------- Comment #15 from amonakov at gmail dot com 2007-12-05 16:26 ------- Zdenek,
please kindly share your thoughts on concerns expressed in previous comments. The failures of number-of-iterations analysis prohibit applying modulo scheduling to many simple loops that are otherwise eligible; in fact, I now test SMS with either your patch reverted, or with -funsafe-loop-optimizations, but I believe this is not a healthy state. Please correct me if I am wrong, but I think that optimizing out the variable that holds number of iterations is not desirable on targets that have doloop machine idiom, because doloop rtl pass will re-introduce it in a specially designated register. However, ia64 does not allow arithmetic operations with loop counter, so it would be nice if iv-opts transformed the loop to the form where decrement-and-branch-on-zero are the only uses of this variable, when possible. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32283
