| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT COMPILER COMPONENTS -- |
| -- -- |
| -- E X P _ C H 5 -- |
| -- -- |
| -- B o d y -- |
| -- -- |
| -- Copyright (C) 1992-2006, Free Software Foundation, Inc. -- |
| -- -- |
| -- GNAT is free software; you can redistribute it and/or modify it under -- |
| -- terms of the GNU General Public License as published by the Free Soft- -- |
| -- ware Foundation; either version 2, or (at your option) any later ver- -- |
| -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- |
| -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- |
| -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- |
| -- for more details. You should have received a copy of the GNU General -- |
| -- Public License distributed with GNAT; see file COPYING. If not, write -- |
| -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- |
| -- Boston, MA 02110-1301, USA. -- |
| -- -- |
| -- GNAT was originally developed by the GNAT team at New York University. -- |
| -- Extensive contributions were provided by Ada Core Technologies Inc. -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| with Atree; use Atree; |
| with Checks; use Checks; |
| with Einfo; use Einfo; |
| with Elists; use Elists; |
| with Exp_Aggr; use Exp_Aggr; |
| 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 Hostparm; use Hostparm; |
| 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_Ch5; use Sem_Ch5; |
| 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 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. |
| |
| 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. |
| |
| function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean; |
| -- This function is used in processing the assignment of a record or |
| -- indexed component. The argument N is either the left hand or right |
| -- hand side of an assignment, and this function determines if there |
| -- is a record component reference where the record may be bit aligned |
| -- in a manner that causes trouble for the back end (see description |
| -- of Exp_Util.Component_May_Be_Bit_Aligned for further details). |
| |
| ------------------------------ |
| -- 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. |
| |
| -- LLVM local |
| 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 -- |
| ----------------------- |
| |
| -- LLVM local |
| 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 |
| -- and that is the case where we have a one dimensional array, |
| -- and either both operands are parameters, or one is a parameter |
| -- and the other is a global variable. In this case the parameter |
| -- could be a slice that overlaps with the other parameter. |
| |
| -- Check for the case of slices requiring an explicit loop. Normally |
| -- it is only the explicit slice cases that bother us, but in the |
| -- case of one dimensional arrays, parameters can be slices that |
| -- are passed by reference, so we can have aliasing for assignments |
| -- from one parameter to another, or assignments between parameters |
| -- and nonlocal variables. 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: overlap is never 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 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 JVM. |
| |
| and then not Java_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 : in 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 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 had 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 |
| if Forwards_OK (N) then |
| return; |
| else |
| null; |
| -- Here is where a memmove would be appropriate ??? |
| 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; |
| |
| -- 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 Java VM case, because addresses |
| -- don't work there. |
| |
| if not Is_Bit_Packed_Array (L_Type) and then not Java_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 Java 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 |
| -- 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 (Lhs) = N_Indexed_Component |
| or else |
| Nkind (Lhs) = 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 (Exp) = N_Selected_Component |
| or else |
| Nkind (Exp) = 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 |
| New_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 generate 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 temporay. |
| |
| 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 := |
| Range_Check |
| (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; |
| |
| 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 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 tag of the Target is covered by the tag of the source |
| |
| 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_Not (Loc, |
| Make_Function_Call (Loc, |
| Name => New_Reference_To |
| (RTE (RE_CW_Membership), Loc), |
| Parameter_Associations => New_List ( |
| Make_Selected_Component (Loc, |
| Prefix => |
| Duplicate_Subexpr (Lhs), |
| Selector_Name => |
| Make_Identifier (Loc, Name_uTag)), |
| Make_Selected_Component (Loc, |
| Prefix => |
| Duplicate_Subexpr (Rhs), |
| Selector_Name => |
| Make_Identifier (Loc, 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_Exception_Handler (Loc, |
| Exception_Choices => |
| New_List (Make_Others_Choice (Loc)), |
| Statements => New_List ( |
| Make_Raise_Program_Error (Loc, |
| Reason => |
| PE_Finalize_Raised_Exception) |
| )))))); |
| 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 (Actual_Rhs) = N_Type_Conversion |
| or else |
| Nkind (Actual_Rhs) = 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 |
| Ensure_Valid (Rhs); |
| |
| -- 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 that the Ensure_Valid call is ignored if the |
| -- Validity_Checking mode is set to none so we do not |
| -- need to 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 the 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. 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)); |
| Kill_Dead_Code (Alternatives (N)); |
| 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_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; |
| |
| 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)); |
| Kill_Dead_Code (Else_Statements (N)); |
| |
| 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)); |
| |
| -- 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. |
| |
| Check_Possible_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 we rewrite the if |
| -- statement as indicated above. We also do the same rewrite |
| -- if the condition is True or False. 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_Return_Statement |
| and then |
| Nkind (Else_Stm) = N_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_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_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; |
| |
| if No (Isc) then |
| return; |
| end if; |
| |
| -- 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_Return_Statement -- |
| ------------------------------- |
| |
| procedure Expand_N_Return_Statement (N : Node_Id) is |
| Loc : constant Source_Ptr := Sloc (N); |
| Exp : constant Node_Id := Expression (N); |
| Exptyp : Entity_Id; |
| T : Entity_Id; |
| Utyp : Entity_Id; |
| Scope_Id : Entity_Id; |
| Kind : Entity_Kind; |
| Call : Node_Id; |
| Acc_Stat : Node_Id; |
| Goto_Stat : Node_Id; |
| Lab_Node : Node_Id; |
| Cur_Idx : Nat; |
| Return_Type : Entity_Id; |
| Result_Exp : Node_Id; |
| Result_Id : Entity_Id; |
| Result_Obj : Node_Id; |
| |
| begin |
| -- Case where returned expression is present |
| |
| if Present (Exp) then |
| |
| -- Always normalize C/Fortran boolean result. This is not always |
| -- necessary, 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. |
| |
| Exptyp := Etype (Exp); |
| |
| 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; |
| end if; |
| |
| -- Find relevant enclosing scope from which return is returning |
| |
| Cur_Idx := Scope_Stack.Last; |
| loop |
| Scope_Id := Scope_Stack.Table (Cur_Idx).Entity; |
| |
| if Ekind (Scope_Id) /= E_Block |
| and then Ekind (Scope_Id) /= E_Loop |
| then |
| exit; |
| |
| else |
| Cur_Idx := Cur_Idx - 1; |
| pragma Assert (Cur_Idx >= 0); |
| end if; |
| end loop; |
| |
| if No (Exp) then |
| Kind := Ekind (Scope_Id); |
| |
| -- If it is a return from procedures do no extra steps |
| |
| if Kind = E_Procedure or else Kind = E_Generic_Procedure then |
| 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 .. Cur_Idx 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 should be expanded |
| -- as a 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; |
| |
| return; |
| end if; |
| |
| T := Etype (Exp); |
| Return_Type := Etype (Scope_Id); |
| Utyp := Underlying_Type (Return_Type); |
| |
| -- 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 (T) then |
| Rewrite (Exp, Convert_To (Return_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_Return_By_Reference_Type (T) then |
| null; |
| |
| elsif not Requires_Transient_Scope (Return_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 (T)); |
| 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)); |
| end if; |
| end; |
| |
| -- Case of secondary stack not used |
| |
| elsif Function_Returns_With_DSP (Scope_Id) then |
| |
| -- Here what we need to do is to always return by reference, since |
| -- we will return with the stack pointer depressed. We may need to |
| -- do a copy to a local temporary before doing this return. |
| |
| No_Secondary_Stack_Case : declare |
| Local_Copy_Required : Boolean := False; |
