summaryrefslogtreecommitdiffstats
path: root/src/bootstrap/compile.rs
blob: dd2b9d59366eab0b5bfc38dfe20a116a8381afca (plain)
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
//! Implementation of compiling various phases of the compiler and standard
//! library.
//!
//! This module contains some of the real meat in the rustbuild build system
//! which is where Cargo is used to compile the standard library, libtest, and
//! the compiler. This module is also responsible for assembling the sysroot as it
//! goes along from the output of the previous stage.

use std::borrow::Cow;
use std::collections::HashSet;
use std::env;
use std::fs;
use std::io::prelude::*;
use std::io::BufReader;
use std::path::{Path, PathBuf};
use std::process::{Command, Stdio};
use std::str;

use serde::Deserialize;

use crate::builder::Cargo;
use crate::builder::{Builder, Kind, RunConfig, ShouldRun, Step};
use crate::cache::{Interned, INTERNER};
use crate::config::{LlvmLibunwind, TargetSelection};
use crate::dist;
use crate::native;
use crate::tool::SourceType;
use crate::util::get_clang_cl_resource_dir;
use crate::util::{exe, is_debug_info, is_dylib, output, symlink_dir, t, up_to_date};
use crate::LLVM_TOOLS;
use crate::{CLang, Compiler, DependencyType, GitRepo, Mode};

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct Std {
    pub target: TargetSelection,
    pub compiler: Compiler,
    /// Whether to build only a subset of crates in the standard library.
    ///
    /// This shouldn't be used from other steps; see the comment on [`Rustc`].
    crates: Interned<Vec<String>>,
}

impl Std {
    pub fn new(compiler: Compiler, target: TargetSelection) -> Self {
        Self { target, compiler, crates: Default::default() }
    }
}

/// Return a `-p=x -p=y` string suitable for passing to a cargo invocation.
fn build_crates_in_set(run: &RunConfig<'_>) -> Interned<Vec<String>> {
    let mut crates = Vec::new();
    for krate in &run.paths {
        let path = krate.assert_single_path();
        let crate_name = run.builder.crate_paths[&path.path];
        crates.push(format!("-p={crate_name}"));
    }
    INTERNER.intern_list(crates)
}

impl Step for Std {
    type Output = ();
    const DEFAULT: bool = true;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        // When downloading stage1, the standard library has already been copied to the sysroot, so
        // there's no need to rebuild it.
        let builder = run.builder;
        run.crate_or_deps("test")
            .path("library")
            .lazy_default_condition(Box::new(|| !builder.download_rustc()))
    }

    fn make_run(run: RunConfig<'_>) {
        // Normally, people will pass *just* library if they pass it.
        // But it's possible (although strange) to pass something like `library std core`.
        // Build all crates anyway, as if they hadn't passed the other args.
        let has_library =
            run.paths.iter().any(|set| set.assert_single_path().path.ends_with("library"));
        let crates = if has_library { Default::default() } else { build_crates_in_set(&run) };
        run.builder.ensure(Std {
            compiler: run.builder.compiler(run.builder.top_stage, run.build_triple()),
            target: run.target,
            crates,
        });
    }

    /// Builds the standard library.
    ///
    /// This will build the standard library for a particular stage of the build
    /// using the `compiler` targeting the `target` architecture. The artifacts
    /// created will also be linked into the sysroot directory.
    fn run(self, builder: &Builder<'_>) {
        let target = self.target;
        let compiler = self.compiler;

        // These artifacts were already copied (in `impl Step for Sysroot`).
        // Don't recompile them.
        // NOTE: the ABI of the beta compiler is different from the ABI of the downloaded compiler,
        // so its artifacts can't be reused.
        if builder.download_rustc() && compiler.stage != 0 {
            return;
        }

        if builder.config.keep_stage.contains(&compiler.stage)
            || builder.config.keep_stage_std.contains(&compiler.stage)
        {
            builder.info("Warning: Using a potentially old libstd. This may not behave well.");
            builder.ensure(StdLink::from_std(self, compiler));
            return;
        }

        builder.update_submodule(&Path::new("library").join("stdarch"));

        // Profiler information requires LLVM's compiler-rt
        if builder.config.profiler {
            builder.update_submodule(&Path::new("src/llvm-project"));
        }

        let mut target_deps = builder.ensure(StartupObjects { compiler, target });

        let compiler_to_use = builder.compiler_for(compiler.stage, compiler.host, target);
        if compiler_to_use != compiler {
            builder.ensure(Std::new(compiler_to_use, target));
            builder.info(&format!("Uplifting stage1 std ({} -> {})", compiler_to_use.host, target));

            // Even if we're not building std this stage, the new sysroot must
            // still contain the third party objects needed by various targets.
            copy_third_party_objects(builder, &compiler, target);
            copy_self_contained_objects(builder, &compiler, target);

            builder.ensure(StdLink::from_std(self, compiler_to_use));
            return;
        }

        target_deps.extend(copy_third_party_objects(builder, &compiler, target));
        target_deps.extend(copy_self_contained_objects(builder, &compiler, target));

        let mut cargo = builder.cargo(compiler, Mode::Std, SourceType::InTree, target, "build");
        std_cargo(builder, target, compiler.stage, &mut cargo);

        builder.info(&format!(
            "Building stage{} std artifacts ({} -> {})",
            compiler.stage, &compiler.host, target
        ));
        run_cargo(
            builder,
            cargo,
            self.crates.to_vec(),
            &libstd_stamp(builder, compiler, target),
            target_deps,
            false,
        );

        builder.ensure(StdLink::from_std(
            self,
            builder.compiler(compiler.stage, builder.config.build),
        ));
    }
}

fn copy_and_stamp(
    builder: &Builder<'_>,
    libdir: &Path,
    sourcedir: &Path,
    name: &str,
    target_deps: &mut Vec<(PathBuf, DependencyType)>,
    dependency_type: DependencyType,
) {
    let target = libdir.join(name);
    builder.copy(&sourcedir.join(name), &target);

    target_deps.push((target, dependency_type));
}

fn copy_llvm_libunwind(builder: &Builder<'_>, target: TargetSelection, libdir: &Path) -> PathBuf {
    let libunwind_path = builder.ensure(native::Libunwind { target });
    let libunwind_source = libunwind_path.join("libunwind.a");
    let libunwind_target = libdir.join("libunwind.a");
    builder.copy(&libunwind_source, &libunwind_target);
    libunwind_target
}

/// Copies third party objects needed by various targets.
fn copy_third_party_objects(
    builder: &Builder<'_>,
    compiler: &Compiler,
    target: TargetSelection,
) -> Vec<(PathBuf, DependencyType)> {
    let mut target_deps = vec![];

