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Diffstat (limited to 'gcc-4.7/gcc/ada/exp_ch5.adb')
| -rw-r--r-- | gcc-4.7/gcc/ada/exp_ch5.adb | 3972 |
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diff --git a/gcc-4.7/gcc/ada/exp_ch5.adb b/gcc-4.7/gcc/ada/exp_ch5.adb deleted file mode 100644 index 2b170a6c4..000000000 --- a/gcc-4.7/gcc/ada/exp_ch5.adb +++ /dev/null @@ -1,3972 +0,0 @@ ------------------------------------------------------------------------------- --- -- --- GNAT COMPILER COMPONENTS -- --- -- --- E X P _ C H 5 -- --- -- --- B o d y -- --- -- --- Copyright (C) 1992-2012, Free Software Foundation, Inc. -- --- -- --- GNAT is free software; you can redistribute it and/or modify it under -- --- terms of the GNU General Public License as published by the Free Soft- -- --- ware Foundation; either version 3, or (at your option) any later ver- -- --- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- --- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- --- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- --- for more details. You should have received a copy of the GNU General -- --- Public License distributed with GNAT; see file COPYING3. If not, go to -- --- http://www.gnu.org/licenses for a complete copy of the license. -- --- -- --- GNAT was originally developed by the GNAT team at New York University. -- --- Extensive contributions were provided by Ada Core Technologies Inc. -- --- -- ------------------------------------------------------------------------------- - -with Aspects; use Aspects; -with Atree; use Atree; -with Checks; use Checks; -with Debug; use Debug; -with Einfo; use Einfo; -with Errout; use Errout; -with Exp_Aggr; use Exp_Aggr; -with Exp_Ch6; use Exp_Ch6; -with Exp_Ch7; use Exp_Ch7; -with Exp_Ch11; use Exp_Ch11; -with Exp_Dbug; use Exp_Dbug; -with Exp_Pakd; use Exp_Pakd; -with Exp_Tss; use Exp_Tss; -with Exp_Util; use Exp_Util; -with Namet; use Namet; -with Nlists; use Nlists; -with Nmake; use Nmake; -with Opt; use Opt; -with Restrict; use Restrict; -with Rident; use Rident; -with Rtsfind; use Rtsfind; -with Sinfo; use Sinfo; -with Sem; use Sem; -with Sem_Aux; use Sem_Aux; -with Sem_Ch3; use Sem_Ch3; -with Sem_Ch8; use Sem_Ch8; -with Sem_Ch13; use Sem_Ch13; -with Sem_Eval; use Sem_Eval; -with Sem_Res; use Sem_Res; -with Sem_Util; use Sem_Util; -with Snames; use Snames; -with Stand; use Stand; -with Stringt; use Stringt; -with Targparm; use Targparm; -with Tbuild; use Tbuild; -with Validsw; use Validsw; - -package body Exp_Ch5 is - - function Change_Of_Representation (N : Node_Id) return Boolean; - -- Determine if the right hand side of assignment N is a type conversion - -- which requires a change of representation. Called only for the array - -- and record cases. - - procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id); - -- N is an assignment which assigns an array value. This routine process - -- the various special cases and checks required for such assignments, - -- including change of representation. Rhs is normally simply the right - -- hand side of the assignment, except that if the right hand side is a - -- type conversion or a qualified expression, then the RHS is the actual - -- expression inside any such type conversions or qualifications. - - function Expand_Assign_Array_Loop - (N : Node_Id; - Larray : Entity_Id; - Rarray : Entity_Id; - L_Type : Entity_Id; - R_Type : Entity_Id; - Ndim : Pos; - Rev : Boolean) return Node_Id; - -- N is an assignment statement which assigns an array value. This routine - -- expands the assignment into a loop (or nested loops for the case of a - -- multi-dimensional array) to do the assignment component by component. - -- Larray and Rarray are the entities of the actual arrays on the left - -- hand and right hand sides. L_Type and R_Type are the types of these - -- arrays (which may not be the same, due to either sliding, or to a - -- change of representation case). Ndim is the number of dimensions and - -- the parameter Rev indicates if the loops run normally (Rev = False), - -- or reversed (Rev = True). The value returned is the constructed - -- loop statement. Auxiliary declarations are inserted before node N - -- using the standard Insert_Actions mechanism. - - procedure Expand_Assign_Record (N : Node_Id); - -- N is an assignment of a non-tagged record value. This routine handles - -- the case where the assignment must be made component by component, - -- either because the target is not byte aligned, or there is a change - -- of representation, or when we have a tagged type with a representation - -- clause (this last case is required because holes in the tagged type - -- might be filled with components from child types). - - procedure Expand_Iterator_Loop (N : Node_Id); - -- Expand loop over arrays and containers that uses the form "for X of C" - -- with an optional subtype mark, or "for Y in C". - - procedure Expand_Predicated_Loop (N : Node_Id); - -- Expand for loop over predicated subtype - - function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id; - -- Generate the necessary code for controlled and tagged assignment, that - -- is to say, finalization of the target before, adjustment of the target - -- after and save and restore of the tag and finalization pointers which - -- are not 'part of the value' and must not be changed upon assignment. N - -- is the original Assignment node. - - ------------------------------ - -- Change_Of_Representation -- - ------------------------------ - - function Change_Of_Representation (N : Node_Id) return Boolean is - Rhs : constant Node_Id := Expression (N); - begin - return - Nkind (Rhs) = N_Type_Conversion - and then - not Same_Representation (Etype (Rhs), Etype (Expression (Rhs))); - end Change_Of_Representation; - - ------------------------- - -- Expand_Assign_Array -- - ------------------------- - - -- There are two issues here. First, do we let Gigi do a block move, or - -- do we expand out into a loop? Second, we need to set the two flags - -- Forwards_OK and Backwards_OK which show whether the block move (or - -- corresponding loops) can be legitimately done in a forwards (low to - -- high) or backwards (high to low) manner. - - procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - - Lhs : constant Node_Id := Name (N); - - Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs); - Act_Rhs : Node_Id := Get_Referenced_Object (Rhs); - - L_Type : constant Entity_Id := - Underlying_Type (Get_Actual_Subtype (Act_Lhs)); - R_Type : Entity_Id := - Underlying_Type (Get_Actual_Subtype (Act_Rhs)); - - L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice; - R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice; - - Crep : constant Boolean := Change_Of_Representation (N); - - Larray : Node_Id; - Rarray : Node_Id; - - Ndim : constant Pos := Number_Dimensions (L_Type); - - Loop_Required : Boolean := False; - -- This switch is set to True if the array move must be done using - -- an explicit front end generated loop. - - procedure Apply_Dereference (Arg : Node_Id); - -- If the argument is an access to an array, and the assignment is - -- converted into a procedure call, apply explicit dereference. - - function Has_Address_Clause (Exp : Node_Id) return Boolean; - -- Test if Exp is a reference to an array whose declaration has - -- an address clause, or it is a slice of such an array. - - function Is_Formal_Array (Exp : Node_Id) return Boolean; - -- Test if Exp is a reference to an array which is either a formal - -- parameter or a slice of a formal parameter. These are the cases - -- where hidden aliasing can occur. - - function Is_Non_Local_Array (Exp : Node_Id) return Boolean; - -- Determine if Exp is a reference to an array variable which is other - -- than an object defined in the current scope, or a slice of such - -- an object. Such objects can be aliased to parameters (unlike local - -- array references). - - ----------------------- - -- Apply_Dereference -- - ----------------------- - - procedure Apply_Dereference (Arg : Node_Id) is - Typ : constant Entity_Id := Etype (Arg); - begin - if Is_Access_Type (Typ) then - Rewrite (Arg, Make_Explicit_Dereference (Loc, - Prefix => Relocate_Node (Arg))); - Analyze_And_Resolve (Arg, Designated_Type (Typ)); - end if; - end Apply_Dereference; - - ------------------------ - -- Has_Address_Clause -- - ------------------------ - - function Has_Address_Clause (Exp : Node_Id) return Boolean is - begin - return - (Is_Entity_Name (Exp) and then - Present (Address_Clause (Entity (Exp)))) - or else - (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp))); - end Has_Address_Clause; - - --------------------- - -- Is_Formal_Array -- - --------------------- - - function Is_Formal_Array (Exp : Node_Id) return Boolean is - begin - return - (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp))) - or else - (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp))); - end Is_Formal_Array; - - ------------------------ - -- Is_Non_Local_Array -- - ------------------------ - - function Is_Non_Local_Array (Exp : Node_Id) return Boolean is - begin - return (Is_Entity_Name (Exp) - and then Scope (Entity (Exp)) /= Current_Scope) - or else (Nkind (Exp) = N_Slice - and then Is_Non_Local_Array (Prefix (Exp))); - end Is_Non_Local_Array; - - -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays - - Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs); - Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs); - - Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs); - Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs); - - -- Start of processing for Expand_Assign_Array - - begin - -- Deal with length check. Note that the length check is done with - -- respect to the right hand side as given, not a possible underlying - -- renamed object, since this would generate incorrect extra checks. - - Apply_Length_Check (Rhs, L_Type); - - -- We start by assuming that the move can be done in either direction, - -- i.e. that the two sides are completely disjoint. - - Set_Forwards_OK (N, True); - Set_Backwards_OK (N, True); - - -- Normally it is only the slice case that can lead to overlap, and - -- explicit checks for slices are made below. But there is one case - -- where the slice can be implicit and invisible to us: when we have a - -- one dimensional array, and either both operands are parameters, or - -- one is a parameter (which can be a slice passed by reference) and the - -- other is a non-local variable. In this case the parameter could be a - -- slice that overlaps with the other operand. - - -- However, if the array subtype is a constrained first subtype in the - -- parameter case, then we don't have to worry about overlap, since - -- slice assignments aren't possible (other than for a slice denoting - -- the whole array). - - -- Note: No overlap is possible if there is a change of representation, - -- so we can exclude this case. - - if Ndim = 1 - and then not Crep - and then - ((Lhs_Formal and Rhs_Formal) - or else - (Lhs_Formal and Rhs_Non_Local_Var) - or else - (Rhs_Formal and Lhs_Non_Local_Var)) - and then - (not Is_Constrained (Etype (Lhs)) - or else not Is_First_Subtype (Etype (Lhs))) - - -- In the case of compiling for the Java or .NET Virtual Machine, - -- slices are always passed by making a copy, so we don't have to - -- worry about overlap. We also want to prevent generation of "<" - -- comparisons for array addresses, since that's a meaningless - -- operation on the VM. - - and then VM_Target = No_VM - then - Set_Forwards_OK (N, False); - Set_Backwards_OK (N, False); - - -- Note: the bit-packed case is not worrisome here, since if we have - -- a slice passed as a parameter, it is always aligned on a byte - -- boundary, and if there are no explicit slices, the assignment - -- can be performed directly. - end if; - - -- If either operand has an address clause clear Backwards_OK and - -- Forwards_OK, since we cannot tell if the operands overlap. We - -- exclude this treatment when Rhs is an aggregate, since we know - -- that overlap can't occur. - - if (Has_Address_Clause (Lhs) and then Nkind (Rhs) /= N_Aggregate) - or else Has_Address_Clause (Rhs) - then - Set_Forwards_OK (N, False); - Set_Backwards_OK (N, False); - end if; - - -- We certainly must use a loop for change of representation and also - -- we use the operand of the conversion on the right hand side as the - -- effective right hand side (the component types must match in this - -- situation). - - if Crep then - Act_Rhs := Get_Referenced_Object (Rhs); - R_Type := Get_Actual_Subtype (Act_Rhs); - Loop_Required := True; - - -- We require a loop if the left side is possibly bit unaligned - - elsif Possible_Bit_Aligned_Component (Lhs) - or else - Possible_Bit_Aligned_Component (Rhs) - then - Loop_Required := True; - - -- Arrays with controlled components are expanded into a loop to force - -- calls to Adjust at the component level. - - elsif Has_Controlled_Component (L_Type) then - Loop_Required := True; - - -- If object is atomic, we cannot tolerate a loop - - elsif Is_Atomic_Object (Act_Lhs) - or else - Is_Atomic_Object (Act_Rhs) - then - return; - - -- Loop is required if we have atomic components since we have to - -- be sure to do any accesses on an element by element basis. - - elsif Has_Atomic_Components (L_Type) - or else Has_Atomic_Components (R_Type) - or else Is_Atomic (Component_Type (L_Type)) - or else Is_Atomic (Component_Type (R_Type)) - then - Loop_Required := True; - - -- Case where no slice is involved - - elsif not L_Slice and not R_Slice then - - -- The following code deals with the case of unconstrained bit packed - -- arrays. The problem is that the template for such arrays contains - -- the bounds of the actual source level array, but the copy of an - -- entire array requires the bounds of the underlying array. It would - -- be nice if the back end could take care of this, but right now it - -- does not know how, so if we have such a type, then we expand out - -- into a loop, which is inefficient but works correctly. If we don't - -- do this, we get the wrong length computed for the array to be - -- moved. The two cases we need to worry about are: - - -- Explicit dereference of an unconstrained packed array type as in - -- the following example: - - -- procedure C52 is - -- type BITS is array(INTEGER range <>) of BOOLEAN; - -- pragma PACK(BITS); - -- type A is access BITS; - -- P1,P2 : A; - -- begin - -- P1 := new BITS (1 .. 