$ perl testSubs.pl
Benchmark: running assigner, direct, shifter, each for at least 2 CPU seconds...

  assigner:  0 wallclock secs ( 2.06 usr +  0.02 sys = 2.08 CPU) @ 384577.33/s
(n=800690)
    direct:  3 wallclock secs ( 2.04 usr +  0.00 sys = 2.04 CPU) @ 629222.22/s
(n=1285501)
   shifter:  2 wallclock secs ( 2.09 usr +  0.00 sys = 2.09 CPU) @ 294563.31/s
(n=616521)
             Rate  shifter assigner   direct
shifter  294563/s       --     -23%     -53%
assigner 384577/s      31%       --     -39%
direct   629222/s     114%      64%       --