| -- Set to True if a local copy is required |
| |
| Copy_Ent : Entity_Id; |
| -- Used for the target entity if a copy is required |
| |
| Decl : Node_Id; |
| -- Declaration used to create copy if needed |
| |
| procedure Test_Copy_Required (Expr : Node_Id); |
| -- Determines if Expr represents a return value for which a |
| -- copy is required. More specifically, a copy is not required |
| -- if Expr represents an object or component of an object that |
| -- is either in the local subprogram frame, or is constant. |
| -- If a copy is required, then Local_Copy_Required is set True. |
| |
| ------------------------ |
| -- Test_Copy_Required -- |
| ------------------------ |
| |
| procedure Test_Copy_Required (Expr : Node_Id) is |
| Ent : Entity_Id; |
| |
| begin |
| -- If component, test prefix (object containing component) |
| |
| if Nkind (Expr) = N_Indexed_Component |
| or else |
| Nkind (Expr) = N_Selected_Component |
| then |
| Test_Copy_Required (Prefix (Expr)); |
| return; |
| |
| -- See if we have an entity name |
| |
| elsif Is_Entity_Name (Expr) then |
| Ent := Entity (Expr); |
| |
| -- Constant entity is always OK, no copy required |
| |
| if Ekind (Ent) = E_Constant then |
| return; |
| |
| -- No copy required for local variable |
| |
| elsif Ekind (Ent) = E_Variable |
| and then Scope (Ent) = Current_Subprogram |
| then |
| return; |
| end if; |
| end if; |
| |
| -- All other cases require a copy |
| |
| Local_Copy_Required := True; |
| end Test_Copy_Required; |
| |
| -- Start of processing for No_Secondary_Stack_Case |
| |
| begin |
| -- No copy needed if result is from a function call. |
| -- In this case the result is already being returned by |
| -- reference with the stack pointer depressed. |
| |
| -- 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 (T) |
| and then |
| (not Is_Array_Type (T) |
| or else Is_Constrained (T) = Is_Constrained (Return_Type) |
| or else Controlled_Type (T)) |
| and then Nkind (Exp) = N_Function_Call |
| then |
| Set_By_Ref (N); |
| |
| -- We always need a local copy for a controlled type, since |
| -- we are required to finalize the local value before return. |
| -- The copy will automatically include the required finalize. |
| -- Moreover, gigi cannot make this copy, since we need special |
| -- processing to ensure proper behavior for finalization. |
| |
| -- Note: the reason we are returning with a depressed stack |
| -- pointer in the controlled case (even if the type involved |
| -- is constrained) is that we must make a local copy to deal |
| -- properly with the requirement that the local result be |
| -- finalized. |
| |
| elsif Controlled_Type (Utyp) then |
| Copy_Ent := |
| Make_Defining_Identifier (Loc, |
| Chars => New_Internal_Name ('R')); |
| |
| -- Build declaration to do the copy, and insert it, setting |
| -- Assignment_OK, because we may be copying a limited type. |
| -- In addition we set the special flag to inhibit finalize |
| -- attachment if this is a controlled type (since this attach |
| -- must be done by the caller, otherwise if we attach it here |
| -- we will finalize the returned result prematurely). |
| |
| Decl := |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Copy_Ent, |
| Object_Definition => New_Occurrence_Of (Return_Type, Loc), |
| Expression => Relocate_Node (Exp)); |
| |
| Set_Assignment_OK (Decl); |
| Set_Delay_Finalize_Attach (Decl); |
| Insert_Action (N, Decl); |
| |
| -- Now the actual return uses the copied value |
| |
| Rewrite (Exp, New_Occurrence_Of (Copy_Ent, Loc)); |
| Analyze_And_Resolve (Exp, Return_Type); |
| |
| -- Since we have made the copy, gigi does not have to, so |
| -- we set the By_Ref flag to prevent another copy being made. |
| |
| Set_By_Ref (N); |
| |
| -- Non-controlled cases |
| |
| else |
| Test_Copy_Required (Exp); |
| |
| -- If a local copy is required, then gigi will make the |
| -- copy, otherwise, we can return the result directly, |
| -- so set By_Ref to suppress the gigi copy. |
| |
| if not Local_Copy_Required then |
| Set_By_Ref (N); |
| end if; |
| end if; |
| end No_Secondary_Stack_Case; |
| |
| -- 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. See example in 7417-003. |
| |
| declare |
| S : Entity_Id := Current_Scope; |
| |
| begin |
| 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 (T) |
| and then |
| (not Is_Array_Type (T) |
| or else Is_Constrained (T) = Is_Constrained (Return_Type) |
| or else Controlled_Type (T)) |
| and then Nkind (Exp) = N_Function_Call |
| then |
| Set_By_Ref (N); |
| |
| -- Remove side effects from the expression now so that |
| -- other part 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 sec-stack |
| -- manually in order to call adjust at the right time |
| -- type Anon1 is access Return_Type; |
