[Mesa-dev] [PATCH 1/3] util: Cope with LONG_BIT not being defined on Windows.

[Jose Fonseca]

On 09/08/15 17:47, Matt Turner wrote:
> On Sun, Aug 9, 2015 at 3:57 AM, Jose Fonseca <jfonseca at vmware.com> wrote:
>> Neither MSVC nor MinGW defines LONG_BIT.  For MSVC this was not a problem as
>> it doesn't define __x86_64__ macro (it's GCC specific.)
>>
>> However on Windows long type is guaranteed to be 32bits.
>>
>> Also add an #error, as GCC will just warn, not throw any error, when no
>> value is returned.
>>
>> Trivial.
>> ---
>>   src/util/rounding.h | 8 ++++++--
>>   1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/src/util/rounding.h b/src/util/rounding.h
>> index b0c9918..ec31b47 100644
>> --- a/src/util/rounding.h
>> +++ b/src/util/rounding.h
>> @@ -96,8 +96,10 @@ _mesa_lroundevenf(float x)
>>   #ifdef __x86_64__
>>   #if LONG_BIT == 64
>>      return _mm_cvtss_si64(_mm_load_ss(&x));
>> -#elif LONG_BIT == 32
>> +#elif LONG_BIT == 32 || defined(_WIN32)
>
> Not clear to me that you want to do this, since on x86-32 using SSE
> intrinsics will force a few memory transfers to and from the x87 FPU.

Our Windows builds use SSE math for x86. (ie., -fpmath=sse for GCC, no 
option required for MSVC, as it's the standard.)  So no x87 should be 
ever used.

(Probably it should make sense to use -msse2 and -fpmath=sse on all 
32bits x86.)

>
>>      return _mm_cvtss_si32(_mm_load_ss(&x));
>> +#else
>> +#error "Unsupported or undefined LONG_BIT"
>
> MSVC... sigh.

The problem was actually with MinGW, not MSVC.  As the commit 
description said, MSVC was fine (because it doesn't define __x86_64__).

AFAICT, LONG_BIT is not standard C.  So I don't think that MSVC or MinGW 
is at fault.

Jose