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+------------------------------------------------------------------------------
+-- --
+-- GNAT COMPILER COMPONENTS --
+-- --
+-- E X P _ C H 5 --
+-- --
+-- B o d y --
+-- --
+-- Copyright (C) 1992-2007, Free Software Foundation, Inc. --
+-- --
+-- GNAT is free software; you can redistribute it and/or modify it under --
+-- terms of the GNU General Public License as published by the Free Soft- --
+-- ware Foundation; either version 3, or (at your option) any later ver- --
+-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
+-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
+-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
+-- for more details. You should have received a copy of the GNU General --
+-- Public License distributed with GNAT; see file COPYING3. If not, go to --
+-- http://www.gnu.org/licenses for a complete copy of the license. --
+-- --
+-- GNAT was originally developed by the GNAT team at New York University. --
+-- Extensive contributions were provided by Ada Core Technologies Inc. --
+-- --
+------------------------------------------------------------------------------
+
+with Atree; use Atree;
+with Checks; use Checks;
+with Debug; use Debug;
+with Einfo; use Einfo;
+with Elists; use Elists;
+with Exp_Atag; use Exp_Atag;
+with Exp_Aggr; use Exp_Aggr;
+with Exp_Ch6; use Exp_Ch6;
+with Exp_Ch7; use Exp_Ch7;
+with Exp_Ch11; use Exp_Ch11;
+with Exp_Dbug; use Exp_Dbug;
+with Exp_Pakd; use Exp_Pakd;
+with Exp_Tss; use Exp_Tss;
+with Exp_Util; use Exp_Util;
+with Namet; use Namet;
+with Nlists; use Nlists;
+with Nmake; use Nmake;
+with Opt; use Opt;
+with Restrict; use Restrict;
+with Rident; use Rident;
+with Rtsfind; use Rtsfind;
+with Sinfo; use Sinfo;
+with Sem; use Sem;
+with Sem_Ch3; use Sem_Ch3;
+with Sem_Ch8; use Sem_Ch8;
+with Sem_Ch13; use Sem_Ch13;
+with Sem_Eval; use Sem_Eval;
+with Sem_Res; use Sem_Res;
+with Sem_Util; use Sem_Util;
+with Snames; use Snames;
+with Stand; use Stand;
+with Stringt; use Stringt;
+with Targparm; use Targparm;
+with Tbuild; use Tbuild;
+with Ttypes; use Ttypes;
+with Uintp; use Uintp;
+with Validsw; use Validsw;
+
+package body Exp_Ch5 is
+
+ function Change_Of_Representation (N : Node_Id) return Boolean;
+ -- Determine if the right hand side of the assignment N is a type
+ -- conversion which requires a change of representation. Called
+ -- only for the array and record cases.
+
+ procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id);
+ -- N is an assignment which assigns an array value. This routine process
+ -- the various special cases and checks required for such assignments,
+ -- including change of representation. Rhs is normally simply the right
+ -- hand side of the assignment, except that if the right hand side is
+ -- a type conversion or a qualified expression, then the Rhs is the
+ -- actual expression inside any such type conversions or qualifications.
+
+ function Expand_Assign_Array_Loop
+ (N : Node_Id;
+ Larray : Entity_Id;
+ Rarray : Entity_Id;
+ L_Type : Entity_Id;
+ R_Type : Entity_Id;
+ Ndim : Pos;
+ Rev : Boolean) return Node_Id;
+ -- N is an assignment statement which assigns an array value. This routine
+ -- expands the assignment into a loop (or nested loops for the case of a
+ -- multi-dimensional array) to do the assignment component by component.
+ -- Larray and Rarray are the entities of the actual arrays on the left
+ -- hand and right hand sides. L_Type and R_Type are the types of these
+ -- arrays (which may not be the same, due to either sliding, or to a
+ -- change of representation case). Ndim is the number of dimensions and
+ -- the parameter Rev indicates if the loops run normally (Rev = False),
+ -- or reversed (Rev = True). The value returned is the constructed
+ -- loop statement. Auxiliary declarations are inserted before node N
+ -- using the standard Insert_Actions mechanism.
+
+ procedure Expand_Assign_Record (N : Node_Id);
+ -- N is an assignment of a non-tagged record value. This routine handles
+ -- the case where the assignment must be made component by component,
+ -- either because the target is not byte aligned, or there is a change
+ -- of representation.
