bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Do not clone valtree and slice constants.

Browse source
This commit is contained in:
Camille GILLOT 2023-09-23 07:56:59 +00:00
parent 5f9d64d72f
commit b2ff77cb78
9 changed files with 605 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

31
compiler/rustc_mir_transform/src/gvn.rs
View file

@ -418,6 +418,35 @@ impl<'tcx> VnState<'_, 'tcx> {
/// If `index` is a `Value::Constant`, return the `Constant` to be put in the MIR.
fn try_as_constant(&mut self, index: VnIndex) -> Option<ConstOperand<'tcx>> {
if let Value::Constant(const_) = *self.get(index) {
// Some constants may contain pointers. We need to preserve the provenance of these
// pointers, but not all constants guarantee this:
// - valtrees purposefully do not;
// - ConstValue::Slice does not either.
match const_ {
Const::Ty(c) => match c.kind() {
ty::ConstKind::Value(valtree) => match valtree {
// This is just an integer, keep it.
ty::ValTree::Leaf(_) => {}
ty::ValTree::Branch(_) => return None,
},
ty::ConstKind::Param(..)
| ty::ConstKind::Unevaluated(..)
| ty::ConstKind::Expr(..) => {}
// Should not appear in runtime MIR.
ty::ConstKind::Infer(..)
| ty::ConstKind::Bound(..)
| ty::ConstKind::Placeholder(..)
| ty::ConstKind::Error(..) => bug!(),
},
Const::Unevaluated(..) => {}
// If the same slice appears twice in the MIR, we cannot guarantee that we will
// give the same `AllocId` to the data.
Const::Val(ConstValue::Slice { .. }, _) => return None,
Const::Val(
ConstValue::ZeroSized | ConstValue::Scalar(_) | ConstValue::Indirect { .. },
_,
) => {}
}
Some(ConstOperand { span: rustc_span::DUMMY_SP, user_ty: None, const_ })
} else {
None
@ -447,6 +476,8 @@ impl<'tcx> MutVisitor<'tcx> for VnState<'_, 'tcx> {
fn visit_statement(&mut self, stmt: &mut Statement<'tcx>, location: Location) {
self.super_statement(stmt, location);
if let StatementKind::Assign(box (_, ref mut rvalue)) = stmt.kind
// Do not try to simplify a constant, it's already in canonical shape.
&& !matches!(rvalue, Rvalue::Use(Operand::Constant(_)))
&& let Some(value) = self.simplify_rvalue(rvalue, location)
{
if let Some(const_) = self.try_as_constant(value) {