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
use std::collections::BTreeSet;
use std::fmt::Display;
use std::fmt::Write as _;
use std::fs;
use std::io::{self, Write};
use std::path::{Path, PathBuf};

use super::graphviz::write_mir_fn_graphviz;
use super::spanview::write_mir_fn_spanview;
use either::Either;
use rustc_data_structures::fx::FxHashMap;
use rustc_hir::def_id::DefId;
use rustc_index::vec::Idx;
use rustc_middle::mir::interpret::{
    read_target_uint, AllocId, Allocation, ConstAllocation, ConstValue, GlobalAlloc, Pointer,
    Provenance,
};
use rustc_middle::mir::visit::Visitor;
use rustc_middle::mir::MirSource;
use rustc_middle::mir::*;
use rustc_middle::ty::{self, TyCtxt};
use rustc_target::abi::Size;

const INDENT: &str = "    ";
/// Alignment for lining up comments following MIR statements
pub(crate) const ALIGN: usize = 40;

/// An indication of where we are in the control flow graph. Used for printing
/// extra information in `dump_mir`
pub enum PassWhere {
    /// We have not started dumping the control flow graph, but we are about to.
    BeforeCFG,

    /// We just finished dumping the control flow graph. This is right before EOF
    AfterCFG,

    /// We are about to start dumping the given basic block.
    BeforeBlock(BasicBlock),

    /// We are just about to dump the given statement or terminator.
    BeforeLocation(Location),

    /// We just dumped the given statement or terminator.
    AfterLocation(Location),

    /// We just dumped the terminator for a block but not the closing `}`.
    AfterTerminator(BasicBlock),
}

/// If the session is properly configured, dumps a human-readable
/// representation of the mir into:
///
/// ```text
/// rustc.node<node_id>.<pass_num>.<pass_name>.<disambiguator>
/// ```
///
/// Output from this function is controlled by passing `-Z dump-mir=<filter>`,
/// where `<filter>` takes the following forms:
///
/// - `all` -- dump MIR for all fns, all passes, all everything
/// - a filter defined by a set of substrings combined with `&` and `|`
///   (`&` has higher precedence). At least one of the `|`-separated groups
///   must match; an `|`-separated group matches if all of its `&`-separated
///   substrings are matched.
///
/// Example:
///
/// - `nll` == match if `nll` appears in the name
/// - `foo & nll` == match if `foo` and `nll` both appear in the name
/// - `foo & nll | typeck` == match if `foo` and `nll` both appear in the name
///   or `typeck` appears in the name.
/// - `foo & nll | bar & typeck` == match if `foo` and `nll` both appear in the name
///   or `typeck` and `bar` both appear in the name.
#[inline]
pub fn dump_mir<'tcx, F>(
    tcx: TyCtxt<'tcx>,
    pass_num: Option<&dyn Display>,
    pass_name: &str,
    disambiguator: &dyn Display,
    body: &Body<'tcx>,
    extra_data: F,
) where
    F: FnMut(PassWhere, &mut dyn Write) -> io::Result<()>,
{
    if !dump_enabled(tcx, pass_name, body.source.def_id()) {
        return;
    }

    dump_matched_mir_node(tcx, pass_num, pass_name, disambiguator, body, extra_data);
}

pub fn dump_enabled<'tcx>(tcx: TyCtxt<'tcx>, pass_name: &str, def_id: DefId) -> bool {
    let Some(ref filters) = tcx.sess.opts.unstable_opts.dump_mir else {
        return false;
    };
    // see notes on #41697 below
    let node_path = ty::print::with_forced_impl_filename_line!(tcx.def_path_str(def_id));
    filters.split('|').any(|or_filter| {
        or_filter.split('&').all(|and_filter| {
            let and_filter_trimmed = and_filter.trim();
            and_filter_trimmed == "all"
                || pass_name.contains(and_filter_trimmed)
                || node_path.contains(and_filter_trimmed)
        })
    })
}

// #41697 -- we use `with_forced_impl_filename_line()` because
// `def_path_str()` would otherwise trigger `type_of`, and this can
// run while we are already attempting to evaluate `type_of`.

fn dump_matched_mir_node<'tcx, F>(
    tcx: TyCtxt<'tcx>,
    pass_num: Option<&dyn Display>,
    pass_name: &str,
    disambiguator: &dyn Display,
    body: &Body<'tcx>,
    mut extra_data: F,
) where
    F: FnMut(PassWhere, &mut dyn Write) -> io::Result<()>,
{
    let _: io::Result<()> = try {
        let mut file =
            create_dump_file(tcx, "mir", pass_num, pass_name, disambiguator, body.source)?;
        // see notes on #41697 above
        let def_path =
            ty::print::with_forced_impl_filename_line!(tcx.def_path_str(body.source.def_id()));
        write!(file, "// MIR for `{}", def_path)?;
        match body.source.promoted {
            None => write!(file, "`")?,
            Some(promoted) => write!(file, "::{:?}`", promoted)?,
        }
        writeln!(file, " {} {}", disambiguator, pass_name)?;
        if let Some(ref layout) = body.generator_layout() {
            writeln!(file, "/* generator_layout = {:#?} */", layout)?;
        }
        writeln!(file)?;
        extra_data(PassWhere::BeforeCFG, &mut file)?;
        write_user_type_annotations(tcx, body, &mut file)?;
        write_mir_fn(tcx, body, &mut extra_data, &mut file)?;
        extra_data(PassWhere::AfterCFG, &mut file)?;
    };

