------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- E X P _ C H 5 -- -- -- -- B o d y -- -- -- -- Copyright (C) 1992-2004, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 2, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING. If not, write -- -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- -- MA 02111-1307, USA. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ with Atree; use Atree; with Checks; use Checks; with Einfo; use Einfo; with Exp_Aggr; use Exp_Aggr; with Exp_Ch7; use Exp_Ch7; with Exp_Ch11; use Exp_Ch11; with Exp_Dbug; use Exp_Dbug; with Exp_Pakd; use Exp_Pakd; with Exp_Tss; use Exp_Tss; with Exp_Util; use Exp_Util; with Hostparm; use Hostparm; with Nlists; use Nlists; with Nmake; use Nmake; with Opt; use Opt; with Restrict; use Restrict; with Rident; use Rident; with Rtsfind; use Rtsfind; with Sinfo; use Sinfo; with Sem; use Sem; with Sem_Ch8; use Sem_Ch8; with Sem_Ch13; use Sem_Ch13; with Sem_Eval; use Sem_Eval; with Sem_Res; use Sem_Res; with Sem_Util; use Sem_Util; with Snames; use Snames; with Stand; use Stand; with Stringt; use Stringt; with Tbuild; use Tbuild; with Uintp; use Uintp; with Validsw; use Validsw; package body Exp_Ch5 is function Change_Of_Representation (N : Node_Id) return Boolean; -- Determine if the right hand side of the assignment N is a type -- conversion which requires a change of representation. Called -- only for the array and record cases. procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id); -- N is an assignment which assigns an array value. This routine process -- the various special cases and checks required for such assignments, -- including change of representation. Rhs is normally simply the right -- hand side of the assignment, except that if the right hand side is -- a type conversion or a qualified expression, then the Rhs is the -- actual expression inside any such type conversions or qualifications. function Expand_Assign_Array_Loop (N : Node_Id; Larray : Entity_Id; Rarray : Entity_Id; L_Type : Entity_Id; R_Type : Entity_Id; Ndim : Pos; Rev : Boolean) return Node_Id; -- N is an assignment statement which assigns an array value. This routine -- expands the assignment into a loop (or nested loops for the case of a -- multi-dimensional array) to do the assignment component by component. -- Larray and Rarray are the entities of the actual arrays on the left -- hand and right hand sides. L_Type and R_Type are the types of these -- arrays (which may not be the same, due to either sliding, or to a -- change of representation case). Ndim is the number of dimensions and -- the parameter Rev indicates if the loops run normally (Rev = False), -- or reversed (Rev = True). The value returned is the constructed -- loop statement. Auxiliary declarations are inserted before node N -- using the standard Insert_Actions mechanism. procedure Expand_Assign_Record (N : Node_Id); -- N is an assignment of a non-tagged record value. This routine handles -- the case where the assignment must be made component by component, -- either because the target is not byte aligned, or there is a change -- of representation. function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id; -- Generate the necessary code for controlled and Tagged assignment, -- that is to say, finalization of the target before, adjustement of -- the target after and save and restore of the tag and finalization -- pointers which are not 'part of the value' and must not be changed -- upon assignment. N is the original Assignment node. function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean; -- This function is used in processing the assignment of a record or -- indexed component. The argument N is either the left hand or right -- hand side of an assignment, and this function determines if there -- is a record component reference where the record may be bit aligned -- in a manner that causes trouble for the back end (see description -- of Exp_Util.Component_May_Be_Bit_Aligned for further details). ------------------------------ -- Change_Of_Representation -- ------------------------------ function Change_Of_Representation (N : Node_Id) return Boolean is Rhs : constant Node_Id := Expression (N); begin return Nkind (Rhs) = N_Type_Conversion and then not Same_Representation (Etype (Rhs), Etype (Expression (Rhs))); end Change_Of_Representation; ------------------------- -- Expand_Assign_Array -- ------------------------- -- There are two issues here. First, do we let Gigi do a block move, or -- do we expand out into a loop? Second, we need to set the two flags -- Forwards_OK and Backwards_OK which show whether the block move (or -- corresponding loops) can be legitimately done in a forwards (low to -- high) or backwards (high to low) manner. procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is Loc : constant Source_Ptr := Sloc (N); Lhs : constant Node_Id := Name (N); Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs); Act_Rhs : Node_Id := Get_Referenced_Object (Rhs); L_Type : constant Entity_Id := Underlying_Type (Get_Actual_Subtype (Act_Lhs)); R_Type : Entity_Id := Underlying_Type (Get_Actual_Subtype (Act_Rhs)); L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice; R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice; Crep : constant Boolean := Change_Of_Representation (N); Larray : Node_Id; Rarray : Node_Id; Ndim : constant Pos := Number_Dimensions (L_Type); Loop_Required : Boolean := False; -- This switch is set to True if the array move must be done using -- an explicit front end generated loop. procedure Apply_Dereference (Arg : in out 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 : in out Node_Id) is Typ : constant Entity_Id := Etype (Arg); begin if Is_Access_Type (Typ) then Rewrite (Arg, Make_Explicit_Dereference (Loc, Prefix => Relocate_Node (Arg))); Analyze_And_Resolve (Arg, Designated_Type (Typ)); end if; end Apply_Dereference; ------------------------ -- Has_Address_Clause -- ------------------------ function Has_Address_Clause (Exp : Node_Id) return Boolean is begin return (Is_Entity_Name (Exp) and then Present (Address_Clause (Entity (Exp)))) or else (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp))); end Has_Address_Clause; --------------------- -- Is_Formal_Array -- --------------------- function Is_Formal_Array (Exp : Node_Id) return Boolean is begin return (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp))) or else (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp))); end Is_Formal_Array; ------------------------ -- Is_Non_Local_Array -- ------------------------ function Is_Non_Local_Array (Exp : Node_Id) return Boolean is begin return (Is_Entity_Name (Exp) and then Scope (Entity (Exp)) /= Current_Scope) or else (Nkind (Exp) = N_Slice and then Is_Non_Local_Array (Prefix (Exp))); end Is_Non_Local_Array; -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs); Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs); Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs); Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs); -- Start of processing for Expand_Assign_Array begin -- Deal with length check, note that the length check is done with -- respect to the right hand side as given, not a possible underlying -- renamed object, since this would generate incorrect extra checks. Apply_Length_Check (Rhs, L_Type); -- We start by assuming that the move can be done in either -- direction, i.e. that the two sides are completely disjoint. Set_Forwards_OK (N, True); Set_Backwards_OK (N, True); -- Normally it is only the slice case that can lead to overlap, -- and explicit checks for slices are made below. But there is -- one case where the slice can be implicit and invisible to us -- and that is the case where we have a one dimensional array, -- and either both operands are parameters, or one is a parameter -- and the other is a global variable. In this case the parameter -- could be a slice that overlaps with the other parameter. -- Check for the case of slices requiring an explicit loop. Normally -- it is only the explicit slice cases that bother us, but in the -- case of one dimensional arrays, parameters can be slices that -- are passed by reference, so we can have aliasing for assignments -- from one parameter to another, or assignments between parameters -- and nonlocal variables. However, if the array subtype is a -- constrained first subtype in the parameter case, then we don't -- have to worry about overlap, since slice assignments aren't -- possible (other than for a slice denoting the whole array). -- Note: overlap is never possible if there is a change of -- representation, so we can exclude this case. if Ndim = 1 and then not Crep and then ((Lhs_Formal and Rhs_Formal) or else (Lhs_Formal and Rhs_Non_Local_Var) or else (Rhs_Formal and Lhs_Non_Local_Var)) and then (not Is_Constrained (Etype (Lhs)) or else not Is_First_Subtype (Etype (Lhs))) -- In the case of compiling for the Java Virtual Machine, -- slices are always passed by making a copy, so we don't -- have to worry about overlap. We also want to prevent -- generation of "<" comparisons for array addresses, -- since that's a meaningless operation on the JVM. and then not Java_VM then Set_Forwards_OK (N, False); Set_Backwards_OK (N, False); -- Note: the bit-packed case is not worrisome here, since if -- we have a slice passed as a parameter, it is always aligned -- on a byte boundary, and if there are no explicit slices, the -- assignment can be performed directly. end if; -- We certainly must use a loop for change of representation -- and also we use the operand of the conversion on the right -- hand side as the effective right hand side (the component -- types must match in this situation). if Crep then Act_Rhs := Get_Referenced_Object (Rhs); R_Type := Get_Actual_Subtype (Act_Rhs); Loop_Required := True; -- We require a loop if the left side is possibly bit unaligned elsif Possible_Bit_Aligned_Component (Lhs) or else Possible_Bit_Aligned_Component (Rhs) then Loop_Required := True; -- Arrays with controlled components are expanded into a loop -- to force calls to adjust at the component level. elsif Has_Controlled_Component (L_Type) then Loop_Required := True; -- Case where no slice is involved elsif not L_Slice and not R_Slice then -- The following code deals with the case of unconstrained bit -- packed arrays. The problem is that the template for such -- arrays contains the bounds of the actual source level array, -- But the copy of an entire array requires the bounds of the -- underlying array. It would be nice if the back end could take -- care of this, but right now it does not know how, so if we -- have such a type, then we expand out into a loop, which is -- inefficient but works correctly. If we don't do this, we -- get the wrong length computed for the array to be moved. -- The two cases we need to worry about are: -- Explicit deference of an unconstrained packed array type as -- in the following example: -- procedure C52 is -- type BITS is array(INTEGER range <>) of BOOLEAN; -- pragma PACK(BITS); -- type A is access BITS; -- P1,P2 : A; -- begin -- P1 := new BITS (1 .. 