| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT COMPILER COMPONENTS -- |
| -- -- |
| -- E X P _ C H 2 -- |
| -- -- |
| -- B o d y -- |
| -- -- |
| -- Copyright (C) 1992-2006, 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 2, 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 COPYING. If not, write -- |
| -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- |
| -- Boston, MA 02110-1301, USA. -- |
| -- -- |
| -- 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 Elists; use Elists; |
| with Errout; use Errout; |
| with Exp_Smem; use Exp_Smem; |
| with Exp_Tss; use Exp_Tss; |
| with Exp_Util; use Exp_Util; |
| with Exp_VFpt; use Exp_VFpt; |
| with Nmake; use Nmake; |
| with Opt; use Opt; |
| with Sem; use Sem; |
| with Sem_Eval; use Sem_Eval; |
| with Sem_Res; use Sem_Res; |
| with Sem_Util; use Sem_Util; |
| with Sem_Warn; use Sem_Warn; |
| with Sinfo; use Sinfo; |
| with Snames; use Snames; |
| with Tbuild; use Tbuild; |
| with Uintp; use Uintp; |
| |
| package body Exp_Ch2 is |
| |
| ----------------------- |
| -- Local Subprograms -- |
| ----------------------- |
| |
| procedure Expand_Current_Value (N : Node_Id); |
| -- N is a node for a variable whose Current_Value field is set. If N is |
| -- node is for a discrete type, replaces node with a copy of the referenced |
| -- value. This provides a limited form of value propagation for variables |
| -- which are initialized or assigned not been further modified at the time |
| -- of reference. The call has no effect if the Current_Value refers to a |
| -- conditional with condition other than equality. |
| |
| procedure Expand_Discriminant (N : Node_Id); |
| -- An occurrence of a discriminant within a discriminated type is replaced |
| -- with the corresponding discriminal, that is to say the formal parameter |
| -- of the initialization procedure for the type that is associated with |
| -- that particular discriminant. This replacement is not performed for |
| -- discriminants of records that appear in constraints of component of the |
| -- record, because Gigi uses the discriminant name to retrieve its value. |
| -- In the other hand, it has to be performed for default expressions of |
| -- components because they are used in the record init procedure. See Einfo |
| -- for more details, and Exp_Ch3, Exp_Ch9 for examples of use. For |
| -- discriminants of tasks and protected types, the transformation is more |
| -- complex when it occurs within a default expression for an entry or |
| -- protected operation. The corresponding default_expression_function has |
| -- an additional parameter which is the target of an entry call, and the |
| -- discriminant of the task must be replaced with a reference to the |
| -- discriminant of that formal parameter. |
| |
| procedure Expand_Entity_Reference (N : Node_Id); |
| -- Common processing for expansion of identifiers and expanded names |
| |
| procedure Expand_Entry_Index_Parameter (N : Node_Id); |
| -- A reference to the identifier in the entry index specification of |
| -- protected entry body is modified to a reference to a constant definition |
| -- equal to the index of the entry family member being called. This |
| -- constant is calculated as part of the elaboration of the expanded code |
| -- for the body, and is calculated from the object-wide entry index |
| -- returned by Next_Entry_Call. |
| |
| procedure Expand_Entry_Parameter (N : Node_Id); |
| -- A reference to an entry parameter is modified to be a reference to the |
| -- corresponding component of the entry parameter record that is passed by |
