| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT COMPILER COMPONENTS -- |
| -- -- |
| -- E X P _ C H 5 -- |
| -- -- |
| -- B o d y -- |
| -- -- |
| -- Copyright (C) 1992-2007, 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 Checks; use Checks; |
| with Debug; use Debug; |
| with Einfo; use Einfo; |
| with Elists; use Elists; |
| with Exp_Atag; use Exp_Atag; |
| with Exp_Aggr; use Exp_Aggr; |
| with Exp_Ch6; use Exp_Ch6; |
| with Exp_Ch7; use Exp_Ch7; |
| with Exp_Ch11; use Exp_Ch11; |
| with Exp_Dbug; use Exp_Dbug; |
| with Exp_Pakd; use Exp_Pakd; |
| with Exp_Tss; use Exp_Tss; |
| with Exp_Util; use Exp_Util; |
| with Namet; use Namet; |
| with Nlists; use Nlists; |
| with Nmake; use Nmake; |
| with Opt; use Opt; |
| with Restrict; use Restrict; |
| with Rident; use Rident; |
| with Rtsfind; use Rtsfind; |
| with Sinfo; use Sinfo; |
| with Sem; use Sem; |
| with Sem_Ch3; use Sem_Ch3; |
| with Sem_Ch8; use Sem_Ch8; |
| with Sem_Ch13; use Sem_Ch13; |
| with Sem_Eval; use Sem_Eval; |
| with Sem_Res; use Sem_Res; |
| with Sem_Util; use Sem_Util; |
| with Snames; use Snames; |
| with Stand; use Stand; |
| with Stringt; use Stringt; |
| with Targparm; use Targparm; |
| with Tbuild; use Tbuild; |
| with Ttypes; use Ttypes; |
| with Uintp; use Uintp; |
| with Validsw; use Validsw; |
| |
| package body Exp_Ch5 is |
| |
| function Change_Of_Representation (N : Node_Id) return Boolean; |
| -- Determine if the right hand side of the assignment N is a type |
| -- conversion which requires a change of representation. Called |
| -- only for the array and record cases. |
| |
| procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id); |
| -- N is an assignment which assigns an array value. This routine process |
| -- the various special cases and checks required for such assignments, |
| -- including change of representation. Rhs is normally simply the right |
| -- hand side of the assignment, except that if the right hand side is |
| -- a type conversion or a qualified expression, then the Rhs is the |
| -- actual expression inside any such type conversions or qualifications. |
| |
| function Expand_Assign_Array_Loop |
| (N : Node_Id; |
| Larray : Entity_Id; |
| Rarray : Entity_Id; |
| L_Type : Entity_Id; |
| R_Type : Entity_Id; |
| Ndim : Pos; |
| Rev : Boolean) return Node_Id; |
| -- N is an assignment statement which assigns an array value. This routine |
| -- expands the assignment into a loop (or nested loops for the case of a |
| -- multi-dimensional array) to do the assignment component by component. |
| -- Larray and Rarray are the entities of the actual arrays on the left |
| -- hand and right hand sides. L_Type and R_Type are the types of these |
| -- arrays (which may not be the same, due to either sliding, or to a |
| -- change of representation case). Ndim is the number of dimensions and |
| -- the parameter Rev indicates if the loops run normally (Rev = False), |
| -- or reversed (Rev = True). The value returned is the constructed |
| -- loop statement. Auxiliary declarations are inserted before node N |
| -- using the standard Insert_Actions mechanism. |
| |
| procedure Expand_Assign_Record (N : Node_Id); |
| -- N is an assignment of a non-tagged record value. This routine handles |
| -- the case where the assignment must be made component by component, |
| -- either because the target is not byte aligned, or there is a change |
| -- of representation. |
| |
| procedure Expand_Non_Function_Return (N : Node_Id); |
| -- Called by Expand_N_Simple_Return_Statement in case we're returning from |
| -- a procedure body, entry body, accept statement, or extended return |
| -- statement. Note that all non-function returns are simple return |
| -- statements. |
| |
| procedure Expand_Simple_Function_Return (N : Node_Id); |
| -- Expand simple return from function. Called by |
| -- Expand_N_Simple_Return_Statement in case we're returning from a function |
| -- body. |
| |
| function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id; |
| -- Generate the necessary code for controlled and tagged assignment, |
| -- that is to say, finalization of the target before, adjustement of |
| -- the target after and save and restore of the tag and finalization |
| -- pointers which are not 'part of the value' and must not be changed |
| -- upon assignment. N is the original Assignment node. |
| |
| ------------------------------ |
| -- Change_Of_Representation -- |
| ------------------------------ |
| |
| function Change_Of_Representation (N : Node_Id) return Boolean is |
| Rhs : constant Node_Id := Expression (N); |
| begin |
| return |
| Nkind (Rhs) = N_Type_Conversion |
| and then |
| not Same_Representation (Etype (Rhs), Etype (Expression (Rhs))); |
| end Change_Of_Representation; |
| |
| ------------------------- |
| -- Expand_Assign_Array -- |
| ------------------------- |
| |
| -- There are two issues here. First, do we let Gigi do a block move, or |
| -- do we expand out into a loop? Second, we need to set the two flags |
| -- Forwards_OK and Backwards_OK which show whether the block move (or |
| -- corresponding loops) can be legitimately done in a forwards (low to |
| -- high) or backwards (high to low) manner. |
| |
| procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is |
| Loc : constant Source_Ptr := Sloc (N); |
| |
| Lhs : constant Node_Id := Name (N); |
| |
| Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs); |
| Act_Rhs : Node_Id := Get_Referenced_Object (Rhs); |
| |
| L_Type : constant Entity_Id := |
| Underlying_Type (Get_Actual_Subtype (Act_Lhs)); |
| R_Type : Entity_Id := |
| Underlying_Type (Get_Actual_Subtype (Act_Rhs)); |
| |
| L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice; |
| R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice; |
| |
| Crep : constant Boolean := Change_Of_Representation (N); |
| |
| Larray : Node_Id; |
| Rarray : Node_Id; |
| |
| Ndim : constant Pos := Number_Dimensions (L_Type); |
| |
| Loop_Required : Boolean := False; |
| -- This switch is set to True if the array move must be done using |
| -- an explicit front end generated loop. |
| |
| procedure Apply_Dereference (Arg : Node_Id); |
| -- If the argument is an access to an array, and the assignment is |
| -- converted into a procedure call, apply explicit dereference. |
| |
| function Has_Address_Clause (Exp : Node_Id) return Boolean; |
| -- Test if Exp is a reference to an array whose declaration has |
| -- an address clause, or it is a slice of such an array. |
| |
| function Is_Formal_Array (Exp : Node_Id) return Boolean; |
| -- Test if Exp is a reference to an array which is either a formal |
| -- parameter or a slice of a formal parameter. These are the cases |
| -- where hidden aliasing can occur. |
| |
| function Is_Non_Local_Array (Exp : Node_Id) return Boolean; |
| -- Determine if Exp is a reference to an array variable which is other |
| -- than an object defined in the current scope, or a slice of such |
| -- an object. Such objects can be aliased to parameters (unlike local |
| -- array references). |
| |
| ----------------------- |
| -- Apply_Dereference -- |
| ----------------------- |
| |
| procedure Apply_Dereference (Arg : Node_Id) is |
| Typ : constant Entity_Id := Etype (Arg); |
| begin |
| if Is_Access_Type (Typ) then |
| Rewrite (Arg, Make_Explicit_Dereference (Loc, |
| Prefix => Relocate_Node (Arg))); |
| Analyze_And_Resolve (Arg, Designated_Type (Typ)); |
| end if; |
| end Apply_Dereference; |
| |
| ------------------------ |
| -- Has_Address_Clause -- |
| ------------------------ |
| |
| function Has_Address_Clause (Exp : Node_Id) return Boolean is |
| begin |
| return |
| (Is_Entity_Name (Exp) and then |
| Present (Address_Clause (Entity (Exp)))) |
| or else |
| (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp))); |
| end Has_Address_Clause; |
| |
| --------------------- |
| -- Is_Formal_Array -- |
| --------------------- |
| |
| function Is_Formal_Array (Exp : Node_Id) return Boolean is |
| begin |
| return |
| (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp))) |
| or else |
| (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp))); |
| end Is_Formal_Array; |
| |
| ------------------------ |
| -- Is_Non_Local_Array -- |
| ------------------------ |
| |
| function Is_Non_Local_Array (Exp : Node_Id) return Boolean is |
| begin |
| return (Is_Entity_Name (Exp) |
| and then Scope (Entity (Exp)) /= Current_Scope) |
| or else (Nkind (Exp) = N_Slice |
| and then Is_Non_Local_Array (Prefix (Exp))); |
| end Is_Non_Local_Array; |
| |
| -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays |
| |
| Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs); |
| Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs); |
| |
| Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs); |
| Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs); |
| |
| -- Start of processing for Expand_Assign_Array |
| |
| begin |
| -- Deal with length check. Note that the length check is done with |
| -- respect to the right hand side as given, not a possible underlying |
| -- renamed object, since this would generate incorrect extra checks. |
| |
| Apply_Length_Check (Rhs, L_Type); |
| |
| -- We start by assuming that the move can be done in either direction, |
| -- i.e. that the two sides are completely disjoint. |
| |
| Set_Forwards_OK (N, True); |
| Set_Backwards_OK (N, True); |
| |
| -- Normally it is only the slice case that can lead to overlap, and |
| -- explicit checks for slices are made below. But there is one case |
| -- where the slice can be implicit and invisible to us: when we have a |
| -- one dimensional array, and either both operands are parameters, or |
| -- one is a parameter (which can be a slice passed by reference) and the |
| -- other is a non-local variable. In this case the parameter could be a |
| -- slice that overlaps with the other operand. |
| |
| -- However, if the array subtype is a constrained first subtype in the |
| -- parameter case, then we don't have to worry about overlap, since |
| -- slice assignments aren't possible (other than for a slice denoting |
| -- the whole array). |
| |
| -- Note: No overlap is possible if there is a change of representation, |
| -- so we can exclude this case. |
| |
| if Ndim = 1 |
| and then not Crep |
| and then |
| ((Lhs_Formal and Rhs_Formal) |
| or else |
| (Lhs_Formal and Rhs_Non_Local_Var) |
| or else |
| (Rhs_Formal and Lhs_Non_Local_Var)) |
| and then |
| (not Is_Constrained (Etype (Lhs)) |
| or else not Is_First_Subtype (Etype (Lhs))) |
| |
| -- In the case of compiling for the Java or .NET Virtual Machine, |
| -- slices are always passed by making a copy, so we don't have to |
| -- worry about overlap. We also want to prevent generation of "<" |
| -- comparisons for array addresses, since that's a meaningless |
| -- operation on the VM. |
| |
| and then VM_Target = No_VM |
| then |
| Set_Forwards_OK (N, False); |
| Set_Backwards_OK (N, False); |
| |
| -- Note: the bit-packed case is not worrisome here, since if we have |
| -- a slice passed as a parameter, it is always aligned on a byte |
| -- boundary, and if there are no explicit slices, the assignment |
| -- can be performed directly. |
| end if; |
| |
| -- We certainly must use a loop for change of representation and also |
| -- we use the operand of the conversion on the right hand side as the |
| -- effective right hand side (the component types must match in this |
| -- situation). |
| |
| if Crep then |
| Act_Rhs := Get_Referenced_Object (Rhs); |
| R_Type := Get_Actual_Subtype (Act_Rhs); |
| Loop_Required := True; |
| |
| -- We require a loop if the left side is possibly bit unaligned |
| |
| elsif Possible_Bit_Aligned_Component (Lhs) |
| or else |
| Possible_Bit_Aligned_Component (Rhs) |
| then |
| Loop_Required := True; |
| |
| -- Arrays with controlled components are expanded into a loop to force |
| -- calls to Adjust at the component level. |
| |
| elsif Has_Controlled_Component (L_Type) then |
| Loop_Required := True; |
| |
| -- If object is atomic, we cannot tolerate a loop |
| |
| elsif Is_Atomic_Object (Act_Lhs) |
| or else |
| Is_Atomic_Object (Act_Rhs) |
| then |
| return; |
| |
| -- Loop is required if we have atomic components since we have to |
| -- be sure to do any accesses on an element by element basis. |
| |
| elsif Has_Atomic_Components (L_Type) |
| or else Has_Atomic_Components (R_Type) |
| or else Is_Atomic (Component_Type (L_Type)) |
| or else Is_Atomic (Component_Type (R_Type)) |
| then |
| Loop_Required := True; |
| |
| -- Case where no slice is involved |
| |
| elsif not L_Slice and not R_Slice then |
| |
| -- The following code deals with the case of unconstrained bit packed |
| -- arrays. The problem is that the template for such arrays contains |
| -- the bounds of the actual source level array, but the copy of an |
| -- entire array requires the bounds of the underlying array. It would |
| -- be nice if the back end could take care of this, but right now it |
| -- does not know how, so if we have such a type, then we expand out |
| -- into a loop, which is inefficient but works correctly. If we don't |
| -- do this, we get the wrong length computed for the array to be |
| -- moved. The two cases we need to worry about are: |
| |
| -- Explicit deference of an unconstrained packed array type as in the |
| -- following example: |
| |
| -- procedure C52 is |
| -- type BITS is array(INTEGER range <>) of BOOLEAN; |
| -- pragma PACK(BITS); |
| -- type A is access BITS; |
| -- P1,P2 : A; |
| -- begin |
| -- P1 := new BITS (1 .. 65_535); |
| -- P2 := new BITS (1 .. 65_535); |
| -- P2.ALL := P1.ALL; |
| -- end C52; |
| |
| -- A formal parameter reference with an unconstrained bit array type |
| -- is the other case we need to worry about (here we assume the same |
| -- BITS type declared above): |
| |
| -- procedure Write_All (File : out BITS; Contents : BITS); |
| -- begin |
| -- File.Storage := Contents; |
| -- end Write_All; |
| |
| -- We expand to a loop in either of these two cases |
| |
| -- Question for future thought. Another potentially more efficient |
| -- approach would be to create the actual subtype, and then do an |
| -- unchecked conversion to this actual subtype ??? |
| |
| Check_Unconstrained_Bit_Packed_Array : declare |
| |
| function Is_UBPA_Reference (Opnd : Node_Id) return Boolean; |
| -- Function to perform required test for the first case, above |
| -- (dereference of an unconstrained bit packed array). |
| |
| ----------------------- |
| -- Is_UBPA_Reference -- |
| ----------------------- |
| |
| function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is |
| Typ : constant Entity_Id := Underlying_Type (Etype (Opnd)); |
| P_Type : Entity_Id; |
| Des_Type : Entity_Id; |
| |
| begin |
| if Present (Packed_Array_Type (Typ)) |
| and then Is_Array_Type (Packed_Array_Type (Typ)) |
| and then not Is_Constrained (Packed_Array_Type (Typ)) |
| then |
| return True; |
| |
| elsif Nkind (Opnd) = N_Explicit_Dereference then |
| P_Type := Underlying_Type (Etype (Prefix (Opnd))); |
| |
| if not Is_Access_Type (P_Type) then |
| return False; |
| |
| else |
| Des_Type := Designated_Type (P_Type); |
| return |
| Is_Bit_Packed_Array (Des_Type) |
| and then not Is_Constrained (Des_Type); |
| end if; |
| |
| else |
| return False; |
| end if; |
| end Is_UBPA_Reference; |
| |
| -- Start of processing for Check_Unconstrained_Bit_Packed_Array |
| |
| begin |
| if Is_UBPA_Reference (Lhs) |
| or else |
| Is_UBPA_Reference (Rhs) |
| then |
| Loop_Required := True; |
| |
| -- Here if we do not have the case of a reference to a bit packed |
| -- unconstrained array case. In this case gigi can most certainly |
| -- handle the assignment if a forwards move is allowed. |
| |
| -- (could it handle the backwards case also???) |
| |
| elsif Forwards_OK (N) then |
| return; |
| end if; |
| end Check_Unconstrained_Bit_Packed_Array; |
| |
| -- The back end can always handle the assignment if the right side is a |
| -- string literal (note that overlap is definitely impossible in this |
| -- case). If the type is packed, a string literal is always converted |
| -- into an aggregate, except in the case of a null slice, for which no |
| -- aggregate can be written. In that case, rewrite the assignment as a |
| -- null statement, a length check has already been emitted to verify |
| -- that the range of the left-hand side is empty. |
| |
| -- Note that this code is not executed if we have an assignment of a |
| -- string literal to a non-bit aligned component of a record, a case |
| -- which cannot be handled by the backend. |
| |
| elsif Nkind (Rhs) = N_String_Literal then |
| if String_Length (Strval (Rhs)) = 0 |
| and then Is_Bit_Packed_Array (L_Type) |
| then |
| Rewrite (N, Make_Null_Statement (Loc)); |
| Analyze (N); |
| end if; |
| |
| return; |
| |
| -- If either operand is bit packed, then we need a loop, since we can't |
| -- be sure that the slice is byte aligned. Similarly, if either operand |
| -- is a possibly unaligned slice, then we need a loop (since the back |
| -- end cannot handle unaligned slices). |
| |
| elsif Is_Bit_Packed_Array (L_Type) |
| or else Is_Bit_Packed_Array (R_Type) |
| or else Is_Possibly_Unaligned_Slice (Lhs) |
| or else Is_Possibly_Unaligned_Slice (Rhs) |
| then |
| Loop_Required := True; |
| |
| -- If we are not bit-packed, and we have only one slice, then no overlap |
| -- is possible except in the parameter case, so we can let the back end |
| -- handle things. |
| |
| elsif not (L_Slice and R_Slice) then |
| if Forwards_OK (N) then |
| return; |
| end if; |
| end if; |
| |
| -- If the right-hand side is a string literal, introduce a temporary for |
| -- it, for use in the generated loop that will follow. |
| |
| if Nkind (Rhs) = N_String_Literal then |
| declare |
| Temp : constant Entity_Id := |
