O4 Optimization

[Ristioja@…]

mplayer is configured to compile with the -O4 parameter, which, at least in case
of GCC, does nothing. In my opinion GCC only supports the following:

-O0 Do not optimize,
-O1 Optimize,
-O2 Optimize even more,
-O3 Optimize yet more,
-Os Optimize for size.

You can check the manpage of gcc for these. And if it won't compile with those,
you can always break these flags up. For example if O3 (which stands for O2 +
-finline-functions, -fweb and -frename-registers) does not work, but O2 does,
the problem may lie in one of those flags. So, for instance, if you identify
that -frename-registers makes things go wrong, you can still use:

-O2 -finline-functions -fweb

[reimar]

Some project even use -O99, so what? Complain to the gcc team that their manpage
is incomplete if you want, though there is not much to document, it behaves just
like -O3.

[Ristioja@…]

So why not use -O3? Just to clear things up.

PS: I just discovered that you can pass CFLAGS to configure as an environment
variable. Did solve my problem, and might be of some help to other folks. :)