ada: Fix unnesting generated loops with nested finalization procedure

The compiler can generate loops for creating array aggregates, for
example used during the initialization of variable. If the component
type of the array element requires finalization, the compiler also
creates a block and a nested procedure that need to be correctly
unnested if unnesting is enabled. During the unnesting transformation,
the scopes for these inner blocks need to be fixed and set to the
enclosing loop entity.

gcc/ada/

	* exp_ch7.adb (Contains_Subprogram): Recursively search for subp
	in loop's statements.
	(Unnest_Loop)<Fixup_Inner_Scopes>: New.
	(Unnest_Loop): Rename local variable for more clarity.
	* exp_unst.ads: Refresh comment.

diff --git a/gcc/ada/exp_ch7.adb b/gcc/ada/exp_ch7.adb
index 271dfd22618c5538e8b692b367778a9ab52bcfef..585acd8b428560b07c7545b3e86dbf216d9a92f7 100644 (file)
--- a/gcc/ada/exp_ch7.adb
+++ b/gcc/ada/exp_ch7.adb
@@ -4378,6 +4378,32 @@ package body Exp_Ch7 is
    begin
       E := First_Entity (Blk);
 
+      --  The compiler may generate loops with a declare block containing
+      --  nested procedures used for finalization. Recursively search for
+      --  subprograms in such constructs.
+
+      if Ekind (Blk) = E_Loop
+        and then Parent_Kind (Blk) = N_Loop_Statement
+      then
+         declare
+            Stmt : Node_Id := First (Statements (Parent (Blk)));
+         begin
+            while Present (Stmt) loop
+               if Nkind (Stmt) = N_Block_Statement then
+                  declare
+                     Id : constant Entity_Id :=
+                              Entity (Identifier (Stmt));
+                  begin
+                     if Contains_Subprogram (Id) then
+                        return True;
+                     end if;
+                  end;
+               end if;
+               Next (Stmt);
+            end loop;
+         end;
+      end if;
+
       while Present (E) loop
          if Is_Subprogram (E) then
             return True;
@@ -9350,17 +9376,67 @@ package body Exp_Ch7 is
    -----------------
 
    procedure Unnest_Loop (Loop_Stmt : Node_Id) is
+
+      procedure Fixup_Inner_Scopes (Loop_Stmt : Node_Id);
+      --  The loops created by the compiler for array aggregates can have
+      --  nested finalization procedure when the type of the array components
+      --  needs finalization. It has the following form:
+
+      --  for J4b in 10 .. 12 loop
+      --     declare
+      --        procedure __finalizer;
+      --     begin
+      --        procedure __finalizer is
+      --          ...
+      --        end;
+      --        ...
+      --        obj (J4b) := ...;
+
+      --  When the compiler creates the N_Block_Statement, it sets its scope to
+      --  the upper scope (the one containing the loop).
+
+      --  The Unnest_Loop procedure moves the N_Loop_Statement inside a new
+      --  procedure and correctly sets the scopes for both the new procedure
+      --  and the loop entity. The inner block scope is not modified and this
+      --  leaves the Tree in an incoherent state (i.e. the inner procedure must
+      --  have its enclosing procedure in its scope ancestries).
+
+      --  This procedure fixes the scope links.
+
+      --  Another (better) fix would be to have the block scope set to be the
+      --  loop entity earlier (when the block is created or when the loop gets
+      --  an actual entity set). But unfortunately this proved harder to
+      --  implement ???
+
+      procedure Fixup_Inner_Scopes (Loop_Stmt : Node_Id) is
+         Stmt          : Node_Id            := First (Statements (Loop_Stmt));
+         Loop_Stmt_Ent : constant Entity_Id := Entity (Identifier (Loop_Stmt));
+         Ent_To_Fix    : Entity_Id;
+      begin
+         while Present (Stmt) loop
+            if Nkind (Stmt) = N_Block_Statement
+              and then Is_Abort_Block (Stmt)
+            then
+               Ent_To_Fix := Entity (Identifier (Stmt));
+               Set_Scope (Ent_To_Fix, Loop_Stmt_Ent);
+            elsif Nkind (Stmt) = N_Loop_Statement then
+               Fixup_Inner_Scopes (Stmt);
+            end if;
+            Next (Stmt);
+         end loop;
+      end Fixup_Inner_Scopes;
+
       Loc        : constant Source_Ptr := Sloc (Loop_Stmt);
       Ent        : Entity_Id;
       Local_Body : Node_Id;
       Local_Call : Node_Id;
+      Loop_Ent   : Entity_Id;
       Local_Proc : Entity_Id;
-      Local_Scop : Entity_Id;
       Loop_Copy  : constant Node_Id :=
                      Relocate_Node (Loop_Stmt);
    begin
-      Local_Scop := Entity (Identifier (Loop_Stmt));
-      Ent := First_Entity (Local_Scop);
+      Loop_Ent := Entity (Identifier (Loop_Stmt));
+      Ent := First_Entity (Loop_Ent);
 
       Local_Proc := Make_Temporary (Loc, 'P');
 
@@ -9389,8 +9465,10 @@ package body Exp_Ch7 is
       --  New procedure has the same scope as the original loop, and the scope
       --  of the loop is the new procedure.
 
-      Set_Scope (Local_Proc, Scope (Local_Scop));
-      Set_Scope (Local_Scop, Local_Proc);
+      Set_Scope (Local_Proc, Scope (Loop_Ent));
+      Set_Scope (Loop_Ent, Local_Proc);
+
+      Fixup_Inner_Scopes (Loop_Copy);
 
       --  The entity list of the new procedure is that of the loop
 

diff --git a/gcc/ada/exp_unst.ads b/gcc/ada/exp_unst.ads
index 40d2257da770e3bc9451a2089df0762eb70d2e78..05385355e8b84ff49613fcfc83800ba2b9abfafe 100644 (file)
--- a/gcc/ada/exp_unst.ads
+++ b/gcc/ada/exp_unst.ads
@@ -42,11 +42,8 @@ package Exp_Unst is
    --  references, and implements an appropriate static chain approach to
    --  dealing with such uplevel references.
 
-   --  However, we also want to be able to interface with back ends that do
-   --  not easily handle such uplevel references. One example is the back end
-   --  that translates the tree into standard C source code. In the future,
-   --  other back ends might need the same capability (e.g. a back end that
-   --  generated LLVM intermediate code).
+   --  However, we also want to be able to interface with back ends that do not
+   --  easily handle such uplevel references. One example is the LLVM back end.
 
    --  We could imagine simply handling such references in the appropriate
    --  back end. For example the back end that generates C could recognize