> Maxim Kuvyrkov wrote: > > You are removing the 2nd alternative that generates "abs" with your patch. > While I agree that > using "csneg" is faster on all implementations, can you say the same for > "abs"? Especially > given the fact that csneg requires 4 operands instead of abs'es 2?
Yes, given that latencies of scalar SIMD instructions are typically worse than integer latencies. The number of operands is not an issue. > Wouldn't it be better to have (define_expand "abs<mode>2") that would expand > into either > csneg3<mode> or second alternative of current absdi2? How would that be possible? You'd have to delay expansion until after register allocation, which loses optimization opportunities. And I still don't see how it would ever make sense to execute integer operations as scalar SIMD. Wilco
