[Bug target/40648] misaligned store vectorizer patch introduced 10% runtime regression on Polyhedron test_fpu

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2009-07-04 12:33 -------
One loop is

   139  0.0046 :               DO l = 1 , K
   622  0.0208 :                  IF ( B(l,j)/=ZERO ) THEN
               :                     temp = Alpha*B(l,j)
 21380  0.7146 :                     DO i = 1 , M
569348 19.0299 :                        C(i,j) = C(i,j) + temp*A(i,l)
               :                     ENDDO
               :                  ENDIF
               :               ENDDO

where C(i,j) and A(i,l) are all unaligned.  As the number of iterations is
symbolic we use epilogue peeling.  But instead we could have done
peeling to align the loads/stores from/to C.


      SUBROUTINE DGEMM(M,N,K,Alpha,A,Lda,B,Ldb,Beta,C,Ldc)
      IMPLICIT NONE
      DOUBLE PRECISION , PARAMETER :: ONE = 1.0D+0 , ZERO = 0.0D+0
      DOUBLE PRECISION :: Alpha , Beta
      INTEGER :: K , Lda , Ldb , Ldc , M , N
      DOUBLE PRECISION , DIMENSION(Lda,*) :: A
      DOUBLE PRECISION , DIMENSION(Ldb,*) :: B
      DOUBLE PRECISION , DIMENSION(Ldc,*) :: C
      INTENT (IN) A , Alpha , B , Beta , K , Lda , Ldb , Ldc , M , N
      INTENT (INOUT) C
      INTEGER :: i , j , l
      DOUBLE PRECISION :: temp
            DO j = 1 , N
               IF ( Beta==ZERO ) THEN
                  DO i = 1 , M
                     C(i,j) = ZERO
                  ENDDO
               ELSEIF ( Beta/=ONE ) THEN
                  DO i = 1 , M
                     C(i,j) = Beta*C(i,j)
                  ENDDO
               ENDIF
               DO l = 1 , K
                  IF ( B(l,j)/=ZERO ) THEN
                     temp = Alpha*B(l,j)
                     DO i = 1 , M
                        C(i,j) = C(i,j) + temp*A(i,l)
                     ENDDO
                  ENDIF
               ENDDO
            ENDDO
      END SUBROUTINE DGEMM


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-07-04 12:33:20
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40648