+
+ procedure Expand_Non_Function_Return (N : Node_Id);
+ -- Called by Expand_N_Simple_Return_Statement in case we're returning from
+ -- a procedure body, entry body, accept statement, or extended return
+ -- statement. Note that all non-function returns are simple return
+ -- statements.
+
+ procedure Expand_Simple_Function_Return (N : Node_Id);
+ -- Expand simple return from function. Called by
+ -- Expand_N_Simple_Return_Statement in case we're returning from a function
+ -- body.
+
+ function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id;
+ -- Generate the necessary code for controlled and tagged assignment,
+ -- that is to say, finalization of the target before, adjustement of
+ -- the target after and save and restore of the tag and finalization
+ -- pointers which are not 'part of the value' and must not be changed
+ -- upon assignment. N is the original Assignment node.
+
+ ------------------------------
+ -- 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;
+
+ -- We certainly must use a loop for change of representation and also
+ -- we use the operand of the conversion on the right hand side as the
+ -- effective right hand side (the component types must match in this
+ -- situation).
+
+ if Crep then
+ Act_Rhs := Get_Referenced_Object (Rhs);
+ R_Type := Get_Actual_Subtype (Act_Rhs);
+ Loop_Required := True;
+
+ -- We require a loop if the left side is possibly bit unaligned
+
+ elsif Possible_Bit_Aligned_Component (Lhs)
+ or else
+ Possible_Bit_Aligned_Component (Rhs)
+ then
+ Loop_Required := True;
+
+ -- Arrays with controlled components are expanded into a loop to force
+ -- calls to Adjust at the component level.
+
+ elsif Has_Controlled_Component (L_Type) then
+ Loop_Required := True;
+
+ -- If object is atomic, we cannot tolerate a loop
+
+ elsif Is_Atomic_Object (Act_Lhs)
+ or else
+ Is_Atomic_Object (Act_Rhs)
+ then
+ return;
+
+ -- Loop is required if we have atomic components since we have to
+ -- be sure to do any accesses on an element by element basis.
+
+ elsif Has_Atomic_Components (L_Type)
+ or else Has_Atomic_Components (R_Type)
+ or else Is_Atomic (Component_Type (L_Type))
+ or else Is_Atomic (Component_Type (R_Type))
+ then
+ Loop_Required := True;
+
+ -- Case where no slice is involved
+
+ elsif not L_Slice and not R_Slice then
+
+ -- The following code deals with the case of unconstrained bit packed
+ -- arrays. The problem is that the template for such arrays contains
+ -- the bounds of the actual source level array, but the copy of an
+ -- entire array requires the bounds of the underlying array. It would
+ -- be nice if the back end could take care of this, but right now it
+ -- does not know how, so if we have such a type, then we expand out
+ -- into a loop, which is inefficient but works correctly. If we don't
+ -- do this, we get the wrong length computed for the array to be
+ -- moved. The two cases we need to worry about are:
+
+ -- Explicit deference of an unconstrained packed array type as in the
+ -- following example:
+
+ -- procedure C52 is
+ -- type BITS is array(INTEGER range <>) of BOOLEAN;
+ -- pragma PACK(BITS);
+ -- type A is access BITS;
+ -- P1,P2 : A;
+ -- begin
+ -- P1 := new BITS (1 .. 65_535);
+ -- P2 := new BITS (1 .. 65_535);
+ -- P2.ALL := P1.ALL;
+ -- end C52;
+
+ -- A formal parameter reference with an unconstrained bit array type
+ -- is the other case we need to worry about (here we assume the same
+ -- BITS type declared above):
+
+ -- procedure Write_All (File : out BITS; Contents : BITS);
+ -- begin
+ -- File.Storage := Contents;
+ -- end Write_All;
+
+ -- We expand to a loop in either of these two cases
+
+ -- Question for future thought. Another potentially more efficient
+ -- approach would be to create the actual subtype, and then do an
+ -- unchecked conversion to this actual subtype ???
+
+ Check_Unconstrained_Bit_Packed_Array : declare
+
+ function Is_UBPA_Reference (Opnd : Node_Id) return Boolean;
+ -- Function to perform required test for the first case, above
+ -- (dereference of an unconstrained bit packed array).
