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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
@@ -423,6 +423,84 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
423423
None
424424
}
425425

426+
#[instrument(level = "trace", skip(self))]
427+
fn process_assign(
428+
&mut self,
429+
bb: BasicBlock,
430+
lhs_place: &Place<'tcx>,
431+
rhs: &Rvalue<'tcx>,
432+
state: &mut State<ConditionSet<'a>>,
433+
) -> Option<!> {
434+
let lhs = self.map.find(lhs_place.as_ref())?;
435+
match rhs {
436+
Rvalue::Use(operand) => self.process_operand(bb, lhs, operand, state)?,
437+
// Transfer the conditions on the copy rhs.
438+
Rvalue::CopyForDeref(rhs) => {
439+
self.process_operand(bb, lhs, &Operand::Copy(*rhs), state)?
440+
}
441+
Rvalue::Discriminant(rhs) => {
442+
let rhs = self.map.find_discr(rhs.as_ref())?;
443+
state.insert_place_idx(rhs, lhs, self.map);
444+
}
445+
// If we expect `lhs ?= A`, we have an opportunity if we assume `constant == A`.
446+
Rvalue::Aggregate(box ref kind, ref operands) => {
447+
let agg_ty = lhs_place.ty(self.body, self.tcx).ty;
448+
let lhs = match kind {
449+
// Do not support unions.
450+
AggregateKind::Adt(.., Some(_)) => return None,
451+
AggregateKind::Adt(_, variant_index, ..) if agg_ty.is_enum() => {
452+
if let Some(discr_target) = self.map.apply(lhs, TrackElem::Discriminant)
453+
&& let Ok(discr_value) =
454+
self.ecx.discriminant_for_variant(agg_ty, *variant_index)
455+
{
456+
self.process_immediate(bb, discr_target, discr_value, state);
457+
}
458+
self.map.apply(lhs, TrackElem::Variant(*variant_index))?
459+
}
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_ => lhs,
461+
};
462+
for (field_index, operand) in operands.iter_enumerated() {
463+
if let Some(field) = self.map.apply(lhs, TrackElem::Field(field_index)) {
464+
self.process_operand(bb, field, operand, state);
465+
}
466+
}
467+
}
468+
// Transfer the conditions on the copy rhs, after inversing polarity.
469+
Rvalue::UnaryOp(UnOp::Not, Operand::Move(place) | Operand::Copy(place)) => {
470+
let conditions = state.try_get_idx(lhs, self.map)?;
471+
let place = self.map.find(place.as_ref())?;
472+
let conds = conditions.map(self.arena, Condition::inv);
473+
state.insert_value_idx(place, conds, self.map);
474+
}
475+
// We expect `lhs ?= A`. We found `lhs = Eq(rhs, B)`.
476+
// Create a condition on `rhs ?= B`.
477+
Rvalue::BinaryOp(
478+
op,
479+
box (Operand::Move(place) | Operand::Copy(place), Operand::Constant(value))
480+
| box (Operand::Constant(value), Operand::Move(place) | Operand::Copy(place)),
481+
) => {
482+
let conditions = state.try_get_idx(lhs, self.map)?;
483+
let place = self.map.find(place.as_ref())?;
484+
let equals = match op {
485+
BinOp::Eq => ScalarInt::TRUE,
486+
BinOp::Ne => ScalarInt::FALSE,
487+
_ => return None,
488+
};
489+
let value = value.const_.normalize(self.tcx, self.param_env).try_to_scalar_int()?;
490+
let conds = conditions.map(self.arena, |c| Condition {
491+
value,
492+
polarity: if c.matches(equals) { Polarity::Eq } else { Polarity::Ne },
493+
..c
494+
});
495+
state.insert_value_idx(place, conds, self.map);
496+
}
497+
498+
_ => {}
499+
}
500+
501+
None
502+
}
503+
426504
#[instrument(level = "trace", skip(self))]
427505
fn process_statement(
428506
&mut self,
@@ -472,95 +550,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
472550
conditions.iter_matches(ScalarInt::TRUE).for_each(register_opportunity);
473551
}
474552
StatementKind::Assign(box (lhs_place, rhs)) => {
475-
if let Some(lhs) = self.map.find(lhs_place.as_ref()) {
476-
match rhs {
477-
Rvalue::Use(operand) => self.process_operand(bb, lhs, operand, state)?,
478-
// Transfer the conditions on the copy rhs.
