1 //===- lib/MC/MCDwarf.cpp - MCDwarf implementation ------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "llvm/MC/MCDwarf.h"
11 #include "llvm/ADT/Hashing.h"
12 #include "llvm/ADT/SmallString.h"
13 #include "llvm/ADT/Twine.h"
14 #include "llvm/Config/config.h"
15 #include "llvm/MC/MCAsmInfo.h"
16 #include "llvm/MC/MCContext.h"
17 #include "llvm/MC/MCExpr.h"
18 #include "llvm/MC/MCObjectFileInfo.h"
19 #include "llvm/MC/MCRegisterInfo.h"
20 #include "llvm/MC/MCStreamer.h"
21 #include "llvm/MC/MCSymbol.h"
22 #include "llvm/Support/Debug.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Support/LEB128.h"
25 #include "llvm/Support/Path.h"
26 #include "llvm/Support/SourceMgr.h"
27 #include "llvm/Support/raw_ostream.h"
30 // Given a special op, return the address skip amount (in units of
31 // DWARF2_LINE_MIN_INSN_LENGTH.
32 #define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE)
34 // The maximum address skip amount that can be encoded with a special op.
35 #define MAX_SPECIAL_ADDR_DELTA SPECIAL_ADDR(255)
37 // First special line opcode - leave room for the standard opcodes.
38 // Note: If you want to change this, you'll have to update the
39 // "standard_opcode_lengths" table that is emitted in DwarfFileTable::Emit().
40 #define DWARF2_LINE_OPCODE_BASE 13
42 // Minimum line offset in a special line info. opcode. This value
43 // was chosen to give a reasonable range of values.
44 #define DWARF2_LINE_BASE -5
46 // Range of line offsets in a special line info. opcode.
47 #define DWARF2_LINE_RANGE 14
49 static inline uint64_t ScaleAddrDelta(MCContext &Context, uint64_t AddrDelta) {
50 unsigned MinInsnLength = Context.getAsmInfo()->getMinInstAlignment();
51 if (MinInsnLength == 1)
53 if (AddrDelta % MinInsnLength != 0) {
54 // TODO: report this error, but really only once.
57 return AddrDelta / MinInsnLength;
61 // This is called when an instruction is assembled into the specified section
62 // and if there is information from the last .loc directive that has yet to have
63 // a line entry made for it is made.
65 void MCLineEntry::Make(MCStreamer *MCOS, const MCSection *Section) {
66 if (!MCOS->getContext().getDwarfLocSeen())
69 // Create a symbol at in the current section for use in the line entry.
70 MCSymbol *LineSym = MCOS->getContext().CreateTempSymbol();
71 // Set the value of the symbol to use for the MCLineEntry.
72 MCOS->EmitLabel(LineSym);
74 // Get the current .loc info saved in the context.
75 const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();
77 // Create a (local) line entry with the symbol and the current .loc info.
78 MCLineEntry LineEntry(LineSym, DwarfLoc);
80 // clear DwarfLocSeen saying the current .loc info is now used.
81 MCOS->getContext().ClearDwarfLocSeen();
83 // Add the line entry to this section's entries.
85 .getMCDwarfLineTable(MCOS->getContext().getDwarfCompileUnitID())
87 .addLineEntry(LineEntry, Section);
91 // This helper routine returns an expression of End - Start + IntVal .
93 static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS,
94 const MCSymbol &Start,
97 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
99 MCSymbolRefExpr::Create(&End, Variant, MCOS.getContext());
101 MCSymbolRefExpr::Create(&Start, Variant, MCOS.getContext());
103 MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext());
105 MCConstantExpr::Create(IntVal, MCOS.getContext());
107 MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext());
112 // This emits the Dwarf line table for the specified section from the entries
113 // in the LineSection.
116 EmitDwarfLineTable(MCStreamer *MCOS, const MCSection *Section,
117 const MCLineSection::MCLineEntryCollection &LineEntries) {
118 unsigned FileNum = 1;
119 unsigned LastLine = 1;
121 unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
123 unsigned Discriminator = 0;
124 MCSymbol *LastLabel = NULL;
126 // Loop through each MCLineEntry and encode the dwarf line number table.
127 for (auto it = LineEntries.begin(),
128 ie = LineEntries.end();
131 if (FileNum != it->getFileNum()) {
132 FileNum = it->getFileNum();
133 MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
134 MCOS->EmitULEB128IntValue(FileNum);
136 if (Column != it->getColumn()) {
137 Column = it->getColumn();
138 MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
139 MCOS->EmitULEB128IntValue(Column);
141 if (Discriminator != it->getDiscriminator()) {
142 Discriminator = it->getDiscriminator();
143 unsigned Size = getULEB128Size(Discriminator);
144 MCOS->EmitIntValue(dwarf::DW_LNS_extended_op, 1);
145 MCOS->EmitULEB128IntValue(Size + 1);
146 MCOS->EmitIntValue(dwarf::DW_LNE_set_discriminator, 1);
147 MCOS->EmitULEB128IntValue(Discriminator);
149 if (Isa != it->getIsa()) {
151 MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
152 MCOS->EmitULEB128IntValue(Isa);
154 if ((it->getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
155 Flags = it->getFlags();
156 MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
158 if (it->getFlags() & DWARF2_FLAG_BASIC_BLOCK)
159 MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
160 if (it->getFlags() & DWARF2_FLAG_PROLOGUE_END)
161 MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
162 if (it->getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
163 MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
165 int64_t LineDelta = static_cast<int64_t>(it->getLine()) - LastLine;
166 MCSymbol *Label = it->getLabel();
168 // At this point we want to emit/create the sequence to encode the delta in
169 // line numbers and the increment of the address from the previous Label
170 // and the current Label.
171 const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo();
172 MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label,
173 asmInfo->getPointerSize());
175 LastLine = it->getLine();
179 // Emit a DW_LNE_end_sequence for the end of the section.
180 // Using the pointer Section create a temporary label at the end of the
181 // section and use that and the LastLabel to compute the address delta
182 // and use INT64_MAX as the line delta which is the signal that this is
183 // actually a DW_LNE_end_sequence.
185 // Switch to the section to be able to create a symbol at its end.
186 // TODO: keep track of the last subsection so that this symbol appears in the
188 MCOS->SwitchSection(Section);
190 MCContext &context = MCOS->getContext();
191 // Create a symbol at the end of the section.
192 MCSymbol *SectionEnd = context.CreateTempSymbol();
193 // Set the value of the symbol, as we are at the end of the section.
194 MCOS->EmitLabel(SectionEnd);
196 // Switch back the dwarf line section.
197 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
199 const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo();
200 MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd,
201 asmInfo->getPointerSize());
205 // This emits the Dwarf file and the line tables.
