Optimizations

Marc Lehmann pcg@goof.com
Sun Dec 14 15:14:00 GMT 1997


On Sun, Dec 14, 1997 at 02:34:36PM +0100, Philipp Thomas wrote:
> Marc Lehmann wrote:
> > -fschedule-insns is a *loss* on x86 cpu's!
> 
> care to explain why it is a loss (and most probably also -fschedule-insns2)
> ?

AFAIR -fschedule-insns (as opposed to -fschedule-insns2) is normally a loss
sicne the first scheduling pass is done before register allocation, so the
register pressure increases and local/global get's problems. (for fpu code
it _could_ be beneficial, though).

the second scheduling pass is done after register allocation, so no
"new" hardware registers are created.

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      ---==---(_)__  __ ____  __       Marc Lehmann       +--
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