmInfo();
822 const MCExpr *v = asmInfo.getExprForFDESymbol(&symbol,
825 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
826 if (streamer.isVerboseAsm() && comment) streamer.AddComment(comment);
827 streamer.EmitAbsValue(v, size);
830 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
831 unsigned symbolEncoding) {
832 MCContext &context = streamer.getContext();
833 const MCAsmInfo &asmInfo = context.getAsmInfo();
834 const MCExpr *v = asmInfo.getExprForPersonalitySymbol(&symbol,
837 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
838 streamer.EmitValue(v, size);
841 static const MachineLocation TranslateMachineLocation(
842 const MCRegisterInfo &MRI,
843 const MachineLocation &Loc) {
844 unsigned Reg = Loc.getReg() == MachineLocation::VirtualFP ?
845 MachineLocation::VirtualFP :
846 unsigned(MRI.getDwarfRegNum(Loc.getReg(), true));
847 const MachineLocation &NewLoc = Loc.isReg() ?
848 MachineLocation(Reg) : MachineLocation(Reg, Loc.getOffset());
853 class FrameEmitterImpl {
858 const MCSymbol *SectionStart;
860 FrameEmitterImpl(bool usingCFI, bool isEH)
861 : CFAOffset(0), CIENum(0), UsingCFI(usingCFI), IsEH(isEH),
864 void setSectionStart(const MCSymbol *Label) { SectionStart = Label; }
866 /// EmitCompactUnwind - Emit the unwind information in a compact way. If
867 /// we're successful, return 'true'. Otherwise, return 'false' and it will
868 /// emit the normal CIE and FDE.
869 bool EmitCompactUnwind(MCStreamer &streamer,
870 const MCDwarfFrameInfo &frame);
872 const MCSymbol &EmitCIE(MCStreamer &streamer,
873 const MCSymbol *personality,
874 unsigned personalityEncoding,
875 const MCSymbol *lsda,
877 unsigned lsdaEncoding);
878 MCSymbol *EmitFDE(MCStreamer &streamer,
879 const MCSymbol &cieStart,
880 const MCDwarfFrameInfo &frame);
881 void EmitCFIInstructions(MCStreamer &streamer,
882 const std::vector<MCCFIInstruction> &Instrs,
883 MCSymbol *BaseLabel);
884 void EmitCFIInstruction(MCStreamer &Streamer,
885 const MCCFIInstruction &Instr);
888 } // end anonymous namespace
890 static void EmitEncodingByte(MCStreamer &Streamer, unsigned Encoding,
892 if (Streamer.isVerboseAsm()) {
895 default: EncStr = "<unknown encoding>"; break;
896 case dwarf::DW_EH_PE_absptr: EncStr = "absptr"; break;
897 case dwarf::DW_EH_PE_omit: EncStr = "omit"; break;
898 case dwarf::DW_EH_PE_pcrel: EncStr = "pcrel"; break;
899 case dwarf::DW_EH_PE_udata4: EncStr = "udata4"; break;
900 case dwarf::DW_EH_PE_udata8: EncStr = "udata8"; break;
901 case dwarf::DW_EH_PE_sdata4: EncStr = "sdata4"; break;
902 case dwarf::DW_EH_PE_sdata8: EncStr = "sdata8"; break;
903 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
904 EncStr = "pcrel udata4";
906 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
907 EncStr = "pcrel sdata4";
909 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
910 EncStr = "pcrel udata8";
912 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
913 EncStr = "screl sdata8";
915 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata4:
916 EncStr = "indirect pcrel udata4";
918 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata4:
919 EncStr = "indirect pcrel sdata4";
921 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata8:
922 EncStr = "indirect pcrel udata8";
924 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata8:
925 EncStr = "indirect pcrel sdata8";
929 Streamer.AddComment(Twine(Prefix) + " = " + EncStr);
932 Streamer.EmitIntValue(Encoding, 1);
935 void FrameEmitterImpl::EmitCFIInstruction(MCStreamer &Streamer,
936 const MCCFIInstruction &Instr) {
937 int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
938 bool VerboseAsm = Streamer.isVerboseAsm();
940 switch (Instr.getOperation()) {
941 case MCCFIInstruction::OpUndefined: {
942 unsigned Reg = Instr.getDestination().getReg();
944 Streamer.AddComment("DW_CFA_undefined");
945 Streamer.AddComment(Twine("Reg ") + Twine(Reg));
947 Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1);
948 Streamer.EmitULEB128IntValue(Reg);
951 case MCCFIInstruction::OpAdjustCfaOffset:
952 case MCCFIInstruction::OpDefCfaOffset: {
