Re: [PATCH] Fix middle-end/81737

[Richard Biener <richard.guenther@gmail.com>]

On Tue, Aug 8, 2017 at 7:23 PM, Marek Polacek <polacek@redhat.com> wrote:
> On Mon, Aug 07, 2017 at 04:07:49PM +0200, Richard Biener wrote:
>> On August 7, 2017 11:09:59 AM GMT+02:00, Marek Polacek <polacek@redhat.com> wrote:
>> >On Mon, Aug 07, 2017 at 10:58:09AM +0200, Jakub Jelinek wrote:
>> >> On Mon, Aug 07, 2017 at 10:47:51AM +0200, Marek Polacek wrote:
>> >> > In my recent change I failed to check whether the type domain
>> >> > of a type is non-NULL and this goof causes crashing on this
>> >> > testcase.
>> >> >
>> >> > Bootstrapped/regtested on x86_64-linux, ok for trunk?
>> >> >
>> >> > 2017-08-07  Marek Polacek  <polacek@redhat.com>
>> >> >
>> >> >  PR middle-end/81737
>> >> >  * fold-const.c (fold_indirect_ref_1): Check type_domain.
>> >> >
>> >> >  * gcc.dg/pr81737.c: New test.
>> >>
>> >> The old code was assuming size_zero_node if type_domain is NULL
>> >> or TYPE_MIN_VALUE is NULL, which is reasonable for C/C++, but indeed
>> >might
>> >> be wrong perhaps for Fortran or Ada.
>>
>> It's how the middle-end defines it, so please restore this behavior (sorry for missing this in the review).  IIRC there are at least one other 'copy' of the folding somewhere.
>
> Sure, this patch should do it:
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2017-08-08  Marek Polacek  <polacek@redhat.com>
>
>         PR middle/81695
>         * fold-const.c (fold_indirect_ref_1): Restore original behavior
>         regarding size_zero_node.
>
> diff --git gcc/fold-const.c gcc/fold-const.c
> index 5a118ca50a1..2c47d1d16a4 100644
> --- gcc/fold-const.c
> +++ gcc/fold-const.c
> @@ -14109,22 +14109,21 @@ fold_indirect_ref_1 (location_t loc, tree type, tree op0)
>                    && type == TREE_TYPE (op00type))
>             {
>               tree type_domain = TYPE_DOMAIN (op00type);
> -             tree min;
> +             tree min = size_zero_node;
>               if (type_domain != NULL_TREE
> -                 && (min = TYPE_MIN_VALUE (type_domain))
> +                 && TYPE_MIN_VALUE (type_domain)
>                   && TREE_CODE (min) == INTEGER_CST)
> +               min = TYPE_MIN_VALUE (type_domain);

I think this is wrong for non-INTEGER_CST TYPE_MIN_VALUE.

Richard.

> +             offset_int off = wi::to_offset (op01);
> +             offset_int el_sz = wi::to_offset (TYPE_SIZE_UNIT (type));
> +             offset_int remainder;
> +             off = wi::divmod_trunc (off, el_sz, SIGNED, &remainder);
> +             if (remainder == 0)
>                 {
> -                 offset_int off = wi::to_offset (op01);
> -                 offset_int el_sz = wi::to_offset (TYPE_SIZE_UNIT (type));
> -                 offset_int remainder;
> -                 off = wi::divmod_trunc (off, el_sz, SIGNED, &remainder);
> -                 if (remainder == 0)
> -                   {
> -                     off = off + wi::to_offset (min);
> -                     op01 = wide_int_to_tree (sizetype, off);
> -                     return build4_loc (loc, ARRAY_REF, type, op00, op01,
> -                                        NULL_TREE, NULL_TREE);
> -                   }
> +                 off = off + wi::to_offset (min);
> +                 op01 = wide_int_to_tree (sizetype, off);
> +                 return build4_loc (loc, ARRAY_REF, type, op00, op01,
> +                                    NULL_TREE, NULL_TREE);
>                 }
>             }
>         }
>
>         Marek