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cjgillotcjgillot
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Extract process_assign.
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‎compiler/rustc_mir_transform/src/jump_threading.rs‎

Lines changed: 79 additions & 89 deletions
Original file line numberDiff line numberDiff line change
@@ -422,6 +422,84 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
422422
None
423423
}
424424

425+
#[instrument(level = "trace", skip(self))]
426+
fn process_assign(
427+
&mut self,
428+
bb: BasicBlock,
429+
lhs_place: &Place<'tcx>,
430+
rhs: &Rvalue<'tcx>,
431+
state: &mut State<ConditionSet<'a>>,
432+
) -> Option<!> {
433+
let lhs = self.map.find(lhs_place.as_ref())?;
434+
match rhs {
435+
Rvalue::Use(operand) => self.process_operand(bb, lhs, operand, state)?,
436+
// Transfer the conditions on the copy rhs.
437+
Rvalue::CopyForDeref(rhs) => {
438+
self.process_operand(bb, lhs, &Operand::Copy(*rhs), state)?
439+
}
440+
Rvalue::Discriminant(rhs) => {
441+
let rhs = self.map.find_discr(rhs.as_ref())?;
442+
state.insert_place_idx(rhs, lhs, self.map);
443+
}
444+
// If we expect `lhs ?= A`, we have an opportunity if we assume `constant == A`.
445+
Rvalue::Aggregate(box ref kind, ref operands) => {
446+
let agg_ty = lhs_place.ty(self.body, self.tcx).ty;
447+
let lhs = match kind {
448+
// Do not support unions.
449+
AggregateKind::Adt(.., Some(_)) => return None,
450+
AggregateKind::Adt(_, variant_index, ..) if agg_ty.is_enum() => {
451+
if let Some(discr_target) = self.map.apply(lhs, TrackElem::Discriminant)
452+
&& let Ok(discr_value) =
453+
self.ecx.discriminant_for_variant(agg_ty, *variant_index)
454+
{
455+
self.process_immediate(bb, discr_target, discr_value, state);
456+
}
457+
self.map.apply(lhs, TrackElem::Variant(*variant_index))?
458+
}
459+
_ => lhs,
460+
};
461+
for (field_index, operand) in operands.iter_enumerated() {
462+
if let Some(field) = self.map.apply(lhs, TrackElem::Field(field_index)) {
463+
self.process_operand(bb, field, operand, state);
464+
}
465+
}
466+
}
467+
// Transfer the conditions on the copy rhs, after inversing polarity.
468+
Rvalue::UnaryOp(UnOp::Not, Operand::Move(place) | Operand::Copy(place)) => {
469+
let conditions = state.try_get_idx(lhs, self.map)?;
470+
let place = self.map.find(place.as_ref())?;
471+
let conds = conditions.map(self.arena, Condition::inv);
472+
state.insert_value_idx(place, conds, self.map);
473+
}
474+
// We expect `lhs ?= A`. We found `lhs = Eq(rhs, B)`.
475+
// Create a condition on `rhs ?= B`.
476+
Rvalue::BinaryOp(
477+
op,
478+
box (Operand::Move(place) | Operand::Copy(place), Operand::Constant(value))
479+
| box (Operand::Constant(value), Operand::Move(place) | Operand::Copy(place)),
480+
) => {
481+
let conditions = state.try_get_idx(lhs, self.map)?;
482+
let place = self.map.find(place.as_ref())?;
483+
let equals = match op {
484+
BinOp::Eq => ScalarInt::TRUE,
485+
BinOp::Ne => ScalarInt::FALSE,
486+
_ => return None,
487+
};
488+
let value = value.const_.normalize(self.tcx, self.param_env).try_to_scalar_int()?;
489+
let conds = conditions.map(self.arena, |c| Condition {
490+
value,
491+
polarity: if c.matches(equals) { Polarity::Eq } else { Polarity::Ne },
492+
..c
493+
});
494+
state.insert_value_idx(place, conds, self.map);
