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Less cloning in early otherwise branch #77472

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simonvandel wants to merge 8 commits into from
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Less cloning in early otherwise branch #77472

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e7811f9
Do not clone vec and bail early
simonvandel Oct 2, 2020
7a8c277
less clone
simonvandel Oct 2, 2020
62b6896
Remove duplicated check
simonvandel Oct 2, 2020
4784a5c
reorder checks from (intuitively) cheapest to most expensive
simonvandel Oct 2, 2020
586ba9d
Restructure data such that data about the first switch is not duplicated
simonvandel Oct 2, 2020
b4e144e
Move helper creation out of loop
simonvandel Oct 3, 2020
bd56b11
Use SwitchTargets instead of storing in Vec
simonvandel Oct 14, 2020
1a8d28a
Use otherwise from switchTargets
simonvandel Oct 14, 2020
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16 changes: 6 additions & 10 deletions compiler/rustc_mir/src/transform/early_otherwise_branch.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -212,17 +212,14 @@ impl<'a, 'tcx> Helper<'a, 'tcx> {
let discr = self.find_switch_discriminant_info(bb, switch)?;

// go through each target, finding a discriminant read, and a switch
let results = discr.targets_with_values.iter().map(|(value, target)| {
self.find_discriminant_switch_pairing(&discr, target.clone(), value.clone())
});

// if the optimization did not apply for one of the targets, then abort
if results.clone().any(|x| x.is_none()) || results.len() == 0 {
trace!("NO: not all of the targets matched the pattern for optimization");
return None;
let mut results = vec![];

for (value, target) in discr.targets_with_values.iter() {
let info = self.find_discriminant_switch_pairing(&discr, *target, *value)?;
results.push(info);
}

Some(results.flatten().collect())
Some(results)
}

fn find_discriminant_switch_pairing(
Expand Down Expand Up @@ -302,7 +299,6 @@ impl<'a, 'tcx> Helper<'a, 'tcx> {
// the declaration of the discriminant read. Place of this read is being used in the switch
let discr_decl = &self.body.local_decls()[discr_local];
let discr_ty = discr_decl.ty;
// the otherwise target lies as the last element
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@jyn514 jyn514 Oct 30, 2020

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I don't think you meant to remove this comment.

let otherwise_bb = targets.otherwise();
let targets_with_values = targets.iter().collect();

Expand Down