You can use the -guide option to generate GAP advice. From a directory where you can compile the sample program, execute make gap_vec_report from the command-line, or execute:
icpc -c -guide scalar_dep.cpp
The GAP Report appears in the compiler output. GAP reports are encapsulated with GAP REPORT LOG OPENED and END OF GAP REPORT LOG.
GAP REPORT LOG OPENED remark #30761: Add -parallel option if you want the compiler to generate recommendations for improving auto-parallelization. scalar_dep.cpp(51): remark #30515: (VECT) Loop at line 51 cannot be vectorized due to conditional assignment(s) into the following variable(s): b. This loop will be vectorized if the variable(s) become unconditionally initialized at the top of every iteration. [VERIFY] Make sure that the value(s) of the variable(s) read in any iteration of the loop must have been written earlier in the same iteration. Number of advice-messages emitted for this compilation session: 1. END OF GAP REPORT LOG
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