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Diffstat (limited to 'gcc-4.4.0/gcc/ada/exp_ch5.adb')
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diff --git a/gcc-4.4.0/gcc/ada/exp_ch5.adb b/gcc-4.4.0/gcc/ada/exp_ch5.adb deleted file mode 100644 index d1c9d884e..000000000 --- a/gcc-4.4.0/gcc/ada/exp_ch5.adb +++ /dev/null @@ -1,4744 +0,0 @@ ------------------------------------------------------------------------------- --- -- --- GNAT COMPILER COMPONENTS -- --- -- --- E X P _ C H 5 -- --- -- --- B o d y -- --- -- --- Copyright (C) 1992-2008, Free Software Foundation, Inc. -- --- -- --- GNAT is free software; you can redistribute it and/or modify it under -- --- terms of the GNU General Public License as published by the Free Soft- -- --- ware Foundation; either version 3, or (at your option) any later ver- -- --- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- --- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- --- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- --- for more details. You should have received a copy of the GNU General -- --- Public License distributed with GNAT; see file COPYING3. If not, go to -- --- http://www.gnu.org/licenses for a complete copy of the license. -- --- -- --- GNAT was originally developed by the GNAT team at New York University. -- --- Extensive contributions were provided by Ada Core Technologies Inc. -- --- -- ------------------------------------------------------------------------------- - -with Atree; use Atree; -with Checks; use Checks; -with Debug; use Debug; -with Einfo; use Einfo; -with Elists; use Elists; -with Exp_Atag; use Exp_Atag; -with Exp_Aggr; use Exp_Aggr; -with Exp_Ch6; use Exp_Ch6; -with Exp_Ch7; use Exp_Ch7; -with Exp_Ch11; use Exp_Ch11; -with Exp_Dbug; use Exp_Dbug; -with Exp_Pakd; use Exp_Pakd; -with Exp_Tss; use Exp_Tss; -with Exp_Util; use Exp_Util; -with Namet; use Namet; -with Nlists; use Nlists; -with Nmake; use Nmake; -with Opt; use Opt; -with Restrict; use Restrict; -with Rident; use Rident; -with Rtsfind; use Rtsfind; -with Sinfo; use Sinfo; -with Sem; use Sem; -with Sem_Ch3; use Sem_Ch3; -with Sem_Ch8; use Sem_Ch8; -with Sem_Ch13; use Sem_Ch13; -with Sem_Eval; use Sem_Eval; -with Sem_Res; use Sem_Res; -with Sem_Util; use Sem_Util; -with Snames; use Snames; -with Stand; use Stand; -with Stringt; use Stringt; -with Targparm; use Targparm; -with Tbuild; use Tbuild; -with Ttypes; use Ttypes; -with Uintp; use Uintp; -with Validsw; use Validsw; - -package body Exp_Ch5 is - - function Change_Of_Representation (N : Node_Id) return Boolean; - -- Determine if the right hand side of the assignment N is a type - -- conversion which requires a change of representation. Called - -- only for the array and record cases. - - procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id); - -- N is an assignment which assigns an array value. This routine process - -- the various special cases and checks required for such assignments, - -- including change of representation. Rhs is normally simply the right - -- hand side of the assignment, except that if the right hand side is - -- a type conversion or a qualified expression, then the Rhs is the - -- actual expression inside any such type conversions or qualifications. - - function Expand_Assign_Array_Loop - (N : Node_Id; - Larray : Entity_Id; - Rarray : Entity_Id; - L_Type : Entity_Id; - R_Type : Entity_Id; - Ndim : Pos; - Rev : Boolean) return Node_Id; - -- N is an assignment statement which assigns an array value. This routine - -- expands the assignment into a loop (or nested loops for the case of a - -- multi-dimensional array) to do the assignment component by component. - -- Larray and Rarray are the entities of the actual arrays on the left - -- hand and right hand sides. L_Type and R_Type are the types of these - -- arrays (which may not be the same, due to either sliding, or to a - -- change of representation case). Ndim is the number of dimensions and - -- the parameter Rev indicates if the loops run normally (Rev = False), - -- or reversed (Rev = True). The value returned is the constructed - -- loop statement. Auxiliary declarations are inserted before node N - -- using the standard Insert_Actions mechanism. - - procedure Expand_Assign_Record (N : Node_Id); - -- N is an assignment of a non-tagged record value. This routine handles - -- the case where the assignment must be made component by component, - -- either because the target is not byte aligned, or there is a change - -- of representation. - - procedure Expand_Non_Function_Return (N : Node_Id); - -- Called by Expand_N_Simple_Return_Statement in case we're returning from - -- a procedure body, entry body, accept statement, or extended return - -- statement. Note that all non-function returns are simple return - -- statements. - - procedure Expand_Simple_Function_Return (N : Node_Id); - -- Expand simple return from function. In the case where we are returning - -- from a function body this is called by Expand_N_Simple_Return_Statement. - - 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, adjustment of - -- the target after and save and restore of the tag and finalization - -- pointers which are not 'part of the value' and must not be changed - -- upon assignment. N is the original Assignment node. - - ------------------------------ - -- Change_Of_Representation -- - ------------------------------ - - function Change_Of_Representation (N : Node_Id) return Boolean is - Rhs : constant Node_Id := Expression (N); - begin - return - Nkind (Rhs) = N_Type_Conversion - and then - not Same_Representation (Etype (Rhs), Etype (Expression (Rhs))); - end Change_Of_Representation; - - ------------------------- - -- Expand_Assign_Array -- - ------------------------- - - -- There are two issues here. First, do we let Gigi do a block move, or - -- do we expand out into a loop? Second, we need to set the two flags - -- Forwards_OK and Backwards_OK which show whether the block move (or - -- corresponding loops) can be legitimately done in a forwards (low to - -- high) or backwards (high to low) manner. - - procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - - Lhs : constant Node_Id := Name (N); - - Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs); - Act_Rhs : Node_Id := Get_Referenced_Object (Rhs); - - L_Type : constant Entity_Id := - Underlying_Type (Get_Actual_Subtype (Act_Lhs)); - R_Type : Entity_Id := - Underlying_Type (Get_Actual_Subtype (Act_Rhs)); - - L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice; - R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice; - - Crep : constant Boolean := Change_Of_Representation (N); - - Larray : Node_Id; - Rarray : Node_Id; - - Ndim : constant Pos := Number_Dimensions (L_Type); - - Loop_Required : Boolean := False; - -- This switch is set to True if the array move must be done using - -- an explicit front end generated loop. - - procedure Apply_Dereference (Arg : Node_Id); - -- If the argument is an access to an array, and the assignment is - -- converted into a procedure call, apply explicit dereference. - - function Has_Address_Clause (Exp : Node_Id) return Boolean; - -- Test if Exp is a reference to an array whose declaration has - -- an address clause, or it is a slice of such an array. - - function Is_Formal_Array (Exp : Node_Id) return Boolean; - -- Test if Exp is a reference to an array which is either a formal - -- parameter or a slice of a formal parameter. These are the cases - -- where hidden aliasing can occur. - - function Is_Non_Local_Array (Exp : Node_Id) return Boolean; - -- Determine if Exp is a reference to an array variable which is other - -- than an object defined in the current scope, or a slice of such - -- an object. Such objects can be aliased to parameters (unlike local - -- array references). - - ----------------------- - -- Apply_Dereference -- - ----------------------- - - procedure Apply_Dereference (Arg : Node_Id) is - Typ : constant Entity_Id := Etype (Arg); - begin - if Is_Access_Type (Typ) then - Rewrite (Arg, Make_Explicit_Dereference (Loc, - Prefix => Relocate_Node (Arg))); - Analyze_And_Resolve (Arg, Designated_Type (Typ)); - end if; - end Apply_Dereference; - - ------------------------ - -- Has_Address_Clause -- - ------------------------ - - function Has_Address_Clause (Exp : Node_Id) return Boolean is - begin - return - (Is_Entity_Name (Exp) and then - Present (Address_Clause (Entity (Exp)))) - or else - (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp))); - end Has_Address_Clause; - - --------------------- - -- Is_Formal_Array -- - --------------------- - - function Is_Formal_Array (Exp : Node_Id) return Boolean is - begin - return - (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp))) - or else - (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp))); - end Is_Formal_Array; - - ------------------------ - -- Is_Non_Local_Array -- - ------------------------ - - function Is_Non_Local_Array (Exp : Node_Id) return Boolean is - begin - return (Is_Entity_Name (Exp) - and then Scope (Entity (Exp)) /= Current_Scope) - or else (Nkind (Exp) = N_Slice - and then Is_Non_Local_Array (Prefix (Exp))); - end Is_Non_Local_Array; - - -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays - - Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs); - Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs); - - Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs); - Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs); - - -- Start of processing for Expand_Assign_Array - - begin - -- Deal with length check. Note that the length check is done with - -- respect to the right hand side as given, not a possible underlying - -- renamed object, since this would generate incorrect extra checks. - - Apply_Length_Check (Rhs, L_Type); - - -- We start by assuming that the move can be done in either direction, - -- i.e. that the two sides are completely disjoint. - - Set_Forwards_OK (N, True); - Set_Backwards_OK (N, True); - - -- Normally it is only the slice case that can lead to overlap, and - -- explicit checks for slices are made below. But there is one case - -- where the slice can be implicit and invisible to us: when we have a - -- one dimensional array, and either both operands are parameters, or - -- one is a parameter (which can be a slice passed by reference) and the - -- other is a non-local variable. In this case the parameter could be a - -- slice that overlaps with the other operand. - - -- However, if the array subtype is a constrained first subtype in the - -- parameter case, then we don't have to worry about overlap, since - -- slice assignments aren't possible (other than for a slice denoting - -- the whole array). - - -- Note: No overlap is possible if there is a change of representation, - -- so we can exclude this case. - - if Ndim = 1 - and then not Crep - and then - ((Lhs_Formal and Rhs_Formal) - or else - (Lhs_Formal and Rhs_Non_Local_Var) - or else - (Rhs_Formal and Lhs_Non_Local_Var)) - and then - (not Is_Constrained (Etype (Lhs)) - or else not Is_First_Subtype (Etype (Lhs))) - - -- In the case of compiling for the Java or .NET Virtual Machine, - -- slices are always passed by making a copy, so we don't have to - -- worry about overlap. We also want to prevent generation of "<" - -- comparisons for array addresses, since that's a meaningless - -- operation on the VM. - - and then VM_Target = No_VM - then - Set_Forwards_OK (N, False); - Set_Backwards_OK (N, False); - - -- Note: the bit-packed case is not worrisome here, since if we have - -- a slice passed as a parameter, it is always aligned on a byte - -- boundary, and if there are no explicit slices, the assignment - -- can be performed directly. - end if; - - -- We certainly must use a loop for change of representation and also - -- we use the operand of the conversion on the right hand side as the - -- effective right hand side (the component types must match in this - -- situation). - - if Crep then - Act_Rhs := Get_Referenced_Object (Rhs); - R_Type := Get_Actual_Subtype (Act_Rhs); - Loop_Required := True; - - -- We require a loop if the left side is possibly bit unaligned - - elsif Possible_Bit_Aligned_Component (Lhs) - or else - Possible_Bit_Aligned_Component (Rhs) - then - Loop_Required := True; - - -- Arrays with controlled components are expanded into a loop to force - -- calls to Adjust at the component level. - - elsif Has_Controlled_Component (L_Type) then - Loop_Required := True; - - -- If object is atomic, we cannot tolerate a loop - - elsif Is_Atomic_Object (Act_Lhs) - or else - Is_Atomic_Object (Act_Rhs) - then - return; - - -- Loop is required if we have atomic components since we have to - -- be sure to do any accesses on an element by element basis. - - elsif Has_Atomic_Components (L_Type) - or else Has_Atomic_Components (R_Type) - or else Is_Atomic (Component_Type (L_Type)) - or else Is_Atomic (Component_Type (R_Type)) - then - Loop_Required := True; - - -- Case where no slice is involved - - elsif not L_Slice and not R_Slice then - - -- The following code deals with the case of unconstrained bit packed - -- arrays. The problem is that the template for such arrays contains - -- the bounds of the actual source level array, but the copy of an - -- entire array requires the bounds of the underlying array. It would - -- be nice if the back end could take care of this, but right now it - -- does not know how, so if we have such a type, then we expand out - -- into a loop, which is inefficient but works correctly. If we don't - -- do this, we get the wrong length computed for the array to be - -- moved. The two cases we need to worry about are: - - -- Explicit deference of an unconstrained packed array type as in the - -- following example: - - -- procedure C52 is - -- type BITS is array(INTEGER range <>) of BOOLEAN; - -- pragma PACK(BITS); - -- type A is access BITS; - -- P1,P2 : A; - -- begin - -- P1 := new BITS (1 .. 65_535); - -- P2 := new BITS (1 .. 