ada: Streamline expansion of controlled actions for aggregates

This changes the strategy used to expand controlled actions for array and
record aggregates so as to make it simpler and more robust.

The current strategy is to set the No_Ctrl_Actions flag on the assignments
generated during the expansion of aggregate, as done during the expansion
of initialization procedures, and to generate the adjustments of the LHS
manually in the same list of actions, before sending the entire list for
analysis and expansion.  The problem is that, when the RHS also requires
controlled actions, the No_Ctrl_Actions flag prevents transient scopes
from being created around the assignments, with the end result that the
actions are "naturally" generated between the assignments and adjustments
of the LHS, causing premature finalization of the RHS.  In order to counter
that, the controlled actions of the RHS must also be generated manually
during the expansion of the aggregates, after blocking normal processing
e.g. by means of the No_Side_Effect_Removal flag.  This means that, for
a more complex RHS, this strategy generates a wrong order of controlled
actions by default, until specifically adjusted.

The new strategy is to reuse the standard machinery as much as possible,
disabling only the part that is not needed for the assignments generated
during the expansion of aggregates, namely the finalization of the LHS;
in other words, the adjustment of the LHS is left entirely to the standard
machinery and the creation of transient scopes is no longer blocked, which
gives a correct order of controlled actions by default.  It is implemented
by means of a No_Finalize_Actions flag present on the assignments generated
during the expansion.

It is mostly straightforward, modulo the following hitch: the assignments
are now analyzed and expanded by the common expander, which in the case of
controlled assignments analyzes the final rewriting with all checks off,
which in particular disables elaboration checks for the calls to the Adjust
primitives; now these checks are necessary in the case where an aggregate
is the initialization expression of an object declared before the body of
the Adjust primitive is seen.  Hence the use of an existing trick, namely
Suppress/Unsuppress blocks, around the assignments.

gcc/ada/

	* gen_il-fields.ads (Opt_Field_Enum): Add No_Finalize_Actions and
	remove No_Side_Effect_Removal.
	* gen_il-gen-gen_nodes.adb (N_Function_Call): Remove semantic flag
	No_Side_Effect_Removal
	(N_Assignment_Statement): Add semantic flag No_Finalize_Actions.
	* sinfo.ads (No_Ctrl_Actions): Adjust comment.
	(No_Finalize_Actions): New flag on assignment statements.
	(No_Side_Effect_Removal): Delete.
	* exp_aggr.adb (Build_Record_Aggr_Code): Remove obsolete comment and
	Ancestor_Is_Expression variable.  In the case of an extension, do
	not generate a call to Adjust manually, call Set_No_Finalize_Actions
	instead.  Do not set the tags, replace call to Make_Unsuppress_Block
	by Make_Suppress_Block and remove useless assertions.
	In the general case, call Initialize_Component.
	(Initialize_Controlled_Component): Delete.
	(Initialize_Simple_Component): Delete.
	(Initialize_Component): Do the low-level processing, but do not
	generate a call to Adjust manually, call Set_No_Finalize_Actions.
	(Process_Transient_Component): Delete.
	(Process_Transient_Component_Completion): Likewise.
	* exp_ch5.adb (Expand_Assign_Array): Deal with No_Finalize_Actions.
	(Expand_Assign_Array_Loop): Likewise.
	(Expand_N_Assignment_Statement): Likewise.
	(Make_Tag_Ctrl_Assignment): Likewise.
	* exp_util.adb (Remove_Side_Effects): Do not test the
	No_Side_Effect_Removal flag.
	* sem_prag.adb (Process_Suppress_Unsuppress): Give the warning in
	SPARK mode only for pragma Suppress.
	* tbuild.ads (Make_Suppress_Block): New declaration.
	(Make_Unsuppress_Block): Adjust comment.
	* tbuild.adb (Make_Suppress_Block): New procedure.
	(Make_Unsuppress_Block): Unsuppress instead of suppressing.

1 files changed, 1 insertions, 1 deletions

diff --git a/gcc/ada/gen_il-fields.ads b/gcc/ada/gen_il-fields.ads
index ad240a7..c62523d 100644
--- a/gcc/ada/gen_il-fields.ads
+++ b/gcc/ada/gen_il-fields.ads
@@ -321,9 +321,9 @@ package Gen_IL.Fields is
       No_Ctrl_Actions,
       No_Elaboration_Check,
       No_Entities_Ref_In_Spec,
+      No_Finalize_Actions,
       No_Initialization,
       No_Minimize_Eliminate,
-      No_Side_Effect_Removal,
       No_Truncation,
       Null_Excluding_Subtype,
       Null_Exclusion_Present,