error: inlining failed to call always_inline

Question

I am trying to implement and code on some files, some of which contain SIMD-calls. I have compiled this code on a server, running basically the same OS as my machine, yet i cant compile it.

This is the error:

make
g++ main.cpp -march=native -o main -fopenmp
In file included from /usr/lib/gcc/x86_64-linux-gnu/7/include/immintrin.h:53:0,
                 from tensor.hpp:9,
                 from main.cpp:4:
/usr/lib/gcc/x86_64-linux-gnu/7/include/avx512vlintrin.h: In function ‘_ZN6TensorIdE8add_avx2ERKS0_._omp_fn.5’:
/usr/lib/gcc/x86_64-linux-gnu/7/include/avx512vlintrin.h:447:1: error: inlining failed in call to always_inline ‘__m256d _mm256_mask_add_pd(__m256d, __mmask8, __m256d, __m256d)’: target specific option mismatch
 _mm256_mask_add_pd (__m256d __W, __mmask8 __U, __m256d __A,
 ^~~~~~~~~~~~~~~~~~
In file included from main.cpp:4:0:
tensor.hpp:228:33: note: called from here
         res = _mm256_mask_add_pd(tmp, 0xFF, _mm256_mask_loadu_pd(tmp, 0xFF, &elements[i]), _mm256_mask_loadu_pd(tmp, 0xFF, &a.elements[i]));
               ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/lib/gcc/x86_64-linux-gnu/7/include/immintrin.h:53:0,
                 from tensor.hpp:9,
                 from main.cpp:4:
/usr/lib/gcc/x86_64-linux-gnu/7/include/avx512vlintrin.h:610:1: error: inlining failed in call to always_inline ‘__m256d _mm256_mask_loadu_pd(__m256d, __mmask8, const void*)’: target specific option mismatch
 _mm256_mask_loadu_pd (__m256d __W, __mmask8 __U, void const *__P)
 ^~~~~~~~~~~~~~~~~~~~
In file included from main.cpp:4:0:
tensor.hpp:228:33: note: called from here
         res = _mm256_mask_add_pd(tmp, 0xFF, _mm256_mask_loadu_pd(tmp, 0xFF, &elements[i]), _mm256_mask_loadu_pd(tmp, 0xFF, &a.elements[i]));
               ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/lib/gcc/x86_64-linux-gnu/7/include/immintrin.h:53:0,
                 from tensor.hpp:9,
                 from main.cpp:4:
/usr/lib/gcc/x86_64-linux-gnu/7/include/avx512vlintrin.h:610:1: error: inlining failed in call to always_inline ‘__m256d _mm256_mask_loadu_pd(__m256d, __mmask8, const void*)’: target specific option mismatch
 _mm256_mask_loadu_pd (__m256d __W, __mmask8 __U, void const *__P)
 ^~~~~~~~~~~~~~~~~~~~
In file included from main.cpp:4:0:
tensor.hpp:228:33: note: called from here
         res = _mm256_mask_add_pd(tmp, 0xFF, _mm256_mask_loadu_pd(tmp, 0xFF, &elements[i]), _mm256_mask_loadu_pd(tmp, 0xFF, &a.elements[i]));
               ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Makefile:7: recipe for target 'main' failed
make: *** [main] Error 1

Googling the problem didnt really help, as all answers pointed things out, i allready do/tried.

Can somebody provide some background as to why it doesn´t work.

EDIT:

int main(){
#ifdef __AVX512F___
    auto tt = createTensor();
    auto tt2 = createTensor();
    auto res = tt.addAVX512(tt2);
#endif
}

//This is in tensor.hpp
#ifdef __AVX512F__
Tensor<T> Tensor::addAVX512(_param_){
   res = _mm256_mask_add_pd(tmp, 0xFF, _mm256_mask_loadu_pd(tmp, 0xFF, &elements[i]), _mm256_mask_loadu_pd(tmp, 0xFF, &a.elements[i]));
}
#endif

This it the gist of what happens ... i have encased all SIMDcalls in #ifdefs, etc.

Answer 1

GCC will only let you use intrinsics for instruction sets that are enabled for the compiler to use. e.g. a related question about an AVX1 intrinsic: inlining failed in call to always_inline '__m256d _mm256_broadcast_sd(const double*)'

---

These are _mask_ versions of 256-bit intrinsics, they require AVX512VL.

(My comments under the question about -mavx were wrong, I didn't notice the _mask in the name or args, just the _mm256.)

You're probably compiling on KNL (Knight's Landing / Xeon Phi) on your server, which has AVX512F but not AVX512VL. So -march=native will set -mavx512f. (Unlike Skylake-AVX512 which does have AVX512VL allowing use of cool new AVX512 stuff like masked instructions with narrower vectors.)

And you've found a bug in your tensor.hpp, where you use AVX512VL intrinsics after only checking for __AVX512F__ instead of __AVX512VL__. AVX512-anything implies 512F, so it doesn't need to check both.

#ifdef __AVX512F__    // should be __AVX512VL__
Tensor<T> Tensor::addAVX512(_param_){
   res = _mm256_mask_add_pd(tmp, 0xFF, _mm256_mask_loadu_pd(tmp, 0xFF, &elements[i]), _mm256_mask_loadu_pd(tmp, 0xFF, &a.elements[i]));
}
#endif

This is just pointless, you don't need to use the masked versions of these intrinsics if you're going to use constant all-ones masks. Use _mm256_add_pd like a normal person and only check for __AVX__. Or use _mm512_add_pd.

I thought at first this was from TensorFlow, but (from your comments) that doesn't make sense. And it can't be that badly written. Merge-masking into 3 copies of the same tmp with an all-true mask just makes no sense; it looks like a silly way to introduce a false dependency if the compiler can't optimize away the mask=all-ones into an unmasked load.

And also terrible C++ style: you have a variable called __m256d tmp as a global or class member?? It's not even a local dummy variable, it may exist somewhere the compiler can't fully optimize it away.