65_535); - -- P2.ALL := P1.ALL; - -- end C52; - - -- A formal parameter reference with an unconstrained bit array type - -- is the other case we need to worry about (here we assume the same - -- BITS type declared above): - - -- procedure Write_All (File : out BITS; Contents : BITS); - -- begin - -- File.Storage := Contents; - -- end Write_All; - - -- We expand to a loop in either of these two cases - - -- Question for future thought. Another potentially more efficient - -- approach would be to create the actual subtype, and then do an - -- unchecked conversion to this actual subtype ??? - - Check_Unconstrained_Bit_Packed_Array : declare - - function Is_UBPA_Reference (Opnd : Node_Id) return Boolean; - -- Function to perform required test for the first case, above - -- (dereference of an unconstrained bit packed array). - - ----------------------- - -- Is_UBPA_Reference -- - ----------------------- - - function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is - Typ : constant Entity_Id := Underlying_Type (Etype (Opnd)); - P_Type : Entity_Id; - Des_Type : Entity_Id; - - begin - if Present (Packed_Array_Type (Typ)) - and then Is_Array_Type (Packed_Array_Type (Typ)) - and then not Is_Constrained (Packed_Array_Type (Typ)) - then - return True; - - elsif Nkind (Opnd) = N_Explicit_Dereference then - P_Type := Underlying_Type (Etype (Prefix (Opnd))); - - if not Is_Access_Type (P_Type) then - return False; - - else - Des_Type := Designated_Type (P_Type); - return - Is_Bit_Packed_Array (Des_Type) - and then not Is_Constrained (Des_Type); - end if; - - else - return False; - end if; - end Is_UBPA_Reference; - - -- Start of processing for Check_Unconstrained_Bit_Packed_Array - - begin - if Is_UBPA_Reference (Lhs) - or else - Is_UBPA_Reference (Rhs) - then - Loop_Required := True; - - -- Here if we do not have the case of a reference to a bit packed - -- unconstrained array case. In this case gigi can most certainly - -- handle the assignment if a forwards move is allowed. - - -- (could it handle the backwards case also???) - - elsif Forwards_OK (N) then - return; - end if; - end Check_Unconstrained_Bit_Packed_Array; - - -- The back end can always handle the assignment if the right side is a - -- string literal (note that overlap is definitely impossible in this - -- case). If the type is packed, a string literal is always converted - -- into an aggregate, except in the case of a null slice, for which no - -- aggregate can be written. In that case, rewrite the assignment as a - -- null statement, a length check has already been emitted to verify - -- that the range of the left-hand side is empty. - - -- Note that this code is not executed if we have an assignment of a - -- string literal to a non-bit aligned component of a record, a case - -- which cannot be handled by the backend. - - elsif Nkind (Rhs) = N_String_Literal then - if String_Length (Strval (Rhs)) = 0 - and then Is_Bit_Packed_Array (L_Type) - then - Rewrite (N, Make_Null_Statement (Loc)); - Analyze (N); - end if; - - return; - - -- If either operand is bit packed, then we need a loop, since we can't - -- be sure that the slice is byte aligned. Similarly, if either operand - -- is a possibly unaligned slice, then we need a loop (since the back - -- end cannot handle unaligned slices). - - elsif Is_Bit_Packed_Array (L_Type) - or else Is_Bit_Packed_Array (R_Type) - or else Is_Possibly_Unaligned_Slice (Lhs) - or else Is_Possibly_Unaligned_Slice (Rhs) - then - Loop_Required := True; - - -- If we are not bit-packed, and we have only one slice, then no overlap - -- is possible except in the parameter case, so we can let the back end - -- handle things. - - elsif not (L_Slice and R_Slice) then - if Forwards_OK (N) then - return; - end if; - end if; - - -- If the right-hand side is a string literal, introduce a temporary for - -- it, for use in the generated loop that will follow. - - if Nkind (Rhs) = N_String_Literal then - declare - Temp : constant Entity_Id := - Make_Defining_Identifier (Loc, New_Internal_Name ('T')); - Decl : Node_Id; - - begin - Decl := - Make_Object_Declaration (Loc, - Defining_Identifier => Temp, - Object_Definition => New_Occurrence_Of (L_Type, Loc), - Expression => Relocate_Node (Rhs)); - - Insert_Action (N, Decl); - Rewrite (Rhs, New_Occurrence_Of (Temp, Loc)); - R_Type := Etype (Temp); - end; - end if; - - -- Come here to complete the analysis - - -- Loop_Required: Set to True if we know that a loop is required - -- regardless of overlap considerations. - - -- Forwards_OK: Set to False if we already know that a forwards - -- move is not safe, else set to True. - - -- Backwards_OK: Set to False if we already know that a backwards - -- move is not safe, else set to True - - -- Our task at this stage is to complete the overlap analysis, which can - -- result in possibly setting Forwards_OK or Backwards_OK to False, and - -- then generating the final code, either by deciding that it is OK - -- after all to let Gigi handle it, or by generating appropriate code - -- in the front end. - - declare - L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type)); - R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type)); - - Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ); - Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ); - Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ); - Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ); - - Act_L_Array : Node_Id; - Act_R_Array : Node_Id; - - Cleft_Lo : Node_Id; - Cright_Lo : Node_Id; - Condition : Node_Id; - - Cresult : Compare_Result; - - begin - -- Get the expressions for the arrays. If we are dealing with a - -- private type, then convert to the underlying type. We can do - -- direct assignments to an array that is a private type, but we - -- cannot assign to elements of the array without this extra - -- unchecked conversion. - - if Nkind (Act_Lhs) = N_Slice then - Larray := Prefix (Act_Lhs); - else - Larray := Act_Lhs; - - if Is_Private_Type (Etype (Larray)) then - Larray := - Unchecked_Convert_To - (Underlying_Type (Etype (Larray)), Larray); - end if; - end if; - - if Nkind (Act_Rhs) = N_Slice then - Rarray := Prefix (Act_Rhs); - else - Rarray := Act_Rhs; - - if Is_Private_Type (Etype (Rarray)) then - Rarray := - Unchecked_Convert_To - (Underlying_Type (Etype (Rarray)), Rarray); - end if; - end if; - - -- If both sides are slices, we must figure out whether it is safe - -- to do the move in one direction or the other. It is always safe - -- if there is a change of representation since obviously two arrays - -- with different representations cannot possibly overlap. - - if (not Crep) and L_Slice and R_Slice then - Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs)); - Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs)); - - -- If both left and right hand arrays are entity names, and refer - -- to different entities, then we know that the move is safe (the - -- two storage areas are completely disjoint). - - if Is_Entity_Name (Act_L_Array) - and then Is_Entity_Name (Act_R_Array) - and then Entity (Act_L_Array) /= Entity (Act_R_Array) - then - null; - - -- Otherwise, we assume the worst, which is that the two arrays - -- are the same array. There is no need to check if we know that - -- is the case, because if we don't know it, we still have to - -- assume it! - - -- Generally if the same array is involved, then we have an - -- overlapping case. We will have to really assume the worst (i.e. - -- set neither of the OK flags) unless we can determine the lower - -- or upper bounds at compile time and compare them. - - else - Cresult := - Compile_Time_Compare - (Left_Lo, Right_Lo, Assume_Valid => True); - - if Cresult = Unknown then - Cresult := - Compile_Time_Compare - (Left_Hi, Right_Hi, Assume_Valid => True); - end if; - - case Cresult is - when LT | LE | EQ => Set_Backwards_OK (N, False); - when GT | GE => Set_Forwards_OK (N, False); - when NE | Unknown => Set_Backwards_OK (N, False); - Set_Forwards_OK (N, False); - end case; - end if; - end if; - - -- If after that analysis, Forwards_OK is still True, and - -- Loop_Required is False, meaning that we have not discovered some - -- non-overlap reason for requiring a loop, then we can still let - -- gigi handle it. - - if not Loop_Required then - - -- Assume gigi can handle it if Forwards_OK is set - - if Forwards_OK (N) then - return; - - -- If Forwards_OK is not set, the back end will need something - -- like memmove to handle the move. For now, this processing is - -- activated using the .s debug flag (-gnatd.s). - - elsif Debug_Flag_Dot_S then - return; - end if; - end if; - - -- At this stage we have to generate an explicit loop, and we have - -- the following cases: - - -- Forwards_OK = True - - -- Rnn : right_index := right_index'First; - -- for Lnn in left-index loop - -- left (Lnn) := right (Rnn); - -- Rnn := right_index'Succ (Rnn); - -- end loop; - - -- Note: the above code MUST be analyzed with checks off, because - -- otherwise the Succ could overflow. But in any case this is more - -- efficient! - - -- Forwards_OK = False, Backwards_OK = True - - -- Rnn : right_index := right_index'Last; - -- for Lnn in reverse left-index loop - -- left (Lnn) := right (Rnn); - -- Rnn := right_index'Pred (Rnn); - -- end loop; - - -- Note: the above code MUST be analyzed with checks off, because - -- otherwise the Pred could overflow. But in any case this is more - -- efficient! - - -- Forwards_OK = Backwards_OK = False - - -- This only happens if we have the same array on each side. It is - -- possible to create situations using overlays that violate this, - -- but we simply do not promise to get this "right" in this case. - - -- There are two possible subcases. If the No_Implicit_Conditionals - -- restriction is set, then we generate the following code: - - -- declare - -- T : constant <operand-type> := rhs; - -- begin - -- lhs := T; - -- end; - - -- If implicit conditionals are permitted, then we generate: - - -- if Left_Lo <= Right_Lo then - -- <code for Forwards_OK = True above> - -- else - -- <code for Backwards_OK = True above> - -- end if; - - -- In order to detect possible aliasing, we examine the renamed - -- expression when the source or target is a renaming. However, - -- the renaming may be intended to capture an address that may be - -- affected by subsequent code, and therefore we must recover - -- the actual entity for the expansion that follows, not the - -- object it renames. In particular, if source or target designate - -- a portion of a dynamically allocated object, the pointer to it - -- may be reassigned but the renaming preserves the proper location. - - if Is_Entity_Name (Rhs) - and then - Nkind (Parent (Entity (Rhs))) = N_Object_Renaming_Declaration - and then Nkind (Act_Rhs) = N_Slice - then - Rarray := Rhs; - end if; - - if Is_Entity_Name (Lhs) - and then - Nkind (Parent (Entity (Lhs))) = N_Object_Renaming_Declaration - and then Nkind (Act_Lhs) = N_Slice - then - Larray := Lhs; - end if; - - -- Cases where either Forwards_OK or Backwards_OK is true - - if Forwards_OK (N) or else Backwards_OK (N) then - if Needs_Finalization (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 reliable, and handles the cases of - -- parameters, conversions etc. But we can't do that in the bit - -- packed case or the VM case, because addresses don't work there. - - if not Is_Bit_Packed_Array (L_Type) and then VM_Target = No_VM then - Condition := - Make_Op_Le (Loc, - Left_Opnd => - Unchecked_Convert_To (RTE (RE_Integer_Address), - Make_Attribute_Reference (Loc, - Prefix => - Make_Indexed_Component (Loc, - Prefix => - Duplicate_Subexpr_Move_Checks (Larray, True), - Expressions => New_List ( - Make_Attribute_Reference (Loc, - Prefix => - New_Reference_To - (L_Index_Typ, Loc), - Attribute_Name => Name_First))), - Attribute_Name => Name_Address)), - - Right_Opnd => - Unchecked_Convert_To (RTE (RE_Integer_Address), - Make_Attribute_Reference (Loc, - Prefix => - Make_Indexed_Component (Loc, - Prefix => - Duplicate_Subexpr_Move_Checks (Rarray, True), - Expressions => New_List ( - Make_Attribute_Reference (Loc, - Prefix => - New_Reference_To - (R_Index_Typ, Loc), - Attribute_Name => Name_First))), - Attribute_Name => Name_Address))); - - -- For the bit packed and VM cases we use the bounds. That's OK, - -- because we don't have to worry about parameters, since they - -- cannot cause overlap. Perhaps we should worry about weird slice - -- conversions ??? - - else - -- Copy the bounds and reset the Analyzed flag, because the - -- bounds of the index type itself may be universal, and must - -- must be reaanalyzed to acquire the proper type for Gigi. - - Cleft_Lo := New_Copy_Tree (Left_Lo); - Cright_Lo := New_Copy_Tree (Right_Lo); - Set_Analyzed (Cleft_Lo, False); - Set_Analyzed (Cright_Lo, False); - - Condition := - Make_Op_Le (Loc, - Left_Opnd => Cleft_Lo, - Right_Opnd => Cright_Lo); - end if; - - if Needs_Finalization (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 - -- explicit bounds of right and left hand sides. - - 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, - 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 we are expanding the initialization of a derived record - -- that constrains or renames discriminants of the parent, we - -- must use the corresponding discriminant in the parent. - - declare - CF : Entity_Id; - - begin - if Inside_Init_Proc - and then Present (Corresponding_Discriminant (F)) - then - CF := Corresponding_Discriminant (F); - else - CF := F; - end if; - - if Is_Unchecked_Union (Base_Type (R_Typ)) then - Insert_Action (N, Make_Field_Assign (CF, True)); - else - Insert_Action (N, Make_Field_Assign (CF)); - end if; - - Next_Discriminant (F); - end; - end loop; - end if; - - -- We know the underlying type is a record, but its current view - -- may be private. We must retrieve the usable record declaration. - - if Nkind (Decl) = N_Private_Type_Declaration - and then Present (Full_View (R_Typ)) - then - RDef := Type_Definition (Declaration_Node (Full_View (R_Typ))); - else - RDef := Type_Definition (Decl); - end if; - - if Nkind (RDef) = N_Record_Definition - and then Present (Component_List (RDef)) - then - - if Is_Unchecked_Union (R_Typ) then - Insert_Actions (N, - Make_Component_List_Assign (Component_List (RDef), True)); - else - Insert_Actions - (N, Make_Component_List_Assign (Component_List (RDef))); - end if; - - Rewrite (N, Make_Null_Statement (Loc)); - end if; - - end; - end Expand_Assign_Record; - - ----------------------------------- - -- Expand_N_Assignment_Statement -- - ----------------------------------- - - -- This procedure implements various cases where an assignment statement - -- cannot just be passed on to the back end in untransformed state. - - procedure Expand_N_Assignment_Statement (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Lhs : constant Node_Id := Name (N); - Rhs : constant Node_Id := Expression (N); - Typ : constant Entity_Id := Underlying_Type (Etype (Lhs)); - Exp : Node_Id; - - begin - -- Ada 2005 (AI-327): Handle assignment to priority of protected object - - -- Rewrite an assignment to X'Priority into a run-time call - - -- For example: X'Priority := New_Prio_Expr; - -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr); - - -- Note that although X'Priority is notionally an object, it is quite - -- deliberately not defined as an aliased object in the RM. This means - -- that it works fine to rewrite it as a call, without having to worry - -- about complications that would other arise from X'Priority'Access, - -- which is illegal, because of the lack of aliasing. - - if Ada_Version >= Ada_05 then - declare - Call : Node_Id; - Conctyp : Entity_Id; - Ent : Entity_Id; - Subprg : Entity_Id; - RT_Subprg_Name : Node_Id; - - begin - -- Handle chains of renamings - - Ent := Name (N); - while Nkind (Ent) in N_Has_Entity - and then Present (Entity (Ent)) - and then Present (Renamed_Object (Entity (Ent))) - loop - Ent := Renamed_Object (Entity (Ent)); - end loop; - - -- The attribute Priority applied to protected objects has been - -- previously expanded into a call to the Get_Ceiling run-time - -- subprogram. - - if Nkind (Ent) = N_Function_Call - and then (Entity (Name (Ent)) = RTE (RE_Get_Ceiling) - or else - Entity (Name (Ent)) = RTE (RO_PE_Get_Ceiling)) - then - -- Look for the enclosing concurrent type - - Conctyp := Current_Scope; - while not Is_Concurrent_Type (Conctyp) loop - Conctyp := Scope (Conctyp); - end loop; - - pragma Assert (Is_Protected_Type (Conctyp)); - - -- Generate the first actual of the call - - Subprg := Current_Scope; - while not Present (Protected_Body_Subprogram (Subprg)) loop - Subprg := Scope (Subprg); - end loop; - - -- Select the appropriate run-time call - - if Number_Entries (Conctyp) = 0 then - RT_Subprg_Name := - New_Reference_To (RTE (RE_Set_Ceiling), Loc); - else - RT_Subprg_Name := - New_Reference_To (RTE (RO_PE_Set_Ceiling), Loc); - end if; - - Call := - Make_Procedure_Call_Statement (Loc, - Name => RT_Subprg_Name, - Parameter_Associations => New_List ( - New_Copy_Tree (First (Parameter_Associations (Ent))), - Relocate_Node (Expression (N)))); - - Rewrite (N, Call); - Analyze (N); - return; - end if; - end; - end if; - - -- First deal with generation of range check if required. For now we do - -- this only for discrete types. - - if Do_Range_Check (Rhs) - and then Is_Discrete_Type (Typ) - then - Set_Do_Range_Check (Rhs, False); - Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed); - end if; - - -- Check for a special case where a high level transformation is - -- required. If we have either of: - - -- P.field := rhs; - -- P (sub) := rhs; - - -- where P is a reference to a bit packed array, then we have to unwind - -- the