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------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- E X P _ C H 5 -- -- -- -- B o d y -- -- -- -- Copyright (C) 1992-2009, 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_Aux; use Sem_Aux; 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, or when we have a tagged type with a representation -- clause (this last case is required because holes in the tagged type -- might be filled with components from child types). 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; -- If either operand has an address clause clear Backwards_OK and -- Forwards_OK, since we cannot tell if the operands overlap. We -- exclude this treatment when Rhs is an aggregate, since we know -- that overlap can't occur. if (Has_Address_Clause (Lhs) and then Nkind (Rhs) /= N_Aggregate) or else Has_Address_Clause (Rhs) then Set_Forwards_OK (N, False); Set_Backwards_OK (N, False); 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 dereference 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 Loop_Required is False, meaning that we -- have not discovered some non-overlap reason for requiring a loop, -- then the outcome depends on the capabilities of the back end. if not Loop_Required then -- The GCC back end can deal with all cases of overlap by falling -- back to memmove if it cannot use a more efficient approach. if VM_Target = No_VM and not AAMP_On_Target then return; -- Assume other back ends can handle it if Forwards_OK is set elsif 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 Cleft_Lo := New_Copy_Tree (Left_Lo); Cright_Lo := New_Copy_Tree (Right_Lo); -- If the types do not match we add an implicit conversion -- here to ensure proper match if Etype (Left_Lo) /= Etype (Right_Lo) then Cright_Lo := Unchecked_Convert_To (Etype (Left_Lo), Cright_Lo); end if; -- 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 the back end. 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 -- -------------------------- procedure Expand_Assign_Record (N : Node_Id) is Lhs : constant Node_Id := Name (N); Rhs : Node_Id := Expression (N); L_Typ : constant Entity_Id := Base_Type (Etype (Lhs)); 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 we have a tagged type that has a complete record representation -- clause, we must do we must do component-wise assignments, since child -- types may have used gaps for their components, and we might be -- dealing with a view conversion. elsif Is_Fully_Repped_Tagged_Type (L_Typ) 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)); 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); if Componentwise_Assignment (N) and then Nkind (Name (A)) = N_Selected_Component and then Chars (Selector_Name (Name (A))) = Name_uParent then Set_Componentwise_Assignment (A); end if; 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 -- Look for components, but exclude _tag field assignment if -- the special Componentwise_Assignment flag is set. if Nkind (Item) = N_Component_Declaration and then not (Is_Tag (Defining_Identifier (Item)) and then Componentwise_Assignment (N)) 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_In (Decl, N_Private_Type_Declaration, N_Private_Extension_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_Derived_Type_Definition then RDef := Record_Extension_Part (RDef); 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 -- Special case to check right away, if the Componentwise_Assignment -- flag is set, this is a reanalysis from the expansion of the primitive -- assignment procedure for a tagged type, and all we need to do is to -- expand to assignment of components, because otherwise, we would get -- infinite recursion (since this looks like a tagged assignment which -- would normally try to *call* the primitive assignment procedure). if Componentwise_Assignment (N) then Expand_Assign_Record (N); return; 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. -- Note that we do this right away, because there are some early return -- paths in this procedure, and this is required on all paths. if Validity_Checks_On and then Validity_Check_Default and then not Validity_Check_Subscripts then Check_Valid_Lvalue_Subscripts (Lhs); end if; -- 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 if Do_Range_Check (Rhs) 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 ensure 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, -- fetch the proper type 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 one of these -- conditions holds: -- The expression of the right side has Do_Range_Check set so -- that we know a range check will be performed. Note that it -- can be the case that a range check is omitted because we -- make the assumption that we can assume validity for operands -- appearing in the right side in determining whether a range -- check is required -- The subtype of the right side matches the subtype of the -- left side. In this case, even though we have not checked -- the range of the right side, we know it is in range of its -- subtype if the expression is valid. if Is_Local_Variable_Reference (Lhs) and then not Is_Known_Valid (Entity (Lhs)) and then In_Unconditional_Context (N) then if Do_Range_Check (Rhs) or else Etype (Lhs) = Etype (Rhs) then Set_Is_Known_Valid (Entity (Lhs), True); end if; 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; 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 pragma Assert (Nkind (Original_Node (Return_Object_Decl)) = N_Object_Declaration and then Is_Build_In_Place_Function_Call (Expression (Original_Node (Return_Object_Decl)))); 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). The case where -- the result type is an interface (or class-wide interface) -- is also excluded because the context of the function call -- must be unconstrained, so the initialization will always -- be done as part of an allocator evaluation (storage pool -- or secondary stack), never to a constrained target object -- passed in by the caller. Besides the assignment being -- unneeded in this case, it avoids problems with trying to -- generate a dispatching assignment when the return expression -- is a nonlimited descendant of a limited interface (the -- interface has no assignment operation). if Present (Return_Obj_Expr) and then not No_Initialization (Return_Object_Decl) and then not Is_Interface (Return_Obj_Typ) 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 -- Always use the type of the expression for the -- qualified expression, rather than the result type. -- In general we cannot always use the result type -- for the allocator, because the expression might be -- of a specific type, such as in the case of an -- aggregate or even a nonlimited object when the -- result type is a limited class-wide interface type. Heap_Allocator := Make_Allocator (Loc, Expression => Make_Qualified_Expression (Loc, Subtype_Mark => New_Reference_To (Etype (Return_Obj_Expr), Loc), Expression => New_Copy_Tree (Return_Obj_Expr))); 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, Expression => New_Reference_To (Etype (Return_Obj_Expr), Loc)); else Heap_Allocator := Make_Allocator (Loc, Expression => 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); end if; -- If the No_Allocators restriction is active, then only -- an allocator for secondary stack allocation is needed. -- It's OK for such allocators to have Comes_From_Source -- set to False, because gigi knows not to flag them as -- being a violation of No_Implicit_Heap_Allocations. 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_Allocations -- 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 and -- do not do them if control flow optimizations are suppressed. if Optimization_Level > 0 and then not Opt.Suppress_Control_Flow_Optimizations 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. Remove null loop entirely -- 2. Deal with while condition for C/Fortran boolean -- 3. Deal with loops with a non-standard enumeration type range -- 4. Deal with while loops where Condition_Actions is set -- 5. 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 -- Delete null loop if Is_Null_Loop (N) then Rewrite (N, Make_Null_Statement (Loc)); return; end if; -- Deal with condition for C/Fortran Boolean if Present (Isc) then Adjust_Condition (Condition (Isc)); end if; -- Generate polling call 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. Here, we use the Postcondition_Proc attribute, which -- is needed for implicitly-generated returns. Functions never -- have implicitly-generated returns, and there's no room for -- Postcondition_Proc in E_Function, so we look up the identifier -- Name_uPostconditions for function returns (see -- Expand_Simple_Function_Return). if Ekind (Scope_Id) = E_Procedure and then Has_Postconditions (Scope_Id) then pragma Assert (Present (Postcondition_Proc (Scope_Id))); Insert_Action (N, Make_Procedure_Call_Statement (Loc, Name => New_Reference_To (Postcondition_Proc (Scope_Id), Loc))); 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)); -- The expression is resolved to ensure that the conversion gets -- expanded to generate a possible constraint check. Analyze_And_Resolve (Exp, R_Type); 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)); -- This is an allocator for the secondary stack, and it's fine -- to have Comes_From_Source set False on it, as gigi knows not -- to flag it as a violation of No_Implicit_Heap_Allocations. 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 Tagged_Type_Expansion 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); Component_Assign : constant Boolean := Is_Fully_Repped_Tagged_Type (T); Save_Tag : constant Boolean := Is_Tagged_Type (T) and then not Component_Assign and then not No_Ctrl_Actions (N) and then Tagged_Type_Expansion; -- 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 controlled object, skip 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 -- record controller Prev/Next components. 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; -- Not controlled case else declare Asn : constant Node_Id := Relocate_Node (N); begin -- If this is the case of a tagged type with a full rep clause, -- we must expand it into component assignments, so we mark the -- node as unanalyzed, to get it reanalyzed, but flag it has -- requiring component-wise assignment so we don't get infinite -- recursion. if Component_Assign then Set_Analyzed (Asn, False); Set_Componentwise_Assignment (Asn, True); end if; Append_To (Res, Asn); end; 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;