Mercurial > hg > CbC > CbC_gcc
view gcc/ada/exp_unst.adb @ 111:04ced10e8804
gcc 7
| author | kono |
|---|---|
| date | Fri, 27 Oct 2017 22:46:09 +0900 |
| parents | |
| children | 84e7813d76e9 |
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------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- E X P _ U N S T -- -- -- -- B o d y -- -- -- -- Copyright (C) 2014-2017, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 3, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING3. If not, go to -- -- http://www.gnu.org/licenses for a complete copy of the license. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ with Atree; use Atree; with Debug; use Debug; with Einfo; use Einfo; with Elists; use Elists; with Lib; use Lib; with Namet; use Namet; with Nlists; use Nlists; with Nmake; use Nmake; with Opt; with Output; use Output; with Rtsfind; use Rtsfind; with Sem; use Sem; with Sem_Aux; use Sem_Aux; with Sem_Ch8; use Sem_Ch8; with Sem_Mech; use Sem_Mech; with Sem_Res; use Sem_Res; with Sem_Util; use Sem_Util; with Sinfo; use Sinfo; with Sinput; use Sinput; with Snames; use Snames; with Tbuild; use Tbuild; with Uintp; use Uintp; package body Exp_Unst is ----------------------- -- Local Subprograms -- ----------------------- procedure Unnest_Subprogram (Subp : Entity_Id; Subp_Body : Node_Id); -- Subp is a library-level subprogram which has nested subprograms, and -- Subp_Body is the corresponding N_Subprogram_Body node. This procedure -- declares the AREC types and objects, adds assignments to the AREC record -- as required, defines the xxxPTR types for uplevel referenced objects, -- adds the ARECP parameter to all nested subprograms which need it, and -- modifies all uplevel references appropriately. ----------- -- Calls -- ----------- -- Table to record calls within the nest being analyzed. These are the -- calls which may need to have an AREC actual added. This table is built -- new for each subprogram nest and cleared at the end of processing each -- subprogram nest. type Call_Entry is record N : Node_Id; -- The actual call Caller : Entity_Id; -- Entity of the subprogram containing the call (can be at any level) Callee : Entity_Id; -- Entity of the subprogram called (always at level 2 or higher). Note -- that in accordance with the basic rules of nesting, the level of To -- is either less than or equal to the level of From, or one greater. end record; package Calls is new Table.Table ( Table_Component_Type => Call_Entry, Table_Index_Type => Nat, Table_Low_Bound => 1, Table_Initial => 100, Table_Increment => 200, Table_Name => "Unnest_Calls"); -- Records each call within the outer subprogram and all nested subprograms -- that are to other subprograms nested within the outer subprogram. These -- are the calls that may need an additional parameter. procedure Append_Unique_Call (Call : Call_Entry); -- Append a call entry to the Calls table. A check is made to see if the -- table already contains this entry and if so it has no effect. ----------- -- Urefs -- ----------- -- Table to record explicit uplevel references to objects (variables, -- constants, formal parameters). These are the references that will -- need rewriting to use the activation table (AREC) pointers. Also -- included are implicit and explicit uplevel references to types, but -- these do not get rewritten by the front end. This table is built new -- for each subprogram nest and cleared at the end of processing each -- subprogram nest. type Uref_Entry is record Ref : Node_Id; -- The reference itself. For objects this is always an entity reference -- and the referenced entity will have its Is_Uplevel_Referenced_Entity -- flag set and will appear in the Uplevel_Referenced_Entities list of -- the subprogram declaring this entity. Ent : Entity_Id; -- The Entity_Id of the uplevel referenced object or type Caller : Entity_Id; -- The entity for the subprogram immediately containing this entity Callee : Entity_Id; -- The entity for the subprogram containing the referenced entity. Note -- that the level of Callee must be less than the level of Caller, since -- this is an uplevel reference. end record; package Urefs is new Table.Table ( Table_Component_Type => Uref_Entry, Table_Index_Type => Nat, Table_Low_Bound => 1, Table_Initial => 100, Table_Increment => 200, Table_Name => "Unnest_Urefs"); ------------------------ -- Append_Unique_Call -- ------------------------ procedure Append_Unique_Call (Call : Call_Entry) is begin for J in Calls.First .. Calls.Last loop if Calls.Table (J) = Call then return; end if; end loop; Calls.Append (Call); end Append_Unique_Call; --------------- -- Get_Level -- --------------- function Get_Level (Subp : Entity_Id; Sub : Entity_Id) return Nat is Lev : Nat; S : Entity_Id; begin Lev := 1; S := Sub; loop if S = Subp then return Lev; else Lev := Lev + 1; S := Enclosing_Subprogram (S); end if; end loop; end Get_Level; ---------------- -- Subp_Index -- ---------------- function Subp_Index (Sub : Entity_Id) return SI_Type is E : Entity_Id := Sub; begin pragma Assert (Is_Subprogram (E)); if Subps_Index (E) = Uint_0 then E := Ultimate_Alias (E); if Ekind (E) = E_Function and then Rewritten_For_C (E) and then Present (Corresponding_Procedure (E)) then E := Corresponding_Procedure (E); end if; end if; pragma Assert (Subps_Index (E) /= Uint_0); return SI_Type (UI_To_Int (Subps_Index (E))); end Subp_Index; ----------------------- -- Unnest_Subprogram -- ----------------------- procedure Unnest_Subprogram (Subp : Entity_Id; Subp_Body : Node_Id) is function AREC_Name (J : Pos; S : String) return Name_Id; -- Returns name for string ARECjS, where j is the decimal value of j function Enclosing_Subp (Subp : SI_Type) return SI_Type; -- Subp is the index of a subprogram which has a Lev greater than 1. -- This function returns the index of the enclosing subprogram which -- will have a Lev value one less than this. function Img_Pos (N : Pos) return String; -- Return image of N without leading blank function Upref_Name (Ent : Entity_Id; Index : Pos; Clist : List_Id) return Name_Id; -- This function returns the name to be used in the activation record to -- reference the variable uplevel. Clist is the list of components that -- have been created in the activation record so far. Normally the name -- is just a copy of the Chars field of the entity. The exception is -- when the name has already been used, in which case we suffix the name -- with the index value Index to avoid duplication. This happens with -- declare blocks and generic parameters at least. --------------- -- AREC_Name -- --------------- function AREC_Name (J : Pos; S : String) return Name_Id is begin return Name_Find ("AREC" & Img_Pos (J) & S); end AREC_Name; -------------------- -- Enclosing_Subp -- -------------------- function Enclosing_Subp (Subp : SI_Type) return SI_Type is STJ : Subp_Entry renames Subps.Table (Subp); Ret : constant SI_Type := Subp_Index (Enclosing_Subprogram (STJ.Ent)); begin pragma Assert (STJ.Lev > 1); pragma Assert (Subps.Table (Ret).Lev = STJ.Lev - 1); return Ret; end Enclosing_Subp; ------------- -- Img_Pos -- ------------- function Img_Pos (N : Pos) return String is Buf : String (1 .. 20); Ptr : Natural; NV : Nat; begin Ptr := Buf'Last; NV := N; while NV /= 0 loop Buf (Ptr) := Character'Val (48 + NV mod 10); Ptr := Ptr - 1; NV := NV / 10; end loop; return Buf (Ptr + 1 .. Buf'Last); end Img_Pos; ---------------- -- Upref_Name -- ---------------- function Upref_Name (Ent : Entity_Id; Index : Pos; Clist : List_Id) return Name_Id is C : Node_Id; begin C := First (Clist); loop if No (C) then return Chars (Ent); elsif Chars (Defining_Identifier (C)) = Chars (Ent) then return Name_Find (Get_Name_String (Chars (Ent)) & Img_Pos (Index)); else Next (C); end if; end loop; end Upref_Name; -- Start of processing for Unnest_Subprogram begin -- Nothing to do inside a generic (all processing is for instance) if Inside_A_Generic then return; end if; -- At least for now, do not unnest anything but main source unit if not In_Extended_Main_Source_Unit (Subp_Body) then return; end if; -- This routine is called late, after the scope stack is gone. The -- following creates a suitable dummy scope stack to be used for the -- analyze/expand calls made from this routine. Push_Scope (Subp); -- First step, we must mark all nested subprograms that require a static -- link (activation record) because either they contain explicit uplevel -- references (as indicated by Is_Uplevel_Referenced_Entity being set at -- this point), or they make calls to other subprograms in the same nest -- that require a static link (in which case we set this flag). -- This is a recursive definition, and to implement this, we have to -- build a call graph for the set of nested subprograms, and then go -- over this graph to implement recursively the invariant that if a -- subprogram has a call to a subprogram requiring a static link, then -- the calling subprogram requires a static link. -- First populate the above tables Subps_First := Subps.Last + 1; Calls.Init; Urefs.Init; Build_Tables : declare Current_Subprogram : Entity_Id; -- When we scan a subprogram body, we set Current_Subprogram to the -- corresponding entity. This gets recursively saved and restored. function Visit_Node (N : Node_Id) return Traverse_Result; -- Visit a single node in Subp ----------- -- Visit -- ----------- procedure Visit is new Traverse_Proc (Visit_Node); -- Used to traverse the body of Subp, populating the tables ---------------- -- Visit_Node -- ---------------- function Visit_Node (N : Node_Id) return Traverse_Result is Ent : Entity_Id; Caller : Entity_Id; Callee : Entity_Id; procedure Check_Static_Type (T : Entity_Id; DT : in out Boolean); -- Given a type T, checks if it is a static type defined as a type -- with no dynamic bounds in sight. If so, the only action is to -- set Is_Static_Type True for T. If T is not a static type, then -- all types with dynamic bounds associated with T are detected, -- and their bounds are marked as uplevel referenced if not at the -- library level, and DT is set True. procedure Note_Uplevel_Ref (E : Entity_Id; Caller : Entity_Id; Callee : Entity_Id); -- Called when we detect an explicit or implicit uplevel reference -- from within Caller to entity E declared in Callee. E can be a -- an object or a type. ----------------------- -- Check_Static_Type -- ----------------------- procedure Check_Static_Type (T : Entity_Id; DT : in out Boolean) is procedure Note_Uplevel_Bound (N : Node_Id); -- N is the bound of a dynamic type. This procedure notes that -- this bound is uplevel referenced, it can handle references -- to entities (typically _FIRST and _LAST entities), and also -- attribute references of the form T'name (name is typically -- FIRST or LAST) where T is the uplevel referenced bound. ------------------------ -- Note_Uplevel_Bound -- ------------------------ procedure Note_Uplevel_Bound (N : Node_Id) is begin -- Entity name case if Is_Entity_Name (N) then if Present (Entity (N)) then Note_Uplevel_Ref (E => Entity (N), Caller => Current_Subprogram, Callee => Enclosing_Subprogram (Entity (N))); end if; -- Attribute case elsif Nkind (N) = N_Attribute_Reference then Note_Uplevel_Bound (Prefix (N)); end if; end Note_Uplevel_Bound; -- Start of processing for Check_Static_Type begin -- If already marked static, immediate return if Is_Static_Type (T) then return; end if; -- If the type is at library level, always consider it static, -- since such uplevel references are irrelevant. if Is_Library_Level_Entity (T) then Set_Is_Static_Type (T); return; end if; -- Otherwise figure out what the story is with this type -- For a scalar type, check bounds if Is_Scalar_Type (T) then -- If both bounds static, then this is a static type declare LB : constant Node_Id := Type_Low_Bound (T); UB : constant Node_Id := Type_High_Bound (T); begin if not Is_Static_Expression (LB) then Note_Uplevel_Bound (LB); DT := True; end if; if not Is_Static_Expression (UB) then Note_Uplevel_Bound (UB); DT := True; end if; end; -- For record type, check all components elsif Is_Record_Type (T) then declare C : Entity_Id; begin C := First_Component_Or_Discriminant (T); while Present (C) loop Check_Static_Type (Etype (C), DT); Next_Component_Or_Discriminant (C); end loop; end; -- For array type, check index types and component type elsif Is_Array_Type (T) then declare IX : Node_Id; begin Check_Static_Type (Component_Type (T), DT); IX := First_Index (T); while Present (IX) loop Check_Static_Type (Etype (IX), DT); Next_Index (IX); end loop; end; -- For private type, examine whether full view is static elsif Is_Private_Type (T) and then Present (Full_View (T)) then Check_Static_Type (Full_View (T), DT); if Is_Static_Type (Full_View (T)) then Set_Is_Static_Type (T); end if; -- For now, ignore other types else return; end if; if not DT then Set_Is_Static_Type (T); end if; end Check_Static_Type; ---------------------- -- Note_Uplevel_Ref -- ---------------------- procedure Note_Uplevel_Ref (E : Entity_Id; Caller : Entity_Id; Callee : Entity_Id) is begin -- Nothing to do for static type if Is_Static_Type (E) then return; end if; -- Nothing to do if Caller and Callee are the same if Caller = Callee then return; -- Callee may be a function that returns an array, and that has -- been rewritten as a procedure. If caller is that procedure, -- nothing to do either. elsif Ekind (Callee) = E_Function and then Rewritten_For_C (Callee) and then Corresponding_Procedure (Callee) = Caller then return; end if; -- We have a new uplevel referenced entity -- All we do at this stage is to add the uplevel reference to -- the table. It's too early to do anything else, since this -- uplevel reference may come from an unreachable subprogram -- in which case the entry will be deleted. Urefs.Append ((N, E, Caller, Callee)); end Note_Uplevel_Ref; -- Start of processing for Visit_Node begin -- Record a call if Nkind_In (N, N_Procedure_Call_Statement, N_Function_Call) -- We are only interested in direct calls, not indirect calls -- (where Name (N) is an explicit dereference) at least for now! and then Nkind (Name (N)) in N_Has_Entity then Ent := Entity (Name (N)); -- We are only interested in calls to subprograms nested -- within Subp. Calls to Subp itself or to subprograms that -- are outside the nested structure do not affect us. if Scope_Within (Ent, Subp) then -- Ignore calls to imported routines if Is_Imported (Ent) then null; -- Here we have a call to keep and analyze else -- Both caller and callee must be subprograms if Is_Subprogram (Ent) then Append_Unique_Call ((N, Current_Subprogram, Ent)); end if; end if; end if; -- Record a subprogram. We record a subprogram body that acts as -- a spec. Otherwise we record a subprogram declaration, providing -- that it has a corresponding body we can get hold of. The case -- of no corresponding body being available is ignored for now. elsif Nkind (N) = N_Subprogram_Body then Ent := Unique_Defining_Entity (N); -- Ignore generic subprogram if Is_Generic_Subprogram (Ent) then return Skip; end if; -- Make new entry in subprogram table if not already made declare L : constant Nat := Get_Level (Subp, Ent); begin Subps.Append ((Ent => Ent, Bod => N, Lev => L, Reachable => False, Uplevel_Ref => L, Declares_AREC => False, Uents => No_Elist, Last => 0, ARECnF => Empty, ARECn => Empty, ARECnT => Empty, ARECnPT => Empty, ARECnP => Empty, ARECnU => Empty)); Set_Subps_Index (Ent, UI_From_Int (Subps.Last)); end; -- We make a recursive call to scan the subprogram body, so -- that we can save and restore Current_Subprogram. declare Save_CS : constant Entity_Id := Current_Subprogram; Decl : Node_Id; begin Current_Subprogram := Ent; -- Scan declarations Decl := First (Declarations (N)); while Present (Decl) loop Visit (Decl); Next (Decl); end loop; -- Scan statements Visit (Handled_Statement_Sequence (N)); -- Restore current subprogram setting Current_Subprogram := Save_CS; end; -- Now at this level, return skipping the subprogram body -- descendants, since we already took care of them! return Skip; -- Record an uplevel reference elsif Nkind (N) in N_Has_Entity and then Present (Entity (N)) then Ent := Entity (N); -- Only interested in entities declared within our nest if not Is_Library_Level_Entity (Ent) and then Scope_Within_Or_Same (Scope (Ent), Subp) -- Skip entities defined in inlined subprograms and then Chars (Enclosing_Subprogram (Ent)) /= Name_uParent and then -- Constants and variables are interesting (Ekind_In (Ent, E_Constant, E_Variable) -- Formals are interesting, but not if being used as mere -- names of parameters for name notation calls. or else (Is_Formal (Ent) and then not (Nkind (Parent (N)) = N_Parameter_Association and then Selector_Name (Parent (N)) = N)) -- Types other than known Is_Static types are interesting or else (Is_Type (Ent) and then not Is_Static_Type (Ent))) then -- Here we have a possible interesting uplevel reference if Is_Type (Ent) then declare DT : Boolean := False; begin Check_Static_Type (Ent, DT); if Is_Static_Type (Ent) then return OK; end if; end; end if; Caller := Current_Subprogram; Callee := Enclosing_Subprogram (Ent); if Callee /= Caller and then not Is_Static_Type (Ent) then Note_Uplevel_Ref (Ent, Caller, Callee); end if; end if; -- If we have a body stub, visit the associated subunit elsif Nkind (N) in N_Body_Stub then Visit (Library_Unit (N)); -- Skip generic declarations elsif Nkind (N) in N_Generic_Declaration then return Skip; -- Skip generic package body elsif Nkind (N) = N_Package_Body and then Present (Corresponding_Spec (N)) and then Ekind (Corresponding_Spec (N)) = E_Generic_Package then return Skip; end if; -- Fall through to continue scanning children of this node return OK; end Visit_Node; -- Start of processing for Build_Tables begin -- Traverse the body to get subprograms, calls and uplevel references Visit (Subp_Body); end Build_Tables; -- Now do the first transitive closure which determines which -- subprograms in the nest are actually reachable. Reachable_Closure : declare Modified : Boolean; begin Subps.Table (Subps_First).Reachable := True; -- We use a simple minded algorithm as follows (obviously this can -- be done more efficiently, using one of the standard algorithms -- for efficient transitive closure computation, but this is simple -- and most likely fast enough that its speed does not matter). -- Repeatedly scan the list of calls. Any time we find a call from -- A to B, where A is reachable, but B is not, then B is reachable, -- and note that we have made a change by setting Modified True. We -- repeat this until we make a pass with no modifications. Outer : loop Modified := False; Inner : for J in Calls.First .. Calls.Last loop declare CTJ : Call_Entry renames Calls.Table (J); SINF : constant SI_Type := Subp_Index (CTJ.Caller); SINT : constant SI_Type := Subp_Index (CTJ.Callee); SUBF : Subp_Entry renames Subps.Table (SINF); SUBT : Subp_Entry renames Subps.Table (SINT); begin if SUBF.Reachable and then not SUBT.Reachable then SUBT.Reachable := True; Modified := True; end if; end; end loop Inner; exit Outer when not Modified; end loop Outer; end Reachable_Closure; -- Remove calls from unreachable subprograms declare New_Index : Nat; begin New_Index := 0; for J in Calls.First .. Calls.Last loop declare CTJ : Call_Entry renames Calls.Table (J); SINF : constant SI_Type := Subp_Index (CTJ.Caller); SINT : constant SI_Type := Subp_Index (CTJ.Callee); SUBF : Subp_Entry renames Subps.Table (SINF); SUBT : Subp_Entry renames Subps.Table (SINT); begin if SUBF.Reachable then pragma Assert (SUBT.Reachable); New_Index := New_Index + 1; Calls.Table (New_Index) := Calls.Table (J); end if; end; end loop; Calls.Set_Last (New_Index); end; -- Remove uplevel references from unreachable subprograms declare New_Index : Nat; begin New_Index := 0; for J in Urefs.First .. Urefs.Last loop declare URJ : Uref_Entry renames Urefs.Table (J); SINF : constant SI_Type := Subp_Index (URJ.Caller); SINT : constant SI_Type := Subp_Index (URJ.Callee); SUBF : Subp_Entry renames Subps.Table (SINF); SUBT : Subp_Entry renames Subps.Table (SINT); S : Entity_Id; begin -- Keep reachable reference if SUBF.Reachable then New_Index := New_Index + 1; Urefs.Table (New_Index) := Urefs.Table (J); -- And since we know we are keeping this one, this is a good -- place to fill in information for a good reference. -- Mark all enclosing subprograms need to declare AREC S := URJ.Caller; loop S := Enclosing_Subprogram (S); -- if we are at the top level, as can happen with -- references to formals in aspects of nested subprogram -- declarations, there are no further subprograms to -- mark as requiring activation records. exit when No (S); Subps.Table (Subp_Index (S)).Declares_AREC := True; exit when S = URJ.Callee; end loop; -- Add to list of uplevel referenced entities for Callee. -- We do not add types to this list, only actual references -- to objects that will be referenced uplevel, and we use -- the flag Is_Uplevel_Referenced_Entity to avoid making -- duplicate entries in the list. if not Is_Uplevel_Referenced_Entity (URJ.Ent) then Set_Is_Uplevel_Referenced_Entity (URJ.Ent); if not Is_Type (URJ.Ent) then Append_New_Elmt (URJ.Ent, SUBT.Uents); end if; end if; -- And set uplevel indication for caller if SUBT.Lev < SUBF.Uplevel_Ref then SUBF.Uplevel_Ref := SUBT.Lev; end if; end if; end; end loop; Urefs.Set_Last (New_Index); end; -- Remove unreachable subprograms from Subps table. Note that we do -- this after eliminating entries from the other two tables, since -- those elimination steps depend on referencing the Subps table. declare New_SI : SI_Type; begin New_SI := Subps_First - 1; for J in Subps_First .. Subps.Last loop declare STJ : Subp_Entry renames Subps.Table (J); Spec : Node_Id; Decl : Node_Id; begin -- Subprogram is reachable, copy and reset index if STJ.Reachable then New_SI := New_SI + 1; Subps.Table (New_SI) := STJ; Set_Subps_Index (STJ.Ent, UI_From_Int (New_SI)); -- Subprogram is not reachable else -- Clear index, since no longer active Set_Subps_Index (Subps.Table (J).Ent, Uint_0); -- Output debug information if -gnatd.3 set if Debug_Flag_Dot_3 then Write_Str ("Eliminate "); Write_Name (Chars (Subps.Table (J).Ent)); Write_Str (" at "); Write_Location (Sloc (Subps.Table (J).Ent)); Write_Str (" (not referenced)"); Write_Eol; end if; -- Rewrite declaration and body to null statements Spec := Corresponding_Spec (STJ.Bod); if Present (Spec) then Decl := Parent (Declaration_Node (Spec)); Rewrite (Decl, Make_Null_Statement (Sloc (Decl))); end if; Rewrite (STJ.Bod, Make_Null_Statement (Sloc (STJ.Bod))); end if; end; end loop; Subps.Set_Last (New_SI); end; -- Now it is time for the second transitive closure, which follows calls -- and makes sure that A calls B, and B has uplevel references, then A -- is also marked as having uplevel references. Closure_Uplevel : declare Modified : Boolean; begin -- We use a simple minded algorithm as follows (obviously this can -- be done more efficiently, using one of the standard algorithms -- for efficient transitive closure computation, but this is simple -- and most likely fast enough that its speed does not matter). -- Repeatedly scan the list of calls. Any time we find a call from -- A to B, where B has uplevel references, make sure that A is marked -- as having at least the same level of uplevel referencing. Outer2 : loop Modified := False; Inner2 : for J in Calls.First .. Calls.Last loop declare CTJ : Call_Entry renames Calls.Table (J); SINF : constant SI_Type := Subp_Index (CTJ.Caller); SINT : constant SI_Type := Subp_Index (CTJ.Callee); SUBF : Subp_Entry renames Subps.Table (SINF); SUBT : Subp_Entry renames Subps.Table (SINT); begin if SUBT.Lev > SUBT.Uplevel_Ref and then SUBF.Uplevel_Ref > SUBT.Uplevel_Ref then SUBF.Uplevel_Ref := SUBT.Uplevel_Ref; Modified := True; end if; end; end loop Inner2; exit Outer2 when not Modified; end loop Outer2; end Closure_Uplevel; -- We have one more step before the tables are complete. An uplevel -- call from subprogram A to subprogram B where subprogram B has uplevel -- references is in effect an uplevel reference, and must arrange for -- the proper activation link to be passed. for J in Calls.First .. Calls.Last loop declare CTJ : Call_Entry renames Calls.Table (J); SINF : constant SI_Type := Subp_Index (CTJ.Caller); SINT : constant SI_Type := Subp_Index (CTJ.Callee); SUBF : Subp_Entry renames Subps.Table (SINF); SUBT : Subp_Entry renames Subps.Table (SINT); A : Entity_Id; begin -- If callee has uplevel references if SUBT.Uplevel_Ref < SUBT.Lev -- And this is an uplevel call and then SUBT.Lev < SUBF.Lev then -- We need to arrange for finding the uplink A := CTJ.Caller; loop A := Enclosing_Subprogram (A); Subps.Table (Subp_Index (A)).Declares_AREC := True; exit when A = CTJ.Callee; -- In any case exit when we get to the outer level. This -- happens in some odd cases with generics (in particular -- sem_ch3.adb does not compile without this kludge ???). exit when A = Subp; end loop; end if; end; end loop; -- The tables are now complete, so we can record the last index in the -- Subps table for later reference in Cprint. Subps.Table (Subps_First).Last := Subps.Last; -- Next step, create the entities for code we will insert. We do this -- at the start so that all the entities are defined, regardless of the -- order in which we do the code insertions. Create_Entities : for J in Subps_First .. Subps.Last loop declare STJ : Subp_Entry renames Subps.Table (J); Loc : constant Source_Ptr := Sloc (STJ.Bod); begin -- First we create the ARECnF entity for the additional formal for -- all subprograms which need an activation record passed. if STJ.Uplevel_Ref < STJ.Lev then STJ.ARECnF := Make_Defining_Identifier (Loc, Chars => AREC_Name (J, "F")); end if; -- Define the AREC entities for the activation record if needed if STJ.Declares_AREC then STJ.ARECn := Make_Defining_Identifier (Loc, AREC_Name (J, "")); STJ.ARECnT := Make_Defining_Identifier (Loc, AREC_Name (J, "T")); STJ.ARECnPT := Make_Defining_Identifier (Loc, AREC_Name (J, "PT")); STJ.ARECnP := Make_Defining_Identifier (Loc, AREC_Name (J, "P")); -- Define uplink component entity if inner nesting case if Present (STJ.ARECnF) then STJ.ARECnU := Make_Defining_Identifier (Loc, AREC_Name (J, "U")); end if; end if; end; end loop Create_Entities; -- Loop through subprograms Subp_Loop : declare Addr : constant Entity_Id := RTE (RE_Address); begin for J in Subps_First .. Subps.Last loop declare STJ : Subp_Entry renames Subps.Table (J); begin -- First add the extra formal if needed. This applies to all -- nested subprograms that require an activation record to be -- passed, as indicated by ARECnF being defined. if Present (STJ.ARECnF) then -- Here we need the extra formal. We do the expansion and -- analysis of this manually, since it is fairly simple, -- and it is not obvious how we can get what we want if we -- try to use the normal Analyze circuit. Add_Extra_Formal : declare Encl : constant SI_Type := Enclosing_Subp (J); STJE : Subp_Entry renames Subps.Table (Encl); -- Index and Subp_Entry for enclosing routine Form : constant Entity_Id := STJ.ARECnF; -- The formal to be added. Note that n here is one less -- than the level of the subprogram itself (STJ.Ent). procedure Add_Form_To_Spec (F : Entity_Id; S : Node_Id); -- S is an N_Function/Procedure_Specification node, and F -- is the new entity to add to this subprogramn spec as -- the last Extra_Formal. ---------------------- -- Add_Form_To_Spec -- ---------------------- procedure Add_Form_To_Spec (F : Entity_Id; S : Node_Id) is Sub : constant Entity_Id := Defining_Entity (S); Ent : Entity_Id; begin -- Case of at least one Extra_Formal is present, set -- ARECnF as the new last