[Mesa-dev] [PATCH] gallium/util: Define ffsll on OpenBSD.

[Emil Velikov]

On 26/02/15 13:49, Jose Fonseca wrote:
> On 26/02/15 13:42, Jose Fonseca wrote:
>> On 26/02/15 03:55, Jonathan Gray wrote:
>>> On Wed, Feb 25, 2015 at 07:09:26PM -0800, Matt Turner wrote:
>>>> On Wed, Feb 25, 2015 at 7:03 PM, Jonathan Gray <jsg at jsg.id.au> wrote:
>>>>> On Wed, Feb 25, 2015 at 06:53:14PM -0800, Matt Turner wrote:
>>>>>> On Wed, Feb 25, 2015 at 5:37 PM, Jonathan Gray <jsg at jsg.id.au> wrote:
>>>>>>> If it isn't going to be configure checks could someone merge the
>>>>>>> original patch in this thread?
>>>>>>
>>>>>> I committed
>>>>>>
>>>>>> commit 3492e88090d2d0c0bfbc934963b8772b45fc8880
>>>>>> Author: Matt Turner <mattst88 at gmail.com>
>>>>>> Date:   Fri Feb 20 18:46:43 2015 -0800
>>>>>>
>>>>>>      gallium/util: Use HAVE___BUILTIN_* macros.
>>>>>>
>>>>>>      Reviewed-by: Eric Anholt <eric at anholt.net>
>>>>>>      Reviewed-by: Jose Fonseca <jfonseca at vmware.com>
>>>>>>
>>>>>> which switched over a bunch of preprocessor checks around __builtin*
>>>>>> calls to use the macros defined by autotools.
>>>>>>
>>>>>> So I think cleaning it up to use __builtin_ffs* first #ifdef
>>>>>> HAVE___BUILTIN_* can go forward now.
>>>>>
>>>>> Yes but there is no HAVE_FFSLL for constructs like
>>>>>
>>>>> #if !defined(HAVE_FFSLL) && defined(HAVE___BUILTIN_FFSLL)
>>>>>
>>>>> or is it ok to always use the builtin?
>>>>
>>>> I think the question is whether it's okay to always use the builtin if
>>>> it's available (as opposed to libc functions). I think the answer to
>>>> that is yes.
>>>
>>> So in that case how about the following?  Or is it going to break
>>> the android scons build?
>>>
>>>  From cba39ba72115e57d262cb4b099c4e72106f01812 Mon Sep 17 00:00:00 2001
>>> From: Jonathan Gray <jsg at jsg.id.au>
>>> Date: Thu, 26 Feb 2015 14:46:45 +1100
>>> Subject: [PATCH] gallium/util: use ffs* builtins if available
>>>
>>> Required to build on OpenBSD which doesn't have ffsll in libc.
>>>
>>> Signed-off-by: Jonathan Gray <jsg at jsg.id.au>
>>> ---
>>>   src/gallium/auxiliary/util/u_math.h | 11 ++++++++---
>>>   1 file changed, 8 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/src/gallium/auxiliary/util/u_math.h
>>> b/src/gallium/auxiliary/util/u_math.h
>>> index b4a65e4..5bc9b97 100644
>>> --- a/src/gallium/auxiliary/util/u_math.h
>>> +++ b/src/gallium/auxiliary/util/u_math.h
>>> @@ -384,9 +384,6 @@ unsigned ffs( unsigned u )
>>>
>>>      return i;
>>>   }
>>> -#elif defined(__MINGW32__) || defined(PIPE_OS_ANDROID)
>>> -#define ffs __builtin_ffs
>>> -#define ffsll __builtin_ffsll
>>
>> Scons does define HAVE___BUILTIN_FFS for mingw.
>>
>> However `git grep '\<ffs\>` shows ffs is used directly in many other
>> places.  So I suspect this change will break them.
>>
>>>   #endif
>>>
>>>   #endif /* FFS_DEFINED */
>>> @@ -435,7 +432,11 @@ util_last_bit_signed(int i)
>>>   static INLINE int
>>>   u_bit_scan(unsigned *mask)
>>>   {
>>> +#if defined(HAVE___BUILTIN_FFS)
>>> +   int i = __builtin_ffs(*mask) - 1;
>>> +#else
>>>      int i = ffs(*mask) - 1;
>>> +#endif
>>>      *mask &= ~(1 << i);
>>>      return i;
>>>   }
>>> @@ -444,7 +445,11 @@ u_bit_scan(unsigned *mask)
>>>   static INLINE int
>>>   u_bit_scan64(uint64_t *mask)
>>>   {
>>> +#if defined(HAVE___BUILTIN_FFSLL)
>>> +   int i = __builtin_ffsll(*mask) - 1;
>>> +#else
>>>      int i = ffsll(*mask) - 1;
>>> +#endif
>>>      *mask &= ~(1llu << i);
>>>      return i;
>>>   }
>>>
>>
>>
>> I think the right thing long term is to provide ffs and ffsll in
>> c99_compat.h or c99_math.h for all platforms.  And let the rest of the
>> code just always assume it's available somehow.
>>
>>
>> Otherwise, let's just '#define ffs __builtin_ffs' on OpenBSD too.
> 
> In other words, the original patch on this thread
> 
>   http://lists.freedesktop.org/archives/mesa-dev/2015-February/076071.html
> 
> is the only patch I've seen so far that doesn't break Mingw.
> 
> If you rather use HAVE___BUILTIN_FFSLL, then just do
> 
> diff --git a/src/gallium/auxiliary/util/u_math.h
> b/src/gallium/auxiliary/util/u_math.h
> index 959f76e..d372cfd 100644
> --- a/src/gallium/auxiliary/util/u_math.h
> +++ b/src/gallium/auxiliary/util/u_math.h
> @@ -384,7 +384,7 @@ unsigned ffs( unsigned u )
> 
>     return i;
>  }
> -#elif defined(__MINGW32__) || defined(PIPE_OS_ANDROID)
> +#elif defined(__MINGW32__) || defined(PIPE_OS_ANDROID) ||
> defined(HAVE___BUILTIN_FFSLL)
>  #define ffs __builtin_ffs
>  #define ffsll __builtin_ffsll
>  #endif
> 
Jonathan

Seems like this has ended up a longer discussion that anticipated :\
Can you please confirm if the above works for you ?

Thanks
Emil