bjoernager/rust
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Remove opt_clone_from_or_clone.

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Switches to the idiom used elsewhere of calling `Analysis::bottom_value`
to initialize a `state` value outside a loop, and then using
`clone_from` to update it within the loop. This is simpler and has no
impact on performance.
This commit is contained in:
Nicholas Nethercote 2024-12-06 15:47:03 +11:00
parent c8c50f4351
commit 83f3d204cf
1 changed files with 13 additions and 30 deletions
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43
compiler/rustc_mir_dataflow/src/framework/direction.rs
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@ -118,11 +118,11 @@ impl Direction for Backward {
let targets =
values.iter().map(|&value| SwitchIntTarget { value, target: block });
let mut tmp = None;
let mut tmp = analysis.bottom_value(body);
for target in targets {
let tmp = opt_clone_from_or_clone(&mut tmp, exit_state);
analysis.apply_switch_int_edge_effect(&mut data, tmp, target);
propagate(pred, tmp);
tmp.clone_from(&exit_state);
analysis.apply_switch_int_edge_effect(&mut data, &mut tmp, target);
propagate(pred, &tmp);
}
} else {
propagate(pred, exit_state)
@ -251,7 +251,7 @@ impl Direction for Forward {
fn apply_effects_in_block<'mir, 'tcx, A>(
analysis: &mut A,
_body: &mir::Body<'tcx>,
body: &mir::Body<'tcx>,
state: &mut A::Domain,
block: BasicBlock,
block_data: &'mir mir::BasicBlockData<'tcx>,
@ -292,14 +292,15 @@ impl Direction for Forward {
}
TerminatorEdges::SwitchInt { targets, discr } => {
if let Some(mut data) = analysis.get_switch_int_data(block, discr) {
let mut tmp = None;
let mut tmp = analysis.bottom_value(body);
for (value, target) in targets.iter() {
let tmp = opt_clone_from_or_clone(&mut tmp, exit_state);
analysis.apply_switch_int_edge_effect(&mut data, tmp, SwitchIntTarget {
value: Some(value),
target,
});
propagate(target, tmp);
tmp.clone_from(&exit_state);
analysis.apply_switch_int_edge_effect(
&mut data,
&mut tmp,
SwitchIntTarget { value: Some(value), target },
);
propagate(target, &tmp);
}
// Once we get to the final, "otherwise" branch, there is no need to preserve
@ -425,21 +426,3 @@ impl Direction for Forward {
vis.visit_block_end(state);
}
}
/// An analogue of `Option::get_or_insert_with` that stores a clone of `val` into `opt`, but uses
/// the more efficient `clone_from` if `opt` was `Some`.
///
/// Returns a mutable reference to the new clone that resides in `opt`.
//
// FIXME: Figure out how to express this using `Option::clone_from`, or maybe lift it into the
// standard library?
fn opt_clone_from_or_clone<'a, T: Clone>(opt: &'a mut Option<T>, val: &T) -> &'a mut T {
if opt.is_some() {
let ret = opt.as_mut().unwrap();
ret.clone_from(val);
ret
} else {
*opt = Some(val.clone());
opt.as_mut().unwrap()
}
}