| Make_Defining_Identifier (Loc, New_Internal_Name ('T')); |
| Decl : Node_Id; |
| |
| begin |
| Decl := |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Temp, |
| Object_Definition => New_Occurrence_Of (L_Type, Loc), |
| Expression => Relocate_Node (Rhs)); |
| |
| Insert_Action (N, Decl); |
| Rewrite (Rhs, New_Occurrence_Of (Temp, Loc)); |
| R_Type := Etype (Temp); |
| end; |
| end if; |
| |
| -- Come here to complete the analysis |
| |
| -- Loop_Required: Set to True if we know that a loop is required |
| -- regardless of overlap considerations. |
| |
| -- Forwards_OK: Set to False if we already know that a forwards |
| -- move is not safe, else set to True. |
| |
| -- Backwards_OK: Set to False if we already know that a backwards |
| -- move is not safe, else set to True |
| |
| -- Our task at this stage is to complete the overlap analysis, which can |
| -- result in possibly setting Forwards_OK or Backwards_OK to False, and |
| -- then generating the final code, either by deciding that it is OK |
| -- after all to let Gigi handle it, or by generating appropriate code |
| -- in the front end. |
| |
| declare |
| L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type)); |
| R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type)); |
| |
| Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ); |
| Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ); |
| Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ); |
| Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ); |
| |
| Act_L_Array : Node_Id; |
| Act_R_Array : Node_Id; |
| |
| Cleft_Lo : Node_Id; |
| Cright_Lo : Node_Id; |
| Condition : Node_Id; |
| |
| Cresult : Compare_Result; |
| |
| begin |
| -- Get the expressions for the arrays. If we are dealing with a |
| -- private type, then convert to the underlying type. We can do |
| -- direct assignments to an array that is a private type, but we |
| -- cannot assign to elements of the array without this extra |
| -- unchecked conversion. |
| |
| if Nkind (Act_Lhs) = N_Slice then |
| Larray := Prefix (Act_Lhs); |
| else |
| Larray := Act_Lhs; |
| |
| if Is_Private_Type (Etype (Larray)) then |
| Larray := |
| Unchecked_Convert_To |
| (Underlying_Type (Etype (Larray)), Larray); |
| end if; |
| end if; |
| |
| if Nkind (Act_Rhs) = N_Slice then |
| Rarray := Prefix (Act_Rhs); |
| else |
| Rarray := Act_Rhs; |
| |
| if Is_Private_Type (Etype (Rarray)) then |
| Rarray := |
| Unchecked_Convert_To |
| (Underlying_Type (Etype (Rarray)), Rarray); |
| end if; |
| end if; |
| |
| -- If both sides are slices, we must figure out whether it is safe |
| -- to do the move in one direction or the other. It is always safe |
| -- if there is a change of representation since obviously two arrays |
| -- with different representations cannot possibly overlap. |
| |
| if (not Crep) and L_Slice and R_Slice then |
| Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs)); |
| Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs)); |
| |
| -- If both left and right hand arrays are entity names, and refer |
| -- to different entities, then we know that the move is safe (the |
| -- two storage areas are completely disjoint). |
| |
| if Is_Entity_Name (Act_L_Array) |
| and then Is_Entity_Name (Act_R_Array) |
| and then Entity (Act_L_Array) /= Entity (Act_R_Array) |
| then |
| null; |
| |
| -- Otherwise, we assume the worst, which is that the two arrays |
| -- are the same array. There is no need to check if we know that |
| -- is the case, because if we don't know it, we still have to |
| -- assume it! |
| |
| -- Generally if the same array is involved, then we have an |
| -- overlapping case. We will have to really assume the worst (i.e. |
| -- set neither of the OK flags) unless we can determine the lower |
| -- or upper bounds at compile time and compare them. |
| |
| else |
| Cresult := Compile_Time_Compare (Left_Lo, Right_Lo); |
| |
| if Cresult = Unknown then |
| Cresult := Compile_Time_Compare (Left_Hi, Right_Hi); |
| end if; |
| |
| case Cresult is |
| when LT | LE | EQ => Set_Backwards_OK (N, False); |
| when GT | GE => Set_Forwards_OK (N, False); |
| when NE | Unknown => Set_Backwards_OK (N, False); |
| Set_Forwards_OK (N, False); |
| end case; |
| end if; |
| end if; |
| |
| -- If after that analysis, Forwards_OK is still True, and |
| -- Loop_Required is False, meaning that we have not discovered some |
| -- non-overlap reason for requiring a loop, then we can still let |
| -- gigi handle it. |
| |
| if not Loop_Required then |
| |
| -- Assume gigi can handle it if Forwards_OK is set |
| |
| if Forwards_OK (N) then |
| return; |
| |
| -- If Forwards_OK is not set, the back end will need something |
| -- like memmove to handle the move. For now, this processing is |
| -- activated using the .s debug flag (-gnatd.s). |
| |
| elsif Debug_Flag_Dot_S then |
| return; |
| end if; |
| end if; |
| |
| -- At this stage we have to generate an explicit loop, and we have |
| -- the following cases: |
| |
| -- Forwards_OK = True |
| |
| -- Rnn : right_index := right_index'First; |
| -- for Lnn in left-index loop |
| -- left (Lnn) := right (Rnn); |
| -- Rnn := right_index'Succ (Rnn); |
| -- end loop; |
| |
| -- Note: the above code MUST be analyzed with checks off, because |
| -- otherwise the Succ could overflow. But in any case this is more |
| -- efficient! |
| |
| -- Forwards_OK = False, Backwards_OK = True |
| |
| -- Rnn : right_index := right_index'Last; |
| -- for Lnn in reverse left-index loop |
| -- left (Lnn) := right (Rnn); |
| -- Rnn := right_index'Pred (Rnn); |
| -- end loop; |
| |
| -- Note: the above code MUST be analyzed with checks off, because |
| -- otherwise the Pred could overflow. But in any case this is more |
| -- efficient! |
| |
| -- Forwards_OK = Backwards_OK = False |
| |
| -- This only happens if we have the same array on each side. It is |
| -- possible to create situations using overlays that violate this, |
| -- but we simply do not promise to get this "right" in this case. |
| |
| -- There are two possible subcases. If the No_Implicit_Conditionals |
| -- restriction is set, then we generate the following code: |
| |
| -- declare |
| -- T : constant <operand-type> := rhs; |
| -- begin |
| -- lhs := T; |
| -- end; |
| |
| -- If implicit conditionals are permitted, then we generate: |
| |
| -- if Left_Lo <= Right_Lo then |
| -- <code for Forwards_OK = True above> |
| -- else |
| -- <code for Backwards_OK = True above> |
| -- end if; |
| |
| -- In order to detect possible aliasing, we examine the renamed |
| -- expression when the source or target is a renaming. However, |
| -- the renaming may be intended to capture an address that may be |
| -- affected by subsequent code, and therefore we must recover |
| -- the actual entity for the expansion that follows, not the |
| -- object it renames. In particular, if source or target designate |
| -- a portion of a dynamically allocated object, the pointer to it |
| -- may be reassigned but the renaming preserves the proper location. |
| |
| if Is_Entity_Name (Rhs) |
| and then |
| Nkind (Parent (Entity (Rhs))) = N_Object_Renaming_Declaration |
| and then Nkind (Act_Rhs) = N_Slice |
| then |
| Rarray := Rhs; |
| end if; |
| |
| if Is_Entity_Name (Lhs) |
| and then |
| Nkind (Parent (Entity (Lhs))) = N_Object_Renaming_Declaration |
| and then Nkind (Act_Lhs) = N_Slice |
| then |
| Larray := Lhs; |
| end if; |
| |
| -- Cases where either Forwards_OK or Backwards_OK is true |
| |
| if Forwards_OK (N) or else Backwards_OK (N) then |
| if Controlled_Type (Component_Type (L_Type)) |
| and then Base_Type (L_Type) = Base_Type (R_Type) |
| and then Ndim = 1 |
| and then not No_Ctrl_Actions (N) |
| then |
| declare |
| Proc : constant Entity_Id := |
| TSS (Base_Type (L_Type), TSS_Slice_Assign); |
| Actuals : List_Id; |
| |
| begin |
| Apply_Dereference (Larray); |
| Apply_Dereference (Rarray); |
| Actuals := New_List ( |
| Duplicate_Subexpr (Larray, Name_Req => True), |
| Duplicate_Subexpr (Rarray, Name_Req => True), |
| Duplicate_Subexpr (Left_Lo, Name_Req => True), |
| Duplicate_Subexpr (Left_Hi, Name_Req => True), |
| Duplicate_Subexpr (Right_Lo, Name_Req => True), |
| Duplicate_Subexpr (Right_Hi, Name_Req => True)); |
| |
| Append_To (Actuals, |
| New_Occurrence_Of ( |
| Boolean_Literals (not Forwards_OK (N)), Loc)); |
| |
| Rewrite (N, |
| Make_Procedure_Call_Statement (Loc, |
| Name => New_Reference_To (Proc, Loc), |
| Parameter_Associations => Actuals)); |
| end; |
| |
| else |
| Rewrite (N, |
| Expand_Assign_Array_Loop |
| (N, Larray, Rarray, L_Type, R_Type, Ndim, |
| Rev => not Forwards_OK (N))); |
| end if; |
| |
| -- Case of both are false with No_Implicit_Conditionals |
| |
| elsif Restriction_Active (No_Implicit_Conditionals) then |
| declare |
| T : constant Entity_Id := |
| Make_Defining_Identifier (Loc, Chars => Name_T); |
| |
| begin |
| Rewrite (N, |
| Make_Block_Statement (Loc, |
| Declarations => New_List ( |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => T, |
| Constant_Present => True, |
| Object_Definition => |
| New_Occurrence_Of (Etype (Rhs), Loc), |
| Expression => Relocate_Node (Rhs))), |
| |
| Handled_Statement_Sequence => |
| Make_Handled_Sequence_Of_Statements (Loc, |
| Statements => New_List ( |
| Make_Assignment_Statement (Loc, |
| Name => Relocate_Node (Lhs), |
| Expression => New_Occurrence_Of (T, Loc)))))); |
| end; |
| |
| -- Case of both are false with implicit conditionals allowed |
| |
| else |
| -- Before we generate this code, we must ensure that the left and |
| -- right side array types are defined. They may be itypes, and we |
| -- cannot let them be defined inside the if, since the first use |
| -- in the then may not be executed. |
| |
| Ensure_Defined (L_Type, N); |
| Ensure_Defined (R_Type, N); |
| |
| -- We normally compare addresses to find out which way round to |
| -- do the loop, since this is realiable, and handles the cases of |
| -- parameters, conversions etc. But we can't do that in the bit |
| -- packed case or the VM case, because addresses don't work there. |
| |
| if not Is_Bit_Packed_Array (L_Type) and then VM_Target = No_VM then |
| Condition := |
| Make_Op_Le (Loc, |
| Left_Opnd => |
| Unchecked_Convert_To (RTE (RE_Integer_Address), |
| Make_Attribute_Reference (Loc, |
| Prefix => |
| Make_Indexed_Component (Loc, |
| Prefix => |
| Duplicate_Subexpr_Move_Checks (Larray, True), |
| Expressions => New_List ( |
| Make_Attribute_Reference (Loc, |
| Prefix => |
| New_Reference_To |
| (L_Index_Typ, Loc), |
| Attribute_Name => Name_First))), |
| Attribute_Name => Name_Address)), |
| |
| Right_Opnd => |
| Unchecked_Convert_To (RTE (RE_Integer_Address), |
| Make_Attribute_Reference (Loc, |
| Prefix => |
| Make_Indexed_Component (Loc, |
| Prefix => |
| Duplicate_Subexpr_Move_Checks (Rarray, True), |
| Expressions => New_List ( |
| Make_Attribute_Reference (Loc, |
| Prefix => |
| New_Reference_To |
| (R_Index_Typ, Loc), |
| Attribute_Name => Name_First))), |
| Attribute_Name => Name_Address))); |
| |
| -- For the bit packed and VM cases we use the bounds. That's OK, |
| -- because we don't have to worry about parameters, since they |
| -- cannot cause overlap. Perhaps we should worry about weird slice |
| -- conversions ??? |
| |
| else |
| -- Copy the bounds and reset the Analyzed flag, because the |
| -- bounds of the index type itself may be universal, and must |
| -- must be reaanalyzed to acquire the proper type for Gigi. |
| |
| Cleft_Lo := New_Copy_Tree (Left_Lo); |
| Cright_Lo := New_Copy_Tree (Right_Lo); |
| Set_Analyzed (Cleft_Lo, False); |
| Set_Analyzed (Cright_Lo, False); |
| |
| Condition := |
| Make_Op_Le (Loc, |
| Left_Opnd => Cleft_Lo, |
| Right_Opnd => Cright_Lo); |
| end if; |
| |
| if Controlled_Type (Component_Type (L_Type)) |
| and then Base_Type (L_Type) = Base_Type (R_Type) |
| and then Ndim = 1 |
| and then not No_Ctrl_Actions (N) |
| then |
| |
| -- Call TSS procedure for array assignment, passing the the |
| -- explicit bounds of right and left hand sides. |
| |
| declare |
| Proc : constant Node_Id := |
| TSS (Base_Type (L_Type), TSS_Slice_Assign); |
| Actuals : List_Id; |
| |
| begin |
| Apply_Dereference (Larray); |
| Apply_Dereference (Rarray); |
| Actuals := New_List ( |
| Duplicate_Subexpr (Larray, Name_Req => True), |
| Duplicate_Subexpr (Rarray, Name_Req => True), |
| Duplicate_Subexpr (Left_Lo, Name_Req => True), |
| Duplicate_Subexpr (Left_Hi, Name_Req => True), |
| Duplicate_Subexpr (Right_Lo, Name_Req => True), |
| Duplicate_Subexpr (Right_Hi, Name_Req => True)); |
| |
| Append_To (Actuals, |
| Make_Op_Not (Loc, |
| Right_Opnd => Condition)); |
| |
| Rewrite (N, |
| Make_Procedure_Call_Statement (Loc, |
| Name => New_Reference_To (Proc, Loc), |
| Parameter_Associations => Actuals)); |
| end; |
| |
| else |
| Rewrite (N, |
| Make_Implicit_If_Statement (N, |
| Condition => Condition, |
| |
| Then_Statements => New_List ( |
| Expand_Assign_Array_Loop |
| (N, Larray, Rarray, L_Type, R_Type, Ndim, |
| Rev => False)), |
| |
| Else_Statements => New_List ( |
| Expand_Assign_Array_Loop |
| (N, Larray, Rarray, L_Type, R_Type, Ndim, |
| Rev => True)))); |
| end if; |
| end if; |
| |
| Analyze (N, Suppress => All_Checks); |
| end; |
| |
| exception |
| when RE_Not_Available => |
| return; |
| end Expand_Assign_Array; |
| |
| ------------------------------ |
| -- Expand_Assign_Array_Loop -- |
| ------------------------------ |
| |
| -- The following is an example of the loop generated for the case of a |
| -- two-dimensional array: |
| |
| -- declare |
| -- R2b : Tm1X1 := 1; |
| -- begin |
| -- for L1b in 1 .. 100 loop |
| -- declare |
| -- R4b : Tm1X2 := 1; |
| -- begin |
| -- for L3b in 1 .. 100 loop |
| -- vm1 (L1b, L3b) := vm2 (R2b, R4b); |
| -- R4b := Tm1X2'succ(R4b); |
| -- end loop; |
| -- end; |
| -- R2b := Tm1X1'succ(R2b); |
| -- end loop; |
| -- end; |
| |
| -- Here Rev is False, and Tm1Xn are the subscript types for the right hand |
| -- side. The declarations of R2b and R4b are inserted before the original |
| -- assignment statement. |
| |
| function Expand_Assign_Array_Loop |
| (N : Node_Id; |
| Larray : Entity_Id; |
| Rarray : Entity_Id; |
| L_Type : Entity_Id; |
| R_Type : Entity_Id; |
| Ndim : Pos; |
| Rev : Boolean) return Node_Id |
| is |
| Loc : constant Source_Ptr := Sloc (N); |
| |
| Lnn : array (1 .. Ndim) of Entity_Id; |
| Rnn : array (1 .. Ndim) of Entity_Id; |
| -- Entities used as subscripts on left and right sides |
| |
| L_Index_Type : array (1 .. Ndim) of Entity_Id; |
| R_Index_Type : array (1 .. Ndim) of Entity_Id; |
| -- Left and right index types |
| |
| Assign : Node_Id; |
| |
| F_Or_L : Name_Id; |
| S_Or_P : Name_Id; |
| |
| begin |
| if Rev then |
| F_Or_L := Name_Last; |
| S_Or_P := Name_Pred; |
| else |
| F_Or_L := Name_First; |
| S_Or_P := Name_Succ; |
| end if; |
| |
| -- Setup index types and subscript entities |
| |
| declare |
| L_Index : Node_Id; |
| R_Index : Node_Id; |
| |
| begin |
| L_Index := First_Index (L_Type); |
| R_Index := First_Index (R_Type); |
| |
| for J in 1 .. Ndim loop |
| Lnn (J) := |
| Make_Defining_Identifier (Loc, |
| Chars => New_Internal_Name ('L')); |
| |
| Rnn (J) := |
| Make_Defining_Identifier (Loc, |
| Chars => New_Internal_Name ('R')); |
| |
| L_Index_Type (J) := Etype (L_Index); |
| R_Index_Type (J) := Etype (R_Index); |
| |
| Next_Index (L_Index); |
| Next_Index (R_Index); |
| end loop; |
| end; |
| |
| -- Now construct the assignment statement |
| |
| declare |
| ExprL : constant List_Id := New_List; |
| ExprR : constant List_Id := New_List; |
| |
| begin |
| for J in 1 .. Ndim loop |
| Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc)); |
| Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc)); |
| end loop; |
| |
| Assign := |
| Make_Assignment_Statement (Loc, |
| Name => |
| Make_Indexed_Component (Loc, |
| Prefix => Duplicate_Subexpr (Larray, Name_Req => True), |
| Expressions => ExprL), |
| Expression => |
| Make_Indexed_Component (Loc, |
| Prefix => Duplicate_Subexpr (Rarray, Name_Req => True), |
| Expressions => ExprR)); |
| |
| -- We set assignment OK, since there are some cases, e.g. in object |
| -- declarations, where we are actually assigning into a constant. |
| -- If there really is an illegality, it was caught long before now, |
| -- and was flagged when the original assignment was analyzed. |
| |
| Set_Assignment_OK (Name (Assign)); |
| |
| -- Propagate the No_Ctrl_Actions flag to individual assignments |
| |
| Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N)); |
| end; |
| |
| -- Now construct the loop from the inside out, with the last subscript |
| -- varying most rapidly. Note that Assign is first the raw assignment |
| -- statement, and then subsequently the loop that wraps it up. |
| |
| for J in reverse 1 .. Ndim loop |
| Assign := |
| Make_Block_Statement (Loc, |
| Declarations => New_List ( |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Rnn (J), |
| Object_Definition => |
| New_Occurrence_Of (R_Index_Type (J), Loc), |
| Expression => |
| Make_Attribute_Reference (Loc, |
| Prefix => New_Occurrence_Of (R_Index_Type (J), Loc), |
| Attribute_Name => F_Or_L))), |
| |
| Handled_Statement_Sequence => |
| Make_Handled_Sequence_Of_Statements (Loc, |
| Statements => New_List ( |
| Make_Implicit_Loop_Statement (N, |
| Iteration_Scheme => |
| Make_Iteration_Scheme (Loc, |
| Loop_Parameter_Specification => |
| Make_Loop_Parameter_Specification (Loc, |
| Defining_Identifier => Lnn (J), |
| Reverse_Present => Rev, |
| Discrete_Subtype_Definition => |
| New_Reference_To (L_Index_Type (J), Loc))), |
| |
| Statements => New_List ( |
| Assign, |
| |
| Make_Assignment_Statement (Loc, |
| Name => New_Occurrence_Of (Rnn (J), Loc), |
| Expression => |
| Make_Attribute_Reference (Loc, |
| Prefix => |
| New_Occurrence_Of (R_Index_Type (J), Loc), |
| Attribute_Name => S_Or_P, |
