[Ada] Small cleanup in the Expand_Image_Attribute procedure

[Pierre-Marie de Rodat <derodat@adacore.com>]

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This moves the inline expansion for user-defined enumeration types back
into the normal flow of control, moves the declarations of local objects
to where they are needed and removes an explicit check for private types
in the enumeration case, which is now superfluous.

No functional changes.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

	* exp_imgv.adb (Is_User_Defined_Enumeration_Type): Delete.
	(Expand_Image_Attribute): Move inline expansion into normal flow of
	control, move down declarations and remove superfluous processing.

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diff --git a/gcc/ada/exp_imgv.adb b/gcc/ada/exp_imgv.adb
--- a/gcc/ada/exp_imgv.adb
+++ b/gcc/ada/exp_imgv.adb
@@ -761,10 +761,6 @@ package body Exp_Imgv is
       --  Expand attribute 'Image in user-defined enumeration types, avoiding
       --  string copy.
 
-      function Is_User_Defined_Enumeration_Type
-        (Typ : Entity_Id) return Boolean;
-      --  Return True if Typ is a user-defined enumeration type
-
       -----------------------------------
       -- Expand_Standard_Boolean_Image --
       -----------------------------------
@@ -837,7 +833,7 @@ package body Exp_Imgv is
              Name                =>
                Make_If_Expression (Loc,
                  Expressions => New_List (
-                   Relocate_Node (Expr),
+                   Duplicate_Subexpr (Expr),
                    New_Occurrence_Of (T_Id, Loc),
                    New_Occurrence_Of (F_Id, Loc)))));
 
@@ -1005,20 +1001,6 @@ package body Exp_Imgv is
          Analyze_And_Resolve (N, Standard_String);
       end Expand_User_Defined_Enumeration_Image;
 
-      --------------------------------------
-      -- Is_User_Defined_Enumeration_Type --
-      --------------------------------------
-
-      function Is_User_Defined_Enumeration_Type
-        (Typ : Entity_Id) return Boolean is
-      begin
-         return Ekind (Typ) = E_Enumeration_Type
-           and then Typ /= Standard_Boolean
-           and then Typ /= Standard_Character
-           and then Typ /= Standard_Wide_Character
-           and then Typ /= Standard_Wide_Wide_Character;
-      end Is_User_Defined_Enumeration_Type;
-
       --  Local variables
 
       Enum_Case : Boolean;
@@ -1060,46 +1042,6 @@ package body Exp_Imgv is
          Rtyp := Underlying_Type (Base_Type (Ptyp));
       end if;
 
-      --  Use inline expansion for user-defined enumeration types for which
-      --  the literal string entity has been built, and if -gnatd_x is not
-      --  passed to the compiler. Otherwise the attribute will be expanded
-      --  into a call to a routine in the runtime.
-
-      if Is_User_Defined_Enumeration_Type (Rtyp)
-        and then Present (Lit_Strings (Rtyp))
-        and then not Debug_Flag_Underscore_X
-      then
-         Expand_User_Defined_Enumeration_Image (Rtyp);
-         return;
-      end if;
-
-      --  Build declarations of Snn and Pnn to be inserted
-
-      Ins_List := New_List (
-
-         --  Snn : String (1 .. typ'Width);
-
-         Make_Object_Declaration (Loc,
-            Defining_Identifier => Snn,
-            Object_Definition   =>
-              Make_Subtype_Indication (Loc,
-                Subtype_Mark => New_Occurrence_Of (Standard_String, Loc),
-                Constraint   =>
-                  Make_Index_Or_Discriminant_Constraint (Loc,
-                    Constraints => New_List (
-                      Make_Range (Loc,
-                        Low_Bound  => Make_Integer_Literal (Loc, 1),
-                        High_Bound =>
-                          Make_Attribute_Reference (Loc,
-                            Prefix         => New_Occurrence_Of (Rtyp, Loc),
-                            Attribute_Name => Name_Width)))))),
-
-         --  Pnn : Natural;
-
-         Make_Object_Declaration (Loc,
-           Defining_Identifier => Pnn,
-           Object_Definition   => New_Occurrence_Of (Standard_Natural, Loc)));
-
       --  Set Imid (RE_Id of procedure to call), and Tent, target for the
       --  type conversion of the first argument for all possibilities.
 
@@ -1266,9 +1208,14 @@ package body Exp_Imgv is
             Analyze_And_Resolve (N, Standard_String);
             return;
 
-         else
-            --  Here for enumeration type case
+         --  Use inline expansion if the -gnatd_x switch is not passed to the
+         --  compiler. Otherwise expand into a call to the runtime.
+
+         elsif not Debug_Flag_Underscore_X then
+            Expand_User_Defined_Enumeration_Image (Rtyp);
+            return;
 
+         else
             Ttyp := Component_Type (Etype (Lit_Indexes (Rtyp)));
 
             if Ttyp = Standard_Integer_8 then
@@ -1295,25 +1242,11 @@ package body Exp_Imgv is
       --  Build first argument for call
 
       if Enum_Case then
-         declare
-            T : Entity_Id;
-         begin
-            --  In Ada 2020 we need the underlying type here, because 'Image is
-            --  allowed on private types. We have already checked the version
-            --  when resolving the attribute.
-
-            if Is_Private_Type (Ptyp) then
-               T := Rtyp;
-            else
-               T := Ptyp;
-            end if;
-
-            Arg_List := New_List (
-              Make_Attribute_Reference (Loc,
-                Attribute_Name => Name_Pos,
-                Prefix         => New_Occurrence_Of (T, Loc),
-                Expressions    => New_List (Expr)));
-         end;
+         Arg_List := New_List (
+           Make_Attribute_Reference (Loc,
+             Attribute_Name => Name_Pos,
+             Prefix         => New_Occurrence_Of (Ptyp, Loc),
+             Expressions    => New_List (Expr)));
 
       --  AI12-0020: Ada 2020 allows 'Image for all types, including private
       --  types. If the full type is not a fixed-point type, then it is enough
@@ -1325,6 +1258,7 @@ package body Exp_Imgv is
       else
          declare
             Conv : Node_Id;
+
          begin
             if Is_Private_Type (Etype (Expr)) then
                if Is_Fixed_Point_Type (Rtyp) then
@@ -1340,6 +1274,33 @@ package body Exp_Imgv is
          end;
       end if;
 
+      --  Build declarations of Snn and Pnn to be inserted
+
+      Ins_List := New_List (
+
+         --  Snn : String (1 .. typ'Width);
+
+         Make_Object_Declaration (Loc,
+            Defining_Identifier => Snn,
+            Object_Definition   =>
+              Make_Subtype_Indication (Loc,
+                Subtype_Mark => New_Occurrence_Of (Standard_String, Loc),
+                Constraint   =>
+                  Make_Index_Or_Discriminant_Constraint (Loc,
+                    Constraints => New_List (
+                      Make_Range (Loc,
+                        Low_Bound  => Make_Integer_Literal (Loc, 1),
+                        High_Bound =>
+                          Make_Attribute_Reference (Loc,
+                            Prefix         => New_Occurrence_Of (Rtyp, Loc),
+                            Attribute_Name => Name_Width)))))),
+
+         --  Pnn : Natural;
+
+         Make_Object_Declaration (Loc,
+           Defining_Identifier => Pnn,
+           Object_Definition   => New_Occurrence_Of (Standard_Natural, Loc)));
+
       --  Append Snn, Pnn arguments
 
       Append_To (Arg_List, New_Occurrence_Of (Snn, Loc));