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Re: -O* Gives Different Results than Individual Optimizations?
And what's the purpose of that?
Alexey
On 10/12/09, Kevin P. Fleming <kpfleming@digium.com> wrote:
> Mike Sullivan wrote:
>>> There was another interesting question in that mail: is "-O1" flag
>>> something different from just combination of "-fsomething" flags?
>>
>> This really is the question I'm interested in. The problem itself was
>> fixed, I just don't understand why applying the same optimizations
>> (and more) which make up -O1 don't elicit the same behavior.
>
> This is frequently asked on this list, and the answer is always the
> same: yes, the -O<N> flag does more than just enable a series of -f<foo>
> flags. Said another way, there are optimizations that do *not* have
> -f<foo> flags that control them, they are enabled by directly checking
> the value supplied to the -O flag, and they cannot be directly controlled.
>
> --
> Kevin P. Fleming
> Digium, Inc. | Director of Software Technologies
> 445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
> skype: kpfleming | jabber: kpfleming@digium.com
> Check us out at www.digium.com & www.asterisk.org
>