------- Comment #12 from law at redhat dot com 2010-02-11 04:49 ------- Subject: Re: [4.4/4.5 regression] IRA apparently systematically making reload too busy on 2 address instructions with 3 operands
On 02/10/10 02:46, steven at gcc dot gnu dot org wrote: > ------- Comment #9 from steven at gcc dot gnu dot org 2010-02-10 09:46 > ------- > What is the purpose of regmove these days, anyway? Isn't it all useless code > thanks to IRA? > Not quite. There were some hunks that were removed shortly after IRA was integrated. The majority of what's left are things not handled by IRA. The code most likely to be useless right now is optimize_reg_copy_2. With some IRA work, optimize_reg_copy_1 might disappear. optimize_reg_copy_3 optimizes zero & sign extensions. One could argue this should be handled elsewhere. fixup_match_2 optimizes constants in arithmetic insns -- the net result is some lifetimes may be shortened and autoinc opportunities may be exposed. This could be handled by more modern techniques, but certainly isn't something IRA should be doing. Jeff -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42973
