bjoernager/rust
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Transform large arrays into Repeat expressions when possible.

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This commit is contained in:
Camille GILLOT 2023-09-23 16:23:37 +00:00
parent 80a5e8522d
commit dbf9ea30dd
4 changed files with 151 additions and 1 deletions
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14
compiler/rustc_mir_transform/src/gvn.rs
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@ -795,6 +795,20 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
.collect();
let fields = fields?;
if let AggregateTy::Array = ty && fields.len() > 4 {
let first = fields[0];
if fields.iter().all(|&v| v == first) {
let len = ty::Const::from_target_usize(self.tcx, fields.len().try_into().unwrap());
if let Some(const_) = self.try_as_constant(first) {
*rvalue = Rvalue::Repeat(Operand::Constant(Box::new(const_)), len);
} else if let Some(local) = self.try_as_local(first, location) {
*rvalue = Rvalue::Repeat(Operand::Copy(local.into()), len);
self.reused_locals.insert(local);
}
return Some(Value::Repeat(first, len));
}
}
let value = Value::Aggregate(ty, variant_index, fields);
Some(value)
}