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 MCOS->EmitBytes(MCDwarfFiles[i].Name); // FileName
291 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
293 MCOS->EmitULEB128IntValue(MCDwarfFiles[i].DirIndex);
294 MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
295 MCOS->EmitIntValue(0, 1); // filesize (always 0)
297 MCOS->EmitIntValue(0, 1); // Terminate the file list
299 // This is the end of the prologue, so set the value of the symbol at the
300 // end of the prologue (that was used in a previous expression).
301 MCOS->EmitLabel(ProEndSym);
303 return std::make_pair(LineStartSym, LineEndSym);
306 const MCSymbol *MCDwarfLineTable::EmitCU(MCStreamer *MCOS) const {
307 MCSymbol *LineStartSym;
308 MCSymbol *LineEndSym;
309 std::tie(LineStartSym, LineEndSym) = Header.Emit(MCOS);
311 // Put out the line tables.
312 for (const auto &LineSec : MCLineSections.getMCLineEntries())
313 EmitDwarfLineTable(MCOS, LineSec.first, LineSec.second);
315 if (MCOS->getContext().getAsmInfo()->getLinkerRequiresNonEmptyDwarfLines() &&
316 MCLineSections.getMCLineEntries().empty()) {
317 // The darwin9 linker has a bug (see PR8715). For for 32-bit architectures
319 // total_length >= prologue_length + 10
320 // We are 4 bytes short, since we have total_length = 51 and
321 // prologue_length = 45
323 // The regular end_sequence should be sufficient.
324 MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
327 // This is the end of the section, so set the value of the symbol at the end
328 // of this section (that was used in a previous expression).
329 MCOS->EmitLabel(LineEndSym);
334 unsigned MCDwarfLineTable::getFile(StringRef Directory, StringRef FileName,
335 unsigned FileNumber) {
336 return Header.getFile(Directory, FileName, FileNumber);
339 unsigned MCDwarfLineTableHeader::getFile(StringRef Directory,
341 unsigned FileNumber) {
342 if (FileNumber == 0) {
343 FileNumber = SourceIdMap.size() + 1;
344 assert((MCDwarfFiles.empty() || FileNumber == MCDwarfFiles.size()) &&
345 "Don't mix autonumbered and explicit numbered line table usage");
346 StringMapEntry<unsigned> &Ent = SourceIdMap.GetOrCreateValue(
347 (Directory + Twine('\0') + FileName).str(), FileNumber);
348 if (Ent.getValue() != FileNumber)
349 return Ent.getValue();
351 // Make space for this FileNumber in the MCDwarfFiles vector if needed.
352 MCDwarfFiles.resize(FileNumber + 1);
354 // Get the new MCDwarfFile slot for this FileNumber.
355 MCDwarfFile &File = MCDwarfFiles[FileNumber];
357 // It is an error to use see the same number more than once.
358 if (!File.Name.empty())
361 if (Directory.empty()) {
362 // Separate the directory part from the basename of the FileName.
363 StringRef tFileName = sys::path::filename(FileName);
364 if (!tFileName.empty()) {
365 Directory = sys::path::parent_path(FileName);
366 if (!Directory.empty())
367 FileName = tFileName;
371 // Find or make an entry in the MCDwarfDirs vector for this Directory.
372 // Capture directory name.
374 if (Directory.empty()) {
375 // For FileNames with no directories a DirIndex of 0 is used.
379 for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
380 if (Directory == MCDwarfDirs[DirIndex])
383 if (DirIndex >= MCDwarfDirs.size())
384 MCDwarfDirs.push_back(Directory);
385 // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
386 // no directories. MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
387 // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
388 // are stored at MCDwarfFiles[FileNumber].Name .
392 File.Name = FileName;
393 File.DirIndex = DirIndex;
395 // return the allocated FileNumber.
399 /// Utility function to emit the encoding to a streamer.
400 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta,
401 uint64_t AddrDelta) {
402 MCContext &Context = MCOS->getContext();
403 SmallString<256> Tmp;
404 raw_svector_ostream OS(Tmp);
405 MCDwarfLineAddr::Encode(Context, LineDelta, AddrDelta, OS);
406 MCOS->EmitBytes(OS.str());
409 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
410 void MCDwarfLineAddr::Encode(MCContext &Context, int64_t LineDelta,
411 uint64_t AddrDelta, raw_ostream &OS) {
412 uint64_t Temp, Opcode;
413 bool NeedCopy = false;
415 // Scale the address delta by the minimum instruction length.
416 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
418 // A LineDelta of INT64_MAX is a signal that this is actually a
419 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
420 // end_sequence to emit the matrix entry.
421 if (LineDelta == INT64_MAX) {
422 if (AddrDelta == MAX_SPECIAL_ADDR_DELTA)
423 OS << char(dwarf::DW_LNS_const_add_pc);
425 OS << char(dwarf::DW_LNS_advance_pc);
426 encodeULEB128(AddrDelta, OS);
428 OS << char(dwarf::DW_LNS_extended_op);
430 OS << char(dwarf::DW_LNE_end_sequence);
434 // Bias the line delta by the base.
435 Temp = LineDelta - DWARF2_LINE_BASE;
437 // If the line increment is out of range of a special opcode, we must encode
438 // it with DW_LNS_advance_line.
439 if (Temp >= DWARF2_LINE_RANGE) {
440 OS << char(dwarf::DW_LNS_advance_line);
441 encodeSLEB128(LineDelta, OS);
444 Temp = 0 - DWARF2_LINE_BASE;
448 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
449 if (LineDelta == 0 && AddrDelta == 0) {
450 OS << char(dwarf::DW_LNS_copy);
454 // Bias the opcode by the special opcode base.
