Fix Dest Prop
Closes#82678, #79191 .
This was not originally a total re-write of the pass but is has gradually turned into one. Notable changes:
1. Significant improvements to documentation all around. The top of the file has been extended with a more precise argument for soundness. The code should be fairly readable, and I've done my best to add useful comments wherever possible. I would very much like for the bus factor to not be one on this code.
3. Improved handling of conflicts that are not visible in normal dataflow. This was the cause of #79191. Handling this correctly requires us to make decision about the semantics and specifically evaluation order of basically all MIR constructs (see specifically #68364#71117. The way this is implemented is based on my preferred resolution to these questions around the semantics of assignment statements.
4. Some re-architecting to improve performance. More details below.
5. Possible future improvements to this optimization are documented, and the code is written with the needs of those improvements in mind. The hope is that adding support for more precise analyses will not require a full re-write of this opt, but just localized changes.
### Regarding Performance
The previous approach had some performance issues; letting `l` be the number of locals and `s` be the number of statements/terminators, the runtime of the pass was `O(l^2 * s)`, both in theory and in practice. This version is smarter about not calculating unnecessary things and doing more caching. Our runtime is now dominated by one invocation of `MaybeLiveLocals` for each "round," and the number of rounds is less than 5 in over 90% of cases. This means it's linear-ish in practice.
r? `@oli-obk` who reviewed the last version of this, but review from anyone else would be more than welcome
This fixes a number of correctness issues from the previous version. Additionally, we use a new
strategy which has much better performance charactersitics and also finds more opportunities to
apply the optimization.
Stop peeling the last iteration of the loop in `Vec::resize_with`
`resize_with` uses the `ExtendWith` code that peels the last iteration:
341d8b8a2c/library/alloc/src/vec/mod.rs (L2525-L2529)
But that's kinda weird for `ExtendFunc` because it does the same thing on the last iteration anyway:
341d8b8a2c/library/alloc/src/vec/mod.rs (L2494-L2502)
So this just has it use the normal `extend`-from-`TrustedLen` code instead.
r? `@ghost`
Revert "Don't set `is_preview` for clippy and rustfmt"
This reverts commit fb3e724d76, which broke `rustup update` for anyone with clippy or rustfmt installed.
Fixes https://github.com/rust-lang/rust/issues/104930.
r? `@Mark-Simulacrum`
`@bors` p=50 fixes nightly
Rollup of 7 pull requests
Successful merges:
- #104786 (Use the power of adding helper function to simplify code w/ `Mutability`)
- #104788 (Do not record unresolved const vars in generator interior)
- #104909 (Rename `normalize_opaque_types` to `reveal_opaque_types_in_bounds`)
- #104921 (Remove unnecessary binder from `get_impl_future_output_ty`)
- #104924 (jsondoclint: Accept trait alias is places where trait expected.)
- #104928 (rustdoc: use flexbox CSS to align sidebar button instead of position)
- #104943 (jsondoclint: Handle using enum variants and glob using enums.)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
jsondoclint: Handle using enum variants and glob using enums.
More work on jsondoclint for `core.json`
Closes#104942
r? `@GuillaumeGomez`
`@rustbot` modify labels: +A-testsuite
jsondoclint: Accept trait alias is places where trait expected.
More work to make `jsondoclint` work for `core.json`
Closes#104923
r? `@GuillaumeGomez`
`@rustbot` modify labels: +A-testsuite
Remove unnecessary binder from `get_impl_future_output_ty`
We never construct an `async fn` with a higher-ranked `impl Future` bound anyways, and basically all the call-sites already skip the binder.
Rename `normalize_opaque_types` to `reveal_opaque_types_in_bounds`
1. The query name is a bit misleading, since it doesn't do any associated type normalization, and
2. since it only takes a predicate list, it sounds a bit more powerful than it actually is.
Do not record unresolved const vars in generator interior
Don't record types in the generator interior when we see unresolved const variables.
We already do this for associated types -- this is important to avoid unresolved inference variables in the generator results during writeback, since the writeback results get stable hashed in incremental mode.
