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

//! Some facilities for tracking how codegen-units are reused during incremental
//! compilation. This is used for incremental compilation tests and debug
//! output.

use crate::errors::{CguNotRecorded, IncorrectCguReuseType};
use crate::Session;
use rustc_data_structures::fx::FxHashMap;
use rustc_errors::{DiagnosticArgValue, IntoDiagnosticArg};
use rustc_span::{Span, Symbol};
use std::borrow::Cow;
use std::fmt::{self};
use std::sync::{Arc, Mutex};

#[derive(Copy, Clone, Debug, PartialEq, PartialOrd)]
pub enum CguReuse {
    No,
    PreLto,
    PostLto,
}

impl fmt::Display for CguReuse {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match *self {
            CguReuse::No => write!(f, "No"),
            CguReuse::PreLto => write!(f, "PreLto "),
            CguReuse::PostLto => write!(f, "PostLto "),
        }
    }
}

impl IntoDiagnosticArg for CguReuse {
    fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
        DiagnosticArgValue::Str(Cow::Owned(self.to_string()))
    }
}

#[derive(Copy, Clone, Debug, PartialEq)]
pub enum ComparisonKind {
    Exact,
    AtLeast,
}

struct TrackerData {
    actual_reuse: FxHashMap<String, CguReuse>,
    expected_reuse: FxHashMap<String, (String, SendSpan, CguReuse, ComparisonKind)>,
}

// Span does not implement `Send`, so we can't just store it in the shared
// `TrackerData` object. Instead of splitting up `TrackerData` into shared and
// non-shared parts (which would be complicated), we just mark the `Span` here
// explicitly as `Send`. That's safe because the span data here is only ever
// accessed from the main thread.
struct SendSpan(Span);
unsafe impl Send for SendSpan {}

#[derive(Clone)]
pub struct CguReuseTracker {
    data: Option<Arc<Mutex<TrackerData>>>,
}

impl CguReuseTracker {
    pub fn new() -> CguReuseTracker {
        let data =
            TrackerData { actual_reuse: Default::default(), expected_reuse: Default::default() };

        CguReuseTracker { data: Some(Arc::new(Mutex::new(data))) }
    }

    pub fn new_disabled() -> CguReuseTracker {
        CguReuseTracker { data: None }
    }

    pub fn set_actual_reuse(&self, cgu_name: &str, kind: CguReuse) {
        if let Some(ref data) = self.data {
            debug!("set_actual_reuse({cgu_name:?}, {kind:?})");

            let prev_reuse = data.lock().unwrap().actual_reuse.insert(cgu_name.to_string(), kind);

            if let Some(prev_reuse) = prev_reuse {
                // The only time it is legal to overwrite reuse state is when
                // we discover during ThinLTO that we can actually reuse the
                // post-LTO version of a CGU.
                assert_eq!(prev_reuse, CguReuse::PreLto);
            }
        }
    }

    pub fn set_expectation(
        &self,
        cgu_name: Symbol,
        cgu_user_name: &str,
        error_span: Span,
        expected_reuse: CguReuse,
        comparison_kind: ComparisonKind,
    ) {
        if let Some(ref data) = self.data {
            debug!("set_expectation({cgu_name:?}, {expected_reuse:?}, {comparison_kind:?})");
            let mut data = data.lock().unwrap();

            data.expected_reuse.insert(
                cgu_name.to_string(),
                (cgu_user_name.to_string(), SendSpan(error_span), expected_reuse, comparison_kind),
            );
        }
    }

    pub fn check_expected_reuse(&self, sess: &Session) {
        if let Some(ref data) = self.data {
            let data = data.lock().unwrap();

            for (cgu_name, &(ref cgu_user_name, ref error_span, expected_reuse, comparison_kind)) in
                &data.expected_reuse
            {
                if let Some(&actual_reuse) = data.actual_reuse.get(cgu_name) {
                    let (error, at_least) = match comparison_kind {
                        ComparisonKind::Exact => (expected_reuse != actual_reuse, false),
                        ComparisonKind::AtLeast => (actual_reuse < expected_reuse, true),
                    };

                    if error {
                        let at_least = if at_least { 1 } else { 0 };
                        IncorrectCguReuseType {
                            span: error_span.0,
                            cgu_user_name: &cgu_user_name,
                            actual_reuse,
                            expected_reuse,
                            at_least,
                        };
                    }
                } else {
                    sess.emit_fatal(CguNotRecorded { cgu_user_name, cgu_name });
                }
            }
        }
    }
}