Change enum->int casts to not go through MIR casts. #96862

oli-obk · 2022-05-09T11:44:34Z

follow-up to #96814

this simplifies all backends and even gives LLVM more information about the return value of Rvalue::Discriminant, enabling optimizations in more cases.

rust-highfive · 2022-05-09T11:44:37Z

r? @compiler-errors

(rust-highfive has picked a reviewer for you, use r? to override)

oli-obk · 2022-05-09T11:49:04Z

@bors try @rust-timer queue

rust-timer · 2022-05-09T11:49:05Z

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

bors · 2022-05-09T12:38:56Z

⌛ Trying commit aba79aecc904cc5cd0174804c375a2bdac4baa82 with merge 9070d93994dedb99925dcdbee841e40c34eee7d4...

oli-obk · 2022-05-09T12:38:58Z

🤣 enum -> int cast acting as mem::forget strikes again. We used to drop these enums right after casting. Then we got MIR and we ended up mem::forgetting them instead. We do have a lint against them now: #73333

compiler/rustc_codegen_ssa/src/mir/rvalue.rs

compiler/rustc_mir_build/src/build/expr/as_rvalue.rs

RalfJung · 2022-05-09T12:49:36Z

follow-up to #96814

To be clear, your PR needs to land first before #96814 can make progress.

compiler/rustc_lint_defs/src/builtin.rs

bjorn3 · 2022-05-09T12:56:36Z

This branch can be removed with this PR, right?

https://github.com/bjorn3/rustc_codegen_cranelift/blob/25f7711fea4f83a82d54c17dff5cc5b9a2b2937b/src/base.rs#L630-L652

src/test/run-pass-valgrind/cast-enum-with-dtor.rs

RalfJung · 2022-05-11T08:42:26Z

Looks like the perf run didn't go through. Not sure if the old try build is still sufficiently up-to-date, so let's
@bors try @rust-timer queue

rust-timer · 2022-05-11T08:42:27Z

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

bors · 2022-05-11T08:42:39Z

⌛ Trying commit 6acd3d5d4411ab9fd4a566bbd0185ab61a4d94b3 with merge 4abfc5bbf05d4e7b813ae10bca09b45cc3e1dcf2...

RalfJung · 2022-05-11T08:46:33Z

Regarding the PR itself, the change LGTM (not that I feel qualified to review this), but we have two decisions to make:

Are we okay with regressing performance of bounds checks for array accesses derived from enum casts? Not sure how common that pattern is, but someone cared enough to add a test. OTOH this is on the critical path for an ICE fix (ICE with aligned enum #92464, enums with repr(align) generate Scalar layout with padding (ICE: miri: field access on non aggregate <uninitialized> ) #96185) and all backend people seem to agree that casting is better done in MIR (or else all backends have to duplicate the same logic, as they did before this PR).
Are we okay with changing dtor behavior when casting C-like enums with Drop to int again? We warn against these casts for quite a while already (Tracking issue for future-incompatibility lint cenum_impl_drop_cast #73333) and have changed behavior in the past so I hope the answer is yes.

Cc @rust-lang/compiler for the first point; @rust-lang/lang for the second.

bors · 2022-05-11T10:15:18Z

☀️ Try build successful - checks-actions
Build commit: 4abfc5bbf05d4e7b813ae10bca09b45cc3e1dcf2 (4abfc5bbf05d4e7b813ae10bca09b45cc3e1dcf2)

rust-timer · 2022-05-11T10:15:20Z

Queued 4abfc5bbf05d4e7b813ae10bca09b45cc3e1dcf2 with parent b862b43, future comparison URL.

rust-timer · 2022-05-11T12:32:38Z

Finished benchmarking commit (4abfc5bbf05d4e7b813ae10bca09b45cc3e1dcf2): comparison url.

Summary:

Primary benchmarks: no relevant changes found
Secondary benchmarks: 🎉 relevant improvement found

	Regressions 😿 (primary)	Regressions 😿 (secondary)	Improvements 🎉 (primary)	Improvements 🎉 (secondary)	All 😿 🎉 (primary)
count¹	0	0	0	1	0
mean²	N/A	N/A	N/A	-0.2%	N/A
max	N/A	N/A	N/A	-0.2%	N/A

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 may lead to changes in compiler perf.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf -perf-regression

number of relevant changes ↩
the arithmetic mean of the percent change ↩

bors · 2022-05-14T13:05:38Z

☔ The latest upstream changes (presumably #95826) made this pull request unmergeable. Please resolve the merge conflicts.

oli-obk · 2022-06-29T14:21:11Z

This is ready for a final review (though is just some minor rebase fixes compared to the earlier version that loses the assumes, too)

Instead we generate a discriminant rvalue and cast the result of that.

compiler/rustc_codegen_ssa/src/mir/rvalue.rs

RalfJung

LGTM (r=me), modulo the question and also maybe changing some/all of these new instrument to trace

…atch 3x

…butes

oli-obk · 2022-07-05T09:27:33Z

@bors r=RalfJung

bors · 2022-07-05T09:27:34Z

📌 Commit 82c73af has been approved by RalfJung

bors · 2022-07-05T09:36:33Z

⌛ Testing commit 82c73af with merge 53792b9...

bors · 2022-07-05T12:17:20Z

☀️ Test successful - checks-actions
Approved by: RalfJung
Pushing 53792b9 to master...

rust-timer · 2022-07-05T15:11:35Z

Finished benchmarking commit (53792b9): comparison url.

Instruction count

Primary benchmarks: 🎉 relevant improvement found
Secondary benchmarks: 🎉 relevant improvement found

	mean¹	max	count²
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	N/A	N/A	0
Improvements 🎉 (primary)	-0.5%	-0.5%	1
Improvements 🎉 (secondary)	-0.7%	-0.7%	1
All 😿🎉 (primary)	-0.5%	-0.5%	1

Max RSS (memory usage)

Results

Primary benchmarks: 🎉 relevant improvement found
Secondary benchmarks: mixed results

	mean¹	max	count²
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	5.1%	5.1%	1
Improvements 🎉 (primary)	-0.0%	-0.0%	1
Improvements 🎉 (secondary)	-2.5%	-2.8%	2
All 😿🎉 (primary)	-0.0%	-0.0%	1

Cycles

Results

Primary benchmarks: 😿 relevant regression found
Secondary benchmarks: no relevant changes found

	mean¹	max	count²
Regressions 😿 (primary)	2.5%	2.5%	1
Regressions 😿 (secondary)	N/A	N/A	0
Improvements 🎉 (primary)	N/A	N/A	0
Improvements 🎉 (secondary)	N/A	N/A	0
All 😿🎉 (primary)	2.5%	2.5%	1

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression

the arithmetic mean of the percent change ↩ ↩² ↩³
number of relevant changes ↩ ↩² ↩³

Change enum->int casts to not go through MIR casts. follow-up to rust-lang#96814 this simplifies all backends and even gives LLVM more information about the return value of `Rvalue::Discriminant`, enabling optimizations in more cases.

Lower the assume intrinsic to a MIR statement This makes rust-lang#96862 (comment) easier and will generally allow us to cheaply insert assume intrinsic calls in mir building. r? rust-lang/wg-mir-opt

Pkgsrc changes: * Add patch to fix vendor/kqueue issue (on 32-bit hosts) * Adjust other patches & line numbers * Version bumps & checksum changes. Upstream changes: Version 1.64.0 (2022-09-22) =========================== Language -------- - [Unions with mutable references or tuples of allowed types are now allowed](rust-lang/rust#97995) - It is now considered valid to deallocate memory pointed to by a shared reference `&T` [if every byte in `T` is inside an `UnsafeCell`](rust-lang/rust#98017) - Unused tuple struct fields are now warned against in an allow-by-default lint, [`unused_tuple_struct_fields`] (rust-lang/rust#95977), similar to the existing warning for unused struct fields. This lint will become warn-by-default in the future. Compiler -------- - [Add Nintendo Switch as tier 3 target] (rust-lang/rust#88991) - Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. - [Only compile `#[used]` as llvm.compiler.used for ELF targets] (rust-lang/rust#93718) - [Add the `--diagnostic-width` compiler flag to define the terminal width.] (rust-lang/rust#95635) - [Add support for link-flavor `rust-lld` for iOS, tvOS and watchOS] (rust-lang/rust#98771) Libraries --------- - [Remove restrictions on compare-exchange memory ordering.] (rust-lang/rust#98383) - You can now `write!` or `writeln!` into an `OsString`: [Implement `fmt::Write` for `OsString`](rust-lang/rust#97915) - [Make RwLockReadGuard covariant] (rust-lang/rust#96820) - [Implement `FusedIterator` for `std::net::[Into]Incoming`] (rust-lang/rust#97300) - [`impl<T: AsRawFd> AsRawFd for {Arc,Box}<T>`] (rust-lang/rust#97437) - [`ptr::copy` and `ptr::swap` are doing untyped copies] (rust-lang/rust#97712) - [Add cgroupv1 support to `available_parallelism`] (rust-lang/rust#97925) - [Mitigate many incorrect uses of `mem::uninitialized`] (rust-lang/rust#99182) Stabilized APIs --------------- - [`future::IntoFuture`] (https://doc.rust-lang.org/stable/std/future/trait.IntoFuture.html) - [`future::poll_fn`] (https://doc.rust-lang.org/stable/std/future/fn.poll_fn.html) - [`task::ready!`] (https://doc.rust-lang.org/stable/std/task/macro.ready.html) - [`num::NonZero*::checked_mul`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_mul) - [`num::NonZero*::checked_pow`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_pow) - [`num::NonZero*::saturating_mul`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.saturating_mul) - [`num::NonZero*::saturating_pow`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.saturating_pow) - [`num::NonZeroI*::abs`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.abs) - [`num::NonZeroI*::checked_abs`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.checked_abs) - [`num::NonZeroI*::overflowing_abs`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.overflowing_abs) - [`num::NonZeroI*::saturating_abs`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.saturating_abs) - [`num::NonZeroI*::unsigned_abs`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.unsigned_abs) - [`num::NonZeroI*::wrapping_abs`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.wrapping_abs) - [`num::NonZeroU*::checked_add`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_add) - [`num::NonZeroU*::checked_next_power_of_two`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_next_power_of_two) - [`num::NonZeroU*::saturating_add`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.saturating_add) - [`os::unix::process::CommandExt::process_group`] (https://doc.rust-lang.org/stable/std/os/unix/process/trait.CommandExt.html#tymethod.process_group) - [`os::windows::fs::FileTypeExt::is_symlink_dir`] (https://doc.rust-lang.org/stable/std/os/windows/fs/trait.FileTypeExt.html#tymethod.is_symlink_dir) - [`os::windows::fs::FileTypeExt::is_symlink_file`] (https://doc.rust-lang.org/stable/std/os/windows/fs/trait.FileTypeExt.html#tymethod.is_symlink_file) These types were previously stable in `std::ffi`, but are now also available in `core` and `alloc`: - [`core::ffi::CStr`] (https://doc.rust-lang.org/stable/core/ffi/struct.CStr.html) - [`core::ffi::FromBytesWithNulError`] (https://doc.rust-lang.org/stable/core/ffi/struct.FromBytesWithNulError.html) - [`alloc::ffi::CString`] (https://doc.rust-lang.org/stable/alloc/ffi/struct.CString.html) - [`alloc::ffi::FromVecWithNulError`] (https://doc.rust-lang.org/stable/alloc/ffi/struct.FromVecWithNulError.html) - [`alloc::ffi::IntoStringError`] (https://doc.rust-lang.org/stable/alloc/ffi/struct.IntoStringError.html) - [`alloc::ffi::NulError`] (https://doc.rust-lang.org/stable/alloc/ffi/struct.NulError.html) These types were previously stable in `std::os::raw`, but are now also available in `core::ffi` and `std::ffi`: - [`ffi::c_char`] (https://doc.rust-lang.org/stable/std/ffi/type.c_char.html) - [`ffi::c_double`] (https://doc.rust-lang.org/stable/std/ffi/type.c_double.html) - [`ffi::c_float`] (https://doc.rust-lang.org/stable/std/ffi/type.c_float.html) - [`ffi::c_int`] (https://doc.rust-lang.org/stable/std/ffi/type.c_int.html) - [`ffi::c_long`] (https://doc.rust-lang.org/stable/std/ffi/type.c_long.html) - [`ffi::c_longlong`] (https://doc.rust-lang.org/stable/std/ffi/type.c_longlong.html) - [`ffi::c_schar`] (https://doc.rust-lang.org/stable/std/ffi/type.c_schar.html) - [`ffi::c_short`] (https://doc.rust-lang.org/stable/std/ffi/type.c_short.html) - [`ffi::c_uchar`] (https://doc.rust-lang.org/stable/std/ffi/type.c_uchar.html) - [`ffi::c_uint`] (https://doc.rust-lang.org/stable/std/ffi/type.c_uint.html) - [`ffi::c_ulong`] (https://doc.rust-lang.org/stable/std/ffi/type.c_ulong.html) - [`ffi::c_ulonglong`] (https://doc.rust-lang.org/stable/std/ffi/type.c_ulonglong.html) - [`ffi::c_ushort`] (https://doc.rust-lang.org/stable/std/ffi/type.c_ushort.html) These APIs are now usable in const contexts: - [`slice::from_raw_parts`] (https://doc.rust-lang.org/stable/core/slice/fn.from_raw_parts.html) Cargo ----- - [Packages can now inherit settings from the workspace so that the settings can be centralized in one place.] (rust-lang/cargo#10859) See [`workspace.package`](https://doc.rust-lang.org/nightly/cargo/reference/workspaces.html#the-workspacepackage-table) and [`workspace.dependencies`](https://doc.rust-lang.org/nightly/cargo/reference/workspaces.html#the-workspacedependencies-table) for more details on how to define these common settings. - [Cargo commands can now accept multiple `--target` flags to build for multiple targets at once] (rust-lang/cargo#10766), and the [`build.target`](https://doc.rust-lang.org/nightly/cargo/reference/config.html#buildtarget) config option may now take an array of multiple targets. - [The `--jobs` argument can now take a negative number to count backwards from the max CPUs.] (rust-lang/cargo#10844) - [`cargo add` will now update `Cargo.lock`.] (rust-lang/cargo#10902) - [Added](rust-lang/cargo#10838) the [`--crate-type`](https://doc.rust-lang.org/nightly/cargo/commands/cargo-rustc.html#option-cargo-rustc---crate-type) flag to `cargo rustc` to override the crate type. - [Significantly improved the performance fetching git dependencies from GitHub when using a hash in the `rev` field.] (rust-lang/cargo#10079) Misc ---- - [The `rust-analyzer` rustup component is now available on the stable channel.] (rust-lang/rust#98640) Compatibility Notes ------------------- - The minimum required versions for all `-linux-gnu` targets are now at least kernel 3.2 and glibc 2.17, for targets that previously supported older versions: [Increase the minimum linux-gnu versions](rust-lang/rust#95026) - [Network primitives are now implemented with the ideal Rust layout, not the C system layout] (rust-lang/rust#78802). This can cause problems when transmuting the types. - [Add assertion that `transmute_copy`'s `U` is not larger than `T`] (rust-lang/rust#98839) - [A soundness bug in `BTreeMap` was fixed] (rust-lang/rust#99413) that allowed data it was borrowing to be dropped before the container. - [The Drop behavior of C-like enums cast to ints has changed] (rust-lang/rust#96862). These are already discouraged by a compiler warning. - [Relate late-bound closure lifetimes to parent fn in NLL] (rust-lang/rust#98835) - [Errors at const-eval time are now in future incompatibility reports] (rust-lang/rust#97743) - On the `thumbv6m-none-eabi` target, some incorrect `asm!` statements were erroneously accepted if they used the high registers (r8 to r14) as an input/output operand. [This is no longer accepted] (rust-lang/rust#99155). - [`impl Trait` was accidentally accepted as the associated type value of return-position `impl Trait`] (rust-lang/rust#97346), without fulfilling all the trait bounds of that associated type, as long as the hidden type satisfies said bounds. This has been fixed. Internal Changes ---------------- These changes do not affect any public interfaces of Rust, but they represent significant improvements to the performance or internals of rustc and related tools. - Windows builds now use profile-guided optimization, providing 10-20% improvements to compiler performance: [Utilize PGO for windows x64 rustc dist builds] (rust-lang/rust#96978) - [Stop keeping metadata in memory before writing it to disk] (rust-lang/rust#96544) - [compiletest: strip debuginfo by default for mode=ui] (rust-lang/rust#98140) - Many improvements to generated code for derives, including performance improvements: - [Don't use match-destructuring for derived ops on structs.] (rust-lang/rust#98446) - [Many small deriving cleanups] (rust-lang/rust#98741) - [More derive output improvements] (rust-lang/rust#98758) - [Clarify deriving code](rust-lang/rust#98915) - [Final derive output improvements] (rust-lang/rust#99046) - [Stop injecting `#[allow(unused_qualifications)]` in generated `derive` implementations](rust-lang/rust#99485) - [Improve `derive(Debug)`](rust-lang/rust#98190) - [Bump to clap 3](rust-lang/rust#98213) - [fully move dropck to mir](rust-lang/rust#98641) - [Optimize `Vec::insert` for the case where `index == len`.] (rust-lang/rust#98755) - [Convert rust-analyzer to an in-tree tool] (rust-lang/rust#99603)