953 const MachineLocation &Src = Instr.getSource();
954 const bool IsRelative =
955 Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset;
958 Streamer.AddComment("DW_CFA_def_cfa_offset");
959 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
962 CFAOffset += Src.getOffset();
964 CFAOffset = -Src.getOffset();
967 Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
968 Streamer.EmitULEB128IntValue(CFAOffset);
972 case MCCFIInstruction::OpDefCfa: {
973 const MachineLocation &Src = Instr.getSource();
976 Streamer.AddComment("DW_CFA_def_cfa");
977 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
980 Streamer.AddComment(Twine("Reg ") + Twine(Src.getReg()));
981 Streamer.EmitULEB128IntValue(Src.getReg());
983 CFAOffset = -Src.getOffset();
986 Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
987 Streamer.EmitULEB128IntValue(CFAOffset);
992 case MCCFIInstruction::OpDefCfaRegister: {
993 const MachineLocation &Dst = Instr.getDestination();
995 assert(Dst.isReg() && "Machine move not supported yet.");
997 Streamer.AddComment("DW_CFA_def_cfa_register");
998 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
1001 Streamer.AddComment(Twine("Reg ") + Twine(Dst.getReg()));
1002 Streamer.EmitULEB128IntValue(Dst.getReg());
1007 case MCCFIInstruction::OpOffset:
1008 case MCCFIInstruction::OpRelOffset: {
1009 const MachineLocation &Dst = Instr.getDestination();
1010 const MachineLocation &Src = Instr.getSource();
1011 const bool IsRelative =
1012 Instr.getOperation() == MCCFIInstruction::OpRelOffset;
1014 unsigned Reg = Src.getReg();
1015 int Offset = Dst.getOffset();
1017 Offset -= CFAOffset;
1018 Offset = Offset / dataAlignmentFactor;
1021 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended_sf");
1022 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
1023 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1024 Streamer.EmitULEB128IntValue(Reg);
1025 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1026 Streamer.EmitSLEB128IntValue(Offset);
1027 } else if (Reg < 64) {
1028 if (VerboseAsm) Streamer.AddComment(Twine("DW_CFA_offset + Reg(") +
1030 Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
1031 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1032 Streamer.EmitULEB128IntValue(Offset);
1034 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended");
1035 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
1036 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1037 Streamer.EmitULEB128IntValue(Reg);
1038 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1039 Streamer.EmitULEB128IntValue(Offset);
1043 case MCCFIInstruction::OpRememberState:
1044 if (VerboseAsm) Streamer.AddComment("DW_CFA_remember_state");
1045 Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
1047 case MCCFIInstruction::OpRestoreState:
1048 if (VerboseAsm) Streamer.AddComment("DW_CFA_restore_state");
1049 Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
1051 case MCCFIInstruction::OpSameValue: {
1052 unsigned Reg = Instr.getDestination().getReg();
1053 if (VerboseAsm) Streamer.AddComment("DW_CFA_same_value");
1054 Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
1055 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1056 Streamer.EmitULEB128IntValue(Reg);
1059 case MCCFIInstruction::OpRestore: {
1060 unsigned Reg = Instr.getDestination().getReg();
1062 Streamer.AddComment("DW_CFA_restore");
1063 Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1065 Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1);
1068 case MCCFIInstruction::OpEscape:
1069 if (VerboseAsm) Streamer.AddComment("Escape bytes");
1070 Streamer.EmitBytes(Instr.getValues(), 0);
1073 llvm_unreachable("Unhandled case in switch");
1076 /// EmitFrameMoves - Emit frame instructions to describe the layout of the
1078 void FrameEmitterImpl::EmitCFIInstructions(MCStreamer &streamer,
1079 const std::vector<MCCFIInstruction> &Instrs,
1080 MCSymbol *BaseLabel) {
1081 for (unsigned i = 0, N = Instrs.size(); i < N; ++i) {
1082 const MCCFIInstruction &Instr = Instrs[i];
1083 MCSymbol *Label = Instr.getLabel();
1084 // Throw out move if the label is invalid.
