dwarf2out.c (gen_variable_die): Emit DW_AT_const_expr attribute if needed.

	* dwarf2out.c (gen_variable_die): Emit DW_AT_const_expr attribute
	if needed.  Re-add origin_die variable and its initialization.
cp/
	* cp-objcp-common.c (cp_decl_dwarf_attribute): Handle
	DW_AT_const_expr.
testsuite/
	* g++.dg/debug/dwarf2/constexpr-var-1.C: New test.

From-SVN: r241408

gcc/ChangeLog

 2016-10-21  Jakub Jelinek  <jakub@redhat.com>
 
+	* dwarf2out.c (gen_variable_die): Emit DW_AT_const_expr attribute
+	if needed.  Re-add origin_die variable and its initialization.
+
 	* gimplify.c (gimplify_bind_expr): Handle oacc_declare_returns
 	even for -fstack-reuse=none, or for volatile vars etc.
 

gcc/cp/ChangeLog

+2016-10-21  Jakub Jelinek  <jakub@redhat.com>
+
+	* cp-objcp-common.c (cp_decl_dwarf_attribute): Handle
+	DW_AT_const_expr.
+
 2016-10-17  Jakub Jelinek  <jakub@redhat.com>
 
 	* cp-objcp-common.h (cp_function_decl_explicit_p,

gcc/cp/cp-objcp-common.c

@@ -168,6 +168,11 @@ cp_decl_dwarf_attribute (const_tree decl, int attr)
 	}
       break;
 
+    case DW_AT_const_expr:
+      if (VAR_OR_FUNCTION_DECL_P (decl) && DECL_DECLARED_CONSTEXPR_P (decl))
+	return 1;
+      break;
+
     default:
       break;
     }

gcc/dwarf2out.c

@@ -21264,6 +21264,7 @@ gen_variable_die (tree decl, tree origin, dw_die_ref context_die)
   tree ultimate_origin;
   dw_die_ref var_die;
   dw_die_ref old_die = decl ? lookup_decl_die (decl) : NULL;
+  dw_die_ref origin_die = NULL;
   bool declaration = (DECL_EXTERNAL (decl_or_origin)
 		      || class_or_namespace_scope_p (context_die));
   bool specialization_p = false;
@@ -21423,7 +21424,7 @@ gen_variable_die (tree decl, tree origin, dw_die_ref context_die)
     var_die = new_die (DW_TAG_variable, context_die, decl);
 
   if (origin != NULL)
-    add_abstract_origin_attribute (var_die, origin);
+    origin_die = add_abstract_origin_attribute (var_die, origin);
 
   /* Loop unrolling can create multiple blocks that refer to the same
      static variable, so we must test for the DW_AT_declaration flag.
@@ -21509,6 +21510,14 @@ gen_variable_die (tree decl, tree origin, dw_die_ref context_die)
     }
   else
     tree_add_const_value_attribute_for_decl (var_die, decl_or_origin);
+
+  if ((dwarf_version >= 4 || !dwarf_strict)
+      && lang_hooks.decls.decl_dwarf_attribute (decl_or_origin,
+						DW_AT_const_expr) == 1
+      && !get_AT (var_die, DW_AT_const_expr)
+      && (origin_die == NULL || get_AT (origin_die, DW_AT_const_expr) == NULL)
+      && !specialization_p)
+    add_AT_flag (var_die, DW_AT_const_expr, 1);
 }
 
 /* Generate a DIE to represent a named constant.  */

gcc/testsuite/ChangeLog

+2016-10-21  Jakub Jelinek  <jakub@redhat.com>
+
+	* g++.dg/debug/dwarf2/constexpr-var-1.C: New test.
+
 2016-10-21  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/69566

gcc/testsuite/g++.dg/debug/dwarf2/constexpr-var-1.C

+// { dg-do compile }
+// { dg-options "-O -std=c++11 -g -dA -gno-strict-dwarf" }
+// { dg-final { scan-assembler-times " DW_AT_const_expr" 2 } }
+
+constexpr int a = 5;
+struct S
+{
+  static constexpr int b = 6;
+} s;