| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT COMPILER COMPONENTS -- |
| -- -- |
| -- E X P _ C H 8 -- |
| -- -- |
| -- B o d y -- |
| -- -- |
| -- Copyright (C) 1992-2019, 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 Einfo; use Einfo; |
| with Exp_Ch3; use Exp_Ch3; |
| with Exp_Ch4; use Exp_Ch4; |
| with Exp_Ch6; use Exp_Ch6; |
| with Exp_Dbug; use Exp_Dbug; |
| with Exp_Util; use Exp_Util; |
| with Freeze; use Freeze; |
| with Namet; use Namet; |
| with Nmake; use Nmake; |
| with Nlists; use Nlists; |
| with Opt; use Opt; |
| with Sem; use Sem; |
| with Sem_Aux; use Sem_Aux; |
| with Sem_Ch8; use Sem_Ch8; |
| with Sem_Util; use Sem_Util; |
| with Sinfo; use Sinfo; |
| with Snames; use Snames; |
| with Stand; use Stand; |
| with Tbuild; use Tbuild; |
| |
| package body Exp_Ch8 is |
| |
| --------------------------------------------- |
| -- Expand_N_Exception_Renaming_Declaration -- |
| --------------------------------------------- |
| |
| procedure Expand_N_Exception_Renaming_Declaration (N : Node_Id) is |
| Decl : Node_Id; |
| |
| begin |
| Decl := Debug_Renaming_Declaration (N); |
| |
| if Present (Decl) then |
| Insert_Action (N, Decl); |
| end if; |
| end Expand_N_Exception_Renaming_Declaration; |
| |
| ------------------------------------------ |
| -- Expand_N_Object_Renaming_Declaration -- |
| ------------------------------------------ |
| |
| -- Most object renaming cases can be done by just capturing the address |
| -- of the renamed object. The cases in which this is not true are when |
| -- this address is not computable, since it involves extraction of a |
| -- packed array element, or of a record component to which a component |
| -- clause applies (that can specify an arbitrary bit boundary), or where |
| -- the enclosing record itself has a non-standard representation. |
| |
| -- In Ada 2020, a third case arises when the renamed object is a nonatomic |
| -- subcomponent of an atomic object, because reads of or writes to it must |
| -- access the enclosing atomic object. That's also the case for an object |
| -- subject to the Volatile_Full_Access GNAT aspect/pragma in any language |
| -- version. For the sake of simplicity, we treat any subcomponent of an |
| -- atomic or Volatile_Full_Access object in any language version this way. |
| |
| -- In these three cases, we pre-evaluate the renaming expression, by |
| -- extracting and freezing the values of any subscripts, and then we |
| -- set the flag Is_Renaming_Of_Object which means that any reference |
| -- to the object will be handled by macro substitution in the front |
| -- end, and the back end will know to ignore the renaming declaration. |
| |
| -- An additional odd case that requires processing by expansion is |
| -- the renaming of a discriminant of a mutable record type. The object |
| -- is a constant because it renames something that cannot be assigned to, |
| -- but in fact the underlying value can change and must be reevaluated |
| -- at each reference. Gigi does have a notion of a "constant view" of |
| -- an object, and therefore the front-end must perform the expansion. |
| -- For simplicity, and to bypass some obscure code-generation problem, |
| -- we use macro substitution for all renamed discriminants, whether the |
| -- enclosing type is constrained or not. |
| |
| -- The other special processing required is for the case of renaming |
| -- of an object of a class wide type, where it is necessary to build |
| -- the appropriate subtype for the renamed object. |
| -- More comments needed for this para ??? |
| |
| procedure Expand_N_Object_Renaming_Declaration (N : Node_Id) is |
| Nam : constant Node_Id := Name (N); |
| Decl : Node_Id; |
| T : Entity_Id; |
| |
| function Evaluation_Required (Nam : Node_Id) return Boolean; |
| -- Determines whether it is necessary to do static name evaluation for |
| -- renaming of Nam. It is considered necessary if evaluating the name |
| -- involves indexing a packed array, or extracting a component of a |
| -- record to which a component clause applies, or a subcomponent of an |
| -- atomic object. Note that we are only interested in these operations |
| -- if they occur as part of the name itself, subscripts are just values |
| -- that are computed as part of the evaluation, so they are unimportant. |
| -- In addition, always return True for Modify_Tree_For_C since the |
| -- code generator doesn't know how to handle renamings. |
| |
| ------------------------- |
| -- Evaluation_Required -- |
| ------------------------- |
| |
| function Evaluation_Required (Nam : Node_Id) return Boolean is |
| begin |
| if Modify_Tree_For_C then |
| return True; |
| |
| elsif Nkind_In (Nam, N_Indexed_Component, N_Slice) then |
| if Is_Packed (Etype (Prefix (Nam))) then |
| return True; |
| |
| elsif Is_Atomic_Or_VFA_Object (Prefix (Nam)) then |
| return True; |
| |
| else |
| return Evaluation_Required (Prefix (Nam)); |
| end if; |
| |
| elsif Nkind (Nam) = N_Selected_Component then |
| declare |
| Rec_Type : constant Entity_Id := Etype (Prefix (Nam)); |
| |
| begin |
| if Present (Component_Clause (Entity (Selector_Name (Nam)))) |
| or else Has_Non_Standard_Rep (Rec_Type) |
| then |
| return True; |
| |
| elsif Ekind (Entity (Selector_Name (Nam))) = E_Discriminant |
| and then Is_Record_Type (Rec_Type) |
| and then not Is_Concurrent_Record_Type (Rec_Type) |
| then |
| return True; |
| |
| elsif Is_Atomic_Or_VFA_Object (Prefix (Nam)) then |
| return True; |
| |
| else |
| return Evaluation_Required (Prefix (Nam)); |
| end if; |
| end; |
| |
| else |
| return False; |
| end if; |
| end Evaluation_Required; |
| |
| -- Start of processing for Expand_N_Object_Renaming_Declaration |
| |
| begin |
| -- Perform name evaluation if required |
| |
| if Evaluation_Required (Nam) then |
| Evaluate_Name (Nam); |
| Set_Is_Renaming_Of_Object (Defining_Identifier (N)); |
| end if; |
| |
| -- Deal with construction of subtype in class-wide case |
| |
| T := Etype (Defining_Identifier (N)); |
| |
| if Is_Class_Wide_Type (T) then |
| Expand_Subtype_From_Expr (N, T, Subtype_Mark (N), Name (N)); |
| Find_Type (Subtype_Mark (N)); |
| Set_Etype (Defining_Identifier (N), Entity (Subtype_Mark (N))); |
| |
| -- Freeze the class-wide subtype here to ensure that the subtype |
| -- and equivalent type are frozen before the renaming. |
| |
| Freeze_Before (N, Entity (Subtype_Mark (N))); |
| end if; |
| |
| -- Ada 2005 (AI-318-02): If the renamed object is a call to a build-in- |
| -- place function, then a temporary return object needs to be created |
| -- and access to it must be passed to the function. |
| |
| if Is_Build_In_Place_Function_Call (Nam) then |
| Make_Build_In_Place_Call_In_Anonymous_Context (Nam); |
| |
| -- Ada 2005 (AI-318-02): Specialization of previous case for renaming |
| -- containing build-in-place function calls whose returned object covers |
| -- interface types. |
| |
| elsif Present (Unqual_BIP_Iface_Function_Call (Nam)) then |
| Make_Build_In_Place_Iface_Call_In_Anonymous_Context (Nam); |
| end if; |
| |
| -- Create renaming entry for debug information. Mark the entity as |
| -- needing debug info if it comes from sources because the current |
| -- setting in Freeze_Entity occurs too late. ??? |
| |
| if Comes_From_Source (Defining_Identifier (N)) then |
| Set_Debug_Info_Needed (Defining_Identifier (N)); |
| end if; |
| |
| Decl := Debug_Renaming_Declaration (N); |
| |
| if Present (Decl) then |
| Insert_Action (N, Decl); |
| end if; |
| end Expand_N_Object_Renaming_Declaration; |
| |
| ------------------------------------------- |
| -- Expand_N_Package_Renaming_Declaration -- |
| ------------------------------------------- |
| |
| procedure Expand_N_Package_Renaming_Declaration (N : Node_Id) is |
| Decl : Node_Id; |
| |
| begin |
| Decl := Debug_Renaming_Declaration (N); |
| |
| if Present (Decl) then |
| |
| -- If we are in a compilation unit, then this is an outer |
| -- level declaration, and must have a scope of Standard |
| |
| if Nkind (Parent (N)) = N_Compilation_Unit then |
| declare |
| Aux : constant Node_Id := Aux_Decls_Node (Parent (N)); |
| |
| begin |
| Push_Scope (Standard_Standard); |
| |
| if No (Actions (Aux)) then |
| Set_Actions (Aux, New_List (Decl)); |
| else |
| Append (Decl, Actions (Aux)); |
| end if; |
| |
| Analyze (Decl); |
| |
| -- Enter the debug variable in the qualification list, which |
| -- must be done at this point because auxiliary declarations |
| -- occur at the library level and aren't associated with a |
| -- normal scope. |
| |