455 Temp += DWARF2_LINE_OPCODE_BASE;
457 // Avoid overflow when addr_delta is large.
458 if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) {
459 // Try using a special opcode.
460 Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE;
466 // Try using DW_LNS_const_add_pc followed by special op.
467 Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
469 OS << char(dwarf::DW_LNS_const_add_pc);
475 // Otherwise use DW_LNS_advance_pc.
476 OS << char(dwarf::DW_LNS_advance_pc);
477 encodeULEB128(AddrDelta, OS);
480 OS << char(dwarf::DW_LNS_copy);
485 // Utility function to write a tuple for .debug_abbrev.
486 static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) {
487 MCOS->EmitULEB128IntValue(Name);
488 MCOS->EmitULEB128IntValue(Form);
491 // When generating dwarf for assembly source files this emits
492 // the data for .debug_abbrev section which contains three DIEs.
493 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
494 MCContext &context = MCOS->getContext();
495 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
497 // DW_TAG_compile_unit DIE abbrev (1).
498 MCOS->EmitULEB128IntValue(1);
499 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit);
500 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
501 EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4);
502 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
503 EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
504 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
505 if (!context.getCompilationDir().empty())
506 EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
507 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
508 if (!DwarfDebugFlags.empty())
509 EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
510 EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string);
511 EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2);
512 EmitAbbrev(MCOS, 0, 0);
514 // DW_TAG_label DIE abbrev (2).
515 MCOS->EmitULEB128IntValue(2);
516 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_label);
517 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
518 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
519 EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);
520 EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);
521 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
522 EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag);
523 EmitAbbrev(MCOS, 0, 0);
525 // DW_TAG_unspecified_parameters DIE abbrev (3).
526 MCOS->EmitULEB128IntValue(3);
527 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters);
528 MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1);
529 EmitAbbrev(MCOS, 0, 0);
531 // Terminate the abbreviations for this compilation unit.
532 MCOS->EmitIntValue(0, 1);
535 // When generating dwarf for assembly source files this emits the data for
536 // .debug_aranges section. Which contains a header and a table of pairs of
537 // PointerSize'ed values for the address and size of section(s) with line table
538 // entries (just the default .text in our case) and a terminating pair of zeros.
539 static void EmitGenDwarfAranges(MCStreamer *MCOS,
540 const MCSymbol *InfoSectionSymbol) {
541 MCContext &context = MCOS->getContext();
543 // Create a symbol at the end of the section that we are creating the dwarf
544 // debugging info to use later in here as part of the expression to calculate
545 // the size of the section for the table.
546 MCOS->SwitchSection(context.getGenDwarfSection());
547 MCSymbol *SectionEndSym = context.CreateTempSymbol();
548 MCOS->EmitLabel(SectionEndSym);
549 context.setGenDwarfSectionEndSym(SectionEndSym);
551 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
553 // This will be the length of the .debug_aranges section, first account for
554 // the size of each item in the header (see below where we emit these items).
555 int Length = 4 + 2 + 4 + 1 + 1;
557 // Figure the padding after the header before the table of address and size
558 // pairs who's values are PointerSize'ed.
559 const MCAsmInfo *asmInfo = context.getAsmInfo();
560 int AddrSize = asmInfo->getPointerSize();
561 int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1));
562 if (Pad == 2 * AddrSize)
566 // Add the size of the pair of PointerSize'ed values for the address and size
567 // of the one default .text section we have in the table.
568 Length += 2 * AddrSize;
569 // And the pair of terminating zeros.
570 Length += 2 * AddrSize;
573 // Emit the header for this section.
574 // The 4 byte length not including the 4 byte value for the length.
575 MCOS->EmitIntValue(Length - 4, 4);
576 // The 2 byte version, which is 2.
577 MCOS->EmitIntValue(2, 2);
578 // The 4 byte offset to the compile unit in the .debug_info from the start
579 // of the .debug_info.
580 if (InfoSectionSymbol)
581 MCOS->EmitSymbolValue(InfoSectionSymbol, 4);
583 MCOS->EmitIntValue(0, 4);
584 // The 1 byte size of an address.
585 MCOS->EmitIntValue(AddrSize, 1);
586 // The 1 byte size of a segment descriptor, we use a value of zero.
587 MCOS->EmitIntValue(0, 1);
588 // Align the header with the padding if needed, before we put out the table.
589 for(int i = 0; i < Pad; i++)
590 MCOS->EmitIntValue(0, 1);
592 // Now emit the table of pairs of PointerSize'ed values for the section(s)
593 // address and size, in our case just the one default .text section.
594 const MCExpr *Addr = MCSymbolRefExpr::Create(
595 context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
596 const MCExpr *Size = MakeStartMinusEndExpr(*MCOS,
597 *context.getGenDwarfSectionStartSym(), *SectionEndSym, 0);
598 MCOS->EmitAbsValue(Addr, AddrSize);
599 MCOS->EmitAbsValue(Size, AddrSize);
601 // And finally the pair of terminating zeros.
602 MCOS->EmitIntValue(0, AddrSize);
603 MCOS->EmitIntValue(0, AddrSize);
606 // When generating dwarf for assembly source files this emits the data for
607 // .debug_info section which contains three parts. The header, the compile_unit
608 // DIE and a list of label DIEs.