| Expressions => New_List ( |
| New_Occurrence_Of (Rnn (J), Loc))))))))); |
| end loop; |
| |
| return Assign; |
| end Expand_Assign_Array_Loop; |
| |
| -------------------------- |
| -- Expand_Assign_Record -- |
| -------------------------- |
| |
| -- The only processing required is in the change of representation case, |
| -- where we must expand the assignment to a series of field by field |
| -- assignments. |
| |
| procedure Expand_Assign_Record (N : Node_Id) is |
| Lhs : constant Node_Id := Name (N); |
| Rhs : Node_Id := Expression (N); |
| |
| begin |
| -- If change of representation, then extract the real right hand side |
| -- from the type conversion, and proceed with component-wise assignment, |
| -- since the two types are not the same as far as the back end is |
| -- concerned. |
| |
| if Change_Of_Representation (N) then |
| Rhs := Expression (Rhs); |
| |
| -- If this may be a case of a large bit aligned component, then proceed |
| -- with component-wise assignment, to avoid possible clobbering of other |
| -- components sharing bits in the first or last byte of the component to |
| -- be assigned. |
| |
| elsif Possible_Bit_Aligned_Component (Lhs) |
| or |
| Possible_Bit_Aligned_Component (Rhs) |
| then |
| null; |
| |
| -- If neither condition met, then nothing special to do, the back end |
| -- can handle assignment of the entire component as a single entity. |
| |
| else |
| return; |
| end if; |
| |
| -- At this stage we know that we must do a component wise assignment |
| |
| declare |
| Loc : constant Source_Ptr := Sloc (N); |
| R_Typ : constant Entity_Id := Base_Type (Etype (Rhs)); |
| L_Typ : constant Entity_Id := Base_Type (Etype (Lhs)); |
| Decl : constant Node_Id := Declaration_Node (R_Typ); |
| RDef : Node_Id; |
| F : Entity_Id; |
| |
| function Find_Component |
| (Typ : Entity_Id; |
| Comp : Entity_Id) return Entity_Id; |
| -- Find the component with the given name in the underlying record |
| -- declaration for Typ. We need to use the actual entity because the |
| -- type may be private and resolution by identifier alone would fail. |
| |
| function Make_Component_List_Assign |
| (CL : Node_Id; |
| U_U : Boolean := False) return List_Id; |
| -- Returns a sequence of statements to assign the components that |
| -- are referenced in the given component list. The flag U_U is |
| -- used to force the usage of the inferred value of the variant |
| -- part expression as the switch for the generated case statement. |
| |
| function Make_Field_Assign |
| (C : Entity_Id; |
| U_U : Boolean := False) return Node_Id; |
| -- Given C, the entity for a discriminant or component, build an |
| -- assignment for the corresponding field values. The flag U_U |
| -- signals the presence of an Unchecked_Union and forces the usage |
| -- of the inferred discriminant value of C as the right hand side |
| -- of the assignment. |
| |
| function Make_Field_Assigns (CI : List_Id) return List_Id; |
| -- Given CI, a component items list, construct series of statements |
| -- for fieldwise assignment of the corresponding components. |
| |
| -------------------- |
| -- Find_Component -- |
| -------------------- |
| |
| function Find_Component |
| (Typ : Entity_Id; |
| Comp : Entity_Id) return Entity_Id |
| is |
| Utyp : constant Entity_Id := Underlying_Type (Typ); |
| C : Entity_Id; |
| |
| begin |
| C := First_Entity (Utyp); |
| |
| while Present (C) loop |
| if Chars (C) = Chars (Comp) then |
| return C; |
| end if; |
| Next_Entity (C); |
| end loop; |
| |
| raise Program_Error; |
| end Find_Component; |
| |
| -------------------------------- |
| -- Make_Component_List_Assign -- |
| -------------------------------- |
| |
| function Make_Component_List_Assign |
| (CL : Node_Id; |
| U_U : Boolean := False) return List_Id |
| is |
| CI : constant List_Id := Component_Items (CL); |
| VP : constant Node_Id := Variant_Part (CL); |
| |
| Alts : List_Id; |
| DC : Node_Id; |
| DCH : List_Id; |
| Expr : Node_Id; |
| Result : List_Id; |
| V : Node_Id; |
| |
| begin |
| Result := Make_Field_Assigns (CI); |
| |
| if Present (VP) then |
| |
| V := First_Non_Pragma (Variants (VP)); |
| Alts := New_List; |
| while Present (V) loop |
| |
| DCH := New_List; |
| DC := First (Discrete_Choices (V)); |
| while Present (DC) loop |
| Append_To (DCH, New_Copy_Tree (DC)); |
| Next (DC); |
| end loop; |
| |
| Append_To (Alts, |
| Make_Case_Statement_Alternative (Loc, |
| Discrete_Choices => DCH, |
| Statements => |
| Make_Component_List_Assign (Component_List (V)))); |
| Next_Non_Pragma (V); |
| end loop; |
| |
| -- If we have an Unchecked_Union, use the value of the inferred |
| -- discriminant of the variant part expression as the switch |
| -- for the case statement. The case statement may later be |
| -- folded. |
| |
| if U_U then |
| Expr := |
| New_Copy (Get_Discriminant_Value ( |
| Entity (Name (VP)), |
| Etype (Rhs), |
| Discriminant_Constraint (Etype (Rhs)))); |
| else |
| Expr := |
| Make_Selected_Component (Loc, |
| Prefix => Duplicate_Subexpr (Rhs), |
| Selector_Name => |
| Make_Identifier (Loc, Chars (Name (VP)))); |
| end if; |
| |
| Append_To (Result, |
| Make_Case_Statement (Loc, |
| Expression => Expr, |
| Alternatives => Alts)); |
| end if; |
| |
| return Result; |
| end Make_Component_List_Assign; |
| |
| ----------------------- |
| -- Make_Field_Assign -- |
| ----------------------- |
| |
| function Make_Field_Assign |
| (C : Entity_Id; |
| U_U : Boolean := False) return Node_Id |
| is |
| A : Node_Id; |
| Expr : Node_Id; |
| |
| begin |
| -- In the case of an Unchecked_Union, use the discriminant |
| -- constraint value as on the right hand side of the assignment. |
| |
| if U_U then |
| Expr := |
| New_Copy (Get_Discriminant_Value (C, |
| Etype (Rhs), |
| Discriminant_Constraint (Etype (Rhs)))); |
| else |
| Expr := |
| Make_Selected_Component (Loc, |
| Prefix => Duplicate_Subexpr (Rhs), |
| Selector_Name => New_Occurrence_Of (C, Loc)); |
| end if; |
| |
| A := |
| Make_Assignment_Statement (Loc, |
| Name => |
| Make_Selected_Component (Loc, |
| Prefix => Duplicate_Subexpr (Lhs), |
| Selector_Name => |
| New_Occurrence_Of (Find_Component (L_Typ, C), Loc)), |
| Expression => Expr); |
| |
| -- Set Assignment_OK, so discriminants can be assigned |
| |
| Set_Assignment_OK (Name (A), True); |
| return A; |
| end Make_Field_Assign; |
| |
| ------------------------ |
| -- Make_Field_Assigns -- |
| ------------------------ |
| |
| function Make_Field_Assigns (CI : List_Id) return List_Id is |
| Item : Node_Id; |
| Result : List_Id; |
| |
| begin |
| Item := First (CI); |
| Result := New_List; |
| while Present (Item) loop |
| if Nkind (Item) = N_Component_Declaration then |
| Append_To |
| (Result, Make_Field_Assign (Defining_Identifier (Item))); |
| end if; |
| |
| Next (Item); |
| end loop; |
| |
| return Result; |
| end Make_Field_Assigns; |
| |
| -- Start of processing for Expand_Assign_Record |
| |
| begin |
| -- Note that we use the base types for this processing. This results |
| -- in some extra work in the constrained case, but the change of |
| -- representation case is so unusual that it is not worth the effort. |
| |
| -- First copy the discriminants. This is done unconditionally. It |
| -- is required in the unconstrained left side case, and also in the |
| -- case where this assignment was constructed during the expansion |
| -- of a type conversion (since initialization of discriminants is |
| -- suppressed in this case). It is unnecessary but harmless in |
| -- other cases. |
| |
| if Has_Discriminants (L_Typ) then |
| F := First_Discriminant (R_Typ); |
| while Present (F) loop |
| |
| if Is_Unchecked_Union (Base_Type (R_Typ)) then |
| Insert_Action (N, Make_Field_Assign (F, True)); |
| else |
| Insert_Action (N, Make_Field_Assign (F)); |
| end if; |
| |
| Next_Discriminant (F); |
| end loop; |
| end if; |
| |
| -- We know the underlying type is a record, but its current view |
| -- may be private. We must retrieve the usable record declaration. |
| |
| if Nkind (Decl) = N_Private_Type_Declaration |
| and then Present (Full_View (R_Typ)) |
| then |
| RDef := Type_Definition (Declaration_Node (Full_View (R_Typ))); |
| else |
| RDef := Type_Definition (Decl); |
| end if; |
| |
| if Nkind (RDef) = N_Record_Definition |
| and then Present (Component_List (RDef)) |
| then |
| |
| if Is_Unchecked_Union (R_Typ) then |
| Insert_Actions (N, |
| Make_Component_List_Assign (Component_List (RDef), True)); |
| else |
| Insert_Actions |
| (N, Make_Component_List_Assign (Component_List (RDef))); |
| end if; |
| |
| Rewrite (N, Make_Null_Statement (Loc)); |
| end if; |
| |
| end; |
| end Expand_Assign_Record; |
| |
| ----------------------------------- |
| -- Expand_N_Assignment_Statement -- |
| ----------------------------------- |
| |
| -- This procedure implements various cases where an assignment statement |
| -- cannot just be passed on to the back end in untransformed state. |
| |
| procedure Expand_N_Assignment_Statement (N : Node_Id) is |
| Loc : constant Source_Ptr := Sloc (N); |
| Lhs : constant Node_Id := Name (N); |
| Rhs : constant Node_Id := Expression (N); |
| Typ : constant Entity_Id := Underlying_Type (Etype (Lhs)); |
| Exp : Node_Id; |
| |
| begin |
| -- Ada 2005 (AI-327): Handle assignment to priority of protected object |
| |
| -- Rewrite an assignment to X'Priority into a run-time call |
| |
| -- For example: X'Priority := New_Prio_Expr; |
| -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr); |
| |
| -- Note that although X'Priority is notionally an object, it is quite |
| -- deliberately not defined as an aliased object in the RM. This means |
| -- that it works fine to rewrite it as a call, without having to worry |
| -- about complications that would other arise from X'Priority'Access, |
| -- which is illegal, because of the lack of aliasing. |
| |
| if Ada_Version >= Ada_05 then |
| declare |
| Call : Node_Id; |
| Conctyp : Entity_Id; |
| Ent : Entity_Id; |
| Subprg : Entity_Id; |
| RT_Subprg_Name : Node_Id; |
| |
| begin |
| -- Handle chains of renamings |
| |
| Ent := Name (N); |
| while Nkind (Ent) in N_Has_Entity |
| and then Present (Entity (Ent)) |
| and then Present (Renamed_Object (Entity (Ent))) |
| loop |
| Ent := Renamed_Object (Entity (Ent)); |
| end loop; |
| |
| -- The attribute Priority applied to protected objects has been |
| -- previously expanded into a call to the Get_Ceiling run-time |
| -- subprogram. |
| |
| if Nkind (Ent) = N_Function_Call |
| and then (Entity (Name (Ent)) = RTE (RE_Get_Ceiling) |
| or else |
| Entity (Name (Ent)) = RTE (RO_PE_Get_Ceiling)) |
| then |
| -- Look for the enclosing concurrent type |
| |
| Conctyp := Current_Scope; |
| while not Is_Concurrent_Type (Conctyp) loop |
| Conctyp := Scope (Conctyp); |
| end loop; |
| |
| pragma Assert (Is_Protected_Type (Conctyp)); |
| |
| -- Generate the first actual of the call |
| |
| Subprg := Current_Scope; |
| while not Present (Protected_Body_Subprogram (Subprg)) loop |
| Subprg := Scope (Subprg); |
| end loop; |
| |
| -- Select the appropriate run-time call |
| |
| if Number_Entries (Conctyp) = 0 then |
| RT_Subprg_Name := |
| New_Reference_To (RTE (RE_Set_Ceiling), Loc); |
| else |
| RT_Subprg_Name := |
| New_Reference_To (RTE (RO_PE_Set_Ceiling), Loc); |
| end if; |
| |
| Call := |
| Make_Procedure_Call_Statement (Loc, |
| Name => RT_Subprg_Name, |
| Parameter_Associations => New_List ( |
| New_Copy_Tree (First (Parameter_Associations (Ent))), |
| Relocate_Node (Expression (N)))); |
| |
| Rewrite (N, Call); |
| Analyze (N); |
| return; |
| end if; |
| end; |
| end if; |
| |
| -- First deal with generation of range check if required. For now we do |
| -- this only for discrete types. |
| |
| if Do_Range_Check (Rhs) |
| and then Is_Discrete_Type (Typ) |
| then |
| Set_Do_Range_Check (Rhs, False); |
| Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed); |
| end if; |
| |
| -- Check for a special case where a high level transformation is |
| -- required. If we have either of: |
| |
| -- P.field := rhs; |
| -- P (sub) := rhs; |
| |
| -- where P is a reference to a bit packed array, then we have to unwind |
| -- the assignment. The exact meaning of being a reference to a bit |
| -- packed array is as follows: |
| |
| -- An indexed component whose prefix is a bit packed array is a |
| -- reference to a bit packed array. |
| |
| -- An indexed component or selected component whose prefix is a |
| -- reference to a bit packed array is itself a reference ot a |
| -- bit packed array. |
| |
| -- The required transformation is |
| |
| -- Tnn : prefix_type := P; |
| -- Tnn.field := rhs; |
| -- P := Tnn; |
| |
| -- or |
| |
| -- Tnn : prefix_type := P; |
| -- Tnn (subscr) := rhs; |
| -- P := Tnn; |
| |
| -- Since P is going to be evaluated more than once, any subscripts |
| -- in P must have their evaluation forced. |
| |
| if Nkind_In (Lhs, N_Indexed_Component, N_Selected_Component) |
| and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs)) |
| then |
| declare |
| BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs)); |
| BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr); |
| Tnn : constant Entity_Id := |
| Make_Defining_Identifier (Loc, |
| Chars => New_Internal_Name ('T')); |
| |
| begin |
| -- Insert the post assignment first, because we want to copy the |
| -- BPAR_Expr tree before it gets analyzed in the context of the |
| -- pre assignment. Note that we do not analyze the post assignment |
| -- yet (we cannot till we have completed the analysis of the pre |
| -- assignment). As usual, the analysis of this post assignment |
| -- will happen on its own when we "run into" it after finishing |
| -- the current assignment. |
| |
| Insert_After (N, |
| Make_Assignment_Statement (Loc, |
| Name => New_Copy_Tree (BPAR_Expr), |
| Expression => New_Occurrence_Of (Tnn, Loc))); |
| |
| -- At this stage BPAR_Expr is a reference to a bit packed array |
| -- where the reference was not expanded in the original tree, |
| -- since it was on the left side of an assignment. But in the |
| -- pre-assignment statement (the object definition), BPAR_Expr |
| -- will end up on the right hand side, and must be reexpanded. To |
| -- achieve this, we reset the analyzed flag of all selected and |
| -- indexed components down to the actual indexed component for |
| -- the packed array. |
| |
| Exp := BPAR_Expr; |
| loop |
| Set_Analyzed (Exp, False); |
| |
| if Nkind_In |
| (Exp, N_Selected_Component, N_Indexed_Component) |
| then |
| Exp := Prefix (Exp); |
| else |
| exit; |
| end if; |
| end loop; |
| |
| -- Now we can insert and analyze the pre-assignment |
| |
| -- If the right-hand side requires a transient scope, it has |
| -- already been placed on the stack. However, the declaration is |
| -- inserted in the tree outside of this scope, and must reflect |
| -- the proper scope for its variable. This awkward bit is forced |
| -- by the stricter scope discipline imposed by GCC 2.97. |
| |
| declare |
| Uses_Transient_Scope : constant Boolean := |
| Scope_Is_Transient |
| and then N = Node_To_Be_Wrapped; |
| |
| begin |
| if Uses_Transient_Scope then |
| Push_Scope (Scope (Current_Scope)); |
| end if; |
| |
| Insert_Before_And_Analyze (N, |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Tnn, |
| Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc), |
| Expression => BPAR_Expr)); |
| |
| if Uses_Transient_Scope then |
| Pop_Scope; |
| end if; |
| end; |
| |
| -- Now fix up the original assignment and continue processing |
| |
| Rewrite (Prefix (Lhs), |
| New_Occurrence_Of (Tnn, Loc)); |
| |
| -- We do not need to reanalyze that assignment, and we do not need |
| -- to worry about references to the temporary, but we do need to |
| -- make sure that the temporary is not marked as a true constant |
| -- since we now have a generated assignment to it! |
| |
| Set_Is_True_Constant (Tnn, False); |
| end; |
| end if; |
| |
| -- When we have the appropriate type of aggregate in the expression (it |
| -- has been determined during analysis of the aggregate by setting the |
| -- delay flag), let's perform in place assignment and thus avoid |
| -- creating a temporary. |
| |
| if Is_Delayed_Aggregate (Rhs) then |
| Convert_Aggr_In_Assignment (N); |
| Rewrite (N, Make_Null_Statement (Loc)); |
| Analyze (N); |
| return; |
| end if; |
| |
| -- Apply discriminant check if required. If Lhs is an access type to a |
| -- designated type with discriminants, we must always check. |
| |
| if Has_Discriminants (Etype (Lhs)) then |
| |
| -- Skip discriminant check if change of representation. Will be |
| -- done when the change of representation is expanded out. |
| |
| if not Change_Of_Representation (N) then |
| Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs); |
| end if; |
| |
| -- If the type is private without discriminants, and the full type |
| -- has discriminants (necessarily with defaults) a check may still be |
| -- necessary if the Lhs is aliased. The private determinants must be |
| -- visible to build the discriminant constraints. |
| |
| -- Only an explicit dereference that comes from source indicates |
| -- aliasing. Access to formals of protected operations and entries |
| -- create dereferences but are not semantic aliasings. |
| |
| elsif Is_Private_Type (Etype (Lhs)) |
| and then Has_Discriminants (Typ) |
| and then Nkind (Lhs) = N_Explicit_Dereference |
| and then Comes_From_Source (Lhs) |
| then |
| declare |
| Lt : constant Entity_Id := Etype (Lhs); |
| begin |
| Set_Etype (Lhs, Typ); |
| Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs)); |
| Apply_Discriminant_Check (Rhs, Typ, Lhs); |
| Set_Etype (Lhs, Lt); |
| end; |
| |
| -- If the Lhs has a private type with unknown discriminants, it |
| -- may have a full view with discriminants, but those are nameable |
| -- only in the underlying type, so convert the Rhs to it before |
