unroll-loops - Is it always safe?
kline at tao.thought.org
Thu Apr 5 15:41:52 UTC 2007
On Thu, Apr 05, 2007 at 09:54:08AM -0300, scuba at centroin.com.br wrote:
> Hi All,
> Is it always safe to use "-funroll-loops" as a flag to
> /etc/make.conf ? Does it realy improve the compiled programs?
> When should I avoid to use it?
If you are using gcc42 -funroll-loops can be a win. gcc3.x
is less savvy about knowing the limits of complexity to unroll
which loops. I'm doing some tests with gcc34 (default) and
gcc42. The latter can yield significant improvements iff
you know what you're doing. It's no magic bullet.
> - Marcelo
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Gary Kline kline at thought.org www.thought.org Public Service Unix
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