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Introduce small cache to avoid recomputing the same value twice

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This commit is contained in:
Urgau 2023-12-15 11:30:16 +01:00
parent 915200fbe0
commit 6a8f50e907
1 changed files with 13 additions and 4 deletions
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17
compiler/rustc_lint/src/reference_casting.rs
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@ -42,8 +42,15 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
let init = cx.expr_or_init(e);
let orig_cast = if init.span != e.span { Some(init.span) } else { None };
// small cache to avoid recomputing needlesly computing peel_casts of init
let mut peel_casts = {
let mut peel_casts_cache = None;
move || *peel_casts_cache.get_or_insert_with(|| peel_casts(cx, init))
};
if matches!(pat, PatternKind::Borrow { mutbl: Mutability::Mut } | PatternKind::Assign)
&& let Some(ty_has_interior_mutability) = is_cast_from_ref_to_mut_ptr(cx, init)
&& let Some(ty_has_interior_mutability) =
is_cast_from_ref_to_mut_ptr(cx, init, &mut peel_casts)
{
let ty_has_interior_mutability = ty_has_interior_mutability.then_some(());
@ -65,7 +72,7 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
}
if let Some((from_ty_layout, to_ty_layout, e_alloc)) =
is_cast_to_bigger_memory_layout(cx, init)
is_cast_to_bigger_memory_layout(cx, init, &mut peel_casts)
{
cx.emit_span_lint(
INVALID_REFERENCE_CASTING,
@ -141,6 +148,7 @@ fn ptr_write<'tcx>(
fn is_cast_from_ref_to_mut_ptr<'tcx>(
cx: &LateContext<'tcx>,
orig_expr: &'tcx Expr<'tcx>,
mut peel_casts: impl FnMut() -> (&'tcx Expr<'tcx>, bool),
) -> Option<bool> {
let end_ty = cx.typeck_results().node_type(orig_expr.hir_id);
@ -149,7 +157,7 @@ fn is_cast_from_ref_to_mut_ptr<'tcx>(
return None;
}
let (e, need_check_freeze) = peel_casts(cx, orig_expr);
let (e, need_check_freeze) = peel_casts();
let start_ty = cx.typeck_results().node_type(e.hir_id);
if let ty::Ref(_, inner_ty, Mutability::Not) = start_ty.kind() {
@ -171,6 +179,7 @@ fn is_cast_from_ref_to_mut_ptr<'tcx>(
fn is_cast_to_bigger_memory_layout<'tcx>(
cx: &LateContext<'tcx>,
orig_expr: &'tcx Expr<'tcx>,
mut peel_casts: impl FnMut() -> (&'tcx Expr<'tcx>, bool),
) -> Option<(TyAndLayout<'tcx>, TyAndLayout<'tcx>, Expr<'tcx>)> {
let end_ty = cx.typeck_results().node_type(orig_expr.hir_id);
@ -178,7 +187,7 @@ fn is_cast_to_bigger_memory_layout<'tcx>(
return None;
};
let (e, _) = peel_casts(cx, orig_expr);
let (e, _) = peel_casts();
let start_ty = cx.typeck_results().node_type(e.hir_id);
let ty::Ref(_, inner_start_ty, _) = start_ty.kind() else {