65_535); -- P2 := new BITS (1 .. 65_535); -- P2.ALL := P1.ALL; -- end C52; -- A formal parameter reference with an unconstrained bit -- array type is the other case we need to worry about (here -- we assume the same BITS type declared above: -- procedure Write_All (File : out BITS; Contents : in BITS); -- begin -- File.Storage := Contents; -- end Write_All; -- We expand to a loop in either of these two cases. -- Question for future thought. Another potentially more efficient -- approach would be to create the actual subtype, and then do an -- unchecked conversion to this actual subtype ??? Check_Unconstrained_Bit_Packed_Array : declare function Is_UBPA_Reference (Opnd : Node_Id) return Boolean; -- Function to perform required test for the first case, -- above (dereference of an unconstrained bit packed array) ----------------------- -- Is_UBPA_Reference -- ----------------------- function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is Typ : constant Entity_Id := Underlying_Type (Etype (Opnd)); P_Type : Entity_Id; Des_Type : Entity_Id; begin if Present (Packed_Array_Type (Typ)) and then Is_Array_Type (Packed_Array_Type (Typ)) and then not Is_Constrained (Packed_Array_Type (Typ)) then return True; elsif Nkind (Opnd) = N_Explicit_Dereference then P_Type := Underlying_Type (Etype (Prefix (Opnd))); if not Is_Access_Type (P_Type) then return False; else Des_Type := Designated_Type (P_Type); return Is_Bit_Packed_Array (Des_Type) and then not Is_Constrained (Des_Type); end if; else return False; end if; end Is_UBPA_Reference; -- Start of processing for Check_Unconstrained_Bit_Packed_Array begin if Is_UBPA_Reference (Lhs) or else Is_UBPA_Reference (Rhs) then Loop_Required := True; -- Here if we do not have the case of a reference to a bit -- packed unconstrained array case. In this case gigi can -- most certainly handle the assignment if a forwards move -- is allowed. -- (could it handle the backwards case also???) elsif Forwards_OK (N) then return; end if; end Check_Unconstrained_Bit_Packed_Array; -- Gigi 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 a -- aggregate, except in the case of a null slice, for which no aggregate -- can be written. In that case, rewrite the assignment as a null -- statement, a length check has already been emitted to verify that -- the range of the left-hand side is empty. -- Note that this code is not executed if we had an assignment of -- a string literal to a non-bit aligned component of a record, a -- case which cannot be handled by the backend elsif Nkind (Rhs) = N_String_Literal then if String_Length (Strval (Rhs)) = 0 and then Is_Bit_Packed_Array (L_Type) then Rewrite (N, Make_Null_Statement (Loc)); Analyze (N); end if; return; -- If either operand is bit packed, then we need a loop, since we -- can't be sure that the slice is byte aligned. Similarly, if either -- operand is a possibly unaligned slice, then we need a loop (since -- gigi 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 -- gigi 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, Name_T); Decl : Node_Id; begin Decl := Make_Object_Declaration (Loc, Defining_Identifier => Temp, Object_Definition => New_Occurrence_Of (L_Type, Loc), Expression => Relocate_Node (Rhs)); Insert_Action (N, Decl); Rewrite (Rhs, New_Occurrence_Of (Temp, Loc)); R_Type := Etype (Temp); end; end if; -- Come here to complete the analysis -- Loop_Required: Set to True if we know that a loop is required -- regardless of overlap considerations. -- Forwards_OK: Set to False if we already know that a forwards -- move is not safe, else set to True. -- Backwards_OK: Set to False if we already know that a backwards -- move is not safe, else set to True -- Our task at this stage is to complete the overlap analysis, which -- can result in possibly setting Forwards_OK or Backwards_OK to -- False, and then generating the final code, either by deciding -- that it is OK after all to let Gigi handle it, or by generating -- appropriate code in the front end. declare L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type)); R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type)); Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ); Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ); Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ); Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ); Act_L_Array : Node_Id; Act_R_Array : Node_Id; Cleft_Lo : Node_Id; Cright_Lo : Node_Id; Condition : Node_Id; Cresult : Compare_Result; begin -- Get the expressions for the arrays. If we are dealing with a -- private type, then convert to the underlying type. We can do -- direct assignments to an array that is a private type, but -- we cannot assign to elements of the array without this extra -- unchecked conversion. if Nkind (Act_Lhs) = N_Slice then Larray := Prefix (Act_Lhs); else Larray := Act_Lhs; if Is_Private_Type (Etype (Larray)) then Larray := Unchecked_Convert_To (Underlying_Type (Etype (Larray)), Larray); end if; end if; if Nkind (Act_Rhs) = N_Slice then Rarray := Prefix (Act_Rhs); else Rarray := Act_Rhs; if Is_Private_Type (Etype (Rarray)) then Rarray := Unchecked_Convert_To (Underlying_Type (Etype (Rarray)), Rarray); end if; end if; -- If both sides are slices, we must figure out whether -- it is safe to do the move in one direction or the other -- It is always safe if there is a change of representation -- since obviously two arrays with different representations -- cannot possibly overlap. if (not Crep) and L_Slice and R_Slice then Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs)); Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs)); -- If both left and right hand arrays are entity names, and -- refer to different entities, then we know that the move -- is safe (the two storage areas are completely disjoint). if Is_Entity_Name (Act_L_Array) and then Is_Entity_Name (Act_R_Array) and then Entity (Act_L_Array) /= Entity (Act_R_Array) then null; -- Otherwise, we assume the worst, which is that the two -- arrays are the same array. There is no need to check if -- we know that is the case, because if we don't know it, -- we still have to assume it! -- Generally if the same array is involved, then we have -- an overlapping case. We will have to really assume the -- worst (i.e. set neither of the OK flags) unless we can -- determine the lower or upper bounds at compile time and -- compare them. else Cresult := Compile_Time_Compare (Left_Lo, Right_Lo); if Cresult = Unknown then Cresult := Compile_Time_Compare (Left_Hi, Right_Hi); end if; case Cresult is when LT | LE | EQ => Set_Backwards_OK (N, False); when GT | GE => Set_Forwards_OK (N, False); when NE | Unknown => Set_Backwards_OK (N, False); Set_Forwards_OK (N, False); end case; end if; end if; -- If after that analysis, Forwards_OK is still True, and -- Loop_Required is False, meaning that we have not discovered -- some non-overlap reason for requiring a loop, then we can -- still let gigi handle it. if not Loop_Required then if Forwards_OK (N) then return; else null; -- Here is where a memmove would be appropriate ??? end if; end if; -- At this stage we have to generate an explicit loop, and -- we have the following cases: -- Forwards_OK = True -- Rnn : right_index := right_index'First; -- for Lnn in left-index loop -- left (Lnn) := right (Rnn); -- Rnn := right_index'Succ (Rnn); -- end loop; -- Note: the above code MUST be analyzed with checks off, -- because otherwise the Succ could overflow. But in any -- case this is more efficient! -- Forwards_OK = False, Backwards_OK = True -- Rnn : right_index := right_index'Last; -- for Lnn in reverse left-index loop -- left (Lnn) := right (Rnn); -- Rnn := right_index'Pred (Rnn); -- end loop; -- Note: the above code MUST be analyzed with checks off, -- because otherwise the Pred could overflow. But in any -- case this is more efficient! -- Forwards_OK = Backwards_OK = False -- This only happens if we have the same array on each side. It is -- possible to create situations using overlays that violate this, -- but we simply do not promise to get this "right" in this case. -- There are two possible subcases. If the No_Implicit_Conditionals -- restriction is set, then we generate the following code: -- declare -- T : constant := rhs; -- begin -- lhs := T; -- end; -- If implicit conditionals are permitted, then we generate: -- if Left_Lo <= Right_Lo then -- -- else -- -- end if; -- Cases where either Forwards_OK or Backwards_OK is true if Forwards_OK (N) or else Backwards_OK (N) then if Controlled_Type (Component_Type (L_Type)) and then Base_Type (L_Type) = Base_Type (R_Type) and then Ndim = 1 and then not No_Ctrl_Actions (N) then declare Proc : constant Entity_Id := TSS (Base_Type (L_Type), TSS_Slice_Assign); Actuals : List_Id; begin Apply_Dereference (Larray); Apply_Dereference (Rarray); Actuals := New_List ( Duplicate_Subexpr (Larray, Name_Req => True), Duplicate_Subexpr (Rarray, Name_Req => True), Duplicate_Subexpr (Left_Lo, Name_Req => True), Duplicate_Subexpr (Left_Hi, Name_Req => True), Duplicate_Subexpr (Right_Lo, Name_Req => True), Duplicate_Subexpr (Right_Hi, Name_Req => True)); Append_To (Actuals, New_Occurrence_Of ( Boolean_Literals (not Forwards_OK (N)), Loc)); Rewrite (N, Make_Procedure_Call_Statement (Loc, Name => New_Reference_To (Proc, Loc), Parameter_Associations => Actuals)); end; else Rewrite (N, Expand_Assign_Array_Loop (N, Larray, Rarray, L_Type, R_Type, Ndim, Rev => not Forwards_OK (N))); end if; -- Case of both are false with No_Implicit_Conditionals elsif Restriction_Active (No_Implicit_Conditionals) then declare T : constant Entity_Id := Make_Defining_Identifier (Loc, Chars => Name_T); begin Rewrite (N, Make_Block_Statement (Loc, Declarations => New_List ( Make_Object_Declaration (Loc, Defining_Identifier => T, Constant_Present => True, Object_Definition => New_Occurrence_Of (Etype (Rhs), Loc), Expression => Relocate_Node (Rhs))), Handled_Statement_Sequence => Make_Handled_Sequence_Of_Statements (Loc, Statements => New_List ( Make_Assignment_Statement (Loc, Name => Relocate_Node (Lhs), Expression => New_Occurrence_Of (T, Loc)))))); end; -- Case of both are false with implicit conditionals allowed else -- Before we generate this code, we must ensure that the -- left and right side array types are defined. They may -- be itypes, and we cannot let them be defined inside the -- if, since the first use in the then may not be executed. Ensure_Defined (L_Type, N); Ensure_Defined (R_Type, N); -- We normally compare addresses to find out which way round -- to do the loop, since this is realiable, and handles the -- cases of parameters, conversions etc. But we can't do that -- in the bit packed case or the Java VM case, because addresses -- don't work there. if not Is_Bit_Packed_Array (L_Type) and then not Java_VM then Condition := Make_Op_Le (Loc, Left_Opnd => Unchecked_Convert_To (RTE (RE_Integer_Address), Make_Attribute_Reference (Loc, Prefix => Make_Indexed_Component (Loc, Prefix => Duplicate_Subexpr_Move_Checks (Larray, True), Expressions => New_List ( Make_Attribute_Reference (Loc, Prefix => New_Reference_To (L_Index_Typ, Loc), Attribute_Name => Name_First))), Attribute_Name => Name_Address)), Right_Opnd => Unchecked_Convert_To (RTE (RE_Integer_Address), Make_Attribute_Reference (Loc, Prefix => Make_Indexed_Component (Loc, Prefix => Duplicate_Subexpr_Move_Checks (Rarray, True), Expressions => New_List ( Make_Attribute_Reference (Loc, Prefix => New_Reference_To (R_Index_Typ, Loc), Attribute_Name => Name_First))), Attribute_Name => Name_Address))); -- For the bit packed and Java VM cases we use the bounds. -- That's OK, because we don't have to worry about parameters, -- since they cannot cause overlap. Perhaps we should worry -- about weird slice conversions ??? else -- Copy the bounds and reset the Analyzed flag, because the -- bounds of the index type itself may be universal, and must -- must be reaanalyzed to acquire the proper type for Gigi. Cleft_Lo := New_Copy_Tree (Left_Lo); Cright_Lo := New_Copy_Tree (Right_Lo); Set_Analyzed (Cleft_Lo, False); Set_Analyzed (Cright_Lo, False); Condition := Make_Op_Le (Loc, Left_Opnd => Cleft_Lo, Right_Opnd => Cright_Lo); end if; if Controlled_Type (Component_Type (L_Type)) and then Base_Type (L_Type) = Base_Type (R_Type) and then Ndim = 1 and then not No_Ctrl_Actions (N) then -- Call TSS procedure for array assignment, passing the -- the explicit bounds of right- and left-hand side. declare Proc : constant Node_Id := TSS (Base_Type (L_Type), TSS_Slice_Assign); Actuals : List_Id; begin Apply_Dereference (Larray); Apply_Dereference (Rarray); Actuals := New_List ( Duplicate_Subexpr (Larray, Name_Req => True), Duplicate_Subexpr (Rarray, Name_Req => True), Duplicate_Subexpr (Left_Lo, Name_Req => True), Duplicate_Subexpr (Left_Hi, Name_Req => True), Duplicate_Subexpr (Right_Lo, Name_Req => True), Duplicate_Subexpr (Right_Hi, Name_Req => True)); Append_To (Actuals, 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)); -- Propagate the No_Ctrl_Actions flag to individual assignments Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N)); end; -- Now construct the loop from the inside out, with the last subscript -- varying most rapidly. Note that Assign is first the raw assignment -- statement, and then subsequently the loop that wraps it up. for J in reverse 1 .. Ndim loop Assign := Make_Block_Statement (Loc, Declarations => New_List ( Make_Object_Declaration (Loc, Defining_Identifier => Rnn (J), Object_Definition => New_Occurrence_Of (R_Index_Type (J), Loc), Expression => Make_Attribute_Reference (Loc, Prefix => New_Occurrence_Of (R_Index_Type (J), Loc), Attribute_Name => F_Or_L))), Handled_Statement_Sequence => Make_Handled_Sequence_Of_Statements (Loc, Statements => New_List ( Make_Implicit_Loop_Statement (N, Iteration_Scheme => Make_Iteration_Scheme (Loc, Loop_Parameter_Specification => Make_Loop_Parameter_Specification (Loc, Defining_Identifier => Lnn (J), Reverse_Present => Rev, Discrete_Subtype_Definition => New_Reference_To (L_Index_Type (J), Loc))), Statements => New_List ( Assign, Make_Assignment_Statement (Loc, Name => New_Occurrence_Of (Rnn (J), Loc), Expression => Make_Attribute_Reference (Loc, Prefix => New_Occurrence_Of (R_Index_Type (J), Loc), Attribute_Name => S_Or_P, Expressions => New_List ( New_Occurrence_Of (Rnn (J), Loc))))))))); end loop; return Assign; end Expand_Assign_Array_Loop; -------------------------- -- Expand_Assign_Record -- -------------------------- -- The only processing required is in the change of representation -- case, where we must expand the assignment to a series of field -- by field assignments. procedure Expand_Assign_Record (N : Node_Id) is Lhs : constant Node_Id := Name (N); Rhs : Node_Id := Expression (N); begin -- If change of representation, then extract the real right hand -- side from the type conversion, and proceed with component-wise -- assignment, since the two types are not the same as far as the -- back end is concerned. if Change_Of_Representation (N) then Rhs := Expression (Rhs); -- If this may be a case of a large bit aligned component, then -- proceed with component-wise assignment, to avoid possible -- clobbering of other components sharing bits in the first or -- last byte of the component to be assigned. elsif Possible_Bit_Aligned_Component (Lhs) or Possible_Bit_Aligned_Component (Rhs) then null; -- If neither condition met, then nothing special to do, the back end -- can handle assignment of the entire component as a single entity. else return; end if; -- At this stage we know that we must do a component wise assignment declare Loc : constant Source_Ptr := Sloc (N); R_Typ : constant Entity_Id := Base_Type (Etype (Rhs)); L_Typ : constant Entity_Id := Base_Type (Etype (Lhs)); Decl : constant Node_Id := Declaration_Node (R_Typ); RDef : Node_Id; F : Entity_Id; function Find_Component (Typ : Entity_Id; Comp : Entity_Id) return Entity_Id; -- Find the component with the given name in the underlying record -- declaration for Typ. We need to use the actual entity because -- the type may be private and resolution by identifier alone would -- fail. function Make_Component_List_Assign (CL : Node_Id) return List_Id; -- Returns a sequence of statements to assign the components that -- are referenced in the given component list. function Make_Field_Assign (C : Entity_Id) return Node_Id; -- Given C, the entity for a discriminant or component, build -- an assignment for the corresponding field values. 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) return List_Id is CI : constant List_Id := Component_Items (CL); VP : constant Node_Id := Variant_Part (CL); Result : List_Id; Alts : List_Id; V : Node_Id; DC : Node_Id; DCH : List_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; Append_To (Result, Make_Case_Statement (Loc, Expression => Make_Selected_Component (Loc, Prefix => Duplicate_Subexpr (Rhs), Selector_Name => Make_Identifier (Loc, Chars (Name (VP)))), Alternatives => Alts)); end if; return Result; end Make_Component_List_Assign; ----------------------- -- Make_Field_Assign -- ----------------------- function Make_Field_Assign (C : Entity_Id) return Node_Id is A : Node_Id; begin 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 => Make_Selected_Component (Loc, Prefix => Duplicate_Subexpr (Rhs), Selector_Name => New_Occurrence_Of (C, Loc))); -- Set Assignment_OK, so discriminants can be assigned Set_Assignment_OK (Name (A), True); return A; end Make_Field_Assign; ------------------------ -- Make_Field_Assigns -- ------------------------ function Make_Field_Assigns (CI : List_Id) return List_Id is Item : Node_Id; Result : List_Id; begin Item := First (CI); Result := New_List; while Present (Item) loop if Nkind (Item) = N_Component_Declaration then Append_To (Result, Make_Field_Assign (Defining_Identifier (Item))); end if; Next (Item); end loop; return Result; end Make_Field_Assigns; -- Start of processing for Expand_Assign_Record begin -- Note that we use the base types for this processing. This results -- in some extra work in the constrained case, but the change of -- representation case is so unusual that it is not worth the effort. -- First copy the discriminants. This is done unconditionally. It -- is required in the unconstrained left side case, and also in the -- case where this assignment was constructed during the expansion -- of a type conversion (since initialization of discriminants is -- suppressed in this case). It is unnecessary but harmless in -- other cases. if Has_Discriminants (L_Typ) then F := First_Discriminant (R_Typ); while Present (F) loop Insert_Action (N, Make_Field_Assign (F)); Next_Discriminant (F); end loop; end if; -- We know the underlying type is a record, but its current view -- may be private. We must retrieve the usable record declaration. if Nkind (Decl) = N_Private_Type_Declaration and then Present (Full_View (R_Typ)) then RDef := Type_Definition (Declaration_Node (Full_View (R_Typ))); else RDef := Type_Definition (Decl); end if; if Nkind (RDef) = N_Record_Definition and then Present (Component_List (RDef)) then Insert_Actions (N, Make_Component_List_Assign (Component_List (RDef))); Rewrite (N, Make_Null_Statement (Loc)); end if; end; end Expand_Assign_Record; ----------------------------------- -- Expand_N_Assignment_Statement -- ----------------------------------- -- For array types, deal with slice assignments and setting the flags -- to indicate if it can be statically determined which