207 const MCSymbol *MCDwarfLineTable::Emit(MCStreamer *MCOS) {
208 MCContext &context = MCOS->getContext();
210 // CUID and MCLineTableSymbols are set in DwarfDebug, when DwarfDebug does
211 // not exist, CUID will be 0 and MCLineTableSymbols will be empty.
212 // Handle Compile Unit 0, the line table start symbol is the section symbol.
213 auto I = MCOS->getContext().getMCDwarfLineTables().begin(),
214 E = MCOS->getContext().getMCDwarfLineTables().end();
216 // Switch to the section where the table will be emitted into.
217 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
219 const MCSymbol *LineStartSym = I->second.EmitCU(MCOS);
220 // Handle the rest of the Compile Units.
221 for (++I; I != E; ++I)
222 I->second.EmitCU(MCOS);
227 std::pair<MCSymbol *, MCSymbol *> MCDwarfLineTableHeader::Emit(MCStreamer *MCOS) const {
228 MCContext &context = MCOS->getContext();
230 // Create a symbol at the beginning of the line table.
231 MCSymbol *LineStartSym = Label;
233 LineStartSym = context.CreateTempSymbol();
234 // Set the value of the symbol, as we are at the start of the line table.
235 MCOS->EmitLabel(LineStartSym);
237 // Create a symbol for the end of the section (to be set when we get there).
238 MCSymbol *LineEndSym = context.CreateTempSymbol();
240 // The first 4 bytes is the total length of the information for this
241 // compilation unit (not including these 4 bytes for the length).
242 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym,4),
245 // Next 2 bytes is the Version, which is Dwarf 2.
246 MCOS->EmitIntValue(2, 2);
248 // Create a symbol for the end of the prologue (to be set when we get there).
249 MCSymbol *ProEndSym = context.CreateTempSymbol(); // Lprologue_end
251 // Length of the prologue, is the next 4 bytes. Which is the start of the
252 // section to the end of the prologue. Not including the 4 bytes for the
253 // total length, the 2 bytes for the version, and these 4 bytes for the
254 // length of the prologue.
255 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym,
258 // Parameters of the state machine, are next.
259 MCOS->EmitIntValue(context.getAsmInfo()->getMinInstAlignment(), 1);
260 MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
261 MCOS->EmitIntValue(DWARF2_LINE_BASE, 1);
262 MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1);
263 MCOS->EmitIntValue(DWARF2_LINE_OPCODE_BASE, 1);
265 // Standard opcode lengths
266 MCOS->EmitIntValue(0, 1); // length of DW_LNS_copy
267 MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_pc
268 MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_line
269 MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_file
270 MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_column
271 MCOS->EmitIntValue(0, 1); // length of DW_LNS_negate_stmt
272 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_basic_block
273 MCOS->EmitIntValue(0, 1); // length of DW_LNS_const_add_pc
274 MCOS->EmitIntValue(1, 1); // length of DW_LNS_fixed_advance_pc
275 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_prologue_end
276 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_epilogue_begin
277 MCOS->EmitIntValue(1, 1); // DW_LNS_set_isa
279 // Put out the directory and file tables.
281 // First the directory table.
282 for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
283 MCOS->EmitBytes(MCDwarfDirs[i]); // the DirectoryName
284 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
286 MCOS->EmitIntValue(0, 1); // Terminate the directory list
288 // Second the file table.
289 for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
290 assert(!MCDwarfFiles[i].Name.empty());
291 MCOS->EmitBytes(MCDwarfFiles[i].Name); // FileName
292 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
294 MCOS->EmitULEB128IntValue(MCDwarfFiles[i].DirIndex);
295 MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
296 MCOS->EmitIntValue(0, 1); // filesize (always 0)
298 MCOS->EmitIntValue(0, 1); // Terminate the file list
300 // This is the end of the prologue, so set the value of the symbol at the
301 // end of the prologue (that was used in a previous expression).
302 MCOS->EmitLabel(ProEndSym);
304 return std::make_pair(LineStartSym, LineEndSym);
307 const MCSymbol *MCDwarfLineTable::EmitCU(MCStreamer *MCOS) const {
308 MCSymbol *LineStartSym;
309 MCSymbol *LineEndSym;
310 std::tie(LineStartSym, LineEndSym) = Header.Emit(MCOS);
312 // Put out the line tables.
313 for (const auto &LineSec : MCLineSections.getMCLineEntries())
314 EmitDwarfLineTable(MCOS, LineSec.first, LineSec.second);
316 if (MCOS->getContext().getAsmInfo()->getLinkerRequiresNonEmptyDwarfLines() &&
317 MCLineSections.getMCLineEntries().empty()) {
318 // The darwin9 linker has a bug (see PR8715). For for 32-bit architectures
320 // total_length >= prologue_length + 10
321 // We are 4 bytes short, since we have total_length = 51 and
322 // prologue_length = 45
324 // The regular end_sequence should be sufficient.
325 MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
328 // This is the end of the section, so set the value of the symbol at the end
329 // of this section (that was used in a previous expression).
330 MCOS->EmitLabel(LineEndSym);
335 unsigned MCDwarfLineTable::getFile(StringRef &Directory, StringRef &FileName,
336 unsigned FileNumber) {
337 return Header.getFile(Directory, FileName, FileNumber);
340 unsigned MCDwarfLineTableHeader::getFile(StringRef &Directory,
342 unsigned FileNumber) {
343 if (Directory == CompilationDir)
345 if (FileName.empty()) {
346 FileName = "<stdin>";
349 assert(!FileName.empty());
350 if (FileNumber == 0) {
351 FileNumber = SourceIdMap.size() + 1;
352 assert((MCDwarfFiles.empty() || FileNumber == MCDwarfFiles.size()) &&
353 "Don't mix autonumbered and explicit numbered line table usage");
354 StringMapEntry<unsigned> &Ent = SourceIdMap.GetOrCreateValue(
355 (Directory + Twine('\0') + FileName).str(), FileNumber);
356 if (Ent.getValue() != FileNumber)
357 return Ent.getValue();
359 // Make space for this FileNumber in the MCDwarfFiles vector if needed.
360 MCDwarfFiles.resize(FileNumber + 1);
362 // Get the new MCDwarfFile slot for this FileNumber.
363 MCDwarfFile &File = MCDwarfFiles[FileNumber];
365 // It is an error to use see the same number more than once.
366 if (!File.Name.empty())
369 if (Directory.empty()) {
370 // Separate the directory part from the basename of the FileName.
371 StringRef tFileName = sys::path::filename(FileName);
372 if (!tFileName.empty()) {
373 Directory = sys::path::parent_path(FileName);
374 if (!Directory.empty())
375 FileName = tFileName;
379 // Find or make an entry in the MCDwarfDirs vector for this Directory.
380 // Capture directory name.
