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Reduce rightward drift.

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This commit is contained in:
Camille GILLOT 2023-04-15 16:27:55 +00:00
parent dd452ae70e
commit dd78b997b5
1 changed files with 35 additions and 37 deletions
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72
compiler/rustc_mir_transform/src/dataflow_const_prop.rs
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@ -110,48 +110,46 @@ fn handle_assign(
// we must make sure that all `target as Variant#i` are `Top`.
state.flood(target.as_ref(), self.map());
if let Some(target_idx) = self.map().find(target.as_ref()) {
let (variant_target, variant_index) = match **kind {
AggregateKind::Tuple | AggregateKind::Closure(..) => {
(Some(target_idx), None)
}
AggregateKind::Adt(def_id, variant_index, ..) => {
match self.tcx.def_kind(def_id) {
DefKind::Struct => (Some(target_idx), None),
DefKind::Enum => (
self.map.apply(target_idx, TrackElem::Variant(variant_index)),
Some(variant_index),
),
_ => (None, None),
}
}
_ => (None, None),
};
if let Some(variant_target_idx) = variant_target {
for (field_index, operand) in operands.iter().enumerate() {
if let Some(field) = self.map().apply(
variant_target_idx,
TrackElem::Field(FieldIdx::from_usize(field_index)),
) {
let result = self.handle_operand(operand, state);
state.insert_idx(field, result, self.map());
}
let Some(target_idx) = self.map().find(target.as_ref()) else { return };
let (variant_target, variant_index) = match **kind {
AggregateKind::Tuple | AggregateKind::Closure(..) => (Some(target_idx), None),
AggregateKind::Adt(def_id, variant_index, ..) => {
match self.tcx.def_kind(def_id) {
DefKind::Struct => (Some(target_idx), None),
DefKind::Enum => (
self.map.apply(target_idx, TrackElem::Variant(variant_index)),
Some(variant_index),
),
_ => return,
}
}
if let Some(variant_index) = variant_index
&& let Some(discr_idx) = self.map().apply(target_idx, TrackElem::Discriminant)
{
// We are assigning the discriminant as part of an aggregate.
// This discriminant can only alias a variant field's value if the operand
// had an invalid value for that type.
// Using invalid values is UB, so we are allowed to perform the assignment
// without extra flooding.
let enum_ty = target.ty(self.local_decls, self.tcx).ty;
if let Some(discr_val) = self.eval_discriminant(enum_ty, variant_index) {
state.insert_value_idx(discr_idx, FlatSet::Elem(discr_val), &self.map);
_ => return,
};
if let Some(variant_target_idx) = variant_target {
for (field_index, operand) in operands.iter().enumerate() {
if let Some(field) = self.map().apply(
variant_target_idx,
TrackElem::Field(FieldIdx::from_usize(field_index)),
) {
let result = self.handle_operand(operand, state);
state.insert_idx(field, result, self.map());
}
}
}
if let Some(variant_index) = variant_index
&& let Some(discr_idx) = self.map().apply(target_idx, TrackElem::Discriminant)
{
// We are assigning the discriminant as part of an aggregate.
// This discriminant can only alias a variant field's value if the operand
// had an invalid value for that type.
// Using invalid values is UB, so we are allowed to perform the assignment
// without extra flooding.
let enum_ty = target.ty(self.local_decls, self.tcx).ty;
if let Some(discr_val) = self.eval_discriminant(enum_ty, variant_index) {
state.insert_value_idx(discr_idx, FlatSet::Elem(discr_val), &self.map);
}
}
}
Rvalue::CheckedBinaryOp(op, box (left, right)) => {
// Flood everything now, so we can use `insert_value_idx` directly later.