direction the -- move should go in. Also deal with generating range/length checks. procedure Expand_N_Assignment_Statement (N : Node_Id) is Loc : constant Source_Ptr := Sloc (N); Lhs : constant Node_Id := Name (N); Rhs : constant Node_Id := Expression (N); Typ : constant Entity_Id := Underlying_Type (Etype (Lhs)); Exp : Node_Id; begin -- First deal with generation of range check if required. For now -- we do this only for discrete types. if Do_Range_Check (Rhs) and then Is_Discrete_Type (Typ) then Set_Do_Range_Check (Rhs, False); Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed); end if; -- Check for a special case where a high level transformation is -- required. If we have either of: -- P.field := rhs; -- P (sub) := rhs; -- where P is a reference to a bit packed array, then we have to unwind -- the assignment. The exact meaning of being a reference to a bit -- packed array is as follows: -- An indexed component whose prefix is a bit packed array is a -- reference to a bit packed array. -- An indexed component or selected component whose prefix is a -- reference to a bit packed array is itself a reference ot a -- bit packed array. -- The required transformation is -- Tnn : prefix_type := P; -- Tnn.field := rhs; -- P := Tnn; -- or -- Tnn : prefix_type := P; -- Tnn (subscr) := rhs; -- P := Tnn; -- Since P is going to be evaluated more than once, any subscripts -- in P must have their evaluation forced. if (Nkind (Lhs) = N_Indexed_Component or else Nkind (Lhs) = N_Selected_Component) and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs)) then declare BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs)); BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr); Tnn : constant Entity_Id := Make_Defining_Identifier (Loc, Chars => New_Internal_Name ('T')); begin -- Insert the post assignment first, because we want to copy -- the BPAR_Expr tree before it gets analyzed in the context -- of the pre assignment. Note that we do not analyze the -- post assignment yet (we cannot till we have completed the -- analysis of the pre assignment). As usual, the analysis -- of this post assignment will happen on its own when we -- "run into" it after finishing the current assignment. Insert_After (N, Make_Assignment_Statement (Loc, Name => New_Copy_Tree (BPAR_Expr), Expression => New_Occurrence_Of (Tnn, Loc))); -- At this stage BPAR_Expr is a reference to a bit packed -- array where the reference was not expanded in the original -- tree, since it was on the left side of an assignment. But -- in the pre-assignment statement (the object definition), -- BPAR_Expr will end up on the right hand side, and must be -- reexpanded. To achieve this, we reset the analyzed flag -- of all selected and indexed components down to the actual -- indexed component for the packed array. Exp := BPAR_Expr; loop Set_Analyzed (Exp, False); if Nkind (Exp) = N_Selected_Component or else Nkind (Exp) = N_Indexed_Component then Exp := Prefix (Exp); else exit; end if; end loop; -- Now we can insert and analyze the pre-assignment. -- If the right-hand side requires a transient scope, it has -- already been placed on the stack. However, the declaration is -- inserted in the tree outside of this scope, and must reflect -- the proper scope for its variable. This awkward bit is forced -- by the stricter scope discipline imposed by GCC 2.97. declare Uses_Transient_Scope : constant Boolean := Scope_Is_Transient and then N = Node_To_Be_Wrapped; begin if Uses_Transient_Scope then New_Scope (Scope (Current_Scope)); end if; Insert_Before_And_Analyze (N, Make_Object_Declaration (Loc, Defining_Identifier => Tnn, Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc), Expression => BPAR_Expr)); if Uses_Transient_Scope then Pop_Scope; end if; end; -- Now fix up the original assignment and continue processing Rewrite (Prefix (Lhs), New_Occurrence_Of (Tnn, Loc)); -- We do not need to reanalyze that assignment, and we do not need -- to worry about references to the temporary, but we do need to -- make sure that the temporary is not marked as a true constant -- since we now have a generate assignment to it! Set_Is_True_Constant (Tnn, False); end; end if; -- When we have the appropriate type of aggregate in the -- expression (it has been determined during analysis of the -- aggregate by setting the delay flag), let's perform in place -- assignment and thus avoid creating a temporay. if Is_Delayed_Aggregate (Rhs) then Convert_Aggr_In_Assignment (N); Rewrite (N, Make_Null_Statement (Loc)); Analyze (N); return; end if; -- Apply discriminant check if required. If Lhs is an access type -- to a designated type with discriminants, we must always check. if Has_Discriminants (Etype (Lhs)) then -- Skip discriminant check if change of representation. Will be -- done when the change of representation is expanded out. if not Change_Of_Representation (N) then Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs); end if; -- If the type is private without discriminants, and the full type -- has discriminants (necessarily with defaults) a check may still be -- necessary if the Lhs is aliased. The private determinants must be -- visible to build the discriminant constraints. -- Only an explicit dereference that comes from source indicates -- aliasing. Access to formals of protected operations and entries -- create dereferences but are not semantic aliasings. elsif Is_Private_Type (Etype (Lhs)) and then Has_Discriminants (Typ) and then Nkind (Lhs) = N_Explicit_Dereference and then Comes_From_Source (Lhs) then declare Lt : constant Entity_Id := Etype (Lhs); begin Set_Etype (Lhs, Typ); Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs)); Apply_Discriminant_Check (Rhs, Typ, Lhs); Set_Etype (Lhs, Lt); end; -- If the Lhs has a private type with unknown discriminants, it -- may have a full view with discriminants, but those are nameable -- only in the underlying type, so convert the Rhs to it before -- potential checking. elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs))) and then Has_Discriminants (Typ) then Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs)); Apply_Discriminant_Check (Rhs, Typ, Lhs); -- In the access type case, we need the same discriminant check, -- and also range checks if we have an access to constrained array. elsif Is_Access_Type (Etype (Lhs)) and then Is_Constrained (Designated_Type (Etype (Lhs))) then if Has_Discriminants (Designated_Type (Etype (Lhs))) then -- Skip discriminant check if change of representation. Will be -- done when the change of representation is expanded out. if not Change_Of_Representation (N) then Apply_Discriminant_Check (Rhs, Etype (Lhs)); end if; elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then Apply_Range_Check (Rhs, Etype (Lhs)); if Is_Constrained (Etype (Lhs)) then Apply_Length_Check (Rhs, Etype (Lhs)); end if; if Nkind (Rhs) = N_Allocator then declare Target_Typ : constant Entity_Id := Etype (Expression (Rhs)); C_Es : Check_Result; begin C_Es := Range_Check (Lhs, Target_Typ, Etype (Designated_Type (Etype (Lhs)))); Insert_Range_Checks (C_Es, N, Target_Typ, Sloc (Lhs), Lhs); end; end if; end if; -- Apply range check for access type case elsif Is_Access_Type (Etype (Lhs)) and then Nkind (Rhs) = N_Allocator and then Nkind (Expression (Rhs)) = N_Qualified_Expression then Analyze_And_Resolve (Expression (Rhs)); Apply_Range_Check (Expression (Rhs), Designated_Type (Etype (Lhs))); end if; -- Ada 2005 (AI-231): Generate conversion to the null-excluding -- type to force the corresponding run-time check if Is_Access_Type (Typ) and then ((Is_Entity_Name (Lhs) and then Can_Never_Be_Null (Entity (Lhs))) or else Can_Never_Be_Null (Etype (Lhs))) then Rewrite (Rhs, Convert_To (Etype (Lhs), Relocate_Node (Rhs))); Analyze_And_Resolve (Rhs, Etype (Lhs)); end if; -- If we are assigning an access type and the left side is an -- entity, then make sure that Is_Known_Non_Null properly -- reflects the state of the entity after the assignment if Is_Access_Type (Typ) and then Is_Entity_Name (Lhs) and then Known_Non_Null (Rhs) and then Safe_To_Capture_Value (N, Entity (Lhs)) then Set_Is_Known_Non_Null (Entity (Lhs), Known_Non_Null (Rhs)); 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; -- Case of tagged type assignment elsif Is_Tagged_Type (Typ) or else (Controlled_Type (Typ) and then not Is_Array_Type (Typ)) then Tagged_Case : declare L : List_Id := No_List; Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N); begin -- In the controlled case, we need to make sure that function -- calls are evaluated before finalizing the target. In all -- cases, it makes the expansion easier if the side-effects -- are removed first. Remove_Side_Effects (Lhs); Remove_Side_Effects (Rhs); -- Avoid recursion in the mechanism Set_Analyzed (N); -- If dispatching assignment, we need to dispatch to _assign if Is_Class_Wide_Type (Typ) -- If the type is tagged, we may as well use the predefined -- primitive assignment. This avoids inlining a lot of code -- and in the class-wide case, the assignment is replaced by -- a 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. or else (Is_Tagged_Type (Typ) and then Chars (Current_Scope) /= Name_uAssign and then Expand_Ctrl_Actions and then not Discriminant_Checks_Suppressed (Empty)) then -- Fetch the primitive op _assign and proper type to call -- it. Because of possible conflits between private and -- full view the proper type is fetched directly from the -- operation profile. declare Op : constant Entity_Id := Find_Prim_Op (Typ, Name_uAssign); F_Typ : Entity_Id := Etype (First_Formal (Op)); begin -- If the assignment is dispatching, make sure to use the -- ??? where is rest of this comment ??? if Is_Class_Wide_Type (Typ) then F_Typ := Class_Wide_Type (F_Typ); end if; L := New_List ( 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 -- -- end if; if not Statically_Different (Lhs, Rhs) and then Expand_Ctrl_Actions then L := New_List ( Make_Implicit_If_Statement (N, Condition => Make_Op_Ne (Loc, Left_Opnd => Make_Attribute_Reference (Loc, Prefix => Duplicate_Subexpr (Lhs), Attribute_Name => Name_Address), Right_Opnd => Make_Attribute_Reference (Loc, Prefix => Duplicate_Subexpr (Rhs), Attribute_Name => Name_Address)), Then_Statements => L)); end if; -- We need to set up an exception handler for implementing -- 7.6.1 (18). The remaining adjustments are tackled by the -- implementation of adjust for record_controllers (see -- s-finimp.adb) -- This is skipped if we have no finalization if Expand_Ctrl_Actions and then not Restriction_Active (No_Finalization) then L := New_List ( Make_Block_Statement (Loc, Handled_Statement_Sequence => Make_Handled_Sequence_Of_Statements (Loc, Statements => L, Exception_Handlers => New_List ( Make_Exception_Handler (Loc, Exception_Choices => New_List (Make_Others_Choice (Loc)), Statements => New_List ( Make_Raise_Program_Error (Loc, Reason => PE_Finalize_Raised_Exception) )))))); end if; end if; Rewrite (N, Make_Block_Statement (Loc, Handled_Statement_Sequence => Make_Handled_Sequence_Of_Statements (Loc, Statements => L))); -- If no restrictions on aborts, protect the whole assignement -- for controlled objects as per 9.8(11) if Controlled_Type (Typ) and then Expand_Ctrl_Actions and then Abort_Allowed then declare Blk : constant Entity_Id := New_Internal_Entity ( E_Block, Current_Scope, Sloc (N), 'B'); begin Set_Scope (Blk, Current_Scope); Set_Etype (Blk, Standard_Void_Type); Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N))); Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer)); Set_At_End_Proc (Handled_Statement_Sequence (N), New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc)); Expand_At_End_Handler (Handled_Statement_Sequence (N), Blk); end; end if; Analyze (N); return; end Tagged_Case; -- Array types elsif Is_Array_Type (Typ) then declare Actual_Rhs : Node_Id := Rhs; begin while Nkind (Actual_Rhs) = N_Type_Conversion or else Nkind (Actual_Rhs) = N_Qualified_Expression loop Actual_Rhs := Expression (Actual_Rhs); end loop; Expand_Assign_Array (N, Actual_Rhs); return; end; -- Record types elsif Is_Record_Type (Typ) then Expand_Assign_Record (N); return; -- Scalar types. This is where we perform the processing related -- to the requirements of (RM 13.9.1(9-11)) concerning the handling -- of invalid scalar values. elsif Is_Scalar_Type (Typ) then -- Case where right side is known valid if Expr_Known_Valid (Rhs) then -- Here the right side is valid, so it is fine. The case to -- deal with is when the left side is a local variable reference -- whose value is not currently known to be valid. If this is -- the case, and the assignment appears in an unconditional -- context, then we can mark the left side as now being valid. if Is_Local_Variable_Reference (Lhs) and then not Is_Known_Valid (Entity (Lhs)) and then In_Unconditional_Context (N) then Set_Is_Known_Valid (Entity (Lhs), True); end if; -- Case where right side may be invalid in the sense of the RM -- reference above. The RM does not require that we check for -- the validity on an assignment, but it does require that the -- assignment of an invalid value not cause erroneous behavior. -- The general approach in GNAT is to use the Is_Known_Valid flag -- to avoid the need for validity checking on assignments. However -- in some cases, we have to do validity checking in order to make -- sure that the setting of this flag is correct. else -- Validate right side if we are validating copies if Validity_Checks_On and then Validity_Check_Copies then Ensure_Valid (Rhs); -- We can propagate this to the left side where appropriate if Is_Local_Variable_Reference (Lhs) and then not Is_Known_Valid (Entity (Lhs)) and then In_Unconditional_Context (N) then Set_Is_Known_Valid (Entity (Lhs), True); end if; -- Otherwise check to see what should be done -- If left side is a local variable, then we just set its -- flag to indicate that its value may no longer be valid, -- since we are copying a potentially invalid value. elsif Is_Local_Variable_Reference (Lhs) then Set_Is_Known_Valid (Entity (Lhs), False); -- Check for case of a nonlocal variable on the left side -- which is currently known to be valid. In this case, we -- simply ensure that the right side is valid. We only play -- the game of copying validity status for local variables, -- since we are doing this statically, not by tracing the -- full flow graph. elsif Is_Entity_Name (Lhs) and then Is_Known_Valid (Entity (Lhs)) then -- Note that the Ensure_Valid call is ignored if the -- Validity_Checking mode is set to none so we do not -- need to worry about that case here. Ensure_Valid (Rhs); -- In all other cases, we can safely copy an invalid value -- without worrying about the status of the left side. Since -- it is not a variable reference it will not be considered -- as being known to be valid in any case. else null; end if; end if; end if; -- Defend against invalid subscripts on left side if we are in -- standard validity checking mode. No need to do this if we -- are checking all subscripts. if Validity_Checks_On and then Validity_Check_Default and then not Validity_Check_Subscripts then Check_Valid_Lvalue_Subscripts (Lhs); end if; exception when RE_Not_Available => return; end Expand_N_Assignment_Statement; ------------------------------ -- Expand_N_Block_Statement -- ------------------------------ -- Encode entity names defined in block statement procedure Expand_N_Block_Statement (N : Node_Id) is begin Qualify_Entity_Names (N); end Expand_N_Block_Statement; ----------------------------- -- Expand_N_Case_Statement -- ----------------------------- procedure Expand_N_Case_Statement (N : Node_Id) is Loc : constant Source_Ptr := Sloc (N); Expr : constant Node_Id := Expression (N); Alt : Node_Id; Len : Nat; Cond : Node_Id; Choice : Node_Id; Chlist : List_Id; begin -- Check for the situation where we know at compile time which -- branch will be taken if Compile_Time_Known_Value (Expr) then Alt := Find_Static_Alternative (N); -- Move the statements from this alternative after the case -- statement. They are already analyzed, so will be skipped -- by the analyzer. Insert_List_After (N, Statements (Alt)); -- That leaves the case statement as a shell. The alternative -- that will be executed is reset to a null list. So now we can -- kill the entire case statement. Kill_Dead_Code (Expression (N)); Kill_Dead_Code (Alternatives (N)); Rewrite (N, Make_Null_Statement (Loc)); return; end if; -- Here if the choice is not determined at compile time declare Last_Alt : constant Node_Id := Last (Alternatives (N)); Others_Present : Boolean; Others_Node : Node_Id; Then_Stms : List_Id; Else_Stms : List_Id; begin if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then Others_Present := True; Others_Node := Last_Alt; else Others_Present := False; end if; -- First step is to worry about possible invalid argument. The RM -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is -- outside the base range), then Constraint_Error must be raised. -- Case of validity check required (validity checks are on, the -- expression is not known to be valid, and the case statement -- comes from source -- no need to validity check internally -- generated case statements). if Validity_Check_Default then Ensure_Valid (Expr); end if; -- If there is only a single alternative, just replace it with -- the sequence of statements since obviously that is what is -- going to be executed in all cases. Len := List_Length (Alternatives (N)); if Len = 1 then -- We still need to evaluate the expression if it has any -- side effects. Remove_Side_Effects (Expression (N)); Insert_List_After (N, Statements (First (Alternatives (N)))); -- That leaves the case statement as a shell. The alternative -- that will be executed is reset to a null list. So now we can -- kill the entire case statement. Kill_Dead_Code (Expression (N)); Rewrite (N, Make_Null_Statement (Loc)); return; end if; -- An optimization. If there are only two alternatives, and only -- a single choice, then rewrite the whole case statement as an -- if statement, since this can result in susbequent optimizations. -- This helps not only with case statements in the source of a -- simple form, but also with generated code (discriminant check -- functions in particular) if Len = 2 then Chlist := Discrete_Choices (First (Alternatives (N))); if List_Length (Chlist) = 1 then Choice := First (Chlist); Then_Stms := Statements (First (Alternatives (N))); Else_Stms := Statements (Last (Alternatives (N))); -- For TRUE, generate "expression", not expression = true if Nkind (Choice) = N_Identifier and then Entity (Choice) = Standard_True then Cond := Expression (N); -- For FALSE, generate "expression" and switch then/else elsif Nkind (Choice) = N_Identifier and then Entity (Choice) = Standard_False then Cond := Expression (N); Else_Stms := Statements (First (Alternatives (N))); Then_Stms := Statements (Last (Alternatives (N))); -- For a range, generate "expression in range" elsif Nkind (Choice) = N_Range or else (Nkind (Choice) = N_Attribute_Reference and then Attribute_Name (Choice) = Name_Range) or else (Is_Entity_Name (Choice) and then Is_Type (Entity (Choice))) or else Nkind (Choice) = N_Subtype_Indication then Cond := Make_In (Loc, Left_Opnd => Expression (N), Right_Opnd => Relocate_Node (Choice)); -- For any other subexpression "expression = value" else Cond := Make_Op_Eq (Loc, Left_Opnd => Expression (N), Right_Opnd => Relocate_Node (Choice)); end if; -- Now rewrite the case as an IF Rewrite (N, Make_If_Statement (Loc, Condition => Cond, Then_Statements => Then_Stms, Else_Statements => Else_Stms)); Analyze (N); return; end if; end if; -- If the last alternative is not an Others choice, replace it -- with an N_Others_Choice. Note that we do not bother to call -- Analyze on the modified case statement, since it's only effect -- would be to compute the contents of the Others_Discrete_Choices -- which is not needed by the back end anyway. -- The reason we do this is that the back end always needs some -- default for a switch, so if we have not supplied one in the -- processing above for validity checking, then we need to -- supply one here. if not Others_Present then Others_Node := Make_Others_Choice (Sloc (Last_Alt)); Set_Others_Discrete_Choices (Others_Node, Discrete_Choices (Last_Alt)); Set_Discrete_Choices (Last_Alt, New_List (Others_Node)); end if; end; end Expand_N_Case_Statement; ----------------------------- -- Expand_N_Exit_Statement -- ----------------------------- -- The only processing required is to deal with a possible C/Fortran -- boolean value used as the condition for the exit statement. procedure Expand_N_Exit_Statement (N : Node_Id) is begin Adjust_Condition (Condition (N)); end Expand_N_Exit_Statement; ----------------------------- -- Expand_N_Goto_Statement -- ----------------------------- -- Add poll before goto if polling active procedure Expand_N_Goto_Statement (N : Node_Id) is begin Generate_Poll_Call (N); end Expand_N_Goto_Statement; --------------------------- -- Expand_N_If_Statement -- --------------------------- -- First we deal with the case of C and Fortran convention boolean -- values, with zero/non-zero semantics. -- Second, we deal with the obvious rewriting for the cases where the -- condition of the IF is known at compile time to be True or False. -- Third, we remove elsif parts which have non-empty Condition_Actions -- and rewrite as independent if statements. For example: -- if x then xs -- elsif y then ys -- ... -- end if; -- becomes -- -- if x then xs -- else -- <> -- if y then ys -- ... -- end if; -- end if; -- This rewriting is needed if at least one elsif part has a non-empty -- Condition_Actions list. We also do the same processing if there is -- a constant condition in an elsif part (in conjunction with the first -- processing step mentioned above, for the recursive call made to deal -- with the created inner if, this deals with properly optimizing the -- cases of constant elsif conditions). procedure Expand_N_If_Statement (N : Node_Id) is Loc : constant Source_Ptr := Sloc (N); Hed : Node_Id; E : Node_Id; New_If : Node_Id; begin Adjust_Condition (Condition (N)); -- The following loop deals with constant conditions for the IF. We -- need a loop because as we eliminate False conditions, we grab the -- first elsif condition and use it as the primary condition. while Compile_Time_Known_Value (Condition (N)) loop -- If condition is True, we can simply rewrite the if statement -- now by replacing it by the series of then statements. if Is_True (Expr_Value (Condition (N))) then -- All the else parts can be killed Kill_Dead_Code (Elsif_Parts (N)); Kill_Dead_Code (Else_Statements (N)); Hed := Remove_Head (Then_Statements (N)); Insert_List_After (N, Then_Statements (N)); Rewrite (N, Hed); return; -- If condition is False, then we can delete the condition and -- the Then statements else -- We do not delete the condition if constant condition -- warnings are enabled, since otherwise we end up deleting -- the desired warning. Of course the backend will get rid -- of this True/False test anyway, so nothing is lost here. if not Constant_Condition_Warnings then Kill_Dead_Code (Condition (N)); end if; Kill_Dead_Code (Then_Statements (N)); -- If there are no elsif statements, then we simply replace -- the entire if statement by the sequence of else statements. if No (Elsif_Parts (N)) then if No (Else_Statements (N)) or else Is_Empty_List (Else_Statements (N)) then Rewrite (N, Make_Null_Statement (Sloc (N))); else Hed := Remove_Head (Else_Statements (N)); Insert_List_After (N, Else_Statements (N)); Rewrite (N, Hed); end if; return; -- If there are elsif statements, the first of them becomes -- the if/then section of the rebuilt if statement This is -- the case where we loop to reprocess this copied condition. else Hed := Remove_Head (Elsif_Parts (N)); Insert_Actions (N, Condition_Actions (Hed)); Set_Condition (N, Condition (Hed)); Set_Then_Statements (N, Then_Statements (Hed)); if Is_Empty_List (Elsif_Parts (N)) then Set_Elsif_Parts (N, No_List); end if; end if; end if; end loop; -- Loop through elsif parts, dealing with constant conditions and -- possible expression actions that are present. if Present (Elsif_Parts (N)) then E := First (Elsif_Parts (N)); while Present (E) loop Adjust_Condition (Condition (E)); -- If there are condition actions, then we rewrite the if -- statement as indicated above. We also do the same rewrite -- if the condition is True or False. The further processing -- of this constant condition is then done by the recursive -- call to expand the newly created if statement if Present (Condition_Actions (E)) or else Compile_Time_Known_Value (Condition (E)) then -- Note this is not an implicit if statement, since it is -- part of an explicit if statement in the source (or of an -- implicit if statement that has already been tested). New_If := Make_If_Statement (Sloc (E), Condition => Condition (E), Then_Statements => Then_Statements (E), Elsif_Parts => No_List, Else_Statements => Else_Statements (N)); -- Elsif parts for new if come from remaining elsif's of parent while Present (Next (E)) loop if No (Elsif_Parts (New_If)) then Set_Elsif_Parts (New_If, New_List); end if; Append (Remove_Next (E), Elsif_Parts (New_If)); end loop; Set_Else_Statements (N, New_List (New_If)); if Present (Condition_Actions (E)) then Insert_List_Before (New_If, Condition_Actions (E)); end if; Remove (E); if Is_Empty_List (Elsif_Parts (N)) then Set_Elsif_Parts (N, No_List); end if; Analyze (New_If); return; -- No special processing for that elsif part, move to next else Next (E); end if; end loop; end if; -- Some more optimizations applicable if we still have an IF statement if Nkind (N) /= N_If_Statement then return; end if; -- Another optimization, special cases that can be simplified -- if expression then -- return true; -- else -- return false; -- end if; -- can be changed to: -- return expression; -- and -- if expression then -- return false; -- else -- return true; -- end if; -- can be changed to: -- return not (expression); if Nkind (N) = N_If_Statement and then No (Elsif_Parts (N)) and then Present (Else_Statements (N)) and then List_Length (Then_Statements (N)) = 1 and then List_Length (Else_Statements (N)) = 1 then declare Then_Stm : constant Node_Id := First (Then_Statements (N)); Else_Stm : constant Node_Id := First (Else_Statements (N)); begin if Nkind (Then_Stm) = N_Return_Statement and then Nkind (Else_Stm) = N_Return_Statement then declare Then_Expr : constant Node_Id := Expression (Then_Stm); Else_Expr : constant Node_Id := Expression (Else_Stm); begin if Nkind (Then_Expr) = N_Identifier and then Nkind (Else_Expr) = N_Identifier then if Entity (Then_Expr) = Standard_True and then Entity (Else_Expr) = Standard_False then Rewrite (N, Make_Return_Statement (Loc, Expression => Relocate_Node (Condition (N)))); Analyze (N); return; elsif Entity (Then_Expr) = Standard_False and then Entity (Else_Expr) = Standard_True then Rewrite (N, Make_Return_Statement (Loc, Expression => Make_Op_Not (Loc, Right_Opnd => Relocate_Node (Condition (N))))); Analyze (N); return; end if; end if; end; end if; end; end if; end Expand_N_If_Statement; ----------------------------- -- Expand_N_Loop_Statement -- ----------------------------- -- 1. Deal with while condition for C/Fortran boolean -- 2. Deal with loops with a non-standard enumeration type range -- 3. Deal with while loops where Condition_Actions is set -- 4. Insert polling call if required procedure Expand_N_Loop_Statement (N : Node_Id) is Loc : constant Source_Ptr := Sloc (N); Isc : constant Node_Id := Iteration_Scheme (N); begin if Present (Isc) then Adjust_Condition (Condition (Isc)); end if; if Is_Non_Empty_List (Statements (N)) then Generate_Poll_Call (First (Statements (N))); end if; if No (Isc) then return; end if; -- Handle the case where we have a for loop with the range type being -- an enumeration type with non-standard representation. In this case -- we expand: -- for x in [reverse] a .. b loop -- ... -- end loop; -- to -- for xP in [reverse] integer -- range etype'Pos (a) .. etype'Pos (b) loop -- declare -- x : constant etype := Pos_To_Rep (xP); -- begin -- ... -- end; -- end loop; if Present (Loop_Parameter_Specification (Isc)) then declare LPS : constant Node_Id := Loop_Parameter_Specification (Isc); Loop_Id : constant Entity_Id := Defining_Identifier (LPS); Ltype : constant Entity_Id := Etype (Loop_Id); Btype : constant Entity_Id := Base_Type (Ltype); Expr : Node_Id; New_Id : Entity_Id; begin if not Is_Enumeration_Type (Btype) or else No (Enum_Pos_To_Rep (Btype)) then return; end if; New_Id := Make_Defining_Identifier (Loc, Chars => New_External_Name (Chars (Loop_Id), 'P')); -- If the type has a contiguous representation, successive -- values can be generated as offsets from the first literal. if Has_Contiguous_Rep (Btype) then Expr := Unchecked_Convert_To (Btype, Make_Op_Add (Loc, Left_Opnd => Make_Integer_Literal (Loc, Enumeration_Rep (First_Literal (Btype))), Right_Opnd => New_Reference_To (New_Id, Loc))); else -- Use the constructed array Enum_Pos_To_Rep. Expr := Make_Indexed_Component (Loc, Prefix => New_Reference_To (Enum_Pos_To_Rep (Btype), Loc), Expressions => New_List (New_Reference_To (New_Id, Loc))); end if; Rewrite (N, Make_Loop_Statement (Loc, Identifier => Identifier (N), Iteration_Scheme => Make_Iteration_Scheme (Loc, Loop_Parameter_Specification => Make_Loop_Parameter_Specification (Loc, Defining_Identifier => New_Id, Reverse_Present => Reverse_Present (LPS), Discrete_Subtype_Definition => Make_Subtype_Indication (Loc, Subtype_Mark => New_Reference_To (Standard_Natural, Loc), Constraint => Make_Range_Constraint (Loc, Range_Expression => Make_Range (Loc, Low_Bound => Make_Attribute_Reference (Loc, Prefix => New_Reference_To (Btype, Loc), Attribute_Name => Name_Pos, Expressions => New_List ( Relocate_Node (Type_Low_Bound (Ltype)))), High_Bound => Make_Attribute_Reference (Loc, Prefix => New_Reference_To (Btype, Loc), Attribute_Name => Name_Pos, Expressions => New_List ( Relocate_Node (Type_High_Bound (Ltype))))))))), Statements => New_List ( Make_Block_Statement (Loc, Declarations => New_List ( Make_Object_Declaration (Loc, Defining_Identifier => Loop_Id, Constant_Present => True, Object_Definition => New_Reference_To (Ltype, Loc), Expression => Expr)), Handled_Statement_Sequence => Make_Handled_Sequence_Of_Statements (Loc, Statements => Statements (N)))), End_Label => End_Label (N))); Analyze (N); end; -- Second case, if we have a while loop with Condition_Actions set, -- then we change it into a plain loop: -- while C