| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT COMPILER COMPONENTS -- |
| -- -- |
| -- S E M _ M E C H -- |
| -- -- |
| -- B o d y -- |
| -- -- |
| -- Copyright (C) 1996-2014, 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 Errout; use Errout; |
| with Namet; use Namet; |
| with Sem; use Sem; |
| with Sem_Aux; use Sem_Aux; |
| with Sinfo; use Sinfo; |
| with Snames; use Snames; |
| |
| package body Sem_Mech is |
| |
| ------------------------- |
| -- Set_Mechanism_Value -- |
| ------------------------- |
| |
| procedure Set_Mechanism_Value (Ent : Entity_Id; Mech_Name : Node_Id) is |
| |
| procedure Bad_Mechanism; |
| -- Signal bad mechanism name |
| |
| ------------------- |
| -- Bad_Mechanism -- |
| ------------------- |
| |
| procedure Bad_Mechanism is |
| begin |
| Error_Msg_N ("unrecognized mechanism name", Mech_Name); |
| end Bad_Mechanism; |
| |
| -- Start of processing for Set_Mechanism_Value |
| |
| begin |
| if Mechanism (Ent) /= Default_Mechanism then |
| Error_Msg_NE |
| ("mechanism for & has already been set", Mech_Name, Ent); |
| end if; |
| |
| -- MECHANISM_NAME ::= value | reference |
| |
| if Nkind (Mech_Name) = N_Identifier then |
| if Chars (Mech_Name) = Name_Value then |
| Set_Mechanism_With_Checks (Ent, By_Copy, Mech_Name); |
| |
| elsif Chars (Mech_Name) = Name_Reference then |
| Set_Mechanism_With_Checks (Ent, By_Reference, Mech_Name); |
| |
| elsif Chars (Mech_Name) = Name_Copy then |
| Error_Msg_N ("bad mechanism name, Value assumed", Mech_Name); |
| Set_Mechanism (Ent, By_Copy); |
| |
| else |
| Bad_Mechanism; |
| end if; |
| |
| else |
| Bad_Mechanism; |
| end if; |
| end Set_Mechanism_Value; |
| |
| ------------------------------- |
| -- Set_Mechanism_With_Checks -- |
| ------------------------------- |
| |
| procedure Set_Mechanism_With_Checks |
| (Ent : Entity_Id; |
| Mech : Mechanism_Type; |
| Enod : Node_Id) |
| is |
| pragma Unreferenced (Enod); |
| |
| begin |
| -- Right now we don't do any checks, should we do more ??? |
| |
| Set_Mechanism (Ent, Mech); |
| end Set_Mechanism_With_Checks; |
| |
| -------------------- |
| -- Set_Mechanisms -- |
| -------------------- |
| |
| procedure Set_Mechanisms (E : Entity_Id) is |
| Formal : Entity_Id; |
| Typ : Entity_Id; |
| |
| begin |
| -- Skip this processing if inside a generic template. Not only is |
| -- it unnecessary (since neither extra formals nor mechanisms are |
| -- relevant for the template itself), but at least at the moment, |
| -- procedures get frozen early inside a template so attempting to |
| -- look at the formal types does not work too well if they are |
| -- private types that have not been frozen yet. |
| |
| if Inside_A_Generic then |
| return; |
| end if; |
| |
| -- Loop through formals |
| |
| Formal := First_Formal (E); |
| while Present (Formal) loop |
| |
| if Mechanism (Formal) = Default_Mechanism then |
| Typ := Underlying_Type (Etype (Formal)); |
| |
| -- If there is no underlying type, then skip this processing and |
| -- leave the convention set to Default_Mechanism. It seems odd |
| -- that there should ever be such cases but there are (see |
| -- comments for filed regression tests 1418-001 and 1912-009) ??? |
| |
| if No (Typ) then |
| goto Skip_Formal; |
| end if; |
| |
| case Convention (E) is |
| |
| --------- |
| -- Ada -- |
| --------- |
| |
| -- Note: all RM defined conventions are treated the same from |
| -- the point of view of parameter passing mechanism. Convention |
| -- Ghost has the same dynamic semantics as convention Ada. |
| |
| when Convention_Ada | |
| Convention_Intrinsic | |
| Convention_Entry | |
| Convention_Protected | |
| Convention_Stubbed => |
| |
| -- By reference types are passed by reference (RM 6.2(4)) |
| |
| if Is_By_Reference_Type (Typ) then |
| Set_Mechanism (Formal, By_Reference); |
| |
| -- By copy types are passed by copy (RM 6.2(3)) |
| |
| elsif Is_By_Copy_Type (Typ) then |
| Set_Mechanism (Formal, By_Copy); |
| |
| -- All other types we leave the Default_Mechanism set, so |
| -- that the backend can choose the appropriate method. |
| |
| else |
| null; |
| end if; |
| |
| -- Special Ada conventions specifying passing mechanism |
| |
| when Convention_Ada_Pass_By_Copy => |
| Set_Mechanism (Formal, By_Copy); |
| |
| when Convention_Ada_Pass_By_Reference => |
| Set_Mechanism (Formal, By_Reference); |
| |
| ------- |
| -- C -- |
| ------- |
| |
| -- Note: Assembler, C++, Java, Stdcall also use C conventions |
| |
| when Convention_Assembler | |
| Convention_C | |
| Convention_CIL | |
| Convention_CPP | |
| Convention_Java | |
| Convention_Stdcall => |
| |
| -- The following values are passed by copy |
| |
| -- IN Scalar parameters (RM B.3(66)) |
