[Ada] Inlining of renamed subprogram instances in package body

This fixes a small discrepancy in the handling of renamed subprograms
declared in a package body, between those originally a regular
subprogram and those an instance of a generic subprogram, the latter
being slightly hindered.

The difference comes from the setting of the Is_Public flag, which was
more conservative in the latter case because instantiations of generic
subprograms are done in compiler-generated local packages.

It is eliminated by allowing Has_Referencer to recurse into nested
packages, but only if they are themselves not instances of generic
packages.

The compiler must now fully inline Doit_I into Doit at -O2 in:

package P is

  generic procedure Doit_G;

  procedure Doit;
end P;

package body P is

  N : Natural := 0;

  procedure Doit_G is
  begin
    N := 1;
  end Doit_G;

  procedure Doit_I is new Doit_G;

  procedure Doit renames Doit_I;

end P;

2018-09-26  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* sem_ch7.adb (Has_Referencer): Remove Top_Level parameter and
	add In_Nested_Instance and
	Has_Outer_Referencer_Of_Non_Subprograms parameters.  Rename
	Has_Non_Subprograms_Referencer variable into
	Has_Referencer_Of_Non_Subprograms and initialize it with the new
	third parameter.  Adjust recursive calls and to the renaming.
	Replace test on Top_Level with test on In_Nested_Instance to
	decide whether to clear the Is_Public flag on entities.
	(Hide_Public_Entities): Adjust call to Has_Referencer.

From-SVN: r264615

1 files changed, 44 insertions, 21 deletions

diff --git a/gcc/ada/sem_ch7.adb b/gcc/ada/sem_ch7.adb
index cb4b853..8aebb0f 100644
--- a/gcc/ada/sem_ch7.adb
+++ b/gcc/ada/sem_ch7.adb
@@ -259,11 +259,12 @@ package body Sem_Ch7 is
 
       procedure Hide_Public_Entities (Decls : List_Id) is
          function Has_Referencer
-           (Decls     : List_Id;
-            Top_Level : Boolean := False) return Boolean;
+           (Decls                                   : List_Id;
+            In_Nested_Instance                      : Boolean;
+            Has_Outer_Referencer_Of_Non_Subprograms : Boolean) return Boolean;
          --  A "referencer" is a construct which may reference a previous
          --  declaration. Examine all declarations in list Decls in reverse
-         --  and determine whether once such referencer exists. All entities
+         --  and determine whether one such referencer exists. All entities
          --  in the range Last (Decls) .. Referencer are hidden from external
          --  visibility.
 
@@ -286,14 +287,16 @@ package body Sem_Ch7 is
          --------------------
 
          function Has_Referencer
-           (Decls     : List_Id;
-            Top_Level : Boolean := False) return Boolean
+           (Decls                                   : List_Id;
+            In_Nested_Instance                      : Boolean;
+            Has_Outer_Referencer_Of_Non_Subprograms : Boolean) return Boolean
          is
             Decl    : Node_Id;
             Decl_Id : Entity_Id;
             Spec    : Node_Id;
 
-            Has_Non_Subprograms_Referencer : Boolean := False;
+            Has_Referencer_Of_Non_Subprograms : Boolean :=
+                                       Has_Outer_Referencer_Of_Non_Subprograms;
             --  Set if an inlined subprogram body was detected as a referencer.
             --  In this case, we do not return True immediately but keep hiding
             --  subprograms from external visibility.
@@ -319,13 +322,23 @@ package body Sem_Ch7 is
 
                elsif Nkind (Decl) = N_Package_Declaration then
                   Spec := Specification (Decl);
+                  Decl_Id := Defining_Entity (Spec);
 
                   --  Inspect the declarations of a non-generic package to try
                   --  and hide more entities from external visibility.
 