| -- potential checking. |
| |
| elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs))) |
| and then Has_Discriminants (Typ) |
| then |
| Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs)); |
| Apply_Discriminant_Check (Rhs, Typ, Lhs); |
| |
| -- In the access type case, we need the same discriminant check, and |
| -- also range checks if we have an access to constrained array. |
| |
| elsif Is_Access_Type (Etype (Lhs)) |
| and then Is_Constrained (Designated_Type (Etype (Lhs))) |
| then |
| if Has_Discriminants (Designated_Type (Etype (Lhs))) then |
| |
| -- Skip discriminant check if change of representation. Will be |
| -- done when the change of representation is expanded out. |
| |
| if not Change_Of_Representation (N) then |
| Apply_Discriminant_Check (Rhs, Etype (Lhs)); |
| end if; |
| |
| elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then |
| Apply_Range_Check (Rhs, Etype (Lhs)); |
| |
| if Is_Constrained (Etype (Lhs)) then |
| Apply_Length_Check (Rhs, Etype (Lhs)); |
| end if; |
| |
| if Nkind (Rhs) = N_Allocator then |
| declare |
| Target_Typ : constant Entity_Id := Etype (Expression (Rhs)); |
| C_Es : Check_Result; |
| |
| begin |
| C_Es := |
| Get_Range_Checks |
| (Lhs, |
| Target_Typ, |
| Etype (Designated_Type (Etype (Lhs)))); |
| |
| Insert_Range_Checks |
| (C_Es, |
| N, |
| Target_Typ, |
| Sloc (Lhs), |
| Lhs); |
| end; |
| end if; |
| end if; |
| |
| -- Apply range check for access type case |
| |
| elsif Is_Access_Type (Etype (Lhs)) |
| and then Nkind (Rhs) = N_Allocator |
| and then Nkind (Expression (Rhs)) = N_Qualified_Expression |
| then |
| Analyze_And_Resolve (Expression (Rhs)); |
| Apply_Range_Check |
| (Expression (Rhs), Designated_Type (Etype (Lhs))); |
| end if; |
| |
| -- Ada 2005 (AI-231): Generate the run-time check |
| |
| if Is_Access_Type (Typ) |
| and then Can_Never_Be_Null (Etype (Lhs)) |
| and then not Can_Never_Be_Null (Etype (Rhs)) |
| then |
| Apply_Constraint_Check (Rhs, Etype (Lhs)); |
| end if; |
| |
| -- Case of assignment to a bit packed array element |
| |
| if Nkind (Lhs) = N_Indexed_Component |
| and then Is_Bit_Packed_Array (Etype (Prefix (Lhs))) |
| then |
| Expand_Bit_Packed_Element_Set (N); |
| return; |
| |
| -- Build-in-place function call case. Note that we're not yet doing |
| -- build-in-place for user-written assignment statements (the assignment |
| -- here came from an aggregate.) |
| |
| elsif Ada_Version >= Ada_05 |
| and then Is_Build_In_Place_Function_Call (Rhs) |
| then |
| Make_Build_In_Place_Call_In_Assignment (N, Rhs); |
| |
| elsif Is_Tagged_Type (Typ) and then Is_Value_Type (Etype (Lhs)) then |
| |
| -- Nothing to do for valuetypes |
| -- ??? Set_Scope_Is_Transient (False); |
| |
| return; |
| |
| elsif Is_Tagged_Type (Typ) |
| or else (Controlled_Type (Typ) and then not Is_Array_Type (Typ)) |
| then |
| Tagged_Case : declare |
| L : List_Id := No_List; |
| Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N); |
| |
| begin |
| -- In the controlled case, we need to make sure that function |
| -- calls are evaluated before finalizing the target. In all cases, |
| -- it makes the expansion easier if the side-effects are removed |
| -- first. |
| |
| Remove_Side_Effects (Lhs); |
| Remove_Side_Effects (Rhs); |
| |
| -- Avoid recursion in the mechanism |
| |
| Set_Analyzed (N); |
| |
| -- If dispatching assignment, we need to dispatch to _assign |
| |
| if Is_Class_Wide_Type (Typ) |
| |
| -- If the type is tagged, we may as well use the predefined |
| -- primitive assignment. This avoids inlining a lot of code |
| -- and in the class-wide case, the assignment is replaced by |
| -- dispatch call to _assign. Note that this cannot be done when |
| -- discriminant checks are locally suppressed (as in extension |
| -- aggregate expansions) because otherwise the discriminant |
| -- check will be performed within the _assign call. It is also |
| -- suppressed for assignmments created by the expander that |
| -- correspond to initializations, where we do want to copy the |
| -- tag (No_Ctrl_Actions flag set True). by the expander and we |
| -- do not need to mess with tags ever (Expand_Ctrl_Actions flag |
| -- is set True in this case). |
| |
| or else (Is_Tagged_Type (Typ) |
| and then not Is_Value_Type (Etype (Lhs)) |
| and then Chars (Current_Scope) /= Name_uAssign |
| and then Expand_Ctrl_Actions |
| and then not Discriminant_Checks_Suppressed (Empty)) |
| then |
| -- Fetch the primitive op _assign and proper type to call it. |
| -- Because of possible conflits between private and full view |
| -- the proper type is fetched directly from the operation |
| -- profile. |
| |
| declare |
| Op : constant Entity_Id := |
| Find_Prim_Op (Typ, Name_uAssign); |
| F_Typ : Entity_Id := Etype (First_Formal (Op)); |
| |
| begin |
| -- If the assignment is dispatching, make sure to use the |
| -- proper type. |
| |
| if Is_Class_Wide_Type (Typ) then |
| F_Typ := Class_Wide_Type (F_Typ); |
| end if; |
| |
| L := New_List; |
| |
| -- In case of assignment to a class-wide tagged type, before |
| -- the assignment we generate run-time check to ensure that |
| -- the tags of source and target match. |
| |
| if Is_Class_Wide_Type (Typ) |
| and then Is_Tagged_Type (Typ) |
| and then Is_Tagged_Type (Underlying_Type (Etype (Rhs))) |
| then |
| Append_To (L, |
| Make_Raise_Constraint_Error (Loc, |
| Condition => |
| Make_Op_Ne (Loc, |
| Left_Opnd => |
| Make_Selected_Component (Loc, |
| Prefix => Duplicate_Subexpr (Lhs), |
| Selector_Name => |
| Make_Identifier (Loc, |
| Chars => Name_uTag)), |
| Right_Opnd => |
| Make_Selected_Component (Loc, |
| Prefix => Duplicate_Subexpr (Rhs), |
| Selector_Name => |
| Make_Identifier (Loc, |
| Chars => Name_uTag))), |
| Reason => CE_Tag_Check_Failed)); |
| end if; |
| |
| Append_To (L, |
| Make_Procedure_Call_Statement (Loc, |
| Name => New_Reference_To (Op, Loc), |
| Parameter_Associations => New_List ( |
| Unchecked_Convert_To (F_Typ, |
| Duplicate_Subexpr (Lhs)), |
| Unchecked_Convert_To (F_Typ, |
| Duplicate_Subexpr (Rhs))))); |
| end; |
| |
| else |
| L := Make_Tag_Ctrl_Assignment (N); |
| |
| -- We can't afford to have destructive Finalization Actions in |
| -- the Self assignment case, so if the target and the source |
| -- are not obviously different, code is generated to avoid the |
| -- self assignment case: |
| |
| -- if lhs'address /= rhs'address then |
| -- <code for controlled and/or tagged assignment> |
| -- end if; |
| |
| if not Statically_Different (Lhs, Rhs) |
| and then Expand_Ctrl_Actions |
| then |
| L := New_List ( |
| Make_Implicit_If_Statement (N, |
| Condition => |
| Make_Op_Ne (Loc, |
| Left_Opnd => |
| Make_Attribute_Reference (Loc, |
| Prefix => Duplicate_Subexpr (Lhs), |
| Attribute_Name => Name_Address), |
| |
| Right_Opnd => |
| Make_Attribute_Reference (Loc, |
| Prefix => Duplicate_Subexpr (Rhs), |
| Attribute_Name => Name_Address)), |
| |
| Then_Statements => L)); |
| end if; |
| |
| -- We need to set up an exception handler for implementing |
| -- 7.6.1(18). The remaining adjustments are tackled by the |
| -- implementation of adjust for record_controllers (see |
| -- s-finimp.adb). |
| |
| -- This is skipped if we have no finalization |
| |
| if Expand_Ctrl_Actions |
| and then not Restriction_Active (No_Finalization) |
| then |
| L := New_List ( |
| Make_Block_Statement (Loc, |
| Handled_Statement_Sequence => |
| Make_Handled_Sequence_Of_Statements (Loc, |
| Statements => L, |
| Exception_Handlers => New_List ( |
| Make_Handler_For_Ctrl_Operation (Loc))))); |
| end if; |
| end if; |
| |
| Rewrite (N, |
| Make_Block_Statement (Loc, |
| Handled_Statement_Sequence => |
| Make_Handled_Sequence_Of_Statements (Loc, Statements => L))); |
| |
| -- If no restrictions on aborts, protect the whole assignement |
| -- for controlled objects as per 9.8(11). |
| |
| if Controlled_Type (Typ) |
| and then Expand_Ctrl_Actions |
| and then Abort_Allowed |
| then |
| declare |
| Blk : constant Entity_Id := |
| New_Internal_Entity |
| (E_Block, Current_Scope, Sloc (N), 'B'); |
| |
| begin |
| Set_Scope (Blk, Current_Scope); |
| Set_Etype (Blk, Standard_Void_Type); |
| Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N))); |
| |
| Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer)); |
| Set_At_End_Proc (Handled_Statement_Sequence (N), |
| New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc)); |
| Expand_At_End_Handler |
| (Handled_Statement_Sequence (N), Blk); |
| end; |
| end if; |
| |
| -- N has been rewritten to a block statement for which it is |
| -- known by construction that no checks are necessary: analyze |
| -- it with all checks suppressed. |
| |
| Analyze (N, Suppress => All_Checks); |
| return; |
| end Tagged_Case; |
| |
| -- Array types |
| |
| elsif Is_Array_Type (Typ) then |
| declare |
| Actual_Rhs : Node_Id := Rhs; |
| |
| begin |
| while Nkind_In (Actual_Rhs, N_Type_Conversion, |
| N_Qualified_Expression) |
| loop |
| Actual_Rhs := Expression (Actual_Rhs); |
| end loop; |
| |
| Expand_Assign_Array (N, Actual_Rhs); |
| return; |
| end; |
| |
| -- Record types |
| |
| elsif Is_Record_Type (Typ) then |
| Expand_Assign_Record (N); |
| return; |
| |
| -- Scalar types. This is where we perform the processing related to the |
| -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid |
| -- scalar values. |
| |
| elsif Is_Scalar_Type (Typ) then |
| |
| -- Case where right side is known valid |
| |
| if Expr_Known_Valid (Rhs) then |
| |
| -- Here the right side is valid, so it is fine. The case to deal |
| -- with is when the left side is a local variable reference whose |
| -- value is not currently known to be valid. If this is the case, |
| -- and the assignment appears in an unconditional context, then we |
| -- can mark the left side as now being valid. |
| |
| if Is_Local_Variable_Reference (Lhs) |
| and then not Is_Known_Valid (Entity (Lhs)) |
| and then In_Unconditional_Context (N) |
| then |
| Set_Is_Known_Valid (Entity (Lhs), True); |
| end if; |
| |
| -- Case where right side may be invalid in the sense of the RM |
| -- reference above. The RM does not require that we check for the |
| -- validity on an assignment, but it does require that the assignment |
| -- of an invalid value not cause erroneous behavior. |
| |
| -- The general approach in GNAT is to use the Is_Known_Valid flag |
| -- to avoid the need for validity checking on assignments. However |
| -- in some cases, we have to do validity checking in order to make |
| -- sure that the setting of this flag is correct. |
| |
| else |
| -- Validate right side if we are validating copies |
| |
| if Validity_Checks_On |
| and then Validity_Check_Copies |
| then |
| -- Skip this if left hand side is an array or record component |
| -- and elementary component validity checks are suppressed. |
| |
| if Nkind_In (Lhs, N_Selected_Component, N_Indexed_Component) |
| and then not Validity_Check_Components |
| then |
| null; |
| else |
| Ensure_Valid (Rhs); |
| end if; |
| |
| -- We can propagate this to the left side where appropriate |
| |
| if Is_Local_Variable_Reference (Lhs) |
| and then not Is_Known_Valid (Entity (Lhs)) |
| and then In_Unconditional_Context (N) |
| then |
| Set_Is_Known_Valid (Entity (Lhs), True); |
| end if; |
| |
| -- Otherwise check to see what should be done |
| |
| -- If left side is a local variable, then we just set its flag to |
| -- indicate that its value may no longer be valid, since we are |
| -- copying a potentially invalid value. |
| |
| elsif Is_Local_Variable_Reference (Lhs) then |
| Set_Is_Known_Valid (Entity (Lhs), False); |
| |
| -- Check for case of a nonlocal variable on the left side which |
| -- is currently known to be valid. In this case, we simply ensure |
| -- that the right side is valid. We only play the game of copying |
| -- validity status for local variables, since we are doing this |
| -- statically, not by tracing the full flow graph. |
| |
| elsif Is_Entity_Name (Lhs) |
| and then Is_Known_Valid (Entity (Lhs)) |
| then |
| -- Note: If Validity_Checking mode is set to none, we ignore |
| -- the Ensure_Valid call so don't worry about that case here. |
| |
| Ensure_Valid (Rhs); |
| |
| -- In all other cases, we can safely copy an invalid value without |
| -- worrying about the status of the left side. Since it is not a |
| -- variable reference it will not be considered |
| -- as being known to be valid in any case. |
| |
| else |
| null; |
| end if; |
| end if; |
| end if; |
| |
| -- Defend against invalid subscripts on left side if we are in standard |
| -- validity checking mode. No need to do this if we are checking all |
| -- subscripts. |
| |
| if Validity_Checks_On |
| and then Validity_Check_Default |
| and then not Validity_Check_Subscripts |
| then |
| Check_Valid_Lvalue_Subscripts (Lhs); |
| end if; |
| |
| exception |
| when RE_Not_Available => |
| return; |
| end Expand_N_Assignment_Statement; |
| |
| ------------------------------ |
| -- Expand_N_Block_Statement -- |
| ------------------------------ |
| |
| -- Encode entity names defined in block statement |
| |
| procedure Expand_N_Block_Statement (N : Node_Id) is |
| begin |
| Qualify_Entity_Names (N); |
| end Expand_N_Block_Statement; |
| |
| ----------------------------- |
| -- Expand_N_Case_Statement -- |
| ----------------------------- |
| |
| procedure Expand_N_Case_Statement (N : Node_Id) is |
| Loc : constant Source_Ptr := Sloc (N); |
| Expr : constant Node_Id := Expression (N); |
| Alt : Node_Id; |
| Len : Nat; |
| Cond : Node_Id; |
| Choice : Node_Id; |
| Chlist : List_Id; |
| |
| begin |
| -- Check for the situation where we know at compile time which branch |
| -- will be taken |
| |
| if Compile_Time_Known_Value (Expr) then |
| Alt := Find_Static_Alternative (N); |
| |
| -- Move statements from this alternative after the case statement. |
| -- They are already analyzed, so will be skipped by the analyzer. |
| |
| Insert_List_After (N, Statements (Alt)); |
| |
| -- That leaves the case statement as a shell. So now we can kill all |
| -- other alternatives in the case statement. |
| |
| Kill_Dead_Code (Expression (N)); |
| |
| declare |
| A : Node_Id; |
| |
| begin |
| -- Loop through case alternatives, skipping pragmas, and skipping |
| -- the one alternative that we select (and therefore retain). |
| |
| A := First (Alternatives (N)); |
| while Present (A) loop |
| if A /= Alt |
| and then Nkind (A) = N_Case_Statement_Alternative |
| then |
| Kill_Dead_Code (Statements (A), Warn_On_Deleted_Code); |
| end if; |
| |
| Next (A); |
| end loop; |
| end; |
| |
| Rewrite (N, Make_Null_Statement (Loc)); |
| return; |
| end if; |
| |
| -- Here if the choice is not determined at compile time |
| |
| declare |
| Last_Alt : constant Node_Id := Last (Alternatives (N)); |
| |
| Others_Present : Boolean; |
| Others_Node : Node_Id; |
| |
| Then_Stms : List_Id; |
| Else_Stms : List_Id; |
| |
| begin |
| if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then |
| Others_Present := True; |
| Others_Node := Last_Alt; |
| else |
| Others_Present := False; |
| end if; |
| |
| -- First step is to worry about possible invalid argument. The RM |
| -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is |
| -- outside the base range), then Constraint_Error must be raised. |
| |
| -- Case of validity check required (validity checks are on, the |
| -- expression is not known to be valid, and the case statement |
| -- comes from source -- no need to validity check internally |
| -- generated case statements). |
| |
| if Validity_Check_Default then |
| Ensure_Valid (Expr); |
| end if; |
| |
| -- If there is only a single alternative, just replace it with the |
| -- sequence of statements since obviously that is what is going to |
| -- be executed in all cases. |
| |
| Len := List_Length (Alternatives (N)); |
| |
| if Len = 1 then |
| -- We still need to evaluate the expression if it has any |
| -- side effects. |
| |
| Remove_Side_Effects (Expression (N)); |
| |
| Insert_List_After (N, Statements (First (Alternatives (N)))); |
| |
| -- That leaves the case statement as a shell. The alternative that |
| -- will be executed is reset to a null list. So now we can kill |
| -- the entire case statement. |
| |
| Kill_Dead_Code (Expression (N)); |
| Rewrite (N, Make_Null_Statement (Loc)); |
| return; |
| end if; |
| |
| -- An optimization. If there are only two alternatives, and only |
| -- a single choice, then rewrite the whole case statement as an |
| -- if statement, since this can result in susbequent optimizations. |
| -- This helps not only with case statements in the source of a |
| -- simple form, but also with generated code (discriminant check |
| -- functions in particular) |
| |
| if Len = 2 then |
| Chlist := Discrete_Choices (First (Alternatives (N))); |
| |
| if List_Length (Chlist) = 1 then |
| Choice := First (Chlist); |
| |
| Then_Stms := Statements (First (Alternatives (N))); |
| Else_Stms := Statements (Last (Alternatives (N))); |
| |
| -- For TRUE, generate "expression", not expression = true |
| |
| if Nkind (Choice) = N_Identifier |
| and then Entity (Choice) = Standard_True |
| then |
| Cond := Expression (N); |
| |
| -- For FALSE, generate "expression" and switch then/else |
| |
| elsif Nkind (Choice) = N_Identifier |
| and then Entity (Choice) = Standard_False |
| then |
| Cond := Expression (N); |
| Else_Stms := Statements (First (Alternatives (N))); |
| Then_Stms := Statements (Last (Alternatives (N))); |
| |
| -- For a range, generate "expression in range" |
| |
| elsif Nkind (Choice) = N_Range |
| or else (Nkind (Choice) = N_Attribute_Reference |
| and then Attribute_Name (Choice) = Name_Range) |
| or else (Is_Entity_Name (Choice) |
| and then Is_Type (Entity (Choice))) |
| or else Nkind (Choice) = N_Subtype_Indication |
| then |
| Cond := |
| Make_In (Loc, |
