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Diffstat (limited to 'gcc-4.2.1/gcc/ada/exp_ch5.adb')
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1 files changed, 0 insertions, 3685 deletions
diff --git a/gcc-4.2.1/gcc/ada/exp_ch5.adb b/gcc-4.2.1/gcc/ada/exp_ch5.adb deleted file mode 100644 index 924e3e53d..000000000 --- a/gcc-4.2.1/gcc/ada/exp_ch5.adb +++ /dev/null @@ -1,3685 +0,0 @@ ------------------------------------------------------------------------------- --- -- --- GNAT COMPILER COMPONENTS -- --- -- --- E X P _ C H 5 -- --- -- --- B o d y -- --- -- --- Copyright (C) 1992-2006, Free Software Foundation, Inc. -- --- -- --- GNAT is free software; you can redistribute it and/or modify it under -- --- terms of the GNU General Public License as published by the Free Soft- -- --- ware Foundation; either version 2, or (at your option) any later ver- -- --- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- --- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- --- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- --- for more details. You should have received a copy of the GNU General -- --- Public License distributed with GNAT; see file COPYING. If not, write -- --- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- --- Boston, MA 02110-1301, USA. -- --- -- --- GNAT was originally developed by the GNAT team at New York University. -- --- Extensive contributions were provided by Ada Core Technologies Inc. -- --- -- ------------------------------------------------------------------------------- - -with Atree; use Atree; -with Checks; use Checks; -with Einfo; use Einfo; -with Elists; use Elists; -with Exp_Aggr; use Exp_Aggr; -with Exp_Ch7; use Exp_Ch7; -with Exp_Ch11; use Exp_Ch11; -with Exp_Dbug; use Exp_Dbug; -with Exp_Pakd; use Exp_Pakd; -with Exp_Tss; use Exp_Tss; -with Exp_Util; use Exp_Util; -with Hostparm; use Hostparm; -with Nlists; use Nlists; -with Nmake; use Nmake; -with Opt; use Opt; -with Restrict; use Restrict; -with Rident; use Rident; -with Rtsfind; use Rtsfind; -with Sinfo; use Sinfo; -with Sem; use Sem; -with Sem_Ch3; use Sem_Ch3; -with Sem_Ch5; use Sem_Ch5; -with Sem_Ch8; use Sem_Ch8; -with Sem_Ch13; use Sem_Ch13; -with Sem_Eval; use Sem_Eval; -with Sem_Res; use Sem_Res; -with Sem_Util; use Sem_Util; -with Snames; use Snames; -with Stand; use Stand; -with Stringt; use Stringt; -with Tbuild; use Tbuild; -with Ttypes; use Ttypes; -with Uintp; use Uintp; -with Validsw; use Validsw; - -package body Exp_Ch5 is - - function Change_Of_Representation (N : Node_Id) return Boolean; - -- Determine if the right hand side of the assignment N is a type - -- conversion which requires a change of representation. Called - -- only for the array and record cases. - - procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id); - -- N is an assignment which assigns an array value. This routine process - -- the various special cases and checks required for such assignments, - -- including change of representation. Rhs is normally simply the right - -- hand side of the assignment, except that if the right hand side is - -- a type conversion or a qualified expression, then the Rhs is the - -- actual expression inside any such type conversions or qualifications. - - function Expand_Assign_Array_Loop - (N : Node_Id; - Larray : Entity_Id; - Rarray : Entity_Id; - L_Type : Entity_Id; - R_Type : Entity_Id; - Ndim : Pos; - Rev : Boolean) return Node_Id; - -- N is an assignment statement which assigns an array value. This routine - -- expands the assignment into a loop (or nested loops for the case of a - -- multi-dimensional array) to do the assignment component by component. - -- Larray and Rarray are the entities of the actual arrays on the left - -- hand and right hand sides. L_Type and R_Type are the types of these - -- arrays (which may not be the same, due to either sliding, or to a - -- change of representation case). Ndim is the number of dimensions and - -- the parameter Rev indicates if the loops run normally (Rev = False), - -- or reversed (Rev = True). The value returned is the constructed - -- loop statement. Auxiliary declarations are inserted before node N - -- using the standard Insert_Actions mechanism. - - procedure Expand_Assign_Record (N : Node_Id); - -- N is an assignment of a non-tagged record value. This routine handles - -- the case where the assignment must be made component by component, - -- either because the target is not byte aligned, or there is a change - -- of representation. - - function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id; - -- Generate the necessary code for controlled and tagged assignment, - -- that is to say, finalization of the target before, adjustement of - -- the target after and save and restore of the tag and finalization - -- pointers which are not 'part of the value' and must not be changed - -- upon assignment. N is the original Assignment node. - - function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean; - -- This function is used in processing the assignment of a record or - -- indexed component. The argument N is either the left hand or right - -- hand side of an assignment, and this function determines if there - -- is a record component reference where the record may be bit aligned - -- in a manner that causes trouble for the back end (see description - -- of Exp_Util.Component_May_Be_Bit_Aligned for further details). - - ------------------------------ - -- Change_Of_Representation -- - ------------------------------ - - function Change_Of_Representation (N : Node_Id) return Boolean is - Rhs : constant Node_Id := Expression (N); - begin - return - Nkind (Rhs) = N_Type_Conversion - and then - not Same_Representation (Etype (Rhs), Etype (Expression (Rhs))); - end Change_Of_Representation; - - ------------------------- - -- Expand_Assign_Array -- - ------------------------- - - -- There are two issues here. First, do we let Gigi do a block move, or - -- do we expand out into a loop? Second, we need to set the two flags - -- Forwards_OK and Backwards_OK which show whether the block move (or - -- corresponding loops) can be legitimately done in a forwards (low to - -- high) or backwards (high to low) manner. - - procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - - Lhs : constant Node_Id := Name (N); - - Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs); - Act_Rhs : Node_Id := Get_Referenced_Object (Rhs); - - L_Type : constant Entity_Id := - Underlying_Type (Get_Actual_Subtype (Act_Lhs)); - R_Type : Entity_Id := - Underlying_Type (Get_Actual_Subtype (Act_Rhs)); - - L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice; - R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice; - - Crep : constant Boolean := Change_Of_Representation (N); - - Larray : Node_Id; - Rarray : Node_Id; - - Ndim : constant Pos := Number_Dimensions (L_Type); - - Loop_Required : Boolean := False; - -- This switch is set to True if the array move must be done using - -- an explicit front end generated loop. - - 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; - - -- If object is atomic, we cannot tolerate a loop - - elsif Is_Atomic_Object (Act_Lhs) - or else - Is_Atomic_Object (Act_Rhs) - then - return; - - -- Loop is required if we have atomic components since we have to - -- be sure to do any accesses on an element by element basis. - - elsif Has_Atomic_Components (L_Type) - or else Has_Atomic_Components (R_Type) - or else Is_Atomic (Component_Type (L_Type)) - or else Is_Atomic (Component_Type (R_Type)) - then - Loop_Required := True; - - -- Case where no slice is involved - - elsif not L_Slice and not R_Slice then - - -- The following code deals with the case of unconstrained bit - -- packed arrays. The problem is that the template for such - -- arrays contains the bounds of the actual source level array, - - -- But the copy of an entire array requires the bounds of the - -- underlying array. It would be nice if the back end could take - -- care of this, but right now it does not know how, so if we - -- have such a type, then we expand out into a loop, which is - -- inefficient but works correctly. If we don't do this, we - -- get the wrong length computed for the array to be moved. - -- The two cases we need to worry about are: - - -- Explicit deference of an unconstrained packed array type as - -- in the following example: - - -- procedure C52 is - -- type BITS is array(INTEGER range <>) of BOOLEAN; - -- pragma PACK(BITS); - -- type A is access BITS; - -- P1,P2 : A; - -- begin - -- P1 := new BITS (1 .. 65_535); - -- P2 := new BITS (1 .. 65_535); - -- P2.ALL := P1.ALL; - -- end C52; - - -- A formal parameter reference with an unconstrained bit - -- array type is the other case we need to worry about (here - -- we assume the same BITS type declared above: - - -- procedure Write_All (File : out BITS; Contents : in BITS); - -- begin - -- File.Storage := Contents; - -- end Write_All; - - -- We expand to a loop in either of these two cases - - -- Question for future thought. Another potentially more efficient - -- approach would be to create the actual subtype, and then do an - -- unchecked conversion to this actual subtype ??? - - Check_Unconstrained_Bit_Packed_Array : declare - - function Is_UBPA_Reference (Opnd : Node_Id) return Boolean; - -- Function to perform required test for the first case, - -- above (dereference of an unconstrained bit packed array) - - ----------------------- - -- Is_UBPA_Reference -- - ----------------------- - - function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is - Typ : constant Entity_Id := Underlying_Type (Etype (Opnd)); - P_Type : Entity_Id; - Des_Type : Entity_Id; - - begin - if Present (Packed_Array_Type (Typ)) - and then Is_Array_Type (Packed_Array_Type (Typ)) - and then not Is_Constrained (Packed_Array_Type (Typ)) - then - return True; - - elsif Nkind (Opnd) = N_Explicit_Dereference then - P_Type := Underlying_Type (Etype (Prefix (Opnd))); - - if not Is_Access_Type (P_Type) then - return False; - - else - Des_Type := Designated_Type (P_Type); - return - Is_Bit_Packed_Array (Des_Type) - and then not Is_Constrained (Des_Type); - end if; - - else - return False; - end if; - end Is_UBPA_Reference; - - -- Start of processing for Check_Unconstrained_Bit_Packed_Array - - begin - if Is_UBPA_Reference (Lhs) - or else - Is_UBPA_Reference (Rhs) - then - Loop_Required := True; - - -- Here if we do not have the case of a reference to a bit - -- packed unconstrained array case. In this case gigi can - -- most certainly handle the assignment if a forwards move - -- is allowed. - - -- (could it handle the backwards case also???) - - elsif Forwards_OK (N) then - return; - end if; - end Check_Unconstrained_Bit_Packed_Array; - - -- The back end can always handle the assignment if the right side is a - -- string literal (note that overlap is definitely impossible in this - -- case). If the type is packed, a string literal is always converted - -- into aggregate, except in the case of a null slice, for which no - -- aggregate can be written. In that case, rewrite the assignment as a - -- null statement, a length check has already been emitted to verify - -- that the range of the left-hand side is empty. - - -- Note that this code is not executed if we had an assignment of - -- a string literal to a non-bit aligned component of a record, a - -- case which cannot be handled by the backend - - elsif Nkind (Rhs) = N_String_Literal then - if String_Length (Strval (Rhs)) = 0 - and then Is_Bit_Packed_Array (L_Type) - then - Rewrite (N, Make_Null_Statement (Loc)); - Analyze (N); - end if; - - return; - - -- If either operand is bit packed, then we need a loop, since we - -- can't be sure that the slice is byte aligned. Similarly, if either - -- operand is a possibly unaligned slice, then we need a loop (since - -- the back end cannot handle unaligned slices). - - elsif Is_Bit_Packed_Array (L_Type) - or else Is_Bit_Packed_Array (R_Type) - or else Is_Possibly_Unaligned_Slice (Lhs) - or else Is_Possibly_Unaligned_Slice (Rhs) - then - Loop_Required := True; - - -- If we are not bit-packed, and we have only one slice, then no - -- overlap is possible except in the parameter case, so we can let - -- the back end handle things. - - elsif not (L_Slice and R_Slice) then - if Forwards_OK (N) then - return; - end if; - end if; - - -- If the right-hand side is a string literal, introduce a temporary - -- for it, for use in the generated loop that will follow. - - if Nkind (Rhs) = N_String_Literal then - declare - Temp : constant Entity_Id := - Make_Defining_Identifier (Loc, New_Internal_Name ('T')); - Decl : Node_Id; - - begin - Decl := - Make_Object_Declaration (Loc, - Defining_Identifier => Temp, - Object_Definition => New_Occurrence_Of (L_Type, Loc), - Expression => Relocate_Node (Rhs)); - - Insert_Action (N, Decl); - Rewrite (Rhs, New_Occurrence_Of (Temp, Loc)); - R_Type := Etype (Temp); - end; - end if; - - -- Come here to complete the analysis - - -- Loop_Required: Set to True if we know that a loop is required - -- regardless of overlap considerations. - - -- Forwards_OK: Set to False if we already know that a forwards - -- move is not safe, else set to True. - - -- Backwards_OK: Set to False if we already know that a backwards - -- move is not safe, else set to True - - -- Our task at this stage is to complete the overlap analysis, which - -- can result in possibly setting Forwards_OK or Backwards_OK to - -- False, and then generating the final code, either by deciding - -- that it is OK after all to let Gigi handle it, or by generating - -- appropriate code in the front end. - - declare - L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type)); - R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type)); - - Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ); - Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ); - Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ); - Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ); - - Act_L_Array : Node_Id; - Act_R_Array : Node_Id; - - Cleft_Lo : Node_Id; - Cright_Lo : Node_Id; - Condition : Node_Id; - - Cresult : Compare_Result; - - begin - -- Get the expressions for the arrays. If we are dealing with a - -- private type, then convert to the underlying type. We can do - -- direct assignments to an array that is a private type, but - -- we cannot assign to elements of the array without this extra - -- unchecked conversion. - - if Nkind (Act_Lhs) = N_Slice then - Larray := Prefix (Act_Lhs); - else - Larray := Act_Lhs; - - if Is_Private_Type (Etype (Larray)) then - Larray := - Unchecked_Convert_To - (Underlying_Type (Etype (Larray)), Larray); - end if; - end if; - - if Nkind (Act_Rhs) = N_Slice then - Rarray := Prefix (Act_Rhs); - else - Rarray := Act_Rhs; - - if Is_Private_Type (Etype (Rarray)) then - Rarray := - Unchecked_Convert_To - (Underlying_Type (Etype (Rarray)), Rarray); - end if; - end if; - - -- If both sides are slices, we must figure out whether - -- it is safe to do the move in one direction or the other - -- It is always safe if there is a change of representation - -- since obviously two arrays with different representations - -- cannot possibly overlap. - - if (not Crep) and L_Slice and R_Slice then - Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs)); - Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs)); - - -- If both left and right hand arrays are entity names, and - -- refer to different entities, then we know that the move - -- is safe (the two storage areas are completely disjoint). - - if Is_Entity_Name (Act_L_Array) - and then Is_Entity_Name (Act_R_Array) - and then Entity (Act_L_Array) /= Entity (Act_R_Array) - then - null; - - -- Otherwise, we assume the worst, which is that the two - -- arrays are the same array. There is no need to check if - -- we know that is the case, because if we don't know it, - -- we still have to assume it! - - -- Generally if the same array is involved, then we have - -- an overlapping case. We will have to really assume the - -- worst (i.e. set neither of the OK flags) unless we can - -- determine the lower or upper bounds at compile time and - -- compare them. - - else - Cresult := Compile_Time_Compare (Left_Lo, Right_Lo); - - if Cresult = Unknown then - Cresult := Compile_Time_Compare (Left_Hi, Right_Hi); - end if; - - case Cresult is - when LT | LE | EQ => Set_Backwards_OK (N, False); - when GT | GE => Set_Forwards_OK (N, False); - when NE | Unknown => Set_Backwards_OK (N, False); - Set_Forwards_OK (N, False); - end case; - end if; - end if; - - -- If after that analysis, Forwards_OK is still True, and - -- Loop_Required is False, meaning that we have not discovered - -- some non-overlap reason for requiring a loop, then we can - -- still let gigi handle it. - - if not Loop_Required then - if Forwards_OK (N) then - return; - else - null; - -- Here is where a memmove would be appropriate ??? - end if; - end if; - - -- At this stage we have to generate an explicit loop, and - -- we have the following cases: - - -- Forwards_OK = True - - -- Rnn : right_index := right_index'First; - -- for Lnn in left-index loop - -- left (Lnn) := right (Rnn); - -- Rnn := right_index'Succ (Rnn); - -- end loop; - - -- Note: the above code MUST be analyzed with checks off, - -- because otherwise the Succ could overflow. But in any - -- case this is more efficient! - - -- Forwards_OK = False, Backwards_OK = True - - -- Rnn : right_index := right_index'Last; - -- for Lnn in reverse left-index loop - -- left (Lnn) := right (Rnn); - -- Rnn := right_index'Pred (Rnn); - -- end loop; - - -- Note: the above code MUST be analyzed with checks off, - -- because otherwise the Pred could overflow. But in any - -- case this is more efficient! - - -- Forwards_OK = Backwards_OK = False - - -- This only happens if we have the same array on each side. It is - -- possible to create situations using overlays that violate this, - -- but we simply do not promise to get this "right" in this case. - - -- There are two possible subcases. If the No_Implicit_Conditionals - -- restriction is set, then we generate the following code: - - -- declare - -- T : constant <operand-type> := rhs; - -- begin - -- lhs := T; - -- end; - - -- If implicit conditionals are permitted, then we generate: - - -- if Left_Lo <= Right_Lo then - -- <code for Forwards_OK = True above> - -- else - -- <code for Backwards_OK = True above> - -- end if; - - -- Cases where either Forwards_OK or Backwards_OK is true - - if Forwards_OK (N) or else Backwards_OK (N) then - if Controlled_Type (Component_Type (L_Type)) - and then Base_Type (L_Type) = Base_Type (R_Type) - and then Ndim = 1 - and then not No_Ctrl_Actions (N) - then - declare - Proc : constant Entity_Id := - TSS (Base_Type (L_Type), TSS_Slice_Assign); - Actuals : List_Id; - - begin - Apply_Dereference (Larray); - Apply_Dereference (Rarray); - Actuals := New_List ( - Duplicate_Subexpr (Larray, Name_Req => True), - Duplicate_Subexpr (Rarray, Name_Req => True), - Duplicate_Subexpr (Left_Lo, Name_Req => True), - Duplicate_Subexpr (Left_Hi, Name_Req => True), - Duplicate_Subexpr (Right_Lo, Name_Req => True), - Duplicate_Subexpr (Right_Hi, Name_Req => True)); - - Append_To (Actuals, - New_Occurrence_Of ( - Boolean_Literals (not Forwards_OK (N)), Loc)); - - Rewrite (N, - Make_Procedure_Call_Statement (Loc, - Name => New_Reference_To (Proc, Loc), - Parameter_Associations => Actuals)); - end; - - else - Rewrite (N, - Expand_Assign_Array_Loop - (N, Larray, Rarray, L_Type, R_Type, Ndim, - Rev => not Forwards_OK (N))); - end if; - - -- Case of both are false with No_Implicit_Conditionals - - elsif Restriction_Active (No_Implicit_Conditionals) then - declare - T : constant Entity_Id := - Make_Defining_Identifier (Loc, Chars => Name_T); - - begin - Rewrite (N, - Make_Block_Statement (Loc, - Declarations => New_List ( - Make_Object_Declaration (Loc, - Defining_Identifier => T, - Constant_Present => True, - Object_Definition => - New_Occurrence_Of (Etype (Rhs), Loc), - Expression => Relocate_Node (Rhs))), - - Handled_Statement_Sequence => - Make_Handled_Sequence_Of_Statements (Loc, - Statements => New_List ( - Make_Assignment_Statement (Loc, - Name => Relocate_Node (Lhs), - Expression => New_Occurrence_Of (T, Loc)))))); - end; - - -- Case of both are false with implicit conditionals allowed - - else - -- Before we generate this code, we must ensure that the - -- left and right side array types are defined. They may - -- be itypes, and we cannot let them be defined inside the - -- if, since the first use in the then may not be executed. - - Ensure_Defined (L_Type, N); - Ensure_Defined (R_Type, N); - - -- We normally compare addresses to find out which way round - -- to do the loop, since this is realiable, and handles the - -- cases of parameters, conversions etc. But we can't do that - -- in the bit packed case or the Java VM case, because addresses - -- don't work there. - - if not Is_Bit_Packed_Array (L_Type) and then not Java_VM then - Condition := - Make_Op_Le (Loc, - Left_Opnd => - Unchecked_Convert_To (RTE (RE_Integer_Address), - Make_Attribute_Reference (Loc, - Prefix => - Make_Indexed_Component (Loc, - Prefix => - Duplicate_Subexpr_Move_Checks (Larray, True), - Expressions => New_List ( - Make_Attribute_Reference (Loc, - Prefix => - New_Reference_To - (L_Index_Typ, Loc), - Attribute_Name => Name_First))), - Attribute_Name => Name_Address)), - - Right_Opnd => - Unchecked_Convert_To (RTE (RE_Integer_Address), - Make_Attribute_Reference (Loc, - Prefix => - Make_Indexed_Component (Loc, - Prefix => - Duplicate_Subexpr_Move_Checks (Rarray, True), - Expressions => New_List ( - Make_Attribute_Reference (Loc, - Prefix => - New_Reference_To - (R_Index_Typ, Loc), - Attribute_Name => Name_First))), - Attribute_Name => Name_Address))); - - -- For the bit packed and Java VM cases we use the bounds. - -- That's OK, because we don't have to worry about parameters, - -- since they cannot cause overlap. Perhaps we should worry - -- about weird slice conversions ??? - - else - -- Copy the bounds and reset the Analyzed flag, because the - -- bounds of the index type itself may be universal, and must - -- must be reaanalyzed to acquire the proper type for Gigi. - - Cleft_Lo := New_Copy_Tree (Left_Lo); - Cright_Lo := New_Copy_Tree (Right_Lo); - Set_Analyzed (Cleft_Lo, False); - Set_Analyzed (Cright_Lo, False); - - Condition := - Make_Op_Le (Loc, - Left_Opnd => Cleft_Lo, - Right_Opnd => Cright_Lo); - end if; - - if Controlled_Type (Component_Type (L_Type)) - and then Base_Type (L_Type) = Base_Type (R_Type) - and then Ndim = 1 - and then not No_Ctrl_Actions (N) - then - - -- Call TSS procedure for array assignment, passing the - -- the explicit bounds of right and left hand sides. - - declare - Proc : constant Node_Id := - TSS (Base_Type (L_Type), TSS_Slice_Assign); - Actuals : List_Id; - - begin - Apply_Dereference (Larray); - Apply_Dereference (Rarray); - Actuals := New_List ( - Duplicate_Subexpr (Larray, Name_Req => True), - Duplicate_Subexpr (Rarray, Name_Req => True), - Duplicate_Subexpr (Left_Lo, Name_Req => True), - Duplicate_Subexpr (Left_Hi, Name_Req => True), - Duplicate_Subexpr (Right_Lo, Name_Req => True), - Duplicate_Subexpr (Right_Hi, Name_Req => True)); - - Append_To (Actuals, - Make_Op_Not (Loc, - Right_Opnd => Condition)); - - Rewrite (N, - Make_Procedure_Call_Statement (Loc, - Name => New_Reference_To (Proc, Loc), - Parameter_Associations => Actuals)); - end; - - else - Rewrite (N, - Make_Implicit_If_Statement (N, - Condition => Condition, - - Then_Statements => New_List ( - Expand_Assign_Array_Loop - (N, Larray, Rarray, L_Type, R_Type, Ndim, - Rev => False)), - - Else_Statements => New_List ( - Expand_Assign_Array_Loop - (N, Larray, Rarray, L_Type, R_Type, Ndim, - Rev => True)))); - end if; - end if; - - Analyze (N, Suppress => All_Checks); - end; - - exception - when RE_Not_Available => - return; - end Expand_Assign_Array; - - ------------------------------ - -- Expand_Assign_Array_Loop -- - ------------------------------ - - -- The following is an example of the loop generated for the case of - -- a two-dimensional array: - - -- declare - -- R2b : Tm1X1 := 1; - -- begin - -- for L1b in 1 .. 100 loop - -- declare - -- R4b : Tm1X2 := 1; - -- begin - -- for L3b in 1 .. 