609 static void EmitGenDwarfInfo(MCStreamer *MCOS,
610 const MCSymbol *AbbrevSectionSymbol,
611 const MCSymbol *LineSectionSymbol) {
612 MCContext &context = MCOS->getContext();
614 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
616 // Create a symbol at the start and end of this section used in here for the
617 // expression to calculate the length in the header.
618 MCSymbol *InfoStart = context.CreateTempSymbol();
619 MCOS->EmitLabel(InfoStart);
620 MCSymbol *InfoEnd = context.CreateTempSymbol();
622 // First part: the header.
624 // The 4 byte total length of the information for this compilation unit, not
625 // including these 4 bytes.
626 const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4);
627 MCOS->EmitAbsValue(Length, 4);
629 // The 2 byte DWARF version, which is 2.
630 MCOS->EmitIntValue(2, 2);
632 // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev,
633 // it is at the start of that section so this is zero.
634 if (AbbrevSectionSymbol) {
635 MCOS->EmitSymbolValue(AbbrevSectionSymbol, 4);
637 MCOS->EmitIntValue(0, 4);
640 const MCAsmInfo *asmInfo = context.getAsmInfo();
641 int AddrSize = asmInfo->getPointerSize();
642 // The 1 byte size of an address.
643 MCOS->EmitIntValue(AddrSize, 1);
645 // Second part: the compile_unit DIE.
647 // The DW_TAG_compile_unit DIE abbrev (1).
648 MCOS->EmitULEB128IntValue(1);
650 // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section,
651 // which is at the start of that section so this is zero.
652 if (LineSectionSymbol) {
653 MCOS->EmitSymbolValue(LineSectionSymbol, 4);
655 MCOS->EmitIntValue(0, 4);
658 // AT_low_pc, the first address of the default .text section.
659 const MCExpr *Start = MCSymbolRefExpr::Create(
660 context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
661 MCOS->EmitAbsValue(Start, AddrSize);
663 // AT_high_pc, the last address of the default .text section.
664 const MCExpr *End = MCSymbolRefExpr::Create(
665 context.getGenDwarfSectionEndSym(), MCSymbolRefExpr::VK_None, context);
666 MCOS->EmitAbsValue(End, AddrSize);
668 // AT_name, the name of the source file. Reconstruct from the first directory
669 // and file table entries.
670 const SmallVectorImpl<std::string> &MCDwarfDirs = context.getMCDwarfDirs();
671 if (MCDwarfDirs.size() > 0) {
672 MCOS->EmitBytes(MCDwarfDirs[0]);
673 MCOS->EmitBytes("/");
675 const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles =
676 MCOS->getContext().getMCDwarfFiles();
677 MCOS->EmitBytes(MCDwarfFiles[1].Name);
678 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
680 // AT_comp_dir, the working directory the assembly was done in.
681 if (!context.getCompilationDir().empty()) {
682 MCOS->EmitBytes(context.getCompilationDir());
683 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
686 // AT_APPLE_flags, the command line arguments of the assembler tool.
687 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
688 if (!DwarfDebugFlags.empty()){
689 MCOS->EmitBytes(DwarfDebugFlags);
690 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
693 // AT_producer, the version of the assembler tool.
694 StringRef DwarfDebugProducer = context.getDwarfDebugProducer();
695 if (!DwarfDebugProducer.empty()){
696 MCOS->EmitBytes(DwarfDebugProducer);
699 MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM "));
700 MCOS->EmitBytes(StringRef(PACKAGE_VERSION));
701 MCOS->EmitBytes(StringRef(")"));
703 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
705 // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2
706 // draft has no standard code for assembler.
707 MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2);
709 // Third part: the list of label DIEs.
711 // Loop on saved info for dwarf labels and create the DIEs for them.
712 const std::vector<const MCGenDwarfLabelEntry *> &Entries =
713 MCOS->getContext().getMCGenDwarfLabelEntries();
714 for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it =
715 Entries.begin(), ie = Entries.end(); it != ie;
717 const MCGenDwarfLabelEntry *Entry = *it;
719 // The DW_TAG_label DIE abbrev (2).
720 MCOS->EmitULEB128IntValue(2);
722 // AT_name, of the label without any leading underbar.
723 MCOS->EmitBytes(Entry->getName());
724 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
726 // AT_decl_file, index into the file table.
727 MCOS->EmitIntValue(Entry->getFileNumber(), 4);
729 // AT_decl_line, source line number.
730 MCOS->EmitIntValue(Entry->getLineNumber(), 4);
732 // AT_low_pc, start address of the label.
733 const MCExpr *AT_low_pc = MCSymbolRefExpr::Create(Entry->getLabel(),
734 MCSymbolRefExpr::VK_None, context);
735 MCOS->EmitAbsValue(AT_low_pc, AddrSize);
737 // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype.
738 MCOS->EmitIntValue(0, 1);
740 // The DW_TAG_unspecified_parameters DIE abbrev (3).
741 MCOS->EmitULEB128IntValue(3);
743 // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's.
744 MCOS->EmitIntValue(0, 1);
746 // Deallocate the MCGenDwarfLabelEntry classes that saved away the info
747 // for the dwarf labels.
748 for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it =
749 Entries.begin(), ie = Entries.end(); it != ie;
751 const MCGenDwarfLabelEntry *Entry = *it;
755 // Add the NULL DIE terminating the Compile Unit DIE's.
756 MCOS->EmitIntValue(0, 1);
758 // Now set the value of the symbol at the end of the info section.
