https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118333
--- Comment #2 from Hongtao Liu <liuhongt at gcc dot gnu.org> --- (In reply to Uroš Bizjak from comment #1) > (In reply to David Binderman from comment #0) > > Static analyser cppcheck says: > > > > gcc/config/i386/i386-expand.cc:24871:35: warning: Identical condition > > '!TARGET_AVX512BW', second condition is always false > > [identicalConditionAfterEarlyExit] > > > > Source code is > > > > if (!TARGET_AVX512BW) > > return false; > > > > if ((qimode == V16QImode && !TARGET_AVX2) > > || (qimode == V32QImode && (!TARGET_AVX512BW || !TARGET_EVEX512)) > > /* There are no V64HImode instructions. */ > > || qimode == V64QImode) > > return false; > > > > Suggest remove second condition. > > The comment before the first condition says: > > /* Without VPMOVWB (provided by AVX512BW ISA), the expansion uses the > generic permutation to merge the data back into the right place. This > permutation results in VPERMQ, which is slow, so better fall back to > ix86_expand_vecop_qihi. */ > > so the whole function should be rewritten with this in mind. Even with the > above condition in place, V16QImode without AVX512VL will fallback to VPERMQ: > > case E_V16QImode: > himode = V16HImode; > if (TARGET_AVX512VL && TARGET_AVX512BW) > gen_truncate = gen_truncv16hiv16qi2; Yes, I'll do a refactor.