100 loop - -- vm1 (L1b, L3b) := vm2 (R2b, R4b); - -- R4b := Tm1X2'succ(R4b); - -- end loop; - -- end; - -- R2b := Tm1X1'succ(R2b); - -- end loop; - -- end; - - -- Here Rev is False, and Tm1Xn are the subscript types for the right - -- hand side. The declarations of R2b and R4b are inserted before the - -- original assignment statement. - - function Expand_Assign_Array_Loop - (N : Node_Id; - Larray : Entity_Id; - Rarray : Entity_Id; - L_Type : Entity_Id; - R_Type : Entity_Id; - Ndim : Pos; - Rev : Boolean) return Node_Id - is - Loc : constant Source_Ptr := Sloc (N); - - Lnn : array (1 .. Ndim) of Entity_Id; - Rnn : array (1 .. Ndim) of Entity_Id; - -- Entities used as subscripts on left and right sides - - L_Index_Type : array (1 .. Ndim) of Entity_Id; - R_Index_Type : array (1 .. Ndim) of Entity_Id; - -- Left and right index types - - Assign : Node_Id; - - F_Or_L : Name_Id; - S_Or_P : Name_Id; - - begin - if Rev then - F_Or_L := Name_Last; - S_Or_P := Name_Pred; - else - F_Or_L := Name_First; - S_Or_P := Name_Succ; - end if; - - -- Setup index types and subscript entities - - declare - L_Index : Node_Id; - R_Index : Node_Id; - - begin - L_Index := First_Index (L_Type); - R_Index := First_Index (R_Type); - - for J in 1 .. Ndim loop - Lnn (J) := - Make_Defining_Identifier (Loc, - Chars => New_Internal_Name ('L')); - - Rnn (J) := - Make_Defining_Identifier (Loc, - Chars => New_Internal_Name ('R')); - - L_Index_Type (J) := Etype (L_Index); - R_Index_Type (J) := Etype (R_Index); - - Next_Index (L_Index); - Next_Index (R_Index); - end loop; - end; - - -- Now construct the assignment statement - - declare - ExprL : constant List_Id := New_List; - ExprR : constant List_Id := New_List; - - begin - for J in 1 .. Ndim loop - Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc)); - Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc)); - end loop; - - Assign := - Make_Assignment_Statement (Loc, - Name => - Make_Indexed_Component (Loc, - Prefix => Duplicate_Subexpr (Larray, Name_Req => True), - Expressions => ExprL), - Expression => - Make_Indexed_Component (Loc, - Prefix => Duplicate_Subexpr (Rarray, Name_Req => True), - Expressions => ExprR)); - - -- We set assignment OK, since there are some cases, e.g. in object - -- declarations, where we are actually assigning into a constant. - -- If there really is an illegality, it was caught long before now, - -- and was flagged when the original assignment was analyzed. - - Set_Assignment_OK (Name (Assign)); - - -- Propagate the No_Ctrl_Actions flag to individual assignments - - Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N)); - end; - - -- Now construct the loop from the inside out, with the last subscript - -- varying most rapidly. Note that Assign is first the raw assignment - -- statement, and then subsequently the loop that wraps it up. - - for J in reverse 1 .. Ndim loop - Assign := - Make_Block_Statement (Loc, - Declarations => New_List ( - Make_Object_Declaration (Loc, - Defining_Identifier => Rnn (J), - Object_Definition => - New_Occurrence_Of (R_Index_Type (J), Loc), - Expression => - Make_Attribute_Reference (Loc, - Prefix => New_Occurrence_Of (R_Index_Type (J), Loc), - Attribute_Name => F_Or_L))), - - Handled_Statement_Sequence => - Make_Handled_Sequence_Of_Statements (Loc, - Statements => New_List ( - Make_Implicit_Loop_Statement (N, - Iteration_Scheme => - Make_Iteration_Scheme (Loc, - Loop_Parameter_Specification => - Make_Loop_Parameter_Specification (Loc, - Defining_Identifier => Lnn (J), - Reverse_Present => Rev, - Discrete_Subtype_Definition => - New_Reference_To (L_Index_Type (J), Loc))), - - Statements => New_List ( - Assign, - - Make_Assignment_Statement (Loc, - Name => New_Occurrence_Of (Rnn (J), Loc), - Expression => - Make_Attribute_Reference (Loc, - Prefix => - New_Occurrence_Of (R_Index_Type (J), Loc), - Attribute_Name => S_Or_P, - Expressions => New_List ( - New_Occurrence_Of (Rnn (J), Loc))))))))); - end loop; - - return Assign; - end Expand_Assign_Array_Loop; - - -------------------------- - -- Expand_Assign_Record -- - -------------------------- - - -- The only processing required is in the change of representation - -- case, where we must expand the assignment to a series of field - -- by field assignments. - - procedure Expand_Assign_Record (N : Node_Id) is - Lhs : constant Node_Id := Name (N); - Rhs : Node_Id := Expression (N); - - begin - -- If change of representation, then extract the real right hand - -- side from the type conversion, and proceed with component-wise - -- assignment, since the two types are not the same as far as the - -- back end is concerned. - - if Change_Of_Representation (N) then - Rhs := Expression (Rhs); - - -- If this may be a case of a large bit aligned component, then - -- proceed with component-wise assignment, to avoid possible - -- clobbering of other components sharing bits in the first or - -- last byte of the component to be assigned. - - elsif Possible_Bit_Aligned_Component (Lhs) - or - Possible_Bit_Aligned_Component (Rhs) - then - null; - - -- If neither condition met, then nothing special to do, the back end - -- can handle assignment of the entire component as a single entity. - - else - return; - end if; - - -- At this stage we know that we must do a component wise assignment - - declare - Loc : constant Source_Ptr := Sloc (N); - R_Typ : constant Entity_Id := Base_Type (Etype (Rhs)); - L_Typ : constant Entity_Id := Base_Type (Etype (Lhs)); - Decl : constant Node_Id := Declaration_Node (R_Typ); - RDef : Node_Id; - F : Entity_Id; - - function Find_Component - (Typ : Entity_Id; - Comp : Entity_Id) return Entity_Id; - -- Find the component with the given name in the underlying record - -- declaration for Typ. We need to use the actual entity because - -- the type may be private and resolution by identifier alone would - -- fail. - - function Make_Component_List_Assign - (CL : Node_Id; - U_U : Boolean := False) return List_Id; - -- Returns a sequence of statements to assign the components that - -- are referenced in the given component list. The flag U_U is - -- used to force the usage of the inferred value of the variant - -- part expression as the switch for the generated case statement. - - function Make_Field_Assign - (C : Entity_Id; - U_U : Boolean := False) return Node_Id; - -- Given C, the entity for a discriminant or component, build an - -- assignment for the corresponding field values. The flag U_U - -- signals the presence of an Unchecked_Union and forces the usage - -- of the inferred discriminant value of C as the right hand side - -- of the assignment. - - function Make_Field_Assigns (CI : List_Id) return List_Id; - -- Given CI, a component items list, construct series of statements - -- for fieldwise assignment of the corresponding components. - - -------------------- - -- Find_Component -- - -------------------- - - function Find_Component - (Typ : Entity_Id; - Comp : Entity_Id) return Entity_Id - is - Utyp : constant Entity_Id := Underlying_Type (Typ); - C : Entity_Id; - - begin - C := First_Entity (Utyp); - - while Present (C) loop - if Chars (C) = Chars (Comp) then - return C; - end if; - Next_Entity (C); - end loop; - - raise Program_Error; - end Find_Component; - - -------------------------------- - -- Make_Component_List_Assign -- - -------------------------------- - - function Make_Component_List_Assign - (CL : Node_Id; - U_U : Boolean := False) return List_Id - is - CI : constant List_Id := Component_Items (CL); - VP : constant Node_Id := Variant_Part (CL); - - Alts : List_Id; - DC : Node_Id; - DCH : List_Id; - Expr : Node_Id; - Result : List_Id; - V : Node_Id; - - begin - Result := Make_Field_Assigns (CI); - - if Present (VP) then - - V := First_Non_Pragma (Variants (VP)); - Alts := New_List; - while Present (V) loop - - DCH := New_List; - DC := First (Discrete_Choices (V)); - while Present (DC) loop - Append_To (DCH, New_Copy_Tree (DC)); - Next (DC); - end loop; - - Append_To (Alts, - Make_Case_Statement_Alternative (Loc, - Discrete_Choices => DCH, - Statements => - Make_Component_List_Assign (Component_List (V)))); - Next_Non_Pragma (V); - end loop; - - -- If we have an Unchecked_Union, use the value of the inferred - -- discriminant of the variant part expression as the switch - -- for the case statement. The case statement may later be - -- folded. - - if U_U then - Expr := - New_Copy (Get_Discriminant_Value ( - Entity (Name (VP)), - Etype (Rhs), - Discriminant_Constraint (Etype (Rhs)))); - else - Expr := - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr (Rhs), - Selector_Name => - Make_Identifier (Loc, Chars (Name (VP)))); - end if; - - Append_To (Result, - Make_Case_Statement (Loc, - Expression => Expr, - Alternatives => Alts)); - end if; - - return Result; - end Make_Component_List_Assign; - - ----------------------- - -- Make_Field_Assign -- - ----------------------- - - function Make_Field_Assign - (C : Entity_Id; - U_U : Boolean := False) return Node_Id - is - A : Node_Id; - Expr : Node_Id; - - begin - -- In the case of an Unchecked_Union, use the discriminant - -- constraint value as on the right hand side of the assignment. - - if U_U then - Expr := - New_Copy (Get_Discriminant_Value (C, - Etype (Rhs), - Discriminant_Constraint (Etype (Rhs)))); - else - Expr := - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr (Rhs), - Selector_Name => New_Occurrence_Of (C, Loc)); - end if; - - A := - Make_Assignment_Statement (Loc, - Name => - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr (Lhs), - Selector_Name => - New_Occurrence_Of (Find_Component (L_Typ, C), Loc)), - Expression => Expr); - - -- Set Assignment_OK, so discriminants can be assigned - - Set_Assignment_OK (Name (A), True); - return A; - end Make_Field_Assign; - - ------------------------ - -- Make_Field_Assigns -- - ------------------------ - - function Make_Field_Assigns (CI : List_Id) return List_Id is - Item : Node_Id; - Result : List_Id; - - begin - Item := First (CI); - Result := New_List; - while Present (Item) loop - if Nkind (Item) = N_Component_Declaration then - Append_To - (Result, Make_Field_Assign (Defining_Identifier (Item))); - end if; - - Next (Item); - end loop; - - return Result; - end Make_Field_Assigns; - - -- Start of processing for Expand_Assign_Record - - begin - -- Note that we use the base types for this processing. This results - -- in some extra work in the constrained case, but the change of - -- representation case is so unusual that it is not worth the effort. - - -- First copy the discriminants. This is done unconditionally. It - -- is required in the unconstrained left side case, and also in the - -- case where this assignment was constructed during the expansion - -- of a type conversion (since initialization of discriminants is - -- suppressed in this case). It is unnecessary but harmless in - -- other cases. - - if Has_Discriminants (L_Typ) then - F := First_Discriminant (R_Typ); - while Present (F) loop - - if Is_Unchecked_Union (Base_Type (R_Typ)) then - Insert_Action (N, Make_Field_Assign (F, True)); - else - Insert_Action (N, Make_Field_Assign (F)); - end if; - - Next_Discriminant (F); - end loop; - end if; - - -- We know the underlying type is a record, but its current view - -- may be private. We must retrieve the usable record declaration. - - if Nkind (Decl) = N_Private_Type_Declaration - and then Present (Full_View (R_Typ)) - then - RDef := Type_Definition (Declaration_Node (Full_View (R_Typ))); - else - RDef := Type_Definition (Decl); - end if; - - if Nkind (RDef) = N_Record_Definition - and then Present (Component_List (RDef)) - then - - if Is_Unchecked_Union (R_Typ) then - Insert_Actions (N, - Make_Component_List_Assign (Component_List (RDef), True)); - else - Insert_Actions - (N, Make_Component_List_Assign (Component_List (RDef))); - end if; - - Rewrite (N, Make_Null_Statement (Loc)); - end if; - - end; - end Expand_Assign_Record; - - ----------------------------------- - -- Expand_N_Assignment_Statement -- - ----------------------------------- - - -- This procedure implements various cases where an assignment statement - -- cannot just be passed on to the back end in untransformed state. - - procedure Expand_N_Assignment_Statement (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Lhs : constant Node_Id := Name (N); - Rhs : constant Node_Id := Expression (N); - Typ : constant Entity_Id := Underlying_Type (Etype (Lhs)); - Exp : Node_Id; - - begin - -- First deal with generation of range check if required. For now - -- we do this only for discrete types. - - if Do_Range_Check (Rhs) - and then Is_Discrete_Type (Typ) - then - Set_Do_Range_Check (Rhs, False); - Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed); - end if; - - -- Check for a special case where a high level transformation is - -- required. If we have either of: - - -- P.field := rhs; - -- P (sub) := rhs; - - -- where P is a reference to a bit packed array, then we have to unwind - -- the assignment. The exact meaning of being a reference to a bit - -- packed array is as follows: - - -- An indexed component whose prefix is a bit packed array is a - -- reference to a bit packed array. - - -- An indexed component or selected component whose prefix is a - -- reference to a bit packed array is itself a reference ot a - -- bit packed array. - - -- The required transformation is - - -- Tnn : prefix_type := P; - -- Tnn.field := rhs; - -- P := Tnn; - - -- or - - -- Tnn : prefix_type := P; - -- Tnn (subscr) := rhs; - -- P := Tnn; - - -- Since P is going to be evaluated more than once, any subscripts - -- in P must have their evaluation forced. - - if (Nkind (Lhs) = N_Indexed_Component - or else - Nkind (Lhs) = N_Selected_Component) - and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs)) - then - declare - BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs)); - BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr); - Tnn : constant Entity_Id := - Make_Defining_Identifier (Loc, - Chars => New_Internal_Name ('T')); - - begin - -- Insert the post assignment first, because we want to copy - -- the BPAR_Expr tree before it gets analyzed in the context - -- of the