1085 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
1087 // Advance row if new location.
1088 if (BaseLabel && Label) {
1089 MCSymbol *ThisSym = Label;
1090 if (ThisSym != BaseLabel) {
1091 if (streamer.isVerboseAsm()) streamer.AddComment("DW_CFA_advance_loc4");
1092 streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
1093 BaseLabel = ThisSym;
1097 EmitCFIInstruction(streamer, Instr);
1101 /// EmitCompactUnwind - Emit the unwind information in a compact way. If we're
1102 /// successful, return 'true'. Otherwise, return 'false' and it will emit the
1103 /// normal CIE and FDE.
1104 bool FrameEmitterImpl::EmitCompactUnwind(MCStreamer &Streamer,
1105 const MCDwarfFrameInfo &Frame) {
1106 MCContext &Context = Streamer.getContext();
1107 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1108 bool VerboseAsm = Streamer.isVerboseAsm();
1110 // range-start range-length compact-unwind-enc personality-func lsda
1111 // _foo LfooEnd-_foo 0x00000023 0 0
1112 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1
1114 // .section __LD,__compact_unwind,regular,debug
1116 // # compact unwind for _foo
1118 // .set L1,LfooEnd-_foo
1124 // # compact unwind for _bar
1126 // .set L2,LbarEnd-_bar
1129 // .quad __gxx_personality
1130 // .quad except_tab1
1132 uint32_t Encoding = Frame.CompactUnwindEncoding;
1133 if (!Encoding) return false;
1135 // The encoding needs to know we have an LSDA.
1137 Encoding |= 0x40000000;
1139 Streamer.SwitchSection(MOFI->getCompactUnwindSection());
1142 unsigned FDEEncoding = MOFI->getFDEEncoding(UsingCFI);
1143 unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
1144 if (VerboseAsm) Streamer.AddComment("Range Start");
1145 Streamer.EmitSymbolValue(Frame.Function, Size);
1148 const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin,
1150 if (VerboseAsm) Streamer.AddComment("Range Length");
1151 Streamer.EmitAbsValue(Range, 4);
1154 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
1155 if (VerboseAsm) Streamer.AddComment("Compact Unwind Encoding: 0x" +
1156 Twine::utohexstr(Encoding));
1157 Streamer.EmitIntValue(Encoding, Size);
1160 // Personality Function
1161 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
1162 if (VerboseAsm) Streamer.AddComment("Personality Function");
1163 if (Frame.Personality)
1164 Streamer.EmitSymbolValue(Frame.Personality, Size);
1166 Streamer.EmitIntValue(0, Size); // No personality fn
1169 Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
1170 if (VerboseAsm) Streamer.AddComment("LSDA");
1172 Streamer.EmitSymbolValue(Frame.Lsda, Size);
1174 Streamer.EmitIntValue(0, Size); // No LSDA
1179 const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
1180 const MCSymbol *personality,
1181 unsigned personalityEncoding,
1182 const MCSymbol *lsda,
1184 unsigned lsdaEncoding) {
1185 MCContext &context = streamer.getContext();
1186 const MCRegisterInfo &MRI = context.getRegisterInfo();
1187 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1188 bool verboseAsm = streamer.isVerboseAsm();
1190 MCSymbol *sectionStart;
1191 if (MOFI->isFunctionEHFrameSymbolPrivate() || !IsEH)
1192 sectionStart = context.CreateTempSymbol();
1194 sectionStart = context.GetOrCreateSymbol(Twine("EH_frame") + Twine(CIENum));
1196 streamer.EmitLabel(sectionStart);
1199 MCSymbol *sectionEnd = context.CreateTempSymbol();
1202 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *sectionStart,
1204 if (verboseAsm) streamer.AddComment("CIE Length");
