aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/llvm12/lib/DWARFLinker/DWARFStreamer.cpp
blob: c0043ae39efecea5edf4d0b93bfe8f57c2a255e0 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
//===- DwarfStreamer.cpp --------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "llvm/DWARFLinker/DWARFStreamer.h"
#include "llvm/ADT/Triple.h"
#include "llvm/CodeGen/NonRelocatableStringpool.h"
#include "llvm/DWARFLinker/DWARFLinkerCompileUnit.h"
#include "llvm/DebugInfo/DWARF/DWARFContext.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCTargetOptions.h"
#include "llvm/MC/MCTargetOptionsCommandFlags.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Target/TargetOptions.h"

namespace llvm {

bool DwarfStreamer::init(Triple TheTriple) {
  std::string ErrorStr;
  std::string TripleName;
  StringRef Context = "dwarf streamer init";

  // Get the target.
  const Target *TheTarget =
      TargetRegistry::lookupTarget(TripleName, TheTriple, ErrorStr);
  if (!TheTarget)
    return error(ErrorStr, Context), false;
  TripleName = TheTriple.getTriple();

  // Create all the MC Objects.
  MRI.reset(TheTarget->createMCRegInfo(TripleName));
  if (!MRI)
    return error(Twine("no register info for target ") + TripleName, Context),
           false;

  MCTargetOptions MCOptions = mc::InitMCTargetOptionsFromFlags();
  MAI.reset(TheTarget->createMCAsmInfo(*MRI, TripleName, MCOptions));
  if (!MAI)
    return error("no asm info for target " + TripleName, Context), false;

  MOFI.reset(new MCObjectFileInfo);
  MC.reset(new MCContext(MAI.get(), MRI.get(), MOFI.get()));
  MOFI->InitMCObjectFileInfo(TheTriple, /*PIC*/ false, *MC);

  MSTI.reset(TheTarget->createMCSubtargetInfo(TripleName, "", ""));
  if (!MSTI)
    return error("no subtarget info for target " + TripleName, Context), false;

  MAB = TheTarget->createMCAsmBackend(*MSTI, *MRI, MCOptions);
  if (!MAB)
    return error("no asm backend for target " + TripleName, Context), false;

  MII.reset(TheTarget->createMCInstrInfo());
  if (!MII)
    return error("no instr info info for target " + TripleName, Context), false;

  MCE = TheTarget->createMCCodeEmitter(*MII, *MRI, *MC);
  if (!MCE)
    return error("no code emitter for target " + TripleName, Context), false;

  switch (OutFileType) {
  case OutputFileType::Assembly: {
    MIP = TheTarget->createMCInstPrinter(TheTriple, MAI->getAssemblerDialect(),
                                         *MAI, *MII, *MRI);
    MS = TheTarget->createAsmStreamer(
        *MC, std::make_unique<formatted_raw_ostream>(OutFile), true, true, MIP,
        std::unique_ptr<MCCodeEmitter>(MCE), std::unique_ptr<MCAsmBackend>(MAB),
        true);
    break;
  }
  case OutputFileType::Object: {
    MS = TheTarget->createMCObjectStreamer(
        TheTriple, *MC, std::unique_ptr<MCAsmBackend>(MAB),
        MAB->createObjectWriter(OutFile), std::unique_ptr<MCCodeEmitter>(MCE),
        *MSTI, MCOptions.MCRelaxAll, MCOptions.MCIncrementalLinkerCompatible,
        /*DWARFMustBeAtTheEnd*/ false);
    break;
  }
  }

  if (!MS)
    return error("no object streamer for target " + TripleName, Context), false;

  // Finally create the AsmPrinter we'll use to emit the DIEs.
  TM.reset(TheTarget->createTargetMachine(TripleName, "", "", TargetOptions(),
                                          None));
  if (!TM)
    return error("no target machine for target " + TripleName, Context), false;

  Asm.reset(TheTarget->createAsmPrinter(*TM, std::unique_ptr<MCStreamer>(MS)));
  if (!Asm)
    return error("no asm printer for target " + TripleName, Context), false;