    // FIXME: remove this in 2021
    if target == "x86_64-fortanix-unknown-sgx" {
        if env::var_os("X86_FORTANIX_SGX_LIBS").is_some() {
            builder.info("Warning: X86_FORTANIX_SGX_LIBS environment variable is ignored, libunwind is now compiled as part of rustbuild");
        }
    }

    if builder.config.sanitizers_enabled(target) && compiler.stage != 0 {
        // The sanitizers are only copied in stage1 or above,
        // to avoid creating dependency on LLVM.
        target_deps.extend(
            copy_sanitizers(builder, &compiler, target)
                .into_iter()
                .map(|d| (d, DependencyType::Target)),
        );
    }

    if target == "x86_64-fortanix-unknown-sgx"
        || target.contains("pc-windows-gnullvm")
        || builder.config.llvm_libunwind(target) == LlvmLibunwind::InTree
            && (target.contains("linux") || target.contains("fuchsia"))
    {
        let libunwind_path =
            copy_llvm_libunwind(builder, target, &builder.sysroot_libdir(*compiler, target));
        target_deps.push((libunwind_path, DependencyType::Target));
    }

    target_deps
}

/// Copies third party objects needed by various targets for self-contained linkage.
fn copy_self_contained_objects(
    builder: &Builder<'_>,
    compiler: &Compiler,
    target: TargetSelection,
) -> Vec<(PathBuf, DependencyType)> {
    let libdir_self_contained = builder.sysroot_libdir(*compiler, target).join("self-contained");
    t!(fs::create_dir_all(&libdir_self_contained));
    let mut target_deps = vec![];

    // Copies the libc and CRT objects.
    //
    // rustc historically provides a more self-contained installation for musl targets
    // not requiring the presence of a native musl toolchain. For example, it can fall back
    // to using gcc from a glibc-targeting toolchain for linking.
    // To do that we have to distribute musl startup objects as a part of Rust toolchain
    // and link with them manually in the self-contained mode.
    if target.contains("musl") {
        let srcdir = builder.musl_libdir(target).unwrap_or_else(|| {
            panic!("Target {:?} does not have a \"musl-libdir\" key", target.triple)
        });
        for &obj in &["libc.a", "crt1.o", "Scrt1.o", "rcrt1.o", "crti.o", "crtn.o"] {
            copy_and_stamp(
                builder,
                &libdir_self_contained,
                &srcdir,
                obj,
                &mut target_deps,
                DependencyType::TargetSelfContained,
            );
        }
        let crt_path = builder.ensure(native::CrtBeginEnd { target });
        for &obj in &["crtbegin.o", "crtbeginS.o", "crtend.o", "crtendS.o"] {
            let src = crt_path.join(obj);
            let target = libdir_self_contained.join(obj);
            builder.copy(&src, &target);
            target_deps.push((target, DependencyType::TargetSelfContained));
        }

        if !target.starts_with("s390x") {
            let libunwind_path = copy_llvm_libunwind(builder, target, &libdir_self_contained);
            target_deps.push((libunwind_path, DependencyType::TargetSelfContained));
        }
    } else if target.ends_with("-wasi") {
        let srcdir = builder
            .wasi_root(target)
            .unwrap_or_else(|| {
                panic!("Target {:?} does not have a \"wasi-root\" key", target.triple)
            })
            .join("lib/wasm32-wasi");
        for &obj in &["libc.a", "crt1-command.o", "crt1-reactor.o"] {
            copy_and_stamp(
                builder,
                &libdir_self_contained,
                &srcdir,
                obj,
                &mut target_deps,
                DependencyType::TargetSelfContained,
            );
        }
    } else if target.ends_with("windows-gnu") {
        for obj in ["crt2.o", "dllcrt2.o"].iter() {
            let src = compiler_file(builder, builder.cc(target), target, CLang::C, obj);
            let target = libdir_self_contained.join(obj);
            builder.copy(&src, &target);
            target_deps.push((target, DependencyType::TargetSelfContained));
        }
    }

    target_deps
}

/// Configure cargo to compile the standard library, adding appropriate env vars
/// and such.
pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, cargo: &mut Cargo) {
    if let Some(target) = env::var_os("MACOSX_STD_DEPLOYMENT_TARGET") {
        cargo.env("MACOSX_DEPLOYMENT_TARGET", target);
    }

    // Determine if we're going to compile in optimized C intrinsics to
    // the `compiler-builtins` crate. These intrinsics live in LLVM's
    // `compiler-rt` repository, but our `src/llvm-project` submodule isn't
    // always checked out, so we need to conditionally look for this. (e.g. if
    // an external LLVM is used we skip the LLVM submodule checkout).
    //
    // Note that this shouldn't affect the correctness of `compiler-builtins`,
    // but only its speed. Some intrinsics in C haven't been translated to Rust
    // yet but that's pretty rare. Other intrinsics have optimized
    // implementations in C which have only had slower versions ported to Rust,
    // so we favor the C version where we can, but it's not critical.
    //
    // If `compiler-rt` is available ensure that the `c` feature of the
    // `compiler-builtins` crate is enabled and it's configured to learn where
    // `compiler-rt` is located.
    let compiler_builtins_root = builder.src.join("src/llvm-project/compiler-rt");
    let compiler_builtins_c_feature = if compiler_builtins_root.exists() {
        // Note that `libprofiler_builtins/build.rs` also computes this so if
        // you're changing something here please also change that.
        cargo.env("RUST_COMPILER_RT_ROOT", &compiler_builtins_root);
        " compiler-builtins-c"
    } else {
        ""
    };

    if builder.no_std(target) == Some(true) {
        let mut features = "compiler-builtins-mem".to_string();
        if !target.starts_with("bpf") {
            features.push_str(compiler_builtins_c_feature);
        }

        // for no-std targets we only compile a few no_std crates
        cargo
            .args(&["-p", "alloc"])
            .arg("--manifest-path")
            .arg(builder.src.join("library/alloc/Cargo.toml"))
            .arg("--features")
            .arg(features);
    } else {
        let mut features = builder.std_features(target);
        features.push_str(compiler_builtins_c_feature);

        cargo
            .arg("--features")
            .arg(features)
            .arg("--manifest-path")
            .arg(builder.src.join("library/test/Cargo.toml"));

        // Help the libc crate compile by assisting it in finding various
        // sysroot native libraries.
        if target.contains("musl") {
            if let Some(p) = builder.musl_libdir(target) {
                let root = format!("native={}", p.to_str().unwrap());
                cargo.rustflag("-L").rustflag(&root);
            }
        }

        if target.ends_with("-wasi") {
            if let Some(p) = builder.wasi_root(target) {
                let root = format!("native={}/lib/wasm32-wasi", p.to_str().unwrap());
                cargo.rustflag("-L").rustflag(&root);
            }
        }
    }

    // By default, rustc uses `-Cembed-bitcode=yes`, and Cargo overrides that
    // with `-Cembed-bitcode=no` for non-LTO builds. However, libstd must be
    // built with bitcode so that the produced rlibs can be used for both LTO
    // builds (which use bitcode) and non-LTO builds (which use object code).
    // So we override the override here!
    //
    // But we don't bother for the stage 0 compiler because it's never used
    // with LTO.
    if stage >= 1 {
        cargo.rustflag("-Cembed-bitcode=yes");
    }

