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Auto merge of #105436 - nnethercote:inline-place_contents_drop_state_cannot_differ, r=spastorino

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Inline and remove `place_contents_drop_state_cannot_differ`.

It has a single call site and is hot enough to be worth inlining. And make sure `is_terminal_path` is inlined, too.

r? `@ghost`
This commit is contained in:
bors 2022-12-13 03:28:57 +00:00
commit 71ec1457ee
1 changed files with 46 additions and 51 deletions
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97
compiler/rustc_mir_dataflow/src/drop_flag_effects.rs
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@ -29,56 +29,6 @@ where
None
}
/// When enumerating the child fragments of a path, don't recurse into
/// paths (1.) past arrays, slices, and pointers, nor (2.) into a type
/// that implements `Drop`.
///
/// Places behind references or arrays are not tracked by elaboration
/// and are always assumed to be initialized when accessible. As
/// references and indexes can be reseated, trying to track them can
/// only lead to trouble.
///
/// Places behind ADT's with a Drop impl are not tracked by
/// elaboration since they can never have a drop-flag state that
/// differs from that of the parent with the Drop impl.
///
/// In both cases, the contents can only be accessed if and only if
/// their parents are initialized. This implies for example that there
/// is no need to maintain separate drop flags to track such state.
//
// FIXME: we have to do something for moving slice patterns.
fn place_contents_drop_state_cannot_differ<'tcx>(
tcx: TyCtxt<'tcx>,
body: &Body<'tcx>,
place: mir::Place<'tcx>,
) -> bool {
let ty = place.ty(body, tcx).ty;
match ty.kind() {
ty::Array(..) => {
debug!(
"place_contents_drop_state_cannot_differ place: {:?} ty: {:?} => false",
place, ty
);
false
}
ty::Slice(..) | ty::Ref(..) | ty::RawPtr(..) => {
debug!(
"place_contents_drop_state_cannot_differ place: {:?} ty: {:?} refd => true",
place, ty
);
true
}
ty::Adt(def, _) if (def.has_dtor(tcx) && !def.is_box()) || def.is_union() => {
debug!(
"place_contents_drop_state_cannot_differ place: {:?} ty: {:?} Drop => true",
place, ty
);
true
}
_ => false,
}
}
pub fn on_lookup_result_bits<'tcx, F>(
tcx: TyCtxt<'tcx>,
body: &Body<'tcx>,
@ -105,13 +55,58 @@ pub fn on_all_children_bits<'tcx, F>(
) where
F: FnMut(MovePathIndex),
{
#[inline]
fn is_terminal_path<'tcx>(
tcx: TyCtxt<'tcx>,
body: &Body<'tcx>,
move_data: &MoveData<'tcx>,
path: MovePathIndex,
) -> bool {
place_contents_drop_state_cannot_differ(tcx, body, move_data.move_paths[path].place)
let place = move_data.move_paths[path].place;
// When enumerating the child fragments of a path, don't recurse into
// paths (1.) past arrays, slices, and pointers, nor (2.) into a type
// that implements `Drop`.
//
// Places behind references or arrays are not tracked by elaboration
// and are always assumed to be initialized when accessible. As
// references and indexes can be reseated, trying to track them can
// only lead to trouble.
//
// Places behind ADT's with a Drop impl are not tracked by
// elaboration since they can never have a drop-flag state that
// differs from that of the parent with the Drop impl.
//
// In both cases, the contents can only be accessed if and only if
// their parents are initialized. This implies for example that there
// is no need to maintain separate drop flags to track such state.
//
// FIXME: we have to do something for moving slice patterns.
let ty = place.ty(body, tcx).ty;
match ty.kind() {
ty::Adt(def, _) if (def.has_dtor(tcx) && !def.is_box()) || def.is_union() => {
debug!(
"place_contents_drop_state_cannot_differ place: {:?} ty: {:?} Drop => true",
place, ty
);
true
}
ty::Array(..) => {
debug!(
"place_contents_drop_state_cannot_differ place: {:?} ty: {:?} => false",
place, ty
);
false
}
ty::Slice(..) | ty::Ref(..) | ty::RawPtr(..) => {
debug!(
"place_contents_drop_state_cannot_differ place: {:?} ty: {:?} refd => true",
place, ty
);
true
}
_ => false,
}
}
fn on_all_children_bits<'tcx, F>(