  RangesSectionSize = 0;
  LocSectionSize = 0;
  LineSectionSize = 0;
  FrameSectionSize = 0;
  DebugInfoSectionSize = 0;

  return true;
}

void DwarfStreamer::finish() { MS->Finish(); }

void DwarfStreamer::switchToDebugInfoSection(unsigned DwarfVersion) {
  MS->SwitchSection(MOFI->getDwarfInfoSection());
  MC->setDwarfVersion(DwarfVersion);
}

/// Emit the compilation unit header for \p Unit in the debug_info section.
///
/// A Dwarf 4 section header is encoded as:
///  uint32_t   Unit length (omitting this field)
///  uint16_t   Version
///  uint32_t   Abbreviation table offset
///  uint8_t    Address size
/// Leading to a total of 11 bytes.
///
/// A Dwarf 5 section header is encoded as:
///  uint32_t   Unit length (omitting this field)
///  uint16_t   Version
///  uint8_t    Unit type
///  uint8_t    Address size
///  uint32_t   Abbreviation table offset
/// Leading to a total of 12 bytes.
void DwarfStreamer::emitCompileUnitHeader(CompileUnit &Unit,
                                          unsigned DwarfVersion) {
  switchToDebugInfoSection(DwarfVersion);

  /// The start of the unit within its section.
  Unit.setLabelBegin(Asm->createTempSymbol("cu_begin"));
  Asm->OutStreamer->emitLabel(Unit.getLabelBegin());

  // Emit size of content not including length itself. The size has already
  // been computed in CompileUnit::computeOffsets(). Subtract 4 to that size to
  // account for the length field.
  Asm->emitInt32(Unit.getNextUnitOffset() - Unit.getStartOffset() - 4);
  Asm->emitInt16(DwarfVersion);

  if (DwarfVersion >= 5) {
    Asm->emitInt8(dwarf::DW_UT_compile);
    Asm->emitInt8(Unit.getOrigUnit().getAddressByteSize());
    // We share one abbreviations table across all units so it's always at the
    // start of the section.
    Asm->emitInt32(0);
    DebugInfoSectionSize += 12;
  } else {
    // We share one abbreviations table across all units so it's always at the
    // start of the section.
    Asm->emitInt32(0);
    Asm->emitInt8(Unit.getOrigUnit().getAddressByteSize());
    DebugInfoSectionSize += 11;
  }

  // Remember this CU.
  EmittedUnits.push_back({Unit.getUniqueID(), Unit.getLabelBegin()});
}

/// Emit the \p Abbrevs array as the shared abbreviation table
/// for the linked Dwarf file.
void DwarfStreamer::emitAbbrevs(
    const std::vector<std::unique_ptr<DIEAbbrev>> &Abbrevs,
    unsigned DwarfVersion) {
  MS->SwitchSection(MOFI->getDwarfAbbrevSection());
  MC->setDwarfVersion(DwarfVersion);
  Asm->emitDwarfAbbrevs(Abbrevs);
}

/// Recursively emit the DIE tree rooted at \p Die.
void DwarfStreamer::emitDIE(DIE &Die) {
  MS->SwitchSection(MOFI->getDwarfInfoSection());
  Asm->emitDwarfDIE(Die);
  DebugInfoSectionSize += Die.getSize();
}

/// Emit contents of section SecName From Obj.
void DwarfStreamer::emitSectionContents(StringRef SecData, StringRef SecName) {
  MCSection *Section =
      StringSwitch<MCSection *>(SecName)
          .Case("debug_line", MC->getObjectFileInfo()->getDwarfLineSection())
          .Case("debug_loc", MC->getObjectFileInfo()->getDwarfLocSection())
          .Case("debug_ranges",
                MC->getObjectFileInfo()->getDwarfRangesSection())
          .Case("debug_frame", MC->getObjectFileInfo()->getDwarfFrameSection())
          .Case("debug_aranges",
                MC->getObjectFileInfo()->getDwarfARangesSection())
          .Default(nullptr);

  if (Section) {
    MS->SwitchSection(Section);

    MS->emitBytes(SecData);
  }
}

/// Emit DIE containing warnings.
void DwarfStreamer::emitPaperTrailWarningsDie(DIE &Die) {
  switchToDebugInfoSection(/* Version */ 2);
  auto &Asm = getAsmPrinter();
  Asm.emitInt32(11 + Die.getSize() - 4);
  Asm.emitInt16(2);
  Asm.emitInt32(0);
  Asm.emitInt8(MOFI->getTargetTriple().isArch64Bit() ? 8 : 4);
  DebugInfoSectionSize += 11;
  emitDIE(Die);
}

