1 //===- lib/MC/MCDwarf.cpp - MCDwarf implementation ------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "llvm/MC/MCDwarf.h"
10 #include "llvm/ADT/ArrayRef.h"
11 #include "llvm/ADT/DenseMap.h"
12 #include "llvm/ADT/Hashing.h"
13 #include "llvm/ADT/Optional.h"
14 #include "llvm/ADT/STLExtras.h"
15 #include "llvm/ADT/SmallString.h"
16 #include "llvm/ADT/SmallVector.h"
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/ADT/Twine.h"
19 #include "llvm/BinaryFormat/Dwarf.h"
20 #include "llvm/Config/config.h"
21 #include "llvm/MC/MCAsmInfo.h"
22 #include "llvm/MC/MCContext.h"
23 #include "llvm/MC/MCExpr.h"
24 #include "llvm/MC/MCObjectFileInfo.h"
25 #include "llvm/MC/MCObjectStreamer.h"
26 #include "llvm/MC/MCRegisterInfo.h"
27 #include "llvm/MC/MCSection.h"
28 #include "llvm/MC/MCStreamer.h"
29 #include "llvm/MC/MCSymbol.h"
30 #include "llvm/Support/Casting.h"
31 #include "llvm/Support/Endian.h"
32 #include "llvm/Support/EndianStream.h"
33 #include "llvm/Support/ErrorHandling.h"
34 #include "llvm/Support/LEB128.h"
35 #include "llvm/Support/MathExtras.h"
36 #include "llvm/Support/Path.h"
37 #include "llvm/Support/SourceMgr.h"
38 #include "llvm/Support/raw_ostream.h"
39 #include <cassert>
40 #include <cstdint>
41 #include <string>
42 #include <utility>
43 #include <vector>
44
45 using namespace llvm;
46
emitListsTableHeaderStart(MCStreamer & S)47 MCSymbol *mcdwarf::emitListsTableHeaderStart(MCStreamer &S) {
48 MCSymbol *Start = S.getContext().createTempSymbol("debug_list_header_start");
49 MCSymbol *End = S.getContext().createTempSymbol("debug_list_header_end");
50 auto DwarfFormat = S.getContext().getDwarfFormat();
51 if (DwarfFormat == dwarf::DWARF64) {
52 S.AddComment("DWARF64 mark");
53 S.emitInt32(dwarf::DW_LENGTH_DWARF64);
54 }
55 S.AddComment("Length");
56 S.emitAbsoluteSymbolDiff(End, Start,
57 dwarf::getDwarfOffsetByteSize(DwarfFormat));
58 S.emitLabel(Start);
59 S.AddComment("Version");
60 S.emitInt16(S.getContext().getDwarfVersion());
61 S.AddComment("Address size");
62 S.emitInt8(S.getContext().getAsmInfo()->getCodePointerSize());
63 S.AddComment("Segment selector size");
64 S.emitInt8(0);
65 return End;
66 }
67
ScaleAddrDelta(MCContext & Context,uint64_t AddrDelta)68 static inline uint64_t ScaleAddrDelta(MCContext &Context, uint64_t AddrDelta) {
69 unsigned MinInsnLength = Context.getAsmInfo()->getMinInstAlignment();
70 if (MinInsnLength == 1)
71 return AddrDelta;
72 if (AddrDelta % MinInsnLength != 0) {
73 // TODO: report this error, but really only once.
74 ;
75 }
76 return AddrDelta / MinInsnLength;
77 }
78
MCDwarfLineStr(MCContext & Ctx)79 MCDwarfLineStr::MCDwarfLineStr(MCContext &Ctx) {
80 UseRelocs = Ctx.getAsmInfo()->doesDwarfUseRelocationsAcrossSections();
81 if (UseRelocs)
82 LineStrLabel =
83 Ctx.getObjectFileInfo()->getDwarfLineStrSection()->getBeginSymbol();
84 }
85
86 //
87 // This is called when an instruction is assembled into the specified section
88 // and if there is information from the last .loc directive that has yet to have
89 // a line entry made for it is made.
90 //
make(MCStreamer * MCOS,MCSection * Section)91 void MCDwarfLineEntry::make(MCStreamer *MCOS, MCSection *Section) {
92 if (!MCOS->getContext().getDwarfLocSeen())
93 return;
94
95 // Create a symbol at in the current section for use in the line entry.
96 MCSymbol *LineSym = MCOS->getContext().createTempSymbol();
97 // Set the value of the symbol to use for the MCDwarfLineEntry.
98 MCOS->emitLabel(LineSym);
99
100 // Get the current .loc info saved in the context.
101 const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();
102
103 // Create a (local) line entry with the symbol and the current .loc info.
104 MCDwarfLineEntry LineEntry(LineSym, DwarfLoc);
105
106 // clear DwarfLocSeen saying the current .loc info is now used.
107 MCOS->getContext().clearDwarfLocSeen();
108
109 // Add the line entry to this section's entries.
110 MCOS->getContext()
111 .getMCDwarfLineTable(MCOS->getContext().getDwarfCompileUnitID())
112 .getMCLineSections()
113 .addLineEntry(LineEntry, Section);
114 }
115
116 //
117 // This helper routine returns an expression of End - Start + IntVal .
118 //
makeEndMinusStartExpr(MCContext & Ctx,const MCSymbol & Start,const MCSymbol & End,int IntVal)119 static inline const MCExpr *makeEndMinusStartExpr(MCContext &Ctx,
120 const MCSymbol &Start,
121 const MCSymbol &End,
122 int IntVal) {
123 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
124 const MCExpr *Res = MCSymbolRefExpr::create(&End, Variant, Ctx);
125 const MCExpr *RHS = MCSymbolRefExpr::create(&Start, Variant, Ctx);
126 const MCExpr *Res1 = MCBinaryExpr::create(MCBinaryExpr::Sub, Res, RHS, Ctx);
127 const MCExpr *Res2 = MCConstantExpr::create(IntVal, Ctx);
128 const MCExpr *Res3 = MCBinaryExpr::create(MCBinaryExpr::Sub, Res1, Res2, Ctx);
129 return Res3;
130 }
131
132 //
133 // This helper routine returns an expression of Start + IntVal .
134 //
135 static inline const MCExpr *
makeStartPlusIntExpr(MCContext & Ctx,const MCSymbol & Start,int IntVal)136 makeStartPlusIntExpr(MCContext &Ctx, const MCSymbol &Start, int IntVal) {
137 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
138 const MCExpr *LHS = MCSymbolRefExpr::create(&Start, Variant, Ctx);
139 const MCExpr *RHS = MCConstantExpr::create(IntVal, Ctx);
140 const MCExpr *Res = MCBinaryExpr::create(MCBinaryExpr::Add, LHS, RHS, Ctx);
141 return Res;
142 }
143
144 //
145 // This emits the Dwarf line table for the specified section from the entries
146 // in the LineSection.
147 //
emitOne(MCStreamer * MCOS,MCSection * Section,const MCLineSection::MCDwarfLineEntryCollection & LineEntries)148 void MCDwarfLineTable::emitOne(
149 MCStreamer *MCOS, MCSection *Section,
150 const MCLineSection::MCDwarfLineEntryCollection &LineEntries) {
151 unsigned FileNum = 1;
152 unsigned LastLine = 1;
153 unsigned Column = 0;
154 unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
155 unsigned Isa = 0;
156 unsigned Discriminator = 0;
157 MCSymbol *LastLabel = nullptr;
158
159 // Loop through each MCDwarfLineEntry and encode the dwarf line number table.
160 for (const MCDwarfLineEntry &LineEntry : LineEntries) {
161 int64_t LineDelta = static_cast<int64_t>(LineEntry.getLine()) - LastLine;
162
163 if (FileNum != LineEntry.getFileNum()) {
164 FileNum = LineEntry.getFileNum();
165 MCOS->emitInt8(dwarf::DW_LNS_set_file);
166 MCOS->emitULEB128IntValue(FileNum);
167 }
168 if (Column != LineEntry.getColumn()) {
169 Column = LineEntry.getColumn();
170 MCOS->emitInt8(dwarf::DW_LNS_set_column);
171 MCOS->emitULEB128IntValue(Column);
172 }
173 if (Discriminator != LineEntry.getDiscriminator() &&
174 MCOS->getContext().getDwarfVersion() >= 4) {
175 Discriminator = LineEntry.getDiscriminator();
176 unsigned Size = getULEB128Size(Discriminator);
177 MCOS->emitInt8(dwarf::DW_LNS_extended_op);
178 MCOS->emitULEB128IntValue(Size + 1);
179 MCOS->emitInt8(dwarf::DW_LNE_set_discriminator);
180 MCOS->emitULEB128IntValue(Discriminator);
181 }
182 if (Isa != LineEntry.getIsa()) {
183 Isa = LineEntry.getIsa();
184 MCOS->emitInt8(dwarf::DW_LNS_set_isa);
185 MCOS->emitULEB128IntValue(Isa);
186 }
187 if ((LineEntry.getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
188 Flags = LineEntry.getFlags();
189 MCOS->emitInt8(dwarf::DW_LNS_negate_stmt);
190 }
191 if (LineEntry.getFlags() & DWARF2_FLAG_BASIC_BLOCK)
192 MCOS->emitInt8(dwarf::DW_LNS_set_basic_block);
193 if (LineEntry.getFlags() & DWARF2_FLAG_PROLOGUE_END)
194 MCOS->emitInt8(dwarf::DW_LNS_set_prologue_end);
195 if (LineEntry.getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
196 MCOS->emitInt8(dwarf::DW_LNS_set_epilogue_begin);
197
198 MCSymbol *Label = LineEntry.getLabel();
199
200 // At this point we want to emit/create the sequence to encode the delta in
201 // line numbers and the increment of the address from the previous Label
202 // and the current Label.
203 const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo();
204 MCOS->emitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label,
205 asmInfo->getCodePointerSize());
206
207 Discriminator = 0;
208 LastLine = LineEntry.getLine();
209 LastLabel = Label;
210 }
211
212 // Generate DWARF line end entry.
213 MCOS->emitDwarfLineEndEntry(Section, LastLabel);
214 }
215
216 //
217 // This emits the Dwarf file and the line tables.
218 //
emit(MCStreamer * MCOS,MCDwarfLineTableParams Params)219 void MCDwarfLineTable::emit(MCStreamer *MCOS, MCDwarfLineTableParams Params) {
220 MCContext &context = MCOS->getContext();
221
222 auto &LineTables = context.getMCDwarfLineTables();
223
224 // Bail out early so we don't switch to the debug_line section needlessly and
225 // in doing so create an unnecessary (if empty) section.
226 if (LineTables.empty())
227 return;
228
229 // In a v5 non-split line table, put the strings in a separate section.
230 Optional<MCDwarfLineStr> LineStr;
231 if (context.getDwarfVersion() >= 5)
232 LineStr = MCDwarfLineStr(context);
233
234 // Switch to the section where the table will be emitted into.
235 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
236
237 // Handle the rest of the Compile Units.
