------- Additional Comments From sebastian dot pop at cri dot ensmp dot fr 2005-01-02 21:46 ------- (In reply to comment #7) > Subject: Re: [4.0 regression] Endless loop compiling simple file: Bug in tree-scalar-evolution.c (instantiate_parameters_1)? > > not really (well, maybe in this particular case, but not in general). > Your patch definitely helps (and you should submit it anyway), but > yhe problem is that even with your patch it may happen that > instantiate_parameters is called recursively several times for one > ssa name if the expression contains it several times, and if this > happens for several expressions in a row, you get the exponential > complexity. I am just testing the patch below that caches the results > to avoid this problem. >
Richtig. I'm just speeding the chrec_dont_know case, whereas your patch solves the more general problem of huge expressions that have to be instantiated and that don't necessarily lead to unknown evolutions. Thanks. PS: I'll test my patch separately and will post it to gcc-patches. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19224