| -- for Anon1'Storage_pool use ss_pool; |
| -- Anon2 : anon1 := new Return_Type'(expr); |
| -- return Anon2.all; |
| |
| elsif 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 (Return_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, Return_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 Java VM do not use |
| -- SS_Allocate since everything is heap-allocated anyway. |
| |
| if not Java_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 (Exp) = N_Type_Conversion |
| or else Nkind (Exp) = 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 (Return_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 |
| Result_Id := |
| Make_Defining_Identifier (Loc, New_Internal_Name ('R')); |
| Result_Exp := New_Reference_To (Result_Id, Loc); |
| |
| Result_Obj := |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Result_Id, |
| Object_Definition => New_Reference_To (Return_Type, Loc), |
| Constant_Present => True, |
| Expression => Relocate_Node (Exp)); |
| |
| Set_Assignment_OK (Result_Obj); |
| Insert_Action (Exp, Result_Obj); |
| |
| Rewrite (Exp, Result_Exp); |
| Analyze_And_Resolve (Exp, Return_Type); |
| 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. |
| |
| elsif Ada_Version >= Ada_05 |
| and then Is_Class_Wide_Type (Return_Type) |
| and then not Scope_Suppress (Accessibility_Check) |
| and then |
| (Is_Class_Wide_Type (Etype (Exp)) |
| or else Nkind (Exp) = N_Type_Conversion |
| or else Nkind (Exp) = 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 |
| Insert_Action (Exp, |
| Make_Raise_Program_Error (Loc, |
| Condition => |
| Make_Op_Gt (Loc, |
| Left_Opnd => |
| Make_Function_Call (Loc, |
| Name => |
| New_Reference_To |
| (RTE (RE_Get_Access_Level), Loc), |
| Parameter_Associations => |
| New_List (Make_Attribute_Reference (Loc, |
| Prefix => |
| Duplicate_Subexpr (Exp), |
| Attribute_Name => |
| Name_Tag))), |
| Right_Opnd => |
| Make_Integer_Literal (Loc, |
| Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))), |
| Reason => PE_Accessibility_Check_Failed)); |
| end if; |
| |
| exception |
| when RE_Not_Available => |
| return; |
| end Expand_N_Return_Statement; |
| |
| ------------------------------ |
| -- 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 not Java_VM; |
| -- Tags are not saved and restored when Java_VM because JVM tags |
| -- are represented implicitly in objects. |
| |
| Res : List_Id; |
| Tag_Tmp : Entity_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; |
| |
| -- 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. |
| |
| if Ctrl_Act then |
| 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, |
| 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; |
| |
| 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; |
| |
| -- Adjust the target after the assignment when controlled (not in the |
| -- init proc since it is an initialization more than an assignment). |
| |
| if Ctrl_Act then |
| 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; |
| |
| ------------------------------------ |
| -- Possible_Bit_Aligned_Component -- |
| ------------------------------------ |
| |
| function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean is |
| begin |
| case Nkind (N) is |
| |
| -- Case of indexed component |
| |
| when N_Indexed_Component => |
| declare |
| P : constant Node_Id := Prefix (N); |
| Ptyp : constant Entity_Id := Etype (P); |
| |
| begin |
| -- If we know the component size and it is less than 64, then |
| -- we are definitely OK. The back end always does assignment |
| -- of misaligned small objects correctly. |
| |
| if Known_Static_Component_Size (Ptyp) |
| and then Component_Size (Ptyp) <= 64 |
| then |
| return False; |
| |
| -- Otherwise, we need to test the prefix, to see if we are |
| -- indexing from a possibly unaligned component. |
| |
| else |
| return Possible_Bit_Aligned_Component (P); |
| end if; |
| end; |
| |
| -- Case of selected component |
| |
| when N_Selected_Component => |
| declare |
| P : constant Node_Id := Prefix (N); |
| Comp : constant Entity_Id := Entity (Selector_Name (N)); |
| |
| begin |
| -- If there is no component clause, then we are in the clear |
| -- since the back end will never misalign a large component |
| -- unless it is forced to do so. In the clear means we need |
| -- only the recursive test on the prefix. |
| |
| if Component_May_Be_Bit_Aligned (Comp) then |
| return True; |
| else |
| return Possible_Bit_Aligned_Component (P); |
| end if; |
| end; |
| |
| -- If we have neither a record nor array component, it means that |
| -- we have fallen off the top testing prefixes recursively, and |
| -- we now have a stand alone object, where we don't have a problem |
| |
| when others => |
| return False; |
| |
| end case; |
| end Possible_Bit_Aligned_Component; |
| |
| end Exp_Ch5; |