Re: Auto-vectorization with gcj

[Andrew Haley <aph at redhat dot com>]

Dietmar Lippold writes:
 > I tried to test auto-vectorization with the following java program:
 > 
 > public class Test {
 >   private static int[] a = new int[256];
 >   private static int[] b = new int[256];
 >   private static int[] c = new int[256];
 > 
 >   public static final void main(String[] args) {
 >     for (int i = 0; i < 256; i++) {
 >       b[i] = i;
 >       c[i] = i;
 >     }
 >     for (int i = 0; i < 256; i++) {
 >       a[i] = b[i] + c[i];
 >     }
 >   }
 > }
 > 
 > When I compile it with
 > 
 > gcj -msse2 -O2 -ftree-vectorize -ftree-vectorizer-verbose=5 -c Test.java
 > 
 > I get the following message:
 > 
 > Test.java:9: note: not vectorized: multiple exits.
 > Test.java:14: note: not vectorized: multiple exits.
 > Test.java:7: note: vectorized 0 loops in function.
 > 
 > Is it not possible to use auto-vectorization with gcj until now?

Not as far as I am aware, no.  You may be the first person ever to
try it.

I don't know why the compiler believes the loops have multiple exits.
If you want to find out, it's time to start looking at dumps.

Andrew.