    if tcx.sess.opts.unstable_opts.dump_mir_graphviz {
        let _: io::Result<()> = try {
            let mut file =
                create_dump_file(tcx, "dot", pass_num, pass_name, disambiguator, body.source)?;
            write_mir_fn_graphviz(tcx, body, false, &mut file)?;
        };
    }

    if let Some(spanview) = tcx.sess.opts.unstable_opts.dump_mir_spanview {
        let _: io::Result<()> = try {
            let file_basename =
                dump_file_basename(tcx, pass_num, pass_name, disambiguator, body.source);
            let mut file = create_dump_file_with_basename(tcx, &file_basename, "html")?;
            if body.source.def_id().is_local() {
                write_mir_fn_spanview(tcx, body, spanview, &file_basename, &mut file)?;
            }
        };
    }
}

/// Returns the file basename portion (without extension) of a filename path
/// where we should dump a MIR representation output files.
fn dump_file_basename<'tcx>(
    tcx: TyCtxt<'tcx>,
    pass_num: Option<&dyn Display>,
    pass_name: &str,
    disambiguator: &dyn Display,
    source: MirSource<'tcx>,
) -> String {
    let promotion_id = match source.promoted {
        Some(id) => format!("-{:?}", id),
        None => String::new(),
    };

    let pass_num = if tcx.sess.opts.unstable_opts.dump_mir_exclude_pass_number {
        String::new()
    } else {
        match pass_num {
            None => ".-------".to_string(),
            Some(pass_num) => format!(".{}", pass_num),
        }
    };

    let crate_name = tcx.crate_name(source.def_id().krate);
    let item_name = tcx.def_path(source.def_id()).to_filename_friendly_no_crate();
    // All drop shims have the same DefId, so we have to add the type
    // to get unique file names.
    let shim_disambiguator = match source.instance {
        ty::InstanceDef::DropGlue(_, Some(ty)) => {
            // Unfortunately, pretty-printed typed are not very filename-friendly.
            // We dome some filtering.
            let mut s = ".".to_owned();
            s.extend(ty.to_string().chars().filter_map(|c| match c {
                ' ' => None,
                ':' | '<' | '>' => Some('_'),
                c => Some(c),
            }));
            s
        }
        _ => String::new(),
    };

    format!(
        "{}.{}{}{}{}.{}.{}",
        crate_name, item_name, shim_disambiguator, promotion_id, pass_num, pass_name, disambiguator,
    )
}

/// Returns the path to the filename where we should dump a given MIR.
/// Also used by other bits of code (e.g., NLL inference) that dump
/// graphviz data or other things.
fn dump_path(tcx: TyCtxt<'_>, basename: &str, extension: &str) -> PathBuf {
    let mut file_path = PathBuf::new();
    file_path.push(Path::new(&tcx.sess.opts.unstable_opts.dump_mir_dir));

    let file_name = format!("{}.{}", basename, extension,);

    file_path.push(&file_name);

    file_path
}

/// Attempts to open the MIR dump file with the given name and extension.
fn create_dump_file_with_basename(
    tcx: TyCtxt<'_>,
    file_basename: &str,
    extension: &str,
) -> io::Result<io::BufWriter<fs::File>> {
    let file_path = dump_path(tcx, file_basename, extension);
    if let Some(parent) = file_path.parent() {
        fs::create_dir_all(parent).map_err(|e| {
            io::Error::new(
                e.kind(),
                format!("IO error creating MIR dump directory: {:?}; {}", parent, e),
            )
        })?;
    }
    Ok(io::BufWriter::new(fs::File::create(&file_path).map_err(|e| {
        io::Error::new(e.kind(), format!("IO error creating MIR dump file: {:?}; {}", file_path, e))
    })?))
}

/// Attempts to open a file where we should dump a given MIR or other
/// bit of MIR-related data. Used by `mir-dump`, but also by other
/// bits of code (e.g., NLL inference) that dump graphviz data or
/// other things, and hence takes the extension as an argument.
pub fn create_dump_file<'tcx>(
    tcx: TyCtxt<'tcx>,
    extension: &str,
    pass_num: Option<&dyn Display>,
    pass_name: &str,
    disambiguator: &dyn Display,
    source: MirSource<'tcx>,
) -> io::Result<io::BufWriter<fs::File>> {
    create_dump_file_with_basename(
        tcx,
        &dump_file_basename(tcx, pass_num, pass_name, disambiguator, source),
        extension,
    )
}

