[Bug tree-optimization/18437] New: vectorizer failed for matrix multiplication

["giovannibajo at libero dot it" <gcc-bugzilla at gcc dot gnu dot org>]

Vectorizer fails to handle this:

----------------------------------------------------
#define align(x) __attribute__((align(x)))
typedef float align(16) MATRIX[3][3];

void RotateMatrix(MATRIX ret, MATRIX a, MATRIX b)
{
  int i, j;

  for (j = 0; j < 3; j++)
    for (i = 0; i < 3; i++)
      ret[j][i] =   a[j][0] * b[0][i]
                  + a[j][1] * b[1][i]
                  + a[j][2] * b[2][i];
}
----------------------------------------------------

loop at bench.cc:33: not vectorized: unsupported scalar cycle.
loop at bench.cc:33: bad scalar cycle.

-- 
           Summary: vectorizer failed for matrix multiplication
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: giovannibajo at libero dot it
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18437