+
+ -----------------------
+ -- Is_UBPA_Reference --
+ -----------------------
+
+ function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is
+ Typ : constant Entity_Id := Underlying_Type (Etype (Opnd));
+ P_Type : Entity_Id;
+ Des_Type : Entity_Id;
+
+ begin
+ if Present (Packed_Array_Type (Typ))
+ and then Is_Array_Type (Packed_Array_Type (Typ))
+ and then not Is_Constrained (Packed_Array_Type (Typ))
+ then
+ return True;
+
+ elsif Nkind (Opnd) = N_Explicit_Dereference then
+ P_Type := Underlying_Type (Etype (Prefix (Opnd)));
+
+ if not Is_Access_Type (P_Type) then
+ return False;
+
+ else
+ Des_Type := Designated_Type (P_Type);
+ return
+ Is_Bit_Packed_Array (Des_Type)
+ and then not Is_Constrained (Des_Type);
+ end if;
+
+ else
+ return False;
+ end if;
+ end Is_UBPA_Reference;
+
+ -- Start of processing for Check_Unconstrained_Bit_Packed_Array
+
+ begin
+ if Is_UBPA_Reference (Lhs)
+ or else
+ Is_UBPA_Reference (Rhs)
+ then
+ Loop_Required := True;
+
+ -- Here if we do not have the case of a reference to a bit packed
+ -- unconstrained array case. In this case gigi can most certainly
+ -- handle the assignment if a forwards move is allowed.
+
+ -- (could it handle the backwards case also???)
+
+ elsif Forwards_OK (N) then
+ return;
+ end if;
+ end Check_Unconstrained_Bit_Packed_Array;
+
+ -- The back end can always handle the assignment if the right side is a
+ -- string literal (note that overlap is definitely impossible in this
+ -- case). If the type is packed, a string literal is always converted
+ -- into an aggregate, except in the case of a null slice, for which no
+ -- aggregate can be written. In that case, rewrite the assignment as a
+ -- null statement, a length check has already been emitted to verify
+ -- that the range of the left-hand side is empty.
+
+ -- Note that this code is not executed if we have an assignment of a
+ -- string literal to a non-bit aligned component of a record, a case
+ -- which cannot be handled by the backend.
+
+ elsif Nkind (Rhs) = N_String_Literal then
+ if String_Length (Strval (Rhs)) = 0
+ and then Is_Bit_Packed_Array (L_Type)
+ then
+ Rewrite (N, Make_Null_Statement (Loc));
+ Analyze (N);
+ end if;
+
+ return;
+
+ -- If either operand is bit packed, then we need a loop, since we can't
+ -- be sure that the slice is byte aligned. Similarly, if either operand
+ -- is a possibly unaligned slice, then we need a loop (since the back
+ -- end cannot handle unaligned slices).
+
+ elsif Is_Bit_Packed_Array (L_Type)
+ or else Is_Bit_Packed_Array (R_Type)
+ or else Is_Possibly_Unaligned_Slice (Lhs)
+ or else Is_Possibly_Unaligned_Slice (Rhs)
+ then
+ Loop_Required := True;
+
+ -- If we are not bit-packed, and we have only one slice, then no overlap
+ -- is possible except in the parameter case, so we can let the back end
+ -- handle things.
+
+ elsif not (L_Slice and R_Slice) then
+ if Forwards_OK (N) then
+ return;
+ end if;
+ end if;
+
+ -- If the right-hand side is a string literal, introduce a temporary for
+ -- it, for use in the generated loop that will follow.
+
+ if Nkind (Rhs) = N_String_Literal then
+ declare
+ Temp : constant Entity_Id :=
+ Make_Defining_Identifier (Loc, New_Internal_Name ('T'));
+ Decl : Node_Id;
+
+ begin
+ Decl :=
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Temp,
+ Object_Definition => New_Occurrence_Of (L_Type, Loc),
+ Expression => Relocate_Node (Rhs));
+
+ Insert_Action (N, Decl);
+ Rewrite (Rhs, New_Occurrence_Of (Temp, Loc));
+ R_Type := Etype (Temp);
+ end;
+ end if;
+
+ -- Come here to complete the analysis
+
+ -- Loop_Required: Set to True if we know that a loop is required
+ -- regardless of overlap considerations.
+
+ -- Forwards_OK: Set to False if we already know that a forwards
+ -- move is not safe, else set to True.