1205 streamer.EmitAbsValue(Length, 4);
1208 unsigned CIE_ID = IsEH ? 0 : -1;
1209 if (verboseAsm) streamer.AddComment("CIE ID Tag");
1210 streamer.EmitIntValue(CIE_ID, 4);
1213 if (verboseAsm) streamer.AddComment("DW_CIE_VERSION");
1214 streamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1);
1216 // Augmentation String
1217 SmallString<8> Augmentation;
1219 if (verboseAsm) streamer.AddComment("CIE Augmentation");
1220 Augmentation += "z";
1222 Augmentation += "P";
1224 Augmentation += "L";
1225 Augmentation += "R";
1227 Augmentation += "S";
1228 streamer.EmitBytes(Augmentation.str(), 0);
1230 streamer.EmitIntValue(0, 1);
1232 // Code Alignment Factor
1233 if (verboseAsm) streamer.AddComment("CIE Code Alignment Factor");
1234 streamer.EmitULEB128IntValue(1);
1236 // Data Alignment Factor
1237 if (verboseAsm) streamer.AddComment("CIE Data Alignment Factor");
1238 streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer));
1240 // Return Address Register
1241 if (verboseAsm) streamer.AddComment("CIE Return Address Column");
1242 streamer.EmitULEB128IntValue(MRI.getDwarfRegNum(MRI.getRARegister(), true));
1244 // Augmentation Data Length (optional)
1246 unsigned augmentationLength = 0;
1249 // Personality Encoding
1250 augmentationLength += 1;
1252 augmentationLength += getSizeForEncoding(streamer, personalityEncoding);
1255 augmentationLength += 1;
1256 // Encoding of the FDE pointers
1257 augmentationLength += 1;
1259 if (verboseAsm) streamer.AddComment("Augmentation Size");
1260 streamer.EmitULEB128IntValue(augmentationLength);
1262 // Augmentation Data (optional)
1264 // Personality Encoding
1265 EmitEncodingByte(streamer, personalityEncoding,
1266 "Personality Encoding");
1268 if (verboseAsm) streamer.AddComment("Personality");
1269 EmitPersonality(streamer, *personality, personalityEncoding);
1273 EmitEncodingByte(streamer, lsdaEncoding, "LSDA Encoding");
1275 // Encoding of the FDE pointers
1276 EmitEncodingByte(streamer, MOFI->getFDEEncoding(UsingCFI),
1280 // Initial Instructions
1282 const MCAsmInfo &MAI = context.getAsmInfo();
1283 const std::vector<MachineMove> &Moves = MAI.getInitialFrameState();
1284 std::vector<MCCFIInstruction> Instructions;
1286 for (int i = 0, n = Moves.size(); i != n; ++i) {
1287 MCSymbol *Label = Moves[i].getLabel();
1288 const MachineLocation &Dst =
1289 TranslateMachineLocation(MRI, Moves[i].getDestination());
1290 const MachineLocation &Src =
1291 TranslateMachineLocation(MRI, Moves[i].getSource());
1294 assert(Dst.getReg() == MachineLocation::VirtualFP);
1295 assert(!Src.isReg());
1296 MCCFIInstruction Inst =
1297 MCCFIInstruction::createDefCfa(Label, Src.getReg(), -Src.getOffset());
1298 Instructions.push_back(Inst);
1300 assert(Src.isReg());
1301 unsigned Reg = Src.getReg();
1302 int Offset = Dst.getOffset();
1303 MCCFIInstruction Inst =
1304 MCCFIInstruction::createOffset(Label, Reg, Offset);
1305 Instructions.push_back(Inst);
1309 EmitCFIInstructions(streamer, Instructions, NULL);
1312 streamer.EmitValueToAlignment(IsEH
1313 ? 4 : context.getAsmInfo().getPointerSize());
1315 streamer.EmitLabel(sectionEnd);
1316 return *sectionStart;
1319 MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
1320 const MCSymbol &cieStart,
1321 const MCDwarfFrameInfo &frame) {
1322 MCContext &context = streamer.getContext();
1323 MCSymbol *fdeStart = context.CreateTempSymbol();
1324 MCSymbol *fdeEnd = context.CreateTempSymbol();
