Product Version: Intel® Fortran Compiler 15.0 and above
Cause:
The vectorization report generated using Visual Fortran Compiler's optimization and vectorization report options -O2 -Qvec-report2 -Qopt-report:2 states that loop was not vectorized: vectorization possible but seems inefficient.
Example:
An example below will generate the following remark in optimization report:
ifort -c /O2 /Qopt-report:2 /Qopt-report-phase:vec /Qopt-report-file:stdout f15335.f90
Report from: Vector optimizations [vec]
LOOP BEGIN at f15335.f90(9,5)
remark #15335: loop was not vectorized: vectorization possible but seems inefficient. Use vector always directive or /Qvec-threshold0 to override
LOOP END
Resolution:
Using !DEC$ VECTOR ALWAYS directive in the code will vectorize the loop by overriding efficiency heuristics of the vectorizer.
See also:
VECTOR and NOVECTOR
Vectorization and Optimization Reports
Back to the list of vectorization diagnostics for Intel® Fortran