gcc autovectorize

[Cyrille Berger]

> It may also let you (the developer) know how it may effect
> performance without dealing with hand coding it just yet.


> In which cases
> did you find it buggy? I would think it wouldn't create any more bugs than
> were already existant... but perhaps its doing something funny, and if it
> is, perhaps the people writting the vectorizer should be notified.
just googling a bit
http://www.google.com/search?q=ftree-vectorize&ie=UTF-8&oe=UTF-8

even the man page of gcc for most of those option (not about
-ftree-vectorize) gives a lot of warning on usuage of such functions.
I haven't played much with -ftree-vectorize so I can't speak
specifically about this option. But usually, when something isn't
enabled by one of the -O option of gcc, it's because either the gcc
folks consider it unstable, either it doesn't necesserellay give a
performance boost. In this case, I consider the former. (and even if
it's in -O3, it's risky, and yes I have experienced reproductible weird
crash at -O3 not apparing at -O2).

That's said, there are quiet a lot of crash in krita which are caused
by the code and not gcc ;)

--
Cyrille Berger