759 MCOS->EmitLabel(InfoEnd);
763 // When generating dwarf for assembly source files this emits the Dwarf
766 void MCGenDwarfInfo::Emit(MCStreamer *MCOS, const MCSymbol *LineSectionSymbol) {
767 // Create the dwarf sections in this order (.debug_line already created).
768 MCContext &context = MCOS->getContext();
769 const MCAsmInfo *AsmInfo = context.getAsmInfo();
770 bool CreateDwarfSectionSymbols =
771 AsmInfo->doesDwarfUseRelocationsAcrossSections();
772 if (!CreateDwarfSectionSymbols)
773 LineSectionSymbol = NULL;
774 MCSymbol *AbbrevSectionSymbol = NULL;
775 MCSymbol *InfoSectionSymbol = NULL;
776 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
777 if (CreateDwarfSectionSymbols) {
778 InfoSectionSymbol = context.CreateTempSymbol();
779 MCOS->EmitLabel(InfoSectionSymbol);
781 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
782 if (CreateDwarfSectionSymbols) {
783 AbbrevSectionSymbol = context.CreateTempSymbol();
784 MCOS->EmitLabel(AbbrevSectionSymbol);
786 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
788 // If there are no line table entries then do not emit any section contents.
789 if (!context.hasMCLineSections())
792 // Output the data for .debug_aranges section.
793 EmitGenDwarfAranges(MCOS, InfoSectionSymbol);
795 // Output the data for .debug_abbrev section.
796 EmitGenDwarfAbbrev(MCOS);
798 // Output the data for .debug_info section.
799 EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol);
803 // When generating dwarf for assembly source files this is called when symbol
804 // for a label is created. If this symbol is not a temporary and is in the
805 // section that dwarf is being generated for, save the needed info to create
808 void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
809 SourceMgr &SrcMgr, SMLoc &Loc) {
810 // We won't create dwarf labels for temporary symbols or symbols not in
812 if (Symbol->isTemporary())
814 MCContext &context = MCOS->getContext();
815 if (context.getGenDwarfSection() != MCOS->getCurrentSection().first)
818 // The dwarf label's name does not have the symbol name's leading
820 StringRef Name = Symbol->getName();
821 if (Name.startswith("_"))
822 Name = Name.substr(1, Name.size()-1);
824 // Get the dwarf file number to be used for the dwarf label.
825 unsigned FileNumber = context.getGenDwarfFileNumber();
827 // Finding the line number is the expensive part which is why we just don't
828 // pass it in as for some symbols we won't create a dwarf label.
829 int CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
830 unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
832 // We create a temporary symbol for use for the AT_high_pc and AT_low_pc
833 // values so that they don't have things like an ARM thumb bit from the
834 // original symbol. So when used they won't get a low bit set after
836 MCSymbol *Label = context.CreateTempSymbol();
837 MCOS->EmitLabel(Label);
839 // Create and entry for the info and add it to the other entries.
840 MCGenDwarfLabelEntry *Entry =
841 new MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label);
842 MCOS->getContext().addMCGenDwarfLabelEntry(Entry);
845 static int getDataAlignmentFactor(MCStreamer &streamer) {
846 MCContext &context = streamer.getContext();
847 const MCAsmInfo *asmInfo = context.getAsmInfo();
848 int size = asmInfo->getCalleeSaveStackSlotSize();
849 if (asmInfo->isStackGrowthDirectionUp())
855 static unsigned getSizeForEncoding(MCStreamer &streamer,
856 unsigned symbolEncoding) {
857 MCContext &context = streamer.getContext();
858 unsigned format = symbolEncoding & 0x0f;
860 default: llvm_unreachable("Unknown Encoding");
861 case dwarf::DW_EH_PE_absptr:
862 case dwarf::DW_EH_PE_signed:
863 return context.getAsmInfo()->getPointerSize();
864 case dwarf::DW_EH_PE_udata2:
865 case dwarf::DW_EH_PE_sdata2:
867 case dwarf::DW_EH_PE_udata4:
868 case dwarf::DW_EH_PE_sdata4:
870 case dwarf::DW_EH_PE_udata8:
871 case dwarf::DW_EH_PE_sdata8:
876 static void EmitFDESymbol(MCStreamer &streamer, const MCSymbol &symbol,
877 unsigned symbolEncoding, bool isEH,
878 const char *comment = 0) {
879 MCContext &context = streamer.getContext();
880 const MCAsmInfo *asmInfo = context.getAsmInfo();
881 const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol,
884 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
885 if (streamer.isVerboseAsm() && comment) streamer.AddComment(comment);
886 if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH)
887 streamer.EmitAbsValue(v, size);
889 streamer.EmitValue(v, size);
892 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
893 unsigned symbolEncoding) {
894 MCContext &context = streamer.getContext();
895 const MCAsmInfo *asmInfo = context.getAsmInfo();
896 const MCExpr *v = asmInfo->getExprForPersonalitySymbol(&symbol,
899 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
900 streamer.EmitValue(v, size);
904 class FrameEmitterImpl {
909 const MCSymbol *SectionStart;
911 FrameEmitterImpl(bool usingCFI, bool isEH)
912 : CFAOffset(0), CIENum(0), UsingCFI(usingCFI), IsEH(isEH),
915 void setSectionStart(const MCSymbol *Label) { SectionStart = Label; }
917 /// EmitCompactUnwind - Emit the unwind information in a compact way.
