[CLUE-Tech] Curious about GCC -O3

[Ed Hill]

On Thu, 2002-04-25 at 09:59, Matt Gushee wrote:
> I have a question about the GCC optimization flags. I remember that
> as recently as a couple of years ago, 'gcc -O3' was supposed to be
> be buggy, thus -O2 was the most common setting on most or all Linux
> distros. But I've gotten the impression more recently that -O3 is now
> safe to use in most cases; at any rate, I now compile most applications
> with -O3, and have not found it to cause any problems. So why is -O2
> still the default?


Hi Matt,

According to the manual, -O3 is equal to "-O2 -finline-functions".
I've used -O3 on occasion and had no problems.  I've also seen *no*
significant improvement in execution speed for -O3 versus -O2.

Have you ever run across a code where that optimization did give an
appreciable speed-up?  I'd guess that the occasions are rare...

Ed


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Edward H. Hill III, PhD
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