-                  if not Is_Generic_Unit (Defining_Entity (Spec)) then
-                     if Has_Referencer (Private_Declarations (Spec))
-                       or else Has_Referencer (Visible_Declarations (Spec))
+                  if not Is_Generic_Unit (Decl_Id) then
+                     if Has_Referencer (Private_Declarations (Spec),
+                                        In_Nested_Instance
+                                          or else
+                                        Is_Generic_Instance (Decl_Id),
+                                        Has_Referencer_Of_Non_Subprograms)
+                       or else
+                        Has_Referencer (Visible_Declarations (Spec),
+                                        In_Nested_Instance
+                                          or else
+                                        Is_Generic_Instance (Decl_Id),
+                                        Has_Referencer_Of_Non_Subprograms)
                      then
                         return True;
                      end if;
@@ -354,7 +367,12 @@ package body Sem_Ch7 is
                   --  Inspect the declarations of a non-generic package body to
                   --  try and hide more entities from external visibility.
 
-                  elsif Has_Referencer (Declarations (Decl)) then
+                  elsif Has_Referencer (Declarations (Decl),
+                                        In_Nested_Instance
+                                          or else
+                                        Is_Generic_Instance (Decl_Id),
+                                        Has_Referencer_Of_Non_Subprograms)
+                  then
                      return True;
                   end if;
 
@@ -382,7 +400,7 @@ package body Sem_Ch7 is
                      if Is_Inlined (Decl_Id)
                        or else Has_Pragma_Inline (Decl_Id)
                      then
-                        Has_Non_Subprograms_Referencer := True;
+                        Has_Referencer_Of_Non_Subprograms := True;
 
                         --  Inspect the statements of the subprogram body
                         --  to determine whether the body references other
@@ -401,7 +419,7 @@ package body Sem_Ch7 is
                      if Is_Inlined (Decl_Id)
                        or else Has_Pragma_Inline (Decl_Id)
                      then
-                        Has_Non_Subprograms_Referencer := True;
+                        Has_Referencer_Of_Non_Subprograms := True;
 
                         --  Inspect the statements of the subprogram body
                         --  to determine whether the body references other
@@ -425,15 +443,20 @@ package body Sem_Ch7 is
                   begin
                      --  Inspect the actions to find references to subprograms
 
-                     Discard := Has_Referencer (Actions (Decl));
+                     Discard :=
+                       Has_Referencer (Actions (Decl),
+                                       In_Nested_Instance,
+                                       Has_Referencer_Of_Non_Subprograms);
                   end;
 
                --  Exceptions, objects and renamings do not need to be public
                --  if they are not followed by a construct which can reference
-               --  and export them. The Is_Public flag is reset on top level
-               --  entities only as anything nested is local to its context.
-               --  Likewise for subprograms, but we work harder for them.
-
+               --  and export them. Likewise for subprograms but we work harder
+               --  for them to see whether they are referenced on an individual
+               --  basis by looking into the table of referenced subprograms.
+               --  But we cannot say anything for entities declared in nested
+               --  instances because instantiations are not done yet so the
+               --  bodies are not visible and could contain references to them.
                elsif Nkind_In (Decl, N_Exception_Declaration,
                                      N_Object_Declaration,
                                      N_Object_Renaming_Declaration,
@@ -442,12 +465,12 @@ package body Sem_Ch7 is
                then
                   Decl_Id := Defining_Entity (Decl);
 
-                  if Top_Level
+                  if not In_Nested_Instance
                     and then not Is_Imported (Decl_Id)
                     and then not Is_Exported (Decl_Id)
                     and then No (Interface_Name (Decl_Id))
                     and then
-                      (not Has_Non_Subprograms_Referencer
+                      (not Has_Referencer_Of_Non_Subprograms
                         or else (Nkind (Decl) = N_Subprogram_Declaration
                                   and then not Subprogram_Table.Get (Decl_Id)))
                   then
@@ -475,7 +498,7 @@ package body Sem_Ch7 is
                Prev (Decl);
             end loop;
 
-            return Has_Non_Subprograms_Referencer;
+            return Has_Referencer_Of_Non_Subprograms;
          end Has_Referencer;
 
          -------------------------
@@ -609,7 +632,7 @@ package body Sem_Ch7 is
 
          Traversed_Table.Reset;
          Subprogram_Table.Reset;
-         Discard := Has_Referencer (Decls, Top_Level => True);
+         Discard := Has_Referencer (Decls, False, False);
       end Hide_Public_Entities;
 
       ----------------------------------