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Re: About g++ optimization


From: Allan Wind
Subject: Re: About g++ optimization
Date: Thu, 30 Mar 2006 17:01:43 -0500
User-agent: Mutt/1.5.9i

On 2006-03-30T12:30:30-0800, PengYu.UT@gmail.com wrote:
> for(int i = 0; i < f(n); ++ i) {
> ...
> }

Make sure you remove the space between ++ and i.

> If I have the above "for" statement and I compile it with -O3, will the
> function "f(n)" be optimized such that f(n) will only be evaluated
> once. Or I have to factor "f(n)" outside the loop to make sure that it
> only be evaluated once?

If you compile you example with -S then the assembler file (.s) will
tell you.


/Allan

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