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.
This commit is contained in:
bors 2021-06-05 14:08:38 +00:00
commit 9104c898eb

View File

@ -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);