Pkgsrc changes: * This package now contains rust-analyzer, so implicitly conflicts with that pkgsrc package. The same goes for the rust-src package. * Add NetBSD/arm6 port * Add unfinished NetBSD/mipsel port * Revert the use of the internal LLVM, should now build with the new pkgsrc LLVM (15). * Add depndence on compat80 for sparc64 to fix the build * Adapt patches * Add CHECK_INTERPRETER_SKIP for a few (mostly unused) files. (A proper fix may come later.) Upstream changes: Version 1.64.0 (2022-09-22) =========================== Language -------- - [Unions with mutable references or tuples of allowed types are now allowed](rust-lang/rust#97995) - It is now considered valid to deallocate memory pointed to by a shared reference `&T` [if every byte in `T` is inside an `UnsafeCell`](rust-lang/rust#98017) - Unused tuple struct fields are now warned against in an allow-by-default lint, [`unused_tuple_struct_fields`] (rust-lang/rust#95977), similar to the existing warning for unused struct fields. This lint will become warn-by-default in the future. Compiler -------- - [Add Nintendo Switch as tier 3 target] (rust-lang/rust#88991) - Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. - [Only compile `#[used]` as llvm.compiler.used for ELF targets] (rust-lang/rust#93718) - [Add the `--diagnostic-width` compiler flag to define the terminal width.] (rust-lang/rust#95635) - [Add support for link-flavor `rust-lld` for iOS, tvOS and watchOS] (rust-lang/rust#98771) Libraries --------- - [Remove restrictions on compare-exchange memory ordering.] (rust-lang/rust#98383) - You can now `write!` or `writeln!` into an `OsString`: [Implement `fmt::Write` for `OsString`](rust-lang/rust#97915) - [Make RwLockReadGuard covariant] (rust-lang/rust#96820) - [Implement `FusedIterator` for `std::net::[Into]Incoming`] (rust-lang/rust#97300) - [`impl<T: AsRawFd> AsRawFd for {Arc,Box}<T>`] (rust-lang/rust#97437) - [`ptr::copy` and `ptr::swap` are doing untyped copies] (rust-lang/rust#97712) - [Add cgroupv1 support to `available_parallelism`] (rust-lang/rust#97925) - [Mitigate many incorrect uses of `mem::uninitialized`] (rust-lang/rust#99182) Stabilized APIs --------------- - [`future::IntoFuture`] (https://doc.rust-lang.org/stable/std/future/trait.IntoFuture.html) - [`future::poll_fn`] (https://doc.rust-lang.org/stable/std/future/fn.poll_fn.html) - [`task::ready!`] (https://doc.rust-lang.org/stable/std/task/macro.ready.html) - [`num::NonZero*::checked_mul`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_mul) - [`num::NonZero*::checked_pow`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_pow) - [`num::NonZero*::saturating_mul`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.saturating_mul) - [`num::NonZero*::saturating_pow`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.saturating_pow) - [`num::NonZeroI*::abs`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.abs) - [`num::NonZeroI*::checked_abs`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.checked_abs) - [`num::NonZeroI*::overflowing_abs`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.overflowing_abs) - [`num::NonZeroI*::saturating_abs`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.saturating_abs) - [`num::NonZeroI*::unsigned_abs`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.unsigned_abs) - [`num::NonZeroI*::wrapping_abs`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.wrapping_abs) - [`num::NonZeroU*::checked_add`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_add) - [`num::NonZeroU*::checked_next_power_of_two`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_next_power_of_two) - [`num::NonZeroU*::saturating_add`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.saturating_add) - [`os::unix::process::CommandExt::process_group`] (https://doc.rust-lang.org/stable/std/os/unix/process/trait.CommandExt.html#tymethod.process_group) - [`os::windows::fs::FileTypeExt::is_symlink_dir`] (https://doc.rust-lang.org/stable/std/os/windows/fs/trait.FileTypeExt.html#tymethod.is_symlink_dir) - [`os::windows::fs::FileTypeExt::is_symlink_file`] (https://doc.rust-lang.org/stable/std/os/windows/fs/trait.FileTypeExt.html#tymethod.is_symlink_file) These types were previously stable in `std::ffi`, but are now also available in `core` and `alloc`: - [`core::ffi::CStr`] (https://doc.rust-lang.org/stable/core/ffi/struct.CStr.html) - [`core::ffi::FromBytesWithNulError`] (https://doc.rust-lang.org/stable/core/ffi/struct.FromBytesWithNulError.html) - [`alloc::ffi::CString`] (https://doc.rust-lang.org/stable/alloc/ffi/struct.CString.html) - [`alloc::ffi::FromVecWithNulError`] (https://doc.rust-lang.org/stable/alloc/ffi/struct.FromVecWithNulError.html) - [`alloc::ffi::IntoStringError`] (https://doc.rust-lang.org/stable/alloc/ffi/struct.IntoStringError.html) - [`alloc::ffi::NulError`] (https://doc.rust-lang.org/stable/alloc/ffi/struct.NulError.html) These types were previously stable in `std::os::raw`, but are now also available in `core::ffi` and `std::ffi`: - [`ffi::c_char`] (https://doc.rust-lang.org/stable/std/ffi/type.c_char.html) - [`ffi::c_double`] (https://doc.rust-lang.org/stable/std/ffi/type.c_double.html) - [`ffi::c_float`] (https://doc.rust-lang.org/stable/std/ffi/type.c_float.html) - [`ffi::c_int`] (https://doc.rust-lang.org/stable/std/ffi/type.c_int.html) - [`ffi::c_long`] (https://doc.rust-lang.org/stable/std/ffi/type.c_long.html) - [`ffi::c_longlong`] (https://doc.rust-lang.org/stable/std/ffi/type.c_longlong.html) - [`ffi::c_schar`] (https://doc.rust-lang.org/stable/std/ffi/type.c_schar.html) - [`ffi::c_short`] (https://doc.rust-lang.org/stable/std/ffi/type.c_short.html) - [`ffi::c_uchar`] (https://doc.rust-lang.org/stable/std/ffi/type.c_uchar.html) - [`ffi::c_uint`] (https://doc.rust-lang.org/stable/std/ffi/type.c_uint.html) - [`ffi::c_ulong`] (https://doc.rust-lang.org/stable/std/ffi/type.c_ulong.html) - [`ffi::c_ulonglong`] (https://doc.rust-lang.org/stable/std/ffi/type.c_ulonglong.html) - [`ffi::c_ushort`] (https://doc.rust-lang.org/stable/std/ffi/type.c_ushort.html) These APIs are now usable in const contexts: - [`slice::from_raw_parts`] (https://doc.rust-lang.org/stable/core/slice/fn.from_raw_parts.html) Cargo ----- - [Packages can now inherit settings from the workspace so that the settings can be centralized in one place.] (rust-lang/cargo#10859) See [`workspace.package`](https://doc.rust-lang.org/nightly/cargo/reference/workspaces.html#the-workspacepackage-table) and [`workspace.dependencies`](https://doc.rust-lang.org/nightly/cargo/reference/workspaces.html#the-workspacedependencies-table) for more details on how to define these common settings. - [Cargo commands can now accept multiple `--target` flags to build for multiple targets at once] (rust-lang/cargo#10766), and the [`build.target`](https://doc.rust-lang.org/nightly/cargo/reference/config.html#buildtarget) config option may now take an array of multiple targets. - [The `--jobs` argument can now take a negative number to count backwards from the max CPUs.] (rust-lang/cargo#10844) - [`cargo add` will now update `Cargo.lock`.] (rust-lang/cargo#10902) - [Added](rust-lang/cargo#10838) the [`--crate-type`](https://doc.rust-lang.org/nightly/cargo/commands/cargo-rustc.html#option-cargo-rustc---crate-type) flag to `cargo rustc` to override the crate type. - [Significantly improved the performance fetching git dependencies from GitHub when using a hash in the `rev` field.] (rust-lang/cargo#10079) Misc ---- - [The `rust-analyzer` rustup component is now available on the stable channel.] (rust-lang/rust#98640) Compatibility Notes ------------------- - The minimum required versions for all `-linux-gnu` targets are now at least kernel 3.2 and glibc 2.17, for targets that previously supported older versions: [Increase the minimum linux-gnu versions](rust-lang/rust#95026) - [Network primitives are now implemented with the ideal Rust layout, not the C system layout] (rust-lang/rust#78802). This can cause problems when transmuting the types. - [Add assertion that `transmute_copy`'s `U` is not larger than `T`] (rust-lang/rust#98839) - [A soundness bug in `BTreeMap` was fixed] (rust-lang/rust#99413) that allowed data it was borrowing to be dropped before the container. - [The Drop behavior of C-like enums cast to ints has changed] (rust-lang/rust#96862). These are already discouraged by a compiler warning. - [Relate late-bound closure lifetimes to parent fn in NLL] (rust-lang/rust#98835) - [Errors at const-eval time are now in future incompatibility reports] (rust-lang/rust#97743) - On the `thumbv6m-none-eabi` target, some incorrect `asm!` statements were erroneously accepted if they used the high registers (r8 to r14) as an input/output operand. [This is no longer accepted] (rust-lang/rust#99155). - [`impl Trait` was accidentally accepted as the associated type value of return-position `impl Trait`] (rust-lang/rust#97346), without fulfilling all the trait bounds of that associated type, as long as the hidden type satisfies said bounds. This has been fixed. Internal Changes ---------------- These changes do not affect any public interfaces of Rust, but they represent significant improvements to the performance or internals of rustc and related tools. - Windows builds now use profile-guided optimization, providing 10-20% improvements to compiler performance: [Utilize PGO for windows x64 rustc dist builds] (rust-lang/rust#96978) - [Stop keeping metadata in memory before writing it to disk] (rust-lang/rust#96544) - [compiletest: strip debuginfo by default for mode=ui] (rust-lang/rust#98140) - Many improvements to generated code for derives, including performance improvements: - [Don't use match-destructuring for derived ops on structs.] (rust-lang/rust#98446) - [Many small deriving cleanups] (rust-lang/rust#98741) - [More derive output improvements] (rust-lang/rust#98758) - [Clarify deriving code](rust-lang/rust#98915) - [Final derive output improvements] (rust-lang/rust#99046) - [Stop injecting `#[allow(unused_qualifications)]` in generated `derive` implementations](rust-lang/rust#99485) - [Improve `derive(Debug)`](rust-lang/rust#98190) - [Bump to clap 3](rust-lang/rust#98213) - [fully move dropck to mir](rust-lang/rust#98641) - [Optimize `Vec::insert` for the case where `index == len`.] (rust-lang/rust#98755) - [Convert rust-analyzer to an in-tree tool] (rust-lang/rust#99603)

