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 .getMCDwarfFileTable(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 *MCDwarfFileTable::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().getMCDwarfFileTables().begin(),
214 E = MCOS->getContext().getMCDwarfFileTables().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 const MCSymbol *MCDwarfFileTable::EmitCU(MCStreamer *MCOS) const {
228 MCContext &context = MCOS->getContext();
232 // Create a symbol at the beginning of the line table.
233 MCSymbol *LineStartSym = Label;
235 LineStartSym = context.CreateTempSymbol();
236 // Set the value of the symbol, as we are at the start of the line table.
237 MCOS->EmitLabel(LineStartSym);
239 // Create a symbol for the end of the section (to be set when we get there).
240 MCSymbol *LineEndSym = context.CreateTempSymbol();
242 // The first 4 bytes is the total length of the information for this
243 // compilation unit (not including these 4 bytes for the length).
244 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym,4),
247 // Next 2 bytes is the Version, which is Dwarf 2.
248 MCOS->EmitIntValue(2, 2);
250 // Create a symbol for the end of the prologue (to be set when we get there).
251 MCSymbol *ProEndSym = context.CreateTempSymbol(); // Lprologue_end
253 // Length of the prologue, is the next 4 bytes. Which is the start of the
254 // section to the end of the prologue. Not including the 4 bytes for the
255 // total length, the 2 bytes for the version, and these 4 bytes for the
256 // length of the prologue.
257 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym,
260 // Parameters of the state machine, are next.
261 MCOS->EmitIntValue(context.getAsmInfo()->getMinInstAlignment(), 1);
262 MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
263 MCOS->EmitIntValue(DWARF2_LINE_BASE, 1);
264 MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1);
265 MCOS->EmitIntValue(DWARF2_LINE_OPCODE_BASE, 1);
267 // Standard opcode lengths
268 MCOS->EmitIntValue(0, 1); // length of DW_LNS_copy
269 MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_pc
270 MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_line
271 MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_file
272 MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_column
273 MCOS->EmitIntValue(0, 1); // length of DW_LNS_negate_stmt
274 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_basic_block
275 MCOS->EmitIntValue(0, 1); // length of DW_LNS_const_add_pc
276 MCOS->EmitIntValue(1, 1); // length of DW_LNS_fixed_advance_pc
277 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_prologue_end
278 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_epilogue_begin
279 MCOS->EmitIntValue(1, 1); // DW_LNS_set_isa
281 // Put out the directory and file tables.
283 // First the directory table.
284 for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
285 MCOS->EmitBytes(MCDwarfDirs[i]); // the DirectoryName
286 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
288 MCOS->EmitIntValue(0, 1); // Terminate the directory list
290 // Second the file table.
291 for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
292 MCOS->EmitBytes(MCDwarfFiles[i].Name); // FileName
293 MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
295 MCOS->EmitULEB128IntValue(MCDwarfFiles[i].DirIndex);
296 MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
297 MCOS->EmitIntValue(0, 1); // filesize (always 0)
299 MCOS->EmitIntValue(0, 1); // Terminate the file list
301 // This is the end of the prologue, so set the value of the symbol at the
302 // end of the prologue (that was used in a previous expression).
303 MCOS->EmitLabel(ProEndSym);
305 // Put out the line tables.
306 for (const auto &LineSec : MCLineSections.getMCLineEntries())
307 EmitDwarfLineTable(MCOS, LineSec.first, LineSec.second);
309 if (MCOS->getContext().getAsmInfo()->getLinkerRequiresNonEmptyDwarfLines() &&
310 MCLineSections.getMCLineEntries().empty()) {
311 // The darwin9 linker has a bug (see PR8715). For for 32-bit architectures
313 // total_length >= prologue_length + 10
314 // We are 4 bytes short, since we have total_length = 51 and
315 // prologue_length = 45
317 // The regular end_sequence should be sufficient.
318 MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
321 // This is the end of the section, so set the value of the symbol at the end
322 // of this section (that was used in a previous expression).
323 MCOS->EmitLabel(LineEndSym);
328 /// Utility function to emit the encoding to a streamer.
329 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta,
330 uint64_t AddrDelta) {
331 MCContext &Context = MCOS->getContext();
332 SmallString<256> Tmp;
333 raw_svector_ostream OS(Tmp);
334 MCDwarfLineAddr::Encode(Context, LineDelta, AddrDelta, OS);
335 MCOS->EmitBytes(OS.str());
338 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
339 void MCDwarfLineAddr::Encode(MCContext &Context, int64_t LineDelta,
340 uint64_t AddrDelta, raw_ostream &OS) {
341 uint64_t Temp, Opcode;
342 bool NeedCopy = false;
344 // Scale the address delta by the minimum instruction length.
345 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
347 // A LineDelta of INT64_MAX is a signal that this is actually a
348 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
349 // end_sequence to emit the matrix entry.
350 if (LineDelta == INT64_MAX) {
351 if (AddrDelta == MAX_SPECIAL_ADDR_DELTA)
352 OS << char(dwarf::DW_LNS_const_add_pc);
354 OS << char(dwarf::DW_LNS_advance_pc);
355 encodeULEB128(AddrDelta, OS);
357 OS << char(dwarf::DW_LNS_extended_op);
359 OS << char(dwarf::DW_LNE_end_sequence);
363 // Bias the line delta by the base.
364 Temp = LineDelta - DWARF2_LINE_BASE;
366 // If the line increment is out of range of a special opcode, we must encode
367 // it with DW_LNS_advance_line.