entry in the list. if Present (Extra_Formals (Sub)) then Ent := Extra_Formals (Sub); while Present (Extra_Formal (Ent)) loop Ent := Extra_Formal (Ent); end loop; Set_Extra_Formal (Ent, F); -- No Extra formals present else Set_Extra_Formals (Sub, F); Ent := Last_Formal (Sub); if Present (Ent) then Set_Extra_Formal (Ent, F); end if; end if; end Add_Form_To_Spec; -- Start of processing for Add_Extra_Formal begin -- Decorate the new formal entity Set_Scope (Form, STJ.Ent); Set_Ekind (Form, E_In_Parameter); Set_Etype (Form, STJE.ARECnPT); Set_Mechanism (Form, By_Copy); Set_Never_Set_In_Source (Form, True); Set_Analyzed (Form, True); Set_Comes_From_Source (Form, False); -- Case of only body present if Acts_As_Spec (STJ.Bod) then Add_Form_To_Spec (Form, Specification (STJ.Bod)); -- Case of separate spec else Add_Form_To_Spec (Form, Parent (STJ.Ent)); end if; end Add_Extra_Formal; end if; -- Processing for subprograms that declare an activation record if Present (STJ.ARECn) then -- Local declarations for one such subprogram declare Loc : constant Source_Ptr := Sloc (STJ.Bod); Clist : List_Id; Comp : Entity_Id; Decl_ARECnT : Node_Id; Decl_ARECnPT : Node_Id; Decl_ARECn : Node_Id; Decl_ARECnP : Node_Id; -- Declaration nodes for the AREC entities we build Decl_Assign : Node_Id; -- Assigment to set uplink, Empty if none Decls : List_Id; -- List of new declarations we create begin -- Build list of component declarations for ARECnT Clist := Empty_List; -- If we are in a subprogram that has a static link that -- is passed in (as indicated by ARECnF being defined), -- then include ARECnU : ARECmPT where ARECmPT comes from -- the level one higher than the current level, and the -- entity ARECnPT comes from the enclosing subprogram. if Present (STJ.ARECnF) then declare STJE : Subp_Entry renames Subps.Table (Enclosing_Subp (J)); begin Append_To (Clist, Make_Component_Declaration (Loc, Defining_Identifier => STJ.ARECnU, Component_Definition => Make_Component_Definition (Loc, Subtype_Indication => New_Occurrence_Of (STJE.ARECnPT, Loc)))); end; end if; -- Add components for uplevel referenced entities if Present (STJ.Uents) then declare Elmt : Elmt_Id; Uent : Entity_Id; Indx : Nat; -- 1's origin of index in list of elements. This is -- used to uniquify names if needed in Upref_Name. begin Elmt := First_Elmt (STJ.Uents); Indx := 0; while Present (Elmt) loop Uent := Node (Elmt); Indx := Indx + 1; Comp := Make_Defining_Identifier (Loc, Chars => Upref_Name (Uent, Indx, Clist)); Set_Activation_Record_Component (Uent, Comp); Append_To (Clist, Make_Component_Declaration (Loc, Defining_Identifier => Comp, Component_Definition => Make_Component_Definition (Loc, Subtype_Indication => New_Occurrence_Of (Addr, Loc)))); Next_Elmt (Elmt); end loop; end; end if; -- Now we can insert the AREC declarations into the body -- type ARECnT is record .. end record; -- pragma Suppress_Initialization (ARECnT); -- Note that we need to set the Suppress_Initialization -- flag after Decl_ARECnT has been analyzed. Decl_ARECnT := Make_Full_Type_Declaration (Loc, Defining_Identifier => STJ.ARECnT, Type_Definition => Make_Record_Definition (Loc, Component_List => Make_Component_List (Loc, Component_Items => Clist))); Decls := New_List (Decl_ARECnT); -- type ARECnPT is access all ARECnT; Decl_ARECnPT := Make_Full_Type_Declaration (Loc, Defining_Identifier => STJ.ARECnPT, Type_Definition => Make_Access_To_Object_Definition (Loc, All_Present => True, Subtype_Indication => New_Occurrence_Of (STJ.ARECnT, Loc))); Append_To (Decls, Decl_ARECnPT); -- ARECn : aliased ARECnT; Decl_ARECn := Make_Object_Declaration (Loc, Defining_Identifier => STJ.ARECn, Aliased_Present => True, Object_Definition => New_Occurrence_Of (STJ.ARECnT, Loc)); Append_To (Decls, Decl_ARECn); -- ARECnP : constant ARECnPT := ARECn'Access; Decl_ARECnP := Make_Object_Declaration (Loc, Defining_Identifier => STJ.ARECnP, Constant_Present => True, Object_Definition => New_Occurrence_Of (STJ.ARECnPT, Loc), Expression => Make_Attribute_Reference (Loc, Prefix => New_Occurrence_Of (STJ.ARECn, Loc), Attribute_Name => Name_Access)); Append_To (Decls, Decl_ARECnP); -- If we are in a subprogram that has a static link that -- is passed in (as indicated by ARECnF being defined), -- then generate ARECn.ARECmU := ARECmF where m is -- one less than the current level to set the uplink. if Present (STJ.ARECnF) then Decl_Assign := Make_Assignment_Statement (Loc, Name => Make_Selected_Component (Loc, Prefix => New_Occurrence_Of (STJ.ARECn, Loc), Selector_Name => New_Occurrence_Of (STJ.ARECnU, Loc)), Expression => New_Occurrence_Of (STJ.ARECnF, Loc)); Append_To (Decls, Decl_Assign); else Decl_Assign := Empty; end if; Prepend_List_To (Declarations (STJ.Bod), Decls); -- Analyze the newly inserted declarations. Note that we -- do not need to establish the whole scope stack, since -- we have already set all entity fields (so there will -- be no searching of upper scopes to resolve names). But -- we do set the scope of the current subprogram, so that -- newly created entities go in the right entity chain. -- We analyze with all checks suppressed (since we do -- not expect any exceptions). Push_Scope (STJ.Ent); Analyze (Decl_ARECnT, Suppress => All_Checks); -- Note that we need to call Set_Suppress_Initialization -- after Decl_ARECnT has been analyzed, but before -- analyzing Decl_ARECnP so that the flag is properly -- taking into account. Set_Suppress_Initialization (STJ.ARECnT); Analyze (Decl_ARECnPT, Suppress => All_Checks); Analyze (Decl_ARECn, Suppress => All_Checks); Analyze (Decl_ARECnP, Suppress => All_Checks); if Present (Decl_Assign) then Analyze (Decl_Assign, Suppress => All_Checks); end if; Pop_Scope; -- Next step, for each uplevel referenced entity, add -- assignment operations to set the component in the -- activation record. if Present (STJ.Uents) then declare Elmt : Elmt_Id; begin Elmt := First_Elmt (STJ.Uents); while Present (Elmt) loop declare Ent : constant Entity_Id := Node (Elmt); Loc : constant Source_Ptr := Sloc (Ent); Dec : constant Node_Id := Declaration_Node (Ent); Ins : Node_Id; Asn : Node_Id; begin -- For parameters, we insert the assignment -- right after the declaration of ARECnP. -- For all other entities, we insert -- the assignment immediately after -- the declaration of the entity. -- Note: we don't need to mark the entity -- as being aliased, because the address -- attribute will mark it as Address_Taken, -- and that is good enough. if Is_Formal (Ent) then Ins := Decl_ARECnP; else Ins := Dec; end if; -- Build and insert the assignment: -- ARECn.nam := nam'Address Asn := Make_Assignment_Statement (Loc, Name => Make_Selected_Component (Loc, Prefix => New_Occurrence_Of (STJ.ARECn, Loc), Selector_Name => New_Occurrence_Of (Activation_Record_Component (Ent), Loc)), Expression => Make_Attribute_Reference (Loc, Prefix => New_Occurrence_Of (Ent, Loc), Attribute_Name => Name_Address)); Insert_After (Ins, Asn); -- Analyze the assignment statement. We do -- not need to establish the relevant scope -- stack entries here, because we have -- already set the correct entity references, -- so no name resolution is required, and no -- new entities are created, so we don't even -- need to set the current scope. -- We analyze with all checks suppressed -- (since we do not expect any exceptions). Analyze (Asn, Suppress => All_Checks); end; Next_Elmt (Elmt); end loop; end; end if; end; end if; end; end loop; end Subp_Loop; -- Next step, process uplevel references. This has to be done in a -- separate pass, after completing the processing in Sub_Loop because we -- need all the AREC declarations generated, inserted, and analyzed so -- that the uplevel references can be successfully analyzed. Uplev_Refs : for J in Urefs.First .. Urefs.Last loop declare UPJ : Uref_Entry renames Urefs.Table (J); begin -- Ignore type references, these are implicit references that do -- not need rewriting (e.g. the appearence in a conversion). if Is_Type (UPJ.Ent) then goto Continue; end if; -- Also ignore uplevel references to bounds of types that come -- from the original type reference. if Is_Entity_Name (UPJ.Ref) and then Present (Entity (UPJ.Ref)) and then Is_Type (Entity (UPJ.Ref)) then goto Continue; end if; -- Rewrite one reference Rewrite_One_Ref : declare Loc : constant Source_Ptr := Sloc (UPJ.Ref); -- Source location for the reference Typ : constant Entity_Id := Etype (UPJ.Ent); -- The type of the referenced entity Atyp : constant Entity_Id := Get_Actual_Subtype (UPJ.Ref); -- The actual subtype of the reference RS_Caller : constant SI_Type := Subp_Index (UPJ.Caller); -- Subp_Index for caller containing reference STJR : Subp_Entry renames Subps.Table (RS_Caller); -- Subp_Entry for subprogram containing reference RS_Callee : constant SI_Type := Subp_Index (UPJ.Callee); -- Subp_Index for subprogram containing referenced entity STJE : Subp_Entry renames Subps.Table (RS_Callee); -- Subp_Entry for subprogram containing referenced entity Pfx : Node_Id; Comp : Entity_Id; SI : SI_Type; begin -- Ignore if no ARECnF entity for enclosing subprogram which -- probably happens as a result of not properly treating -- instance bodies. To be examined ??? -- If this test is omitted, then the compilation of freeze.adb -- and inline.adb fail in unnesting mode. if No (STJR.ARECnF) then goto Continue; end if; -- Push the current scope, so that the pointer type Tnn, and -- any subsidiary entities resulting from the analysis of the -- rewritten reference, go in the right entity chain. Push_Scope (STJR.Ent); -- Now we need to rewrite the reference. We have a reference -- from level STJR.Lev to level STJE.Lev. The general form of -- the rewritten reference for entity X is: -- Typ'Deref (ARECaF.ARECbU.ARECcU.ARECdU....ARECm.X) -- where a,b,c,d .. m = -- STJR.Lev - 1, STJR.Lev - 2, .. STJE.Lev pragma Assert (STJR.Lev > STJE.Lev); -- Compute the prefix of X. Here are examples to make things -- clear (with parens to show groupings, the prefix is -- everything except the .X at the end). -- level 2 to level 1 -- AREC1F.X -- level 3 to level 1 -- (AREC2F.AREC1U).X -- level 4 to level 1 -- ((AREC3F.AREC2U).AREC1U).X -- level 6 to level 2 -- (((AREC5F.AREC4U).AREC3U).AREC2U).X -- In the above, ARECnF and ARECnU are pointers, so there are -- explicit dereferences required for these occurrences. Pfx := Make_Explicit_Dereference (Loc, Prefix => New_Occurrence_Of (STJR.ARECnF, Loc)); SI := RS_Caller; for L in STJE.Lev .. STJR.Lev - 2 loop SI := Enclosing_Subp (SI); Pfx := Make_Explicit_Dereference (Loc, Prefix => Make_Selected_Component (Loc, Prefix => Pfx, Selector_Name => New_Occurrence_Of (Subps.Table (SI).ARECnU, Loc))); end loop; -- Get activation record component (must exist) Comp := Activation_Record_Component (UPJ.Ent); pragma Assert (Present (Comp)); -- Do the replacement Rewrite (UPJ.Ref, Make_Attribute_Reference (Loc, Prefix => New_Occurrence_Of (Atyp, Loc), Attribute_Name => Name_Deref, Expressions => New_List ( Make_Selected_Component (Loc, Prefix => Pfx, Selector_Name => New_Occurrence_Of (Comp, Loc))))); -- Analyze and resolve the new expression. We