pre assignment. Note that we do not analyze the - -- post assignment yet (we cannot till we have completed the - -- analysis of the pre assignment). As usual, the analysis - -- of this post assignment will happen on its own when we - -- "run into" it after finishing the current assignment. - - Insert_After (N, - Make_Assignment_Statement (Loc, - Name => New_Copy_Tree (BPAR_Expr), - Expression => New_Occurrence_Of (Tnn, Loc))); - - -- At this stage BPAR_Expr is a reference to a bit packed - -- array where the reference was not expanded in the original - -- tree, since it was on the left side of an assignment. But - -- in the pre-assignment statement (the object definition), - -- BPAR_Expr will end up on the right hand side, and must be - -- reexpanded. To achieve this, we reset the analyzed flag - -- of all selected and indexed components down to the actual - -- indexed component for the packed array. - - Exp := BPAR_Expr; - loop - Set_Analyzed (Exp, False); - - if Nkind (Exp) = N_Selected_Component - or else - Nkind (Exp) = N_Indexed_Component - then - Exp := Prefix (Exp); - else - exit; - end if; - end loop; - - -- Now we can insert and analyze the pre-assignment - - -- If the right-hand side requires a transient scope, it has - -- already been placed on the stack. However, the declaration is - -- inserted in the tree outside of this scope, and must reflect - -- the proper scope for its variable. This awkward bit is forced - -- by the stricter scope discipline imposed by GCC 2.97. - - declare - Uses_Transient_Scope : constant Boolean := - Scope_Is_Transient - and then N = Node_To_Be_Wrapped; - - begin - if Uses_Transient_Scope then - New_Scope (Scope (Current_Scope)); - end if; - - Insert_Before_And_Analyze (N, - Make_Object_Declaration (Loc, - Defining_Identifier => Tnn, - Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc), - Expression => BPAR_Expr)); - - if Uses_Transient_Scope then - Pop_Scope; - end if; - end; - - -- Now fix up the original assignment and continue processing - - Rewrite (Prefix (Lhs), - New_Occurrence_Of (Tnn, Loc)); - - -- We do not need to reanalyze that assignment, and we do not need - -- to worry about references to the temporary, but we do need to - -- make sure that the temporary is not marked as a true constant - -- since we now have a generate assignment to it! - - Set_Is_True_Constant (Tnn, False); - end; - end if; - - -- When we have the appropriate type of aggregate in the - -- expression (it has been determined during analysis of the - -- aggregate by setting the delay flag), let's perform in place - -- assignment and thus avoid creating a temporay. - - if Is_Delayed_Aggregate (Rhs) then - Convert_Aggr_In_Assignment (N); - Rewrite (N, Make_Null_Statement (Loc)); - Analyze (N); - return; - end if; - - -- Apply discriminant check if required. If Lhs is an access type - -- to a designated type with discriminants, we must always check. - - if Has_Discriminants (Etype (Lhs)) then - - -- Skip discriminant check if change of representation. Will be - -- done when the change of representation is expanded out. - - if not Change_Of_Representation (N) then - Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs); - end if; - - -- If the type is private without discriminants, and the full type - -- has discriminants (necessarily with defaults) a check may still be - -- necessary if the Lhs is aliased. The private determinants must be - -- visible to build the discriminant constraints. - - -- Only an explicit dereference that comes from source indicates - -- aliasing. Access to formals of protected operations and entries - -- create dereferences but are not semantic aliasings. - - elsif Is_Private_Type (Etype (Lhs)) - and then Has_Discriminants (Typ) - and then Nkind (Lhs) = N_Explicit_Dereference - and then Comes_From_Source (Lhs) - then - declare - Lt : constant Entity_Id := Etype (Lhs); - begin - Set_Etype (Lhs, Typ); - Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs)); - Apply_Discriminant_Check (Rhs, Typ, Lhs); - Set_Etype (Lhs, Lt); - end; - - -- If the Lhs has a private type with unknown discriminants, it - -- may have a full view with discriminants, but those are nameable - -- only in the underlying type, so convert the Rhs to it before - -- potential checking. - - elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs))) - and then Has_Discriminants (Typ) - then - Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs)); - Apply_Discriminant_Check (Rhs, Typ, Lhs); - - -- In the access type case, we need the same discriminant check, - -- and also range checks if we have an access to constrained array. - - elsif Is_Access_Type (Etype (Lhs)) - and then Is_Constrained (Designated_Type (Etype (Lhs))) - then - if Has_Discriminants (Designated_Type (Etype (Lhs))) then - - -- Skip discriminant check if change of representation. Will be - -- done when the change of representation is expanded out. - - if not Change_Of_Representation (N) then - Apply_Discriminant_Check (Rhs, Etype (Lhs)); - end if; - - elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then - Apply_Range_Check (Rhs, Etype (Lhs)); - - if Is_Constrained (Etype (Lhs)) then - Apply_Length_Check (Rhs, Etype (Lhs)); - end if; - - if Nkind (Rhs) = N_Allocator then - declare - Target_Typ : constant Entity_Id := Etype (Expression (Rhs)); - C_Es : Check_Result; - - begin - C_Es := - Range_Check - (Lhs, - Target_Typ, - Etype (Designated_Type (Etype (Lhs)))); - - Insert_Range_Checks - (C_Es, - N, - Target_Typ, - Sloc (Lhs), - Lhs); - end; - end if; - end if; - - -- Apply range check for access type case - - elsif Is_Access_Type (Etype (Lhs)) - and then Nkind (Rhs) = N_Allocator - and then Nkind (Expression (Rhs)) = N_Qualified_Expression - then - Analyze_And_Resolve (Expression (Rhs)); - Apply_Range_Check - (Expression (Rhs), Designated_Type (Etype (Lhs))); - end if; - - -- Ada 2005 (AI-231): Generate the run-time check - - if Is_Access_Type (Typ) - and then Can_Never_Be_Null (Etype (Lhs)) - and then not Can_Never_Be_Null (Etype (Rhs)) - then - Apply_Constraint_Check (Rhs, Etype (Lhs)); - end if; - - -- Case of assignment to a bit packed array element - - if Nkind (Lhs) = N_Indexed_Component - and then Is_Bit_Packed_Array (Etype (Prefix (Lhs))) - then - Expand_Bit_Packed_Element_Set (N); - return; - - elsif Is_Tagged_Type (Typ) - or else (Controlled_Type (Typ) and then not Is_Array_Type (Typ)) - then - Tagged_Case : declare - L : List_Id := No_List; - Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N); - - begin - -- In the controlled case, we need to make sure that function - -- calls are evaluated before finalizing the target. In all - -- cases, it makes the expansion easier if the side-effects - -- are removed first. - - Remove_Side_Effects (Lhs); - Remove_Side_Effects (Rhs); - - -- Avoid recursion in the mechanism - - Set_Analyzed (N); - - -- If dispatching assignment, we need to dispatch to _assign - - if Is_Class_Wide_Type (Typ) - - -- If the type is tagged, we may as well use the predefined - -- primitive assignment. This avoids inlining a lot of code - -- and in the class-wide case, the assignment is replaced by - -- dispatch call to _assign. Note that this cannot be done - -- when discriminant checks are locally suppressed (as in - -- extension aggregate expansions) because otherwise the - -- discriminant check will be performed within the _assign - -- call. It is also suppressed for assignmments created by the - -- expander that correspond to initializations, where we do - -- want to copy the tag (No_Ctrl_Actions flag set True). - -- by the expander and we do not need to mess with tags ever - -- (Expand_Ctrl_Actions flag is set True in this case). - - or else (Is_Tagged_Type (Typ) - and then Chars (Current_Scope) /= Name_uAssign - and then Expand_Ctrl_Actions - and then not Discriminant_Checks_Suppressed (Empty)) - then - -- Fetch the primitive op _assign and proper type to call - -- it. Because of possible conflits between private and - -- full view the proper type is fetched directly from the - -- operation profile. - - declare - Op : constant Entity_Id := - Find_Prim_Op (Typ, Name_uAssign); - F_Typ : Entity_Id := Etype (First_Formal (Op)); - - begin - -- If the assignment is dispatching, make sure to use the - -- proper type. - - if Is_Class_Wide_Type (Typ) then - F_Typ := Class_Wide_Type (F_Typ); - end if; - - L := New_List; - - -- In case of assignment to a class-wide tagged type, before - -- the assignment we generate run-time check to ensure that - -- the tag of the Target is covered by the tag of the source - - if Is_Class_Wide_Type (Typ) - and then Is_Tagged_Type (Typ) - and then Is_Tagged_Type (Underlying_Type (Etype (Rhs))) - then - Append_To (L, - Make_Raise_Constraint_Error (Loc, - Condition => - Make_Op_Not (Loc, - Make_Function_Call (Loc, - Name => New_Reference_To - (RTE (RE_CW_Membership), Loc), - Parameter_Associations => New_List ( - Make_Selected_Component (Loc, - Prefix => - Duplicate_Subexpr (Lhs), - Selector_Name => - Make_Identifier (Loc, Name_uTag)), - Make_Selected_Component (Loc, - Prefix => - Duplicate_Subexpr (Rhs), - Selector_Name => - Make_Identifier (Loc, Name_uTag))))), - Reason => CE_Tag_Check_Failed)); - end if; - - Append_To (L, - Make_Procedure_Call_Statement (Loc, - Name => New_Reference_To (Op, Loc), - Parameter_Associations => New_List ( - Unchecked_Convert_To (F_Typ, Duplicate_Subexpr (Lhs)), - Unchecked_Convert_To (F_Typ, - Duplicate_Subexpr (Rhs))))); - end; - - else - L := Make_Tag_Ctrl_Assignment (N); - - -- We can't afford to have destructive Finalization Actions - -- in the Self assignment case, so if the target and the - -- source are not obviously different, code is generated to - -- avoid the self assignment case - -- - -- if lhs'address /= rhs'address then - -- <code for controlled and/or tagged assignment> - -- end if; - - if not Statically_Different (Lhs, Rhs) - and then Expand_Ctrl_Actions - then - L := New_List ( - Make_Implicit_If_Statement (N, - Condition => - Make_Op_Ne (Loc, - Left_Opnd => - Make_Attribute_Reference (Loc, - Prefix => Duplicate_Subexpr (Lhs), - Attribute_Name => Name_Address), - - Right_Opnd => - Make_Attribute_Reference (Loc, - Prefix => Duplicate_Subexpr (Rhs), - Attribute_Name => Name_Address)), - - Then_Statements => L)); - end if; - - -- We need to set up an exception handler for implementing - -- 7.6.1 (18). The remaining adjustments are tackled by the - -- implementation of adjust for record_controllers (see - -- s-finimp.adb) - - -- This is skipped if we have no finalization - - if Expand_Ctrl_Actions - and then not Restriction_Active (No_Finalization) - then - L := New_List ( - Make_Block_Statement (Loc, - Handled_Statement_Sequence => - Make_Handled_Sequence_Of_Statements (Loc, - Statements => L, - Exception_Handlers => New_List ( - Make_Exception_Handler (Loc, - Exception_Choices => - New_List (Make_Others_Choice (Loc)), - Statements => New_List ( - Make_Raise_Program_Error (Loc, - Reason => - PE_Finalize_Raised_Exception) - )))))); - end if; - end if; - - Rewrite (N, - Make_Block_Statement (Loc, - Handled_Statement_Sequence => - Make_Handled_Sequence_Of_Statements (Loc, Statements => L))); - - -- If no restrictions on aborts, protect the whole assignement - -- for controlled objects as per 9.8(11) - - if Controlled_Type (Typ) - and then Expand_Ctrl_Actions - and then Abort_Allowed - then - declare - Blk : constant Entity_Id := - New_Internal_Entity - (E_Block, Current_Scope, Sloc (N), 'B'); - - begin - Set_Scope (Blk, Current_Scope); - Set_Etype (Blk, Standard_Void_Type); - Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N))); - - Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer)); - Set_At_End_Proc (Handled_Statement_Sequence (N), - New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc)); - Expand_At_End_Handler - (Handled_Statement_Sequence (N), Blk); - end; - end if; - - -- N has been rewritten to a block statement for which it is - -- known by construction that no checks are necessary: analyze - -- it with all checks suppressed. - - Analyze (N, Suppress => All_Checks); - return; - end Tagged_Case; - - -- Array types - - elsif Is_Array_Type (Typ) then - declare - Actual_Rhs : Node_Id := Rhs; - - begin - while Nkind (Actual_Rhs) = N_Type_Conversion - or else - Nkind (Actual_Rhs) = N_Qualified_Expression - loop - Actual_Rhs := Expression (Actual_Rhs); - end loop; - - Expand_Assign_Array (N, Actual_Rhs); - return; - end; - - -- Record types - - elsif Is_Record_Type (Typ) then - Expand_Assign_Record (N); - return; - - -- Scalar types. This is where we perform the processing related - -- to the requirements of (RM 13.9.1(9-11)) concerning the handling - -- of invalid scalar values. - - elsif Is_Scalar_Type (Typ) then - - -- Case where right side is known valid - - if Expr_Known_Valid (Rhs) then - - -- Here the right side is valid, so it is fine. The case to - -- deal with is when the left side is a local variable reference - -- whose value is not currently known to be valid. If this is - -- the case, and the assignment appears in an unconditional - -- context, then we can mark the left side as now being valid. - - if Is_Local_Variable_Reference (Lhs) - and then not Is_Known_Valid (Entity (Lhs)) - and then In_Unconditional_Context (N) - then - Set_Is_Known_Valid (Entity (Lhs), True); - end if; - - -- Case where right side may be invalid in the sense of the RM - -- reference above. The RM does not require that we check for - -- the validity on an assignment, but it does require that the - -- assignment of an invalid value not cause erroneous behavior. - - -- The general approach in GNAT is to use the Is_Known_Valid flag - -- to avoid the need for validity checking on assignments. However - -- in some cases, we have to do validity checking in order to make - -- sure that the setting of this flag is correct. - - else - -- Validate right side if we are validating copies - - if Validity_Checks_On - and then Validity_Check_Copies - then - Ensure_Valid (Rhs); - - -- We can propagate this to the left side where appropriate - - if Is_Local_Variable_Reference (Lhs) - and then not Is_Known_Valid (Entity (Lhs)) - and then In_Unconditional_Context (N) - then - Set_Is_Known_Valid (Entity (Lhs), True); - end if; - - -- Otherwise check to see what should be done - - -- If left side is a local variable, then we just set its - -- flag to indicate that its value may no longer be valid, - -- since we are copying a potentially invalid value. - - elsif Is_Local_Variable_Reference (Lhs) then - Set_Is_Known_Valid (Entity (Lhs), False); - - -- Check for case of a nonlocal variable on the left side - -- which is currently known to be valid. In this case, we - -- simply ensure that the right side is valid. We only play - -- the game of copying validity status for local variables, - -- since we are doing this statically, not by tracing the - -- full flow graph. - - elsif Is_Entity_Name (Lhs) - and then Is_Known_Valid (Entity (Lhs)) - then - -- Note that the Ensure_Valid call is ignored if the - -- Validity_Checking mode is set to none so we do not - -- need to worry about that case here. - - Ensure_Valid (Rhs); - - -- In all other cases, we can safely copy an invalid value - -- without worrying about the status of the left side. Since - -- it is not a variable reference it will not be considered - -- as being known to be valid in any case. - - else - null; - end if; - end if; - end if; - - -- Defend against invalid subscripts on left side if we are in - -- standard validity checking mode. No need to do this if we - -- are checking all subscripts. - - if Validity_Checks_On - and then Validity_Check_Default - and then not Validity_Check_Subscripts - then - Check_Valid_Lvalue_Subscripts (Lhs); - end if; - - exception - when RE_Not_Available => - return; - end Expand_N_Assignment_Statement; - - ------------------------------ - -- Expand_N_Block_Statement -- - ------------------------------ - - -- Encode entity names defined in block statement - - procedure Expand_N_Block_Statement (N : Node_Id) is - begin - Qualify_Entity_Names (N); - end Expand_N_Block_Statement; - - ----------------------------- - -- Expand_N_Case_Statement -- - ----------------------------- - - procedure Expand_N_Case_Statement (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Expr : constant Node_Id := Expression (N); - Alt : Node_Id; - Len : Nat; - Cond : Node_Id; - Choice : Node_Id; - Chlist : List_Id; - - begin - -- Check for the situation where we know at compile time which - -- branch will be taken - - if Compile_Time_Known_Value (Expr) then - Alt := Find_Static_Alternative (N); - - -- Move the statements from this alternative after the case - -- statement. They are already analyzed, so will be skipped - -- by the analyzer. - - Insert_List_After (N, Statements (Alt)); - - -- That leaves the case statement as a shell. The alternative - -- that will be executed is reset to a null list. So now we can - -- kill the entire case statement. - - Kill_Dead_Code (Expression (N)); - Kill_Dead_Code (Alternatives (N)); - Rewrite (N, Make_Null_Statement (Loc)); - return; - end if; - - -- Here if the choice is not determined at compile time - - declare - Last_Alt : constant Node_Id := Last (Alternatives (N)); - - Others_Present : Boolean; - Others_Node : Node_Id; - - Then_Stms : List_Id; - Else_Stms : List_Id; - - begin - if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then - Others_Present := True; - Others_Node := Last_Alt; - else - Others_Present := False; - end if; - - -- First step is to worry about possible invalid argument. The RM - -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is - -- outside the base range), then Constraint_Error must be raised. - - -- Case of validity check required (validity checks are on, the - -- expression is not known to be valid, and the case statement - -- comes from source -- no need to validity check internally - -- generated case statements). - - if Validity_Check_Default then - Ensure_Valid (Expr); - end if; - - -- If there is only a single alternative, just replace it with - -- the sequence of statements since obviously that is what is - -- going to be executed in all cases. - - Len := List_Length (Alternatives (N)); - - if Len = 1 then - -- We still need to evaluate the expression if it has any - -- side effects. - - Remove_Side_Effects (Expression (N)); - - Insert_List_After (N, Statements (First (Alternatives (N)))); - - -- That leaves the case statement as a shell. The alternative - -- that will be executed is reset to a null list. So now we can - -- kill the entire case statement. - - Kill_Dead_Code (Expression (N)); - Rewrite (N, Make_Null_Statement (Loc)); - return; - end if; - - -- An optimization. If there are only two alternatives, and only - -- a single choice, then rewrite the whole case statement as an - -- if statement, since this can result in susbequent optimizations. - -- This helps not only with case statements in the source of a - -- simple form, but also with generated code (discriminant check - -- functions in particular) - - if Len = 2 then - Chlist := Discrete_Choices (First (Alternatives (N))); - - if List_Length (Chlist) = 1 then - Choice := First (Chlist); - - Then_Stms := Statements (First (Alternatives (N))); - Else_Stms := Statements (Last (Alternatives (N))); - - -- For TRUE, generate "expression", not expression = true - - if Nkind (Choice) = N_Identifier - and then Entity (Choice) = Standard_True - then - Cond := Expression (N); - - -- For FALSE, generate "expression" and switch then/else - - elsif Nkind (Choice) = N_Identifier - and then Entity (Choice) = Standard_False - then - Cond := Expression (N); - Else_Stms := Statements (First (Alternatives (N))); - Then_Stms := Statements (Last (Alternatives (N))); - - -- For a range, generate "expression in range" - - elsif Nkind (Choice) = N_Range - or else (Nkind (Choice) = N_Attribute_Reference - and then Attribute_Name (Choice) = Name_Range) - or else (Is_Entity_Name (Choice) - and then Is_Type (Entity (Choice))) - or else Nkind (Choice) = N_Subtype_Indication - then - Cond := - Make_In (Loc, - Left_Opnd => Expression (N), - Right_Opnd => Relocate_Node (Choice)); - - -- For any other subexpression "expression = value" - - else - Cond := - Make_Op_Eq (Loc, - Left_Opnd => Expression (N), - Right_Opnd => Relocate_Node (Choice)); - end if; - - -- Now rewrite the case as an IF - - Rewrite (N, - Make_If_Statement (Loc, - Condition => Cond, - Then_Statements => Then_Stms, - Else_Statements => Else_Stms)); - Analyze (N); - return; - end if; - end if; - - -- If the last alternative is not an Others choice, replace it - -- with an N_Others_Choice. Note that we do not bother to call - -- Analyze on the modified case statement, since it's only effect - -- would be to compute the contents of the Others_Discrete_Choices - -- which is not needed by the back end anyway. - - -- The reason we do this is that the back end always needs some - -- default for a switch, so if we have not supplied one in the - -- processing above for validity checking, then we need to - -- supply one here. - - if not Others_Present then - Others_Node := Make_Others_Choice (Sloc (Last_Alt)); - Set_Others_Discrete_Choices - (Others_Node, Discrete_Choices (Last_Alt)); - Set_Discrete_Choices (Last_Alt, New_List (Others_Node)); - end if; - end; - end Expand_N_Case_Statement; - - ----------------------------- - -- Expand_N_Exit_Statement -- - ----------------------------- - - -- The only processing required is to deal with a possible C/Fortran - -- boolean value used as the condition for the exit statement. - - procedure Expand_N_Exit_Statement (N : Node_Id) is - begin - Adjust_Condition (Condition (N)); - end Expand_N_Exit_Statement; - - ----------------------------- - -- Expand_N_Goto_Statement -- - ----------------------------- - - -- Add poll before goto if polling active - - procedure Expand_N_Goto_Statement (N : Node_Id) is - begin - Generate_Poll_Call (N); - end Expand_N_Goto_Statement; - - --------------------------- - -- Expand_N_If_Statement -- - --------------------------- - - -- First we deal with the case of C and Fortran convention boolean - -- values, with zero/non-zero semantics. - - -- Second, we deal with the obvious rewriting for the cases where the - -- condition of the IF is known at compile time to be True or False. - - -- Third, we remove elsif parts which have non-empty Condition_Actions - -- and rewrite as independent if statements. For example: - - -- if x then xs - -- elsif y then ys - -- ... - -- end if; - - -- becomes - -- - -- if x then xs - -- else - -- <<condition actions of y>> - -- if y then ys - -- ... - -- end if; - -- end if; - - -- This rewriting is needed if at least one elsif part has a non-empty - -- Condition_Actions list. We also do the same processing if there is - -- a constant condition in an elsif part (in conjunction with the first - -- processing step mentioned above, for the recursive call made to deal - -- with the created inner if, this deals with properly optimizing the - -- cases of constant elsif conditions). - - procedure Expand_N_If_Statement (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Hed : Node_Id; - E : Node_Id; - New_If : Node_Id; - - begin - Adjust_Condition (Condition (N)); - - -- The following loop deals with constant conditions for the IF. We - -- need a loop because as we eliminate False conditions, we grab the - -- first elsif condition and use it as the primary condition. - - while Compile_Time_Known_Value (Condition (N)) loop - - -- If condition is True, we can simply rewrite the if statement - -- now by replacing it by the series of then statements. - - if Is_True (Expr_Value (Condition (N))) then - - -- All the else parts can be killed - - Kill_Dead_Code (Elsif_Parts (N)); - Kill_Dead_Code (Else_Statements (N)); - - Hed := Remove_Head (Then_Statements (N)); - Insert_List_After (N, Then_Statements (N)); - Rewrite (N, Hed); - return; - - -- If condition is False, then we can delete the condition and - -- the Then statements - - else - -- We do not delete the condition if constant condition - -- warnings are enabled, since otherwise we end up deleting - -- the desired warning. Of course the backend will get rid - -- of this True/False test anyway, so nothing is lost here. - - if not Constant_Condition_Warnings then - Kill_Dead_Code (Condition (N)); - end if; - - Kill_Dead_Code (Then_Statements (N)); - - -- If there are no elsif statements, then we simply replace - -- the entire if statement by the sequence of else statements. - - if No (Elsif_Parts (N)) then - - if No (Else_Statements (N)) - or else Is_Empty_List (Else_Statements (N)) - then - Rewrite (N, - Make_Null_Statement (Sloc (N))); - - else - Hed := Remove_Head (Else_Statements (N)); - Insert_List_After (N, Else_Statements (N)); - Rewrite (N, Hed); - end if; - - return; - - -- If there are elsif statements, the first of them becomes - -- the if/then section of the rebuilt if statement This is - -- the case where we loop to reprocess this copied condition. - - else - Hed := Remove_Head (Elsif_Parts (N)); - Insert_Actions (N, Condition_Actions (Hed)); - Set_Condition (N, Condition (Hed)); - Set_Then_Statements (N, Then_Statements (Hed)); - - -- Hed might have been captured as the condition determining - -- the current value for an entity. Now it is detached from - -- the tree, so a Current_Value pointer in the condition might - -- need to be updated. - - Check_Possible_Current_Value_Condition (N); - - if Is_Empty_List (Elsif_Parts (N)) then - Set_Elsif_Parts (N, No_List); - end if; - end if; - end if; - end