368 if (Temp >= DWARF2_LINE_RANGE) {
369 OS << char(dwarf::DW_LNS_advance_line);
370 encodeSLEB128(LineDelta, OS);
373 Temp = 0 - DWARF2_LINE_BASE;
377 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
378 if (LineDelta == 0 && AddrDelta == 0) {
379 OS << char(dwarf::DW_LNS_copy);
383 // Bias the opcode by the special opcode base.
384 Temp += DWARF2_LINE_OPCODE_BASE;
386 // Avoid overflow when addr_delta is large.
387 if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) {
388 // Try using a special opcode.
389 Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE;
395 // Try using DW_LNS_const_add_pc followed by special op.
396 Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
398 OS << char(dwarf::DW_LNS_const_add_pc);
404 // Otherwise use DW_LNS_advance_pc.
405 OS << char(dwarf::DW_LNS_advance_pc);
406 encodeULEB128(AddrDelta, OS);
409 OS << char(dwarf::DW_LNS_copy);
414 // Utility function to write a tuple for .debug_abbrev.
415 static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) {
416 MCOS->EmitULEB128IntValue(Name);
417 MCOS->EmitULEB128IntValue(Form);
420 // When generating dwarf for assembly source files this emits
421 // the data for .debug_abbrev section which contains three DIEs.
422 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
423 MCContext &context = MCOS->getContext();
424 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
426 // DW_TAG_compile_unit DIE abbrev (1).
427 MCOS->EmitULEB128IntValue(1);
428 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit);
429 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
430 EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4);
431 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
432 EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
433 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
434 if (!context.getCompilationDir().empty())
435 EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
436 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
437 if (!DwarfDebugFlags.empty())
438 EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
439 EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string);
440 EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2);
441 EmitAbbrev(MCOS, 0, 0);
443 // DW_TAG_label DIE abbrev (2).
444 MCOS->EmitULEB128IntValue(2);
445 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_label);
446 MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
447 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
448 EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);
449 EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);
450 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
451 EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag);
452 EmitAbbrev(MCOS, 0, 0);
454 // DW_TAG_unspecified_parameters DIE abbrev (3).
455 MCOS->EmitULEB128IntValue(3);
456 MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters);
457 MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1);
458 EmitAbbrev(MCOS, 0, 0);
460 // Terminate the abbreviations for this compilation unit.
461 MCOS->EmitIntValue(0, 1);
464 // When generating dwarf for assembly source files this emits the data for
465 // .debug_aranges section. Which contains a header and a table of pairs of
466 // PointerSize'ed values for the address and size of section(s) with line table
467 // entries (just the default .text in our case) and a terminating pair of zeros.
468 static void EmitGenDwarfAranges(MCStreamer *MCOS,
469 const MCSymbol *InfoSectionSymbol) {
470 MCContext &context = MCOS->getContext();
472 // Create a symbol at the end of the section that we are creating the dwarf
473 // debugging info to use later in here as part of the expression to calculate
474 // the size of the section for the table.
475 MCOS->SwitchSection(context.getGenDwarfSection());
476 MCSymbol *SectionEndSym = context.CreateTempSymbol();
477 MCOS->EmitLabel(SectionEndSym);
478 context.setGenDwarfSectionEndSym(SectionEndSym);
480 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
482 // This will be the length of the .debug_aranges section, first account for
483 // the size of each item in the header (see below where we emit these items).
484 int Length = 4 + 2 + 4 + 1 + 1;
486 // Figure the padding after the header before the table of address and size
487 // pairs who's values are PointerSize'ed.
488 const MCAsmInfo *asmInfo = context.getAsmInfo();
489 int AddrSize = asmInfo->getPointerSize();
490 int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1));
491 if (Pad == 2 * AddrSize)
495 // Add the size of the pair of PointerSize'ed values for the address and size
496 // of the one default .text section we have in the table.
497 Length += 2 * AddrSize;
498 // And the pair of terminating zeros.
499 Length += 2 * AddrSize;
502 // Emit the header for this section.
503 // The 4 byte length not including the 4 byte value for the length.
504 MCOS->EmitIntValue(Length - 4, 4);
505 // The 2 byte version, which is 2.
506 MCOS->EmitIntValue(2, 2);
507 // The 4 byte offset to the compile unit in the .debug_info from the start
508 // of the .debug_info.
509 if (InfoSectionSymbol)
510 MCOS->EmitSymbolValue(InfoSectionSymbol, 4);
512 MCOS->EmitIntValue(0, 4);
513 // The 1 byte size of an address.
514 MCOS->EmitIntValue(AddrSize, 1);
515 // The 1 byte size of a segment descriptor, we use a value of zero.
516 MCOS->EmitIntValue(0, 1);
517 // Align the header with the padding if needed, before we put out the table.
518 for(int i = 0; i < Pad; i++)
519 MCOS->EmitIntValue(0, 1);
521 // Now emit the table of pairs of PointerSize'ed values for the section(s)
522 // address and size, in our case just the one default .text section.
523 const MCExpr *Addr = MCSymbolRefExpr::Create(
524 context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
525 const MCExpr *Size = MakeStartMinusEndExpr(*MCOS,
526 *context.getGenDwarfSectionStartSym(), *SectionEndSym, 0);
527 MCOS->EmitAbsValue(Addr, AddrSize);
528 MCOS->EmitAbsValue(Size, AddrSize);
530 // And finally the pair of terminating zeros.
531 MCOS->EmitIntValue(0, AddrSize);
532 MCOS->EmitIntValue(0, AddrSize);
535 // When generating dwarf for assembly source files this emits the data for
536 // .debug_info section which contains three parts. The header, the compile_unit
537 // DIE and a list of label DIEs.
