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JumpThreading: Re-enable and fix Not ops on non-booleans

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clubby789 2024-10-04 12:54:09 +00:00
parent 092a284ba0
commit 9f35fe47c7
6 changed files with 120 additions and 27 deletions
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29
compiler/rustc_mir_transform/src/jump_threading.rs
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@ -150,14 +150,6 @@ impl Condition {
fn matches(&self, value: ScalarInt) -> bool {
(self.value == value) == (self.polarity == Polarity::Eq)
}
fn inv(mut self) -> Self {
self.polarity = match self.polarity {
Polarity::Eq => Polarity::Ne,
Polarity::Ne => Polarity::Eq,
};
self
}
}
#[derive(Copy, Clone, Debug)]
@ -495,19 +487,20 @@ impl<'a, 'tcx> TOFinder<'a, 'tcx> {
}
}
}
// Transfer the conditions on the copy rhs, after inversing polarity.
// Transfer the conditions on the copy rhs, after inverting the value of the condition.
Rvalue::UnaryOp(UnOp::Not, Operand::Move(place) | Operand::Copy(place)) => {
if !place.ty(self.body, self.tcx).ty.is_bool() {
// Constructing the conditions by inverting the polarity
// of equality is only correct for bools. That is to say,
// `!a == b` is not `a != b` for integers greater than 1 bit.
return;
}
let layout = self.ecx.layout_of(place.ty(self.body, self.tcx).ty).unwrap();
let Some(conditions) = state.try_get_idx(lhs, &self.map) else { return };
let Some(place) = self.map.find(place.as_ref()) else { return };
// FIXME: I think This could be generalized to not bool if we
// actually perform a logical not on the condition's value.
let conds = conditions.map(self.arena, Condition::inv);
let conds = conditions.map(self.arena, |mut cond| {
cond.value = self
.ecx
.unary_op(UnOp::Not, &ImmTy::from_scalar_int(cond.value, layout))
.unwrap()
.to_scalar_int()
.unwrap();
cond
});
state.insert_value_idx(place, conds, &self.map);
}
// We expect `lhs ?= A`. We found `lhs = Eq(rhs, B)`.