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
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
use self::type_map::DINodeCreationResult;
use self::type_map::Stub;
use self::type_map::UniqueTypeId;

use super::namespace::mangled_name_of_instance;
use super::type_names::{compute_debuginfo_type_name, compute_debuginfo_vtable_name};
use super::utils::{
    create_DIArray, debug_context, get_namespace_for_item, is_node_local_to_unit, DIB,
};
use super::CodegenUnitDebugContext;

use crate::abi;
use crate::common::CodegenCx;
use crate::debuginfo::metadata::type_map::build_type_with_children;
use crate::debuginfo::utils::fat_pointer_kind;
use crate::debuginfo::utils::FatPtrKind;
use crate::llvm;
use crate::llvm::debuginfo::{
    DIDescriptor, DIFile, DIFlags, DILexicalBlock, DIScope, DIType, DebugEmissionKind,
};
use crate::value::Value;

use cstr::cstr;
use rustc_codegen_ssa::debuginfo::type_names::cpp_like_debuginfo;
use rustc_codegen_ssa::debuginfo::type_names::VTableNameKind;
use rustc_codegen_ssa::traits::*;
use rustc_fs_util::path_to_c_string;
use rustc_hir::def::CtorKind;
use rustc_hir::def_id::{DefId, LOCAL_CRATE};
use rustc_index::vec::{Idx, IndexVec};
use rustc_middle::bug;
use rustc_middle::mir::{self, GeneratorLayout};
use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
use rustc_middle::ty::subst::GenericArgKind;
use rustc_middle::ty::{
    self, AdtKind, Instance, ParamEnv, PolyExistentialTraitRef, Ty, TyCtxt, Visibility,
};
use rustc_session::config::{self, DebugInfo, Lto};
use rustc_span::symbol::Symbol;
use rustc_span::FileName;
use rustc_span::{self, FileNameDisplayPreference, SourceFile};
use rustc_symbol_mangling::typeid_for_trait_ref;
use rustc_target::abi::{Align, Size};
use smallvec::smallvec;

use libc::{c_char, c_longlong, c_uint};
use std::borrow::Cow;
use std::fmt::{self, Write};
use std::hash::{Hash, Hasher};
use std::iter;
use std::path::{Path, PathBuf};
use std::ptr;

impl PartialEq for llvm::Metadata {
    fn eq(&self, other: &Self) -> bool {
        ptr::eq(self, other)
    }
}

impl Eq for llvm::Metadata {}

impl Hash for llvm::Metadata {
    fn hash<H: Hasher>(&self, hasher: &mut H) {
        (self as *const Self).hash(hasher);
    }
}

impl fmt::Debug for llvm::Metadata {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        (self as *const Self).fmt(f)
    }
}

// From DWARF 5.
// See http://www.dwarfstd.org/ShowIssue.php?issue=140129.1.
const DW_LANG_RUST: c_uint = 0x1c;
#[allow(non_upper_case_globals)]
const DW_ATE_boolean: c_uint = 0x02;
#[allow(non_upper_case_globals)]
const DW_ATE_float: c_uint = 0x04;
#[allow(non_upper_case_globals)]
const DW_ATE_signed: c_uint = 0x05;
#[allow(non_upper_case_globals)]
const DW_ATE_unsigned: c_uint = 0x07;
#[allow(non_upper_case_globals)]
const DW_ATE_UTF: c_uint = 0x10;

pub(super) const UNKNOWN_LINE_NUMBER: c_uint = 0;
pub(super) const UNKNOWN_COLUMN_NUMBER: c_uint = 0;

const NO_SCOPE_METADATA: Option<&DIScope> = None;
/// A function that returns an empty list of generic parameter debuginfo nodes.
const NO_GENERICS: for<'ll> fn(&CodegenCx<'ll, '_>) -> SmallVec<&'ll DIType> = |_| SmallVec::new();

// SmallVec is used quite a bit in this module, so create a shorthand.
// The actual number of elements is not so important.
pub type SmallVec<T> = smallvec::SmallVec<[T; 16]>;

mod enums;
mod type_map;

pub(crate) use type_map::TypeMap;

/// Returns from the enclosing function if the type debuginfo node with the given
/// unique ID can be found in the type map.
macro_rules! return_if_di_node_created_in_meantime {
    ($cx: expr, $unique_type_id: expr) => {
        if let Some(di_node) = debug_context($cx).type_map.di_node_for_unique_id($unique_type_id) {
            return DINodeCreationResult::new(di_node, true);
        }
    };
}

/// Extract size and alignment from a TyAndLayout.
#[inline]
fn size_and_align_of<'tcx>(ty_and_layout: TyAndLayout<'tcx>) -> (Size, Align) {
    (ty_and_layout.size, ty_and_layout.align.abi)
}

/// Creates debuginfo for a fixed size array (e.g. `[u64; 123]`).
/// For slices (that is, "arrays" of unknown size) use [build_slice_type_di_node].
fn build_fixed_size_array_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    unique_type_id: UniqueTypeId<'tcx>,
    array_type: Ty<'tcx>,
) -> DINodeCreationResult<'ll> {
    let ty::Array(element_type, len) = array_type.kind() else {
        bug!("build_fixed_size_array_di_node() called with non-ty::Array type `{:?}`", array_type)
    };

    let element_type_di_node = type_di_node(cx, *element_type);

    return_if_di_node_created_in_meantime!(cx, unique_type_id);

    let (size, align) = cx.size_and_align_of(array_type);

    let upper_bound = len.eval_usize(cx.tcx, ty::ParamEnv::reveal_all()) as c_longlong;

    let subrange =
        unsafe { Some(llvm::LLVMRustDIBuilderGetOrCreateSubrange(DIB(cx), 0, upper_bound)) };

    let subscripts = create_DIArray(DIB(cx), &[subrange]);
    let di_node = unsafe {
        llvm::LLVMRustDIBuilderCreateArrayType(
            DIB(cx),
            size.bits(),
            align.bits() as u32,
            element_type_di_node,
            subscripts,
        )
    };

    DINodeCreationResult::new(di_node, false)
}

/// Creates debuginfo for built-in pointer-like things:
///
///  - ty::Ref
///  - ty::RawPtr
///  - ty::Adt in the case it's Box
///
/// At some point we might want to remove the special handling of Box
/// and treat it the same as other smart pointers (like Rc, Arc, ...).
fn build_pointer_or_reference_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    ptr_type: Ty<'tcx>,
    pointee_type: Ty<'tcx>,
    unique_type_id: UniqueTypeId<'tcx>,
) -> DINodeCreationResult<'ll> {
    // The debuginfo generated by this function is only valid if `ptr_type` is really just
    // a (fat) pointer. Make sure it is not called for e.g. `Box<T, NonZSTAllocator>`.
    debug_assert_eq!(
        cx.size_and_align_of(ptr_type),
        cx.size_and_align_of(cx.tcx.mk_mut_ptr(pointee_type))
    );

    let pointee_type_di_node = type_di_node(cx, pointee_type);

    return_if_di_node_created_in_meantime!(cx, unique_type_id);

    let (thin_pointer_size, thin_pointer_align) =
        cx.size_and_align_of(cx.tcx.mk_imm_ptr(cx.tcx.types.unit));
    let ptr_type_debuginfo_name = compute_debuginfo_type_name(cx.tcx, ptr_type, true);

    match fat_pointer_kind(cx, pointee_type) {
        None => {
            // This is a thin pointer. Create a regular pointer type and give it the correct name.
            debug_assert_eq!(
                (thin_pointer_size, thin_pointer_align),
                cx.size_and_align_of(ptr_type),
                "ptr_type={}, pointee_type={}",
                ptr_type,
                pointee_type,
            );

            let di_node = unsafe {
                llvm::LLVMRustDIBuilderCreatePointerType(
                    DIB(cx),
                    pointee_type_di_node,
                    thin_pointer_size.bits(),
                    thin_pointer_align.bits() as u32,
                    0, // Ignore DWARF address space.
                    ptr_type_debuginfo_name.as_ptr().cast(),
                    ptr_type_debuginfo_name.len(),
                )
            };

