[virtmach] switch vs dispatch table (was Your VM)

[Thomas Fjellstrom]

Thaddaeus Frogley wrote:
> 
> > Many compilers will generate an indirect jump through a
> > table of pointers for a dense switch.  Generally, the
> > compiler can generate better code for this internally
> > than can be written in source code, so the switch version
> > is likely to be faster.
> 
> Most compilers will generate a range check before the jump, where as a hand
> coded jump table can assume that the data is in range.  Of course, its very
> hard to say, as we haven't even mentioned what language this VM might be
> implemented in...
> 

Personally I was thinking about C and gcc when I asked the question...

-- 
"Computer programmers don't byte, they nybble a bit."
Thomas Fjellstrom
tfjellstrom@home.com
http://strangesoft.net/