[Bug tree-optimization/45022] New: No prefetch for the vectorized loop

[changpeng dot fang at amd dot com]

For the following test case, if we compile with -O3 -fprefetch-loop-arrays
-march=amdfam10, the loop is versioned (for runtime alias checking) to be
vectorized. However, we see prefetches in the non-vectorize version, but
not in the vectorized version.

void foo(int beta, float *a, float *b)
{
  int i;
  for(i=0; i<1024; i++)
     a[i] = a[i] + beta * b[i];
}

For the vectorized loop, in tree-ssa-loop-arrays.c (idx_analyze_ref):
 if (TREE_CODE (base) == MISALIGNED_INDIRECT_REF
      || TREE_CODE (base) == ALIGN_INDIRECT_REF)
    return false;

FALSE is returned due to mis-aligned indirect reference:
M*vect_p.18_61{misalignment: 0}
M*vect_p.23_66{misalignment: 0}
M*vect_p.31_74{misalignment: 0}


-- 
           Summary: No prefetch for the vectorized loop
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: changpeng dot fang at amd dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45022