RFR: 8287700: C2 Crash running eclipse benchmark from Dacapo

[Xin Liu]

On Tue, 7 Jun 2022 07:48:42 GMT, Roland Westrelin <roland at openjdk.org> wrote:

> With 8275201 (C2: hide klass() accessor from TypeOopPtr and typeKlassPtr subclasses), I made the following change to escape.cpp:
> 
> 
> @@ -2628,7 +2632,7 @@ bool ConnectionGraph::split_AddP(Node *addp, Node *base) {
>    // this code branch will go away.
>    //
>    if (!t->is_known_instance() &&
> -      !base_t->klass()->is_subtype_of(t->klass())) {
> +      !t->maybe_java_subtype_of(base_t)) {
>       return false; // bail out
>    }
>    const TypeOopPtr *tinst = base_t->add_offset(t->offset())->is_oopptr();
> @@ -3312,7 +3316,7 @@ void ConnectionGraph::split_unique_types(GrowableArray<Node *>  &alloc_worklist,
>          } else {
>            tn_t = tn_type->isa_oopptr();
>          }
> -        if (tn_t != NULL && tinst->klasgs()->is_subtype_of(tn_t->klass())) {
> +        if (tn_t != NULL && tn_t->maybe_java_subtype_of(tinst)) {
>            if (tn_type->isa_narrowoop()) {
>              tn_type = tinst->make_narrowoop();
>            } else {
> @@ -3325,7 +3329,7 @@ void ConnectionGraph::split_unique_types(GrowableArray<Node *>  &alloc_worklist,
>            record_for_optimizer(n);
>          } else {
>            assert(tn_type == TypePtr::NULL_PTR ||
> -                 tn_t != NULL && !tinst->klass()->is_subtype_of(tn_t->klass()),
> +                 tn_t != NULL && !tinst->is_java_subtype_of(tn_t),
>                   "unexpected type");
>            continue; // Skip dead path with different type
>          }
> 
> 
> Where I inverted the subtype and supertype in a subtype check (that is `tn_t->maybe_java_subtype_of(tinst)` when it was `tinst->klasgs()->is_subtype_of(tn_t->klass())`) in 2 places for no good reason AFAICT now. The assert used to also test the same condition as the if above but I changed that by mistake. This fixes addresses both issues.

LGTM.

-------------

Marked as reviewed by xliu (Committer).

PR: https://git.openjdk.java.net/jdk/pull/9054