538 static void EmitGenDwarfInfo(MCStreamer *MCOS,
539 const MCSymbol *AbbrevSectionSymbol,
540 const MCSymbol *LineSectionSymbol) {
541 MCContext &context = MCOS->getContext();
543 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
545 // Create a symbol at the start and end of this section used in here for the
546 // expression to calculate the length in the header.
547 MCSymbol *InfoStart = context.CreateTempSymbol();
548 MCOS->EmitLabel(InfoStart);
549 MCSymbol *InfoEnd = context.CreateTempSymbol();
551 // First part: the header.
553 // The 4 byte total length of the information for this compilation unit, not
554 // including these 4 bytes.
555 const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4);
556 MCOS->EmitAbsValue(Length, 4);
558 // The 2 byte DWARF version, which is 2.
559 MCOS->EmitIntValue(2, 2);
561 // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev,
562 // it is at the start of that section so this is zero.
563 if (AbbrevSectionSymbol) {
564 MCOS->EmitSymbolValue(AbbrevSectionSymbol, 4);
566 MCOS->EmitIntValue(0, 4);
569 const MCAsmInfo *asmInfo = context.getAsmInfo();
570 int AddrSize = asmInfo->getPointerSize();
571 // The 1 byte size of an address.
572 MCOS->EmitIntValue(AddrSize, 1);
574 // Second part: the compile_unit DIE.
576 // The DW_TAG_compile_unit DIE abbrev (1).
577 MCOS->EmitULEB128IntValue(1);
579 // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section,
580 // which is at the start of that section so this is zero.
581 if (LineSectionSymbol) {
582 MCOS->EmitSymbolValue(LineSectionSymbol, 4);
584 MCOS->EmitIntValue(0, 4);
587 // AT_low_pc, the first address of the default .text section.
588 const MCExpr *Start = MCSymbolRefExpr::Create(
589 context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
590 MCOS->EmitAbsValue(Start, AddrSize);
592 // AT_high_pc, the last address of the default .text section.
593 const MCExpr *End = MCSymbolRefExpr::Create(
594 context.getGenDwarfSectionEndSym(), MCSymbolRefExpr::VK_None, context);
595 MCOS->EmitAbsValue(End, AddrSize);
597 // AT_name, the name of the source file. Reconstruct from the first directory
598 // and file table entries.
599 const SmallVectorImpl<std::string> &MCDwarfDirs = context.getMCDwarfDirs();
600 if (MCDwarfDirs.size() > 0) {
601 MCOS->EmitBytes(MCDwarfDirs[0]);
602 MCOS->EmitBytes("/");
604 const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles =
605 MCOS->getContext().getMCDwarfFiles();
606 MCOS->EmitBytes(MCDwarfFiles[1].Name);
607 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
609 // AT_comp_dir, the working directory the assembly was done in.
610 if (!context.getCompilationDir().empty()) {
611 MCOS->EmitBytes(context.getCompilationDir());
612 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
615 // AT_APPLE_flags, the command line arguments of the assembler tool.
616 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
617 if (!DwarfDebugFlags.empty()){
618 MCOS->EmitBytes(DwarfDebugFlags);
619 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
622 // AT_producer, the version of the assembler tool.
623 StringRef DwarfDebugProducer = context.getDwarfDebugProducer();
624 if (!DwarfDebugProducer.empty()){
625 MCOS->EmitBytes(DwarfDebugProducer);
628 MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM "));
629 MCOS->EmitBytes(StringRef(PACKAGE_VERSION));
630 MCOS->EmitBytes(StringRef(")"));
632 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
634 // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2
635 // draft has no standard code for assembler.
636 MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2);
638 // Third part: the list of label DIEs.
640 // Loop on saved info for dwarf labels and create the DIEs for them.
641 const std::vector<const MCGenDwarfLabelEntry *> &Entries =
642 MCOS->getContext().getMCGenDwarfLabelEntries();
643 for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it =
644 Entries.begin(), ie = Entries.end(); it != ie;
646 const MCGenDwarfLabelEntry *Entry = *it;
648 // The DW_TAG_label DIE abbrev (2).
649 MCOS->EmitULEB128IntValue(2);
651 // AT_name, of the label without any leading underbar.
652 MCOS->EmitBytes(Entry->getName());
653 MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
655 // AT_decl_file, index into the file table.
656 MCOS->EmitIntValue(Entry->getFileNumber(), 4);
658 // AT_decl_line, source line number.
659 MCOS->EmitIntValue(Entry->getLineNumber(), 4);
661 // AT_low_pc, start address of the label.
662 const MCExpr *AT_low_pc = MCSymbolRefExpr::Create(Entry->getLabel(),
663 MCSymbolRefExpr::VK_None, context);
664 MCOS->EmitAbsValue(AT_low_pc, AddrSize);
666 // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype.
667 MCOS->EmitIntValue(0, 1);
669 // The DW_TAG_unspecified_parameters DIE abbrev (3).
670 MCOS->EmitULEB128IntValue(3);
672 // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's.
673 MCOS->EmitIntValue(0, 1);
675 // Deallocate the MCGenDwarfLabelEntry classes that saved away the info
676 // for the dwarf labels.
677 for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it =
678 Entries.begin(), ie = Entries.end(); it != ie;
680 const MCGenDwarfLabelEntry *Entry = *it;
684 // Add the NULL DIE terminating the Compile Unit DIE's.