/// Write out a human-readable textual representation for the given MIR.
pub fn write_mir_pretty<'tcx>(
    tcx: TyCtxt<'tcx>,
    single: Option<DefId>,
    w: &mut dyn Write,
) -> io::Result<()> {
    writeln!(w, "// WARNING: This output format is intended for human consumers only")?;
    writeln!(w, "// and is subject to change without notice. Knock yourself out.")?;

    let mut first = true;
    for def_id in dump_mir_def_ids(tcx, single) {
        if first {
            first = false;
        } else {
            // Put empty lines between all items
            writeln!(w)?;
        }

        let render_body = |w: &mut dyn Write, body| -> io::Result<()> {
            write_mir_fn(tcx, body, &mut |_, _| Ok(()), w)?;

            for body in tcx.promoted_mir(def_id) {
                writeln!(w)?;
                write_mir_fn(tcx, body, &mut |_, _| Ok(()), w)?;
            }
            Ok(())
        };

        // For `const fn` we want to render both the optimized MIR and the MIR for ctfe.
        if tcx.is_const_fn_raw(def_id) {
            render_body(w, tcx.optimized_mir(def_id))?;
            writeln!(w)?;
            writeln!(w, "// MIR FOR CTFE")?;
            // Do not use `render_body`, as that would render the promoteds again, but these
            // are shared between mir_for_ctfe and optimized_mir
            write_mir_fn(tcx, tcx.mir_for_ctfe(def_id), &mut |_, _| Ok(()), w)?;
        } else {
            let instance_mir =
                tcx.instance_mir(ty::InstanceDef::Item(ty::WithOptConstParam::unknown(def_id)));
            render_body(w, instance_mir)?;
        }
    }
    Ok(())
}

/// Write out a human-readable textual representation for the given function.
pub fn write_mir_fn<'tcx, F>(
    tcx: TyCtxt<'tcx>,
    body: &Body<'tcx>,
    extra_data: &mut F,
    w: &mut dyn Write,
) -> io::Result<()>
where
    F: FnMut(PassWhere, &mut dyn Write) -> io::Result<()>,
{
    write_mir_intro(tcx, body, w)?;
    for block in body.basic_blocks.indices() {
        extra_data(PassWhere::BeforeBlock(block), w)?;
        write_basic_block(tcx, block, body, extra_data, w)?;
        if block.index() + 1 != body.basic_blocks.len() {
            writeln!(w)?;
        }
    }

    writeln!(w, "}}")?;

    write_allocations(tcx, body, w)?;

    Ok(())
}

/// Write out a human-readable textual representation for the given basic block.
pub fn write_basic_block<'tcx, F>(
    tcx: TyCtxt<'tcx>,
    block: BasicBlock,
    body: &Body<'tcx>,
    extra_data: &mut F,
    w: &mut dyn Write,
) -> io::Result<()>
where
    F: FnMut(PassWhere, &mut dyn Write) -> io::Result<()>,
{
    let data = &body[block];

    // Basic block label at the top.
    let cleanup_text = if data.is_cleanup { " (cleanup)" } else { "" };
    writeln!(w, "{}{:?}{}: {{", INDENT, block, cleanup_text)?;

    // List of statements in the middle.
    let mut current_location = Location { block, statement_index: 0 };
    for statement in &data.statements {
        extra_data(PassWhere::BeforeLocation(current_location), w)?;
        let indented_body = format!("{0}{0}{1:?};", INDENT, statement);
        writeln!(
            w,
            "{:A$} // {}{}",
            indented_body,
            if tcx.sess.verbose() { format!("{:?}: ", current_location) } else { String::new() },
            comment(tcx, statement.source_info, body.span),
            A = ALIGN,
        )?;

        write_extra(tcx, w, |visitor| {
            visitor.visit_statement(statement, current_location);
        })?;

        extra_data(PassWhere::AfterLocation(current_location), w)?;

        current_location.statement_index += 1;
    }

    // Terminator at the bottom.
    extra_data(PassWhere::BeforeLocation(current_location), w)?;
    let indented_terminator = format!("{0}{0}{1:?};", INDENT, data.terminator().kind);
    writeln!(
        w,
        "{:A$} // {}{}",
        indented_terminator,
        if tcx.sess.verbose() { format!("{:?}: ", current_location) } else { String::new() },
        comment(tcx, data.terminator().source_info, body.span),
        A = ALIGN,
    )?;

    write_extra(tcx, w, |visitor| {
        visitor.visit_terminator(data.terminator(), current_location);
    })?;

    extra_data(PassWhere::AfterLocation(current_location), w)?;
    extra_data(PassWhere::AfterTerminator(block), w)?;

    writeln!(w, "{}}}", INDENT)
}

/// After we print the main statement, we sometimes dump extra
/// information. There's often a lot of little things "nuzzled up" in
/// a statement.
fn write_extra<'tcx, F>(tcx: TyCtxt<'tcx>, write: &mut dyn Write, mut visit_op: F) -> io::Result<()>
where
    F: FnMut(&mut ExtraComments<'tcx>),
{
    let mut extra_comments = ExtraComments { tcx, comments: vec![] };
    visit_op(&mut extra_comments);
    for comment in extra_comments.comments {
        writeln!(write, "{:A$} // {}", "", comment, A = ALIGN)?;
    }
    Ok(())
}

