diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f97c401..3e34022 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2018-12-14  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* dwarf2out.c (analyze_discr_in_predicate): Simplify.
+	(analyze_variants_discr): Deal with naked boolean discriminants.
+
 2018-12-14  Claudiu Zissulescu  <claziss@synopsys.com>
 
 	* config/arc/arc.c (arc_restore_callee_milli) Don't clobber off
diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index f04a052..9fa05898 100644
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,3 +1,8 @@
+2018-12-14  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gcc-interface/decl.c (choices_to_gnu): Directly use a naked boolean
+	discriminant if the value is the boolean true.
+
 2018-12-11  Eric Botcazou  <ebotcazou@adacore.com>
 
 	PR ada/88429
@@ -170,8 +175,8 @@
 	retrieve directly its RM size.
 	(components_to_record): Minor tweak.
 	(set_rm_size): Remove useless test.
-	* gcc-interface/trans.c (gnat_to_gnu): Do wrap the instance of a
-	boolean discriminant attached to a variant part.
+	* gcc-interface/trans.c (gnat_to_gnu): Do not wrap the instance of
+	a boolean discriminant attached to a variant part.
 
 2018-12-11  Ed Schonberg  <schonberg@adacore.com>
 
@@ -289,8 +294,7 @@
 
 	* fe.h (Is_Atomic_Object): Declare.
 	(Is_Volatile_Object): Likewise.
-	* gcc-interface/trans.c (atomic_or_volatile_copy_required_p):
-	New.
+	* gcc-interface/trans.c (atomic_or_volatile_copy_required_p): New.
 	(Call_to_gnu): Generate a copy for an actual parameter passed by
 	reference if the conditions set forth by RM C.6(19) are met and
 	specificially deal with an atomic actual parameter.
diff --git a/gcc/ada/gcc-interface/decl.c b/gcc/ada/gcc-interface/decl.c
index b2f9229..0ad06f1 100644
--- a/gcc/ada/gcc-interface/decl.c
+++ b/gcc/ada/gcc-interface/decl.c
@@ -6848,6 +6848,9 @@
 			     build_binary_op (LE_EXPR, boolean_type_node,
 					      gnu_operand, gnu_high, true),
 			     true);
+      else if (gnu_low == boolean_true_node
+	       && TREE_TYPE (gnu_operand) == boolean_type_node)
+	gnu_test = gnu_operand;
       else if (gnu_low)
 	gnu_test
 	  = build_binary_op (EQ_EXPR, boolean_type_node, gnu_operand, gnu_low,
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 99ac40f..cb5cc01 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -24537,6 +24537,7 @@
 
 /* Return whether DECL is a FIELD_DECL that represents the variant part of a
    structure.  */
+
 static bool
 is_variant_part (tree decl)
 {
@@ -24550,17 +24551,8 @@
 static tree
 analyze_discr_in_predicate (tree operand, tree struct_type)
 {
-  bool continue_stripping = true;
-  while (continue_stripping)
-    switch (TREE_CODE (operand))
-      {
-      CASE_CONVERT:
-	operand = TREE_OPERAND (operand, 0);
-	break;
-      default:
-	continue_stripping = false;
-	break;
-      }
+  while (CONVERT_EXPR_P (operand))
+    operand = TREE_OPERAND (operand, 0);
 
   /* Match field access to members of struct_type only.  */
   if (TREE_CODE (operand) == COMPONENT_REF
@@ -24780,6 +24772,19 @@
 	      new_node->dw_discr_range = true;
 	    }
 
+	  else if ((candidate_discr
+		      = analyze_discr_in_predicate (match_expr, struct_type))
+		   && TREE_TYPE (candidate_discr) == boolean_type_node)
+	    {
+	      /* We are matching:  <discr_field> for a boolean discriminant.
+		 This sub-expression matches boolean_true_node.  */
+	      new_node = ggc_cleared_alloc<dw_discr_list_node> ();
+	      if (!get_discr_value (boolean_true_node,
+				    &new_node->dw_discr_lower_bound))
+		goto abort;
+	      new_node->dw_discr_range = false;
+	    }
+
 	  else
 	    /* Unsupported sub-expression: we cannot determine the set of
 	       matching discriminant values.  Abort everything.  */