2007-04-06 Robert Dewar <dewar@adacore.com>

	    Thomas Quinot  <quinot@adacore.com>
	    Ed Schonberg  <schonberg@adacore.com>
	    Bob Duff  <duff@adacore.com>

	* einfo.ads, einfo.adb: (First_Component_Or_Discriminant): New function
	(Next_Component_Or_Discriminant): New function and procedure
	(First_Index, First_Literal, Master_Id,
	Set_First_Index, Set_First_Literal, Set_Master_Id):
	Add missing Ekind assertions.
	(Is_Access_Protected_Subprogram_Type): New predicate.
	(Has_RACW): New entity flag, set on package entities to indicate that
	the package contains the declaration of a remote accecss-to-classwide
	type.
	(E_Return_Statement): This node type has the Finalization_Chain_Entity
	attribute, in case the result type has controlled parts.
	(Requires_Overriding): Add this new flag, because "requires
	overriding" is subtly different from "is abstract" (see AI-228).
	(Is_Abstract): Split Is_Abstract flag into Is_Abstract_Subprogram and
	Is_Abstract_Type. Make sure these are called only when appropriate.
	(Has_Pragma_Unreferenced_Objects): New flag

	* exp_ch5.adb (Expand_N_Assignment_Statement): If the left-hand side is
	class-wide, the tag of the right-hand side must be an exact match, not
	an ancestor of that of the object on left-hand side.
	(Move_Activation_Chain): New procedure to create the call to
	System.Tasking.Stages.Move_Activation_Chain.
	(Expand_N_Extended_Return_Statement): Generate code to call
	System.Finalization_Implementation.Move_Final_List at the end of a
	return statement if the function's result type has controlled parts.
	Move asserts to Build_In_Place_Formal.
	(Move_Final_List): New function to create the call statement.
	(Expand_N_Assignment_Statement): In case of assignment to a class-wide
	tagged type, replace generation of call to the run-time subprogram
	CW_Membership by call to Build_CW_Membership.
	(Expand_N_Return_Statement): Replace generation of call to the run-time
	subprogram Get_Access_Level by call to Build_Get_Access_Level.
	(Expand_N_Simple_Function_Return): Replace generation of call to the
	run-time subprogram Get_Access_Level by call to Build_Get_Access_Level.

	* exp_ch6.ads, exp_ch6.adb (Expand_Call): Use new predicate
	Is_Access_Protected_Subprogram_Type, to handle both named and anonymous
	access to protected operations.
	(Add_Task_Actuals_To_Build_In_Place_Call): New procedure to add the
	master and chain actual parameters to a build-in-place function call
	involving tasks.
	(BIP_Formal_Suffix): Add new enumeration literals to complete the case
	statement.
	(Make_Build_In_Place_Call_In_Allocator,
	Make_Build_In_Place_Call_In_Anonymous_Context,
	Make_Build_In_Place_Call_In_Assignment,
	Make_Build_In_Place_Call_In_Object_Declaration): Call
	Add_Task_Actuals_To_Build_In_Place_Call with the appropriate master.
	(Expand_Inlined_Call): If the subprogram is a null procedure, or a
	stubbed procedure with a null body, replace the call with a null
	statement without using the full inlining machinery, for efficiency
	and to avoid invalid values in source file table entries.

	* exp_ch8.adb (Expand_N_Object_Renaming_Declaration): Add support for
	renamings of calls to build-in-place functions.

	* rtsfind.adb (RTE_Record_Component_Available): New subprogram that
	provides the functionality of RTE_Available to record components.
	(RTU_Entity): The function Entity has been renamed to RTU_Entity
	to avoid undesired overloading.
	(Entity): New subprogram that returns the entity for the referened
	unit. If this unit has not been loaded, it returns Empty.
	(RE_Activation_Chain_Access, RE_Move_Activation_Chain): New entities.
	Remove no longer used entities.
	(RE_Finalizable_Ptr_Ptr, RE_Move_Final_List): New entities.
	(RE_Type_Specific_Data): New entity.
	(RE_Move_Any_Value): New entity.
	(RE_TA_A, RE_Get_Any_Type): New entities.
	(RE_Access_Level, RE_Dispatch_Table, E_Default_Prim_Op_Count,
	 RE_Prims_Ptr, RE_RC_Offset, RE_Remotely_Callable,
	 RE_DT_Typeinfo_Ptr_Size, RE_Cstring_Ptr, RE_DT_Expanded_Name): Added.
	(Entity): New subprogram that returns the entity for the referened
	unit. If this unit has not been loaded, it returns Empty.
	(RTE): Addition of a new formal that extends the search to the scopes
	of the record types found in the chain of the package.