struct ExtraComments<'tcx> {
    tcx: TyCtxt<'tcx>,
    comments: Vec<String>,
}

impl<'tcx> ExtraComments<'tcx> {
    fn push(&mut self, lines: &str) {
        for line in lines.split('\n') {
            self.comments.push(line.to_string());
        }
    }
}

fn use_verbose<'tcx>(ty: Ty<'tcx>, fn_def: bool) -> bool {
    match *ty.kind() {
        ty::Int(_) | ty::Uint(_) | ty::Bool | ty::Char | ty::Float(_) => false,
        // Unit type
        ty::Tuple(g_args) if g_args.is_empty() => false,
        ty::Tuple(g_args) => g_args.iter().any(|g_arg| use_verbose(g_arg, fn_def)),
        ty::Array(ty, _) => use_verbose(ty, fn_def),
        ty::FnDef(..) => fn_def,
        _ => true,
    }
}

impl<'tcx> Visitor<'tcx> for ExtraComments<'tcx> {
    fn visit_constant(&mut self, constant: &Constant<'tcx>, _location: Location) {
        let Constant { span, user_ty, literal } = constant;
        if use_verbose(literal.ty(), true) {
            self.push("mir::Constant");
            self.push(&format!(
                "+ span: {}",
                self.tcx.sess.source_map().span_to_embeddable_string(*span)
            ));
            if let Some(user_ty) = user_ty {
                self.push(&format!("+ user_ty: {:?}", user_ty));
            }

            // FIXME: this is a poor version of `pretty_print_const_value`.
            let fmt_val = |val: &ConstValue<'tcx>| match val {
                ConstValue::ZeroSized => format!("<ZST>"),
                ConstValue::Scalar(s) => format!("Scalar({:?})", s),
                ConstValue::Slice { .. } => format!("Slice(..)"),
                ConstValue::ByRef { .. } => format!("ByRef(..)"),
            };

            let fmt_valtree = |valtree: &ty::ValTree<'tcx>| match valtree {
                ty::ValTree::Leaf(leaf) => format!("ValTree::Leaf({:?})", leaf),
                ty::ValTree::Branch(_) => format!("ValTree::Branch(..)"),
            };

            let val = match literal {
                ConstantKind::Ty(ct) => match ct.kind() {
                    ty::ConstKind::Param(p) => format!("Param({})", p),
                    ty::ConstKind::Unevaluated(uv) => {
                        format!(
                            "Unevaluated({}, {:?}, {:?})",
                            self.tcx.def_path_str(uv.def.did),
                            uv.substs,
                            uv.promoted,
                        )
                    }
                    ty::ConstKind::Value(val) => format!("Value({})", fmt_valtree(&val)),
                    ty::ConstKind::Error(_) => "Error".to_string(),
                    // These variants shouldn't exist in the MIR.
                    ty::ConstKind::Placeholder(_)
                    | ty::ConstKind::Infer(_)
                    | ty::ConstKind::Bound(..) => bug!("unexpected MIR constant: {:?}", literal),
                },
                ConstantKind::Unevaluated(uv, _) => {
                    format!(
                        "Unevaluated({}, {:?}, {:?})",
                        self.tcx.def_path_str(uv.def.did),
                        uv.substs,
                        uv.promoted,
                    )
                }
                // To keep the diffs small, we render this like we render `ty::Const::Value`.
                //
                // This changes once `ty::Const::Value` is represented using valtrees.
                ConstantKind::Val(val, _) => format!("Value({})", fmt_val(&val)),
            };

            // This reflects what `Const` looked liked before `val` was renamed
            // as `kind`. We print it like this to avoid having to update
            // expected output in a lot of tests.
            self.push(&format!("+ literal: Const {{ ty: {}, val: {} }}", literal.ty(), val));
        }
    }

    fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) {
        self.super_rvalue(rvalue, location);
        if let Rvalue::Aggregate(kind, _) = rvalue {
            match **kind {
                AggregateKind::Closure(def_id, substs) => {
                    self.push("closure");
                    self.push(&format!("+ def_id: {:?}", def_id));
                    self.push(&format!("+ substs: {:#?}", substs));
                }

                AggregateKind::Generator(def_id, substs, movability) => {
                    self.push("generator");
                    self.push(&format!("+ def_id: {:?}", def_id));
                    self.push(&format!("+ substs: {:#?}", substs));
                    self.push(&format!("+ movability: {:?}", movability));
                }

                AggregateKind::Adt(_, _, _, Some(user_ty), _) => {
                    self.push("adt");
                    self.push(&format!("+ user_ty: {:?}", user_ty));
                }

