overflow checking benchmarks

[Henry Cejtin]

As far as the cost for the jo instructions, could it be branch prediction?  I
would think that for  these  benchmarks  things  loop  sufficiently  that  it
doesn't  matter,  but  perhaps  for  the  cases not recently seen the default
assumption is wrong.  I know that on the Alpha CPU,  a  branch  backwards  is
assumed  to be taken if it isn't in the branch table.  If your block ordering
is such that some of the jo's are to smaller addresses, then  this  could  be
happening.

Can that explain the slow down?