| Left_Opnd => Expression (N), |
| Right_Opnd => Relocate_Node (Choice)); |
| |
| -- For any other subexpression "expression = value" |
| |
| else |
| Cond := |
| Make_Op_Eq (Loc, |
| Left_Opnd => Expression (N), |
| Right_Opnd => Relocate_Node (Choice)); |
| end if; |
| |
| -- Now rewrite the case as an IF |
| |
| Rewrite (N, |
| Make_If_Statement (Loc, |
| Condition => Cond, |
| Then_Statements => Then_Stms, |
| Else_Statements => Else_Stms)); |
| Analyze (N); |
| return; |
| end if; |
| end if; |
| |
| -- If the last alternative is not an Others choice, replace it with |
| -- an N_Others_Choice. Note that we do not bother to call Analyze on |
| -- the modified case statement, since it's only effect would be to |
| -- compute the contents of the Others_Discrete_Choices which is not |
| -- needed by the back end anyway. |
| |
| -- The reason we do this is that the back end always needs some |
| -- default for a switch, so if we have not supplied one in the |
| -- processing above for validity checking, then we need to supply |
| -- one here. |
| |
| if not Others_Present then |
| Others_Node := Make_Others_Choice (Sloc (Last_Alt)); |
| Set_Others_Discrete_Choices |
| (Others_Node, Discrete_Choices (Last_Alt)); |
| Set_Discrete_Choices (Last_Alt, New_List (Others_Node)); |
| end if; |
| end; |
| end Expand_N_Case_Statement; |
| |
| ----------------------------- |
| -- Expand_N_Exit_Statement -- |
| ----------------------------- |
| |
| -- The only processing required is to deal with a possible C/Fortran |
| -- boolean value used as the condition for the exit statement. |
| |
| procedure Expand_N_Exit_Statement (N : Node_Id) is |
| begin |
| Adjust_Condition (Condition (N)); |
| end Expand_N_Exit_Statement; |
| |
| ---------------------------------------- |
| -- Expand_N_Extended_Return_Statement -- |
| ---------------------------------------- |
| |
| -- If there is a Handled_Statement_Sequence, we rewrite this: |
| |
| -- return Result : T := <expression> do |
| -- <handled_seq_of_stms> |
| -- end return; |
| |
| -- to be: |
| |
| -- declare |
| -- Result : T := <expression>; |
| -- begin |
| -- <handled_seq_of_stms> |
| -- return Result; |
| -- end; |
| |
| -- Otherwise (no Handled_Statement_Sequence), we rewrite this: |
| |
| -- return Result : T := <expression>; |
| |
| -- to be: |
| |
| -- return <expression>; |
| |
| -- unless it's build-in-place or there's no <expression>, in which case |
| -- we generate: |
| |
| -- declare |
| -- Result : T := <expression>; |
| -- begin |
| -- return Result; |
| -- end; |
| |
| -- Note that this case could have been written by the user as an extended |
| -- return statement, or could have been transformed to this from a simple |
| -- return statement. |
| |
| -- That is, we need to have a reified return object if there are statements |
| -- (which might refer to it) or if we're doing build-in-place (so we can |
| -- set its address to the final resting place or if there is no expression |
| -- (in which case default initial values might need to be set). |
| |
| procedure Expand_N_Extended_Return_Statement (N : Node_Id) is |
| Loc : constant Source_Ptr := Sloc (N); |
| |
| Return_Object_Entity : constant Entity_Id := |
| First_Entity (Return_Statement_Entity (N)); |
| Return_Object_Decl : constant Node_Id := |
| Parent (Return_Object_Entity); |
| Parent_Function : constant Entity_Id := |
| Return_Applies_To (Return_Statement_Entity (N)); |
| Is_Build_In_Place : constant Boolean := |
| Is_Build_In_Place_Function (Parent_Function); |
| |
| Return_Stm : Node_Id; |
| Statements : List_Id; |
| Handled_Stm_Seq : Node_Id; |
| Result : Node_Id; |
| Exp : Node_Id; |
| |
| function Move_Activation_Chain return Node_Id; |
| -- Construct a call to System.Tasking.Stages.Move_Activation_Chain |
| -- with parameters: |
| -- From current activation chain |
| -- To activation chain passed in by the caller |
| -- New_Master master passed in by the caller |
| |
| function Move_Final_List return Node_Id; |
| -- Construct call to System.Finalization_Implementation.Move_Final_List |
| -- with parameters: |
| -- |
| -- From finalization list of the return statement |
| -- To finalization list passed in by the caller |
| |
| --------------------------- |
| -- Move_Activation_Chain -- |
| --------------------------- |
| |
| function Move_Activation_Chain return Node_Id is |
| Activation_Chain_Formal : constant Entity_Id := |
| Build_In_Place_Formal |
| (Parent_Function, BIP_Activation_Chain); |
| To : constant Node_Id := |
| New_Reference_To |
| (Activation_Chain_Formal, Loc); |
| Master_Formal : constant Entity_Id := |
| Build_In_Place_Formal |
| (Parent_Function, BIP_Master); |
| New_Master : constant Node_Id := |
| New_Reference_To (Master_Formal, Loc); |
| |
| Chain_Entity : Entity_Id; |
| From : Node_Id; |
| |
| begin |
| Chain_Entity := First_Entity (Return_Statement_Entity (N)); |
| while Chars (Chain_Entity) /= Name_uChain loop |
| Chain_Entity := Next_Entity (Chain_Entity); |
| end loop; |
| |
| From := |
| Make_Attribute_Reference (Loc, |
| Prefix => New_Reference_To (Chain_Entity, Loc), |
| Attribute_Name => Name_Unrestricted_Access); |
| -- ??? Not clear why "Make_Identifier (Loc, Name_uChain)" doesn't |
| -- work, instead of "New_Reference_To (Chain_Entity, Loc)" above. |
| |
| return |
| Make_Procedure_Call_Statement (Loc, |
| Name => New_Reference_To (RTE (RE_Move_Activation_Chain), Loc), |
| Parameter_Associations => New_List (From, To, New_Master)); |
| end Move_Activation_Chain; |
| |
| --------------------- |
| -- Move_Final_List -- |
| --------------------- |
| |
| function Move_Final_List return Node_Id is |
| Flist : constant Entity_Id := |
| Finalization_Chain_Entity (Return_Statement_Entity (N)); |
| |
| From : constant Node_Id := New_Reference_To (Flist, Loc); |
| |
| Caller_Final_List : constant Entity_Id := |
| Build_In_Place_Formal |
| (Parent_Function, BIP_Final_List); |
| |
| To : constant Node_Id := New_Reference_To (Caller_Final_List, Loc); |
| |
| begin |
| -- Catch cases where a finalization chain entity has not been |
| -- associated with the return statement entity. |
| |
| pragma Assert (Present (Flist)); |
| |
| -- Build required call |
| |
| return |
| Make_If_Statement (Loc, |
| Condition => |
| Make_Op_Ne (Loc, |
| Left_Opnd => New_Copy (From), |
| Right_Opnd => New_Node (N_Null, Loc)), |
| Then_Statements => |
| New_List ( |
| Make_Procedure_Call_Statement (Loc, |
| Name => New_Reference_To (RTE (RE_Move_Final_List), Loc), |
| Parameter_Associations => New_List (From, To)))); |
| end Move_Final_List; |
| |
| -- Start of processing for Expand_N_Extended_Return_Statement |
| |
| begin |
| if Nkind (Return_Object_Decl) = N_Object_Declaration then |
| Exp := Expression (Return_Object_Decl); |
| else |
| Exp := Empty; |
| end if; |
| |
| Handled_Stm_Seq := Handled_Statement_Sequence (N); |
| |
| -- Build a simple_return_statement that returns the return object when |
| -- there is a statement sequence, or no expression, or the result will |
| -- be built in place. Note however that we currently do this for all |
| -- composite cases, even though nonlimited composite results are not yet |
| -- built in place (though we plan to do so eventually). |
| |
| if Present (Handled_Stm_Seq) |
| or else Is_Composite_Type (Etype (Parent_Function)) |
| or else No (Exp) |
| then |
| if No (Handled_Stm_Seq) then |
| Statements := New_List; |
| |
| -- If the extended return has a handled statement sequence, then wrap |
| -- it in a block and use the block as the first statement. |
| |
| else |
| Statements := |
| New_List (Make_Block_Statement (Loc, |
| Declarations => New_List, |
| Handled_Statement_Sequence => Handled_Stm_Seq)); |
| end if; |
| |
| -- If control gets past the above Statements, we have successfully |
| -- completed the return statement. If the result type has controlled |
| -- parts and the return is for a build-in-place function, then we |
| -- call Move_Final_List to transfer responsibility for finalization |
| -- of the return object to the caller. An alternative would be to |
| -- declare a Success flag in the function, initialize it to False, |
| -- and set it to True here. Then move the Move_Final_List call into |
| -- the cleanup code, and check Success. If Success then make a call |
| -- to Move_Final_List else do finalization. Then we can remove the |
| -- abort-deferral and the nulling-out of the From parameter from |
| -- Move_Final_List. Note that the current method is not quite correct |
| -- in the rather obscure case of a select-then-abort statement whose |
| -- abortable part contains the return statement. |
| |
| -- We test the type of the expression as well as the return type |
| -- of the function, because the latter may be a class-wide type |
| -- which is always treated as controlled, while the expression itself |
| -- has to have a definite type. The expression may be absent if a |
| -- constrained aggregate has been expanded into component assignments |
| -- so we have to check for this as well. |
| |
| if Is_Build_In_Place |
| and then Controlled_Type (Etype (Parent_Function)) |
| then |
| if not Is_Class_Wide_Type (Etype (Parent_Function)) |
| or else |
| (Present (Exp) |
| and then Controlled_Type (Etype (Exp))) |
| then |
| Append_To (Statements, Move_Final_List); |
| end if; |
| end if; |
| |
| -- Similarly to the above Move_Final_List, if the result type |
| -- contains tasks, we call Move_Activation_Chain. Later, the cleanup |
| -- code will call Complete_Master, which will terminate any |
| -- unactivated tasks belonging to the return statement master. But |
| -- Move_Activation_Chain updates their master to be that of the |
| -- caller, so they will not be terminated unless the return statement |
| -- completes unsuccessfully due to exception, abort, goto, or exit. |
| -- As a formality, we test whether the function requires the result |
| -- to be built in place, though that's necessarily true for the case |
| -- of result types with task parts. |
| |
| if Is_Build_In_Place and Has_Task (Etype (Parent_Function)) then |
| Append_To (Statements, Move_Activation_Chain); |
| end if; |
| |
| -- Build a simple_return_statement that returns the return object |
| |
| Return_Stm := |
| Make_Simple_Return_Statement (Loc, |
| Expression => New_Occurrence_Of (Return_Object_Entity, Loc)); |
| Append_To (Statements, Return_Stm); |
| |
| Handled_Stm_Seq := |
| Make_Handled_Sequence_Of_Statements (Loc, Statements); |
| end if; |
| |
| -- Case where we build a block |
| |
| if Present (Handled_Stm_Seq) then |
| Result := |
| Make_Block_Statement (Loc, |
| Declarations => Return_Object_Declarations (N), |
| Handled_Statement_Sequence => Handled_Stm_Seq); |
| |
| -- We set the entity of the new block statement to be that of the |
| -- return statement. This is necessary so that various fields, such |
| -- as Finalization_Chain_Entity carry over from the return statement |
| -- to the block. Note that this block is unusual, in that its entity |
| -- is an E_Return_Statement rather than an E_Block. |
| |
| Set_Identifier |
| (Result, New_Occurrence_Of (Return_Statement_Entity (N), Loc)); |
| |
| -- If the object decl was already rewritten as a renaming, then |
| -- we don't want to do the object allocation and transformation of |
| -- of the return object declaration to a renaming. This case occurs |
| -- when the return object is initialized by a call to another |
| -- build-in-place function, and that function is responsible for the |
| -- allocation of the return object. |
| |
| if Is_Build_In_Place |
| and then |
| Nkind (Return_Object_Decl) = N_Object_Renaming_Declaration |
| then |
| Set_By_Ref (Return_Stm); -- Return build-in-place results by ref |
| |
| elsif Is_Build_In_Place then |
| |
| -- Locate the implicit access parameter associated with the |
| -- caller-supplied return object and convert the return |
| -- statement's return object declaration to a renaming of a |
| -- dereference of the access parameter. If the return object's |
| -- declaration includes an expression that has not already been |
| -- expanded as separate assignments, then add an assignment |
| -- statement to ensure the return object gets initialized. |
| |
| -- declare |
| -- Result : T [:= <expression>]; |
| -- begin |
| -- ... |
| |
| -- is converted to |
| |
| -- declare |
| -- Result : T renames FuncRA.all; |
| -- [Result := <expression;] |
| -- begin |
| -- ... |
| |
| declare |
| Return_Obj_Id : constant Entity_Id := |
| Defining_Identifier (Return_Object_Decl); |
| Return_Obj_Typ : constant Entity_Id := Etype (Return_Obj_Id); |
| Return_Obj_Expr : constant Node_Id := |
| Expression (Return_Object_Decl); |
| Result_Subt : constant Entity_Id := |
| Etype (Parent_Function); |
| Constr_Result : constant Boolean := |
| Is_Constrained (Result_Subt); |
| Obj_Alloc_Formal : Entity_Id; |
| Object_Access : Entity_Id; |
| Obj_Acc_Deref : Node_Id; |
| Init_Assignment : Node_Id := Empty; |
| |
| begin |
| -- Build-in-place results must be returned by reference |
| |
| Set_By_Ref (Return_Stm); |
| |
| -- Retrieve the implicit access parameter passed by the caller |
| |
| Object_Access := |
| Build_In_Place_Formal (Parent_Function, BIP_Object_Access); |
| |
| -- If the return object's declaration includes an expression |
| -- and the declaration isn't marked as No_Initialization, then |
| -- we need to generate an assignment to the object and insert |
| -- it after the declaration before rewriting it as a renaming |
| -- (otherwise we'll lose the initialization). |
| |
| if Present (Return_Obj_Expr) |
| and then not No_Initialization (Return_Object_Decl) |
| then |
| Init_Assignment := |
| Make_Assignment_Statement (Loc, |
| Name => New_Reference_To (Return_Obj_Id, Loc), |
| Expression => Relocate_Node (Return_Obj_Expr)); |
| Set_Etype (Name (Init_Assignment), Etype (Return_Obj_Id)); |
| Set_Assignment_OK (Name (Init_Assignment)); |
| Set_No_Ctrl_Actions (Init_Assignment); |
| |
| Set_Parent (Name (Init_Assignment), Init_Assignment); |
| Set_Parent (Expression (Init_Assignment), Init_Assignment); |
| |
| Set_Expression (Return_Object_Decl, Empty); |
| |
| if Is_Class_Wide_Type (Etype (Return_Obj_Id)) |
| and then not Is_Class_Wide_Type |
| (Etype (Expression (Init_Assignment))) |
| then |
| Rewrite (Expression (Init_Assignment), |
| Make_Type_Conversion (Loc, |
| Subtype_Mark => |
| New_Occurrence_Of |
| (Etype (Return_Obj_Id), Loc), |
| Expression => |
| Relocate_Node (Expression (Init_Assignment)))); |
| end if; |
| |
| -- In the case of functions where the calling context can |
| -- determine the form of allocation needed, initialization |
| -- is done with each part of the if statement that handles |
| -- the different forms of allocation (this is true for |
| -- unconstrained and tagged result subtypes). |
| |
| if Constr_Result |
| and then not Is_Tagged_Type (Underlying_Type (Result_Subt)) |
| then |
| Insert_After (Return_Object_Decl, Init_Assignment); |
| end if; |
| end if; |
| |
| -- When the function's subtype is unconstrained, a run-time |
| -- test is needed to determine the form of allocation to use |
| -- for the return object. The function has an implicit formal |
| -- parameter indicating this. If the BIP_Alloc_Form formal has |
| -- the value one, then the caller has passed access to an |
| -- existing object for use as the return object. If the value |
| -- is two, then the return object must be allocated on the |
| -- secondary stack. Otherwise, the object must be allocated in |
| -- a storage pool (currently only supported for the global |
| -- heap, user-defined storage pools TBD ???). We generate an |
| -- if statement to test the implicit allocation formal and |
| -- initialize a local access value appropriately, creating |
| -- allocators in the secondary stack and global heap cases. |
| -- The special formal also exists and must be tested when the |
| -- function has a tagged result, even when the result subtype |
| -- is constrained, because in general such functions can be |
| -- called in dispatching contexts and must be handled similarly |
| -- to functions with a class-wide result. |
| |
| if not Constr_Result |
| or else Is_Tagged_Type (Underlying_Type (Result_Subt)) |
| then |
| Obj_Alloc_Formal := |
| Build_In_Place_Formal (Parent_Function, BIP_Alloc_Form); |
| |
| declare |
| Ref_Type : Entity_Id; |
| Ptr_Type_Decl : Node_Id; |
| Alloc_Obj_Id : Entity_Id; |
| Alloc_Obj_Decl : Node_Id; |
| Alloc_If_Stmt : Node_Id; |
| SS_Allocator : Node_Id; |
| Heap_Allocator : Node_Id; |
| |
| begin |
| -- Reuse the itype created for the function's implicit |
| -- access formal. This avoids the need to create a new |
| -- access type here, plus it allows assigning the access |
| -- formal directly without applying a conversion. |
| |
| -- Ref_Type := Etype (Object_Access); |
| |
| -- Create an access type designating the function's |
| -- result subtype. |
| |
| Ref_Type := |
| Make_Defining_Identifier (Loc, New_Internal_Name ('A')); |
| |
| Ptr_Type_Decl := |
| Make_Full_Type_Declaration (Loc, |
| Defining_Identifier => Ref_Type, |
| Type_Definition => |
| Make_Access_To_Object_Definition (Loc, |
| All_Present => True, |
| Subtype_Indication => |
| New_Reference_To (Return_Obj_Typ, Loc))); |
| |
| Insert_Before (Return_Object_Decl, Ptr_Type_Decl); |
| |
| -- Create an access object that will be initialized to an |
| -- access value denoting the return object, either coming |
| -- from an implicit access value passed in by the caller |
| -- or from the result of an allocator. |
| |
| Alloc_Obj_Id := |
| Make_Defining_Identifier (Loc, |
| Chars => New_Internal_Name ('R')); |
| Set_Etype (Alloc_Obj_Id, Ref_Type); |
| |
| Alloc_Obj_Decl := |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Alloc_Obj_Id, |
| Object_Definition => New_Reference_To |
| (Ref_Type, Loc)); |
