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make first component of dyn* use pointer layout+type, and adjust DynStar comment

This commit is contained in:
Ralf Jung 2023-02-06 15:54:35 +01:00 committed by Michael Goulet
parent 3eb5c4581a
commit 88e39ee314
4 changed files with 6 additions and 15 deletions

View file

@ -39,7 +39,7 @@ use rustc_session::Session;
use rustc_span::symbol::sym; use rustc_span::symbol::sym;
use rustc_span::Symbol; use rustc_span::Symbol;
use rustc_span::{DebuggerVisualizerFile, DebuggerVisualizerType}; use rustc_span::{DebuggerVisualizerFile, DebuggerVisualizerType};
use rustc_target::abi::{Align, Size, VariantIdx}; use rustc_target::abi::{Align, VariantIdx};
use std::collections::BTreeSet; use std::collections::BTreeSet;
use std::time::{Duration, Instant}; use std::time::{Duration, Instant};
@ -273,13 +273,6 @@ pub fn cast_to_dyn_star<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
matches!(dst_ty.kind(), ty::Dynamic(_, _, ty::DynStar)), matches!(dst_ty.kind(), ty::Dynamic(_, _, ty::DynStar)),
"destination type must be a dyn*" "destination type must be a dyn*"
); );
// FIXME(dyn-star): this is probably not the best way to check if this is
// a pointer, and really we should ensure that the value is a suitable
// pointer earlier in the compilation process.
let src = match src_ty_and_layout.pointee_info_at(bx.cx(), Size::ZERO) {
Some(_) => bx.ptrtoint(src, bx.cx().type_isize()),
None => bx.bitcast(src, bx.type_isize()),
};
(src, unsized_info(bx, src_ty_and_layout.ty, dst_ty, old_info)) (src, unsized_info(bx, src_ty_and_layout.ty, dst_ty, old_info))
} }

View file

@ -770,7 +770,7 @@ where
ty::Dynamic(_, _, ty::DynStar) => { ty::Dynamic(_, _, ty::DynStar) => {
if i == 0 { if i == 0 {
TyMaybeWithLayout::Ty(tcx.types.usize) TyMaybeWithLayout::Ty(tcx.mk_mut_ptr(tcx.types.unit))
} else if i == 1 { } else if i == 1 {
// FIXME(dyn-star) same FIXME as above applies here too // FIXME(dyn-star) same FIXME as above applies here too
TyMaybeWithLayout::Ty( TyMaybeWithLayout::Ty(

View file

@ -193,7 +193,7 @@ fn layout_of_uncached<'tcx>(
} }
ty::Dynamic(_, _, ty::DynStar) => { ty::Dynamic(_, _, ty::DynStar) => {
let mut data = scalar_unit(Int(dl.ptr_sized_integer(), false)); let mut data = scalar_unit(Pointer(AddressSpace::DATA));
data.valid_range_mut().start = 0; data.valid_range_mut().start = 0;
let mut vtable = scalar_unit(Pointer(AddressSpace::DATA)); let mut vtable = scalar_unit(Pointer(AddressSpace::DATA));
vtable.valid_range_mut().start = 1; vtable.valid_range_mut().start = 1;

View file

@ -26,11 +26,9 @@ pub enum DynKind {
Dyn, Dyn,
/// A sized `dyn* Trait` object /// A sized `dyn* Trait` object
/// ///
/// These objects are represented as a `(data, vtable)` pair where `data` is a ptr-sized value /// These objects are represented as a `(data, vtable)` pair where `data` is a value of some
/// (often a pointer to the real object, but not necessarily) and `vtable` is a pointer to /// ptr-sized and ptr-aligned dynamically determined type `T` and `vtable` is a pointer to the
/// the vtable for `dyn* Trait`. The representation is essentially the same as `&dyn Trait` /// vtable of `impl T for Trait`. This allows a `dyn*` object to be treated agnostically with
/// or similar, but the drop function included in the vtable is responsible for freeing the
/// underlying storage if needed. This allows a `dyn*` object to be treated agnostically with
/// respect to whether it points to a `Box<T>`, `Rc<T>`, etc. /// respect to whether it points to a `Box<T>`, `Rc<T>`, etc.
DynStar, DynStar,
} }