Hi all, When vectorizing some of my integer code, I had this "Illegal instruction" problem with SIMD intrinsics in GCC. I believe the error is triggered by the instruction: _mm_store_si128((__m128i *)c, v2); where C and v2 are defined as: int c[4] __attribute__((aligned(16))) = {0, 0, 0, 0}; __m128i v2; And the CFLAGS is -I/usr/local/papi-3.6.1/include -L/usr/local/papi-3.6.1/lib/ -lpapi -lm -O2 -msse4.1 -fno-inline-small-functions I searched around when starting with SIMD intrinsics, and didn't find a complete instruction set for GCC. So I end up using something similar from MSDN. What's the legal intrinsic function in GCC to store a __m128i vector back to an integer array? Thanks, LC