[Bug tree-optimization/122493] is_eye in leela is not split because of empty basic block (merge_phi should be part of cfgcleanup instead of its own pass)

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122493

--- Comment #14 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
+FAIL: gcc.dg/uninit-pr40635.c  (test for warnings, line 32)
+FAIL: gcc.dg/uninit-pr40635.c (test for excess errors)

I have a fix for this, it was a latent bug in the way
remove_forwarder_block_with_phi was handling locations of phi entries. it would
always use the location of the mapped location even if it was unknown.