Compiling AVX2 program on Mavericks

Question

I try to compile a dummy AVX2 program on my Mac OS 10.9 with gcc version 4.9.0 20131201

//dummy program
#include <immintrin.h> // AVX2
#include <stdio.h>
int main(int argc, char* argv[]) {
   __m256i reg =  _mm256_set1_epi8(1);
   __m256i result = _mm256_max_epu8(reg,reg);
   printf("%d",((int *)&result)[0]);
}

I used this command to compile

gcc -mavx -O0 test.C

and I get this error

In function 'int main(int, char**)':
avx2intrin.h:373:1: 
error: inlining failed in call to always_inline 
'__m256i _mm256_max_epu8(__m256i, __m256i)': target specific option mismatch
 _mm256_max_epu8 (__m256i __A, __m256i __B)

The _mm256_max_epu8 uses an always_inline attribute. Is this the problem?

I also get the problem if I compile with O3.

What am I doing wrong?

Answer 1

To compile for a target with AVX2, use -mavx2.

Answer 2

I can compile the program with

g++ -mavx2 -Wa,-q test.C

In this thread is discussed why -Wa,q is also needed