/// Emit the debug_str section stored in \p Pool.
void DwarfStreamer::emitStrings(const NonRelocatableStringpool &Pool) {
  Asm->OutStreamer->SwitchSection(MOFI->getDwarfStrSection());
  std::vector<DwarfStringPoolEntryRef> Entries = Pool.getEntriesForEmission();
  for (auto Entry : Entries) {
    // Emit the string itself.
    Asm->OutStreamer->emitBytes(Entry.getString());
    // Emit a null terminator.
    Asm->emitInt8(0);
  }

#if 0
  if (DwarfVersion >= 5) {
    // Emit an empty string offset section.
    Asm->OutStreamer->SwitchSection(MOFI->getDwarfStrOffSection());
    Asm->emitDwarfUnitLength(4, "Length of String Offsets Set");
    Asm->emitInt16(DwarfVersion);
    Asm->emitInt16(0);
  }
#endif
}

void DwarfStreamer::emitDebugNames(
    AccelTable<DWARF5AccelTableStaticData> &Table) {
  if (EmittedUnits.empty())
    return;

  // Build up data structures needed to emit this section.
  std::vector<MCSymbol *> CompUnits;
  DenseMap<unsigned, size_t> UniqueIdToCuMap;
  unsigned Id = 0;
  for (auto &CU : EmittedUnits) {
    CompUnits.push_back(CU.LabelBegin);
    // We might be omitting CUs, so we need to remap them.
    UniqueIdToCuMap[CU.ID] = Id++;
  }

  Asm->OutStreamer->SwitchSection(MOFI->getDwarfDebugNamesSection());
  emitDWARF5AccelTable(
      Asm.get(), Table, CompUnits,
      [&UniqueIdToCuMap](const DWARF5AccelTableStaticData &Entry) {
        return UniqueIdToCuMap[Entry.getCUIndex()];
      });
}

void DwarfStreamer::emitAppleNamespaces(
    AccelTable<AppleAccelTableStaticOffsetData> &Table) {
  Asm->OutStreamer->SwitchSection(MOFI->getDwarfAccelNamespaceSection());
  auto *SectionBegin = Asm->createTempSymbol("namespac_begin");
  Asm->OutStreamer->emitLabel(SectionBegin);
  emitAppleAccelTable(Asm.get(), Table, "namespac", SectionBegin);
}

void DwarfStreamer::emitAppleNames(
    AccelTable<AppleAccelTableStaticOffsetData> &Table) {
  Asm->OutStreamer->SwitchSection(MOFI->getDwarfAccelNamesSection());
  auto *SectionBegin = Asm->createTempSymbol("names_begin");
  Asm->OutStreamer->emitLabel(SectionBegin);
  emitAppleAccelTable(Asm.get(), Table, "names", SectionBegin);
}

void DwarfStreamer::emitAppleObjc(
    AccelTable<AppleAccelTableStaticOffsetData> &Table) {
  Asm->OutStreamer->SwitchSection(MOFI->getDwarfAccelObjCSection());
  auto *SectionBegin = Asm->createTempSymbol("objc_begin");
  Asm->OutStreamer->emitLabel(SectionBegin);
  emitAppleAccelTable(Asm.get(), Table, "objc", SectionBegin);
}

void DwarfStreamer::emitAppleTypes(
    AccelTable<AppleAccelTableStaticTypeData> &Table) {
  Asm->OutStreamer->SwitchSection(MOFI->getDwarfAccelTypesSection());
  auto *SectionBegin = Asm->createTempSymbol("types_begin");
  Asm->OutStreamer->emitLabel(SectionBegin);
  emitAppleAccelTable(Asm.get(), Table, "types", SectionBegin);
}

/// Emit the swift_ast section stored in \p Buffers.
void DwarfStreamer::emitSwiftAST(StringRef Buffer) {
  MCSection *SwiftASTSection = MOFI->getDwarfSwiftASTSection();
  SwiftASTSection->setAlignment(Align(32));
  MS->SwitchSection(SwiftASTSection);
  MS->emitBytes(Buffer);
}

