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slice.get(i) should use a slice projection in MIR, like slice[i] does

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This commit is contained in:
Scott McMurray
2025-03-29 02:34:15 -07:00
parent aa5832b142
commit 4668124cc7
15 changed files with 385 additions and 86 deletions
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46
compiler/rustc_mir_transform/src/lower_intrinsics.rs
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@@ -262,6 +262,52 @@ impl<'tcx> crate::MirPass<'tcx> for LowerIntrinsics {
});
terminator.kind = TerminatorKind::Goto { target };
}
sym::slice_get_unchecked => {
let target = target.unwrap();
let Ok([ptrish, index]) = take_array(args) else {
span_bug!(
terminator.source_info.span,
"Wrong number of arguments for {intrinsic:?}",
);
};
let place = ptrish.node.place().unwrap();
assert!(!place.is_indirect());
let updated_place = place.project_deeper(
&[
ProjectionElem::Deref,
ProjectionElem::Index(
index.node.place().unwrap().as_local().unwrap(),
),
],
tcx,
);
let ret_ty = generic_args.type_at(0);
let rvalue = match *ret_ty.kind() {
ty::RawPtr(_, Mutability::Not) => {
Rvalue::RawPtr(RawPtrKind::Const, updated_place)
}
ty::RawPtr(_, Mutability::Mut) => {
Rvalue::RawPtr(RawPtrKind::Mut, updated_place)
}
ty::Ref(region, _, Mutability::Not) => {
Rvalue::Ref(region, BorrowKind::Shared, updated_place)
}
ty::Ref(region, _, Mutability::Mut) => Rvalue::Ref(
region,
BorrowKind::Mut { kind: MutBorrowKind::Default },
updated_place,
),
_ => bug!("Unknown return type {ret_ty:?}"),
};
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Assign(Box::new((*destination, rvalue))),
});
terminator.kind = TerminatorKind::Goto { target };
}
sym::transmute | sym::transmute_unchecked => {
let dst_ty = destination.ty(local_decls, tcx).ty;
let Ok([arg]) = take_array(args) else {