[Ada] Introduce a new Needs_Activation_Record entity flag

2018-05-28  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* einfo.ads, einfo.adb (Needs_Activation_Record): New flag on
	access-to-subprogram types, to indicate that an indirect call through
	such a type requires an activation record when compiling for LLVM.
	* sem_ch3.adb (Access_Subprogram_Declaration): Set new flag as needed.

From-SVN: r260833

gcc/ada/ChangeLog

 2018-05-28  Ed Schonberg  <schonberg@adacore.com>
 
+	* einfo.ads, einfo.adb (Needs_Activation_Record): New flag on
+	access-to-subprogram types, to indicate that an indirect call through
+	such a type requires an activation record when compiling for LLVM.
+	* sem_ch3.adb (Access_Subprogram_Declaration): Set new flag as needed.
+
+2018-05-28  Ed Schonberg  <schonberg@adacore.com>
+
 	* exp_ch4.adb (Real_Range_Check): Specialize float-to-fixed conversions
 	when bounds of fixed type are static, to remove some spuerfluous
 	implicit conversions and provide an accurate result when converting

gcc/ada/einfo.adb

@@ -629,8 +629,8 @@ package body Einfo is
    --    Suppress_Elaboration_Warnings   Flag303
    --    Is_Elaboration_Warnings_OK_Id   Flag304
    --    Is_Activation_Record            Flag305
+   --    Needs_Activation_Record         Flag306
 
-   --    (unused)                        Flag306
    --    (unused)                        Flag307
    --    (unused)                        Flag308
    --    (unused)                        Flag309
@@ -2870,6 +2870,11 @@ package body Einfo is
       return Flag208 (Id);
    end Must_Have_Preelab_Init;
 
+   function Needs_Activation_Record (Id : E) return B is
+   begin
+      return Flag306 (Id);
+   end Needs_Activation_Record;
+
    function Needs_Debug_Info (Id : E) return B is
    begin
       return Flag147 (Id);
@@ -6108,6 +6113,11 @@ package body Einfo is
       Set_Flag208 (Id, V);
    end Set_Must_Have_Preelab_Init;
 
+   procedure Set_Needs_Activation_Record (Id : E; V : B := True) is
+   begin
+      Set_Flag306 (Id, V);
+   end Set_Needs_Activation_Record;
+
    procedure Set_Needs_Debug_Info (Id : E; V : B := True) is
    begin
       Set_Flag147 (Id, V);
@@ -9915,6 +9925,7 @@ package body Einfo is
       W ("May_Inherit_Delayed_Rep_Aspects", Flag262 (Id));
       W ("Must_Be_On_Byte_Boundary",        Flag183 (Id));
       W ("Must_Have_Preelab_Init",          Flag208 (Id));
+      W ("Needs_Activation_Record",         Flag306 (Id));
       W ("Needs_Debug_Info",                Flag147 (Id));
       W ("Needs_No_Actuals",                Flag22  (Id));
       W ("Never_Set_In_Source",             Flag115 (Id));

gcc/ada/einfo.ads

@@ -3534,6 +3534,11 @@ package Einfo is
 --       preelaborable initialization at freeze time (this has to be deferred
 --       to the freeze point because of the rule about overriding Initialize).
 
+--    Needs_Activation_Record (Flag306)
+--       Defined on access_to_subprogram types. Indicates that a call through
+--       a named or anonymous access to subprogram requires an activation
+--       record when compiling with unnesting for C or LLVM.
+
 --    Needs_Debug_Info (Flag147)
 --       Defined in all entities. Set if the entity requires normal debugging
 --       information to be generated. This is true of all entities that have
@@ -5814,6 +5819,7 @@ package Einfo is
    --    Needs_No_Actuals                    (Flag22)
    --    Original_Access_Type                (Node28)
    --    Can_Use_Internal_Rep                (Flag229)
+   --    Needs_Activation_Record             (Flag306)
    --    (plus type attributes)
 
    --  E_Access_Type
@@ -5846,6 +5852,7 @@ package Einfo is
    --    Directly_Designated_Type            (Node20)
    --    Storage_Size_Variable               (Node26)   ??? is this needed ???
    --    Can_Use_Internal_Rep                (Flag229)
+   --    Needs_Activation_Record             (Flag306)
    --    (plus type attributes)
 
    --  E_Anonymous_Access_Type
@@ -7405,6 +7412,7 @@ package Einfo is
    function Modulus                             (Id : E) return U;
    function Must_Be_On_Byte_Boundary            (Id : E) return B;
    function Must_Have_Preelab_Init              (Id : E) return B;
+   function Needs_Activation_Record             (Id : E) return B;
    function Needs_Debug_Info                    (Id : E) return B;
    function Needs_No_Actuals                    (Id : E) return B;
    function Never_Set_In_Source                 (Id : E) return B;
@@ -8110,6 +8118,7 @@ package Einfo is
    procedure Set_Modulus                         (Id : E; V : U);
    procedure Set_Must_Be_On_Byte_Boundary        (Id : E; V : B := True);
    procedure Set_Must_Have_Preelab_Init          (Id : E; V : B := True);
+   procedure Set_Needs_Activation_Record         (Id : E; V : B := True);
    procedure Set_Needs_Debug_Info                (Id : E; V : B := True);
    procedure Set_Needs_No_Actuals                (Id : E; V : B := True);
    procedure Set_Never_Set_In_Source             (Id : E; V : B := True);
@@ -8980,6 +8989,7 @@ package Einfo is
    pragma Inline (Modulus);
    pragma Inline (Must_Be_On_Byte_Boundary);
    pragma Inline (Must_Have_Preelab_Init);
+   pragma Inline (Needs_Activation_Record);
    pragma Inline (Needs_Debug_Info);
    pragma Inline (Needs_No_Actuals);
    pragma Inline (Never_Set_In_Source);
@@ -9474,6 +9484,7 @@ package Einfo is
    pragma Inline (Set_Modulus);
    pragma Inline (Set_Must_Be_On_Byte_Boundary);
    pragma Inline (Set_Must_Have_Preelab_Init);
+   pragma Inline (Set_Needs_Activation_Record);
    pragma Inline (Set_Needs_Debug_Info);
    pragma Inline (Set_Needs_No_Actuals);
    pragma Inline (Set_Never_Set_In_Source);

gcc/ada/sem_ch3.adb

@@ -1305,6 +1305,16 @@ package body Sem_Ch3 is
       Init_Size_Align              (T_Name);
       Set_Directly_Designated_Type (T_Name, Desig_Type);
 
+      --  If the access_to_subprogram is not declared at the library level,
+      --  it can only point to subprograms that are at the same or deeper
+      --  accessibility level. All such might require an activation record
+      --  when compiling for C.
+
+      Set_Needs_Activation_Record  (T_Name,
+                                      not Is_Library_Level_Entity (T_Name));
+      Set_Needs_Activation_Record  (Desig_Type,
+                                      not Is_Library_Level_Entity (T_Name));
+
       Generate_Reference_To_Formals (T_Name);
 
       --  Ada 2005 (AI-231): Propagate the null-excluding attribute