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Enable verification for 1/32th of queries loaded from disk #90361
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(rust-highfive has picked a reviewer for you, use r? to override) |
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Thanks, @Mark-Simulacrum! I'm in favor of doing this but I wonder if we should discuss it with the wider compiler team.
// should limit us to checking every `2^5`th hash. This reduces the | ||
// number of hashes we check low enough that the overhead of | ||
// verification is acceptable to always enable. | ||
let try_verify = prev_fingerprint.as_value().1 & 0x1f == 0; |
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x % 32 == 0
and x & 0b11111 == 0
compile to the same assembly. I think x % 32
is easier to read.
(see https://play.rust-lang.org/?
version=stable&mode=release&edition=2021&gist=9fac0eb991024affb003e069ded6d334)
// verification is acceptable to always enable. | ||
let try_verify = prev_fingerprint.as_value().1 & 0x1f == 0; | ||
if try_verify | ||
|| unlikely!(tcx.dep_context().sess().opts.debugging_opts.incremental_verify_ich) |
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I think we should wrap the entire condition in unlikely!()
as in if unlikely!(try_verify || ...)
-- because we already know that try_verify
is unlikely to be true too.
Nominating for discussion in the triage meeting. I think this is a good idea but it does cause a bit of a performance regression and, more importantly, we want to be prepared for new unstable fingerprint errors if they start to show up. |
This would address (partially) #85783. |
How stable is the behaviour? If there is an assertion error but it's only in 1 of 32 cases, it seems to make bugs harder reproducible for users, especially as the user tries around and it doesn't reproduce. |
HashStable should be reliable enough that this is deterministically triggered, I believe, but it's also the case that anyone seeking to reproduce the behavior likely should enable -Zincremental-verify-ich to just verify all hashes (accepting the performance hit). I don't think that should break hash consistency for most cases. |
If you get an assertion error that you want to reproduce you can re-run with |
59dbb8c
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I'm just worried because even now a lot of the incr comp assertion failures manifest themselves to users say once per day of usage, or maybe even more rarely. The bug reports are formulated similarly vaguely, and one has to rely on the bug being hit often enough by enough people so that it can be pinned down. A flag that enables unconditional incr comp assertion checking is definitely helpful and gives an actionable tool to debug an incr comp issue. |
I don't think we should mention -Z flags in the error because in practice most users probably aren't on nightly (and checking for ability to use feature flags feels excessive). It's also true that AFAIK reproducing these is pretty difficult regardless, as @est31 mentions, and from what I've seen in bug reports if we don't get the incremental state packaged up by the user we often need to just "intelligently guess" for the most part. So I don't in practice think end-users being able to reproduce is likely to be that important: we may get less bug reports in the sense that a recompilation fixes it, but that's already often the case today (e.g., if you happen to save in your editor after starting the main compilation), so I don't know that this is a meaningful shift. Once we get that reproduction having rustc contributors/developers work with the code while minifying with the preexisting -Z flag seems fine. I also am fairly sure that this should be deterministic in the sense that we're verifying the same results on each compilation, so it shouldn't be much of a change from before. |
@bors try @rust-timer queue |
Awaiting bors try build completion. @rustbot label: +S-waiting-on-perf |
⌛ Trying commit 49e7c99 with merge 4bcc562cf44466242182a4c92eae6f3002308e17... |
Since we didn't get to discuss this in the triage meeting two times in a row now, I'm planning to just r+ this (if the performance hit is indeed acceptable). We are still some time away from the next release and this can be quickly reverted if necessary. We'll just have to keep an eye out for bug reports. |
☀️ Try build successful - checks-actions |
Queued 4bcc562cf44466242182a4c92eae6f3002308e17 with parent 27143a9, future comparison URL. |
Finished benchmarking commit (4bcc562cf44466242182a4c92eae6f3002308e17): comparison url. Summary: This change led to very large relevant regressions 😿 in compiler performance.
