can_const_prop: IndexVec<Local, ConstPropMode>,
// false at the beginning, once set, there are not allowed to be any more assignments
found_assignment: BitSet<Local>,
+ // Cache of locals' information
+ local_kinds: IndexVec<Local, LocalKind>,
}
impl CanConstProp {
let mut cpv = CanConstProp {
can_const_prop: IndexVec::from_elem(ConstPropMode::FullConstProp, &body.local_decls),
found_assignment: BitSet::new_empty(body.local_decls.len()),
+ local_kinds: IndexVec::from_fn_n(
+ |local| body.local_kind(local),
+ body.local_decls.len(),
+ ),
};
for (local, val) in cpv.can_const_prop.iter_enumerated_mut() {
// cannot use args at all
// lint for x != y
// FIXME(oli-obk): lint variables until they are used in a condition
// FIXME(oli-obk): lint if return value is constant
- let local_kind = body.local_kind(local);
-
- if local_kind == LocalKind::Arg || local_kind == LocalKind::Var {
+ if cpv.local_kinds[local] == LocalKind::Arg || cpv.local_kinds[local] == LocalKind::Var
+ {
*val = ConstPropMode::OnlyPropagateInto;
trace!("local {:?} can't be const propagated because it's not a temporary", local);
}
| NonMutatingUse(NonMutatingUseContext::Move)
| NonMutatingUse(NonMutatingUseContext::Inspect)
| NonMutatingUse(NonMutatingUseContext::Projection)
- | MutatingUse(MutatingUseContext::Projection)
| NonUse(_) => {}
+ MutatingUse(MutatingUseContext::Projection) => {
+ if self.local_kinds[local] != LocalKind::Temp {
+ self.can_const_prop[local] = ConstPropMode::NoPropagation;
+ }
+ }
_ => {
trace!("local {:?} can't be propagaged because it's used: {:?}", local, context);
self.can_const_prop[local] = ConstPropMode::NoPropagation;