Re: [FFmpeg-devel] Don't use _tzcnt instrinics with clang for windows w/o BMI.

2017-10-25 Thread Michael Niedermayer
On Thu, Oct 26, 2017 at 03:39:57AM +1100, Matt Oliver wrote: > On 25 October 2017 at 07:15, Dale Curtis wrote: > > > Technically _tzcnt* intrinsics are only available when the BMI > > instruction set is present. However the instruction encoding > > degrades to "rep bsf"

Re: [FFmpeg-devel] Don't use _tzcnt instrinics with clang for windows w/o BMI.

2017-10-25 Thread Matt Oliver
On 25 October 2017 at 07:15, Dale Curtis wrote: > Technically _tzcnt* intrinsics are only available when the BMI > instruction set is present. However the instruction encoding > degrades to "rep bsf" on older processors. > > Clang for Windows debatably restricts the

[FFmpeg-devel] Don't use _tzcnt instrinics with clang for windows w/o BMI.

2017-10-24 Thread Dale Curtis
Technically _tzcnt* intrinsics are only available when the BMI instruction set is present. However the instruction encoding degrades to "rep bsf" on older processors. Clang for Windows debatably restricts the _tzcnt* instrinics behind the __BMI__ architecture define, so check for its presence or