1325 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1326 bool verboseAsm = streamer.isVerboseAsm();
1328 if (IsEH && frame.Function && !MOFI->isFunctionEHFrameSymbolPrivate()) {
1330 context.GetOrCreateSymbol(frame.Function->getName() + Twine(".eh"));
1331 streamer.EmitEHSymAttributes(frame.Function, EHSym);
1332 streamer.EmitLabel(EHSym);
1336 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *fdeStart, *fdeEnd, 0);
1337 if (verboseAsm) streamer.AddComment("FDE Length");
1338 streamer.EmitAbsValue(Length, 4);
1340 streamer.EmitLabel(fdeStart);
1343 const MCAsmInfo &asmInfo = context.getAsmInfo();
1345 const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart,
1347 if (verboseAsm) streamer.AddComment("FDE CIE Offset");
1348 streamer.EmitAbsValue(offset, 4);
1349 } else if (!asmInfo.doesDwarfUseRelocationsAcrossSections()) {
1350 const MCExpr *offset = MakeStartMinusEndExpr(streamer, *SectionStart,
1352 streamer.EmitAbsValue(offset, 4);
1354 streamer.EmitSymbolValue(&cieStart, 4);
1358 unsigned PCEncoding = IsEH ? MOFI->getFDEEncoding(UsingCFI)
1359 : (unsigned)dwarf::DW_EH_PE_absptr;
1360 unsigned PCSize = getSizeForEncoding(streamer, PCEncoding);
1361 EmitSymbol(streamer, *frame.Begin, PCEncoding, "FDE initial location");
1364 const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin,
1366 if (verboseAsm) streamer.AddComment("FDE address range");
1367 streamer.EmitAbsValue(Range, PCSize);
1370 // Augmentation Data Length
1371 unsigned augmentationLength = 0;
1374 augmentationLength += getSizeForEncoding(streamer, frame.LsdaEncoding);
1376 if (verboseAsm) streamer.AddComment("Augmentation size");
1377 streamer.EmitULEB128IntValue(augmentationLength);
1379 // Augmentation Data
1381 EmitSymbol(streamer, *frame.Lsda, frame.LsdaEncoding,
1382 "Language Specific Data Area");
1385 // Call Frame Instructions
1387 EmitCFIInstructions(streamer, frame.Instructions, frame.Begin);
1390 streamer.EmitValueToAlignment(PCSize);
1397 static const CIEKey getEmptyKey() { return CIEKey(0, 0, -1, false); }
1398 static const CIEKey getTombstoneKey() { return CIEKey(0, -1, 0, false); }
1400 CIEKey(const MCSymbol* Personality_, unsigned PersonalityEncoding_,
1401 unsigned LsdaEncoding_, bool IsSignalFrame_) :
1402 Personality(Personality_), PersonalityEncoding(PersonalityEncoding_),
1403 LsdaEncoding(LsdaEncoding_), IsSignalFrame(IsSignalFrame_) {
1405 const MCSymbol* Personality;
1406 unsigned PersonalityEncoding;
1407 unsigned LsdaEncoding;
1414 struct DenseMapInfo<CIEKey> {
1415 static CIEKey getEmptyKey() {
1416 return CIEKey::getEmptyKey();
1418 static CIEKey getTombstoneKey() {
1419 return CIEKey::getTombstoneKey();
1421 static unsigned getHashValue(const CIEKey &Key) {
1422 return static_cast<unsigned>(hash_combine(Key.Personality,
1423 Key.PersonalityEncoding,
1425 Key.IsSignalFrame));
1427 static bool isEqual(const CIEKey &LHS,
1428 const CIEKey &RHS) {
1429 return LHS.Personality == RHS.Personality &&
1430 LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
1431 LHS.LsdaEncoding == RHS.LsdaEncoding &&
1432 LHS.IsSignalFrame == RHS.IsSignalFrame;
1437 void MCDwarfFrameEmitter::Emit(MCStreamer &Streamer,
1440 MCContext &Context = Streamer.getContext();
1441 MCObjectFileInfo *MOFI =
1442 const_cast<MCObjectFileInfo*>(Context.getObjectFileInfo());
1443 FrameEmitterImpl Emitter(UsingCFI, IsEH);
1444 ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getFrameInfos();
1446 // Emit the compact unwind info if available.
1447 if (IsEH && MOFI->getCompactUnwindSection())
1448 for (unsigned i = 0, n = Streamer.getNumFrameInfos(); i < n; ++i) {
1449 const MCDwarfFrameInfo &Frame = Streamer.getFrameInfo(i);
1450 if (Frame.CompactUnwindEncoding)
1451 Emitter.EmitCompactUnwind(Streamer, Frame);
1454 const MCSection &Section = IsEH ? *MOFI->getEHFrameSection() :
1455 *MOFI->getDwarfFrameSection();
1456 Streamer.SwitchSection(&Section);
1457 MCSymbol *SectionStart = Context.CreateTempSymbol();
1458 Streamer.EmitLabel(SectionStart);
1459 Emitter.setSectionStart(SectionStart);
1461 MCSymbol *FDEEnd = NULL;
1462 DenseMap<CIEKey, const MCSymbol*> CIEStarts;
1464 const MCSymbol *DummyDebugKey = NULL;
1465 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
1466 const MCDwarfFrameInfo &Frame = FrameArray[i];
1467 CIEKey Key(Frame.Personality, Frame.PersonalityEncoding,
1468 Frame.LsdaEncoding, Frame.IsSignalFrame);
1469 const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
1471 CIEStart = &Emitter.EmitCIE(Streamer, Frame.Personality,
1472 Frame.PersonalityEncoding, Frame.Lsda,
1473 Frame.IsSignalFrame,
1474 Frame.LsdaEncoding);
1476 FDEEnd = Emitter.EmitFDE(Streamer, *CIEStart, Frame);
1479 Streamer.EmitLabel(FDEEnd);
1482 Streamer.EmitValueToAlignment(Context.getAsmInfo().getPointerSize());
1484 Streamer.EmitLabel(FDEEnd);
1487 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCStreamer &Streamer,
1488 uint64_t AddrDelta) {
1489 SmallString<256> Tmp;
1490 raw_svector_ostream OS(Tmp);
1491 MCDwarfFrameEmitter::EncodeAdvanceLoc(AddrDelta, OS);
1492 Streamer.EmitBytes(OS.str(), /*AddrSpace=*/0);
1495 void MCDwarfFrameEmitter::EncodeAdvanceLoc(uint64_t AddrDelta,
1497 // FIXME: Assumes the code alignment factor is 1.
1498 if (AddrDelta == 0) {
1499 } else if (isUIntN(6, AddrDelta)) {
1500 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
1502 } else if (isUInt<8>(AddrDelta)) {
1503 OS << uint8_t(dwarf::DW_CFA_advance_loc1);
1504 OS << uint8_t(AddrDelta);
1505 } else if (isUInt<16>(AddrDelta)) {
1506 // FIXME: check what is the correct behavior on a big endian machine.
1507 OS << uint8_t(dwarf::DW_CFA_advance_loc2);
1508 OS << uint8_t( AddrDelta & 0xff);
1509 OS << uint8_t((AddrDelta >> 8) & 0xff);
1511 // FIXME: check what is the correct behavior on a big endian machine.
1512 assert(isUInt<32>(AddrDelta));
1513 OS << uint8_t(dwarf::DW_CFA_advance_loc4);
1514 OS << uint8_t( AddrDelta & 0xff);
1515 OS << uint8_t((AddrDelta >> 8) & 0xff);
1516 OS << uint8_t((AddrDelta >> 16) & 0xff);
1517 OS << uint8_t((AddrDelta >> 24) & 0xff);