Diagnostic 15021: loop was not vectorized: #pragma novector used

Cause:

This diagnostic message is emitted when #pragma novector is used explicitly on a loop. Below is an example for this scenario:

Example:
 

void foo(float *A, int n){
  int i;
#pragma novector
  for(i=0;i<n;i++){
    A[i] = i;
  }
}


$ icpc -c example28.cc -vec-report2
example28.cc(4): (col. 3) remark: loop was not vectorized: #pragma novector used

Recommendation:

Not using this pragma will enable the compiler heuristics to analysis if the loop is an apt candidate for vectorization.

For more complete information about compiler optimizations, see our Optimization Notice.