===================================================================
@@ -168,15 +168,31 @@
Msg_Node : Node_Id;
begin
- -- Nothing to do if we are the prefix of an attribute, since we do not
- -- want an atomic sync operation for things like A'Adress or A'Size).
- if Nkind (Parent (N)) = N_Attribute_Reference
- and then Prefix (Parent (N)) = N
- then
- return;
- end if;
+ case Nkind (Parent (N)) is
+ when N_Attribute_Reference |
+ -- Nothing to do if we are the prefix of an attribute, since we
+ -- do not want an atomic sync operation for things like 'Size.
+
+ N_Reference |
+
+ -- Likewise for a mere reference
+
+ N_Indexed_Component |
+ N_Selected_Component |
+ N_Slice =>
+
+ -- The C.6(15) clause says that only reads and updates of the
+ -- object as a whole require atomic synchronization.
+
+ if Prefix (Parent (N)) = N then
+ return;
+ end if;
+
+ when others => null;
+ end case;
+
-- Go ahead and set the flag
Set_Atomic_Sync_Required (N);
===================================================================
@@ -8196,15 +8196,44 @@
Analyze (N);
end if;
- -- If we still have a selected component, and the type is an Atomic
- -- type for which Atomic_Sync is enabled, then we set the atomic sync
- -- flag on the selector.
+ -- Set Atomic_Sync_Required if necessary for atomic component
- if Nkind (N) = N_Selected_Component
- and then Is_Atomic (Etype (N))
- and then not Atomic_Synchronization_Disabled (Etype (N))
- then
- Activate_Atomic_Synchronization (N);
+ if Nkind (N) = N_Selected_Component then
+ declare
+ E : constant Entity_Id := Entity (Selector_Name (N));
+ Set : Boolean;
+
+ begin
+ -- If component is atomic, but type is not, setting depends on
+ -- disable/enable state for the component.
+
+ if Is_Atomic (E) and then not Is_Atomic (Etype (E)) then
+ Set := not Atomic_Synchronization_Disabled (E);
+
+ -- If component is not atomic, but its type is atomic, setting
+ -- depends on disable/enable state for the type.
+
+ elsif not Is_Atomic (E) and then Is_Atomic (Etype (E)) then
+ Set := not Atomic_Synchronization_Disabled (Etype (E));
+
+ -- If both component and type are atomic, we disable if either
+ -- component or its type have sync disabled.
+
+ elsif Is_Atomic (E) and then Is_Atomic (Etype (E)) then
+ Set := (not Atomic_Synchronization_Disabled (E))
+ and then
+ (not Atomic_Synchronization_Disabled (Etype (E)));
+
+ else
+ Set := False;
+ end if;
+
+ -- Set flag if required
+
+ if Set then
+ Activate_Atomic_Synchronization (N);
+ end if;
+ end;
end if;
end Expand_N_Selected_Component;
This makes the compiler detect one more case needing atomic synchronization, namely a pragma Atomic on a component with a predefined type. And this also excludes a few more cases not needing it. The compiler should issue the warning with -gnatw.n -gnatld7 -gnatj60 on: procedure Synccomp is type R is record I : Integer; pragma Atomic (I); end record; Rec : R; begin Rec.I := 1; end; for Rec.I in the assignment. Tested on x86_64-pc-linux-gnu, committed on trunk 2011-11-04 Eric Botcazou <ebotcazou@adacore.com> * exp_ch4.adb (Expand_N_Selected_Component): Refine code setting the Atomic_Sync_Required flag to detect one more case. * exp_util.adb (Activate_Atomic_Synchronization): Refine code setting the Atomic_Sync_Required flag to exclude more cases, depending on the parent of the node to be examined.