382 if (Directory.empty()) {
383 // For FileNames with no directories a DirIndex of 0 is used.
387 for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
388 if (Directory == MCDwarfDirs[DirIndex])
391 if (DirIndex >= MCDwarfDirs.size())
392 MCDwarfDirs.push_back(Directory);
393 // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
394 // no directories. MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
395 // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
396 // are stored at MCDwarfFiles[FileNumber].Name .
400 File.Name = FileName;
401 File.DirIndex = DirIndex;
403 // return the allocated FileNumber.
407 /// Utility function to emit the encoding to a streamer.
408 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta,
409 uint64_t AddrDelta) {
410 MCContext &Context = MCOS->getContext();
411 SmallString<256> Tmp;
412 raw_svector_ostream OS(Tmp);
413 MCDwarfLineAddr::Encode(Context, LineDelta, AddrDelta, OS);
414 MCOS->EmitBytes(OS.str());
417 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
418 void MCDwarfLineAddr::Encode(MCContext &Context, int64_t LineDelta,
419 uint64_t AddrDelta, raw_ostream &OS) {
420 uint64_t Temp, Opcode;
421 bool NeedCopy = false;
423 // Scale the address delta by the minimum instruction length.
424 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
426 // A LineDelta of INT64_MAX is a signal that this is actually a
427 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
428 // end_sequence to emit the matrix entry.
429 if (LineDelta == INT64_MAX) {
430 if (AddrDelta == MAX_SPECIAL_ADDR_DELTA)
431 OS << char(dwarf::DW_LNS_const_add_pc);
433 OS << char(dwarf::DW_LNS_advance_pc);
434 encodeULEB128(AddrDelta, OS);
436 OS << char(dwarf::DW_LNS_extended_op);
438 OS << char(dwarf::DW_LNE_end_sequence);
442 // Bias the line delta by the base.
443 Temp = LineDelta - DWARF2_LINE_BASE;
445 // If the line increment is out of range of a special opcode, we must encode
446 // it with DW_LNS_advance_line.
447 if (Temp >= DWARF2_LINE_RANGE) {
448 OS << char(dwarf::DW_LNS_advance_line);
449 encodeSLEB128(LineDelta, OS);
452 Temp = 0 - DWARF2_LINE_BASE;
456 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
457 if (LineDelta == 0 && AddrDelta == 0) {
458 OS << char(dwarf::DW_LNS_copy);
462 // Bias the opcode by the special opcode base.
463 Temp += DWARF2_LINE_OPCODE_BASE;
465 // Avoid overflow when addr_delta is large.
466 if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) {
467 // Try using a special opcode.
468 Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE;
474 // Try using DW_LNS_const_add_pc followed by special op.
475 Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
477 OS << char(dwarf::DW_LNS_const_add_pc);
483 // Otherwise use DW_LNS_advance_pc.
484 OS << char(dwarf::DW_LNS_advance_pc);
485 encodeULEB128(AddrDelta, OS);
488 OS << char(dwarf::DW_LNS_copy);
493 // Utility function to write a tuple for .debug_abbrev.
494 static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) {
495 MCOS->EmitULEB128IntValue(Name);
496 MCOS->EmitULEB128IntValue(Form);
499 // When generating dwarf for assembly source files this emits
500 // the data for .debug_abbrev section which contains three DIEs.
501 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
502 MCContext &context = MCOS->getContext();
503 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
505 // DW_TAG_compile_unit DIE abbrev (1).
506 MCOS->EmitULEB128IntValue(1);
507 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit);
508 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
509 EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4);
510 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
511 EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
512 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
513 if (!context.getCompilationDir().empty())
514 EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
515 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
516 if (!DwarfDebugFlags.empty())
517 EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
518 EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string);
519 EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2);
520 EmitAbbrev(MCOS, 0, 0);
522 // DW_TAG_label DIE abbrev (2).
523 MCOS->EmitULEB128IntValue(2);
524 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_label);
525 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
526 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
527 EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);
528 EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);
529 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
530 EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag);
531 EmitAbbrev(MCOS, 0, 0);
533 // DW_TAG_unspecified_parameters DIE abbrev (3).
534 MCOS->EmitULEB128IntValue(3);
535 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters);
536 MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1);
537 EmitAbbrev(MCOS, 0, 0);
539 // Terminate the abbreviations for this compilation unit.
540 MCOS->EmitIntValue(0, 1);
543 // When generating dwarf for assembly source files this emits the data for
544 // .debug_aranges section. Which contains a header and a table of pairs of
545 // PointerSize'ed values for the address and size of section(s) with line table
546 // entries (just the default .text in our case) and a terminating pair of zeros.
547 static void EmitGenDwarfAranges(MCStreamer *MCOS,
548 const MCSymbol *InfoSectionSymbol) {
549 MCContext &context = MCOS->getContext();
551 // Create a symbol at the end of the section that we are creating the dwarf
552 // debugging info to use later in here as part of the expression to calculate
553 // the size of the section for the table.
554 MCOS->SwitchSection(context.getGenDwarfSection());
555 MCSymbol *SectionEndSym = context.CreateTempSymbol();
556 MCOS->EmitLabel(SectionEndSym);
557 context.setGenDwarfSectionEndSym(SectionEndSym);
559 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
561 // This will be the length of the .debug_aranges section, first account for
562 // the size of each item in the header (see below where we emit these items).
563 int Length = 4 + 2 + 4 + 1 + 1;
565 // Figure the padding after the header before the table of address and size
566 // pairs who's values are PointerSize'ed.
567 const MCAsmInfo *asmInfo = context.getAsmInfo();
568 int AddrSize = asmInfo->getPointerSize();
569 int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1));
570 if (Pad == 2 * AddrSize)
574 // Add the size of the pair of PointerSize'ed values for the address and size
575 // of the one default .text section we have in the table.
576 Length += 2 * AddrSize;
577 // And the pair of terminating zeros.
578 Length += 2 * AddrSize;
581 // Emit the header for this section.
582 // The 4 byte length not including the 4 byte value for the length.
583 MCOS->EmitIntValue(Length - 4, 4);
584 // The 2 byte version, which is 2.
585 MCOS->EmitIntValue(2, 2);
586 // The 4 byte offset to the compile unit in the .debug_info from the start
587 // of the .debug_info.
588 if (InfoSectionSymbol)
589 MCOS->EmitSymbolValue(InfoSectionSymbol, 4);
591 MCOS->EmitIntValue(0, 4);
592 // The 1 byte size of an address.
593 MCOS->EmitIntValue(AddrSize, 1);
594 // The 1 byte size of a segment descriptor, we use a value of zero.
595 MCOS->EmitIntValue(0, 1);
596 // Align the header with the padding if needed, before we put out the table.