65_535); - -- P2 := new BITS (1 .. 65_535); - -- P2.ALL := P1.ALL; - -- end C52; - - -- A formal parameter reference with an unconstrained bit array type - -- is the other case we need to worry about (here we assume the same - -- BITS type declared above): - - -- procedure Write_All (File : out BITS; Contents : BITS); - -- begin - -- File.Storage := Contents; - -- end Write_All; - - -- We expand to a loop in either of these two cases - - -- Question for future thought. Another potentially more efficient - -- approach would be to create the actual subtype, and then do an - -- unchecked conversion to this actual subtype ??? - - Check_Unconstrained_Bit_Packed_Array : declare - - function Is_UBPA_Reference (Opnd : Node_Id) return Boolean; - -- Function to perform required test for the first case, above - -- (dereference of an unconstrained bit packed array). - - ----------------------- - -- Is_UBPA_Reference -- - ----------------------- - - function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is - Typ : constant Entity_Id := Underlying_Type (Etype (Opnd)); - P_Type : Entity_Id; - Des_Type : Entity_Id; - - begin - if Present (Packed_Array_Type (Typ)) - and then Is_Array_Type (Packed_Array_Type (Typ)) - and then not Is_Constrained (Packed_Array_Type (Typ)) - then - return True; - - elsif Nkind (Opnd) = N_Explicit_Dereference then - P_Type := Underlying_Type (Etype (Prefix (Opnd))); - - if not Is_Access_Type (P_Type) then - return False; - - else - Des_Type := Designated_Type (P_Type); - return - Is_Bit_Packed_Array (Des_Type) - and then not Is_Constrained (Des_Type); - end if; - - else - return False; - end if; - end Is_UBPA_Reference; - - -- Start of processing for Check_Unconstrained_Bit_Packed_Array - - begin - if Is_UBPA_Reference (Lhs) - or else - Is_UBPA_Reference (Rhs) - then - Loop_Required := True; - - -- Here if we do not have the case of a reference to a bit packed - -- unconstrained array case. In this case gigi can most certainly - -- handle the assignment if a forwards move is allowed. - - -- (could it handle the backwards case also???) - - elsif Forwards_OK (N) then - return; - end if; - end Check_Unconstrained_Bit_Packed_Array; - - -- The back end can always handle the assignment if the right side is a - -- string literal (note that overlap is definitely impossible in this - -- case). If the type is packed, a string literal is always converted - -- into an aggregate, except in the case of a null slice, for which no - -- aggregate can be written. In that case, rewrite the assignment as a - -- null statement, a length check has already been emitted to verify - -- that the range of the left-hand side is empty. - - -- Note that this code is not executed if we have an assignment of a - -- string literal to a non-bit aligned component of a record, a case - -- which cannot be handled by the backend. - - elsif Nkind (Rhs) = N_String_Literal then - if String_Length (Strval (Rhs)) = 0 - and then Is_Bit_Packed_Array (L_Type) - then - Rewrite (N, Make_Null_Statement (Loc)); - Analyze (N); - end if; - - return; - - -- If either operand is bit packed, then we need a loop, since we can't - -- be sure that the slice is byte aligned. Similarly, if either operand - -- is a possibly unaligned slice, then we need a loop (since the back - -- end cannot handle unaligned slices). - - elsif Is_Bit_Packed_Array (L_Type) - or else Is_Bit_Packed_Array (R_Type) - or else Is_Possibly_Unaligned_Slice (Lhs) - or else Is_Possibly_Unaligned_Slice (Rhs) - then - Loop_Required := True; - - -- If we are not bit-packed, and we have only one slice, then no overlap - -- is possible except in the parameter case, so we can let the back end - -- handle things. - - elsif not (L_Slice and R_Slice) then - if Forwards_OK (N) then - return; - end if; - end if; - - -- If the right-hand side is a string literal, introduce a temporary for - -- it, for use in the generated loop that will follow. - - if Nkind (Rhs) = N_String_Literal then - declare - Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Rhs); - 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. - - -- Note: We propagate Parent to the conversion nodes to generate - -- a well-formed subtree. - - if Nkind (Act_Lhs) = N_Slice then - Larray := Prefix (Act_Lhs); - else - Larray := Act_Lhs; - - if Is_Private_Type (Etype (Larray)) then - declare - Par : constant Node_Id := Parent (Larray); - begin - Larray := - Unchecked_Convert_To - (Underlying_Type (Etype (Larray)), Larray); - Set_Parent (Larray, Par); - end; - 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 - declare - Par : constant Node_Id := Parent (Rarray); - begin - Rarray := - Unchecked_Convert_To - (Underlying_Type (Etype (Rarray)), Rarray); - Set_Parent (Rarray, Par); - end; - end if; - end if; - - -- If both sides are slices, we must figure out whether it is safe - -- to do the move in one direction or the other. It is always safe - -- if there is a change of representation since obviously two arrays - -- with different representations cannot possibly overlap. - - if (not Crep) and L_Slice and R_Slice then - Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs)); - Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs)); - - -- If both left and right hand arrays are entity names, and refer - -- to different entities, then we know that the move is safe (the - -- two storage areas are completely disjoint). - - if Is_Entity_Name (Act_L_Array) - and then Is_Entity_Name (Act_R_Array) - and then Entity (Act_L_Array) /= Entity (Act_R_Array) - then - null; - - -- Otherwise, we assume the worst, which is that the two arrays - -- are the same array. There is no need to check if we know that - -- is the case, because if we don't know it, we still have to - -- assume it! - - -- Generally if the same array is involved, then we have an - -- overlapping case. We will have to really assume the worst (i.e. - -- set neither of the OK flags) unless we can determine the lower - -- or upper bounds at compile time and compare them. - - else - Cresult := - Compile_Time_Compare - (Left_Lo, Right_Lo, Assume_Valid => True); - - if Cresult = Unknown then - Cresult := - Compile_Time_Compare - (Left_Hi, Right_Hi, Assume_Valid => True); - end if; - - case Cresult is - when LT | LE | EQ => Set_Backwards_OK (N, False); - when GT | GE => Set_Forwards_OK (N, False); - when NE | Unknown => Set_Backwards_OK (N, False); - Set_Forwards_OK (N, False); - end case; - end if; - end if; - - -- If after that analysis Loop_Required is False, meaning that we - -- have not discovered some non-overlap reason for requiring a loop, - -- then the outcome depends on the capabilities of the back end. - - if not Loop_Required then - - -- The GCC back end can deal with all cases of overlap by falling - -- back to memmove if it cannot use a more efficient approach. - - if VM_Target = No_VM and not AAMP_On_Target then - return; - - -- Assume other back ends can handle it if Forwards_OK is set - - elsif Forwards_OK (N) then - return; - - -- If Forwards_OK is not set, the back end will need something - -- like memmove to handle the move. For now, this processing is - -- activated using the .s debug flag (-gnatd.s). - - elsif Debug_Flag_Dot_S then - return; - end if; - end if; - - -- At this stage we have to generate an explicit loop, and we have - -- the following cases: - - -- Forwards_OK = True - - -- Rnn : right_index := right_index'First; - -- for Lnn in left-index loop - -- left (Lnn) := right (Rnn); - -- Rnn := right_index'Succ (Rnn); - -- end loop; - - -- Note: the above code MUST be analyzed with checks off, because - -- otherwise the Succ could overflow. But in any case this is more - -- efficient! - - -- Forwards_OK = False, Backwards_OK = True - - -- Rnn : right_index := right_index'Last; - -- for Lnn in reverse left-index loop - -- left (Lnn) := right (Rnn); - -- Rnn := right_index'Pred (Rnn); - -- end loop; - - -- Note: the above code MUST be analyzed with checks off, because - -- otherwise the Pred could overflow. But in any case this is more - -- efficient! - - -- Forwards_OK = Backwards_OK = False - - -- This only happens if we have the same array on each side. It is - -- possible to create situations using overlays that violate this, - -- but we simply do not promise to get this "right" in this case. - - -- There are two possible subcases. If the No_Implicit_Conditionals - -- restriction is set, then we generate the following code: - - -- declare - -- T : constant <operand-type> := rhs; - -- begin - -- lhs := T; - -- end; - - -- If implicit conditionals are permitted, then we generate: - - -- if Left_Lo <= Right_Lo then - -- <code for Forwards_OK = True above> - -- else - -- <code for Backwards_OK = True above> - -- end if; - - -- In order to detect possible aliasing, we examine the renamed - -- expression when the source or target is a renaming. However, - -- the renaming may be intended to capture an address that may be - -- affected by subsequent code, and therefore we must recover - -- the actual entity for the expansion that follows, not the - -- object it renames. In particular, if source or target designate - -- a portion of a dynamically allocated object, the pointer to it - -- may be reassigned but the renaming preserves the proper location. - - if Is_Entity_Name (Rhs) - and then - Nkind (Parent (Entity (Rhs))) = N_Object_Renaming_Declaration - and then Nkind (Act_Rhs) = N_Slice - then - Rarray := Rhs; - end if; - - if Is_Entity_Name (Lhs) - and then - Nkind (Parent (Entity (Lhs))) = N_Object_Renaming_Declaration - and then Nkind (Act_Lhs) = N_Slice - then - Larray := Lhs; - end if; - - -- Cases where either Forwards_OK or Backwards_OK is true - - if Forwards_OK (N) or else Backwards_OK (N) then - if Needs_Finalization (Component_Type (L_Type)) - and then Base_Type (L_Type) = Base_Type (R_Type) - and then Ndim = 1 - and then not No_Ctrl_Actions (N) - then - declare - Proc : constant Entity_Id := - TSS (Base_Type (L_Type), TSS_Slice_Assign); - Actuals : List_Id; - - begin - Apply_Dereference (Larray); - Apply_Dereference (Rarray); - Actuals := New_List ( - Duplicate_Subexpr (Larray, Name_Req => True), - Duplicate_Subexpr (Rarray, Name_Req => True), - Duplicate_Subexpr (Left_Lo, Name_Req => True), - Duplicate_Subexpr (Left_Hi, Name_Req => True), - Duplicate_Subexpr (Right_Lo, Name_Req => True), - Duplicate_Subexpr (Right_Hi, Name_Req => True)); - - Append_To (Actuals, - New_Occurrence_Of ( - Boolean_Literals (not Forwards_OK (N)), Loc)); - - Rewrite (N, - Make_Procedure_Call_Statement (Loc, - Name => New_Reference_To (Proc, Loc), - Parameter_Associations => Actuals)); - end; - - else - Rewrite (N, - Expand_Assign_Array_Loop - (N, Larray, Rarray, L_Type, R_Type, Ndim, - Rev => not Forwards_OK (N))); - end if; - - -- Case of both are false with