238 for (const auto &CUIDTablePair : LineTables) {
239 CUIDTablePair.second.emitCU(MCOS, Params, LineStr);
240 }
241
242 if (LineStr)
243 LineStr->emitSection(MCOS);
244 }
245
Emit(MCStreamer & MCOS,MCDwarfLineTableParams Params,MCSection * Section) const246 void MCDwarfDwoLineTable::Emit(MCStreamer &MCOS, MCDwarfLineTableParams Params,
247 MCSection *Section) const {
248 if (!HasSplitLineTable)
249 return;
250 Optional<MCDwarfLineStr> NoLineStr(None);
251 MCOS.SwitchSection(Section);
252 MCOS.emitLabel(Header.Emit(&MCOS, Params, None, NoLineStr).second);
253 }
254
255 std::pair<MCSymbol *, MCSymbol *>
Emit(MCStreamer * MCOS,MCDwarfLineTableParams Params,Optional<MCDwarfLineStr> & LineStr) const256 MCDwarfLineTableHeader::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
257 Optional<MCDwarfLineStr> &LineStr) const {
258 static const char StandardOpcodeLengths[] = {
259 0, // length of DW_LNS_copy
260 1, // length of DW_LNS_advance_pc
261 1, // length of DW_LNS_advance_line
262 1, // length of DW_LNS_set_file
263 1, // length of DW_LNS_set_column
264 0, // length of DW_LNS_negate_stmt
265 0, // length of DW_LNS_set_basic_block
266 0, // length of DW_LNS_const_add_pc
267 1, // length of DW_LNS_fixed_advance_pc
268 0, // length of DW_LNS_set_prologue_end
269 0, // length of DW_LNS_set_epilogue_begin
270 1 // DW_LNS_set_isa
271 };
272 assert(array_lengthof(StandardOpcodeLengths) >=
273 (Params.DWARF2LineOpcodeBase - 1U));
274 return Emit(
275 MCOS, Params,
276 makeArrayRef(StandardOpcodeLengths, Params.DWARF2LineOpcodeBase - 1),
277 LineStr);
278 }
279
forceExpAbs(MCStreamer & OS,const MCExpr * Expr)280 static const MCExpr *forceExpAbs(MCStreamer &OS, const MCExpr* Expr) {
281 MCContext &Context = OS.getContext();
282 assert(!isa<MCSymbolRefExpr>(Expr));
283 if (Context.getAsmInfo()->hasAggressiveSymbolFolding())
284 return Expr;
285
286 MCSymbol *ABS = Context.createTempSymbol();
287 OS.emitAssignment(ABS, Expr);
288 return MCSymbolRefExpr::create(ABS, Context);
289 }
290
emitAbsValue(MCStreamer & OS,const MCExpr * Value,unsigned Size)291 static void emitAbsValue(MCStreamer &OS, const MCExpr *Value, unsigned Size) {
292 const MCExpr *ABS = forceExpAbs(OS, Value);
293 OS.emitValue(ABS, Size);
294 }
295
emitSection(MCStreamer * MCOS)296 void MCDwarfLineStr::emitSection(MCStreamer *MCOS) {
297 // Switch to the .debug_line_str section.
298 MCOS->SwitchSection(
299 MCOS->getContext().getObjectFileInfo()->getDwarfLineStrSection());
300 // Emit the strings without perturbing the offsets we used.
301 LineStrings.finalizeInOrder();
302 SmallString<0> Data;
303 Data.resize(LineStrings.getSize());
304 LineStrings.write((uint8_t *)Data.data());
305 MCOS->emitBinaryData(Data.str());
306 }
307
emitRef(MCStreamer * MCOS,StringRef Path)308 void MCDwarfLineStr::emitRef(MCStreamer *MCOS, StringRef Path) {
309 int RefSize =
310 dwarf::getDwarfOffsetByteSize(MCOS->getContext().getDwarfFormat());
311 size_t Offset = LineStrings.add(Path);
312 if (UseRelocs) {
313 MCContext &Ctx = MCOS->getContext();
314 MCOS->emitValue(makeStartPlusIntExpr(Ctx, *LineStrLabel, Offset), RefSize);
315 } else
316 MCOS->emitIntValue(Offset, RefSize);
317 }
318
emitV2FileDirTables(MCStreamer * MCOS) const319 void MCDwarfLineTableHeader::emitV2FileDirTables(MCStreamer *MCOS) const {
320 // First the directory table.
321 for (auto &Dir : MCDwarfDirs) {
322 MCOS->emitBytes(Dir); // The DirectoryName, and...
323 MCOS->emitBytes(StringRef("\0", 1)); // its null terminator.
324 }
325 MCOS->emitInt8(0); // Terminate the directory list.
326
327 // Second the file table.
328 for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
329 assert(!MCDwarfFiles[i].Name.empty());
330 MCOS->emitBytes(MCDwarfFiles[i].Name); // FileName and...
331 MCOS->emitBytes(StringRef("\0", 1)); // its null terminator.
332 MCOS->emitULEB128IntValue(MCDwarfFiles[i].DirIndex); // Directory number.
333 MCOS->emitInt8(0); // Last modification timestamp (always 0).
334 MCOS->emitInt8(0); // File size (always 0).
335 }
336 MCOS->emitInt8(0); // Terminate the file list.
337 }
338
emitOneV5FileEntry(MCStreamer * MCOS,const MCDwarfFile & DwarfFile,bool EmitMD5,bool HasSource,Optional<MCDwarfLineStr> & LineStr)339 static void emitOneV5FileEntry(MCStreamer *MCOS, const MCDwarfFile &DwarfFile,
340 bool EmitMD5, bool HasSource,
341 Optional<MCDwarfLineStr> &LineStr) {
342 assert(!DwarfFile.Name.empty());
343 if (LineStr)
344 LineStr->emitRef(MCOS, DwarfFile.Name);
345 else {
346 MCOS->emitBytes(DwarfFile.Name); // FileName and...
347 MCOS->emitBytes(StringRef("\0", 1)); // its null terminator.
348 }
349 MCOS->emitULEB128IntValue(DwarfFile.DirIndex); // Directory number.
350 if (EmitMD5) {
351 const MD5::MD5Result &Cksum = *DwarfFile.Checksum;
352 MCOS->emitBinaryData(
353 StringRef(reinterpret_cast<const char *>(Cksum.Bytes.data()),
354 Cksum.Bytes.size()));
355 }
356 if (HasSource) {
357 if (LineStr)
358 LineStr->emitRef(MCOS, DwarfFile.Source.getValueOr(StringRef()));
359 else {
360 MCOS->emitBytes(
361 DwarfFile.Source.getValueOr(StringRef())); // Source and...
362 MCOS->emitBytes(StringRef("\0", 1)); // its null terminator.
363 }
364 }
365 }
366
emitV5FileDirTables(MCStreamer * MCOS,Optional<MCDwarfLineStr> & LineStr) const367 void MCDwarfLineTableHeader::emitV5FileDirTables(
368 MCStreamer *MCOS, Optional<MCDwarfLineStr> &LineStr) const {
369 // The directory format, which is just a list of the directory paths. In a
370 // non-split object, these are references to .debug_line_str; in a split
371 // object, they are inline strings.
372 MCOS->emitInt8(1);
373 MCOS->emitULEB128IntValue(dwarf::DW_LNCT_path);
374 MCOS->emitULEB128IntValue(LineStr ? dwarf::DW_FORM_line_strp
375 : dwarf::DW_FORM_string);
376 MCOS->emitULEB128IntValue(MCDwarfDirs.size() + 1);
377 // Try not to emit an empty compilation directory.
378 const StringRef CompDir = CompilationDir.empty()
379 ? MCOS->getContext().getCompilationDir()
380 : StringRef(CompilationDir);
381 if (LineStr) {
382 // Record path strings, emit references here.
383 LineStr->emitRef(MCOS, CompDir);
384 for (const auto &Dir : MCDwarfDirs)
385 LineStr->emitRef(MCOS, Dir);
386 } else {
387 // The list of directory paths. Compilation directory comes first.
388 MCOS->emitBytes(CompDir);
389 MCOS->emitBytes(StringRef("\0", 1));
390 for (const auto &Dir : MCDwarfDirs) {
391 MCOS->emitBytes(Dir); // The DirectoryName, and...
392 MCOS->emitBytes(StringRef("\0", 1)); // its null terminator.
393 }
394 }
395
396 // The file format, which is the inline null-terminated filename and a
397 // directory index. We don't track file size/timestamp so don't emit them
398 // in the v5 table. Emit MD5 checksums and source if we have them.
399 uint64_t Entries = 2;
400 if (HasAllMD5)
401 Entries += 1;
402 if (HasSource)
403 Entries += 1;
404 MCOS->emitInt8(Entries);
405 MCOS->emitULEB128IntValue(dwarf::DW_LNCT_path);
406 MCOS->emitULEB128IntValue(LineStr ? dwarf::DW_FORM_line_strp
407 : dwarf::DW_FORM_string);
408 MCOS->emitULEB128IntValue(dwarf::DW_LNCT_directory_index);
409 MCOS->emitULEB128IntValue(dwarf::DW_FORM_udata);
410 if (HasAllMD5) {
411 MCOS->emitULEB128IntValue(dwarf::DW_LNCT_MD5);
412 MCOS->emitULEB128IntValue(dwarf::DW_FORM_data16);
413 }
414 if (HasSource) {
415 MCOS->emitULEB128IntValue(dwarf::DW_LNCT_LLVM_source);
416 MCOS->emitULEB128IntValue(LineStr ? dwarf::DW_FORM_line_strp
417 : dwarf::DW_FORM_string);
418 }
419 // Then the counted list of files. The root file is file #0, then emit the
420 // files as provide by .file directives.
421 // MCDwarfFiles has an unused element [0] so use size() not size()+1.
422 // But sometimes MCDwarfFiles is empty, in which case we still emit one file.
423 MCOS->emitULEB128IntValue(MCDwarfFiles.empty() ? 1 : MCDwarfFiles.size());
424 // To accommodate assembler source written for DWARF v4 but trying to emit
425 // v5: If we didn't see a root file explicitly, replicate file #1.
426 assert((!RootFile.Name.empty() || MCDwarfFiles.size() >= 1) &&
427 "No root file and no .file directives");
428 emitOneV5FileEntry(MCOS, RootFile.Name.empty() ? MCDwarfFiles[1] : RootFile,
429 HasAllMD5, HasSource, LineStr);
430 for (unsigned i = 1; i < MCDwarfFiles.size(); ++i)
431 emitOneV5FileEntry(MCOS, MCDwarfFiles[i], HasAllMD5, HasSource, LineStr);
432 }
433
434 std::pair<MCSymbol *, MCSymbol *>
Emit(MCStreamer * MCOS,MCDwarfLineTableParams Params,ArrayRef<char> StandardOpcodeLengths,Optional<MCDwarfLineStr> & LineStr) const435 MCDwarfLineTableHeader::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
436 ArrayRef<char> StandardOpcodeLengths,
437 Optional<MCDwarfLineStr> &LineStr) const {
438 MCContext &context = MCOS->getContext();
439
440 // Create a symbol at the beginning of the line table.
