On Mon, Nov 13, 2017 at 6:25 PM, Shalnov, Sergey <sergey.shal...@intel.com> wrote: > Hi, > Modern architectures provides wider and wider vector registers. This patch > implements > common (in i386 arch) option to prefer vector register width for the > vectorizer. > Currently, GCC has "-mprefer-avx128" and "-mprefer-avx256" options to limit > maximum > vector register width in vectorizer. To avoid feature implementation of > further options > like "-mprefer-avx512", "-mprefer-avx1024", etc. I propose to implement > the option "-mprefer-vector-width=[none|128|256|512]". > > Also I propose to remove recently added -mprefer-avx256 option in favor > of -mprefer-vector-width=256 and consider also make -mprefer-avx128 as > deprecated. > Latter one is already there for few years, so It might be better to keep it as > deprecated for some time.
This is a good idea, but please mark -mprefer-avx128 "RejectNegative Alias(mprefer-vector-width=, 128)". IMO, we can leave this option as is, no need to deprecate it, or warn about its usage. Using Alias keyword, it will be just a shortcut for -mprefer-vector-width=128. [BTW: --mprefer-avx128 should be marked RejectNegative from the beginning; let's just assume nobody uses it in its (somehow weird) negative "-mno-prefer-avx128" form.] Uros.
