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------------------------------------------------------------------------------ -- -- -- 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;
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