bjoernager/rust
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Remove OnlyPropagateInto.

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This commit is contained in:
Camille GILLOT 2023-03-07 15:04:53 +00:00
parent 24dbf9c112
commit 9928d0e566
3 changed files with 13 additions and 34 deletions
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35
compiler/rustc_mir_transform/src/const_prop.rs
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@ -718,8 +718,6 @@ pub enum ConstPropMode {
FullConstProp,
/// The `Local` can only be propagated into and from its own block.
OnlyInsideOwnBlock,
/// The `Local` can be propagated into but reads cannot be propagated.
OnlyPropagateInto,
/// The `Local` cannot be part of propagation at all. Any statement
/// referencing it either for reading or writing will not get propagated.
NoPropagation,
@ -729,8 +727,6 @@ pub struct CanConstProp {
can_const_prop: IndexVec<Local, ConstPropMode>,
// False at the beginning. Once set, no more assignments are allowed to that local.
found_assignment: BitSet<Local>,
// Cache of locals' information
local_kinds: IndexVec<Local, LocalKind>,
}
impl CanConstProp {
@ -743,10 +739,6 @@ 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() {
let ty = body.local_decls[local].ty;
@ -759,24 +751,10 @@ impl CanConstProp {
continue;
}
}
// Cannot use args at all
// Cannot use locals because if x < y { y - x } else { x - y } would
// 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
if cpv.local_kinds[local] == LocalKind::Arg {
*val = ConstPropMode::OnlyPropagateInto;
trace!(
"local {:?} can't be const propagated because it's a function argument",
local
);
} else if cpv.local_kinds[local] == LocalKind::Var {
*val = ConstPropMode::OnlyInsideOwnBlock;
trace!(
"local {:?} will only be propagated inside its block, because it's a user variable",
local
);
}
}
// Consider that arguments are assigned on entry.
for arg in body.args_iter() {
cpv.found_assignment.insert(arg);
}
cpv.visit_body(&body);
cpv.can_const_prop
@ -806,7 +784,6 @@ impl Visitor<'_> for CanConstProp {
// states as applicable.
ConstPropMode::OnlyInsideOwnBlock => {}
ConstPropMode::NoPropagation => {}
ConstPropMode::OnlyPropagateInto => {}
other @ ConstPropMode::FullConstProp => {
trace!(
"local {:?} can't be propagated because of multiple assignments. Previous state: {:?}",
@ -897,7 +874,7 @@ impl<'tcx> MutVisitor<'tcx> for ConstPropagator<'_, 'tcx> {
place.local
);
}
ConstPropMode::OnlyPropagateInto | ConstPropMode::NoPropagation => {
ConstPropMode::NoPropagation => {
trace!("can't propagate into {:?}", place);
if place.local != RETURN_PLACE {
Self::remove_const(&mut self.ecx, place.local);
@ -933,7 +910,7 @@ impl<'tcx> MutVisitor<'tcx> for ConstPropagator<'_, 'tcx> {
Self::remove_const(&mut self.ecx, place.local);
}
}
ConstPropMode::OnlyPropagateInto | ConstPropMode::NoPropagation => {
ConstPropMode::NoPropagation => {
Self::remove_const(&mut self.ecx, place.local);
}
}