| -- IN parameters of access types (RM B.3(67)) |
| -- Access parameters (RM B.3(68)) |
| -- Access to subprogram types (RM B.3(71)) |
| |
| -- Note: in the case of access parameters, it is the pointer |
| -- that is passed by value. In GNAT access parameters are |
| -- treated as IN parameters of an anonymous access type, so |
| -- this falls out free. |
| |
| -- The bottom line is that all IN elementary types are |
| -- passed by copy in GNAT. |
| |
| if Is_Elementary_Type (Typ) then |
| if Ekind (Formal) = E_In_Parameter then |
| Set_Mechanism (Formal, By_Copy); |
| |
| -- OUT and IN OUT parameters of elementary types are |
| -- passed by reference (RM B.3(68)). Note that we are |
| -- not following the advice to pass the address of a |
| -- copy to preserve by copy semantics. |
| |
| else |
| Set_Mechanism (Formal, By_Reference); |
| end if; |
| |
| -- Records are normally passed by reference (RM B.3(69)). |
| -- However, this can be overridden by the use of the |
| -- C_Pass_By_Copy pragma or C_Pass_By_Copy convention. |
| |
| elsif Is_Record_Type (Typ) then |
| |
| -- If the record is not convention C, then we always |
| -- pass by reference, C_Pass_By_Copy does not apply. |
| |
| if Convention (Typ) /= Convention_C then |
| Set_Mechanism (Formal, By_Reference); |
| |
| -- OUT and IN OUT parameters of record types are passed |
| -- by reference regardless of pragmas (RM B.3 (69/2)). |
| |
| elsif Ekind_In (Formal, E_Out_Parameter, |
| E_In_Out_Parameter) |
| then |
| Set_Mechanism (Formal, By_Reference); |
| |
| -- IN parameters of record types are passed by copy only |
| -- when the related type has convention C_Pass_By_Copy |
| -- (RM B.3 (68.1/2)). |
| |
| elsif Ekind (Formal) = E_In_Parameter |
| and then C_Pass_By_Copy (Typ) |
| then |
| Set_Mechanism (Formal, By_Copy); |
| |
| -- Otherwise, for a C convention record, we set the |
| -- convention in accordance with a possible use of |
| -- the C_Pass_By_Copy pragma. Note that the value of |
| -- Default_C_Record_Mechanism in the absence of such |
| -- a pragma is By_Reference. |
| |
| else |
| Set_Mechanism (Formal, Default_C_Record_Mechanism); |
| end if; |
| |
| -- Array types are passed by reference (B.3 (71)) |
| |
| elsif Is_Array_Type (Typ) then |
| Set_Mechanism (Formal, By_Reference); |
| |
| -- For all other types, use Default_Mechanism mechanism |
| |
| else |
| null; |
| end if; |
| |
| ----------- |
| -- COBOL -- |
| ----------- |
| |
| when Convention_COBOL => |
| |
| -- Access parameters (which in GNAT look like IN parameters |
| -- of an access type) are passed by copy (RM B.4(96)) as |
| -- are all other IN parameters of scalar type (RM B.4(97)). |
| |
| -- For now we pass these parameters by reference as well. |
| -- The RM specifies the intent BY_CONTENT, but gigi does |
| -- not currently transform By_Copy properly. If we pass by |
| -- reference, it will be imperative to introduce copies ??? |
| |
| if Is_Elementary_Type (Typ) |
| and then Ekind (Formal) = E_In_Parameter |
| then |
| Set_Mechanism (Formal, By_Reference); |
| |
| -- All other parameters (i.e. all non-scalar types, and |
| -- all OUT or IN OUT parameters) are passed by reference. |
| -- Note that at the moment we are not bothering to make |
| -- copies of scalar types as recommended in the RM. |
| |
| else |
| Set_Mechanism (Formal, By_Reference); |
| end if; |
| |
| ------------- |
| -- Fortran -- |
| ------------- |
| |
| when Convention_Fortran => |
| |
| -- Access types are passed by default (presumably this |
| -- will mean they are passed by copy) |
| |
| if Is_Access_Type (Typ) then |
| null; |
| |
| -- For now, we pass all other parameters by reference. |
| -- It is not clear that this is right in the long run, |
| -- but it seems to correspond to what gnu f77 wants. |
| |
| else |
| Set_Mechanism (Formal, By_Reference); |
| end if; |
| end case; |
| end if; |
| |
| <<Skip_Formal>> -- remove this when problem above is fixed ??? |
| |
| Next_Formal (Formal); |
| end loop; |
| |
| -- Note: there is nothing we need to do for the return type here. |
| -- We deal with returning by reference in the Ada sense, by use of |
| -- the flag By_Ref, rather than by messing with mechanisms. |
| |
| -- A mechanism of Reference for the return means that an extra |
| -- parameter must be provided for the return value (that is the |
| -- DEC meaning of the pragma), and is unrelated to the Ada notion |
| -- of return by reference. |
| |
| -- Note: there was originally code here to set the mechanism to |
| -- By_Reference for types that are "by reference" in the Ada sense, |
| -- but, in accordance with the discussion above, this is wrong, and |
| -- the code was removed. |
| |
| end Set_Mechanisms; |
| |
| end Sem_Mech; |