918 void EmitCompactUnwind(MCStreamer &streamer,
919 const MCDwarfFrameInfo &frame);
921 const MCSymbol &EmitCIE(MCStreamer &streamer,
922 const MCSymbol *personality,
923 unsigned personalityEncoding,
924 const MCSymbol *lsda,
926 unsigned lsdaEncoding,
928 MCSymbol *EmitFDE(MCStreamer &streamer,
929 const MCSymbol &cieStart,
930 const MCDwarfFrameInfo &frame);
931 void EmitCFIInstructions(MCStreamer &streamer,
932 ArrayRef<MCCFIInstruction> Instrs,
933 MCSymbol *BaseLabel);
934 void EmitCFIInstruction(MCStreamer &Streamer,
935 const MCCFIInstruction &Instr);
938 } // end anonymous namespace
940 static void EmitEncodingByte(MCStreamer &Streamer, unsigned Encoding,
942 if (Streamer.isVerboseAsm()) {
945 default: EncStr = "<unknown encoding>"; break;
946 case dwarf::DW_EH_PE_absptr: EncStr = "absptr"; break;
947 case dwarf::DW_EH_PE_omit: EncStr = "omit"; break;
948 case dwarf::DW_EH_PE_pcrel: EncStr = "pcrel"; break;
949 case dwarf::DW_EH_PE_udata4: EncStr = "udata4"; break;
950 case dwarf::DW_EH_PE_udata8: EncStr = "udata8"; break;
951 case dwarf::DW_EH_PE_sdata4: EncStr = "sdata4"; break;
952 case dwarf::DW_EH_PE_sdata8: EncStr = "sdata8"; break;
953 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
954 EncStr = "pcrel udata4";
956 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
957 EncStr = "pcrel sdata4";
959 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
960 EncStr = "pcrel udata8";
962 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
963 EncStr = "screl sdata8";
965 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata4:
966 EncStr = "indirect pcrel udata4";
968 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata4:
969 EncStr = "indirect pcrel sdata4";
971 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata8:
972 EncStr = "indirect pcrel udata8";
974 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata8:
975 EncStr = "indirect pcrel sdata8";
979 Streamer.AddComment(Twine(Prefix) + " = " + EncStr);
982 Streamer.EmitIntValue(Encoding, 1);
985 void FrameEmitterImpl::EmitCFIInstruction(MCStreamer &Streamer,
986 const MCCFIInstruction &Instr) {
987 int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
988 bool VerboseAsm = Streamer.isVerboseAsm();
990 switch (Instr.getOperation()) {
991 case MCCFIInstruction::OpRegister: {
992 unsigned Reg1 = Instr.getRegister();
993 unsigned Reg2 = Instr.getRegister2();
995 Streamer.AddComment("DW_CFA_register");
996 Streamer.AddComment(Twine("Reg1 ") + Twine(Reg1));
997 Streamer.AddComment(Twine("Reg2 ") + Twine(Reg2));
999 Streamer.EmitIntValue(dwarf::DW_CFA_register, 1);
1000 Streamer.EmitULEB128IntValue(Reg1);
1001 Streamer.EmitULEB128IntValue(Reg2);
1004 case MCCFIInstruction::OpWindowSave: {
1005 Streamer.EmitIntValue(dwarf::DW_CFA_GNU_window_save, 1);
1008 case MCCFIInstruction::OpUndefined: {
1009 unsigned Reg = Instr.getRegister();
1011 Streamer.AddComment("DW_CFA_undefined");
1012 Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1014 Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1);
1015 Streamer.EmitULEB128IntValue(Reg);
1018 case MCCFIInstruction::OpAdjustCfaOffset:
1019 case MCCFIInstruction::OpDefCfaOffset: {
1020 const bool IsRelative =
1021 Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset;
1024 Streamer.AddComment("DW_CFA_def_cfa_offset");
1025 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
1028 CFAOffset += Instr.getOffset();
1030 CFAOffset = -Instr.getOffset();
1033 Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
1034 Streamer.EmitULEB128IntValue(CFAOffset);
1038 case MCCFIInstruction::OpDefCfa: {
1040 Streamer.AddComment("DW_CFA_def_cfa");
1041 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
1044 Streamer.AddComment(Twine("Reg ") + Twine(Instr.getRegister()));
1045 Streamer.EmitULEB128IntValue(Instr.getRegister());
1047 CFAOffset = -Instr.getOffset();
1050 Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
1051 Streamer.EmitULEB128IntValue(CFAOffset);
1056 case MCCFIInstruction::OpDefCfaRegister: {
1058 Streamer.AddComment("DW_CFA_def_cfa_register");
1059 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
1062 Streamer.AddComment(Twine("Reg ") + Twine(Instr.getRegister()));
1063 Streamer.EmitULEB128IntValue(Instr.getRegister());
1068 case MCCFIInstruction::OpOffset:
1069 case MCCFIInstruction::OpRelOffset: {
1070 const bool IsRelative =
1071 Instr.getOperation() == MCCFIInstruction::OpRelOffset;
1073 unsigned Reg = Instr.getRegister();
1074 int Offset = Instr.getOffset();
1076 Offset -= CFAOffset;
1077 Offset = Offset / dataAlignmentFactor;
1080 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended_sf");
1081 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
1082 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1083 Streamer.EmitULEB128IntValue(Reg);
1084 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1085 Streamer.EmitSLEB128IntValue(Offset);
