Clang can tell you why a loop wasn&#x27;t vectorized with a couple of compiler flags:<p>-Rpass-analysis=loop-vectorize -Rpass-missed=loop-vectorized<p><a href="http:&#x2F;&#x2F;llvm.org&#x2F;docs&#x2F;Vectorizers.html#diagnostics" rel="nofollow">http:&#x2F;&#x2F;llvm.org&#x2F;docs&#x2F;Vectorizers.html#diagnostics</a>