If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf. Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR led to changes in compiler perf. Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @bors rollup=never |
Results do not significantly differ from the previous ones (see PR description for the link), and I think they're OK. We can reduce the impact with a smaller fraction being processed (for example, 1/64), but I think that there's a certain level of diminishing returns -- most affected benchmarks are incr-unchanged, and the few println or other patchsets are only slightly affected. I think the potential for catching bugs is higher the more we check, so I'd rather not reduce without strong motivation. |
OK, I'm going to approve this now under the assumption that we will turn the check off again if it causes trouble (e.g. many false positives that aren't easily fixed). This PR is known to introduce a large regression (up to 5.78% instruction count) for a small number of benchmarks, and small regression for many other @rustbot label: +perf-regression-triaged The PR is still nominated for discussion in the triage meeting. It's trivial to revert so I don't want to block it any longer. @bors r+ |
📌 Commit 49e7c99 has been approved by |
☀️ Test successful - checks-actions |
Finished benchmarking commit (495322d): comparison url. Summary: This change led to very large relevant regressions 😿 in compiler performance.
If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf. Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression |
Pkgsrc changes: * Bump available bootstraps to 1.57.0. * For some reason, the vendor/libc checksums don't need fixing. * Bump required external LLVM to 12.0, according to upstream change log. * Adapt the Darwin linker patch. (For some reason I've not figured out yet, cargo is a lot more verbose while building, echoes the rustc invocation.) Upstream changes: Version 1.58.1 (2022-01-19) =========================== * Fix race condition in `std::fs::remove_dir_all` ([CVE-2022-21658]) * [Handle captured arguments in the `useless_format` Clippy lint][clippy/8295] * [Move `non_send_fields_in_send_ty` Clippy lint to nursery][clippy/8075] * [Fix wrong error message displayed when some imports are missing][91254] * [Fix rustfmt not formatting generated files from stdin][92912] [CVE-2022-21658]: https://www.cve.org/CVERecord?id=CVE-2022-21658] [91254]: rust-lang/rust#91254 [92912]: rust-lang/rust#92912 [clippy/8075]: rust-lang/rust-clippy#8075 [clippy/8295]: rust-lang/rust-clippy#8295 Version 1.58.0 (2022-01-13) ========================== Language -------- - [Format strings can now capture arguments simply by writing `{ident}` in the string.][90473] This works in all macros accepting format strings. Support for this in `panic!` (`panic!("{ident}")`) requires the 2021 edition; panic invocations in previous editions that appear to be trying to use this will result in a warning lint about not having the intended effect. - [`*const T` pointers can now be dereferenced in const contexts.][89551] - [The rules for when a generic struct implements `Unsize` have been relaxed.][90417] Compiler -------- - [Add LLVM CFI support to the Rust compiler][89652] - [Stabilize -Z strip as -C strip][90058]. Note that while release builds already don't add debug symbols for the code you compile, the compiled standard library that ships with Rust includes debug symbols, so you may want to use the `strip` option to remove these symbols to produce smaller release binaries. Note that this release only includes support in rustc, not directly in cargo. - [Add support for LLVM coverage mapping format versions 5 and 6][91207] - [Emit LLVM optimization remarks when enabled with `-Cremark`][90833] - [Update the minimum external LLVM to 12][90175] - [Add `x86_64-unknown-none` at Tier 3*][89062] - [Build musl dist artifacts with debuginfo enabled][90733]. When building release binaries using musl, you may want to use the newly stabilized strip option to remove these debug symbols, reducing the size of your binaries. - [Don't abort compilation after giving a lint error][87337] - [Error messages point at the source of trait bound obligations in more places][89580] \* Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [All remaining functions in the standard library have `#[must_use]` annotations where appropriate][89692], producing a warning when ignoring their return value. This helps catch mistakes such as expecting a function to mutate a value in place rather than return a new value. - [Paths are automatically canonicalized on Windows for operations that support it][89174] - [Re-enable debug checks for `copy` and `copy_nonoverlapping`][90041] - [Implement `RefUnwindSafe` for `Rc<T>`][87467] - [Make RSplit<T, P>: Clone not require T: Clone][90117] - [Implement `Termination` for `Result<Infallible, E>`][88601]. This allows writing `fn main() -> Result<Infallible, ErrorType>`, for a program whose successful exits never involve returning from `main` (for instance, a program that calls `exit`, or that uses `exec` to run another program). Stabilized APIs --------------- - [`Metadata::is_symlink`] - [`Path::is_symlink`] - [`{integer}::saturating_div`] - [`Option::unwrap_unchecked`] - [`Result::unwrap_unchecked`] - [`Result::unwrap_err_unchecked`] - [`NonZero{unsigned}::is_power_of_two`] - [`File::options`] These APIs are now usable in const contexts: - [`Duration::new`] - [`Duration::checked_add`] - [`Duration::saturating_add`] - [`Duration::checked_sub`] - [`Duration::saturating_sub`] - [`Duration::checked_mul`] - [`Duration::saturating_mul`] - [`Duration::checked_div`] - [`MaybeUninit::as_ptr`] - [`MaybeUninit::as_mut_ptr`] - [`MaybeUninit::assume_init`] - [`MaybeUninit::assume_init_ref`] Cargo ----- - [Add --message-format for install command][cargo/10107] - [Warn when alias shadows external subcommand][cargo/10082] Rustdoc ------- - [Show all Deref implementations recursively in rustdoc][90183] - [Use computed visibility in rustdoc][88447] Compatibility Notes ------------------- - [Try all stable method candidates first before trying unstable ones][90329]. This change ensures that adding new nightly-only methods to the Rust standard library will not break code invoking methods of the same name from traits outside the standard library. - Windows: [`std::process::Command` will no longer search the current directory for executables.][87704] - [All proc-macro backward-compatibility lints are now deny-by-default.][88041] - [proc_macro: Append .0 to unsuffixed float if it would otherwise become int token][90297] - [Refactor weak symbols in std::sys::unix][90846]. This optimizes accesses to glibc functions, by avoiding the use of dlopen. This does not increase the [minimum expected version of glibc](https://doc.rust-lang.org/nightly/rustc/platform-support.html). However, software distributions that use symbol versions to detect library dependencies, and which take weak symbols into account in that analysis, may detect rust binaries as requiring newer versions of glibc. - [rustdoc now rejects some unexpected semicolons in doctests][91026] Internal Changes ---------------- These changes provide no direct user facing benefits, but represent significant improvements to the internals and overall performance of rustc and related tools. - [Implement coherence checks for negative trait impls][90104] - [Add rustc lint, warning when iterating over hashmaps][89558] - [Optimize live point computation][90491] - [Enable verification for 1/32nd of queries loaded from disk][90361] - [Implement version of normalize_erasing_regions that allows for normalization failure][91255] [87337]: rust-lang/rust#87337 [87467]: rust-lang/rust#87467 [87704]: rust-lang/rust#87704 [88041]: rust-lang/rust#88041 [88300]: rust-lang/rust#88300 [88447]: rust-lang/rust#88447 [88601]: rust-lang/rust#88601 [88624]: rust-lang/rust#88624 [89062]: rust-lang/rust#89062 [89174]: rust-lang/rust#89174 [89542]: rust-lang/rust#89542 [89551]: rust-lang/rust#89551 [89558]: rust-lang/rust#89558 [89580]: rust-lang/rust#89580 [89652]: rust-lang/rust#89652 [89677]: rust-lang/rust#89677 [89951]: rust-lang/rust#89951 [90041]: rust-lang/rust#90041 [90058]: rust-lang/rust#90058 [90104]: rust-lang/rust#90104 [90117]: rust-lang/rust#90117 [90175]: rust-lang/rust#90175 [90183]: rust-lang/rust#90183 [90297]: rust-lang/rust#90297 [90329]: rust-lang/rust#90329 [90361]: rust-lang/rust#90361 [90417]: rust-lang/rust#90417 [90473]: rust-lang/rust#90473 [90491]: rust-lang/rust#90491 [90733]: rust-lang/rust#90733 [90833]: rust-lang/rust#90833 [90846]: rust-lang/rust#90846 [90896]: rust-lang/rust#90896 [91026]: rust-lang/rust#91026 [91207]: rust-lang/rust#91207 [91255]: rust-lang/rust#91255 [91301]: rust-lang/rust#91301 [cargo/10082]: rust-lang/cargo#10082 [cargo/10107]: rust-lang/cargo#10107 [`Metadata::is_symlink`]: https://doc.rust-lang.org/stable/std/fs/struct.Metadata.html#method.is_symlink [`Path::is_symlink`]: https://doc.rust-lang.org/stable/std/path/struct.Path.html#method.is_symlink [`{integer}::saturating_div`]: https://doc.rust-lang.org/stable/std/primitive.i8.html#method.saturating_div [`Option::unwrap_unchecked`]: https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.unwrap_unchecked [`Result::unwrap_unchecked`]: https://doc.rust-lang.org/stable/std/result/enum.Result.html#method.unwrap_unchecked [`Result::unwrap_err_unchecked`]: https://doc.rust-lang.org/stable/std/result/enum.Result.html#method.unwrap_err_unchecked [`NonZero{unsigned}::is_power_of_two`]: https://doc.rust-lang.org/stable/std/num/struct.NonZeroU8.html#method.is_power_of_two [`File::options`]: https://doc.rust-lang.org/stable/std/fs/struct.File.html#method.options [`unix::process::ExitStatusExt::core_dumped`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.core_dumped [`unix::process::ExitStatusExt::stopped_signal`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.stopped_signal [`unix::process::ExitStatusExt::continued`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.continued [`unix::process::ExitStatusExt::into_raw`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.into_raw [`Duration::new`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.new [`Duration::checked_add`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_add [`Duration::saturating_add`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_add [`Duration::checked_sub`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_sub [`Duration::saturating_sub`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_sub [`Duration::checked_mul`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_mul [`Duration::saturating_mul`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_mul [`Duration::checked_div`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_div [`Duration::as_secs_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.as_secs_f64 [`Duration::as_secs_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.as_secs_f32 [`Duration::from_secs_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.from_secs_f64 [`Duration::from_secs_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.from_secs_f32 [`Duration::mul_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.mul_f64 [`Duration::mul_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.mul_f32 [`Duration::div_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_f64 [`Duration::div_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_f32 [`Duration::div_duration_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_duration_f64 [`Duration::div_duration_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_duration_f32 [`MaybeUninit::as_ptr`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.as_ptr [`MaybeUninit::as_mut_ptr`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.as_mut_ptr [`MaybeUninit::assume_init`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init [`MaybeUninit::assume_init_ref`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init_ref
Pkgsrc changes: * Bump bootstrap kit version to 1.57.0. * Bump require external LLVM to 12.0, according to upstream change log. * Adjust patches as needed, adjust line numbers. * Update checksum adjustments. For some reason the vendor/libc checksum doesn't need fixing, apparently, it remains as commented out. * Add makefile to do all the NetBSD boostrap/cross builds (do-cross.mk). Allow passing in additions to CONFIGURE_ARGS via ADD_CONFIGURE_ARGS. Upstream changes: Version 1.58.1 (2022-01-19) =========================== * Fix race condition in `std::fs::remove_dir_all` ([CVE-2022-21658]) * [Handle captured arguments in the `useless_format` Clippy lint][clippy/8295] * [Move `non_send_fields_in_send_ty` Clippy lint to nursery][clippy/8075] * [Fix wrong error message displayed when some imports are missing][91254] * [Fix rustfmt not formatting generated files from stdin][92912] [CVE-2022-21658]: https://www.cve.org/CVERecord?id=CVE-2022-21658] [91254]: rust-lang/rust#91254 [92912]: rust-lang/rust#92912 [clippy/8075]: rust-lang/rust-clippy#8075 [clippy/8295]: rust-lang/rust-clippy#8295 Version 1.58.0 (2022-01-13) ========================== Language -------- - [Format strings can now capture arguments simply by writing `{ident}` in the string.][90473] This works in all macros accepting format strings. Support for this in `panic!` (`panic!("{ident}")`) requires the 2021 edition; panic invocations in previous editions that appear to be trying to use this will result in a warning lint about not having the intended effect. - [`*const T` pointers can now be dereferenced in const contexts.][89551] - [The rules for when a generic struct implements `Unsize` have been relaxed.][90417] Compiler -------- - [Add LLVM CFI support to the Rust compiler][89652] - [Stabilize -Z strip as -C strip][90058]. Note that while release builds already don't add debug symbols for the code you compile, the compiled standard library that ships with Rust includes debug symbols, so you may want to use the `strip` option to remove these symbols to produce smaller release binaries. Note that this release only includes support in rustc, not directly in cargo. - [Add support