[ros-users] Question about cmake and SSE optimizations
Rosen Diankov
rosen.diankov at gmail.com
Tue Mar 23 19:11:54 UTC 2010
awesome work with sse3 jose! i just checked it on a non-sse3 cpu and
it behaves as expected.
i agree with radu that we should go with the highest sse available,
however you have to be very careful when distributing binaries
(especially now that ros has debian releases). i'm not sure what would
be the appropriate way to distribute packages compiled with no-sse,
sse1 only, sse1-2 only, etc. in another, more simpler project i was
in, we ended up having one executable for every setting..... for
sse-optimized math libraries, these checks are actually done during
runtime, so they can support multiple sse versions without dealing
with this problem
rosen,
2010/3/23 Jose Gonzalez <de0a100 at gmail.com>:
> Here is the version I got with SSE3 (I'm not familiar with MSVC so I
> didn't include it)
>
> # check for SSE extensions
> include(CheckCXXSourceRuns)
> if( CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX )
> set(SSE_FLAGS)
>
> set(CMAKE_REQUIRED_FLAGS "-msse3")
> check_cxx_source_runs("
> #include <pmmintrin.h>
>
> int main()
> {
> __m128d a, b;
> double vals[2] = {0};
> a = _mm_loadu_pd(vals);
> b = _mm_hadd_pd(a,a);
> _mm_storeu_pd(vals, b);
> return 0;
> }"
> HAS_SSE3_EXTENSIONS)
>
> set(CMAKE_REQUIRED_FLAGS "-msse2")
> check_cxx_source_runs("
> #include <emmintrin.h>
>
> int main()
> {
> __m128d a, b;
> double vals[2] = {0};
> a = _mm_loadu_pd(vals);
> b = _mm_add_pd(a,a);
> _mm_storeu_pd(vals,b);
> return 0;
> }"
> HAS_SSE2_EXTENSIONS)
>
> set(CMAKE_REQUIRED_FLAGS "-msse")
> check_cxx_source_runs("
> #include <xmmintrin.h>
> int main()
> {
> __m128 a, b;
> float vals[4] = {0};
> a = _mm_loadu_ps(vals);
> b = a;
> b = _mm_add_ps(a,b);
> _mm_storeu_ps(vals,b);
> return 0;
> }"
> HAS_SSE_EXTENSIONS)
>
> set(CMAKE_REQUIRED_FLAGS)
>
> if(HAS_SSE3_EXTENSIONS)
> message(STATUS "Using SSE3 extensions")
> set(SSE_FLAGS "-msse3 -mfpmath=sse")
> elseif(HAS_SSE2_EXTENSIONS)
> message(STATUS "Using SSE2 extensions")
> set(SSE_FLAGS "-msse2 -mfpmath=sse")
> elseif(HAS_SSE_EXTENSIONS)
> message(STATUS "Using SSE extensions")
> set(SSE_FLAGS "-msse -mfpmath=sse")
> endif()
>
> add_definitions(${SSE_FLAGS})
> elseif(MSVC)
> check_cxx_source_runs("
> #include <emmintrin.h>
>
> int main()
> {
> __m128d a, b;
> double vals[2] = {0};
> a = _mm_loadu_pd(vals);
> b = _mm_add_pd(a,a);
> _mm_storeu_pd(vals,b);
> return 0;
> }"
> HAS_SSE2_EXTENSIONS)
> if( HAS_SSE2_EXTENSIONS )
> message(STATUS "Using SSE2 extensions")
> add_definitions( "/arch:SSE2 /fp:fast -D__SSE__ -D__SSE2__" )
> endif()
> endif()
>
> On Tue, Mar 23, 2010 at 2:24 PM, Radu Bogdan Rusu <rusu at willowgarage.com> wrote:
>> In terms of SSE only, we can safely go to the highest SSE version available.
>>
>> Brian Gerkey wrote:
>>> It would be great to see this functionality wrapped up in a single
>>> CMake macro, something like:
>>> rosbuild_add_sse_flags(target)
>>> It would do checks, compute flags, then call
>>> rosbuild_add_compile_flags(target ...). Of course, this assumes that
>>> you want the highest / best level of SSE available; I'm not familiar
>>> enough with these optimizations to know if that's appropriate, or if
>>> you'd rather have finer-grained control.
>>>
>>> I'd happily add such a macro to rosbuild, for general reuse. Come to
>>> think of it, this would be a nice module to contribute to CMake
>>> itself.