    // By default, rustc does not include unwind tables unless they are required
    // for a particular target. They are not required by RISC-V targets, but
    // compiling the standard library with them means that users can get
    // backtraces without having to recompile the standard library themselves.
    //
    // This choice was discussed in https://github.com/rust-lang/rust/pull/69890
    if target.contains("riscv") {
        cargo.rustflag("-Cforce-unwind-tables=yes");
    }

    let html_root =
        format!("-Zcrate-attr=doc(html_root_url=\"{}/\")", builder.doc_rust_lang_org_channel(),);
    cargo.rustflag(&html_root);
    cargo.rustdocflag(&html_root);
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
struct StdLink {
    pub compiler: Compiler,
    pub target_compiler: Compiler,
    pub target: TargetSelection,
    /// Not actually used; only present to make sure the cache invalidation is correct.
    crates: Interned<Vec<String>>,
}

impl StdLink {
    fn from_std(std: Std, host_compiler: Compiler) -> Self {
        Self {
            compiler: host_compiler,
            target_compiler: std.compiler,
            target: std.target,
            crates: std.crates,
        }
    }
}

impl Step for StdLink {
    type Output = ();

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        run.never()
    }

    /// Link all libstd rlibs/dylibs into the sysroot location.
    ///
    /// Links those artifacts generated by `compiler` to the `stage` compiler's
    /// sysroot for the specified `host` and `target`.
    ///
    /// Note that this assumes that `compiler` has already generated the libstd
    /// libraries for `target`, and this method will find them in the relevant
    /// output directory.
    fn run(self, builder: &Builder<'_>) {
        let compiler = self.compiler;
        let target_compiler = self.target_compiler;
        let target = self.target;
        builder.info(&format!(
            "Copying stage{} std from stage{} ({} -> {} / {})",
            target_compiler.stage, compiler.stage, &compiler.host, target_compiler.host, target
        ));
        let libdir = builder.sysroot_libdir(target_compiler, target);
        let hostdir = builder.sysroot_libdir(target_compiler, compiler.host);
        add_to_sysroot(builder, &libdir, &hostdir, &libstd_stamp(builder, compiler, target));
    }
}

/// Copies sanitizer runtime libraries into target libdir.
fn copy_sanitizers(
    builder: &Builder<'_>,
    compiler: &Compiler,
    target: TargetSelection,
) -> Vec<PathBuf> {
    let runtimes: Vec<native::SanitizerRuntime> = builder.ensure(native::Sanitizers { target });

    if builder.config.dry_run {
        return Vec::new();
    }

    let mut target_deps = Vec::new();
    let libdir = builder.sysroot_libdir(*compiler, target);

    for runtime in &runtimes {
        let dst = libdir.join(&runtime.name);
        builder.copy(&runtime.path, &dst);

        if target == "x86_64-apple-darwin" || target == "aarch64-apple-darwin" {
            // Update the library’s install name to reflect that it has has been renamed.
            apple_darwin_update_library_name(&dst, &format!("@rpath/{}", &runtime.name));
            // Upon renaming the install name, the code signature of the file will invalidate,
            // so we will sign it again.
            apple_darwin_sign_file(&dst);
        }

        target_deps.push(dst);
    }

    target_deps
}

fn apple_darwin_update_library_name(library_path: &Path, new_name: &str) {
    let status = Command::new("install_name_tool")
        .arg("-id")
        .arg(new_name)
        .arg(library_path)
        .status()
        .expect("failed to execute `install_name_tool`");
    assert!(status.success());
}

fn apple_darwin_sign_file(file_path: &Path) {
    let status = Command::new("codesign")
        .arg("-f") // Force to rewrite the existing signature
        .arg("-s")
        .arg("-")
        .arg(file_path)
        .status()
        .expect("failed to execute `codesign`");
    assert!(status.success());
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
pub struct StartupObjects {
    pub compiler: Compiler,
    pub target: TargetSelection,
}

impl Step for StartupObjects {
    type Output = Vec<(PathBuf, DependencyType)>;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        run.path("library/rtstartup")
    }

    fn make_run(run: RunConfig<'_>) {
        run.builder.ensure(StartupObjects {
            compiler: run.builder.compiler(run.builder.top_stage, run.build_triple()),
            target: run.target,
        });
    }

    /// Builds and prepare startup objects like rsbegin.o and rsend.o
    ///
    /// These are primarily used on Windows right now for linking executables/dlls.
    /// They don't require any library support as they're just plain old object
    /// files, so we just use the nightly snapshot compiler to always build them (as
    /// no other compilers are guaranteed to be available).
    fn run(self, builder: &Builder<'_>) -> Vec<(PathBuf, DependencyType)> {
        let for_compiler = self.compiler;
        let target = self.target;
        if !target.ends_with("windows-gnu") {
            return vec![];
        }

        let mut target_deps = vec![];

        let src_dir = &builder.src.join("library").join("rtstartup");
        let dst_dir = &builder.native_dir(target).join("rtstartup");
        let sysroot_dir = &builder.sysroot_libdir(for_compiler, target);
        t!(fs::create_dir_all(dst_dir));

        for file in &["rsbegin", "rsend"] {
            let src_file = &src_dir.join(file.to_string() + ".rs");
            let dst_file = &dst_dir.join(file.to_string() + ".o");
            if !up_to_date(src_file, dst_file) {
                let mut cmd = Command::new(&builder.initial_rustc);
                cmd.env("RUSTC_BOOTSTRAP", "1");
                if !builder.local_rebuild {
                    // a local_rebuild compiler already has stage1 features
                    cmd.arg("--cfg").arg("bootstrap");
                }
                builder.run(
                    cmd.arg("--target")
                        .arg(target.rustc_target_arg())
                        .arg("--emit=obj")
                        .arg("-o")
                        .arg(dst_file)
                        .arg(src_file),
                );
            }

            let target = sysroot_dir.join((*file).to_string() + ".o");
            builder.copy(dst_file, &target);
            target_deps.push((target, DependencyType::Target));
        }

        target_deps
    }
}

#[derive(Debug, PartialOrd, Ord, Copy, Clone, PartialEq, Eq, Hash)]
pub struct Rustc {
    pub target: TargetSelection,
    pub compiler: Compiler,
    /// Whether to build a subset of crates, rather than the whole compiler.
    ///
    /// This should only be requested by the user, not used within rustbuild itself.
    /// Using it within rustbuild can lead to confusing situation where lints are replayed
    /// in two different steps.
    crates: Interned<Vec<String>>,
}

impl Rustc {
    pub fn new(compiler: Compiler, target: TargetSelection) -> Self {
        Self { target, compiler, crates: Default::default() }
    }
}

impl Step for Rustc {
    type Output = ();
    const ONLY_HOSTS: bool = true;
    const DEFAULT: bool = false;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        let mut crates = run.builder.in_tree_crates("rustc-main", None);
        for (i, krate) in crates.iter().enumerate() {
            if krate.name == "rustc-main" {
                crates.swap_remove(i);
                break;
            }
        }
        run.crates(crates)
    }

    fn make_run(run: RunConfig<'_>) {
        let crates = build_crates_in_set(&run);
        run.builder.ensure(Rustc {
            compiler: run.builder.compiler(run.builder.top_stage, run.build_triple()),
            target: run.target,
            crates,
        });
    }