No_Implicit_Conditionals - - elsif Restriction_Active (No_Implicit_Conditionals) then - declare - T : constant Entity_Id := - Make_Defining_Identifier (Loc, Chars => Name_T); - - begin - Rewrite (N, - Make_Block_Statement (Loc, - Declarations => New_List ( - Make_Object_Declaration (Loc, - Defining_Identifier => T, - Constant_Present => True, - Object_Definition => - New_Occurrence_Of (Etype (Rhs), Loc), - Expression => Relocate_Node (Rhs))), - - Handled_Statement_Sequence => - Make_Handled_Sequence_Of_Statements (Loc, - Statements => New_List ( - Make_Assignment_Statement (Loc, - Name => Relocate_Node (Lhs), - Expression => New_Occurrence_Of (T, Loc)))))); - end; - - -- Case of both are false with implicit conditionals allowed - - else - -- Before we generate this code, we must ensure that the left and - -- right side array types are defined. They may be itypes, and we - -- cannot let them be defined inside the if, since the first use - -- in the then may not be executed. - - Ensure_Defined (L_Type, N); - Ensure_Defined (R_Type, N); - - -- We normally compare addresses to find out which way round to - -- do the loop, since this is reliable, and handles the cases of - -- parameters, conversions etc. But we can't do that in the bit - -- packed case or the VM case, because addresses don't work there. - - if not Is_Bit_Packed_Array (L_Type) and then VM_Target = No_VM then - Condition := - Make_Op_Le (Loc, - Left_Opnd => - Unchecked_Convert_To (RTE (RE_Integer_Address), - Make_Attribute_Reference (Loc, - Prefix => - Make_Indexed_Component (Loc, - Prefix => - Duplicate_Subexpr_Move_Checks (Larray, True), - Expressions => New_List ( - Make_Attribute_Reference (Loc, - Prefix => - New_Reference_To - (L_Index_Typ, Loc), - Attribute_Name => Name_First))), - Attribute_Name => Name_Address)), - - Right_Opnd => - Unchecked_Convert_To (RTE (RE_Integer_Address), - Make_Attribute_Reference (Loc, - Prefix => - Make_Indexed_Component (Loc, - Prefix => - Duplicate_Subexpr_Move_Checks (Rarray, True), - Expressions => New_List ( - Make_Attribute_Reference (Loc, - Prefix => - New_Reference_To - (R_Index_Typ, Loc), - Attribute_Name => Name_First))), - Attribute_Name => Name_Address))); - - -- For the bit packed and VM cases we use the bounds. That's OK, - -- because we don't have to worry about parameters, since they - -- cannot cause overlap. Perhaps we should worry about weird slice - -- conversions ??? - - else - -- Copy the bounds - - Cleft_Lo := New_Copy_Tree (Left_Lo); - Cright_Lo := New_Copy_Tree (Right_Lo); - - -- If the types do not match we add an implicit conversion - -- here to ensure proper match - - if Etype (Left_Lo) /= Etype (Right_Lo) then - Cright_Lo := - Unchecked_Convert_To (Etype (Left_Lo), Cright_Lo); - end if; - - -- Reset the Analyzed flag, because the bounds of the index - -- type itself may be universal, and must must be reanalyzed - -- to acquire the proper type for the back end. - - Set_Analyzed (Cleft_Lo, False); - Set_Analyzed (Cright_Lo, False); - - Condition := - Make_Op_Le (Loc, - Left_Opnd => Cleft_Lo, - Right_Opnd => Cright_Lo); - end if; - - if Needs_Finalization (Component_Type (L_Type)) - and then Base_Type (L_Type) = Base_Type (R_Type) - and then Ndim = 1 - and then not No_Ctrl_Actions (N) - then - - -- Call TSS procedure for array assignment, passing the - -- explicit bounds of right and left hand sides. - - declare - Proc : constant Entity_Id := - TSS (Base_Type (L_Type), TSS_Slice_Assign); - Actuals : List_Id; - - begin - Apply_Dereference (Larray); - Apply_Dereference (Rarray); - Actuals := New_List ( - Duplicate_Subexpr (Larray, Name_Req => True), - Duplicate_Subexpr (Rarray, Name_Req => True), - Duplicate_Subexpr (Left_Lo, Name_Req => True), - Duplicate_Subexpr (Left_Hi, Name_Req => True), - Duplicate_Subexpr (Right_Lo, Name_Req => True), - Duplicate_Subexpr (Right_Hi, Name_Req => True)); - - Append_To (Actuals, - Make_Op_Not (Loc, - Right_Opnd => Condition)); - - Rewrite (N, - Make_Procedure_Call_Statement (Loc, - Name => New_Reference_To (Proc, Loc), - Parameter_Associations => Actuals)); - end; - - else - Rewrite (N, - Make_Implicit_If_Statement (N, - Condition => Condition, - - Then_Statements => New_List ( - Expand_Assign_Array_Loop - (N, Larray, Rarray, L_Type, R_Type, Ndim, - Rev => False)), - - Else_Statements => New_List ( - Expand_Assign_Array_Loop - (N, Larray, Rarray, L_Type, R_Type, Ndim, - Rev => True)))); - end if; - end if; - - Analyze (N, Suppress => All_Checks); - end; - - exception - when RE_Not_Available => - return; - end Expand_Assign_Array; - - ------------------------------ - -- Expand_Assign_Array_Loop -- - ------------------------------ - - -- The following is an example of the loop generated for the case of a - -- two-dimensional array: - - -- declare - -- R2b : Tm1X1 := 1; - -- begin - -- for L1b in 1 .. 100 loop - -- declare - -- R4b : Tm1X2 := 1; - -- begin - -- for L3b in 1 .. 100 loop - -- vm1 (L1b, L3b) := vm2 (R2b, R4b); - -- R4b := Tm1X2'succ(R4b); - -- end loop; - -- end; - -- R2b := Tm1X1'succ(R2b); - -- end loop; - -- end; - - -- Here Rev is False, and Tm1Xn are the subscript types for the right hand - -- side. The declarations of R2b and R4b are inserted before the original - -- assignment statement. - - function Expand_Assign_Array_Loop - (N : Node_Id; - Larray : Entity_Id; - Rarray : Entity_Id; - L_Type : Entity_Id; - R_Type : Entity_Id; - Ndim : Pos; - Rev : Boolean) return Node_Id - is - Loc : constant Source_Ptr := Sloc (N); - - Lnn : array (1 .. Ndim) of Entity_Id; - Rnn : array (1 .. Ndim) of Entity_Id; - -- Entities used as subscripts on left and right sides - - L_Index_Type : array (1 .. Ndim) of Entity_Id; - R_Index_Type : array (1 .. Ndim) of Entity_Id; - -- Left and right index types - - Assign : Node_Id; - - F_Or_L : Name_Id; - S_Or_P : Name_Id; - - function Build_Step (J : Nat) return Node_Id; - -- The increment step for the index of the right-hand side is written - -- as an attribute reference (Succ or Pred). This function returns - -- the corresponding node, which is placed at the end of the loop body. - - ---------------- - -- Build_Step -- - ---------------- - - function Build_Step (J : Nat) return Node_Id is - Step : Node_Id; - Lim : Name_Id; - - begin - if Rev then - Lim := Name_First; - else - Lim := Name_Last; - end if; - - Step := - 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)))); - - -- Note that on the last iteration of the loop, the index is increased - -- (or decreased) past the corresponding bound. This is consistent with - -- the C semantics of the back-end, where such an off-by-one value on a - -- dead index variable is OK. However, in CodePeer mode this leads to - -- spurious warnings, and thus we place a guard around the attribute - -- reference. For obvious reasons we only do this for CodePeer. - - if CodePeer_Mode then - Step := - Make_If_Statement (Loc, - Condition => - Make_Op_Ne (Loc, - Left_Opnd => New_Occurrence_Of (Lnn (J), Loc), - Right_Opnd => - Make_Attribute_Reference (Loc, - Prefix => New_Occurrence_Of (L_Index_Type (J), Loc), - Attribute_Name => Lim)), - Then_Statements => New_List (Step)); - end if; - - return Step; - end Build_Step; - - -- Start of processing for Expand_Assign_Array_Loop - - 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_Temporary (Loc, 'L'); - Rnn (J) := Make_Temporary (Loc, '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, Build_Step (J)))))); - end loop; - - return Assign; - end Expand_Assign_Array_Loop; - - -------------------------- - -- Expand_Assign_Record -- - -------------------------- - - procedure Expand_Assign_Record (N : Node_Id) is - Lhs : constant Node_Id := Name (N); - Rhs : Node_Id := Expression (N); - L_Typ : constant Entity_Id := Base_Type (Etype (Lhs)); - - begin - -- If change of representation, then extract the real right hand side - -- from the type conversion, and proceed with component-wise assignment, - -- since the two types are not the same as far as the back end is - -- concerned. - - if Change_Of_Representation (N) then - Rhs := Expression (Rhs); - - -- If this may be a case of a large bit aligned component, then proceed - -- with component-wise assignment, to avoid possible clobbering of other - -- components sharing bits in the first or last byte of the component to - -- be assigned. - - elsif Possible_Bit_Aligned_Component (Lhs) - or - Possible_Bit_Aligned_Component (Rhs) - then - null; - - -- If we have a tagged type that has a complete record representation - -- clause, we must do we must do component-wise assignments, since child - -- types may have used gaps for their components, and we might be - -- dealing with a view conversion. - - elsif Is_Fully_Repped_Tagged_Type (L_Typ) then - null; - - -- If neither condition met, then nothing special to do, the back end - -- can handle assignment of the entire component as a single entity. - - else - return; - end if; - - -- At this stage we know that we must do a component wise assignment - - declare - Loc : constant Source_Ptr := Sloc (N); - R_Typ : constant Entity_Id := Base_Type (Etype (Rhs)); - Decl : constant Node_Id := Declaration_Node (R_Typ); - RDef : Node_Id; - F : Entity_Id; - - function Find_Component - (Typ : Entity_Id; - Comp : Entity_Id) return Entity_Id; - -- Find the component with the given name in the underlying record - -- declaration for Typ. We need to use the actual entity because the - -- type may be private and resolution by identifier alone would fail. - - function Make_Component_List_Assign - (CL : Node_Id; - U_U : Boolean := False) return List_Id; - -- Returns a sequence of statements to assign the components that - -- are referenced in the given component list. The flag U_U is - -- used to force the usage of the inferred value of the variant - -- part expression as the switch for the generated case statement. - - function Make_Field_Assign - (C : Entity_Id; - U_U : Boolean := False) return Node_Id; - -- Given C, the entity for a discriminant or component, build an - -- assignment for the corresponding field values. The flag U_U - -- signals the presence of an Unchecked_Union and forces the usage - -- of the inferred discriminant value of C as the right hand side - -- of the assignment. - - function Make_Field_Assigns (CI : List_Id) return List_Id; - -- Given CI, a component items list, construct series of statements - -- for fieldwise assignment of the corresponding components. - - -------------------- - -- Find_Component -- - -------------------- - - function Find_Component - (Typ : Entity_Id; - Comp : Entity_Id) return Entity_Id - is - Utyp : constant Entity_Id := Underlying_Type (Typ); - C : Entity_Id; - - begin - C := First_Entity (Utyp); - while Present (C) loop - if Chars (C) = Chars (Comp) then - return C; - end if; - - Next_Entity (C); - end loop; - - raise Program_Error; - end Find_Component; - - -------------------------------- - -- Make_Component_List_Assign -- - -------------------------------- - - function Make_Component_List_Assign - (CL : Node_Id; - U_U : Boolean := False) return List_Id - is - CI : constant List_Id := Component_Items (CL); - VP : constant Node_Id := Variant_Part (CL); - - Alts : List_Id; - DC : Node_Id; - DCH : List_Id; - Expr : Node_Id; - Result : List_Id; - V : Node_Id; - - begin - Result := Make_Field_Assigns (CI); - - if Present (VP) then - V := First_Non_Pragma (Variants (VP)); - Alts := New_List; - while Present (V) loop - DCH := New_List; - DC := First (Discrete_Choices (V)); - while Present (DC) loop - Append_To (DCH, New_Copy_Tree (DC)); - Next (DC); - end loop; - - Append_To (Alts, - Make_Case_Statement_Alternative (Loc, - Discrete_Choices => DCH, - Statements => - Make_Component_List_Assign (Component_List (V)))); - Next_Non_Pragma (V); - end loop; - - -- If we have an Unchecked_Union, use the value of the inferred - -- discriminant of the variant part expression as the switch - -- for the case statement. The case statement may later be - -- folded. - - if U_U then - Expr := - New_Copy (Get_Discriminant_Value ( - Entity (Name (VP)), - Etype (Rhs), - Discriminant_Constraint (Etype (Rhs)))); - else - Expr := - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr (Rhs), - Selector_Name => - Make_Identifier (Loc, Chars (Name (VP)))); - end if; - - Append_To (Result, - Make_Case_Statement (Loc, - Expression => Expr, - Alternatives => Alts)); - end if; - - return Result; - end Make_Component_List_Assign; - - ----------------------- - -- Make_Field_Assign -- - ----------------------- - - function Make_Field_Assign - (C : Entity_Id; - U_U : Boolean := False) return Node_Id - is - A : Node_Id; - Expr : Node_Id; - - begin - -- In the case of an Unchecked_Union, use the discriminant - -- constraint value as on the right hand side of the assignment. - - if U_U then - Expr := - New_Copy (Get_Discriminant_Value (C, - Etype (Rhs), - Discriminant_Constraint (Etype (Rhs)))); - else - Expr := - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr (Rhs), - Selector_Name => New_Occurrence_Of (C, Loc)); - end if; - - A := - Make_Assignment_Statement (Loc, - Name => - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr (Lhs), - Selector_Name => - New_Occurrence_Of (Find_Component (L_Typ, C), Loc)), - Expression => Expr); - - -- Set Assignment_OK, so discriminants can be assigned - - Set_Assignment_OK (Name (A), True); - - if Componentwise_Assignment (N) - and then Nkind (Name (A)) = N_Selected_Component - and then Chars (Selector_Name (Name (A))) = Name_uParent - then - Set_Componentwise_Assignment (A); - end if; - - return A; - end Make_Field_Assign; - - ------------------------ - -- Make_Field_Assigns -- - ------------------------ - - function Make_Field_Assigns (CI : List_Id) return List_Id is - Item : Node_Id; - Result : List_Id; - - begin - Item := First (CI); - Result := New_List; - - while Present (Item) loop - - -- Look for components, but exclude _tag field assignment if - -- the special Componentwise_Assignment flag is set. - - if Nkind (Item) = N_Component_Declaration - and then not (Is_Tag (Defining_Identifier (Item)) - and then Componentwise_Assignment (N)) - then - Append_To - (Result, Make_Field_Assign (Defining_Identifier (Item))); - end if; - - Next (Item); - end loop; - - return Result; - end Make_Field_Assigns; - - -- Start of processing for Expand_Assign_Record - - begin - -- Note that we use the base types for this processing. This results - -- in some extra work in the constrained case, but the change of - -- representation case is so unusual that it is not worth the effort. - - -- First copy the discriminants. This is done unconditionally. It - -- is required in the unconstrained left side case, and also in the - -- case where this assignment was constructed during the expansion - -- of a type conversion (since initialization of discriminants is - -- suppressed in this case). It is unnecessary but harmless in - -- other cases. - - if Has_Discriminants (L_Typ) then - F := First_Discriminant (R_Typ); - while Present (F) loop - - -- If we are expanding the initialization of a derived record - -- that constrains or renames discriminants of the parent, we - -- must use the corresponding discriminant in the parent. - - declare - CF : Entity_Id; - - begin - if Inside_Init_Proc - and then Present (Corresponding_Discriminant (F)) - then - CF := Corresponding_Discriminant (F); - else - CF := F; - end if; - - if Is_Unchecked_Union (Base_Type (R_Typ)) then - - -- Within an initialization procedure this is the - -- assignment to an unchecked union component, in which - -- case there is no discriminant to initialize. - - if Inside_Init_Proc then - null; - - else - -- The assignment is part of a conversion from a - -- derived unchecked union type with an inferable - -- discriminant, to a parent type. - - Insert_Action (N, Make_Field_Assign (CF, True)); - end if; - - else - Insert_Action (N, Make_Field_Assign (CF)); - end if; - - Next_Discriminant (F); - end; - end loop; - end if; - - -- We know the underlying type is a record, but its current view - -- may be private. We must retrieve the usable record declaration. - - if Nkind_In (Decl, N_Private_Type_Declaration, - N_Private_Extension_Declaration) - and then Present (Full_View (R_Typ)) - then - RDef := Type_Definition (Declaration_Node (Full_View (R_Typ))); - else - RDef := Type_Definition (Decl); - end if; - - if Nkind (RDef) = N_Derived_Type_Definition then - RDef := Record_Extension_Part (RDef); - end if; - - if Nkind (RDef) = N_Record_Definition - and then Present (Component_List (RDef)) - then - if Is_Unchecked_Union (R_Typ) then - Insert_Actions (N, - Make_Component_List_Assign (Component_List (RDef), True)); - else - Insert_Actions - (N, Make_Component_List_Assign (Component_List (RDef))); - end if; - - Rewrite (N, Make_Null_Statement (Loc)); - end if; - end; - end Expand_Assign_Record; - - ----------------------------------- - -- Expand_N_Assignment_Statement -- - ----------------------------------- - - -- This procedure implements various cases where an assignment statement - -- cannot just be passed on to the back end in untransformed state. - - procedure Expand_N_Assignment_Statement (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Crep : constant Boolean := Change_Of_Representation (N); - Lhs : constant Node_Id := Name (N); - Rhs : constant Node_Id := Expression (N); - Typ : constant Entity_Id := Underlying_Type (Etype (Lhs)); - Exp : Node_Id; - - begin - -- Special case to check right away, if the Componentwise_Assignment - -- flag is set, this is a reanalysis from the expansion of the primitive - -- assignment procedure for a tagged type, and all we need to do is to - -- expand to assignment of components, because otherwise, we would get - -- infinite recursion (since this looks like a tagged assignment which - -- would normally try to *call* the primitive assignment procedure). - - if Componentwise_Assignment (N) then - Expand_Assign_Record (N); - return; - end if; - - -- Defend against invalid subscripts on left side if we are in standard - -- validity checking mode. No need to do this if we are checking all - -- subscripts. - - -- Note that we do this right away, because there are some early return - -- paths in this procedure, and this is required on all paths. - - if Validity_Checks_On - and then Validity_Check_Default - and then not Validity_Check_Subscripts - then - Check_Valid_Lvalue_Subscripts (Lhs); - end if; - - -- Ada 2005 (AI-327): Handle assignment to priority of protected object - - -- Rewrite an assignment to X'Priority into a run-time call - - -- For example: X'Priority := New_Prio_Expr; - -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr); - - -- Note that although X'Priority is notionally an object, it is quite - -- deliberately not defined as an aliased object in the RM. This means - -- that it works fine to rewrite it as a call, without having to worry - -- about complications that would other arise from X'Priority'Access, - -- which is illegal, because of the lack of aliasing. - - if Ada_Version >= Ada_2005 then - declare - Call : Node_Id; - Conctyp : Entity_Id; - Ent : Entity_Id; - Subprg : Entity_Id; - RT_Subprg_Name : Node_Id; - - begin - -- Handle chains of renamings - - Ent := Name (N); - while Nkind (Ent) in N_Has_Entity - and then Present (Entity (Ent)) - and then Present (Renamed_Object (Entity (Ent))) - loop - Ent := Renamed_Object (Entity (Ent)); - end loop; - - -- The attribute Priority applied to protected objects has been - -- previously expanded into a call to the Get_Ceiling run-time - -- subprogram. - - if Nkind (Ent) = N_Function_Call - and then (Entity (Name (Ent)) = RTE (RE_Get_Ceiling) - or else - Entity (Name (Ent)) = RTE (RO_PE_Get_Ceiling)) - then - -- Look for the enclosing concurrent type - - Conctyp := Current_Scope; - while not Is_Concurrent_Type (Conctyp) loop - Conctyp := Scope (Conctyp); - end loop; - - pragma Assert (Is_Protected_Type (Conctyp)); - - -- Generate the first actual of the call - - Subprg := Current_Scope; - while not Present (Protected_Body_Subprogram (Subprg)) loop - Subprg := Scope (Subprg); - end loop; - - -- Select the appropriate run-time call - - if Number_Entries (Conctyp) = 0 then - RT_Subprg_Name := - New_Reference_To (RTE (RE_Set_Ceiling), Loc); - else - RT_Subprg_Name := - New_Reference_To (RTE (RO_PE_Set_Ceiling), Loc); - end if; - - Call := - Make_Procedure_Call_Statement (Loc, - Name => RT_Subprg_Name, - Parameter_Associations => New_List ( - New_Copy_Tree (First (Parameter_Associations (Ent))), - Relocate_Node (Expression (N)))); - - Rewrite (N, Call); - Analyze (N); - return; - end if; - end; - end if; - - -- Deal with assignment checks unless suppressed - - if not Suppress_Assignment_Checks (N) then - - -- First deal with generation of range check if required - - if Do_Range_Check (Rhs) then - Set_Do_Range_Check (Rhs, False); - Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed); - end if; - - -- Then generate predicate check if required - - Apply_Predicate_Check (Rhs, Typ); - end if; - - -- Check for a special case where a high level transformation is - -- required. If we have either of: - - -- P.field := rhs; - -- P (sub) := rhs; - - -- where P is a reference to a bit packed array, then we have to unwind - -- the assignment. The exact meaning of being a reference to a bit - -- packed array is as follows: - - -- An indexed component whose prefix is a bit packed array is a - -- reference to a bit packed array. - - -- An indexed component or selected component whose prefix is a - -- reference to a bit packed array is itself a reference ot a - -- bit packed array. - - -- The required transformation is - - -- Tnn : prefix_type := P; - -- Tnn.field := rhs; - -- P := Tnn; - - -- or - - -- Tnn : prefix_type := P; - -- Tnn (subscr) := rhs; - -- P := Tnn; - - -- Since P is going to be evaluated more than once, any subscripts - -- in P must have their evaluation forced. - - if Nkind_In (Lhs, N_Indexed_Component, N_Selected_Component) - and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs)) - then - declare - BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs)); - BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr); - Tnn : constant Entity_Id := - Make_Temporary (Loc, 'T', BPAR_Expr); - - begin - -- Insert the post assignment first, because we want to copy the - -- BPAR_Expr tree before it gets analyzed in the context of the - -- pre assignment. Note that we do not analyze the post assignment - -- yet (we cannot till we have completed the analysis of the pre - -- assignment). As usual, the analysis of this post assignment - -- will happen on its own when we "run into" it after finishing - -- the current assignment. - - Insert_After (N, - Make_Assignment_Statement (Loc, - Name => New_Copy_Tree (BPAR_Expr), - Expression => New_Occurrence_Of (Tnn, Loc))); - - -- At this stage BPAR_Expr is a reference to a bit packed array - -- where the reference was not expanded in the original tree, - -- since it was on the left side of an assignment. But in the - -- pre-assignment statement (the object definition), BPAR_Expr - -- will end up on the right hand side, and must be reexpanded. To - -- achieve this, we reset the analyzed flag of all selected and - -- indexed components down to the actual indexed component for - -- the packed array. - - Exp := BPAR_Expr; - loop - Set_Analyzed (Exp, False); - - if Nkind_In - (Exp, N_Selected_Component, N_Indexed_Component) - then - Exp := Prefix (Exp); - else - exit; - end if; - end loop; - - -- Now we can insert and analyze the pre-assignment - - -- If the right-hand side requires a transient scope, it has - -- already been placed on the stack. However, the declaration is - -- inserted in the tree outside of this scope, and must reflect - -- the proper scope for its variable. This awkward bit is forced - -- by the stricter scope discipline imposed by GCC 2.97. - - declare - Uses_Transient_Scope : constant Boolean := - Scope_Is_Transient - and then N = Node_To_Be_Wrapped; - - begin - if Uses_Transient_Scope then - Push_Scope (Scope (Current_Scope)); - end if; - - Insert_Before_And_Analyze (N, - Make_Object_Declaration (Loc, - Defining_Identifier => Tnn, - Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc), - Expression => BPAR_Expr)); - - if Uses_Transient_Scope then - Pop_Scope; - end if; - end; - - -- Now fix up the original assignment and continue processing - - Rewrite (Prefix (Lhs), - New_Occurrence_Of (Tnn, Loc)); - - -- We do not need to reanalyze that assignment, and we do not need - -- to worry about references to the temporary, but we do need to - -- make sure that the temporary is not marked as a true constant - -- since we now have a generated assignment to it! - - Set_Is_True_Constant (Tnn, False); - end; - end if; - - -- When we have the appropriate type of aggregate in the expression (it - -- has been determined during analysis of the aggregate by setting the - -- delay flag), let's perform in place assignment and thus avoid - -- creating a temporary. - - if Is_Delayed_Aggregate (Rhs) then - Convert_Aggr_In_Assignment (N); - Rewrite (N, Make_Null_Statement (Loc)); - Analyze (N); - return; - end if; - - -- Apply discriminant check if required. If Lhs is an access type to a - -- designated type with discriminants, we