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Make polarity an enum.

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This commit is contained in:
Camille GILLOT 2023-10-17 18:40:06 +00:00
parent b5aa1ef9b4
commit 47056248e5
1 changed files with 23 additions and 11 deletions
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34
compiler/rustc_mir_transform/src/jump_threading.rs
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@ -11,9 +11,9 @@
//! looking for assignments that will turn the `SwitchInt` into a simple `Goto`.
//!
//! The algorithm maintains a set of replacement conditions:
//! - `conditions[place]` contains `Condition { value, polarity: true, target }`
//! - `conditions[place]` contains `Condition { value, polarity: Eq, target }`
//! if assigning `value` to `place` turns the `SwitchInt` into `Goto { target }`.
//! - `conditions[place]` contains `Condition { value, polarity: false, target }`
//! - `conditions[place]` contains `Condition { value, polarity: Ne, target }`
//! if assigning anything different from `value` to `place` turns the `SwitchInt`
//! into `Goto { target }`.
//!
@ -98,13 +98,13 @@ impl<'tcx> MirPass<'tcx> for JumpThreading {
continue;
};
arena.alloc_from_iter([
Condition { value, polarity: true, target: then },
Condition { value, polarity: false, target: else_ },
Condition { value, polarity: Polarity::Eq, target: then },
Condition { value, polarity: Polarity::Ne, target: else_ },
])
} else {
arena.alloc_from_iter(targets.iter().filter_map(|(value, target)| {
let value = ScalarInt::try_from_uint(value, discr_layout.size)?;
Some(Condition { value, polarity: true, target })
Some(Condition { value, polarity: Polarity::Eq, target })
}))
};
let conds = ConditionSet(conds);
@ -149,18 +149,26 @@ struct TOFinder<'tcx, 'a> {
#[derive(Copy, Clone, Debug)]
struct Condition {
value: ScalarInt,
/// `true` means `==`, `false` means `!=`
polarity: bool,
polarity: Polarity,
target: BasicBlock,
}
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
enum Polarity {
Ne,
Eq,
}
impl Condition {
fn matches(&self, value: ScalarInt) -> bool {
(self.value == value) == self.polarity
(self.value == value) == (self.polarity == Polarity::Eq)
}
fn inv(mut self) -> Self {
self.polarity = !self.polarity;
self.polarity = match self.polarity {
Polarity::Eq => Polarity::Ne,
Polarity::Ne => Polarity::Eq,
};
self
}
}
@ -455,7 +463,11 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
.try_to_scalar_int()?;
let conds = conditions.map(self.arena, |c| Condition {
value,
polarity: c.matches(equals),
polarity: if c.matches(equals) {
Polarity::Eq
} else {
Polarity::Ne
},
..c
});
state.insert_value_idx(place, conds, self.map);
@ -560,7 +572,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
// Likewise, we know that `discr != value`. That's a must weaker information,
// so we can only match the exact same condition.
for c in conditions.iter() {
if c.value == value && c.polarity == false {
if c.value == value && c.polarity == Polarity::Ne {
debug!(?target_bb, ?c.target, "register");
self.opportunities
.push(ThreadingOpportunity { chain: vec![], target: c.target });