495+
}
496+
497+
_ => {}
498+
}
499+
500+
None
501+
}
502+
425503
#[instrument(level = "trace", skip(self))]
426504
fn process_statement(
427505
&mut self,
@@ -454,95 +532,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
454532
conditions.iter_matches(ScalarInt::TRUE).for_each(register_opportunity);
455533
}
456534
StatementKind::Assign(box (lhs_place, rhs)) => {
457-
if let Some(lhs) = self.map.find(lhs_place.as_ref()) {
458-
match rhs {
459-
Rvalue::Use(operand) => self.process_operand(bb, lhs, operand, state)?,
460-
// Transfer the conditions on the copy rhs.
461-
Rvalue::CopyForDeref(rhs) => {
462-
self.process_operand(bb, lhs, &Operand::Copy(*rhs), state)?
463-
}
464-
Rvalue::Discriminant(rhs) => {
465-
let rhs = self.map.find_discr(rhs.as_ref())?;
466-
state.insert_place_idx(rhs, lhs, self.map);
467-
}
468-
// If we expect `lhs ?= A`, we have an opportunity if we assume `constant == A`.
469-
Rvalue::Aggregate(box ref kind, ref operands) => {
470-
let agg_ty = lhs_place.ty(self.body, self.tcx).ty;
471-
let lhs = match kind {
472-
// Do not support unions.
473-
AggregateKind::Adt(.., Some(_)) => return None,
474-
AggregateKind::Adt(_, variant_index, ..) if agg_ty.is_enum() => {
475-
if let Some(discr_target) =
476-
self.map.apply(lhs, TrackElem::Discriminant)
477-
&& let Ok(discr_value) = self
478-
.ecx
479-
.discriminant_for_variant(agg_ty, *variant_index)
480-
{
481-
self.process_immediate(
482-
bb,
483-
discr_target,
484-
discr_value,
485-
state,
486-
);
487-
}
488-
self.map.apply(lhs, TrackElem::Variant(*variant_index))?
489-
}
490-
_ => lhs,
491-
};
492-
for (field_index, operand) in operands.iter_enumerated() {
493-
if let Some(field) =
494-
self.map.apply(lhs, TrackElem::Field(field_index))
495-
{
496-
self.process_operand(bb, field, operand, state);
497-
}
498-
}
499-
}
500-
// Transfer the conditions on the copy rhs, after inversing polarity.
501-
Rvalue::UnaryOp(UnOp::Not, Operand::Move(place) | Operand::Copy(place)) => {
502-
let conditions = state.try_get_idx(lhs, self.map)?;
503-
let place = self.map.find(place.as_ref())?;
504-
let conds = conditions.map(self.arena, Condition::inv);
505-
state.insert_value_idx(place, conds, self.map);
506-
}
507-
// We expect `lhs ?= A`. We found `lhs = Eq(rhs, B)`.
508-
// Create a condition on `rhs ?= B`.
509-
Rvalue::BinaryOp(
510-
op,
511-
box (
512-
Operand::Move(place) | Operand::Copy(place),
513-
Operand::Constant(value),
514-
)
515-
| box (
516-
Operand::Constant(value),
517-
Operand::Move(place) | Operand::Copy(place),
518-
),
519-
) => {
520-
let conditions = state.try_get_idx(lhs, self.map)?;
521-
let place = self.map.find(place.as_ref())?;
522-
let equals = match op {
523-
BinOp::Eq => ScalarInt::TRUE,
524-
BinOp::Ne => ScalarInt::FALSE,
525-
_ => return None,
526-
};
527-
let value = value
528-
.const_
529-
.normalize(self.tcx, self.param_env)
530-
.try_to_scalar_int()?;
531-
let conds = conditions.map(self.arena, |c| Condition {
532-
value,
533-
polarity: if c.matches(equals) {
534-
Polarity::Eq
535-
} else {
536-
Polarity::Ne
537-
},
538-
..c
539-
});
540-
state.insert_value_idx(place, conds, self.map);
541-
}
542-
543-
_ => {}
544-
}
545-
}
535+
self.process_assign(bb, lhs_place, rhs, state)?;
546536
}
547537
_ => {}
548538
}

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