New MIR optimization pass to reduce branches on match of tuples of enums
Fixes#68867 by adding a new pass that turns something like
```rust
let x: Option<()>;
let y: Option<()>;
match (x,y) {
(Some(_), Some(_)) => {0},
_ => {1}
}
```
into something like
```rust
let x: Option<()>;
let y: Option<()>;
let discriminant_x = // get discriminant of x
let discriminant_y = // get discriminant of x
if discriminant_x != discriminant_y {1} else {0}
```
The opt-diffs still have the old basic blocks like
```
bb3: {
_8 = discriminant((*(_4.1: &ViewportPercentageLength))); // scope 0 at $DIR/early-otherwise-branch-68867.rs:21:21: 21:30
switchInt(move _8) -> [1_isize: bb7, otherwise: bb2]; // scope 0 at $DIR/early-otherwise-branch-68867.rs:21:21: 21:30
}
bb4: {
_9 = discriminant((*(_4.1: &ViewportPercentageLength))); // scope 0 at $DIR/early-otherwise-branch-68867.rs:22:23: 22:34
switchInt(move _9) -> [2_isize: bb8, otherwise: bb2]; // scope 0 at $DIR/early-otherwise-branch-68867.rs:22:23: 22:34
}
bb5: {
_10 = discriminant((*(_4.1: &ViewportPercentageLength))); // scope 0 at $DIR/early-otherwise-branch-68867.rs:23:23: 23:34
switchInt(move _10) -> [3_isize: bb9, otherwise: bb2]; // scope 0 at $DIR/early-otherwise-branch-68867.rs:23:23: 23:34
}
```
These do get removed on later passes. I'm not sure if I should include those passes in the test to make it clear?
Rollup of 15 pull requests
Successful merges:
- #76732 (Add docs for `BasicBlock`)
- #76832 (Let backends define custom targets)
- #76866 (Remove unused feature gates from library/ crates)
- #76875 (Move to intra-doc links in library/alloc/src/collections/binary_heap.rs)
- #76876 (Move to intra-doc links in collections/btree/map.rs and collections/linked_list.rs)
- #76877 (Move to intra-doc links in collections/vec_deque.rs and collections/vec_deque/drain.rs)
- #76878 (Move the version number to a plaintext file)
- #76883 (README.md: Remove prompts from code blocks)
- #76887 (Add missing examples on HashSet iter types)
- #76890 (use matches!() macro for simple if let conditions)
- #76891 (don't take `TyCtxt` by reference)
- #76910 (transmute: use diagnostic item)
- #76924 (Add tracking issue for feature(unix_socket_peek))
- #76926 (BTreeMap: code readability tweaks)
- #76940 (Don't allow implementing trait directly on type-alias-impl-trait)
Failed merges:
r? `@ghost`
Don't allow implementing trait directly on type-alias-impl-trait
This is specifically disallowed by the RFC, but we never added a check
for it.
Fixes#76202
transmute: use diagnostic item
closes#66075, we now have no remaining uses of `match_def_path` in the compiler while some uses still remain in `clippy`.
cc @RalfJung
Move the version number to a plaintext file
The Rust version number is currently embedded in bootstrap's source code, which makes it hard to update it automatically or access it outside of ./x.py (as you'd have to parse the source code).
This PR moves the version number to a standalone plaintext file, which makes accessing or updating it trivial.
r? @Mark-Simulacrum
Move to intra-doc links in collections/vec_deque.rs and collections/vec_deque/drain.rs
Helps with #75080.
@rustbot modify labels: T-doc, A-intra-doc-links
Remove unused feature gates from library/ crates
Removes some unused feature gates from library crates. It's likely not a complete list as I only tested a subset for which it's more likely that it is unused.
Stabilize some Result methods as const
Stabilize the following methods of Result as const:
- `is_ok`
- `is_err`
- `as_ref`
A test is also included, analogous to the test for `const_option`.
These methods are currently const under the unstable feature `const_result` (tracking issue: #67520).
I believe these methods to be eligible for stabilization because of the stabilization of #49146 (Allow if and match in constants) and the trivial implementations, see also: [PR#75463](https://github.com/rust-lang/rust/pull/75463) and [PR#76135](https://github.com/rust-lang/rust/pull/76135).
Note: these methods are the only methods currently under the `const_result` feature, thus this PR results in the removal of the feature.
Related: #76225
Rollup of 15 pull requests
Successful merges:
- #76722 (Test and fix Send and Sync traits of BTreeMap artefacts)
- #76766 (Extract some intrinsics out of rustc_codegen_llvm)
- #76800 (Don't generate bootstrap usage unless it's needed)
- #76809 (simplfy condition in ItemLowerer::with_trait_impl_ref())
- #76815 (Fix wording in mir doc)
- #76818 (Don't compile regex at every function call.)
