g++ optimizer report?

Yue K. Li yue.kevin.li@gmail.com
Mon Feb 8 10:47:00 GMT 2010

On Mon, Feb 8, 2010 at 2:05 AM, Yue K. Li <yue.kevin.li@gmail.com> wrote:
> Hi, John,
> On Wed, Feb 3, 2010 at 6:32 AM, John (Eljay) Love-Jensen
> <eljay@adobe.com> wrote:
>> Hi Yue,
>> You can get a list of toggle-able optimization flags like this:
>> touch Empty.cpp
>> gcc -O2 -fverbose-asm -S Empty.cpp -o O2.s
>> gcc -O3 -fverbose-asm -S Empty.cpp -o O3.s
>> However, that will not tell you what non-toggle-able optimizations are enabled, since -O2 enables many optimizations that are not controlled by command line flags.  And -O3 enables a few more, as I understand it.
>  This is interesting, and works.
>> Nor will that tell you what optimization(s) were applied to a particular code segment.
     I think it would be great if gcc/g++ will have this kind of
optimization report feature, it would be very helpful for doing
performance analysis.



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