                _ => {}
            }
        }
    }
}

fn comment(tcx: TyCtxt<'_>, SourceInfo { span, scope }: SourceInfo, function_span: Span) -> String {
    let location = if tcx.sess.opts.unstable_opts.mir_pretty_relative_line_numbers {
        tcx.sess.source_map().span_to_relative_line_string(span, function_span)
    } else {
        tcx.sess.source_map().span_to_embeddable_string(span)
    };

    format!("scope {} at {}", scope.index(), location,)
}

/// Prints local variables in a scope tree.
fn write_scope_tree(
    tcx: TyCtxt<'_>,
    body: &Body<'_>,
    scope_tree: &FxHashMap<SourceScope, Vec<SourceScope>>,
    w: &mut dyn Write,
    parent: SourceScope,
    depth: usize,
) -> io::Result<()> {
    let indent = depth * INDENT.len();

    // Local variable debuginfo.
    for var_debug_info in &body.var_debug_info {
        if var_debug_info.source_info.scope != parent {
            // Not declared in this scope.
            continue;
        }

        let indented_debug_info = format!(
            "{0:1$}debug {2} => {3:?};",
            INDENT, indent, var_debug_info.name, var_debug_info.value,
        );

        writeln!(
            w,
            "{0:1$} // in {2}",
            indented_debug_info,
            ALIGN,
            comment(tcx, var_debug_info.source_info, body.span),
        )?;
    }

    // Local variable types.
    for (local, local_decl) in body.local_decls.iter_enumerated() {
        if (1..body.arg_count + 1).contains(&local.index()) {
            // Skip over argument locals, they're printed in the signature.
            continue;
        }

        if local_decl.source_info.scope != parent {
            // Not declared in this scope.
            continue;
        }

        let mut_str = if local_decl.mutability == Mutability::Mut { "mut " } else { "" };

        let mut indented_decl =
            format!("{0:1$}let {2}{3:?}: {4:?}", INDENT, indent, mut_str, local, local_decl.ty);
        if let Some(user_ty) = &local_decl.user_ty {
            for user_ty in user_ty.projections() {
                write!(indented_decl, " as {:?}", user_ty).unwrap();
            }
        }
        indented_decl.push(';');

        let local_name = if local == RETURN_PLACE { " return place" } else { "" };

        writeln!(
            w,
            "{0:1$} //{2} in {3}",
            indented_decl,
            ALIGN,
            local_name,
            comment(tcx, local_decl.source_info, body.span),
        )?;
    }

    let Some(children) = scope_tree.get(&parent) else {
        return Ok(());
    };

    for &child in children {
        let child_data = &body.source_scopes[child];
        assert_eq!(child_data.parent_scope, Some(parent));

        let (special, span) = if let Some((callee, callsite_span)) = child_data.inlined {
            (
                format!(
                    " (inlined {}{})",
                    if callee.def.requires_caller_location(tcx) { "#[track_caller] " } else { "" },
                    callee
                ),
                Some(callsite_span),
            )
        } else {
            (String::new(), None)
        };

        let indented_header = format!("{0:1$}scope {2}{3} {{", "", indent, child.index(), special);

        if let Some(span) = span {
            writeln!(
                w,
                "{0:1$} // at {2}",
                indented_header,
                ALIGN,
                tcx.sess.source_map().span_to_embeddable_string(span),
            )?;
        } else {
            writeln!(w, "{}", indented_header)?;
        }

        write_scope_tree(tcx, body, scope_tree, w, child, depth + 1)?;
        writeln!(w, "{0:1$}}}", "", depth * INDENT.len())?;
    }

    Ok(())
}

/// Write out a human-readable textual representation of the MIR's `fn` type and the types of its
/// local variables (both user-defined bindings and compiler temporaries).
pub fn write_mir_intro<'tcx>(
    tcx: TyCtxt<'tcx>,
    body: &Body<'_>,
    w: &mut dyn Write,
) -> io::Result<()> {
    write_mir_sig(tcx, body, w)?;
    writeln!(w, "{{")?;

    // construct a scope tree and write it out
    let mut scope_tree: FxHashMap<SourceScope, Vec<SourceScope>> = Default::default();
    for (index, scope_data) in body.source_scopes.iter().enumerate() {
        if let Some(parent) = scope_data.parent_scope {
            scope_tree.entry(parent).or_default().push(SourceScope::new(index));
        } else {
            // Only the argument scope has no parent, because it's the root.
            assert_eq!(index, OUTERMOST_SOURCE_SCOPE.index());
        }
    }

    write_scope_tree(tcx, body, &scope_tree, w, OUTERMOST_SOURCE_SCOPE, 1)?;

    // Add an empty line before the first block is printed.
    writeln!(w)?;

