[C++ PATCH] Fix ICE with PTRMEM_CST (PR c++/70869)

[Jason Merrill]

OK for trunk; just the earlier patch is fine for 6.2.

On Mon, Jul 11, 2016 at 4:17 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Thu, Jul 07, 2016 at 03:06:55PM -0400, Jason Merrill wrote:
>> On Thu, Jul 7, 2016 at 2:23 PM, Jakub Jelinek <jakub@redhat.com> wrote:
>> > On Thu, Jul 07, 2016 at 12:32:02PM -0400, Jason Merrill wrote:
>> >> Hmm, I wonder if walk_tree_1 should walk into DECL_EXPR like it does into
>> >> BIND_EXPR_VARS.  But your patch is OK.
>> >
>> > Well, walk_tree_1 does walk into DECL_EXPR, but cp_genericize_r says
>> > *walk_subtrees on the VAR_DECL inside of it.
>> > When walking BIND_EXPR_VARS, it doesn't walk the vars themselves, but
>> >             /* Walk the DECL_INITIAL and DECL_SIZE.  We don't want to walk
>> >                into declarations that are just mentioned, rather than
>> >                declared; they don't really belong to this part of the tree.
>> >                And, we can see cycles: the initializer for a declaration
>> >                can refer to the declaration itself.  */
>> >             WALK_SUBTREE (DECL_INITIAL (decl));
>> >             WALK_SUBTREE (DECL_SIZE (decl));
>> >             WALK_SUBTREE (DECL_SIZE_UNIT (decl));
>> > Do you mean walk_tree_1 should walk DECL_INITIAL/DECL_SIZE/DECL_SIZE_UNIT
>> > of the var mentioned in the DECL_EXPR?  Then for many vars (which are both
>> > mentioned in BIND_EXPR_VARS and in DECL_EXPR) it would walk them twice.
>>
>> Yes, that's what I meant.  Or perhaps since this is a C++ FE issue,
>> cp_walk_subtrees should walk those fields for artificial variables.
>
> I've already committed the patch, given your "But your patch is OK." above.
> But the following works too, bootstrapped/regtested on x86_64-linux and
> i686-linux, ok for trunk?
>
> If yes, do you want the combined diff from both patches on the 6.2 branch
> too, or just the earlier patch?
>
> 2016-07-11  Jakub Jelinek  <jakub@redhat.com>
>
>         PR c++/70869
>         PR c++/71054
>         * cp-gimplify.c (cp_genericize_r): Revert the 2016-07-07 change.
>         * tree.c (cp_walk_subtrees): For DECL_EXPR on DECL_ARTIFICIAL
>         non-static VAR_DECL, walk the decl's DECL_INITIAL, DECL_SIZE and
>         DECL_SIZE_UNIT.
>
> --- gcc/cp/cp-gimplify.c.jj     2016-07-11 11:24:30.554083084 +0200
> +++ gcc/cp/cp-gimplify.c        2016-07-11 15:21:30.459546129 +0200
> @@ -1351,15 +1351,7 @@ cp_genericize_r (tree *stmt_p, int *walk
>      {
>        tree d = DECL_EXPR_DECL (stmt);
>        if (TREE_CODE (d) == VAR_DECL)
> -       {
> -         gcc_assert (CP_DECL_THREAD_LOCAL_P (d) == DECL_THREAD_LOCAL_P (d));
> -         /* User var initializers should be genericized during containing
> -            BIND_EXPR genericization when walk_tree walks DECL_INITIAL
> -            of BIND_EXPR_VARS.  Artificial temporaries might not be
> -            mentioned there though, so walk them now.  */
> -         if (DECL_ARTIFICIAL (d) && !TREE_STATIC (d) && DECL_INITIAL (d))
> -           cp_walk_tree (&DECL_INITIAL (d), cp_genericize_r, data, NULL);
> -       }
> +       gcc_assert (CP_DECL_THREAD_LOCAL_P (d) == DECL_THREAD_LOCAL_P (d));
>      }
>    else if (TREE_CODE (stmt) == OMP_PARALLEL
>            || TREE_CODE (stmt) == OMP_TASK
> --- gcc/cp/tree.c.jj    2016-07-11 11:14:28.000000000 +0200
> +++ gcc/cp/tree.c       2016-07-11 15:30:38.635047697 +0200
> @@ -4075,6 +4075,22 @@ cp_walk_subtrees (tree *tp, int *walk_su
>        *walk_subtrees_p = 0;
>        break;
>
> +    case DECL_EXPR:
> +      /* User variables should be mentioned in BIND_EXPR_VARS
> +        and their initializers and sizes walked when walking
> +        the containing BIND_EXPR.  Compiler temporaries are
> +        handled here.  */
> +      if (VAR_P (TREE_OPERAND (*tp, 0))
> +         && DECL_ARTIFICIAL (TREE_OPERAND (*tp, 0))
> +         && !TREE_STATIC (TREE_OPERAND (*tp, 0)))
> +       {
> +         tree decl = TREE_OPERAND (*tp, 0);
> +         WALK_SUBTREE (DECL_INITIAL (decl));
> +         WALK_SUBTREE (DECL_SIZE (decl));
> +         WALK_SUBTREE (DECL_SIZE_UNIT (decl));
> +       }
> +      break;
> +
>      default:
>        return NULL_TREE;
>      }
>
>
>         Jakub