    /// Builds the compiler.
    ///
    /// This will build the compiler for a particular stage of the build using
    /// the `compiler` targeting the `target` architecture. The artifacts
    /// created will also be linked into the sysroot directory.
    fn run(self, builder: &Builder<'_>) {
        let compiler = self.compiler;
        let target = self.target;

        // NOTE: the ABI of the beta compiler is different from the ABI of the downloaded compiler,
        // so its artifacts can't be reused.
        if builder.download_rustc() && compiler.stage != 0 {
            // Copy the existing artifacts instead of rebuilding them.
            // NOTE: this path is only taken for tools linking to rustc-dev.
            builder.ensure(Sysroot { compiler });
            return;
        }

        builder.ensure(Std::new(compiler, target));

        if builder.config.keep_stage.contains(&compiler.stage) {
            builder.info("Warning: Using a potentially old librustc. This may not behave well.");
            builder.info("Warning: Use `--keep-stage-std` if you want to rebuild the compiler when it changes");
            builder.ensure(RustcLink::from_rustc(self, compiler));
            return;
        }

        let compiler_to_use = builder.compiler_for(compiler.stage, compiler.host, target);
        if compiler_to_use != compiler {
            builder.ensure(Rustc::new(compiler_to_use, target));
            builder
                .info(&format!("Uplifting stage1 rustc ({} -> {})", builder.config.build, target));
            builder.ensure(RustcLink::from_rustc(self, compiler_to_use));
            return;
        }

        // Ensure that build scripts and proc macros have a std / libproc_macro to link against.
        builder.ensure(Std::new(
            builder.compiler(self.compiler.stage, builder.config.build),
            builder.config.build,
        ));

        let mut cargo = builder.cargo(compiler, Mode::Rustc, SourceType::InTree, target, "build");
        rustc_cargo(builder, &mut cargo, target);

        if builder.config.rust_profile_use.is_some()
            && builder.config.rust_profile_generate.is_some()
        {
            panic!("Cannot use and generate PGO profiles at the same time");
        }

        // With LLD, we can use ICF (identical code folding) to reduce the executable size
        // of librustc_driver/rustc and to improve i-cache utilization.
        if builder.config.use_lld {
            cargo.rustflag("-Clink-args=-Wl,--icf=all");
        }

        let is_collecting = if let Some(path) = &builder.config.rust_profile_generate {
            if compiler.stage == 1 {
                cargo.rustflag(&format!("-Cprofile-generate={}", path));
                // Apparently necessary to avoid overflowing the counters during
                // a Cargo build profile
                cargo.rustflag("-Cllvm-args=-vp-counters-per-site=4");
                true
            } else {
                false
            }
        } else if let Some(path) = &builder.config.rust_profile_use {
            if compiler.stage == 1 {
                cargo.rustflag(&format!("-Cprofile-use={}", path));
                cargo.rustflag("-Cllvm-args=-pgo-warn-missing-function");
                true
            } else {
                false
            }
        } else {
            false
        };
        if is_collecting {
            // Ensure paths to Rust sources are relative, not absolute.
            cargo.rustflag(&format!(
                "-Cllvm-args=-static-func-strip-dirname-prefix={}",
                builder.config.src.components().count()
            ));
        }

        builder.info(&format!(
            "Building stage{} compiler artifacts ({} -> {})",
            compiler.stage, &compiler.host, target
        ));
        run_cargo(
            builder,
            cargo,
            self.crates.to_vec(),
            &librustc_stamp(builder, compiler, target),
            vec![],
            false,
        );

        builder.ensure(RustcLink::from_rustc(
            self,
            builder.compiler(compiler.stage, builder.config.build),
        ));
    }
}

pub fn rustc_cargo(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetSelection) {
    cargo
        .arg("--features")
        .arg(builder.rustc_features(builder.kind))
        .arg("--manifest-path")
        .arg(builder.src.join("compiler/rustc/Cargo.toml"));
    rustc_cargo_env(builder, cargo, target);
}

pub fn rustc_cargo_env(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetSelection) {
    // Set some configuration variables picked up by build scripts and
    // the compiler alike
    cargo
        .env("CFG_RELEASE", builder.rust_release())
        .env("CFG_RELEASE_CHANNEL", &builder.config.channel)
        .env("CFG_VERSION", builder.rust_version());

    if let Some(backend) = builder.config.rust_codegen_backends.get(0) {
        cargo.env("CFG_DEFAULT_CODEGEN_BACKEND", backend);
    }

    let libdir_relative = builder.config.libdir_relative().unwrap_or_else(|| Path::new("lib"));
    let target_config = builder.config.target_config.get(&target);

    cargo.env("CFG_LIBDIR_RELATIVE", libdir_relative);

    if let Some(ref ver_date) = builder.rust_info.commit_date() {
        cargo.env("CFG_VER_DATE", ver_date);
    }
    if let Some(ref ver_hash) = builder.rust_info.sha() {
        cargo.env("CFG_VER_HASH", ver_hash);
    }
    if !builder.unstable_features() {
        cargo.env("CFG_DISABLE_UNSTABLE_FEATURES", "1");
    }

    // Prefer the current target's own default_linker, else a globally
    // specified one.
    if let Some(s) = target_config.and_then(|c| c.default_linker.as_ref()) {
        cargo.env("CFG_DEFAULT_LINKER", s);
    } else if let Some(ref s) = builder.config.rustc_default_linker {
        cargo.env("CFG_DEFAULT_LINKER", s);
    }

    if builder.config.rustc_parallel {
        // keep in sync with `bootstrap/lib.rs:Build::rustc_features`
        // `cfg` option for rustc, `features` option for cargo, for conditional compilation
        cargo.rustflag("--cfg=parallel_compiler");
        cargo.rustdocflag("--cfg=parallel_compiler");
    }
    if builder.config.rust_verify_llvm_ir {
        cargo.env("RUSTC_VERIFY_LLVM_IR", "1");
    }

    // Pass down configuration from the LLVM build into the build of
    // rustc_llvm and rustc_codegen_llvm.
    //
    // Note that this is disabled if LLVM itself is disabled or we're in a check
    // build. If we are in a check build we still go ahead here presuming we've
    // detected that LLVM is already built and good to go which helps prevent
    // busting caches (e.g. like #71152).
    if builder.config.llvm_enabled()
        && (builder.kind != Kind::Check
            || crate::native::prebuilt_llvm_config(builder, target).is_ok())
    {
        if builder.is_rust_llvm(target) {
            cargo.env("LLVM_RUSTLLVM", "1");
        }
        let llvm_config = builder.ensure(native::Llvm { target });
        cargo.env("LLVM_CONFIG", &llvm_config);
        if let Some(s) = target_config.and_then(|c| c.llvm_config.as_ref()) {
            cargo.env("CFG_LLVM_ROOT", s);
        }

