re PR fortran/31732 (Assignment to array slice affects whole array)

2007-05-01  Thomas Koenig  <tkoenig@gcc.gnu.org>

        PR fortran/31732
	* dependency.c (gfc_full_array_ref_p):  If the reference is
	to a single element, check that the array has a single
	element and that the correct element is referenced.

2007-05-01  Thomas Koenig  <tkoenig@gcc.gnu.org>

        PR fortran/31732
	* gfortran.dg/array_memset_2:  New test case.

From-SVN: r124326

4 files changed, 68 insertions, 0 deletions

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index ca1991d..66e6158 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,10 @@
+2007-05-01  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+        PR fortran/31732
+	* dependency.c (gfc_full_array_ref_p):  If the reference is
+	to a single element, check that the array has a single
+	element and that the correct element is referenced.
+
 2007-05-01  Daniel Franke  <franke.daniel@gmail.com>
 
 	* intrinsic.c (add_functions): Fixed ELEMENTAL specifications.
diff --git a/gcc/fortran/dependency.c b/gcc/fortran/dependency.c
index b79f222..bdda6d8 100644
--- a/gcc/fortran/dependency.c
+++ b/gcc/fortran/dependency.c
@@ -1126,6 +1126,24 @@ gfc_full_array_ref_p (gfc_ref *ref)
 
   for (i = 0; i < ref->u.ar.dimen; i++)
     {
+      /* If we have a single element in the reference, we need to check
+	 that the array has a single element and that we actually reference
+	 the correct element.  */
+      if (ref->u.ar.dimen_type[i] == DIMEN_ELEMENT)
+	{
+	  if (!ref->u.ar.as
+	      || !ref->u.ar.as->lower[i]
+	      || !ref->u.ar.as->upper[i]
+	      || gfc_dep_compare_expr (ref->u.ar.as->lower[i],
+				       ref->u.ar.as->upper[i])
+	      || !ref->u.ar.start[i]
+	      || gfc_dep_compare_expr (ref->u.ar.start[i],
+				       ref->u.ar.as->lower[i]))
+	    return false;
+	  else
+	    continue;
+	}
+
       /* Check the lower bound.  */
       if (ref->u.ar.start[i]
 	  && (!ref->u.ar.as
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 617de90..82c9109 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2007-05-01  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+        PR fortran/31732
+	* gfortran.dg/array_memset_2:  New test case.
+
 2007-05-01  Dorit Nuzman  <dorit@il.ibm.com>
 
 	PR testsuite/31615
diff --git a/gcc/testsuite/gfortran.dg/array_memset_2.f90 b/gcc/testsuite/gfortran.dg/array_memset_2.f90
new file mode 100644
index 0000000..58ce8fe
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/array_memset_2.f90
@@ -0,0 +1,38 @@
+! { dg-do run }
+! { dg-options "-O2 -fdump-tree-original" }
+
+module foo
+contains
+  subroutine bar(a)
+    real, dimension(:,:) :: a
+    a(1,:) = 0.
+  end subroutine bar
+end module foo
+
+program test
+  use foo
+  implicit none
+  real, dimension (2,2) :: a, d, e
+  real, dimension (1,2) :: b
+  real, dimension (2) :: c
+  data a, d, e /12*1.0/
+  data b /2*1.0/
+  data c /2*1.0/
+
+  a(1,:) = 0.    ! This can't be optimized to a memset.
+  b(1,:) = 0.    ! This is optimized to memset.
+  c = 0.         ! This is optimized to memset.
+  d(:,1) = 0.    ! This can't be otimized to a memset.
+  call bar(e)
+
+  if (any(a /= reshape((/ 0.0, 1.0, 0.0, 1.0/), shape(a)))) call abort
+  if (any(b /= 0.)) call abort
+  if (any(c /= 0.)) call abort
+  if (any(d /= reshape((/ 0.0, 0.0, 1.0, 1.0/), shape(d)))) call abort
+  if (any(e /= reshape((/ 0.0, 1.0, 0.0, 1.0/), shape(e)))) call abort
+
+end program
+
+! { dg-final { scan-tree-dump-times "memset" 2 "original" } }
+! { dg-final { cleanup-tree-dump "original" } }
+! { dg-final { cleanup-modules "foo" } }