| -- the runtime to the accept body procedure |
| |
| procedure Expand_Formal (N : Node_Id); |
| -- A reference to a formal parameter of a protected subprogram is expanded |
| -- to the corresponding formal of the unprotected procedure used to |
| -- represent the protected subprogram within the protected object. |
| |
| procedure Expand_Protected_Private (N : Node_Id); |
| -- A reference to a private object of a protected type is expanded to a |
| -- component selected from the record used to implement the protected |
| -- object. Such a record is passed to all operations on a protected object |
| -- in a parameter named _object. Such an object is a constant within a |
| -- function, and a variable otherwise. |
| |
| procedure Expand_Renaming (N : Node_Id); |
| -- For renamings, just replace the identifier by the corresponding |
| -- name expression. Note that this has been evaluated (see routine |
| -- Exp_Ch8.Expand_N_Object_Renaming.Evaluate_Name) so this gives |
| -- the correct renaming semantics. |
| |
| -------------------------- |
| -- Expand_Current_Value -- |
| -------------------------- |
| |
| procedure Expand_Current_Value (N : Node_Id) is |
| Loc : constant Source_Ptr := Sloc (N); |
| E : constant Entity_Id := Entity (N); |
| CV : constant Node_Id := Current_Value (E); |
| T : constant Entity_Id := Etype (N); |
| Val : Node_Id; |
| Op : Node_Kind; |
| |
| -- Start of processing for Expand_Current_Value |
| |
| begin |
| if True |
| |
| -- No replacement if value raises constraint error |
| |
| and then Nkind (CV) /= N_Raise_Constraint_Error |
| |
| -- Do this only for discrete types |
| |
| and then Is_Discrete_Type (T) |
| |
| -- Do not replace biased types, since it is problematic to |
| -- consistently generate a sensible constant value in this case. |
| |
| and then not Has_Biased_Representation (T) |
| |
| -- Do not replace lvalues |
| |
| and then not Is_Lvalue (N) |
| |
| -- Check that entity is suitable for replacement |
| |
| and then OK_To_Do_Constant_Replacement (E) |
| |
| -- Do not replace occurrences in pragmas (where names typically |
| -- appear not as values, but as simply names. If there are cases |
| -- where values are required, it is only a very minor efficiency |
| -- issue that they do not get replaced when they could be). |
| |
| and then Nkind (Parent (N)) /= N_Pragma_Argument_Association |
| |
| -- Same for Asm_Input and Asm_Output attribute references |
| |
| and then not (Nkind (Parent (N)) = N_Attribute_Reference |
| and then |
| (Attribute_Name (Parent (N)) = Name_Asm_Input |
| or else |
| Attribute_Name (Parent (N)) = Name_Asm_Output)) |
| then |
| -- Case of Current_Value is a compile time known value |
| |
| if Nkind (CV) in N_Subexpr then |
| Val := CV; |
| |
| -- Case of Current_Value is a conditional expression reference |
| |
| else |
| Get_Current_Value_Condition (N, Op, Val); |
| |
| if Op /= N_Op_Eq then |
| return; |
| end if; |
| end if; |
| |
| -- If constant value is an occurrence of an enumeration literal, |
| -- then we just make another occurence of the same literal. |
| |
| if Is_Entity_Name (Val) |
| and then Ekind (Entity (Val)) = E_Enumeration_Literal |
| then |
| Rewrite (N, |
| Unchecked_Convert_To (T, |
| New_Occurrence_Of (Entity (Val), Loc))); |
| |
| -- Otherwise get the value, and convert to appropriate type |
| |
| else |
| Rewrite (N, |
| Unchecked_Convert_To (T, |
| Make_Integer_Literal (Loc, |
| Intval => Expr_Rep_Value (Val)))); |
| end if; |
| |
| Analyze_And_Resolve (N, T); |
| Set_Is_Static_Expression (N, False); |
| end if; |
| end Expand_Current_Value; |
