Hi Joern,

Here are some benchmark results.  Following your advice, I took the
arith-rand test, increased its main loop count until it took around
10 seconds to run on my test machine, and tested it against the eight
optimization combinations that are tested for in the gcc torture test
[see methodology notes attached]


I found that my change increased the runtime by 1.5 to 2 percent
(even when I added the new instructions that I'm working on).
That didn't seem too bad to me, but I took some advice from Alex
Oliva and tried simply changing the sh_jmp_table from char to short.
This much simpler change increased the runtime by only 0.5 to 1
percent, at the cost of 64k more data space.

So I'll withdraw my previous patch and submit the following instead: