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[multiple changes]

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2011-08-05  Sergey Rybin  <rybin@adacore.com>

	* tree_io.ads: Update ASIS_Version_Number because of the change of the
	order of calling Tree_Write/Tree_Read routines made for aspects.

2011-08-05  Bob Duff  <duff@adacore.com>

	* a-fihema.adb (Finalize): Fix race condition.

From-SVN: r177445
This commit is contained in:
Arnaud Charlet 2011-08-05 16:27:16 +02:00
parent 5f9cdefe6b
commit efe05dfc95
3 changed files with 126 additions and 53 deletions
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9
gcc/ada/ChangeLog
View File

@ -1,3 +1,12 @@
2011-08-05 Sergey Rybin <rybin@adacore.com>
* tree_io.ads: Update ASIS_Version_Number because of the change of the
order of calling Tree_Write/Tree_Read routines made for aspects.
2011-08-05 Bob Duff <duff@adacore.com>
* a-fihema.adb (Finalize): Fix race condition.
2011-08-05 Yannick Moy <moy@adacore.com>
* sem_ch12.adb (Analyze_Package_Instantiation,

168
gcc/ada/a-fihema.adb
View File

@ -35,12 +35,16 @@ with Ada.Unchecked_Conversion;
with System; use System;
with System.Address_Image;
with System.IO; use System.IO;
with System.OS_Lib;
with System.Soft_Links; use System.Soft_Links;
with System.Storage_Elements; use System.Storage_Elements;
with System.Storage_Pools; use System.Storage_Pools;
package body Ada.Finalization.Heap_Management is
Debug : constant Boolean := False;
-- True for debugging printouts.
Header_Size : constant Storage_Count := Node'Size / Storage_Unit;
-- Size of the header in bytes. Added to Storage_Size requested by
-- Allocate/Deallocate to determine the Storage_Size passed to the
@ -59,6 +63,42 @@ package body Ada.Finalization.Heap_Management is
procedure Detach (N : Node_Ptr);
-- Unhook a node from an arbitrary list
procedure Fin_Assert (Condition : Boolean; Message : String);
-- Asserts that the condition is True. Used instead of pragma Assert in
-- delicate places where raising an exception would cause re-invocation of
-- finalization. Instead of raising an exception, aborts the whole
-- process.
function Is_Empty (Objects : Node_Ptr) return Boolean;
-- True if the Objects list is empty.
----------------
-- Fin_Assert --
----------------
procedure Fin_Assert (Condition : Boolean; Message : String) is
procedure Fail;
-- Use a separate procedure to make it easy to set a breakpoint here.
----------
-- Fail --
----------
procedure Fail is
begin
Put_Line ("Heap_Management: Fin_Assert failed: " & Message);
OS_Lib.OS_Abort;
end Fail;
-- Start of processing for Fin_Assert
begin
if not Condition then
Fail;
end if;
end Fin_Assert;
---------------------------
-- Add_Offset_To_Address --
---------------------------
@ -221,40 +261,24 @@ package body Ada.Finalization.Heap_Management is
------------
procedure Detach (N : Node_Ptr) is
-- N must be attached to some list
pragma Assert (N.Next /= null and then N.Prev /= null);
procedure Null_Out_Pointers;
-- Set Next/Prev pointer of N to null (for debugging)
----------
-- Head --
----------
procedure Null_Out_Pointers is
begin
N.Next := null;
N.Prev := null;
end Null_Out_Pointers;
-- Start of processing for Detach
begin
pragma Debug (Fin_Assert (N /= null, "Detach null"));
Lock_Task.all;
N.Prev.Next := N.Next;
N.Next.Prev := N.Prev;
if N.Next = null then
pragma Assert (N.Prev = null);
else
N.Prev.Next := N.Next;
N.Next.Prev := N.Prev;
N.Next := null;
N.Prev := null;
end if;
Unlock_Task.all;
-- Note: no need to unlock in case of exceptions; the above code cannot
-- raise any.
-- No need to null out the pointers, except that it makes pcol easier to
-- understand.
pragma Debug (Null_Out_Pointers);
end Detach;
--------------
@ -264,54 +288,81 @@ package body Ada.Finalization.Heap_Management is
overriding procedure Finalize
(Collection : in out Finalization_Collection)
is
Curr_Ptr : Node_Ptr := Collection.Objects.Next; -- skip dummy head
Ex_Occur : Exception_Occurrence;
Raised : Boolean := False;
-- Start of processing for Finalize
begin
if Debug then
Put_Line ("-->Heap_Management: ");
pcol (Collection);
end if;
-- Set Finalization_Started to prevent any allocations of objects with
-- controlled parts during finalization. The associated access type is
-- about to go out of scope; Finalization_Started is never again
-- modified.
if Collection.Finalization_Started then
-- ???Needed for shared libraries.
return;
end if;
pragma Debug (Fin_Assert (not Collection.Finalization_Started,
"Finalize: already started"));
Collection.Finalization_Started := True;
-- Go through the Objects list, and finalize each one. There is no need
-- to detach items from the list, because the whole collection is about
-- to go away.
-- For each object in the Objects list, detach it, and finalize it. Note
-- that other tasks can be doing Unchecked_Deallocations at the same
-- time, so we need to beware of race conditions.
while Curr_Ptr /= Collection.Objects'Unchecked_Access loop
while not Is_Empty (Collection.Objects'Unchecked_Access) loop
-- ??? Kludge: Don't do anything until the proper place to set
-- primitive Finalize_Address has been determined.
declare
Node : constant Node_Ptr := Collection.Objects.Next;
begin
-- Remove the current node from the list first, in case some other
-- task is simultaneously doing Unchecked_Deallocation on this
-- object. Detach does Lock_Task. Note that we can't Lock_Task
-- during Finalize_Address, because finalization can do pretty
-- much anything.
if Collection.Finalize_Address /= null then
declare
Object_Address : constant Address :=
Curr_Ptr.all'Address + Header_Offset;
-- Get address of object from address of header
Detach (Node);
begin
Collection.Finalize_Address (Object_Address);
-- ??? Kludge: Don't do anything until the proper place to set
-- primitive Finalize_Address has been determined.
exception
when Fin_Except : others =>
if not Raised then
Raised := True;
Save_Occurrence (Ex_Occur, Fin_Except);
end if;
end;
end if;
if Collection.Finalize_Address /= null then
declare
Object_Address : constant Address :=
Node.all'Address + Header_Offset;
-- Get address of object from address of header
Curr_Ptr := Curr_Ptr.Next;
begin
Collection.Finalize_Address (Object_Address);
exception
when Fin_Except : others =>
if not Raised then
Raised := True;
Save_Occurrence (Ex_Occur, Fin_Except);
end if;
end;
end if;
end;
end loop;
if Debug then
Put_Line ("<--Heap_Management: ");
pcol (Collection);
end if;
-- If the finalization of a particular node raised an exception, reraise
-- it after the remainder of the list has been finalized.
if Raised then
if Debug then
Put_Line ("Heap_Management: reraised");
end if;
Reraise_Occurrence (Ex_Occur);
end if;
end Finalize;
@ -328,8 +379,21 @@ package body Ada.Finalization.Heap_Management is
Collection.Objects.Next := Collection.Objects'Unchecked_Access;
Collection.Objects.Prev := Collection.Objects'Unchecked_Access;
pragma Assert (Is_Empty (Collection.Objects'Unchecked_Access));
end Initialize;
--------------
-- Is_Empty --
--------------
function Is_Empty (Objects : Node_Ptr) return Boolean is
begin
pragma Debug
(Fin_Assert ((Objects.Next = Objects) = (Objects.Prev = Objects),
"Is_Empty"));
return Objects.Next = Objects;
end Is_Empty;
----------
-- pcol --
----------

2
gcc/ada/tree_io.ads
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@ -47,7 +47,7 @@ package Tree_IO is
Tree_Format_Error : exception;
-- Raised if a format error is detected in the input file
ASIS_Version_Number : constant := 25;
ASIS_Version_Number : constant := 26;
-- ASIS Version. This is used to check for consistency between the compiler
-- used to generate trees and an ASIS application that is reading the
-- trees. It must be incremented whenever a change is made to the tree