685 MCOS->EmitIntValue(0, 1);
687 // Now set the value of the symbol at the end of the info section.
688 MCOS->EmitLabel(InfoEnd);
692 // When generating dwarf for assembly source files this emits the Dwarf
695 void MCGenDwarfInfo::Emit(MCStreamer *MCOS, const MCSymbol *LineSectionSymbol) {
696 // Create the dwarf sections in this order (.debug_line already created).
697 MCContext &context = MCOS->getContext();
698 const MCAsmInfo *AsmInfo = context.getAsmInfo();
699 bool CreateDwarfSectionSymbols =
700 AsmInfo->doesDwarfUseRelocationsAcrossSections();
701 if (!CreateDwarfSectionSymbols)
702 LineSectionSymbol = NULL;
703 MCSymbol *AbbrevSectionSymbol = NULL;
704 MCSymbol *InfoSectionSymbol = NULL;
705 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
706 if (CreateDwarfSectionSymbols) {
707 InfoSectionSymbol = context.CreateTempSymbol();
708 MCOS->EmitLabel(InfoSectionSymbol);
710 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
711 if (CreateDwarfSectionSymbols) {
712 AbbrevSectionSymbol = context.CreateTempSymbol();
713 MCOS->EmitLabel(AbbrevSectionSymbol);
715 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
717 // If there are no line table entries then do not emit any section contents.
718 if (!context.hasMCLineSections())
721 // Output the data for .debug_aranges section.
722 EmitGenDwarfAranges(MCOS, InfoSectionSymbol);
724 // Output the data for .debug_abbrev section.
725 EmitGenDwarfAbbrev(MCOS);
727 // Output the data for .debug_info section.
728 EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol);
732 // When generating dwarf for assembly source files this is called when symbol
733 // for a label is created. If this symbol is not a temporary and is in the
734 // section that dwarf is being generated for, save the needed info to create
737 void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
738 SourceMgr &SrcMgr, SMLoc &Loc) {
739 // We won't create dwarf labels for temporary symbols or symbols not in
741 if (Symbol->isTemporary())
743 MCContext &context = MCOS->getContext();
744 if (context.getGenDwarfSection() != MCOS->getCurrentSection().first)
747 // The dwarf label's name does not have the symbol name's leading
749 StringRef Name = Symbol->getName();
750 if (Name.startswith("_"))
751 Name = Name.substr(1, Name.size()-1);
753 // Get the dwarf file number to be used for the dwarf label.
754 unsigned FileNumber = context.getGenDwarfFileNumber();
756 // Finding the line number is the expensive part which is why we just don't
757 // pass it in as for some symbols we won't create a dwarf label.
758 int CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
759 unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
761 // We create a temporary symbol for use for the AT_high_pc and AT_low_pc
762 // values so that they don't have things like an ARM thumb bit from the
763 // original symbol. So when used they won't get a low bit set after
765 MCSymbol *Label = context.CreateTempSymbol();
766 MCOS->EmitLabel(Label);
768 // Create and entry for the info and add it to the other entries.
769 MCGenDwarfLabelEntry *Entry =
770 new MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label);
771 MCOS->getContext().addMCGenDwarfLabelEntry(Entry);
774 static int getDataAlignmentFactor(MCStreamer &streamer) {
775 MCContext &context = streamer.getContext();
776 const MCAsmInfo *asmInfo = context.getAsmInfo();
777 int size = asmInfo->getCalleeSaveStackSlotSize();
778 if (asmInfo->isStackGrowthDirectionUp())
784 static unsigned getSizeForEncoding(MCStreamer &streamer,
785 unsigned symbolEncoding) {
786 MCContext &context = streamer.getContext();
787 unsigned format = symbolEncoding & 0x0f;
789 default: llvm_unreachable("Unknown Encoding");
790 case dwarf::DW_EH_PE_absptr:
791 case dwarf::DW_EH_PE_signed:
792 return context.getAsmInfo()->getPointerSize();
793 case dwarf::DW_EH_PE_udata2:
794 case dwarf::DW_EH_PE_sdata2:
796 case dwarf::DW_EH_PE_udata4:
797 case dwarf::DW_EH_PE_sdata4:
799 case dwarf::DW_EH_PE_udata8:
800 case dwarf::DW_EH_PE_sdata8:
805 static void EmitFDESymbol(MCStreamer &streamer, const MCSymbol &symbol,
806 unsigned symbolEncoding, bool isEH,
807 const char *comment = 0) {
808 MCContext &context = streamer.getContext();
809 const MCAsmInfo *asmInfo = context.getAsmInfo();
810 const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol,
813 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
814 if (streamer.isVerboseAsm() && comment) streamer.AddComment(comment);
815 if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH)
816 streamer.EmitAbsValue(v, size);
818 streamer.EmitValue(v, size);
821 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
822 unsigned symbolEncoding) {
823 MCContext &context = streamer.getContext();
824 const MCAsmInfo *asmInfo = context.getAsmInfo();
825 const MCExpr *v = asmInfo->getExprForPersonalitySymbol(&symbol,
828 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
829 streamer.EmitValue(v, size);
833 class FrameEmitterImpl {
838 const MCSymbol *SectionStart;
840 FrameEmitterImpl(bool usingCFI, bool isEH)
841 : CFAOffset(0), CIENum(0), UsingCFI(usingCFI), IsEH(isEH),
844 void setSectionStart(const MCSymbol *Label) { SectionStart = Label; }
846 /// EmitCompactUnwind - Emit the unwind information in a compact way.