            DINodeCreationResult { di_node, already_stored_in_typemap: false }
        }
        Some(fat_pointer_kind) => {
            type_map::build_type_with_children(
                cx,
                type_map::stub(
                    cx,
                    Stub::Struct,
                    unique_type_id,
                    &ptr_type_debuginfo_name,
                    cx.size_and_align_of(ptr_type),
                    NO_SCOPE_METADATA,
                    DIFlags::FlagZero,
                ),
                |cx, owner| {
                    // FIXME: If this fat pointer is a `Box` then we don't want to use its
                    //        type layout and instead use the layout of the raw pointer inside
                    //        of it.
                    //        The proper way to handle this is to not treat Box as a pointer
                    //        at all and instead emit regular struct debuginfo for it. We just
                    //        need to make sure that we don't break existing debuginfo consumers
                    //        by doing that (at least not without a warning period).
                    let layout_type =
                        if ptr_type.is_box() { cx.tcx.mk_mut_ptr(pointee_type) } else { ptr_type };

                    let layout = cx.layout_of(layout_type);
                    let addr_field = layout.field(cx, abi::FAT_PTR_ADDR);
                    let extra_field = layout.field(cx, abi::FAT_PTR_EXTRA);

                    let (addr_field_name, extra_field_name) = match fat_pointer_kind {
                        FatPtrKind::Dyn => ("pointer", "vtable"),
                        FatPtrKind::Slice => ("data_ptr", "length"),
                    };

                    debug_assert_eq!(abi::FAT_PTR_ADDR, 0);
                    debug_assert_eq!(abi::FAT_PTR_EXTRA, 1);

                    // The data pointer type is a regular, thin pointer, regardless of whether this
                    // is a slice or a trait object.
                    let data_ptr_type_di_node = unsafe {
                        llvm::LLVMRustDIBuilderCreatePointerType(
                            DIB(cx),
                            pointee_type_di_node,
                            addr_field.size.bits(),
                            addr_field.align.abi.bits() as u32,
                            0, // Ignore DWARF address space.
                            std::ptr::null(),
                            0,
                        )
                    };

                    smallvec![
                        build_field_di_node(
                            cx,
                            owner,
                            addr_field_name,
                            (addr_field.size, addr_field.align.abi),
                            layout.fields.offset(abi::FAT_PTR_ADDR),
                            DIFlags::FlagZero,
                            data_ptr_type_di_node,
                        ),
                        build_field_di_node(
                            cx,
                            owner,
                            extra_field_name,
                            (extra_field.size, extra_field.align.abi),
                            layout.fields.offset(abi::FAT_PTR_EXTRA),
                            DIFlags::FlagZero,
                            type_di_node(cx, extra_field.ty),
                        ),
                    ]
                },
                NO_GENERICS,
            )
        }
    }
}

fn build_subroutine_type_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    unique_type_id: UniqueTypeId<'tcx>,
) -> DINodeCreationResult<'ll> {
    // It's possible to create a self-referential
    // type in Rust by using 'impl trait':
    //
    // fn foo() -> impl Copy { foo }
    //
    // Unfortunately LLVM's API does not allow us to create recursive subroutine types.
    // In order to work around that restriction we place a marker type in the type map,
    // before creating the actual type. If the actual type is recursive, it will hit the
    // marker type. So we end up with a type that looks like
    //
    // fn foo() -> <recursive_type>
    //
    // Once that is created, we replace the marker in the typemap with the actual type.
    debug_context(cx)
        .type_map
        .unique_id_to_di_node
        .borrow_mut()
        .insert(unique_type_id, recursion_marker_type_di_node(cx));

    let fn_ty = unique_type_id.expect_ty();
    let signature = cx
        .tcx
        .normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), fn_ty.fn_sig(cx.tcx));

    let signature_di_nodes: SmallVec<_> = iter::once(
        // return type
        match signature.output().kind() {
            ty::Tuple(tys) if tys.is_empty() => {
                // this is a "void" function
                None
            }
            _ => Some(type_di_node(cx, signature.output())),
        },
    )
    .chain(
        // regular arguments
        signature.inputs().iter().map(|&argument_type| Some(type_di_node(cx, argument_type))),
    )
    .collect();

    debug_context(cx).type_map.unique_id_to_di_node.borrow_mut().remove(&unique_type_id);

    let fn_di_node = unsafe {
        llvm::LLVMRustDIBuilderCreateSubroutineType(
            DIB(cx),
            create_DIArray(DIB(cx), &signature_di_nodes[..]),
        )
    };

    // This is actually a function pointer, so wrap it in pointer DI.
    let name = compute_debuginfo_type_name(cx.tcx, fn_ty, false);
    let di_node = unsafe {
        llvm::LLVMRustDIBuilderCreatePointerType(
            DIB(cx),
            fn_di_node,
            cx.tcx.data_layout.pointer_size.bits(),
            cx.tcx.data_layout.pointer_align.abi.bits() as u32,
            0, // Ignore DWARF address space.
            name.as_ptr().cast(),
            name.len(),
        )
    };

    DINodeCreationResult::new(di_node, false)
}

/// Create debuginfo for `dyn SomeTrait` types. Currently these are empty structs
/// we with the correct type name (e.g. "dyn SomeTrait<Foo, Item=u32> + Sync").
fn build_dyn_type_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    dyn_type: Ty<'tcx>,
    unique_type_id: UniqueTypeId<'tcx>,
) -> DINodeCreationResult<'ll> {
    if let ty::Dynamic(..) = dyn_type.kind() {
        let type_name = compute_debuginfo_type_name(cx.tcx, dyn_type, true);
        type_map::build_type_with_children(
            cx,
            type_map::stub(
                cx,
                Stub::Struct,
                unique_type_id,
                &type_name,
                cx.size_and_align_of(dyn_type),
                NO_SCOPE_METADATA,
                DIFlags::FlagZero,
            ),
            |_, _| smallvec![],
            NO_GENERICS,
        )
    } else {
        bug!(
            "Only ty::Dynamic is valid for build_dyn_type_di_node(). Found {:?} instead.",
            dyn_type
        )
    }
}

/// Create debuginfo for `[T]` and `str`. These are unsized.
///
/// NOTE: We currently emit just emit the debuginfo for the element type here
/// (i.e. `T` for slices and `u8` for `str`), so that we end up with
/// `*const T` for the `data_ptr` field of the corresponding fat-pointer
/// debuginfo of `&[T]`.
///
/// It would be preferable and more accurate if we emitted a DIArray of T
/// without an upper bound instead. That is, LLVM already supports emitting
/// debuginfo of arrays of unknown size. But GDB currently seems to end up
/// in an infinite loop when confronted with such a type.
///
/// As a side effect of the current encoding every instance of a type like
/// `struct Foo { unsized_field: [u8] }` will look like
/// `struct Foo { unsized_field: u8 }` in debuginfo. If the length of the
/// slice is zero, then accessing `unsized_field` in the debugger would
/// result in an out-of-bounds access.
fn build_slice_type_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    slice_type: Ty<'tcx>,
    unique_type_id: UniqueTypeId<'tcx>,
) -> DINodeCreationResult<'ll> {
    let element_type = match slice_type.kind() {
        ty::Slice(element_type) => *element_type,
        ty::Str => cx.tcx.types.u8,
        _ => {
            bug!(
                "Only ty::Slice is valid for build_slice_type_di_node(). Found {:?} instead.",
                slice_type
            )
        }
    };

    let element_type_di_node = type_di_node(cx, element_type);
    return_if_di_node_created_in_meantime!(cx, unique_type_id);
    DINodeCreationResult { di_node: element_type_di_node, already_stored_in_typemap: false }
}

