}
}
+pub fn remove_unused_definitions<'tcx>(body: &mut Body<'tcx>) {
+ // First, we're going to get a count of *actual* uses for every `Local`.
+ let mut used_locals = UsedLocals::new(body);
+
+ // Next, we're going to remove any `Local` with zero actual uses. When we remove those
+ // `Locals`, we're also going to subtract any uses of other `Locals` from the `used_locals`
+ // count. For example, if we removed `_2 = discriminant(_1)`, then we'll subtract one from
+ // `use_counts[_1]`. That in turn might make `_1` unused, so we loop until we hit a
+ // fixedpoint where there are no more unused locals.
+ remove_unused_definitions_helper(&mut used_locals, body);
+}
+
pub fn simplify_locals<'tcx>(body: &mut Body<'tcx>, tcx: TyCtxt<'tcx>) {
// First, we're going to get a count of *actual* uses for every `Local`.
let mut used_locals = UsedLocals::new(body);
// count. For example, if we removed `_2 = discriminant(_1)`, then we'll subtract one from
// `use_counts[_1]`. That in turn might make `_1` unused, so we loop until we hit a
// fixedpoint where there are no more unused locals.
- remove_unused_definitions(&mut used_locals, body);
+ remove_unused_definitions_helper(&mut used_locals, body);
// Finally, we'll actually do the work of shrinking `body.local_decls` and remapping the `Local`s.
let map = make_local_map(&mut body.local_decls, &used_locals);
}
/// Removes unused definitions. Updates the used locals to reflect the changes made.
-fn remove_unused_definitions(used_locals: &mut UsedLocals, body: &mut Body<'_>) {
+fn remove_unused_definitions_helper(used_locals: &mut UsedLocals, body: &mut Body<'_>) {
// The use counts are updated as we remove the statements. A local might become unused
// during the retain operation, leading to a temporary inconsistency (storage statements or
// definitions referencing the local might remain). For correctness it is crucial that this