Auto merge of #85869 - tmiasko:box-free, r=nagisa

Remove special handling of `box_free` from `LocalAnalyzer` The special casing of `box_free` predates the use of dominators in analyzer. It is no longer necessary now that analyzer verifies that the first assignment dominates all uses.

Author: bors

compiler/rustc_codegen_ssa/src/mir/analyze.rs

@@ -11,7 +11,6 @@ use rustc_middle::mir::visit::{
  MutatingUseContext, NonMutatingUseContext, NonUseContext, PlaceContext, Visitor,
 };
 use rustc_middle::mir::{self, Location, TerminatorKind};
-use rustc_middle::ty;
 use rustc_middle::ty::layout::HasTyCtxt;
 use rustc_target::abi::LayoutOf;
 
@@ -228,34 +227,6 @@ impl<'mir, 'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> Visitor<'tcx>
  self.visit_rvalue(rvalue, location);
  }
 
- fn visit_terminator(&mut self, terminator: &mir::Terminator<'tcx>, location: Location) {
- let check = match terminator.kind {
- mir::TerminatorKind::Call { func: mir::Operand::Constant(ref c), ref args, .. } => {
- match *c.ty().kind() {
- ty::FnDef(did, _) => Some((did, args)),
- _ => None,
- }
- }
- _ => None,
- };
- if let Some((def_id, args)) = check {
- if Some(def_id) == self.fx.cx.tcx().lang_items().box_free_fn() {
- // box_free(x) shares with `drop x` the property that it
- // is not guaranteed to be statically dominated by the
- // definition of x, so x must always be in an alloca.
- if let mir::Operand::Move(ref place) = args[0] {
- self.visit_place(
- place,
- PlaceContext::MutatingUse(MutatingUseContext::Drop),
- location,
- );
- }
- }
- }
-
- self.super_terminator(terminator, location);
- }
-
  fn visit_place(&mut self, place: &mir::Place<'tcx>, context: PlaceContext, location: Location) {
  debug!("visit_place(place={:?}, context={:?})", place, context);
  self.process_place(&place.as_ref(), context, location);