        // Some LLVM linker flags (-L and -l) may be needed to link `rustc_llvm`. Its build script
        // expects these to be passed via the `LLVM_LINKER_FLAGS` env variable, separated by
        // whitespace.
        //
        // For example:
        // - on windows, when `clang-cl` is used with instrumentation, we need to manually add
        // clang's runtime library resource directory so that the profiler runtime library can be
        // found. This is to avoid the linker errors about undefined references to
        // `__llvm_profile_instrument_memop` when linking `rustc_driver`.
        let mut llvm_linker_flags = String::new();
        if builder.config.llvm_profile_generate && target.contains("msvc") {
            if let Some(ref clang_cl_path) = builder.config.llvm_clang_cl {
                // Add clang's runtime library directory to the search path
                let clang_rt_dir = get_clang_cl_resource_dir(clang_cl_path);
                llvm_linker_flags.push_str(&format!("-L{}", clang_rt_dir.display()));
            }
        }

        // The config can also specify its own llvm linker flags.
        if let Some(ref s) = builder.config.llvm_ldflags {
            if !llvm_linker_flags.is_empty() {
                llvm_linker_flags.push_str(" ");
            }
            llvm_linker_flags.push_str(s);
        }

        // Set the linker flags via the env var that `rustc_llvm`'s build script will read.
        if !llvm_linker_flags.is_empty() {
            cargo.env("LLVM_LINKER_FLAGS", llvm_linker_flags);
        }

        // Building with a static libstdc++ is only supported on linux right now,
        // not for MSVC or macOS
        if builder.config.llvm_static_stdcpp
            && !target.contains("freebsd")
            && !target.contains("msvc")
            && !target.contains("apple")
            && !target.contains("solaris")
        {
            let file = compiler_file(
                builder,
                builder.cxx(target).unwrap(),
                target,
                CLang::Cxx,
                "libstdc++.a",
            );
            cargo.env("LLVM_STATIC_STDCPP", file);
        }
        if builder.llvm_link_shared() {
            cargo.env("LLVM_LINK_SHARED", "1");
        }
        if builder.config.llvm_use_libcxx {
            cargo.env("LLVM_USE_LIBCXX", "1");
        }
        if builder.config.llvm_optimize && !builder.config.llvm_release_debuginfo {
            cargo.env("LLVM_NDEBUG", "1");
        }
    }
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
struct RustcLink {
    pub compiler: Compiler,
    pub target_compiler: Compiler,
    pub target: TargetSelection,
    /// Not actually used; only present to make sure the cache invalidation is correct.
    crates: Interned<Vec<String>>,
}

impl RustcLink {
    fn from_rustc(rustc: Rustc, host_compiler: Compiler) -> Self {
        Self {
            compiler: host_compiler,
            target_compiler: rustc.compiler,
            target: rustc.target,
            crates: rustc.crates,
        }
    }
}

impl Step for RustcLink {
    type Output = ();

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        run.never()
    }

    /// Same as `std_link`, only for librustc
    fn run(self, builder: &Builder<'_>) {
        let compiler = self.compiler;
        let target_compiler = self.target_compiler;
        let target = self.target;
        builder.info(&format!(
            "Copying stage{} rustc from stage{} ({} -> {} / {})",
            target_compiler.stage, compiler.stage, &compiler.host, target_compiler.host, target
        ));
        add_to_sysroot(
            builder,
            &builder.sysroot_libdir(target_compiler, target),
            &builder.sysroot_libdir(target_compiler, compiler.host),
            &librustc_stamp(builder, compiler, target),
        );
    }
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
pub struct CodegenBackend {
    pub target: TargetSelection,
    pub compiler: Compiler,
    pub backend: Interned<String>,
}

impl Step for CodegenBackend {
    type Output = ();
    const ONLY_HOSTS: bool = true;
    // Only the backends specified in the `codegen-backends` entry of `config.toml` are built.
    const DEFAULT: bool = true;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        run.paths(&["compiler/rustc_codegen_cranelift", "compiler/rustc_codegen_gcc"])
    }

    fn make_run(run: RunConfig<'_>) {
        for &backend in &run.builder.config.rust_codegen_backends {
            if backend == "llvm" {
                continue; // Already built as part of rustc
            }

            run.builder.ensure(CodegenBackend {
                target: run.target,
                compiler: run.builder.compiler(run.builder.top_stage, run.build_triple()),
                backend,
            });
        }
    }

    fn run(self, builder: &Builder<'_>) {
        let compiler = self.compiler;
        let target = self.target;
        let backend = self.backend;

        builder.ensure(Rustc::new(compiler, target));

        if builder.config.keep_stage.contains(&compiler.stage) {
            builder.info(
                "Warning: Using a potentially old codegen backend. \
                This may not behave well.",
            );
            // Codegen backends are linked separately from this step today, so we don't do
            // anything here.
            return;
        }

        let compiler_to_use = builder.compiler_for(compiler.stage, compiler.host, target);
        if compiler_to_use != compiler {
            builder.ensure(CodegenBackend { compiler: compiler_to_use, target, backend });
            return;
        }

        let out_dir = builder.cargo_out(compiler, Mode::Codegen, target);

        let mut cargo = builder.cargo(compiler, Mode::Codegen, SourceType::InTree, target, "build");
        cargo
            .arg("--manifest-path")
            .arg(builder.src.join(format!("compiler/rustc_codegen_{}/Cargo.toml", backend)));
        rustc_cargo_env(builder, &mut cargo, target);

        let tmp_stamp = out_dir.join(".tmp.stamp");

        builder.info(&format!(
            "Building stage{} codegen backend {} ({} -> {})",
            compiler.stage, backend, &compiler.host, target
        ));
        let files = run_cargo(builder, cargo, vec![], &tmp_stamp, vec![], false);
        if builder.config.dry_run {
            return;
        }
        let mut files = files.into_iter().filter(|f| {
            let filename = f.file_name().unwrap().to_str().unwrap();
            is_dylib(filename) && filename.contains("rustc_codegen_")
        });
        let codegen_backend = match files.next() {
            Some(f) => f,
            None => panic!("no dylibs built for codegen backend?"),
        };
        if let Some(f) = files.next() {
            panic!(
                "codegen backend built two dylibs:\n{}\n{}",
                codegen_backend.display(),
                f.display()
            );
        }
        let stamp = codegen_backend_stamp(builder, compiler, target, backend);
        let codegen_backend = codegen_backend.to_str().unwrap();
        t!(fs::write(&stamp, &codegen_backend));
    }
}

/// Creates the `codegen-backends` folder for a compiler that's about to be
/// assembled as a complete compiler.
///
/// This will take the codegen artifacts produced by `compiler` and link them
/// into an appropriate location for `target_compiler` to be a functional
/// compiler.
fn copy_codegen_backends_to_sysroot(
    builder: &Builder<'_>,
    compiler: Compiler,
    target_compiler: Compiler,
) {
    let target = target_compiler.host;