assignment. The exact meaning of being a reference to a bit - -- packed array is as follows: - - -- An indexed component whose prefix is a bit packed array is a - -- reference to a bit packed array. - - -- An indexed component or selected component whose prefix is a - -- reference to a bit packed array is itself a reference ot a - -- bit packed array. - - -- The required transformation is - - -- Tnn : prefix_type := P; - -- Tnn.field := rhs; - -- P := Tnn; - - -- or - - -- Tnn : prefix_type := P; - -- Tnn (subscr) := rhs; - -- P := Tnn; - - -- Since P is going to be evaluated more than once, any subscripts - -- in P must have their evaluation forced. - - if Nkind_In (Lhs, N_Indexed_Component, N_Selected_Component) - and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs)) - then - declare - BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs)); - BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr); - Tnn : constant Entity_Id := - Make_Defining_Identifier (Loc, - Chars => New_Internal_Name ('T')); - - begin - -- Insert the post assignment first, because we want to copy the - -- BPAR_Expr tree before it gets analyzed in the context of the - -- pre assignment. Note that we do not analyze the post assignment - -- yet (we cannot till we have completed the analysis of the pre - -- assignment). As usual, the analysis of this post assignment - -- will happen on its own when we "run into" it after finishing - -- the current assignment. - - Insert_After (N, - Make_Assignment_Statement (Loc, - Name => New_Copy_Tree (BPAR_Expr), - Expression => New_Occurrence_Of (Tnn, Loc))); - - -- At this stage BPAR_Expr is a reference to a bit packed array - -- where the reference was not expanded in the original tree, - -- since it was on the left side of an assignment. But in the - -- pre-assignment statement (the object definition), BPAR_Expr - -- will end up on the right hand side, and must be reexpanded. To - -- achieve this, we reset the analyzed flag of all selected and - -- indexed components down to the actual indexed component for - -- the packed array. - - Exp := BPAR_Expr; - loop - Set_Analyzed (Exp, False); - - if Nkind_In - (Exp, N_Selected_Component, N_Indexed_Component) - then - Exp := Prefix (Exp); - else - exit; - end if; - end loop; - - -- Now we can insert and analyze the pre-assignment - - -- If the right-hand side requires a transient scope, it has - -- already been placed on the stack. However, the declaration is - -- inserted in the tree outside of this scope, and must reflect - -- the proper scope for its variable. This awkward bit is forced - -- by the stricter scope discipline imposed by GCC 2.97. - - declare - Uses_Transient_Scope : constant Boolean := - Scope_Is_Transient - and then N = Node_To_Be_Wrapped; - - begin - if Uses_Transient_Scope then - Push_Scope (Scope (Current_Scope)); - end if; - - Insert_Before_And_Analyze (N, - Make_Object_Declaration (Loc, - Defining_Identifier => Tnn, - Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc), - Expression => BPAR_Expr)); - - if Uses_Transient_Scope then - Pop_Scope; - end if; - end; - - -- Now fix up the original assignment and continue processing - - Rewrite (Prefix (Lhs), - New_Occurrence_Of (Tnn, Loc)); - - -- We do not need to reanalyze that assignment, and we do not need - -- to worry about references to the temporary, but we do need to - -- make sure that the temporary is not marked as a true constant - -- since we now have a generated assignment to it! - - Set_Is_True_Constant (Tnn, False); - end; - end if; - - -- When we have the appropriate type of aggregate in the expression (it - -- has been determined during analysis of the aggregate by setting the - -- delay flag), let's perform in place assignment and thus avoid - -- creating a temporary. - - if Is_Delayed_Aggregate (Rhs) then - Convert_Aggr_In_Assignment (N); - Rewrite (N, Make_Null_Statement (Loc)); - Analyze (N); - return; - end if; - - -- Apply discriminant check if required. If Lhs is an access type to a - -- designated type with discriminants, we must always check. - - if Has_Discriminants (Etype (Lhs)) then - - -- Skip discriminant check if change of representation. Will be - -- done when the change of representation is expanded out. - - if not Change_Of_Representation (N) then - Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs); - end if; - - -- If the type is private without discriminants, and the full type - -- has discriminants (necessarily with defaults) a check may still be - -- necessary if the Lhs is aliased. The private determinants must be - -- visible to build the discriminant constraints. - - -- Only an explicit dereference that comes from source indicates - -- aliasing. Access to formals of protected operations and entries - -- create dereferences but are not semantic aliasings. - - elsif Is_Private_Type (Etype (Lhs)) - and then Has_Discriminants (Typ) - and then Nkind (Lhs) = N_Explicit_Dereference - and then Comes_From_Source (Lhs) - then - declare - Lt : constant Entity_Id := Etype (Lhs); - begin - Set_Etype (Lhs, Typ); - Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs)); - Apply_Discriminant_Check (Rhs, Typ, Lhs); - Set_Etype (Lhs, Lt); - end; - - -- If the Lhs has a private type with unknown discriminants, it - -- may have a full view with discriminants, but those are nameable - -- only in the underlying type, so convert the Rhs to it before - -- potential checking. - - elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs))) - and then Has_Discriminants (Typ) - then - Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs)); - Apply_Discriminant_Check (Rhs, Typ, Lhs); - - -- In the access type case, we need the same discriminant check, and - -- also range checks if we have an access to constrained array. - - elsif Is_Access_Type (Etype (Lhs)) - and then Is_Constrained (Designated_Type (Etype (Lhs))) - then - if Has_Discriminants (Designated_Type (Etype (Lhs))) then - - -- Skip discriminant check if change of representation. Will be - -- done when the change of representation is expanded out. - - if not Change_Of_Representation (N) then - Apply_Discriminant_Check (Rhs, Etype (Lhs)); - end if; - - elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then - Apply_Range_Check (Rhs, Etype (Lhs)); - - if Is_Constrained (Etype (Lhs)) then - Apply_Length_Check (Rhs, Etype (Lhs)); - end if; - - if Nkind (Rhs) = N_Allocator then - declare - Target_Typ : constant Entity_Id := Etype (Expression (Rhs)); - C_Es : Check_Result; - - begin - C_Es := - Get_Range_Checks - (Lhs, - Target_Typ, - Etype (Designated_Type (Etype (Lhs)))); - - Insert_Range_Checks - (C_Es, - N, - Target_Typ, - Sloc (Lhs), - Lhs); - end; - end if; - end if; - - -- Apply range check for access type case - - elsif Is_Access_Type (Etype (Lhs)) - and then Nkind (Rhs) = N_Allocator - and then Nkind (Expression (Rhs)) = N_Qualified_Expression - then - Analyze_And_Resolve (Expression (Rhs)); - Apply_Range_Check - (Expression (Rhs), Designated_Type (Etype (Lhs))); - end if; - - -- Ada 2005 (AI-231): Generate the run-time check - - if Is_Access_Type (Typ) - and then Can_Never_Be_Null (Etype (Lhs)) - and then not Can_Never_Be_Null (Etype (Rhs)) - then - Apply_Constraint_Check (Rhs, Etype (Lhs)); - end if; - - -- Case of assignment to a bit packed array element - - if Nkind (Lhs) = N_Indexed_Component - and then Is_Bit_Packed_Array (Etype (Prefix (Lhs))) - then - Expand_Bit_Packed_Element_Set (N); - return; - - -- Build-in-place function call case. Note that we're not yet doing - -- build-in-place for user-written assignment statements (the assignment - -- here came from an aggregate.) - - elsif Ada_Version >= Ada_05 - and then Is_Build_In_Place_Function_Call (Rhs) - then - Make_Build_In_Place_Call_In_Assignment (N, Rhs); - - elsif Is_Tagged_Type (Typ) and then Is_Value_Type (Etype (Lhs)) then - - -- Nothing to do for valuetypes - -- ??? Set_Scope_Is_Transient (False); - - return; - - elsif Is_Tagged_Type (Typ) - or else (Needs_Finalization (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 assignments created by the expander that - -- correspond to initializations, where we do want to copy the - -- tag (No_Ctrl_Actions flag set True) by the expander and we - -- do not need to mess with tags ever (Expand_Ctrl_Actions flag - -- is set True in this case). - - or else (Is_Tagged_Type (Typ) - and then not Is_Value_Type (Etype (Lhs)) - and then Chars (Current_Scope) /= Name_uAssign - and then Expand_Ctrl_Actions - and then not Discriminant_Checks_Suppressed (Empty)) - then - -- Fetch the primitive op _assign and proper type to call it. - -- Because of possible conflicts between private and full view - -- the proper type is fetched directly from the operation - -- profile. - - declare - Op : constant Entity_Id := - Find_Prim_Op (Typ, Name_uAssign); - F_Typ : Entity_Id := Etype (First_Formal (Op)); - - begin - -- If the assignment is dispatching, make sure to use the - -- proper type. - - if Is_Class_Wide_Type (Typ) then - F_Typ := Class_Wide_Type (F_Typ); - end if; - - L := New_List; - - -- In case of assignment to a class-wide tagged type, before - -- the assignment we generate run-time check to ensure that - -- the tags of source and target match. - - if Is_Class_Wide_Type (Typ) - and then Is_Tagged_Type (Typ) - and then Is_Tagged_Type (Underlying_Type (Etype (Rhs))) - then - Append_To (L, - Make_Raise_Constraint_Error (Loc, - Condition => - Make_Op_Ne (Loc, - Left_Opnd => - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr (Lhs), - Selector_Name => - Make_Identifier (Loc, - Chars => Name_uTag)), - Right_Opnd => - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr (Rhs), - Selector_Name => - Make_Identifier (Loc, - Chars => Name_uTag))), - Reason => CE_Tag_Check_Failed)); - end if; - - Append_To (L, - Make_Procedure_Call_Statement (Loc, - Name => New_Reference_To (Op, Loc), - Parameter_Associations => New_List ( - Unchecked_Convert_To (F_Typ, - Duplicate_Subexpr (Lhs)), - Unchecked_Convert_To (F_Typ, - Duplicate_Subexpr (Rhs))))); - end; - - else - L := Make_Tag_Ctrl_Assignment (N); - - -- We can't afford to have destructive Finalization Actions in - -- the Self assignment case, so if the target and the source - -- are not obviously different, code is generated to avoid the - -- self assignment case: - - -- if lhs'address /= rhs'address then - -- <code for controlled and/or tagged assignment> - -- end if; - - -- Skip this if Restriction (No_Finalization) is active - - if not Statically_Different (Lhs, Rhs) - and then Expand_Ctrl_Actions - and then not Restriction_Active (No_Finalization) - then - L := New_List ( - Make_Implicit_If_Statement (N, - Condition => - Make_Op_Ne (Loc, - Left_Opnd => - Make_Attribute_Reference (Loc, - Prefix => Duplicate_Subexpr (Lhs), - Attribute_Name => Name_Address), - - Right_Opnd => - Make_Attribute_Reference (Loc, - Prefix => Duplicate_Subexpr (Rhs), - Attribute_Name => Name_Address)), - - Then_Statements => L)); - end if; - - -- We need to set up an exception handler for implementing - -- 7.6.1(18). The remaining adjustments are tackled by the - -- implementation of adjust for record_controllers (see - -- s-finimp.adb). - - -- This is skipped if we have no finalization - - if Expand_Ctrl_Actions - and then not Restriction_Active (No_Finalization) - then - L := New_List ( - Make_Block_Statement (Loc, - Handled_Statement_Sequence => - Make_Handled_Sequence_Of_Statements (Loc, - Statements => L, - Exception_Handlers => New_List ( - Make_Handler_For_Ctrl_Operation (Loc))))); - end if; - end if; - - Rewrite (N, - Make_Block_Statement (Loc, - Handled_Statement_Sequence => - Make_Handled_Sequence_Of_Statements (Loc, Statements => L))); - - -- If no restrictions on aborts, protect the whole assignment - -- for controlled objects as per 9.8(11). - - if Needs_Finalization (Typ) - and then Expand_Ctrl_Actions - and then Abort_Allowed - then - declare - Blk : constant Entity_Id := - New_Internal_Entity - (E_Block, Current_Scope, Sloc (N), 'B'); - - begin - Set_Scope (Blk, Current_Scope); - Set_Etype (Blk, Standard_Void_Type); - Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N))); - - Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer)); - Set_At_End_Proc (Handled_Statement_Sequence (N), - New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc)); - Expand_At_End_Handler - (Handled_Statement_Sequence (N), Blk); - end; - end if; - - -- N has been rewritten to a block statement for which it is - -- known by construction that no checks are necessary: analyze - -- it with all checks suppressed. - - Analyze (N, Suppress => All_Checks); - return; - end Tagged_Case; - - -- Array types - - elsif Is_Array_Type (Typ) then - declare - Actual_Rhs : Node_Id := Rhs; - - begin - while Nkind_In (Actual_Rhs, N_Type_Conversion, - N_Qualified_Expression) - loop - Actual_Rhs := Expression (Actual_Rhs); - end loop; - - Expand_Assign_Array (N, Actual_Rhs); - return; - end; - - -- Record types - - elsif Is_Record_Type (Typ) then - Expand_Assign_Record (N); - return; - - -- Scalar types. This is where we perform the processing related to the - -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid - -- scalar values. - - elsif Is_Scalar_Type (Typ) then - - -- Case where right side is known valid - - if Expr_Known_Valid (Rhs) then - - -- Here the right side is valid, so it is fine. The case to deal - -- with is when the left side is a local variable reference whose - -- value is not currently known to be valid. If this is the case, - -- and the assignment appears in an unconditional context, then we - -- can mark the left side as now being valid. - - if Is_Local_Variable_Reference (Lhs) - and then not Is_Known_Valid (Entity (Lhs)) - and then In_Unconditional_Context (N) - then - Set_Is_Known_Valid (Entity (Lhs), True); - end if; - - -- Case where right side may be invalid in the sense of the RM - -- reference above. The RM does not require that we check for the - -- validity on an assignment, but it does require that the assignment - -- of an invalid value not cause erroneous behavior. - - -- The general approach in GNAT is to use the Is_Known_Valid flag - -- to avoid the need for validity checking on assignments. However - -- in some cases, we have to do validity checking in order to make - -- sure that the setting of this flag is correct. - - else - -- Validate right side if we are validating copies - - if Validity_Checks_On - and then Validity_Check_Copies - then - -- Skip this if left hand side is an array or record component - -- and elementary component validity checks are suppressed. - - if Nkind_In (Lhs, N_Selected_Component, N_Indexed_Component) - and then not Validity_Check_Components - then - null; - else - Ensure_Valid (Rhs); - end if; - - -- We can propagate this to the left side where appropriate - - if Is_Local_Variable_Reference (Lhs) - and then not Is_Known_Valid (Entity (Lhs)) - and then In_Unconditional_Context (N) - then - Set_Is_Known_Valid (Entity (Lhs), True); - end if; - - -- Otherwise check to see what should be done - - -- If left side is a local variable, then we just set its flag to - -- indicate that its value may no longer be valid, since we are - -- copying a potentially invalid value. - - elsif Is_Local_Variable_Reference (Lhs) then - Set_Is_Known_Valid (Entity (Lhs), False); - - -- Check for case of a nonlocal variable on the left side which - -- is currently known to be valid. In this case, we simply ensure - -- that the right side is valid. We only play the game of copying - -- validity status for local variables, since we are doing this - -- statically, not by tracing the full flow graph. - - elsif Is_Entity_Name (Lhs) - and then Is_Known_Valid (Entity (Lhs)) - then - -- Note: If Validity_Checking mode is set to none, we ignore - -- the Ensure_Valid call so don't worry about that case here. - - Ensure_Valid (Rhs); - - -- In all other cases, we can safely copy an invalid value without - -- worrying about the status of the left side. Since it is not a - -- variable reference it will not be considered - -- as being known to be valid in any case. - - else - null; - end if; - end if; - end if; - - -- Defend against invalid subscripts on left side if we are in standard - -- validity checking mode. No need to do this if we are checking all - -- subscripts. - - if Validity_Checks_On - and then Validity_Check_Default - and then not Validity_Check_Subscripts - then - Check_Valid_Lvalue_Subscripts (Lhs); - end if; - - exception - when RE_Not_Available => - return; - end Expand_N_Assignment_Statement; - - ------------------------------ - -- Expand_N_Block_Statement -- - ------------------------------ - - -- Encode entity names defined in block statement - - procedure Expand_N_Block_Statement (N : Node_Id) is - begin - Qualify_Entity_Names (N); - end Expand_N_Block_Statement; - - ----------------------------- - -- Expand_N_Case_Statement -- - ----------------------------- - - procedure Expand_N_Case_Statement (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Expr : constant Node_Id := Expression (N); - Alt : Node_Id; - Len : Nat; - Cond : Node_Id; - Choice : Node_Id; - Chlist : List_Id; - - begin - -- Check for the situation where we know at compile time which branch - -- will be taken - - if Compile_Time_Known_Value (Expr) then - Alt := Find_Static_Alternative (N); - - -- Move statements from this alternative after the case statement. - -- They are already analyzed, so will be skipped by the analyzer. - - Insert_List_After (N, Statements (Alt)); - - -- That leaves the case statement as a shell. So now we can kill all - -- other alternatives in the case statement. - - Kill_Dead_Code (Expression (N)); - - declare - A : Node_Id; - - begin - -- Loop through case alternatives, skipping pragmas, and skipping - -- the one alternative that we select (and therefore retain). - - A := First (Alternatives (N)); - while Present (A) loop - if A /= Alt - and then Nkind (A) = N_Case_Statement_Alternative - then - Kill_Dead_Code (Statements (A), Warn_On_Deleted_Code); - end if; - - Next (A); - end loop; - end; - - Rewrite (N, Make_Null_Statement (Loc)); - return; - end if; - - -- Here if the choice is not determined at compile time - - declare - Last_Alt : constant Node_Id := Last (Alternatives (N)); - - Others_Present : Boolean; - Others_Node : Node_Id; - - Then_Stms : List_Id; - Else_Stms : List_Id; - - begin - if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then - Others_Present := True; - Others_Node := Last_Alt; - else - Others_Present := False; - end if; - - -- First step is to worry about possible invalid argument. The RM - -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is - -- outside the base range), then Constraint_Error must be raised. - - -- Case of validity check required (validity checks are on, the - -- expression is not known to be valid, and the case statement - -- comes from source -- no need to validity check internally - -- generated case statements). - - if Validity_Check_Default then - Ensure_Valid (Expr); - end if; - - -- If there is only a single alternative, just replace it with the - -- sequence of statements since obviously that is what is going to - -- be executed in all cases. - - Len := List_Length (Alternatives (N)); - - if Len = 1 then - -- We still need to evaluate the expression if it has any - -- side effects. - - Remove_Side_Effects (Expression (N)); - - Insert_List_After (N, Statements (First (Alternatives (N)))); - - -- That leaves the case statement as a shell. The alternative that - -- will be executed is reset to a null list. So now we can kill - -- the entire case statement. - - Kill_Dead_Code (Expression (N)); - Rewrite (N, Make_Null_Statement (Loc)); - return; - end if; - - -- An optimization. If there are only two alternatives, and only - -- a single choice, then rewrite the whole case statement as an - -- if statement, since this can result in subsequent optimizations. - -- This helps not only with case statements in the source of a - -- simple form, but also with generated code (discriminant check - -- functions in particular) - - if Len = 2 then - Chlist := Discrete_Choices (First (Alternatives (N))); - - if List_Length (Chlist) = 1 then - Choice := First (Chlist); - - Then_Stms := Statements (First (Alternatives (N))); - Else_Stms := Statements (Last (Alternatives (N))); - - -- For TRUE, generate "expression", not expression = true - - if Nkind (Choice) = N_Identifier - and then Entity (Choice) = Standard_True - then - Cond := Expression (N); - - -- For FALSE, generate "expression" and switch then/else - - elsif Nkind (Choice) = N_Identifier - and then Entity (Choice) = Standard_False - then - Cond := Expression (N); - Else_Stms := Statements (First (Alternatives (N))); - Then_Stms := Statements (Last (Alternatives (N))); - - -- For a range, generate "expression in range" - - elsif Nkind (Choice) = N_Range - or else (Nkind (Choice) = N_Attribute_Reference - and then Attribute_Name (Choice) = Name_Range) - or else (Is_Entity_Name (Choice) - and then Is_Type (Entity (Choice))) - or else Nkind (Choice) = N_Subtype_Indication - then - Cond := - Make_In (Loc, - Left_Opnd => Expression (N), - Right_Opnd => Relocate_Node (Choice)); - - -- For any other subexpression "expression = value" - - else - Cond := - Make_Op_Eq (Loc, - Left_Opnd => Expression (N), - Right_Opnd => Relocate_Node (Choice)); - end if; - - -- Now rewrite the case as an IF - - Rewrite (N, - Make_If_Statement (Loc, - Condition => Cond, - Then_Statements => Then_Stms, - Else_Statements => Else_Stms)); - Analyze (N); - return; - end if; - end if; - - -- If the last alternative is not an Others choice, replace it with - -- an N_Others_Choice. Note that we do not bother to call Analyze on - -- the modified case statement, since it's only effect would be to - -- compute the contents of the Others_Discrete_Choices which is not - -- needed by the back end anyway. - - -- The reason we do this is that the back end always needs some - -- default for a switch, so if we have not supplied one in the - -- processing above for validity checking, then we need to supply - -- one here. - - if not Others_Present then - Others_Node := Make_Others_Choice (Sloc (Last_Alt)); - Set_Others_Discrete_Choices - (Others_Node, Discrete_Choices (Last_Alt)); - Set_Discrete_Choices (Last_Alt, New_List (Others_Node)); - end if; - end; - end Expand_N_Case_Statement; - - ----------------------------- - -- Expand_N_Exit_Statement -- - ----------------------------- - - -- The only processing required is to deal with a possible C/Fortran - -- boolean value used as the condition for the exit statement. - - procedure Expand_N_Exit_Statement (N : Node_Id) is - begin - Adjust_Condition (Condition (N)); - end Expand_N_Exit_Statement; - - ---------------------------------------- - -- Expand_N_Extended_Return_Statement -- - ---------------------------------------- - - -- If there is a Handled_Statement_Sequence, we rewrite this: - - -- return Result : T := <expression> do - -- <handled_seq_of_stms> - -- end return; - - -- to be: - - -- declare - -- Result : T := <expression>; - -- begin - -- <handled_seq_of_stms> - -- return Result; - -- end; - - -- Otherwise (no Handled_Statement_Sequence), we rewrite this: - - -- return Result : T := <expression>; - - -- to be: - - -- return <expression>; - - -- unless it's build-in-place or there's no <expression>, in which case - -- we generate: - - -- declare - -- Result : T := <expression>; - -- begin - -- return Result; - -- end; - - -- Note that this case could have been written by the user as an extended - -- return statement, or could have been transformed to this from a simple - -- return statement. - - -- That is, we need to have a reified return object if there are statements - -- (which might refer to it) or if we're doing build-in-place (so we can - -- set its address to the final resting place or if there is no expression - -- (in which case default initial values might need to be set). - - procedure Expand_N_Extended_Return_Statement (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - - Return_Object_Entity : constant Entity_Id := - First_Entity (Return_Statement_Entity (N)); - Return_Object_Decl : constant Node_Id := - Parent (Return_Object_Entity); - Parent_Function : constant Entity_Id := - Return_Applies_To (Return_Statement_Entity (N)); - Parent_Function_Typ : constant Entity_Id := Etype (Parent_Function); - Is_Build_In_Place : constant Boolean := - Is_Build_In_Place_Function (Parent_Function); - - Return_Stm : Node_Id; - Statements : List_Id; - Handled_Stm_Seq : Node_Id; - Result : Node_Id; - Exp : Node_Id; - - function Has_Controlled_Parts (Typ : Entity_Id) return Boolean; - -- Determine whether type Typ is controlled or contains a controlled - -- subcomponent. - - function Move_Activation_Chain return Node_Id; - -- Construct a call to System.Tasking.Stages.Move_Activation_Chain - -- with parameters: - -- From current activation chain - -- To activation chain passed in by the caller - -- New_Master master passed in by the caller - - function Move_Final_List return Node_Id; - -- Construct call to System.Finalization_Implementation.Move_Final_List - -- with parameters: - -- - -- From finalization list of the return statement - -- To finalization list passed in by the caller - - -------------------------- - -- Has_Controlled_Parts -- - -------------------------- - - function Has_Controlled_Parts (Typ : Entity_Id) return Boolean is - begin - return - Is_Controlled (Typ) - or else Has_Controlled_Component (Typ); - end Has_Controlled_Parts; - - --------------------------- - -- Move_Activation_Chain -- - --------------------------- - - function Move_Activation_Chain return Node_Id is - Activation_Chain_Formal : constant Entity_Id := - Build_In_Place_Formal - (Parent_Function, BIP_Activation_Chain); - To : constant Node_Id := - New_Reference_To - (Activation_Chain_Formal, Loc); - Master_Formal : constant Entity_Id := - Build_In_Place_Formal - (Parent_Function, BIP_Master); - New_Master : constant Node_Id := - New_Reference_To (Master_Formal, Loc); - - Chain_Entity : Entity_Id; - From : Node_Id; - - begin - Chain_Entity := First_Entity (Return_Statement_Entity (N)); - while Chars (Chain_Entity) /= Name_uChain loop - Chain_Entity := Next_Entity (Chain_Entity); - end loop; - - From := - Make_Attribute_Reference (Loc, - Prefix => New_Reference_To (Chain_Entity, Loc), - Attribute_Name => Name_Unrestricted_Access); - -- ??? Not clear why "Make_Identifier (Loc, Name_uChain)" doesn't - -- work, instead of "New_Reference_To (Chain_Entity, Loc)" above. - - return - Make_Procedure_Call_Statement (Loc, - Name => New_Reference_To (RTE (RE_Move_Activation_Chain), Loc), - Parameter_Associations => New_List (From, To, New_Master)); - end Move_Activation_Chain; - - --------------------- - -- Move_Final_List -- - --------------------- - - function Move_Final_List return Node_Id is - Flist : constant Entity_Id := - Finalization_Chain_Entity (Return_Statement_Entity (N)); - - From : constant Node_Id := New_Reference_To (Flist, Loc); - - Caller_Final_List : constant Entity_Id := - Build_In_Place_Formal - (Parent_Function, BIP_Final_List); - - To : constant Node_Id := New_Reference_To (Caller_Final_List, Loc); - - begin - -- Catch cases where a finalization chain entity has not been - -- associated with the return statement entity. - - pragma Assert (Present (Flist)); - - -- Build required call - - return - Make_If_Statement (Loc, - Condition => - Make_Op_Ne (Loc, - Left_Opnd => New_Copy (From), - Right_Opnd => New_Node (N_Null, Loc)), - Then_Statements => - New_List ( - Make_Procedure_Call_Statement (Loc, - Name => New_Reference_To (RTE (RE_Move_Final_List), Loc), - Parameter_Associations => New_List (From, To)))); - end Move_Final_List; - - -- Start of processing for Expand_N_Extended_Return_Statement - - begin - if Nkind (Return_Object_Decl) = N_Object_Declaration then - Exp := Expression (Return_Object_Decl); - else - Exp := Empty; - end if; - - Handled_Stm_Seq := Handled_Statement_Sequence (N); - - -- Build a simple_return_statement that returns the return object when - -- there is a statement sequence, or no expression, or the result will - -- be built in place. Note however that we currently do this for all - -- composite cases, even though nonlimited composite results are not yet - -- built in place (though we plan to do so eventually). - - if Present (Handled_Stm_Seq) - or else Is_Composite_Type (Etype (Parent_Function)) - or else No (Exp) - then - if No (Handled_Stm_Seq) then - Statements := New_List; - - -- If the extended return has a handled statement sequence, then wrap - -- it in a block and use the block as the first statement. - - else - Statements := - New_List (Make_Block_Statement (Loc, - Declarations => New_List, - Handled_Statement_Sequence => Handled_Stm_Seq)); - end if; - - -- If control gets past the above Statements, we have successfully - -- completed the return statement. If the result type has controlled - -- parts and the return is for a build-in-place function, then we - -- call Move_Final_List to transfer responsibility for finalization - -- of the return object to the caller. An alternative would be to - -- declare a Success flag in the function, initialize it to False, - -- and set it to True here. Then move the Move_Final_List call into - -- the cleanup code, and check Success. If Success then make a call - -- to Move_Final_List else do finalization. Then we can remove the - -- abort-deferral and the nulling-out of the From parameter from - -- Move_Final_List. Note that the current method is not quite correct - -- in the rather obscure case of a select-then-abort statement whose - -- abortable part contains the return statement. - - -- Check the type of the function to determine whether to move the - -- finalization list. A special case arises when processing a simple - -- return statement which has been rewritten as an extended return. - -- In that case check the type of the returned object or the original - -- expression. - - if Is_Build_In_Place - and then - (Has_Controlled_Parts (Parent_Function_Typ) - or else (Is_Class_Wide_Type (Parent_Function_Typ) - and then - Has_Controlled_Parts (Root_Type (Parent_Function_Typ))) - or else Has_Controlled_Parts (Etype (Return_Object_Entity)) - or else (Present (Exp) - and then Has_Controlled_Parts (Etype (Exp)))) - then - Append_To (Statements, Move_Final_List); - end if; - - -- Similarly to the above Move_Final_List, if the result type - -- contains tasks, we call Move_Activation_Chain. Later, the cleanup - -- code will call Complete_Master, which will terminate any - -- unactivated tasks belonging to the return statement master. But - -- Move_Activation_Chain updates their master to be that of the - -- caller, so they will not be terminated unless the return statement - -- completes unsuccessfully due to exception, abort, goto, or exit. - -- As a formality, we test whether the function requires the result - -- to be built in place, though that's necessarily true for the case - -- of result types with task parts. - - if Is_Build_In_Place and Has_Task (Etype (Parent_Function)) then - Append_To (Statements, Move_Activation_Chain); - end if; - - -- Build a simple_return_statement that returns the return object - - Return_Stm := - Make_Simple_Return_Statement (Loc, - Expression => New_Occurrence_Of (Return_Object_Entity, Loc)); - Append_To (Statements, Return_Stm); - - Handled_Stm_Seq := - Make_Handled_Sequence_Of_Statements (Loc, Statements); - end if; - - -- Case where we build a block - - if Present (Handled_Stm_Seq) then - Result := - Make_Block_Statement (Loc, - Declarations => Return_Object_Declarations (N), - Handled_Statement_Sequence => Handled_Stm_Seq); - - -- We set the entity of the new block statement to be that of the - -- return statement. This is necessary so that various fields, such - -- as Finalization_Chain_Entity carry over from the return statement - -- to the block. Note that this block is unusual, in that its entity - -- is an E_Return_Statement rather than an E_Block. - - Set_Identifier - (Result, New_Occurrence_Of (Return_Statement_Entity (N), Loc)); - - -- If the object decl was already rewritten as a renaming, then - -- we don't want to do the object allocation and transformation of - -- of the return object declaration to a renaming. This case occurs - -- when the return object is initialized by a call to another - -- build-in-place function, and that function is responsible for the - -- allocation of the return object. - - if Is_Build_In_Place - and then - Nkind (Return_Object_Decl) = N_Object_Renaming_Declaration - then - Set_By_Ref (Return_Stm); -- Return build-in-place results by ref - - elsif Is_Build_In_Place then - - -- Locate the implicit access parameter associated with the - -- caller-supplied return object and convert the return - -- statement's return object declaration to a renaming of a - -- dereference of the access parameter. If the return object's - -- declaration includes an expression that has not already been - -- expanded as separate assignments, then add an assignment - -- statement to ensure the return object gets initialized. - - -- declare - -- Result : T [:= <expression>]; - -- begin - -- ... - - -- is converted to - - -- declare - -- Result : T renames FuncRA.all; - -- [Result := <expression;] - -- begin - -- ... - - declare - Return_Obj_Id : constant Entity_Id := - Defining_Identifier (Return_Object_Decl); - Return_Obj_Typ : constant Entity_Id := Etype (Return_Obj_Id); - Return_Obj_Expr : constant Node_Id := - Expression (Return_Object_Decl); - Result_Subt : constant Entity_Id := - Etype (Parent_Function); - Constr_Result : constant Boolean := - Is_Constrained (Result_Subt); - Obj_Alloc_Formal : Entity_Id; - Object_Access : Entity_Id; - Obj_Acc_Deref : Node_Id; - Init_Assignment : Node_Id := Empty; - - begin - -- Build-in-place results must be returned by reference - - Set_By_Ref (Return_Stm); - - -- Retrieve the implicit access parameter passed by the caller - - Object_Access := - Build_In_Place_Formal (Parent_Function, BIP_Object_Access); - - -- If the return object's declaration includes an expression - -- and the declaration isn't marked as No_Initialization, then - -- we need to generate an assignment to the object and insert - -- it after the declaration before rewriting it as a renaming - -- (otherwise we'll lose the initialization). - - if Present (Return_Obj_Expr) - and then not No_Initialization (Return_Object_Decl) - then - Init_Assignment := - Make_Assignment_Statement (Loc, - Name => New_Reference_To (Return_Obj_Id, Loc), - Expression => Relocate_Node (Return_Obj_Expr)); - Set_Etype (Name (Init_Assignment), Etype (Return_Obj_Id)); - Set_Assignment_OK (Name (Init_Assignment)); - Set_No_Ctrl_Actions (Init_Assignment); - - Set_Parent (Name (Init_Assignment), Init_Assignment); - Set_Parent (Expression (Init_Assignment), Init_Assignment); - - Set_Expression (Return_Object_Decl, Empty); - - if Is_Class_Wide_Type (Etype (Return_Obj_Id)) - and then not Is_Class_Wide_Type - (Etype (Expression (Init_Assignment))) - then - Rewrite (Expression (Init_Assignment), - Make_Type_Conversion (Loc, - Subtype_Mark => - New_Occurrence_Of - (Etype (Return_Obj_Id), Loc), - Expression => - Relocate_Node (Expression (Init_Assignment)))); - end if; - - -- In the case of functions where the calling context can - -- determine the form of allocation needed, initialization - -- is done with each part of the if statement that handles - -- the different forms of allocation (this is true for - -- unconstrained and tagged result subtypes). - - if Constr_Result - and then not Is_Tagged_Type (Underlying_Type (Result_Subt)) - then - Insert_After (Return_Object_Decl, Init_Assignment); - end if; - end if; - - -- When the function's subtype is unconstrained, a run-time - -- test is needed to determine the form of allocation to use - -- for the return object. The function has an implicit formal - -- parameter indicating this. If the BIP_Alloc_Form formal has - -- the value one, then the caller has passed access to an - -- existing object for use as the return object. If the value - -- is two, then the return object must be allocated on the - -- secondary stack. Otherwise, the object must be allocated in - -- a storage pool (currently only supported for the global - -- heap, user-defined storage pools TBD ???). We generate an - -- if statement to test the implicit allocation formal and - -- initialize a local access value appropriately, creating - -- allocators in the secondary stack and global heap cases. - -- The special formal also exists and must be tested when the - -- function has a tagged result, even when the result subtype - -- is constrained, because in general such functions can be - -- called in dispatching contexts and must be handled similarly - -- to functions with a class-wide result. - - if not Constr_Result - or else Is_Tagged_Type (Underlying_Type (Result_Subt)) - then - Obj_Alloc_Formal := - Build_In_Place_Formal (Parent_Function, BIP_Alloc_Form); - - declare - Ref_Type : Entity_Id; - Ptr_Type_Decl : Node_Id; - Alloc_Obj_Id : Entity_Id; - Alloc_Obj_Decl : Node_Id; - Alloc_If_Stmt : Node_Id; - SS_Allocator : Node_Id; - Heap_Allocator : Node_Id; - - begin - -- Reuse the itype created for the function's implicit - -- access formal. This avoids the need to create a new - -- access type here, plus it allows assigning the access - -- formal directly without applying a conversion. - - -- Ref_Type := Etype (Object_Access); - - -- Create an access type designating the function's - -- result subtype. - - Ref_Type := - Make_Defining_Identifier (Loc, New_Internal_Name ('A')); - - Ptr_Type_Decl := - Make_Full_Type_Declaration (Loc, - Defining_Identifier => Ref_Type, - Type_Definition => - Make_Access_To_Object_Definition (Loc, - All_Present => True, - Subtype_Indication => - New_Reference_To (Return_Obj_Typ, Loc))); - - Insert_Before (Return_Object_Decl, Ptr_Type_Decl); - - -- Create an access object that will be initialized to an - -- access value denoting the return object, either coming - -- from an implicit access value passed in by the caller - -- or from the result of an allocator. - - Alloc_Obj_Id := - Make_Defining_Identifier (Loc, - Chars => New_Internal_Name ('R')); - Set_Etype (Alloc_Obj_Id, Ref_Type); - - Alloc_Obj_Decl := - Make_Object_Declaration (Loc, - Defining_Identifier => Alloc_Obj_Id, - Object_Definition => New_Reference_To - (Ref_Type, Loc)); - - Insert_Before (Return_Object_Decl, Alloc_Obj_Decl); - - -- Create allocators for both the secondary stack and - -- global heap. If there's an initialization expression, - -- then create these as initialized allocators. - - if Present (Return_Obj_Expr) - and then not No_Initialization (Return_Object_Decl) - then - Heap_Allocator := - Make_Allocator (Loc, - Expression => - Make_Qualified_Expression (Loc, - Subtype_Mark => - New_Reference_To (Return_Obj_Typ, Loc), - Expression => - New_Copy_Tree (Return_Obj_Expr))); - - SS_Allocator := New_Copy_Tree (Heap_Allocator); - - else - -- If the function returns a class-wide type we cannot - -- use the return type for the allocator. Instead we - -- use the type of the expression, which must be an - -- aggregate of a definite type. - - if Is_Class_Wide_Type (Return_Obj_Typ) then - Heap_Allocator := - Make_Allocator (Loc, - New_Reference_To - (Etype (Return_Obj_Expr), Loc)); - else - Heap_Allocator := - Make_Allocator (Loc, - New_Reference_To (Return_Obj_Typ, Loc)); - end if; - - -- If the object requires default initialization then - -- that will happen later following the elaboration of - -- the object renaming. If we don't turn it off here - -- then the object will be default initialized twice. - - Set_No_Initialization (Heap_Allocator); - - SS_Allocator := New_Copy_Tree (Heap_Allocator); - end if; - - -- If the No_Allocators restriction is active, then only - -- an allocator for secondary stack allocation is needed. - - if Restriction_Active (No_Allocators) then - SS_Allocator := Heap_Allocator; - Heap_Allocator := Make_Null (Loc); - - -- Otherwise the heap allocator may be needed, so we - -- make another allocator for secondary stack allocation. - - else - SS_Allocator := New_Copy_Tree (Heap_Allocator); - - -- The heap allocator is marked Comes_From_Source - -- since it corresponds to an explicit user-written - -- allocator (that is, it will only be executed on - -- behalf of callers that call the function as - -- initialization for such an allocator). This - -- prevents errors when No_Implicit_Heap_Allocation - -- is in force. - - Set_Comes_From_Source (Heap_Allocator, True); - end if; - - -- The allocator is returned on the secondary stack. We - -- don't do this on VM targets, since the SS is not used. - - if VM_Target = No_VM then - Set_Storage_Pool (SS_Allocator, RTE (RE_SS_Pool)); - Set_Procedure_To_Call - (SS_Allocator, RTE (RE_SS_Allocate)); - - -- The allocator is returned on the secondary stack, - -- so indicate that the function return, as well as - -- the block that encloses the allocator, must not - -- release it. The flags must be set now because the - -- decision to use the secondary stack is done very - -- late in the course of expanding the return - -- statement, past the point where these flags are - -- normally set. - - Set_Sec_Stack_Needed_For_Return (Parent_Function); - Set_Sec_Stack_Needed_For_Return - (Return_Statement_Entity (N)); - Set_Uses_Sec_Stack (Parent_Function); - Set_Uses_Sec_Stack (Return_Statement_Entity (N)); - end if; - - -- Create an if statement to test the BIP_Alloc_Form - -- formal and initialize the access object to either the - -- BIP_Object_Access formal (BIP_Alloc_Form = 0), the - -- result of allocating the object in the secondary stack - -- (BIP_Alloc_Form = 1), or else an allocator to create - -- the return object in the heap (BIP_Alloc_Form = 2). - - -- ??? An unchecked type conversion must be made in the - -- case of assigning the access object formal to the - -- local access object, because a normal conversion would - -- be illegal in some cases (such as converting access- - -- to-unconstrained to access-to-constrained), but the - -- the unchecked conversion will presumably fail to work - -- right in just such cases. It's not clear at all how to - -- handle this. ??? - - Alloc_If_Stmt := - Make_If_Statement (Loc, - Condition => - Make_Op_Eq (Loc, - Left_Opnd => - New_Reference_To (Obj_Alloc_Formal, Loc), - Right_Opnd => - Make_Integer_Literal (Loc, - UI_From_Int (BIP_Allocation_Form'Pos - (Caller_Allocation)))), - Then_Statements => - New_List (Make_Assignment_Statement (Loc, - Name => - New_Reference_To - (Alloc_Obj_Id, Loc), - Expression => - Make_Unchecked_Type_Conversion (Loc, - Subtype_Mark => - New_Reference_To (Ref_Type, Loc), - Expression => - New_Reference_To - (Object_Access, Loc)))), - Elsif_Parts => - New_List (Make_Elsif_Part (Loc, - Condition => - Make_Op_Eq (Loc, - Left_Opnd => - New_Reference_To - (Obj_Alloc_Formal, Loc), - Right_Opnd => - Make_Integer_Literal (Loc, - UI_From_Int ( - BIP_Allocation_Form'Pos - (Secondary_Stack)))), - Then_Statements => - New_List - (Make_Assignment_Statement (Loc, - Name => - New_Reference_To - (Alloc_Obj_Id, Loc), - Expression => - SS_Allocator)))), - Else_Statements => - New_List (Make_Assignment_Statement (Loc, - Name => - New_Reference_To - (Alloc_Obj_Id, Loc), - Expression => - Heap_Allocator))); - - -- If a separate initialization assignment was created - -- earlier, append that following the assignment of the - -- implicit access formal to the access object, to ensure - -- that the return object is initialized in that case. - -- In this situation, the target of the assignment must - -- be rewritten to denote a dereference of the access to - -- the return object passed in by the caller. - - if Present (Init_Assignment) then - Rewrite (Name (Init_Assignment), - Make_Explicit_Dereference (Loc, - Prefix => New_Reference_To (Alloc_Obj_Id, Loc))); - Set_Etype - (Name (Init_Assignment), Etype (Return_Obj_Id)); - - Append_To - (Then_Statements (Alloc_If_Stmt), - Init_Assignment); - end if; - - Insert_Before (Return_Object_Decl, Alloc_If_Stmt); - - -- Remember the local access object for use in the - -- dereference of the renaming created below. - - Object_Access := Alloc_Obj_Id; - end; - end if; - - -- Replace the return object declaration with a renaming of a - -- dereference of the access value designating the return - -- object. - - Obj_Acc_Deref := - Make_Explicit_Dereference (Loc, - Prefix => New_Reference_To (Object_Access, Loc)); - - Rewrite (Return_Object_Decl, - Make_Object_Renaming_Declaration (Loc, - Defining_Identifier => Return_Obj_Id, - Access_Definition => Empty, - Subtype_Mark => New_Occurrence_Of - (Return_Obj_Typ, Loc), - Name => Obj_Acc_Deref)); - - Set_Renamed_Object (Return_Obj_Id, Obj_Acc_Deref); - end; - end if; - - -- Case where we do not build a block - - else - -- We're about to drop Return_Object_Declarations on the floor, so - -- we need to insert it, in case it got expanded into useful code. - - Insert_List_Before (N, Return_Object_Declarations (N)); - - -- Build simple_return_statement that returns the expression directly - - Return_Stm := Make_Simple_Return_Statement (Loc, Expression => Exp); - - Result := Return_Stm; - end if; - - -- Set the flag to prevent infinite recursion - - Set_Comes_From_Extended_Return_Statement (Return_Stm); - - Rewrite (N, Result); - Analyze (N); - end Expand_N_Extended_Return_Statement; - - ----------------------------- - -- Expand_N_Goto_Statement -- - ----------------------------- - - -- Add poll before goto if polling active - - procedure Expand_N_Goto_Statement (N : Node_Id) is - begin - Generate_Poll_Call (N); - end Expand_N_Goto_Statement; - - --------------------------- - -- Expand_N_If_Statement -- - --------------------------- - - -- First we deal with the case of C and Fortran convention boolean values, - -- with zero/non-zero semantics. - - -- Second, we deal with the obvious rewriting for the cases where the - -- condition of the IF is known at compile time to be True or False. - - -- Third, we remove elsif parts which have non-empty Condition_Actions - -- and rewrite as independent if statements. For example: - - -- if x then xs - -- elsif y then ys - -- ... - -- end if; - - -- becomes - -- - -- if x then xs - -- else - -- <<condition actions of y>> - -- if y then ys - -- ... - -- end if; - -- end if; - - -- This rewriting is needed if at least one elsif part has a non-empty - -- Condition_Actions list. We also do the same processing if there is a - -- constant condition in an elsif part (in conjunction with the first - -- processing step mentioned above, for the recursive call made to deal - -- with the created inner if, this deals with properly optimizing the - -- cases of constant elsif conditions). - - procedure Expand_N_If_Statement (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Hed : Node_Id; - E : Node_Id; - New_If : Node_Id; - - Warn_If_Deleted : constant Boolean := - Warn_On_Deleted_Code and then Comes_From_Source (N); - -- Indicates whether we want warnings when we delete branches of the - -- if statement based on constant condition analysis. We never want - -- these warnings for expander generated code. - - begin - Adjust_Condition (Condition (N)); - - -- The following loop deals with constant conditions for the IF. We - -- need a loop because as we eliminate False conditions, we grab the - -- first elsif condition and use it as the primary condition. - - while