aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/llvm12/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
blob: befc4bba19a29e9dd4ea320eab10759f112db543 (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
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
//===- llvm/CodeGen/DwarfCompileUnit.cpp - Dwarf Compile Units ------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file contains support for constructing a dwarf compile unit.
//
//===----------------------------------------------------------------------===//

#include "DwarfCompileUnit.h"
#include "AddressPool.h"
#include "DwarfExpression.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/DIE.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/TargetFrameLowering.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCSymbolWasm.h"
#include "llvm/MC/MachineLocation.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include <iterator>
#include <string>
#include <utility>

using namespace llvm;

static dwarf::Tag GetCompileUnitType(UnitKind Kind, DwarfDebug *DW) {

  //  According to DWARF Debugging Information Format Version 5,
  //  3.1.2 Skeleton Compilation Unit Entries:
  //  "When generating a split DWARF object file (see Section 7.3.2
  //  on page 187), the compilation unit in the .debug_info section
  //  is a "skeleton" compilation unit with the tag DW_TAG_skeleton_unit"
  if (DW->getDwarfVersion() >= 5 && Kind == UnitKind::Skeleton)
    return dwarf::DW_TAG_skeleton_unit;

  return dwarf::DW_TAG_compile_unit;
}

DwarfCompileUnit::DwarfCompileUnit(unsigned UID, const DICompileUnit *Node,
                                   AsmPrinter *A, DwarfDebug *DW,
                                   DwarfFile *DWU, UnitKind Kind)
    : DwarfUnit(GetCompileUnitType(Kind, DW), Node, A, DW, DWU), UniqueID(UID) {
  insertDIE(Node, &getUnitDie());
  MacroLabelBegin = Asm->createTempSymbol("cu_macro_begin");
}

/// addLabelAddress - Add a dwarf label attribute data and value using
/// DW_FORM_addr or DW_FORM_GNU_addr_index.
void DwarfCompileUnit::addLabelAddress(DIE &Die, dwarf::Attribute Attribute,
                                       const MCSymbol *Label) {
  // Don't use the address pool in non-fission or in the skeleton unit itself.
  if ((!DD->useSplitDwarf() || !Skeleton) && DD->getDwarfVersion() < 5)
    return addLocalLabelAddress(Die, Attribute, Label);

  if (Label)
    DD->addArangeLabel(SymbolCU(this, Label));

  unsigned idx = DD->getAddressPool().getIndex(Label);
  Die.addValue(DIEValueAllocator, Attribute,
               DD->getDwarfVersion() >= 5 ? dwarf::DW_FORM_addrx
                                          : dwarf::DW_FORM_GNU_addr_index,
               DIEInteger(idx));
}

void DwarfCompileUnit::addLocalLabelAddress(DIE &Die,
                                            dwarf::Attribute Attribute,
                                            const MCSymbol *Label) {
  if (Label)
    DD->addArangeLabel(SymbolCU(this, Label));

  if (Label)
    Die.addValue(DIEValueAllocator, Attribute, dwarf::DW_FORM_addr,
                 DIELabel(Label));
  else
    Die.addValue(DIEValueAllocator, Attribute, dwarf::DW_FORM_addr,
                 DIEInteger(0));
}

unsigned DwarfCompileUnit::getOrCreateSourceID(const DIFile *File) {
  // If we print assembly, we can't separate .file entries according to
  // compile units. Thus all files will belong to the default compile unit.

  // FIXME: add a better feature test than hasRawTextSupport. Even better,
  // extend .file to support this.
  unsigned CUID = Asm->OutStreamer->hasRawTextSupport() ? 0 : getUniqueID();
  if (!File)
    return Asm->OutStreamer->emitDwarfFileDirective(0, "", "", None, None,
                                                    CUID);
  return Asm->OutStreamer->emitDwarfFileDirective(
      0, File->getDirectory(), File->getFilename(), DD->getMD5AsBytes(File),
      File->getSource(), CUID);
}

DIE *DwarfCompileUnit::getOrCreateGlobalVariableDIE(
    const DIGlobalVariable *GV, ArrayRef<GlobalExpr> GlobalExprs) {
  // Check for pre-existence.
  if (DIE *Die = getDIE(GV))
    return Die;

  assert(GV);

  auto *GVContext = GV->getScope();
  const DIType *GTy = GV->getType();

  // Construct the context before querying for the existence of the DIE in
  // case such construction creates the DIE.
  auto *CB = GVContext ? dyn_cast<DICommonBlock>(GVContext) : nullptr;
  DIE *ContextDIE = CB ? getOrCreateCommonBlock(CB, GlobalExprs)
    : getOrCreateContextDIE(GVContext);

  // Add to map.
  DIE *VariableDIE = &createAndAddDIE(GV->getTag(), *ContextDIE, GV);
  DIScope *DeclContext;
  if (auto *SDMDecl = GV->getStaticDataMemberDeclaration()) {
    DeclContext = SDMDecl->getScope();
    assert(SDMDecl->isStaticMember() && "Expected static member decl");
    assert(GV->isDefinition());
    // We need the declaration DIE that is in the static member's class.
    DIE *VariableSpecDIE = getOrCreateStaticMemberDIE(SDMDecl);
    addDIEEntry(*VariableDIE, dwarf::DW_AT_specification, *VariableSpecDIE);
    // If the global variable's type is different from the one in the class
    // member type, assume that it's more specific and also emit it.
    if (GTy != SDMDecl->getBaseType())
      addType(*VariableDIE, GTy);
  } else {
    DeclContext = GV->getScope();
    // Add name and type.
    addString(*VariableDIE, dwarf::DW_AT_name, GV->getDisplayName());
    if (GTy)
      addType(*VariableDIE, GTy);

    // Add scoping info.
    if (!GV->isLocalToUnit())
      addFlag(*VariableDIE, dwarf::DW_AT_external);

    // Add line number info.
    addSourceLine(*VariableDIE, GV);
  }

  if (!GV->isDefinition())
    addFlag(*VariableDIE, dwarf::DW_AT_declaration);
  else
    addGlobalName(GV->getName(), *VariableDIE, DeclContext);

  if (uint32_t AlignInBytes = GV->getAlignInBytes())
    addUInt(*VariableDIE, dwarf::DW_AT_alignment, dwarf::DW_FORM_udata,
            AlignInBytes);

  if (MDTuple *TP = GV->getTemplateParams())
    addTemplateParams(*VariableDIE, DINodeArray(TP));

  // Add location.
  addLocationAttribute(VariableDIE, GV, GlobalExprs);

  return VariableDIE;
}

void DwarfCompileUnit::addLocationAttribute(
    DIE *VariableDIE, const DIGlobalVariable *GV, ArrayRef<GlobalExpr> GlobalExprs) {
  bool addToAccelTable = false;
  DIELoc *Loc = nullptr;
  Optional<unsigned> NVPTXAddressSpace;
  std::unique_ptr<DIEDwarfExpression> DwarfExpr;
  for (const auto &GE : GlobalExprs) {
    const GlobalVariable *Global = GE.Var;
    const DIExpression *Expr = GE.Expr;

    // For compatibility with DWARF 3 and earlier,
    // DW_AT_location(DW_OP_constu, X, DW_OP_stack_value) becomes
    // DW_AT_const_value(X).
    if (GlobalExprs.size() == 1 && Expr && Expr->isConstant()) {
      addToAccelTable = true;
      addConstantValue(*VariableDIE, /*Unsigned=*/true, Expr->getElement(1));
      break;
    }

    // We cannot describe the location of dllimport'd variables: the
    // computation of their address requires loads from the IAT.
    if (Global && Global->hasDLLImportStorageClass())
      continue;