597 for(int i = 0; i < Pad; i++)
598 MCOS->EmitIntValue(0, 1);
600 // Now emit the table of pairs of PointerSize'ed values for the section(s)
601 // address and size, in our case just the one default .text section.
602 const MCExpr *Addr = MCSymbolRefExpr::Create(
603 context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
604 const MCExpr *Size = MakeStartMinusEndExpr(*MCOS,
605 *context.getGenDwarfSectionStartSym(), *SectionEndSym, 0);
606 MCOS->EmitAbsValue(Addr, AddrSize);
607 MCOS->EmitAbsValue(Size, AddrSize);
609 // And finally the pair of terminating zeros.
610 MCOS->EmitIntValue(0, AddrSize);
611 MCOS->EmitIntValue(0, AddrSize);
614 // When generating dwarf for assembly source files this emits the data for
615 // .debug_info section which contains three parts. The header, the compile_unit
616 // DIE and a list of label DIEs.
617 static void EmitGenDwarfInfo(MCStreamer *MCOS,
618 const MCSymbol *AbbrevSectionSymbol,
619 const MCSymbol *LineSectionSymbol) {
620 MCContext &context = MCOS->getContext();
622 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
624 // Create a symbol at the start and end of this section used in here for the
625 // expression to calculate the length in the header.
626 MCSymbol *InfoStart = context.CreateTempSymbol();
627 MCOS->EmitLabel(InfoStart);
628 MCSymbol *InfoEnd = context.CreateTempSymbol();
630 // First part: the header.
632 // The 4 byte total length of the information for this compilation unit, not
633 // including these 4 bytes.
634 const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4);
635 MCOS->EmitAbsValue(Length, 4);
637 // The 2 byte DWARF version, which is 2.
638 MCOS->EmitIntValue(2, 2);
640 // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev,
641 // it is at the start of that section so this is zero.
642 if (AbbrevSectionSymbol) {
643 MCOS->EmitSymbolValue(AbbrevSectionSymbol, 4);
645 MCOS->EmitIntValue(0, 4);
648 const MCAsmInfo *asmInfo = context.getAsmInfo();
649 int AddrSize = asmInfo->getPointerSize();
650 // The 1 byte size of an address.
651 MCOS->EmitIntValue(AddrSize, 1);
653 // Second part: the compile_unit DIE.
655 // The DW_TAG_compile_unit DIE abbrev (1).
656 MCOS->EmitULEB128IntValue(1);
658 // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section,
659 // which is at the start of that section so this is zero.
660 if (LineSectionSymbol) {
661 MCOS->EmitSymbolValue(LineSectionSymbol, 4);
663 MCOS->EmitIntValue(0, 4);
666 // AT_low_pc, the first address of the default .text section.
667 const MCExpr *Start = MCSymbolRefExpr::Create(
668 context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
669 MCOS->EmitAbsValue(Start, AddrSize);
671 // AT_high_pc, the last address of the default .text section.
672 const MCExpr *End = MCSymbolRefExpr::Create(
673 context.getGenDwarfSectionEndSym(), MCSymbolRefExpr::VK_None, context);
674 MCOS->EmitAbsValue(End, AddrSize);
676 // AT_name, the name of the source file. Reconstruct from the first directory
677 // and file table entries.
678 const SmallVectorImpl<std::string> &MCDwarfDirs = context.getMCDwarfDirs();
679 if (MCDwarfDirs.size() > 0) {
680 MCOS->EmitBytes(MCDwarfDirs[0]);
681 MCOS->EmitBytes("/");
683 const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles =
684 MCOS->getContext().getMCDwarfFiles();
685 MCOS->EmitBytes(MCDwarfFiles[1].Name);
686 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
688 // AT_comp_dir, the working directory the assembly was done in.
689 if (!context.getCompilationDir().empty()) {
690 MCOS->EmitBytes(context.getCompilationDir());
691 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
694 // AT_APPLE_flags, the command line arguments of the assembler tool.
695 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
696 if (!DwarfDebugFlags.empty()){
697 MCOS->EmitBytes(DwarfDebugFlags);
698 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
701 // AT_producer, the version of the assembler tool.
702 StringRef DwarfDebugProducer = context.getDwarfDebugProducer();
703 if (!DwarfDebugProducer.empty()){
704 MCOS->EmitBytes(DwarfDebugProducer);
707 MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM "));
708 MCOS->EmitBytes(StringRef(PACKAGE_VERSION));
709 MCOS->EmitBytes(StringRef(")"));
711 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
713 // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2
714 // draft has no standard code for assembler.
715 MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2);
717 // Third part: the list of label DIEs.
719 // Loop on saved info for dwarf labels and create the DIEs for them.
720 const std::vector<const MCGenDwarfLabelEntry *> &Entries =
721 MCOS->getContext().getMCGenDwarfLabelEntries();
722 for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it =
723 Entries.begin(), ie = Entries.end(); it != ie;
725 const MCGenDwarfLabelEntry *Entry = *it;
727 // The DW_TAG_label DIE abbrev (2).
728 MCOS->EmitULEB128IntValue(2);
730 // AT_name, of the label without any leading underbar.
731 MCOS->EmitBytes(Entry->getName());
732 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
734 // AT_decl_file, index into the file table.
735 MCOS->EmitIntValue(Entry->getFileNumber(), 4);
737 // AT_decl_line, source line number.
738 MCOS->EmitIntValue(Entry->getLineNumber(), 4);
740 // AT_low_pc, start address of the label.
741 const MCExpr *AT_low_pc = MCSymbolRefExpr::Create(Entry->getLabel(),
742 MCSymbolRefExpr::VK_None, context);
743 MCOS->EmitAbsValue(AT_low_pc, AddrSize);
745 // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype.
746 MCOS->EmitIntValue(0, 1);
748 // The DW_TAG_unspecified_parameters DIE abbrev (3).
749 MCOS->EmitULEB128IntValue(3);
751 // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's.
752 MCOS->EmitIntValue(0, 1);
754 // Deallocate the MCGenDwarfLabelEntry classes that saved away the info
755 // for the dwarf labels.
756 for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it =
757 Entries.begin(), ie = Entries.end(); it != ie;
759 const MCGenDwarfLabelEntry *Entry = *it;
763 // Add the NULL DIE terminating the Compile Unit DIE's.
764 MCOS->EmitIntValue(0, 1);
766 // Now set the value of the symbol at the end of the info section.
767 MCOS->EmitLabel(InfoEnd);
771 // When generating dwarf for assembly source files this emits the Dwarf
774 void MCGenDwarfInfo::Emit(MCStreamer *MCOS, const MCSymbol *LineSectionSymbol) {
775 // Create the dwarf sections in this order (.debug_line already created).