must always check. - - if Has_Discriminants (Etype (Lhs)) then - - -- Skip discriminant check if change of representation. Will be - -- done when the change of representation is expanded out. - - if not Crep 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 discriminants 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); - Ubt : Entity_Id := Base_Type (Typ); - - begin - -- In the case of an expander-generated record subtype whose base - -- type still appears private, Typ will have been set to that - -- private type rather than the underlying record type (because - -- Underlying type will have returned the record subtype), so it's - -- necessary to apply Underlying_Type again to the base type to - -- get the record type we need for the discriminant check. Such - -- subtypes can be created for assignments in certain cases, such - -- as within an instantiation passed this kind of private type. - -- It would be good to avoid this special test, but making changes - -- to prevent this odd form of record subtype seems difficult. ??? - - if Is_Private_Type (Ubt) then - Ubt := Underlying_Type (Ubt); - end if; - - Set_Etype (Lhs, Ubt); - Rewrite (Rhs, OK_Convert_To (Base_Type (Ubt), Rhs)); - Apply_Discriminant_Check (Rhs, Ubt, 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 Crep then - Apply_Discriminant_Check (Rhs, Etype (Lhs)); - end if; - - elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then - Apply_Range_Check (Rhs, Etype (Lhs)); - - if Is_Constrained (Etype (Lhs)) then - Apply_Length_Check (Rhs, Etype (Lhs)); - end if; - - if Nkind (Rhs) = N_Allocator then - declare - Target_Typ : constant Entity_Id := Etype (Expression (Rhs)); - C_Es : Check_Result; - - begin - C_Es := - Get_Range_Checks - (Lhs, - Target_Typ, - Etype (Designated_Type (Etype (Lhs)))); - - Insert_Range_Checks - (C_Es, - N, - Target_Typ, - Sloc (Lhs), - Lhs); - end; - end if; - end if; - - -- Apply range check for access type case - - elsif Is_Access_Type (Etype (Lhs)) - and then Nkind (Rhs) = N_Allocator - and then Nkind (Expression (Rhs)) = N_Qualified_Expression - then - Analyze_And_Resolve (Expression (Rhs)); - Apply_Range_Check - (Expression (Rhs), Designated_Type (Etype (Lhs))); - end if; - - -- Ada 2005 (AI-231): Generate the run-time check - - if Is_Access_Type (Typ) - and then Can_Never_Be_Null (Etype (Lhs)) - and then not Can_Never_Be_Null (Etype (Rhs)) - then - Apply_Constraint_Check (Rhs, Etype (Lhs)); - end if; - - -- Ada 2012 (AI05-148): Update current accessibility level if Rhs is a - -- stand-alone obj of an anonymous access type. - - if Is_Access_Type (Typ) - and then Is_Entity_Name (Lhs) - and then Present (Effective_Extra_Accessibility (Entity (Lhs))) then - declare - function Lhs_Entity return Entity_Id; - -- Look through renames to find the underlying entity. - -- For assignment to a rename, we don't care about the - -- Enclosing_Dynamic_Scope of the rename declaration. - - ---------------- - -- Lhs_Entity -- - ---------------- - - function Lhs_Entity return Entity_Id is - Result : Entity_Id := Entity (Lhs); - - begin - while Present (Renamed_Object (Result)) loop - - -- Renamed_Object must return an Entity_Name here - -- because of preceding "Present (E_E_A (...))" test. - - Result := Entity (Renamed_Object (Result)); - end loop; - - return Result; - end Lhs_Entity; - - -- Local Declarations - - Access_Check : constant Node_Id := - Make_Raise_Program_Error (Loc, - Condition => - Make_Op_Gt (Loc, - Left_Opnd => - Dynamic_Accessibility_Level (Rhs), - Right_Opnd => - Make_Integer_Literal (Loc, - Intval => - Scope_Depth - (Enclosing_Dynamic_Scope - (Lhs_Entity)))), - Reason => PE_Accessibility_Check_Failed); - - Access_Level_Update : constant Node_Id := - Make_Assignment_Statement (Loc, - Name => - New_Occurrence_Of - (Effective_Extra_Accessibility - (Entity (Lhs)), Loc), - Expression => - Dynamic_Accessibility_Level (Rhs)); - - begin - if not Accessibility_Checks_Suppressed (Entity (Lhs)) then - Insert_Action (N, Access_Check); - end if; - - Insert_Action (N, Access_Level_Update); - end; - end if; - - -- Case of assignment to a bit packed array element. If there is a - -- change of representation this must be expanded into components, - -- otherwise this is a bit-field assignment. - - if Nkind (Lhs) = N_Indexed_Component - and then Is_Bit_Packed_Array (Etype (Prefix (Lhs))) - then - -- Normal case, no change of representation - - if not Crep then - Expand_Bit_Packed_Element_Set (N); - return; - - -- Change of representation case - - else - -- Generate the following, to force component-by-component - -- assignments in an efficient way. Otherwise each component - -- will require a temporary and two bit-field manipulations. - - -- T1 : Elmt_Type; - -- T1 := RhS; - -- Lhs := T1; - - declare - Tnn : constant Entity_Id := Make_Temporary (Loc, 'T'); - Stats : List_Id; - - begin - Stats := - New_List ( - Make_Object_Declaration (Loc, - Defining_Identifier => Tnn, - Object_Definition => - New_Occurrence_Of (Etype (Lhs), Loc)), - Make_Assignment_Statement (Loc, - Name => New_Occurrence_Of (Tnn, Loc), - Expression => Relocate_Node (Rhs)), - Make_Assignment_Statement (Loc, - Name => Relocate_Node (Lhs), - Expression => New_Occurrence_Of (Tnn, Loc))); - - Insert_Actions (N, Stats); - Rewrite (N, Make_Null_Statement (Loc)); - Analyze (N); - end; - end if; - - -- Build-in-place function call case. Note that we're not yet doing - -- build-in-place for user-written assignment statements (the assignment - -- here came from an aggregate.) - - elsif Ada_Version >= Ada_2005 - and then Is_Build_In_Place_Function_Call (Rhs) - then - Make_Build_In_Place_Call_In_Assignment (N, Rhs); - - elsif Is_Tagged_Type (Typ) and then Is_Value_Type (Etype (Lhs)) then - - -- Nothing to do for valuetypes - -- ??? Set_Scope_Is_Transient (False); - - return; - - elsif Is_Tagged_Type (Typ) - or else (Needs_Finalization (Typ) and then not Is_Array_Type (Typ)) - then - Tagged_Case : declare - L : List_Id := No_List; - Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N); - - begin - -- In the controlled case, we ensure that function calls are - -- evaluated before finalizing the target. In all cases, it makes - -- the expansion easier if the side-effects are removed first. - - Remove_Side_Effects (Lhs); - Remove_Side_Effects (Rhs); - - -- Avoid recursion in the mechanism - - Set_Analyzed (N); - - -- If dispatching assignment, we need to dispatch to _assign - - if Is_Class_Wide_Type (Typ) - - -- If the type is tagged, we may as well use the predefined - -- primitive assignment. This avoids inlining a lot of code - -- and in the class-wide case, the assignment is replaced - -- by a dispatching call to _assign. It is suppressed in the - -- case of assignments created by the expander that correspond - -- to initializations, where we do want to copy the tag - -- (Expand_Ctrl_Actions flag is set True in this case). It is - -- also suppressed if restriction No_Dispatching_Calls is in - -- force because in that case predefined primitives are not - -- generated. - - or else (Is_Tagged_Type (Typ) - and then not Is_Value_Type (Etype (Lhs)) - and then Chars (Current_Scope) /= Name_uAssign - and then Expand_Ctrl_Actions - and then - not Restriction_Active (No_Dispatching_Calls)) - then - if Is_Limited_Type (Typ) then - - -- This can happen in an instance when the formal is an - -- extension of a limited interface, and the actual is - -- limited. This is an error according to AI05-0087, but - -- is not caught at the point of instantiation in earlier - -- versions. - - -- This is wrong, error messages cannot be issued during - -- expansion, since they would be missed in -gnatc mode ??? - - Error_Msg_N ("assignment not available on limited type", N); - return; - end if; - - -- Fetch the primitive op _assign and proper type to call it. - -- Because of possible conflicts between private and full view, - -- fetch the proper type directly from the operation profile. - - declare - Op : constant Entity_Id := - Find_Prim_Op (Typ, Name_uAssign); - F_Typ : Entity_Id := Etype (First_Formal (Op)); - - begin - -- If the assignment is dispatching, make sure to use the - -- proper type. - - if Is_Class_Wide_Type (Typ) then - F_Typ := Class_Wide_Type (F_Typ); - end if; - - L := New_List; - - -- In case of assignment to a class-wide tagged type, before - -- the assignment we generate run-time check to ensure that - -- the tags of source and target match. - - if Is_Class_Wide_Type (Typ) - and then Is_Tagged_Type (Typ) - and then Is_Tagged_Type (Underlying_Type (Etype (Rhs))) - then - Append_To (L, - Make_Raise_Constraint_Error (Loc, - Condition => - Make_Op_Ne (Loc, - Left_Opnd => - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr (Lhs), - Selector_Name => - Make_Identifier (Loc, Name_uTag)), - Right_Opnd => - Make_Selected_Component (Loc, - Prefix => Duplicate_Subexpr (Rhs), - Selector_Name => - Make_Identifier (Loc, Name_uTag))), - Reason => CE_Tag_Check_Failed)); - end if; - - declare - Left_N : Node_Id := Duplicate_Subexpr (Lhs); - Right_N : Node_Id := Duplicate_Subexpr (Rhs); - - begin - -- In order to dispatch the call to _assign the type of - -- the actuals must match. Add conversion (if required). - - if Etype (Lhs) /= F_Typ then - Left_N := Unchecked_Convert_To (F_Typ, Left_N); - end if; - - if Etype (Rhs) /= F_Typ then - Right_N := Unchecked_Convert_To (F_Typ, Right_N); - end if; - - Append_To (L, - Make_Procedure_Call_Statement (Loc, - Name => New_Reference_To (Op, Loc), - Parameter_Associations => New_List ( - Node1 => Left_N, - Node2 => Right_N))); - end; - end; - - else - L := Make_Tag_Ctrl_Assignment (N); - - -- We can't afford to have destructive Finalization Actions in - -- the Self assignment case, so if the target and the source - -- are not obviously different, code is generated to avoid the - -- self assignment case: - - -- if lhs'address /= rhs'address then - -- <code for controlled and/or tagged assignment> - -- end if; - - -- Skip this if Restriction (No_Finalization) is active - - if not Statically_Different (Lhs, Rhs) - and then Expand_Ctrl_Actions - and then not Restriction_Active (No_Finalization) - then - L := New_List ( - Make_Implicit_If_Statement (N, - Condition => - Make_Op_Ne (Loc, - Left_Opnd => - Make_Attribute_Reference (Loc, - Prefix => Duplicate_Subexpr (Lhs), - Attribute_Name => Name_Address), - - Right_Opnd => - Make_Attribute_Reference (Loc, - Prefix => Duplicate_Subexpr (Rhs), - Attribute_Name => Name_Address)), - - Then_Statements => L)); - end if; - - -- We need to set up an exception handler for implementing - -- 7.6.1(18). The remaining adjustments are tackled by the - -- implementation of adjust for record_controllers (see - -- s-finimp.adb). - - -- This is skipped if we have no finalization - - if Expand_Ctrl_Actions - and then not Restriction_Active (No_Finalization) - then - L := New_List ( - Make_Block_Statement (Loc, - Handled_Statement_Sequence => - Make_Handled_Sequence_Of_Statements (Loc, - Statements => L, - Exception_Handlers => New_List ( - Make_Handler_For_Ctrl_Operation (Loc))))); - end if; - end if; - - Rewrite (N, - Make_Block_Statement (Loc, - Handled_Statement_Sequence => - Make_Handled_Sequence_Of_Statements (Loc, Statements => L))); - - -- If no restrictions on aborts, protect the whole assignment - -- for controlled objects as per 9.8(11). - - if Needs_Finalization (Typ) - and then Expand_Ctrl_Actions - and then Abort_Allowed - then - declare - Blk : constant Entity_Id := - New_Internal_Entity - (E_Block, Current_Scope, Sloc (N), 'B'); - - begin - Set_Scope (Blk, Current_Scope); - Set_Etype (Blk, Standard_Void_Type); - Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N))); - - Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer)); - Set_At_End_Proc (Handled_Statement_Sequence (N), - New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc)); - Expand_At_End_Handler - (Handled_Statement_Sequence (N), Blk); - end; - end if; - - -- N has been rewritten to a block statement for which it is - -- known by construction that no checks are necessary: analyze - -- it with all checks suppressed. - - Analyze (N, Suppress => All_Checks); - return; - end Tagged_Case; - - -- Array types - - elsif Is_Array_Type (Typ) then - declare - Actual_Rhs : Node_Id := Rhs; - - begin - while Nkind_In (Actual_Rhs, N_Type_Conversion, - N_Qualified_Expression) - loop - Actual_Rhs := Expression (Actual_Rhs); - end loop; - - Expand_Assign_Array (N, Actual_Rhs); - return; - end; - - -- Record types - - elsif Is_Record_Type (Typ) then - Expand_Assign_Record (N); - return; - - -- Scalar types. This is where we perform the processing