441 MCSymbol *LineStartSym = Label;
442 if (!LineStartSym)
443 LineStartSym = context.createTempSymbol();
444
445 // Set the value of the symbol, as we are at the start of the line table.
446 MCOS->emitDwarfLineStartLabel(LineStartSym);
447
448 unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(context.getDwarfFormat());
449
450 MCSymbol *LineEndSym = MCOS->emitDwarfUnitLength("debug_line", "unit length");
451
452 // Next 2 bytes is the Version.
453 unsigned LineTableVersion = context.getDwarfVersion();
454 MCOS->emitInt16(LineTableVersion);
455
456 // In v5, we get address info next.
457 if (LineTableVersion >= 5) {
458 MCOS->emitInt8(context.getAsmInfo()->getCodePointerSize());
459 MCOS->emitInt8(0); // Segment selector; same as EmitGenDwarfAranges.
460 }
461
462 // Create symbols for the start/end of the prologue.
463 MCSymbol *ProStartSym = context.createTempSymbol("prologue_start");
464 MCSymbol *ProEndSym = context.createTempSymbol("prologue_end");
465
466 // Length of the prologue, is the next 4 bytes (8 bytes for DWARF64). This is
467 // actually the length from after the length word, to the end of the prologue.
468 MCOS->emitAbsoluteSymbolDiff(ProEndSym, ProStartSym, OffsetSize);
469
470 MCOS->emitLabel(ProStartSym);
471
472 // Parameters of the state machine, are next.
473 MCOS->emitInt8(context.getAsmInfo()->getMinInstAlignment());
474 // maximum_operations_per_instruction
475 // For non-VLIW architectures this field is always 1.
476 // FIXME: VLIW architectures need to update this field accordingly.
477 if (LineTableVersion >= 4)
478 MCOS->emitInt8(1);
479 MCOS->emitInt8(DWARF2_LINE_DEFAULT_IS_STMT);
480 MCOS->emitInt8(Params.DWARF2LineBase);
481 MCOS->emitInt8(Params.DWARF2LineRange);
482 MCOS->emitInt8(StandardOpcodeLengths.size() + 1);
483
484 // Standard opcode lengths
485 for (char Length : StandardOpcodeLengths)
486 MCOS->emitInt8(Length);
487
488 // Put out the directory and file tables. The formats vary depending on
489 // the version.
490 if (LineTableVersion >= 5)
491 emitV5FileDirTables(MCOS, LineStr);
492 else
493 emitV2FileDirTables(MCOS);
494
495 // This is the end of the prologue, so set the value of the symbol at the
496 // end of the prologue (that was used in a previous expression).
497 MCOS->emitLabel(ProEndSym);
498
499 return std::make_pair(LineStartSym, LineEndSym);
500 }
501
emitCU(MCStreamer * MCOS,MCDwarfLineTableParams Params,Optional<MCDwarfLineStr> & LineStr) const502 void MCDwarfLineTable::emitCU(MCStreamer *MCOS, MCDwarfLineTableParams Params,
503 Optional<MCDwarfLineStr> &LineStr) const {
504 MCSymbol *LineEndSym = Header.Emit(MCOS, Params, LineStr).second;
505
506 // Put out the line tables.
507 for (const auto &LineSec : MCLineSections.getMCLineEntries())
508 emitOne(MCOS, LineSec.first, LineSec.second);
509
510 // This is the end of the section, so set the value of the symbol at the end
511 // of this section (that was used in a previous expression).
512 MCOS->emitLabel(LineEndSym);
513 }
514
tryGetFile(StringRef & Directory,StringRef & FileName,Optional<MD5::MD5Result> Checksum,Optional<StringRef> Source,uint16_t DwarfVersion,unsigned FileNumber)515 Expected<unsigned> MCDwarfLineTable::tryGetFile(StringRef &Directory,
516 StringRef &FileName,
517 Optional<MD5::MD5Result> Checksum,
518 Optional<StringRef> Source,
519 uint16_t DwarfVersion,
520 unsigned FileNumber) {
521 return Header.tryGetFile(Directory, FileName, Checksum, Source, DwarfVersion,
522 FileNumber);
523 }
524
isRootFile(const MCDwarfFile & RootFile,StringRef & Directory,StringRef & FileName,Optional<MD5::MD5Result> Checksum)525 static bool isRootFile(const MCDwarfFile &RootFile, StringRef &Directory,
526 StringRef &FileName, Optional<MD5::MD5Result> Checksum) {
527 if (RootFile.Name.empty() || RootFile.Name != FileName.data())
528 return false;
529 return RootFile.Checksum == Checksum;
530 }
531
532 Expected<unsigned>
tryGetFile(StringRef & Directory,StringRef & FileName,Optional<MD5::MD5Result> Checksum,Optional<StringRef> Source,uint16_t DwarfVersion,unsigned FileNumber)533 MCDwarfLineTableHeader::tryGetFile(StringRef &Directory,
534 StringRef &FileName,
535 Optional<MD5::MD5Result> Checksum,
536 Optional<StringRef> Source,
537 uint16_t DwarfVersion,
538 unsigned FileNumber) {
539 if (Directory == CompilationDir)
540 Directory = "";
541 if (FileName.empty()) {
542 FileName = "<stdin>";
543 Directory = "";
544 }
545 assert(!FileName.empty());
546 // Keep track of whether any or all files have an MD5 checksum.
547 // If any files have embedded source, they all must.
548 if (MCDwarfFiles.empty()) {
549 trackMD5Usage(Checksum.hasValue());
550 HasSource = (Source != None);
551 }
552 if (isRootFile(RootFile, Directory, FileName, Checksum) && DwarfVersion >= 5)
553 return 0;
554 if (FileNumber == 0) {
555 // File numbers start with 1 and/or after any file numbers
556 // allocated by inline-assembler .file directives.
557 FileNumber = MCDwarfFiles.empty() ? 1 : MCDwarfFiles.size();
558 SmallString<256> Buffer;
559 auto IterBool = SourceIdMap.insert(
560 std::make_pair((Directory + Twine('\0') + FileName).toStringRef(Buffer),
561 FileNumber));
562 if (!IterBool.second)
563 return IterBool.first->second;
564 }
565 // Make space for this FileNumber in the MCDwarfFiles vector if needed.
566 if (FileNumber >= MCDwarfFiles.size())
567 MCDwarfFiles.resize(FileNumber + 1);
568
569 // Get the new MCDwarfFile slot for this FileNumber.
570 MCDwarfFile &File = MCDwarfFiles[FileNumber];
571
572 // It is an error to see the same number more than once.
573 if (!File.Name.empty())
574 return make_error<StringError>("file number already allocated",
575 inconvertibleErrorCode());
576
577 // If any files have embedded source, they all must.
578 if (HasSource != (Source != None))
579 return make_error<StringError>("inconsistent use of embedded source",
580 inconvertibleErrorCode());
581
582 if (Directory.empty()) {
583 // Separate the directory part from the basename of the FileName.
584 StringRef tFileName = sys::path::filename(FileName);
585 if (!tFileName.empty()) {
586 Directory = sys::path::parent_path(FileName);
587 if (!Directory.empty())
588 FileName = tFileName;
589 }
590 }
591
592 // Find or make an entry in the MCDwarfDirs vector for this Directory.
593 // Capture directory name.
594 unsigned DirIndex;
595 if (Directory.empty()) {
596 // For FileNames with no directories a DirIndex of 0 is used.
597 DirIndex = 0;
598 } else {
599 DirIndex = llvm::find(MCDwarfDirs, Directory) - MCDwarfDirs.begin();
600 if (DirIndex >= MCDwarfDirs.size())
601 MCDwarfDirs.push_back(std::string(Directory));
602 // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
603 // no directories. MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
604 // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
605 // are stored at MCDwarfFiles[FileNumber].Name .
606 DirIndex++;
607 }
608
609 File.Name = std::string(FileName);
610 File.DirIndex = DirIndex;
611 File.Checksum = Checksum;
612 trackMD5Usage(Checksum.hasValue());
613 File.Source = Source;
614 if (Source)
615 HasSource = true;
616
617 // return the allocated FileNumber.
618 return FileNumber;
619 }
620
621 /// Utility function to emit the encoding to a streamer.
Emit(MCStreamer * MCOS,MCDwarfLineTableParams Params,int64_t LineDelta,uint64_t AddrDelta)622 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
623 int64_t LineDelta, uint64_t AddrDelta) {
624 MCContext &Context = MCOS->getContext();
625 SmallString<256> Tmp;
626 raw_svector_ostream OS(Tmp);
627 MCDwarfLineAddr::Encode(Context, Params, LineDelta, AddrDelta, OS);
628 MCOS->emitBytes(OS.str());
629 }
630
631 /// Given a special op, return the address skip amount (in units of
632 /// DWARF2_LINE_MIN_INSN_LENGTH).
SpecialAddr(MCDwarfLineTableParams Params,uint64_t op)633 static uint64_t SpecialAddr(MCDwarfLineTableParams Params, uint64_t op) {
634 return (op - Params.DWARF2LineOpcodeBase) / Params.DWARF2LineRange;
635 }
636
637 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
Encode(MCContext & Context,MCDwarfLineTableParams Params,int64_t LineDelta,uint64_t AddrDelta,raw_ostream & OS)638 void MCDwarfLineAddr::Encode(MCContext &Context, MCDwarfLineTableParams Params,
639 int64_t LineDelta, uint64_t AddrDelta,
640 raw_ostream &OS) {
641 uint64_t Temp, Opcode;
642 bool NeedCopy = false;
643
644 // The maximum address skip amount that can be encoded with a special op.
645 uint64_t MaxSpecialAddrDelta = SpecialAddr(Params, 255);
646
647 // Scale the address delta by the minimum instruction length.
648 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
649
650 // A LineDelta of INT64_MAX is a signal that this is actually a
651 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
652 // end_sequence to emit the matrix entry.
653 if (LineDelta == INT64_MAX) {
654 if (AddrDelta == MaxSpecialAddrDelta)
655 OS << char(dwarf::DW_LNS_const_add_pc);
656 else if (AddrDelta) {
657 OS << char(dwarf::DW_LNS_advance_pc);
658 encodeULEB128(AddrDelta, OS);
659 }
660 OS << char(dwarf::DW_LNS_extended_op);
661 OS << char(1);
662 OS << char(dwarf::DW_LNE_end_sequence);
663 return;
664 }
665
666 // Bias the line delta by the base.
667 Temp = LineDelta - Params.DWARF2LineBase;
668
669 // If the line increment is out of range of a special opcode, we must encode
670 // it with DW_LNS_advance_line.
671 if (Temp >= Params.DWARF2LineRange ||
672 Temp + Params.DWARF2LineOpcodeBase > 255) {
673 OS << char(dwarf::DW_LNS_advance_line);
674 encodeSLEB128(LineDelta, OS);
675
676 LineDelta = 0;
677 Temp = 0 - Params.DWARF2LineBase;
678 NeedCopy = true;
679 }
680
681 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
682 if (LineDelta == 0 && AddrDelta == 0) {
683 OS << char(dwarf::DW_LNS_copy);
684 return;
685 }
686
687 // Bias the opcode by the special opcode base.
