80 lines
2.5 KiB
Rust
80 lines
2.5 KiB
Rust
//! Codegen vtables and vtable accesses.
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//!
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//! See `rustc_codegen_ssa/src/meth.rs` for reference.
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use crate::constant::data_id_for_alloc_id;
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use crate::prelude::*;
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fn vtable_memflags() -> MemFlags {
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let mut flags = MemFlags::trusted(); // A vtable access is always aligned and will never trap.
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flags.set_readonly(); // A vtable is always read-only.
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flags
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}
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pub(crate) fn drop_fn_of_obj(fx: &mut FunctionCx<'_, '_, '_>, vtable: Value) -> Value {
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let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes() as usize;
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fx.bcx.ins().load(
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pointer_ty(fx.tcx),
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vtable_memflags(),
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vtable,
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(ty::COMMON_VTABLE_ENTRIES_DROPINPLACE * usize_size) as i32,
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)
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}
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pub(crate) fn size_of_obj(fx: &mut FunctionCx<'_, '_, '_>, vtable: Value) -> Value {
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let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes() as usize;
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fx.bcx.ins().load(
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pointer_ty(fx.tcx),
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vtable_memflags(),
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vtable,
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(ty::COMMON_VTABLE_ENTRIES_SIZE * usize_size) as i32,
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)
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}
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pub(crate) fn min_align_of_obj(fx: &mut FunctionCx<'_, '_, '_>, vtable: Value) -> Value {
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let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes() as usize;
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fx.bcx.ins().load(
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pointer_ty(fx.tcx),
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vtable_memflags(),
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vtable,
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(ty::COMMON_VTABLE_ENTRIES_ALIGN * usize_size) as i32,
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)
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}
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pub(crate) fn get_ptr_and_method_ref<'tcx>(
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fx: &mut FunctionCx<'_, '_, 'tcx>,
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arg: CValue<'tcx>,
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idx: usize,
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) -> (Value, Value) {
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let (ptr, vtable) = if let Abi::ScalarPair(_, _) = arg.layout().abi {
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arg.load_scalar_pair(fx)
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} else {
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let (ptr, vtable) = arg.try_to_ptr().unwrap();
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(ptr.get_addr(fx), vtable.unwrap())
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};
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let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes();
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let func_ref = fx.bcx.ins().load(
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pointer_ty(fx.tcx),
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vtable_memflags(),
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vtable,
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(idx * usize_size as usize) as i32,
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);
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(ptr, func_ref)
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}
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pub(crate) fn get_vtable<'tcx>(
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fx: &mut FunctionCx<'_, '_, 'tcx>,
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ty: Ty<'tcx>,
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trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
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) -> Value {
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let alloc_id = fx.tcx.vtable_allocation(ty, trait_ref);
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let data_id =
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data_id_for_alloc_id(&mut fx.constants_cx, &mut *fx.module, alloc_id, Mutability::Not);
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let local_data_id = fx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
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if fx.clif_comments.enabled() {
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fx.add_comment(local_data_id, format!("vtable: {:?}", alloc_id));
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}
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fx.bcx.ins().global_value(fx.pointer_type, local_data_id)
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}
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