776 MCContext &context = MCOS->getContext();
777 const MCAsmInfo *AsmInfo = context.getAsmInfo();
778 bool CreateDwarfSectionSymbols =
779 AsmInfo->doesDwarfUseRelocationsAcrossSections();
780 if (!CreateDwarfSectionSymbols)
781 LineSectionSymbol = NULL;
782 MCSymbol *AbbrevSectionSymbol = NULL;
783 MCSymbol *InfoSectionSymbol = NULL;
784 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
785 if (CreateDwarfSectionSymbols) {
786 InfoSectionSymbol = context.CreateTempSymbol();
787 MCOS->EmitLabel(InfoSectionSymbol);
789 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
790 if (CreateDwarfSectionSymbols) {
791 AbbrevSectionSymbol = context.CreateTempSymbol();
792 MCOS->EmitLabel(AbbrevSectionSymbol);
794 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
796 // If there are no line table entries then do not emit any section contents.
797 if (!context.hasMCLineSections())
800 // Output the data for .debug_aranges section.
801 EmitGenDwarfAranges(MCOS, InfoSectionSymbol);
803 // Output the data for .debug_abbrev section.
804 EmitGenDwarfAbbrev(MCOS);
806 // Output the data for .debug_info section.
807 EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol);
811 // When generating dwarf for assembly source files this is called when symbol
812 // for a label is created. If this symbol is not a temporary and is in the
813 // section that dwarf is being generated for, save the needed info to create
816 void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
817 SourceMgr &SrcMgr, SMLoc &Loc) {
818 // We won't create dwarf labels for temporary symbols or symbols not in
820 if (Symbol->isTemporary())
822 MCContext &context = MCOS->getContext();
823 if (context.getGenDwarfSection() != MCOS->getCurrentSection().first)
826 // The dwarf label's name does not have the symbol name's leading
828 StringRef Name = Symbol->getName();
829 if (Name.startswith("_"))
830 Name = Name.substr(1, Name.size()-1);
832 // Get the dwarf file number to be used for the dwarf label.
833 unsigned FileNumber = context.getGenDwarfFileNumber();
835 // Finding the line number is the expensive part which is why we just don't
836 // pass it in as for some symbols we won't create a dwarf label.
837 int CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
838 unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
840 // We create a temporary symbol for use for the AT_high_pc and AT_low_pc
841 // values so that they don't have things like an ARM thumb bit from the
842 // original symbol. So when used they won't get a low bit set after
844 MCSymbol *Label = context.CreateTempSymbol();
845 MCOS->EmitLabel(Label);
847 // Create and entry for the info and add it to the other entries.
848 MCGenDwarfLabelEntry *Entry =
849 new MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label);
850 MCOS->getContext().addMCGenDwarfLabelEntry(Entry);
853 static int getDataAlignmentFactor(MCStreamer &streamer) {
854 MCContext &context = streamer.getContext();
855 const MCAsmInfo *asmInfo = context.getAsmInfo();
856 int size = asmInfo->getCalleeSaveStackSlotSize();
857 if (asmInfo->isStackGrowthDirectionUp())
863 static unsigned getSizeForEncoding(MCStreamer &streamer,
864 unsigned symbolEncoding) {
865 MCContext &context = streamer.getContext();
866 unsigned format = symbolEncoding & 0x0f;
868 default: llvm_unreachable("Unknown Encoding");
869 case dwarf::DW_EH_PE_absptr:
870 case dwarf::DW_EH_PE_signed:
871 return context.getAsmInfo()->getPointerSize();
872 case dwarf::DW_EH_PE_udata2:
873 case dwarf::DW_EH_PE_sdata2:
875 case dwarf::DW_EH_PE_udata4:
876 case dwarf::DW_EH_PE_sdata4:
878 case dwarf::DW_EH_PE_udata8:
879 case dwarf::DW_EH_PE_sdata8:
884 static void EmitFDESymbol(MCStreamer &streamer, const MCSymbol &symbol,
885 unsigned symbolEncoding, bool isEH,
886 const char *comment = 0) {
887 MCContext &context = streamer.getContext();
888 const MCAsmInfo *asmInfo = context.getAsmInfo();
889 const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol,
892 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
893 if (streamer.isVerboseAsm() && comment) streamer.AddComment(comment);
894 if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH)
895 streamer.EmitAbsValue(v, size);
897 streamer.EmitValue(v, size);
900 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
901 unsigned symbolEncoding) {
902 MCContext &context = streamer.getContext();
903 const MCAsmInfo *asmInfo = context.getAsmInfo();
904 const MCExpr *v = asmInfo->getExprForPersonalitySymbol(&symbol,
907 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
908 streamer.EmitValue(v, size);
912 class FrameEmitterImpl {
917 const MCSymbol *SectionStart;
919 FrameEmitterImpl(bool usingCFI, bool isEH)
920 : CFAOffset(0), CIENum(0), UsingCFI(usingCFI), IsEH(isEH),
923 void setSectionStart(const MCSymbol *Label) { SectionStart = Label; }
925 /// EmitCompactUnwind - Emit the unwind information in a compact way.
