Auto merge of #78597 - RalfJung:raw-retag, r=oli-obk
Retagging: do not retag 'raw reborrows' When doing `&raw const (*raw_ptr).field`, we do not want any retagging; the original provenance should be fully preserved. Fixes https://github.com/rust-lang/miri/issues/1608 Test added by https://github.com/rust-lang/miri/pull/1614 Not sure whom to ask for review on this... `@oli-obk` can you have a look? Or maybe highfive makes a good choice.^^
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0cd1516696
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@ -73,6 +73,19 @@ impl<'tcx> MirPass<'tcx> for AddRetag {
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// a temporary and retag on that.
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is_stable(place.as_ref()) && may_be_reference(place.ty(&*local_decls, tcx).ty)
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};
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let place_base_raw = |place: &Place<'tcx>| {
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// If this is a `Deref`, get the type of what we are deref'ing.
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let deref_base =
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place.projection.iter().rposition(|p| matches!(p, ProjectionElem::Deref));
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if let Some(deref_base) = deref_base {
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let base_proj = &place.projection[..deref_base];
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let ty = Place::ty_from(place.local, base_proj, &*local_decls, tcx).ty;
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ty.is_unsafe_ptr()
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} else {
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// Not a deref, and thus not raw.
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false
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}
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};
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// PART 1
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// Retag arguments at the beginning of the start block.
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@ -136,13 +149,14 @@ impl<'tcx> MirPass<'tcx> for AddRetag {
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// iterate backwards using indices.
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for i in (0..block_data.statements.len()).rev() {
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let (retag_kind, place) = match block_data.statements[i].kind {
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// Retag-as-raw after escaping to a raw pointer.
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StatementKind::Assign(box (place, Rvalue::AddressOf(..))) => {
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(RetagKind::Raw, place)
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// Retag-as-raw after escaping to a raw pointer, if the referent
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// is not already a raw pointer.
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StatementKind::Assign(box (lplace, Rvalue::AddressOf(_, ref rplace)))
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if !place_base_raw(rplace) =>
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{
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(RetagKind::Raw, lplace)
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}
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// Assignments of reference or ptr type are the ones where we may have
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// to update tags. This includes `x = &[mut] ...` and hence
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// we also retag after taking a reference!
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// Retag after assignments of reference type.
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StatementKind::Assign(box (ref place, ref rvalue)) if needs_retag(place) => {
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let kind = match rvalue {
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Rvalue::Ref(_, borrow_kind, _)
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