688 Temp += Params.DWARF2LineOpcodeBase;
689
690 // Avoid overflow when addr_delta is large.
691 if (AddrDelta < 256 + MaxSpecialAddrDelta) {
692 // Try using a special opcode.
693 Opcode = Temp + AddrDelta * Params.DWARF2LineRange;
694 if (Opcode <= 255) {
695 OS << char(Opcode);
696 return;
697 }
698
699 // Try using DW_LNS_const_add_pc followed by special op.
700 Opcode = Temp + (AddrDelta - MaxSpecialAddrDelta) * Params.DWARF2LineRange;
701 if (Opcode <= 255) {
702 OS << char(dwarf::DW_LNS_const_add_pc);
703 OS << char(Opcode);
704 return;
705 }
706 }
707
708 // Otherwise use DW_LNS_advance_pc.
709 OS << char(dwarf::DW_LNS_advance_pc);
710 encodeULEB128(AddrDelta, OS);
711
712 if (NeedCopy)
713 OS << char(dwarf::DW_LNS_copy);
714 else {
715 assert(Temp <= 255 && "Buggy special opcode encoding.");
716 OS << char(Temp);
717 }
718 }
719
720 // Utility function to write a tuple for .debug_abbrev.
EmitAbbrev(MCStreamer * MCOS,uint64_t Name,uint64_t Form)721 static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) {
722 MCOS->emitULEB128IntValue(Name);
723 MCOS->emitULEB128IntValue(Form);
724 }
725
726 // When generating dwarf for assembly source files this emits
727 // the data for .debug_abbrev section which contains three DIEs.
EmitGenDwarfAbbrev(MCStreamer * MCOS)728 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
729 MCContext &context = MCOS->getContext();
730 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
731
732 // DW_TAG_compile_unit DIE abbrev (1).
733 MCOS->emitULEB128IntValue(1);
734 MCOS->emitULEB128IntValue(dwarf::DW_TAG_compile_unit);
735 MCOS->emitInt8(dwarf::DW_CHILDREN_yes);
736 dwarf::Form SecOffsetForm =
737 context.getDwarfVersion() >= 4
738 ? dwarf::DW_FORM_sec_offset
739 : (context.getDwarfFormat() == dwarf::DWARF64 ? dwarf::DW_FORM_data8
740 : dwarf::DW_FORM_data4);
741 EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, SecOffsetForm);
742 if (context.getGenDwarfSectionSyms().size() > 1 &&
743 context.getDwarfVersion() >= 3) {
744 EmitAbbrev(MCOS, dwarf::DW_AT_ranges, SecOffsetForm);
745 } else {
746 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
747 EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
748 }
749 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
750 if (!context.getCompilationDir().empty())
751 EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
752 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
753 if (!DwarfDebugFlags.empty())
754 EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
755 EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string);
756 EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2);
757 EmitAbbrev(MCOS, 0, 0);
758
759 // DW_TAG_label DIE abbrev (2).
760 MCOS->emitULEB128IntValue(2);
761 MCOS->emitULEB128IntValue(dwarf::DW_TAG_label);
762 MCOS->emitInt8(dwarf::DW_CHILDREN_no);
763 EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
764 EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);
765 EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);
766 EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
767 EmitAbbrev(MCOS, 0, 0);
768
769 // Terminate the abbreviations for this compilation unit.
770 MCOS->emitInt8(0);
771 }
772
773 // When generating dwarf for assembly source files this emits the data for
774 // .debug_aranges section. This section contains a header and a table of pairs
775 // of PointerSize'ed values for the address and size of section(s) with line
776 // table entries.
EmitGenDwarfAranges(MCStreamer * MCOS,const MCSymbol * InfoSectionSymbol)777 static void EmitGenDwarfAranges(MCStreamer *MCOS,
778 const MCSymbol *InfoSectionSymbol) {
779 MCContext &context = MCOS->getContext();
780
781 auto &Sections = context.getGenDwarfSectionSyms();
782
783 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
784
785 unsigned UnitLengthBytes =
786 dwarf::getUnitLengthFieldByteSize(context.getDwarfFormat());
787 unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(context.getDwarfFormat());
788
789 // This will be the length of the .debug_aranges section, first account for
790 // the size of each item in the header (see below where we emit these items).
791 int Length = UnitLengthBytes + 2 + OffsetSize + 1 + 1;
792
793 // Figure the padding after the header before the table of address and size
794 // pairs who's values are PointerSize'ed.
795 const MCAsmInfo *asmInfo = context.getAsmInfo();
796 int AddrSize = asmInfo->getCodePointerSize();
797 int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1));
798 if (Pad == 2 * AddrSize)
799 Pad = 0;
800 Length += Pad;
801
802 // Add the size of the pair of PointerSize'ed values for the address and size
803 // of each section we have in the table.
804 Length += 2 * AddrSize * Sections.size();
805 // And the pair of terminating zeros.
806 Length += 2 * AddrSize;
807
808 // Emit the header for this section.
809 if (context.getDwarfFormat() == dwarf::DWARF64)
810 // The DWARF64 mark.
811 MCOS->emitInt32(dwarf::DW_LENGTH_DWARF64);
812 // The 4 (8 for DWARF64) byte length not including the length of the unit
813 // length field itself.
814 MCOS->emitIntValue(Length - UnitLengthBytes, OffsetSize);
815 // The 2 byte version, which is 2.
816 MCOS->emitInt16(2);
817 // The 4 (8 for DWARF64) byte offset to the compile unit in the .debug_info
818 // from the start of the .debug_info.
819 if (InfoSectionSymbol)
820 MCOS->emitSymbolValue(InfoSectionSymbol, OffsetSize,
821 asmInfo->needsDwarfSectionOffsetDirective());
822 else
823 MCOS->emitIntValue(0, OffsetSize);
824 // The 1 byte size of an address.
825 MCOS->emitInt8(AddrSize);
826 // The 1 byte size of a segment descriptor, we use a value of zero.
827 MCOS->emitInt8(0);
828 // Align the header with the padding if needed, before we put out the table.
829 for(int i = 0; i < Pad; i++)
830 MCOS->emitInt8(0);
831
832 // Now emit the table of pairs of PointerSize'ed values for the section
833 // addresses and sizes.
834 for (MCSection *Sec : Sections) {
835 const MCSymbol *StartSymbol = Sec->getBeginSymbol();
836 MCSymbol *EndSymbol = Sec->getEndSymbol(context);
837 assert(StartSymbol && "StartSymbol must not be NULL");
838 assert(EndSymbol && "EndSymbol must not be NULL");
839
840 const MCExpr *Addr = MCSymbolRefExpr::create(
841 StartSymbol, MCSymbolRefExpr::VK_None, context);
842 const MCExpr *Size =
843 makeEndMinusStartExpr(context, *StartSymbol, *EndSymbol, 0);
844 MCOS->emitValue(Addr, AddrSize);
845 emitAbsValue(*MCOS, Size, AddrSize);
846 }
847
848 // And finally the pair of terminating zeros.
849 MCOS->emitIntValue(0, AddrSize);
850 MCOS->emitIntValue(0, AddrSize);
851 }
852
853 // When generating dwarf for assembly source files this emits the data for
854 // .debug_info section which contains three parts. The header, the compile_unit
855 // DIE and a list of label DIEs.
EmitGenDwarfInfo(MCStreamer * MCOS,const MCSymbol * AbbrevSectionSymbol,const MCSymbol * LineSectionSymbol,const MCSymbol * RangesSymbol)856 static void EmitGenDwarfInfo(MCStreamer *MCOS,
857 const MCSymbol *AbbrevSectionSymbol,
858 const MCSymbol *LineSectionSymbol,
859 const MCSymbol *RangesSymbol) {
860 MCContext &context = MCOS->getContext();
861
862 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
863
864 // Create a symbol at the start and end of this section used in here for the
865 // expression to calculate the length in the header.
866 MCSymbol *InfoStart = context.createTempSymbol();
867 MCOS->emitLabel(InfoStart);
868 MCSymbol *InfoEnd = context.createTempSymbol();
869
870 // First part: the header.
871
872 unsigned UnitLengthBytes =
873 dwarf::getUnitLengthFieldByteSize(context.getDwarfFormat());
874 unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(context.getDwarfFormat());
875
876 if (context.getDwarfFormat() == dwarf::DWARF64)
877 // Emit DWARF64 mark.
878 MCOS->emitInt32(dwarf::DW_LENGTH_DWARF64);
879
880 // The 4 (8 for DWARF64) byte total length of the information for this
881 // compilation unit, not including the unit length field itself.
882 const MCExpr *Length =
883 makeEndMinusStartExpr(context, *InfoStart, *InfoEnd, UnitLengthBytes);
884 emitAbsValue(*MCOS, Length, OffsetSize);
885
886 // The 2 byte DWARF version.
887 MCOS->emitInt16(context.getDwarfVersion());
888
889 // The DWARF v5 header has unit type, address size, abbrev offset.
890 // Earlier versions have abbrev offset, address size.
891 const MCAsmInfo &AsmInfo = *context.getAsmInfo();
892 int AddrSize = AsmInfo.getCodePointerSize();
893 if (context.getDwarfVersion() >= 5) {
894 MCOS->emitInt8(dwarf::DW_UT_compile);
895 MCOS->emitInt8(AddrSize);
896 }
897 // The 4 (8 for DWARF64) byte offset to the debug abbrevs from the start of
898 // the .debug_abbrev.
899 if (AbbrevSectionSymbol)
900 MCOS->emitSymbolValue(AbbrevSectionSymbol, OffsetSize,
901 AsmInfo.needsDwarfSectionOffsetDirective());
902 else
903 // Since the abbrevs are at the start of the section, the offset is zero.
904 MCOS->emitIntValue(0, OffsetSize);
905 if (context.getDwarfVersion() <= 4)
906 MCOS->emitInt8(AddrSize);
907
908 // Second part: the compile_unit DIE.
909
910 // The DW_TAG_compile_unit DIE abbrev (1).
911 MCOS->emitULEB128IntValue(1);
912
913 // DW_AT_stmt_list, a 4 (8 for DWARF64) byte offset from the start of the
914 // .debug_line section.
915 if (LineSectionSymbol)
916 MCOS->emitSymbolValue(LineSectionSymbol, OffsetSize,
917 AsmInfo.needsDwarfSectionOffsetDirective());
918 else
919 // The line table is at the start of the section, so the offset is zero.
920 MCOS->emitIntValue(0, OffsetSize);
921
922 if (RangesSymbol) {
923 // There are multiple sections containing code, so we must use
924 // .debug_ranges/.debug_rnglists. AT_ranges, the 4/8 byte offset from the
925 // start of the .debug_ranges/.debug_rnglists.