926 void EmitCompactUnwind(MCStreamer &streamer,
927 const MCDwarfFrameInfo &frame);
929 const MCSymbol &EmitCIE(MCStreamer &streamer,
930 const MCSymbol *personality,
931 unsigned personalityEncoding,
932 const MCSymbol *lsda,
934 unsigned lsdaEncoding,
936 MCSymbol *EmitFDE(MCStreamer &streamer,
937 const MCSymbol &cieStart,
938 const MCDwarfFrameInfo &frame);
939 void EmitCFIInstructions(MCStreamer &streamer,
940 ArrayRef<MCCFIInstruction> Instrs,
941 MCSymbol *BaseLabel);
942 void EmitCFIInstruction(MCStreamer &Streamer,
943 const MCCFIInstruction &Instr);
946 } // end anonymous namespace
948 static void EmitEncodingByte(MCStreamer &Streamer, unsigned Encoding,
950 if (Streamer.isVerboseAsm()) {
953 default: EncStr = "<unknown encoding>"; break;
954 case dwarf::DW_EH_PE_absptr: EncStr = "absptr"; break;
955 case dwarf::DW_EH_PE_omit: EncStr = "omit"; break;
956 case dwarf::DW_EH_PE_pcrel: EncStr = "pcrel"; break;
957 case dwarf::DW_EH_PE_udata4: EncStr = "udata4"; break;
958 case dwarf::DW_EH_PE_udata8: EncStr = "udata8"; break;
959 case dwarf::DW_EH_PE_sdata4: EncStr = "sdata4"; break;
960 case dwarf::DW_EH_PE_sdata8: EncStr = "sdata8"; break;
961 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
962 EncStr = "pcrel udata4";
964 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
965 EncStr = "pcrel sdata4";
967 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
968 EncStr = "pcrel udata8";
970 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
971 EncStr = "screl sdata8";
973 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata4:
974 EncStr = "indirect pcrel udata4";
976 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata4:
977 EncStr = "indirect pcrel sdata4";
979 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata8:
980 EncStr = "indirect pcrel udata8";
982 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata8:
983 EncStr = "indirect pcrel sdata8";
987 Streamer.AddComment(Twine(Prefix) + " = " + EncStr);
990 Streamer.EmitIntValue(Encoding, 1);
993 void FrameEmitterImpl::EmitCFIInstruction(MCStreamer &Streamer,
994 const MCCFIInstruction &Instr) {
995 int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
996 bool VerboseAsm = Streamer.isVerboseAsm();
998 switch (Instr.getOperation()) {
999 case MCCFIInstruction::OpRegister: {
1000 unsigned Reg1 = Instr.getRegister();
1001 unsigned Reg2 = Instr.getRegister2();
1003 Streamer.AddComment("DW_CFA_register");
1004 Streamer.AddComment(Twine("Reg1 ") + Twine(Reg1));
1005 Streamer.AddComment(Twine("Reg2 ") + Twine(Reg2));
1007 Streamer.EmitIntValue(dwarf::DW_CFA_register, 1);
1008 Streamer.EmitULEB128IntValue(Reg1);
1009 Streamer.EmitULEB128IntValue(Reg2);
1012 case MCCFIInstruction::OpWindowSave: {
1013 Streamer.EmitIntValue(dwarf::DW_CFA_GNU_window_save, 1);
1016 case MCCFIInstruction::OpUndefined: {
1017 unsigned Reg = Instr.getRegister();
1019 Streamer.AddComment("DW_CFA_undefined");
1020 Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1022 Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1);
1023 Streamer.EmitULEB128IntValue(Reg);
1026 case MCCFIInstruction::OpAdjustCfaOffset:
1027 case MCCFIInstruction::OpDefCfaOffset: {
1028 const bool IsRelative =
1029 Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset;
1032 Streamer.AddComment("DW_CFA_def_cfa_offset");
1033 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
1036 CFAOffset += Instr.getOffset();
1038 CFAOffset = -Instr.getOffset();
1041 Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
1042 Streamer.EmitULEB128IntValue(CFAOffset);
1046 case MCCFIInstruction::OpDefCfa: {
1048 Streamer.AddComment("DW_CFA_def_cfa");
1049 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
1052 Streamer.AddComment(Twine("Reg ") + Twine(Instr.getRegister()));
1053 Streamer.EmitULEB128IntValue(Instr.getRegister());
1055 CFAOffset = -Instr.getOffset();
1058 Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
1059 Streamer.EmitULEB128IntValue(CFAOffset);
1064 case MCCFIInstruction::OpDefCfaRegister: {
1066 Streamer.AddComment("DW_CFA_def_cfa_register");
1067 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
1070 Streamer.AddComment(Twine("Reg ") + Twine(Instr.getRegister()));
1071 Streamer.EmitULEB128IntValue(Instr.getRegister());
1076 case MCCFIInstruction::OpOffset:
1077 case MCCFIInstruction::OpRelOffset: {
1078 const bool IsRelative =
1079 Instr.getOperation() == MCCFIInstruction::OpRelOffset;
1081 unsigned Reg = Instr.getRegister();
1082 int Offset = Instr.getOffset();
1084 Offset -= CFAOffset;
1085 Offset = Offset / dataAlignmentFactor;
1088 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended_sf");
1089 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
1090 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1091 Streamer.EmitULEB128IntValue(Reg);
1092 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1093 Streamer.EmitSLEB128IntValue(Offset);
1094 } else if (Reg < 64) {
1095 if (VerboseAsm) Streamer.AddComment(Twine("DW_CFA_offset + Reg(") +
1097 Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
1098 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1099 Streamer.EmitULEB128IntValue(Offset);
1101 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended");
1102 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
1103 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1104 Streamer.EmitULEB128IntValue(Reg);
1105 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1106 Streamer.EmitULEB128IntValue(Offset);
1110 case MCCFIInstruction::OpRememberState:
1111 if (VerboseAsm) Streamer.AddComment("DW_CFA_remember_state");
1112 Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
1114 case MCCFIInstruction::OpRestoreState:
1115 if (VerboseAsm) Streamer.AddComment("DW_CFA_restore_state");
1116 Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
1118 case MCCFIInstruction::OpSameValue: {
1119 unsigned Reg = Instr.getRegister();
1120 if (VerboseAsm) Streamer.AddComment("DW_CFA_same_value");
1121 Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
1122 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1123 Streamer.EmitULEB128IntValue(Reg);
1126 case MCCFIInstruction::OpRestore: {
1127 unsigned Reg = Instr.getRegister();
1129 Streamer.AddComment("DW_CFA_restore");
1130 Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1132 Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1);
1135 case MCCFIInstruction::OpEscape:
1136 if (VerboseAsm) Streamer.AddComment("Escape bytes");
1137 Streamer.EmitBytes(Instr.getValues());
1140 llvm_unreachable("Unhandled case in switch");
1143 /// EmitFrameMoves - Emit frame instructions to describe the layout of the
1145 void FrameEmitterImpl::EmitCFIInstructions(MCStreamer &streamer,
1146 ArrayRef<MCCFIInstruction> Instrs,
1147 MCSymbol *BaseLabel) {
1148 for (unsigned i = 0, N = Instrs.size(); i < N; ++i) {
1149 const MCCFIInstruction &Instr = Instrs[i];
1150 MCSymbol *Label = Instr.getLabel();
1151 // Throw out move if the label is invalid.
1152 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
1154 // Advance row if new location.
1155 if (BaseLabel && Label) {
1156 MCSymbol *ThisSym = Label;
1157 if (ThisSym != BaseLabel) {
1158 if (streamer.isVerboseAsm()) streamer.AddComment("DW_CFA_advance_loc4");
1159 streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
1160 BaseLabel = ThisSym;
1164 EmitCFIInstruction(streamer, Instr);
1168 /// EmitCompactUnwind - Emit the unwind information in a compact way.
1169 void FrameEmitterImpl::EmitCompactUnwind(MCStreamer &Streamer,
1170 const MCDwarfFrameInfo &Frame) {
1171 MCContext &Context = Streamer.getContext();
1172 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1173 bool VerboseAsm = Streamer.isVerboseAsm();
1175 // range-start range-length compact-unwind-enc personality-func lsda
1176 // _foo LfooEnd-_foo 0x00000023 0 0
1177 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1
1179 // .section __LD,__compact_unwind,regular,debug
1181 // # compact unwind for _foo
1183 // .set L1,LfooEnd-_foo
1189 // # compact unwind for _bar
1191 // .set L2,LbarEnd-_bar
1194 // .quad __gxx_personality
1195 // .quad except_tab1
1197 uint32_t Encoding = Frame.CompactUnwindEncoding;
1198 if (!Encoding) return;
1199 bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly());
1201 // The encoding needs to know we have an LSDA.