Fixes#104787
Remove AscribeUserTypeCx
r? ``@compiler-errors``
This basically inlines `AscribeUserTypeCx::relate_mir_and_user_ty` into `type_op_ascribe_user_type_with_span` which is the only place where it's used and makes direct use of `ObligationCtxt` API.
Unsupported query error now specifies if its unsupported for local or external crate
Fixes#101666.
I had to move `keys.rs` from `rustc_query_impl` to `rustc_middle`. I don't know if that is problematic. I couldn't think of any other way to get the needed information inside `rustc_middle`.
r? ```@jyn514```
Refine `instruction_set` MIR inline rules
Previously an exact match of the `instruction_set` attribute was required for an MIR inline to be considered. This change checks for an exact match *only* if the callee sets an `instruction_set` in the first place. When the callee does not declare an instruction set then it is considered to be platform agnostic code and it's allowed to be inline'd into the caller.
cc ``@oli-obk``
[Edit] Zulip Context: https://rust-lang.zulipchat.com/#narrow/stream/189540-t-compiler.2Fwg-mir-opt/topic/What.20exactly.20does.20the.20MIR.20optimizer.20do.3F
Manually implement PartialEq for Option<T> and specialize non-nullable types
This PR manually implements `PartialEq` and `StructuralPartialEq` for `Option`, which seems to produce slightly better codegen than the automatically derived implementation.
It also allows specializing on the `core::num::NonZero*` and `core::ptr::NonNull` types, taking advantage of the niche optimization by transmuting the `Option<T>` to `T` to be compared directly, which can be done in just two instructions.
A comparison of the original, new and specialized code generation is available [here](https://godbolt.org/z/dE4jxdYsa).
Enable profiler in dist-riscv64-linux
Build the profiler runtime to allow using -C profile-generate and -C instrument-coverage on riscv64-linux.
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Add `ConstKind::Expr`
Starting to implement `ty::ConstKind::Abstract`, most of the match cases are stubbed out, some I was unsure what to add, others I didn't want to add until a more complete implementation was ready.
r? `@lcnr`
Previously an exact match of the `instruction_set` attribute was required for an MIR inline to be considered. This change checks for an exact match *only* if the callee sets an `instruction_set` in the first place. When the callee does not declare an instruction set then it is considered to be platform agnostic code and it's allowed to be inline'd into the caller.
rustdoc: fix broken tooltip CSS
text `#ffffff` on background `#fdffd3` fails the [WCAG color contrast checker], and seems like a mistake in 16b55903ee.
Making the cursor a pointer is misleading, since clicking it doesn't do anything.
[WCAG color contrast checker]: https://accessibleweb.com/color-contrast-checker/
rustbuild: Don't build doc::SharedAssets when building JSON docs.
Previously, running `./x doc library/core/ --json` on a plain build would panic bootstrap.
```
$ ./x doc library/core/ --json
Building rustbuild
Blocking waiting for file lock on package cache
Compiling bootstrap v0.0.0 (/home/nixon/dev/rust/rust/src/bootstrap)
Finished dev [unoptimized] target(s) in 4.47s
thread 'main' panicked at 'fs::write(&version_info, &info) failed with No such file or directory (os error 2) ("/home/nixon/dev/rust/rust/build/x86_64-unknown-linux-gnu/doc/version_info.html")', doc.rs:410:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Build completed unsuccessfully in 0:00:04
```
Becuase the `SharedAssets` step assumes that the HTML out dir has been created. This isn't true for JSON.
The fix is to not build shared assets when doing a JSON doc build, as it doesn't need them.
r? ``@jyn514``
``@rustbot`` modify labels: +A-rustdoc-json
rustc_codegen_ssa: write `.dwp` in a streaming fashion
When writing a `.dwp` file, rustc writes to a Vec first then to a BufWriter-wrapped file. It seems very likely that we can write in a streaming fashion to avoid double buffering in an intermediate Vec.
On my Linux machine, `.dwp` from the latest rust-lang/cargo is 113MiB. It may worth a stream writer, though I didn't do any benchmark 🙇🏾♂️.
