sync adding nounwind attribute with generating abort-on-panic shim #63884
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RalfJung
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RalfJung
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| // Foreign items like `extern "C" { fn foo(); }` are assumed not to | ||
| // unwind | ||
| // Foreign items like `extern "C" { fn foo(); }` and `extern "Rust" { fn bar(); }` | ||
| // are assumed not to unwind. |
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Do we really want to assume that an imported extern "Rust" { fn bar(); } does not unwind? I just expanded the comment here to describe already existing behavior.
Cc @gnzlbg
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Do we really want to assume that an imported extern "Rust" { fn bar(); } does not unwind?
IIRC, "Rust", "platform-intrinsic", "rust-intrinsic", and "rustcall" are actually the same ABI, and it is ok for extern declarations of those to actually unwind. One such a declaration would be the integer add intrinsic that panics on integer overflow. We also sometimes import llvm intrinsics (via #[feature(link_llvm_intrinsics(]) using the "unadjusted" ABI. I'm not sure if that one should be able to unwind as well.
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My personal inclination is to just remove the foreign_item case here. But that decision should probably be made by someone who actually knows the surrounding code.
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In fact I had to remove that branch to make the codegen tests work as expected. Whatever that means.
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src/librustc/ty/context.rs
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| @@ -1581,6 +1581,32 @@ impl<'tcx> TyCtxt<'tcx> { | |||
| pub fn has_strict_asm_symbol_naming(&self) -> bool { | |||
| self.gcx.sess.target.target.arch.contains("nvptx") | |||
| } | |||
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| /// Determine if this function gets a shim to catch panics and abort. | |||
| pub fn abort_on_panic_shim(&self, fn_def_id: DefId, abi: abi::Abi) -> bool { | |||
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I had no idea what the right place would be for this method. Suggestions?
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The job Click to expand the log.I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact |
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Adjusted and expanded the failing test. I tried for a long time to also adjust and expand |
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The job Click to expand the log.I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact |
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Hm, incremental thinlto tests are failing and I have no idea why, |
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@Centril I am not entirely sure why you nominated this for T-lang? This is a bugfix, solving the problem that the comments in LLVM codegen are wrong (they say we add abort-on-panic shims but we don't). #62603 seems like the more interesting one from a T-lang perspective, that one actually changed program behavior. |
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I felt like this PR did a bit too much for backporting, so I moved the soundness-fix part into a separate PR: #63909. This PR here is now based on that. Here's the relative diff. |
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Why is this nominated for beta ? AFAICT this only fixes a bug in a unstable Rust feature right ? |
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Does it remove the |
No, it (or rather, #63909) removes the This PR here is not nominated for backport any more.
#63909 does. This PR includes that one. That is already reflected in the PR message. |
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Marking as blocked and removing nomination; that has been moved to #63909. |
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☔ The latest upstream changes (presumably #64264) made this pull request unmergeable. Please resolve the merge conflicts. |
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Currently, the code paths for deciding whether to add an abort-on-panic shim, and whether to add the
nounwindattribute, are separate. This unifies them. As a consequence, we now add anounwindattribute to#[unwind(aborts)]functions.The logic is also changed slightly to not take the call ABI into account any more. Fixes #63883.
Based on #63909, relative diff.