I am using ARMv8 GCC compiler and I would like to optimize Neon Intrinsics code for better execution time performance. I have already tried loop unrolling and I am using look up table for the computation of log10. Any ideas?
Here is the code:
static inline void func(float32x4x4_t inputData_real, float * outputs ) { float32x4x4_t outputData; float32x4x4_t outputData1; for(unsigned short i =0; i < 4; i++) { outputData.val[i] = vmulq_f32 (inputData_real.val[i], inputData_real.val[i]); outputData1.val[i] = vmlaq_f32 (outputData.val[i], inputData_imag.val[i], inputData_imag.val[i]); outputs[i] = 10.0F * log10f_c(vaddvq_f32(outputData1.val[i]) + (a_imagvalue[i] * b_imagvalue[i]) + (a_realvalue[i] * b_realvalue[i])) - 7.89865767467723; } }
There are "memory hint" instruction, which tell the memory subsystem to preload some memory you will access soon. So while calculating the first chunk, the next will be loaded into cache.
I do not know the instruction by heart.