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interpret: refactor dyn trait handling

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We can check that the vtable is for the right trait very early, and then just pass the type around.
This commit is contained in:
Ralf Jung
2024-06-10 17:24:36 +02:00
parent 0de24a5177
commit af4d6c74ef
7 changed files with 90 additions and 112 deletions
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19
compiler/rustc_const_eval/src/interpret/memory.rs
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@@ -867,19 +867,28 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
.ok_or_else(|| err_ub!(InvalidFunctionPointer(Pointer::new(alloc_id, offset))).into())
}
pub fn get_ptr_vtable(
/// Get the dynamic type of the given vtable pointer.
/// If `expected_trait` is `Some`, it must be a vtable for the given trait.
pub fn get_ptr_vtable_ty(
&self,
ptr: Pointer<Option<M::Provenance>>,
) -> InterpResult<'tcx, (Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>)> {
expected_trait: Option<&'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>>,
) -> InterpResult<'tcx, Ty<'tcx>> {
trace!("get_ptr_vtable({:?})", ptr);
let (alloc_id, offset, _tag) = self.ptr_get_alloc_id(ptr)?;
if offset.bytes() != 0 {
throw_ub!(InvalidVTablePointer(Pointer::new(alloc_id, offset)))
}
match self.tcx.try_get_global_alloc(alloc_id) {
Some(GlobalAlloc::VTable(ty, trait_ref)) => Ok((ty, trait_ref)),
_ => throw_ub!(InvalidVTablePointer(Pointer::new(alloc_id, offset))),
let Some(GlobalAlloc::VTable(ty, vtable_trait)) = self.tcx.try_get_global_alloc(alloc_id)
else {
throw_ub!(InvalidVTablePointer(Pointer::new(alloc_id, offset)))
};
if let Some(expected_trait) = expected_trait {
if vtable_trait != expected_trait.principal() {
throw_ub!(InvalidVTableTrait { expected_trait, vtable_trait });
}
}
Ok(ty)
}
pub fn alloc_mark_immutable(&mut self, id: AllocId) -> InterpResult<'tcx> {