how to enable atomicAdd for float?

I have been using an atomicFloatAdd() function from the following thread:

http://forums.nvidia.com/index.php?showtop…mp;#entry380935

now Fermi has the native atomicAdd for floats, is there a preprocessor (macro) so that I can use the native function when compiling my code for a Fermi?

Also, is there a way to do this at the run-time? I mean when running the kernel, if it sees a Fermi, it uses the native atomic function, otherwise, use the hacked version?

thanks

a second question:

when I compile a cu unit with nvcc -arch=sm_11, sm_12,…,sm_20, is there a corresponding macro that I can use inside the cu unit to tell me which gpu-arch that I am compiling against?

never mind, I used nvcc -v to get the defined macros.