	* sem_ch6.ads, sem_ch6.adb (Check_Overriding_Indicator): Print
	"abstract subprograms must be visible" message, whether or not the type
	is an interface; that is, remove the special case for interface types.
	(Analyze_Function_Return): Remove error message "return of task objects
	is not yet implemented" because this is now implemented.
	(Create_Extra_Formals): Add the extra master and activation chain
	formals in case the result type has tasks.
	Remove error message "return of limited controlled objects is not yet
	implemented".
	(Create_Extra_Formals): Add the extra caller's finalization list formal
	in case the result type has controlled parts.
	(Process_Formals): In case of access formal types there is no need
	to continue with the analysis of the formals if we already notified
	errors.
	(Check_Overriding_Indicator): Add code to check overriding of predefined
	operators.
	(Create_Extra_Formals): Prevent creation of useless Extra_Constrained
	flags for formals that do not require them,.
	(Enter_Overloaded_Entity): Do not give -gnatwh warning message unless
	hidden entity is use visible or directly visible.
	(Analyze_Abstract_Subprogram_Declaration,Analyze_Subprogram_Body,
	Analyze_Subprogram_Declaration,Analyze_Subprogram_Specification,
	Check_Conventions,Check_Delayed_Subprogram,Make_Inequality_Operator,
	New_Overloaded_Entity): Split Is_Abstract flag into
	Is_Abstract_Subprogram and Is_Abstract_Type.

	* s-finimp.ads, s-finimp.adb (Move_Final_List): New procedure to move
	a return statement's finalization list to the caller's list, used for
	build-in-place functions with result type with controlled parts.
	Remove no longer used entities.

	* s-taskin.ads (Activation_Chain): Remove pragma Volatile. It is no
	longer needed, because the full type is now limited, and therefore a
	pass-by-reference type.
	(Foreign_Task_Level): New constant.

	* s-tassta.ads, s-tassta.adb (Move_Activation_Chain): New procedure to
	move tasks from the activation chain belonging to a return statement to
	the one passed in by the caller, and update the master to the one
	passed in by the caller.
	(Vulnerable_Complete_Master, Check_Unactivated_Tasks): Check the master
	of unactivated tasks, so we don't kill the ones that are being returned
	by a build-in-place function.
	(Create_Task): Ignore AI-280 for foreign threads.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@123558 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 14 insertions, 9 deletions

diff --git a/gcc/ada/s-taskin.ads b/gcc/ada/s-taskin.ads
index a9b1812b7dc..ae6908dac49 100644
--- a/gcc/ada/s-taskin.ads
+++ b/gcc/ada/s-taskin.ads
@@ -364,10 +364,12 @@ package System.Tasking is
    ------------------------------------
 
    type Activation_Chain is limited private;
-   --  Comment required ???
+   --  Linked list of to-be-activated tasks, linked through
+   --  Activation_Link. The order of tasks on the list is irrelevant, because
+   --  the priority rules will ensure that they actually start activating in
+   --  priority order.
 
    type Activation_Chain_Access is access all Activation_Chain;
-   --  Comment required ???
 
    type Task_Procedure_Access is access procedure (Arg : System.Address);
 
@@ -651,11 +653,14 @@ package System.Tasking is
    --  Normally, a task starts out with internal master nesting level one
    --  larger than external master nesting level. It is incremented to one by
    --  Enter_Master, which is called in the task body only if the compiler
-   --  thinks the task may have dependent tasks. It is set to for the
+   --  thinks the task may have dependent tasks. It is set to 1 for the
    --  environment task, the level 2 is reserved for server tasks of the
    --  run-time system (the so called "independent tasks"), and the level 3 is
-   --  for the library level tasks.
+   --  for the library level tasks. Foreign threads which are detected by
+   --  the run-time have a level of 0, allowing these tasks to be easily
+   --  distinguished if needed.
 
+   Foreign_Task_Level     : constant Master_Level := 0;
    Environment_Task_Level : constant Master_Level := 1;
    Independent_Task_Level : constant Master_Level := 2;
    Library_Task_Level     : constant Master_Level := 3;
@@ -1062,14 +1067,14 @@ package System.Tasking is
 private
    Null_Task : constant Task_Id := null;
 
-   type Activation_Chain is record
+   type Activation_Chain is limited record
       T_ID : Task_Id;
    end record;
-   pragma Volatile (Activation_Chain);
 
-   --  Activation_chain is an in-out parameter of initialization procedures
-   --  and it must be passed by reference because the init proc may terminate
+   --  Activation_Chain is an in-out parameter of initialization procedures and
+   --  it must be passed by reference because the init proc may terminate
    --  abnormally after creating task components, and these must be properly
-   --  registered for removal (Expunge_Unactivated_Tasks).
+   --  registered for removal (Expunge_Unactivated_Tasks). The "limited" forces
+   --  Activation_Chain to be a by-reference type; see RM-6.2(4).
 
 end System.Tasking;