Compile_Time_Known_Value (Condition (N)) loop - - -- If condition is True, we can simply rewrite the if statement now - -- by replacing it by the series of then statements. - - if Is_True (Expr_Value (Condition (N))) then - - -- All the else parts can be killed - - Kill_Dead_Code (Elsif_Parts (N), Warn_If_Deleted); - Kill_Dead_Code (Else_Statements (N), Warn_If_Deleted); - - Hed := Remove_Head (Then_Statements (N)); - Insert_List_After (N, Then_Statements (N)); - Rewrite (N, Hed); - return; - - -- If condition is False, then we can delete the condition and - -- the Then statements - - else - -- We do not delete the condition if constant condition warnings - -- are enabled, since otherwise we end up deleting the desired - -- warning. Of course the backend will get rid of this True/False - -- test anyway, so nothing is lost here. - - if not Constant_Condition_Warnings then - Kill_Dead_Code (Condition (N)); - end if; - - Kill_Dead_Code (Then_Statements (N), Warn_If_Deleted); - - -- If there are no elsif statements, then we simply replace the - -- entire if statement by the sequence of else statements. - - if No (Elsif_Parts (N)) then - if No (Else_Statements (N)) - or else Is_Empty_List (Else_Statements (N)) - then - Rewrite (N, - Make_Null_Statement (Sloc (N))); - else - Hed := Remove_Head (Else_Statements (N)); - Insert_List_After (N, Else_Statements (N)); - Rewrite (N, Hed); - end if; - - return; - - -- If there are elsif statements, the first of them becomes the - -- if/then section of the rebuilt if statement This is the case - -- where we loop to reprocess this copied condition. - - else - Hed := Remove_Head (Elsif_Parts (N)); - Insert_Actions (N, Condition_Actions (Hed)); - Set_Condition (N, Condition (Hed)); - Set_Then_Statements (N, Then_Statements (Hed)); - - -- Hed might have been captured as the condition determining - -- the current value for an entity. Now it is detached from - -- the tree, so a Current_Value pointer in the condition might - -- need to be updated. - - Set_Current_Value_Condition (N); - - if Is_Empty_List (Elsif_Parts (N)) then - Set_Elsif_Parts (N, No_List); - end if; - end if; - end if; - end loop; - - -- Loop through elsif parts, dealing with constant conditions and - -- possible expression actions that are present. - - if Present (Elsif_Parts (N)) then - E := First (Elsif_Parts (N)); - while Present (E) loop - Adjust_Condition (Condition (E)); - - -- If there are condition actions, then rewrite the if statement - -- as indicated above. We also do the same rewrite for a True or - -- False condition. The further processing of this constant - -- condition is then done by the recursive call to expand the - -- newly created if statement - - if Present (Condition_Actions (E)) - or else Compile_Time_Known_Value (Condition (E)) - then - -- Note this is not an implicit if statement, since it is part - -- of an explicit if statement in the source (or of an implicit - -- if statement that has already been tested). - - New_If := - Make_If_Statement (Sloc (E), - Condition => Condition (E), - Then_Statements => Then_Statements (E), - Elsif_Parts => No_List, - Else_Statements => Else_Statements (N)); - - -- Elsif parts for new if come from remaining elsif's of parent - - while Present (Next (E)) loop - if No (Elsif_Parts (New_If)) then - Set_Elsif_Parts (New_If, New_List); - end if; - - Append (Remove_Next (E), Elsif_Parts (New_If)); - end loop; - - Set_Else_Statements (N, New_List (New_If)); - - if Present (Condition_Actions (E)) then - Insert_List_Before (New_If, Condition_Actions (E)); - end if; - - Remove (E); - - if Is_Empty_List (Elsif_Parts (N)) then - Set_Elsif_Parts (N, No_List); - end if; - - Analyze (New_If); - return; - - -- No special processing for that elsif part, move to next - - else - Next (E); - end if; - end loop; - end if; - - -- Some more optimizations applicable if we still have an IF statement - - if Nkind (N) /= N_If_Statement then - return; - end if; - - -- Another optimization, special cases that can be simplified - - -- if expression then - -- return true; - -- else - -- return false; - -- end if; - - -- can be changed to: - - -- return expression; - - -- and - - -- if expression then - -- return false; - -- else - -- return true; - -- end if; - - -- can be changed to: - - -- return not (expression); - - -- Only do these optimizations if we are at least at -O1 level - - if Optimization_Level > 0 then - if Nkind (N) = N_If_Statement - and then No (Elsif_Parts (N)) - and then Present (Else_Statements (N)) - and then List_Length (Then_Statements (N)) = 1 - and then List_Length (Else_Statements (N)) = 1 - then - declare - Then_Stm : constant Node_Id := First (Then_Statements (N)); - Else_Stm : constant Node_Id := First (Else_Statements (N)); - - begin - if Nkind (Then_Stm) = N_Simple_Return_Statement - and then - Nkind (Else_Stm) = N_Simple_Return_Statement - then - declare - Then_Expr : constant Node_Id := Expression (Then_Stm); - Else_Expr : constant Node_Id := Expression (Else_Stm); - - begin - if Nkind (Then_Expr) = N_Identifier - and then - Nkind (Else_Expr) = N_Identifier - then - if Entity (Then_Expr) = Standard_True - and then Entity (Else_Expr) = Standard_False - then - Rewrite (N, - Make_Simple_Return_Statement (Loc, - Expression => Relocate_Node (Condition (N)))); - Analyze (N); - return; - - elsif Entity (Then_Expr) = Standard_False - and then Entity (Else_Expr) = Standard_True - then - Rewrite (N, - Make_Simple_Return_Statement (Loc, - Expression => - Make_Op_Not (Loc, - Right_Opnd => - Relocate_Node (Condition (N))))); - Analyze (N); - return; - end if; - end if; - end; - end if; - end; - end if; - end if; - end Expand_N_If_Statement; - - ----------------------------- - -- Expand_N_Loop_Statement -- - ----------------------------- - - -- 1. Deal with while condition for C/Fortran boolean - -- 2. Deal with loops with a non-standard enumeration type range - -- 3. Deal with while loops where Condition_Actions is set - -- 4. Insert polling call if required - - procedure Expand_N_Loop_Statement (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Isc : constant Node_Id := Iteration_Scheme (N); - - begin - if Present (Isc) then - Adjust_Condition (Condition (Isc)); - end if; - - if Is_Non_Empty_List (Statements (N)) then - Generate_Poll_Call (First (Statements (N))); - end if; - - -- Nothing more to do for plain loop with no iteration scheme - - if No (Isc) then - return; - end if; - - -- Note: we do not have to worry about validity checking of the for loop - -- range bounds here, since they were frozen with constant declarations - -- and it is during that process that the validity checking is done. - - -- Handle the case where we have a for loop with the range type being an - -- enumeration type with non-standard representation. In this case we - -- expand: - - -- for x in [reverse] a .. b loop - -- ... - -- end loop; - - -- to - - -- for xP in [reverse] integer - -- range etype'Pos (a) .. etype'Pos (b) loop - -- declare - -- x : constant etype := Pos_To_Rep (xP); - -- begin - -- ... - -- end; - -- end loop; - - if Present (Loop_Parameter_Specification (Isc)) then - declare - LPS : constant Node_Id := Loop_Parameter_Specification (Isc); - Loop_Id : constant Entity_Id := Defining_Identifier (LPS); - Ltype : constant Entity_Id := Etype (Loop_Id); - Btype : constant Entity_Id := Base_Type (Ltype); - Expr : Node_Id; - New_Id : Entity_Id; - - begin - if not Is_Enumeration_Type (Btype) - or else No (Enum_Pos_To_Rep (Btype)) - then - return; - end if; - - New_Id := - Make_Defining_Identifier (Loc, - Chars => New_External_Name (Chars (Loop_Id), 'P')); - - -- If the type has a contiguous representation, successive values - -- can be generated as offsets from the first literal. - - if Has_Contiguous_Rep (Btype) then - Expr := - Unchecked_Convert_To (Btype, - Make_Op_Add (Loc, - Left_Opnd => - Make_Integer_Literal (Loc, - Enumeration_Rep (First_Literal (Btype))), - Right_Opnd => New_Reference_To (New_Id, Loc))); - else - -- Use the constructed array Enum_Pos_To_Rep - - Expr := - Make_Indexed_Component (Loc, - Prefix => New_Reference_To (Enum_Pos_To_Rep (Btype), Loc), - Expressions => New_List (New_Reference_To (New_Id, Loc))); - end if; - - Rewrite (N, - Make_Loop_Statement (Loc, - Identifier => Identifier (N), - - Iteration_Scheme => - Make_Iteration_Scheme (Loc, - Loop_Parameter_Specification => - Make_Loop_Parameter_Specification (Loc, - Defining_Identifier => New_Id, - Reverse_Present => Reverse_Present (LPS), - - Discrete_Subtype_Definition => - Make_Subtype_Indication (Loc, - - Subtype_Mark => - New_Reference_To (Standard_Natural, Loc), - - Constraint => - Make_Range_Constraint (Loc, - Range_Expression => - Make_Range (Loc, - - Low_Bound => - Make_Attribute_Reference (Loc, - Prefix => - New_Reference_To (Btype, Loc), - - Attribute_Name => Name_Pos, - - Expressions => New_List ( - Relocate_Node - (Type_Low_Bound (Ltype)))), - - High_Bound => - Make_Attribute_Reference (Loc, - Prefix => - New_Reference_To (Btype, Loc), - - Attribute_Name => Name_Pos, - - Expressions => New_List ( - Relocate_Node - (Type_High_Bound (Ltype))))))))), - - Statements => New_List ( - Make_Block_Statement (Loc, - Declarations => New_List ( - Make_Object_Declaration (Loc, - Defining_Identifier => Loop_Id, - Constant_Present => True, - Object_Definition => New_Reference_To (Ltype, Loc), - Expression => Expr)), - - Handled_Statement_Sequence => - Make_Handled_Sequence_Of_Statements (Loc, - Statements => Statements (N)))), - - End_Label => End_Label (N))); - Analyze (N); - end; - - -- Second case, if we have a while loop with Condition_Actions set, then - -- we change it into a plain loop: - - -- while C loop - -- ... - -- end loop; - - -- changed to: - - -- loop - -- <<condition actions>> - -- exit when not C; - -- ... - -- end loop - - elsif Present (Isc) - and then Present (Condition_Actions (Isc)) - then - declare - ES : Node_Id; - - begin - ES := - Make_Exit_Statement (Sloc (Condition (Isc)), - Condition => - Make_Op_Not (Sloc (Condition (Isc)), - Right_Opnd => Condition (Isc))); - - Prepend (ES, Statements (N)); - Insert_List_Before (ES, Condition_Actions (Isc)); - - -- This is not an implicit loop, since it is generated in response - -- to the loop statement being processed. If this is itself - -- implicit, the restriction has already been checked. If not, - -- it is an explicit loop. - - Rewrite (N, - Make_Loop_Statement (Sloc (N), - Identifier => Identifier (N), - Statements => Statements (N), - End_Label => End_Label (N))); - - Analyze (N); - end; - end if; - end Expand_N_Loop_Statement; - - -------------------------------------- - -- Expand_N_Simple_Return_Statement -- - -------------------------------------- - - procedure Expand_N_Simple_Return_Statement (N : Node_Id) is - begin - -- Defend against previous errors (i.e. the return statement calls a - -- function that is not available in configurable runtime). - - if Present (Expression (N)) - and then Nkind (Expression (N)) = N_Empty - then - return; - end if; - - -- Distinguish the function and non-function cases: - - case Ekind (Return_Applies_To (Return_Statement_Entity (N))) is - - when E_Function | - E_Generic_Function => - Expand_Simple_Function_Return (N); - - when E_Procedure | - E_Generic_Procedure | - E_Entry | - E_Entry_Family | - E_Return_Statement => - Expand_Non_Function_Return (N); - - when others => - raise Program_Error; - end case; - - exception - when RE_Not_Available => - return; - end Expand_N_Simple_Return_Statement; - - -------------------------------- - -- Expand_Non_Function_Return -- - -------------------------------- - - procedure Expand_Non_Function_Return (N : Node_Id) is - pragma Assert (No (Expression (N))); - - Loc : constant Source_Ptr := Sloc (N); - Scope_Id : Entity_Id := - Return_Applies_To (Return_Statement_Entity (N)); - Kind : constant Entity_Kind := Ekind (Scope_Id); - Call : Node_Id; - Acc_Stat : Node_Id; - Goto_Stat : Node_Id; - Lab_Node : Node_Id; - - begin - -- Call postconditions procedure if procedure with active postconditions - - if Ekind (Scope_Id) = E_Procedure - and then Has_Postconditions (Scope_Id) - then - Insert_Action (N, - Make_Procedure_Call_Statement (Loc, - Name => Make_Identifier (Loc, Name_uPostconditions))); - end if; - - -- If it is a return from a procedure do no extra steps - - if Kind = E_Procedure or else Kind = E_Generic_Procedure then - return; - - -- If it is a nested return within an extended one, replace it with a - -- return of the previously declared return object. - - elsif Kind = E_Return_Statement then - Rewrite (N, - Make_Simple_Return_Statement (Loc, - Expression => - New_Occurrence_Of (First_Entity (Scope_Id), Loc))); - Set_Comes_From_Extended_Return_Statement (N); - Set_Return_Statement_Entity (N, Scope_Id); - Expand_Simple_Function_Return (N); - return; - end if; - - pragma Assert (Is_Entry (Scope_Id)); - - -- Look at the enclosing block to see whether the return is from an - -- accept statement or an entry body. - - for J in reverse 0 .. Scope_Stack.Last loop - Scope_Id := Scope_Stack.Table (J).Entity; - exit when Is_Concurrent_Type (Scope_Id); - end loop; - - -- If it is a return from accept statement it is expanded as call to - -- RTS Complete_Rendezvous and a goto to the end of the accept body. - - -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept, - -- Expand_N_Accept_Alternative in exp_ch9.adb) - - if Is_Task_Type (Scope_Id) then - - Call := - Make_Procedure_Call_Statement (Loc, - Name => New_Reference_To - (RTE (RE_Complete_Rendezvous), Loc)); - Insert_Before (N, Call); - -- why not insert actions here??? - Analyze (Call); - - Acc_Stat := Parent (N); - while Nkind (Acc_Stat) /= N_Accept_Statement loop - Acc_Stat := Parent (Acc_Stat); - end loop; - - Lab_Node := Last (Statements - (Handled_Statement_Sequence (Acc_Stat))); - - Goto_Stat := Make_Goto_Statement (Loc, - Name => New_Occurrence_Of - (Entity (Identifier (Lab_Node)), Loc)); - - Set_Analyzed (Goto_Stat); - - Rewrite (N, Goto_Stat); - Analyze (N); - - -- If it is a return from an entry body, put a Complete_Entry_Body call - -- in front of the return. - - elsif Is_Protected_Type (Scope_Id) then - Call := - Make_Procedure_Call_Statement (Loc, - Name => - New_Reference_To (RTE (RE_Complete_Entry_Body), Loc), - Parameter_Associations => New_List ( - Make_Attribute_Reference (Loc, - Prefix => - New_Reference_To - (Find_Protection_Object (Current_Scope), Loc), - Attribute_Name => - Name_Unchecked_Access))); - - Insert_Before (N, Call); - Analyze (Call); - end if; - end Expand_Non_Function_Return; - - ----------------------------------- - -- Expand_Simple_Function_Return -- - ----------------------------------- - - -- The "simple" comes from the syntax rule simple_return_statement. - -- The semantics are not at all simple! - - procedure Expand_Simple_Function_Return (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - - Scope_Id : constant Entity_Id := - Return_Applies_To (Return_Statement_Entity (N)); - -- The function we are returning from - - R_Type : constant Entity_Id := Etype (Scope_Id); - -- The result type of the function - - Utyp : constant Entity_Id := Underlying_Type (R_Type); - - Exp : constant Node_Id := Expression (N); - pragma Assert (Present (Exp)); - - Exptyp : constant Entity_Id := Etype (Exp); - -- The type of the expression (not necessarily the same as R_Type) - - Subtype_Ind : Node_Id; - -- If the result type of the function is class-wide and the - -- expression has a specific type, then we use the expression's - -- type as the type of the return object. In cases where the - -- expression is an aggregate that is built in place, this avoids - -- the need for an expensive conversion of the return object to - -- the specific type on assignments to the individual components. - - begin - if Is_Class_Wide_Type (R_Type) - and