Depending on what compiler and cpu you use, some of these flags might be already turned on by default. You can check 
that using:

$ gcc -Q -O3 --help=target

for example.

Other than that, we don't have a proper way to enable/disable different SSE optimizations for now. Most ROS packages 
cram a add_definitions ("-msse... etc") in their CMakeLists.txt.

Patches to make this more standard across multiple platforms and enable/disable SSE1-5 automatically would be great!

Cheers,
Radu.

Jose Gonzalez wrote:
> Hi,
> 
> Doing some experiments in the past with OpenCV (linux/g++) I realized
> that there is a significant performance difference between the
> versions compiled with autoconf and cmake. Digging in the compilation
> scripts I came to the conclusion that the only extra flags that were
> added by the autoconf scripts were the SSE optimizations (and openMP).
> 
> Talking about the SSE optimizations, I can see how ROS sets the flags
> in a similar way. When the detected platform is i686, all the SSE
> optimizations are disabled by default (there is a comment "SSE/SSE2
> might probably be not available for some old AMD or VIA processors").
> Before finding out a solution by myself I'd like to ask the list if
> somebody knows a standard way of testing for SSE optimizations in
> cmake.
> 
> Thanks,
> Jose
> 
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| Radu Bogdan Rusu | http://rbrusu.com/