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cjgillotcjgillot
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Merge if-let and match.
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‎compiler/rustc_mir_transform/src/const_prop.rs‎

Lines changed: 63 additions & 67 deletions
Original file line numberDiff line numberDiff line change
@@ -917,84 +917,80 @@ impl<'tcx> MutVisitor<'tcx> for ConstPropagator<'_, 'tcx> {
917917
trace!("visit_statement: {:?}", statement);
918918
let source_info = statement.source_info;
919919
self.source_info = Some(source_info);
920-
if let StatementKind::Assign(box (place, ref mut rval)) = statement.kind {
921-
let can_const_prop = self.ecx.machine.can_const_prop[place.local];
922-
if let Some(()) = self.const_prop(rval, place) {
923-
// This will return None if the above `const_prop` invocation only "wrote" a
924-
// type whose creation requires no write. E.g. a generator whose initial state
925-
// consists solely of uninitialized memory (so it doesn't capture any locals).
926-
if let Some(ref value) = self.get_const(place) && self.should_const_prop(value) {
927-
trace!("replacing {:?} with {:?}", rval, value);
928-
self.replace_with_const(rval, value, source_info);
929-
if can_const_prop == ConstPropMode::FullConstProp
930-
|| can_const_prop == ConstPropMode::OnlyInsideOwnBlock
931-
{
932-
trace!("propagated into {:?}", place);
920+
match statement.kind {
921+
StatementKind::Assign(box (place, ref mut rval)) => {
922+
let can_const_prop = self.ecx.machine.can_const_prop[place.local];
923+
if let Some(()) = self.const_prop(rval, place) {
924+
// This will return None if the above `const_prop` invocation only "wrote" a
925+
// type whose creation requires no write. E.g. a generator whose initial state
926+
// consists solely of uninitialized memory (so it doesn't capture any locals).
927+
if let Some(ref value) = self.get_const(place) && self.should_const_prop(value) {
928+
trace!("replacing {:?} with {:?}", rval, value);
929+
self.replace_with_const(rval, value, source_info);
930+
if can_const_prop == ConstPropMode::FullConstProp
931+
|| can_const_prop == ConstPropMode::OnlyInsideOwnBlock
932+
{
933+
trace!("propagated into {:?}", place);
934+
}
933935
}
934-
}
935-
match can_const_prop {
936-
ConstPropMode::OnlyInsideOwnBlock => {
937-
trace!(
938-
"found local restricted to its block. \
936+
match can_const_prop {
937+
ConstPropMode::OnlyInsideOwnBlock => {
938+
trace!(
939+
"found local restricted to its block. \
939940
Will remove it from const-prop after block is finished. Local: {:?}",
940-
place.local
941-
);
942-
}
943-
ConstPropMode::OnlyPropagateInto | ConstPropMode::NoPropagation => {
944-
trace!("can't propagate into {:?}", place);
945-
if place.local != RETURN_PLACE {
946-
Self::remove_const(&mut self.ecx, place.local);
941+
place.local
942+
);
947943
}
948-
}
949-
ConstPropMode::FullConstProp => {}
950-
}
951-
} else {
952-
// Const prop failed, so erase the destination, ensuring that whatever happens
953-
// from here on, does not know about the previous value.
954-
// This is important in case we have
955-
// ```rust
956-
// let mut x = 42;
957-
// x = SOME_MUTABLE_STATIC;
958-
// // x must now be uninit
959-
// ```
960-
// FIXME: we overzealously erase the entire local, because that's easier to
961-
// implement.
962-
trace!(
963-
"propagation into {:?} failed.
964-
Nuking the entire site from orbit, it's the only way to be sure",
965-
place,
966-
);
967-
Self::remove_const(&mut self.ecx, place.local);
968-
}
969-
} else {
970-
match statement.kind {
971-
StatementKind::SetDiscriminant { ref place, .. } => {
972-
match self.ecx.machine.can_const_prop[place.local] {
973-
ConstPropMode::FullConstProp | ConstPropMode::OnlyInsideOwnBlock => {
974-
if self.use_ecx(|this| this.ecx.statement(statement)).is_some() {
975-
trace!("propped discriminant into {:?}", place);
976-
} else {
944+
ConstPropMode::OnlyPropagateInto | ConstPropMode::NoPropagation => {
945+
trace!("can't propagate into {:?}", place);
946+
if place.local != RETURN_PLACE {
977947
Self::remove_const(&mut self.ecx, place.local);
978948
}
979949
}
980-
ConstPropMode::OnlyPropagateInto | ConstPropMode::NoPropagation => {
981-
Self::remove_const(&mut self.ecx, place.local);
982-
}
950+
ConstPropMode::FullConstProp => {}
983951
}
952+
} else {
953+
// Const prop failed, so erase the destination, ensuring that whatever happens
954+
// from here on, does not know about the previous value.
955+
// This is important in case we have
956+
// ```rust
957+
// let mut x = 42;
958+
// x = SOME_MUTABLE_STATIC;
959+
// // x must now be uninit
960+
// ```
961+
// FIXME: we overzealously erase the entire local, because that's easier to
962+
// implement.
963+
trace!(
964+
"propagation into {:?} failed.
965+
Nuking the entire site from orbit, it's the only way to be sure",
966+
place,
967+
);
968+
Self::remove_const(&mut self.ecx, place.local);
984969
}
985-
StatementKind::StorageLive(local) | StatementKind::StorageDead(local) => {
986-
let frame = self.ecx.frame_mut();
987-
frame.locals[local].value =
988-
if let StatementKind::StorageLive(_) = statement.kind {
989-
LocalValue::Live(interpret::Operand::Immediate(
990-
interpret::Immediate::Uninit,
991-
))
970+
}
971+
StatementKind::SetDiscriminant { ref place, .. } => {
972+
match self.ecx.machine.can_const_prop[place.local] {
973+
ConstPropMode::FullConstProp | ConstPropMode::OnlyInsideOwnBlock => {
974+
if self.use_ecx(|this| this.ecx.statement(statement)).is_some() {
975+
trace!("propped discriminant into {:?}", place);
992976
} else {
993-
LocalValue::Dead
994-
};
977+
Self::remove_const(&mut self.ecx, place.local);
978+
}
979+
}
980+
ConstPropMode::OnlyPropagateInto | ConstPropMode::NoPropagation => {
981+
Self::remove_const(&mut self.ecx, place.local);
982+
}
995983
}
996-
_ => {}
997984
}
985+
StatementKind::StorageLive(local) | StatementKind::StorageDead(local) => {
986+
let frame = self.ecx.frame_mut();
987+
frame.locals[local].value = if let StatementKind::StorageLive(_) = statement.kind {
988+
LocalValue::Live(interpret::Operand::Immediate(interpret::Immediate::Uninit))
989+
} else {
990+
LocalValue::Dead
991+
};
992+
}
993+
_ => {}
998994
}
999995

1000996
self.super_statement(statement, location);

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