847 void EmitCompactUnwind(MCStreamer &streamer,
848 const MCDwarfFrameInfo &frame);
850 const MCSymbol &EmitCIE(MCStreamer &streamer,
851 const MCSymbol *personality,
852 unsigned personalityEncoding,
853 const MCSymbol *lsda,
855 unsigned lsdaEncoding,
857 MCSymbol *EmitFDE(MCStreamer &streamer,
858 const MCSymbol &cieStart,
859 const MCDwarfFrameInfo &frame);
860 void EmitCFIInstructions(MCStreamer &streamer,
861 ArrayRef<MCCFIInstruction> Instrs,
862 MCSymbol *BaseLabel);
863 void EmitCFIInstruction(MCStreamer &Streamer,
864 const MCCFIInstruction &Instr);
867 } // end anonymous namespace
869 static void EmitEncodingByte(MCStreamer &Streamer, unsigned Encoding,
871 if (Streamer.isVerboseAsm()) {
874 default: EncStr = "<unknown encoding>"; break;
875 case dwarf::DW_EH_PE_absptr: EncStr = "absptr"; break;
876 case dwarf::DW_EH_PE_omit: EncStr = "omit"; break;
877 case dwarf::DW_EH_PE_pcrel: EncStr = "pcrel"; break;
878 case dwarf::DW_EH_PE_udata4: EncStr = "udata4"; break;
879 case dwarf::DW_EH_PE_udata8: EncStr = "udata8"; break;
880 case dwarf::DW_EH_PE_sdata4: EncStr = "sdata4"; break;
881 case dwarf::DW_EH_PE_sdata8: EncStr = "sdata8"; break;
882 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
883 EncStr = "pcrel udata4";
885 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
886 EncStr = "pcrel sdata4";
888 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
889 EncStr = "pcrel udata8";
891 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
892 EncStr = "screl sdata8";
894 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata4:
895 EncStr = "indirect pcrel udata4";
897 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata4:
898 EncStr = "indirect pcrel sdata4";
900 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata8:
901 EncStr = "indirect pcrel udata8";
903 case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata8:
904 EncStr = "indirect pcrel sdata8";
908 Streamer.AddComment(Twine(Prefix) + " = " + EncStr);
911 Streamer.EmitIntValue(Encoding, 1);
914 void FrameEmitterImpl::EmitCFIInstruction(MCStreamer &Streamer,
915 const MCCFIInstruction &Instr) {
916 int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
917 bool VerboseAsm = Streamer.isVerboseAsm();
919 switch (Instr.getOperation()) {
920 case MCCFIInstruction::OpRegister: {
921 unsigned Reg1 = Instr.getRegister();
922 unsigned Reg2 = Instr.getRegister2();
924 Streamer.AddComment("DW_CFA_register");
925 Streamer.AddComment(Twine("Reg1 ") + Twine(Reg1));
926 Streamer.AddComment(Twine("Reg2 ") + Twine(Reg2));
928 Streamer.EmitIntValue(dwarf::DW_CFA_register, 1);
929 Streamer.EmitULEB128IntValue(Reg1);
930 Streamer.EmitULEB128IntValue(Reg2);
933 case MCCFIInstruction::OpWindowSave: {
934 Streamer.EmitIntValue(dwarf::DW_CFA_GNU_window_save, 1);
937 case MCCFIInstruction::OpUndefined: {
938 unsigned Reg = Instr.getRegister();
940 Streamer.AddComment("DW_CFA_undefined");
941 Streamer.AddComment(Twine("Reg ") + Twine(Reg));
943 Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1);
944 Streamer.EmitULEB128IntValue(Reg);
947 case MCCFIInstruction::OpAdjustCfaOffset:
948 case MCCFIInstruction::OpDefCfaOffset: {
949 const bool IsRelative =
950 Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset;
953 Streamer.AddComment("DW_CFA_def_cfa_offset");
954 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
957 CFAOffset += Instr.getOffset();
959 CFAOffset = -Instr.getOffset();
962 Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
963 Streamer.EmitULEB128IntValue(CFAOffset);
967 case MCCFIInstruction::OpDefCfa: {
969 Streamer.AddComment("DW_CFA_def_cfa");
970 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
973 Streamer.AddComment(Twine("Reg ") + Twine(Instr.getRegister()));
974 Streamer.EmitULEB128IntValue(Instr.getRegister());
976 CFAOffset = -Instr.getOffset();
979 Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
980 Streamer.EmitULEB128IntValue(CFAOffset);
985 case MCCFIInstruction::OpDefCfaRegister: {
987 Streamer.AddComment("DW_CFA_def_cfa_register");
988 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
991 Streamer.AddComment(Twine("Reg ") + Twine(Instr.getRegister()));
992 Streamer.EmitULEB128IntValue(Instr.getRegister());
997 case MCCFIInstruction::OpOffset:
998 case MCCFIInstruction::OpRelOffset: {
999 const bool IsRelative =
1000 Instr.getOperation() == MCCFIInstruction::OpRelOffset;
1002 unsigned Reg = Instr.getRegister();
1003 int Offset = Instr.getOffset();
1005 Offset -= CFAOffset;
1006 Offset = Offset / dataAlignmentFactor;
1009 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended_sf");
1010 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
1011 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1012 Streamer.EmitULEB128IntValue(Reg);
1013 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1014 Streamer.EmitSLEB128IntValue(Offset);
1015 } else if (Reg < 64) {