    Ok(())
}

/// Find all `AllocId`s mentioned (recursively) in the MIR body and print their corresponding
/// allocations.
pub fn write_allocations<'tcx>(
    tcx: TyCtxt<'tcx>,
    body: &Body<'_>,
    w: &mut dyn Write,
) -> io::Result<()> {
    fn alloc_ids_from_alloc(
        alloc: ConstAllocation<'_>,
    ) -> impl DoubleEndedIterator<Item = AllocId> + '_ {
        alloc.inner().provenance().values().map(|id| *id)
    }

    fn alloc_ids_from_const_val(val: ConstValue<'_>) -> impl Iterator<Item = AllocId> + '_ {
        match val {
            ConstValue::Scalar(interpret::Scalar::Ptr(ptr, _)) => {
                Either::Left(Either::Left(std::iter::once(ptr.provenance)))
            }
            ConstValue::Scalar(interpret::Scalar::Int { .. }) => {
                Either::Left(Either::Right(std::iter::empty()))
            }
            ConstValue::ZeroSized => Either::Left(Either::Right(std::iter::empty())),
            ConstValue::ByRef { alloc, .. } | ConstValue::Slice { data: alloc, .. } => {
                Either::Right(alloc_ids_from_alloc(alloc))
            }
        }
    }
    struct CollectAllocIds(BTreeSet<AllocId>);

    impl<'tcx> Visitor<'tcx> for CollectAllocIds {
        fn visit_constant(&mut self, c: &Constant<'tcx>, _: Location) {
            match c.literal {
                ConstantKind::Ty(_) | ConstantKind::Unevaluated(..) => {}
                ConstantKind::Val(val, _) => {
                    self.0.extend(alloc_ids_from_const_val(val));
                }
            }
        }
    }

    let mut visitor = CollectAllocIds(Default::default());
    visitor.visit_body(body);

    // `seen` contains all seen allocations, including the ones we have *not* printed yet.
    // The protocol is to first `insert` into `seen`, and only if that returns `true`
    // then push to `todo`.
    let mut seen = visitor.0;
    let mut todo: Vec<_> = seen.iter().copied().collect();
    while let Some(id) = todo.pop() {
        let mut write_allocation_track_relocs =
            |w: &mut dyn Write, alloc: ConstAllocation<'tcx>| -> io::Result<()> {
                // `.rev()` because we are popping them from the back of the `todo` vector.
                for id in alloc_ids_from_alloc(alloc).rev() {
                    if seen.insert(id) {
                        todo.push(id);
                    }
                }
                write!(w, "{}", display_allocation(tcx, alloc.inner()))
            };
        write!(w, "\n{id:?}")?;
        match tcx.try_get_global_alloc(id) {
            // This can't really happen unless there are bugs, but it doesn't cost us anything to
            // gracefully handle it and allow buggy rustc to be debugged via allocation printing.
            None => write!(w, " (deallocated)")?,
            Some(GlobalAlloc::Function(inst)) => write!(w, " (fn: {inst})")?,
            Some(GlobalAlloc::VTable(ty, Some(trait_ref))) => {
                write!(w, " (vtable: impl {trait_ref} for {ty})")?
            }
            Some(GlobalAlloc::VTable(ty, None)) => {
                write!(w, " (vtable: impl <auto trait> for {ty})")?
            }
            Some(GlobalAlloc::Static(did)) if !tcx.is_foreign_item(did) => {
                match tcx.eval_static_initializer(did) {
                    Ok(alloc) => {
                        write!(w, " (static: {}, ", tcx.def_path_str(did))?;
                        write_allocation_track_relocs(w, alloc)?;
                    }
                    Err(_) => write!(
                        w,
                        " (static: {}, error during initializer evaluation)",
                        tcx.def_path_str(did)
                    )?,
                }
            }
            Some(GlobalAlloc::Static(did)) => {
                write!(w, " (extern static: {})", tcx.def_path_str(did))?
            }
            Some(GlobalAlloc::Memory(alloc)) => {
                write!(w, " (")?;
                write_allocation_track_relocs(w, alloc)?
            }
        }
        writeln!(w)?;
    }
    Ok(())
}

/// Dumps the size and metadata and content of an allocation to the given writer.
/// The expectation is that the caller first prints other relevant metadata, so the exact
/// format of this function is (*without* leading or trailing newline):
///
/// ```text
/// size: {}, align: {}) {
///     <bytes>
/// }
/// ```
///
/// The byte format is similar to how hex editors print bytes. Each line starts with the address of
/// the start of the line, followed by all bytes in hex format (space separated).
/// If the allocation is small enough to fit into a single line, no start address is given.
/// After the hex dump, an ascii dump follows, replacing all unprintable characters (control
/// characters or characters whose value is larger than 127) with a `.`
/// This also prints provenance adequately.
pub fn display_allocation<'a, 'tcx, Prov, Extra>(
    tcx: TyCtxt<'tcx>,
    alloc: &'a Allocation<Prov, Extra>,
) -> RenderAllocation<'a, 'tcx, Prov, Extra> {
    RenderAllocation { tcx, alloc }
}

