https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91460
H.J. Lu <hjl.tools at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- Target| |i386 Status|UNCONFIRMED |NEW Last reconfirmed| |2019-08-15 Ever confirmed|0 |1 --- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> --- When loop trip count is known, vectorizer won't select 256-bit vector when 266-bit vector can't be used. When loop trip count is unknown, 256-bit vector can be slower than 128-bit vector, depending on workloads. In case of SPEC CPU 2017, 128-bit vector is much faster than 256-bit vector for a couple benchmarks. For most of benchmarks, there are no performance differences between 128-bit vector and 256-bit vector.