related to the - -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid - -- scalar values. - - elsif Is_Scalar_Type (Typ) then - - -- Case where right side is known valid - - if Expr_Known_Valid (Rhs) then - - -- Here the right side is valid, so it is fine. The case to deal - -- with is when the left side is a local variable reference whose - -- value is not currently known to be valid. If this is the case, - -- and the assignment appears in an unconditional context, then - -- we can mark the left side as now being valid if one of these - -- conditions holds: - - -- The expression of the right side has Do_Range_Check set so - -- that we know a range check will be performed. Note that it - -- can be the case that a range check is omitted because we - -- make the assumption that we can assume validity for operands - -- appearing in the right side in determining whether a range - -- check is required - - -- The subtype of the right side matches the subtype of the - -- left side. In this case, even though we have not checked - -- the range of the right side, we know it is in range of its - -- subtype if the expression is valid. - - if Is_Local_Variable_Reference (Lhs) - and then not Is_Known_Valid (Entity (Lhs)) - and then In_Unconditional_Context (N) - then - if Do_Range_Check (Rhs) - or else Etype (Lhs) = Etype (Rhs) - then - Set_Is_Known_Valid (Entity (Lhs), True); - end if; - end if; - - -- Case where right side may be invalid in the sense of the RM - -- reference above. The RM does not require that we check for the - -- validity on an assignment, but it does require that the assignment - -- of an invalid value not cause erroneous behavior. - - -- The general approach in GNAT is to use the Is_Known_Valid flag - -- to avoid the need for validity checking on assignments. However - -- in some cases, we have to do validity checking in order to make - -- sure that the setting of this flag is correct. - - else - -- Validate right side if we are validating copies - - if Validity_Checks_On - and then Validity_Check_Copies - then - -- Skip this if left hand side is an array or record component - -- and elementary component validity checks are suppressed. - - if Nkind_In (Lhs, N_Selected_Component, N_Indexed_Component) - and then not Validity_Check_Components - then - null; - else - Ensure_Valid (Rhs); - end if; - - -- We can propagate this to the left side where appropriate - - if Is_Local_Variable_Reference (Lhs) - and then not Is_Known_Valid (Entity (Lhs)) - and then In_Unconditional_Context (N) - then - Set_Is_Known_Valid (Entity (Lhs), True); - end if; - - -- Otherwise check to see what should be done - - -- If left side is a local variable, then we just set its flag to - -- indicate that its value may no longer be valid, since we are - -- copying a potentially invalid value. - - elsif Is_Local_Variable_Reference (Lhs) then - Set_Is_Known_Valid (Entity (Lhs), False); - - -- Check for case of a nonlocal variable on the left side which - -- is currently known to be valid. In this case, we simply ensure - -- that the right side is valid. We only play the game of copying - -- validity status for local variables, since we are doing this - -- statically, not by tracing the full flow graph. - - elsif Is_Entity_Name (Lhs) - and then Is_Known_Valid (Entity (Lhs)) - then - -- Note: If Validity_Checking mode is set to none, we ignore - -- the Ensure_Valid call so don't worry about that case here. - - Ensure_Valid (Rhs); - - -- In all other cases, we can safely copy an invalid value without - -- worrying about the status of the left side. Since it is not a - -- variable reference it will not be considered - -- as being known to be valid in any case. - - else - null; - end if; - end if; - end if; - - exception - when RE_Not_Available => - return; - end Expand_N_Assignment_Statement; - - ------------------------------ - -- Expand_N_Block_Statement -- - ------------------------------ - - -- Encode entity names defined in block statement - - procedure Expand_N_Block_Statement (N : Node_Id) is - begin - Qualify_Entity_Names (N); - end Expand_N_Block_Statement; - - ----------------------------- - -- Expand_N_Case_Statement -- - ----------------------------- - - procedure Expand_N_Case_Statement (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Expr : constant Node_Id := Expression (N); - Alt : Node_Id; - Len : Nat; - Cond : Node_Id; - Choice : Node_Id; - Chlist : List_Id; - - begin - -- Check for the situation where we know at compile time which branch - -- will be taken - - if Compile_Time_Known_Value (Expr) then - Alt := Find_Static_Alternative (N); - - Process_Statements_For_Controlled_Objects (Alt); - - -- Move statements from this alternative after the case statement. - -- They are already analyzed, so will be skipped by the analyzer. - - Insert_List_After (N, Statements (Alt)); - - -- That leaves the case statement as a shell. So now we can kill all - -- other alternatives in the case statement. - - Kill_Dead_Code (Expression (N)); - - declare - Dead_Alt : Node_Id; - - begin - -- Loop through case alternatives, skipping pragmas, and skipping - -- the one alternative that we select (and therefore retain). - - Dead_Alt := First (Alternatives (N)); - while Present (Dead_Alt) loop - if Dead_Alt /= Alt - and then Nkind (Dead_Alt) = N_Case_Statement_Alternative - then - Kill_Dead_Code (Statements (Dead_Alt), Warn_On_Deleted_Code); - end if; - - Next (Dead_Alt); - end loop; - end; - - Rewrite (N, Make_Null_Statement (Loc)); - return; - end if; - - -- Here if the choice is not determined at compile time - - declare - Last_Alt : constant Node_Id := Last (Alternatives (N)); - - Others_Present : Boolean; - Others_Node : Node_Id; - - Then_Stms : List_Id; - Else_Stms : List_Id; - - begin - if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then - Others_Present := True; - Others_Node := Last_Alt; - else - Others_Present := False; - end if; - - -- First step is to worry about possible invalid argument. The RM - -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is - -- outside the base range), then Constraint_Error must be raised. - - -- Case of validity check required (validity checks are on, the - -- expression is not known to be valid, and the case statement - -- comes from source -- no need to validity check internally - -- generated case statements). - - if Validity_Check_Default then - Ensure_Valid (Expr); - end if; - - -- If there is only a single alternative, just replace it with the - -- sequence of statements since obviously that is what is going to - -- be executed in all cases. - - Len := List_Length (Alternatives (N)); - - if Len = 1 then - - -- We still need to evaluate the expression if it has any side - -- effects. - - Remove_Side_Effects (Expression (N)); - - Alt := First (Alternatives (N)); - - Process_Statements_For_Controlled_Objects (Alt); - 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)); - Rewrite (N, Make_Null_Statement (Loc)); - return; - - -- An optimization. If there are only two alternatives, and only - -- a single choice, then rewrite the whole case statement as an - -- if statement, since this can result in subsequent optimizations. - -- This helps not only with case statements in the source of a - -- simple form, but also with generated code (discriminant check - -- functions in particular) - - elsif 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; - - Alt := First (Alternatives (N)); - while Present (Alt) - and then Nkind (Alt) = N_Case_Statement_Alternative - loop - Process_Statements_For_Controlled_Objects (Alt); - Next (Alt); - end loop; - 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; - - Warn_If_Deleted : constant Boolean := - Warn_On_Deleted_Code and then Comes_From_Source (N); - -- Indicates whether we want warnings when we delete branches of the - -- if statement based on constant condition analysis. We never want - -- these warnings for expander generated code. - - begin - Process_Statements_For_Controlled_Objects (N); - - Adjust_Condition (Condition (N)); - - -- The following loop deals with constant conditions for the IF. We - -- need a loop because as we eliminate False conditions, we grab the - -- first elsif condition and use it as the primary condition. - - while Compile_Time_Known_Value (Condition (N)) loop - - -- If condition is True, we can simply rewrite the if statement now - -- by replacing it by the series of then statements. - - if Is_True (Expr_Value (Condition (N))) then - - -- All the else parts can be killed - - Kill_Dead_Code (Elsif_Parts (N), Warn_If_Deleted); - Kill_Dead_Code (Else_Statements (N), Warn_If_Deleted); - - Hed := Remove_Head (Then_Statements (N)); - Insert_List_After (N, Then_Statements (N)); - Rewrite (N, Hed); - return; - - -- If condition is False, then we can delete the condition and - -- the Then statements - - else - -- We do not delete the condition if constant condition warnings - -- are enabled, since otherwise we end up deleting the desired - -- warning. Of course the backend will get rid of this True/False - -- test anyway, so nothing is lost here. - - if not Constant_Condition_Warnings then - Kill_Dead_Code (Condition (N)); - end if; - - Kill_Dead_Code (Then_Statements (N), Warn_If_Deleted); - - -- If there are no elsif statements, then we simply replace the - -- entire if statement by the sequence of else statements. - - if No (Elsif_Parts (N)) then - if No (Else_Statements (N)) - or else Is_Empty_List (Else_Statements (N)) - then - Rewrite (N, - Make_Null_Statement (Sloc (N))); - else - Hed := Remove_Head (Else_Statements (N)); - Insert_List_After (N, Else_Statements (N)); - Rewrite (N, Hed); - end if; - - return; - - -- If there are elsif statements, the first of them becomes the - -- if/then section of the rebuilt if statement This is the case - -- where we loop to reprocess this copied condition. - - else - Hed := Remove_Head (Elsif_Parts (N)); - Insert_Actions (N, Condition_Actions (Hed)); - Set_Condition (N, Condition (Hed)); - Set_Then_Statements (N, Then_Statements (Hed)); - - -- Hed might have been captured as the condition determining - -- the current value for an entity. Now it is detached from - -- the tree, so a Current_Value pointer in the condition might - -- need to be updated. - - Set_Current_Value_Condition (N); - - if Is_Empty_List (Elsif_Parts (N)) then - Set_Elsif_Parts (N, No_List); - end if; - end if; - end if; - end loop; - - -- Loop through elsif parts, dealing with constant conditions and - -- possible expression actions that are present. - - if Present (Elsif_Parts (N)) then - E := First (Elsif_Parts (N)); - while Present (E) loop - Process_Statements_For_Controlled_Objects (E); - - Adjust_Condition (Condition (E)); - - -- If there are condition actions, then rewrite the if statement - -- as indicated above. We also do the same rewrite for a True or - -- False condition. The further processing of this constant - -- condition is then done by the recursive call to expand the - -- newly created if statement - - if Present (Condition_Actions (E)) - or else Compile_Time_Known_Value (Condition (E)) - then - -- Note this is not an implicit if statement, since it is part - -- of an explicit if statement in the source (or of an implicit - -- if statement that has already been tested). - - New_If := - Make_If_Statement (Sloc (E), - Condition => Condition (E), - Then_Statements => Then_Statements (E), - Elsif_Parts => No_List, - Else_Statements => Else_Statements (N)); - - -- Elsif parts for new if come from remaining elsif's of parent - - while Present (Next (E)) loop - if No (Elsif_Parts (New_If)) then - Set_Elsif_Parts (New_If, New_List); - end if; - - Append (Remove_Next (E), Elsif_Parts (New_If)); - end loop; - - Set_Else_Statements (N, New_List (New_If)); - - if Present (Condition_Actions (E)) then - Insert_List_Before (New_If, Condition_Actions (E)); - end if; - - Remove (E); - - if Is_Empty_List (Elsif_Parts (N)) then - Set_Elsif_Parts (N, No_List); - end if; - - Analyze (New_If); - return; - - -- No special processing for that elsif part, move to next - - else - Next (E); - end if; - end loop; - end if; - - -- Some more optimizations applicable if we still have an IF statement - - if Nkind (N) /= N_If_Statement then - return; - end if; - - -- Another optimization, special cases that can be simplified - - -- if expression then - -- return true; - -- else - -- return false; - -- end if; - - -- can be changed to: - - -- return expression; - - -- and - - -- if expression then - -- return false; - -- else - -- return true; - -- end if; - - -- can be changed to: - - -- return not (expression); - - -- Only do these optimizations if we are at least at -O1 level and - -- do not do them if control flow optimizations are suppressed. - - if Optimization_Level > 0 - and then not Opt.Suppress_Control_Flow_Optimizations - then - if Nkind (N) = N_If_Statement - and then No (Elsif_Parts (N)) - and then Present (Else_Statements (N)) - and then List_Length (Then_Statements (N)) = 1 - and then List_Length (Else_Statements (N)) = 1 - then - declare - Then_Stm : constant Node_Id := First (Then_Statements (N)); - Else_Stm : constant Node_Id := First (Else_Statements (N)); - - begin - if Nkind (Then_Stm) = N_Simple_Return_Statement - and then - Nkind (Else_Stm) = N_Simple_Return_Statement - then - declare - Then_Expr : constant Node_Id := Expression (Then_Stm); - Else_Expr : constant Node_Id := Expression (Else_Stm); - - begin - if Nkind (Then_Expr) = N_Identifier - and then - Nkind (Else_Expr) = N_Identifier - then - if Entity (Then_Expr) = Standard_True - and then Entity (Else_Expr) = Standard_False - then - Rewrite (N, - Make_Simple_Return_Statement (Loc, - Expression => Relocate_Node (Condition (N)))); - Analyze (N); - return; - - elsif Entity (Then_Expr) = Standard_False - and then Entity (Else_Expr) = Standard_True - then - Rewrite (N, - Make_Simple_Return_Statement (Loc, - Expression => - Make_Op_Not (Loc, - Right_Opnd => - Relocate_Node (Condition (N))))); - Analyze (N); - return; - end if; - end if; - end; - end if; - end; - end if; - end if; - end Expand_N_If_Statement; - - -------------------------- - -- Expand_Iterator_Loop -- - -------------------------- - - procedure Expand_Iterator_Loop (N : Node_Id) is - Isc : constant Node_Id := Iteration_Scheme (N); - I_Spec : constant Node_Id := Iterator_Specification (Isc); - Id : constant Entity_Id := Defining_Identifier (I_Spec); - Loc : constant Source_Ptr := Sloc (N); - - Container : constant Node_Id := Name (I_Spec); - Container_Typ : constant Entity_Id := Base_Type (Etype (Container)); - Cursor : Entity_Id; - Iterator : Entity_Id; - New_Loop : Node_Id; - Stats : List_Id := Statements (N); - - begin - -- Processing for arrays - - if Is_Array_Type (Container_Typ) then - - -- for Element of Array loop - -- - -- This case requires an internally generated cursor to iterate over - -- the array. - - if Of_Present (I_Spec) then - Iterator := Make_Temporary (Loc, 'C'); - - -- Generate: - -- Element : Component_Type renames Container (Iterator); - - Prepend_To (Stats, - Make_Object_Renaming_Declaration (Loc, - Defining_Identifier => Id, - Subtype_Mark => - New_Reference_To (Component_Type (Container_Typ), Loc), - Name => - Make_Indexed_Component (Loc, - Prefix => Relocate_Node (Container), - Expressions => New_List ( - New_Reference_To (Iterator, Loc))))); - - -- for Index in Array loop - - -- This case utilizes the already given iterator name - - else - Iterator := Id; - end if; - - -- Generate: - -- for Iterator in [reverse] Container'Range loop - -- Element : Component_Type renames Container (Iterator); - -- -- for the "of" form - - -- <original loop statements> - -- end loop; - - New_Loop := - Make_Loop_Statement (Loc, - Iteration_Scheme => - Make_Iteration_Scheme (Loc, - Loop_Parameter_Specification => - Make_Loop_Parameter_Specification (Loc, - Defining_Identifier => Iterator, - Discrete_Subtype_Definition => - Make_Attribute_Reference (Loc, - Prefix => Relocate_Node (Container), - Attribute_Name => Name_Range), - Reverse_Present => Reverse_Present (I_Spec))), - Statements => Stats, - End_Label => Empty); - - -- Processing for containers - - else - -- For an "of" iterator the name is a container expression, which - -- is transformed into a call to the default iterator. - - -- For an iterator of the form "in" the name is a function call - -- that delivers an iterator type. - - -- In both cases, analysis of the iterator has introduced an object - -- declaration to capture the domain, so that Container is an entity. - - -- The for loop is expanded into a while loop which uses a container - -- specific cursor to desgnate each element. - - -- Iter : Iterator_Type := Container.Iterate; - -- Cursor : Cursor_type := First (Iter); - -- while Has_Element (Iter) loop - -- declare - -- -- The block is added when Element_Type is controlled - - -- Obj : Pack.Element_Type := Element (Cursor); - -- -- for the "of" loop form - -- begin - -- <original loop statements> - -- end; - - -- Cursor := Iter.Next (Cursor); - -- end loop; - - -- If "reverse" is present, then the initialization of the cursor - -- uses Last and the step becomes Prev. Pack is the name of the - -- scope where the container package is instantiated. - - declare - Element_Type : constant Entity_Id := Etype (Id); - Iter_Type : Entity_Id; - Pack : Entity_Id; - Decl : Node_Id; - Name_Init : Name_Id; - Name_Step : Name_Id; - - begin - -- The type of the iterator is the return type of the Iterate - -- function used. For the "of" form this is the default iterator - -- for the type, otherwise it is the type of the explicit - -- function used in the iterator specification. The most common - -- case will be an Iterate function in the container package. - - -- The primitive operations of the container type may not be - -- use-visible, so we introduce the name of the enclosing package - -- in the declarations below. The Iterator type is declared in a - -- an instance within the container package itself. - - -- If the container type is a derived type, the cursor type is - -- found in the package of the parent type. - - if Is_Derived_Type (Container_Typ) then - Pack := Scope (Root_Type (Container_Typ)); - else - Pack := Scope (Container_Typ); - end if; - - Iter_Type := Etype (Name (I_Spec)); - - -- The "of" case uses an internally generated cursor whose type - -- is found in the container package. The domain of iteration - -- is expanded into a call to the default Iterator function, but - -- this expansion does not take place in quantified expressions - -- that are analyzed with expansion disabled, and in that case the - -- type of the iterator must be obtained from the aspect. - - if Of_Present (I_Spec) then - declare - Default_Iter : constant Entity_Id := - Entity - (Find_Aspect - (Etype (Container), - Aspect_Default_Iterator)); - - Container_Arg : Node_Id; - Ent : Entity_Id; - - begin - Cursor := Make_Temporary (Loc, 'I'); - - -- For an container element iterator, the iterator type - -- is obtained from the corresponding aspect. - - Iter_Type := Etype (Default_Iter); - Pack := Scope (Iter_Type); - - -- Rewrite domain of iteration as a call to the default - -- iterator for the container type. If the container is - -- a derived type and the aspect is inherited, convert - -- container to parent type. The Cursor type is also - -- inherited from the scope of the parent. - - if Base_Type (Etype (Container)) = - Base_Type (Etype (First_Formal (Default_Iter))) - then - Container_Arg := New_Copy_Tree (Container); - - else - Container_Arg := - Make_Type_Conversion (Loc, - Subtype_Mark => - New_Occurrence_Of - (Etype (First_Formal (Default_Iter)), Loc), - Expression => New_Copy_Tree (Container)); - end if; - - Rewrite (Name (I_Spec), - Make_Function_Call (Loc, - Name => New_Occurrence_Of (Default_Iter, Loc), - Parameter_Associations => - New_List (Container_Arg))); - Analyze_And_Resolve (Name (I_Spec)); - - -- Find cursor type in proper iterator package, which is an - -- instantiation of Iterator_Interfaces. - - Ent := First_Entity (Pack); - while Present (Ent) loop - if Chars (Ent) = Name_Cursor then - Set_Etype (Cursor, Etype (Ent)); - exit; - end if; - Next_Entity (Ent); - end loop; - - -- Generate: - -- Id : Element_Type renames Container (Cursor); - -- This assumes that the container type has an indexing - -- operation with Cursor. The check that this operation - -- exists is performed in Check_Container_Indexing. - - Decl := - Make_Object_Renaming_Declaration (Loc, - Defining_Identifier => Id, - Subtype_Mark => - New_Reference_To (Element_Type, Loc), - Name => - Make_Indexed_Component (Loc, - Prefix => Relocate_Node (Container_Arg), - Expressions => - New_List (New_Occurrence_Of (Cursor, Loc)))); - - -- If the container holds controlled objects, wrap the loop - -- statements and element renaming declaration with a block. - -- This ensures that the result of Element (Cusor) is - -- cleaned up after each iteration of the loop. - - if Needs_Finalization (Element_Type) then - - -- Generate: - -- declare - -- Id : Element_Type := Element (curosr); - -- begin - -- <original loop statements> - -- end; - - Stats := New_List ( - Make_Block_Statement (Loc, - Declarations => New_List (Decl), - Handled_Statement_Sequence => - Make_Handled_Sequence_Of_Statements (Loc, - Statements => Stats))); - - -- Elements do not need finalization - - else - Prepend_To (Stats, Decl); - end if; - end; - - -- X in Iterate (S) : type of iterator is type of explicitly - -- given Iterate function, and the loop variable is the cursor. - -- It will be assigned in the loop and must be a variable. - - else - Cursor := Id; - Set_Ekind (Cursor, E_Variable); - end if; - - Iterator := Make_Temporary (Loc, 'I'); - - -- Determine the advancement and initialization steps for the - -- cursor. - - -- Analysis of the expanded loop will verify that the container - -- has a reverse iterator. - - if Reverse_Present (I_Spec) then - Name_Init := Name_Last; - Name_Step := Name_Previous; - - else - Name_Init := Name_First; - Name_Step := Name_Next; - end if; - - -- For both iterator forms, add a call to the step operation to - -- advance the cursor. Generate: - - -- Cursor := Iterator.Next (Cursor); - - -- or else - - -- Cursor := Next (Cursor); - - declare - Rhs : Node_Id; - - begin - Rhs := - Make_Function_Call (Loc, - Name => - Make_Selected_Component (Loc, - Prefix => New_Reference_To (Iterator, Loc), - Selector_Name => Make_Identifier (Loc, Name_Step)), - Parameter_Associations => New_List ( - New_Reference_To (Cursor, Loc))); - - Append_To (Stats, - Make_Assignment_Statement (Loc, - Name => New_Occurrence_Of (Cursor, Loc), - Expression => Rhs)); - end; - - -- Generate: - -- while Iterator.Has_Element loop - -- <Stats> - -- end loop; - - -- Has_Element is the second actual in the iterator package - - New_Loop := - Make_Loop_Statement (Loc, - Iteration_Scheme => - Make_Iteration_Scheme (Loc, - Condition => - Make_Function_Call (Loc, - Name => - New_Occurrence_Of ( - Next_Entity (First_Entity (Pack)), Loc), - Parameter_Associations => - New_List ( - New_Reference_To (Cursor, Loc)))), - - Statements => Stats, - End_Label => Empty); - - -- Create the declarations for Iterator and cursor and insert them - -- before the source loop. Given that the domain of iteration is - -- already an entity, the iterator is just a renaming of that - -- entity. Possible optimization ??? - -- Generate: - - -- I : Iterator_Type renames Container; - -- C : Cursor_Type := Container.