reduce rightward drift, add precondition comment
diff --git a/src/librustc_mir/transform/deaggregator.rs b/src/librustc_mir/transform/deaggregator.rs
index ae91123..fccd4a6 100644
--- a/src/librustc_mir/transform/deaggregator.rs
+++ b/src/librustc_mir/transform/deaggregator.rs
@@ -34,6 +34,8 @@
// Do not trigger on constants. Could be revised in future
if let MirSource::Fn(_) = source {} else { return; }
+ // In fact, we might not want to trigger in other cases.
+ // Ex: when we could use SROA. See issue #35259
let mut curr: usize = 0;
for bb in mir.basic_blocks_mut() {
@@ -90,21 +92,24 @@
for i in curr..statements.len() {
let ref statement = statements[i];
let StatementKind::Assign(_, ref rhs) = statement.kind;
- if let &Rvalue::Aggregate(ref kind, ref operands) = rhs {
- if let &AggregateKind::Adt(adt_def, variant, _) = kind {
- if operands.len() > 0 { // don't deaggregate ()
- if adt_def.variants.len() > 1 {
- // only deaggrate structs for now
- continue;
- }
- debug!("getting variant {:?}", variant);
- debug!("for adt_def {:?}", adt_def);
- let variant_def = &adt_def.variants[variant];
- if variant_def.kind == VariantKind::Struct {
- return Some(i);
- }
- }
- }
+ let (kind, operands) = match rhs {
+ &Rvalue::Aggregate(ref kind, ref operands) => (kind, operands),
+ _ => continue,
+ };
+ let (adt_def, variant) = match kind {
+ &AggregateKind::Adt(adt_def, variant, _) => (adt_def, variant),
+ _ => continue,
+ };
+ if operands.len() == 0 || adt_def.variants.len() > 1 {
+ // don't deaggregate ()
+ // don't deaggregate enums ... for now
+ continue;
+ }
+ debug!("getting variant {:?}", variant);
+ debug!("for adt_def {:?}", adt_def);
+ let variant_def = &adt_def.variants[variant];
+ if variant_def.kind == VariantKind::Struct {
+ return Some(i);
}
};
None
