diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6c4d6d25b32..39cc5522a9c 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2009-07-07  Eric Botcazou  <ebotcazou@adacore.com>
+
+	PR debug/40666
+	* dbxout.c (dbxout_symbol) <PARM_DECL>: Deal with parameters pointing
+	to variables for debugging purposes.
+
 2009-06-23  Mark Loeser  <mark@halcy0n.com>
 
 	PR build/40010
diff --git a/gcc/dbxout.c b/gcc/dbxout.c
index df11628329b..bc7965e25b8 100644
--- a/gcc/dbxout.c
+++ b/gcc/dbxout.c
@@ -2778,9 +2778,15 @@ dbxout_symbol (tree decl, int local ATTRIBUTE_UNUSED)
       }
 
     case PARM_DECL:
-      /* Parm decls go in their own separate chains
-	 and are output by dbxout_reg_parms and dbxout_parms.  */
-      gcc_unreachable ();
+      if (DECL_HAS_VALUE_EXPR_P (decl))
+	decl = DECL_VALUE_EXPR (decl);
+
+      /* PARM_DECLs go in their own separate chain and are output by
+	 dbxout_reg_parms and dbxout_parms, except for those that are
+	 disguised VAR_DECLs like Out parameters in Ada.  */
+      gcc_assert (TREE_CODE (decl) == VAR_DECL);
+
+      /* ... fall through ...  */
 
     case RESULT_DECL:
     case VAR_DECL: