[Bug tree-optimization/122734] [15/16 Regression] ch gets confused with some extra if (a) __builtin_unreachable

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122734

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Created attachment 62835
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=62835&action=edit
This patch kinda of works but seems to peel a full iteration off

Signed-off-by: Andrew Pinski <andrew.pinski@oss.qualcomm.com>

This partly works but it seems to have copied too much.