------- Comment #5 from rguenther at suse dot de 2009-08-13 15:58 ------- Subject: Re: invariant address load inside loop with -Os.
On Thu, 13 Aug 2009, rahul at icerasemi dot com wrote: > ------- Comment #4 from rahul at icerasemi dot com 2009-08-13 15:46 ------- > Confirmed. Introducing loop header copy for Os, resolves the problem. > On our port, this not only helps move the invariant load outside the loop, but > also correctly uses an auto-increment address mode via the AutoInc patches we > use. Other examples also confirm that the header copying enables more > induction > variables to be identified and hence post-increment opportunities. > > Does better loop analysis and hence potential for further optimizations > outweigh the cost of copying the loop header? It would be ideal to relax the > loop header copy predicate for Os and select an appropriate threshold, > currently set at 20 insn, a lower value to start with perhaps. Experimenting with that would be certainly useful. Richard. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41026
