bjoernager/rust
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only set noalias on Box with the global allocator

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This commit is contained in:
Ralf Jung 2024-03-05 11:32:03 +01:00
parent 5a1e5449c8
commit f391c0793b
17 changed files with 75 additions and 28 deletions
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20
compiler/rustc_middle/src/ty/layout.rs
View file

@ -969,6 +969,8 @@ where
}
}
/// Compute the information for the pointer stored at the given offset inside this type.
/// This will recurse into fields of ADTs to find the inner pointer.
fn ty_and_layout_pointee_info_at(
this: TyAndLayout<'tcx>,
cx: &C,
@ -1068,15 +1070,17 @@ where
}
}
// FIXME(eddyb) This should be for `ptr::Unique<T>`, not `Box<T>`.
// Fixup info for the first field of a `Box`. Recursive traversal will have found
// the raw pointer, so size and align are set to the boxed type, but `pointee.safe`
// will still be `None`.
if let Some(ref mut pointee) = result {
if let ty::Adt(def, _) = this.ty.kind() {
if def.is_box() && offset.bytes() == 0 {
let optimize = tcx.sess.opts.optimize != OptLevel::No;
pointee.safe = Some(PointerKind::Box {
unpin: optimize && this.ty.boxed_ty().is_unpin(tcx, cx.param_env()),
});
}
if offset.bytes() == 0 && this.ty.is_box() {
debug_assert!(pointee.safe.is_none());
let optimize = tcx.sess.opts.optimize != OptLevel::No;
pointee.safe = Some(PointerKind::Box {
unpin: optimize && this.ty.boxed_ty().is_unpin(tcx, cx.param_env()),
global: this.ty.is_box_global(tcx),
});
}
}

21
compiler/rustc_middle/src/ty/sty.rs
View file

@ -1999,6 +1999,27 @@ impl<'tcx> Ty<'tcx> {
}
}
/// Tests whether this is a Box using the global allocator.
#[inline]
pub fn is_box_global(self, tcx: TyCtxt<'tcx>) -> bool {
match self.kind() {
Adt(def, args) if def.is_box() => {
let Some(alloc) = args.get(1) else {
// Single-argument Box is always global. (for "minicore" tests)
return true;
};
if let Some(alloc_adt) = alloc.expect_ty().ty_adt_def() {
let global_alloc = tcx.require_lang_item(LangItem::GlobalAlloc, None);
alloc_adt.did() == global_alloc
} else {
// Allocator is not an ADT...
false
}
}
_ => false,
}
}
/// Panics if called on any type other than `Box<T>`.
pub fn boxed_ty(self) -> Ty<'tcx> {
match self.kind() {