926 MCOS->emitSymbolValue(RangesSymbol, OffsetSize);
927 } else {
928 // If we only have one non-empty code section, we can use the simpler
929 // AT_low_pc and AT_high_pc attributes.
930
931 // Find the first (and only) non-empty text section
932 auto &Sections = context.getGenDwarfSectionSyms();
933 const auto TextSection = Sections.begin();
934 assert(TextSection != Sections.end() && "No text section found");
935
936 MCSymbol *StartSymbol = (*TextSection)->getBeginSymbol();
937 MCSymbol *EndSymbol = (*TextSection)->getEndSymbol(context);
938 assert(StartSymbol && "StartSymbol must not be NULL");
939 assert(EndSymbol && "EndSymbol must not be NULL");
940
941 // AT_low_pc, the first address of the default .text section.
942 const MCExpr *Start = MCSymbolRefExpr::create(
943 StartSymbol, MCSymbolRefExpr::VK_None, context);
944 MCOS->emitValue(Start, AddrSize);
945
946 // AT_high_pc, the last address of the default .text section.
947 const MCExpr *End = MCSymbolRefExpr::create(
948 EndSymbol, MCSymbolRefExpr::VK_None, context);
949 MCOS->emitValue(End, AddrSize);
950 }
951
952 // AT_name, the name of the source file. Reconstruct from the first directory
953 // and file table entries.
954 const SmallVectorImpl<std::string> &MCDwarfDirs = context.getMCDwarfDirs();
955 if (MCDwarfDirs.size() > 0) {
956 MCOS->emitBytes(MCDwarfDirs[0]);
957 MCOS->emitBytes(sys::path::get_separator());
958 }
959 const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles = context.getMCDwarfFiles();
960 // MCDwarfFiles might be empty if we have an empty source file.
961 // If it's not empty, [0] is unused and [1] is the first actual file.
962 assert(MCDwarfFiles.empty() || MCDwarfFiles.size() >= 2);
963 const MCDwarfFile &RootFile =
964 MCDwarfFiles.empty()
965 ? context.getMCDwarfLineTable(/*CUID=*/0).getRootFile()
966 : MCDwarfFiles[1];
967 MCOS->emitBytes(RootFile.Name);
968 MCOS->emitInt8(0); // NULL byte to terminate the string.
969
970 // AT_comp_dir, the working directory the assembly was done in.
971 if (!context.getCompilationDir().empty()) {
972 MCOS->emitBytes(context.getCompilationDir());
973 MCOS->emitInt8(0); // NULL byte to terminate the string.
974 }
975
976 // AT_APPLE_flags, the command line arguments of the assembler tool.
977 StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
978 if (!DwarfDebugFlags.empty()){
979 MCOS->emitBytes(DwarfDebugFlags);
980 MCOS->emitInt8(0); // NULL byte to terminate the string.
981 }
982
983 // AT_producer, the version of the assembler tool.
984 StringRef DwarfDebugProducer = context.getDwarfDebugProducer();
985 if (!DwarfDebugProducer.empty())
986 MCOS->emitBytes(DwarfDebugProducer);
987 else
988 MCOS->emitBytes(StringRef("llvm-mc (based on LLVM " PACKAGE_VERSION ")"));
989 MCOS->emitInt8(0); // NULL byte to terminate the string.
990
991 // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2
992 // draft has no standard code for assembler.
993 MCOS->emitInt16(dwarf::DW_LANG_Mips_Assembler);
994
995 // Third part: the list of label DIEs.
996
997 // Loop on saved info for dwarf labels and create the DIEs for them.
998 const std::vector<MCGenDwarfLabelEntry> &Entries =
999 MCOS->getContext().getMCGenDwarfLabelEntries();
1000 for (const auto &Entry : Entries) {
1001 // The DW_TAG_label DIE abbrev (2).
1002 MCOS->emitULEB128IntValue(2);
1003
1004 // AT_name, of the label without any leading underbar.
1005 MCOS->emitBytes(Entry.getName());
1006 MCOS->emitInt8(0); // NULL byte to terminate the string.
1007
1008 // AT_decl_file, index into the file table.
1009 MCOS->emitInt32(Entry.getFileNumber());
1010
1011 // AT_decl_line, source line number.
1012 MCOS->emitInt32(Entry.getLineNumber());
1013
1014 // AT_low_pc, start address of the label.
1015 const MCExpr *AT_low_pc = MCSymbolRefExpr::create(Entry.getLabel(),
1016 MCSymbolRefExpr::VK_None, context);
1017 MCOS->emitValue(AT_low_pc, AddrSize);
1018 }
1019
1020 // Add the NULL DIE terminating the Compile Unit DIE's.
1021 MCOS->emitInt8(0);
1022
1023 // Now set the value of the symbol at the end of the info section.
1024 MCOS->emitLabel(InfoEnd);
1025 }
1026
1027 // When generating dwarf for assembly source files this emits the data for
1028 // .debug_ranges section. We only emit one range list, which spans all of the
1029 // executable sections of this file.
emitGenDwarfRanges(MCStreamer * MCOS)1030 static MCSymbol *emitGenDwarfRanges(MCStreamer *MCOS) {
1031 MCContext &context = MCOS->getContext();
1032 auto &Sections = context.getGenDwarfSectionSyms();
1033
1034 const MCAsmInfo *AsmInfo = context.getAsmInfo();
1035 int AddrSize = AsmInfo->getCodePointerSize();
1036 MCSymbol *RangesSymbol;
1037
1038 if (MCOS->getContext().getDwarfVersion() >= 5) {
1039 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRnglistsSection());
1040 MCSymbol *EndSymbol = mcdwarf::emitListsTableHeaderStart(*MCOS);
1041 MCOS->AddComment("Offset entry count");
1042 MCOS->emitInt32(0);
1043 RangesSymbol = context.createTempSymbol("debug_rnglist0_start");
1044 MCOS->emitLabel(RangesSymbol);
1045 for (MCSection *Sec : Sections) {
1046 const MCSymbol *StartSymbol = Sec->getBeginSymbol();
1047 const MCSymbol *EndSymbol = Sec->getEndSymbol(context);
1048 const MCExpr *SectionStartAddr = MCSymbolRefExpr::create(
1049 StartSymbol, MCSymbolRefExpr::VK_None, context);
1050 const MCExpr *SectionSize =
1051 makeEndMinusStartExpr(context, *StartSymbol, *EndSymbol, 0);
1052 MCOS->emitInt8(dwarf::DW_RLE_start_length);
1053 MCOS->emitValue(SectionStartAddr, AddrSize);
1054 MCOS->emitULEB128Value(SectionSize);
1055 }
1056 MCOS->emitInt8(dwarf::DW_RLE_end_of_list);
1057 MCOS->emitLabel(EndSymbol);
1058 } else {
1059 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection());
1060 RangesSymbol = context.createTempSymbol("debug_ranges_start");
1061 MCOS->emitLabel(RangesSymbol);
1062 for (MCSection *Sec : Sections) {
1063 const MCSymbol *StartSymbol = Sec->getBeginSymbol();
1064 const MCSymbol *EndSymbol = Sec->getEndSymbol(context);
1065
1066 // Emit a base address selection entry for the section start.
1067 const MCExpr *SectionStartAddr = MCSymbolRefExpr::create(
1068 StartSymbol, MCSymbolRefExpr::VK_None, context);
1069 MCOS->emitFill(AddrSize, 0xFF);
1070 MCOS->emitValue(SectionStartAddr, AddrSize);
1071
1072 // Emit a range list entry spanning this section.
1073 const MCExpr *SectionSize =
1074 makeEndMinusStartExpr(context, *StartSymbol, *EndSymbol, 0);
1075 MCOS->emitIntValue(0, AddrSize);
1076 emitAbsValue(*MCOS, SectionSize, AddrSize);
1077 }
1078
1079 // Emit end of list entry
1080 MCOS->emitIntValue(0, AddrSize);
1081 MCOS->emitIntValue(0, AddrSize);
1082 }
1083
1084 return RangesSymbol;
1085 }
1086
1087 //
1088 // When generating dwarf for assembly source files this emits the Dwarf
1089 // sections.
1090 //
Emit(MCStreamer * MCOS)1091 void MCGenDwarfInfo::Emit(MCStreamer *MCOS) {
1092 MCContext &context = MCOS->getContext();
1093
1094 // Create the dwarf sections in this order (.debug_line already created).
1095 const MCAsmInfo *AsmInfo = context.getAsmInfo();
1096 bool CreateDwarfSectionSymbols =
1097 AsmInfo->doesDwarfUseRelocationsAcrossSections();
1098 MCSymbol *LineSectionSymbol = nullptr;
1099 if (CreateDwarfSectionSymbols)
1100 LineSectionSymbol = MCOS->getDwarfLineTableSymbol(0);
1101 MCSymbol *AbbrevSectionSymbol = nullptr;
1102 MCSymbol *InfoSectionSymbol = nullptr;
1103 MCSymbol *RangesSymbol = nullptr;
1104
1105 // Create end symbols for each section, and remove empty sections
1106 MCOS->getContext().finalizeDwarfSections(*MCOS);
1107
1108 // If there are no sections to generate debug info for, we don't need
1109 // to do anything
1110 if (MCOS->getContext().getGenDwarfSectionSyms().empty())
1111 return;
1112
1113 // We only use the .debug_ranges section if we have multiple code sections,
1114 // and we are emitting a DWARF version which supports it.
1115 const bool UseRangesSection =
1116 MCOS->getContext().getGenDwarfSectionSyms().size() > 1 &&
1117 MCOS->getContext().getDwarfVersion() >= 3;
1118 CreateDwarfSectionSymbols |= UseRangesSection;
1119
1120 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
1121 if (CreateDwarfSectionSymbols) {
1122 InfoSectionSymbol = context.createTempSymbol();
1123 MCOS->emitLabel(InfoSectionSymbol);
1124 }
1125 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
1126 if (CreateDwarfSectionSymbols) {
1127 AbbrevSectionSymbol = context.createTempSymbol();
1128 MCOS->emitLabel(AbbrevSectionSymbol);
1129 }
1130
1131 MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
1132
1133 // Output the data for .debug_aranges section.
1134 EmitGenDwarfAranges(MCOS, InfoSectionSymbol);
1135
1136 if (UseRangesSection) {
1137 RangesSymbol = emitGenDwarfRanges(MCOS);
1138 assert(RangesSymbol);
1139 }
1140
1141 // Output the data for .debug_abbrev section.
1142 EmitGenDwarfAbbrev(MCOS);
1143
1144 // Output the data for .debug_info section.
1145 EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol, RangesSymbol);
1146 }
1147
1148 //
1149 // When generating dwarf for assembly source files this is called when symbol
1150 // for a label is created. If this symbol is not a temporary and is in the
1151 // section that dwarf is being generated for, save the needed info to create
1152 // a dwarf label.
1153 //
Make(MCSymbol * Symbol,MCStreamer * MCOS,SourceMgr & SrcMgr,SMLoc & Loc)1154 void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
1155 SourceMgr &SrcMgr, SMLoc &Loc) {
1156 // We won't create dwarf labels for temporary symbols.
