PR fortran/77261 Run random_3 testcase only when real(10) is available.

From-SVN: r239817

gcc/testsuite/ChangeLog

+2016-08-29  Janne Blomqvist  <jb@gcc.gnu.org>
+
+	PR fortran/77261
+	* gfortran.dg/random_3.f90: Run testcase only when real(10) is
+	available.
+
 2016-08-28  Tom de Vries  <tom@codesourcery.com>
 
 	PR lto/70955

gcc/testsuite/gfortran.dg/random_3.f90

 ! { dg-do run }
 ! { dg-require-effective-target fortran_large_real }
-! Check that the random_seed for real(10) or real(16) exists and that
-! real(8) and real(10) or real(16) random number generators
+! Check that the random_seed for real(10) exists and that
+! real(8) and real(10) random number generators
 ! return the same sequence of values.
 ! Mostly copied from random_2.f90
-program random_4
+program random_3
   integer,parameter :: k = selected_real_kind (precision (0.0_8) + 1)
 
   integer, dimension(:), allocatable :: seed
@@ -13,6 +13,11 @@ program random_4
   real, parameter :: delta = 1.d-10
   integer n
 
+  ! Run the test only if real(10) is available. With the current
+  ! xorshift1024* PRNG the real(16) generator uses two uint64_t values
+  ! for every real(16) value generated, and hence the sequences won't
+  ! be the same as with real(4,8,10).
+  if (k == 10) then
      call random_seed (size=n)
      allocate (seed(n))
      call random_seed (get=seed)
@@ -26,4 +31,5 @@ program random_4
      call random_number (r10(10))
 
      if (any ((r8 - r10) .gt. delta)) call abort
-end program random_4
+  end if
+end program random_3