| |
| ------------------------- |
| -- Expand_Discriminant -- |
| ------------------------- |
| |
| procedure Expand_Discriminant (N : Node_Id) is |
| Scop : constant Entity_Id := Scope (Entity (N)); |
| P : Node_Id := N; |
| Parent_P : Node_Id := Parent (P); |
| In_Entry : Boolean := False; |
| |
| begin |
| -- The Incomplete_Or_Private_Kind happens while resolving the |
| -- discriminant constraint involved in a derived full type, |
| -- such as: |
| |
| -- type D is private; |
| -- type D(C : ...) is new T(C); |
| |
| if Ekind (Scop) = E_Record_Type |
| or Ekind (Scop) in Incomplete_Or_Private_Kind |
| then |
| -- Find the origin by walking up the tree till the component |
| -- declaration |
| |
| while Present (Parent_P) |
| and then Nkind (Parent_P) /= N_Component_Declaration |
| loop |
| P := Parent_P; |
| Parent_P := Parent (P); |
| end loop; |
| |
| -- If the discriminant reference was part of the default expression |
| -- it has to be "discriminalized" |
| |
| if Present (Parent_P) and then P = Expression (Parent_P) then |
| Set_Entity (N, Discriminal (Entity (N))); |
| end if; |
| |
| elsif Is_Concurrent_Type (Scop) then |
| while Present (Parent_P) |
| and then Nkind (Parent_P) /= N_Subprogram_Body |
| loop |
| P := Parent_P; |
| |
| if Nkind (P) = N_Entry_Declaration then |
| In_Entry := True; |
| end if; |
| |
| Parent_P := Parent (Parent_P); |
| end loop; |
| |
| -- If the discriminant occurs within the default expression for a |
| -- formal of an entry or protected operation, create a default |
| -- function for it, and replace the discriminant with a reference to |
| -- the discriminant of the formal of the default function. The |
| -- discriminant entity is the one defined in the corresponding |
| -- record. |
| |
| if Present (Parent_P) |
| and then Present (Corresponding_Spec (Parent_P)) |
| then |
| declare |
| Loc : constant Source_Ptr := Sloc (N); |
| D_Fun : constant Entity_Id := Corresponding_Spec (Parent_P); |
| Formal : constant Entity_Id := First_Formal (D_Fun); |
| New_N : Node_Id; |
| Disc : Entity_Id; |
| |
| begin |
| -- Verify that we are within a default function: the type of |
| -- its formal parameter is the same task or protected type. |
| |
| if Present (Formal) |
| and then Etype (Formal) = Scope (Entity (N)) |
| then |
| Disc := CR_Discriminant (Entity (N)); |
| |
| New_N := |
| Make_Selected_Component (Loc, |
| Prefix => New_Occurrence_Of (Formal, Loc), |
| Selector_Name => New_Occurrence_Of (Disc, Loc)); |
| |
| Set_Etype (New_N, Etype (N)); |
| Rewrite (N, New_N); |
| |
| else |
| Set_Entity (N, Discriminal (Entity (N))); |
| end if; |
| end; |
| |
| elsif Nkind (Parent (N)) = N_Range |
| and then In_Entry |
| then |
| Set_Entity (N, CR_Discriminant (Entity (N))); |
| else |
| Set_Entity (N, Discriminal (Entity (N))); |
| end if; |
| |
| else |
| Set_Entity (N, Discriminal (Entity (N))); |
| end if; |
| end Expand_Discriminant; |
| |
| ----------------------------- |
| -- Expand_Entity_Reference -- |
| ----------------------------- |
| |
| procedure Expand_Entity_Reference (N : Node_Id) is |
| E : constant Entity_Id := Entity (N); |
| |
| begin |
| -- Defend against errors |
| |
| if No (E) and then Total_Errors_Detected /= 0 then |
| return; |
| end if; |
| |
| if Ekind (E) = E_Discriminant then |
| Expand_Discriminant (N); |
| |
| elsif Is_Entry_Formal (E) then |
| Expand_Entry_Parameter (N); |
| |
| elsif Ekind (E) = E_Component |
| and then Is_Protected_Private (E) |
| then |
| -- Protect against junk use of tasking in no run time mode |
| |
| if No_Run_Time_Mode then |
