Set Vector Width in Polly

Hello,

What is the way to set vector width with polly.

I used following command for polly vectorization in clang; i don’t use opt because it looks clang llvm and opt are same with polly;

clang -S -emit-llvm matn.c -march=knl -O3 -mllvm -polly -mllvm -polly-vectorizer=stripmine -o matn_poly.ll

is the above command correct?

Here getting vector width=16, i want to set it to 64? not know how to do??

Also what is the advantage of vectorization with polly?