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coverage: Discard spans that fill the entire function body

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When we try to extract coverage-relevant spans from MIR, sometimes we see MIR
statements/terminators whose spans cover the entire function body. Those spans
tend to be unhelpful for coverage purposes, because they often represent
compiler-inserted code, e.g. the implicit return value of `()`.
This commit is contained in:
Zalathar 2024-02-15 18:12:27 +11:00
parent 75af3c58f9
commit cd9021e8cb
10 changed files with 29 additions and 33 deletions
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13
compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs
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@ -132,18 +132,23 @@ fn bcb_to_initial_coverage_spans<'a, 'tcx>(
bcb_data.basic_blocks.iter().flat_map(move |&bb| {
let data = &mir_body[bb];
let unexpand = move |expn_span| {
unexpand_into_body_span_with_visible_macro(expn_span, body_span)
// Discard any spans that fill the entire body, because they tend
// to represent compiler-inserted code, e.g. implicitly returning `()`.
.filter(|(span, _)| !span.source_equal(body_span))
};
let statement_spans = data.statements.iter().filter_map(move |statement| {
let expn_span = filtered_statement_span(statement)?;
let (span, visible_macro) =
unexpand_into_body_span_with_visible_macro(expn_span, body_span)?;
let (span, visible_macro) = unexpand(expn_span)?;
Some(SpanFromMir::new(span, visible_macro, bcb, is_closure_like(statement)))
});
let terminator_span = Some(data.terminator()).into_iter().filter_map(move |terminator| {
let expn_span = filtered_terminator_span(terminator)?;
let (span, visible_macro) =
unexpand_into_body_span_with_visible_macro(expn_span, body_span)?;
let (span, visible_macro) = unexpand(expn_span)?;
Some(SpanFromMir::new(span, visible_macro, bcb, false))
});

6
tests/coverage/closure_unit_return.cov-map
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@ -16,13 +16,13 @@ Number of file 0 mappings: 1
- Code(Zero) at (prev + 8, 22) to (start + 2, 6)
Function name: closure_unit_return::implicit_unit
Raw bytes (14): 0x[01, 01, 00, 02, 01, 10, 01, 01, 13, 01, 03, 06, 04, 02]
Raw bytes (14): 0x[01, 01, 00, 02, 01, 10, 01, 01, 10, 01, 05, 05, 02, 02]
Number of files: 1
- file 0 => global file 1
Number of expressions: 0
Number of file 0 mappings: 2
- Code(Counter(0)) at (prev + 16, 1) to (start + 1, 19)
- Code(Counter(0)) at (prev + 3, 6) to (start + 4, 2)
- Code(Counter(0)) at (prev + 16, 1) to (start + 1, 16)
- Code(Counter(0)) at (prev + 5, 5) to (start + 2, 2)
Function name: closure_unit_return::implicit_unit::{closure#0} (unused)
Raw bytes (9): 0x[01, 01, 00, 01, 00, 11, 16, 02, 06]

4
tests/coverage/closure_unit_return.coverage
View File

@ -16,8 +16,8 @@
LL| 1|fn implicit_unit() {
LL| 1| let closure = || {
LL| 0| ();
LL| 1| };
LL| 1|
LL| 0| };
LL| |
LL| 1| drop(closure);
LL| 1| // implicit return of `()`
LL| 1|}

8
tests/coverage/coverage_attr_closure.cov-map
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@ -15,14 +15,14 @@ Number of file 0 mappings: 1
- Code(Zero) at (prev + 29, 19) to (start + 2, 6)
Function name: coverage_attr_closure::contains_closures_on
Raw bytes (19): 0x[01, 01, 00, 03, 01, 0f, 01, 02, 05, 01, 04, 06, 02, 05, 01, 04, 06, 01, 02]
Raw bytes (19): 0x[01, 01, 00, 03, 01, 0f, 01, 01, 1a, 01, 05, 09, 00, 1b, 01, 04, 01, 00, 02]
Number of files: 1
- file 0 => global file 1
Number of expressions: 0
Number of file 0 mappings: 3
- Code(Counter(0)) at (prev + 15, 1) to (start + 2, 5)
- Code(Counter(0)) at (prev + 4, 6) to (start + 2, 5)
- Code(Counter(0)) at (prev + 4, 6) to (start + 1, 2)
- Code(Counter(0)) at (prev + 15, 1) to (start + 1, 26)
- Code(Counter(0)) at (prev + 5, 9) to (start + 0, 27)
- Code(Counter(0)) at (prev + 4, 1) to (start + 0, 2)
Function name: coverage_attr_closure::contains_closures_on::{closure#0} (unused)
Raw bytes (9): 0x[01, 01, 00, 01, 00, 11, 13, 02, 06]

