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Malformed coverage data when using llvm-cov #119453
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@Zalathar I don't know how to reproduce this with a minimal example, but would appreciate it if you could somehow debug this in LLVM code. As you wrote earlier this comes from |
I debugged LLVM and this comes from the same place: https://github.com/rust-lang/llvm-project/blob/fef3d7b14ede45d051dc688aae0bb8c8b02a0566/llvm/lib/ProfileData/Coverage/CoverageMappingReader.cpp#L340-L344 |
Pinpointing the LLVM error was very helpful, thanks. Without that I wouldn’t be able to do much. Can you give me an example of the LineStart/ColumnStart/NumLines/ColumnEnd values that are present when it fails? That should give me a better idea of what’s going wrong on the Rust side. |
(I might not be able to track down the underlying issue, but hopefully I should at least be able to add some extra checks to the compiler to make sure LLVM doesn’t encounter a fatal error.) |
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I've submitted a possible workaround in #119460. It doesn't address the underlying question of why we were producing improper regions in the first place, but it does at least mean that we will detect and discard those regions early, instead of emitting them and having |
This suggests that the original coordinates were |
Spans within the compiler are always properly-ordered in terms of byte positions (enforced in I'm not sure how we're ending up with a span like that. I initially suspected |
I wonder if the span adjustment in Though if the resulting span crosses file boundaries, I would expect it to be discarded by |
@Zalathar Is there a way to find out which source file is causing the problem? I think it's pretty easy to edit the |
If you look at method That file ID should be an index into the field So you might be able to rig up something to print out that filename. |
The problem comes from the macro
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That looks like the source of the I don’t think those coordinates point anywhere meaningful in the same file, but I’m not sure what other file they could be trying to refer to. |
I don’t know what the hell is going on at |
Another piece of information that might be useful is the name of the function that has the malformed region in its coverage mappings. It looks like you should be able to dump it from But you might need to dump it before the call to |
…wiser coverage: Never emit improperly-ordered coverage regions If we emit a coverage region that is improperly ordered (end < start), `llvm-cov` will fail with `coveragemap_error::malformed`, which is inconvenient for users and also very hard to debug. Ideally we would fix the root causes of these situations, but they tend to occur in very obscure edge-case scenarios (often involving nested macros), and we don't always have a good MCVE to work from. So it makes sense to also have a catch-all check that will prevent improperly-ordered regions from ever being emitted. --- This is mainly aimed at resolving rust-lang#119453. We don't have a specific way to reproduce it, which is why I haven't been able to add a test case in this PR. But based on the information provided in that issue, this change seems likely to avoid the error in `llvm-cov`. `@rustbot` label +A-code-coverage
…wiser coverage: Never emit improperly-ordered coverage regions If we emit a coverage region that is improperly ordered (end < start), `llvm-cov` will fail with `coveragemap_error::malformed`, which is inconvenient for users and also very hard to debug. Ideally we would fix the root causes of these situations, but they tend to occur in very obscure edge-case scenarios (often involving nested macros), and we don't always have a good MCVE to work from. So it makes sense to also have a catch-all check that will prevent improperly-ordered regions from ever being emitted. --- This is mainly aimed at resolving rust-lang#119453. We don't have a specific way to reproduce it, which is why I haven't been able to add a test case in this PR. But based on the information provided in that issue, this change seems likely to avoid the error in `llvm-cov`. ``@rustbot`` label +A-code-coverage
…wiser coverage: Never emit improperly-ordered coverage regions If we emit a coverage region that is improperly ordered (end < start), `llvm-cov` will fail with `coveragemap_error::malformed`, which is inconvenient for users and also very hard to debug. Ideally we would fix the root causes of these situations, but they tend to occur in very obscure edge-case scenarios (often involving nested macros), and we don't always have a good MCVE to work from. So it makes sense to also have a catch-all check that will prevent improperly-ordered regions from ever being emitted. --- This is mainly aimed at resolving rust-lang#119453. We don't have a specific way to reproduce it, which is why I haven't been able to add a test case in this PR. But based on the information provided in that issue, this change seems likely to avoid the error in `llvm-cov`. ``@rustbot`` label +A-code-coverage
…wiser coverage: Never emit improperly-ordered coverage regions If we emit a coverage region that is improperly ordered (end < start), `llvm-cov` will fail with `coveragemap_error::malformed`, which is inconvenient for users and also very hard to debug. Ideally we would fix the root causes of these situations, but they tend to occur in very obscure edge-case scenarios (often involving nested macros), and we don't always have a good MCVE to work from. So it makes sense to also have a catch-all check that will prevent improperly-ordered regions from ever being emitted. --- This is mainly aimed at resolving rust-lang#119453. We don't have a specific way to reproduce it, which is why I haven't been able to add a test case in this PR. But based on the information provided in that issue, this change seems likely to avoid the error in `llvm-cov`. ```@rustbot``` label +A-code-coverage
…wiser coverage: Never emit improperly-ordered coverage regions If we emit a coverage region that is improperly ordered (end < start), `llvm-cov` will fail with `coveragemap_error::malformed`, which is inconvenient for users and also very hard to debug. Ideally we would fix the root causes of these situations, but they tend to occur in very obscure edge-case scenarios (often involving nested macros), and we don't always have a good MCVE to work from. So it makes sense to also have a catch-all check that will prevent improperly-ordered regions from ever being emitted. --- This is mainly aimed at resolving rust-lang#119453. We don't have a specific way to reproduce it, which is why I haven't been able to add a test case in this PR. But based on the information provided in that issue, this change seems likely to avoid the error in `llvm-cov`. ````@rustbot```` label +A-code-coverage
…wiser coverage: Never emit improperly-ordered coverage regions If we emit a coverage region that is improperly ordered (end < start), `llvm-cov` will fail with `coveragemap_error::malformed`, which is inconvenient for users and also very hard to debug. Ideally we would fix the root causes of these situations, but they tend to occur in very obscure edge-case scenarios (often involving nested macros), and we don't always have a good MCVE to work from. So it makes sense to also have a catch-all check that will prevent improperly-ordered regions from ever being emitted. --- This is mainly aimed at resolving rust-lang#119453. We don't have a specific way to reproduce it, which is why I haven't been able to add a test case in this PR. But based on the information provided in that issue, this change seems likely to avoid the error in `llvm-cov`. `````@rustbot````` label +A-code-coverage
Rollup merge of rust-lang#119460 - Zalathar:improper-region, r=wesleywiser coverage: Never emit improperly-ordered coverage regions If we emit a coverage region that is improperly ordered (end < start), `llvm-cov` will fail with `coveragemap_error::malformed`, which is inconvenient for users and also very hard to debug. Ideally we would fix the root causes of these situations, but they tend to occur in very obscure edge-case scenarios (often involving nested macros), and we don't always have a good MCVE to work from. So it makes sense to also have a catch-all check that will prevent improperly-ordered regions from ever being emitted. --- This is mainly aimed at resolving rust-lang#119453. We don't have a specific way to reproduce it, which is why I haven't been able to add a test case in this PR. But based on the information provided in that issue, this change seems likely to avoid the error in `llvm-cov`. `````@rustbot````` label +A-code-coverage
FTR I was seeing the same issue when running @Zalathar thanks for your patch! |
I tried to fuzz our substrate runtime but getting error:
How to reproduce (on our large repo)
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rustc --version --verbose
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