1086 } else if (Reg < 64) {
1087 if (VerboseAsm) Streamer.AddComment(Twine("DW_CFA_offset + Reg(") +
1089 Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
1090 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1091 Streamer.EmitULEB128IntValue(Offset);
1093 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended");
1094 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
1095 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1096 Streamer.EmitULEB128IntValue(Reg);
1097 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1098 Streamer.EmitULEB128IntValue(Offset);
1102 case MCCFIInstruction::OpRememberState:
1103 if (VerboseAsm) Streamer.AddComment("DW_CFA_remember_state");
1104 Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
1106 case MCCFIInstruction::OpRestoreState:
1107 if (VerboseAsm) Streamer.AddComment("DW_CFA_restore_state");
1108 Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
1110 case MCCFIInstruction::OpSameValue: {
1111 unsigned Reg = Instr.getRegister();
1112 if (VerboseAsm) Streamer.AddComment("DW_CFA_same_value");
1113 Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
1114 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1115 Streamer.EmitULEB128IntValue(Reg);
1118 case MCCFIInstruction::OpRestore: {
1119 unsigned Reg = Instr.getRegister();
1121 Streamer.AddComment("DW_CFA_restore");
1122 Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1124 Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1);
1127 case MCCFIInstruction::OpEscape:
1128 if (VerboseAsm) Streamer.AddComment("Escape bytes");
1129 Streamer.EmitBytes(Instr.getValues());
1132 llvm_unreachable("Unhandled case in switch");
1135 /// EmitFrameMoves - Emit frame instructions to describe the layout of the
1137 void FrameEmitterImpl::EmitCFIInstructions(MCStreamer &streamer,
1138 ArrayRef<MCCFIInstruction> Instrs,
1139 MCSymbol *BaseLabel) {
1140 for (unsigned i = 0, N = Instrs.size(); i < N; ++i) {
1141 const MCCFIInstruction &Instr = Instrs[i];
1142 MCSymbol *Label = Instr.getLabel();
1143 // Throw out move if the label is invalid.
1144 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
1146 // Advance row if new location.
1147 if (BaseLabel && Label) {
1148 MCSymbol *ThisSym = Label;
1149 if (ThisSym != BaseLabel) {
1150 if (streamer.isVerboseAsm()) streamer.AddComment("DW_CFA_advance_loc4");
1151 streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
1152 BaseLabel = ThisSym;
1156 EmitCFIInstruction(streamer, Instr);
1160 /// EmitCompactUnwind - Emit the unwind information in a compact way.
1161 void FrameEmitterImpl::EmitCompactUnwind(MCStreamer &Streamer,
1162 const MCDwarfFrameInfo &Frame) {
1163 MCContext &Context = Streamer.getContext();
1164 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1165 bool VerboseAsm = Streamer.isVerboseAsm();
1167 // range-start range-length compact-unwind-enc personality-func lsda
1168 // _foo LfooEnd-_foo 0x00000023 0 0
1169 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1
1171 // .section __LD,__compact_unwind,regular,debug
1173 // # compact unwind for _foo
1175 // .set L1,LfooEnd-_foo
1181 // # compact unwind for _bar
1183 // .set L2,LbarEnd-_bar
1186 // .quad __gxx_personality
1187 // .quad except_tab1
1189 uint32_t Encoding = Frame.CompactUnwindEncoding;
1190 if (!Encoding) return;
1191 bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly());
1193 // The encoding needs to know we have an LSDA.
1194 if (!DwarfEHFrameOnly && Frame.Lsda)
1195 Encoding |= 0x40000000;
1198 unsigned FDEEncoding = MOFI->getFDEEncoding(UsingCFI);
1199 unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
1200 if (VerboseAsm) Streamer.AddComment("Range Start");
1201 Streamer.EmitSymbolValue(Frame.Function, Size);
1204 const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin,
1206 if (VerboseAsm) Streamer.AddComment("Range Length");
1207 Streamer.EmitAbsValue(Range, 4);
1210 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
1211 if (VerboseAsm) Streamer.AddComment("Compact Unwind Encoding: 0x" +
1212 Twine::utohexstr(Encoding));
1213 Streamer.EmitIntValue(Encoding, Size);
1215 // Personality Function
1216 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
1217 if (VerboseAsm) Streamer.AddComment("Personality Function");
1218 if (!DwarfEHFrameOnly && Frame.Personality)
1219 Streamer.EmitSymbolValue(Frame.Personality, Size);
1221 Streamer.EmitIntValue(0, Size); // No personality fn
1224 Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
1225 if (VerboseAsm) Streamer.AddComment("LSDA");
1226 if (!DwarfEHFrameOnly && Frame.Lsda)
1227 Streamer.EmitSymbolValue(Frame.Lsda, Size);
1229 Streamer.EmitIntValue(0, Size); // No LSDA
1232 const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
1233 const MCSymbol *personality,
1234 unsigned personalityEncoding,
1235 const MCSymbol *lsda,
1237 unsigned lsdaEncoding,
1239 MCContext &context = streamer.getContext();
