diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index fcbed1e77bc..f74bad768cf 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2011-12-19  Eric Botcazou  <ebotcazou@adacore.com>
+
+	PR tree-optimization/51580
+	* gnat.dg/specs/loop_optimization1.ads: New test.
+	* gnat.dg/specs/loop_optimization1_pkg.ad[sb]: New helper.
+
 2011-12-19  Richard Guenther  <rguenther@suse.de>
 
 	PR lto/51573
diff --git a/gcc/testsuite/gnat.dg/specs/loop_optimization1.ads b/gcc/testsuite/gnat.dg/specs/loop_optimization1.ads
new file mode 100644
index 00000000000..020ddcd6869
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/specs/loop_optimization1.ads
@@ -0,0 +1,14 @@
+-- { dg-do compile }
+-- { dg-options "-O3" }
+
+with Loop_Optimization1_Pkg;
+
+package Loop_Optimization1 is
+
+  type Kind_Type is (One, Two, Three, Four);
+  type Array_Type is array (Kind_Type) of Boolean;
+  pragma Pack (Array_Type);
+
+  package Q is new Loop_Optimization1_Pkg (Boolean, Kind_Type, Array_Type);
+
+end Loop_Optimization1;
diff --git a/gcc/testsuite/gnat.dg/specs/loop_optimization1_pkg.adb b/gcc/testsuite/gnat.dg/specs/loop_optimization1_pkg.adb
new file mode 100644
index 00000000000..f55dbb07f75
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/specs/loop_optimization1_pkg.adb
@@ -0,0 +1,16 @@
+package body Loop_Optimization1_Pkg is
+
+  type Unconstrained_Array_Type
+    is array (Index_Type range <>) of Element_Type;
+
+  procedure Local (UA : in out Unconstrained_Array_Type) is
+  begin
+    null;
+  end;
+
+  procedure Proc (CA : in out Constrained_Array_Type) is
+  begin
+    Local (Unconstrained_Array_Type (CA));
+  end;
+
+end Loop_Optimization1_Pkg;
diff --git a/gcc/testsuite/gnat.dg/specs/loop_optimization1_pkg.ads b/gcc/testsuite/gnat.dg/specs/loop_optimization1_pkg.ads
new file mode 100644
index 00000000000..577b3a2508d
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/specs/loop_optimization1_pkg.ads
@@ -0,0 +1,13 @@
+-- { dg-excess-errors "no code generated" }
+
+generic
+
+  type Element_Type is private;
+  type Index_Type is (<>);
+  type Constrained_Array_Type is array (Index_Type) of Element_Type;
+
+package Loop_Optimization1_Pkg is
+
+  procedure Proc (CA : in out Constrained_Array_Type);
+
+end Loop_Optimization1_Pkg;