2009-09-21 Basile Starynkevitch <basile@starynkevitch.net>

	MELT branch merged with trunk rev 151911



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/melt-branch@151912 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 18 insertions, 12 deletions

diff --git a/gcc/ada/s-taprop-posix.adb b/gcc/ada/s-taprop-posix.adb
index ac147000b7a..db385c8c589 100644
--- a/gcc/ada/s-taprop-posix.adb
+++ b/gcc/ada/s-taprop-posix.adb
@@ -71,9 +71,6 @@ package body System.Task_Primitives.Operations is
    use System.Parameters;
    use System.OS_Primitives;
 
-   Use_Alternate_Stack : constant Boolean := Alternate_Stack_Size /= 0;
-   --  Whether to use an alternate signal stack for stack overflows
-
    ----------------
    -- Local Data --
    ----------------
@@ -117,6 +114,12 @@ package body System.Task_Primitives.Operations is
    Foreign_Task_Elaborated : aliased Boolean := True;
    --  Used to identified fake tasks (i.e., non-Ada Threads)
 
+   Use_Alternate_Stack : constant Boolean := Alternate_Stack_Size /= 0;
+   --  Whether to use an alternate signal stack for stack overflows
+
+   Abort_Handler_Installed : Boolean := False;
+   --  True if a handler for the abort signal is installed
+
    --------------------
    -- Local Packages --
    --------------------
@@ -198,8 +201,10 @@ package body System.Task_Primitives.Operations is
       pragma Warnings (Off, Result);
 
    begin
-      --  It is not safe to raise an exception when using ZCX and the GCC
-      --  exception handling mechanism.
+      --  It's not safe to raise an exception when using GCC ZCX mechanism.
+      --  Note that we still need to install a signal handler, since in some
+      --  cases (e.g. shutdown of the Server_Task in System.Interrupts) we
+      --  need to send the Abort signal to a task.
 
       if ZCX_By_Default and then GCC_ZCX_Support then
          return;
@@ -1066,11 +1071,13 @@ package body System.Task_Primitives.Operations is
    procedure Abort_Task (T : Task_Id) is
       Result : Interfaces.C.int;
    begin
-      Result :=
-        pthread_kill
-          (T.Common.LL.Thread,
-           Signal (System.Interrupt_Management.Abort_Task_Interrupt));
-      pragma Assert (Result = 0);
+      if Abort_Handler_Installed then
+         Result :=
+           pthread_kill
+             (T.Common.LL.Thread,
+              Signal (System.Interrupt_Management.Abort_Task_Interrupt));
+         pragma Assert (Result = 0);
+      end if;
    end Abort_Task;
 
    ----------------
@@ -1447,8 +1454,6 @@ package body System.Task_Primitives.Operations is
 
       Enter_Task (Environment_Task);
 
-      --  Install the abort-signal handler
-
       if State
           (System.Interrupt_Management.Abort_Task_Interrupt) /= Default
       then
@@ -1465,6 +1470,7 @@ package body System.Task_Primitives.Operations is
               act'Unchecked_Access,
               old_act'Unchecked_Access);
          pragma Assert (Result = 0);
+         Abort_Handler_Installed := True;
       end if;
    end Initialize;