user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

add fast-path for wide pointers

Browse source
This commit is contained in:
Ralf Jung 2025-11-17 09:10:45 +01:00
parent 635bacf466
commit 5a76a60d01
1 changed files with 13 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

17
compiler/rustc_const_eval/src/interpret/place.rs
View file

@ -5,8 +5,8 @@
use either::{Either, Left, Right};
use rustc_abi::{BackendRepr, HasDataLayout, Size};
use rustc_data_structures::assert_matches;
use rustc_middle::ty::Ty;
use rustc_middle::ty::layout::TyAndLayout;
use rustc_middle::ty::{self, Ty};
use rustc_middle::{bug, mir, span_bug};
use tracing::field::Empty;
use tracing::{instrument, trace};
@ -884,18 +884,27 @@ where
dest.layout().ty,
);
}
// If the source has padding, we want to always do the mem-to-mem copy to ensure consistent
// If the source has padding, we want to always do a mem-to-mem copy to ensure consistent
// padding in the target independent of layout choices.
let src_has_padding = match src.layout().backend_repr {
BackendRepr::Scalar(_) => false,
BackendRepr::ScalarPair(left, right)
if matches!(src.layout().ty.kind(), ty::Ref(..) | ty::RawPtr(..)) =>
{
// Wide pointers never have padding, so we can avoid calling `size()`.
debug_assert_eq!(left.size(self) + right.size(self), src.layout().size);
false
}
BackendRepr::ScalarPair(left, right) => {
let left_size = left.size(self);
let right_size = right.size(self);
// We have padding if the sizes don't add up to the total.
left_size + right_size != src.layout().size
}
// Everything else can only exist in memory anyway.
_ => true,
// Everything else can only exist in memory anyway, so it doesn't matter.
BackendRepr::SimdVector { .. }
| BackendRepr::ScalableVector { .. }
| BackendRepr::Memory { .. } => true,
};
let src_val = if src_has_padding {