This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [PATCH] Fix unsafe function attributes for special functions (PR 71876)
On 07/22/16 14:28, Richard Biener wrote:
> On Thu, 21 Jul 2016, Bernd Edlinger wrote:
>
>> Hi,
>>
>> based on the discussion here, I have updated my patch again...
>>
>> This is the rest of the patch, which removes outdated function names,
>> and creates built-in definitions for vfork, getcontext, savectx.
>> These built-ins have the return_twice attribute but not the
>> leaf attribute, because we do not really know, what these functions
>> do.
>>
>> The reason for ceating the builtin functions is, that I would like
>> to get a warning about conflicting builtin definition if someone
>> accidentally picks the name of one of these less well known special
>> functions, which are _not_ reserved names in most environments.
>>
>> I do not define builtins (without __builtin_ prefix) for setjmp and
>> sigsetjmp because these are like wildcards, and they fall in the
>> well-known category anyways.
>>
>> I still retain the handling of these functions in special_function_p
>> because even in a free standing environment, returning
>> ECF_RETURNS_TWICE is on the safe side.
>>
>>
>>
>> Is it OK for trunk after boot-strap and regression-testing?
>
> As DEF_EXT_LIB_BUILTIN won't have any effect with -std=c99 for example
> I don't think having the builtins helps much. I think we have
> this name-matching function for correctness purposes (and even my
> local glibc doesn't declare [v]fork as returning twice nor does
> the existing BUILT_IN_FORK btw).
>
fork does not have to, but it is a no-leaf function because it
calls pthread_atfork handlers. So it has to be __TROWNL.
I think in the long run the header files just should be fixed.
But that will take a while...
Bernd.