    // Nothing to describe without address or constant.
    if (!Global && (!Expr || !Expr->isConstant()))
      continue;

    if (Global && Global->isThreadLocal() &&
        !Asm->getObjFileLowering().supportDebugThreadLocalLocation())
      continue;

    if (!Loc) {
      addToAccelTable = true;
      Loc = new (DIEValueAllocator) DIELoc;
      DwarfExpr = std::make_unique<DIEDwarfExpression>(*Asm, *this, *Loc);
    }

    if (Expr) {
      // According to
      // https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf
      // cuda-gdb requires DW_AT_address_class for all variables to be able to
      // correctly interpret address space of the variable address.
      // Decode DW_OP_constu <DWARF Address Space> DW_OP_swap DW_OP_xderef
      // sequence for the NVPTX + gdb target.
      unsigned LocalNVPTXAddressSpace;
      if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
        const DIExpression *NewExpr =
            DIExpression::extractAddressClass(Expr, LocalNVPTXAddressSpace);
        if (NewExpr != Expr) {
          Expr = NewExpr;
          NVPTXAddressSpace = LocalNVPTXAddressSpace;
        }
      }
      DwarfExpr->addFragmentOffset(Expr);
    }

    if (Global) {
      const MCSymbol *Sym = Asm->getSymbol(Global);
      if (Global->isThreadLocal()) {
        if (Asm->TM.useEmulatedTLS()) {
          // TODO: add debug info for emulated thread local mode.
        } else {
          // FIXME: Make this work with -gsplit-dwarf.
          unsigned PointerSize = Asm->getDataLayout().getPointerSize();
          assert((PointerSize == 4 || PointerSize == 8) &&
                 "Add support for other sizes if necessary");
          // Based on GCC's support for TLS:
          if (!DD->useSplitDwarf()) {
            // 1) Start with a constNu of the appropriate pointer size
            addUInt(*Loc, dwarf::DW_FORM_data1,
                    PointerSize == 4 ? dwarf::DW_OP_const4u
                                     : dwarf::DW_OP_const8u);
            // 2) containing the (relocated) offset of the TLS variable
            //    within the module's TLS block.
            addExpr(*Loc,
                    PointerSize == 4 ? dwarf::DW_FORM_data4
                                     : dwarf::DW_FORM_data8,
                    Asm->getObjFileLowering().getDebugThreadLocalSymbol(Sym));
          } else {
            addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_GNU_const_index);
            addUInt(*Loc, dwarf::DW_FORM_udata,
                    DD->getAddressPool().getIndex(Sym, /* TLS */ true));
          }
          // 3) followed by an OP to make the debugger do a TLS lookup.
          addUInt(*Loc, dwarf::DW_FORM_data1,
                  DD->useGNUTLSOpcode() ? dwarf::DW_OP_GNU_push_tls_address
                                        : dwarf::DW_OP_form_tls_address);
        }
      } else {
        DD->addArangeLabel(SymbolCU(this, Sym));
        addOpAddress(*Loc, Sym);
      }
    }
    // Global variables attached to symbols are memory locations.
    // It would be better if this were unconditional, but malformed input that
    // mixes non-fragments and fragments for the same variable is too expensive
    // to detect in the verifier.
    if (DwarfExpr->isUnknownLocation())
      DwarfExpr->setMemoryLocationKind();
    DwarfExpr->addExpression(Expr);
  }
  if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
    // According to
    // https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf
    // cuda-gdb requires DW_AT_address_class for all variables to be able to
    // correctly interpret address space of the variable address.
    const unsigned NVPTX_ADDR_global_space = 5;
    addUInt(*VariableDIE, dwarf::DW_AT_address_class, dwarf::DW_FORM_data1,
            NVPTXAddressSpace ? *NVPTXAddressSpace : NVPTX_ADDR_global_space);
  }
  if (Loc)
    addBlock(*VariableDIE, dwarf::DW_AT_location, DwarfExpr->finalize());

  if (DD->useAllLinkageNames())
    addLinkageName(*VariableDIE, GV->getLinkageName());

  if (addToAccelTable) {
    DD->addAccelName(*CUNode, GV->getName(), *VariableDIE);

    // If the linkage name is different than the name, go ahead and output
    // that as well into the name table.
    if (GV->getLinkageName() != "" && GV->getName() != GV->getLinkageName() &&
        DD->useAllLinkageNames())
      DD->addAccelName(*CUNode, GV->getLinkageName(), *VariableDIE);
  }
}

DIE *DwarfCompileUnit::getOrCreateCommonBlock(
    const DICommonBlock *CB, ArrayRef<GlobalExpr> GlobalExprs) {
  // Construct the context before querying for the existence of the DIE in case
  // such construction creates the DIE.
  DIE *ContextDIE = getOrCreateContextDIE(CB->getScope());

  if (DIE *NDie = getDIE(CB))
    return NDie;
  DIE &NDie = createAndAddDIE(dwarf::DW_TAG_common_block, *ContextDIE, CB);
  StringRef Name = CB->getName().empty() ? "_BLNK_" : CB->getName();
  addString(NDie, dwarf::DW_AT_name, Name);
  addGlobalName(Name, NDie, CB->getScope());
  if (CB->getFile())
    addSourceLine(NDie, CB->getLineNo(), CB->getFile());
  if (DIGlobalVariable *V = CB->getDecl())
    getCU().addLocationAttribute(&NDie, V, GlobalExprs);
  return &NDie;
}

void DwarfCompileUnit::addRange(RangeSpan Range) {
  DD->insertSectionLabel(Range.Begin);

  bool SameAsPrevCU = this == DD->getPrevCU();
  DD->setPrevCU(this);
  // If we have no current ranges just add the range and return, otherwise,
  // check the current section and CU against the previous section and CU we
  // emitted into and the subprogram was contained within. If these are the
  // same then extend our current range, otherwise add this as a new range.
  if (CURanges.empty() || !SameAsPrevCU ||
      (&CURanges.back().End->getSection() !=
       &Range.End->getSection())) {
    CURanges.push_back(Range);
    return;
  }

  CURanges.back().End = Range.End;
}

void DwarfCompileUnit::initStmtList() {
  if (CUNode->isDebugDirectivesOnly())
    return;

  const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
  if (DD->useSectionsAsReferences()) {
    LineTableStartSym = TLOF.getDwarfLineSection()->getBeginSymbol();
  } else {
    LineTableStartSym =
        Asm->OutStreamer->getDwarfLineTableSymbol(getUniqueID());
  }

  // DW_AT_stmt_list is a offset of line number information for this
  // compile unit in debug_line section. For split dwarf this is
  // left in the skeleton CU and so not included.
  // The line table entries are not always emitted in assembly, so it
  // is not okay to use line_table_start here.
      addSectionLabel(getUnitDie(), dwarf::DW_AT_stmt_list, LineTableStartSym,
                      TLOF.getDwarfLineSection()->getBeginSymbol());
}

void DwarfCompileUnit::applyStmtList(DIE &D) {
  const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
  addSectionLabel(D, dwarf::DW_AT_stmt_list, LineTableStartSym,
                  TLOF.getDwarfLineSection()->getBeginSymbol());
}

void DwarfCompileUnit::attachLowHighPC(DIE &D, const MCSymbol *Begin,
                                       const MCSymbol *End) {
  assert(Begin && "Begin label should not be null!");
  assert(End && "End label should not be null!");
  assert(Begin->isDefined() && "Invalid starting label");
  assert(End->isDefined() && "Invalid end label");

  addLabelAddress(D, dwarf::DW_AT_low_pc, Begin);
  if (DD->getDwarfVersion() < 4)
    addLabelAddress(D, dwarf::DW_AT_high_pc, End);
  else
    addLabelDelta(D, dwarf::DW_AT_high_pc, End, Begin);
}

// Find DIE for the given subprogram and attach appropriate DW_AT_low_pc
// and DW_AT_high_pc attributes. If there are global variables in this
// scope then create and insert DIEs for these variables.
DIE &DwarfCompileUnit::updateSubprogramScopeDIE(const DISubprogram *SP) {
  DIE *SPDie = getOrCreateSubprogramDIE(SP, includeMinimalInlineScopes());