1202 if (!DwarfEHFrameOnly && Frame.Lsda)
1203 Encoding |= 0x40000000;
1206 unsigned FDEEncoding = MOFI->getFDEEncoding(UsingCFI);
1207 unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
1208 if (VerboseAsm) Streamer.AddComment("Range Start");
1209 Streamer.EmitSymbolValue(Frame.Function, Size);
1212 const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin,
1214 if (VerboseAsm) Streamer.AddComment("Range Length");
1215 Streamer.EmitAbsValue(Range, 4);
1218 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
1219 if (VerboseAsm) Streamer.AddComment("Compact Unwind Encoding: 0x" +
1220 Twine::utohexstr(Encoding));
1221 Streamer.EmitIntValue(Encoding, Size);
1223 // Personality Function
1224 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
1225 if (VerboseAsm) Streamer.AddComment("Personality Function");
1226 if (!DwarfEHFrameOnly && Frame.Personality)
1227 Streamer.EmitSymbolValue(Frame.Personality, Size);
1229 Streamer.EmitIntValue(0, Size); // No personality fn
1232 Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
1233 if (VerboseAsm) Streamer.AddComment("LSDA");
1234 if (!DwarfEHFrameOnly && Frame.Lsda)
1235 Streamer.EmitSymbolValue(Frame.Lsda, Size);
1237 Streamer.EmitIntValue(0, Size); // No LSDA
1240 const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
1241 const MCSymbol *personality,
1242 unsigned personalityEncoding,
1243 const MCSymbol *lsda,
1245 unsigned lsdaEncoding,
1247 MCContext &context = streamer.getContext();
1248 const MCRegisterInfo *MRI = context.getRegisterInfo();
1249 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1250 bool verboseAsm = streamer.isVerboseAsm();
1252 MCSymbol *sectionStart;
1253 if (MOFI->isFunctionEHFrameSymbolPrivate() || !IsEH)
1254 sectionStart = context.CreateTempSymbol();
1256 sectionStart = context.GetOrCreateSymbol(Twine("EH_frame") + Twine(CIENum));
1258 streamer.EmitLabel(sectionStart);
1261 MCSymbol *sectionEnd = context.CreateTempSymbol();
1264 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *sectionStart,
1266 if (verboseAsm) streamer.AddComment("CIE Length");
1267 streamer.EmitAbsValue(Length, 4);
1270 unsigned CIE_ID = IsEH ? 0 : -1;
1271 if (verboseAsm) streamer.AddComment("CIE ID Tag");
1272 streamer.EmitIntValue(CIE_ID, 4);
1275 if (verboseAsm) streamer.AddComment("DW_CIE_VERSION");
1276 streamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1);
1278 // Augmentation String
1279 SmallString<8> Augmentation;
1281 if (verboseAsm) streamer.AddComment("CIE Augmentation");
1282 Augmentation += "z";
1284 Augmentation += "P";
1286 Augmentation += "L";
1287 Augmentation += "R";
1289 Augmentation += "S";
1290 streamer.EmitBytes(Augmentation.str());
1292 streamer.EmitIntValue(0, 1);
1294 // Code Alignment Factor
1295 if (verboseAsm) streamer.AddComment("CIE Code Alignment Factor");
1296 streamer.EmitULEB128IntValue(context.getAsmInfo()->getMinInstAlignment());
1298 // Data Alignment Factor
1299 if (verboseAsm) streamer.AddComment("CIE Data Alignment Factor");
1300 streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer));
1302 // Return Address Register
1303 if (verboseAsm) streamer.AddComment("CIE Return Address Column");
1304 streamer.EmitULEB128IntValue(MRI->getDwarfRegNum(MRI->getRARegister(), true));
1306 // Augmentation Data Length (optional)
1308 unsigned augmentationLength = 0;
1311 // Personality Encoding
1312 augmentationLength += 1;
1314 augmentationLength += getSizeForEncoding(streamer, personalityEncoding);
1317 augmentationLength += 1;
1318 // Encoding of the FDE pointers
1319 augmentationLength += 1;
1321 if (verboseAsm) streamer.AddComment("Augmentation Size");
1322 streamer.EmitULEB128IntValue(augmentationLength);
1324 // Augmentation Data (optional)
1326 // Personality Encoding
1327 EmitEncodingByte(streamer, personalityEncoding,
1328 "Personality Encoding");
1330 if (verboseAsm) streamer.AddComment("Personality");
1331 EmitPersonality(streamer, *personality, personalityEncoding);
1335 EmitEncodingByte(streamer, lsdaEncoding, "LSDA Encoding");
1337 // Encoding of the FDE pointers
1338 EmitEncodingByte(streamer, MOFI->getFDEEncoding(UsingCFI),
1342 // Initial Instructions
1344 const MCAsmInfo *MAI = context.getAsmInfo();
1346 const std::vector<MCCFIInstruction> &Instructions =
1347 MAI->getInitialFrameState();
1348 EmitCFIInstructions(streamer, Instructions, NULL);
1352 streamer.EmitValueToAlignment(IsEH ? 4 : MAI->getPointerSize());
1354 streamer.EmitLabel(sectionEnd);
1355 return *sectionStart;
1358 MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
1359 const MCSymbol &cieStart,
1360 const MCDwarfFrameInfo &frame) {
1361 MCContext &context = streamer.getContext();
1362 MCSymbol *fdeStart = context.CreateTempSymbol();
1363 MCSymbol *fdeEnd = context.CreateTempSymbol();
1364 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1365 bool verboseAsm = streamer.isVerboseAsm();
1367 if (IsEH && frame.Function && !MOFI->isFunctionEHFrameSymbolPrivate()) {
1369 context.GetOrCreateSymbol(frame.Function->getName() + Twine(".eh"));
1370 streamer.EmitEHSymAttributes(frame.Function, EHSym);
1371 streamer.EmitLabel(EHSym);
1375 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *fdeStart, *fdeEnd, 0);
1376 if (verboseAsm) streamer.AddComment("FDE Length");
1377 streamer.EmitAbsValue(Length, 4);
1379 streamer.EmitLabel(fdeStart);
1382 const MCAsmInfo *asmInfo = context.getAsmInfo();
1384 const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart,
1386 if (verboseAsm) streamer.AddComment("FDE CIE Offset");
1387 streamer.EmitAbsValue(offset, 4);
1388 } else if (!asmInfo->doesDwarfUseRelocationsAcrossSections()) {