/// Get the debuginfo node for the given type.
///
/// This function will look up the debuginfo node in the TypeMap. If it can't find it, it
/// will create the node by dispatching to the corresponding `build_*_di_node()` function.
pub fn type_di_node<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>, t: Ty<'tcx>) -> &'ll DIType {
    let unique_type_id = UniqueTypeId::for_ty(cx.tcx, t);

    if let Some(existing_di_node) = debug_context(cx).type_map.di_node_for_unique_id(unique_type_id)
    {
        return existing_di_node;
    }

    debug!("type_di_node: {:?}", t);

    let DINodeCreationResult { di_node, already_stored_in_typemap } = match *t.kind() {
        ty::Never | ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) => {
            build_basic_type_di_node(cx, t)
        }
        ty::Tuple(elements) if elements.is_empty() => build_basic_type_di_node(cx, t),
        ty::Array(..) => build_fixed_size_array_di_node(cx, unique_type_id, t),
        ty::Slice(_) | ty::Str => build_slice_type_di_node(cx, t, unique_type_id),
        ty::Dynamic(..) => build_dyn_type_di_node(cx, t, unique_type_id),
        ty::Foreign(..) => build_foreign_type_di_node(cx, t, unique_type_id),
        ty::RawPtr(ty::TypeAndMut { ty: pointee_type, .. }) | ty::Ref(_, pointee_type, _) => {
            build_pointer_or_reference_di_node(cx, t, pointee_type, unique_type_id)
        }
        // Box<T, A> may have a non-ZST allocator A. In that case, we
        // cannot treat Box<T, A> as just an owned alias of `*mut T`.
        ty::Adt(def, substs) if def.is_box() && cx.layout_of(substs.type_at(1)).is_zst() => {
            build_pointer_or_reference_di_node(cx, t, t.boxed_ty(), unique_type_id)
        }
        ty::FnDef(..) | ty::FnPtr(_) => build_subroutine_type_di_node(cx, unique_type_id),
        ty::Closure(..) => build_closure_env_di_node(cx, unique_type_id),
        ty::Generator(..) => enums::build_generator_di_node(cx, unique_type_id),
        ty::Adt(def, ..) => match def.adt_kind() {
            AdtKind::Struct => build_struct_type_di_node(cx, unique_type_id),
            AdtKind::Union => build_union_type_di_node(cx, unique_type_id),
            AdtKind::Enum => enums::build_enum_type_di_node(cx, unique_type_id),
        },
        ty::Tuple(_) => build_tuple_type_di_node(cx, unique_type_id),
        // Type parameters from polymorphized functions.
        ty::Param(_) => build_param_type_di_node(cx, t),
        _ => bug!("debuginfo: unexpected type in type_di_node(): {:?}", t),
    };

    {
        if already_stored_in_typemap {
            // Make sure that we really do have a `TypeMap` entry for the unique type ID.
            let di_node_for_uid =
                match debug_context(cx).type_map.di_node_for_unique_id(unique_type_id) {
                    Some(di_node) => di_node,
                    None => {
                        bug!(
                            "expected type debuginfo node for unique \
                               type ID '{:?}' to already be in \
                               the `debuginfo::TypeMap` but it \
                               was not.",
                            unique_type_id,
                        );
                    }
                };

            debug_assert_eq!(di_node_for_uid as *const _, di_node as *const _);
        } else {
            debug_context(cx).type_map.insert(unique_type_id, di_node);
        }
    }

    di_node
}

// FIXME(mw): Cache this via a regular UniqueTypeId instead of an extra field in the debug context.
fn recursion_marker_type_di_node<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>) -> &'ll DIType {
    *debug_context(cx).recursion_marker_type.get_or_init(move || {
        unsafe {
            // The choice of type here is pretty arbitrary -
            // anything reading the debuginfo for a recursive
            // type is going to see *something* weird - the only
            // question is what exactly it will see.
            //
            // FIXME: the name `<recur_type>` does not fit the naming scheme
            //        of other types.
            //
            // FIXME: it might make sense to use an actual pointer type here
            //        so that debuggers can show the address.
            let name = "<recur_type>";
            llvm::LLVMRustDIBuilderCreateBasicType(
                DIB(cx),
                name.as_ptr().cast(),
                name.len(),
                cx.tcx.data_layout.pointer_size.bits(),
                DW_ATE_unsigned,
            )
        }
    })
}

fn hex_encode(data: &[u8]) -> String {
    let mut hex_string = String::with_capacity(data.len() * 2);
    for byte in data.iter() {
        write!(&mut hex_string, "{:02x}", byte).unwrap();
    }
    hex_string
}

pub fn file_metadata<'ll>(cx: &CodegenCx<'ll, '_>, source_file: &SourceFile) -> &'ll DIFile {
    let cache_key = Some((source_file.name_hash, source_file.src_hash));
    return debug_context(cx)
        .created_files
        .borrow_mut()
        .entry(cache_key)
        .or_insert_with(|| alloc_new_file_metadata(cx, source_file));

    #[instrument(skip(cx, source_file), level = "debug")]
    fn alloc_new_file_metadata<'ll>(
        cx: &CodegenCx<'ll, '_>,
        source_file: &SourceFile,
    ) -> &'ll DIFile {
        debug!(?source_file.name);

        let (directory, file_name) = match &source_file.name {
            FileName::Real(filename) => {
                let working_directory = &cx.sess().opts.working_dir;
                debug!(?working_directory);

                let filename = cx
                    .sess()
                    .source_map()
                    .path_mapping()
                    .to_embeddable_absolute_path(filename.clone(), working_directory);

                // Construct the absolute path of the file
                let abs_path = filename.remapped_path_if_available();
                debug!(?abs_path);

                if let Ok(rel_path) =
                    abs_path.strip_prefix(working_directory.remapped_path_if_available())
                {
                    // If the compiler's working directory (which also is the DW_AT_comp_dir of
                    // the compilation unit) is a prefix of the path we are about to emit, then
                    // only emit the part relative to the working directory.
                    // Because of path remapping we sometimes see strange things here: `abs_path`
                    // might actually look like a relative path
                    // (e.g. `<crate-name-and-version>/src/lib.rs`), so if we emit it without
                    // taking the working directory into account, downstream tooling will
                    // interpret it as `<working-directory>/<crate-name-and-version>/src/lib.rs`,
                    // which makes no sense. Usually in such cases the working directory will also
                    // be remapped to `<crate-name-and-version>` or some other prefix of the path
                    // we are remapping, so we end up with
                    // `<crate-name-and-version>/<crate-name-and-version>/src/lib.rs`.
                    // By moving the working directory portion into the `directory` part of the
                    // DIFile, we allow LLVM to emit just the relative path for DWARF, while
                    // still emitting the correct absolute path for CodeView.
                    (
                        working_directory.to_string_lossy(FileNameDisplayPreference::Remapped),
                        rel_path.to_string_lossy().into_owned(),
                    )
                } else {
                    ("".into(), abs_path.to_string_lossy().into_owned())
                }
            }
            other => ("".into(), other.prefer_remapped().to_string_lossy().into_owned()),
        };

