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[Ada] Eliminated protected operations

Message ID 20100617152431.GA14142@adacore.com
State New
Headers show

Commit Message

Arnaud Charlet June 17, 2010, 3:24 p.m. UTC 
The enclosing dynamic scope of a construct is the subprogram body that executes
the construct. If the source construct appears within a protected operation,
the enclosing dynamic scope is the protected subprogram body built for it.
However, this body is not constructed if the protected operation has been
eliminated. In that case the enclosing dynamic scope is the source subprogram,
and is used only for semantic checks.

The following must compile quietly:
   gnatmake -f -gnatec=elim.out test_it.adb
--:
procedure Test_It is
   Var : Integer := 1;

   protected Obj is
      procedure Used;
      procedure Unused;
   private
   end Obj;

   protected body Obj is
      procedure Hidden is
      begin
         declare
            I : Integer := 1;
            procedure Hidden1 is
            begin
               Var := Var + I;
            end Hidden1;
         begin
            Hidden1;
         end;

         Var := Var + 1;
      end Hidden;

      procedure Used is
      begin
         Var := Var + 1;
      end;

      procedure Unused is
      begin
         Hidden;
      end;

   end Obj;

begin
   Obj.Used;
end Test_It;

--- contents of file elim.out (output of gnatelim)

--  List of unused entities to be placed in gnat.adc.  --
pragma Eliminate (Test_It, Unused, Source_Location => "test_it.adb:7");
pragma Eliminate (Test_It, Hidden, Source_Location => "test_it.adb:14");
pragma Eliminate (Test_It, Hidden1, Source_Location => "test_it.adb:18");

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

2010-06-17  Ed Schonberg  <schonberg@adacore.com>

	* sem_util.adb (Enclosing_Subprogram): If the called subprogram is
	protected, use the protected_subprogram_body only if the original
	subprogram has not been eliminated.
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Patch

Index: sem_util.adb
===================================================================
--- sem_util.adb	(revision 160908)
+++ sem_util.adb	(working copy)
@@ -2549,7 +2549,12 @@  package body Sem_Util is
       elsif Ekind (Dynamic_Scope) = E_Task_Type then
          return Get_Task_Body_Procedure (Dynamic_Scope);
 
-      elsif Convention (Dynamic_Scope) = Convention_Protected then
+      --  No body is generated if the protected operation is eliminated
+
+      elsif Convention (Dynamic_Scope) = Convention_Protected
+        and then not Is_Eliminated (Dynamic_Scope)
+        and then Present (Protected_Body_Subprogram (Dynamic_Scope))
+      then
          return Protected_Body_Subprogram (Dynamic_Scope);
 
       else