1389 const MCExpr *offset = MakeStartMinusEndExpr(streamer, *SectionStart,
1391 streamer.EmitAbsValue(offset, 4);
1393 streamer.EmitSymbolValue(&cieStart, 4);
1397 unsigned PCEncoding = IsEH ? MOFI->getFDEEncoding(UsingCFI)
1398 : (unsigned)dwarf::DW_EH_PE_absptr;
1399 unsigned PCSize = getSizeForEncoding(streamer, PCEncoding);
1400 EmitFDESymbol(streamer, *frame.Begin, PCEncoding, IsEH, "FDE initial location");
1403 const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin,
1405 if (verboseAsm) streamer.AddComment("FDE address range");
1406 streamer.EmitAbsValue(Range, PCSize);
1409 // Augmentation Data Length
1410 unsigned augmentationLength = 0;
1413 augmentationLength += getSizeForEncoding(streamer, frame.LsdaEncoding);
1415 if (verboseAsm) streamer.AddComment("Augmentation size");
1416 streamer.EmitULEB128IntValue(augmentationLength);
1418 // Augmentation Data
1420 EmitFDESymbol(streamer, *frame.Lsda, frame.LsdaEncoding, true,
1421 "Language Specific Data Area");
1424 // Call Frame Instructions
1425 EmitCFIInstructions(streamer, frame.Instructions, frame.Begin);
1428 streamer.EmitValueToAlignment(PCSize);
1435 static const CIEKey getEmptyKey() { return CIEKey(0, 0, -1, false, false); }
1436 static const CIEKey getTombstoneKey() { return CIEKey(0, -1, 0, false, false); }
1438 CIEKey(const MCSymbol* Personality_, unsigned PersonalityEncoding_,
1439 unsigned LsdaEncoding_, bool IsSignalFrame_, bool IsSimple_) :
1440 Personality(Personality_), PersonalityEncoding(PersonalityEncoding_),
1441 LsdaEncoding(LsdaEncoding_), IsSignalFrame(IsSignalFrame_),
1442 IsSimple(IsSimple_) {
1444 const MCSymbol* Personality;
1445 unsigned PersonalityEncoding;
1446 unsigned LsdaEncoding;
1454 struct DenseMapInfo<CIEKey> {
1455 static CIEKey getEmptyKey() {
1456 return CIEKey::getEmptyKey();
1458 static CIEKey getTombstoneKey() {
1459 return CIEKey::getTombstoneKey();
1461 static unsigned getHashValue(const CIEKey &Key) {
1462 return static_cast<unsigned>(hash_combine(Key.Personality,
1463 Key.PersonalityEncoding,
1468 static bool isEqual(const CIEKey &LHS,
1469 const CIEKey &RHS) {
1470 return LHS.Personality == RHS.Personality &&
1471 LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
1472 LHS.LsdaEncoding == RHS.LsdaEncoding &&
1473 LHS.IsSignalFrame == RHS.IsSignalFrame &&
1474 LHS.IsSimple == RHS.IsSimple;
1479 void MCDwarfFrameEmitter::Emit(MCStreamer &Streamer, MCAsmBackend *MAB,
1480 bool UsingCFI, bool IsEH) {
1481 Streamer.generateCompactUnwindEncodings(MAB);
1483 MCContext &Context = Streamer.getContext();
1484 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1485 FrameEmitterImpl Emitter(UsingCFI, IsEH);
1486 ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getFrameInfos();
1488 // Emit the compact unwind info if available.
1489 if (IsEH && MOFI->getCompactUnwindSection()) {
1490 bool SectionEmitted = false;
1491 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
1492 const MCDwarfFrameInfo &Frame = FrameArray[i];
1493 if (Frame.CompactUnwindEncoding == 0) continue;
1494 if (!SectionEmitted) {
1495 Streamer.SwitchSection(MOFI->getCompactUnwindSection());
1496 Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize());
1497 SectionEmitted = true;
1499 Emitter.EmitCompactUnwind(Streamer, Frame);
1503 const MCSection &Section =
1504 IsEH ? *const_cast<MCObjectFileInfo*>(MOFI)->getEHFrameSection() :
1505 *MOFI->getDwarfFrameSection();
1506 Streamer.SwitchSection(&Section);
1507 MCSymbol *SectionStart = Context.CreateTempSymbol();
1508 Streamer.EmitLabel(SectionStart);
1509 Emitter.setSectionStart(SectionStart);
1511 MCSymbol *FDEEnd = NULL;
1512 DenseMap<CIEKey, const MCSymbol*> CIEStarts;
1514 const MCSymbol *DummyDebugKey = NULL;
1515 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
1516 const MCDwarfFrameInfo &Frame = FrameArray[i];
1517 CIEKey Key(Frame.Personality, Frame.PersonalityEncoding,
1518 Frame.LsdaEncoding, Frame.IsSignalFrame, Frame.IsSimple);
1519 const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
1521 CIEStart = &Emitter.EmitCIE(Streamer, Frame.Personality,
1522 Frame.PersonalityEncoding, Frame.Lsda,
1523 Frame.IsSignalFrame,
1527 FDEEnd = Emitter.EmitFDE(Streamer, *CIEStart, Frame);
1530 Streamer.EmitLabel(FDEEnd);
1533 Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize());
1535 Streamer.EmitLabel(FDEEnd);
1538 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCStreamer &Streamer,
1539 uint64_t AddrDelta) {
1540 MCContext &Context = Streamer.getContext();
1541 SmallString<256> Tmp;
1542 raw_svector_ostream OS(Tmp);
1543 MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OS);
1544 Streamer.EmitBytes(OS.str());
1547 void MCDwarfFrameEmitter::EncodeAdvanceLoc(MCContext &Context,
1550 // Scale the address delta by the minimum instruction length.
1551 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
1553 if (AddrDelta == 0) {
1554 } else if (isUIntN(6, AddrDelta)) {
1555 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
1557 } else if (isUInt<8>(AddrDelta)) {
1558 OS << uint8_t(dwarf::DW_CFA_advance_loc1);
1559 OS << uint8_t(AddrDelta);
1560 } else if (isUInt<16>(AddrDelta)) {
1561 // FIXME: check what is the correct behavior on a big endian machine.
1562 OS << uint8_t(dwarf::DW_CFA_advance_loc2);
1563 OS << uint8_t( AddrDelta & 0xff);
1564 OS << uint8_t((AddrDelta >> 8) & 0xff);
1566 // FIXME: check what is the correct behavior on a big endian machine.
1567 assert(isUInt<32>(AddrDelta));
1568 OS << uint8_t(dwarf::DW_CFA_advance_loc4);
1569 OS << uint8_t( AddrDelta & 0xff);
1570 OS << uint8_t((AddrDelta >> 8) & 0xff);
1571 OS << uint8_t((AddrDelta >> 16) & 0xff);
1572 OS << uint8_t((AddrDelta >> 24) & 0xff);