[Bug tree-optimization/60505] New: Warning caused by GCC vectorizer.

["congh at google dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60505

            Bug ID: 60505
           Summary: Warning caused by GCC vectorizer.
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: congh at google dot com

The compilation on the code below fails with options "-Wall  -Werror -O2
-ftree-loop-vectorize". The reason is that the epilogue generated by the
vectorizer tries to access the memory outside of ovec[16] and the the vrp pass
emits the warning "array subscript is above array bounds" for the access to
ovec[i]. The vectorizer should not generate the epilogue for this loop.



void foo(char *in, char *out, int num)
{
 int i;
 unsigned char ovec[16] = {0};

 for(i=0; i < num ; ++i)
   out[i] = (ovec[i] = in[i]);
 out[num] = ovec[num/2];
}