| |
| Insert_Before (Return_Object_Decl, Alloc_Obj_Decl); |
| |
| -- Create allocators for both the secondary stack and |
| -- global heap. If there's an initialization expression, |
| -- then create these as initialized allocators. |
| |
| if Present (Return_Obj_Expr) |
| and then not No_Initialization (Return_Object_Decl) |
| then |
| Heap_Allocator := |
| Make_Allocator (Loc, |
| Expression => |
| Make_Qualified_Expression (Loc, |
| Subtype_Mark => |
| New_Reference_To (Return_Obj_Typ, Loc), |
| Expression => |
| New_Copy_Tree (Return_Obj_Expr))); |
| |
| SS_Allocator := New_Copy_Tree (Heap_Allocator); |
| |
| else |
| -- If the function returns a class-wide type we cannot |
| -- use the return type for the allocator. Instead we |
| -- use the type of the expression, which must be an |
| -- aggregate of a definite type. |
| |
| if Is_Class_Wide_Type (Return_Obj_Typ) then |
| Heap_Allocator := |
| Make_Allocator (Loc, |
| New_Reference_To |
| (Etype (Return_Obj_Expr), Loc)); |
| else |
| Heap_Allocator := |
| Make_Allocator (Loc, |
| New_Reference_To (Return_Obj_Typ, Loc)); |
| end if; |
| |
| -- If the object requires default initialization then |
| -- that will happen later following the elaboration of |
| -- the object renaming. If we don't turn it off here |
| -- then the object will be default initialized twice. |
| |
| Set_No_Initialization (Heap_Allocator); |
| |
| SS_Allocator := New_Copy_Tree (Heap_Allocator); |
| end if; |
| |
| -- The allocator is returned on the secondary stack. We |
| -- don't do this on VM targets, since the SS is not used. |
| |
| if VM_Target = No_VM then |
| Set_Storage_Pool (SS_Allocator, RTE (RE_SS_Pool)); |
| Set_Procedure_To_Call |
| (SS_Allocator, RTE (RE_SS_Allocate)); |
| |
| -- The allocator is returned on the secondary stack, |
| -- so indicate that the function return, as well as |
| -- the block that encloses the allocator, must not |
| -- release it. The flags must be set now because the |
| -- decision to use the secondary stack is done very |
| -- late in the course of expanding the return |
| -- statement, past the point where these flags are |
| -- normally set. |
| |
| Set_Sec_Stack_Needed_For_Return (Parent_Function); |
| Set_Sec_Stack_Needed_For_Return |
| (Return_Statement_Entity (N)); |
| Set_Uses_Sec_Stack (Parent_Function); |
| Set_Uses_Sec_Stack (Return_Statement_Entity (N)); |
| end if; |
| |
| -- Create an if statement to test the BIP_Alloc_Form |
| -- formal and initialize the access object to either the |
| -- BIP_Object_Access formal (BIP_Alloc_Form = 0), the |
| -- result of allocating the object in the secondary stack |
| -- (BIP_Alloc_Form = 1), or else an allocator to create |
| -- the return object in the heap (BIP_Alloc_Form = 2). |
| |
| -- ??? An unchecked type conversion must be made in the |
| -- case of assigning the access object formal to the |
| -- local access object, because a normal conversion would |
| -- be illegal in some cases (such as converting access- |
| -- to-unconstrained to access-to-constrained), but the |
| -- the unchecked conversion will presumably fail to work |
| -- right in just such cases. It's not clear at all how to |
| -- handle this. ??? |
| |
| Alloc_If_Stmt := |
| Make_If_Statement (Loc, |
| Condition => |
| Make_Op_Eq (Loc, |
| Left_Opnd => |
| New_Reference_To (Obj_Alloc_Formal, Loc), |
| Right_Opnd => |
| Make_Integer_Literal (Loc, |
| UI_From_Int (BIP_Allocation_Form'Pos |
| (Caller_Allocation)))), |
| Then_Statements => |
| New_List (Make_Assignment_Statement (Loc, |
| Name => |
| New_Reference_To |
| (Alloc_Obj_Id, Loc), |
| Expression => |
| Make_Unchecked_Type_Conversion (Loc, |
| Subtype_Mark => |
| New_Reference_To (Ref_Type, Loc), |
| Expression => |
| New_Reference_To |
| (Object_Access, Loc)))), |
| Elsif_Parts => |
| New_List (Make_Elsif_Part (Loc, |
| Condition => |
| Make_Op_Eq (Loc, |
| Left_Opnd => |
| New_Reference_To |
| (Obj_Alloc_Formal, Loc), |
| Right_Opnd => |
| Make_Integer_Literal (Loc, |
| UI_From_Int ( |
| BIP_Allocation_Form'Pos |
| (Secondary_Stack)))), |
| Then_Statements => |
| New_List |
| (Make_Assignment_Statement (Loc, |
| Name => |
| New_Reference_To |
| (Alloc_Obj_Id, Loc), |
| Expression => |
| SS_Allocator)))), |
| Else_Statements => |
| New_List (Make_Assignment_Statement (Loc, |
| Name => |
| New_Reference_To |
| (Alloc_Obj_Id, Loc), |
| Expression => |
| Heap_Allocator))); |
| |
| -- If a separate initialization assignment was created |
| -- earlier, append that following the assignment of the |
| -- implicit access formal to the access object, to ensure |
| -- that the return object is initialized in that case. |
| -- In this situation, the target of the assignment must |
| -- be rewritten to denote a derference of the access to |
| -- the return object passed in by the caller. |
| |
| if Present (Init_Assignment) then |
| Rewrite (Name (Init_Assignment), |
| Make_Explicit_Dereference (Loc, |
| Prefix => New_Reference_To (Alloc_Obj_Id, Loc))); |
| Set_Etype |
| (Name (Init_Assignment), Etype (Return_Obj_Id)); |
| |
| Append_To |
| (Then_Statements (Alloc_If_Stmt), |
| Init_Assignment); |
| end if; |
| |
| Insert_Before (Return_Object_Decl, Alloc_If_Stmt); |
| |
| -- Remember the local access object for use in the |
| -- dereference of the renaming created below. |
| |
| Object_Access := Alloc_Obj_Id; |
| end; |
| end if; |
| |
| -- Replace the return object declaration with a renaming of a |
| -- dereference of the access value designating the return |
| -- object. |
| |
| Obj_Acc_Deref := |
| Make_Explicit_Dereference (Loc, |
| Prefix => New_Reference_To (Object_Access, Loc)); |
| |
| Rewrite (Return_Object_Decl, |
| Make_Object_Renaming_Declaration (Loc, |
| Defining_Identifier => Return_Obj_Id, |
| Access_Definition => Empty, |
| Subtype_Mark => New_Occurrence_Of |
| (Return_Obj_Typ, Loc), |
| Name => Obj_Acc_Deref)); |
| |
| Set_Renamed_Object (Return_Obj_Id, Obj_Acc_Deref); |
| end; |
| end if; |
| |
| -- Case where we do not build a block |
| |
| else |
| -- We're about to drop Return_Object_Declarations on the floor, so |
| -- we need to insert it, in case it got expanded into useful code. |
| |
| Insert_List_Before (N, Return_Object_Declarations (N)); |
| |
| -- Build simple_return_statement that returns the expression directly |
| |
| Return_Stm := Make_Simple_Return_Statement (Loc, Expression => Exp); |
| |
| Result := Return_Stm; |
| end if; |
| |
| -- Set the flag to prevent infinite recursion |
| |
| Set_Comes_From_Extended_Return_Statement (Return_Stm); |
| |
| Rewrite (N, Result); |
| Analyze (N); |
| end Expand_N_Extended_Return_Statement; |
| |
| ----------------------------- |
| -- Expand_N_Goto_Statement -- |
| ----------------------------- |
| |
| -- Add poll before goto if polling active |
| |
| procedure Expand_N_Goto_Statement (N : Node_Id) is |
| begin |
| Generate_Poll_Call (N); |
| end Expand_N_Goto_Statement; |
| |
| --------------------------- |
| -- Expand_N_If_Statement -- |
| --------------------------- |
| |
| -- First we deal with the case of C and Fortran convention boolean values, |
| -- with zero/non-zero semantics. |
| |
| -- Second, we deal with the obvious rewriting for the cases where the |
| -- condition of the IF is known at compile time to be True or False. |
| |
| -- Third, we remove elsif parts which have non-empty Condition_Actions |
| -- and rewrite as independent if statements. For example: |
| |
| -- if x then xs |
| -- elsif y then ys |
| -- ... |
| -- end if; |
| |
| -- becomes |
| -- |
| -- if x then xs |
| -- else |
| -- <<condition actions of y>> |
| -- if y then ys |
| -- ... |
| -- end if; |
| -- end if; |
| |
| -- This rewriting is needed if at least one elsif part has a non-empty |
| -- Condition_Actions list. We also do the same processing if there is a |
| -- constant condition in an elsif part (in conjunction with the first |
| -- processing step mentioned above, for the recursive call made to deal |
| -- with the created inner if, this deals with properly optimizing the |
| -- cases of constant elsif conditions). |
| |
| procedure Expand_N_If_Statement (N : Node_Id) is |
| Loc : constant Source_Ptr := Sloc (N); |
| Hed : Node_Id; |
| E : Node_Id; |
| New_If : Node_Id; |
| |
| Warn_If_Deleted : constant Boolean := |
| Warn_On_Deleted_Code and then Comes_From_Source (N); |
| -- Indicates whether we want warnings when we delete branches of the |
| -- if statement based on constant condition analysis. We never want |
| -- these warnings for expander generated code. |
| |
| begin |
| Adjust_Condition (Condition (N)); |
| |
| -- The following loop deals with constant conditions for the IF. We |
| -- need a loop because as we eliminate False conditions, we grab the |
| -- first elsif condition and use it as the primary condition. |
| |
| while Compile_Time_Known_Value (Condition (N)) loop |
| |
| -- If condition is True, we can simply rewrite the if statement now |
| -- by replacing it by the series of then statements. |
| |
| if Is_True (Expr_Value (Condition (N))) then |
| |
| -- All the else parts can be killed |
| |
| Kill_Dead_Code (Elsif_Parts (N), Warn_If_Deleted); |
| Kill_Dead_Code (Else_Statements (N), Warn_If_Deleted); |
| |
| Hed := Remove_Head (Then_Statements (N)); |
| Insert_List_After (N, Then_Statements (N)); |
| Rewrite (N, Hed); |
| return; |
| |
| -- If condition is False, then we can delete the condition and |
| -- the Then statements |
| |
| else |
| -- We do not delete the condition if constant condition warnings |
| -- are enabled, since otherwise we end up deleting the desired |
| -- warning. Of course the backend will get rid of this True/False |
| -- test anyway, so nothing is lost here. |
| |
| if not Constant_Condition_Warnings then |
| Kill_Dead_Code (Condition (N)); |
| end if; |
| |
| Kill_Dead_Code (Then_Statements (N), Warn_If_Deleted); |
| |
| -- If there are no elsif statements, then we simply replace the |
| -- entire if statement by the sequence of else statements. |
| |
| if No (Elsif_Parts (N)) then |
| if No (Else_Statements (N)) |
| or else Is_Empty_List (Else_Statements (N)) |
| then |
| Rewrite (N, |
| Make_Null_Statement (Sloc (N))); |
| else |
| Hed := Remove_Head (Else_Statements (N)); |
| Insert_List_After (N, Else_Statements (N)); |
| Rewrite (N, Hed); |
| end if; |
| |
| return; |
| |
| -- If there are elsif statements, the first of them becomes the |
| -- if/then section of the rebuilt if statement This is the case |
| -- where we loop to reprocess this copied condition. |
| |
| else |
| Hed := Remove_Head (Elsif_Parts (N)); |
| Insert_Actions (N, Condition_Actions (Hed)); |
| Set_Condition (N, Condition (Hed)); |
| Set_Then_Statements (N, Then_Statements (Hed)); |
| |
| -- Hed might have been captured as the condition determining |
| -- the current value for an entity. Now it is detached from |
| -- the tree, so a Current_Value pointer in the condition might |
| -- need to be updated. |
| |
| Set_Current_Value_Condition (N); |
| |
| if Is_Empty_List (Elsif_Parts (N)) then |
| Set_Elsif_Parts (N, No_List); |
| end if; |
| end if; |
| end if; |
| end loop; |
| |
| -- Loop through elsif parts, dealing with constant conditions and |
| -- possible expression actions that are present. |
| |
| if Present (Elsif_Parts (N)) then |
| E := First (Elsif_Parts (N)); |
| while Present (E) loop |
| Adjust_Condition (Condition (E)); |
| |
| -- If there are condition actions, then rewrite the if statement |
| -- as indicated above. We also do the same rewrite for a True or |
| -- False condition. The further processing of this constant |
| -- condition is then done by the recursive call to expand the |
| -- newly created if statement |
| |
| if Present (Condition_Actions (E)) |
| or else Compile_Time_Known_Value (Condition (E)) |
| then |
| -- Note this is not an implicit if statement, since it is part |
| -- of an explicit if statement in the source (or of an implicit |
| -- if statement that has already been tested). |
| |
| New_If := |
| Make_If_Statement (Sloc (E), |
| Condition => Condition (E), |
| Then_Statements => Then_Statements (E), |
| Elsif_Parts => No_List, |
| Else_Statements => Else_Statements (N)); |
| |
| -- Elsif parts for new if come from remaining elsif's of parent |
| |
| while Present (Next (E)) loop |
| if No (Elsif_Parts (New_If)) then |
| Set_Elsif_Parts (New_If, New_List); |
| end if; |
| |
| Append (Remove_Next (E), Elsif_Parts (New_If)); |
| end loop; |
| |
| Set_Else_Statements (N, New_List (New_If)); |
| |
| if Present (Condition_Actions (E)) then |
| Insert_List_Before (New_If, Condition_Actions (E)); |
| end if; |
| |
| Remove (E); |
| |
| if Is_Empty_List (Elsif_Parts (N)) then |
| Set_Elsif_Parts (N, No_List); |
| end if; |
| |
| Analyze (New_If); |
| return; |
| |
| -- No special processing for that elsif part, move to next |
| |
| else |
| Next (E); |
| end if; |
| end loop; |
| end if; |
| |
| -- Some more optimizations applicable if we still have an IF statement |
| |
| if Nkind (N) /= N_If_Statement then |
| return; |
| end if; |
| |
| -- Another optimization, special cases that can be simplified |
| |
| -- if expression then |
| -- return true; |
| -- else |
| -- return false; |
| -- end if; |
| |
| -- can be changed to: |
| |
| -- return expression; |
| |
| -- and |
| |
| -- if expression then |
| -- return false; |
| -- else |
| -- return true; |
| -- end if; |
| |
| -- can be changed to: |
| |
| -- return not (expression); |
| |
| if Nkind (N) = N_If_Statement |
| and then No (Elsif_Parts (N)) |
| and then Present (Else_Statements (N)) |
| and then List_Length (Then_Statements (N)) = 1 |
| and then List_Length (Else_Statements (N)) = 1 |
| then |
| declare |
| Then_Stm : constant Node_Id := First (Then_Statements (N)); |
| Else_Stm : constant Node_Id := First (Else_Statements (N)); |
| |
| begin |
| if Nkind (Then_Stm) = N_Simple_Return_Statement |
| and then |
| Nkind (Else_Stm) = N_Simple_Return_Statement |
| then |
| declare |
| Then_Expr : constant Node_Id := Expression (Then_Stm); |
| Else_Expr : constant Node_Id := Expression (Else_Stm); |
| |
| begin |
| if Nkind (Then_Expr) = N_Identifier |
| and then |
| Nkind (Else_Expr) = N_Identifier |
| then |
| if Entity (Then_Expr) = Standard_True |
| and then Entity (Else_Expr) = Standard_False |
| then |
| Rewrite (N, |
| Make_Simple_Return_Statement (Loc, |
| Expression => Relocate_Node (Condition (N)))); |
| Analyze (N); |
| return; |
| |
| elsif Entity (Then_Expr) = Standard_False |
| and then Entity (Else_Expr) = Standard_True |
| then |
| Rewrite (N, |
| Make_Simple_Return_Statement (Loc, |
| Expression => |
| Make_Op_Not (Loc, |
| Right_Opnd => Relocate_Node (Condition (N))))); |
| Analyze (N); |
| return; |
| end if; |
| end if; |
| end; |
| end if; |
| end; |
| end if; |
| end Expand_N_If_Statement; |
| |
| ----------------------------- |
| -- Expand_N_Loop_Statement -- |
| ----------------------------- |
| |
| -- 1. Deal with while condition for C/Fortran boolean |
| -- 2. Deal with loops with a non-standard enumeration type range |
| -- 3. Deal with while loops where Condition_Actions is set |
| -- 4. Insert polling call if required |
| |
| procedure Expand_N_Loop_Statement (N : Node_Id) is |
| Loc : constant Source_Ptr := Sloc (N); |
| Isc : constant Node_Id := Iteration_Scheme (N); |
| |
| begin |
| if Present (Isc) then |
| Adjust_Condition (Condition (Isc)); |
| end if; |
| |
| if Is_Non_Empty_List (Statements (N)) then |
| Generate_Poll_Call (First (Statements (N))); |
| end if; |
| |
| -- Nothing more to do for plain loop with no iteration scheme |
| |
| if No (Isc) then |
| return; |
| end if; |
| |
| -- Note: we do not have to worry about validity chekcing of the for loop |
| -- range bounds here, since they were frozen with constant declarations |
| -- and it is during that process that the validity checking is done. |
| |
| -- Handle the case where we have a for loop with the range type being an |
| -- enumeration type with non-standard representation. In this case we |
| -- expand: |
| |
| -- for x in [reverse] a .. b loop |
| -- ... |
| -- end loop; |
| |
| -- to |
| |
| -- for xP in [reverse] integer |
| -- range etype'Pos (a) .. etype'Pos (b) loop |
| -- declare |
| -- x : constant etype := Pos_To_Rep (xP); |
| -- begin |
| -- ... |
| -- end; |
| -- end loop; |
| |
| if Present (Loop_Parameter_Specification (Isc)) then |
| declare |
| LPS : constant Node_Id := Loop_Parameter_Specification (Isc); |
| Loop_Id : constant Entity_Id := Defining_Identifier (LPS); |
| Ltype : constant Entity_Id := Etype (Loop_Id); |
| Btype : constant Entity_Id := Base_Type (Ltype); |
| Expr : Node_Id; |
| New_Id : Entity_Id; |
| |
| begin |
| if not Is_Enumeration_Type (Btype) |
| or else No (Enum_Pos_To_Rep (Btype)) |
| then |
| return; |
| end if; |
| |
| New_Id := |
| Make_Defining_Identifier (Loc, |
| Chars => New_External_Name (Chars (Loop_Id), 'P')); |
| |
| -- If the type has a contiguous representation, successive values |
| -- can be generated as offsets from the first literal. |
| |
| if Has_Contiguous_Rep (Btype) then |
| Expr := |
| Unchecked_Convert_To (Btype, |
| Make_Op_Add (Loc, |
| Left_Opnd => |
| Make_Integer_Literal (Loc, |
| Enumeration_Rep (First_Literal (Btype))), |
| Right_Opnd => New_Reference_To (New_Id, Loc))); |
| else |
| -- Use the constructed array Enum_Pos_To_Rep |
| |
| Expr := |
| Make_Indexed_Component (Loc, |
| Prefix => New_Reference_To (Enum_Pos_To_Rep (Btype), Loc), |
| Expressions => New_List (New_Reference_To (New_Id, Loc))); |
| end if; |
| |
| Rewrite (N, |
| Make_Loop_Statement (Loc, |
| Identifier => Identifier (N), |
| |
| Iteration_Scheme => |
| Make_Iteration_Scheme (Loc, |
| Loop_Parameter_Specification => |
| Make_Loop_Parameter_Specification (Loc, |
| Defining_Identifier => New_Id, |
| Reverse_Present => Reverse_Present (LPS), |
| |
