61 lines
1.7 KiB
Rust
61 lines
1.7 KiB
Rust
use rustc_middle::mir::*;
|
|
use rustc_middle::ty::{self, TyCtxt};
|
|
|
|
/// Returns `true` if this place is allowed to be less aligned
|
|
/// than its containing struct (because it is within a packed
|
|
/// struct).
|
|
pub fn is_disaligned<'tcx, L>(
|
|
tcx: TyCtxt<'tcx>,
|
|
local_decls: &L,
|
|
param_env: ty::ParamEnv<'tcx>,
|
|
place: Place<'tcx>,
|
|
) -> bool
|
|
where
|
|
L: HasLocalDecls<'tcx>,
|
|
{
|
|
debug!("is_disaligned({:?})", place);
|
|
if !is_within_packed(tcx, local_decls, place) {
|
|
debug!("is_disaligned({:?}) - not within packed", place);
|
|
return false;
|
|
}
|
|
|
|
let ty = place.ty(local_decls, tcx).ty;
|
|
match tcx.layout_raw(param_env.and(ty)) {
|
|
Ok(layout) if layout.align.abi.bytes() == 1 => {
|
|
// if the alignment is 1, the type can't be further
|
|
// disaligned.
|
|
debug!("is_disaligned({:?}) - align = 1", place);
|
|
false
|
|
}
|
|
_ => {
|
|
debug!("is_disaligned({:?}) - true", place);
|
|
true
|
|
}
|
|
}
|
|
}
|
|
|
|
fn is_within_packed<'tcx, L>(tcx: TyCtxt<'tcx>, local_decls: &L, place: Place<'tcx>) -> bool
|
|
where
|
|
L: HasLocalDecls<'tcx>,
|
|
{
|
|
let mut cursor = place.projection.as_ref();
|
|
while let &[ref proj_base @ .., elem] = cursor {
|
|
cursor = proj_base;
|
|
|
|
match elem {
|
|
// encountered a Deref, which is ABI-aligned
|
|
ProjectionElem::Deref => break,
|
|
ProjectionElem::Field(..) => {
|
|
let ty = Place::ty_from(place.local, proj_base, local_decls, tcx).ty;
|
|
match ty.kind() {
|
|
ty::Adt(def, _) if def.repr.packed() => return true,
|
|
_ => {}
|
|
}
|
|
}
|
|
_ => {}
|
|
}
|
|
}
|
|
|
|
false
|
|
}
|