[Bug tree-optimization/65875] [5/6 Regression] ICE: Segmentation fault

["rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

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.