diff options
| -rw-r--r-- | src/librustc/mir/interpret/mod.rs | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/src/librustc/mir/interpret/mod.rs b/src/librustc/mir/interpret/mod.rs index 49cbc90eb10..783bb6f521e 100644 --- a/src/librustc/mir/interpret/mod.rs +++ b/src/librustc/mir/interpret/mod.rs @@ -322,8 +322,11 @@ impl<'tcx> AllocMap<'tcx> { } } - /// obtains a new allocation ID that can be referenced but does not + /// Obtains a new allocation ID that can be referenced but does not /// yet have an allocation backing it. + /// + /// Make sure to call `set_id_memory` or `set_id_same_memory` before returning such an + /// `AllocId` from a query. pub fn reserve( &mut self, ) -> AllocId { @@ -357,10 +360,14 @@ impl<'tcx> AllocMap<'tcx> { id } + /// Returns `None` in case the `AllocId` is dangling. + /// This function exists to allow const eval to detect the difference between evaluation- + /// local dangling pointers and allocations in constants/statics. pub fn get(&self, id: AllocId) -> Option<AllocType<'tcx>> { self.id_to_type.get(&id).cloned() } + /// Panics if the `AllocId` does not refer to an `Allocation` pub fn unwrap_memory(&self, id: AllocId) -> &'tcx Allocation { match self.get(id) { Some(AllocType::Memory(mem)) => mem, @@ -368,24 +375,35 @@ impl<'tcx> AllocMap<'tcx> { } } + /// Generate an `AllocId` for a static or return a cached one in case this function has been + /// called on the same static before. pub fn intern_static(&mut self, static_id: DefId) -> AllocId { self.intern(AllocType::Static(static_id)) } + /// Intern the `Allocation` and return a new `AllocId`, even if there's already an identical + /// `Allocation` with a different `AllocId`. + // FIXME: is this really necessary? Can we ensure `FOO` and `BAR` being different after codegen + // in `static FOO: u32 = 42; static BAR: u32 = 42;` even if they reuse the same allocation + // inside rustc? pub fn allocate(&mut self, mem: &'tcx Allocation) -> AllocId { let id = self.reserve(); self.set_id_memory(id, mem); id } + /// Freeze an `AllocId` created with `reserve` by pointing it at an `Allocation`. Trying to + /// call this function twice, even with the same `Allocation` will ICE the compiler. pub fn set_id_memory(&mut self, id: AllocId, mem: &'tcx Allocation) { if let Some(old) = self.id_to_type.insert(id, AllocType::Memory(mem)) { bug!("tried to set allocation id {}, but it was already existing as {:#?}", id, old); } } + /// Freeze an `AllocId` created with `reserve` by pointing it at an `Allocation`. May be called + /// twice for the same `(AllocId, Allocation)` pair. pub fn set_id_same_memory(&mut self, id: AllocId, mem: &'tcx Allocation) { - self.id_to_type.insert_same(id, AllocType::Memory(mem)); + self.id_to_type.insert_same(id, AllocType::Memory(mem)); } } |