        let hash_kind = match source_file.src_hash.kind {
            rustc_span::SourceFileHashAlgorithm::Md5 => llvm::ChecksumKind::MD5,
            rustc_span::SourceFileHashAlgorithm::Sha1 => llvm::ChecksumKind::SHA1,
            rustc_span::SourceFileHashAlgorithm::Sha256 => llvm::ChecksumKind::SHA256,
        };
        let hash_value = hex_encode(source_file.src_hash.hash_bytes());

        unsafe {
            llvm::LLVMRustDIBuilderCreateFile(
                DIB(cx),
                file_name.as_ptr().cast(),
                file_name.len(),
                directory.as_ptr().cast(),
                directory.len(),
                hash_kind,
                hash_value.as_ptr().cast(),
                hash_value.len(),
            )
        }
    }
}

pub fn unknown_file_metadata<'ll>(cx: &CodegenCx<'ll, '_>) -> &'ll DIFile {
    debug_context(cx).created_files.borrow_mut().entry(None).or_insert_with(|| unsafe {
        let file_name = "<unknown>";
        let directory = "";
        let hash_value = "";

        llvm::LLVMRustDIBuilderCreateFile(
            DIB(cx),
            file_name.as_ptr().cast(),
            file_name.len(),
            directory.as_ptr().cast(),
            directory.len(),
            llvm::ChecksumKind::None,
            hash_value.as_ptr().cast(),
            hash_value.len(),
        )
    })
}

trait MsvcBasicName {
    fn msvc_basic_name(self) -> &'static str;
}

impl MsvcBasicName for ty::IntTy {
    fn msvc_basic_name(self) -> &'static str {
        match self {
            ty::IntTy::Isize => "ptrdiff_t",
            ty::IntTy::I8 => "__int8",
            ty::IntTy::I16 => "__int16",
            ty::IntTy::I32 => "__int32",
            ty::IntTy::I64 => "__int64",
            ty::IntTy::I128 => "__int128",
        }
    }
}

impl MsvcBasicName for ty::UintTy {
    fn msvc_basic_name(self) -> &'static str {
        match self {
            ty::UintTy::Usize => "size_t",
            ty::UintTy::U8 => "unsigned __int8",
            ty::UintTy::U16 => "unsigned __int16",
            ty::UintTy::U32 => "unsigned __int32",
            ty::UintTy::U64 => "unsigned __int64",
            ty::UintTy::U128 => "unsigned __int128",
        }
    }
}

impl MsvcBasicName for ty::FloatTy {
    fn msvc_basic_name(self) -> &'static str {
        match self {
            ty::FloatTy::F32 => "float",
            ty::FloatTy::F64 => "double",
        }
    }
}

fn build_basic_type_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    t: Ty<'tcx>,
) -> DINodeCreationResult<'ll> {
    debug!("build_basic_type_di_node: {:?}", t);

    // When targeting MSVC, emit MSVC style type names for compatibility with
    // .natvis visualizers (and perhaps other existing native debuggers?)
    let cpp_like_debuginfo = cpp_like_debuginfo(cx.tcx);

    let (name, encoding) = match t.kind() {
        ty::Never => ("!", DW_ATE_unsigned),
        ty::Tuple(elements) if elements.is_empty() => {
            if cpp_like_debuginfo {
                return build_tuple_type_di_node(cx, UniqueTypeId::for_ty(cx.tcx, t));
            } else {
                ("()", DW_ATE_unsigned)
            }
        }
        ty::Bool => ("bool", DW_ATE_boolean),
        ty::Char => ("char", DW_ATE_UTF),
        ty::Int(int_ty) if cpp_like_debuginfo => (int_ty.msvc_basic_name(), DW_ATE_signed),
        ty::Uint(uint_ty) if cpp_like_debuginfo => (uint_ty.msvc_basic_name(), DW_ATE_unsigned),
        ty::Float(float_ty) if cpp_like_debuginfo => (float_ty.msvc_basic_name(), DW_ATE_float),
        ty::Int(int_ty) => (int_ty.name_str(), DW_ATE_signed),
        ty::Uint(uint_ty) => (uint_ty.name_str(), DW_ATE_unsigned),
        ty::Float(float_ty) => (float_ty.name_str(), DW_ATE_float),
        _ => bug!("debuginfo::build_basic_type_di_node - `t` is invalid type"),
    };

    let ty_di_node = unsafe {
        llvm::LLVMRustDIBuilderCreateBasicType(
            DIB(cx),
            name.as_ptr().cast(),
            name.len(),
            cx.size_of(t).bits(),
            encoding,
        )
    };

    if !cpp_like_debuginfo {
        return DINodeCreationResult::new(ty_di_node, false);
    }

    let typedef_name = match t.kind() {
        ty::Int(int_ty) => int_ty.name_str(),
        ty::Uint(uint_ty) => uint_ty.name_str(),
        ty::Float(float_ty) => float_ty.name_str(),
        _ => return DINodeCreationResult::new(ty_di_node, false),
    };

    let typedef_di_node = unsafe {
        llvm::LLVMRustDIBuilderCreateTypedef(
            DIB(cx),
            ty_di_node,
            typedef_name.as_ptr().cast(),
            typedef_name.len(),
            unknown_file_metadata(cx),
            0,
            None,
        )
    };

    DINodeCreationResult::new(typedef_di_node, false)
}

fn build_foreign_type_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    t: Ty<'tcx>,
    unique_type_id: UniqueTypeId<'tcx>,
) -> DINodeCreationResult<'ll> {
    debug!("build_foreign_type_di_node: {:?}", t);

    let &ty::Foreign(def_id) = unique_type_id.expect_ty().kind() else {
        bug!("build_foreign_type_di_node() called with unexpected type: {:?}", unique_type_id.expect_ty());
    };

    build_type_with_children(
        cx,
        type_map::stub(
            cx,
            Stub::Struct,
            unique_type_id,
            &compute_debuginfo_type_name(cx.tcx, t, false),
            cx.size_and_align_of(t),
            Some(get_namespace_for_item(cx, def_id)),
            DIFlags::FlagZero,
        ),
        |_, _| smallvec![],
        NO_GENERICS,
    )
}

fn build_param_type_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    t: Ty<'tcx>,
) -> DINodeCreationResult<'ll> {
    debug!("build_param_type_di_node: {:?}", t);
    let name = format!("{:?}", t);
    DINodeCreationResult {
        di_node: unsafe {
            llvm::LLVMRustDIBuilderCreateBasicType(
                DIB(cx),
                name.as_ptr().cast(),
                name.len(),
                Size::ZERO.bits(),
                DW_ATE_unsigned,
            )
        },
        already_stored_in_typemap: false,
    }
}

pub fn build_compile_unit_di_node<'ll, 'tcx>(
    tcx: TyCtxt<'tcx>,
    codegen_unit_name: &str,
    debug_context: &CodegenUnitDebugContext<'ll, 'tcx>,
) -> &'ll DIDescriptor {
    let mut name_in_debuginfo = match tcx.sess.local_crate_source_file {
        Some(ref path) => path.clone(),
        None => PathBuf::from(tcx.crate_name(LOCAL_CRATE).as_str()),
    };