1016 if (VerboseAsm) Streamer.AddComment(Twine("DW_CFA_offset + Reg(") +
1018 Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
1019 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1020 Streamer.EmitULEB128IntValue(Offset);
1022 if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended");
1023 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
1024 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1025 Streamer.EmitULEB128IntValue(Reg);
1026 if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
1027 Streamer.EmitULEB128IntValue(Offset);
1031 case MCCFIInstruction::OpRememberState:
1032 if (VerboseAsm) Streamer.AddComment("DW_CFA_remember_state");
1033 Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
1035 case MCCFIInstruction::OpRestoreState:
1036 if (VerboseAsm) Streamer.AddComment("DW_CFA_restore_state");
1037 Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
1039 case MCCFIInstruction::OpSameValue: {
1040 unsigned Reg = Instr.getRegister();
1041 if (VerboseAsm) Streamer.AddComment("DW_CFA_same_value");
1042 Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
1043 if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1044 Streamer.EmitULEB128IntValue(Reg);
1047 case MCCFIInstruction::OpRestore: {
1048 unsigned Reg = Instr.getRegister();
1050 Streamer.AddComment("DW_CFA_restore");
1051 Streamer.AddComment(Twine("Reg ") + Twine(Reg));
1053 Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1);
1056 case MCCFIInstruction::OpEscape:
1057 if (VerboseAsm) Streamer.AddComment("Escape bytes");
1058 Streamer.EmitBytes(Instr.getValues());
1061 llvm_unreachable("Unhandled case in switch");
1064 /// EmitFrameMoves - Emit frame instructions to describe the layout of the
1066 void FrameEmitterImpl::EmitCFIInstructions(MCStreamer &streamer,
1067 ArrayRef<MCCFIInstruction> Instrs,
1068 MCSymbol *BaseLabel) {
1069 for (unsigned i = 0, N = Instrs.size(); i < N; ++i) {
1070 const MCCFIInstruction &Instr = Instrs[i];
1071 MCSymbol *Label = Instr.getLabel();
1072 // Throw out move if the label is invalid.
1073 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
1075 // Advance row if new location.
1076 if (BaseLabel && Label) {
1077 MCSymbol *ThisSym = Label;
1078 if (ThisSym != BaseLabel) {
1079 if (streamer.isVerboseAsm()) streamer.AddComment("DW_CFA_advance_loc4");
1080 streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
1081 BaseLabel = ThisSym;
1085 EmitCFIInstruction(streamer, Instr);
1089 /// EmitCompactUnwind - Emit the unwind information in a compact way.
1090 void FrameEmitterImpl::EmitCompactUnwind(MCStreamer &Streamer,
1091 const MCDwarfFrameInfo &Frame) {
1092 MCContext &Context = Streamer.getContext();
1093 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1094 bool VerboseAsm = Streamer.isVerboseAsm();
1096 // range-start range-length compact-unwind-enc personality-func lsda
1097 // _foo LfooEnd-_foo 0x00000023 0 0
1098 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1
1100 // .section __LD,__compact_unwind,regular,debug
1102 // # compact unwind for _foo
1104 // .set L1,LfooEnd-_foo
1110 // # compact unwind for _bar
1112 // .set L2,LbarEnd-_bar
1115 // .quad __gxx_personality
1116 // .quad except_tab1
1118 uint32_t Encoding = Frame.CompactUnwindEncoding;
1119 if (!Encoding) return;
1120 bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly());
1122 // The encoding needs to know we have an LSDA.
1123 if (!DwarfEHFrameOnly && Frame.Lsda)
1124 Encoding |= 0x40000000;
1127 unsigned FDEEncoding = MOFI->getFDEEncoding(UsingCFI);
1128 unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
1129 if (VerboseAsm) Streamer.AddComment("Range Start");
1130 Streamer.EmitSymbolValue(Frame.Function, Size);
1133 const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin,
1135 if (VerboseAsm) Streamer.AddComment("Range Length");
1136 Streamer.EmitAbsValue(Range, 4);
1139 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
1140 if (VerboseAsm) Streamer.AddComment("Compact Unwind Encoding: 0x" +
1141 Twine::utohexstr(Encoding));
1142 Streamer.EmitIntValue(Encoding, Size);
1144 // Personality Function
1145 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
1146 if (VerboseAsm) Streamer.AddComment("Personality Function");
1147 if (!DwarfEHFrameOnly && Frame.Personality)
1148 Streamer.EmitSymbolValue(Frame.Personality, Size);
1150 Streamer.EmitIntValue(0, Size); // No personality fn
1153 Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
1154 if (VerboseAsm) Streamer.AddComment("LSDA");
1155 if (!DwarfEHFrameOnly && Frame.Lsda)
1156 Streamer.EmitSymbolValue(Frame.Lsda, Size);
1158 Streamer.EmitIntValue(0, Size); // No LSDA
1161 const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
1162 const MCSymbol *personality,
1163 unsigned personalityEncoding,
1164 const MCSymbol *lsda,
1166 unsigned lsdaEncoding,
1168 MCContext &context = streamer.getContext();