do not need to -- establish the relevant scope stack entries here, because we -- have already set all the correct entity references, so no -- name resolution is needed. We have already set the current -- scope, so that any new entities created will be in the right -- scope. -- We analyze with all checks suppressed (since we do not -- expect any exceptions) Analyze_And_Resolve (UPJ.Ref, Typ, Suppress => All_Checks); Pop_Scope; end Rewrite_One_Ref; end; <<Continue>> null; end loop Uplev_Refs; -- Finally, loop through all calls adding extra actual for the -- activation record where it is required. Adjust_Calls : for J in Calls.First .. Calls.Last loop -- Process a single call, we are only interested in a call to a -- subprogram that actually needs a pointer to an activation record, -- as indicated by the ARECnF entity being set. This excludes the -- top level subprogram, and any subprogram not having uplevel refs. Adjust_One_Call : declare CTJ : Call_Entry renames Calls.Table (J); STF : Subp_Entry renames Subps.Table (Subp_Index (CTJ.Caller)); STT : Subp_Entry renames Subps.Table (Subp_Index (CTJ.Callee)); Loc : constant Source_Ptr := Sloc (CTJ.N); Extra : Node_Id; ExtraP : Node_Id; SubX : SI_Type; Act : Node_Id; begin if Present (STT.ARECnF) then -- CTJ.N is a call to a subprogram which may require a pointer -- to an activation record. The subprogram containing the call -- is CTJ.From and the subprogram being called is CTJ.To, so we -- have a call from level STF.Lev to level STT.Lev. -- There are three possibilities: -- For a call to the same level, we just pass the activation -- record passed to the calling subprogram. if STF.Lev = STT.Lev then Extra := New_Occurrence_Of (STF.ARECnF, Loc); -- For a call that goes down a level, we pass a pointer to the -- activation record constructed within the caller (which may -- be the outer-level subprogram, but also may be a more deeply -- nested caller). elsif STT.Lev = STF.Lev + 1 then Extra := New_Occurrence_Of (STF.ARECnP, Loc); -- Otherwise we must have an upcall (STT.Lev < STF.LEV), -- since it is not possible to do a downcall of more than -- one level. -- For a call from level STF.Lev to level STT.Lev, we -- have to find the activation record needed by the -- callee. This is as follows: -- ARECaF.ARECbU.ARECcU....ARECm -- where a,b,c .. m = -- STF.Lev - 1, STF.Lev - 2, STF.Lev - 3 .. STT.Lev else pragma Assert (STT.Lev < STF.Lev); Extra := New_Occurrence_Of (STF.ARECnF, Loc); SubX := Subp_Index (CTJ.Caller); for K in reverse STT.Lev .. STF.Lev - 1 loop SubX := Enclosing_Subp (SubX); Extra := Make_Selected_Component (Loc, Prefix => Extra, Selector_Name => New_Occurrence_Of (Subps.Table (SubX).ARECnU, Loc)); end loop; end if; -- Extra is the additional parameter to be added. Build a -- parameter association that we can append to the actuals. ExtraP := Make_Parameter_Association (Loc, Selector_Name => New_Occurrence_Of (STT.ARECnF, Loc), Explicit_Actual_Parameter => Extra); if No (Parameter_Associations (CTJ.N)) then Set_Parameter_Associations (CTJ.N, Empty_List); end if; Append (ExtraP, Parameter_Associations (CTJ.N)); -- We need to deal with the actual parameter chain as well. The -- newly added parameter is always the last actual. Act := First_Named_Actual (CTJ.N); if No (Act) then Set_First_Named_Actual (CTJ.N, Extra); -- Here we must follow the chain and append the new entry else loop declare PAN : Node_Id; NNA : Node_Id; begin PAN := Parent (Act); pragma Assert (Nkind (PAN) = N_Parameter_Association); NNA := Next_Named_Actual (PAN); if No (NNA) then Set_Next_Named_Actual (PAN, Extra); exit; end if; Act := NNA; end; end loop; end if; -- Analyze and resolve the new actual. We do not need to -- establish the relevant scope stack entries here, because -- we have already set all the correct entity references, so -- no name resolution is needed. -- We analyze with all checks suppressed (since we do not -- expect any exceptions, and also we temporarily turn off -- Unested_Subprogram_Mode to avoid trying to mark uplevel -- references (not needed at this stage, and in fact causes -- a bit of recursive chaos). Opt.Unnest_Subprogram_Mode := False; Analyze_And_Resolve (Extra, Etype (STT.ARECnF), Suppress => All_Checks); Opt.Unnest_Subprogram_Mode := True; end if; end Adjust_One_Call; end loop Adjust_Calls; return; end Unnest_Subprogram; ------------------------ -- Unnest_Subprograms -- ------------------------ procedure Unnest_Subprograms (N : Node_Id) is function Search_Subprograms (N : Node_Id) return Traverse_Result; -- Tree visitor that search for outer level procedures with nested -- subprograms and invokes Unnest_Subprogram() ------------------------ -- Search_Subprograms -- ------------------------ function Search_Subprograms (N : Node_Id) return Traverse_Result is begin if Nkind_In (N, N_Subprogram_Body, N_Subprogram_Body_Stub) then declare Spec_Id : constant Entity_Id := Unique_Defining_Entity (N); begin -- We are only interested in subprograms (not generic -- subprograms), that have nested subprograms. if Is_Subprogram (Spec_Id) and then Has_Nested_Subprogram (Spec_Id) and then Is_Library_Level_Entity (Spec_Id) then Unnest_Subprogram (Spec_Id, N); end if; end; end if; return OK; end Search_Subprograms; --------------- -- Do_Search -- --------------- procedure Do_Search is new Traverse_Proc (Search_Subprograms); -- Subtree visitor instantiation -- Start of processing for Unnest_Subprograms begin if not Opt.Unnest_Subprogram_Mode then return; end if; Do_Search (N); end Unnest_Subprograms; end Exp_Unst;