[Bug tree-optimization/59249] if-conversion doesn't handle basic-blocks with only critical predecessor edges

[bmei at broadcom dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59249

--- Comment #4 from Bingfeng Mei <bmei at broadcom dot com> ---
Even I split one critical predecessor edge, predicate of BB6 is still ORed
result of two conditions from BB4 & BB5. ORing two conditions results in a
sequence of statements that cannot be vectorized. Vectorizer complains of
"bit-precision arithmetic not supported" because of boolean operations.

Not sure how to transform the code except reverting back to a form similar to
pre jump-threading.