>>>
>>> brian.
>>>
>>> On Tue, Mar 23, 2010 at 11:14 AM, Radu Bogdan Rusu
>>> <rusu at willowgarage.com> wrote:
>>>> Great job Rosen! That's exactly what I had in mind.
>>>>
>>>> We should add SSE3 and SSE4. Gotta love that dot product :)
>>>>
>>>> Cheers,
>>>> Radu.
>>>>
>>>> Rosen Diankov wrote:
>>>>> i'm pasting cmake code i use for sse checks. it checks for both sse1
>>>>> and sse2, although similar checks can be used for sse3-5, there's also
>>>>> a check for msvc
>>>>>
>>>>> # check for SSE extensions
>>>>> include(CheckCXXSourceRuns)
>>>>> if( CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX )
>>>>> set(SSE_FLAGS)
>>>>>
>>>>> set(CMAKE_REQUIRED_FLAGS "-msse2")
>>>>> check_cxx_source_runs("
>>>>> #include <emmintrin.h>
>>>>>
>>>>> int main()
>>>>> {
>>>>> __m128d a, b;
>>>>> double vals[2] = {0};
>>>>> a = _mm_loadu_pd(vals);
>>>>> b = _mm_add_pd(a,a);
>>>>> _mm_storeu_pd(vals,b);
>>>>> return 0;
>>>>> }"
>>>>> HAS_SSE2_EXTENSIONS)
>>>>>
>>>>> set(CMAKE_REQUIRED_FLAGS "-msse")
>>>>> check_cxx_source_runs("
>>>>> #include <xmmintrin.h>
>>>>> int main()
>>>>> {
>>>>> __m128 a, b;
>>>>> float vals[4] = {0};
>>>>> a = _mm_loadu_ps(vals);
>>>>> b = a;
>>>>> b = _mm_add_ps(a,b);
>>>>> _mm_storeu_ps(vals,b);
>>>>> return 0;
>>>>> }"
>>>>> HAS_SSE_EXTENSIONS)
>>>>>
>>>>> set(CMAKE_REQUIRED_FLAGS)
>>>>>
>>>>> if(HAS_SSE2_EXTENSIONS)
>>>>> message(STATUS "Using SSE2 extensions")
>>>>> set(SSE_FLAGS "-msse2 -mfpmath=sse")
>>>>> elseif(HAS_SSE_EXTENSIONS)
>>>>> message(STATUS "Using SSE extensions")
>>>>> set(SSE_FLAGS "-msse -mfpmath=sse")
>>>>> endif()
>>>>>
>>>>> add_definitions(${SSE_FLAGS})
>>>>> elseif(MSVC)
>>>>> check_cxx_source_runs("
>>>>> #include <emmintrin.h>
>>>>>
>>>>> int main()
>>>>> {
>>>>> __m128d a, b;
>>>>> double vals[2] = {0};
>>>>> a = _mm_loadu_pd(vals);
>>>>> b = _mm_add_pd(a,a);
>>>>> _mm_storeu_pd(vals,b);
>>>>> return 0;
>>>>> }"
>>>>> HAS_SSE2_EXTENSIONS)
>>>>> if( HAS_SSE2_EXTENSIONS )
>>>>> message(STATUS "Using SSE2 extensions")
>>>>> add_definitions( "/arch:SSE2 /fp:fast -D__SSE__ -D__SSE2__" )
>>>>> endif()
>>>>> endif()
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> 2010/3/24 Jose Gonzalez <de0a100 at gmail.com>:
>>>>>> Thanks for the comments?
>>>>>>
>>>>>> What about check_cxx_compiler_flag("-msse2" COMPILER_SUPPORT_SSE2)?
>>>>>> Have you ever tried it?
>>>>>>
>>>>>> On Tue, Mar 23, 2010 at 12:16 PM, Radu Bogdan Rusu
>>>>>> <rusu at willowgarage.com> wrote:
>>>>>>> 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/
>>>>>>> _______________________________________________
>>>>>>> ros-users mailing list
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>>>>>>>
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>>>>>>
>>>> --
>>>> | Radu Bogdan Rusu | http://rbrusu.com/
>>>> _______________________________________________
>>>> ros-users mailing list
>>>> ros-users at code.ros.org
>>>> https://code.ros.org/mailman/listinfo/ros-users
>>>>
>>
>> --
>> | Radu Bogdan Rusu | http://rbrusu.com/
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