----- Original Message ----- From: "RB" <[email protected]> To: "OpenWrt Development List" <[email protected]> Sent: Monday, January 17, 2011 3:42 PM Subject: Re: [OpenWrt-Devel] Optimize for speed, not for size
> On Mon, Jan 17, 2011 at 00:32, Bastian Bittorf <[email protected]> wrote: > > this is theory as must be checked. > > If the GCC man page is theoretical, then I'm obviously a big fan of > fiction. Please spend an evening with 'man 1 gcc' and learn what > optimizations are turned on with what switches and what effects those > optimizations have before issuing such assertions. You may be > surprised to find that many optimizations turned on under -O3 are also > used under -Os. > gcc kindly answer to the optimizer question, when politely asked gcc -Os -Q --help=optimizers > gcc-$(gcc -dumpversion)-Os.txt gcc -O3 -Q --help=optimizers > gcc-$(gcc -dumpversion)-O3.txt This example is with Ubuntu 10.04 diff gcc-4.4.3-Os.txt gcc-4.4.3-O3.txt 40c40 < -fgcse-after-reload [disabled] --- > -fgcse-after-reload [enabled] 53c53 < -fipa-cp-clone [disabled] --- > -fipa-cp-clone [enabled] 78c78 < -fpredictive-commoning [disabled] --- > -fpredictive-commoning [enabled] 145c145 < -ftree-vectorize [disabled] --- > -ftree-vectorize [enabled] 152c152 < -funswitch-loops [disabled] --- > -funswitch-loops [enabled] Gilles _______________________________________________ openwrt-devel mailing list [email protected] https://lists.openwrt.org/mailman/listinfo/openwrt-devel
