On Tue, Nov 12, 2013 at 02:48:46PM +0400, Sergey Ostanevich wrote:
> You are right regarding the cost model if we talk about vectorizer alone.
> But the #pragma omp simd goes beyond the vectorizer - it introduces
> parallel context in a place user defines, similar to #pragma omp parallel.
> Are we applying any cost model for omp parallel region?
>
> You can consider this pragma as a helper for developer for 'easily'
> introduce parallelism in his code, hence any type of cost model -
> whatever quality it is - will plays against this paradigm, forcing user
> to play around our cost model to let it make the loop simd-parallel.
So what do other compilers do here? Does icc also totally ignore all
cost analysis for #pragma omp simd or #pragma simd and vectorizes even when
it would be obviously undesirable?
Jakub