| Discrete_Subtype_Definition => |
| Make_Subtype_Indication (Loc, |
| |
| Subtype_Mark => |
| New_Reference_To (Standard_Natural, Loc), |
| |
| Constraint => |
| Make_Range_Constraint (Loc, |
| Range_Expression => |
| Make_Range (Loc, |
| |
| Low_Bound => |
| Make_Attribute_Reference (Loc, |
| Prefix => |
| New_Reference_To (Btype, Loc), |
| |
| Attribute_Name => Name_Pos, |
| |
| Expressions => New_List ( |
| Relocate_Node |
| (Type_Low_Bound (Ltype)))), |
| |
| High_Bound => |
| Make_Attribute_Reference (Loc, |
| Prefix => |
| New_Reference_To (Btype, Loc), |
| |
| Attribute_Name => Name_Pos, |
| |
| Expressions => New_List ( |
| Relocate_Node |
| (Type_High_Bound (Ltype))))))))), |
| |
| Statements => New_List ( |
| Make_Block_Statement (Loc, |
| Declarations => New_List ( |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Loop_Id, |
| Constant_Present => True, |
| Object_Definition => New_Reference_To (Ltype, Loc), |
| Expression => Expr)), |
| |
| Handled_Statement_Sequence => |
| Make_Handled_Sequence_Of_Statements (Loc, |
| Statements => Statements (N)))), |
| |
| End_Label => End_Label (N))); |
| Analyze (N); |
| end; |
| |
| -- Second case, if we have a while loop with Condition_Actions set, then |
| -- we change it into a plain loop: |
| |
| -- while C loop |
| -- ... |
| -- end loop; |
| |
| -- changed to: |
| |
| -- loop |
| -- <<condition actions>> |
| -- exit when not C; |
| -- ... |
| -- end loop |
| |
| elsif Present (Isc) |
| and then Present (Condition_Actions (Isc)) |
| then |
| declare |
| ES : Node_Id; |
| |
| begin |
| ES := |
| Make_Exit_Statement (Sloc (Condition (Isc)), |
| Condition => |
| Make_Op_Not (Sloc (Condition (Isc)), |
| Right_Opnd => Condition (Isc))); |
| |
| Prepend (ES, Statements (N)); |
| Insert_List_Before (ES, Condition_Actions (Isc)); |
| |
| -- This is not an implicit loop, since it is generated in response |
| -- to the loop statement being processed. If this is itself |
| -- implicit, the restriction has already been checked. If not, |
| -- it is an explicit loop. |
| |
| Rewrite (N, |
| Make_Loop_Statement (Sloc (N), |
| Identifier => Identifier (N), |
| Statements => Statements (N), |
| End_Label => End_Label (N))); |
| |
| Analyze (N); |
| end; |
| end if; |
| end Expand_N_Loop_Statement; |
| |
| -------------------------------------- |
| -- Expand_N_Simple_Return_Statement -- |
| -------------------------------------- |
| |
| procedure Expand_N_Simple_Return_Statement (N : Node_Id) is |
| begin |
| -- Distinguish the function and non-function cases: |
| |
| case Ekind (Return_Applies_To (Return_Statement_Entity (N))) is |
| |
| when E_Function | |
| E_Generic_Function => |
| Expand_Simple_Function_Return (N); |
| |
| when E_Procedure | |
| E_Generic_Procedure | |
| E_Entry | |
| E_Entry_Family | |
| E_Return_Statement => |
| Expand_Non_Function_Return (N); |
| |
| when others => |
| raise Program_Error; |
| end case; |
| |
| exception |
| when RE_Not_Available => |
| return; |
| end Expand_N_Simple_Return_Statement; |
| |
| -------------------------------- |
| -- Expand_Non_Function_Return -- |
| -------------------------------- |
| |
| procedure Expand_Non_Function_Return (N : Node_Id) is |
| pragma Assert (No (Expression (N))); |
| |
| Loc : constant Source_Ptr := Sloc (N); |
| Scope_Id : Entity_Id := |
| Return_Applies_To (Return_Statement_Entity (N)); |
| Kind : constant Entity_Kind := Ekind (Scope_Id); |
| Call : Node_Id; |
| Acc_Stat : Node_Id; |
| Goto_Stat : Node_Id; |
| Lab_Node : Node_Id; |
| |
| begin |
| -- If it is a return from a procedure do no extra steps |
| |
| if Kind = E_Procedure or else Kind = E_Generic_Procedure then |
| return; |
| |
| -- If it is a nested return within an extended one, replace it with a |
| -- return of the previously declared return object. |
| |
| elsif Kind = E_Return_Statement then |
| Rewrite (N, |
| Make_Simple_Return_Statement (Loc, |
| Expression => |
| New_Occurrence_Of (First_Entity (Scope_Id), Loc))); |
| Set_Comes_From_Extended_Return_Statement (N); |
| Set_Return_Statement_Entity (N, Scope_Id); |
| Expand_Simple_Function_Return (N); |
| return; |
| end if; |
| |
| pragma Assert (Is_Entry (Scope_Id)); |
| |
| -- Look at the enclosing block to see whether the return is from an |
| -- accept statement or an entry body. |
| |
| for J in reverse 0 .. Scope_Stack.Last loop |
| Scope_Id := Scope_Stack.Table (J).Entity; |
| exit when Is_Concurrent_Type (Scope_Id); |
| end loop; |
| |
| -- If it is a return from accept statement it is expanded as call to |
| -- RTS Complete_Rendezvous and a goto to the end of the accept body. |
| |
| -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept, |
| -- Expand_N_Accept_Alternative in exp_ch9.adb) |
| |
| if Is_Task_Type (Scope_Id) then |
| |
| Call := |
| Make_Procedure_Call_Statement (Loc, |
| Name => New_Reference_To |
| (RTE (RE_Complete_Rendezvous), Loc)); |
| Insert_Before (N, Call); |
| -- why not insert actions here??? |
| Analyze (Call); |
| |
| Acc_Stat := Parent (N); |
| while Nkind (Acc_Stat) /= N_Accept_Statement loop |
| Acc_Stat := Parent (Acc_Stat); |
| end loop; |
| |
| Lab_Node := Last (Statements |
| (Handled_Statement_Sequence (Acc_Stat))); |
| |
| Goto_Stat := Make_Goto_Statement (Loc, |
| Name => New_Occurrence_Of |
| (Entity (Identifier (Lab_Node)), Loc)); |
| |
| Set_Analyzed (Goto_Stat); |
| |
| Rewrite (N, Goto_Stat); |
| Analyze (N); |
| |
| -- If it is a return from an entry body, put a Complete_Entry_Body call |
| -- in front of the return. |
| |
| elsif Is_Protected_Type (Scope_Id) then |
| Call := |
| Make_Procedure_Call_Statement (Loc, |
| Name => New_Reference_To |
| (RTE (RE_Complete_Entry_Body), Loc), |
| Parameter_Associations => New_List |
| (Make_Attribute_Reference (Loc, |
| Prefix => |
| New_Reference_To |
| (Object_Ref |
| (Corresponding_Body (Parent (Scope_Id))), |
| Loc), |
| Attribute_Name => Name_Unchecked_Access))); |
| |
| Insert_Before (N, Call); |
| Analyze (Call); |
| end if; |
| end Expand_Non_Function_Return; |
| |
| ----------------------------------- |
| -- Expand_Simple_Function_Return -- |
| ----------------------------------- |
| |
| -- The "simple" comes from the syntax rule simple_return_statement. |
| -- The semantics are not at all simple! |
| |
| procedure Expand_Simple_Function_Return (N : Node_Id) is |
| Loc : constant Source_Ptr := Sloc (N); |
| |
| Scope_Id : constant Entity_Id := |
| Return_Applies_To (Return_Statement_Entity (N)); |
| -- The function we are returning from |
| |
| R_Type : constant Entity_Id := Etype (Scope_Id); |
| -- The result type of the function |
| |
| Utyp : constant Entity_Id := Underlying_Type (R_Type); |
| |
| Exp : constant Node_Id := Expression (N); |
| pragma Assert (Present (Exp)); |
| |
| Exptyp : constant Entity_Id := Etype (Exp); |
| -- The type of the expression (not necessarily the same as R_Type) |
| |
| begin |
| -- We rewrite "return <expression>;" to be: |
| |
| -- return _anon_ : <return_subtype> := <expression> |
| |
| -- The expansion produced by Expand_N_Extended_Return_Statement will |
| -- contain simple return statements (for example, a block containing |
| -- simple return of the return object), which brings us back here with |
| -- Comes_From_Extended_Return_Statement set. To avoid infinite |
| -- recursion, we do not transform into an extended return if |
| -- Comes_From_Extended_Return_Statement is True. |
| |
| -- The reason for this design is that for Ada 2005 limited returns, we |
| -- need to reify the return object, so we can build it "in place", and |
| -- we need a block statement to hang finalization and tasking stuff. |
| |
| -- ??? In order to avoid disruption, we avoid translating to extended |
| -- return except in the cases where we really need to (Ada 2005 |
| -- inherently limited). We would prefer eventually to do this |
| -- translation in all cases except perhaps for the case of Ada 95 |
| -- inherently limited, in order to fully exercise the code in |
| -- Expand_N_Extended_Return_Statement, and in order to do |
| -- build-in-place for efficiency when it is not required. |
| |
| -- As before, we check the type of the return expression rather than the |
| -- return type of the function, because the latter may be a limited |
| -- class-wide interface type, which is not a limited type, even though |
| -- the type of the expression may be. |
| |
| if not Comes_From_Extended_Return_Statement (N) |
| and then Is_Inherently_Limited_Type (Etype (Expression (N))) |
| and then Ada_Version >= Ada_05 -- ??? |
| and then not Debug_Flag_Dot_L |
| then |
| declare |
| Return_Object_Entity : constant Entity_Id := |
| Make_Defining_Identifier (Loc, |
| New_Internal_Name ('R')); |
| |
| Subtype_Ind : constant Node_Id := New_Occurrence_Of (R_Type, Loc); |
| |
| Obj_Decl : constant Node_Id := |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Return_Object_Entity, |
| Object_Definition => Subtype_Ind, |
| Expression => Exp); |
| |
| Ext : constant Node_Id := Make_Extended_Return_Statement (Loc, |
| Return_Object_Declarations => New_List (Obj_Decl)); |
| |
| begin |
| Rewrite (N, Ext); |
| Analyze (N); |
| return; |
| end; |
| end if; |
| |
| -- Here we have a simple return statement that is part of the expansion |
| -- of an extended return statement (either written by the user, or |
| -- generated by the above code). |
| |
| -- Always normalize C/Fortran boolean result. This is not always needed, |
| -- but it seems a good idea to minimize the passing around of non- |
| -- normalized values, and in any case this handles the processing of |
| -- barrier functions for protected types, which turn the condition into |
| -- a return statement. |
| |
| if Is_Boolean_Type (Exptyp) |
| and then Nonzero_Is_True (Exptyp) |
| then |
| Adjust_Condition (Exp); |
| Adjust_Result_Type (Exp, Exptyp); |
| end if; |
| |
| -- Do validity check if enabled for returns |
| |
| if Validity_Checks_On |
| and then Validity_Check_Returns |
| then |
| Ensure_Valid (Exp); |
| end if; |
| |
| -- Check the result expression of a scalar function against the subtype |
| -- of the function by inserting a conversion. This conversion must |
| -- eventually be performed for other classes of types, but for now it's |
| -- only done for scalars. |
| -- ??? |
| |
| if Is_Scalar_Type (Exptyp) then |
| Rewrite (Exp, Convert_To (R_Type, Exp)); |
| Analyze (Exp); |
| end if; |
| |
| -- Deal with returning variable length objects and controlled types |
| |
| -- Nothing to do if we are returning by reference, or this is not a |
| -- type that requires special processing (indicated by the fact that |
| -- it requires a cleanup scope for the secondary stack case). |
| |
| if Is_Inherently_Limited_Type (Exptyp) |
| or else Is_Limited_Interface (Exptyp) |
| then |
| null; |
| |
| elsif not Requires_Transient_Scope (R_Type) then |
| |
| -- Mutable records with no variable length components are not |
| -- returned on the sec-stack, so we need to make sure that the |
| -- backend will only copy back the size of the actual value, and not |
| -- the maximum size. We create an actual subtype for this purpose. |
| |
| declare |
| Ubt : constant Entity_Id := Underlying_Type (Base_Type (Exptyp)); |
| Decl : Node_Id; |
| Ent : Entity_Id; |
| begin |
| if Has_Discriminants (Ubt) |
| and then not Is_Constrained (Ubt) |
| and then not Has_Unchecked_Union (Ubt) |
| then |
| Decl := Build_Actual_Subtype (Ubt, Exp); |
| Ent := Defining_Identifier (Decl); |
| Insert_Action (Exp, Decl); |
| Rewrite (Exp, Unchecked_Convert_To (Ent, Exp)); |
| Analyze_And_Resolve (Exp); |
| end if; |
| end; |
| |
| -- Here if secondary stack is used |
| |
| else |
| -- Make sure that no surrounding block will reclaim the secondary |
| -- stack on which we are going to put the result. Not only may this |
| -- introduce secondary stack leaks but worse, if the reclamation is |
| -- done too early, then the result we are returning may get |
| -- clobbered. |
| |
| declare |
| S : Entity_Id; |
| begin |
| S := Current_Scope; |
| while Ekind (S) = E_Block or else Ekind (S) = E_Loop loop |
| Set_Sec_Stack_Needed_For_Return (S, True); |
| S := Enclosing_Dynamic_Scope (S); |
| end loop; |
| end; |
| |
| -- Optimize the case where the result is a function call. In this |
| -- case either the result is already on the secondary stack, or is |
| -- already being returned with the stack pointer depressed and no |
| -- further processing is required except to set the By_Ref flag to |
| -- ensure that gigi does not attempt an extra unnecessary copy. |
| -- (actually not just unnecessary but harmfully wrong in the case |
| -- of a controlled type, where gigi does not know how to do a copy). |
| -- To make up for a gcc 2.8.1 deficiency (???), we perform |
| -- the copy for array types if the constrained status of the |
| -- target type is different from that of the expression. |
| |
| if Requires_Transient_Scope (Exptyp) |
| and then |
| (not Is_Array_Type (Exptyp) |
| or else Is_Constrained (Exptyp) = Is_Constrained (R_Type) |
| or else CW_Or_Controlled_Type (Utyp)) |
| and then Nkind (Exp) = N_Function_Call |
| then |
| Set_By_Ref (N); |
| |
| -- Remove side effects from the expression now so that other parts |
| -- of the expander do not have to reanalyze this node without this |
| -- optimization |
| |
| Rewrite (Exp, Duplicate_Subexpr_No_Checks (Exp)); |
| |
| -- For controlled types, do the allocation on the secondary stack |
| -- manually in order to call adjust at the right time: |
| |
| -- type Anon1 is access R_Type; |
| -- for Anon1'Storage_pool use ss_pool; |
| -- Anon2 : anon1 := new R_Type'(expr); |
| -- return Anon2.all; |
| |
| -- We do the same for classwide types that are not potentially |
| -- controlled (by the virtue of restriction No_Finalization) because |
| -- gigi is not able to properly allocate class-wide types. |
| |
| elsif CW_Or_Controlled_Type (Utyp) then |
| declare |
| Loc : constant Source_Ptr := Sloc (N); |
| Temp : constant Entity_Id := |
| Make_Defining_Identifier (Loc, |
| Chars => New_Internal_Name ('R')); |
| Acc_Typ : constant Entity_Id := |
| Make_Defining_Identifier (Loc, |
| Chars => New_Internal_Name ('A')); |
| Alloc_Node : Node_Id; |
| |
| begin |
| Set_Ekind (Acc_Typ, E_Access_Type); |
| |
| Set_Associated_Storage_Pool (Acc_Typ, RTE (RE_SS_Pool)); |
| |
| Alloc_Node := |
| Make_Allocator (Loc, |
| Expression => |
| Make_Qualified_Expression (Loc, |
| Subtype_Mark => New_Reference_To (Etype (Exp), Loc), |
| Expression => Relocate_Node (Exp))); |
| |
| Insert_List_Before_And_Analyze (N, New_List ( |
| Make_Full_Type_Declaration (Loc, |
| Defining_Identifier => Acc_Typ, |
| Type_Definition => |
| Make_Access_To_Object_Definition (Loc, |
| Subtype_Indication => |
| New_Reference_To (R_Type, Loc))), |
| |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Temp, |
| Object_Definition => New_Reference_To (Acc_Typ, Loc), |
| Expression => Alloc_Node))); |
| |
| Rewrite (Exp, |
| Make_Explicit_Dereference (Loc, |
| Prefix => New_Reference_To (Temp, Loc))); |
| |
| Analyze_And_Resolve (Exp, R_Type); |
| end; |
| |
| -- Otherwise use the gigi mechanism to allocate result on the |
| -- secondary stack. |
| |
| else |
| Set_Storage_Pool (N, RTE (RE_SS_Pool)); |
| |
| -- If we are generating code for the VM do not use |
| -- SS_Allocate since everything is heap-allocated anyway. |
| |
| if VM_Target = No_VM then |
| Set_Procedure_To_Call (N, RTE (RE_SS_Allocate)); |
| end if; |
| end if; |
| end if; |
| |
| -- Implement the rules of 6.5(8-10), which require a tag check in the |
| -- case of a limited tagged return type, and tag reassignment for |
| -- nonlimited tagged results. These actions are needed when the return |
| -- type is a specific tagged type and the result expression is a |
| -- conversion or a formal parameter, because in that case the tag of the |
| -- expression might differ from the tag of the specific result type. |
| |
| if Is_Tagged_Type (Utyp) |
| and then not Is_Class_Wide_Type (Utyp) |
| and then (Nkind_In (Exp, N_Type_Conversion, |
| N_Unchecked_Type_Conversion) |
| or else (Is_Entity_Name (Exp) |
| and then Ekind (Entity (Exp)) in Formal_Kind)) |
| then |
| -- When the return type is limited, perform a check that the |
| -- tag of the result is the same as the tag of the return type. |
| |
| if Is_Limited_Type (R_Type) then |
| Insert_Action (Exp, |
| Make_Raise_Constraint_Error (Loc, |
| Condition => |
| Make_Op_Ne (Loc, |
| Left_Opnd => |
| Make_Selected_Component (Loc, |
| Prefix => Duplicate_Subexpr (Exp), |
| Selector_Name => |
| New_Reference_To (First_Tag_Component (Utyp), Loc)), |
| Right_Opnd => |
| Unchecked_Convert_To (RTE (RE_Tag), |
| New_Reference_To |
| (Node (First_Elmt |
| (Access_Disp_Table (Base_Type (Utyp)))), |
| Loc))), |
| Reason => CE_Tag_Check_Failed)); |
| |
| -- If the result type is a specific nonlimited tagged type, then we |
| -- have to ensure that the tag of the result is that of the result |
| -- type. This is handled by making a copy of the expression in the |
| -- case where it might have a different tag, namely when the |
| -- expression is a conversion or a formal parameter. We create a new |
| -- object of the result type and initialize it from the expression, |
| -- which will implicitly force the tag to be set appropriately. |
| |
| else |
| declare |
| Result_Id : constant Entity_Id := |
| Make_Defining_Identifier (Loc, |
| Chars => New_Internal_Name ('R')); |
| Result_Exp : constant Node_Id := |
| New_Reference_To (Result_Id, Loc); |
| Result_Obj : constant Node_Id := |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Result_Id, |
| Object_Definition => |
| New_Reference_To (R_Type, Loc), |
| Constant_Present => True, |
| Expression => Relocate_Node (Exp)); |
| |
| begin |
| Set_Assignment_OK (Result_Obj); |
| Insert_Action (Exp, Result_Obj); |
| |
