Re: [PATCH, libgfortran] PR 60324 Unbounded stack allocations in libgfortran

[Janne Blomqvist <blomqvist dot janne at gmail dot com>]

On Fri, Nov 14, 2014 at 11:02 PM, Tobias Burnus <burnus@net-b.de> wrote:
> Cesar Philippidis wrote:
>>
>> On 11/13/2014 02:32 AM, Janne Blomqvist wrote:
>> I hit an error when building intrinsics/random.c:
>>    error: expression in static assertion is not constant
>> Joseph told me that static const variables cannot be used in constant
>> expressions in C, so I've replaced the _Static_assert with a regular
>> assert. Are you using g++ to build libgfortran?
>
>
> I wonder why you are seeing this while others aren't.

Yeah, I wonder the same?

>> I don't have a good baseline test this patch thoroughly, but at least I
>> can bootstrap gcc without it failing in libgfortran. Is this OK for
>> mainline and/or could someone see if it causes any regressions?
>
>
> I think instead of doing a run-time check I'd prefer something like the
> following, keeping the compile-time assert.
>
> --- a/libgfortran/intrinsics/random.c
> +++ b/libgfortran/intrinsics/random.c
> @@ -253 +253 @@ static GFC_UINTEGER_4 kiss_default_seed[] = {
> -static const GFC_INTEGER_4 kiss_size =
> sizeof(kiss_seed)/sizeof(kiss_seed[0]);
> +#define KISS_SIZE ((GFC_INTEGER_4) (sizeof(kiss_seed)/sizeof(kiss_seed[0]))
>
> (plus s/kiss_size/KISS_SIZE/ changes in the code.)
>
> Janne, what do you think?

I like it. With this, you can also get rid of the assert and the newly
introduced KISS_MAX_SIZE macro, and just make the seed array the
correct size, as was originally done (with a VLA). Consider such a
patch pre-approved.


-- 
Janne Blomqvist