| return; |
| end if; |
| |
| Expand_Protected_Private (N); |
| |
| elsif Ekind (E) = E_Entry_Index_Parameter then |
| Expand_Entry_Index_Parameter (N); |
| |
| elsif Is_Formal (E) then |
| Expand_Formal (N); |
| |
| elsif Is_Renaming_Of_Object (E) then |
| Expand_Renaming (N); |
| |
| elsif Ekind (E) = E_Variable |
| and then Is_Shared_Passive (E) |
| then |
| Expand_Shared_Passive_Variable (N); |
| |
| elsif (Ekind (E) = E_Variable |
| or else |
| Ekind (E) = E_In_Out_Parameter |
| or else |
| Ekind (E) = E_Out_Parameter) |
| and then Present (Current_Value (E)) |
| then |
| Expand_Current_Value (N); |
| |
| -- We do want to warn for the case of a boolean variable (not a |
| -- boolean constant) whose value is known at compile time. |
| |
| if Is_Boolean_Type (Etype (N)) then |
| Warn_On_Known_Condition (N); |
| end if; |
| end if; |
| end Expand_Entity_Reference; |
| |
| ---------------------------------- |
| -- Expand_Entry_Index_Parameter -- |
| ---------------------------------- |
| |
| procedure Expand_Entry_Index_Parameter (N : Node_Id) is |
| begin |
| Set_Entity (N, Entry_Index_Constant (Entity (N))); |
| end Expand_Entry_Index_Parameter; |
| |
| ---------------------------- |
| -- Expand_Entry_Parameter -- |
| ---------------------------- |
| |
| procedure Expand_Entry_Parameter (N : Node_Id) is |
| Loc : constant Source_Ptr := Sloc (N); |
| Ent_Formal : constant Entity_Id := Entity (N); |
| Ent_Spec : constant Entity_Id := Scope (Ent_Formal); |
| Parm_Type : constant Entity_Id := Entry_Parameters_Type (Ent_Spec); |
| Acc_Stack : constant Elist_Id := Accept_Address (Ent_Spec); |
| Addr_Ent : constant Entity_Id := Node (Last_Elmt (Acc_Stack)); |
| P_Comp_Ref : Entity_Id; |
| |
| function In_Assignment_Context (N : Node_Id) return Boolean; |
| -- Check whether this is a context in which the entry formal may be |
| -- assigned to. |
| |
| --------------------------- |
| -- In_Assignment_Context -- |
| --------------------------- |
| |
| function In_Assignment_Context (N : Node_Id) return Boolean is |
| begin |
| if Nkind (Parent (N)) = N_Procedure_Call_Statement |
| or else Nkind (Parent (N)) = N_Entry_Call_Statement |
| or else |
| (Nkind (Parent (N)) = N_Assignment_Statement |
| and then N = Name (Parent (N))) |
| then |
| return True; |
| |
| elsif Nkind (Parent (N)) = N_Parameter_Association then |
| return In_Assignment_Context (Parent (N)); |
| |
| elsif (Nkind (Parent (N)) = N_Selected_Component |
| or else Nkind (Parent (N)) = N_Indexed_Component |
| or else Nkind (Parent (N)) = N_Slice) |
| and then In_Assignment_Context (Parent (N)) |
| then |
| return True; |
| else |
| return False; |
| end if; |
| end In_Assignment_Context; |
| |
| -- Start of processing for Expand_Entry_Parameter |
| |
| begin |
| if Is_Task_Type (Scope (Ent_Spec)) |
| and then Comes_From_Source (Ent_Formal) |
| then |
| -- Before replacing the formal with the local renaming that is used |
| -- in the accept block, note if this is an assignment context, and |
| -- note the modification to avoid spurious warnings, because the |
| -- original entity is not used further. If formal is unconstrained, |
| -- we also generate an extra parameter to hold the Constrained |
| -- attribute of the actual. No renaming is generated for this flag. |
| |
| if Ekind (Entity (N)) /= E_In_Parameter |
| and then In_Assignment_Context (N) |
| then |
| Note_Possible_Modification (N); |
| end if; |
| |
| Rewrite (N, New_Occurrence_Of (Renamed_Object (Entity (N)), Loc)); |
| return; |
| end if; |
| |
| -- What we need is a reference to the corresponding component of the |
