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
|
use rustc_span::source_map::SourceMap;
use rustc_span::{BytePos, Pos, SourceFile, Span};
use tracing::debug;
use crate::coverageinfo::ffi;
use crate::coverageinfo::mapgen::LocalFileId;
/// Line and byte-column coordinates of a source code span within some file.
/// The file itself must be tracked separately.
#[derive(Clone, Copy, Debug)]
pub(crate) struct Coords {
/// 1-based starting line of the source code span.
pub(crate) start_line: u32,
/// 1-based starting column (in bytes) of the source code span.
pub(crate) start_col: u32,
/// 1-based ending line of the source code span.
pub(crate) end_line: u32,
/// 1-based ending column (in bytes) of the source code span. High bit must be unset.
pub(crate) end_col: u32,
}
impl Coords {
/// Attaches a local file ID to these coordinates to produce an `ffi::CoverageSpan`.
pub(crate) fn make_coverage_span(&self, local_file_id: LocalFileId) -> ffi::CoverageSpan {
let &Self { start_line, start_col, end_line, end_col } = self;
let file_id = local_file_id.as_u32();
ffi::CoverageSpan { file_id, start_line, start_col, end_line, end_col }
}
}
/// Converts the span into its start line and column, and end line and column.
///
/// Line numbers and column numbers are 1-based. Unlike most column numbers emitted by
/// the compiler, these column numbers are denoted in **bytes**, because that's what
/// LLVM's `llvm-cov` tool expects to see in coverage maps.
///
/// Returns `None` if the conversion failed for some reason. This should be uncommon,
/// but it's hard to rule out entirely (especially in the presence of complex macros
/// or other expansions), and if it does happen then skipping a span or function is
/// better than an ICE or `llvm-cov` failure that the user might have no way to avoid.
pub(crate) fn make_coords(source_map: &SourceMap, file: &SourceFile, span: Span) -> Option<Coords> {
if span.is_empty() {
debug_assert!(false, "can't make coords from empty span: {span:?}");
return None;
}
let lo = span.lo();
let hi = span.hi();
// Column numbers need to be in bytes, so we can't use the more convenient
// `SourceMap` methods for looking up file coordinates.
let line_and_byte_column = |pos: BytePos| -> Option<(usize, usize)> {
let rpos = file.relative_position(pos);
let line_index = file.lookup_line(rpos)?;
let line_start = file.lines()[line_index];
// Line numbers and column numbers are 1-based, so add 1 to each.
Some((line_index + 1, (rpos - line_start).to_usize() + 1))
};
let (mut start_line, start_col) = line_and_byte_column(lo)?;
let (mut end_line, end_col) = line_and_byte_column(hi)?;
// Apply an offset so that code in doctests has correct line numbers.
// FIXME(#79417): Currently we have no way to offset doctest _columns_.
start_line = source_map.doctest_offset_line(&file.name, start_line);
end_line = source_map.doctest_offset_line(&file.name, end_line);
check_coords(Coords {
start_line: start_line as u32,
start_col: start_col as u32,
end_line: end_line as u32,
end_col: end_col as u32,
})
}
/// If `llvm-cov` sees a source region that is improperly ordered (end < start),
/// it will immediately exit with a fatal error. To prevent that from happening,
/// discard regions that are improperly ordered, or might be interpreted in a
/// way that makes them improperly ordered.
fn check_coords(coords: Coords) -> Option<Coords> {
let Coords { start_line, start_col, end_line, end_col } = coords;
// Line/column coordinates are supposed to be 1-based. If we ever emit
// coordinates of 0, `llvm-cov` might misinterpret them.
let all_nonzero = [start_line, start_col, end_line, end_col].into_iter().all(|x| x != 0);
// Coverage mappings use the high bit of `end_col` to indicate that a
// region is actually a "gap" region, so make sure it's unset.
let end_col_has_high_bit_unset = (end_col & (1 << 31)) == 0;
// If a region is improperly ordered (end < start), `llvm-cov` will exit
// with a fatal error, which is inconvenient for users and hard to debug.
let is_ordered = (start_line, start_col) <= (end_line, end_col);
if all_nonzero && end_col_has_high_bit_unset && is_ordered {
Some(coords)
} else {
debug!(
?coords,
?all_nonzero,
?end_col_has_high_bit_unset,
?is_ordered,
"Skipping source region that would be misinterpreted or rejected by LLVM"
);
// If this happens in a debug build, ICE to make it easier to notice.
debug_assert!(false, "Improper source region: {coords:?}");
None
}
}
|