    // To avoid breaking split DWARF, we need to ensure that each codegen unit
    // has a unique `DW_AT_name`. This is because there's a remote chance that
    // different codegen units for the same module will have entirely
    // identical DWARF entries for the purpose of the DWO ID, which would
    // violate Appendix F ("Split Dwarf Object Files") of the DWARF 5
    // specification. LLVM uses the algorithm specified in section 7.32 "Type
    // Signature Computation" to compute the DWO ID, which does not include
    // any fields that would distinguish compilation units. So we must embed
    // the codegen unit name into the `DW_AT_name`. (Issue #88521.)
    //
    // Additionally, the OSX linker has an idiosyncrasy where it will ignore
    // some debuginfo if multiple object files with the same `DW_AT_name` are
    // linked together.
    //
    // As a workaround for these two issues, we generate unique names for each
    // object file. Those do not correspond to an actual source file but that
    // is harmless.
    name_in_debuginfo.push("@");
    name_in_debuginfo.push(codegen_unit_name);

    debug!("build_compile_unit_di_node: {:?}", name_in_debuginfo);
    let rustc_producer =
        format!("rustc version {}", option_env!("CFG_VERSION").expect("CFG_VERSION"),);
    // FIXME(#41252) Remove "clang LLVM" if we can get GDB and LLVM to play nice.
    let producer = format!("clang LLVM ({})", rustc_producer);

    let name_in_debuginfo = name_in_debuginfo.to_string_lossy();
    let work_dir = tcx.sess.opts.working_dir.to_string_lossy(FileNameDisplayPreference::Remapped);
    let flags = "\0";
    let output_filenames = tcx.output_filenames(());
    let split_name = if tcx.sess.target_can_use_split_dwarf() {
        output_filenames
            .split_dwarf_path(
                tcx.sess.split_debuginfo(),
                tcx.sess.opts.unstable_opts.split_dwarf_kind,
                Some(codegen_unit_name),
            )
            // We get a path relative to the working directory from split_dwarf_path
            .map(|f| tcx.sess.source_map().path_mapping().map_prefix(f).0)
    } else {
        None
    }
    .unwrap_or_default();
    let split_name = split_name.to_str().unwrap();

    // FIXME(#60020):
    //
    //    This should actually be
    //
    //        let kind = DebugEmissionKind::from_generic(tcx.sess.opts.debuginfo);
    //
    //    That is, we should set LLVM's emission kind to `LineTablesOnly` if
    //    we are compiling with "limited" debuginfo. However, some of the
    //    existing tools relied on slightly more debuginfo being generated than
    //    would be the case with `LineTablesOnly`, and we did not want to break
    //    these tools in a "drive-by fix", without a good idea or plan about
    //    what limited debuginfo should exactly look like. So for now we keep
    //    the emission kind as `FullDebug`.
    //
    //    See https://github.com/rust-lang/rust/issues/60020 for details.
    let kind = DebugEmissionKind::FullDebug;
    assert!(tcx.sess.opts.debuginfo != DebugInfo::None);

    unsafe {
        let compile_unit_file = llvm::LLVMRustDIBuilderCreateFile(
            debug_context.builder,
            name_in_debuginfo.as_ptr().cast(),
            name_in_debuginfo.len(),
            work_dir.as_ptr().cast(),
            work_dir.len(),
            llvm::ChecksumKind::None,
            ptr::null(),
            0,
        );

        let unit_metadata = llvm::LLVMRustDIBuilderCreateCompileUnit(
            debug_context.builder,
            DW_LANG_RUST,
            compile_unit_file,
            producer.as_ptr().cast(),
            producer.len(),
            tcx.sess.opts.optimize != config::OptLevel::No,
            flags.as_ptr().cast(),
            0,
            // NB: this doesn't actually have any perceptible effect, it seems. LLVM will instead
            // put the path supplied to `MCSplitDwarfFile` into the debug info of the final
            // output(s).
            split_name.as_ptr().cast(),
            split_name.len(),
            kind,
            0,
            tcx.sess.opts.unstable_opts.split_dwarf_inlining,
        );

        if tcx.sess.opts.unstable_opts.profile {
            let cu_desc_metadata =
                llvm::LLVMRustMetadataAsValue(debug_context.llcontext, unit_metadata);
            let default_gcda_path = &output_filenames.with_extension("gcda");
            let gcda_path =
                tcx.sess.opts.unstable_opts.profile_emit.as_ref().unwrap_or(default_gcda_path);

            let gcov_cu_info = [
                path_to_mdstring(debug_context.llcontext, &output_filenames.with_extension("gcno")),
                path_to_mdstring(debug_context.llcontext, gcda_path),
                cu_desc_metadata,
            ];
            let gcov_metadata = llvm::LLVMMDNodeInContext(
                debug_context.llcontext,
                gcov_cu_info.as_ptr(),
                gcov_cu_info.len() as c_uint,
            );

            let llvm_gcov_ident = cstr!("llvm.gcov");
            llvm::LLVMAddNamedMetadataOperand(
                debug_context.llmod,
                llvm_gcov_ident.as_ptr(),
                gcov_metadata,
            );
        }

        // Insert `llvm.ident` metadata on the wasm targets since that will
        // get hooked up to the "producer" sections `processed-by` information.
        if tcx.sess.target.is_like_wasm {
            let name_metadata = llvm::LLVMMDStringInContext(
                debug_context.llcontext,
                rustc_producer.as_ptr().cast(),
                rustc_producer.as_bytes().len() as c_uint,
            );
            llvm::LLVMAddNamedMetadataOperand(
                debug_context.llmod,
                cstr!("llvm.ident").as_ptr(),
                llvm::LLVMMDNodeInContext(debug_context.llcontext, &name_metadata, 1),
            );
        }

        return unit_metadata;
    };

    fn path_to_mdstring<'ll>(llcx: &'ll llvm::Context, path: &Path) -> &'ll Value {
        let path_str = path_to_c_string(path);
        unsafe {
            llvm::LLVMMDStringInContext(
                llcx,
                path_str.as_ptr(),
                path_str.as_bytes().len() as c_uint,
            )
        }
    }
}

/// Creates a `DW_TAG_member` entry inside the DIE represented by the given `type_di_node`.
fn build_field_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    owner: &'ll DIScope,
    name: &str,
    size_and_align: (Size, Align),
    offset: Size,
    flags: DIFlags,
    type_di_node: &'ll DIType,
) -> &'ll DIType {
    unsafe {
        llvm::LLVMRustDIBuilderCreateMemberType(
            DIB(cx),
            owner,
            name.as_ptr().cast(),
            name.len(),
            unknown_file_metadata(cx),
            UNKNOWN_LINE_NUMBER,
            size_and_align.0.bits(),
            size_and_align.1.bits() as u32,
            offset.bits(),
            flags,
            type_di_node,
        )
    }
}

