2020-09-23 08:13:49 -05:00
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//! Codegen vtables and vtable accesses.
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//!
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2021-04-07 14:47:01 -05:00
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//! See `rustc_codegen_ssa/src/meth.rs` for reference.
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2020-09-23 08:13:49 -05:00
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// FIXME dedup this logic between miri, cg_llvm and cg_clif
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2018-09-08 11:00:06 -05:00
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use crate::prelude::*;
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2021-06-20 04:43:25 -05:00
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use super::constant::pointer_for_allocation;
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2018-09-08 11:00:06 -05:00
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2019-12-20 09:16:28 -06:00
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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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2021-03-05 12:12:59 -06:00
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pub(crate) fn drop_fn_of_obj(fx: &mut FunctionCx<'_, '_, '_>, vtable: Value) -> Value {
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2020-08-22 09:47:31 -05:00
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let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes() as usize;
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2019-02-07 13:45:15 -06:00
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fx.bcx.ins().load(
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2020-08-22 09:47:31 -05:00
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pointer_ty(fx.tcx),
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2019-12-20 09:16:28 -06:00
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vtable_memflags(),
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2019-02-07 13:45:15 -06:00
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vtable,
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2021-06-14 05:02:53 -05:00
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(ty::COMMON_VTABLE_ENTRIES_DROPINPLACE * usize_size) as i32,
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2019-02-07 13:45:15 -06:00
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)
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}
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2021-03-05 12:12:59 -06:00
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pub(crate) fn size_of_obj(fx: &mut FunctionCx<'_, '_, '_>, vtable: Value) -> Value {
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2020-08-22 09:47:31 -05:00
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let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes() as usize;
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2018-09-08 11:00:06 -05:00
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fx.bcx.ins().load(
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2020-08-22 09:47:31 -05:00
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pointer_ty(fx.tcx),
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2019-12-20 09:16:28 -06:00
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vtable_memflags(),
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2018-09-08 11:00:06 -05:00
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vtable,
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2021-06-14 05:02:53 -05:00
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(ty::COMMON_VTABLE_ENTRIES_SIZE * usize_size) as i32,
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2018-09-08 11:00:06 -05:00
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)
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}
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2021-03-05 12:12:59 -06:00
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pub(crate) fn min_align_of_obj(fx: &mut FunctionCx<'_, '_, '_>, vtable: Value) -> Value {
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2020-08-22 09:47:31 -05:00
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let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes() as usize;
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2018-09-15 04:14:27 -05:00
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fx.bcx.ins().load(
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2020-08-22 09:47:31 -05:00
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pointer_ty(fx.tcx),
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2019-12-20 09:16:28 -06:00
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vtable_memflags(),
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2018-09-15 04:14:27 -05:00
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vtable,
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2021-06-17 11:41:43 -05:00
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(ty::COMMON_VTABLE_ENTRIES_ALIGN * usize_size) as i32,
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2018-09-15 04:14:27 -05:00
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)
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}
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2020-03-27 06:14:45 -05:00
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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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2020-03-10 14:41:31 -05:00
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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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2020-08-28 05:10:48 -05:00
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(ptr.get_addr(fx), vtable.unwrap())
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2020-03-10 14:41:31 -05:00
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};
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2020-08-22 09:47:31 -05:00
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let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes();
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2018-09-08 11:00:06 -05:00
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let func_ref = fx.bcx.ins().load(
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2020-08-22 09:47:31 -05:00
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pointer_ty(fx.tcx),
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2019-12-20 09:16:28 -06:00
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vtable_memflags(),
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2018-09-08 11:00:06 -05:00
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vtable,
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2021-06-14 05:02:53 -05:00
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(idx * usize_size as usize) as i32,
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2018-09-08 11:00:06 -05:00
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);
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(ptr, func_ref)
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}
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2020-03-27 06:14:45 -05:00
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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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2019-01-06 08:27:20 -06:00
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trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
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) -> Value {
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let vtable_ptr = if let Some(vtable_ptr) = fx.vtables.get(&(ty, trait_ref)) {
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*vtable_ptr
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2018-09-08 11:00:06 -05:00
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} else {
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2021-06-20 04:43:25 -05:00
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let vtable_alloc_id = fx.tcx.vtable_allocation(ty, trait_ref);
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let vtable_allocation = fx.tcx.global_alloc(vtable_alloc_id).unwrap_memory();
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let vtable_ptr = pointer_for_allocation(fx, vtable_allocation);
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2018-09-08 11:00:06 -05:00
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2021-06-20 04:43:25 -05:00
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fx.vtables.insert((ty, trait_ref), vtable_ptr);
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vtable_ptr
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2019-01-06 08:27:20 -06:00
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};
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2018-09-08 11:00:06 -05:00
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2021-06-20 04:43:25 -05:00
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vtable_ptr.get_addr(fx)
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2018-09-08 11:00:06 -05:00
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}
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