[COMMITTED] algol68: handle ultra-flat multiples in ELEMS

[Jose E. Marchesi]

---
 gcc/algol68/a68-low-prelude.cc            | 23 +++++++++++++++--------
 gcc/testsuite/algol68/execute/elems-2.a68 |  6 ++++++
 2 files changed, 21 insertions(+), 8 deletions(-)
 create mode 100644 gcc/testsuite/algol68/execute/elems-2.a68

diff --git a/gcc/algol68/a68-low-prelude.cc b/gcc/algol68/a68-low-prelude.cc
index 506817607cd..4dccdc4fb47 100644
--- a/gcc/algol68/a68-low-prelude.cc
+++ b/gcc/algol68/a68-low-prelude.cc
@@ -684,8 +684,6 @@ elems (tree boundable, tree dim)
   /* BOUNDABLE can be a multiple or a ROWS.  */
   tree type = TREE_TYPE (boundable);
 
-  /* XXX handle flat dimensions other than 1:0 and return zero for them.  */
-
   /* Make DIM zero-based.  */
   dim = fold_build2 (MINUS_EXPR, TREE_TYPE (dim), dim, size_one_node);
 
@@ -707,12 +705,21 @@ elems (tree boundable, tree dim)
   else
     gcc_unreachable ();
 
-  return fold_build2 (PLUS_EXPR,
-		      sizetype,
-		      fold_convert (sizetype,
-				    fold_build2 (MINUS_EXPR, ssizetype,
-						 upper_bound, lower_bound)),
-		      size_one_node);
+  upper_bound = save_expr (upper_bound);
+  lower_bound = save_expr (lower_bound);
+
+  tree non_flat = fold_build2 (PLUS_EXPR,
+			       sizetype,
+			       fold_convert (sizetype,
+					     fold_build2 (MINUS_EXPR, ssizetype,
+							  upper_bound, lower_bound)),
+			       size_one_node);
+
+  return fold_build3 (COND_EXPR, sizetype,
+		      fold_build2 (LT_EXPR, boolean_type_node,
+				   upper_bound, lower_bound),
+		      size_zero_node,
+		      non_flat);
 }
 
 tree
diff --git a/gcc/testsuite/algol68/execute/elems-2.a68 b/gcc/testsuite/algol68/execute/elems-2.a68
new file mode 100644
index 00000000000..e2f6d7d882c
--- /dev/null
+++ b/gcc/testsuite/algol68/execute/elems-2.a68
@@ -0,0 +1,6 @@
+# Flat and ultra-flat multiples.  #
+BEGIN [3][10:3]INT arr;
+      ASSERT (2 ELEMS arr = 0);
+      [1:0]INT arr2;
+      ASSERT (ELEMS arr2 = 0)
+END
-- 
2.30.2