bjoernager/rust
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Store a DefId instead of an AdtDef in AggregateKind::Adt

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The `AggregateKind` enum ends up in the final mir `Body`. Currently,
any changes to `AdtDef` (regardless of how significant they are)
will legitimately cause the overall result of `optimized_mir` to change,
invalidating any codegen re-use involving that mir.

This will get worse once we start hashing the `Span` inside `FieldDef`
(which is itself contained in `AdtDef`).

To try to reduce these kinds of invalidations, this commit changes
`AggregateKind::Adt` to store just the `DefId`, instead of the full
`AdtDef`. This allows the result of `optimized_mir` to be unchanged
if the `AdtDef` changes in a way that doesn't actually affect any
of the MIR we build.
This commit is contained in:
Aaron Hill 2021-12-22 14:35:17 -05:00
parent e100ec5bc7
commit cac431ba75
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GPG key ID: B4087E510E98B164
11 changed files with 32 additions and 31 deletions
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4
compiler/rustc_const_eval/src/interpret/step.rs
View file

@ -199,9 +199,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
Aggregate(ref kind, ref operands) => {
// active_field_index is for union initialization.
let (dest, active_field_index) = match **kind {
mir::AggregateKind::Adt(adt_def, variant_index, _, _, active_field_index) => {
mir::AggregateKind::Adt(adt_did, variant_index, _, _, active_field_index) => {
self.write_discriminant(variant_index, &dest)?;
if adt_def.is_enum() {
if self.tcx.adt_def(adt_did).is_enum() {
assert!(active_field_index.is_none());
(self.place_downcast(&dest, variant_index)?, None)
} else {

3
compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
View file

@ -270,7 +270,8 @@ where
Rvalue::Aggregate(kind, operands) => {
// Return early if we know that the struct or enum being constructed is always
// qualified.
if let AggregateKind::Adt(def, _, substs, ..) = **kind {
if let AggregateKind::Adt(adt_did, _, substs, ..) = **kind {
let def = cx.tcx.adt_def(adt_did);
if Q::in_adt_inherently(cx, def, substs) {
return true;
}

3
compiler/rustc_const_eval/src/util/aggregate.rs
View file

@ -22,7 +22,8 @@ pub fn expand_aggregate<'tcx>(
) -> impl Iterator<Item = Statement<'tcx>> + TrustedLen {
let mut set_discriminant = None;
let active_field_index = match kind {
AggregateKind::Adt(adt_def, variant_index, _, _, active_field_index) => {
AggregateKind::Adt(adt_did, variant_index, _, _, active_field_index) => {
let adt_def = tcx.adt_def(adt_did);
if adt_def.is_enum() {
set_discriminant = Some(Statement {
kind: StatementKind::SetDiscriminant { place: Box::new(lhs), variant_index },