On Mon, Jan 15, 2018 at 05:07:22PM +0100, Arnd Bergmann wrote: > My last bugfix added -Os on the command line, which unfortunately caused > a build regression on powerpc in some configurations. > > I've done some more analysis of the original problem and found slightly > different workaround that avoids this regression and also results in > better performance on gcc-7.0: -fcode-hoisting is an optimization step > that got added in gcc-7 and that for all gcc-7 versions causes worse > performance. > > This disables -fcode-hoisting on all compilers that understand the option. > For gcc-7.1 and 7.2 I found the same performance as my previous patch > (using -Os), in gcc-7.0 it was even better. On gcc-8 I could see no > change in performance from this patch. In theory, code hoisting should > not be able make things better for the AES cipher, so leaving it > disabled for gcc-8 only serves to simplify the Makefile change. > > Reported-by: kbuild test robot <fengguang.wu@xxxxxxxxx> > Link: https://www.mail-archive.com/linux-crypto@xxxxxxxxxxxxxxx/msg30418.html > Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83356 > Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83651 > Fixes: 148b974deea9 ("crypto: aes-generic - build with -Os on gcc-7+") > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Patch applied. Thanks. -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
