New register allocator branch created

[Daniel Berlin]

On Sun, 28 Jan 2001 dewar@gnat.com wrote:

> Indeed the improvement from this example is impressive!
>

Thanks. Well, thank Appell and George, and Briggs, etc. I just implemented
their ideas (plus a few others).

I actually find it odd that we do so badly in examples like that.
It makes me wonder if we do the same thing for C++ code. If we do, and
it's spilling link registers like that, all the time, it must *really*
kill virtual function performance, among other things.

I wonder how much performance we lose due to the register allocator
spilling so much. We do all these nice optimizations, and a lot of the
effects probably get negated by having to throw a lot of stuff back in
memory.


(I'll benchmark using spec as soon as i stop laughing about reload and the
reg-rename pass fighting it out. We say to put something in register 0,
reload moves it to register 8, reg rename moves it to 0. Duh.)

--Dan