[gcc(refs/users/guojiufu/heads/personal-branch)] Added test case for a PR which has been fixed in the meantime.

[Jiu Fu Guo]

https://gcc.gnu.org/g:905ba62ec96f8469c1085861d9ceec58fbee5709

commit 905ba62ec96f8469c1085861d9ceec58fbee5709
Author: Thomas Koenig <tkoenig@gcc.gnu.org>
Date:   Sun Jun 7 10:43:54 2020 +0200

    Added test case for a PR which has been fixed in the meantime.
    
    gcc/testsuite/ChangeLog:
    
            PR tree-optimization/50439
            * gfortran.dg/loop_interchange_2.f: New test.

Diff:
---
 gcc/testsuite/gfortran.dg/loop_interchange_2.f | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/gcc/testsuite/gfortran.dg/loop_interchange_2.f b/gcc/testsuite/gfortran.dg/loop_interchange_2.f
new file mode 100644
index 00000000000..5869c29aa4b
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/loop_interchange_2.f
@@ -0,0 +1,20 @@
+C { dg-do compile }
+C { dg-options "-std=legacy -O3 -floop-interchange" }
+C PR 50439 - this used to hang. Test case by Pat Haugen.
+
+      subroutine comnul
+C-----------------------------------------------------------------------
+      implicit real*8 (a-h,o-z)
+      parameter(zero=0.0d0,half=0.5d0,one=1.0d0)
+      common/secom/rtc(9,18,10,5),rts(9,18,10,5)
+      save
+C-----------------------------------------------------------------------
+      do 110 i1=1,9
+        do 110 i2=1,18
+          do 110 i3=1,10
+            do 110 i4=1,5
+              rtc(i1,i2,i3,i4)=zero
+              rts(i1,i2,i3,i4)=zero
+  110 continue
+      return
+      end