[prev in list] [next in list] [prev in thread] [next in thread] 

List:       linux-kernel
Subject:    Re: any chance of 2.6.0-test*?
From:       "Albert D. Cahalan" <acahalan () cs ! uml ! edu>
Date:       2003-01-13 22:37:48
[Download RAW message or body]


Matti Aarnio writes:

> Advanced optimizer hinting features, like unlikely() attribute
> are very new in (this) compiler, and while they in theory move the
> "unlikely" codes out of the fast-path, such things have been buggy
> in the past, and we are worried of bug effects... 

I've been wondering about this as the goto-thread spewed by.

As I recall, gcc recently started moving basic blocks around.
This destroyed most of the careful goto-based optimizations.
Now we're supposed to use likely() and unlikely() instead.

Hmmm?

BTW, what I'd like is a way to change optimization settings
on a per-function or even per-block basis. Telling gcc to
unroll a specific loop or pack a function into a tiny space
would be really cool.   __attribute__((__opt__("-Os")))
I could go for an "assume default case can't happen" too.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/
[prev in list] [next in list] [prev in thread] [next in thread]