Visible to Intel only — GUID: GUID-CFBEC461-748D-4162-A669-C4F42848267F
Visible to Intel only — GUID: GUID-CFBEC461-748D-4162-A669-C4F42848267F
novector
Specifies that a particular loop should never be vectorized.
Syntax
#pragma novector |
Arguments
None
Description
The novector pragma specifies that a particular loop should never be vectorized, even if it is legal to do so. When avoiding vectorization of a loop is desirable (when vectorization results in a performance regression rather than improvement), the novector pragma can be used in the source text to disable vectorization of a loop. This behavior is in contrast to the vector always pragma.
Examples
Use the novector pragma:
void foo(int lb, int ub) {
#pragma novector
for(j=lb; j<ub; j++) { a[j]=a[j]+b[j]; }
}
When the trip count (ub - lb) is too low to make vectorization worthwhile, you can use the novector pragma to tell the compiler not to vectorize, even if the loop is considered vectorizable.