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

[steven at gcc dot gnu.org]

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

Steven Bosscher <steven at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2005-12-21 03:40:32         |2011-05-22 17:36:32

--- Comment #4 from Steven Bosscher <steven at gcc dot gnu.org> 2011-05-22 15:36:52 UTC ---
Test case of comment #0 is not vectorized in recent GCC:

     1    #define align(x) __attribute__((align(x)))
     2    typedef float align(16) MATRIX[3][3];
     3     
     4    void RotateMatrix(MATRIX ret, MATRIX a, MATRIX b)
     5    {
     6      int i, j;
     7     
     8      for (j = 0; j < 3; j++)
     9        for (i = 0; i < 3; i++)
    10          ret[j][i] =   a[j][0] * b[0][i]
    11                      + a[j][1] * b[1][i]
    12                      + a[j][2] * b[2][i];
    13    }


t.c:8: note: not vectorized: loop contains function calls or data references
that cannot be analyzed
t.c:8: note: bad data references.
t.c:4: note: vectorized 0 loops in function.

"GCC: (GNU) 4.6.0 20110312 (experimental) [trunk revision 170907]"