    // Note that this step is different than all the other `*Link` steps in
    // that it's not assembling a bunch of libraries but rather is primarily
    // moving the codegen backend into place. The codegen backend of rustc is
    // not linked into the main compiler by default but is rather dynamically
    // selected at runtime for inclusion.
    //
    // Here we're looking for the output dylib of the `CodegenBackend` step and
    // we're copying that into the `codegen-backends` folder.
    let dst = builder.sysroot_codegen_backends(target_compiler);
    t!(fs::create_dir_all(&dst), dst);

    if builder.config.dry_run {
        return;
    }

    for backend in builder.config.rust_codegen_backends.iter() {
        if backend == "llvm" {
            continue; // Already built as part of rustc
        }

        let stamp = codegen_backend_stamp(builder, compiler, target, *backend);
        let dylib = t!(fs::read_to_string(&stamp));
        let file = Path::new(&dylib);
        let filename = file.file_name().unwrap().to_str().unwrap();
        // change `librustc_codegen_cranelift-xxxxxx.so` to
        // `librustc_codegen_cranelift-release.so`
        let target_filename = {
            let dash = filename.find('-').unwrap();
            let dot = filename.find('.').unwrap();
            format!("{}-{}{}", &filename[..dash], builder.rust_release(), &filename[dot..])
        };
        builder.copy(&file, &dst.join(target_filename));
    }
}

/// Cargo's output path for the standard library in a given stage, compiled
/// by a particular compiler for the specified target.
pub fn libstd_stamp(builder: &Builder<'_>, compiler: Compiler, target: TargetSelection) -> PathBuf {
    builder.cargo_out(compiler, Mode::Std, target).join(".libstd.stamp")
}

/// Cargo's output path for librustc in a given stage, compiled by a particular
/// compiler for the specified target.
pub fn librustc_stamp(
    builder: &Builder<'_>,
    compiler: Compiler,
    target: TargetSelection,
) -> PathBuf {
    builder.cargo_out(compiler, Mode::Rustc, target).join(".librustc.stamp")
}

/// Cargo's output path for librustc_codegen_llvm in a given stage, compiled by a particular
/// compiler for the specified target and backend.
fn codegen_backend_stamp(
    builder: &Builder<'_>,
    compiler: Compiler,
    target: TargetSelection,
    backend: Interned<String>,
) -> PathBuf {
    builder
        .cargo_out(compiler, Mode::Codegen, target)
        .join(format!(".librustc_codegen_{}.stamp", backend))
}

pub fn compiler_file(
    builder: &Builder<'_>,
    compiler: &Path,
    target: TargetSelection,
    c: CLang,
    file: &str,
) -> PathBuf {
    let mut cmd = Command::new(compiler);
    cmd.args(builder.cflags(target, GitRepo::Rustc, c));
    cmd.arg(format!("-print-file-name={}", file));
    let out = output(&mut cmd);
    PathBuf::from(out.trim())
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
pub struct Sysroot {
    pub compiler: Compiler,
}

impl Step for Sysroot {
    type Output = Interned<PathBuf>;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        run.never()
    }

    /// Returns the sysroot for the `compiler` specified that *this build system
    /// generates*.
    ///
    /// That is, the sysroot for the stage0 compiler is not what the compiler
    /// thinks it is by default, but it's the same as the default for stages
    /// 1-3.
    fn run(self, builder: &Builder<'_>) -> Interned<PathBuf> {
        let compiler = self.compiler;
        let sysroot = if compiler.stage == 0 {
            builder.out.join(&compiler.host.triple).join("stage0-sysroot")
        } else {
            builder.out.join(&compiler.host.triple).join(format!("stage{}", compiler.stage))
        };
        let _ = fs::remove_dir_all(&sysroot);
        t!(fs::create_dir_all(&sysroot));

        // If we're downloading a compiler from CI, we can use the same compiler for all stages other than 0.
        if builder.download_rustc() && compiler.stage != 0 {
            assert_eq!(
                builder.config.build, compiler.host,
                "Cross-compiling is not yet supported with `download-rustc`",
            );
            // Copy the compiler into the correct sysroot.
            let ci_rustc_dir =
                builder.config.out.join(&*builder.config.build.triple).join("ci-rustc");
            builder.cp_r(&ci_rustc_dir, &sysroot);
            return INTERNER.intern_path(sysroot);
        }

        // Symlink the source root into the same location inside the sysroot,
        // where `rust-src` component would go (`$sysroot/lib/rustlib/src/rust`),
        // so that any tools relying on `rust-src` also work for local builds,
        // and also for translating the virtual `/rustc/$hash` back to the real
        // directory (for running tests with `rust.remap-debuginfo = true`).
        let sysroot_lib_rustlib_src = sysroot.join("lib/rustlib/src");
        t!(fs::create_dir_all(&sysroot_lib_rustlib_src));
        let sysroot_lib_rustlib_src_rust = sysroot_lib_rustlib_src.join("rust");
        if let Err(e) = symlink_dir(&builder.config, &builder.src, &sysroot_lib_rustlib_src_rust) {
            eprintln!(
                "warning: creating symbolic link `{}` to `{}` failed with {}",
                sysroot_lib_rustlib_src_rust.display(),
                builder.src.display(),
                e,
            );
            if builder.config.rust_remap_debuginfo {
                eprintln!(
                    "warning: some `src/test/ui` tests will fail when lacking `{}`",
                    sysroot_lib_rustlib_src_rust.display(),
                );
            }
        }

        INTERNER.intern_path(sysroot)
    }
}

#[derive(Debug, Copy, PartialOrd, Ord, Clone, PartialEq, Eq, Hash)]
pub struct Assemble {
    /// The compiler which we will produce in this step. Assemble itself will
    /// take care of ensuring that the necessary prerequisites to do so exist,
    /// that is, this target can be a stage2 compiler and Assemble will build
    /// previous stages for you.
    pub target_compiler: Compiler,
}

impl Step for Assemble {
    type Output = Compiler;
    const ONLY_HOSTS: bool = true;

    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
        run.path("compiler/rustc").path("compiler")
    }

    fn make_run(run: RunConfig<'_>) {
        run.builder.ensure(Assemble {
            target_compiler: run.builder.compiler(run.builder.top_stage + 1, run.target),
        });
    }

    /// Prepare a new compiler from the artifacts in `stage`
    ///
    /// This will assemble a compiler in `build/$host/stage$stage`. The compiler
    /// must have been previously produced by the `stage - 1` builder.build
    /// compiler.
    fn run(self, builder: &Builder<'_>) -> Compiler {
        let target_compiler = self.target_compiler;

        if target_compiler.stage == 0 {
            assert_eq!(
                builder.config.build, target_compiler.host,
                "Cannot obtain compiler for non-native build triple at stage 0"
            );
            // The stage 0 compiler for the build triple is always pre-built.
            return target_compiler;
        }

        // Get the compiler that we'll use to bootstrap ourselves.
        //
        // Note that this is where the recursive nature of the bootstrap
        // happens, as this will request the previous stage's compiler on
        // downwards to stage 0.
        //
        // Also note that we're building a compiler for the host platform. We
        // only assume that we can run `build` artifacts, which means that to
        // produce some other architecture compiler we need to start from
        // `build` to get there.
        //
        // FIXME: It may be faster if we build just a stage 1 compiler and then
        //        use that to bootstrap this compiler forward.
        let build_compiler = builder.compiler(target_compiler.stage - 1, builder.config.build);

