[issue4753] Faster opcode dispatch on gcc

[Paolo 'Blaisorblade' Giarrusso]

Paolo 'Blaisorblade' Giarrusso <p.giarrusso at gmail.com> added the comment:

@ ajaksu2
> Applying your patches makes no difference with gcc 4.2 and gives a
> barely noticeable (~2%) slowdown with icc.
"Your patches" is something quite unclear :-)
Which are the patch sets you are comparing?
And on 32 or 64 bits? But does Yonah supports 64bits? IIRC no, but I'm
not sure.
I would be surprised from slowdowns for restore-old-oparg-load.diff,
really surprised.
And I would be just surprised by slowdowns on
reenable-static-prediction.diff.
Also, about ICC output, we still need to ensure that it's properly
compiled (see above the instructions for counting "jmp *" or similar).
In the measurements above, ICC did miscompile the patch with the switch.
By "properly compiled" I mean that separate indirect branches are
generated, instead of just one.

> These results are from a
> Celeron M 410 (Core Solo Yonah-based), so it's a rather old platform to
> run benchmarks on.

Not really - at the very least we should listen to results on Pentium 4,
Core (i.e. Yonah) and Core 2, and I would also add Pentium3/Pentium M to
represent the P6 family.
Anyway, I have to do my benchmarks on this, I hope this weekend I'll
have time.

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