1240 const MCRegisterInfo *MRI = context.getRegisterInfo();
1241 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1242 bool verboseAsm = streamer.isVerboseAsm();
1244 MCSymbol *sectionStart;
1245 if (MOFI->isFunctionEHFrameSymbolPrivate() || !IsEH)
1246 sectionStart = context.CreateTempSymbol();
1248 sectionStart = context.GetOrCreateSymbol(Twine("EH_frame") + Twine(CIENum));
1250 streamer.EmitLabel(sectionStart);
1253 MCSymbol *sectionEnd = context.CreateTempSymbol();
1256 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *sectionStart,
1258 if (verboseAsm) streamer.AddComment("CIE Length");
1259 streamer.EmitAbsValue(Length, 4);
1262 unsigned CIE_ID = IsEH ? 0 : -1;
1263 if (verboseAsm) streamer.AddComment("CIE ID Tag");
1264 streamer.EmitIntValue(CIE_ID, 4);
1267 if (verboseAsm) streamer.AddComment("DW_CIE_VERSION");
1268 streamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1);
1270 // Augmentation String
1271 SmallString<8> Augmentation;
1273 if (verboseAsm) streamer.AddComment("CIE Augmentation");
1274 Augmentation += "z";
1276 Augmentation += "P";
1278 Augmentation += "L";
1279 Augmentation += "R";
1281 Augmentation += "S";
1282 streamer.EmitBytes(Augmentation.str());
1284 streamer.EmitIntValue(0, 1);
1286 // Code Alignment Factor
1287 if (verboseAsm) streamer.AddComment("CIE Code Alignment Factor");
1288 streamer.EmitULEB128IntValue(context.getAsmInfo()->getMinInstAlignment());
1290 // Data Alignment Factor
1291 if (verboseAsm) streamer.AddComment("CIE Data Alignment Factor");
1292 streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer));
1294 // Return Address Register
1295 if (verboseAsm) streamer.AddComment("CIE Return Address Column");
1296 streamer.EmitULEB128IntValue(MRI->getDwarfRegNum(MRI->getRARegister(), true));
1298 // Augmentation Data Length (optional)
1300 unsigned augmentationLength = 0;
1303 // Personality Encoding
1304 augmentationLength += 1;
1306 augmentationLength += getSizeForEncoding(streamer, personalityEncoding);
1309 augmentationLength += 1;
1310 // Encoding of the FDE pointers
1311 augmentationLength += 1;
1313 if (verboseAsm) streamer.AddComment("Augmentation Size");
1314 streamer.EmitULEB128IntValue(augmentationLength);
1316 // Augmentation Data (optional)
1318 // Personality Encoding
1319 EmitEncodingByte(streamer, personalityEncoding,
1320 "Personality Encoding");
1322 if (verboseAsm) streamer.AddComment("Personality");
1323 EmitPersonality(streamer, *personality, personalityEncoding);
1327 EmitEncodingByte(streamer, lsdaEncoding, "LSDA Encoding");
1329 // Encoding of the FDE pointers
1330 EmitEncodingByte(streamer, MOFI->getFDEEncoding(UsingCFI),
1334 // Initial Instructions
1336 const MCAsmInfo *MAI = context.getAsmInfo();
1338 const std::vector<MCCFIInstruction> &Instructions =
1339 MAI->getInitialFrameState();
1340 EmitCFIInstructions(streamer, Instructions, NULL);
1344 streamer.EmitValueToAlignment(IsEH ? 4 : MAI->getPointerSize());
1346 streamer.EmitLabel(sectionEnd);
1347 return *sectionStart;
1350 MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
1351 const MCSymbol &cieStart,
1352 const MCDwarfFrameInfo &frame) {
1353 MCContext &context = streamer.getContext();
1354 MCSymbol *fdeStart = context.CreateTempSymbol();
1355 MCSymbol *fdeEnd = context.CreateTempSymbol();
1356 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1357 bool verboseAsm = streamer.isVerboseAsm();
1359 if (IsEH && frame.Function && !MOFI->isFunctionEHFrameSymbolPrivate()) {
1361 context.GetOrCreateSymbol(frame.Function->getName() + Twine(".eh"));
1362 streamer.EmitEHSymAttributes(frame.Function, EHSym);
1363 streamer.EmitLabel(EHSym);
1367 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *fdeStart, *fdeEnd, 0);
1368 if (verboseAsm) streamer.AddComment("FDE Length");
1369 streamer.EmitAbsValue(Length, 4);
1371 streamer.EmitLabel(fdeStart);
1374 const MCAsmInfo *asmInfo = context.getAsmInfo();
1376 const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart,
1378 if (verboseAsm) streamer.AddComment("FDE CIE Offset");
1379 streamer.EmitAbsValue(offset, 4);
1380 } else if (!asmInfo->doesDwarfUseRelocationsAcrossSections()) {
1381 const MCExpr *offset = MakeStartMinusEndExpr(streamer, *SectionStart,
1383 streamer.EmitAbsValue(offset, 4);
1385 streamer.EmitSymbolValue(&cieStart, 4);
1389 unsigned PCEncoding = IsEH ? MOFI->getFDEEncoding(UsingCFI)
1390 : (unsigned)dwarf::DW_EH_PE_absptr;
1391 unsigned PCSize = getSizeForEncoding(streamer, PCEncoding);
1392 EmitFDESymbol(streamer, *frame.Begin, PCEncoding, IsEH, "FDE initial location");
1395 const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin,
1397 if (verboseAsm) streamer.AddComment("FDE address range");
1398 streamer.EmitAbsValue(Range, PCSize);
1401 // Augmentation Data Length
1402 unsigned augmentationLength = 0;
1405 augmentationLength += getSizeForEncoding(streamer, frame.LsdaEncoding);