loop -- ... -- end loop; -- changed to: -- loop -- <> -- exit when not C; -- ... -- end loop elsif Present (Isc) and then Present (Condition_Actions (Isc)) then declare ES : Node_Id; begin ES := Make_Exit_Statement (Sloc (Condition (Isc)), Condition => Make_Op_Not (Sloc (Condition (Isc)), Right_Opnd => Condition (Isc))); Prepend (ES, Statements (N)); Insert_List_Before (ES, Condition_Actions (Isc)); -- This is not an implicit loop, since it is generated in -- response to the loop statement being processed. If this -- is itself implicit, the restriction has already been -- checked. If not, it is an explicit loop. Rewrite (N, Make_Loop_Statement (Sloc (N), Identifier => Identifier (N), Statements => Statements (N), End_Label => End_Label (N))); Analyze (N); end; end if; end Expand_N_Loop_Statement; ------------------------------- -- Expand_N_Return_Statement -- ------------------------------- procedure Expand_N_Return_Statement (N : Node_Id) is Loc : constant Source_Ptr := Sloc (N); Exp : constant Node_Id := Expression (N); Exptyp : Entity_Id; T : Entity_Id; Utyp : Entity_Id; Scope_Id : Entity_Id; Kind : Entity_Kind; Call : Node_Id; Acc_Stat : Node_Id; Goto_Stat : Node_Id; Lab_Node : Node_Id; Cur_Idx : Nat; Return_Type : Entity_Id; Result_Exp : Node_Id; Result_Id : Entity_Id; Result_Obj : Node_Id; begin -- Case where returned expression is present if Present (Exp) then -- Always normalize C/Fortran boolean result. This is not always -- necessary, but it seems a good idea to minimize the passing -- around of non-normalized values, and in any case this handles -- the processing of barrier functions for protected types, which -- turn the condition into a return statement. Exptyp := Etype (Exp); if Is_Boolean_Type (Exptyp) and then Nonzero_Is_True (Exptyp) then Adjust_Condition (Exp); Adjust_Result_Type (Exp, Exptyp); end if; -- Do validity check if enabled for returns if Validity_Checks_On and then Validity_Check_Returns then Ensure_Valid (Exp); end if; end if; -- Find relevant enclosing scope from which return is returning Cur_Idx := Scope_Stack.Last; loop Scope_Id := Scope_Stack.Table (Cur_Idx).Entity; if Ekind (Scope_Id) /= E_Block and then Ekind (Scope_Id) /= E_Loop then exit; else Cur_Idx := Cur_Idx - 1; pragma Assert (Cur_Idx >= 0); end if; end loop; if No (Exp) then Kind := Ekind (Scope_Id); -- If it is a return from procedures do no extra steps. if Kind = E_Procedure or else Kind = E_Generic_Procedure then return; end if; pragma Assert (Is_Entry (Scope_Id)); -- Look at the enclosing block to see whether the return is from -- an accept statement or an entry body. for J in reverse 0 .. Cur_Idx loop Scope_Id := Scope_Stack.Table (J).Entity; exit when Is_Concurrent_Type (Scope_Id); end loop; -- If it is a return from accept statement it should be expanded -- as a call to RTS Complete_Rendezvous and a goto to the end of -- the accept body. -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept, -- Expand_N_Accept_Alternative in exp_ch9.adb) if Is_Task_Type (Scope_Id) then Call := (Make_Procedure_Call_Statement (Loc, Name => New_Reference_To (RTE (RE_Complete_Rendezvous), Loc))); Insert_Before (N, Call); -- why not insert actions here??? Analyze (Call); Acc_Stat := Parent (N); while Nkind (Acc_Stat) /= N_Accept_Statement loop Acc_Stat := Parent (Acc_Stat); end loop; Lab_Node := Last (Statements (Handled_Statement_Sequence (Acc_Stat))); Goto_Stat := Make_Goto_Statement (Loc, Name => New_Occurrence_Of (Entity (Identifier (Lab_Node)), Loc)); Set_Analyzed (Goto_Stat); Rewrite (N, Goto_Stat); Analyze (N); -- If it is a return from an entry body, put a Complete_Entry_Body -- call in front of the return. elsif Is_Protected_Type (Scope_Id) then Call := Make_Procedure_Call_Statement (Loc, Name => New_Reference_To (RTE (RE_Complete_Entry_Body), Loc), Parameter_Associations => New_List (Make_Attribute_Reference (Loc, Prefix => New_Reference_To (Object_Ref (Corresponding_Body (Parent (Scope_Id))), Loc), Attribute_Name => Name_Unchecked_Access))); Insert_Before (N, Call); Analyze (Call); end if; return; end if; T := Etype (Exp); Return_Type := Etype (Scope_Id); Utyp := Underlying_Type (Return_Type); -- Check the result expression of a scalar function against -- the subtype of the function by inserting a conversion. -- This conversion must eventually be performed for other -- classes of types, but for now it's only done for scalars. -- ??? if Is_Scalar_Type (T) then Rewrite (Exp, Convert_To (Return_Type, Exp)); Analyze (Exp); end if; -- Implement the rules of 6.5(8-10), which require a tag check in -- the case of a limited tagged return type, and tag reassignment -- for nonlimited tagged results. These actions are needed when -- the return type is a specific tagged type and the result -- expression is a conversion or a formal parameter, because in -- that case the tag of the expression might differ from the tag -- of the specific result type. if Is_Tagged_Type (Utyp) and then not Is_Class_Wide_Type (Utyp) and then (Nkind (Exp) = N_Type_Conversion or else Nkind (Exp) = N_Unchecked_Type_Conversion or else (Is_Entity_Name (Exp) and then Ekind (Entity (Exp)) in Formal_Kind)) then -- When the return type is limited, perform a check that the -- tag of the result is the same as the tag of the return type. if Is_Limited_Type (Return_Type) then Insert_Action (Exp, Make_Raise_Constraint_Error (Loc, Condition => Make_Op_Ne (Loc, Left_Opnd => Make_Selected_Component (Loc, Prefix => Duplicate_Subexpr (Exp), Selector_Name => New_Reference_To (Tag_Component (Utyp), Loc)), Right_Opnd => Unchecked_Convert_To (RTE (RE_Tag), New_Reference_To (Access_Disp_Table (Base_Type (Utyp)), Loc))), Reason => CE_Tag_Check_Failed)); -- If the result type is a specific nonlimited tagged type, -- then we have to ensure that the tag of the result is that -- of the result type. This is handled by making a copy of the -- expression in the case where it might have a different tag, -- namely when the expression is a conversion or a formal -- parameter. We create a new object of the result type and -- initialize it from the expression, which will implicitly -- force the tag to be set appropriately. else Result_Id := Make_Defining_Identifier (Loc, New_Internal_Name ('R')); Result_Exp := New_Reference_To (Result_Id, Loc); Result_Obj := Make_Object_Declaration (Loc, Defining_Identifier => Result_Id, Object_Definition => New_Reference_To (Return_Type, Loc), Constant_Present => True, Expression => Relocate_Node (Exp)); Set_Assignment_OK (Result_Obj); Insert_Action (Exp, Result_Obj); Rewrite (Exp, Result_Exp); Analyze_And_Resolve (Exp, Return_Type); end if; end if; -- Deal with returning variable length objects and controlled types -- Nothing to do if we are returning by reference, or this is not -- a type that requires special processing (indicated by the fact -- that it requires a cleanup scope for the secondary stack case) if Is_Return_By_Reference_Type (T) or else not Requires_Transient_Scope (Return_Type) then null; -- Case of secondary stack not used elsif Function_Returns_With_DSP (Scope_Id) then -- Here what we need to do is to always return by reference, since -- we will return with the stack pointer depressed. We may need to -- do a copy to a local temporary before doing this return. No_Secondary_Stack_Case : declare Local_Copy_Required : Boolean := False; -- Set to True if a local copy is required Copy_Ent : Entity_Id; -- Used for the target entity if a copy is required Decl : Node_Id; -- Declaration used to create copy if needed procedure Test_Copy_Required (Expr : Node_Id); -- Determines if Expr represents a return value for which a -- copy is required. More specifically, a copy is not required -- if Expr represents an object or component of an object that -- is either in the local subprogram frame, or is constant. -- If a copy is required, then Local_Copy_Required is set True. ------------------------ -- Test_Copy_Required -- ------------------------ procedure Test_Copy_Required (Expr : Node_Id) is Ent : Entity_Id; begin -- If component, test prefix (object containing component) if Nkind (Expr) = N_Indexed_Component or else Nkind (Expr) = N_Selected_Component then Test_Copy_Required (Prefix (Expr)); return; -- See if we have an entity name elsif Is_Entity_Name (Expr) then Ent := Entity (Expr); -- Constant entity is always OK, no copy required if Ekind (Ent) = E_Constant then return; -- No copy required for local variable elsif Ekind (Ent) = E_Variable and then Scope (Ent) = Current_Subprogram then return; end if; end if; -- All other cases require a copy Local_Copy_Required := True; end Test_Copy_Required; -- Start of processing for No_Secondary_Stack_Case begin -- No copy needed if result is from a function call. -- In this case the result is already being returned by -- reference with the stack pointer depressed. -- To make up for a gcc 2.8.1 deficiency (???), we perform -- the copy for array types if the constrained status of the -- target type is different from that of the expression. if Requires_Transient_Scope (T) and then (not Is_Array_Type (T) or else Is_Constrained (T) = Is_Constrained (Return_Type) or else Controlled_Type (T)) and then Nkind (Exp) = N_Function_Call then Set_By_Ref (N); -- We always need a local copy for a controlled type, since -- we are required to finalize the local value before return. -- The copy will automatically include the required finalize. -- Moreover, gigi cannot make this copy, since we need special -- processing to ensure proper behavior for finalization. -- Note: the reason we are returning with a depressed stack -- pointer in the controlled case (even if the type involved -- is constrained) is that we must make a local copy to deal -- properly with the requirement that the local result be -- finalized. elsif Controlled_Type (Utyp) then Copy_Ent := Make_Defining_Identifier (Loc, Chars => New_Internal_Name ('R')); -- Build declaration to do the copy, and insert it, setting -- Assignment_OK, because we may be copying a limited type. -- In addition we set the special flag to inhibit finalize -- attachment if this is a controlled type (since this attach -- must be done by the caller, otherwise if we attach it here -- we will finalize