Understanding gcc 4.9.2 auto-vectorization output

Question

I am trying to learn gcc auto-vectorization module. After reading documentation from here.

Here is what I tried (debian jessie amd64):

$ cat ex1.c
in         


        

Answer 1

Actually digging in gcc online doc, I finally found out that I should use instead: -fopt-info-vec-optimized (or maybe -fopt-info-vec-all). See here and here:

optimized: Print information when an optimization is successfully applied. It is up to a pass to decide which information is relevant. For example, the vectorizer passes print the source location of loops which are successfully vectorized.

missed: Print information about missed optimizations. Individual passes control which information to include in the output.

note: Print verbose information about optimizations, such as certain transformations, more detailed messages about decisions etc.

all: Print detailed optimization information. This includes ‘optimized’, ‘missed’, and ‘note’.