8
tests/coverage/coverage_attr_closure.coverage
View File

@ -14,13 +14,13 @@
LL| |#[coverage(on)]
LL| 1|fn contains_closures_on() {
LL| 1| let _local_closure_on = #[coverage(on)]
LL| 1| |input: &str| {
LL| 0| |input: &str| {
LL| 0| println!("{input}");
LL| 1| };
LL| 0| };
LL| 1| let _local_closure_off = #[coverage(off)]
LL| 1| |input: &str| {
LL| | |input: &str| {
LL| | println!("{input}");
LL| 1| };
LL| | };
LL| 1|}
LL| |
LL| |#[coverage(off)]

6
tests/coverage/inline-dead.cov-map
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@ -22,13 +22,13 @@ Number of file 0 mappings: 4
= (Zero + (c0 - Zero))
Function name: inline_dead::main
Raw bytes (14): 0x[01, 01, 00, 02, 01, 04, 01, 03, 0d, 01, 05, 06, 02, 02]
Raw bytes (14): 0x[01, 01, 00, 02, 01, 04, 01, 03, 0a, 01, 06, 05, 01, 02]
Number of files: 1
- file 0 => global file 1
Number of expressions: 0
Number of file 0 mappings: 2
- Code(Counter(0)) at (prev + 4, 1) to (start + 3, 13)
- Code(Counter(0)) at (prev + 5, 6) to (start + 2, 2)
- Code(Counter(0)) at (prev + 4, 1) to (start + 3, 10)
- Code(Counter(0)) at (prev + 6, 5) to (start + 1, 2)
Function name: inline_dead::main::{closure#0}
Raw bytes (23): 0x[01, 01, 02, 00, 06, 01, 00, 03, 01, 07, 17, 01, 16, 00, 01, 17, 00, 18, 03, 01, 05, 00, 06]

4
tests/coverage/macro_name_span.cov-map
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@ -1,10 +1,10 @@
Function name: macro_name_span::affected_function
Raw bytes (9): 0x[01, 01, 00, 01, 01, 16, 1c, 02, 06]
Raw bytes (9): 0x[01, 01, 00, 01, 01, 16, 1c, 01, 40]
Number of files: 1
- file 0 => global file 1
Number of expressions: 0
Number of file 0 mappings: 1
- Code(Counter(0)) at (prev + 22, 28) to (start + 2, 6)
- Code(Counter(0)) at (prev + 22, 28) to (start + 1, 64)
Function name: macro_name_span::main
Raw bytes (9): 0x[01, 01, 00, 01, 01, 0b, 01, 02, 02]

2
tests/coverage/macro_name_span.coverage
View File

@ -21,6 +21,6 @@
LL| |macro_name_span_helper::macro_that_defines_a_function! {
LL| 1| fn affected_function() {
LL| 1| macro_with_an_unreasonably_and_egregiously_long_name!();
LL| 1| }
LL| | }
LL| |}

8
tests/coverage/unicode.cov-map
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@ -27,14 +27,6 @@ Number of file 0 mappings: 9
- Code(Expression(5, Add)) at (prev + 2, 5) to (start + 1, 2)
= (c4 + ((((c0 + c1) - c1) - c2) + c3))
Function name: unicode::サビ
Raw bytes (9): 0x[01, 01, 00, 01, 01, 1e, 14, 00, 18]
Number of files: 1
- file 0 => global file 1
Number of expressions: 0
Number of file 0 mappings: 1
- Code(Counter(0)) at (prev + 30, 20) to (start + 0, 24)
Function name: unicode::他 (unused)
Raw bytes (9): 0x[01, 01, 00, 01, 00, 1e, 19, 00, 25]
Number of files: 1

3
tests/coverage/unicode.coverage
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@ -29,8 +29,7 @@
LL| |
LL| |macro_rules! macro_that_defines_a_function {
LL| | (fn $名:ident () $体:tt) => {
LL| 1| fn $名 () $体 fn 他 () {}
^0
LL| 0| fn $名 () $体 fn 他 () {}
LL| | }
LL| |}
LL| |