/// Emit the debug_range section contents for \p FuncRange by
/// translating the original \p Entries. The debug_range section
/// format is totally trivial, consisting just of pairs of address
/// sized addresses describing the ranges.
void DwarfStreamer::emitRangesEntries(
    int64_t UnitPcOffset, uint64_t OrigLowPc,
    const FunctionIntervals::const_iterator &FuncRange,
    const std::vector<DWARFDebugRangeList::RangeListEntry> &Entries,
    unsigned AddressSize) {
  MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection());

  // Offset each range by the right amount.
  int64_t PcOffset = Entries.empty() ? 0 : FuncRange.value() + UnitPcOffset;
  for (const auto &Range : Entries) {
    if (Range.isBaseAddressSelectionEntry(AddressSize)) {
      warn("unsupported base address selection operation",
           "emitting debug_ranges");
      break;
    }
    // Do not emit empty ranges.
    if (Range.StartAddress == Range.EndAddress)
      continue;

    // All range entries should lie in the function range.
    if (!(Range.StartAddress + OrigLowPc >= FuncRange.start() &&
          Range.EndAddress + OrigLowPc <= FuncRange.stop()))
      warn("inconsistent range data.", "emitting debug_ranges");
    MS->emitIntValue(Range.StartAddress + PcOffset, AddressSize);
    MS->emitIntValue(Range.EndAddress + PcOffset, AddressSize);
    RangesSectionSize += 2 * AddressSize;
  }

  // Add the terminator entry.
  MS->emitIntValue(0, AddressSize);
  MS->emitIntValue(0, AddressSize);
  RangesSectionSize += 2 * AddressSize;
}

/// Emit the debug_aranges contribution of a unit and
/// if \p DoDebugRanges is true the debug_range contents for a
/// compile_unit level DW_AT_ranges attribute (Which are basically the
/// same thing with a different base address).
/// Just aggregate all the ranges gathered inside that unit.
void DwarfStreamer::emitUnitRangesEntries(CompileUnit &Unit,
                                          bool DoDebugRanges) {
  unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
  // Gather the ranges in a vector, so that we can simplify them. The
  // IntervalMap will have coalesced the non-linked ranges, but here
  // we want to coalesce the linked addresses.
  std::vector<std::pair<uint64_t, uint64_t>> Ranges;
  const auto &FunctionRanges = Unit.getFunctionRanges();
  for (auto Range = FunctionRanges.begin(), End = FunctionRanges.end();
       Range != End; ++Range)
    Ranges.push_back(std::make_pair(Range.start() + Range.value(),
                                    Range.stop() + Range.value()));

  // The object addresses where sorted, but again, the linked
  // addresses might end up in a different order.
  llvm::sort(Ranges);

  if (!Ranges.empty()) {
    MS->SwitchSection(MC->getObjectFileInfo()->getDwarfARangesSection());

    MCSymbol *BeginLabel = Asm->createTempSymbol("Barange");
    MCSymbol *EndLabel = Asm->createTempSymbol("Earange");

    unsigned HeaderSize =
        sizeof(int32_t) + // Size of contents (w/o this field
        sizeof(int16_t) + // DWARF ARange version number
        sizeof(int32_t) + // Offset of CU in the .debug_info section
        sizeof(int8_t) +  // Pointer Size (in bytes)
        sizeof(int8_t);   // Segment Size (in bytes)

    unsigned TupleSize = AddressSize * 2;
    unsigned Padding = offsetToAlignment(HeaderSize, Align(TupleSize));

    Asm->emitLabelDifference(EndLabel, BeginLabel, 4); // Arange length
    Asm->OutStreamer->emitLabel(BeginLabel);
    Asm->emitInt16(dwarf::DW_ARANGES_VERSION); // Version number
    Asm->emitInt32(Unit.getStartOffset());     // Corresponding unit's offset
    Asm->emitInt8(AddressSize);                // Address size
    Asm->emitInt8(0);                          // Segment size

    Asm->OutStreamer->emitFill(Padding, 0x0);

    for (auto Range = Ranges.begin(), End = Ranges.end(); Range != End;
         ++Range) {
      uint64_t RangeStart = Range->first;
      MS->emitIntValue(RangeStart, AddressSize);
      while ((Range + 1) != End && Range->second == (Range + 1)->first)
        ++Range;
      MS->emitIntValue(Range->second - RangeStart, AddressSize);
    }

