[Bug tree-optimization/106397] [13 Regression] ICE in check_loop_closed_ssa_def, at tree-ssa-loop-manip.cc:645 since r13-1450-gd2a898666609452e

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106397

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
The prefetching pass puts a __builtin_ia32_mfence () before the
__builtin_unreachable () at the loop exit.  IIRC there's a related bug that
while return statements have a VUSE alternate "function returns" may lack them
(that includes some EH related returns as well).

Since the function eventually splits loop exit edges it breaks LC SSA anyway
(that's a latent issue I think).