[FFmpeg-devel] [PATCH] x86/cpu: set avxslow cpuflag on bdver4 and btver2 CPUs

[James Almer]

On 2/7/2016 1:38 PM, Hendrik Leppkes wrote:
> On Sun, Feb 7, 2016 at 4:05 AM, James Almer <jamrial at gmail.com> wrote:
>> They are also slow when using 256 bit wide registers
>>
>> Signed-off-by: James Almer <jamrial at gmail.com>
>> ---
>> See https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=3a33f4ce8ea1efdebec7f7138d00e9be9a12d630
>>  libavutil/x86/cpu.c | 10 ++++------
>>  1 file changed, 4 insertions(+), 6 deletions(-)
>>
>> diff --git a/libavutil/x86/cpu.c b/libavutil/x86/cpu.c
>> index f57d72d..bb63daa 100644
>> --- a/libavutil/x86/cpu.c
>> +++ b/libavutil/x86/cpu.c
>> @@ -182,13 +182,11 @@ int ff_get_cpu_flags_x86(void)
>>
>>          /* Similar to the above but for AVX functions on AMD processors.
>>             This is necessary only for functions using YMM registers on Bulldozer
>> -           based CPUs as they lack 256-bits execution units. SSE/AVX functions
>> -           using XMM registers are always faster on them.
>> +           and Jaguar based CPUs as they lack 256-bits execution units. SSE/AVX
>> +           functions using XMM registers are always faster on them.
>>             AV_CPU_FLAG_AVX and AV_CPU_FLAG_AVXSLOW are both set so that AVX is
>> -           used unless explicitly disabled by checking AV_CPU_FLAG_AVXSLOW.
>> -           TODO: Confirm if Excavator is affected or not by this once it's
>> -                 released, and update the check if necessary. Same for btver2. */
>> -            if (family == 0x15 && (rval & AV_CPU_FLAG_AVX))
>> +           used unless explicitly disabled by checking AV_CPU_FLAG_AVXSLOW. */
>> +            if ((family == 0x15 || family == 0x16) && (rval & AV_CPU_FLAG_AVX))
>>                  rval |= AV_CPU_FLAG_AVXSLOW;
>>          }
>>
> 
> 
> LGTM.

Pushed, thanks.