| -- parameter record object. The Accept_Address field of the entry entity |
| -- references the address variable that contains the address of the |
| -- accept parameters record. We first have to do an unchecked conversion |
| -- to turn this into a pointer to the parameter record and then we |
| -- select the required parameter field. |
| |
| P_Comp_Ref := |
| Make_Selected_Component (Loc, |
| Prefix => |
| Make_Explicit_Dereference (Loc, |
| Unchecked_Convert_To (Parm_Type, |
| New_Reference_To (Addr_Ent, Loc))), |
| Selector_Name => |
| New_Reference_To (Entry_Component (Ent_Formal), Loc)); |
| |
| -- For all types of parameters, the constructed parameter record object |
| -- contains a pointer to the parameter. Thus we must dereference them to |
| -- access them (this will often be redundant, since the needed deference |
| -- is implicit, but no harm is done by making it explicit). |
| |
| Rewrite (N, |
| Make_Explicit_Dereference (Loc, P_Comp_Ref)); |
| |
| Analyze (N); |
| end Expand_Entry_Parameter; |
| |
| ------------------- |
| -- Expand_Formal -- |
| ------------------- |
| |
| procedure Expand_Formal (N : Node_Id) is |
| E : constant Entity_Id := Entity (N); |
| Subp : constant Entity_Id := Scope (E); |
| |
| begin |
| if Is_Protected_Type (Scope (Subp)) |
| and then not Is_Init_Proc (Subp) |
| and then Present (Protected_Formal (E)) |
| then |
| Set_Entity (N, Protected_Formal (E)); |
| end if; |
| end Expand_Formal; |
| |
| ---------------------------- |
| -- Expand_N_Expanded_Name -- |
| ---------------------------- |
| |
| procedure Expand_N_Expanded_Name (N : Node_Id) is |
| begin |
| Expand_Entity_Reference (N); |
| end Expand_N_Expanded_Name; |
| |
| ------------------------- |
| -- Expand_N_Identifier -- |
| ------------------------- |
| |
| procedure Expand_N_Identifier (N : Node_Id) is |
| begin |
| Expand_Entity_Reference (N); |
| end Expand_N_Identifier; |
| |
| --------------------------- |
| -- Expand_N_Real_Literal -- |
| --------------------------- |
| |
| procedure Expand_N_Real_Literal (N : Node_Id) is |
| begin |
| if Vax_Float (Etype (N)) then |
| Expand_Vax_Real_Literal (N); |
| end if; |
| end Expand_N_Real_Literal; |
| |
| ------------------------------ |
| -- Expand_Protected_Private -- |
| ------------------------------ |
| |
| procedure Expand_Protected_Private (N : Node_Id) is |
| Loc : constant Source_Ptr := Sloc (N); |
| E : constant Entity_Id := Entity (N); |
| Op : constant Node_Id := Protected_Operation (E); |
| Scop : Entity_Id; |
| Lo : Node_Id; |
| Hi : Node_Id; |
| D_Range : Node_Id; |
| |
| begin |
| if Nkind (Op) /= N_Subprogram_Body |
| or else Nkind (Specification (Op)) /= N_Function_Specification |
| then |
| Set_Ekind (Prival (E), E_Variable); |
| else |
| Set_Ekind (Prival (E), E_Constant); |
| end if; |
| |
| -- If the private component appears in an assignment (either lhs or |
| -- rhs) and is a one-dimensional array constrained by a discriminant, |
| -- rewrite as P (Lo .. Hi) with an explicit range, so that discriminal |
| -- is directly visible. This solves delicate visibility problems. |
| |
| if Comes_From_Source (N) |
| and then Is_Array_Type (Etype (E)) |
| and then Number_Dimensions (Etype (E)) = 1 |
| and then not Within_Init_Proc |
| then |
| Lo := Type_Low_Bound (Etype (First_Index (Etype (E)))); |
| Hi := Type_High_Bound (Etype (First_Index (Etype (E)))); |
| |
| if Nkind (Parent (N)) = N_Assignment_Statement |
| and then ((Is_Entity_Name (Lo) |
| and then Ekind (Entity (Lo)) = E_In_Parameter) |
| or else (Is_Entity_Name (Hi) |
| and then |
