On Wed, May 02, 2012 at 11:24:13AM +0200, Richard Guenther wrote: > > Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, > > ok for trunk/4.7? > > Ok.
Thanks. > > BTW, tree-ssa-loop-prefetch.c seems to have the same problem, but no idea > > how that should be handled in there... > > I think it handles it fine by treating the chrec_dont_know DDR > properly? I suppose > failing would be an option, too, by returning a bool from > determine_loop_nest_reuse > and adjusting its single caller. IMHO it will just segfault (I don't have a testcase though). compute_all_dependences (datarefs, &dependences, vloops, true); FOR_EACH_VEC_ELT (ddr_p, dependences, i, dep) { if (DDR_ARE_DEPENDENT (dep) == chrec_known) continue; ref = (struct mem_ref *) DDR_A (dep)->aux; refb = (struct mem_ref *) DDR_B (dep)->aux; if (DDR_ARE_DEPENDENT (dep) == chrec_dont_know || DDR_NUM_DIST_VECTS (dep) == 0) { /* If the dependence cannot be analyzed, assume that there might * be a reuse. */ dist = 0; ref->independent_p = false; refb->independent_p = false; } If compute_all_dependences above fails (returns false), then dependences vector will contain just single chrec_dont_know element, but with DDR_A (dep) == DDR_B (dep) == NULL. So the above will try to dereference both and ICE before checking chrec_dont_know (and even if it wouldn't, there is nothing to mark independent_p = false - supposedly everything should be no longer independent_p). Jakub