the influence from the option -no-vec -no-simd

[dingjun_chencmgl_ca]

HI, Could someone tell me the differences between compiler option -no-vec and -no-simd?

Do I have to use both options to disable auto-vectorization from the Intel Compiler for some specific files?

If I just use one option, such as  -no-vec, in terms of Intel Fortran compiler manual, the default option is still to enable SIMD vectorization. I am confused about these 2 options and why are there 2 compiler options for auto-vectorization?

Thanks and I look forward to your response.

[TimP]

-no-vec turns off auto-vectorization in plain source code with no simd directives.

-no-simd in effect removes the effect of simd directives; otherwise -no-vec doesn't apply within the scope of those directives.

Now that there are omp simd directives as well, which are put into effect by either -qopenmp or -qopenmp-simd directives (spelled without the q in past compilers), this adds another similar category to consider.