bjoernager/rust
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Auto merge of #84295 - richkadel:continue-coverage, r=tmandry

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Add coverage to continue statements

`continue` statements were missing coverage. This was particularly
noticeable in a match pattern that contained only a `continue`
statement, leaving the branch appear uncounted. This PR addresses the
problem and adds tests to prove it.

r? `@tmandry`
cc: `@wesleywiser`
This commit is contained in:
bors 2021-04-20 03:08:24 +00:00
commit b2c20b51ed
4 changed files with 161 additions and 2 deletions
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15
compiler/rustc_mir_build/src/build/scope.rs
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@ -618,6 +618,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
}
} else {
assert!(value.is_none(), "`return` and `break` should have a destination");
if self.tcx.sess.instrument_coverage() {
// Unlike `break` and `return`, which push an `Assign` statement to MIR, from which
// a Coverage code region can be generated, `continue` needs no `Assign`; but
// without one, the `InstrumentCoverage` MIR pass cannot generate a code region for
// `continue`. Coverage will be missing unless we add a dummy `Assign` to MIR.
self.add_dummy_assignment(&span, block, source_info);
}
}
let region_scope = self.scopes.breakable_scopes[break_index].region_scope;
@ -643,6 +650,14 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
self.cfg.start_new_block().unit()
}
// Add a dummy `Assign` statement to the CFG, with the span for the source code's `continue`
// statement.
fn add_dummy_assignment(&mut self, span: &Span, block: BasicBlock, source_info: SourceInfo) {
let local_decl = LocalDecl::new(self.tcx.mk_unit(), *span).internal();
let temp_place = Place::from(self.local_decls.push(local_decl));
self.cfg.push_assign_unit(block, source_info, temp_place, self.tcx);
}
crate fn exit_top_scope(
&mut self,
mut block: BasicBlock,