#[doc(hidden)]
pub struct RenderAllocation<'a, 'tcx, Prov, Extra> {
    tcx: TyCtxt<'tcx>,
    alloc: &'a Allocation<Prov, Extra>,
}

impl<'a, 'tcx, Prov: Provenance, Extra> std::fmt::Display
    for RenderAllocation<'a, 'tcx, Prov, Extra>
{
    fn fmt(&self, w: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let RenderAllocation { tcx, alloc } = *self;
        write!(w, "size: {}, align: {})", alloc.size().bytes(), alloc.align.bytes())?;
        if alloc.size() == Size::ZERO {
            // We are done.
            return write!(w, " {{}}");
        }
        // Write allocation bytes.
        writeln!(w, " {{")?;
        write_allocation_bytes(tcx, alloc, w, "    ")?;
        write!(w, "}}")?;
        Ok(())
    }
}

fn write_allocation_endline(w: &mut dyn std::fmt::Write, ascii: &str) -> std::fmt::Result {
    for _ in 0..(BYTES_PER_LINE - ascii.chars().count()) {
        write!(w, "   ")?;
    }
    writeln!(w, " │ {}", ascii)
}

/// Number of bytes to print per allocation hex dump line.
const BYTES_PER_LINE: usize = 16;

/// Prints the line start address and returns the new line start address.
fn write_allocation_newline(
    w: &mut dyn std::fmt::Write,
    mut line_start: Size,
    ascii: &str,
    pos_width: usize,
    prefix: &str,
) -> Result<Size, std::fmt::Error> {
    write_allocation_endline(w, ascii)?;
    line_start += Size::from_bytes(BYTES_PER_LINE);
    write!(w, "{}0x{:02$x} │ ", prefix, line_start.bytes(), pos_width)?;
    Ok(line_start)
}

/// The `prefix` argument allows callers to add an arbitrary prefix before each line (even if there
/// is only one line). Note that your prefix should contain a trailing space as the lines are
/// printed directly after it.
fn write_allocation_bytes<'tcx, Prov: Provenance, Extra>(
    tcx: TyCtxt<'tcx>,
    alloc: &Allocation<Prov, Extra>,
    w: &mut dyn std::fmt::Write,
    prefix: &str,
) -> std::fmt::Result {
    let num_lines = alloc.size().bytes_usize().saturating_sub(BYTES_PER_LINE);
    // Number of chars needed to represent all line numbers.
    let pos_width = hex_number_length(alloc.size().bytes());

    if num_lines > 0 {
        write!(w, "{}0x{:02$x} │ ", prefix, 0, pos_width)?;
    } else {
        write!(w, "{}", prefix)?;
    }

    let mut i = Size::ZERO;
    let mut line_start = Size::ZERO;

    let ptr_size = tcx.data_layout.pointer_size;

    let mut ascii = String::new();

    let oversized_ptr = |target: &mut String, width| {
        if target.len() > width {
            write!(target, " ({} ptr bytes)", ptr_size.bytes()).unwrap();
        }
    };

    while i < alloc.size() {
        // The line start already has a space. While we could remove that space from the line start
        // printing and unconditionally print a space here, that would cause the single-line case
        // to have a single space before it, which looks weird.
        if i != line_start {
            write!(w, " ")?;
        }
        if let Some(&prov) = alloc.provenance().get(&i) {
            // Memory with provenance must be defined
            assert!(alloc.init_mask().is_range_initialized(i, i + ptr_size).is_ok());
            let j = i.bytes_usize();
            let offset = alloc
                .inspect_with_uninit_and_ptr_outside_interpreter(j..j + ptr_size.bytes_usize());
            let offset = read_target_uint(tcx.data_layout.endian, offset).unwrap();
            let offset = Size::from_bytes(offset);
            let provenance_width = |bytes| bytes * 3;
            let ptr = Pointer::new(prov, offset);
            let mut target = format!("{:?}", ptr);
            if target.len() > provenance_width(ptr_size.bytes_usize() - 1) {
                // This is too long, try to save some space.
                target = format!("{:#?}", ptr);
            }
            if ((i - line_start) + ptr_size).bytes_usize() > BYTES_PER_LINE {
                // This branch handles the situation where a provenance starts in the current line
                // but ends in the next one.
                let remainder = Size::from_bytes(BYTES_PER_LINE) - (i - line_start);
                let overflow = ptr_size - remainder;
                let remainder_width = provenance_width(remainder.bytes_usize()) - 2;
                let overflow_width = provenance_width(overflow.bytes_usize() - 1) + 1;
                ascii.push('╾');
                for _ in 0..remainder.bytes() - 1 {
                    ascii.push('─');
                }
                if overflow_width > remainder_width && overflow_width >= target.len() {
                    // The case where the provenance fits into the part in the next line
                    write!(w, "╾{0:─^1$}", "", remainder_width)?;
                    line_start =
                        write_allocation_newline(w, line_start, &ascii, pos_width, prefix)?;
                    ascii.clear();
                    write!(w, "{0:─^1$}╼", target, overflow_width)?;
                } else {
                    oversized_ptr(&mut target, remainder_width);
                    write!(w, "╾{0:─^1$}", target, remainder_width)?;
                    line_start =
                        write_allocation_newline(w, line_start, &ascii, pos_width, prefix)?;
                    write!(w, "{0:─^1$}╼", "", overflow_width)?;
                    ascii.clear();
                }
                for _ in 0..overflow.bytes() - 1 {
                    ascii.push('─');
                }
                ascii.push('╼');
                i += ptr_size;
                continue;
            } else {
                // This branch handles a provenance that starts and ends in the current line.
                let provenance_width = provenance_width(ptr_size.bytes_usize() - 1);
                oversized_ptr(&mut target, provenance_width);
                ascii.push('╾');
                write!(w, "╾{0:─^1$}╼", target, provenance_width)?;
                for _ in 0..ptr_size.bytes() - 2 {
                    ascii.push('─');
                }
                ascii.push('╼');
                i += ptr_size;
            }
        } else if alloc.init_mask().is_range_initialized(i, i + Size::from_bytes(1)).is_ok() {
            let j = i.bytes_usize();

