c++ - Does using -parallel or (and) -vec will make our program run faster? -

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i'm using linux & intel compiler (c/c++).

my code not use cilkplus or openmp. read following article : auto-parallelization overview

and i'm confused:

  1. if i'm not using openmp (or cilkplus) , compile program "-parallel" (auto-parallelizer) , "-vec" (auto-vectorization), program run faster (because compiler break serial code parallel code ?)
  2. if (it run faster), why not default option ? (why not use flags ) ?

thanks

intel uses such techniques loop unwinding, task decomposition & etc parallel code. these techniques make program run faster problem may occurred when program faces race condition, deadlock, tasks done priority , .... can not used default.


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