  SmallVector<RangeSpan, 2> BB_List;
  // If basic block sections are on, ranges for each basic block section has
  // to be emitted separately.
  for (const auto &R : Asm->MBBSectionRanges)
    BB_List.push_back({R.second.BeginLabel, R.second.EndLabel});

  attachRangesOrLowHighPC(*SPDie, BB_List);

  if (DD->useAppleExtensionAttributes() &&
      !DD->getCurrentFunction()->getTarget().Options.DisableFramePointerElim(
          *DD->getCurrentFunction()))
    addFlag(*SPDie, dwarf::DW_AT_APPLE_omit_frame_ptr);

  // Only include DW_AT_frame_base in full debug info
  if (!includeMinimalInlineScopes()) {
    const TargetFrameLowering *TFI = Asm->MF->getSubtarget().getFrameLowering();
    TargetFrameLowering::DwarfFrameBase FrameBase =
        TFI->getDwarfFrameBase(*Asm->MF);
    switch (FrameBase.Kind) {
    case TargetFrameLowering::DwarfFrameBase::Register: {
      if (Register::isPhysicalRegister(FrameBase.Location.Reg)) {
        MachineLocation Location(FrameBase.Location.Reg);
        addAddress(*SPDie, dwarf::DW_AT_frame_base, Location);
      }
      break;
    }
    case TargetFrameLowering::DwarfFrameBase::CFA: {
      DIELoc *Loc = new (DIEValueAllocator) DIELoc;
      addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_call_frame_cfa);
      addBlock(*SPDie, dwarf::DW_AT_frame_base, Loc);
      break;
    }
    case TargetFrameLowering::DwarfFrameBase::WasmFrameBase: {
      // FIXME: duplicated from Target/WebAssembly/WebAssembly.h
      // don't want to depend on target specific headers in this code?
      const unsigned TI_GLOBAL_RELOC = 3;
      // FIXME: when writing dwo, we need to avoid relocations. Probably
      // the "right" solution is to treat globals the way func and data symbols
      // are (with entries in .debug_addr).
      if (FrameBase.Location.WasmLoc.Kind == TI_GLOBAL_RELOC && !isDwoUnit()) {
        // These need to be relocatable.
        assert(FrameBase.Location.WasmLoc.Index == 0);  // Only SP so far.
        auto SPSym = cast<MCSymbolWasm>(
          Asm->GetExternalSymbolSymbol("__stack_pointer"));
        // FIXME: this repeats what WebAssemblyMCInstLower::
        // GetExternalSymbolSymbol does, since if there's no code that
        // refers to this symbol, we have to set it here.
        SPSym->setType(wasm::WASM_SYMBOL_TYPE_GLOBAL);
        SPSym->setGlobalType(wasm::WasmGlobalType{
            uint8_t(Asm->getSubtargetInfo().getTargetTriple().getArch() ==
                            Triple::wasm64
                        ? wasm::WASM_TYPE_I64
                        : wasm::WASM_TYPE_I32),
            true});
        DIELoc *Loc = new (DIEValueAllocator) DIELoc;
        addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_WASM_location);
        addSInt(*Loc, dwarf::DW_FORM_sdata, TI_GLOBAL_RELOC);
        addLabel(*Loc, dwarf::DW_FORM_data4, SPSym);
        DD->addArangeLabel(SymbolCU(this, SPSym));
        addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_stack_value);
        addBlock(*SPDie, dwarf::DW_AT_frame_base, Loc);
      } else {
        DIELoc *Loc = new (DIEValueAllocator) DIELoc;
        DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
        DIExpressionCursor Cursor({});
        DwarfExpr.addWasmLocation(FrameBase.Location.WasmLoc.Kind,
            FrameBase.Location.WasmLoc.Index);
        DwarfExpr.addExpression(std::move(Cursor));
        addBlock(*SPDie, dwarf::DW_AT_frame_base, DwarfExpr.finalize());
      }
      break;
    }
    }
  }

  // Add name to the name table, we do this here because we're guaranteed
  // to have concrete versions of our DW_TAG_subprogram nodes.
  DD->addSubprogramNames(*CUNode, SP, *SPDie);

  return *SPDie;
}

// Construct a DIE for this scope.
void DwarfCompileUnit::constructScopeDIE(
    LexicalScope *Scope, SmallVectorImpl<DIE *> &FinalChildren) {
  if (!Scope || !Scope->getScopeNode())
    return;

  auto *DS = Scope->getScopeNode();

  assert((Scope->getInlinedAt() || !isa<DISubprogram>(DS)) &&
         "Only handle inlined subprograms here, use "
         "constructSubprogramScopeDIE for non-inlined "
         "subprograms");

  SmallVector<DIE *, 8> Children;

  // We try to create the scope DIE first, then the children DIEs. This will
  // avoid creating un-used children then removing them later when we find out
  // the scope DIE is null.
  DIE *ScopeDIE;
  if (Scope->getParent() && isa<DISubprogram>(DS)) {
    ScopeDIE = constructInlinedScopeDIE(Scope);
    if (!ScopeDIE)
      return;
    // We create children when the scope DIE is not null.
    createScopeChildrenDIE(Scope, Children);
  } else {
    // Early exit when we know the scope DIE is going to be null.
    if (DD->isLexicalScopeDIENull(Scope))
      return;

    bool HasNonScopeChildren = false;

    // We create children here when we know the scope DIE is not going to be
    // null and the children will be added to the scope DIE.
    createScopeChildrenDIE(Scope, Children, &HasNonScopeChildren);

    // If there are only other scopes as children, put them directly in the
    // parent instead, as this scope would serve no purpose.
    if (!HasNonScopeChildren) {
      FinalChildren.insert(FinalChildren.end(),
                           std::make_move_iterator(Children.begin()),
                           std::make_move_iterator(Children.end()));
      return;
    }
    ScopeDIE = constructLexicalScopeDIE(Scope);
    assert(ScopeDIE && "Scope DIE should not be null.");
  }

  // Add children
  for (auto &I : Children)
    ScopeDIE->addChild(std::move(I));

  FinalChildren.push_back(std::move(ScopeDIE));
}

void DwarfCompileUnit::addScopeRangeList(DIE &ScopeDIE,
                                         SmallVector<RangeSpan, 2> Range) {

  HasRangeLists = true;

  // Add the range list to the set of ranges to be emitted.
  auto IndexAndList =
      (DD->getDwarfVersion() < 5 && Skeleton ? Skeleton->DU : DU)
          ->addRange(*(Skeleton ? Skeleton : this), std::move(Range));

  uint32_t Index = IndexAndList.first;
  auto &List = *IndexAndList.second;

  // Under fission, ranges are specified by constant offsets relative to the
  // CU's DW_AT_GNU_ranges_base.
  // FIXME: For DWARF v5, do not generate the DW_AT_ranges attribute under
  // fission until we support the forms using the .debug_addr section
  // (DW_RLE_startx_endx etc.).
  if (DD->getDwarfVersion() >= 5)
    addUInt(ScopeDIE, dwarf::DW_AT_ranges, dwarf::DW_FORM_rnglistx, Index);
  else {
    const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
    const MCSymbol *RangeSectionSym =
        TLOF.getDwarfRangesSection()->getBeginSymbol();
    if (isDwoUnit())
      addSectionDelta(ScopeDIE, dwarf::DW_AT_ranges, List.Label,
                      RangeSectionSym);
    else
      addSectionLabel(ScopeDIE, dwarf::DW_AT_ranges, List.Label,
                      RangeSectionSym);
  }
}

