On Thu, Mar 14, 2019 at 03:07:53PM +0000, Patrick Bellasi wrote:

On 14-Mar 14:32, Peter Zijlstra wrote:

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On Thu, Mar 14, 2019 at 12:13:15PM +0000, Patrick Bellasi wrote:

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I'd be most impressed if they pull this off. Check the generated code
and see I suppose :-)

On x86 the code generated looks exactly the same:

   https://godbolt.org/z/PjmA7k

Argh, they do mult by inverse to avoid the division, and can do this
because its a constant.

And then yes, your arm version looks worse.

your "arm version" is worst then x86, or "your version" is worse?

IOW, should I keep the code as the original? Do you prefer your
version? Or... we don't really care...

Yeah, keep the original, it didn't matter on x86 and arm regressed with
my version.

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It does what I expected with -Os, but as Rutland said the other day,
that stands for Optimize for Sadness.

Yes, I guess we cannot optimize for all flags... however, just let me
know what you prefer and I'll put that version in ;)

Yeah, don't bother optimizing for -Os, it generally creates atrocious
crap, hence Rutland calling it 'Optimize for Sadness'.