https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84777
Bug ID: 84777
Summary: -Os inhibits all vectorization
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: linux at carewolf dot com
Target Milestone: ---
Neither the command-line flag -ftree-loop-vectorize nor -fopenmp combined with
"#pragma omp simd" works when -Os is active.
It seems that it when specified manually vectorization should be work even in
-Os mode. I can almost see why -ftree-loop-vectorize wouldn't work, which is
why I tried the manual marking of loops to vectorize, but the latter didn't
work either.
I would suggest documenting this behavior and fix at least vectorizing manually
marked loops.