1407 if (verboseAsm) streamer.AddComment("Augmentation size");
1408 streamer.EmitULEB128IntValue(augmentationLength);
1410 // Augmentation Data
1412 EmitFDESymbol(streamer, *frame.Lsda, frame.LsdaEncoding, true,
1413 "Language Specific Data Area");
1416 // Call Frame Instructions
1417 EmitCFIInstructions(streamer, frame.Instructions, frame.Begin);
1420 streamer.EmitValueToAlignment(PCSize);
1427 static const CIEKey getEmptyKey() { return CIEKey(0, 0, -1, false, false); }
1428 static const CIEKey getTombstoneKey() { return CIEKey(0, -1, 0, false, false); }
1430 CIEKey(const MCSymbol* Personality_, unsigned PersonalityEncoding_,
1431 unsigned LsdaEncoding_, bool IsSignalFrame_, bool IsSimple_) :
1432 Personality(Personality_), PersonalityEncoding(PersonalityEncoding_),
1433 LsdaEncoding(LsdaEncoding_), IsSignalFrame(IsSignalFrame_),
1434 IsSimple(IsSimple_) {
1436 const MCSymbol* Personality;
1437 unsigned PersonalityEncoding;
1438 unsigned LsdaEncoding;
1446 struct DenseMapInfo<CIEKey> {
1447 static CIEKey getEmptyKey() {
1448 return CIEKey::getEmptyKey();
1450 static CIEKey getTombstoneKey() {
1451 return CIEKey::getTombstoneKey();
1453 static unsigned getHashValue(const CIEKey &Key) {
1454 return static_cast<unsigned>(hash_combine(Key.Personality,
1455 Key.PersonalityEncoding,
1460 static bool isEqual(const CIEKey &LHS,
1461 const CIEKey &RHS) {
1462 return LHS.Personality == RHS.Personality &&
1463 LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
1464 LHS.LsdaEncoding == RHS.LsdaEncoding &&
1465 LHS.IsSignalFrame == RHS.IsSignalFrame &&
1466 LHS.IsSimple == RHS.IsSimple;
1471 void MCDwarfFrameEmitter::Emit(MCStreamer &Streamer, MCAsmBackend *MAB,
1472 bool UsingCFI, bool IsEH) {
1473 Streamer.generateCompactUnwindEncodings(MAB);
1475 MCContext &Context = Streamer.getContext();
1476 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1477 FrameEmitterImpl Emitter(UsingCFI, IsEH);
1478 ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getFrameInfos();
1480 // Emit the compact unwind info if available.
1481 if (IsEH && MOFI->getCompactUnwindSection()) {
1482 bool SectionEmitted = false;
1483 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
1484 const MCDwarfFrameInfo &Frame = FrameArray[i];
1485 if (Frame.CompactUnwindEncoding == 0) continue;
1486 if (!SectionEmitted) {
1487 Streamer.SwitchSection(MOFI->getCompactUnwindSection());
1488 Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize());
1489 SectionEmitted = true;
1491 Emitter.EmitCompactUnwind(Streamer, Frame);
1495 const MCSection &Section =
1496 IsEH ? *const_cast<MCObjectFileInfo*>(MOFI)->getEHFrameSection() :
1497 *MOFI->getDwarfFrameSection();
1498 Streamer.SwitchSection(&Section);
1499 MCSymbol *SectionStart = Context.CreateTempSymbol();
1500 Streamer.EmitLabel(SectionStart);
1501 Emitter.setSectionStart(SectionStart);
1503 MCSymbol *FDEEnd = NULL;
1504 DenseMap<CIEKey, const MCSymbol*> CIEStarts;
1506 const MCSymbol *DummyDebugKey = NULL;
1507 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
1508 const MCDwarfFrameInfo &Frame = FrameArray[i];
1509 CIEKey Key(Frame.Personality, Frame.PersonalityEncoding,
1510 Frame.LsdaEncoding, Frame.IsSignalFrame, Frame.IsSimple);
1511 const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
1513 CIEStart = &Emitter.EmitCIE(Streamer, Frame.Personality,
1514 Frame.PersonalityEncoding, Frame.Lsda,
1515 Frame.IsSignalFrame,
1519 FDEEnd = Emitter.EmitFDE(Streamer, *CIEStart, Frame);
1522 Streamer.EmitLabel(FDEEnd);
1525 Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize());
1527 Streamer.EmitLabel(FDEEnd);
1530 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCStreamer &Streamer,
1531 uint64_t AddrDelta) {
1532 MCContext &Context = Streamer.getContext();
1533 SmallString<256> Tmp;
1534 raw_svector_ostream OS(Tmp);
1535 MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OS);
1536 Streamer.EmitBytes(OS.str());
1539 void MCDwarfFrameEmitter::EncodeAdvanceLoc(MCContext &Context,
1542 // Scale the address delta by the minimum instruction length.
1543 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
1545 if (AddrDelta == 0) {
1546 } else if (isUIntN(6, AddrDelta)) {
1547 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
1549 } else if (isUInt<8>(AddrDelta)) {
1550 OS << uint8_t(dwarf::DW_CFA_advance_loc1);
1551 OS << uint8_t(AddrDelta);
1552 } else if (isUInt<16>(AddrDelta)) {
1553 // FIXME: check what is the correct behavior on a big endian machine.
1554 OS << uint8_t(dwarf::DW_CFA_advance_loc2);
1555 OS << uint8_t( AddrDelta & 0xff);
1556 OS << uint8_t((AddrDelta >> 8) & 0xff);
1558 // FIXME: check what is the correct behavior on a big endian machine.
1559 assert(isUInt<32>(AddrDelta));
1560 OS << uint8_t(dwarf::DW_CFA_advance_loc4);
1561 OS << uint8_t( AddrDelta & 0xff);
1562 OS << uint8_t((AddrDelta >> 8) & 0xff);
1563 OS << uint8_t((AddrDelta >> 16) & 0xff);
1564 OS << uint8_t((AddrDelta >> 24) & 0xff);