bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Do not create move paths that do not need dropping.

Browse source
This commit is contained in:
Camille GILLOT 2023-09-30 21:42:49 +00:00
parent f038882fc0
commit c9c0c0cbca
5 changed files with 64 additions and 60 deletions
Download patch file Download diff file Expand all files Collapse all files

17
compiler/rustc_mir_transform/src/elaborate_drops.rs
View file

@ -54,7 +54,10 @@ impl<'tcx> MirPass<'tcx> for ElaborateDrops {
let def_id = body.source.def_id();
let param_env = tcx.param_env_reveal_all_normalized(def_id);
let move_data = MoveData::gather_moves(&body, tcx, param_env, |_| true);
// For types that do not need dropping, the behaviour is trivial. So we only need to track
// init/uninit for types that do need dropping.
let move_data =
MoveData::gather_moves(&body, tcx, param_env, |ty| ty.needs_drop(tcx, param_env));
let elaborate_patch = {
let env = MoveDataParamEnv { move_data, param_env };
@ -338,6 +341,18 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> {
continue;
};
// This place does not need dropping. It is not have an associated move-path, so the
// match below will conservatively keep an unconditional drop. As that drop is useless,
// just remove it here and now.
if !place
.ty(&self.body.local_decls, self.tcx)
.ty
.needs_drop(self.tcx, self.env.param_env)
{
self.patch.patch_terminator(bb, TerminatorKind::Goto { target });
continue;
}
let path = self.move_data().rev_lookup.find(place.as_ref());
match path {
LookupResult::Exact(path) => {

3
compiler/rustc_mir_transform/src/remove_uninit_drops.rs
View file

@ -24,7 +24,8 @@ pub struct RemoveUninitDrops;
impl<'tcx> MirPass<'tcx> for RemoveUninitDrops {
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let param_env = tcx.param_env(body.source.def_id());
let move_data = MoveData::gather_moves(&body, tcx, param_env, |_| true);
let move_data =
MoveData::gather_moves(&body, tcx, param_env, |ty| ty.needs_drop(tcx, param_env));
let mdpe = MoveDataParamEnv { move_data, param_env };
let mut maybe_inits = MaybeInitializedPlaces::new(tcx, body, &mdpe)