[Bug tree-optimization/84777] -Os inhibits all vectorization

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84777

--- Comment #7 from rguenther at suse dot de <rguenther at suse dot de> ---
On Fri, 9 Mar 2018, linux at carewolf dot com wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84777
> 
> --- Comment #6 from Allan Jensen <linux at carewolf dot com> ---
> Great. Your patch worked with 90% of the marked loops!

Good!

> The remaining report things like this with -fopt-info-vec-missed:
> 
> note: not vectorized: relevant stmt not supported: idisty.872_437 = (unsigned
> int) idisty_386;
> note: bad operation or unsupported loop bound.
> 
> But the result is already pretty good for -fopenmp with manually marked loops.

So is it any better if you use -O2 rather than -Os?  Do you really need
-Os?  GCCs -O2 isn't as excessive code-size wise as competitors like ICC.