+
+ -- Backwards_OK: Set to False if we already know that a backwards
+ -- move is not safe, else set to True
+
+ -- Our task at this stage is to complete the overlap analysis, which can
+ -- result in possibly setting Forwards_OK or Backwards_OK to False, and
+ -- then generating the final code, either by deciding that it is OK
+ -- after all to let Gigi handle it, or by generating appropriate code
+ -- in the front end.
+
+ declare
+ L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type));
+ R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type));
+
+ Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ);
+ Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ);
+ Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ);
+ Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ);
+
+ Act_L_Array : Node_Id;
+ Act_R_Array : Node_Id;
+
+ Cleft_Lo : Node_Id;
+ Cright_Lo : Node_Id;
+ Condition : Node_Id;
+
+ Cresult : Compare_Result;
+
+ begin
+ -- Get the expressions for the arrays. If we are dealing with a
+ -- private type, then convert to the underlying type. We can do
+ -- direct assignments to an array that is a private type, but we
+ -- cannot assign to elements of the array without this extra
+ -- unchecked conversion.
+
+ if Nkind (Act_Lhs) = N_Slice then
+ Larray := Prefix (Act_Lhs);
+ else
+ Larray := Act_Lhs;
+
+ if Is_Private_Type (Etype (Larray)) then
+ Larray :=
+ Unchecked_Convert_To
+ (Underlying_Type (Etype (Larray)), Larray);
+ end if;
+ end if;
+
+ if Nkind (Act_Rhs) = N_Slice then
+ Rarray := Prefix (Act_Rhs);
+ else
+ Rarray := Act_Rhs;
+
+ if Is_Private_Type (Etype (Rarray)) then
+ Rarray :=
+ Unchecked_Convert_To
+ (Underlying_Type (Etype (Rarray)), Rarray);
+ end if;
+ end if;
+
+ -- If both sides are slices, we must figure out whether it is safe
+ -- to do the move in one direction or the other. It is always safe
+ -- if there is a change of representation since obviously two arrays
+ -- with different representations cannot possibly overlap.
+
+ if (not Crep) and L_Slice and R_Slice then
+ Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs));
+ Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs));
+
+ -- If both left and right hand arrays are entity names, and refer
+ -- to different entities, then we know that the move is safe (the
+ -- two storage areas are completely disjoint).
+
+ if Is_Entity_Name (Act_L_Array)
+ and then Is_Entity_Name (Act_R_Array)
+ and then Entity (Act_L_Array) /= Entity (Act_R_Array)
+ then
+ null;
+
+ -- Otherwise, we assume the worst, which is that the two arrays
+ -- are the same array. There is no need to check if we know that
+ -- is the case, because if we don't know it, we still have to
+ -- assume it!
+
+ -- Generally if the same array is involved, then we have an
+ -- overlapping case. We will have to really assume the worst (i.e.
+ -- set neither of the OK flags) unless we can determine the lower
+ -- or upper bounds at compile time and compare them.
+
+ else
+ Cresult := Compile_Time_Compare (Left_Lo, Right_Lo);
+
+ if Cresult = Unknown then
+ Cresult := Compile_Time_Compare (Left_Hi, Right_Hi);
+ end if;
+
+ case Cresult is
+ when LT | LE | EQ => Set_Backwards_OK (N, False);
+ when GT | GE => Set_Forwards_OK (N, False);
+ when NE | Unknown => Set_Backwards_OK (N, False);
+ Set_Forwards_OK (N, False);
+ end case;
+ end if;
+ end if;
+
+ -- If after that analysis, Forwards_OK is still True, and
+ -- Loop_Required is False, meaning that we have not discovered some
+ -- non-overlap reason for requiring a loop, then we can still let
+ -- gigi handle it.
