re PR fortran/45159 (Unnecessary temporaries)

2010-08-27  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/45159
	* dependency.c (check_section_vs_section):  Single test for
	identical strides which takes into account that only one
	of the strides may be NULL.

2010-08-27  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/45159
	* gfortran.dg/dependency_33.f90:  New test.

From-SVN: r163584

4 files changed, 44 insertions, 15 deletions

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index f28030f..9bd81c3 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,10 @@
+2010-08-27  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/45159
+	* dependency.c (check_section_vs_section):  Single test for
+	identical strides which takes into account that only one
+	of the strides may be NULL.
+
 2010-08-27  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
 
 	PR fortran/43217
diff --git a/gcc/fortran/dependency.c b/gcc/fortran/dependency.c
index dfb0c94..ab75bde 100644
--- a/gcc/fortran/dependency.c
+++ b/gcc/fortran/dependency.c
@@ -1023,6 +1023,7 @@ check_section_vs_section (gfc_array_ref *l_ar, gfc_array_ref *r_ar, int n)
   gfc_expr *r_lower;
   gfc_expr *r_upper;
   int r_dir;
+  bool identical_strides;
 
   /* If they are the same range, return without more ado.  */
   if (gfc_is_same_range (l_ar, r_ar, n, 0))
@@ -1076,6 +1077,23 @@ check_section_vs_section (gfc_array_ref *l_ar, gfc_array_ref *r_ar, int n)
   if (l_dir == 0 || r_dir == 0)
     return GFC_DEP_OVERLAP;
 
+  /* Determine if the strides are equal.  */
+
+  if (l_stride)
+    {
+      if (r_stride)
+	identical_strides = gfc_dep_compare_expr (l_stride, r_stride) == 0;
+      else
+	identical_strides = gfc_expr_is_one (l_stride, 0) == 1;
+    }
+  else
+    {
+      if (r_stride)
+	identical_strides = gfc_expr_is_one (r_stride, 0) == 1;
+      else
+	identical_strides = true;
+    }
+
   /* Determine LHS upper and lower bounds.  */
   if (l_dir == 1)
     {
@@ -1175,11 +1193,7 @@ check_section_vs_section (gfc_array_ref *l_ar, gfc_array_ref *r_ar, int n)
       && l_start && r_start && gfc_dep_compare_expr (l_start, r_start) == -1
       && l_end && r_end && gfc_dep_compare_expr (l_end, r_end) == -1)
     {
-      /* Check that the strides are the same.  */
-      if (!l_stride && !r_stride)
-	return GFC_DEP_FORWARD;
-      if (l_stride && r_stride
-	  && gfc_dep_compare_expr (l_stride, r_stride) == 0)
+      if (identical_strides)
 	return GFC_DEP_FORWARD;
     }
 
@@ -1188,20 +1202,12 @@ check_section_vs_section (gfc_array_ref *l_ar, gfc_array_ref *r_ar, int n)
       && l_start && r_start && gfc_dep_compare_expr (l_start, r_start) == 1
       && l_end && r_end && gfc_dep_compare_expr (l_end, r_end) == 1)
     {
-      /* Check that the strides are the same.  */
-      if (!l_stride && !r_stride)
-	return GFC_DEP_FORWARD;
-      if (l_stride && r_stride
-	  && gfc_dep_compare_expr (l_stride, r_stride) == 0)
+      if (identical_strides)
 	return GFC_DEP_FORWARD;
     }
 
 
-  /*  Are the strides the same?  */
-  if ((!l_stride && !r_stride)
-	||
-      (l_stride && r_stride
-	&& gfc_dep_compare_expr (l_stride, r_stride) == 0))
+  if (identical_strides)
     {
 
       if (l_start && IS_ARRAY_EXPLICIT (l_ar->as))
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index d8b9801..1c1dc43 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2010-08-27  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/45159
+	* gfortran.dg/dependency_33.f90:  New test.
+
 2010-08-27  Richard Guenther  <rguenther@suse.de>
 
 	* gcc.dg/graphite/scop-1.c: Fix out-of-bound array accesses.
diff --git a/gcc/testsuite/gfortran.dg/dependency_33.f90 b/gcc/testsuite/gfortran.dg/dependency_33.f90
new file mode 100644
index 0000000..cf6f175
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/dependency_33.f90
@@ -0,0 +1,11 @@
+! { dg-do compile }
+! { dg-options "-Warray-temporaries" }
+! No temporary should be created for this, as a missing stride and
+! a stride equal to one should be equal.
+program main
+  integer a(100)
+  a(10:16) = a(11:17)
+  a(10:16) = a(11:17:1)
+  a(10:16:1) = a(11:17)
+  a(10:16:1) = a(11:17:1)
+end program main