1 files changed, 0 insertions, 76 deletions
diff --git a/compiler/rustc_mir/src/transform/remove_zsts.rs b/compiler/rustc_mir/src/transform/remove_zsts.rs
deleted file mode 100644
index 03277b1b2e0..00000000000
--- a/compiler/rustc_mir/src/transform/remove_zsts.rs
+++ /dev/null
@@ -1,76 +0,0 @@
-//! Removes assignments to ZST places.
-
-use crate::transform::MirPass;
-use rustc_middle::mir::tcx::PlaceTy;
-use rustc_middle::mir::{Body, LocalDecls, Place, StatementKind};
-use rustc_middle::ty::{self, Ty, TyCtxt};
-
-pub struct RemoveZsts;
-
-impl<'tcx> MirPass<'tcx> for RemoveZsts {
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        let param_env = tcx.param_env(body.source.def_id());
-        let (basic_blocks, local_decls) = body.basic_blocks_and_local_decls_mut();
-        for block in basic_blocks.iter_mut() {
-            for statement in block.statements.iter_mut() {
-                if let StatementKind::Assign(box (place, _)) = statement.kind {
-                    let place_ty = place.ty(local_decls, tcx).ty;
-                    if !maybe_zst(place_ty) {
-                        continue;
-                    }
-                    let layout = match tcx.layout_of(param_env.and(place_ty)) {
-                        Ok(layout) => layout,
-                        Err(_) => continue,
-                    };
-                    if !layout.is_zst() {
-                        continue;
-                    }
-                    if involves_a_union(place, local_decls, tcx) {
-                        continue;
-                    }
-                    if tcx.consider_optimizing(|| {
-                        format!(
-                            "RemoveZsts - Place: {:?} SourceInfo: {:?}",
-                            place, statement.source_info
-                        )
-                    }) {
-                        statement.make_nop();
-                    }
-                }
-            }
-        }
-    }
-}
-
-/// A cheap, approximate check to avoid unnecessary `layout_of` calls.
-fn maybe_zst(ty: Ty<'_>) -> bool {
-    match ty.kind() {
-        // maybe ZST (could be more precise)
-        ty::Adt(..) | ty::Array(..) | ty::Closure(..) | ty::Tuple(..) | ty::Opaque(..) => true,
-        // definitely ZST
-        ty::FnDef(..) | ty::Never => true,
-        // unreachable or can't be ZST
-        _ => 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;
-}