diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/librustc/mir/interpret/mod.rs | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/src/librustc/mir/interpret/mod.rs b/src/librustc/mir/interpret/mod.rs index 35719e49723..49cbc90eb10 100644 --- a/src/librustc/mir/interpret/mod.rs +++ b/src/librustc/mir/interpret/mod.rs @@ -305,7 +305,7 @@ pub struct AllocMap<'tcx> { /// Lets you know what an AllocId refers to id_to_type: FxHashMap<AllocId, AllocType<'tcx>>, - /// Used to ensure that functions and statics only get one associated AllocId + /// Used to ensure that statics only get one associated AllocId type_interner: FxHashMap<AllocType<'tcx>, AllocId>, /// The AllocId to assign to the next requested id. @@ -347,11 +347,14 @@ impl<'tcx> AllocMap<'tcx> { id } - // FIXME: Check if functions have identity. If not, we should not intern these, - // but instead create a new id per use. - // Alternatively we could just make comparing function pointers an error. + /// Functions cannot be identified by pointers, as asm-equal functions can get deduplicated + /// by the linker and functions can be duplicated across crates. + /// We thus generate a new `AllocId` for every mention of a function. This means that + /// `main as fn() == main as fn()` is false, while `let x = main as fn(); x == x` is true. pub fn create_fn_alloc(&mut self, instance: Instance<'tcx>) -> AllocId { - self.intern(AllocType::Function(instance)) + let id = self.reserve(); + self.id_to_type.insert(id, AllocType::Function(instance)); + id } pub fn get(&self, id: AllocId) -> Option<AllocType<'tcx>> { |