    // Emit terminator
    Asm->OutStreamer->emitIntValue(0, AddressSize);
    Asm->OutStreamer->emitIntValue(0, AddressSize);
    Asm->OutStreamer->emitLabel(EndLabel);
  }

  if (!DoDebugRanges)
    return;

  MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection());
  // Offset each range by the right amount.
  int64_t PcOffset = -Unit.getLowPc();
  // Emit coalesced ranges.
  for (auto Range = Ranges.begin(), End = Ranges.end(); Range != End; ++Range) {
    MS->emitIntValue(Range->first + PcOffset, AddressSize);
    while (Range + 1 != End && Range->second == (Range + 1)->first)
      ++Range;
    MS->emitIntValue(Range->second + PcOffset, AddressSize);
    RangesSectionSize += 2 * AddressSize;
  }

  // Add the terminator entry.
  MS->emitIntValue(0, AddressSize);
  MS->emitIntValue(0, AddressSize);
  RangesSectionSize += 2 * AddressSize;
}

/// Emit location lists for \p Unit and update attributes to point to the new
/// entries.
void DwarfStreamer::emitLocationsForUnit(
    const CompileUnit &Unit, DWARFContext &Dwarf,
    std::function<void(StringRef, SmallVectorImpl<uint8_t> &)> ProcessExpr) {
  const auto &Attributes = Unit.getLocationAttributes();

  if (Attributes.empty())
    return;

  MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLocSection());

  unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
  uint64_t BaseAddressMarker = (AddressSize == 8)
                                   ? std::numeric_limits<uint64_t>::max()
                                   : std::numeric_limits<uint32_t>::max();
  const DWARFSection &InputSec = Dwarf.getDWARFObj().getLocSection();
  DataExtractor Data(InputSec.Data, Dwarf.isLittleEndian(), AddressSize);
  DWARFUnit &OrigUnit = Unit.getOrigUnit();
  auto OrigUnitDie = OrigUnit.getUnitDIE(false);
  int64_t UnitPcOffset = 0;
  if (auto OrigLowPc = dwarf::toAddress(OrigUnitDie.find(dwarf::DW_AT_low_pc)))
    UnitPcOffset = int64_t(*OrigLowPc) - Unit.getLowPc();

  SmallVector<uint8_t, 32> Buffer;
  for (const auto &Attr : Attributes) {
    uint64_t Offset = Attr.first.get();
    Attr.first.set(LocSectionSize);
    // This is the quantity to add to the old location address to get
    // the correct address for the new one.
    int64_t LocPcOffset = Attr.second + UnitPcOffset;
    while (Data.isValidOffset(Offset)) {
      uint64_t Low = Data.getUnsigned(&Offset, AddressSize);
      uint64_t High = Data.getUnsigned(&Offset, AddressSize);
      LocSectionSize += 2 * AddressSize;
      // End of list entry.
      if (Low == 0 && High == 0) {
        Asm->OutStreamer->emitIntValue(0, AddressSize);
        Asm->OutStreamer->emitIntValue(0, AddressSize);
        break;
      }
      // Base address selection entry.
      if (Low == BaseAddressMarker) {
        Asm->OutStreamer->emitIntValue(BaseAddressMarker, AddressSize);
        Asm->OutStreamer->emitIntValue(High + Attr.second, AddressSize);
        LocPcOffset = 0;
        continue;
      }
      // Location list entry.
      Asm->OutStreamer->emitIntValue(Low + LocPcOffset, AddressSize);
      Asm->OutStreamer->emitIntValue(High + LocPcOffset, AddressSize);
      uint64_t Length = Data.getU16(&Offset);
      Asm->OutStreamer->emitIntValue(Length, 2);
      // Copy the bytes into to the buffer, process them, emit them.
      Buffer.reserve(Length);
      Buffer.resize(0);
      StringRef Input = InputSec.Data.substr(Offset, Length);
      ProcessExpr(Input, Buffer);
      Asm->OutStreamer->emitBytes(
          StringRef((const char *)Buffer.data(), Length));
      Offset += Length;
      LocSectionSize += Length + 2;
    }
  }
}

void DwarfStreamer::emitLineTableForUnit(MCDwarfLineTableParams Params,
                                         StringRef PrologueBytes,
                                         unsigned MinInstLength,
                                         std::vector<DWARFDebugLine::Row> &Rows,
                                         unsigned PointerSize) {
  // Switch to the section where the table will be emitted into.
  MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLineSection());
  MCSymbol *LineStartSym = MC->createTempSymbol();
  MCSymbol *LineEndSym = MC->createTempSymbol();

