C******************************************************************************
C FILE: loop05.f
C DESCRIPTION:
C   Demonstrates invarient IF code optimization
C******************************************************************************

	program loop05

	IMPLICIT NONE
	integer ARRAY_SIZE
	parameter(ARRAY_SIZE = 1000)
	integer	I, J
        real A(ARRAY_SIZE), AA(ARRAY_SIZE)
        real B(ARRAY_SIZE), BB(ARRAY_SIZE)
        real X, Y, XX
        integer(8) T1, T2, IRTC

C*****************************************************************************
C*				Untuned Loop				     *
C*****************************************************************************
        T1 = IRTC()

        DO I=1, ARRAY_SIZE
          DO J=1, ARRAY_SIZE
            IF (A(I).GT.100.0) THEN
              B(I) = A(I) - 3.7
            ENDIF
            X = X + A(J) + B(I)
          ENDDO
        ENDDO

        T2 = IRTC()
        write(*,*)'Untuned loop took', (T2-T1)/1000000, 'msec'

C*****************************************************************************
C*				Tuned Loop				     *
C*****************************************************************************
        T1 = IRTC()

        DO I=1, ARRAY_SIZE
          IF (AA(I).GT.100.0) THEN
            BB(I) = AA(I) -3.7
          ENDIF
          DO J=1, ARRAY_SIZE
            XX = XX + AA(J) + BB(I)
          ENDDO
        ENDDO

        T2 = IRTC()
        write(*,*)'Tuned loop took', (T2-T1)/1000000, 'msec'

C       Need to actually use the results of the calculations or else the
C       optimizing compiler may just skip doing them...so we'll just
C       print them.  This will force the optimizer to actually do the work.
        print *, X,XX

999   end