| Qualify_Entity_Names (Decl); |
| |
| Pop_Scope; |
| end; |
| |
| -- Otherwise, just insert after the package declaration |
| |
| else |
| Insert_Action (N, Decl); |
| end if; |
| end if; |
| end Expand_N_Package_Renaming_Declaration; |
| |
| ---------------------------------------------- |
| -- Expand_N_Subprogram_Renaming_Declaration -- |
| ---------------------------------------------- |
| |
| procedure Expand_N_Subprogram_Renaming_Declaration (N : Node_Id) is |
| Loc : constant Source_Ptr := Sloc (N); |
| Id : constant Entity_Id := Defining_Entity (N); |
| |
| function Build_Body_For_Renaming (Typ : Entity_Id) return Node_Id; |
| -- Build and return the body for the renaming declaration of an equality |
| -- or inequality operator of type Typ. |
| |
| ----------------------------- |
| -- Build_Body_For_Renaming -- |
| ----------------------------- |
| |
| function Build_Body_For_Renaming (Typ : Entity_Id) return Node_Id is |
| Left : constant Entity_Id := First_Formal (Id); |
| Right : constant Entity_Id := Next_Formal (Left); |
| Body_Id : Entity_Id; |
| Decl : Node_Id; |
| |
| begin |
| Set_Alias (Id, Empty); |
| Set_Has_Completion (Id, False); |
| Rewrite (N, |
| Make_Subprogram_Declaration (Sloc (N), |
| Specification => Specification (N))); |
| Set_Has_Delayed_Freeze (Id); |
| |
| Body_Id := Make_Defining_Identifier (Sloc (N), Chars (Id)); |
| Set_Debug_Info_Needed (Body_Id); |
| |
| if Has_Variant_Part (Typ) then |
| Decl := |
| Build_Variant_Record_Equality |
| (Typ => Typ, |
| Body_Id => Body_Id, |
| Param_Specs => Copy_Parameter_List (Id)); |
| |
| -- Build body for renamed equality, to capture its current meaning. |
| -- It may be redefined later, but the renaming is elaborated where |
| -- it occurs. This is technically known as Squirreling semantics. |
| -- Renaming is rewritten as a subprogram declaration, and the |
| -- generated body is inserted into the freeze actions for the |
| -- subprogram. |
| |
| else |
| Decl := |
| Make_Subprogram_Body (Loc, |
| Specification => |
| Make_Function_Specification (Loc, |
| Defining_Unit_Name => Body_Id, |
| Parameter_Specifications => Copy_Parameter_List (Id), |
| Result_Definition => |
| New_Occurrence_Of (Standard_Boolean, Loc)), |
| Declarations => Empty_List, |
| Handled_Statement_Sequence => Empty); |
| |
| Set_Handled_Statement_Sequence (Decl, |
| Make_Handled_Sequence_Of_Statements (Loc, |
| Statements => New_List ( |
| Make_Simple_Return_Statement (Loc, |
| Expression => |
| Expand_Record_Equality |
| (Id, |
| Typ => Typ, |
| Lhs => Make_Identifier (Loc, Chars (Left)), |
| Rhs => Make_Identifier (Loc, Chars (Right)), |
| Bodies => Declarations (Decl)))))); |
| end if; |
| |
| return Decl; |
| end Build_Body_For_Renaming; |
| |
| -- Local variables |
| |
| Nam : constant Node_Id := Name (N); |
| |
| -- Start of processing for Expand_N_Subprogram_Renaming_Declaration |
| |
| begin |
| -- When the prefix of the name is a function call, we must force the |
| -- call to be made by removing side effects from the call, since we |
| -- must only call the function once. |
| |
| if Nkind (Nam) = N_Selected_Component |
| and then Nkind (Prefix (Nam)) = N_Function_Call |
| then |
| Remove_Side_Effects (Prefix (Nam)); |
| |
| -- For an explicit dereference, the prefix must be captured to prevent |
| -- reevaluation on calls through the renaming, which could result in |
| -- calling the wrong subprogram if the access value were to be changed. |
| |
| elsif Nkind (Nam) = N_Explicit_Dereference then |
| Force_Evaluation (Prefix (Nam)); |
| end if; |
| |
| -- Handle cases where we build a body for a renamed equality |
| |
| if Is_Entity_Name (Nam) |
| and then Chars (Entity (Nam)) = Name_Op_Eq |
| and then Scope (Entity (Nam)) = Standard_Standard |
| then |
| declare |
| Typ : constant Entity_Id := Etype (First_Formal (Id)); |
| |
| begin |
| -- Check whether this is a renaming of a predefined equality on an |
| -- untagged record type (AI05-0123). |
| |
| if Ada_Version >= Ada_2012 |
| and then Is_Record_Type (Typ) |
| and then not Is_Tagged_Type (Typ) |
| and then not Is_Frozen (Typ) |
| then |
| Append_Freeze_Action (Id, Build_Body_For_Renaming (Typ)); |
| end if; |
| end; |
| end if; |
| end Expand_N_Subprogram_Renaming_Declaration; |
| |
| end Exp_Ch8; |
