On Wed, Apr 11, 2012 at 12:39 PM, Richard Guenther <richard.guent...@gmail.com> wrote: > On Tue, Apr 10, 2012 at 8:43 PM, Igor Zamyatin <izamya...@gmail.com> wrote: >> Hi All! >> >> Here is a patch that enables unroll at O2 for Atom. >> >> This gives good performance boost on EEMBC 2.0 (~+8% in Geomean for 32 >> bits) with quite moderate code size increase (~5% for EEMBC2.0, 32 >> bits). > > 5% is not moderate. Your patch does enable unrolling at -O2 but not -O3, > why? Why do you disable register renaming? check_imull requires a function > comment.
Sure, enabling unroll for O3 could be the next step. We can't avoid code size increase with unroll - what number do you think will be appropriate? Register renaming was the reason of several degradations during tuning process Comment for check_imull was added > > This completely looks like a hack for EEMBC2.0, so it's definitely not ok. Why? EEMBC was measured and result provided here just because this benchmark considers to be very relevant for Atom > > -O2 is not supposed to give best benchmark results. O2 is wide-used so performance improvement could be important for users. > > Thanks, > Richard. > >> >> Tested for i386 and x86-64, ok for trunk? Updated patch attached >> >> Thanks, >> Igor >> >> ChangeLog: >> >> 2012-04-10 Yakovlev Vladimir <vladimir.b.yakov...@intel.com> >> >> * gcc/config/i386/i386.c (check_imul): New routine. >> (ix86_loop_unroll_adjust): New target hook. >> (ix86_option_override_internal): Enable unrolling on Atom at -O2. >> (TARGET_LOOP_UNROLL_ADJUST): New define.
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