Add new MIR constant propagation based on dataflow analysis
The current constant propagation in `rustc_mir_transform/src/const_prop.rs` fails to handle many cases that would be expected from a constant propagation optimization. For example:
```rust
let x = if true { 0 } else { 0 };
```
This pull request adds a new constant propagation MIR optimization pass based on the existing dataflow analysis framework. Since most of the analysis is not unique to constant propagation, a generic framework has been extracted. It works on top of the existing framework and could be reused for other optimzations.
Closes#80038. Closes#81605.
## Todo
### Essential
- [x] [Writes to inactive enum variants](https://github.com/rust-lang/rust/pull/101168#pullrequestreview-1089493974). Resolved by rejecting the registration of places with downcast projections for now. Could be improved by flooding other variants if mutable access to a variant is observed.
- [X] Handle [`StatementKind::CopyNonOverlapping`](https://github.com/rust-lang/rust/pull/101168#discussion_r957774914). Resolved by flooding the destination.
- [x] Handle `UnsafeCell` / `!Freeze` correctly.
- [X] Overflow propagation of `CheckedBinaryOp`: Decided to not propagate if overflow flag is `true` (`false` will still be propagated)
- [x] More documentation in general.
- [x] Arguments for correctness, documentation of necessary assumptions.
- [x] Better performance, or alternatively, require `-Zmir-opt-level=3` for now.
### Extra
- [x] Add explicit unreachability, i.e. upgrading the lattice from $\mathbb{P} \to \mathbb{V}$ to $\set{\bot} \cup (\mathbb{P} \to \mathbb{V})$.
- [x] Use storage statements to improve precision.
- [ ] Consider opening issue for duplicate diagnostics: https://github.com/rust-lang/rust/pull/101168#issuecomment-1276609950
- [ ] Flood moved-from places with $\bot$ (requires some changes for places with tracked projections).
- [ ] Add downcast projections back in.
- [ ] [Algebraic simplifications](https://github.com/rust-lang/rust/pull/101168#discussion_r957967878) (possibly with a shared API; done by old const prop).
- [ ] Propagation through slices / arrays.
- [ ] Find other optimizations that are done by old `const_prop.rs`, but not by this one.
Rollup of 11 pull requests
Successful merges:
- #101967 (Move `unix_socket_abstract` feature API to `SocketAddrExt`.)
- #102470 (Stabilize const char convert)
- #104223 (Recover from function pointer types with generic parameter list)
- #104229 (Don't print full paths in overlap errors)
- #104294 (Don't ICE with inline const errors during MIR build)
- #104332 (Fixed some `_i32` notation in `maybe_uninit`’s doc)
- #104349 (fix some typos in comments)
- #104350 (Fix x finding Python on Windows)
- #104356 (interpret: make check_mplace public)
- #104364 (rustdoc: Resolve doc links in external traits having local impls)
- #104378 (Bump chalk to v0.87)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
rustdoc: fix corner case in search keyboard commands
This fixes a bug when that shows up in nightly and in stable where:
* Search something
* Press down: first result is highlighted
* Press down: second result is highlighted
* Press down: third result is highlighted
* Press right: first result of second tab is highlighted
* Press left: third result of first tab is highlighted
* Press up: second result is highlighted
* Press up: first result is highlighted
* Press up: Search box is highlighted
* Press down: **third result** is highlighted, where it ought to highlight the first result
Fix missing minification for static files
It's a fix for https://github.com/rust-lang/rust/pull/101702.
The problem was that `Path::ends_with` doesn't do what we thought it does: it checks if the entire item is the last path part, no just if the "path string" ends with the given argument. So instead, I just used the `extension()` method to get the information we want.
cc `@jsha`
r? `@notriddle`
PS: Is it worth it to add a CI test to ensure that the minification was performed on JS and CSS files or not?
Remove unused symbols and diagnostic items
As the title suggests, this removes unused symbols from `sym::` and `#[rustc_diagnostic_item]` annotations that weren't mentioned anywhere.
Originally I tried to use grep, to find symbols and item names that are never mentioned via `sym::name`, however this produced a lot of false positives (?), for example clippy matching on `Symbol::as_str` or macros "implicitly" adding `sym::`. I ended up fixing all these false positives (?) by hand, but tbh I'm not sure if it was worth it...
