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mir/pretty: use Option instead of Either<Once, Empty>

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`Either` is wasteful for a one-or-none iterator, especially since `Once`
is already an `option::IntoIter` internally. We don't really need any of
the iterator mechanisms in this case, just a single conditional insert.
This commit is contained in:
Josh Stone 2024-08-16 12:42:02 -07:00
parent a73bc4a131
commit 29017e45a1
1 changed files with 9 additions and 9 deletions
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18
compiler/rustc_middle/src/mir/pretty.rs
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@ -1418,21 +1418,19 @@ pub fn write_allocations<'tcx>(
alloc.inner().provenance().ptrs().values().map(|p| p.alloc_id())
}
fn alloc_ids_from_const_val(val: ConstValue<'_>) -> impl Iterator<Item = AllocId> + '_ {
fn alloc_id_from_const_val(val: ConstValue<'_>) -> Option<AllocId> {
match val {
ConstValue::Scalar(interpret::Scalar::Ptr(ptr, _)) => {
Either::Left(std::iter::once(ptr.provenance.alloc_id()))
}
ConstValue::Scalar(interpret::Scalar::Int { .. }) => Either::Right(std::iter::empty()),
ConstValue::ZeroSized => Either::Right(std::iter::empty()),
ConstValue::Scalar(interpret::Scalar::Ptr(ptr, _)) => Some(ptr.provenance.alloc_id()),
ConstValue::Scalar(interpret::Scalar::Int { .. }) => None,
ConstValue::ZeroSized => None,
ConstValue::Slice { .. } => {
// `u8`/`str` slices, shouldn't contain pointers that we want to print.
Either::Right(std::iter::empty())
None
}
ConstValue::Indirect { alloc_id, .. } => {
// FIXME: we don't actually want to print all of these, since some are printed nicely directly as values inline in MIR.
// Really we'd want `pretty_print_const_value` to decide which allocations to print, instead of having a separate visitor.
Either::Left(std::iter::once(alloc_id))
Some(alloc_id)
}
}
}
@ -1443,7 +1441,9 @@ pub fn write_allocations<'tcx>(
match c.const_ {
Const::Ty(_, _) | Const::Unevaluated(..) => {}
Const::Val(val, _) => {
self.0.extend(alloc_ids_from_const_val(val));
if let Some(id) = alloc_id_from_const_val(val) {
self.0.insert(id);
}
}
}
}