the returned result prematurely). Decl := Make_Object_Declaration (Loc, Defining_Identifier => Copy_Ent, Object_Definition => New_Occurrence_Of (Return_Type, Loc), Expression => Relocate_Node (Exp)); Set_Assignment_OK (Decl); Set_Delay_Finalize_Attach (Decl); Insert_Action (N, Decl); -- Now the actual return uses the copied value Rewrite (Exp, New_Occurrence_Of (Copy_Ent, Loc)); Analyze_And_Resolve (Exp, Return_Type); -- Since we have made the copy, gigi does not have to, so -- we set the By_Ref flag to prevent another copy being made. Set_By_Ref (N); -- Non-controlled cases else Test_Copy_Required (Exp); -- If a local copy is required, then gigi will make the -- copy, otherwise, we can return the result directly, -- so set By_Ref to suppress the gigi copy. if not Local_Copy_Required then Set_By_Ref (N); end if; end if; end No_Secondary_Stack_Case; -- Here if secondary stack is used else -- Make sure that no surrounding block will reclaim the -- secondary-stack on which we are going to put the result. -- Not only may this introduce secondary stack leaks but worse, -- if the reclamation is done too early, then the result we are -- returning may get clobbered. See example in 7417-003. declare S : Entity_Id := Current_Scope; begin while Ekind (S) = E_Block or else Ekind (S) = E_Loop loop Set_Sec_Stack_Needed_For_Return (S, True); S := Enclosing_Dynamic_Scope (S); end loop; end; -- Optimize the case where the result is a function call. In this -- case either the result is already on the secondary stack, or is -- already being returned with the stack pointer depressed and no -- further processing is required except to set the By_Ref flag to -- ensure that gigi does not attempt an extra unnecessary copy. -- (actually not just unnecessary but harmfully wrong in the case -- of a controlled type, where gigi does not know how to do a copy). -- To make up for a gcc 2.8.1 deficiency (???), we perform -- the copy for array types if the constrained status of the -- target type is different from that of the expression. if Requires_Transient_Scope (T) and then (not Is_Array_Type (T) or else Is_Constrained (T) = Is_Constrained (Return_Type) or else Controlled_Type (T)) and then Nkind (Exp) = N_Function_Call then Set_By_Ref (N); -- For controlled types, do the allocation on the sec-stack -- manually in order to call adjust at the right time -- type Anon1 is access Return_Type; -- for Anon1'Storage_pool use ss_pool; -- Anon2 : anon1 := new Return_Type'(expr); -- return Anon2.all; elsif Controlled_Type (Utyp) then declare Loc : constant Source_Ptr := Sloc (N); Temp : constant Entity_Id := Make_Defining_Identifier (Loc, Chars => New_Internal_Name ('R')); Acc_Typ : constant Entity_Id := Make_Defining_Identifier (Loc, Chars => New_Internal_Name ('A')); Alloc_Node : Node_Id; begin Set_Ekind (Acc_Typ, E_Access_Type); Set_Associated_Storage_Pool (Acc_Typ, RTE (RE_SS_Pool)); Alloc_Node := Make_Allocator (Loc, Expression => Make_Qualified_Expression (Loc, Subtype_Mark => New_Reference_To (Etype (Exp), Loc), Expression => Relocate_Node (Exp))); Insert_List_Before_And_Analyze (N, New_List ( Make_Full_Type_Declaration (Loc, Defining_Identifier => Acc_Typ, Type_Definition => Make_Access_To_Object_Definition (Loc, Subtype_Indication => New_Reference_To (Return_Type, Loc))), Make_Object_Declaration (Loc, Defining_Identifier => Temp, Object_Definition => New_Reference_To (Acc_Typ, Loc), Expression => Alloc_Node))); Rewrite (Exp, Make_Explicit_Dereference (Loc, Prefix => New_Reference_To (Temp, Loc))); Analyze_And_Resolve (Exp, Return_Type); end; -- Otherwise use the gigi mechanism to allocate result on the -- secondary stack. else Set_Storage_Pool (N, RTE (RE_SS_Pool)); -- If we are generating code for the Java VM do not use -- SS_Allocate since everything is heap-allocated anyway. if not Java_VM then Set_Procedure_To_Call (N, RTE (RE_SS_Allocate)); end if; end if; end if; exception when RE_Not_Available => return; end Expand_N_Return_Statement; ------------------------------ -- Make_Tag_Ctrl_Assignment -- ------------------------------ function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is Loc : constant Source_Ptr := Sloc (N); L : constant Node_Id := Name (N); T : constant Entity_Id := Underlying_Type (Etype (L)); Ctrl_Act : constant Boolean := Controlled_Type (T) and then not No_Ctrl_Actions (N); Save_Tag : constant Boolean := Is_Tagged_Type (T) and then not No_Ctrl_Actions (N) and then not Java_VM; -- Tags are not saved and restored when Java_VM because JVM tags -- are represented implicitly in objects. Res : List_Id; Tag_Tmp : Entity_Id; Prev_Tmp : Entity_Id; Next_Tmp : Entity_Id; Ctrl_Ref : Node_Id; Ctrl_Ref2 : Node_Id := Empty; Prev_Tmp2 : Entity_Id := Empty; -- prevent warning Next_Tmp2 : Entity_Id := Empty; -- prevent warning begin Res := New_List; -- Finalize the target of the assignment when controlled. -- We have two exceptions here: -- 1. If we are in an init proc since it is an initialization -- more than an assignment -- 2. If the left-hand side is a temporary that was not initialized -- (or the parent part of a temporary since it is the case in -- extension aggregates). Such a temporary does not come from -- source. We must examine the original node for the prefix, because -- it may be a component of an entry formal, in which case it has -- been rewritten and does not appear to come from source either. -- Case of init proc if not Ctrl_Act then null; -- The left hand side is an uninitialized temporary elsif Nkind (L) = N_Type_Conversion and then Is_Entity_Name (Expression (L)) and then No_Initialization (Parent (Entity (Expression (L)))) then null; else Append_List_To (Res, Make_Final_Call ( Ref => Duplicate_Subexpr_No_Checks (L), Typ => Etype (L), With_Detach => New_Reference_To (Standard_False, Loc))); end if; Next_Tmp := Make_Defining_Identifier (Loc, New_Internal_Name ('C')); -- 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 (Tag_Component (T), Loc)))); -- Otherwise Tag_Tmp not used else Tag_Tmp := Empty; end if; -- 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 and if it is also -- Is_Controlled, we need to save the object pointers as well. if Ctrl_Act then Ctrl_Ref := Duplicate_Subexpr_No_Checks (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)); if Is_Controlled (T) then Ctrl_Ref2 := Duplicate_Subexpr_No_Checks (L); end if; 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, 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)))); if Present (Ctrl_Ref2) then Prev_Tmp2 := Make_Defining_Identifier (Loc, New_Internal_Name ('B')); Append_To (Res, Make_Object_Declaration (Loc, Defining_Identifier => Prev_Tmp2, Object_Definition => New_Reference_To (RTE (RE_Finalizable_Ptr), Loc), Expression => Make_Selected_Component (Loc, Prefix => Unchecked_Convert_To (RTE (RE_Finalizable), Ctrl_Ref2), Selector_Name => Make_Identifier (Loc, Name_Prev)))); Next_Tmp2 := Make_Defining_Identifier (Loc, New_Internal_Name ('C')); Append_To (Res, Make_Object_Declaration (Loc, Defining_Identifier => Next_Tmp2, 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_Ref2)), Selector_Name => Make_Identifier (Loc, Name_Next)))); end if; -- If not controlled type, then Prev_Tmp and Ctrl_Ref unused else Prev_Tmp := Empty; Ctrl_Ref := Empty; end if; -- Do the Assignment Append_To (Res, Relocate_Node (N)); -- 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 (Tag_Component (T), Loc)), Expression => New_Reference_To (Tag_Tmp, Loc))); end if; -- Restore the finalization pointers if Ctrl_Act then 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))); if Present (Ctrl_Ref2) then Append_To (Res, Make_Assignment_Statement (Loc, Name => Make_Selected_Component (Loc, Prefix => Unchecked_Convert_To (RTE (RE_Finalizable), New_Copy_Tree (Ctrl_Ref2)), Selector_Name => Make_Identifier (Loc, Name_Prev)), Expression => New_Reference_To (Prev_Tmp2, Loc))); Append_To (Res, Make_Assignment_Statement (Loc, Name => Make_Selected_Component (Loc, Prefix => Unchecked_Convert_To (RTE (RE_Finalizable), New_Copy_Tree (Ctrl_Ref2)), Selector_Name => Make_Identifier (Loc, Name_Next)), Expression => New_Reference_To (Next_Tmp2, Loc))); end if; end if; -- Adjust the target after the assignment when controlled. (not in -- the init proc since it is an initialization more than an -- assignment) if Ctrl_Act then Append_List_To (Res, Make_Adjust_Call ( Ref => Duplicate_Subexpr_Move_Checks (L), Typ => Etype (L), Flist_Ref => New_Reference_To (RTE (RE_Global_Final_List), Loc), With_Attach => Make_Integer_Literal (Loc, 0))); end if; return Res; exception when RE_Not_Available => return Empty_List; end Make_Tag_Ctrl_Assignment; ------------------------------------ -- Possible_Bit_Aligned_Component -- ------------------------------------ function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean is begin case Nkind (N) is -- Case of indexed component when N_Indexed_Component => declare P : constant Node_Id := Prefix (N); Ptyp : constant Entity_Id := Etype (P); begin -- If we know the component size and it is less than 64, then -- we are definitely OK. The back end always does assignment -- of misaligned small objects correctly. if Known_Static_Component_Size (Ptyp) and then Component_Size (Ptyp) <= 64 then return False; -- Otherwise, we need to test the prefix, to see if we are -- indexing from a possibly unaligned component. else return Possible_Bit_Aligned_Component (P); end if; end; -- Case of selected component when N_Selected_Component => declare P : constant Node_Id := Prefix (N); Comp : constant Entity_Id := Entity (Selector_Name (N)); begin -- If there is no component clause, then we are in the clear -- since the back end will never misalign a large component -- unless it is forced to do so. In the clear means we need -- only the recursive test on the prefix. if Component_May_Be_Bit_Aligned (Comp) then return True; else return Possible_Bit_Aligned_Component (P); end if; end; -- If we have neither a record nor array component, it means that -- we have fallen off the top testing prefixes recursively, and -- we now have a stand alone object, where we don't have a problem when others => return False; end case; end Possible_Bit_Aligned_Component; end Exp_Ch5;