479-
Rvalue::CopyForDeref(rhs) => {
480-
self.process_operand(bb, lhs, &Operand::Copy(*rhs), state)?
481-
}
482-
Rvalue::Discriminant(rhs) => {
483-
let rhs = self.map.find_discr(rhs.as_ref())?;
484-
state.insert_place_idx(rhs, lhs, self.map);
485-
}
486-
// If we expect `lhs ?= A`, we have an opportunity if we assume `constant == A`.
487-
Rvalue::Aggregate(box ref kind, ref operands) => {
488-
let agg_ty = lhs_place.ty(self.body, self.tcx).ty;
489-
let lhs = match kind {
490-
// Do not support unions.
491-
AggregateKind::Adt(.., Some(_)) => return None,
492-
AggregateKind::Adt(_, variant_index, ..) if agg_ty.is_enum() => {
493-
if let Some(discr_target) =
494-
self.map.apply(lhs, TrackElem::Discriminant)
495-
&& let Ok(discr_value) = self
496-
.ecx
497-
.discriminant_for_variant(agg_ty, *variant_index)
498-
{
499-
self.process_immediate(
500-
bb,
501-
discr_target,
502-
discr_value,
503-
state,
504-
);
505-
}
506-
self.map.apply(lhs, TrackElem::Variant(*variant_index))?
507-
}
508-
_ => lhs,
509-
};
510-
for (field_index, operand) in operands.iter_enumerated() {
511-
if let Some(field) =
512-
self.map.apply(lhs, TrackElem::Field(field_index))
513-
{
514-
self.process_operand(bb, field, operand, state);
515-
}
516-
}
517-
}
518-
// Transfer the conditions on the copy rhs, after inversing polarity.
519-
Rvalue::UnaryOp(UnOp::Not, Operand::Move(place) | Operand::Copy(place)) => {
520-
let conditions = state.try_get_idx(lhs, self.map)?;
521-
let place = self.map.find(place.as_ref())?;
522-
let conds = conditions.map(self.arena, Condition::inv);
523-
state.insert_value_idx(place, conds, self.map);
524-
}
525-
// We expect `lhs ?= A`. We found `lhs = Eq(rhs, B)`.
526-
// Create a condition on `rhs ?= B`.
527-
Rvalue::BinaryOp(
528-
op,
529-
box (
530-
Operand::Move(place) | Operand::Copy(place),
531-
Operand::Constant(value),
532-
)
533-
| box (
534-
Operand::Constant(value),
535-
Operand::Move(place) | Operand::Copy(place),
536-
),
537-
) => {
538-
let conditions = state.try_get_idx(lhs, self.map)?;
539-
let place = self.map.find(place.as_ref())?;
540-
let equals = match op {
541-
BinOp::Eq => ScalarInt::TRUE,
542-
BinOp::Ne => ScalarInt::FALSE,
543-
_ => return None,
544-
};
545-
let value = value
546-
.const_
547-
.normalize(self.tcx, self.param_env)
548-
.try_to_scalar_int()?;
549-
let conds = conditions.map(self.arena, |c| Condition {
550-
value,
551-
polarity: if c.matches(equals) {
552-
Polarity::Eq
553-
} else {
554-
Polarity::Ne
555-
},
556-
..c
557-
});
558-
state.insert_value_idx(place, conds, self.map);
559-
}
560-
561-
_ => {}
562-
}
563-
}
553+
self.process_assign(bb, lhs_place, rhs, state)?;
564554
}
565555
_ => {}
566556
}

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