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Auto merge of #124190 - RalfJung:pat-compare-with-fast-path, r=Nadrieril

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PatRangeBoundary::compare_with: als add a fast-path for signed integers

Not sure if we have a benchmark that hits this... but it seems odd to only do this for unsigned integers.
This commit is contained in:
bors 2024-04-20 12:54:15 +00:00
parent 584f183dc0 727fe81fd6
commit c3ceb00281
1 changed files with 8 additions and 5 deletions
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13
compiler/rustc_middle/src/thir.rs
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@ -1006,15 +1006,18 @@ pub fn compare_with(
// This code is hot when compiling matches with many ranges. So we
// special-case extraction of evaluated scalars for speed, for types where
// unsigned int comparisons are appropriate. E.g. `unicode-normalization` has
// we can do scalar comparisons. E.g. `unicode-normalization` has
// many ranges such as '\u{037A}'..='\u{037F}', and chars can be compared
// in this way.
(Finite(a), Finite(b)) if matches!(ty.kind(), ty::Uint(_) | ty::Char) => {
(Finite(a), Finite(b)) if matches!(ty.kind(), ty::Int(_) | ty::Uint(_) | ty::Char) => {
if let (Some(a), Some(b)) = (a.try_to_scalar_int(), b.try_to_scalar_int()) {
let sz = ty.primitive_size(tcx);
let a = a.assert_uint(sz);
let b = b.assert_uint(sz);
return Some(a.cmp(&b));
let cmp = match ty.kind() {
ty::Uint(_) | ty::Char => a.assert_uint(sz).cmp(&b.assert_uint(sz)),
ty::Int(_) => a.assert_int(sz).cmp(&b.assert_int(sz)),
_ => unreachable!(),
};
return Some(cmp);
}
}
_ => {}