https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65875
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> --- (In reply to Jakub Jelinek from comment #3) > Created attachment 35395 [details] > gcc5-pr65875.patch > > Untested fix. IMHO vrp_visit_phi_node was missing the vr_result VR_VARING > handling if the value range turned into varying only during > update_value_range, and also update_value_range wasn't telling the caller if > it changed it into varying late. > > That said, the testcase has conditionally undefined variable, and checking > whether all the VRP decisions (first and second pass) are sane, would be > nice, Richard, could you please have a look? > E.g. I find it strange that h has VR [0, LONG_MAX] before VRP2, when it > really has just values 0 or 1, so should be ideally [0, 1]. Or that i has > value range [1, LONG_MAX] - it is conditionally undefined (that is ignored), > and conditionally negation of an int variable (only if that int variable is > negative). The negated int variable is [1, +INF(OVF)] because INT_MIN might > overflow, perhaps if we really need to preserve the OVF flag, we have to use > [1, +INF(OVF)] again rather than just [1, 0x7fffffff] :(. For h we get into the loop PHI handling code which drops to INF-1 if it iterates "too much". The rest probably ripples down from that. I can't see where that [1, 0x7ffffff] issue happens.