[First | Last]; - - Insert_Action (N, - Make_Object_Renaming_Declaration (Loc, - Defining_Identifier => Iterator, - Subtype_Mark => New_Occurrence_Of (Iter_Type, Loc), - Name => Relocate_Node (Name (I_Spec)))); - - -- Create declaration for cursor - - declare - Decl : Node_Id; - - begin - Decl := - Make_Object_Declaration (Loc, - Defining_Identifier => Cursor, - Object_Definition => - New_Occurrence_Of (Etype (Cursor), Loc), - Expression => - Make_Selected_Component (Loc, - Prefix => New_Reference_To (Iterator, Loc), - Selector_Name => - Make_Identifier (Loc, Name_Init))); - - -- The cursor is only modified in expanded code, so it appears - -- as unassigned to the warning machinery. We must suppress - -- this spurious warning explicitly. - - Set_Warnings_Off (Cursor); - Set_Assignment_OK (Decl); - - Insert_Action (N, Decl); - end; - - -- If the range of iteration is given by a function call that - -- returns a container, the finalization actions have been saved - -- in the Condition_Actions of the iterator. Insert them now at - -- the head of the loop. - - if Present (Condition_Actions (Isc)) then - Insert_List_Before (N, Condition_Actions (Isc)); - end if; - end; - end if; - - Rewrite (N, New_Loop); - Analyze (N); - end Expand_Iterator_Loop; - - ----------------------------- - -- Expand_N_Loop_Statement -- - ----------------------------- - - -- 1. Remove null loop entirely - -- 2. Deal with while condition for C/Fortran boolean - -- 3. Deal with loops with a non-standard enumeration type range - -- 4. Deal with while loops where Condition_Actions is set - -- 5. Deal with loops over predicated subtypes - -- 6. Deal with loops with iterators over arrays and containers - -- 7. Insert polling call if required - - procedure Expand_N_Loop_Statement (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Isc : constant Node_Id := Iteration_Scheme (N); - - begin - -- Delete null loop - - if Is_Null_Loop (N) then - Rewrite (N, Make_Null_Statement (Loc)); - return; - end if; - - Process_Statements_For_Controlled_Objects (N); - - -- Deal with condition for C/Fortran Boolean - - if Present (Isc) then - Adjust_Condition (Condition (Isc)); - end if; - - -- Generate polling call - - if Is_Non_Empty_List (Statements (N)) then - Generate_Poll_Call (First (Statements (N))); - end if; - - -- Nothing more to do for plain loop with no iteration scheme - - if No (Isc) then - null; - - -- Case of for loop (Loop_Parameter_Specification present) - - -- Note: we do not have to worry about validity checking of the for loop - -- range bounds here, since they were frozen with constant declarations - -- and it is during that process that the validity checking is done. - - elsif 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 - -- Deal with loop over predicates - - if Is_Discrete_Type (Ltype) - and then Present (Predicate_Function (Ltype)) - then - Expand_Predicated_Loop (N); - - -- 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; - - elsif Is_Enumeration_Type (Btype) - and then Present (Enum_Pos_To_Rep (Btype)) - then - 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))); - - -- The loop parameter's entity must be removed from the loop - -- scope's entity list, since it will now be located in the - -- new block scope. Any other entities already associated with - -- the loop scope, such as the loop parameter's subtype, will - -- remain there. - - pragma Assert (First_Entity (Scope (Loop_Id)) = Loop_Id); - Set_First_Entity (Scope (Loop_Id), Next_Entity (Loop_Id)); - - if Last_Entity (Scope (Loop_Id)) = Loop_Id then - Set_Last_Entity (Scope (Loop_Id), Empty); - end if; - - Analyze (N); - - -- Nothing to do with other cases of for loops - - else - null; - end if; - 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)) - and then Present (Condition (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; - - -- Here to deal with iterator case - - elsif Present (Isc) - and then Present (Iterator_Specification (Isc)) - then - Expand_Iterator_Loop (N); - end if; - end Expand_N_Loop_Statement; - - ---------------------------- - -- Expand_Predicated_Loop -- - ---------------------------- - - -- Note: the expander can handle generation of loops over predicated - -- subtypes for both the dynamic and static cases. Depending on what - -- we decide is allowed in Ada 2012 mode and/or extensions allowed - -- mode, the semantic analyzer may disallow one or both forms. - - procedure Expand_Predicated_Loop (N : Node_Id) is - Loc : constant Source_Ptr := Sloc (N); - Isc : constant Node_Id := Iteration_Scheme (N); - LPS : constant Node_Id := Loop_Parameter_Specification (Isc); - Loop_Id : constant Entity_Id := Defining_Identifier (LPS); - Ltype : constant Entity_Id := Etype (Loop_Id); - Stat : constant List_Id := Static_Predicate (Ltype); - Stmts : constant List_Id := Statements (N); - - begin - -- Case of iteration over non-static predicate, should not be possible - -- since this is not allowed by the semantics and should have been - -- caught during analysis of the loop statement. - - if No (Stat) then - raise Program_Error; - - -- If the predicate list is empty, that corresponds to a predicate of - -- False, in which case the loop won't run at all, and we rewrite the - -- entire loop as a null statement. - - elsif Is_Empty_List (Stat) then - Rewrite (N, Make_Null_Statement (Loc)); - Analyze (N); - - -- For expansion over a static predicate we generate the following - - -- declare - -- J : Ltype := min-val; - -- begin - -- loop - -- body - -- case J is - -- when endpoint => J := startpoint; - -- when endpoint => J := startpoint; - -- ... - -- when max-val => exit; - -- when others => J := Lval'Succ (J); - -- end case; - -- end loop; - -- end; - - -- To make this a little clearer, let's take a specific example: - - -- type Int is range 1 .. 10; - -- subtype L is Int with - -- predicate => L in 3 | 10 | 5 .. 7; - -- ... - -- for L in StaticP loop - -- Put_Line ("static:" & J'Img); - -- end loop; - - -- In this case, the loop is transformed into - - -- begin - -- J : L := 3; - -- loop - -- body - -- case J is - -- when 3 => J := 5; - -- when 7 => J := 10; - -- when 10 => exit; - -- when others => J := L'Succ (J); - -- end case; - -- end loop; - -- end; - - else - Static_Predicate : declare - S : Node_Id; - D : Node_Id; - P : Node_Id; - Alts : List_Id; - Cstm : Node_Id; - - function Lo_Val (N : Node_Id) return Node_Id; - -- Given static expression or static range, returns an identifier - -- whose value is the low bound of the expression value or range. - - function Hi_Val (N : Node_Id) return Node_Id; - -- Given static expression or static range, returns an identifier - -- whose value is the high bound of the expression value or range. - - ------------ - -- Hi_Val -- - ------------ - - function Hi_Val (N : Node_Id) return Node_Id is - begin - if Is_Static_Expression (N) then - return New_Copy (N); - else - pragma Assert (Nkind (N) = N_Range); - return New_Copy (High_Bound (N)); - end if; - end Hi_Val; - - ------------ - -- Lo_Val -- - ------------ - - function Lo_Val (N : Node_Id) return Node_Id is - begin - if Is_Static_Expression (N) then - return New_Copy (N); - else - pragma Assert (Nkind (N) = N_Range); - return New_Copy (Low_Bound (N)); - end if; - end Lo_Val; - - -- Start of processing for Static_Predicate - - begin - -- Convert loop identifier to normal variable and reanalyze it so - -- that this conversion works. We have to use the same defining - -- identifier, since there may be references in the loop body. - - Set_Analyzed (Loop_Id, False); - Set_Ekind (Loop_Id, E_Variable); - - -- Loop to create branches of case statement - - Alts := New_List; - P := First (Stat); - while Present (P) loop - if No (Next (P)) then - S := Make_Exit_Statement (Loc); - else - S := - Make_Assignment_Statement (Loc, - Name => New_Occurrence_Of (Loop_Id, Loc), - Expression => Lo_Val (Next (P))); - Set_Suppress_Assignment_Checks (S); - end if; - - Append_To (Alts, - Make_Case_Statement_Alternative (Loc, - Statements => New_List (S), - Discrete_Choices => New_List (Hi_Val (P)))); - - Next (P); - end loop; - - -- Add others choice - - S := - Make_Assignment_Statement (Loc, - Name => New_Occurrence_Of (Loop_Id, Loc), - Expression => - Make_Attribute_Reference (Loc, - Prefix => New_Occurrence_Of (Ltype, Loc), - Attribute_Name => Name_Succ, - Expressions => New_List ( - New_Occurrence_Of (Loop_Id, Loc)))); - Set_Suppress_Assignment_Checks (S); - - Append_To (Alts, - Make_Case_Statement_Alternative (Loc, - Discrete_Choices => New_List (Make_Others_Choice (Loc)), - Statements => New_List (S))); - - -- Construct case statement and append to body statements - - Cstm := - Make_Case_Statement (Loc, - Expression => New_Occurrence_Of (Loop_Id, Loc), - Alternatives => Alts); - Append_To (Stmts, Cstm); - - -- Rewrite the loop - - D := - Make_Object_Declaration (Loc, - Defining_Identifier => Loop_Id, - Object_Definition => New_Occurrence_Of (Ltype, Loc), - Expression => Lo_Val (First (Stat))); - Set_Suppress_Assignment_Checks (D); - - Rewrite (N, - Make_Block_Statement (Loc, - Declarations => New_List (D), - Handled_Statement_Sequence => - Make_Handled_Sequence_Of_Statements (Loc, - Statements => New_List ( - Make_Loop_Statement (Loc, - Statements => Stmts, - End_Label => Empty))))); - - Analyze (N); - end Static_Predicate; - end if; - end Expand_Predicated_Loop; - - ------------------------------ - -- Make_Tag_Ctrl_Assignment -- - ------------------------------ - - function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is - Asn : constant Node_Id := Relocate_Node (N); - L : constant Node_Id := Name (N); - Loc : constant Source_Ptr := Sloc (N); - Res : constant List_Id := New_List; - T : constant Entity_Id := Underlying_Type (Etype (L)); - - Comp_Asn : constant Boolean := Is_Fully_Repped_Tagged_Type (T); - Ctrl_Act : constant Boolean := Needs_Finalization (T) - and then not No_Ctrl_Actions (N); - Save_Tag : constant Boolean := Is_Tagged_Type (T) - and then not Comp_Asn - and then not No_Ctrl_Actions (N) - and then Tagged_Type_Expansion; - -- Tags are not saved and restored when VM_Target because VM tags are - -- represented implicitly in objects. - - Next_Id : Entity_Id; - Prev_Id : Entity_Id; - Tag_Id : Entity_Id; - - begin - -- Finalize the target of the assignment when controlled - - -- We have two exceptions here: - - -- 1. If we are in an init proc since it is an initialization more - -- than an assignment. - - -- 2. If the left-hand side is a temporary that was not initialized - -- (or the parent part of a temporary since it is the case in - -- extension aggregates). Such a temporary does not come from - -- source. We must examine the original node for the prefix, because - -- it may be a component of an entry formal, in which case it has - -- been rewritten and does not appear to come from source either. - - -- Case of init proc - - if not Ctrl_Act then - null; - - -- The left hand side is an uninitialized temporary object - - elsif Nkind (L) = N_Type_Conversion - and then Is_Entity_Name (Expression (L)) - and then Nkind (Parent (Entity (Expression (L)))) = - N_Object_Declaration - and then No_Initialization (Parent (Entity (Expression (L)))) - then - null; - - else - Append_To (Res, - Make_Final_Call - (Obj_Ref => Duplicate_Subexpr_No_Checks (L), - Typ => Etype (L))); - end if; - - -- Save the Tag in a local variable Tag_Id - - if Save_Tag then - Tag_Id := Make_Temporary (Loc, 'A'); - - Append_To (Res, - Make_Object_Declaration (Loc, - Defining_Identifier => Tag_Id, - 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_Id is not used - - else - Tag_Id := Empty; - end if; - - -- Save the Prev and Next fields on .NET/JVM. This is not needed on non - -- VM targets since the fields are not part of the object. - - if VM_Target /= No_VM - and then Is_Controlled (T) - then - Prev_Id := Make_Temporary (Loc, 'P'); - Next_Id := Make_Temporary (Loc, 'N'); - - -- Generate: - -- Pnn : Root_Controlled_Ptr := Root_Controlled (L).Prev; - - Append_To (Res, - Make_Object_Declaration (Loc, - Defining_Identifier => Prev_Id, - Object_Definition => - New_Reference_To (RTE (RE_Root_Controlled_Ptr), Loc), - Expression => - Make_Selected_Component (Loc, - Prefix => - Unchecked_Convert_To - (RTE (RE_Root_Controlled), New_Copy_Tree (L)), - Selector_Name => - Make_Identifier (Loc, Name_Prev)))); - - -- Generate: - -- Nnn : Root_Controlled_Ptr := Root_Controlled (L).Next; - - Append_To (Res, - Make_Object_Declaration (Loc, - Defining_Identifier => Next_Id, - Object_Definition => - New_Reference_To (RTE (RE_Root_Controlled_Ptr), Loc), - Expression => - Make_Selected_Component (Loc, - Prefix => - Unchecked_Convert_To - (RTE (RE_Root_Controlled), New_Copy_Tree (L)), - Selector_Name => - Make_Identifier (Loc, Name_Next)))); - end if; - - -- If the tagged type has a full rep clause, expand the assignment into - -- component-wise assignments. Mark the node as unanalyzed in order to - -- generate the proper code and propagate this scenario by setting a - -- flag to avoid infinite recursion. - - if Comp_Asn then - Set_Analyzed (Asn, False); - Set_Componentwise_Assignment (Asn, True); - end if; - - Append_To (Res, Asn); - - -- 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_Id, Loc))); - end if; - - -- Restore the Prev and Next fields on .NET/JVM - - if VM_Target /= No_VM - and then Is_Controlled (T) - then - -- Generate: - -- Root_Controlled (L).Prev := Prev_Id; - - Append_To (Res, - Make_Assignment_Statement (Loc, - Name => - Make_Selected_Component (Loc, - Prefix => - Unchecked_Convert_To - (RTE (RE_Root_Controlled), New_Copy_Tree (L)), - Selector_Name => - Make_Identifier (Loc, Name_Prev)), - Expression => New_Reference_To (Prev_Id, Loc))); - - -- Generate: - -- Root_Controlled (L).Next := Next_Id; - - Append_To (Res, - Make_Assignment_Statement (Loc, - Name => - Make_Selected_Component (Loc, - Prefix => - Unchecked_Convert_To - (RTE (RE_Root_Controlled), New_Copy_Tree (L)), - Selector_Name => Make_Identifier (Loc, Name_Next)), - Expression => New_Reference_To (Next_Id, 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_To (Res, - Make_Adjust_Call - (Obj_Ref => Duplicate_Subexpr_Move_Checks (L), - Typ => Etype (L))); - end if; - - return Res; - - exception - - -- Could use comment here ??? - - when RE_Not_Available => - return Empty_List; - end Make_Tag_Ctrl_Assignment; - -end Exp_Ch5; |