1169 const MCRegisterInfo *MRI = context.getRegisterInfo();
1170 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1171 bool verboseAsm = streamer.isVerboseAsm();
1173 MCSymbol *sectionStart;
1174 if (MOFI->isFunctionEHFrameSymbolPrivate() || !IsEH)
1175 sectionStart = context.CreateTempSymbol();
1177 sectionStart = context.GetOrCreateSymbol(Twine("EH_frame") + Twine(CIENum));
1179 streamer.EmitLabel(sectionStart);
1182 MCSymbol *sectionEnd = context.CreateTempSymbol();
1185 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *sectionStart,
1187 if (verboseAsm) streamer.AddComment("CIE Length");
1188 streamer.EmitAbsValue(Length, 4);
1191 unsigned CIE_ID = IsEH ? 0 : -1;
1192 if (verboseAsm) streamer.AddComment("CIE ID Tag");
1193 streamer.EmitIntValue(CIE_ID, 4);
1196 if (verboseAsm) streamer.AddComment("DW_CIE_VERSION");
1197 streamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1);
1199 // Augmentation String
1200 SmallString<8> Augmentation;
1202 if (verboseAsm) streamer.AddComment("CIE Augmentation");
1203 Augmentation += "z";
1205 Augmentation += "P";
1207 Augmentation += "L";
1208 Augmentation += "R";
1210 Augmentation += "S";
1211 streamer.EmitBytes(Augmentation.str());
1213 streamer.EmitIntValue(0, 1);
1215 // Code Alignment Factor
1216 if (verboseAsm) streamer.AddComment("CIE Code Alignment Factor");
1217 streamer.EmitULEB128IntValue(context.getAsmInfo()->getMinInstAlignment());
1219 // Data Alignment Factor
1220 if (verboseAsm) streamer.AddComment("CIE Data Alignment Factor");
1221 streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer));
1223 // Return Address Register
1224 if (verboseAsm) streamer.AddComment("CIE Return Address Column");
1225 streamer.EmitULEB128IntValue(MRI->getDwarfRegNum(MRI->getRARegister(), true));
1227 // Augmentation Data Length (optional)
1229 unsigned augmentationLength = 0;
1232 // Personality Encoding
1233 augmentationLength += 1;
1235 augmentationLength += getSizeForEncoding(streamer, personalityEncoding);
1238 augmentationLength += 1;
1239 // Encoding of the FDE pointers
1240 augmentationLength += 1;
1242 if (verboseAsm) streamer.AddComment("Augmentation Size");
1243 streamer.EmitULEB128IntValue(augmentationLength);
1245 // Augmentation Data (optional)
1247 // Personality Encoding
1248 EmitEncodingByte(streamer, personalityEncoding,
1249 "Personality Encoding");
1251 if (verboseAsm) streamer.AddComment("Personality");
1252 EmitPersonality(streamer, *personality, personalityEncoding);
1256 EmitEncodingByte(streamer, lsdaEncoding, "LSDA Encoding");
1258 // Encoding of the FDE pointers
1259 EmitEncodingByte(streamer, MOFI->getFDEEncoding(UsingCFI),
1263 // Initial Instructions
1265 const MCAsmInfo *MAI = context.getAsmInfo();
1267 const std::vector<MCCFIInstruction> &Instructions =
1268 MAI->getInitialFrameState();
1269 EmitCFIInstructions(streamer, Instructions, NULL);
1273 streamer.EmitValueToAlignment(IsEH ? 4 : MAI->getPointerSize());
1275 streamer.EmitLabel(sectionEnd);
1276 return *sectionStart;
1279 MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
1280 const MCSymbol &cieStart,
1281 const MCDwarfFrameInfo &frame) {
1282 MCContext &context = streamer.getContext();
1283 MCSymbol *fdeStart = context.CreateTempSymbol();
1284 MCSymbol *fdeEnd = context.CreateTempSymbol();
1285 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1286 bool verboseAsm = streamer.isVerboseAsm();
1288 if (IsEH && frame.Function && !MOFI->isFunctionEHFrameSymbolPrivate()) {
1290 context.GetOrCreateSymbol(frame.Function->getName() + Twine(".eh"));
1291 streamer.EmitEHSymAttributes(frame.Function, EHSym);
1292 streamer.EmitLabel(EHSym);
1296 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *fdeStart, *fdeEnd, 0);
1297 if (verboseAsm) streamer.AddComment("FDE Length");
1298 streamer.EmitAbsValue(Length, 4);
1300 streamer.EmitLabel(fdeStart);
1303 const MCAsmInfo *asmInfo = context.getAsmInfo();
1305 const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart,
1307 if (verboseAsm) streamer.AddComment("FDE CIE Offset");
1308 streamer.EmitAbsValue(offset, 4);
1309 } else if (!asmInfo->doesDwarfUseRelocationsAcrossSections()) {
1310 const MCExpr *offset = MakeStartMinusEndExpr(streamer, *SectionStart,
1312 streamer.EmitAbsValue(offset, 4);
1314 streamer.EmitSymbolValue(&cieStart, 4);
1318 unsigned PCEncoding = IsEH ? MOFI->getFDEEncoding(UsingCFI)
1319 : (unsigned)dwarf::DW_EH_PE_absptr;
1320 unsigned PCSize = getSizeForEncoding(streamer, PCEncoding);
1321 EmitFDESymbol(streamer, *frame.Begin, PCEncoding, IsEH, "FDE initial location");
1324 const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin,
1326 if (verboseAsm) streamer.AddComment("FDE address range");
1327 streamer.EmitAbsValue(Range, PCSize);
1330 // Augmentation Data Length
1331 unsigned augmentationLength = 0;
1334 augmentationLength += getSizeForEncoding(streamer, frame.LsdaEncoding);
1336 if (verboseAsm) streamer.AddComment("Augmentation size");
