Port of i386 low-hanging fruit optimizations

[toxieainc]

Hi! As part of getting the Pinball 2000 platform up and running, we use MAMEs i386 implementation here: https://github.com/vpinball/pinmame/tree/master/src/p2k/mame/cpu/i386

I did some small optimizations there, that led to rather large speedups in the end though (at least for that platform), allowing us to clock the MediaGX from previously 20MHz up to the real 233MHz (needs a beefy machine though, on mid-end machines ~80MHz runs okay).
Its boils down to a bit more inlining, and changing the layout of the class members to exploit cache lines much better.
(On top we have a shortcut for some memory areas, that's the more involved part that would be harder to generalize i fear, but still its rather simple)

Maybe someone wants to have a look if porting (some of) these changes to MAME is okay/feasible?

[rb6502]

Can you point us to some change lists on your end where you did the speedups so we can see them more clearly?

[toxieainc]

You could just use the whole directory of PinMAMEs i386 and put it into a current MAME checkout and diff. Its really not that much, and the cacheline and inline changes are minimalistic.
I also don't know how all of that generalizes, but as said, for Pin2K the sum of it all was dramatic. But the initial benefit came from the fast mem access windows, and then the other things became the bottleneck, so i don't know if the cacheline and inline changes alone will be as dramatic for MAME/other machines.