//! Removes assignments to ZST places.
use crate::MirPass;
-use rustc_middle::mir::tcx::PlaceTy;
-use rustc_middle::mir::{Body, LocalDecls, Place, StatementKind};
+use rustc_middle::mir::{Body, StatementKind};
use rustc_middle::ty::{self, Ty, TyCtxt};
pub struct RemoveZsts;
if !layout.is_zst() {
continue;
}
- if involves_a_union(place, local_decls, tcx) {
- continue;
- }
if tcx.consider_optimizing(|| {
format!(
"RemoveZsts - Place: {:?} SourceInfo: {:?}",
_ => false,
}
}
-
-/// Miri lazily allocates memory for locals on assignment,
-/// so we must preserve writes to unions and union fields,
-/// or it will ICE on reads of those fields.
-fn involves_a_union<'tcx>(
- place: Place<'tcx>,
- local_decls: &LocalDecls<'tcx>,
- tcx: TyCtxt<'tcx>,
-) -> bool {
- let mut place_ty = PlaceTy::from_ty(local_decls[place.local].ty);
- if place_ty.ty.is_union() {
- return true;
- }
- for elem in place.projection {
- place_ty = place_ty.projection_ty(tcx, elem);
- if place_ty.ty.is_union() {
- return true;
- }
- }
- return false;
-}