Re: What are the best gcc optimization options for Pentium 200 MMX

[Ville-Pertti Keinonen]

[EMAIL PROTECTED] (Kris Kennaway) writes:

> Can you say "gimmick"? :-) gcc often produces demonstrably broken code for
> optimisation levels higher than -O.

That -O is safe seems to be a persistent myth.  GCC also produces
broken code for -O and no optimization in some cases, sometimes while
producing working code for higher optimization levels...  I wouldn't
state e.g. that -O2 produces broken code any more often than -O, this
may have been true for version X.Y.Z but is certainly not universally
true.

I believe that the reasons the FreeBSD build uses -O are the fact that
especially with older versions of gcc, -O2 slowed down compilation
considerably for little noticable performance improvement (as for -O3,
automatic inlining is generally undesirable), and it is always best to
only have to test the system with a single set of flags.


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