On Mon, Feb 8, 2010 at 2:05 AM, Yue K. Li <yue.kevin.li@xxxxxxxxx> wrote: > Hi, John, > > On Wed, Feb 3, 2010 at 6:32 AM, John (Eljay) Love-Jensen > <eljay@xxxxxxxxx> 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. Cheers, Yue