/// Creates the debuginfo node for a Rust struct type. Maybe be a regular struct or a tuple-struct.
fn build_struct_type_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    unique_type_id: UniqueTypeId<'tcx>,
) -> DINodeCreationResult<'ll> {
    let struct_type = unique_type_id.expect_ty();
    let ty::Adt(adt_def, _) = struct_type.kind() else {
        bug!("build_struct_type_di_node() called with non-struct-type: {:?}", struct_type);
    };
    debug_assert!(adt_def.is_struct());
    let containing_scope = get_namespace_for_item(cx, adt_def.did());
    let struct_type_and_layout = cx.layout_of(struct_type);
    let variant_def = adt_def.non_enum_variant();

    type_map::build_type_with_children(
        cx,
        type_map::stub(
            cx,
            Stub::Struct,
            unique_type_id,
            &compute_debuginfo_type_name(cx.tcx, struct_type, false),
            size_and_align_of(struct_type_and_layout),
            Some(containing_scope),
            DIFlags::FlagZero,
        ),
        // Fields:
        |cx, owner| {
            variant_def
                .fields
                .iter()
                .enumerate()
                .map(|(i, f)| {
                    let field_name = if variant_def.ctor_kind == CtorKind::Fn {
                        // This is a tuple struct
                        tuple_field_name(i)
                    } else {
                        // This is struct with named fields
                        Cow::Borrowed(f.name.as_str())
                    };
                    let field_layout = struct_type_and_layout.field(cx, i);
                    build_field_di_node(
                        cx,
                        owner,
                        &field_name[..],
                        (field_layout.size, field_layout.align.abi),
                        struct_type_and_layout.fields.offset(i),
                        DIFlags::FlagZero,
                        type_di_node(cx, field_layout.ty),
                    )
                })
                .collect()
        },
        |cx| build_generic_type_param_di_nodes(cx, struct_type),
    )
}

//=-----------------------------------------------------------------------------
// Tuples
//=-----------------------------------------------------------------------------

/// Returns names of captured upvars for closures and generators.
///
/// Here are some examples:
///  - `name__field1__field2` when the upvar is captured by value.
///  - `_ref__name__field` when the upvar is captured by reference.
///
/// For generators this only contains upvars that are shared by all states.
fn closure_saved_names_of_captured_variables(tcx: TyCtxt<'_>, def_id: DefId) -> SmallVec<String> {
    let body = tcx.optimized_mir(def_id);

    body.var_debug_info
        .iter()
        .filter_map(|var| {
            let is_ref = match var.value {
                mir::VarDebugInfoContents::Place(place) if place.local == mir::Local::new(1) => {
                    // The projection is either `[.., Field, Deref]` or `[.., Field]`. It
                    // implies whether the variable is captured by value or by reference.
                    matches!(place.projection.last().unwrap(), mir::ProjectionElem::Deref)
                }
                _ => return None,
            };
            let prefix = if is_ref { "_ref__" } else { "" };
            Some(prefix.to_owned() + var.name.as_str())
        })
        .collect()
}

/// Builds the DW_TAG_member debuginfo nodes for the upvars of a closure or generator.
/// For a generator, this will handle upvars shared by all states.
fn build_upvar_field_di_nodes<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    closure_or_generator_ty: Ty<'tcx>,
    closure_or_generator_di_node: &'ll DIType,
) -> SmallVec<&'ll DIType> {
    let (&def_id, up_var_tys) = match closure_or_generator_ty.kind() {
        ty::Generator(def_id, substs, _) => {
            let upvar_tys: SmallVec<_> = substs.as_generator().prefix_tys().collect();
            (def_id, upvar_tys)
        }
        ty::Closure(def_id, substs) => {
            let upvar_tys: SmallVec<_> = substs.as_closure().upvar_tys().collect();
            (def_id, upvar_tys)
        }
        _ => {
            bug!(
                "build_upvar_field_di_nodes() called with non-closure-or-generator-type: {:?}",
                closure_or_generator_ty
            )
        }
    };

    debug_assert!(
        up_var_tys
            .iter()
            .all(|&t| t == cx.tcx.normalize_erasing_regions(ParamEnv::reveal_all(), t))
    );

    let capture_names = closure_saved_names_of_captured_variables(cx.tcx, def_id);
    let layout = cx.layout_of(closure_or_generator_ty);

    up_var_tys
        .into_iter()
        .zip(capture_names.iter())
        .enumerate()
        .map(|(index, (up_var_ty, capture_name))| {
            build_field_di_node(
                cx,
                closure_or_generator_di_node,
                capture_name,
                cx.size_and_align_of(up_var_ty),
                layout.fields.offset(index),
                DIFlags::FlagZero,
                type_di_node(cx, up_var_ty),
            )
        })
        .collect()
}

/// Builds the DW_TAG_structure_type debuginfo node for a Rust tuple type.
fn build_tuple_type_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    unique_type_id: UniqueTypeId<'tcx>,
) -> DINodeCreationResult<'ll> {
    let tuple_type = unique_type_id.expect_ty();
    let &ty::Tuple(component_types) = tuple_type.kind() else {
        bug!("build_tuple_type_di_node() called with non-tuple-type: {:?}", tuple_type)
    };

    let tuple_type_and_layout = cx.layout_of(tuple_type);
    let type_name = compute_debuginfo_type_name(cx.tcx, tuple_type, false);

    type_map::build_type_with_children(
        cx,
        type_map::stub(
            cx,
            Stub::Struct,
            unique_type_id,
            &type_name,
            size_and_align_of(tuple_type_and_layout),
            NO_SCOPE_METADATA,
            DIFlags::FlagZero,
        ),
        // Fields:
        |cx, tuple_di_node| {
            component_types
                .into_iter()
                .enumerate()
                .map(|(index, component_type)| {
                    build_field_di_node(
                        cx,
                        tuple_di_node,
                        &tuple_field_name(index),
                        cx.size_and_align_of(component_type),
                        tuple_type_and_layout.fields.offset(index),
                        DIFlags::FlagZero,
                        type_di_node(cx, component_type),
                    )
                })
                .collect()
        },
        NO_GENERICS,
    )
}

/// Builds the debuginfo node for a closure environment.
fn build_closure_env_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    unique_type_id: UniqueTypeId<'tcx>,
) -> DINodeCreationResult<'ll> {
    let closure_env_type = unique_type_id.expect_ty();
    let &ty::Closure(def_id, _substs) = closure_env_type.kind() else {
        bug!("build_closure_env_di_node() called with non-closure-type: {:?}", closure_env_type)
    };
    let containing_scope = get_namespace_for_item(cx, def_id);
    let type_name = compute_debuginfo_type_name(cx.tcx, closure_env_type, false);

    type_map::build_type_with_children(
        cx,
        type_map::stub(
            cx,
            Stub::Struct,
            unique_type_id,
            &type_name,
            cx.size_and_align_of(closure_env_type),
            Some(containing_scope),
            DIFlags::FlagZero,
        ),
        // Fields:
        |cx, owner| build_upvar_field_di_nodes(cx, closure_env_type, owner),
        NO_GENERICS,
    )
}

/// Build the debuginfo node for a Rust `union` type.
fn build_union_type_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    unique_type_id: UniqueTypeId<'tcx>,
) -> DINodeCreationResult<'ll> {
    let union_type = unique_type_id.expect_ty();
    let (union_def_id, variant_def) = match union_type.kind() {
        ty::Adt(def, _) => (def.did(), def.non_enum_variant()),
        _ => bug!("build_union_type_di_node on a non-ADT"),
    };
    let containing_scope = get_namespace_for_item(cx, union_def_id);
    let union_ty_and_layout = cx.layout_of(union_type);
    let type_name = compute_debuginfo_type_name(cx.tcx, union_type, false);

    type_map::build_type_with_children(
        cx,
        type_map::stub(
            cx,
            Stub::Union,
            unique_type_id,
            &type_name,
            size_and_align_of(union_ty_and_layout),
            Some(containing_scope),
            DIFlags::FlagZero,
        ),
        // Fields:
        |cx, owner| {
            variant_def
                .fields
                .iter()
                .enumerate()
                .map(|(i, f)| {
                    let field_layout = union_ty_and_layout.field(cx, i);
                    build_field_di_node(
                        cx,
                        owner,
                        f.name.as_str(),
                        size_and_align_of(field_layout),
                        Size::ZERO,
                        DIFlags::FlagZero,
                        type_di_node(cx, field_layout.ty),
                    )
                })
                .collect()
        },
        // Generics:
        |cx| build_generic_type_param_di_nodes(cx, union_type),
    )
}

