diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src')
| -rw-r--r-- | compiler/rustc_mir_transform/src/gvn.rs | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/compiler/rustc_mir_transform/src/gvn.rs b/compiler/rustc_mir_transform/src/gvn.rs index 8b8d1efbbd2..209e818e9e3 100644 --- a/compiler/rustc_mir_transform/src/gvn.rs +++ b/compiler/rustc_mir_transform/src/gvn.rs @@ -836,6 +836,7 @@ impl<'body, 'tcx> VnState<'body, 'tcx> { #[instrument(level = "trace", skip(self), ret)] fn simplify_rvalue( &mut self, + lhs: &Place<'tcx>, rvalue: &mut Rvalue<'tcx>, location: Location, ) -> Option<VnIndex> { @@ -855,7 +856,7 @@ impl<'body, 'tcx> VnState<'body, 'tcx> { Value::Repeat(op, amount) } Rvalue::NullaryOp(op, ty) => Value::NullaryOp(op, ty), - Rvalue::Aggregate(..) => return self.simplify_aggregate(rvalue, location), + Rvalue::Aggregate(..) => return self.simplify_aggregate(lhs, rvalue, location), Rvalue::Ref(_, borrow_kind, ref mut place) => { self.simplify_place_projection(place, location); return Some(self.new_pointer(*place, AddressKind::Ref(borrow_kind))); @@ -943,6 +944,7 @@ impl<'body, 'tcx> VnState<'body, 'tcx> { fn simplify_aggregate_to_copy( &mut self, + lhs: &Place<'tcx>, rvalue: &mut Rvalue<'tcx>, location: Location, fields: &[VnIndex], @@ -982,12 +984,16 @@ impl<'body, 'tcx> VnState<'body, 'tcx> { // Allow introducing places with non-constant offsets, as those are still better than // reconstructing an aggregate. - if let Some(place) = self.try_as_place(copy_from_local_value, location, true) { - if rvalue.ty(self.local_decls, self.tcx) == place.ty(self.local_decls, self.tcx).ty { + if let Some(place) = self.try_as_place(copy_from_local_value, location, true) + && rvalue.ty(self.local_decls, self.tcx) == place.ty(self.local_decls, self.tcx).ty + { + // Avoid creating `*a = copy (*b)`, as they might be aliases resulting in overlapping assignments. + // FIXME: This also avoids any kind of projection, not just derefs. We can add allowed projections. + if lhs.as_local().is_some() { self.reused_locals.insert(place.local); *rvalue = Rvalue::Use(Operand::Copy(place)); - return Some(copy_from_local_value); } + return Some(copy_from_local_value); } None @@ -995,6 +1001,7 @@ impl<'body, 'tcx> VnState<'body, 'tcx> { fn simplify_aggregate( &mut self, + lhs: &Place<'tcx>, rvalue: &mut Rvalue<'tcx>, location: Location, ) -> Option<VnIndex> { @@ -1090,7 +1097,7 @@ impl<'body, 'tcx> VnState<'body, 'tcx> { if let AggregateTy::Def(_, _) = ty && let Some(value) = - self.simplify_aggregate_to_copy(rvalue, location, &fields, variant_index) + self.simplify_aggregate_to_copy(lhs, rvalue, location, &fields, variant_index) { return Some(value); } @@ -1765,7 +1772,7 @@ impl<'tcx> MutVisitor<'tcx> for VnState<'_, 'tcx> { if let StatementKind::Assign(box (ref mut lhs, ref mut rvalue)) = stmt.kind { self.simplify_place_projection(lhs, location); - let value = self.simplify_rvalue(rvalue, location); + let value = self.simplify_rvalue(lhs, rvalue, location); let value = if let Some(local) = lhs.as_local() && self.ssa.is_ssa(local) // FIXME(#112651) `rvalue` may have a subtype to `local`. We can only mark |