Lower the assume intrinsic to a MIR statement This makes rust-lang/rust#96862 (comment) easier and will generally allow us to cheaply insert assume intrinsic calls in mir building. r? rust-lang/wg-mir-opt

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Fix repr(align) enum handling #96814

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oli-obk force-pushed the enum_cast_mir branch from 0eacd43 to 6acd3d5 Compare May 9, 2022 13:07

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Change enum->int casts to not go through MIR casts.

7839cb9

Instead we generate a discriminant rvalue and cast the result of that.

oli-obk force-pushed the enum_cast_mir branch from 291329a to 7839cb9 Compare June 30, 2022 07:47

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oli-obk added 2 commits July 5, 2022 09:26

Add a helper method with an explicit name instead of hand rolling a m…

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…atch 3x

Prefer trace level instrumentation for the new noisy instrument attri…

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clubby789 mentioned this pull request Sep 26, 2022

Array indexed by enum cast to usize no longer has bounds check eliminated #102303

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scottmcm mentioned this pull request Sep 28, 2022

as cast of non-Copy enum is no longer a move #102389

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pnkfelix mentioned this pull request Oct 13, 2022

Ensure enum cast moves #103016

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Change enum->int casts to not go through MIR casts. #96862

Change enum->int casts to not go through MIR casts. #96862

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Change enum->int casts to not go through MIR casts. #96862

Change enum->int casts to not go through MIR casts. #96862

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