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Cut code size for feature hashing

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This locally cuts ~32 kB of .text instructions.
This commit is contained in:
Mark Rousskov 2023-11-26 22:32:41 -05:00
parent 1bcbb7c93b
commit 1487bd6a17
2 changed files with 14 additions and 6 deletions
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12
compiler/rustc_feature/src/unstable.rs
View File

@ -50,6 +50,8 @@ macro_rules! declare_features {
}),+
];
const NUM_FEATURES: usize = UNSTABLE_FEATURES.len();
/// A set of features to be used by later passes.
#[derive(Clone, Default, Debug)]
pub struct Features {
@ -82,8 +84,14 @@ macro_rules! declare_features {
self.declared_features.insert(symbol);
}
pub fn walk_feature_fields(&self, mut f: impl FnMut(&str, bool)) {
$(f(stringify!($feature), self.$feature);)+
/// This is intended for hashing the set of active features.
///
/// The expectation is that this produces much smaller code than other alternatives.
///
/// Note that the total feature count is pretty small, so this is not a huge array.
#[inline]
pub fn all_features(&self) -> [u8; NUM_FEATURES] {
[$(self.$feature as u8),+]
}
/// Is the given feature explicitly declared, i.e. named in a

8
compiler/rustc_query_system/src/ich/impls_syntax.rs
View File

@ -117,9 +117,9 @@ impl<'tcx> HashStable<StableHashingContext<'tcx>> for rustc_feature::Features {
self.declared_lang_features.hash_stable(hcx, hasher);
self.declared_lib_features.hash_stable(hcx, hasher);
self.walk_feature_fields(|feature_name, value| {
feature_name.hash_stable(hcx, hasher);
value.hash_stable(hcx, hasher);
});
self.all_features()[..].hash_stable(hcx, hasher);
for feature in rustc_feature::UNSTABLE_FEATURES.iter() {
feature.feature.name.hash_stable(hcx, hasher);
}
}
}