[Bug ipa/78644] [7 Regression] ICE: SIGSEGV in is_gimple_reg_type with -Og -fipa-cp

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78644

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Verified reverting the tree-ssa-ccp.c hunk of r242920 makes the ICE go away
(then instead of _18 = _7 + _17; there is _18 = x2_3 + _17;
(no idea why _7 hasn't actually been replaced with 0 but just with x2_3, though
there is UB involved in the loop if x4[0] isn't 0 at the beginning)).