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I’m currently measuring the performance of some code in FLOPS. This code presents some arithmetic negate instructions like this one:
d = -a
where d and a are floating point variables. The architecture I’m currently using does have specific negate instructions. Should I have to take into account this kind of operations to measure FLOPS? What kind of operations account for FLOPS? Is there a convention or anything?
As @Andrey said, to be sure you should check the disassembled code.
But in general, yes, the instruction would likely execute on a FPU. It simply flips a bit, so it could be done on an integer unit as well, but since you’re operating on floating point values, these are most likely already loaded into FP registers, and so there’d be a fair amount of overhead to moving them to general purpose registers, flipping the bit and moving them back.
I don’t know if there is a complete universal guide to “what should be counted as a FLOP”, but this is most likely an instruction which executes on a FPU, and so it is competing with other FP instructions for resources on the CPU, so yes, I would include it in a FLOPS count.