void DwarfCompileUnit::attachRangesOrLowHighPC(
    DIE &Die, SmallVector<RangeSpan, 2> Ranges) {
  assert(!Ranges.empty());
  if (!DD->useRangesSection() ||
      (Ranges.size() == 1 &&
       (!DD->alwaysUseRanges() ||
        DD->getSectionLabel(&Ranges.front().Begin->getSection()) ==
            Ranges.front().Begin))) {
    const RangeSpan &Front = Ranges.front();
    const RangeSpan &Back = Ranges.back();
    attachLowHighPC(Die, Front.Begin, Back.End);
  } else
    addScopeRangeList(Die, std::move(Ranges));
}

void DwarfCompileUnit::attachRangesOrLowHighPC(
    DIE &Die, const SmallVectorImpl<InsnRange> &Ranges) {
  SmallVector<RangeSpan, 2> List;
  List.reserve(Ranges.size());
  for (const InsnRange &R : Ranges) {
    auto *BeginLabel = DD->getLabelBeforeInsn(R.first);
    auto *EndLabel = DD->getLabelAfterInsn(R.second);

    const auto *BeginMBB = R.first->getParent();
    const auto *EndMBB = R.second->getParent();

    const auto *MBB = BeginMBB;
    // Basic block sections allows basic block subsets to be placed in unique
    // sections. For each section, the begin and end label must be added to the
    // list. If there is more than one range, debug ranges must be used.
    // Otherwise, low/high PC can be used.
    // FIXME: Debug Info Emission depends on block order and this assumes that
    // the order of blocks will be frozen beyond this point.
    do {
      if (MBB->sameSection(EndMBB) || MBB->isEndSection()) {
        auto MBBSectionRange = Asm->MBBSectionRanges[MBB->getSectionIDNum()];
        List.push_back(
            {MBB->sameSection(BeginMBB) ? BeginLabel
                                        : MBBSectionRange.BeginLabel,
             MBB->sameSection(EndMBB) ? EndLabel : MBBSectionRange.EndLabel});
      }
      if (MBB->sameSection(EndMBB))
        break;
      MBB = MBB->getNextNode();
    } while (true);
  }
  attachRangesOrLowHighPC(Die, std::move(List));
}

// This scope represents inlined body of a function. Construct DIE to
// represent this concrete inlined copy of the function.
DIE *DwarfCompileUnit::constructInlinedScopeDIE(LexicalScope *Scope) {
  assert(Scope->getScopeNode());
  auto *DS = Scope->getScopeNode();
  auto *InlinedSP = getDISubprogram(DS);
  // Find the subprogram's DwarfCompileUnit in the SPMap in case the subprogram
  // was inlined from another compile unit.
  DIE *OriginDIE = getAbstractSPDies()[InlinedSP];
  assert(OriginDIE && "Unable to find original DIE for an inlined subprogram.");

  auto ScopeDIE = DIE::get(DIEValueAllocator, dwarf::DW_TAG_inlined_subroutine);
  addDIEEntry(*ScopeDIE, dwarf::DW_AT_abstract_origin, *OriginDIE);

  attachRangesOrLowHighPC(*ScopeDIE, Scope->getRanges());

  // Add the call site information to the DIE.
  const DILocation *IA = Scope->getInlinedAt();
  addUInt(*ScopeDIE, dwarf::DW_AT_call_file, None,
          getOrCreateSourceID(IA->getFile()));
  addUInt(*ScopeDIE, dwarf::DW_AT_call_line, None, IA->getLine());
  if (IA->getColumn())
    addUInt(*ScopeDIE, dwarf::DW_AT_call_column, None, IA->getColumn());
  if (IA->getDiscriminator() && DD->getDwarfVersion() >= 4)
    addUInt(*ScopeDIE, dwarf::DW_AT_GNU_discriminator, None,
            IA->getDiscriminator());

  // Add name to the name table, we do this here because we're guaranteed
  // to have concrete versions of our DW_TAG_inlined_subprogram nodes.
  DD->addSubprogramNames(*CUNode, InlinedSP, *ScopeDIE);

  return ScopeDIE;
}

// Construct new DW_TAG_lexical_block for this scope and attach
// DW_AT_low_pc/DW_AT_high_pc labels.
DIE *DwarfCompileUnit::constructLexicalScopeDIE(LexicalScope *Scope) {
  if (DD->isLexicalScopeDIENull(Scope))
    return nullptr;

  auto ScopeDIE = DIE::get(DIEValueAllocator, dwarf::DW_TAG_lexical_block);
  if (Scope->isAbstractScope())
    return ScopeDIE;

  attachRangesOrLowHighPC(*ScopeDIE, Scope->getRanges());

  return ScopeDIE;
}

/// constructVariableDIE - Construct a DIE for the given DbgVariable.
DIE *DwarfCompileUnit::constructVariableDIE(DbgVariable &DV, bool Abstract) {
  auto D = constructVariableDIEImpl(DV, Abstract);
  DV.setDIE(*D);
  return D;
}

DIE *DwarfCompileUnit::constructLabelDIE(DbgLabel &DL,
                                         const LexicalScope &Scope) {
  auto LabelDie = DIE::get(DIEValueAllocator, DL.getTag());
  insertDIE(DL.getLabel(), LabelDie);
  DL.setDIE(*LabelDie);

  if (Scope.isAbstractScope())
    applyLabelAttributes(DL, *LabelDie);

  return LabelDie;
}

DIE *DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
                                                bool Abstract) {
  // Define variable debug information entry.
  auto VariableDie = DIE::get(DIEValueAllocator, DV.getTag());
  insertDIE(DV.getVariable(), VariableDie);

  if (Abstract) {
    applyVariableAttributes(DV, *VariableDie);
    return VariableDie;
  }

  // Add variable address.

  unsigned Index = DV.getDebugLocListIndex();
  if (Index != ~0U) {
    addLocationList(*VariableDie, dwarf::DW_AT_location, Index);
    auto TagOffset = DV.getDebugLocListTagOffset();
    if (TagOffset)
      addUInt(*VariableDie, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
              *TagOffset);
    return VariableDie;
  }

  // Check if variable has a single location description.
  if (auto *DVal = DV.getValueLoc()) {
    if (DVal->isLocation())
      addVariableAddress(DV, *VariableDie, DVal->getLoc());
    else if (DVal->isInt()) {
      auto *Expr = DV.getSingleExpression();
      if (Expr && Expr->getNumElements()) {
        DIELoc *Loc = new (DIEValueAllocator) DIELoc;
        DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
        // If there is an expression, emit raw unsigned bytes.
        DwarfExpr.addFragmentOffset(Expr);
        DwarfExpr.addUnsignedConstant(DVal->getInt());
        DwarfExpr.addExpression(Expr);
        addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
        if (DwarfExpr.TagOffset)
          addUInt(*VariableDie, dwarf::DW_AT_LLVM_tag_offset,
                  dwarf::DW_FORM_data1, *DwarfExpr.TagOffset);

      } else
        addConstantValue(*VariableDie, DVal->getInt(), DV.getType());
    } else if (DVal->isConstantFP()) {
      addConstantFPValue(*VariableDie, DVal->getConstantFP());
    } else if (DVal->isConstantInt()) {
      addConstantValue(*VariableDie, DVal->getConstantInt(), DV.getType());
    } else if (DVal->isTargetIndexLocation()) {
      DIELoc *Loc = new (DIEValueAllocator) DIELoc;
      DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
      const DIBasicType *BT = dyn_cast<DIBasicType>(
          static_cast<const Metadata *>(DV.getVariable()->getType()));
      DwarfDebug::emitDebugLocValue(*Asm, BT, *DVal, DwarfExpr);
      addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
    }
    return VariableDie;
  }

  // .. else use frame index.
  if (!DV.hasFrameIndexExprs())
    return VariableDie;

  Optional<unsigned> NVPTXAddressSpace;
  DIELoc *Loc = new (DIEValueAllocator) DIELoc;
  DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
  for (auto &Fragment : DV.getFrameIndexExprs()) {
    Register FrameReg;
    const DIExpression *Expr = Fragment.Expr;
    const TargetFrameLowering *TFI = Asm->MF->getSubtarget().getFrameLowering();
    StackOffset Offset =
        TFI->getFrameIndexReference(*Asm->MF, Fragment.FI, FrameReg);
    DwarfExpr.addFragmentOffset(Expr);

    auto *TRI = Asm->MF->getSubtarget().getRegisterInfo();
    SmallVector<uint64_t, 8> Ops;
    TRI->getOffsetOpcodes(Offset, Ops);

    // According to
    // https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf
    // cuda-gdb requires DW_AT_address_class for all variables to be able to
    // correctly interpret address space of the variable address.
    // Decode DW_OP_constu <DWARF Address Space> DW_OP_swap DW_OP_xderef
    // sequence for the NVPTX + gdb target.
    unsigned LocalNVPTXAddressSpace;
    if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
      const DIExpression *NewExpr =
          DIExpression::extractAddressClass(Expr, LocalNVPTXAddressSpace);
      if (NewExpr != Expr) {
        Expr = NewExpr;
        NVPTXAddressSpace = LocalNVPTXAddressSpace;
      }
    }
    if (Expr)
      Ops.append(Expr->elements_begin(), Expr->elements_end());
    DIExpressionCursor Cursor(Ops);
    DwarfExpr.setMemoryLocationKind();
    if (const MCSymbol *FrameSymbol = Asm->getFunctionFrameSymbol())
      addOpAddress(*Loc, FrameSymbol);
    else
      DwarfExpr.addMachineRegExpression(
          *Asm->MF->getSubtarget().getRegisterInfo(), Cursor, FrameReg);
    DwarfExpr.addExpression(std::move(Cursor));
  }
  if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
    // According to
    // https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf
    // cuda-gdb requires DW_AT_address_class for all variables to be able to
    // correctly interpret address space of the variable address.
    const unsigned NVPTX_ADDR_local_space = 6;
    addUInt(*VariableDie, dwarf::DW_AT_address_class, dwarf::DW_FORM_data1,
            NVPTXAddressSpace ? *NVPTXAddressSpace : NVPTX_ADDR_local_space);
  }
  addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
  if (DwarfExpr.TagOffset)
    addUInt(*VariableDie, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
            *DwarfExpr.TagOffset);

  return VariableDie;
}

DIE *DwarfCompileUnit::constructVariableDIE(DbgVariable &DV,
                                            const LexicalScope &Scope,
                                            DIE *&ObjectPointer) {
  auto Var = constructVariableDIE(DV, Scope.isAbstractScope());
  if (DV.isObjectPointer())
    ObjectPointer = Var;
  return Var;
}

/// Return all DIVariables that appear in count: expressions.
static SmallVector<const DIVariable *, 2> dependencies(DbgVariable *Var) {
  SmallVector<const DIVariable *, 2> Result;
  auto *Array = dyn_cast<DICompositeType>(Var->getType());
  if (!Array || Array->getTag() != dwarf::DW_TAG_array_type)
    return Result;
  if (auto *DLVar = Array->getDataLocation())
    Result.push_back(DLVar);
  if (auto *AsVar = Array->getAssociated())
    Result.push_back(AsVar);
  if (auto *AlVar = Array->getAllocated())
    Result.push_back(AlVar);
  for (auto *El : Array->getElements()) {
    if (auto *Subrange = dyn_cast<DISubrange>(El)) {
      if (auto Count = Subrange->getCount())
        if (auto *Dependency = Count.dyn_cast<DIVariable *>())
          Result.push_back(Dependency);
      if (auto LB = Subrange->getLowerBound())
        if (auto *Dependency = LB.dyn_cast<DIVariable *>())
          Result.push_back(Dependency);
      if (auto UB = Subrange->getUpperBound())
        if (auto *Dependency = UB.dyn_cast<DIVariable *>())
          Result.push_back(Dependency);
      if (auto ST = Subrange->getStride())
        if (auto *Dependency = ST.dyn_cast<DIVariable *>())
          Result.push_back(Dependency);
    } else if (auto *GenericSubrange = dyn_cast<DIGenericSubrange>(El)) {
      if (auto Count = GenericSubrange->getCount())
        if (auto *Dependency = Count.dyn_cast<DIVariable *>())
          Result.push_back(Dependency);
      if (auto LB = GenericSubrange->getLowerBound())
        if (auto *Dependency = LB.dyn_cast<DIVariable *>())
          Result.push_back(Dependency);
      if (auto UB = GenericSubrange->getUpperBound())
        if (auto *Dependency = UB.dyn_cast<DIVariable *>())
          Result.push_back(Dependency);
      if (auto ST = GenericSubrange->getStride())
        if (auto *Dependency = ST.dyn_cast<DIVariable *>())
          Result.push_back(Dependency);
    }
  }
  return Result;
}

/// Sort local variables so that variables appearing inside of helper
/// expressions come first.
static SmallVector<DbgVariable *, 8>
sortLocalVars(SmallVectorImpl<DbgVariable *> &Input) {
  SmallVector<DbgVariable *, 8> Result;
  SmallVector<PointerIntPair<DbgVariable *, 1>, 8> WorkList;
  // Map back from a DIVariable to its containing DbgVariable.
  SmallDenseMap<const DILocalVariable *, DbgVariable *> DbgVar;
  // Set of DbgVariables in Result.
  SmallDenseSet<DbgVariable *, 8> Visited;
  // For cycle detection.
  SmallDenseSet<DbgVariable *, 8> Visiting;

  // Initialize the worklist and the DIVariable lookup table.
  for (auto Var : reverse(Input)) {
    DbgVar.insert({Var->getVariable(), Var});
    WorkList.push_back({Var, 0});
  }

  // Perform a stable topological sort by doing a DFS.
  while (!WorkList.empty()) {
    auto Item = WorkList.back();
    DbgVariable *Var = Item.getPointer();
    bool visitedAllDependencies = Item.getInt();
    WorkList.pop_back();

    // Dependency is in a different lexical scope or a global.
    if (!Var)
      continue;

    // Already handled.
    if (Visited.count(Var))
      continue;

    // Add to Result if all dependencies are visited.
    if (visitedAllDependencies) {
      Visited.insert(Var);
      Result.push_back(Var);
      continue;
    }

    // Detect cycles.
    auto Res = Visiting.insert(Var);
    if (!Res.second) {
      assert(false && "dependency cycle in local variables");
      return Result;
    }

    // Push dependencies and this node onto the worklist, so that this node is
    // visited again after all of its dependencies are handled.
    WorkList.push_back({Var, 1});
    for (auto *Dependency : dependencies(Var)) {
      auto Dep = dyn_cast_or_null<const DILocalVariable>(Dependency);
      WorkList.push_back({DbgVar[Dep], 0});
    }
  }
  return Result;
}

DIE *DwarfCompileUnit::createScopeChildrenDIE(LexicalScope *Scope,
                                              SmallVectorImpl<DIE *> &Children,
                                              bool *HasNonScopeChildren) {
  assert(Children.empty());
  DIE *ObjectPointer = nullptr;

  // Emit function arguments (order is significant).
  auto Vars = DU->getScopeVariables().lookup(Scope);
  for (auto &DV : Vars.Args)
    Children.push_back(constructVariableDIE(*DV.second, *Scope, ObjectPointer));

  // Emit local variables.
  auto Locals = sortLocalVars(Vars.Locals);
  for (DbgVariable *DV : Locals)
    Children.push_back(constructVariableDIE(*DV, *Scope, ObjectPointer));

