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Re: [RFC] Enabling loop unrolls at -O3?
Steven Bosscher wrote:
One reason why it's not enabled is because it causes a huge compile time
regression.
For the majority of Ada applications, as opposed to specific bench marks,
we see little gain in -O2 over -O1 in any case, although that's for GCC 3.4
and it is always possible that GCC 4 is qualitatively different in this
respect (I doubt it, optimizations are always less significant in real
applications than you hope). Thus -O1 seems the general
best choice if compile time is an issue. I think it is reasonable to
figure that -O2 means I want good performance regardless of compile time.
I guess the issue is what does "huge" mean, it is hard to discuss based
on loaded adjectives taking the place of data :-)