            // Checked definedness (and thus range) and provenance. This access also doesn't
            // influence interpreter execution but is only for debugging.
            let c = alloc.inspect_with_uninit_and_ptr_outside_interpreter(j..j + 1)[0];
            write!(w, "{:02x}", c)?;
            if c.is_ascii_control() || c >= 0x80 {
                ascii.push('.');
            } else {
                ascii.push(char::from(c));
            }
            i += Size::from_bytes(1);
        } else {
            write!(w, "__")?;
            ascii.push('░');
            i += Size::from_bytes(1);
        }
        // Print a new line header if the next line still has some bytes to print.
        if i == line_start + Size::from_bytes(BYTES_PER_LINE) && i != alloc.size() {
            line_start = write_allocation_newline(w, line_start, &ascii, pos_width, prefix)?;
            ascii.clear();
        }
    }
    write_allocation_endline(w, &ascii)?;

    Ok(())
}

fn write_mir_sig(tcx: TyCtxt<'_>, body: &Body<'_>, w: &mut dyn Write) -> io::Result<()> {
    use rustc_hir::def::DefKind;

    trace!("write_mir_sig: {:?}", body.source.instance);
    let def_id = body.source.def_id();
    let kind = tcx.def_kind(def_id);
    let is_function = match kind {
        DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(..) => true,
        _ => tcx.is_closure(def_id),
    };
    match (kind, body.source.promoted) {
        (_, Some(i)) => write!(w, "{:?} in ", i)?,
        (DefKind::Const | DefKind::AssocConst, _) => write!(w, "const ")?,
        (DefKind::Static(hir::Mutability::Not), _) => write!(w, "static ")?,
        (DefKind::Static(hir::Mutability::Mut), _) => write!(w, "static mut ")?,
        (_, _) if is_function => write!(w, "fn ")?,
        (DefKind::AnonConst | DefKind::InlineConst, _) => {} // things like anon const, not an item
        _ => bug!("Unexpected def kind {:?}", kind),
    }

    ty::print::with_forced_impl_filename_line! {
        // see notes on #41697 elsewhere
        write!(w, "{}", tcx.def_path_str(def_id))?
    }

    if body.source.promoted.is_none() && is_function {
        write!(w, "(")?;

        // fn argument types.
        for (i, arg) in body.args_iter().enumerate() {
            if i != 0 {
                write!(w, ", ")?;
            }
            write!(w, "{:?}: {}", Place::from(arg), body.local_decls[arg].ty)?;
        }

        write!(w, ") -> {}", body.return_ty())?;
    } else {
        assert_eq!(body.arg_count, 0);
        write!(w, ": {} =", body.return_ty())?;
    }

    if let Some(yield_ty) = body.yield_ty() {
        writeln!(w)?;
        writeln!(w, "yields {}", yield_ty)?;
    }

    write!(w, " ")?;
    // Next thing that gets printed is the opening {

    Ok(())
}

fn write_user_type_annotations(
    tcx: TyCtxt<'_>,
    body: &Body<'_>,
    w: &mut dyn Write,
) -> io::Result<()> {
    if !body.user_type_annotations.is_empty() {
        writeln!(w, "| User Type Annotations")?;
    }
    for (index, annotation) in body.user_type_annotations.iter_enumerated() {
        writeln!(
            w,
            "| {:?}: user_ty: {:?}, span: {}, inferred_ty: {:?}",
            index.index(),
            annotation.user_ty,
            tcx.sess.source_map().span_to_embeddable_string(annotation.span),
            annotation.inferred_ty,
        )?;
    }
    if !body.user_type_annotations.is_empty() {
        writeln!(w, "|")?;
    }
    Ok(())
}

pub fn dump_mir_def_ids(tcx: TyCtxt<'_>, single: Option<DefId>) -> Vec<DefId> {
    if let Some(i) = single {
        vec![i]
    } else {
        tcx.mir_keys(()).iter().map(|def_id| def_id.to_def_id()).collect()
    }
}

/// Calc converted u64 decimal into hex and return it's length in chars
///
/// ```ignore (cannot-test-private-function)
/// assert_eq!(1, hex_number_length(0));
/// assert_eq!(1, hex_number_length(1));
/// assert_eq!(2, hex_number_length(16));
/// ```
fn hex_number_length(x: u64) -> usize {
    if x == 0 {
        return 1;
    }
    let mut length = 0;
    let mut x_left = x;
    while x_left > 0 {
        x_left /= 16;
        length += 1;
    }
    length
}