  // Skip imported directives in gmlt-like data.
  if (!includeMinimalInlineScopes()) {
    // There is no need to emit empty lexical block DIE.
    for (const auto *IE : ImportedEntities[Scope->getScopeNode()])
      Children.push_back(
          constructImportedEntityDIE(cast<DIImportedEntity>(IE)));
  }

  if (HasNonScopeChildren)
    *HasNonScopeChildren = !Children.empty();

  for (DbgLabel *DL : DU->getScopeLabels().lookup(Scope))
    Children.push_back(constructLabelDIE(*DL, *Scope));

  for (LexicalScope *LS : Scope->getChildren())
    constructScopeDIE(LS, Children);

  return ObjectPointer;
}

DIE &DwarfCompileUnit::constructSubprogramScopeDIE(const DISubprogram *Sub,
                                                   LexicalScope *Scope) {
  DIE &ScopeDIE = updateSubprogramScopeDIE(Sub);

  if (Scope) {
    assert(!Scope->getInlinedAt());
    assert(!Scope->isAbstractScope());
    // Collect lexical scope children first.
    // ObjectPointer might be a local (non-argument) local variable if it's a
    // block's synthetic this pointer.
    if (DIE *ObjectPointer = createAndAddScopeChildren(Scope, ScopeDIE))
      addDIEEntry(ScopeDIE, dwarf::DW_AT_object_pointer, *ObjectPointer);
  }

  // If this is a variadic function, add an unspecified parameter.
  DITypeRefArray FnArgs = Sub->getType()->getTypeArray();

  // If we have a single element of null, it is a function that returns void.
  // If we have more than one elements and the last one is null, it is a
  // variadic function.
  if (FnArgs.size() > 1 && !FnArgs[FnArgs.size() - 1] &&
      !includeMinimalInlineScopes())
    ScopeDIE.addChild(
        DIE::get(DIEValueAllocator, dwarf::DW_TAG_unspecified_parameters));

  return ScopeDIE;
}

DIE *DwarfCompileUnit::createAndAddScopeChildren(LexicalScope *Scope,
                                                 DIE &ScopeDIE) {
  // We create children when the scope DIE is not null.
  SmallVector<DIE *, 8> Children;
  DIE *ObjectPointer = createScopeChildrenDIE(Scope, Children);

  // Add children
  for (auto &I : Children)
    ScopeDIE.addChild(std::move(I));

  return ObjectPointer;
}

void DwarfCompileUnit::constructAbstractSubprogramScopeDIE(
    LexicalScope *Scope) {
  DIE *&AbsDef = getAbstractSPDies()[Scope->getScopeNode()];
  if (AbsDef)
    return;

  auto *SP = cast<DISubprogram>(Scope->getScopeNode());

  DIE *ContextDIE;
  DwarfCompileUnit *ContextCU = this;

  if (includeMinimalInlineScopes())
    ContextDIE = &getUnitDie();
  // Some of this is duplicated from DwarfUnit::getOrCreateSubprogramDIE, with
  // the important distinction that the debug node is not associated with the
  // DIE (since the debug node will be associated with the concrete DIE, if
  // any). It could be refactored to some common utility function.
  else if (auto *SPDecl = SP->getDeclaration()) {
    ContextDIE = &getUnitDie();
    getOrCreateSubprogramDIE(SPDecl);
  } else {
    ContextDIE = getOrCreateContextDIE(SP->getScope());
    // The scope may be shared with a subprogram that has already been
    // constructed in another CU, in which case we need to construct this
    // subprogram in the same CU.
    ContextCU = DD->lookupCU(ContextDIE->getUnitDie());
  }

  // Passing null as the associated node because the abstract definition
  // shouldn't be found by lookup.
  AbsDef = &ContextCU->createAndAddDIE(dwarf::DW_TAG_subprogram, *ContextDIE, nullptr);
  ContextCU->applySubprogramAttributesToDefinition(SP, *AbsDef);

  if (!ContextCU->includeMinimalInlineScopes())
    ContextCU->addUInt(*AbsDef, dwarf::DW_AT_inline, None, dwarf::DW_INL_inlined);
  if (DIE *ObjectPointer = ContextCU->createAndAddScopeChildren(Scope, *AbsDef))
    ContextCU->addDIEEntry(*AbsDef, dwarf::DW_AT_object_pointer, *ObjectPointer);
}

bool DwarfCompileUnit::useGNUAnalogForDwarf5Feature() const {
  return DD->getDwarfVersion() == 4 && !DD->tuneForLLDB();
}

dwarf::Tag DwarfCompileUnit::getDwarf5OrGNUTag(dwarf::Tag Tag) const {
  if (!useGNUAnalogForDwarf5Feature())
    return Tag;
  switch (Tag) {
  case dwarf::DW_TAG_call_site:
    return dwarf::DW_TAG_GNU_call_site;
  case dwarf::DW_TAG_call_site_parameter:
    return dwarf::DW_TAG_GNU_call_site_parameter;
  default:
    llvm_unreachable("DWARF5 tag with no GNU analog");
  }
}

dwarf::Attribute
DwarfCompileUnit::getDwarf5OrGNUAttr(dwarf::Attribute Attr) const {
  if (!useGNUAnalogForDwarf5Feature())
    return Attr;
  switch (Attr) {
  case dwarf::DW_AT_call_all_calls:
    return dwarf::DW_AT_GNU_all_call_sites;
  case dwarf::DW_AT_call_target:
    return dwarf::DW_AT_GNU_call_site_target;
  case dwarf::DW_AT_call_origin:
    return dwarf::DW_AT_abstract_origin;
  case dwarf::DW_AT_call_return_pc:
    return dwarf::DW_AT_low_pc;
  case dwarf::DW_AT_call_value:
    return dwarf::DW_AT_GNU_call_site_value;
  case dwarf::DW_AT_call_tail_call:
    return dwarf::DW_AT_GNU_tail_call;
  default:
    llvm_unreachable("DWARF5 attribute with no GNU analog");
  }
}

dwarf::LocationAtom
DwarfCompileUnit::getDwarf5OrGNULocationAtom(dwarf::LocationAtom Loc) const {
  if (!useGNUAnalogForDwarf5Feature())
    return Loc;
  switch (Loc) {
  case dwarf::DW_OP_entry_value:
    return dwarf::DW_OP_GNU_entry_value;
  default:
    llvm_unreachable("DWARF5 location atom with no GNU analog");
  }
}

DIE &DwarfCompileUnit::constructCallSiteEntryDIE(DIE &ScopeDIE,
                                                 DIE *CalleeDIE,
                                                 bool IsTail,
                                                 const MCSymbol *PCAddr,
                                                 const MCSymbol *CallAddr,
                                                 unsigned CallReg) {
  // Insert a call site entry DIE within ScopeDIE.
  DIE &CallSiteDIE = createAndAddDIE(getDwarf5OrGNUTag(dwarf::DW_TAG_call_site),
                                     ScopeDIE, nullptr);

  if (CallReg) {
    // Indirect call.
    addAddress(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_target),
               MachineLocation(CallReg));
  } else {
    assert(CalleeDIE && "No DIE for call site entry origin");
    addDIEEntry(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_origin),
                *CalleeDIE);
  }

  if (IsTail) {
    // Attach DW_AT_call_tail_call to tail calls for standards compliance.
    addFlag(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_tail_call));

    // Attach the address of the branch instruction to allow the debugger to
    // show where the tail call occurred. This attribute has no GNU analog.
    //
    // GDB works backwards from non-standard usage of DW_AT_low_pc (in DWARF4
    // mode -- equivalently, in DWARF5 mode, DW_AT_call_return_pc) at tail-call
    // site entries to figure out the PC of tail-calling branch instructions.
    // This means it doesn't need the compiler to emit DW_AT_call_pc, so we
    // don't emit it here.
    //
    // There's no need to tie non-GDB debuggers to this non-standardness, as it
    // adds unnecessary complexity to the debugger. For non-GDB debuggers, emit
    // the standard DW_AT_call_pc info.
    if (!useGNUAnalogForDwarf5Feature())
      addLabelAddress(CallSiteDIE, dwarf::DW_AT_call_pc, CallAddr);
  }

