--- /dev/null
+! { dg-do compile }
+! { dg-options "-O3 -ffast-math -floop-interchange -fdump-tree-linterchange-details" }
+
+ subroutine mat_times_vec(y,x,a,axp,ayp,azp,axm,aym,azm,
+ $ nb,nx,ny,nz)
+ implicit none
+ integer nb,nx,ny,nz,i,j,k,m,l,kit,im1,ip1,jm1,jp1,km1,kp1
+
+ real*8 y(nb,nx,ny,nz),x(nb,nx,ny,nz)
+
+ real*8 a(nb,nb,nx,ny,nz),
+ 1 axp(nb,nb,nx,ny,nz),ayp(nb,nb,nx,ny,nz),azp(nb,nb,nx,ny,nz),
+ 2 axm(nb,nb,nx,ny,nz),aym(nb,nb,nx,ny,nz),azm(nb,nb,nx,ny,nz)
+
+
+ do k=1,nz
+ km1=mod(k+nz-2,nz)+1
+ kp1=mod(k,nz)+1
+ do j=1,ny
+ jm1=mod(j+ny-2,ny)+1
+ jp1=mod(j,ny)+1
+ do i=1,nx
+ im1=mod(i+nx-2,nx)+1
+ ip1=mod(i,nx)+1
+ do l=1,nb
+ y(l,i,j,k)=0.0d0
+ do m=1,nb
+ y(l,i,j,k)=y(l,i,j,k)+
+ 1 a(l,m,i,j,k)*x(m,i,j,k)+
+ 2 axp(l,m,i,j,k)*x(m,ip1,j,k)+
+ 3 ayp(l,m,i,j,k)*x(m,i,jp1,k)+
+ 4 azp(l,m,i,j,k)*x(m,i,j,kp1)+
+ 5 axm(l,m,i,j,k)*x(m,im1,j,k)+
+ 6 aym(l,m,i,j,k)*x(m,i,jm1,k)+
+ 7 azm(l,m,i,j,k)*x(m,i,j,km1)
+ enddo
+ enddo
+ enddo
+ enddo
+ enddo
+ return
+ end
+
+! { dg-final { scan-tree-dump-times "is interchanged" 1 "linterchange" } }
--- /dev/null
+! { dg-do compile }
+! { dg-require-effective-target vect_cond_mixed }
+! { dg-require-effective-target vect_double }
+! { dg-additional-options "-O3 -ffast-math -floop-interchange -fdump-tree-linterchange-details" }
+! vect_cond_mixed lies on x86, we cannot do vcond[_eq]v2div2df
+! { dg-additional-options "-msse4.1" { target { x86_64-*-* i?86-*-* } } }
+
+ subroutine mat_times_vec(y,x,a,axp,ayp,azp,axm,aym,azm,
+ $ nb,nx,ny,nz)
+ implicit none
+ integer nb,nx,ny,nz,i,j,k,m,l,kit,im1,ip1,jm1,jp1,km1,kp1
+
+ real*8 y(nb,nx,ny,nz),x(nb,nx,ny,nz)
+
+ real*8 a(nb,nb,nx,ny,nz),
+ 1 axp(nb,nb,nx,ny,nz),ayp(nb,nb,nx,ny,nz),azp(nb,nb,nx,ny,nz),
+ 2 axm(nb,nb,nx,ny,nz),aym(nb,nb,nx,ny,nz),azm(nb,nb,nx,ny,nz)
+
+
+ do k=1,nz
+ km1=mod(k+nz-2,nz)+1
+ kp1=mod(k,nz)+1
+ do j=1,ny
+ jm1=mod(j+ny-2,ny)+1
+ jp1=mod(j,ny)+1
+ do i=1,nx
+ im1=mod(i+nx-2,nx)+1
+ ip1=mod(i,nx)+1
+ do l=1,nb
+ y(l,i,j,k)=0.0d0
+ do m=1,nb
+ y(l,i,j,k)=y(l,i,j,k)+
+ 1 a(l,m,i,j,k)*x(m,i,j,k)+
+ 2 axp(l,m,i,j,k)*x(m,ip1,j,k)+
+ 3 ayp(l,m,i,j,k)*x(m,i,jp1,k)+
+ 4 azp(l,m,i,j,k)*x(m,i,j,kp1)+
+ 5 axm(l,m,i,j,k)*x(m,im1,j,k)+
+ 6 aym(l,m,i,j,k)*x(m,i,jm1,k)+
+ 7 azm(l,m,i,j,k)*x(m,i,j,km1)
+ enddo
+ enddo
+ enddo
+ enddo
+ enddo
+ return
+ end
+
+! verify we can vectorize the inner loop after interchange
+! { dg-final { scan-tree-dump-times "is interchanged" 1 "linterchange" } }
+! { dg-final { scan-tree-dump "vectorized 1 loops in function" "vect" } }