In file included from ../eigen/Eigen/Core:293:0, from ../eigen/Eigen/Dense:1, ../eigen/Eigen/src/Core/arch/NEON/PacketMath.h:55:45: error: missing binary operator before token "(" #if (defined(__has_builtin) && __has_builtin(__builtin_prefetch)) || defined(__GNUC__) I am using arm-linux-gcc 4.8.
According to http://stackoverflow.com/questions/25584920/how-to-fix-error-in-eigen-for-arm-neon , this is the same issue as discussed on the mailing list in the thread starting at http://listengine.tuxfamily.org/lists.tuxfamily.org/eigen/2013/11/msg00011.html , but it looks like the solution proposed by Christoph in http://listengine.tuxfamily.org/lists.tuxfamily.org/eigen/2013/11/msg00048.html was never acted on. Time to revisit this?
I modified PacketMath.h according to msg00048, and it did pass compiling. However, the output assembly code was not as I expected. Example code: Eigen::Vector4f X, Y; // X = ... // Y = ... X = X + Y; There were four fadds instead of one vadd. (In reply to Jitse Niesen from comment #1) > According to > http://stackoverflow.com/questions/25584920/how-to-fix-error-in-eigen-for- > arm-neon , this is the same issue as discussed on the mailing list in the > thread starting at > http://listengine.tuxfamily.org/lists.tuxfamily.org/eigen/2013/11/msg00011. > html , but it looks like the solution proposed by Christoph in > http://listengine.tuxfamily.org/lists.tuxfamily.org/eigen/2013/11/msg00048. > html was never acted on. Time to revisit this?
I applied the needed changes: https://bitbucket.org/eigen/eigen/commits/7829fa7c91cf/ https://bitbucket.org/eigen/eigen/commits/e6b961139761/ @phil.wang, make sure you compiled with neon enabled, for instance with "-mfpu=neon -mcpu=cortex-a8".
I have a file name eigen-neon-example.cpp: https://gist.github.com/Phillip-Wang/f729b26ab61dadc2a865 I compile it with arm-linux-gcc, with flags "-mfpu=neon -mcpu=cortex-a8". Output assembly shows that addition between Eigen::Vector4f has not been parallelized.
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