  // The first 4 bytes is the total length of the information for this
  // compilation unit (not including these 4 bytes for the length).
  Asm->emitLabelDifference(LineEndSym, LineStartSym, 4);
  Asm->OutStreamer->emitLabel(LineStartSym);
  // Copy Prologue.
  MS->emitBytes(PrologueBytes);
  LineSectionSize += PrologueBytes.size() + 4;

  SmallString<128> EncodingBuffer;
  raw_svector_ostream EncodingOS(EncodingBuffer);

  if (Rows.empty()) {
    // We only have the dummy entry, dsymutil emits an entry with a 0
    // address in that case.
    MCDwarfLineAddr::Encode(*MC, Params, std::numeric_limits<int64_t>::max(), 0,
                            EncodingOS);
    MS->emitBytes(EncodingOS.str());
    LineSectionSize += EncodingBuffer.size();
    MS->emitLabel(LineEndSym);
    return;
  }

  // Line table state machine fields
  unsigned FileNum = 1;
  unsigned LastLine = 1;
  unsigned Column = 0;
  unsigned IsStatement = 1;
  unsigned Isa = 0;
  uint64_t Address = -1ULL;

  unsigned RowsSinceLastSequence = 0;

  for (unsigned Idx = 0; Idx < Rows.size(); ++Idx) {
    auto &Row = Rows[Idx];

    int64_t AddressDelta;
    if (Address == -1ULL) {
      MS->emitIntValue(dwarf::DW_LNS_extended_op, 1);
      MS->emitULEB128IntValue(PointerSize + 1);
      MS->emitIntValue(dwarf::DW_LNE_set_address, 1);
      MS->emitIntValue(Row.Address.Address, PointerSize);
      LineSectionSize += 2 + PointerSize + getULEB128Size(PointerSize + 1);
      AddressDelta = 0;
    } else {
      AddressDelta = (Row.Address.Address - Address) / MinInstLength;
    }

    // FIXME: code copied and transformed from MCDwarf.cpp::EmitDwarfLineTable.
    // We should find a way to share this code, but the current compatibility
    // requirement with classic dsymutil makes it hard. Revisit that once this
    // requirement is dropped.

    if (FileNum != Row.File) {
      FileNum = Row.File;
      MS->emitIntValue(dwarf::DW_LNS_set_file, 1);
      MS->emitULEB128IntValue(FileNum);
      LineSectionSize += 1 + getULEB128Size(FileNum);
    }
    if (Column != Row.Column) {
      Column = Row.Column;
      MS->emitIntValue(dwarf::DW_LNS_set_column, 1);
      MS->emitULEB128IntValue(Column);
      LineSectionSize += 1 + getULEB128Size(Column);
    }

    // FIXME: We should handle the discriminator here, but dsymutil doesn't
    // consider it, thus ignore it for now.

    if (Isa != Row.Isa) {
      Isa = Row.Isa;
      MS->emitIntValue(dwarf::DW_LNS_set_isa, 1);
      MS->emitULEB128IntValue(Isa);
      LineSectionSize += 1 + getULEB128Size(Isa);
    }
    if (IsStatement != Row.IsStmt) {
      IsStatement = Row.IsStmt;
      MS->emitIntValue(dwarf::DW_LNS_negate_stmt, 1);
      LineSectionSize += 1;
    }
    if (Row.BasicBlock) {
      MS->emitIntValue(dwarf::DW_LNS_set_basic_block, 1);
      LineSectionSize += 1;
    }

    if (Row.PrologueEnd) {
      MS->emitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
      LineSectionSize += 1;
    }

    if (Row.EpilogueBegin) {
      MS->emitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
      LineSectionSize += 1;
    }

