bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Auto merge of #120080 - cuviper:128-align-packed, r=nikic

Browse source 
Pack u128 in the compiler to mitigate new alignment

This is based on #116672, adding a new `#[repr(packed(8))]` wrapper on `u128` to avoid changing any of the compiler's size assertions. This is needed in two places:

* `SwitchTargets`, otherwise its `SmallVec<[u128; 1]>` gets padded up to 32 bytes.
* `LitKind::Int`, so that entire `enum` can stay 24 bytes.
  * This change definitely has far-reaching effects though, since it's public.
This commit is contained in:
bors 2024-01-22 13:08:19 +00:00
commit 3066253050
43 changed files with 173 additions and 86 deletions
Download patch file Download diff file Expand all files Collapse all files

2
compiler/rustc_mir_build/src/build/expr/as_constant.rs
View file

@ -153,7 +153,7 @@ fn lit_to_mir_constant<'tcx>(
ConstValue::Scalar(Scalar::from_uint(*n, Size::from_bytes(1)))
}
(ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => {
trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?
trunc(if neg { (n.get() as i128).overflowing_neg().0 as u128 } else { n.get() })?
}
(ast::LitKind::Float(n, _), ty::Float(fty)) => parse_float_into_constval(*n, *fty, neg)
.ok_or_else(|| {

2
compiler/rustc_mir_build/src/thir/constant.rs
View file

@ -54,7 +54,7 @@ pub(crate) fn lit_to_const<'tcx>(
}
(ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => {
let scalar_int =
trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?;
trunc(if neg { (n.get() as i128).overflowing_neg().0 as u128 } else { n.get() })?;
ty::ValTree::from_scalar_int(scalar_int)
}
(ast::LitKind::Bool(b), ty::Bool) => ty::ValTree::from_scalar_int((*b).into()),