loop; - - -- Loop through elsif parts, dealing with constant conditions and - -- possible expression actions that are present. - - if Present (Elsif_Parts (N)) then - E := First (Elsif_Parts (N)); - while Present (E) loop - Adjust_Condition (Condition (E)); - - -- If there are condition actions, then we rewrite the if - -- statement as indicated above. We also do the same rewrite - -- if the condition is True or False. The further processing - -- of this constant condition is then done by the recursive - -- call to expand the newly created if statement - - if Present (Condition_Actions (E)) - or else Compile_Time_Known_Value (Condition (E)) - then - -- Note this is not an implicit if statement, since it is - -- part of an explicit if statement in the source (or of an - -- implicit if statement that has already been tested). - - New_If := - Make_If_Statement (Sloc (E), - Condition => Condition (E), - Then_Statements => Then_Statements (E), - Elsif_Parts => No_List, - Else_Statements => Else_Statements (N)); - - -- Elsif parts for new if come from remaining elsif's of parent - - while Present (Next (E)) loop - if No (Elsif_Parts (New_If)) then - Set_Elsif_Parts (New_If, New_List); - end if; - - Append (Remove_Next (E), Elsif_Parts (New_If)); - end loop; - - Set_Else_Statements (N, New_List (New_If)); - - if Present (Condition_Actions (E)) then - Insert_List_Before (New_If, Condition_Actions (E)); - end if; - - Remove (E); - - if Is_Empty_List (Elsif_Parts (N)) then - Set_Elsif_Parts (N, No_List); - end if; - - Analyze (New_If); - return; - - -- No special processing for that elsif part, move to next - - else - Next (E); - end if; - end loop; - end if; - - -- Some more optimizations applicable if we still have an IF statement - - if Nkind (N) /= N_If_Statement then - return; - end if; - - -- Another optimization, special cases that can be simplified - - -- if expression then - -- return true; - -- else - -- return false; - -- end if; - - -- can be changed to: - - -- return expression; - - -- and - - -- if expression then - -- return false; - -- else - -- return true; - -- end if; - - -- can be changed to: - - -- return not (expression); - - if Nkind (N) = N_If_Statement - and then No (Elsif_Parts (N)) - and then Present (Else_Statements (N)) - and then List_Length (Then_Statements (N)) = 1 - and then List_Length (Else_Statements (N)) = 1 - then - declare - Then_Stm : constant Node_Id := First (Then_Statements (N)); - Else_Stm : constant Node_Id := First (Else_Statements (N)); - - begin - if Nkind (Then_Stm) = N_Return_Statement - and then - Nkind (Else_Stm) = N_Return_Statement - then - declare - Then_Expr : constant Node_Id := Expression (Then_Stm); - Else_Expr : constant Node_Id := Expression (Else_Stm); - - begin - if Nkind (Then_Expr) = N_Identifier - and then - Nkind (Else_Expr) = N_Identifier - then - if Entity (Then_Expr) = Standard_True - and then Entity (Else_Expr) = Standard_False - then - Rewrite (N, - Make_Return_Statement (Loc, - Expression => Relocate_Node (Condition (N)))); - Analyze (N); - return; - - elsif Entity (Then_Expr) = Standard_False - and then Entity (Else_Expr) = Standard_True - then - Rewrite (N, - Make_Return_Statement (Loc, - Expression => - Make_Op_Not (Loc, - Right_Opnd => Relocate_Node (Condition (N))))); - Analyze (N); - return; - end if; - end if; - end; - end if; - end; - end if; - end Expand_N_If_Statement; - - ----------------------------- - -- Expand_N_Loop_Statement -- - ----------------------------- - - -- 1. Deal with while condition for C/Fortran boolean - -- 2. Deal with loops with a non-standard enumeration type range - -- 3. Deal with while loops where Condition_Actions is set - -- 4. Insert polling call if required - - procedure Expand_N_Loop_Statement (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Isc : constant Node_Id := Iteration_Scheme (N); - - begin - if Present (Isc) then - Adjust_Condition (Condition (Isc)); - end if; - - if Is_Non_Empty_List (Statements (N)) then - Generate_Poll_Call (First (Statements (N))); - end if; - - if No (Isc) then - return; - end if; - - -- Handle the case where we have a for loop with the range type being - -- an enumeration type with non-standard representation. In this case - -- we expand: - - -- for x in [reverse] a .. b loop - -- ... - -- end loop; - - -- to - - -- for xP in [reverse] integer - -- range etype'Pos (a) .. etype'Pos (b) loop - -- declare - -- x : constant etype := Pos_To_Rep (xP); - -- begin - -- ... - -- end; - -- end loop; - - if Present (Loop_Parameter_Specification (Isc)) then - declare - LPS : constant Node_Id := Loop_Parameter_Specification (Isc); - Loop_Id : constant Entity_Id := Defining_Identifier (LPS); - Ltype : constant Entity_Id := Etype (Loop_Id); - Btype : constant Entity_Id := Base_Type (Ltype); - Expr : Node_Id; - New_Id : Entity_Id; - - begin - if not Is_Enumeration_Type (Btype) - or else No (Enum_Pos_To_Rep (Btype)) - then - return; - end if; - - New_Id := - Make_Defining_Identifier (Loc, - Chars => New_External_Name (Chars (Loop_Id), 'P')); - - -- If the type has a contiguous representation, successive - -- values can be generated as offsets from the first literal. - - if Has_Contiguous_Rep (Btype) then - Expr := - Unchecked_Convert_To (Btype, - Make_Op_Add (Loc, - Left_Opnd => - Make_Integer_Literal (Loc, - Enumeration_Rep (First_Literal (Btype))), - Right_Opnd => New_Reference_To (New_Id, Loc))); - else - -- Use the constructed array Enum_Pos_To_Rep - - Expr := - Make_Indexed_Component (Loc, - Prefix => New_Reference_To (Enum_Pos_To_Rep (Btype), Loc), - Expressions => New_List (New_Reference_To (New_Id, Loc))); - end if; - - Rewrite (N, - Make_Loop_Statement (Loc, - Identifier => Identifier (N), - - Iteration_Scheme => - Make_Iteration_Scheme (Loc, - Loop_Parameter_Specification => - Make_Loop_Parameter_Specification (Loc, - Defining_Identifier => New_Id, - Reverse_Present => Reverse_Present (LPS), - - Discrete_Subtype_Definition => - Make_Subtype_Indication (Loc, - - Subtype_Mark => - New_Reference_To (Standard_Natural, Loc), - - Constraint => - Make_Range_Constraint (Loc, - Range_Expression => - Make_Range (Loc, - - Low_Bound => - Make_Attribute_Reference (Loc, - Prefix => - New_Reference_To (Btype, Loc), - - Attribute_Name => Name_Pos, - - Expressions => New_List ( - Relocate_Node - (Type_Low_Bound (Ltype)))), - - High_Bound => - Make_Attribute_Reference (Loc, - Prefix => - New_Reference_To (Btype, Loc), - - Attribute_Name => Name_Pos, - - Expressions => New_List ( - Relocate_Node - (Type_High_Bound (Ltype))))))))), - - Statements => New_List ( - Make_Block_Statement (Loc, - Declarations => New_List ( - Make_Object_Declaration (Loc, - Defining_Identifier => Loop_Id, - Constant_Present => True, - Object_Definition => New_Reference_To (Ltype, Loc), - Expression => Expr)), - - Handled_Statement_Sequence => - Make_Handled_Sequence_Of_Statements (Loc, - Statements => Statements (N)))), - - End_Label => End_Label (N))); - Analyze (N); - end; - - -- Second case, if we have a while loop with Condition_Actions set, - -- then we change it into a plain loop: - - -- while C loop - -- ... - -- end loop; - - -- changed to: - - -- loop - -- <<condition actions>> - -- exit when not C; - -- ... - -- end loop - - elsif Present (Isc) - and then Present (Condition_Actions (Isc)) - then - declare - ES : Node_Id; - - begin - ES := - Make_Exit_Statement (Sloc (Condition (Isc)), - Condition => - Make_Op_Not (Sloc (Condition (Isc)), - Right_Opnd => Condition (Isc))); - - Prepend (ES, Statements (N)); - Insert_List_Before (ES, Condition_Actions (Isc)); - - -- This is not an implicit loop, since it is generated in - -- response to the loop statement being processed. If this - -- is itself implicit, the restriction has already been - -- checked. If not, it is an explicit loop. - - Rewrite (N, - Make_Loop_Statement (Sloc (N), - Identifier => Identifier (N), - Statements => Statements (N), - End_Label => End_Label (N))); - - Analyze (N); - end; - end if; - end Expand_N_Loop_Statement; - - ------------------------------- - -- Expand_N_Return_Statement -- - ------------------------------- - - procedure Expand_N_Return_Statement (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Exp : constant Node_Id := Expression (N); - Exptyp : Entity_Id; - T : Entity_Id; - Utyp : Entity_Id; - Scope_Id : Entity_Id; - Kind : Entity_Kind; - Call : Node_Id; - Acc_Stat : Node_Id; - Goto_Stat : Node_Id; - Lab_Node : Node_Id; - Cur_Idx : Nat; - Return_Type : Entity_Id; - Result_Exp : Node_Id; - Result_Id : Entity_Id; - Result_Obj : Node_Id; - - begin - -- Case where returned expression is present - - if Present (Exp) then - - -- Always normalize C/Fortran boolean result. This is not always - -- necessary, but it seems a good idea to minimize the passing - -- around of non-normalized values, and in any case this handles - -- the processing of barrier functions for protected types, which - -- turn the condition into a return statement. - - Exptyp := Etype (Exp); - - if Is_Boolean_Type (Exptyp) - and then Nonzero_Is_True (Exptyp) - then - Adjust_Condition (Exp); - Adjust_Result_Type (Exp, Exptyp); - end if; - - -- Do validity check if enabled for returns - - if Validity_Checks_On - and then Validity_Check_Returns - then - Ensure_Valid (Exp); - end if; - end if; - - -- Find relevant enclosing scope from which return is returning - - Cur_Idx := Scope_Stack.Last; - loop - Scope_Id := Scope_Stack.Table (Cur_Idx).Entity; - - if Ekind (Scope_Id) /= E_Block - and then Ekind (Scope_Id) /= E_Loop - then - exit; - - else - Cur_Idx := Cur_Idx - 1; - pragma Assert (Cur_Idx >= 0); - end if; - end loop; - - if No (Exp) then - Kind := Ekind (Scope_Id); - - -- If it is a return from procedures do no extra steps - - if Kind = E_Procedure or else Kind = E_Generic_Procedure then - return; - end if; - - pragma Assert (Is_Entry (Scope_Id)); - - -- Look at the enclosing block to see whether the return is from - -- an accept statement or an entry body. - - for J in reverse 0 .. Cur_Idx loop - Scope_Id := Scope_Stack.Table (J).Entity; - exit when Is_Concurrent_Type (Scope_Id); - end loop; - - -- If it is a return from accept statement it should be expanded - -- as a call to RTS Complete_Rendezvous and a goto to the end of - -- the accept body. - - -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept, - -- Expand_N_Accept_Alternative in exp_ch9.adb) - - if Is_Task_Type (Scope_Id) then - - Call := (Make_Procedure_Call_Statement (Loc, - Name => New_Reference_To - (RTE (RE_Complete_Rendezvous), Loc))); - Insert_Before (N, Call); - -- why not insert actions here??? - Analyze (Call); - - Acc_Stat := Parent (N); - while Nkind (Acc_Stat) /= N_Accept_Statement loop - Acc_Stat := Parent (Acc_Stat); - end loop; - - Lab_Node := Last (Statements - (Handled_Statement_Sequence (Acc_Stat))); - - Goto_Stat := Make_Goto_Statement (Loc, - Name => New_Occurrence_Of - (Entity (Identifier (Lab_Node)), Loc)); - - Set_Analyzed (Goto_Stat); - - Rewrite (N, Goto_Stat); - Analyze (N); - - -- If it is a return from an entry body, put a Complete_Entry_Body - -- call in front of the return. - - elsif Is_Protected_Type (Scope_Id) then - - Call := - Make_Procedure_Call_Statement (Loc, - Name => New_Reference_To - (RTE (RE_Complete_Entry_Body), Loc), - Parameter_Associations => New_List - (Make_Attribute_Reference (Loc, - Prefix => - New_Reference_To - (Object_Ref - (Corresponding_Body (Parent (Scope_Id))), - Loc), - Attribute_Name => Name_Unchecked_Access))); - - Insert_Before (N, Call); - Analyze (Call); - - end if; - - return; - end if; - - T := Etype (Exp); - Return_Type := Etype (Scope_Id); - Utyp := Underlying_Type (Return_Type); - - -- Check the result expression of a scalar function against - -- the subtype of the function by inserting a conversion. - -- This conversion must eventually be performed for other - -- classes of types, but for now it's only done for scalars. - -- ??? - - if Is_Scalar_Type (T) then - Rewrite (Exp, Convert_To (Return_Type, Exp)); - Analyze (Exp); - end if; - - -- Deal with returning variable length objects and controlled types - - -- Nothing to do if we are returning by reference, or this is not - -- a type that requires special processing (indicated by the fact - -- that it requires a cleanup scope for the secondary stack case). - - if Is_Return_By_Reference_Type (T) then - null; - - elsif not Requires_Transient_Scope (Return_Type) then - - -- Mutable records with no variable length components are not - -- returned on the sec-stack so we need to make sure that the - -- backend will only copy back the size of the actual value and not - -- the maximum size. We create an actual subtype for this purpose - - declare - Ubt : constant Entity_Id := Underlying_Type (Base_Type (T)); - Decl : Node_Id; - Ent : Entity_Id; - begin - if Has_Discriminants (Ubt) - and then not Is_Constrained (Ubt) - and then not Has_Unchecked_Union (Ubt) - then - Decl := Build_Actual_Subtype (Ubt, Exp); - Ent := Defining_Identifier (Decl); - Insert_Action (Exp, Decl); - Rewrite (Exp, Unchecked_Convert_To (Ent, Exp)); - end if; - end; - - -- Case of secondary stack not used - - elsif Function_Returns_With_DSP (Scope_Id) then - - -- Here what we need to do is to always return by reference, since - -- we will return with the stack pointer depressed. We may need to - -- do a copy to a local temporary before doing this return. - - No_Secondary_Stack_Case : declare - Local_Copy_Required : Boolean := False; - -- Set to True if a local copy is required - - Copy_Ent : Entity_Id; - -- Used for the target entity if a copy is required - - Decl : Node_Id; - -- Declaration used to create copy if needed - - procedure Test_Copy_Required (Expr : Node_Id); - -- Determines if Expr represents a return value for which a - -- copy is required. More specifically, a copy is not required - -- if Expr represents an object or component of an object that - -- is either in the local subprogram frame, or is constant. - -- If a copy is required, then Local_Copy_Required is set True. - - ------------------------ - -- Test_Copy_Required -- - ------------------------ - - procedure Test_Copy_Required (Expr : Node_Id) is - Ent : Entity_Id; - - begin - -- If component, test prefix (object containing component) - - if Nkind (Expr) = N_Indexed_Component - or else - Nkind (Expr) = N_Selected_Component - then - Test_Copy_Required (Prefix (Expr)); - return; - - -- See if we have an entity name - - elsif Is_Entity_Name (Expr) then - Ent := Entity (Expr); - - -- Constant entity is always OK, no copy required - - if Ekind (Ent) = E_Constant then - return; - - -- No copy required for local variable - - elsif Ekind (Ent) = E_Variable - and then Scope (Ent) = Current_Subprogram - then - return; - end if; - end if; - - -- All other cases require a copy - - Local_Copy_Required := True; - end Test_Copy_Required; - - -- Start of processing for No_Secondary_Stack_Case - - begin - -- No copy needed if result is from a function call. - -- In this case the result is already being returned by - -- reference with the stack pointer depressed. - - -- To make up for a gcc 2.8.1 deficiency (???), we perform - -- the copy for array types if the constrained status of the - -- target type is different from that of the expression. - - if Requires_Transient_Scope (T) - and then - (not Is_Array_Type (T) - or else Is_Constrained (T) = Is_Constrained (Return_Type) - or else Controlled_Type (T)) - and then Nkind (Exp) = N_Function_Call - then - Set_By_Ref (N); - - -- We always need a local copy for a controlled type, since - -- we are required to finalize the local value before return. - -- The copy will automatically include the required finalize. - -- Moreover, gigi cannot make this copy, since we need special - -- processing to ensure proper behavior for finalization. - - -- Note: the reason we are returning with a depressed stack - -- pointer in the controlled case (even if the type involved - -- is constrained) is that we must make a local copy to deal - -- properly with the requirement that the local result be - -- finalized. - - elsif Controlled_Type (Utyp) then - Copy_Ent := - Make_Defining_Identifier (Loc, - Chars => New_Internal_Name ('R')); - - -- Build declaration to do the copy, and insert it, setting - -- Assignment_OK, because we may be copying a limited type. - -- In addition we set the special flag to inhibit finalize - -- attachment if this is a controlled type (since this attach - -- must be done by the caller, otherwise if we attach it here - -- we will finalize the returned result prematurely). - - Decl := - Make_Object_Declaration (Loc, - Defining_Identifier => Copy_Ent, - Object_Definition => New_Occurrence_Of (Return_Type, Loc), - Expression => Relocate_Node (Exp)); - - Set_Assignment_OK (Decl); - Set_Delay_Finalize_Attach (Decl); - Insert_Action (N, Decl); - - -- Now the actual return uses the copied value - - Rewrite (Exp, New_Occurrence_Of (Copy_Ent, Loc)); - Analyze_And_Resolve (Exp, Return_Type); - - -- Since we have made the copy, gigi does not have to, so - -- we set the By_Ref flag to prevent another copy being made. - - Set_By_Ref (N); - - -- Non-controlled cases - - else - Test_Copy_Required (Exp); - - -- If a local copy is required, then gigi will make the - -- copy, otherwise, we can return the result directly, - -- so set By_Ref to suppress the gigi copy. - - if not Local_Copy_Required then - Set_By_Ref (N); - end if; - end if; - end No_Secondary_Stack_Case; - - -- Here if secondary stack is used - - else - -- Make sure that no surrounding block will reclaim the - -- secondary-stack on which we are going to put the result. - -- Not only may this introduce secondary stack leaks but worse, - -- if the reclamation is done too early, then the result we are - -- returning may get clobbered. See example in 7417-003. - - declare - S : Entity_Id := Current_Scope; - - begin - while Ekind (S) = E_Block or else Ekind (S) = E_Loop loop - Set_Sec_Stack_Needed_For_Return (S, True); - S := Enclosing_Dynamic_Scope (S); - end loop; - end; - - -- Optimize the case where the result is a function call. In this - -- case either the result is already on the secondary stack, or is - -- already being returned with the stack pointer depressed and no - -- further processing is required except to set the By_Ref flag to - -- ensure that gigi does not attempt an extra unnecessary copy. - -- (actually not just unnecessary but harmfully wrong in the case - -- of a controlled type, where gigi does not know how to do a copy). - -- To make up for a gcc 2.8.1 deficiency (???), we perform - -- the copy for array types if the constrained status of the - -- target type is different from that of the expression. - - if Requires_Transient_Scope (T) - and then - (not Is_Array_Type (T) - or else Is_Constrained (T) = Is_Constrained (Return_Type) - or else Controlled_Type (T)) - and then Nkind (Exp) = N_Function_Call - then - Set_By_Ref (N); - - -- Remove side effects from the expression now so that - -- other part of the expander do not have to reanalyze - -- this node without this optimization - - Rewrite (Exp, Duplicate_Subexpr_No_Checks (Exp)); - - -- For controlled types, do the allocation on the sec-stack - -- manually in order to call adjust at the right time - -- type Anon1 is access Return_Type; - -- for Anon1'Storage_pool use ss_pool; - -- Anon2 : anon1 := new Return_Type'(expr); - -- return Anon2.all; - - elsif Controlled_Type (Utyp) then - declare - Loc : constant Source_Ptr := Sloc (N); - Temp : constant Entity_Id := - Make_Defining_Identifier (Loc, - Chars => New_Internal_Name ('R')); - Acc_Typ : constant Entity_Id := - Make_Defining_Identifier (Loc, - Chars => New_Internal_Name ('A')); - Alloc_Node : Node_Id; - - begin - Set_Ekind (Acc_Typ, E_Access_Type); - - Set_Associated_Storage_Pool (Acc_Typ, RTE (RE_SS_Pool)); - - Alloc_Node := - Make_Allocator (Loc, - Expression => - Make_Qualified_Expression (Loc, - Subtype_Mark => New_Reference_To (Etype (Exp), Loc), - Expression => Relocate_Node (Exp))); - - Insert_List_Before_And_Analyze (N, New_List ( - Make_Full_Type_Declaration (Loc, - Defining_Identifier => Acc_Typ, - Type_Definition => - Make_Access_To_Object_Definition (Loc, - Subtype_Indication => - New_Reference_To (Return_Type, Loc))), - - Make_Object_Declaration (Loc, - Defining_Identifier => Temp, - Object_Definition => New_Reference_To (Acc_Typ, Loc), - Expression => Alloc_Node))); - - Rewrite (Exp, - Make_Explicit_Dereference (Loc, - Prefix => New_Reference_To (Temp, Loc))); - - Analyze_And_Resolve (Exp, Return_Type); - end; - - -- Otherwise use the gigi mechanism to allocate result on the - -- secondary stack. - - else - Set_Storage_Pool (N, RTE (RE_SS_Pool)); - - -- If we are generating code for the Java VM do not use - -- SS_Allocate since everything is heap-allocated anyway. - - if not Java_VM then - Set_Procedure_To_Call (N, RTE (RE_SS_Allocate)); - end if; - end if; - end if; - - -- Implement the rules of 6.5(8-10), which require a tag check in - -- the case of a limited tagged return type, and tag reassignment - -- for nonlimited tagged results. These actions are needed when - -- the return type is a specific tagged type and the result - -- expression is a conversion or a formal parameter, because in - -- that case the tag of the expression might differ from the tag - -- of the specific result type. - - if Is_Tagged_Type (Utyp) - and then not Is_Class_Wide_Type (Utyp) - and then (Nkind (Exp) = N_Type_Conversion - or else Nkind (Exp) = N_Unchecked_Type_Conversion - or else (Is_Entity_Name (Exp) - and then Ekind (Entity (Exp)) in Formal_Kind)) - then - -- When the return type is limited, perform a check that the - -- tag of the result is the same as the tag of the return type. - - if Is_Limited_Type (Return_Type) then - Insert_Action (Exp, - Make_Raise_Constraint_Error (Loc, - Condition => - Make_Op_Ne (Loc, - Left_Opnd => - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr (Exp), - Selector_Name => - New_Reference_To (First_Tag_Component (Utyp), Loc)), - Right_Opnd => - Unchecked_Convert_To (RTE (RE_Tag), - New_Reference_To - (Node (First_Elmt - (Access_Disp_Table (Base_Type (Utyp)))), - Loc))), - Reason => CE_Tag_Check_Failed)); - - -- If the result type is a specific nonlimited tagged type, - -- then we have to ensure that the tag of the result is that - -- of the result type. This is handled by making a copy of the - -- expression in the case where it might have a different tag, - -- namely when the expression is a conversion or a formal - -- parameter. We create a new object of the result type and - -- initialize it from the expression, which will implicitly - -- force the tag to be set appropriately. - - else - Result_Id := - Make_Defining_Identifier (Loc, New_Internal_Name ('R')); - Result_Exp := New_Reference_To (Result_Id, Loc); - - Result_Obj := - Make_Object_Declaration (Loc, - Defining_Identifier => Result_Id, - Object_Definition => New_Reference_To (Return_Type, Loc), - Constant_Present => True, - Expression => Relocate_Node (Exp)); - - Set_Assignment_OK (Result_Obj); - Insert_Action (Exp, Result_Obj); - - Rewrite (Exp, Result_Exp); - Analyze_And_Resolve (Exp, Return_Type); - end if; - - -- Ada 2005 (AI-344): If the result type is class-wide, then insert - -- a check that the level of the return expression's underlying type - -- is not deeper than the level of the master enclosing the function. - -- Always generate the check when the type of the return expression - -- is class-wide, when it's a type conversion, or when it's a formal - -- parameter. Otherwise, suppress the check in the case where the - -- return expression has a specific type whose level is known not to - -- be statically deeper than the function's result type. - - elsif Ada_Version >= Ada_05 - and then Is_Class_Wide_Type (Return_Type) - and then not Scope_Suppress (Accessibility_Check) - and then - (Is_Class_Wide_Type (Etype (Exp)) - or else Nkind (Exp) = N_Type_Conversion - or else Nkind (Exp) = N_Unchecked_Type_Conversion - or else (Is_Entity_Name (Exp) - and then Ekind (Entity (Exp)) in Formal_Kind) - or else Scope_Depth (Enclosing_Dynamic_Scope (Etype (Exp))) > - Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id))) - then - Insert_Action (Exp, - Make_Raise_Program_Error (Loc, - Condition => - Make_Op_Gt (Loc, - Left_Opnd => - Make_Function_Call (Loc, - Name => - New_Reference_To - (RTE (RE_Get_Access_Level), Loc), - Parameter_Associations => - New_List (Make_Attribute_Reference (Loc, - Prefix => - Duplicate_Subexpr (Exp), - Attribute_Name => - Name_Tag))), - Right_Opnd => - Make_Integer_Literal (Loc, - Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))), - Reason => PE_Accessibility_Check_Failed)); - end if; - - exception - when RE_Not_Available => - return; - end Expand_N_Return_Statement; - - ------------------------------ - -- Make_Tag_Ctrl_Assignment -- - ------------------------------ - - function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is - Loc : constant Source_Ptr := Sloc (N); - L : constant Node_Id := Name (N); - T : constant Entity_Id := Underlying_Type (Etype (L)); - - Ctrl_Act : constant Boolean := Controlled_Type (T) - and then not No_Ctrl_Actions (N); - - Save_Tag : constant Boolean := Is_Tagged_Type (T) - and then not No_Ctrl_Actions (N) - and then not Java_VM; - -- Tags are not saved and restored when Java_VM because JVM tags - -- are represented implicitly in objects. - - Res : List_Id; - Tag_Tmp : Entity_Id; - - begin - Res := New_List; - - -- Finalize the target of the assignment when controlled. - -- We have two exceptions here: - - -- 1. If we are in an init proc since