for LLVM coverage mapping format versions 5 and 6][91207] - [Emit LLVM optimization remarks when enabled with `-Cremark`][90833] - [Update the minimum external LLVM to 12][90175] - [Add `x86_64-unknown-none` at Tier 3*][89062] - [Build musl dist artifacts with debuginfo enabled][90733]. When building release binaries using musl, you may want to use the newly stabilized strip option to remove these debug symbols, reducing the size of your binaries. - [Don't abort compilation after giving a lint error][87337] - [Error messages point at the source of trait bound obligations in more places][89580] \* Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [All remaining functions in the standard library have `#[must_use]` annotations where appropriate][89692], producing a warning when ignoring their return value. This helps catch mistakes such as expecting a function to mutate a value in place rather than return a new value. - [Paths are automatically canonicalized on Windows for operations that support it][89174] - [Re-enable debug checks for `copy` and `copy_nonoverlapping`][90041] - [Implement `RefUnwindSafe` for `Rc<T>`][87467] - [Make RSplit<T, P>: Clone not require T: Clone][90117] - [Implement `Termination` for `Result<Infallible, E>`][88601]. This allows writing `fn main() -> Result<Infallible, ErrorType>`, for a program whose successful exits never involve returning from `main` (for instance, a program that calls `exit`, or that uses `exec` to run another program). Stabilized APIs --------------- - [`Metadata::is_symlink`] - [`Path::is_symlink`] - [`{integer}::saturating_div`] - [`Option::unwrap_unchecked`] - [`Result::unwrap_unchecked`] - [`Result::unwrap_err_unchecked`] - [`NonZero{unsigned}::is_power_of_two`] - [`File::options`] These APIs are now usable in const contexts: - [`Duration::new`] - [`Duration::checked_add`] - [`Duration::saturating_add`] - [`Duration::checked_sub`] - [`Duration::saturating_sub`] - [`Duration::checked_mul`] - [`Duration::saturating_mul`] - [`Duration::checked_div`] - [`MaybeUninit::as_ptr`] - [`MaybeUninit::as_mut_ptr`] - [`MaybeUninit::assume_init`] - [`MaybeUninit::assume_init_ref`] Cargo ----- - [Add --message-format for install command][cargo/10107] - [Warn when alias shadows external subcommand][cargo/10082] Rustdoc ------- - [Show all Deref implementations recursively in rustdoc][90183] - [Use computed visibility in rustdoc][88447] Compatibility Notes ------------------- - [Try all stable method candidates first before trying unstable ones][90329]. This change ensures that adding new nightly-only methods to the Rust standard library will not break code invoking methods of the same name from traits outside the standard library. - Windows: [`std::process::Command` will no longer search the current directory for executables.][87704] - [All proc-macro backward-compatibility lints are now deny-by-default.][88041] - [proc_macro: Append .0 to unsuffixed float if it would otherwise become int token][90297] - [Refactor weak symbols in std::sys::unix][90846]. This optimizes accesses to glibc functions, by avoiding the use of dlopen. This does not increase the [minimum expected version of glibc](https://doc.rust-lang.org/nightly/rustc/platform-support.html). However, software distributions that use symbol versions to detect library dependencies, and which take weak symbols into account in that analysis, may detect rust binaries as requiring newer versions of glibc. - [rustdoc now rejects some unexpected semicolons in doctests][91026] Internal Changes ---------------- These changes provide no direct user facing benefits, but represent significant improvements to the internals and overall performance of rustc and related tools. - [Implement coherence checks for negative trait impls][90104] - [Add rustc lint, warning when iterating over hashmaps][89558] - [Optimize live point computation][90491] - [Enable verification for 1/32nd of queries loaded from disk][90361] - [Implement version of normalize_erasing_regions that allows for normalization failure][91255] [87337]: rust-lang/rust#87337 [87467]: rust-lang/rust#87467 [87704]: rust-lang/rust#87704 [88041]: rust-lang/rust#88041 [88300]: rust-lang/rust#88300 [88447]: rust-lang/rust#88447 [88601]: rust-lang/rust#88601 [88624]: rust-lang/rust#88624 [89062]: rust-lang/rust#89062 [89174]: rust-lang/rust#89174 [89542]: rust-lang/rust#89542 [89551]: rust-lang/rust#89551 [89558]: rust-lang/rust#89558 [89580]: rust-lang/rust#89580 [89652]: rust-lang/rust#89652 [89677]: rust-lang/rust#89677 [89951]: rust-lang/rust#89951 [90041]: rust-lang/rust#90041 [90058]: rust-lang/rust#90058 [90104]: rust-lang/rust#90104 [90117]: rust-lang/rust#90117 [90175]: rust-lang/rust#90175 [90183]: rust-lang/rust#90183 [90297]: rust-lang/rust#90297 [90329]: rust-lang/rust#90329 [90361]: rust-lang/rust#90361 [90417]: rust-lang/rust#90417 [90473]: rust-lang/rust#90473 [90491]: rust-lang/rust#90491 [90733]: rust-lang/rust#90733 [90833]: rust-lang/rust#90833 [90846]: rust-lang/rust#90846 [90896]: rust-lang/rust#90896 [91026]: rust-lang/rust#91026 [91207]: rust-lang/rust#91207 [91255]: rust-lang/rust#91255 [91301]: rust-lang/rust#91301 [cargo/10082]: rust-lang/cargo#10082 [cargo/10107]: rust-lang/cargo#10107 [`Metadata::is_symlink`]: https://doc.rust-lang.org/stable/std/fs/struct.Metadata.html#method.is_symlink [`Path::is_symlink`]: https://doc.rust-lang.org/stable/std/path/struct.Path.html#method.is_symlink [`{integer}::saturating_div`]: https://doc.rust-lang.org/stable/std/primitive.i8.html#method.saturating_div [`Option::unwrap_unchecked`]: https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.unwrap_unchecked [`Result::unwrap_unchecked`]: https://doc.rust-lang.org/stable/std/result/enum.Result.html#method.unwrap_unchecked [`Result::unwrap_err_unchecked`]: https://doc.rust-lang.org/stable/std/result/enum.Result.html#method.unwrap_err_unchecked [`NonZero{unsigned}::is_power_of_two`]: https://doc.rust-lang.org/stable/std/num/struct.NonZeroU8.html#method.is_power_of_two [`File::options`]: https://doc.rust-lang.org/stable/std/fs/struct.File.html#method.options [`unix::process::ExitStatusExt::core_dumped`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.core_dumped [`unix::process::ExitStatusExt::stopped_signal`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.stopped_signal [`unix::process::ExitStatusExt::continued`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.continued [`unix::process::ExitStatusExt::into_raw`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.into_raw [`Duration::new`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.new [`Duration::checked_add`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_add [`Duration::saturating_add`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_add [`Duration::checked_sub`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_sub [`Duration::saturating_sub`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_sub [`Duration::checked_mul`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_mul [`Duration::saturating_mul`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_mul [`Duration::checked_div`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_div [`Duration::as_secs_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.as_secs_f64 [`Duration::as_secs_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.as_secs_f32 [`Duration::from_secs_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.from_secs_f64 [`Duration::from_secs_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.from_secs_f32 [`Duration::mul_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.mul_f64 [`Duration::mul_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.mul_f32 [`Duration::div_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_f64 [`Duration::div_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_f32 [`Duration::div_duration_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_duration_f64 [`Duration::div_duration_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_duration_f32 [`MaybeUninit::as_ptr`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.as_ptr [`MaybeUninit::as_mut_ptr`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.as_mut_ptr [`MaybeUninit::assume_init`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init [`MaybeUninit::assume_init_ref`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init_ref
This is a limited enabling of incremental verification for query results loaded from disk, which previously did not run without -Zincremental-verify-ich. If enabled for all queries, we see a probably unacceptable hit of ~50% in the worst case, so this pairs back the verification to a more limited set based on the hash key.
Per collected perf results, this is a regression of at most 7% on coercions opt incr-unchanged, and typically less than 0.5% on other benchmarks (largely limited to incr-unchanged). I believe this is acceptable performance to land, and we can either ratchet it up or down fairly easily.
We have no real sense of whether this will lead to a large amount of assertions in the wild, but since those assertions may lead to miscompilations today, it seems potentially warranted. We have a good bit of lead time until the next stable release, though the holiday season will also start soon; we may wish to discuss the timing of enabling this and weigh the desire to prevent (possible) miscompilations against assertions.
cc @rust-lang/wg-incr-comp