then not Is_Class_Wide_Type (Etype (Exp)) - then - Subtype_Ind := New_Occurrence_Of (Etype (Exp), Loc); - else - Subtype_Ind := New_Occurrence_Of (R_Type, Loc); - end if; - - -- For the case of a simple return that does not come from an extended - -- return, in the case of Ada 2005 where we are returning a limited - -- type, we rewrite "return <expression>;" to be: - - -- return _anon_ : <return_subtype> := <expression> - - -- The expansion produced by Expand_N_Extended_Return_Statement will - -- contain simple return statements (for example, a block containing - -- simple return of the return object), which brings us back here with - -- Comes_From_Extended_Return_Statement set. The reason for the barrier - -- checking for a simple return that does not come from an extended - -- return is to avoid this infinite recursion. - - -- The reason for this design is that for Ada 2005 limited returns, we - -- need to reify the return object, so we can build it "in place", and - -- we need a block statement to hang finalization and tasking stuff. - - -- ??? In order to avoid disruption, we avoid translating to extended - -- return except in the cases where we really need to (Ada 2005 for - -- inherently limited). We might prefer to do this translation in all - -- cases (except perhaps for the case of Ada 95 inherently limited), - -- in order to fully exercise the Expand_N_Extended_Return_Statement - -- code. This would also allow us to do the build-in-place optimization - -- for efficiency even in cases where it is semantically not required. - - -- As before, we check the type of the return expression rather than the - -- return type of the function, because the latter may be a limited - -- class-wide interface type, which is not a limited type, even though - -- the type of the expression may be. - - if not Comes_From_Extended_Return_Statement (N) - and then Is_Inherently_Limited_Type (Etype (Expression (N))) - and then Ada_Version >= Ada_05 - and then not Debug_Flag_Dot_L - then - declare - Return_Object_Entity : constant Entity_Id := - Make_Defining_Identifier (Loc, - New_Internal_Name ('R')); - Obj_Decl : constant Node_Id := - Make_Object_Declaration (Loc, - Defining_Identifier => Return_Object_Entity, - Object_Definition => Subtype_Ind, - Expression => Exp); - - Ext : constant Node_Id := Make_Extended_Return_Statement (Loc, - Return_Object_Declarations => New_List (Obj_Decl)); - -- Do not perform this high-level optimization if the result type - -- is an interface because the "this" pointer must be displaced. - - begin - Rewrite (N, Ext); - Analyze (N); - return; - end; - end if; - - -- Here we have a simple return statement that is part of the expansion - -- of an extended return statement (either written by the user, or - -- generated by the above code). - - -- Always normalize C/Fortran boolean result. This is not always needed, - -- but it seems a good idea to minimize the passing around of non- - -- normalized values, and in any case this handles the processing of - -- barrier functions for protected types, which turn the condition into - -- a return statement. - - if Is_Boolean_Type (Exptyp) - and then Nonzero_Is_True (Exptyp) - then - Adjust_Condition (Exp); - Adjust_Result_Type (Exp, Exptyp); - end if; - - -- Do validity check if enabled for returns - - if Validity_Checks_On - and then Validity_Check_Returns - then - Ensure_Valid (Exp); - end if; - - -- Check the result expression of a scalar function against the subtype - -- of the function by inserting a conversion. This conversion must - -- eventually be performed for other classes of types, but for now it's - -- only done for scalars. - -- ??? - - if Is_Scalar_Type (Exptyp) then - Rewrite (Exp, Convert_To (R_Type, Exp)); - Analyze (Exp); - end if; - - -- Deal with returning variable length objects and controlled types - - -- Nothing to do if we are returning by reference, or this is not a - -- type that requires special processing (indicated by the fact that - -- it requires a cleanup scope for the secondary stack case). - - if Is_Inherently_Limited_Type (Exptyp) - or else Is_Limited_Interface (Exptyp) - then - null; - - elsif not Requires_Transient_Scope (R_Type) then - - -- Mutable records with no variable length components are not - -- returned on the sec-stack, so we need to make sure that the - -- backend will only copy back the size of the actual value, and not - -- the maximum size. We create an actual subtype for this purpose. - - declare - Ubt : constant Entity_Id := Underlying_Type (Base_Type (Exptyp)); - Decl : Node_Id; - Ent : Entity_Id; - begin - if Has_Discriminants (Ubt) - and then not Is_Constrained (Ubt) - and then not Has_Unchecked_Union (Ubt) - then - Decl := Build_Actual_Subtype (Ubt, Exp); - Ent := Defining_Identifier (Decl); - Insert_Action (Exp, Decl); - Rewrite (Exp, Unchecked_Convert_To (Ent, Exp)); - Analyze_And_Resolve (Exp); - end if; - end; - - -- Here if secondary stack is used - - else - -- Make sure that no surrounding block will reclaim the secondary - -- stack on which we are going to put the result. Not only may this - -- introduce secondary stack leaks but worse, if the reclamation is - -- done too early, then the result we are returning may get - -- clobbered. - - declare - S : Entity_Id; - begin - S := Current_Scope; - while Ekind (S) = E_Block or else Ekind (S) = E_Loop loop - Set_Sec_Stack_Needed_For_Return (S, True); - S := Enclosing_Dynamic_Scope (S); - end loop; - end; - - -- Optimize the case where the result is a function call. In this - -- case either the result is already on the secondary stack, or is - -- already being returned with the stack pointer depressed and no - -- further processing is required except to set the By_Ref flag to - -- ensure that gigi does not attempt an extra unnecessary copy. - -- (actually not just unnecessary but harmfully wrong in the case - -- of a controlled type, where gigi does not know how to do a copy). - -- To make up for a gcc 2.8.1 deficiency (???), we perform - -- the copy for array types if the constrained status of the - -- target type is different from that of the expression. - - if Requires_Transient_Scope (Exptyp) - and then - (not Is_Array_Type (Exptyp) - or else Is_Constrained (Exptyp) = Is_Constrained (R_Type) - or else CW_Or_Has_Controlled_Part (Utyp)) - and then Nkind (Exp) = N_Function_Call - then - Set_By_Ref (N); - - -- Remove side effects from the expression now so that other parts - -- of the expander do not have to reanalyze this node without this - -- optimization - - Rewrite (Exp, Duplicate_Subexpr_No_Checks (Exp)); - - -- For controlled types, do the allocation on the secondary stack - -- manually in order to call adjust at the right time: - - -- type Anon1 is access R_Type; - -- for Anon1'Storage_pool use ss_pool; - -- Anon2 : anon1 := new R_Type'(expr); - -- return Anon2.all; - - -- We do the same for classwide types that are not potentially - -- controlled (by the virtue of restriction No_Finalization) because - -- gigi is not able to properly allocate class-wide types. - - elsif CW_Or_Has_Controlled_Part (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))); - - -- We do not want discriminant checks on the declaration, - -- given that it gets its value from the allocator. - - Set_No_Initialization (Alloc_Node); - - 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 => Subtype_Ind)), - - Make_Object_Declaration (Loc, - Defining_Identifier => Temp, - Object_Definition => New_Reference_To (Acc_Typ, Loc), - Expression => Alloc_Node))); - - Rewrite (Exp, - Make_Explicit_Dereference (Loc, - Prefix => New_Reference_To (Temp, Loc))); - - Analyze_And_Resolve (Exp, R_Type); - end; - - -- Otherwise use the gigi mechanism to allocate result on the - -- secondary stack. - - else - Check_Restriction (No_Secondary_Stack, N); - Set_Storage_Pool (N, RTE (RE_SS_Pool)); - - -- If we are generating code for the VM do not use - -- SS_Allocate since everything is heap-allocated anyway. - - if VM_Target = No_VM then - Set_Procedure_To_Call (N, RTE (RE_SS_Allocate)); - end if; - end if; - end if; - - -- Implement the rules of 6.5(8-10), which require a tag check in the - -- case of a limited tagged return type, and tag reassignment for - -- nonlimited tagged results. These actions are needed when the return - -- type is a specific tagged type and the result expression is a - -- conversion or a formal parameter, because in that case the tag of the - -- expression might differ from the tag of the specific result type. - - if Is_Tagged_Type (Utyp) - and then not Is_Class_Wide_Type (Utyp) - and then (Nkind_In (Exp, N_Type_Conversion, - N_Unchecked_Type_Conversion) - or else (Is_Entity_Name (Exp) - and then Ekind (Entity (Exp)) in Formal_Kind)) - then - -- When the return type is limited, perform a check that the - -- tag of the result is the same as the tag of the return type. - - if Is_Limited_Type (R_Type) then - Insert_Action (Exp, - Make_Raise_Constraint_Error (Loc, - Condition => - Make_Op_Ne (Loc, - Left_Opnd => - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr (Exp), - Selector_Name => - New_Reference_To (First_Tag_Component (Utyp), Loc)), - Right_Opnd => - Unchecked_Convert_To (RTE (RE_Tag), - New_Reference_To - (Node (First_Elmt - (Access_Disp_Table (Base_Type (Utyp)))), - Loc))), - Reason => CE_Tag_Check_Failed)); - - -- If the result type is a specific nonlimited tagged type, then we - -- have to ensure that the tag of the result is that of the result - -- type. This is handled by making a copy of the expression in the - -- case where it might have a different tag, namely when the - -- expression is a conversion or a formal parameter. We create a new - -- object of the result type and initialize it from the expression, - -- which will implicitly force the tag to be set appropriately. - - else - declare - Result_Id : constant Entity_Id := - Make_Defining_Identifier (Loc, - Chars => New_Internal_Name ('R')); - Result_Exp : constant Node_Id := - New_Reference_To (Result_Id, Loc); - Result_Obj : constant Node_Id := - Make_Object_Declaration (Loc, - Defining_Identifier => Result_Id, - Object_Definition => - New_Reference_To (R_Type, Loc), - Constant_Present => True, - Expression => Relocate_Node (Exp)); - - begin - Set_Assignment_OK (Result_Obj); - Insert_Action (Exp, Result_Obj); - - Rewrite (Exp, Result_Exp); - Analyze_And_Resolve (Exp, R_Type); - end; - end if; - - -- Ada 2005 (AI-344): If the result type is class-wide, then insert - -- a check that the level of the return expression's underlying type - -- is not deeper than the level of the master enclosing the function. - -- Always generate the check when the type of the return expression - -- is class-wide, when it's a type conversion, or when it's a formal - -- parameter. Otherwise, suppress the check in the case where the - -- return expression has a specific type whose level is known not to - -- be statically deeper than the function's result type. - - -- Note: accessibility check is skipped in the VM case, since there - -- does not seem to be any practical way to implement this check. - - elsif Ada_Version >= Ada_05 - and then VM_Target = No_VM - and then Is_Class_Wide_Type (R_Type) - and then not Scope_Suppress (Accessibility_Check) - and then - (Is_Class_Wide_Type (Etype (Exp)) - or else Nkind_In (Exp, N_Type_Conversion, - N_Unchecked_Type_Conversion) - or else (Is_Entity_Name (Exp) - and then Ekind (Entity (Exp)) in Formal_Kind) - or else Scope_Depth (Enclosing_Dynamic_Scope (Etype (Exp))) > - Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id))) - then - declare - Tag_Node : Node_Id; - - begin - -- Ada 2005 (AI-251): In class-wide interface objects we displace - -- "this" to reference the base of the object --- required to get - -- access to the TSD of the object. - - if Is_Class_Wide_Type (Etype (Exp)) - and then Is_Interface (Etype (Exp)) - and then Nkind (Exp) = N_Explicit_Dereference - then - Tag_Node := - Make_Explicit_Dereference (Loc, - Unchecked_Convert_To (RTE (RE_Tag_Ptr), - Make_Function_Call (Loc, - Name => New_Reference_To (RTE (RE_Base_Address), Loc), - Parameter_Associations => New_List ( - Unchecked_Convert_To (RTE (RE_Address), - Duplicate_Subexpr (Prefix (Exp))))))); - else - Tag_Node := - Make_Attribute_Reference (Loc, - Prefix => Duplicate_Subexpr (Exp), - Attribute_Name => Name_Tag); - end if; - - Insert_Action (Exp, - Make_Raise_Program_Error (Loc, - Condition => - Make_Op_Gt (Loc, - Left_Opnd => - Build_Get_Access_Level (Loc, Tag_Node), - Right_Opnd => - Make_Integer_Literal (Loc, - Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))), - Reason => PE_Accessibility_Check_Failed)); - end; - end if; - - -- If we are returning an object that may not be bit-aligned, then - -- copy the value into a temporary first. This copy may need to expand - -- to a loop of component operations.. - - if Is_Possibly_Unaligned_Slice (Exp) - or else Is_Possibly_Unaligned_Object (Exp) - then - declare - Tnn : constant Entity_Id := - Make_Defining_Identifier (Loc, New_Internal_Name ('T')); - begin - Insert_Action (Exp, - Make_Object_Declaration (Loc, - Defining_Identifier => Tnn, - Constant_Present => True, - Object_Definition => New_Occurrence_Of (R_Type, Loc), - Expression => Relocate_Node (Exp)), - Suppress => All_Checks); - Rewrite (Exp, New_Occurrence_Of (Tnn, Loc)); - end; - end if; - - -- Generate call to postcondition checks if they are present - - if Ekind (Scope_Id) = E_Function - and then Has_Postconditions (Scope_Id) - then - -- We are going to reference the returned value twice in this case, - -- once in the call to _Postconditions, and once in the actual return - -- statement, but we can't have side effects happening twice, and in - -- any case for efficiency we don't want to do the computation twice. - - -- If the returned expression is an entity name, we don't need to - -- worry since it is efficient and safe to reference it twice, that's - -- also true for literals other than string literals, and for the - -- case of X.all where X is an entity name. - - if Is_Entity_Name (Exp) - or else Nkind_In (Exp, N_Character_Literal, - N_Integer_Literal, - N_Real_Literal) - or else (Nkind (Exp) = N_Explicit_Dereference - and then Is_Entity_Name (Prefix (Exp))) - then - null; - - -- Otherwise we are going to need a temporary to capture the value - - else - declare - Tnn : constant Entity_Id := - Make_Defining_Identifier (Loc, New_Internal_Name ('T')); - - begin - -- For a complex expression of an elementary type, capture - -- value in the temporary and use it as the reference. - - if Is_Elementary_Type (R_Type) then - Insert_Action (Exp, - Make_Object_Declaration (Loc, - Defining_Identifier => Tnn, - Constant_Present => True, - Object_Definition => New_Occurrence_Of (R_Type, Loc), - Expression => Relocate_Node (Exp)), - Suppress => All_Checks); - - Rewrite (Exp, New_Occurrence_Of (Tnn, Loc)); - - -- If we have something we can rename, generate a renaming of - -- the object and replace the expression with a reference - - elsif Is_Object_Reference (Exp) then - Insert_Action (Exp, - Make_Object_Renaming_Declaration (Loc, - Defining_Identifier => Tnn, - Subtype_Mark => New_Occurrence_Of (R_Type, Loc), - Name => Relocate_Node (Exp)), - Suppress => All_Checks); - - Rewrite (Exp, New_Occurrence_Of (Tnn, Loc)); - - -- Otherwise we have something like a string literal or an - -- aggregate. We could copy the value, but that would be - -- inefficient. Instead we make a reference to the value and - -- capture this reference with a renaming, the expression is - -- then replaced by a dereference of this renaming. - - else - -- For now, copy the value, since the code below does not - -- seem to work correctly ??? - - Insert_Action (Exp, - Make_Object_Declaration (Loc, - Defining_Identifier => Tnn, - Constant_Present => True, - Object_Definition => New_Occurrence_Of (R_Type, Loc), - Expression => Relocate_Node (Exp)), - Suppress => All_Checks); - - Rewrite (Exp, New_Occurrence_Of (Tnn, Loc)); - - -- Insert_Action (Exp, - -- Make_Object_Renaming_Declaration (Loc, - -- Defining_Identifier => Tnn, - -- Access_Definition => - -- Make_Access_Definition (Loc, - -- All_Present => True, - -- Subtype_Mark => New_Occurrence_Of (R_Type, Loc)), - -- Name => - -- Make_Reference (Loc, - -- Prefix => Relocate_Node (Exp))), - -- Suppress => All_Checks); - - -- Rewrite (Exp, - -- Make_Explicit_Dereference (Loc, - -- Prefix => New_Occurrence_Of (Tnn, Loc))); - end if; - end; - end if; - - -- Generate call to _postconditions - - Insert_Action (Exp, - Make_Procedure_Call_Statement (Loc, - Name => Make_Identifier (Loc, Name_uPostconditions), - Parameter_Associations => New_List (Duplicate_Subexpr (Exp)))); - end if; - - -- Ada 2005 (AI-251): If this return statement corresponds with an - -- simple return statement associated with an extended return statement - -- and the type of the returned object is an interface then generate an - -- implicit conversion to force displacement of the "this" pointer. - - if Ada_Version >= Ada_05 - and then Comes_From_Extended_Return_Statement (N) - and then Nkind (Expression (N)) = N_Identifier - and then Is_Interface (Utyp) - and then Utyp /= Underlying_Type (Exptyp) - then - Rewrite (Exp, Convert_To (Utyp, Relocate_Node (Exp))); - Analyze_And_Resolve (Exp); - end if; - end Expand_Simple_Function_Return; - - ------------------------------ - -- Make_Tag_Ctrl_Assignment -- - ------------------------------ - - function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is - Loc : constant Source_Ptr := Sloc (N); - L : constant Node_Id := Name (N); - T : constant Entity_Id := Underlying_Type (Etype (L)); - - Ctrl_Act : constant Boolean := Needs_Finalization (T) - and then not No_Ctrl_Actions (N); - - Save_Tag : constant Boolean := Is_Tagged_Type (T) - and then not No_Ctrl_Actions (N) - and then VM_Target = No_VM; - -- Tags are not saved and restored when VM_Target because VM tags are - -- represented implicitly in objects. - - Res : List_Id; - Tag_Tmp : Entity_Id; - - Prev_Tmp : Entity_Id; - Next_Tmp : Entity_Id; - Ctrl_Ref : Node_Id; - - begin - Res := New_List; - - -- Finalize the target of the assignment when controlled. - -- We have two exceptions here: - - -- 1. If we are in an init proc since it is an initialization - -- more than an assignment - - -- 2. If the left-hand side is a temporary that was not initialized - -- (or the parent part of a temporary since it is the case in - -- extension aggregates). Such a temporary does not come from - -- source. We must examine the original node for the prefix, because - -- it may be a component of an entry formal, in which case it has - -- been rewritten and does not appear to come from source either. - - -- Case of init proc - - if not Ctrl_Act then - null; - - -- The left hand side is an uninitialized temporary object - - elsif Nkind (L) = N_Type_Conversion - and then Is_Entity_Name (Expression (L)) - and then Nkind (Parent (Entity (Expression (L)))) - = N_Object_Declaration - and then No_Initialization (Parent (Entity (Expression (L)))) - then - null; - - else - Append_List_To (Res, - Make_Final_Call ( - Ref => Duplicate_Subexpr_No_Checks (L), - Typ => Etype (L), - With_Detach => New_Reference_To (Standard_False, Loc))); - end if; - - -- Save the Tag in a local variable Tag_Tmp - - if Save_Tag then - Tag_Tmp := - Make_Defining_Identifier (Loc, New_Internal_Name ('A')); - - Append_To (Res, - Make_Object_Declaration (Loc, - Defining_Identifier => Tag_Tmp, - Object_Definition => New_Reference_To (RTE (RE_Tag), Loc), - Expression => - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr_No_Checks (L), - Selector_Name => New_Reference_To (First_Tag_Component (T), - Loc)))); - - -- Otherwise Tag_Tmp not used - - else - Tag_Tmp := Empty; - end if; - - if Ctrl_Act then - if VM_Target /= No_VM then - - -- Cannot assign part of the object in a VM context, so instead - -- fallback to the previous mechanism, even though it is not - -- completely correct ??? - - -- Save the Finalization Pointers in local variables Prev_Tmp and - -- Next_Tmp. For objects with Has_Controlled_Component set, these - -- pointers are in the Record_Controller - - Ctrl_Ref := Duplicate_Subexpr (L); - - if Has_Controlled_Component (T) then - Ctrl_Ref := - Make_Selected_Component (Loc, - Prefix => Ctrl_Ref, - Selector_Name => - New_Reference_To (Controller_Component (T), Loc)); - end if; - - Prev_Tmp := - Make_Defining_Identifier (Loc, New_Internal_Name ('B')); - - Append_To (Res, - Make_Object_Declaration (Loc, - Defining_Identifier => Prev_Tmp, - - Object_Definition => - New_Reference_To (RTE (RE_Finalizable_Ptr), Loc), - - Expression => - Make_Selected_Component (Loc, - Prefix => - Unchecked_Convert_To (RTE (RE_Finalizable), Ctrl_Ref), - Selector_Name => Make_Identifier (Loc, Name_Prev)))); - - Next_Tmp := - Make_Defining_Identifier (Loc, - Chars => New_Internal_Name ('C')); - - Append_To (Res, - Make_Object_Declaration (Loc, - Defining_Identifier => Next_Tmp, - - Object_Definition => - New_Reference_To (RTE (RE_Finalizable_Ptr), Loc), - - Expression => - Make_Selected_Component (Loc, - Prefix => - Unchecked_Convert_To (RTE (RE_Finalizable), - New_Copy_Tree (Ctrl_Ref)), - Selector_Name => Make_Identifier (Loc, Name_Next)))); - - -- Do the Assignment - - Append_To (Res, Relocate_Node (N)); - - else - -- Regular (non VM) processing for controlled types and types with - -- controlled components - - -- Variables of such types contain pointers used to chain them in - -- finalization lists, in addition to user data. These pointers - -- are specific to each object of the type, not to the value being - -- assigned. - - -- Thus they need to be left intact during the assignment. We - -- achieve this by constructing a Storage_Array subtype, and by - -- overlaying objects of this type on the source and target of the - -- assignment. The assignment is then rewritten to assignments of - -- slices of these arrays, copying the user data, and leaving the - -- pointers untouched. - - Controlled_Actions : declare - Prev_Ref : Node_Id; - -- A reference to the Prev component of the record controller - - First_After_Root : Node_Id := Empty; - -- Index of first byte to be copied (used to skip - -- Root_Controlled in controlled objects). - - Last_Before_Hole : Node_Id := Empty; - -- Index of last byte to be copied before outermost record - -- controller data. - - Hole_Length : Node_Id := Empty; - -- Length of record controller data (Prev and Next pointers) - - First_After_Hole : Node_Id := Empty; - -- Index of first byte to be copied after outermost record - -- controller data. - - Expr, Source_Size : Node_Id; - Source_Actual_Subtype : Entity_Id; - -- Used for computation of the size of the data to be copied - - Range_Type : Entity_Id; - Opaque_Type : Entity_Id; - - function Build_Slice - (Rec : Entity_Id; - Lo : Node_Id; - Hi : Node_Id) return Node_Id; - -- Build and return a slice of an array of type S overlaid on - -- object Rec, with bounds specified by Lo and Hi. If either - -- bound is empty, a default of S'First (respectively S'Last) - -- is used. - - ----------------- - -- Build_Slice -- - ----------------- - - function Build_Slice - (Rec : Node_Id; - Lo : Node_Id; - Hi : Node_Id) return Node_Id - is - Lo_Bound : Node_Id; - Hi_Bound : Node_Id; - - Opaque : constant Node_Id := - Unchecked_Convert_To (Opaque_Type, - Make_Attribute_Reference (Loc, - Prefix => Rec, - Attribute_Name => Name_Address)); - -- Access value designating an opaque storage array of type - -- S overlaid on record Rec. - - begin - -- Compute slice bounds using S'First (1) and S'Last as - -- default values when not specified by the caller. - - if No (Lo) then - Lo_Bound := Make_Integer_Literal (Loc, 1); - else - Lo_Bound := Lo; - end if; - - if No (Hi) then - Hi_Bound := Make_Attribute_Reference (Loc, - Prefix => New_Occurrence_Of (Range_Type, Loc), - Attribute_Name => Name_Last); - else - Hi_Bound := Hi; - end if; - - return Make_Slice (Loc, - Prefix => - Opaque, - Discrete_Range => Make_Range (Loc, - Lo_Bound, Hi_Bound)); - end Build_Slice; - - -- Start of processing for Controlled_Actions - - begin - -- Create a constrained subtype of Storage_Array whose size - -- corresponds to the value being assigned. - - -- subtype G is Storage_Offset range - -- 1 .. (Expr'Size + Storage_Unit - 1) / Storage_Unit - - Expr := Duplicate_Subexpr_No_Checks (Expression (N)); - - if Nkind (Expr) = N_Qualified_Expression then - Expr := Expression (Expr); - end if; - - Source_Actual_Subtype := Etype (Expr); - - if Has_Discriminants (Source_Actual_Subtype) - and then not Is_Constrained (Source_Actual_Subtype) - then - Append_To (Res, - Build_Actual_Subtype (Source_Actual_Subtype, Expr)); - Source_Actual_Subtype := Defining_Identifier (Last (Res)); - end if; - - Source_Size := - Make_Op_Add (Loc, - Left_Opnd => - Make_Attribute_Reference (Loc, - Prefix => - New_Occurrence_Of (Source_Actual_Subtype, Loc), - Attribute_Name => Name_Size), - Right_Opnd => - Make_Integer_Literal (Loc, - Intval => System_Storage_Unit - 1)); - - Source_Size := - Make_Op_Divide (Loc, - Left_Opnd => Source_Size, - Right_Opnd => - Make_Integer_Literal (Loc, - Intval => System_Storage_Unit)); - - Range_Type := - Make_Defining_Identifier (Loc, - New_Internal_Name ('G')); - - Append_To (Res, - Make_Subtype_Declaration (Loc, - Defining_Identifier => Range_Type, - Subtype_Indication => - Make_Subtype_Indication (Loc, - Subtype_Mark => - New_Reference_To (RTE (RE_Storage_Offset), Loc), - Constraint => Make_Range_Constraint (Loc, - Range_Expression => - Make_Range (Loc, - Low_Bound => Make_Integer_Literal (Loc, 1), - High_Bound => Source_Size))))); - - -- subtype S is Storage_Array (G) - - Append_To (Res, - Make_Subtype_Declaration (Loc, - Defining_Identifier => - Make_Defining_Identifier (Loc, - New_Internal_Name ('S')), - Subtype_Indication => - Make_Subtype_Indication (Loc, - Subtype_Mark => - New_Reference_To (RTE (RE_Storage_Array), Loc), - Constraint => - Make_Index_Or_Discriminant_Constraint (Loc, - Constraints => - New_List (New_Reference_To (Range_Type, Loc)))))); - - -- type A is access S - - Opaque_Type := - Make_Defining_Identifier (Loc, - Chars => New_Internal_Name ('A')); - - Append_To (Res, - Make_Full_Type_Declaration (Loc, - Defining_Identifier => Opaque_Type, - Type_Definition => - Make_Access_To_Object_Definition (Loc, - Subtype_Indication => - New_Occurrence_Of ( - Defining_Identifier (Last (Res)), Loc)))); - - -- Generate appropriate slice assignments - - First_After_Root := Make_Integer_Literal (Loc, 1); - - -- For the case of a controlled object, skip the - -- Root_Controlled part. - - if Is_Controlled (T) then - First_After_Root := - Make_Op_Add (Loc, - First_After_Root, - Make_Op_Divide (Loc, - Make_Attribute_Reference (Loc, - Prefix => - New_Occurrence_Of (RTE (RE_Root_Controlled), Loc), - Attribute_Name => Name_Size), - Make_Integer_Literal (Loc, System_Storage_Unit))); - end if; - - -- For the case of a record with controlled components, skip - -- the Prev and Next components of the record controller. - -- These components constitute a 'hole' in the middle of the - -- data to be copied. - - if Has_Controlled_Component (T) then - Prev_Ref := - Make_Selected_Component (Loc, - Prefix => - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr_No_Checks (L), - Selector_Name => - New_Reference_To (Controller_Component (T), Loc)), - Selector_Name => Make_Identifier (Loc, Name_Prev)); - - -- Last index before hole: determined by position of - -- the _Controller.Prev component. - - Last_Before_Hole := - Make_Defining_Identifier (Loc, - New_Internal_Name ('L')); - - Append_To (Res, - Make_Object_Declaration (Loc, - Defining_Identifier => Last_Before_Hole, - Object_Definition => New_Occurrence_Of ( - RTE (RE_Storage_Offset), Loc), - Constant_Present => True, - Expression => Make_Op_Add (Loc, - Make_Attribute_Reference (Loc, - Prefix => Prev_Ref, - Attribute_Name => Name_Position), - Make_Attribute_Reference (Loc, - Prefix => New_Copy_Tree (Prefix (Prev_Ref)), - Attribute_Name => Name_Position)))); - - -- Hole length: size of the Prev and Next components - - Hole_Length := - Make_Op_Multiply (Loc, - Left_Opnd => Make_Integer_Literal (Loc, Uint_2), - Right_Opnd => - Make_Op_Divide (Loc, - Left_Opnd => - Make_Attribute_Reference (Loc, - Prefix => New_Copy_Tree (Prev_Ref), - Attribute_Name => Name_Size), - Right_Opnd => - Make_Integer_Literal (Loc, - Intval => System_Storage_Unit))); - - -- First index after hole - - First_After_Hole := - Make_Defining_Identifier (Loc, - New_Internal_Name ('F')); - - Append_To (Res, - Make_Object_Declaration (Loc, - Defining_Identifier => First_After_Hole, - Object_Definition => New_Occurrence_Of ( - RTE (RE_Storage_Offset), Loc), - Constant_Present => True, - Expression => - Make_Op_Add (Loc, - Left_Opnd => - Make_Op_Add (Loc, - Left_Opnd => - New_Occurrence_Of (Last_Before_Hole, Loc), - Right_Opnd => Hole_Length), - Right_Opnd => Make_Integer_Literal (Loc, 1)))); - - Last_Before_Hole := - New_Occurrence_Of (Last_Before_Hole, Loc); - First_After_Hole := - New_Occurrence_Of (First_After_Hole, Loc); - end if; - - -- Assign the first slice (possibly skipping Root_Controlled, - -- up to the beginning of the record controller if present, - -- up to the end of the object if not). - - Append_To (Res, Make_Assignment_Statement (Loc, - Name => Build_Slice ( - Rec => Duplicate_Subexpr_No_Checks (L), - Lo => First_After_Root, - Hi => Last_Before_Hole), - - Expression => Build_Slice ( - Rec => Expression (N), - Lo => First_After_Root, - Hi => New_Copy_Tree (Last_Before_Hole)))); - - if Present (First_After_Hole) then - - -- If a record controller is present, copy the second slice, - -- from right after the _Controller.Next component up to the - -- end of the object. - - Append_To (Res, Make_Assignment_Statement (Loc, - Name => Build_Slice ( - Rec => Duplicate_Subexpr_No_Checks (L), - Lo => First_After_Hole, - Hi => Empty), - Expression => Build_Slice ( - Rec => Duplicate_Subexpr_No_Checks (Expression (N)), - Lo => New_Copy_Tree (First_After_Hole), - Hi => Empty))); - end if; - end Controlled_Actions; - end if; - - else - Append_To (Res, Relocate_Node (N)); - end if; - - -- Restore the tag - - if Save_Tag then - Append_To (Res, - Make_Assignment_Statement (Loc, - Name => - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr_No_Checks (L), - Selector_Name => New_Reference_To (First_Tag_Component (T), - Loc)), - Expression => New_Reference_To (Tag_Tmp, Loc))); - end if; - - if Ctrl_Act then - if VM_Target /= No_VM then - -- Restore the finalization pointers - - Append_To (Res, - Make_Assignment_Statement (Loc, - Name => - Make_Selected_Component (Loc, - Prefix => - Unchecked_Convert_To (RTE (RE_Finalizable), - New_Copy_Tree (Ctrl_Ref)), - Selector_Name => Make_Identifier (Loc, Name_Prev)), - Expression => New_Reference_To (Prev_Tmp, Loc))); - - Append_To (Res, - Make_Assignment_Statement (Loc, - Name => - Make_Selected_Component (Loc, - Prefix => - Unchecked_Convert_To (RTE (RE_Finalizable), - New_Copy_Tree (Ctrl_Ref)), - Selector_Name => Make_Identifier (Loc, Name_Next)), - Expression => New_Reference_To (Next_Tmp, Loc))); - end if; - - -- Adjust the target after the assignment when controlled (not in the - -- init proc since it is an initialization more than an assignment). - - Append_List_To (Res, - Make_Adjust_Call ( - Ref => Duplicate_Subexpr_Move_Checks (L), - Typ => Etype (L), - Flist_Ref => New_Reference_To (RTE (RE_Global_Final_List), Loc), - With_Attach => Make_Integer_Literal (Loc, 0))); - end if; - - return Res; - - exception - -- Could use comment here ??? - - when RE_Not_Available => - return Empty_List; - end Make_Tag_Ctrl_Assignment; - -end Exp_Ch5; |