it is an initialization - -- more than an assignment - - -- 2. If the left-hand side is a temporary that was not initialized - -- (or the parent part of a temporary since it is the case in - -- extension aggregates). Such a temporary does not come from - -- source. We must examine the original node for the prefix, because - -- it may be a component of an entry formal, in which case it has - -- been rewritten and does not appear to come from source either. - - -- Case of init proc - - if not Ctrl_Act then - null; - - -- The left hand side is an uninitialized temporary - - elsif Nkind (L) = N_Type_Conversion - and then Is_Entity_Name (Expression (L)) - and then No_Initialization (Parent (Entity (Expression (L)))) - then - null; - else - Append_List_To (Res, - Make_Final_Call ( - Ref => Duplicate_Subexpr_No_Checks (L), - Typ => Etype (L), - With_Detach => New_Reference_To (Standard_False, Loc))); - end if; - - -- Save the Tag in a local variable Tag_Tmp - - if Save_Tag then - Tag_Tmp := - Make_Defining_Identifier (Loc, New_Internal_Name ('A')); - - Append_To (Res, - Make_Object_Declaration (Loc, - Defining_Identifier => Tag_Tmp, - Object_Definition => New_Reference_To (RTE (RE_Tag), Loc), - Expression => - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr_No_Checks (L), - Selector_Name => New_Reference_To (First_Tag_Component (T), - Loc)))); - - -- Otherwise Tag_Tmp not used - - else - Tag_Tmp := Empty; - end if; - - -- Processing for controlled types and types with controlled components - - -- Variables of such types contain pointers used to chain them in - -- finalization lists, in addition to user data. These pointers are - -- specific to each object of the type, not to the value being assigned. - -- Thus they need to be left intact during the assignment. We achieve - -- this by constructing a Storage_Array subtype, and by overlaying - -- objects of this type on the source and target of the assignment. - -- The assignment is then rewritten to assignments of slices of these - -- arrays, copying the user data, and leaving the pointers untouched. - - if Ctrl_Act then - Controlled_Actions : declare - Prev_Ref : Node_Id; - -- A reference to the Prev component of the record controller - - First_After_Root : Node_Id := Empty; - -- Index of first byte to be copied (used to skip - -- Root_Controlled in controlled objects). - - Last_Before_Hole : Node_Id := Empty; - -- Index of last byte to be copied before outermost record - -- controller data. - - Hole_Length : Node_Id := Empty; - -- Length of record controller data (Prev and Next pointers) - - First_After_Hole : Node_Id := Empty; - -- Index of first byte to be copied after outermost record - -- controller data. - - Expr, Source_Size : Node_Id; - Source_Actual_Subtype : Entity_Id; - -- Used for computation of the size of the data to be copied - - Range_Type : Entity_Id; - Opaque_Type : Entity_Id; - - function Build_Slice - (Rec : Entity_Id; - Lo : Node_Id; - Hi : Node_Id) return Node_Id; - -- Build and return a slice of an array of type S overlaid - -- on object Rec, with bounds specified by Lo and Hi. If either - -- bound is empty, a default of S'First (respectively S'Last) - -- is used. - - ----------------- - -- Build_Slice -- - ----------------- - - function Build_Slice - (Rec : Node_Id; - Lo : Node_Id; - Hi : Node_Id) return Node_Id - is - Lo_Bound : Node_Id; - Hi_Bound : Node_Id; - - Opaque : constant Node_Id := - Unchecked_Convert_To (Opaque_Type, - Make_Attribute_Reference (Loc, - Prefix => Rec, - Attribute_Name => Name_Address)); - -- Access value designating an opaque storage array of - -- type S overlaid on record Rec. - - begin - -- Compute slice bounds using S'First (1) and S'Last - -- as default values when not specified by the caller. - - if No (Lo) then - Lo_Bound := Make_Integer_Literal (Loc, 1); - else - Lo_Bound := Lo; - end if; - - if No (Hi) then - Hi_Bound := Make_Attribute_Reference (Loc, - Prefix => New_Occurrence_Of (Range_Type, Loc), - Attribute_Name => Name_Last); - else - Hi_Bound := Hi; - end if; - - return Make_Slice (Loc, - Prefix => - Opaque, - Discrete_Range => Make_Range (Loc, - Lo_Bound, Hi_Bound)); - end Build_Slice; - - -- Start of processing for Controlled_Actions - - begin - -- Create a constrained subtype of Storage_Array whose size - -- corresponds to the value being assigned. - - -- subtype G is Storage_Offset range - -- 1 .. (Expr'Size + Storage_Unit - 1) / Storage_Unit - - Expr := Duplicate_Subexpr_No_Checks (Expression (N)); - - if Nkind (Expr) = N_Qualified_Expression then - Expr := Expression (Expr); - end if; - - Source_Actual_Subtype := Etype (Expr); - - if Has_Discriminants (Source_Actual_Subtype) - and then not Is_Constrained (Source_Actual_Subtype) - then - Append_To (Res, - Build_Actual_Subtype (Source_Actual_Subtype, Expr)); - Source_Actual_Subtype := Defining_Identifier (Last (Res)); - end if; - - Source_Size := - Make_Op_Add (Loc, - Left_Opnd => - Make_Attribute_Reference (Loc, - Prefix => - New_Occurrence_Of (Source_Actual_Subtype, Loc), - Attribute_Name => - Name_Size), - Right_Opnd => - Make_Integer_Literal (Loc, - System_Storage_Unit - 1)); - Source_Size := - Make_Op_Divide (Loc, - Left_Opnd => Source_Size, - Right_Opnd => - Make_Integer_Literal (Loc, - Intval => System_Storage_Unit)); - - Range_Type := - Make_Defining_Identifier (Loc, - New_Internal_Name ('G')); - - Append_To (Res, - Make_Subtype_Declaration (Loc, - Defining_Identifier => Range_Type, - Subtype_Indication => - Make_Subtype_Indication (Loc, - Subtype_Mark => - New_Reference_To (RTE (RE_Storage_Offset), Loc), - Constraint => Make_Range_Constraint (Loc, - Range_Expression => - Make_Range (Loc, - Low_Bound => Make_Integer_Literal (Loc, 1), - High_Bound => Source_Size))))); - - -- subtype S is Storage_Array (G) - - Append_To (Res, - Make_Subtype_Declaration (Loc, - Defining_Identifier => - Make_Defining_Identifier (Loc, - New_Internal_Name ('S')), - Subtype_Indication => - Make_Subtype_Indication (Loc, - Subtype_Mark => - New_Reference_To (RTE (RE_Storage_Array), Loc), - Constraint => - Make_Index_Or_Discriminant_Constraint (Loc, - Constraints => - New_List (New_Reference_To (Range_Type, Loc)))))); - - -- type A is access S - - Opaque_Type := - Make_Defining_Identifier (Loc, - Chars => New_Internal_Name ('A')); - - Append_To (Res, - Make_Full_Type_Declaration (Loc, - Defining_Identifier => Opaque_Type, - Type_Definition => - Make_Access_To_Object_Definition (Loc, - Subtype_Indication => - New_Occurrence_Of ( - Defining_Identifier (Last (Res)), Loc)))); - - -- Generate appropriate slice assignments - - First_After_Root := Make_Integer_Literal (Loc, 1); - - -- For the case of a controlled object, skip the - -- Root_Controlled part. - - if Is_Controlled (T) then - First_After_Root := - Make_Op_Add (Loc, - First_After_Root, - Make_Op_Divide (Loc, - Make_Attribute_Reference (Loc, - Prefix => - New_Occurrence_Of (RTE (RE_Root_Controlled), Loc), - Attribute_Name => Name_Size), - Make_Integer_Literal (Loc, System_Storage_Unit))); - end if; - - -- For the case of a record with controlled components, skip - -- the Prev and Next components of the record controller. - -- These components constitute a 'hole' in the middle of the - -- data to be copied. - - if Has_Controlled_Component (T) then - Prev_Ref := - Make_Selected_Component (Loc, - Prefix => - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr_No_Checks (L), - Selector_Name => - New_Reference_To (Controller_Component (T), Loc)), - Selector_Name => Make_Identifier (Loc, Name_Prev)); - - -- Last index before hole: determined by position of - -- the _Controller.Prev component. - - Last_Before_Hole := - Make_Defining_Identifier (Loc, - New_Internal_Name ('L')); - - Append_To (Res, - Make_Object_Declaration (Loc, - Defining_Identifier => Last_Before_Hole, - Object_Definition => New_Occurrence_Of ( - RTE (RE_Storage_Offset), Loc), - Constant_Present => True, - Expression => Make_Op_Add (Loc, - Make_Attribute_Reference (Loc, - Prefix => Prev_Ref, - Attribute_Name => Name_Position), - Make_Attribute_Reference (Loc, - Prefix => New_Copy_Tree (Prefix (Prev_Ref)), - Attribute_Name => Name_Position)))); - - -- Hole length: size of the Prev and Next components - - Hole_Length := - Make_Op_Multiply (Loc, - Left_Opnd => Make_Integer_Literal (Loc, Uint_2), - Right_Opnd => - Make_Op_Divide (Loc, - Left_Opnd => - Make_Attribute_Reference (Loc, - Prefix => New_Copy_Tree (Prev_Ref), - Attribute_Name => Name_Size), - Right_Opnd => - Make_Integer_Literal (Loc, - Intval => System_Storage_Unit))); - - -- First index after hole - - First_After_Hole := - Make_Defining_Identifier (Loc, - New_Internal_Name ('F')); - - Append_To (Res, - Make_Object_Declaration (Loc, - Defining_Identifier => First_After_Hole, - Object_Definition => New_Occurrence_Of ( - RTE (RE_Storage_Offset), Loc), - Constant_Present => True, - Expression => - Make_Op_Add (Loc, - Left_Opnd => - Make_Op_Add (Loc, - Left_Opnd => - New_Occurrence_Of (Last_Before_Hole, Loc), - Right_Opnd => Hole_Length), - Right_Opnd => Make_Integer_Literal (Loc, 1)))); - - Last_Before_Hole := New_Occurrence_Of (Last_Before_Hole, Loc); - First_After_Hole := New_Occurrence_Of (First_After_Hole, Loc); - end if; - - -- Assign the first slice (possibly skipping Root_Controlled, - -- up to the beginning of the record controller if present, - -- up to the end of the object if not). - - Append_To (Res, Make_Assignment_Statement (Loc, - Name => Build_Slice ( - Rec => Duplicate_Subexpr_No_Checks (L), - Lo => First_After_Root, - Hi => Last_Before_Hole), - - Expression => Build_Slice ( - Rec => Expression (N), - Lo => First_After_Root, - Hi => New_Copy_Tree (Last_Before_Hole)))); - - if Present (First_After_Hole) then - - -- If a record controller is present, copy the second slice, - -- from right after the _Controller.Next component up to the - -- end of the object. - - Append_To (Res, Make_Assignment_Statement (Loc, - Name => Build_Slice ( - Rec => Duplicate_Subexpr_No_Checks (L), - Lo => First_After_Hole, - Hi => Empty), - Expression => Build_Slice ( - Rec => Duplicate_Subexpr_No_Checks (Expression (N)), - Lo => New_Copy_Tree (First_After_Hole), - Hi => Empty))); - end if; - end Controlled_Actions; - - else - Append_To (Res, Relocate_Node (N)); - end if; - - -- Restore the tag - - if Save_Tag then - Append_To (Res, - Make_Assignment_Statement (Loc, - Name => - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr_No_Checks (L), - Selector_Name => New_Reference_To (First_Tag_Component (T), - Loc)), - Expression => New_Reference_To (Tag_Tmp, Loc))); - end if; - - -- Adjust the target after the assignment when controlled (not in the - -- init proc since it is an initialization more than an assignment). - - if Ctrl_Act then - Append_List_To (Res, - Make_Adjust_Call ( - Ref => Duplicate_Subexpr_Move_Checks (L), - Typ => Etype (L), - Flist_Ref => New_Reference_To (RTE (RE_Global_Final_List), Loc), - With_Attach => Make_Integer_Literal (Loc, 0))); - end if; - - return Res; - - exception - -- Could use comment here ??? - - when RE_Not_Available => - return Empty_List; - end Make_Tag_Ctrl_Assignment; - - ------------------------------------ - -- Possible_Bit_Aligned_Component -- - ------------------------------------ - - function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean is - begin - case Nkind (N) is - - -- Case of indexed component - - when N_Indexed_Component => - declare - P : constant Node_Id := Prefix (N); - Ptyp : constant Entity_Id := Etype (P); - - begin - -- If we know the component size and it is less than 64, then - -- we are definitely OK. The back end always does assignment - -- of misaligned small objects correctly. - - if Known_Static_Component_Size (Ptyp) - and then Component_Size (Ptyp) <= 64 - then - return False; - - -- Otherwise, we need to test the prefix, to see if we are - -- indexing from a possibly unaligned component. - - else - return Possible_Bit_Aligned_Component (P); - end if; - end; - - -- Case of selected component - - when N_Selected_Component => - declare - P : constant Node_Id := Prefix (N); - Comp : constant Entity_Id := Entity (Selector_Name (N)); - - begin - -- If there is no component clause, then we are in the clear - -- since the back end will never misalign a large component - -- unless it is forced to do so. In the clear means we need - -- only the recursive test on the prefix. - - if Component_May_Be_Bit_Aligned (Comp) then - return True; - else - return Possible_Bit_Aligned_Component (P); - end if; - end; - - -- If we have neither a record nor array component, it means that - -- we have fallen off the top testing prefixes recursively, and - -- we now have a stand alone object, where we don't have a problem - - when others => - return False; - - end case; - end Possible_Bit_Aligned_Component; - -end Exp_Ch5; |