On 22/02/14 17:42, James Almer wrote: > On 22/02/14 1:29 PM, Luca Barbato wrote: >> On 22/02/14 06:53, James Almer wrote: >>> These are the missing instruction sets introduced with Haswell/Piledriver >>> CPUs. >>> >>> Last two patches are based on x264 detection code. >> >> The set doesn't look bad at all but I'm wondering about it's usage: >> >>> James Almer (3): >>> x86: add missing XOP checks and macros >>> x86: add detection for FMA3 instruction set >> >> Which is the relationship between FMA3 and FMA4 ? >> > > It's what happens when Intel and AMD don't talk to each other to coordinate > stuff. > Short story summary here: https://en.wikipedia.org/wiki/FMA_instruction_set > > Both sets do the same in essence. The only difference is that one uses three > operands > while the other uses four (Technically, FMA4 is the most flexible, but it's > only > supported by AMD). > AMD added FMA4 starting with Bulldozer, then added FMA3 as well to Piledriver > for > compatibility reasons once Intel revealed they would use that starting with > Haswell. > >>> x86: add detection for Bit Manipulation Instruction sets >> >> Is BMI a subset of AVX2? > > No, they are independent and work on general registers. > AMD added BMI1 starting with Piledriver, which doesn't support AVX2, whereas > Intel > added both BMI1 and BMI2 starting with Haswell. >
So complex as usual... I'd let another day pass (hoping somebody else reads those and push them. lu _______________________________________________ libav-devel mailing list [email protected] https://lists.libav.org/mailman/listinfo/libav-devel
