Option -xcore-avx2

Hello everyone!

I'm using ICC version 2016.1.150. I found some drawbacks when compiling for processors endowed with AVX2. When compiling with O0 and -xcore-avx2, code runs without problems. However, when compiling with O1 and -xcore-avx2, code runs, but presents a wrong result.

Furthermore, when compiling with O1 (O2 or O3) and -xavx, code produces a right result. In other words, I think ICC is producing an optimized assembly code that affects program execution behavior and, consequently, the final result.

At last, I tested with GCC 4.8.2 and did not find any problem when compiling with -mavx2 and O3.

Thanks!