1157 if (Symbol->isTemporary())
1158 return;
1159 MCContext &context = MCOS->getContext();
1160 // We won't create dwarf labels for symbols in sections that we are not
1161 // generating debug info for.
1162 if (!context.getGenDwarfSectionSyms().count(MCOS->getCurrentSectionOnly()))
1163 return;
1164
1165 // The dwarf label's name does not have the symbol name's leading
1166 // underbar if any.
1167 StringRef Name = Symbol->getName();
1168 if (Name.startswith("_"))
1169 Name = Name.substr(1, Name.size()-1);
1170
1171 // Get the dwarf file number to be used for the dwarf label.
1172 unsigned FileNumber = context.getGenDwarfFileNumber();
1173
1174 // Finding the line number is the expensive part which is why we just don't
1175 // pass it in as for some symbols we won't create a dwarf label.
1176 unsigned CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
1177 unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
1178
1179 // We create a temporary symbol for use for the AT_high_pc and AT_low_pc
1180 // values so that they don't have things like an ARM thumb bit from the
1181 // original symbol. So when used they won't get a low bit set after
1182 // relocation.
1183 MCSymbol *Label = context.createTempSymbol();
1184 MCOS->emitLabel(Label);
1185
1186 // Create and entry for the info and add it to the other entries.
1187 MCOS->getContext().addMCGenDwarfLabelEntry(
1188 MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label));
1189 }
1190
getDataAlignmentFactor(MCStreamer & streamer)1191 static int getDataAlignmentFactor(MCStreamer &streamer) {
1192 MCContext &context = streamer.getContext();
1193 const MCAsmInfo *asmInfo = context.getAsmInfo();
1194 int size = asmInfo->getCalleeSaveStackSlotSize();
1195 if (asmInfo->isStackGrowthDirectionUp())
1196 return size;
1197 else
1198 return -size;
1199 }
1200
getSizeForEncoding(MCStreamer & streamer,unsigned symbolEncoding)1201 static unsigned getSizeForEncoding(MCStreamer &streamer,
1202 unsigned symbolEncoding) {
1203 MCContext &context = streamer.getContext();
1204 unsigned format = symbolEncoding & 0x0f;
1205 switch (format) {
1206 default: llvm_unreachable("Unknown Encoding");
1207 case dwarf::DW_EH_PE_absptr:
1208 case dwarf::DW_EH_PE_signed:
1209 return context.getAsmInfo()->getCodePointerSize();
1210 case dwarf::DW_EH_PE_udata2:
1211 case dwarf::DW_EH_PE_sdata2:
1212 return 2;
1213 case dwarf::DW_EH_PE_udata4:
1214 case dwarf::DW_EH_PE_sdata4:
1215 return 4;
1216 case dwarf::DW_EH_PE_udata8:
1217 case dwarf::DW_EH_PE_sdata8:
1218 return 8;
1219 }
1220 }
1221
emitFDESymbol(MCObjectStreamer & streamer,const MCSymbol & symbol,unsigned symbolEncoding,bool isEH)1222 static void emitFDESymbol(MCObjectStreamer &streamer, const MCSymbol &symbol,
1223 unsigned symbolEncoding, bool isEH) {
1224 MCContext &context = streamer.getContext();
1225 const MCAsmInfo *asmInfo = context.getAsmInfo();
1226 const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol,
1227 symbolEncoding,
1228 streamer);
1229 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
1230 if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH)
1231 emitAbsValue(streamer, v, size);
1232 else
1233 streamer.emitValue(v, size);
1234 }
1235
EmitPersonality(MCStreamer & streamer,const MCSymbol & symbol,unsigned symbolEncoding)1236 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
1237 unsigned symbolEncoding) {
1238 MCContext &context = streamer.getContext();
1239 const MCAsmInfo *asmInfo = context.getAsmInfo();
1240 const MCExpr *v = asmInfo->getExprForPersonalitySymbol(&symbol,
1241 symbolEncoding,
1242 streamer);
1243 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
1244 streamer.emitValue(v, size);
1245 }
1246
1247 namespace {
1248
1249 class FrameEmitterImpl {
1250 int CFAOffset = 0;
1251 int InitialCFAOffset = 0;
1252 bool IsEH;
1253 MCObjectStreamer &Streamer;
1254
1255 public:
FrameEmitterImpl(bool IsEH,MCObjectStreamer & Streamer)1256 FrameEmitterImpl(bool IsEH, MCObjectStreamer &Streamer)
1257 : IsEH(IsEH), Streamer(Streamer) {}
1258
1259 /// Emit the unwind information in a compact way.
1260 void EmitCompactUnwind(const MCDwarfFrameInfo &frame);
1261
1262 const MCSymbol &EmitCIE(const MCDwarfFrameInfo &F);
1263 void EmitFDE(const MCSymbol &cieStart, const MCDwarfFrameInfo &frame,
1264 bool LastInSection, const MCSymbol &SectionStart);
1265 void emitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs,
1266 MCSymbol *BaseLabel);
1267 void emitCFIInstruction(const MCCFIInstruction &Instr);
1268 };
1269
1270 } // end anonymous namespace
1271
emitEncodingByte(MCObjectStreamer & Streamer,unsigned Encoding)1272 static void emitEncodingByte(MCObjectStreamer &Streamer, unsigned Encoding) {
1273 Streamer.emitInt8(Encoding);
1274 }
1275
emitCFIInstruction(const MCCFIInstruction & Instr)1276 void FrameEmitterImpl::emitCFIInstruction(const MCCFIInstruction &Instr) {
1277 int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
1278 auto *MRI = Streamer.getContext().getRegisterInfo();
1279
1280 switch (Instr.getOperation()) {
1281 case MCCFIInstruction::OpRegister: {
1282 unsigned Reg1 = Instr.getRegister();
1283 unsigned Reg2 = Instr.getRegister2();
1284 if (!IsEH) {
1285 Reg1 = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg1);
1286 Reg2 = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg2);
1287 }
1288 Streamer.emitInt8(dwarf::DW_CFA_register);
1289 Streamer.emitULEB128IntValue(Reg1);
1290 Streamer.emitULEB128IntValue(Reg2);
1291 return;
1292 }
1293 case MCCFIInstruction::OpWindowSave:
1294 Streamer.emitInt8(dwarf::DW_CFA_GNU_window_save);
1295 return;
1296
1297 case MCCFIInstruction::OpNegateRAState:
1298 Streamer.emitInt8(dwarf::DW_CFA_AARCH64_negate_ra_state);
1299 return;
1300
1301 case MCCFIInstruction::OpUndefined: {
1302 unsigned Reg = Instr.getRegister();
1303 Streamer.emitInt8(dwarf::DW_CFA_undefined);
1304 Streamer.emitULEB128IntValue(Reg);
1305 return;
1306 }
1307 case MCCFIInstruction::OpAdjustCfaOffset:
1308 case MCCFIInstruction::OpDefCfaOffset: {
1309 const bool IsRelative =
1310 Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset;
1311
1312 Streamer.emitInt8(dwarf::DW_CFA_def_cfa_offset);
1313
1314 if (IsRelative)
1315 CFAOffset += Instr.getOffset();
1316 else
1317 CFAOffset = Instr.getOffset();
1318
1319 Streamer.emitULEB128IntValue(CFAOffset);
1320
1321 return;
1322 }
1323 case MCCFIInstruction::OpDefCfa: {
1324 unsigned Reg = Instr.getRegister();
1325 if (!IsEH)
1326 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
1327 Streamer.emitInt8(dwarf::DW_CFA_def_cfa);
1328 Streamer.emitULEB128IntValue(Reg);
1329 CFAOffset = Instr.getOffset();
1330 Streamer.emitULEB128IntValue(CFAOffset);
1331
1332 return;
1333 }
1334 case MCCFIInstruction::OpDefCfaRegister: {
1335 unsigned Reg = Instr.getRegister();
1336 if (!IsEH)
1337 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
1338 Streamer.emitInt8(dwarf::DW_CFA_def_cfa_register);
1339 Streamer.emitULEB128IntValue(Reg);
1340
1341 return;
1342 }
1343 // TODO: Implement `_sf` variants if/when they need to be emitted.
1344 case MCCFIInstruction::OpLLVMDefAspaceCfa: {
1345 unsigned Reg = Instr.getRegister();
1346 if (!IsEH)
1347 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
1348 Streamer.emitIntValue(dwarf::DW_CFA_LLVM_def_aspace_cfa, 1);
1349 Streamer.emitULEB128IntValue(Reg);
1350 CFAOffset = Instr.getOffset();
1351 Streamer.emitULEB128IntValue(CFAOffset);
1352 Streamer.emitULEB128IntValue(Instr.getAddressSpace());
1353
1354 return;
1355 }
1356 case MCCFIInstruction::OpOffset:
1357 case MCCFIInstruction::OpRelOffset: {
1358 const bool IsRelative =
1359 Instr.getOperation() == MCCFIInstruction::OpRelOffset;
1360
1361 unsigned Reg = Instr.getRegister();
1362 if (!IsEH)
1363 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
1364
1365 int Offset = Instr.getOffset();
1366 if (IsRelative)
1367 Offset -= CFAOffset;
1368 Offset = Offset / dataAlignmentFactor;
1369
1370 if (Offset < 0) {
1371 Streamer.emitInt8(dwarf::DW_CFA_offset_extended_sf);
1372 Streamer.emitULEB128IntValue(Reg);
1373 Streamer.emitSLEB128IntValue(Offset);
1374 } else if (Reg < 64) {
1375 Streamer.emitInt8(dwarf::DW_CFA_offset + Reg);
1376 Streamer.emitULEB128IntValue(Offset);
1377 } else {
1378 Streamer.emitInt8(dwarf::DW_CFA_offset_extended);
1379 Streamer.emitULEB128IntValue(Reg);
1380 Streamer.emitULEB128IntValue(Offset);
1381 }
1382 return;
1383 }
1384 case MCCFIInstruction::OpRememberState:
1385 Streamer.emitInt8(dwarf::DW_CFA_remember_state);
1386 return;
1387 case MCCFIInstruction::OpRestoreState:
1388 Streamer.emitInt8(dwarf::DW_CFA_restore_state);
1389 return;
1390 case MCCFIInstruction::OpSameValue: {
1391 unsigned Reg = Instr.getRegister();
1392 Streamer.emitInt8(dwarf::DW_CFA_same_value);
1393 Streamer.emitULEB128IntValue(Reg);
1394 return;
1395 }
1396 case MCCFIInstruction::OpRestore: {
1397 unsigned Reg = Instr.getRegister();
1398 if (!IsEH)
1399 Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
1400 if (Reg < 64) {
1401 Streamer.emitInt8(dwarf::DW_CFA_restore | Reg);
1402 } else {
1403 Streamer.emitInt8(dwarf::DW_CFA_restore_extended);
1404 Streamer.emitULEB128IntValue(Reg);
1405 }
1406 return;
1407 }
1408 case MCCFIInstruction::OpGnuArgsSize:
1409 Streamer.emitInt8(dwarf::DW_CFA_GNU_args_size);
1410 Streamer.emitULEB128IntValue(Instr.getOffset());
1411 return;
1412
1413 case MCCFIInstruction::OpEscape:
1414 Streamer.emitBytes(Instr.getValues());
1415 return;
1416 }
1417 llvm_unreachable("Unhandled case in switch");
1418 }
1419
1420 /// Emit frame instructions to describe the layout of the frame.
emitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs,MCSymbol * BaseLabel)1421 void FrameEmitterImpl::emitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs,
1422 MCSymbol *BaseLabel) {
1423 for (const MCCFIInstruction &Instr : Instrs) {
1424 MCSymbol *Label = Instr.getLabel();
1425 // Throw out move if the label is invalid.