        // If we're downloading a compiler from CI, we can use the same compiler for all stages other than 0.
        if builder.download_rustc() {
            builder.ensure(Sysroot { compiler: target_compiler });
            return target_compiler;
        }

        // Build the libraries for this compiler to link to (i.e., the libraries
        // it uses at runtime). NOTE: Crates the target compiler compiles don't
        // link to these. (FIXME: Is that correct? It seems to be correct most
        // of the time but I think we do link to these for stage2/bin compilers
        // when not performing a full bootstrap).
        builder.ensure(Rustc::new(build_compiler, target_compiler.host));

        for &backend in builder.config.rust_codegen_backends.iter() {
            if backend == "llvm" {
                continue; // Already built as part of rustc
            }

            builder.ensure(CodegenBackend {
                compiler: build_compiler,
                target: target_compiler.host,
                backend,
            });
        }

        let lld_install = if builder.config.lld_enabled {
            Some(builder.ensure(native::Lld { target: target_compiler.host }))
        } else {
            None
        };

        let stage = target_compiler.stage;
        let host = target_compiler.host;
        builder.info(&format!("Assembling stage{} compiler ({})", stage, host));

        // Link in all dylibs to the libdir
        let stamp = librustc_stamp(builder, build_compiler, target_compiler.host);
        let proc_macros = builder
            .read_stamp_file(&stamp)
            .into_iter()
            .filter_map(|(path, dependency_type)| {
                if dependency_type == DependencyType::Host {
                    Some(path.file_name().unwrap().to_owned().into_string().unwrap())
                } else {
                    None
                }
            })
            .collect::<HashSet<_>>();

        let sysroot = builder.sysroot(target_compiler);
        let rustc_libdir = builder.rustc_libdir(target_compiler);
        t!(fs::create_dir_all(&rustc_libdir));
        let src_libdir = builder.sysroot_libdir(build_compiler, host);
        for f in builder.read_dir(&src_libdir) {
            let filename = f.file_name().into_string().unwrap();
            if (is_dylib(&filename) || is_debug_info(&filename)) && !proc_macros.contains(&filename)
            {
                builder.copy(&f.path(), &rustc_libdir.join(&filename));
            }
        }

        copy_codegen_backends_to_sysroot(builder, build_compiler, target_compiler);

        // We prepend this bin directory to the user PATH when linking Rust binaries. To
        // avoid shadowing the system LLD we rename the LLD we provide to `rust-lld`.
        let libdir = builder.sysroot_libdir(target_compiler, target_compiler.host);
        let libdir_bin = libdir.parent().unwrap().join("bin");
        t!(fs::create_dir_all(&libdir_bin));
        if let Some(lld_install) = lld_install {
            let src_exe = exe("lld", target_compiler.host);
            let dst_exe = exe("rust-lld", target_compiler.host);
            builder.copy(&lld_install.join("bin").join(&src_exe), &libdir_bin.join(&dst_exe));
            // for `-Z gcc-ld=lld`
            let gcc_ld_dir = libdir_bin.join("gcc-ld");
            t!(fs::create_dir(&gcc_ld_dir));
            let lld_wrapper_exe = builder.ensure(crate::tool::LldWrapper {
                compiler: build_compiler,
                target: target_compiler.host,
            });
            builder.copy(&lld_wrapper_exe, &gcc_ld_dir.join(exe("ld", target_compiler.host)));
        }

        if builder.config.rust_codegen_backends.contains(&INTERNER.intern_str("llvm")) {
            let llvm_config_bin = builder.ensure(native::Llvm { target: target_compiler.host });
            if !builder.config.dry_run {
                let llvm_bin_dir = output(Command::new(llvm_config_bin).arg("--bindir"));
                let llvm_bin_dir = Path::new(llvm_bin_dir.trim());

                // Since we've already built the LLVM tools, install them to the sysroot.
                // This is the equivalent of installing the `llvm-tools-preview` component via
                // rustup, and lets developers use a locally built toolchain to
                // build projects that expect llvm tools to be present in the sysroot
                // (e.g. the `bootimage` crate).
                for tool in LLVM_TOOLS {
                    let tool_exe = exe(tool, target_compiler.host);
                    let src_path = llvm_bin_dir.join(&tool_exe);
                    // When using `download-ci-llvm`, some of the tools
                    // may not exist, so skip trying to copy them.
                    if src_path.exists() {
                        builder.copy(&src_path, &libdir_bin.join(&tool_exe));
                    }
                }
            }
        }

        // Ensure that `libLLVM.so` ends up in the newly build compiler directory,
        // so that it can be found when the newly built `rustc` is run.
        dist::maybe_install_llvm_runtime(builder, target_compiler.host, &sysroot);
        dist::maybe_install_llvm_target(builder, target_compiler.host, &sysroot);

        // Link the compiler binary itself into place
        let out_dir = builder.cargo_out(build_compiler, Mode::Rustc, host);
        let rustc = out_dir.join(exe("rustc-main", host));
        let bindir = sysroot.join("bin");
        t!(fs::create_dir_all(&bindir));
        let compiler = builder.rustc(target_compiler);
        builder.copy(&rustc, &compiler);

        target_compiler
    }
}

/// Link some files into a rustc sysroot.
///
/// For a particular stage this will link the file listed in `stamp` into the
/// `sysroot_dst` provided.
pub fn add_to_sysroot(
    builder: &Builder<'_>,
    sysroot_dst: &Path,
    sysroot_host_dst: &Path,
    stamp: &Path,
) {
    let self_contained_dst = &sysroot_dst.join("self-contained");
    t!(fs::create_dir_all(&sysroot_dst));
    t!(fs::create_dir_all(&sysroot_host_dst));
    t!(fs::create_dir_all(&self_contained_dst));
    for (path, dependency_type) in builder.read_stamp_file(stamp) {
        let dst = match dependency_type {
            DependencyType::Host => sysroot_host_dst,
            DependencyType::Target => sysroot_dst,
            DependencyType::TargetSelfContained => self_contained_dst,
        };
        builder.copy(&path, &dst.join(path.file_name().unwrap()));
    }
}

pub fn run_cargo(
    builder: &Builder<'_>,
    cargo: Cargo,
    tail_args: Vec<String>,
    stamp: &Path,
    additional_target_deps: Vec<(PathBuf, DependencyType)>,
    is_check: bool,
) -> Vec<PathBuf> {
    if builder.config.dry_run {
        return Vec::new();
    }

    // `target_root_dir` looks like $dir/$target/release
    let target_root_dir = stamp.parent().unwrap();
    // `target_deps_dir` looks like $dir/$target/release/deps
    let target_deps_dir = target_root_dir.join("deps");
    // `host_root_dir` looks like $dir/release
    let host_root_dir = target_root_dir
        .parent()
        .unwrap() // chop off `release`
        .parent()
        .unwrap() // chop off `$target`
        .join(target_root_dir.file_name().unwrap());

