Messages in this thread | | | Date | Tue, 13 May 2008 23:46:27 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] common implementation of iterative div/mod |
| |
On Thu, 08 May 2008 16:16:41 +0100 Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> We have a few instances of the open-coded iterative div/mod loop, used > when we don't expcet the dividend to be much bigger than the divisor. > Unfortunately modern gcc's have the tendency to strength "reduce" this > into a full mod operation, which isn't necessarily any faster, and > even if it were, doesn't exist if gcc implements it in libgcc. > > The workaround is to put a dummy asm statement in the loop to prevent > gcc from performing the transformation. > > This patch creates a single implementation of this loop, and uses it > to replace the open-coded versions I know about.
Believe it or not, this patch causes one of my test machines to fail to find its disk.
good dmesg: http://userweb.kernel.org/~akpm/dmesg-t61p.txt bad dmesg: http://userweb.kernel.org/~akpm/dmesg-t61p-dead.txt config: http://userweb.kernel.org/~akpm/config-t61p.txt
| |