🚀 go-pugleaf

In article <QAIBQ2@xds13.ferranti.com>, peter@ficc.ferranti.com (peter da silva) writes:
|> [...]
|> But the question isn't whether you can do these operations in software
|> anywhere near as fast as they can be done in hardware, but rather whether
|> they can be done fast enough. That is, how much faster would applications
|> that make heavy use of these instructions run if you sped them up by a
|> factor of 10 (which is about what I would have guessed the speed difference
|> to be)? If you speed up 3% of the program by a factor of 10, it's pretty
|> much lost in the noise.

Exactly so.  The only thing I was saying is that the software mechanisms
are _not_ done "quite quickly" compared to a hardware implementation of
the same thing.  Whether is is worthwhile to put an instruction into the
hardware is dependent on two things: 1) the commonality of the operation,
and 2) the amount by which the hardware is faster.  Sean Fagan was claiming
the the speedup was insignificant - it isn't.  Now, if you want to claim
the instruction is rarely needed, that's a completely different issue.
It also depends on two things: a) what is the application domain, and 
b) what features _are_ present in the hardware (individual instructions
cannot be selected in isolation from the rest of the instruction set).

J. Giles