// FIXME(eddyb) maybe precompute this? Right now it's computed once
// per generator monomorphization, but it doesn't depend on substs.
fn generator_layout_and_saved_local_names<'tcx>(
    tcx: TyCtxt<'tcx>,
    def_id: DefId,
) -> (&'tcx GeneratorLayout<'tcx>, IndexVec<mir::GeneratorSavedLocal, Option<Symbol>>) {
    let body = tcx.optimized_mir(def_id);
    let generator_layout = body.generator_layout().unwrap();
    let mut generator_saved_local_names = IndexVec::from_elem(None, &generator_layout.field_tys);

    let state_arg = mir::Local::new(1);
    for var in &body.var_debug_info {
        let mir::VarDebugInfoContents::Place(place) = &var.value else { continue };
        if place.local != state_arg {
            continue;
        }
        match place.projection[..] {
            [
                // Deref of the `Pin<&mut Self>` state argument.
                mir::ProjectionElem::Field(..),
                mir::ProjectionElem::Deref,
                // Field of a variant of the state.
                mir::ProjectionElem::Downcast(_, variant),
                mir::ProjectionElem::Field(field, _),
            ] => {
                let name = &mut generator_saved_local_names
                    [generator_layout.variant_fields[variant][field]];
                if name.is_none() {
                    name.replace(var.name);
                }
            }
            _ => {}
        }
    }
    (generator_layout, generator_saved_local_names)
}

/// Computes the type parameters for a type, if any, for the given metadata.
fn build_generic_type_param_di_nodes<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    ty: Ty<'tcx>,
) -> SmallVec<&'ll DIType> {
    if let ty::Adt(def, substs) = *ty.kind() {
        if substs.types().next().is_some() {
            let generics = cx.tcx.generics_of(def.did());
            let names = get_parameter_names(cx, generics);
            let template_params: SmallVec<_> = iter::zip(substs, names)
                .filter_map(|(kind, name)| {
                    if let GenericArgKind::Type(ty) = kind.unpack() {
                        let actual_type =
                            cx.tcx.normalize_erasing_regions(ParamEnv::reveal_all(), ty);
                        let actual_type_di_node = type_di_node(cx, actual_type);
                        let name = name.as_str();
                        Some(unsafe {
                            llvm::LLVMRustDIBuilderCreateTemplateTypeParameter(
                                DIB(cx),
                                None,
                                name.as_ptr().cast(),
                                name.len(),
                                actual_type_di_node,
                            )
                        })
                    } else {
                        None
                    }
                })
                .collect();

            return template_params;
        }
    }

    return smallvec![];

    fn get_parameter_names(cx: &CodegenCx<'_, '_>, generics: &ty::Generics) -> Vec<Symbol> {
        let mut names = generics
            .parent
            .map_or_else(Vec::new, |def_id| get_parameter_names(cx, cx.tcx.generics_of(def_id)));
        names.extend(generics.params.iter().map(|param| param.name));
        names
    }
}

/// Creates debug information for the given global variable.
///
/// Adds the created debuginfo nodes directly to the crate's IR.
pub fn build_global_var_di_node<'ll>(cx: &CodegenCx<'ll, '_>, def_id: DefId, global: &'ll Value) {
    if cx.dbg_cx.is_none() {
        return;
    }

    // Only create type information if full debuginfo is enabled
    if cx.sess().opts.debuginfo != DebugInfo::Full {
        return;
    }

    let tcx = cx.tcx;

    // We may want to remove the namespace scope if we're in an extern block (see
    // https://github.com/rust-lang/rust/pull/46457#issuecomment-351750952).
    let var_scope = get_namespace_for_item(cx, def_id);
    let span = tcx.def_span(def_id);

    let (file_metadata, line_number) = if !span.is_dummy() {
        let loc = cx.lookup_debug_loc(span.lo());
        (file_metadata(cx, &loc.file), loc.line)
    } else {
        (unknown_file_metadata(cx), UNKNOWN_LINE_NUMBER)
    };

    let is_local_to_unit = is_node_local_to_unit(cx, def_id);
    let variable_type = Instance::mono(cx.tcx, def_id).ty(cx.tcx, ty::ParamEnv::reveal_all());
    let type_di_node = type_di_node(cx, variable_type);
    let var_name = tcx.item_name(def_id);
    let var_name = var_name.as_str();
    let linkage_name = mangled_name_of_instance(cx, Instance::mono(tcx, def_id)).name;
    // When empty, linkage_name field is omitted,
    // which is what we want for no_mangle statics
    let linkage_name = if var_name == linkage_name { "" } else { linkage_name };

    let global_align = cx.align_of(variable_type);

    unsafe {
        llvm::LLVMRustDIBuilderCreateStaticVariable(
            DIB(cx),
            Some(var_scope),
            var_name.as_ptr().cast(),
            var_name.len(),
            linkage_name.as_ptr().cast(),
            linkage_name.len(),
            file_metadata,
            line_number,
            type_di_node,
            is_local_to_unit,
            global,
            None,
            global_align.bits() as u32,
        );
    }
}

/// Generates LLVM debuginfo for a vtable.
///
/// The vtable type looks like a struct with a field for each function pointer and super-trait
/// pointer it contains (plus the `size` and `align` fields).
///
/// Except for `size`, `align`, and `drop_in_place`, the field names don't try to mirror
/// the name of the method they implement. This can be implemented in the future once there
/// is a proper disambiguation scheme for dealing with methods from different traits that have
/// the same name.
fn build_vtable_type_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    ty: Ty<'tcx>,
    poly_trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
) -> &'ll DIType {
    let tcx = cx.tcx;

    let vtable_entries = if let Some(poly_trait_ref) = poly_trait_ref {
        let trait_ref = poly_trait_ref.with_self_ty(tcx, ty);
        let trait_ref = tcx.erase_regions(trait_ref);

        tcx.vtable_entries(trait_ref)
    } else {
        TyCtxt::COMMON_VTABLE_ENTRIES
    };

    // All function pointers are described as opaque pointers. This could be improved in the future
    // by describing them as actual function pointers.
    let void_pointer_ty = tcx.mk_imm_ptr(tcx.types.unit);
    let void_pointer_type_di_node = type_di_node(cx, void_pointer_ty);
    let usize_di_node = type_di_node(cx, tcx.types.usize);
    let (pointer_size, pointer_align) = cx.size_and_align_of(void_pointer_ty);
    // If `usize` is not pointer-sized and -aligned then the size and alignment computations
    // for the vtable as a whole would be wrong. Let's make sure this holds even on weird
    // platforms.
    assert_eq!(cx.size_and_align_of(tcx.types.usize), (pointer_size, pointer_align));

    let vtable_type_name =
        compute_debuginfo_vtable_name(cx.tcx, ty, poly_trait_ref, VTableNameKind::Type);
    let unique_type_id = UniqueTypeId::for_vtable_ty(tcx, ty, poly_trait_ref);
    let size = pointer_size * vtable_entries.len() as u64;

    // This gets mapped to a DW_AT_containing_type attribute which allows GDB to correlate
    // the vtable to the type it is for.
    let vtable_holder = type_di_node(cx, ty);

    build_type_with_children(
        cx,
        type_map::stub(
            cx,
            Stub::VTableTy { vtable_holder },
            unique_type_id,
            &vtable_type_name,
            (size, pointer_align),
            NO_SCOPE_METADATA,
            DIFlags::FlagArtificial,
        ),
        |cx, vtable_type_di_node| {
            vtable_entries
                .iter()
                .enumerate()
                .filter_map(|(index, vtable_entry)| {
                    let (field_name, field_type_di_node) = match vtable_entry {
                        ty::VtblEntry::MetadataDropInPlace => {
                            ("drop_in_place".to_string(), void_pointer_type_di_node)
                        }
                        ty::VtblEntry::Method(_) => {
                            // Note: This code does not try to give a proper name to each method
                            //       because their might be multiple methods with the same name
                            //       (coming from different traits).
                            (format!("__method{}", index), void_pointer_type_di_node)
                        }
                        ty::VtblEntry::TraitVPtr(_) => {
                            (format!("__super_trait_ptr{}", index), void_pointer_type_di_node)
                        }
                        ty::VtblEntry::MetadataAlign => ("align".to_string(), usize_di_node),
                        ty::VtblEntry::MetadataSize => ("size".to_string(), usize_di_node),
                        ty::VtblEntry::Vacant => return None,
                    };

                    let field_offset = pointer_size * index as u64;

                    Some(build_field_di_node(
                        cx,
                        vtable_type_di_node,
                        &field_name,
                        (pointer_size, pointer_align),
                        field_offset,
                        DIFlags::FlagZero,
                        field_type_di_node,
                    ))
                })
                .collect()
        },
        NO_GENERICS,
    )
    .di_node
}

fn vcall_visibility_metadata<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    ty: Ty<'tcx>,
    trait_ref: Option<PolyExistentialTraitRef<'tcx>>,
    vtable: &'ll Value,
) {
    enum VCallVisibility {
        Public = 0,
        LinkageUnit = 1,
        TranslationUnit = 2,
    }

    let Some(trait_ref) = trait_ref else { return };

    let trait_ref_self = trait_ref.with_self_ty(cx.tcx, ty);
    let trait_ref_self = cx.tcx.erase_regions(trait_ref_self);
    let trait_def_id = trait_ref_self.def_id();
    let trait_vis = cx.tcx.visibility(trait_def_id);

    let cgus = cx.sess().codegen_units();
    let single_cgu = cgus == 1;

    let lto = cx.sess().lto();

    // Since LLVM requires full LTO for the virtual function elimination optimization to apply,
    // only the `Lto::Fat` cases are relevant currently.
    let vcall_visibility = match (lto, trait_vis, single_cgu) {
        // If there is not LTO and the visibility in public, we have to assume that the vtable can
        // be seen from anywhere. With multiple CGUs, the vtable is quasi-public.
        (Lto::No | Lto::ThinLocal, Visibility::Public, _)
        | (Lto::No, Visibility::Restricted(_), false) => VCallVisibility::Public,
        // With LTO and a quasi-public visibility, the usages of the functions of the vtable are
        // all known by the `LinkageUnit`.
        // FIXME: LLVM only supports this optimization for `Lto::Fat` currently. Once it also
        // supports `Lto::Thin` the `VCallVisibility` may have to be adjusted for those.
        (Lto::Fat | Lto::Thin, Visibility::Public, _)
        | (Lto::ThinLocal | Lto::Thin | Lto::Fat, Visibility::Restricted(_), false) => {
            VCallVisibility::LinkageUnit
        }
        // If there is only one CGU, private vtables can only be seen by that CGU/translation unit
        // and therefore we know of all usages of functions in the vtable.
        (_, Visibility::Restricted(_), true) => VCallVisibility::TranslationUnit,
    };

    let trait_ref_typeid = typeid_for_trait_ref(cx.tcx, trait_ref);

    unsafe {
        let typeid = llvm::LLVMMDStringInContext(
            cx.llcx,
            trait_ref_typeid.as_ptr() as *const c_char,
            trait_ref_typeid.as_bytes().len() as c_uint,
        );
        let v = [cx.const_usize(0), typeid];
        llvm::LLVMRustGlobalAddMetadata(
            vtable,
            llvm::MD_type as c_uint,
            llvm::LLVMValueAsMetadata(llvm::LLVMMDNodeInContext(
                cx.llcx,
                v.as_ptr(),
                v.len() as c_uint,
            )),
        );
        let vcall_visibility = llvm::LLVMValueAsMetadata(cx.const_u64(vcall_visibility as u64));
        let vcall_visibility_metadata = llvm::LLVMMDNodeInContext2(cx.llcx, &vcall_visibility, 1);
        llvm::LLVMGlobalSetMetadata(
            vtable,
            llvm::MetadataType::MD_vcall_visibility as c_uint,
            vcall_visibility_metadata,
        );
    }
}

/// Creates debug information for the given vtable, which is for the
/// given type.
///
/// Adds the created metadata nodes directly to the crate's IR.
pub fn create_vtable_di_node<'ll, 'tcx>(
    cx: &CodegenCx<'ll, 'tcx>,
    ty: Ty<'tcx>,
    poly_trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
    vtable: &'ll Value,
) {
    // FIXME(flip1995): The virtual function elimination optimization only works with full LTO in
    // LLVM at the moment.
    if cx.sess().opts.unstable_opts.virtual_function_elimination && cx.sess().lto() == Lto::Fat {
        vcall_visibility_metadata(cx, ty, poly_trait_ref, vtable);
    }

    if cx.dbg_cx.is_none() {
        return;
    }

    // Only create type information if full debuginfo is enabled
    if cx.sess().opts.debuginfo != DebugInfo::Full {
        return;
    }

    let vtable_name =
        compute_debuginfo_vtable_name(cx.tcx, ty, poly_trait_ref, VTableNameKind::GlobalVariable);
    let vtable_type_di_node = build_vtable_type_di_node(cx, ty, poly_trait_ref);
    let linkage_name = "";

    unsafe {
        llvm::LLVMRustDIBuilderCreateStaticVariable(
            DIB(cx),
            NO_SCOPE_METADATA,
            vtable_name.as_ptr().cast(),
            vtable_name.len(),
            linkage_name.as_ptr().cast(),
            linkage_name.len(),
            unknown_file_metadata(cx),
            UNKNOWN_LINE_NUMBER,
            vtable_type_di_node,
            true,
            vtable,
            None,
            0,
        );
    }
}

/// Creates an "extension" of an existing `DIScope` into another file.
pub fn extend_scope_to_file<'ll>(
    cx: &CodegenCx<'ll, '_>,
    scope_metadata: &'ll DIScope,
    file: &SourceFile,
) -> &'ll DILexicalBlock {
    let file_metadata = file_metadata(cx, file);
    unsafe { llvm::LLVMRustDIBuilderCreateLexicalBlockFile(DIB(cx), scope_metadata, file_metadata) }
}

pub fn tuple_field_name(field_index: usize) -> Cow<'static, str> {
    const TUPLE_FIELD_NAMES: [&'static str; 16] = [
        "__0", "__1", "__2", "__3", "__4", "__5", "__6", "__7", "__8", "__9", "__10", "__11",
        "__12", "__13", "__14", "__15",
    ];
    TUPLE_FIELD_NAMES
        .get(field_index)
        .map(|s| Cow::from(*s))
        .unwrap_or_else(|| Cow::from(format!("__{}", field_index)))
}