On Fri, May 31, 2019 at 10:05:22AM +0200, Arnd Bergmann wrote: > If I remember correctly, we also had the same issue with older versions > of clang, possibly even newer ones. Shouldn't we check for a minimum > compiler version when building with clang to ensure that the code is > really vectorized? > > Arnd
Even on tip of tree, it doesn't look like vectorization happens properly. With -S -Rpass-missed='.*' added to the xor-neon.c command: /home/nathan/cbl/linux-next/include/asm-generic/xor.h:15:2: remark: the cost-model indicates that interleaving is not beneficial [-Rpass-missed=loop-vectorize] /home/nathan/cbl/linux-next/include/asm-generic/xor.h:11:1: remark: List vectorization was possible but not beneficial with cost 0 >= 0 [-Rpass-missed=slp-vectorizer] xor_8regs_2(unsigned long bytes, unsigned long *p1, unsigned long *p2) ^ So right now, it doesn't look like there is a minimum version for clang and I don't think adding a warning for clang is productive (what is a user supposed to do?) Cheers, Nathan
