[Bug ipa/127479] [14/15/16/17 Regression] GCC 15.2 IPA-ICF merges distinct >= and <= comparison functions under -flto, causing incorrect runtime behavior

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127479

--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
OK, so the issue is that LTO streaming can change the order of edges in the
edge vectors and thus the order of PHI arguments.  ICF compares IPA references
in the order they appear in the CFG walk (and PHI argument edges in the order
of the arguments).  This causes the comparison to break down with LTO.