| Ekind (Entity (Hi)) = E_In_Parameter)) |
| then |
| D_Range := New_Node (N_Range, Loc); |
| |
| if Is_Entity_Name (Lo) |
| and then Ekind (Entity (Lo)) = E_In_Parameter |
| then |
| Set_Low_Bound (D_Range, |
| Make_Identifier (Loc, Chars (Entity (Lo)))); |
| else |
| Set_Low_Bound (D_Range, Duplicate_Subexpr (Lo)); |
| end if; |
| |
| if Is_Entity_Name (Hi) |
| and then Ekind (Entity (Hi)) = E_In_Parameter |
| then |
| Set_High_Bound (D_Range, |
| Make_Identifier (Loc, Chars (Entity (Hi)))); |
| else |
| Set_High_Bound (D_Range, Duplicate_Subexpr (Hi)); |
| end if; |
| |
| Rewrite (N, |
| Make_Slice (Loc, |
| Prefix => New_Occurrence_Of (E, Loc), |
| Discrete_Range => D_Range)); |
| |
| Analyze_And_Resolve (N, Etype (E)); |
| return; |
| end if; |
| end if; |
| |
| -- The type of the reference is the type of the prival, which may differ |
| -- from that of the original component if it is an itype. |
| |
| Set_Entity (N, Prival (E)); |
| Set_Etype (N, Etype (Prival (E))); |
| Scop := Current_Scope; |
| |
| -- Find entity for protected operation, which must be on scope stack |
| |
| while not Is_Protected_Type (Scope (Scop)) loop |
| Scop := Scope (Scop); |
| end loop; |
| |
| Append_Elmt (N, Privals_Chain (Scop)); |
| end Expand_Protected_Private; |
| |
| --------------------- |
| -- Expand_Renaming -- |
| --------------------- |
| |
| procedure Expand_Renaming (N : Node_Id) is |
| E : constant Entity_Id := Entity (N); |
| T : constant Entity_Id := Etype (N); |
| |
| begin |
| Rewrite (N, New_Copy_Tree (Renamed_Object (E))); |
| |
| -- We mark the copy as unanalyzed, so that it is sure to be reanalyzed |
| -- at the top level. This is needed in the packed case since we |
| -- specifically avoided expanding packed array references when the |
| -- renaming declaration was analyzed. |
| |
| Reset_Analyzed_Flags (N); |
| Analyze_And_Resolve (N, T); |
| end Expand_Renaming; |
| |
| ------------------ |
| -- Param_Entity -- |
| ------------------ |
| |
| -- This would be trivial, simply a test for an identifier that was a |
| -- reference to a formal, if it were not for the fact that a previous call |
| -- to Expand_Entry_Parameter will have modified the reference to the |
| -- identifier. A formal of a protected entity is rewritten as |
| |
| -- typ!(recobj).rec.all'Constrained |
| |
| -- where rec is a selector whose Entry_Formal link points to the formal |
| -- For a formal of a task entity, the formal is rewritten as a local |
| -- renaming. |
| |
| -- In addition, a formal that is marked volatile because it is aliased |
| -- through an address clause is rewritten as dereference as well. |
| |
| function Param_Entity (N : Node_Id) return Entity_Id is |
| begin |
| -- Simple reference case |
| |
| if Nkind (N) = N_Identifier or else Nkind (N) = N_Expanded_Name then |
| if Is_Formal (Entity (N)) then |
| return Entity (N); |
| |
| elsif Nkind (Parent (Entity (N))) = N_Object_Renaming_Declaration |
| and then Nkind (Parent (Parent (Entity (N)))) = N_Accept_Statement |
| then |
| return Entity (N); |
| end if; |
| |
| else |
| if Nkind (N) = N_Explicit_Dereference then |
| declare |
| P : constant Node_Id := Prefix (N); |
| S : Node_Id; |
| |
| begin |
| if Nkind (P) = N_Selected_Component then |
| S := Selector_Name (P); |
| |
| if Present (Entry_Formal (Entity (S))) then |
| return Entry_Formal (Entity (S)); |
| end if; |
| |
| elsif Nkind (Original_Node (N)) = N_Identifier then |
| return Param_Entity (Original_Node (N)); |
| end if; |
| end; |
| end if; |
| end if; |
| |
| return (Empty); |
| end Param_Entity; |
| |
| end Exp_Ch2; |
