jhorstmann commented on PR #1830: URL: https://github.com/apache/arrow-rs/pull/1830#issuecomment-1152660580
> One question. Because the RUSTFLAGS="-Ctarget-cpu=xxx" is for optimizing on specific CPU model. But for existing simd feature, we don't need to specify CPU. Compared with existing simd feature, is the RUSTFLAGS less general? The simd feature also benefits from specifying the `target-cpu`. Without `target-cpu`, the compiler has to produce code for a common baseline. For x86_64, that baseline includes the SSE2 instructions, which work on 128bit vectors, but misses many useful features added later. I'm guessing here the compiler decides that it's not worthwhile to use sse2 instructions, but it's heuristic seems wrong here. There probably is some additional compiler flag that would make the standard kernel as fast as the simd kernel also for the default target. We probably can't expect everyone to set several flags though. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
