Clang can tell you why a loop wasn't vectorized with a couple of compiler flags: -Rpass-analysis=loop-vectorize -Rpass-missed=loop-vectorized http://llvm.org/

Clang can tell you why a loop wasn't vectorized with a couple of compiler flags: -Rpass-analysis=loop-vectorize -Rpass-missed=loop-vectorized http://llvm.org/docs/Vectorizers.html#diagnostics http://llvm.org/docs/Vectorizers.html#diagnostics