1426 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
1427
1428 // Advance row if new location.
1429 if (BaseLabel && Label) {
1430 MCSymbol *ThisSym = Label;
1431 if (ThisSym != BaseLabel) {
1432 Streamer.emitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
1433 BaseLabel = ThisSym;
1434 }
1435 }
1436
1437 emitCFIInstruction(Instr);
1438 }
1439 }
1440
1441 /// Emit the unwind information in a compact way.
EmitCompactUnwind(const MCDwarfFrameInfo & Frame)1442 void FrameEmitterImpl::EmitCompactUnwind(const MCDwarfFrameInfo &Frame) {
1443 MCContext &Context = Streamer.getContext();
1444 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1445
1446 // range-start range-length compact-unwind-enc personality-func lsda
1447 // _foo LfooEnd-_foo 0x00000023 0 0
1448 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1
1449 //
1450 // .section __LD,__compact_unwind,regular,debug
1451 //
1452 // # compact unwind for _foo
1453 // .quad _foo
1454 // .set L1,LfooEnd-_foo
1455 // .long L1
1456 // .long 0x01010001
1457 // .quad 0
1458 // .quad 0
1459 //
1460 // # compact unwind for _bar
1461 // .quad _bar
1462 // .set L2,LbarEnd-_bar
1463 // .long L2
1464 // .long 0x01020011
1465 // .quad __gxx_personality
1466 // .quad except_tab1
1467
1468 uint32_t Encoding = Frame.CompactUnwindEncoding;
1469 if (!Encoding) return;
1470 bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly());
1471
1472 // The encoding needs to know we have an LSDA.
1473 if (!DwarfEHFrameOnly && Frame.Lsda)
1474 Encoding |= 0x40000000;
1475
1476 // Range Start
1477 unsigned FDEEncoding = MOFI->getFDEEncoding();
1478 unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
1479 Streamer.emitSymbolValue(Frame.Begin, Size);
1480
1481 // Range Length
1482 const MCExpr *Range =
1483 makeEndMinusStartExpr(Context, *Frame.Begin, *Frame.End, 0);
1484 emitAbsValue(Streamer, Range, 4);
1485
1486 // Compact Encoding
1487 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
1488 Streamer.emitIntValue(Encoding, Size);
1489
1490 // Personality Function
1491 Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
1492 if (!DwarfEHFrameOnly && Frame.Personality)
1493 Streamer.emitSymbolValue(Frame.Personality, Size);
1494 else
1495 Streamer.emitIntValue(0, Size); // No personality fn
1496
1497 // LSDA
1498 Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
1499 if (!DwarfEHFrameOnly && Frame.Lsda)
1500 Streamer.emitSymbolValue(Frame.Lsda, Size);
1501 else
1502 Streamer.emitIntValue(0, Size); // No LSDA
1503 }
1504
getCIEVersion(bool IsEH,unsigned DwarfVersion)1505 static unsigned getCIEVersion(bool IsEH, unsigned DwarfVersion) {
1506 if (IsEH)
1507 return 1;
1508 switch (DwarfVersion) {
1509 case 2:
1510 return 1;
1511 case 3:
1512 return 3;
1513 case 4:
1514 case 5:
1515 return 4;
1516 }
1517 llvm_unreachable("Unknown version");
1518 }
1519
EmitCIE(const MCDwarfFrameInfo & Frame)1520 const MCSymbol &FrameEmitterImpl::EmitCIE(const MCDwarfFrameInfo &Frame) {
1521 MCContext &context = Streamer.getContext();
1522 const MCRegisterInfo *MRI = context.getRegisterInfo();
1523 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1524
1525 MCSymbol *sectionStart = context.createTempSymbol();
1526 Streamer.emitLabel(sectionStart);
1527
1528 MCSymbol *sectionEnd = context.createTempSymbol();
1529
1530 dwarf::DwarfFormat Format = IsEH ? dwarf::DWARF32 : context.getDwarfFormat();
1531 unsigned UnitLengthBytes = dwarf::getUnitLengthFieldByteSize(Format);
1532 unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(Format);
1533 bool IsDwarf64 = Format == dwarf::DWARF64;
1534
1535 if (IsDwarf64)
1536 // DWARF64 mark
1537 Streamer.emitInt32(dwarf::DW_LENGTH_DWARF64);
1538
1539 // Length
1540 const MCExpr *Length = makeEndMinusStartExpr(context, *sectionStart,
1541 *sectionEnd, UnitLengthBytes);
1542 emitAbsValue(Streamer, Length, OffsetSize);
1543
1544 // CIE ID
1545 uint64_t CIE_ID =
1546 IsEH ? 0 : (IsDwarf64 ? dwarf::DW64_CIE_ID : dwarf::DW_CIE_ID);
1547 Streamer.emitIntValue(CIE_ID, OffsetSize);
1548
1549 // Version
1550 uint8_t CIEVersion = getCIEVersion(IsEH, context.getDwarfVersion());
1551 Streamer.emitInt8(CIEVersion);
1552
1553 if (IsEH) {
1554 SmallString<8> Augmentation;
1555 Augmentation += "z";
1556 if (Frame.Personality)
1557 Augmentation += "P";
1558 if (Frame.Lsda)
1559 Augmentation += "L";
1560 Augmentation += "R";
1561 if (Frame.IsSignalFrame)
1562 Augmentation += "S";
1563 if (Frame.IsBKeyFrame)
1564 Augmentation += "B";
1565 Streamer.emitBytes(Augmentation);
1566 }
1567 Streamer.emitInt8(0);
1568
1569 if (CIEVersion >= 4) {
1570 // Address Size
1571 Streamer.emitInt8(context.getAsmInfo()->getCodePointerSize());
1572
1573 // Segment Descriptor Size
1574 Streamer.emitInt8(0);
1575 }
1576
1577 // Code Alignment Factor
1578 Streamer.emitULEB128IntValue(context.getAsmInfo()->getMinInstAlignment());
1579
1580 // Data Alignment Factor
1581 Streamer.emitSLEB128IntValue(getDataAlignmentFactor(Streamer));
1582
1583 // Return Address Register
1584 unsigned RAReg = Frame.RAReg;
1585 if (RAReg == static_cast<unsigned>(INT_MAX))
1586 RAReg = MRI->getDwarfRegNum(MRI->getRARegister(), IsEH);
1587
1588 if (CIEVersion == 1) {
1589 assert(RAReg <= 255 &&
1590 "DWARF 2 encodes return_address_register in one byte");
1591 Streamer.emitInt8(RAReg);
1592 } else {
1593 Streamer.emitULEB128IntValue(RAReg);
1594 }
1595
1596 // Augmentation Data Length (optional)
1597 unsigned augmentationLength = 0;
1598 if (IsEH) {
1599 if (Frame.Personality) {
1600 // Personality Encoding
1601 augmentationLength += 1;
1602 // Personality
1603 augmentationLength +=
1604 getSizeForEncoding(Streamer, Frame.PersonalityEncoding);
1605 }
1606 if (Frame.Lsda)
1607 augmentationLength += 1;
1608 // Encoding of the FDE pointers
1609 augmentationLength += 1;
1610
1611 Streamer.emitULEB128IntValue(augmentationLength);
1612
1613 // Augmentation Data (optional)
1614 if (Frame.Personality) {
1615 // Personality Encoding
1616 emitEncodingByte(Streamer, Frame.PersonalityEncoding);
1617 // Personality
1618 EmitPersonality(Streamer, *Frame.Personality, Frame.PersonalityEncoding);
1619 }
1620
1621 if (Frame.Lsda)
1622 emitEncodingByte(Streamer, Frame.LsdaEncoding);
1623
1624 // Encoding of the FDE pointers
1625 emitEncodingByte(Streamer, MOFI->getFDEEncoding());
1626 }
1627
1628 // Initial Instructions
1629
1630 const MCAsmInfo *MAI = context.getAsmInfo();
1631 if (!Frame.IsSimple) {
1632 const std::vector<MCCFIInstruction> &Instructions =
1633 MAI->getInitialFrameState();
1634 emitCFIInstructions(Instructions, nullptr);
1635 }
1636
1637 InitialCFAOffset = CFAOffset;
1638
1639 // Padding
1640 Streamer.emitValueToAlignment(IsEH ? 4 : MAI->getCodePointerSize());
1641
1642 Streamer.emitLabel(sectionEnd);
1643 return *sectionStart;
1644 }
1645
EmitFDE(const MCSymbol & cieStart,const MCDwarfFrameInfo & frame,bool LastInSection,const MCSymbol & SectionStart)1646 void FrameEmitterImpl::EmitFDE(const MCSymbol &cieStart,
1647 const MCDwarfFrameInfo &frame,
1648 bool LastInSection,
1649 const MCSymbol &SectionStart) {
1650 MCContext &context = Streamer.getContext();
1651 MCSymbol *fdeStart = context.createTempSymbol();
1652 MCSymbol *fdeEnd = context.createTempSymbol();
1653 const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
1654
1655 CFAOffset = InitialCFAOffset;
1656
1657 dwarf::DwarfFormat Format = IsEH ? dwarf::DWARF32 : context.getDwarfFormat();
1658 unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(Format);
1659
1660 if (Format == dwarf::DWARF64)
1661 // DWARF64 mark
1662 Streamer.emitInt32(dwarf::DW_LENGTH_DWARF64);
1663
1664 // Length
1665 const MCExpr *Length = makeEndMinusStartExpr(context, *fdeStart, *fdeEnd, 0);
1666 emitAbsValue(Streamer, Length, OffsetSize);
1667
1668 Streamer.emitLabel(fdeStart);
1669
1670 // CIE Pointer
1671 const MCAsmInfo *asmInfo = context.getAsmInfo();
1672 if (IsEH) {
1673 const MCExpr *offset =
1674 makeEndMinusStartExpr(context, cieStart, *fdeStart, 0);
1675 emitAbsValue(Streamer, offset, OffsetSize);
1676 } else if (!asmInfo->doesDwarfUseRelocationsAcrossSections()) {
1677 const MCExpr *offset =
1678 makeEndMinusStartExpr(context, SectionStart, cieStart, 0);
1679 emitAbsValue(Streamer, offset, OffsetSize);
1680 } else {
1681 Streamer.emitSymbolValue(&cieStart, OffsetSize,
1682 asmInfo->needsDwarfSectionOffsetDirective());
1683 }
1684
1685 // PC Begin
1686 unsigned PCEncoding =
1687 IsEH ? MOFI->getFDEEncoding() : (unsigned)dwarf::DW_EH_PE_absptr;
1688 unsigned PCSize = getSizeForEncoding(Streamer, PCEncoding);
1689 emitFDESymbol(Streamer, *frame.Begin, PCEncoding, IsEH);
1690
1691 // PC Range
1692 const MCExpr *Range =
1693 makeEndMinusStartExpr(context, *frame.Begin, *frame.End, 0);
1694 emitAbsValue(Streamer, Range, PCSize);
1695
1696 if (IsEH) {
1697 // Augmentation Data Length
1698 unsigned augmentationLength = 0;
1699
1700 if (frame.Lsda)
1701 augmentationLength += getSizeForEncoding(Streamer, frame.LsdaEncoding);
1702
1703 Streamer.emitULEB128IntValue(augmentationLength);
1704
1705 // Augmentation Data
1706 if (frame.Lsda)
1707 emitFDESymbol(Streamer, *frame.Lsda, frame.LsdaEncoding, true);
1708 }
1709
1710 // Call Frame Instructions
1711 emitCFIInstructions(frame.Instructions, frame.Begin);
1712
1713 // Padding
1714 // The size of a .eh_frame section has to be a multiple of the alignment
1715 // since a null CIE is interpreted as the end. Old systems overaligned
1716 // .eh_frame, so we do too and account for it in the last FDE.