1337 streamer.EmitULEB128IntValue(augmentationLength);
1339 // Augmentation Data
1341 EmitFDESymbol(streamer, *frame.Lsda, frame.LsdaEncoding, true,
1342 "Language Specific Data Area");
1345 // Call Frame Instructions
1346 EmitCFIInstructions(streamer, frame.Instructions, frame.Begin);
1349 streamer.EmitValueToAlignment(PCSize);
1356 static const CIEKey getEmptyKey() { return CIEKey(0, 0, -1, false, false); }
1357 static const CIEKey getTombstoneKey() { return CIEKey(0, -1, 0, false, false); }
1359 CIEKey(const MCSymbol* Personality_, unsigned PersonalityEncoding_,
1360 unsigned LsdaEncoding_, bool IsSignalFrame_, bool IsSimple_) :
1361 Personality(Personality_), PersonalityEncoding(PersonalityEncoding_),
1362 LsdaEncoding(LsdaEncoding_), IsSignalFrame(IsSignalFrame_),
1363 IsSimple(IsSimple_) {
1365 const MCSymbol* Personality;
1366 unsigned PersonalityEncoding;
1367 unsigned LsdaEncoding;
1375 struct DenseMapInfo<CIEKey> {
1376 static CIEKey getEmptyKey() {
1377 return CIEKey::getEmptyKey();
1379 static CIEKey getTombstoneKey() {
1380 return CIEKey::getTombstoneKey();
1382 static unsigned getHashValue(const CIEKey &Key) {
1383 return static_cast<unsigned>(hash_combine(Key.Personality,
1384 Key.PersonalityEncoding,
1389 static bool isEqual(const CIEKey &LHS,
1390 const CIEKey &RHS) {
1391 return LHS.Personality == RHS.Personality &&
1392 LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
1393 LHS.LsdaEncoding == RHS.LsdaEncoding &&
1394 LHS.IsSignalFrame == RHS.IsSignalFrame &&
1395 LHS.IsSimple == RHS.IsSimple;
1400 void MCDwarfFrameEmitter::Emit(MCStreamer &Streamer, MCAsmBackend *MAB,
1401 bool UsingCFI, bool IsEH) {
1402 Streamer.generateCompactUnwindEncodings(MAB);
1404 MCContext &Context = Streamer.getContext();
1405 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1406 FrameEmitterImpl Emitter(UsingCFI, IsEH);
1407 ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getFrameInfos();
1409 // Emit the compact unwind info if available.
1410 if (IsEH && MOFI->getCompactUnwindSection()) {
1411 bool SectionEmitted = false;
1412 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
1413 const MCDwarfFrameInfo &Frame = FrameArray[i];
1414 if (Frame.CompactUnwindEncoding == 0) continue;
1415 if (!SectionEmitted) {
1416 Streamer.SwitchSection(MOFI->getCompactUnwindSection());
1417 Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize());
1418 SectionEmitted = true;
1420 Emitter.EmitCompactUnwind(Streamer, Frame);
1424 const MCSection &Section =
1425 IsEH ? *const_cast<MCObjectFileInfo*>(MOFI)->getEHFrameSection() :
1426 *MOFI->getDwarfFrameSection();
1427 Streamer.SwitchSection(&Section);
1428 MCSymbol *SectionStart = Context.CreateTempSymbol();
1429 Streamer.EmitLabel(SectionStart);
1430 Emitter.setSectionStart(SectionStart);
1432 MCSymbol *FDEEnd = NULL;
1433 DenseMap<CIEKey, const MCSymbol*> CIEStarts;
1435 const MCSymbol *DummyDebugKey = NULL;
1436 for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
1437 const MCDwarfFrameInfo &Frame = FrameArray[i];
1438 CIEKey Key(Frame.Personality, Frame.PersonalityEncoding,
1439 Frame.LsdaEncoding, Frame.IsSignalFrame, Frame.IsSimple);
1440 const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
1442 CIEStart = &Emitter.EmitCIE(Streamer, Frame.Personality,
1443 Frame.PersonalityEncoding, Frame.Lsda,
1444 Frame.IsSignalFrame,
1448 FDEEnd = Emitter.EmitFDE(Streamer, *CIEStart, Frame);
1451 Streamer.EmitLabel(FDEEnd);
1454 Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize());
1456 Streamer.EmitLabel(FDEEnd);
1459 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCStreamer &Streamer,
1460 uint64_t AddrDelta) {
1461 MCContext &Context = Streamer.getContext();
1462 SmallString<256> Tmp;
1463 raw_svector_ostream OS(Tmp);
1464 MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OS);
1465 Streamer.EmitBytes(OS.str());
1468 void MCDwarfFrameEmitter::EncodeAdvanceLoc(MCContext &Context,
1471 // Scale the address delta by the minimum instruction length.
1472 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
1474 if (AddrDelta == 0) {
1475 } else if (isUIntN(6, AddrDelta)) {
1476 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
1478 } else if (isUInt<8>(AddrDelta)) {
1479 OS << uint8_t(dwarf::DW_CFA_advance_loc1);
1480 OS << uint8_t(AddrDelta);
1481 } else if (isUInt<16>(AddrDelta)) {
1482 // FIXME: check what is the correct behavior on a big endian machine.
1483 OS << uint8_t(dwarf::DW_CFA_advance_loc2);
1484 OS << uint8_t( AddrDelta & 0xff);
1485 OS << uint8_t((AddrDelta >> 8) & 0xff);
1487 // FIXME: check what is the correct behavior on a big endian machine.
1488 assert(isUInt<32>(AddrDelta));
1489 OS << uint8_t(dwarf::DW_CFA_advance_loc4);
1490 OS << uint8_t( AddrDelta & 0xff);
1491 OS << uint8_t((AddrDelta >> 8) & 0xff);
1492 OS << uint8_t((AddrDelta >> 16) & 0xff);
1493 OS << uint8_t((AddrDelta >> 24) & 0xff);