| Rewrite (Exp, Result_Exp); |
| Analyze_And_Resolve (Exp, R_Type); |
| end; |
| end if; |
| |
| -- Ada 2005 (AI-344): If the result type is class-wide, then insert |
| -- a check that the level of the return expression's underlying type |
| -- is not deeper than the level of the master enclosing the function. |
| -- Always generate the check when the type of the return expression |
| -- is class-wide, when it's a type conversion, or when it's a formal |
| -- parameter. Otherwise, suppress the check in the case where the |
| -- return expression has a specific type whose level is known not to |
| -- be statically deeper than the function's result type. |
| |
| -- Note: accessibility check is skipped in the VM case, since there |
| -- does not seem to be any practical way to implement this check. |
| |
| elsif Ada_Version >= Ada_05 |
| and then VM_Target = No_VM |
| and then Is_Class_Wide_Type (R_Type) |
| and then not Scope_Suppress (Accessibility_Check) |
| and then |
| (Is_Class_Wide_Type (Etype (Exp)) |
| or else Nkind_In (Exp, N_Type_Conversion, |
| N_Unchecked_Type_Conversion) |
| or else (Is_Entity_Name (Exp) |
| and then Ekind (Entity (Exp)) in Formal_Kind) |
| or else Scope_Depth (Enclosing_Dynamic_Scope (Etype (Exp))) > |
| Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id))) |
| then |
| declare |
| Tag_Node : Node_Id; |
| |
| begin |
| -- Ada 2005 (AI-251): In class-wide interface objects we displace |
| -- "this" to reference the base of the object --- required to get |
| -- access to the TSD of the object. |
| |
| if Is_Class_Wide_Type (Etype (Exp)) |
| and then Is_Interface (Etype (Exp)) |
| and then Nkind (Exp) = N_Explicit_Dereference |
| then |
| Tag_Node := |
| Make_Explicit_Dereference (Loc, |
| Unchecked_Convert_To (RTE (RE_Tag_Ptr), |
| Make_Function_Call (Loc, |
| Name => New_Reference_To (RTE (RE_Base_Address), Loc), |
| Parameter_Associations => New_List ( |
| Unchecked_Convert_To (RTE (RE_Address), |
| Duplicate_Subexpr (Prefix (Exp))))))); |
| else |
| Tag_Node := |
| Make_Attribute_Reference (Loc, |
| Prefix => Duplicate_Subexpr (Exp), |
| Attribute_Name => Name_Tag); |
| end if; |
| |
| Insert_Action (Exp, |
| Make_Raise_Program_Error (Loc, |
| Condition => |
| Make_Op_Gt (Loc, |
| Left_Opnd => |
| Build_Get_Access_Level (Loc, Tag_Node), |
| Right_Opnd => |
| Make_Integer_Literal (Loc, |
| Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))), |
| Reason => PE_Accessibility_Check_Failed)); |
| end; |
| end if; |
| end Expand_Simple_Function_Return; |
| |
| ------------------------------ |
| -- Make_Tag_Ctrl_Assignment -- |
| ------------------------------ |
| |
| function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is |
| Loc : constant Source_Ptr := Sloc (N); |
| L : constant Node_Id := Name (N); |
| T : constant Entity_Id := Underlying_Type (Etype (L)); |
| |
| Ctrl_Act : constant Boolean := Controlled_Type (T) |
| and then not No_Ctrl_Actions (N); |
| |
| Save_Tag : constant Boolean := Is_Tagged_Type (T) |
| and then not No_Ctrl_Actions (N) |
| and then VM_Target = No_VM; |
| -- Tags are not saved and restored when VM_Target because VM tags are |
| -- represented implicitly in objects. |
| |
| Res : List_Id; |
| Tag_Tmp : Entity_Id; |
| |
| Prev_Tmp : Entity_Id; |
| Next_Tmp : Entity_Id; |
| Ctrl_Ref : Node_Id; |
| |
| begin |
| Res := New_List; |
| |
| -- Finalize the target of the assignment when controlled. |
| -- We have two exceptions here: |
| |
| -- 1. If we are in an init proc since it is an initialization |
| -- more than an assignment |
| |
| -- 2. If the left-hand side is a temporary that was not initialized |
| -- (or the parent part of a temporary since it is the case in |
| -- extension aggregates). Such a temporary does not come from |
| -- source. We must examine the original node for the prefix, because |
| -- it may be a component of an entry formal, in which case it has |
| -- been rewritten and does not appear to come from source either. |
| |
| -- Case of init proc |
| |
| if not Ctrl_Act then |
| null; |
| |
| -- The left hand side is an uninitialized temporary |
| |
| elsif Nkind (L) = N_Type_Conversion |
| and then Is_Entity_Name (Expression (L)) |
| and then No_Initialization (Parent (Entity (Expression (L)))) |
| then |
| null; |
| else |
| Append_List_To (Res, |
| Make_Final_Call ( |
| Ref => Duplicate_Subexpr_No_Checks (L), |
| Typ => Etype (L), |
| With_Detach => New_Reference_To (Standard_False, Loc))); |
| end if; |
| |
| -- Save the Tag in a local variable Tag_Tmp |
| |
| if Save_Tag then |
| Tag_Tmp := |
| Make_Defining_Identifier (Loc, New_Internal_Name ('A')); |
| |
| Append_To (Res, |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Tag_Tmp, |
| Object_Definition => New_Reference_To (RTE (RE_Tag), Loc), |
| Expression => |
| Make_Selected_Component (Loc, |
| Prefix => Duplicate_Subexpr_No_Checks (L), |
| Selector_Name => New_Reference_To (First_Tag_Component (T), |
| Loc)))); |
| |
| -- Otherwise Tag_Tmp not used |
| |
| else |
| Tag_Tmp := Empty; |
| end if; |
| |
| if Ctrl_Act then |
| if VM_Target /= No_VM then |
| |
| -- Cannot assign part of the object in a VM context, so instead |
| -- fallback to the previous mechanism, even though it is not |
| -- completely correct ??? |
| |
| -- Save the Finalization Pointers in local variables Prev_Tmp and |
| -- Next_Tmp. For objects with Has_Controlled_Component set, these |
| -- pointers are in the Record_Controller |
| |
| Ctrl_Ref := Duplicate_Subexpr (L); |
| |
| if Has_Controlled_Component (T) then |
| Ctrl_Ref := |
| Make_Selected_Component (Loc, |
| Prefix => Ctrl_Ref, |
| Selector_Name => |
| New_Reference_To (Controller_Component (T), Loc)); |
| end if; |
| |
| Prev_Tmp := |
| Make_Defining_Identifier (Loc, New_Internal_Name ('B')); |
| |
| Append_To (Res, |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Prev_Tmp, |
| |
| Object_Definition => |
| New_Reference_To (RTE (RE_Finalizable_Ptr), Loc), |
| |
| Expression => |
| Make_Selected_Component (Loc, |
| Prefix => |
| Unchecked_Convert_To (RTE (RE_Finalizable), Ctrl_Ref), |
| Selector_Name => Make_Identifier (Loc, Name_Prev)))); |
| |
| Next_Tmp := |
| Make_Defining_Identifier (Loc, |
| Chars => New_Internal_Name ('C')); |
| |
| Append_To (Res, |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Next_Tmp, |
| |
| Object_Definition => |
| New_Reference_To (RTE (RE_Finalizable_Ptr), Loc), |
| |
| Expression => |
| Make_Selected_Component (Loc, |
| Prefix => |
| Unchecked_Convert_To (RTE (RE_Finalizable), |
| New_Copy_Tree (Ctrl_Ref)), |
| Selector_Name => Make_Identifier (Loc, Name_Next)))); |
| |
| -- Do the Assignment |
| |
| Append_To (Res, Relocate_Node (N)); |
| |
| else |
| -- Regular (non VM) processing for controlled types and types with |
| -- controlled components |
| |
| -- Variables of such types contain pointers used to chain them in |
| -- finalization lists, in addition to user data. These pointers |
| -- are specific to each object of the type, not to the value being |
| -- assigned. |
| |
| -- Thus they need to be left intact during the assignment. We |
| -- achieve this by constructing a Storage_Array subtype, and by |
| -- overlaying objects of this type on the source and target of the |
| -- assignment. The assignment is then rewritten to assignments of |
| -- slices of these arrays, copying the user data, and leaving the |
| -- pointers untouched. |
| |
| Controlled_Actions : declare |
| Prev_Ref : Node_Id; |
| -- A reference to the Prev component of the record controller |
| |
| First_After_Root : Node_Id := Empty; |
| -- Index of first byte to be copied (used to skip |
| -- Root_Controlled in controlled objects). |
| |
| Last_Before_Hole : Node_Id := Empty; |
| -- Index of last byte to be copied before outermost record |
| -- controller data. |
| |
| Hole_Length : Node_Id := Empty; |
| -- Length of record controller data (Prev and Next pointers) |
| |
| First_After_Hole : Node_Id := Empty; |
| -- Index of first byte to be copied after outermost record |
| -- controller data. |
| |
| Expr, Source_Size : Node_Id; |
| Source_Actual_Subtype : Entity_Id; |
| -- Used for computation of the size of the data to be copied |
| |
| Range_Type : Entity_Id; |
| Opaque_Type : Entity_Id; |
| |
| function Build_Slice |
| (Rec : Entity_Id; |
| Lo : Node_Id; |
| Hi : Node_Id) return Node_Id; |
| -- Build and return a slice of an array of type S overlaid on |
| -- object Rec, with bounds specified by Lo and Hi. If either |
| -- bound is empty, a default of S'First (respectively S'Last) |
| -- is used. |
| |
| ----------------- |
| -- Build_Slice -- |
| ----------------- |
| |
| function Build_Slice |
| (Rec : Node_Id; |
| Lo : Node_Id; |
| Hi : Node_Id) return Node_Id |
| is |
| Lo_Bound : Node_Id; |
| Hi_Bound : Node_Id; |
| |
| Opaque : constant Node_Id := |
| Unchecked_Convert_To (Opaque_Type, |
| Make_Attribute_Reference (Loc, |
| Prefix => Rec, |
| Attribute_Name => Name_Address)); |
| -- Access value designating an opaque storage array of type |
| -- S overlaid on record Rec. |
| |
| begin |
| -- Compute slice bounds using S'First (1) and S'Last as |
| -- default values when not specified by the caller. |
| |
| if No (Lo) then |
| Lo_Bound := Make_Integer_Literal (Loc, 1); |
| else |
| Lo_Bound := Lo; |
| end if; |
| |
| if No (Hi) then |
| Hi_Bound := Make_Attribute_Reference (Loc, |
| Prefix => New_Occurrence_Of (Range_Type, Loc), |
| Attribute_Name => Name_Last); |
| else |
| Hi_Bound := Hi; |
| end if; |
| |
| return Make_Slice (Loc, |
| Prefix => |
| Opaque, |
| Discrete_Range => Make_Range (Loc, |
| Lo_Bound, Hi_Bound)); |
| end Build_Slice; |
| |
| -- Start of processing for Controlled_Actions |
| |
| begin |
| -- Create a constrained subtype of Storage_Array whose size |
| -- corresponds to the value being assigned. |
| |
| -- subtype G is Storage_Offset range |
| -- 1 .. (Expr'Size + Storage_Unit - 1) / Storage_Unit |
| |
| Expr := Duplicate_Subexpr_No_Checks (Expression (N)); |
| |
| if Nkind (Expr) = N_Qualified_Expression then |
| Expr := Expression (Expr); |
| end if; |
| |
| Source_Actual_Subtype := Etype (Expr); |
| |
| if Has_Discriminants (Source_Actual_Subtype) |
| and then not Is_Constrained (Source_Actual_Subtype) |
| then |
| Append_To (Res, |
| Build_Actual_Subtype (Source_Actual_Subtype, Expr)); |
| Source_Actual_Subtype := Defining_Identifier (Last (Res)); |
| end if; |
| |
| Source_Size := |
| Make_Op_Add (Loc, |
| Left_Opnd => |
| Make_Attribute_Reference (Loc, |
| Prefix => |
| New_Occurrence_Of (Source_Actual_Subtype, Loc), |
| Attribute_Name => Name_Size), |
| Right_Opnd => |
| Make_Integer_Literal (Loc, |
| Intval => System_Storage_Unit - 1)); |
| |
| Source_Size := |
| Make_Op_Divide (Loc, |
| Left_Opnd => Source_Size, |
| Right_Opnd => |
| Make_Integer_Literal (Loc, |
| Intval => System_Storage_Unit)); |
| |
| Range_Type := |
| Make_Defining_Identifier (Loc, |
| New_Internal_Name ('G')); |
| |
| Append_To (Res, |
| Make_Subtype_Declaration (Loc, |
| Defining_Identifier => Range_Type, |
| Subtype_Indication => |
| Make_Subtype_Indication (Loc, |
| Subtype_Mark => |
| New_Reference_To (RTE (RE_Storage_Offset), Loc), |
| Constraint => Make_Range_Constraint (Loc, |
| Range_Expression => |
| Make_Range (Loc, |
| Low_Bound => Make_Integer_Literal (Loc, 1), |
| High_Bound => Source_Size))))); |
| |
| -- subtype S is Storage_Array (G) |
| |
| Append_To (Res, |
| Make_Subtype_Declaration (Loc, |
| Defining_Identifier => |
| Make_Defining_Identifier (Loc, |
| New_Internal_Name ('S')), |
| Subtype_Indication => |
| Make_Subtype_Indication (Loc, |
| Subtype_Mark => |
| New_Reference_To (RTE (RE_Storage_Array), Loc), |
| Constraint => |
| Make_Index_Or_Discriminant_Constraint (Loc, |
| Constraints => |
| New_List (New_Reference_To (Range_Type, Loc)))))); |
| |
| -- type A is access S |
| |
| Opaque_Type := |
| Make_Defining_Identifier (Loc, |
| Chars => New_Internal_Name ('A')); |
| |
| Append_To (Res, |
| Make_Full_Type_Declaration (Loc, |
| Defining_Identifier => Opaque_Type, |
| Type_Definition => |
| Make_Access_To_Object_Definition (Loc, |
| Subtype_Indication => |
| New_Occurrence_Of ( |
| Defining_Identifier (Last (Res)), Loc)))); |
| |
| -- Generate appropriate slice assignments |
| |
| First_After_Root := Make_Integer_Literal (Loc, 1); |
| |
| -- For the case of a controlled object, skip the |
| -- Root_Controlled part. |
| |
| if Is_Controlled (T) then |
| First_After_Root := |
| Make_Op_Add (Loc, |
| First_After_Root, |
| Make_Op_Divide (Loc, |
| Make_Attribute_Reference (Loc, |
| Prefix => |
| New_Occurrence_Of (RTE (RE_Root_Controlled), Loc), |
| Attribute_Name => Name_Size), |
| Make_Integer_Literal (Loc, System_Storage_Unit))); |
| end if; |
| |
| -- For the case of a record with controlled components, skip |
| -- the Prev and Next components of the record controller. |
| -- These components constitute a 'hole' in the middle of the |
| -- data to be copied. |
| |
| if Has_Controlled_Component (T) then |
| Prev_Ref := |
| Make_Selected_Component (Loc, |
| Prefix => |
| Make_Selected_Component (Loc, |
| Prefix => Duplicate_Subexpr_No_Checks (L), |
| Selector_Name => |
| New_Reference_To (Controller_Component (T), Loc)), |
| Selector_Name => Make_Identifier (Loc, Name_Prev)); |
| |
| -- Last index before hole: determined by position of |
| -- the _Controller.Prev component. |
| |
| Last_Before_Hole := |
| Make_Defining_Identifier (Loc, |
| New_Internal_Name ('L')); |
| |
| Append_To (Res, |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Last_Before_Hole, |
| Object_Definition => New_Occurrence_Of ( |
| RTE (RE_Storage_Offset), Loc), |
| Constant_Present => True, |
| Expression => Make_Op_Add (Loc, |
| Make_Attribute_Reference (Loc, |
| Prefix => Prev_Ref, |
| Attribute_Name => Name_Position), |
| Make_Attribute_Reference (Loc, |
| Prefix => New_Copy_Tree (Prefix (Prev_Ref)), |
| Attribute_Name => Name_Position)))); |
| |
| -- Hole length: size of the Prev and Next components |
| |
| Hole_Length := |
| Make_Op_Multiply (Loc, |
| Left_Opnd => Make_Integer_Literal (Loc, Uint_2), |
| Right_Opnd => |
| Make_Op_Divide (Loc, |
| Left_Opnd => |
| Make_Attribute_Reference (Loc, |
| Prefix => New_Copy_Tree (Prev_Ref), |
| Attribute_Name => Name_Size), |
| Right_Opnd => |
| Make_Integer_Literal (Loc, |
| Intval => System_Storage_Unit))); |
| |
| -- First index after hole |
| |
| First_After_Hole := |
| Make_Defining_Identifier (Loc, |
| New_Internal_Name ('F')); |
| |
| Append_To (Res, |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => First_After_Hole, |
| Object_Definition => New_Occurrence_Of ( |
| RTE (RE_Storage_Offset), Loc), |
| Constant_Present => True, |
| Expression => |
| Make_Op_Add (Loc, |
| Left_Opnd => |
| Make_Op_Add (Loc, |
| Left_Opnd => |
| New_Occurrence_Of (Last_Before_Hole, Loc), |
| Right_Opnd => Hole_Length), |
| Right_Opnd => Make_Integer_Literal (Loc, 1)))); |
| |
| Last_Before_Hole := |
| New_Occurrence_Of (Last_Before_Hole, Loc); |
| First_After_Hole := |
| New_Occurrence_Of (First_After_Hole, Loc); |
| end if; |
| |
| -- Assign the first slice (possibly skipping Root_Controlled, |
| -- up to the beginning of the record controller if present, |
| -- up to the end of the object if not). |
| |
| Append_To (Res, Make_Assignment_Statement (Loc, |
| Name => Build_Slice ( |
| Rec => Duplicate_Subexpr_No_Checks (L), |
| Lo => First_After_Root, |
| Hi => Last_Before_Hole), |
| |
| Expression => Build_Slice ( |
| Rec => Expression (N), |
| Lo => First_After_Root, |
| Hi => New_Copy_Tree (Last_Before_Hole)))); |
| |
| if Present (First_After_Hole) then |
| |
| -- If a record controller is present, copy the second slice, |
| -- from right after the _Controller.Next component up to the |
| -- end of the object. |
| |
| Append_To (Res, Make_Assignment_Statement (Loc, |
| Name => Build_Slice ( |
| Rec => Duplicate_Subexpr_No_Checks (L), |
| Lo => First_After_Hole, |
| Hi => Empty), |
| Expression => Build_Slice ( |
| Rec => Duplicate_Subexpr_No_Checks (Expression (N)), |
| Lo => New_Copy_Tree (First_After_Hole), |
| Hi => Empty))); |
| end if; |
| end Controlled_Actions; |
| end if; |
| |
| else |
| Append_To (Res, Relocate_Node (N)); |
| end if; |
| |
| -- Restore the tag |
| |
| if Save_Tag then |
| Append_To (Res, |
| Make_Assignment_Statement (Loc, |
| Name => |
| Make_Selected_Component (Loc, |
| Prefix => Duplicate_Subexpr_No_Checks (L), |
| Selector_Name => New_Reference_To (First_Tag_Component (T), |
| Loc)), |
| Expression => New_Reference_To (Tag_Tmp, Loc))); |
| end if; |
| |
| if Ctrl_Act then |
| if VM_Target /= No_VM then |
| -- Restore the finalization pointers |
| |
| Append_To (Res, |
| Make_Assignment_Statement (Loc, |
| Name => |
| Make_Selected_Component (Loc, |
| Prefix => |
| Unchecked_Convert_To (RTE (RE_Finalizable), |
| New_Copy_Tree (Ctrl_Ref)), |
| Selector_Name => Make_Identifier (Loc, Name_Prev)), |
| Expression => New_Reference_To (Prev_Tmp, Loc))); |
| |
| Append_To (Res, |
| Make_Assignment_Statement (Loc, |
| Name => |
| Make_Selected_Component (Loc, |
| Prefix => |
| Unchecked_Convert_To (RTE (RE_Finalizable), |
| New_Copy_Tree (Ctrl_Ref)), |
| Selector_Name => Make_Identifier (Loc, Name_Next)), |
| Expression => New_Reference_To (Next_Tmp, Loc))); |
| end if; |
| |
| -- Adjust the target after the assignment when controlled (not in the |
| -- init proc since it is an initialization more than an assignment). |
| |
| Append_List_To (Res, |
| Make_Adjust_Call ( |
| Ref => Duplicate_Subexpr_Move_Checks (L), |
| Typ => Etype (L), |
| Flist_Ref => New_Reference_To (RTE (RE_Global_Final_List), Loc), |
| With_Attach => Make_Integer_Literal (Loc, 0))); |
| end if; |
| |
| return Res; |
| |
| exception |
| -- Could use comment here ??? |
| |
| when RE_Not_Available => |
| return Empty_List; |
| end Make_Tag_Ctrl_Assignment; |
| |
| end Exp_Ch5; |