    int64_t LineDelta = int64_t(Row.Line) - LastLine;
    if (!Row.EndSequence) {
      MCDwarfLineAddr::Encode(*MC, Params, LineDelta, AddressDelta, EncodingOS);
      MS->emitBytes(EncodingOS.str());
      LineSectionSize += EncodingBuffer.size();
      EncodingBuffer.resize(0);
      Address = Row.Address.Address;
      LastLine = Row.Line;
      RowsSinceLastSequence++;
    } else {
      if (LineDelta) {
        MS->emitIntValue(dwarf::DW_LNS_advance_line, 1);
        MS->emitSLEB128IntValue(LineDelta);
        LineSectionSize += 1 + getSLEB128Size(LineDelta);
      }
      if (AddressDelta) {
        MS->emitIntValue(dwarf::DW_LNS_advance_pc, 1);
        MS->emitULEB128IntValue(AddressDelta);
        LineSectionSize += 1 + getULEB128Size(AddressDelta);
      }
      MCDwarfLineAddr::Encode(*MC, Params, std::numeric_limits<int64_t>::max(),
                              0, EncodingOS);
      MS->emitBytes(EncodingOS.str());
      LineSectionSize += EncodingBuffer.size();
      EncodingBuffer.resize(0);
      Address = -1ULL;
      LastLine = FileNum = IsStatement = 1;
      RowsSinceLastSequence = Column = Isa = 0;
    }
  }

  if (RowsSinceLastSequence) {
    MCDwarfLineAddr::Encode(*MC, Params, std::numeric_limits<int64_t>::max(), 0,
                            EncodingOS);
    MS->emitBytes(EncodingOS.str());
    LineSectionSize += EncodingBuffer.size();
    EncodingBuffer.resize(0);
  }

  MS->emitLabel(LineEndSym);
}

/// Copy the debug_line over to the updated binary while unobfuscating the file
/// names and directories.
void DwarfStreamer::translateLineTable(DataExtractor Data, uint64_t Offset) {
  MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLineSection());
  StringRef Contents = Data.getData();

  // We have to deconstruct the line table header, because it contains to
  // length fields that will need to be updated when we change the length of
  // the files and directories in there.
  unsigned UnitLength = Data.getU32(&Offset);
  uint64_t UnitEnd = Offset + UnitLength;
  MCSymbol *BeginLabel = MC->createTempSymbol();
  MCSymbol *EndLabel = MC->createTempSymbol();
  unsigned Version = Data.getU16(&Offset);

  if (Version > 5) {
    warn("Unsupported line table version: dropping contents and not "
         "unobfsucating line table.");
    return;
  }

  Asm->emitLabelDifference(EndLabel, BeginLabel, 4);
  Asm->OutStreamer->emitLabel(BeginLabel);
  Asm->emitInt16(Version);
  LineSectionSize += 6;

  MCSymbol *HeaderBeginLabel = MC->createTempSymbol();
  MCSymbol *HeaderEndLabel = MC->createTempSymbol();
  Asm->emitLabelDifference(HeaderEndLabel, HeaderBeginLabel, 4);
  Asm->OutStreamer->emitLabel(HeaderBeginLabel);
  Offset += 4;
  LineSectionSize += 4;

  uint64_t AfterHeaderLengthOffset = Offset;
  // Skip to the directories.
  Offset += (Version >= 4) ? 5 : 4;
  unsigned OpcodeBase = Data.getU8(&Offset);
  Offset += OpcodeBase - 1;
  Asm->OutStreamer->emitBytes(Contents.slice(AfterHeaderLengthOffset, Offset));
  LineSectionSize += Offset - AfterHeaderLengthOffset;

  // Offset points to the first directory.
  while (const char *Dir = Data.getCStr(&Offset)) {
    if (Dir[0] == 0)
      break;

    StringRef Translated = Translator(Dir);
    Asm->OutStreamer->emitBytes(Translated);
    Asm->emitInt8(0);
    LineSectionSize += Translated.size() + 1;
  }
  Asm->emitInt8(0);
  LineSectionSize += 1;

  while (const char *File = Data.getCStr(&Offset)) {
    if (File[0] == 0)
      break;

