| Age | Commit message (Collapse) | Author | Lines |
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add more completion about "impl"
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fix: Fix a bug in MBE expansion that arose from incorrect fixing of an older bug in MBE
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Allow optimizing out `panic_bounds_check` in Unicode checks.
Allow optimizing out `panic_bounds_check` in Unicode checks.
For context, see https://github.com/japaric/ufmt/issues/52#issuecomment-2699207241.
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Expose algebraic floating point intrinsics
# Problem
A stable Rust implementation of a simple dot product is 8x slower than C++ on modern x86-64 CPUs. The root cause is an inability to let the compiler reorder floating point operations for better vectorization.
See https://github.com/calder/dot-bench for benchmarks. Measurements below were performed on a i7-10875H.
### C++: 10us ✅
With Clang 18.1.3 and `-O2 -march=haswell`:
<table>
<tr>
<th>C++</th>
<th>Assembly</th>
</tr>
<tr>
<td>
<pre lang="cc">
float dot(float *a, float *b, size_t len) {
#pragma clang fp reassociate(on)
float sum = 0.0;
for (size_t i = 0; i < len; ++i) {
sum += a[i] * b[i];
}
return sum;
}
</pre>
</td>
<td>
<img src="https://github.com/user-attachments/assets/739573c0-380a-4d84-9fd9-141343ce7e68" />
</td>
</tr>
</table>
### Nightly Rust: 10us ✅
With rustc 1.86.0-nightly (8239a37f9) and `-C opt-level=3 -C target-feature=+avx2,+fma`:
<table>
<tr>
<th>Rust</th>
<th>Assembly</th>
</tr>
<tr>
<td>
<pre lang="rust">
fn dot(a: &[f32], b: &[f32]) -> f32 {
let mut sum = 0.0;
for i in 0..a.len() {
sum = fadd_algebraic(sum, fmul_algebraic(a[i], b[i]));
}
sum
}
</pre>
</td>
<td>
<img src="https://github.com/user-attachments/assets/9dcf953a-2cd7-42f3-bc34-7117de4c5fb9" />
</td>
</tr>
</table>
### Stable Rust: 84us ❌
With rustc 1.84.1 (e71f9a9a9) and `-C opt-level=3 -C target-feature=+avx2,+fma`:
<table>
<tr>
<th>Rust</th>
<th>Assembly</th>
</tr>
<tr>
<td>
<pre lang="rust">
fn dot(a: &[f32], b: &[f32]) -> f32 {
let mut sum = 0.0;
for i in 0..a.len() {
sum += a[i] * b[i];
}
sum
}
</pre>
</td>
<td>
<img src="https://github.com/user-attachments/assets/936a1f7e-33e4-4ff8-a732-c3cdfe068dca" />
</td>
</tr>
</table>
# Proposed Change
Add `core::intrinsics::f*_algebraic` wrappers to `f16`, `f32`, `f64`, and `f128` gated on a new `float_algebraic` feature.
# Alternatives Considered
https://github.com/rust-lang/rust/issues/21690 has a lot of good discussion of various options for supporting fast math in Rust, but is still open a decade later because any choice that opts in more than individual operations is ultimately contrary to Rust's design principles.
In the mean time, processors have evolved and we're leaving major performance on the table by not supporting vectorization. We shouldn't make users choose between an unstable compiler and an 8x performance hit.
# References
* https://github.com/rust-lang/rust/issues/21690
* https://github.com/rust-lang/libs-team/issues/532
* https://github.com/rust-lang/rust/issues/136469
* https://github.com/calder/dot-bench
* https://www.felixcloutier.com/x86/vfmadd132ps:vfmadd213ps:vfmadd231ps
try-job: x86_64-gnu-nopt
try-job: x86_64-gnu-aux
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feat(project-model): provide flag for no deps
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Cargo update
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davidbarsky/davidbarsky/fix-panic-in-view-crate-graph
internal: fix panic in `view_crate_graph`
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fix: don't drop references with more than one definition.
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Implicit field references during struct initialization were
being dropped because get_definition was returning None because
there were multiple definitions.
This adds a new helper, `get_defintions`, that supports returning
more than one definition for a given token and hooks it up.
Fixes #19393
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A Cargo project can now be built without any dependency metadata being fetched.
Signed-off-by: Prajwal S N <prajwalnadig21@gmail.com>
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Add another Miri-detected bug to README.md
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verb -> participle
Co-authored-by: Ralf Jung <post@ralfj.de>
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Signed-off-by: Prajwal S N <prajwalnadig21@gmail.com>
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Add helper function for checking LLD usage to `run-make-support`
Extracted out of https://github.com/rust-lang/rust/pull/138645, should be a simple refactoring.
r? ``@jieyouxu``
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compiletest: Encapsulate all of the code that touches libtest
Compiletest currently relies on unstable libtest APIs in order to actually execute tests. That's unfortunate, but removing the dependency isn't trivial.
However, we can make a small step towards removing the libtest dependency by encapsulating the libtest interactions into a single dedicated module. That makes it easier to see what parts of libtest are actually used.
---
As a side-effect of moving the `test_opts` function into that dedicated module, this PR also ends up allowing `--fail-fast` to be passed on the command line, instead of requiring an environment variable.
---
There is still (at least) one other aspect of the libtest dependency that this PR does not address, namely the fact that we rely on libtest's output capture (via unstable std APIs) to capture the output that we print during individual tests. I hope to do something about that at some point.
r? jieyouxu
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Included API:
impl<T: Copy> Cell<T> {
pub fn update(&self, f: impl FnOnce(T) -> T);
}
Closes: https://github.com/rust-lang/rust/issues/50186
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impl !PartialOrd for HirId
revive of https://github.com/rust-lang/rust/pull/92233
Another checkbox of https://github.com/rust-lang/rust/issues/90317, another small step in making incremental less likely to die in horrible ways
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Tighten up assignment operator representations.
This is step 3 of [MCP 831](https://github.com/rust-lang/compiler-team/issues/831).
r? `@spastorino`
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Miri detected this bug in Mockall: https://github.com/asomers/mockall/issues/647
[skip ci]
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Signed-off-by: Prajwal S N <prajwalnadig21@gmail.com>
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This was being used by a single assist, which qualifies under the "refactor"
kind. The variant has been removed, and all usages updated accordingly.
Signed-off-by: Prajwal S N <prajwalnadig21@gmail.com>
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In the AST, currently we use `BinOpKind` within `ExprKind::AssignOp` and
`AssocOp::AssignOp`, even though this allows some nonsensical
combinations. E.g. there is no `&&=` operator. Likewise for HIR and
THIR.
This commit introduces `AssignOpKind` which only includes the ten
assignable operators, and uses it in `ExprKind::AssignOp` and
`AssocOp::AssignOp`. (And does similar things for `hir::ExprKind` and
`thir::ExprKind`.) This avoids the possibility of nonsensical
combinations, as seen by the removal of the `bug!` case in
`lang_item_for_binop`.
The commit is mostly plumbing, including:
- Adds an `impl From<AssignOpKind> for BinOpKind` (AST) and `impl
From<AssignOp> for BinOp` (MIR/THIR).
- `BinOpCategory` can now be created from both `BinOpKind` and
`AssignOpKind`.
- Replaces the `IsAssign` type with `Op`, which has more information and
a few methods.
- `suggest_swapping_lhs_and_rhs`: moves the condition to the call site,
it's easier that way.
- `check_expr_inner`: had to factor out some code into a separate
method.
I'm on the fence about whether avoiding the nonsensical combinations is
worth the extra code.
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Because it's nice to avoid passing in unnecessary data.
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