Re: Optimizations

[Marc Lehmann <pcg@goof.com>]

On Sun, Dec 14, 1997 at 05:30:48PM -0500, meissner@cygnus.com 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)
> 
> The problem is that -fschedule-insns, -funroll-{,all-}loops, and
> -fstrength-reduce all tend to work by creating more registers to hold

The really intersting point is that -fschedule-insns ins generally a loss
on x86, while -funroll-all-loops is generally a win! (even more
so that -funroll-loops)

I guess loop unrolling should be more clever, i.e. while it should
unroll loops without constant number ofm iterations, it should'nt
unroll all of them.

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