  // Attach the return PC to allow the debugger to disambiguate call paths
  // from one function to another.
  //
  // The return PC is only really needed when the call /isn't/ a tail call, but
  // GDB expects it in DWARF4 mode, even for tail calls (see the comment above
  // the DW_AT_call_pc emission logic for an explanation).
  if (!IsTail || useGNUAnalogForDwarf5Feature()) {
    assert(PCAddr && "Missing return PC information for a call");
    addLabelAddress(CallSiteDIE,
                    getDwarf5OrGNUAttr(dwarf::DW_AT_call_return_pc), PCAddr);
  }

  return CallSiteDIE;
}

void DwarfCompileUnit::constructCallSiteParmEntryDIEs(
    DIE &CallSiteDIE, SmallVector<DbgCallSiteParam, 4> &Params) {
  for (const auto &Param : Params) {
    unsigned Register = Param.getRegister();
    auto CallSiteDieParam =
        DIE::get(DIEValueAllocator,
                 getDwarf5OrGNUTag(dwarf::DW_TAG_call_site_parameter));
    insertDIE(CallSiteDieParam);
    addAddress(*CallSiteDieParam, dwarf::DW_AT_location,
               MachineLocation(Register));

    DIELoc *Loc = new (DIEValueAllocator) DIELoc;
    DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
    DwarfExpr.setCallSiteParamValueFlag();

    DwarfDebug::emitDebugLocValue(*Asm, nullptr, Param.getValue(), DwarfExpr);

    addBlock(*CallSiteDieParam, getDwarf5OrGNUAttr(dwarf::DW_AT_call_value),
             DwarfExpr.finalize());

    CallSiteDIE.addChild(CallSiteDieParam);
  }
}

DIE *DwarfCompileUnit::constructImportedEntityDIE(
    const DIImportedEntity *Module) {
  DIE *IMDie = DIE::get(DIEValueAllocator, (dwarf::Tag)Module->getTag());
  insertDIE(Module, IMDie);
  DIE *EntityDie;
  auto *Entity = Module->getEntity();
  if (auto *NS = dyn_cast<DINamespace>(Entity))
    EntityDie = getOrCreateNameSpace(NS);
  else if (auto *M = dyn_cast<DIModule>(Entity))
    EntityDie = getOrCreateModule(M);
  else if (auto *SP = dyn_cast<DISubprogram>(Entity))
    EntityDie = getOrCreateSubprogramDIE(SP);
  else if (auto *T = dyn_cast<DIType>(Entity))
    EntityDie = getOrCreateTypeDIE(T);
  else if (auto *GV = dyn_cast<DIGlobalVariable>(Entity))
    EntityDie = getOrCreateGlobalVariableDIE(GV, {});
  else
    EntityDie = getDIE(Entity);
  assert(EntityDie);
  addSourceLine(*IMDie, Module->getLine(), Module->getFile());
  addDIEEntry(*IMDie, dwarf::DW_AT_import, *EntityDie);
  StringRef Name = Module->getName();
  if (!Name.empty())
    addString(*IMDie, dwarf::DW_AT_name, Name);

  return IMDie;
}

void DwarfCompileUnit::finishSubprogramDefinition(const DISubprogram *SP) {
  DIE *D = getDIE(SP);
  if (DIE *AbsSPDIE = getAbstractSPDies().lookup(SP)) {
    if (D)
      // If this subprogram has an abstract definition, reference that
      addDIEEntry(*D, dwarf::DW_AT_abstract_origin, *AbsSPDIE);
  } else {
    assert(D || includeMinimalInlineScopes());
    if (D)
      // And attach the attributes
      applySubprogramAttributesToDefinition(SP, *D);
  }
}

void DwarfCompileUnit::finishEntityDefinition(const DbgEntity *Entity) {
  DbgEntity *AbsEntity = getExistingAbstractEntity(Entity->getEntity());

  auto *Die = Entity->getDIE();
  /// Label may be used to generate DW_AT_low_pc, so put it outside
  /// if/else block.
  const DbgLabel *Label = nullptr;
  if (AbsEntity && AbsEntity->getDIE()) {
    addDIEEntry(*Die, dwarf::DW_AT_abstract_origin, *AbsEntity->getDIE());
    Label = dyn_cast<const DbgLabel>(Entity);
  } else {
    if (const DbgVariable *Var = dyn_cast<const DbgVariable>(Entity))
      applyVariableAttributes(*Var, *Die);
    else if ((Label = dyn_cast<const DbgLabel>(Entity)))
      applyLabelAttributes(*Label, *Die);
    else
      llvm_unreachable("DbgEntity must be DbgVariable or DbgLabel.");
  }

  if (Label)
    if (const auto *Sym = Label->getSymbol())
      addLabelAddress(*Die, dwarf::DW_AT_low_pc, Sym);
}

DbgEntity *DwarfCompileUnit::getExistingAbstractEntity(const DINode *Node) {
  auto &AbstractEntities = getAbstractEntities();
  auto I = AbstractEntities.find(Node);
  if (I != AbstractEntities.end())
    return I->second.get();
  return nullptr;
}

void DwarfCompileUnit::createAbstractEntity(const DINode *Node,
                                            LexicalScope *Scope) {
  assert(Scope && Scope->isAbstractScope());
  auto &Entity = getAbstractEntities()[Node];
  if (isa<const DILocalVariable>(Node)) {
    Entity = std::make_unique<DbgVariable>(
                        cast<const DILocalVariable>(Node), nullptr /* IA */);;
    DU->addScopeVariable(Scope, cast<DbgVariable>(Entity.get()));
  } else if (isa<const DILabel>(Node)) {
    Entity = std::make_unique<DbgLabel>(
                        cast<const DILabel>(Node), nullptr /* IA */);
    DU->addScopeLabel(Scope, cast<DbgLabel>(Entity.get()));
  }
}

void DwarfCompileUnit::emitHeader(bool UseOffsets) {
  // Don't bother labeling the .dwo unit, as its offset isn't used.
  if (!Skeleton && !DD->useSectionsAsReferences()) {
    LabelBegin = Asm->createTempSymbol("cu_begin");
    Asm->OutStreamer->emitLabel(LabelBegin);
  }

  dwarf::UnitType UT = Skeleton ? dwarf::DW_UT_split_compile
                                : DD->useSplitDwarf() ? dwarf::DW_UT_skeleton
                                                      : dwarf::DW_UT_compile;
  DwarfUnit::emitCommonHeader(UseOffsets, UT);
  if (DD->getDwarfVersion() >= 5 && UT != dwarf::DW_UT_compile)
    Asm->emitInt64(getDWOId());
}

bool DwarfCompileUnit::hasDwarfPubSections() const {
  switch (CUNode->getNameTableKind()) {
  case DICompileUnit::DebugNameTableKind::None:
    return false;
    // Opting in to GNU Pubnames/types overrides the default to ensure these are
    // generated for things like Gold's gdb_index generation.
  case DICompileUnit::DebugNameTableKind::GNU:
    return true;
  case DICompileUnit::DebugNameTableKind::Default:
    return DD->tuneForGDB() && !includeMinimalInlineScopes() &&
           !CUNode->isDebugDirectivesOnly() &&
           DD->getAccelTableKind() != AccelTableKind::Apple &&
           DD->getDwarfVersion() < 5;
  }
  llvm_unreachable("Unhandled DICompileUnit::DebugNameTableKind enum");
}

/// addGlobalName - Add a new global name to the compile unit.
void DwarfCompileUnit::addGlobalName(StringRef Name, const DIE &Die,
                                     const DIScope *Context) {
  if (!hasDwarfPubSections())
    return;
  std::string FullName = getParentContextString(Context) + Name.str();
  GlobalNames[FullName] = &Die;
}

void DwarfCompileUnit::addGlobalNameForTypeUnit(StringRef Name,
                                                const DIScope *Context) {
  if (!hasDwarfPubSections())
    return;
  std::string FullName = getParentContextString(Context) + Name.str();
  // Insert, allowing the entry to remain as-is if it's already present
  // This way the CU-level type DIE is preferred over the "can't describe this
  // type as a unit offset because it's not really in the CU at all, it's only
  // in a type unit"
  GlobalNames.insert(std::make_pair(std::move(FullName), &getUnitDie()));
}

/// Add a new global type to the unit.
void DwarfCompileUnit::addGlobalType(const DIType *Ty, const DIE &Die,
                                     const DIScope *Context) {
  if (!hasDwarfPubSections())
    return;
  std::string FullName = getParentContextString(Context) + Ty->getName().str();
  GlobalTypes[FullName] = &Die;
}

void DwarfCompileUnit::addGlobalTypeUnitType(const DIType *Ty,
                                             const DIScope *Context) {
  if (!hasDwarfPubSections())
    return;
  std::string FullName = getParentContextString(Context) + Ty->getName().str();
  // Insert, allowing the entry to remain as-is if it's already present
  // This way the CU-level type DIE is preferred over the "can't describe this
  // type as a unit offset because it's not really in the CU at all, it's only
  // in a type unit"
  GlobalTypes.insert(std::make_pair(std::move(FullName), &getUnitDie()));
}

void DwarfCompileUnit::addVariableAddress(const DbgVariable &DV, DIE &Die,
                                          MachineLocation Location) {
  if (DV.hasComplexAddress())
    addComplexAddress(DV, Die, dwarf::DW_AT_location, Location);
  else
    addAddress(Die, dwarf::DW_AT_location, Location);
}

/// Add an address attribute to a die based on the location provided.
void DwarfCompileUnit::addAddress(DIE &Die, dwarf::Attribute Attribute,
                                  const MachineLocation &Location) {
  DIELoc *Loc = new (DIEValueAllocator) DIELoc;
  DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
  if (Location.isIndirect())
    DwarfExpr.setMemoryLocationKind();

  DIExpressionCursor Cursor({});
  const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
  if (!DwarfExpr.addMachineRegExpression(TRI, Cursor, Location.getReg()))
    return;
  DwarfExpr.addExpression(std::move(Cursor));

  // Now attach the location information to the DIE.
  addBlock(Die, Attribute, DwarfExpr.finalize());

  if (DwarfExpr.TagOffset)
    addUInt(Die, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
            *DwarfExpr.TagOffset);
}

/// Start with the address based on the location provided, and generate the
/// DWARF information necessary to find the actual variable given the extra
/// address information encoded in the DbgVariable, starting from the starting
/// location.  Add the DWARF information to the die.
void DwarfCompileUnit::addComplexAddress(const DbgVariable &DV, DIE &Die,
                                         dwarf::Attribute Attribute,
                                         const MachineLocation &Location) {
  DIELoc *Loc = new (DIEValueAllocator) DIELoc;
  DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
  const DIExpression *DIExpr = DV.getSingleExpression();
  DwarfExpr.addFragmentOffset(DIExpr);
  DwarfExpr.setLocation(Location, DIExpr);

  DIExpressionCursor Cursor(DIExpr);

  if (DIExpr->isEntryValue())
    DwarfExpr.beginEntryValueExpression(Cursor);

  const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
  if (!DwarfExpr.addMachineRegExpression(TRI, Cursor, Location.getReg()))
    return;
  DwarfExpr.addExpression(std::move(Cursor));

  // Now attach the location information to the DIE.
  addBlock(Die, Attribute, DwarfExpr.finalize());

  if (DwarfExpr.TagOffset)
    addUInt(Die, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
            *DwarfExpr.TagOffset);
}

/// Add a Dwarf loclistptr attribute data and value.
void DwarfCompileUnit::addLocationList(DIE &Die, dwarf::Attribute Attribute,
                                       unsigned Index) {
  dwarf::Form Form = (DD->getDwarfVersion() >= 5)
                         ? dwarf::DW_FORM_loclistx
                         : DD->getDwarfSectionOffsetForm();
  Die.addValue(DIEValueAllocator, Attribute, Form, DIELocList(Index));
}

void DwarfCompileUnit::applyVariableAttributes(const DbgVariable &Var,
                                               DIE &VariableDie) {
  StringRef Name = Var.getName();
  if (!Name.empty())
    addString(VariableDie, dwarf::DW_AT_name, Name);
  const auto *DIVar = Var.getVariable();
  if (DIVar)
    if (uint32_t AlignInBytes = DIVar->getAlignInBytes())
      addUInt(VariableDie, dwarf::DW_AT_alignment, dwarf::DW_FORM_udata,
              AlignInBytes);

  addSourceLine(VariableDie, DIVar);
  addType(VariableDie, Var.getType());
  if (Var.isArtificial())
    addFlag(VariableDie, dwarf::DW_AT_artificial);
}

void DwarfCompileUnit::applyLabelAttributes(const DbgLabel &Label,
                                            DIE &LabelDie) {
  StringRef Name = Label.getName();
  if (!Name.empty())
    addString(LabelDie, dwarf::DW_AT_name, Name);
  const auto *DILabel = Label.getLabel();
  addSourceLine(LabelDie, DILabel);
}

/// Add a Dwarf expression attribute data and value.
void DwarfCompileUnit::addExpr(DIELoc &Die, dwarf::Form Form,
                               const MCExpr *Expr) {
  Die.addValue(DIEValueAllocator, (dwarf::Attribute)0, Form, DIEExpr(Expr));
}

void DwarfCompileUnit::applySubprogramAttributesToDefinition(
    const DISubprogram *SP, DIE &SPDie) {
  auto *SPDecl = SP->getDeclaration();
  auto *Context = SPDecl ? SPDecl->getScope() : SP->getScope();
  applySubprogramAttributes(SP, SPDie, includeMinimalInlineScopes());
  addGlobalName(SP->getName(), SPDie, Context);
}

bool DwarfCompileUnit::isDwoUnit() const {
  return DD->useSplitDwarf() && Skeleton;
}

void DwarfCompileUnit::finishNonUnitTypeDIE(DIE& D, const DICompositeType *CTy) {
  constructTypeDIE(D, CTy);
}

bool DwarfCompileUnit::includeMinimalInlineScopes() const {
  return getCUNode()->getEmissionKind() == DICompileUnit::LineTablesOnly ||
         (DD->useSplitDwarf() && !Skeleton);
}

void DwarfCompileUnit::addAddrTableBase() {
  const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
  MCSymbol *Label = DD->getAddressPool().getLabel();
  addSectionLabel(getUnitDie(),
                  DD->getDwarfVersion() >= 5 ? dwarf::DW_AT_addr_base
                                             : dwarf::DW_AT_GNU_addr_base,
                  Label, TLOF.getDwarfAddrSection()->getBeginSymbol());
}

void DwarfCompileUnit::addBaseTypeRef(DIEValueList &Die, int64_t Idx) {
  Die.addValue(DIEValueAllocator, (dwarf::Attribute)0, dwarf::DW_FORM_udata,
               new (DIEValueAllocator) DIEBaseTypeRef(this, Idx));
}

void DwarfCompileUnit::createBaseTypeDIEs() {
  // Insert the base_type DIEs directly after the CU so that their offsets will
  // fit in the fixed size ULEB128 used inside the location expressions.
  // Maintain order by iterating backwards and inserting to the front of CU
  // child list.
  for (auto &Btr : reverse(ExprRefedBaseTypes)) {
    DIE &Die = getUnitDie().addChildFront(
      DIE::get(DIEValueAllocator, dwarf::DW_TAG_base_type));
    SmallString<32> Str;
    addString(Die, dwarf::DW_AT_name,
              Twine(dwarf::AttributeEncodingString(Btr.Encoding) +
                    "_" + Twine(Btr.BitSize)).toStringRef(Str));
    addUInt(Die, dwarf::DW_AT_encoding, dwarf::DW_FORM_data1, Btr.Encoding);
    addUInt(Die, dwarf::DW_AT_byte_size, None, Btr.BitSize / 8);

    Btr.Die = &Die;
  }
}