    // Spawn Cargo slurping up its JSON output. We'll start building up the
    // `deps` array of all files it generated along with a `toplevel` array of
    // files we need to probe for later.
    let mut deps = Vec::new();
    let mut toplevel = Vec::new();
    let ok = stream_cargo(builder, cargo, tail_args, &mut |msg| {
        let (filenames, crate_types) = match msg {
            CargoMessage::CompilerArtifact {
                filenames,
                target: CargoTarget { crate_types },
                ..
            } => (filenames, crate_types),
            _ => return,
        };
        for filename in filenames {
            // Skip files like executables
            if !(filename.ends_with(".rlib")
                || filename.ends_with(".lib")
                || filename.ends_with(".a")
                || is_debug_info(&filename)
                || is_dylib(&filename)
                || (is_check && filename.ends_with(".rmeta")))
            {
                continue;
            }

            let filename = Path::new(&*filename);

            // If this was an output file in the "host dir" we don't actually
            // worry about it, it's not relevant for us
            if filename.starts_with(&host_root_dir) {
                // Unless it's a proc macro used in the compiler
                if crate_types.iter().any(|t| t == "proc-macro") {
                    deps.push((filename.to_path_buf(), DependencyType::Host));
                }
                continue;
            }

            // If this was output in the `deps` dir then this is a precise file
            // name (hash included) so we start tracking it.
            if filename.starts_with(&target_deps_dir) {
                deps.push((filename.to_path_buf(), DependencyType::Target));
                continue;
            }

            // Otherwise this was a "top level artifact" which right now doesn't
            // have a hash in the name, but there's a version of this file in
            // the `deps` folder which *does* have a hash in the name. That's
            // the one we'll want to we'll probe for it later.
            //
            // We do not use `Path::file_stem` or `Path::extension` here,
            // because some generated files may have multiple extensions e.g.
            // `std-<hash>.dll.lib` on Windows. The aforementioned methods only
            // split the file name by the last extension (`.lib`) while we need
            // to split by all extensions (`.dll.lib`).
            let expected_len = t!(filename.metadata()).len();
            let filename = filename.file_name().unwrap().to_str().unwrap();
            let mut parts = filename.splitn(2, '.');
            let file_stem = parts.next().unwrap().to_owned();
            let extension = parts.next().unwrap().to_owned();

            toplevel.push((file_stem, extension, expected_len));
        }
    });

    if !ok {
        crate::detail_exit(1);
    }

    // Ok now we need to actually find all the files listed in `toplevel`. We've
    // got a list of prefix/extensions and we basically just need to find the
    // most recent file in the `deps` folder corresponding to each one.
    let contents = t!(target_deps_dir.read_dir())
        .map(|e| t!(e))
        .map(|e| (e.path(), e.file_name().into_string().unwrap(), t!(e.metadata())))
        .collect::<Vec<_>>();
    for (prefix, extension, expected_len) in toplevel {
        let candidates = contents.iter().filter(|&&(_, ref filename, ref meta)| {
            meta.len() == expected_len
                && filename
                    .strip_prefix(&prefix[..])
                    .map(|s| s.starts_with('-') && s.ends_with(&extension[..]))
                    .unwrap_or(false)
        });
        let max = candidates.max_by_key(|&&(_, _, ref metadata)| {
            metadata.modified().expect("mtime should be available on all relevant OSes")
        });
        let path_to_add = match max {
            Some(triple) => triple.0.to_str().unwrap(),
            None => panic!("no output generated for {:?} {:?}", prefix, extension),
        };
        if is_dylib(path_to_add) {
            let candidate = format!("{}.lib", path_to_add);
            let candidate = PathBuf::from(candidate);
            if candidate.exists() {
                deps.push((candidate, DependencyType::Target));
            }
        }
        deps.push((path_to_add.into(), DependencyType::Target));
    }

    deps.extend(additional_target_deps);
    deps.sort();
    let mut new_contents = Vec::new();
    for (dep, dependency_type) in deps.iter() {
        new_contents.extend(match *dependency_type {
            DependencyType::Host => b"h",
            DependencyType::Target => b"t",
            DependencyType::TargetSelfContained => b"s",
        });
        new_contents.extend(dep.to_str().unwrap().as_bytes());
        new_contents.extend(b"\0");
    }
    t!(fs::write(&stamp, &new_contents));
    deps.into_iter().map(|(d, _)| d).collect()
}

pub fn stream_cargo(
    builder: &Builder<'_>,
    cargo: Cargo,
    tail_args: Vec<String>,
    cb: &mut dyn FnMut(CargoMessage<'_>),
) -> bool {
    let mut cargo = Command::from(cargo);
    if builder.config.dry_run {
        return true;
    }
    // Instruct Cargo to give us json messages on stdout, critically leaving
    // stderr as piped so we can get those pretty colors.
    let mut message_format = if builder.config.json_output {
        String::from("json")
    } else {
        String::from("json-render-diagnostics")
    };
    if let Some(s) = &builder.config.rustc_error_format {
        message_format.push_str(",json-diagnostic-");
        message_format.push_str(s);
    }
    cargo.arg("--message-format").arg(message_format).stdout(Stdio::piped());

    for arg in tail_args {
        cargo.arg(arg);
    }

    builder.verbose(&format!("running: {:?}", cargo));
    let mut child = match cargo.spawn() {
        Ok(child) => child,
        Err(e) => panic!("failed to execute command: {:?}\nerror: {}", cargo, e),
    };

    // Spawn Cargo slurping up its JSON output. We'll start building up the
    // `deps` array of all files it generated along with a `toplevel` array of
    // files we need to probe for later.
    let stdout = BufReader::new(child.stdout.take().unwrap());
    for line in stdout.lines() {
        let line = t!(line);
        match serde_json::from_str::<CargoMessage<'_>>(&line) {
            Ok(msg) => {
                if builder.config.json_output {
                    // Forward JSON to stdout.
                    println!("{}", line);
                }
                cb(msg)
            }
            // If this was informational, just print it out and continue
            Err(_) => println!("{}", line),
        }
    }

    // Make sure Cargo actually succeeded after we read all of its stdout.
    let status = t!(child.wait());
    if builder.is_verbose() && !status.success() {
        eprintln!(
            "command did not execute successfully: {:?}\n\
                  expected success, got: {}",
            cargo, status
        );
    }
    status.success()
}

#[derive(Deserialize)]
pub struct CargoTarget<'a> {
    crate_types: Vec<Cow<'a, str>>,
}

#[derive(Deserialize)]
#[serde(tag = "reason", rename_all = "kebab-case")]
pub enum CargoMessage<'a> {
    CompilerArtifact {
        package_id: Cow<'a, str>,
        features: Vec<Cow<'a, str>>,
        filenames: Vec<Cow<'a, str>>,
        target: CargoTarget<'a>,
    },
    BuildScriptExecuted {
        package_id: Cow<'a, str>,
    },
    BuildFinished {
        success: bool,
    },
}