1 //! Codegen vtables and vtable accesses.
3 //! See `rustc_codegen_ssa/src/meth.rs` for reference.
5 use crate::constant::data_id_for_alloc_id;
8 pub(crate) fn vtable_memflags() -> MemFlags {
9 let mut flags = MemFlags::trusted(); // A vtable access is always aligned and will never trap.
10 flags.set_readonly(); // A vtable is always read-only.
14 pub(crate) fn drop_fn_of_obj(fx: &mut FunctionCx<'_, '_, '_>, vtable: Value) -> Value {
15 let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes() as usize;
20 (ty::COMMON_VTABLE_ENTRIES_DROPINPLACE * usize_size) as i32,
24 pub(crate) fn size_of_obj(fx: &mut FunctionCx<'_, '_, '_>, vtable: Value) -> Value {
25 let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes() as usize;
30 (ty::COMMON_VTABLE_ENTRIES_SIZE * usize_size) as i32,
34 pub(crate) fn min_align_of_obj(fx: &mut FunctionCx<'_, '_, '_>, vtable: Value) -> Value {
35 let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes() as usize;
40 (ty::COMMON_VTABLE_ENTRIES_ALIGN * usize_size) as i32,
44 pub(crate) fn get_ptr_and_method_ref<'tcx>(
45 fx: &mut FunctionCx<'_, '_, 'tcx>,
48 ) -> (Pointer, Value) {
49 let (ptr, vtable) = 'block: {
50 if let ty::Ref(_, ty, _) = arg.layout().ty.kind() {
52 let inner_layout = fx.layout_of(arg.layout().ty.builtin_deref(true).unwrap().ty);
53 let dyn_star = CPlace::for_ptr(Pointer::new(arg.load_scalar(fx)), inner_layout);
54 let ptr = dyn_star.place_field(fx, mir::Field::new(0)).to_ptr();
56 dyn_star.place_field(fx, mir::Field::new(1)).to_cvalue(fx).load_scalar(fx);
57 break 'block (ptr, vtable);
61 if let Abi::ScalarPair(_, _) = arg.layout().abi {
62 let (ptr, vtable) = arg.load_scalar_pair(fx);
63 (Pointer::new(ptr), vtable)
65 let (ptr, vtable) = arg.try_to_ptr().unwrap();
66 (ptr, vtable.unwrap())
70 let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes();
71 let func_ref = fx.bcx.ins().load(
75 (idx * usize_size as usize) as i32,
80 pub(crate) fn get_vtable<'tcx>(
81 fx: &mut FunctionCx<'_, '_, 'tcx>,
83 trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
85 let alloc_id = fx.tcx.vtable_allocation((ty, trait_ref));
87 data_id_for_alloc_id(&mut fx.constants_cx, &mut *fx.module, alloc_id, Mutability::Not);
88 let local_data_id = fx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
89 if fx.clif_comments.enabled() {
90 fx.add_comment(local_data_id, format!("vtable: {:?}", alloc_id));
92 fx.bcx.ins().global_value(fx.pointer_type, local_data_id)