diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src/gvn.rs')
| -rw-r--r-- | compiler/rustc_mir_transform/src/gvn.rs | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/compiler/rustc_mir_transform/src/gvn.rs b/compiler/rustc_mir_transform/src/gvn.rs index f8b3e5c6f87..fc0a03b1aab 100644 --- a/compiler/rustc_mir_transform/src/gvn.rs +++ b/compiler/rustc_mir_transform/src/gvn.rs @@ -154,19 +154,25 @@ impl<'tcx> crate::MirPass<'tcx> for GVN { } newtype_index! { + /// This represents a `Value` in the symbolic execution. #[debug_format = "_v{}"] struct VnIndex {} } +/// Marker type to forbid hashing and comparing opaque values. +/// This struct should only be constructed by `ValueSet::insert_unique` to ensure we use that +/// method to create non-unifiable values. It will ICE if used in `ValueSet::insert`. #[derive(Copy, Clone, Debug, Eq)] struct VnOpaque; impl PartialEq for VnOpaque { fn eq(&self, _: &VnOpaque) -> bool { + // ICE if we try to compare unique values unreachable!() } } impl Hash for VnOpaque { fn hash<T: Hasher>(&self, _: &mut T) { + // ICE if we try to hash unique values unreachable!() } } @@ -191,6 +197,8 @@ enum Value<'tcx> { // `disambiguator` is `None` iff the constant is deterministic. disambiguator: Option<VnOpaque>, }, + + // Aggregates. /// An aggregate value, either tuple/closure/struct/enum. /// This does not contain unions, as we cannot reason with the value. Aggregate(VariantIdx, Vec<VnIndex>), @@ -252,6 +260,7 @@ impl<'tcx> ValueSet<'tcx> { } /// Insert a `(Value, Ty)` pair without hashing or deduplication. + /// This always creates a new `VnIndex`. #[inline] fn insert_unique( &mut self, |