bjoernager/rust
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Fixes reported bugs in Rust Coverage

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Fixes: #79569

Fixes: #79566
Fixes: #79565

For the first issue (#79569), I got hit a `debug_assert!()` before
encountering the reported error message (because I have `debug = true`
enabled in my config.toml).

The assertion showed me that some `SwitchInt`s can have more than one
target pointing to the same `BasicBlock`.

I had thought that was invalid, but since it seems to be possible, I'm
allowing this now.

I added a new test for this.

----

In the last two cases above, both tests (intentionally) fail to compile,
but the `InstrumentCoverage` pass is invoked anyway.

The MIR starts with an `Unreachable` `BasicBlock`, which I hadn't
encountered before. (I had assumed the `InstrumentCoverage` pass
would only be invoked with MIRs from successful compilations.)

I don't have test infrastructure set up to test coverage on files that
fail to compile, so I didn't add a new test.
This commit is contained in:
Rich Kadel 2020-12-11 18:28:37 -08:00
parent 9eb3a7ceaf
commit eb963ffe45
8 changed files with 553 additions and 18 deletions
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8
compiler/rustc_mir/src/transform/coverage/mod.rs
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@ -78,6 +78,14 @@ impl<'tcx> MirPass<'tcx> for InstrumentCoverage {
return;
}
match mir_body.basic_blocks()[mir::START_BLOCK].terminator().kind {
TerminatorKind::Unreachable => {
trace!("InstrumentCoverage skipped for unreachable `START_BLOCK`");
return;
}
_ => {}
}
trace!("InstrumentCoverage starting for {:?}", mir_source.def_id());
Instrumentor::new(&self.name(), tcx, mir_body).inject_counters();
trace!("InstrumentCoverage starting for {:?}", mir_source.def_id());