    StringRef Translated = Translator(File);
    Asm->OutStreamer->emitBytes(Translated);
    Asm->emitInt8(0);
    LineSectionSize += Translated.size() + 1;

    uint64_t OffsetBeforeLEBs = Offset;
    Asm->emitULEB128(Data.getULEB128(&Offset));
    Asm->emitULEB128(Data.getULEB128(&Offset));
    Asm->emitULEB128(Data.getULEB128(&Offset));
    LineSectionSize += Offset - OffsetBeforeLEBs;
  }
  Asm->emitInt8(0);
  LineSectionSize += 1;

  Asm->OutStreamer->emitLabel(HeaderEndLabel);

  // Copy the actual line table program over.
  Asm->OutStreamer->emitBytes(Contents.slice(Offset, UnitEnd));
  LineSectionSize += UnitEnd - Offset;

  Asm->OutStreamer->emitLabel(EndLabel);
  Offset = UnitEnd;
}

/// Emit the pubnames or pubtypes section contribution for \p
/// Unit into \p Sec. The data is provided in \p Names.
void DwarfStreamer::emitPubSectionForUnit(
    MCSection *Sec, StringRef SecName, const CompileUnit &Unit,
    const std::vector<CompileUnit::AccelInfo> &Names) {
  if (Names.empty())
    return;

  // Start the dwarf pubnames section.
  Asm->OutStreamer->SwitchSection(Sec);
  MCSymbol *BeginLabel = Asm->createTempSymbol("pub" + SecName + "_begin");
  MCSymbol *EndLabel = Asm->createTempSymbol("pub" + SecName + "_end");

  bool HeaderEmitted = false;
  // Emit the pubnames for this compilation unit.
  for (const auto &Name : Names) {
    if (Name.SkipPubSection)
      continue;

    if (!HeaderEmitted) {
      // Emit the header.
      Asm->emitLabelDifference(EndLabel, BeginLabel, 4); // Length
      Asm->OutStreamer->emitLabel(BeginLabel);
      Asm->emitInt16(dwarf::DW_PUBNAMES_VERSION); // Version
      Asm->emitInt32(Unit.getStartOffset());      // Unit offset
      Asm->emitInt32(Unit.getNextUnitOffset() - Unit.getStartOffset()); // Size
      HeaderEmitted = true;
    }
    Asm->emitInt32(Name.Die->getOffset());

    // Emit the string itself.
    Asm->OutStreamer->emitBytes(Name.Name.getString());
    // Emit a null terminator.
    Asm->emitInt8(0);
  }

  if (!HeaderEmitted)
    return;
  Asm->emitInt32(0); // End marker.
  Asm->OutStreamer->emitLabel(EndLabel);
}

/// Emit .debug_pubnames for \p Unit.
void DwarfStreamer::emitPubNamesForUnit(const CompileUnit &Unit) {
  if (Minimize)
    return;
  emitPubSectionForUnit(MC->getObjectFileInfo()->getDwarfPubNamesSection(),
                        "names", Unit, Unit.getPubnames());
}

/// Emit .debug_pubtypes for \p Unit.
void DwarfStreamer::emitPubTypesForUnit(const CompileUnit &Unit) {
  if (Minimize)
    return;
  emitPubSectionForUnit(MC->getObjectFileInfo()->getDwarfPubTypesSection(),
                        "types", Unit, Unit.getPubtypes());
}

/// Emit a CIE into the debug_frame section.
void DwarfStreamer::emitCIE(StringRef CIEBytes) {
  MS->SwitchSection(MC->getObjectFileInfo()->getDwarfFrameSection());

  MS->emitBytes(CIEBytes);
  FrameSectionSize += CIEBytes.size();
}

/// Emit a FDE into the debug_frame section. \p FDEBytes
/// contains the FDE data without the length, CIE offset and address
/// which will be replaced with the parameter values.
void DwarfStreamer::emitFDE(uint32_t CIEOffset, uint32_t AddrSize,
                            uint32_t Address, StringRef FDEBytes) {
  MS->SwitchSection(MC->getObjectFileInfo()->getDwarfFrameSection());

  MS->emitIntValue(FDEBytes.size() + 4 + AddrSize, 4);
  MS->emitIntValue(CIEOffset, 4);
  MS->emitIntValue(Address, AddrSize);
  MS->emitBytes(FDEBytes);
  FrameSectionSize += FDEBytes.size() + 8 + AddrSize;
}

} // namespace llvm