1717 unsigned Align = LastInSection ? asmInfo->getCodePointerSize() : PCSize;
1718 Streamer.emitValueToAlignment(Align);
1719
1720 Streamer.emitLabel(fdeEnd);
1721 }
1722
1723 namespace {
1724
1725 struct CIEKey {
getEmptyKey__anon177793ac0211::CIEKey1726 static const CIEKey getEmptyKey() {
1727 return CIEKey(nullptr, 0, -1, false, false, static_cast<unsigned>(INT_MAX),
1728 false);
1729 }
1730
getTombstoneKey__anon177793ac0211::CIEKey1731 static const CIEKey getTombstoneKey() {
1732 return CIEKey(nullptr, -1, 0, false, false, static_cast<unsigned>(INT_MAX),
1733 false);
1734 }
1735
CIEKey__anon177793ac0211::CIEKey1736 CIEKey(const MCSymbol *Personality, unsigned PersonalityEncoding,
1737 unsigned LSDAEncoding, bool IsSignalFrame, bool IsSimple,
1738 unsigned RAReg, bool IsBKeyFrame)
1739 : Personality(Personality), PersonalityEncoding(PersonalityEncoding),
1740 LsdaEncoding(LSDAEncoding), IsSignalFrame(IsSignalFrame),
1741 IsSimple(IsSimple), RAReg(RAReg), IsBKeyFrame(IsBKeyFrame) {}
1742
CIEKey__anon177793ac0211::CIEKey1743 explicit CIEKey(const MCDwarfFrameInfo &Frame)
1744 : Personality(Frame.Personality),
1745 PersonalityEncoding(Frame.PersonalityEncoding),
1746 LsdaEncoding(Frame.LsdaEncoding), IsSignalFrame(Frame.IsSignalFrame),
1747 IsSimple(Frame.IsSimple), RAReg(Frame.RAReg),
1748 IsBKeyFrame(Frame.IsBKeyFrame) {}
1749
PersonalityName__anon177793ac0211::CIEKey1750 StringRef PersonalityName() const {
1751 if (!Personality)
1752 return StringRef();
1753 return Personality->getName();
1754 }
1755
operator <__anon177793ac0211::CIEKey1756 bool operator<(const CIEKey &Other) const {
1757 return std::make_tuple(PersonalityName(), PersonalityEncoding, LsdaEncoding,
1758 IsSignalFrame, IsSimple, RAReg) <
1759 std::make_tuple(Other.PersonalityName(), Other.PersonalityEncoding,
1760 Other.LsdaEncoding, Other.IsSignalFrame,
1761 Other.IsSimple, Other.RAReg);
1762 }
1763
1764 const MCSymbol *Personality;
1765 unsigned PersonalityEncoding;
1766 unsigned LsdaEncoding;
1767 bool IsSignalFrame;
1768 bool IsSimple;
1769 unsigned RAReg;
1770 bool IsBKeyFrame;
1771 };
1772
1773 } // end anonymous namespace
1774
1775 namespace llvm {
1776
1777 template <> struct DenseMapInfo<CIEKey> {
getEmptyKeyllvm::DenseMapInfo1778 static CIEKey getEmptyKey() { return CIEKey::getEmptyKey(); }
getTombstoneKeyllvm::DenseMapInfo1779 static CIEKey getTombstoneKey() { return CIEKey::getTombstoneKey(); }
1780
getHashValuellvm::DenseMapInfo1781 static unsigned getHashValue(const CIEKey &Key) {
1782 return static_cast<unsigned>(hash_combine(
1783 Key.Personality, Key.PersonalityEncoding, Key.LsdaEncoding,
1784 Key.IsSignalFrame, Key.IsSimple, Key.RAReg, Key.IsBKeyFrame));
1785 }
1786
isEqualllvm::DenseMapInfo1787 static bool isEqual(const CIEKey &LHS, const CIEKey &RHS) {
1788 return LHS.Personality == RHS.Personality &&
1789 LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
1790 LHS.LsdaEncoding == RHS.LsdaEncoding &&
1791 LHS.IsSignalFrame == RHS.IsSignalFrame &&
1792 LHS.IsSimple == RHS.IsSimple && LHS.RAReg == RHS.RAReg &&
1793 LHS.IsBKeyFrame == RHS.IsBKeyFrame;
1794 }
1795 };
1796
1797 } // end namespace llvm
1798
Emit(MCObjectStreamer & Streamer,MCAsmBackend * MAB,bool IsEH)1799 void MCDwarfFrameEmitter::Emit(MCObjectStreamer &Streamer, MCAsmBackend *MAB,
1800 bool IsEH) {
1801 Streamer.generateCompactUnwindEncodings(MAB);
1802
1803 MCContext &Context = Streamer.getContext();
1804 const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
1805 const MCAsmInfo *AsmInfo = Context.getAsmInfo();
1806 FrameEmitterImpl Emitter(IsEH, Streamer);
1807 ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getDwarfFrameInfos();
1808
1809 // Emit the compact unwind info if available.
1810 bool NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame();
1811 if (IsEH && MOFI->getCompactUnwindSection()) {
1812 bool SectionEmitted = false;
1813 for (const MCDwarfFrameInfo &Frame : FrameArray) {
1814 if (Frame.CompactUnwindEncoding == 0) continue;
1815 if (!SectionEmitted) {
1816 Streamer.SwitchSection(MOFI->getCompactUnwindSection());
1817 Streamer.emitValueToAlignment(AsmInfo->getCodePointerSize());
1818 SectionEmitted = true;
1819 }
1820 NeedsEHFrameSection |=
1821 Frame.CompactUnwindEncoding ==
1822 MOFI->getCompactUnwindDwarfEHFrameOnly();
1823 Emitter.EmitCompactUnwind(Frame);
1824 }
1825 }
1826
1827 if (!NeedsEHFrameSection) return;
1828
1829 MCSection &Section =
1830 IsEH ? *const_cast<MCObjectFileInfo *>(MOFI)->getEHFrameSection()
1831 : *MOFI->getDwarfFrameSection();
1832
1833 Streamer.SwitchSection(&Section);
1834 MCSymbol *SectionStart = Context.createTempSymbol();
1835 Streamer.emitLabel(SectionStart);
1836
1837 DenseMap<CIEKey, const MCSymbol *> CIEStarts;
1838
1839 const MCSymbol *DummyDebugKey = nullptr;
1840 bool CanOmitDwarf = MOFI->getOmitDwarfIfHaveCompactUnwind();
1841 // Sort the FDEs by their corresponding CIE before we emit them.
1842 // This isn't technically necessary according to the DWARF standard,
1843 // but the Android libunwindstack rejects eh_frame sections where
1844 // an FDE refers to a CIE other than the closest previous CIE.
1845 std::vector<MCDwarfFrameInfo> FrameArrayX(FrameArray.begin(), FrameArray.end());
1846 llvm::stable_sort(FrameArrayX,
1847 [](const MCDwarfFrameInfo &X, const MCDwarfFrameInfo &Y) {
1848 return CIEKey(X) < CIEKey(Y);
1849 });
1850 for (auto I = FrameArrayX.begin(), E = FrameArrayX.end(); I != E;) {
1851 const MCDwarfFrameInfo &Frame = *I;
1852 ++I;
1853 if (CanOmitDwarf && Frame.CompactUnwindEncoding !=
1854 MOFI->getCompactUnwindDwarfEHFrameOnly())
1855 // Don't generate an EH frame if we don't need one. I.e., it's taken care
1856 // of by the compact unwind encoding.
1857 continue;
1858
1859 CIEKey Key(Frame);
1860 const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
1861 if (!CIEStart)
1862 CIEStart = &Emitter.EmitCIE(Frame);
1863
1864 Emitter.EmitFDE(*CIEStart, Frame, I == E, *SectionStart);
1865 }
1866 }
1867
EmitAdvanceLoc(MCObjectStreamer & Streamer,uint64_t AddrDelta)1868 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCObjectStreamer &Streamer,
1869 uint64_t AddrDelta) {
1870 MCContext &Context = Streamer.getContext();
1871 SmallString<256> Tmp;
1872 raw_svector_ostream OS(Tmp);
1873 MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OS);
1874 Streamer.emitBytes(OS.str());
1875 }
1876
EncodeAdvanceLoc(MCContext & Context,uint64_t AddrDelta,raw_ostream & OS)1877 void MCDwarfFrameEmitter::EncodeAdvanceLoc(MCContext &Context,
1878 uint64_t AddrDelta,
1879 raw_ostream &OS) {
1880 // Scale the address delta by the minimum instruction length.
1881 AddrDelta = ScaleAddrDelta(Context, AddrDelta);
1882 if (AddrDelta == 0)
1883 return;
1884
1885 support::endianness E =
1886 Context.getAsmInfo()->isLittleEndian() ? support::little : support::big;
1887
1888 if (isUIntN(6, AddrDelta)) {
1889 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
1890 OS << Opcode;
1891 } else if (isUInt<8>(AddrDelta)) {
1892 OS << uint8_t(dwarf::DW_CFA_advance_loc1);
1893 OS << uint8_t(AddrDelta);
1894 } else if (isUInt<16>(AddrDelta)) {
1895 OS << uint8_t(dwarf::DW_CFA_advance_loc2);
1896 support::endian::write<uint16_t>(OS, AddrDelta, E);
1897 } else {
1898 assert(isUInt<32>(AddrDelta));
1899 OS << uint8_t(dwarf::DW_CFA_advance_loc4);
1900 support::endian::write<uint32_t>(OS, AddrDelta, E);
1901 }
1902 }
1903