------- Comment #7 from steven at gcc dot gnu dot org 2005-11-14 10:32 ------- It would be more interesting to measure than think ;-)
My experience is that when it is in Briggs' test suite, it usually also happens in actually useful code. But, only the numbers will tell :-) Zdenek is right, it's just a matter of comparing the evolutions of loop PHI nodes. Instrumenting the compiler to count how often this happens is half the work of implementing the optimization if it turns out to be useful. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19590