- #76821 (Remove redundant nightly features)
- #76823 (black_box: silence unused_mut warning when building with cfg(miri))
- #76825 (use `array_windows` instead of `windows` in the compiler)
- #76827 (fix array_windows docs)
- #76828 (use strip_prefix over starts_with and manual slicing based on pattern length (clippy::manual_strip))
- #76840 (Move to intra doc links in core/src/future)
- #76845 (Use intra docs links in core::{ascii, option, str, pattern, hash::map})
- #76853 (Use intra-doc links in library/core/src/task/wake.rs)
- #76871 (support panic=abort in Miri)
Failed merges:
r? `@ghost`
support panic=abort in Miri
This is needed for https://github.com/rust-lang/miri/issues/1058 on Windows: we cannot run the inline-assembly versions of `abort`, so fall back to the intrinsic (which Miri supports).
use `array_windows` instead of `windows` in the compiler
I do think these changes are beautiful, but do have to admit that using type inference for the window length
can easily be confusing. This seems like a general issue with const generics, where inferring constants adds an additional
complexity which users have to learn and keep in mind.
Remove redundant nightly features
Removes a bunch of redundant/outdated nightly features. The first commit removes a `core_intrinsics` use for which a stable wrapper has been provided since. The second commit replaces the `const_generics` feature with `min_const_generics` which might get stabilized this year. The third commit is the result of a trial/error run of removing every single feature and then adding it back if compile failed. A bunch of unused features are the result that the third commit removes.
Don't compile regex at every function call.
Use `SyncOnceCell` to only compile it once.
I believe this still adds some kind of locking mechanism?
Related issue: https://github.com/rust-lang/rust/issues/76817
Don't generate bootstrap usage unless it's needed
Previously, `x.py` would unconditionally run `x.py build` to get the
help message. After https://github.com/rust-lang/rust/issues/76165,
when checking the CI stage was moved into `Config`, that would cause an
assertion failure (but only only in CI!):
```
thread 'main' panicked at 'assertion failed: `(left == right)`
left: `1`,
right: `2`', src/bootstrap/config.rs:619:49
```
This changes bootstrap to only generate a help message when it needs
to (when someone passes `--help`).
r? @Mark-Simulacrum
This should fix the CI failures in https://github.com/rust-lang/rust/pull/76797 and https://github.com/rust-lang/rust/pull/75991.
Extract some intrinsics out of rustc_codegen_llvm
A significant amount of intrinsics do not actually need backend-specific behaviors to be implemented, instead relying on methods already in rustc_codegen_ssa. So, extract those methods out to rustc_codegen_ssa, so that each backend doesn't need to reimplement the same code.
Almost everything should be a pretty direct translation. A notable not-direct-translation is `add_with_overflow` and friends being changed to `bx.checked_binop`, but it's pretty simple.
I could have been a lot more aggressive here and pulled out way more methods, and add a few new methods in the rustc_codegen_ssa "API". However, because this is my second rustc PR, I thought that moving those to a follow-up PR and doing more incremental changes here would be better (and I guess ask if this work is even desired in the first place). I'm hoping to eventually remove the mess of intrinsic handling in the backend entirely, which would be hecking fantastic ✨
Test and fix Send and Sync traits of BTreeMap artefacts
Fixes#76686.
I'm not quite sure what all this implies. E.g. comparing with the definitions for `NodeRef` in node.rs, maybe an extra bound `T: 'a` is useful for something. The test compiles on stable/beta (apart from `drain_filter`) so I bet `Sync` is equally desirable.
r? @Mark-Simulacrum
Validate constants during `const_eval_raw`
This PR implements the groundwork for https://github.com/rust-lang/rust/issues/72396
* constants are now validated during `const_eval_raw`
* to prevent cycle errors, we do not validate references to statics anymore beyond the fact that they are not dangling
* the `const_eval` query ICEs if used on `static` items
* as a side effect promoteds are now evaluated to `ConstValue::Scalar` again (since they are just a reference to the actual promoted allocation in most cases).
Some promotion cleanup
Based on top of both https://github.com/rust-lang/rust/pull/75502 and https://github.com/rust-lang/rust/pull/75585, this does some cleanup of the promotion code. The last 2 commits are new.
* Remove the remaining cases where `const fn` is treated different from `fn`. This means no longer promoting ptr-to-int casts, raw ptr operations, and union field accesses in `const fn` -- or anywhere, for that matter. These are all unstable in const-context so this should not break any stable code. Fixes https://github.com/rust-lang/rust/issues/75586.
* ~~Promote references to statics even outside statics (i.e., in functions) for consistency.~~
* Promote `&mut []` everywhere, not just in non-`const` functions, for consistency.
* Explain why we do not promote deref's of statics outside statics. ~~(This is the only remaining direct user of `const_kind`.)~~
This can only land once the other two PRs land; I am mostly putting this up already because I couldn't wait ;) and to get some feedback from `@rust-lang/wg-const-eval` .