Update compiler-builtins
This was originally a part of https://github.com/rust-lang/rust/pull/100316. However, extracting it to a seperate PR should help with any extra testing that might be needed.
Signed-off-by: Ayush Singh <ayushsingh1325@gmail.com>
Wrap bundled static libraries into object files
Fixes#103044 (not sure, couldn't test locally)
Bundled static libraries should be wrapped into object files as it's done for metadata file.
r? `@petrochenkov`
This rule was added in 152e888905 to push the
out-of-band content to the right while allowing it to line wrap when it got
too big. The idea was that the justification rule would fill the space
between the `<h1>` element and the `<div class="out-of-band">` element.
A later commit, 3cb03cb342, flattened the
in-band element into the `<h1>`, copying the `flex-grow` rule. This means
the `<h1>` element now grows to fill the space, so there's no need to
justify-content any more.
This commit also adds a test case for this.
Based on Wojciech Muła's "SIMD-friendly algorithms for substring searching"[0]
The two-way algorithm is Big-O efficient but it needs to preprocess the needle
to find a "criticla factorization" of it. This additional work is significant
for short needles. Additionally it mostly advances needle.len() bytes at a time.
The SIMD-based approach used here on the other hand can advance based on its
vector width, which can exceed the needle length. Except for pathological cases,
but due to being limited to small needles the worst case blowup is also small.
benchmarks taken on a Zen2:
```
16CGU, OLD:
test str::bench_contains_short_short ... bench: 27 ns/iter (+/- 1)
test str::bench_contains_short_long ... bench: 667 ns/iter (+/- 29)
test str::bench_contains_bad_naive ... bench: 131 ns/iter (+/- 2)
test str::bench_contains_bad_simd ... bench: 130 ns/iter (+/- 2)
test str::bench_contains_equal ... bench: 148 ns/iter (+/- 4)
16CGU, NEW:
test str::bench_contains_short_short ... bench: 8 ns/iter (+/- 0)
test str::bench_contains_short_long ... bench: 135 ns/iter (+/- 4)
test str::bench_contains_bad_naive ... bench: 130 ns/iter (+/- 2)
test str::bench_contains_bad_simd ... bench: 292 ns/iter (+/- 1)
test str::bench_contains_equal ... bench: 3 ns/iter (+/- 0)
1CGU, OLD:
test str::bench_contains_short_short ... bench: 30 ns/iter (+/- 0)
test str::bench_contains_short_long ... bench: 713 ns/iter (+/- 17)
test str::bench_contains_bad_naive ... bench: 131 ns/iter (+/- 3)
test str::bench_contains_bad_simd ... bench: 130 ns/iter (+/- 3)
test str::bench_contains_equal ... bench: 148 ns/iter (+/- 6)
1CGU, NEW:
test str::bench_contains_short_short ... bench: 10 ns/iter (+/- 0)
test str::bench_contains_short_long ... bench: 111 ns/iter (+/- 0)
test str::bench_contains_bad_naive ... bench: 135 ns/iter (+/- 3)
test str::bench_contains_bad_simd ... bench: 274 ns/iter (+/- 2)
test str::bench_contains_equal ... bench: 4 ns/iter (+/- 0)
```
[0] http://0x80.pl/articles/simd-strfind.html#sse-avx2
This rule was added in cc4f804829 because the help popover inherited the
font-size from the help button "?" icon.
It doesn't inherit this any more, because it was moved from being nested
inside the link to sharing a wrapper DIV with it.
Fix x finding Python on Windows
`x` searches through the path for `{dir}/python{2|3}?`, but this fails on Windows because the appropriate path is `{dir}/python.exe`.
This PR adds the expected `.exe` extension on Windows while searching.
Fixed some `_i32` notation in `maybe_uninit`’s doc
This PR just changed two lines in the documentation for `MaybeUninit`:
```rs
let val = 0x12345678i32;
```
was changed to:
```rs
let val = 0x12345678_i32;
```
in two doctests, making the values a tad easier to read.
It does not seem like there are other literals needing this change in the file.
