| use rustc_target::abi::call::FnType; |
| |
| use crate::callee; |
| use crate::traits::*; |
| |
| use rustc::ty::{self, Ty, Instance}; |
| |
| #[derive(Copy, Clone, Debug)] |
| pub struct VirtualIndex(u64); |
| |
| pub const DESTRUCTOR: VirtualIndex = VirtualIndex(0); |
| pub const SIZE: VirtualIndex = VirtualIndex(1); |
| pub const ALIGN: VirtualIndex = VirtualIndex(2); |
| |
| impl<'a, 'tcx> VirtualIndex { |
| pub fn from_index(index: usize) -> Self { |
| VirtualIndex(index as u64 + 3) |
| } |
| |
| pub fn get_fn<Bx: BuilderMethods<'a, 'tcx>>( |
| self, |
| bx: &mut Bx, |
| llvtable: Bx::Value, |
| fn_ty: &FnType<'tcx, Ty<'tcx>> |
| ) -> Bx::Value { |
| // Load the data pointer from the object. |
| debug!("get_fn({:?}, {:?})", llvtable, self); |
| |
| let llvtable = bx.pointercast( |
| llvtable, |
| bx.type_ptr_to(bx.fn_ptr_backend_type(fn_ty)) |
| ); |
| let ptr_align = bx.tcx().data_layout.pointer_align.abi; |
| let gep = bx.inbounds_gep(llvtable, &[bx.const_usize(self.0)]); |
| let ptr = bx.load(gep, ptr_align); |
| bx.nonnull_metadata(ptr); |
| // Vtable loads are invariant |
| bx.set_invariant_load(ptr); |
| ptr |
| } |
| |
| pub fn get_usize<Bx: BuilderMethods<'a, 'tcx>>( |
| self, |
| bx: &mut Bx, |
| llvtable: Bx::Value |
| ) -> Bx::Value { |
| // Load the data pointer from the object. |
| debug!("get_int({:?}, {:?})", llvtable, self); |
| |
| let llvtable = bx.pointercast(llvtable, bx.type_ptr_to(bx.type_isize())); |
| let usize_align = bx.tcx().data_layout.pointer_align.abi; |
| let gep = bx.inbounds_gep(llvtable, &[bx.const_usize(self.0)]); |
| let ptr = bx.load(gep, usize_align); |
| // Vtable loads are invariant |
| bx.set_invariant_load(ptr); |
| ptr |
| } |
| } |
| |
| /// Creates a dynamic vtable for the given type and vtable origin. |
| /// This is used only for objects. |
| /// |
| /// The vtables are cached instead of created on every call. |
| /// |
| /// The `trait_ref` encodes the erased self type. Hence if we are |
| /// making an object `Foo<dyn Trait>` from a value of type `Foo<T>`, then |
| /// `trait_ref` would map `T:Trait`. |
| pub fn get_vtable<'tcx, Cx: CodegenMethods<'tcx>>( |
| cx: &Cx, |
| ty: Ty<'tcx>, |
| trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>, |
| ) -> Cx::Value { |
| let tcx = cx.tcx(); |
| |
| debug!("get_vtable(ty={:?}, trait_ref={:?})", ty, trait_ref); |
| |
| // Check the cache. |
| if let Some(&val) = cx.vtables().borrow().get(&(ty, trait_ref)) { |
| return val; |
| } |
| |
| // Not in the cache. Build it. |
| let nullptr = cx.const_null(cx.type_i8p()); |
| |
| let methods_root; |
| let methods = if let Some(trait_ref) = trait_ref { |
| methods_root = tcx.vtable_methods(trait_ref.with_self_ty(tcx, ty)); |
| methods_root.iter() |
| } else { |
| (&[]).iter() |
| }; |
| |
| let methods = methods.cloned().map(|opt_mth| { |
| opt_mth.map_or(nullptr, |(def_id, substs)| { |
| callee::resolve_and_get_fn_for_vtable(cx, def_id, substs) |
| }) |
| }); |
| |
| let layout = cx.layout_of(ty); |
| // ///////////////////////////////////////////////////////////////////////////////////////////// |
| // If you touch this code, be sure to also make the corresponding changes to |
| // `get_vtable` in rust_mir/interpret/traits.rs |
| // ///////////////////////////////////////////////////////////////////////////////////////////// |
| let components: Vec<_> = [ |
| cx.get_fn(Instance::resolve_drop_in_place(cx.tcx(), ty)), |
| cx.const_usize(layout.size.bytes()), |
| cx.const_usize(layout.align.abi.bytes()) |
| ].iter().cloned().chain(methods).collect(); |
| |
| let vtable_const = cx.const_struct(&components, false); |
| let align = cx.data_layout().pointer_align.abi; |
| let vtable = cx.static_addr_of(vtable_const, align, Some("vtable")); |
| |
| cx.create_vtable_metadata(ty, vtable); |
| |
| cx.vtables().borrow_mut().insert((ty, trait_ref), vtable); |
| vtable |
| } |