+
+ if not Loop_Required then
+
+ -- Assume gigi can handle it if Forwards_OK is set
+
+ if 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 Controlled_Type (Component_Type (L_Type))
+ and then Base_Type (L_Type) = Base_Type (R_Type)
+ and then Ndim = 1
+ and then not No_Ctrl_Actions (N)
+ then
+ declare
+ Proc : constant Entity_Id :=
+ TSS (Base_Type (L_Type), TSS_Slice_Assign);
+ Actuals : List_Id;
+
+ begin
+ Apply_Dereference (Larray);
+ Apply_Dereference (Rarray);
+ Actuals := New_List (
+ Duplicate_Subexpr (Larray, Name_Req => True),
+ Duplicate_Subexpr (Rarray, Name_Req => True),
+ Duplicate_Subexpr (Left_Lo, Name_Req => True),
+ Duplicate_Subexpr (Left_Hi, Name_Req => True),
+ Duplicate_Subexpr (Right_Lo, Name_Req => True),
+ Duplicate_Subexpr (Right_Hi, Name_Req => True));
+
+ Append_To (Actuals,
+ New_Occurrence_Of (
+ Boolean_Literals (not Forwards_OK (N)), Loc));
+
+ Rewrite (N,
+ Make_Procedure_Call_Statement (Loc,
+ Name => New_Reference_To (Proc, Loc),
+ Parameter_Associations => Actuals));
+ end;
+
+ else
+ Rewrite (N,
+ Expand_Assign_Array_Loop
+ (N, Larray, Rarray, L_Type, R_Type, Ndim,
+ Rev => not Forwards_OK (N)));
+ end if;
+
+ -- Case of both are false with No_Implicit_Conditionals
+
+ elsif Restriction_Active (No_Implicit_Conditionals) then
+ declare
+ T : constant Entity_Id :=
+ Make_Defining_Identifier (Loc, Chars => Name_T);
+
+ begin
+ Rewrite (N,
+ Make_Block_Statement (Loc,
+ Declarations => New_List (
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => T,
+ Constant_Present => True,
+ Object_Definition =>
+ New_Occurrence_Of (Etype (Rhs), Loc),
+ Expression => Relocate_Node (Rhs))),
+
+ Handled_Statement_Sequence =>
+ Make_Handled_Sequence_Of_Statements (Loc,
+ Statements => New_List (
+ Make_Assignment_Statement (Loc,
+ Name => Relocate_Node (Lhs),
+ Expression => New_Occurrence_Of (T, Loc))))));
+ end;
+
+ -- Case of both are false with implicit conditionals allowed
+
+ else
+ -- Before we generate this code, we must ensure that the left and
+ -- right side array types are defined. They may be itypes, and we
+ -- cannot let them be defined inside the if, since the first use
+ -- in the then may not be executed.
+
+ Ensure_Defined (L_Type, N);
+ Ensure_Defined (R_Type, N);
+
+ -- We normally compare addresses to find out which way round to
+ -- do the loop, since this is realiable, and handles the cases of
+ -- parameters, conversions etc. But we can't do that in the bit
+ -- packed case or the 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 and reset the Analyzed flag, because the
+ -- bounds of the index type itself may be universal, and must
+ -- must be reaanalyzed to acquire the proper type for Gigi.
+
+ Cleft_Lo := New_Copy_Tree (Left_Lo);
+ Cright_Lo := New_Copy_Tree (Right_Lo);
+ Set_Analyzed (Cleft_Lo, False);
+ Set_Analyzed (Cright_Lo, False);
+
+ Condition :=
+ Make_Op_Le (Loc,
+ Left_Opnd => Cleft_Lo,
+ Right_Opnd => Cright_Lo);
+ end if;
+
+ if Controlled_Type (Component_Type (L_Type))
+ and then Base_Type (L_Type) = Base_Type (R_Type)
+ and then Ndim = 1
+ and then not No_Ctrl_Actions (N)
+ then
+
+ -- Call TSS procedure for array assignment, passing the the
+ -- explicit bounds of right and left hand sides.
+
+ declare
+ Proc : constant Node_Id :=
+ TSS (Base_Type (L_Type), TSS_Slice_Assign);
+ Actuals : List_Id;
+
+ begin
+ Apply_Dereference (Larray);
+ Apply_Dereference (Rarray);
+ Actuals := New_List (
+ Duplicate_Subexpr (Larray, Name_Req => True),
+ Duplicate_Subexpr (Rarray, Name_Req => True),
+ Duplicate_Subexpr (Left_Lo, Name_Req => True),
+ Duplicate_Subexpr (Left_Hi, Name_Req => True),
+ Duplicate_Subexpr (Right_Lo, Name_Req => True),
+ Duplicate_Subexpr (Right_Hi, Name_Req => True));
+
+ Append_To (Actuals,
+ Make_Op_Not (Loc,
+ Right_Opnd => Condition));
+
+ Rewrite (N,
+ Make_Procedure_Call_Statement (Loc,
+ Name => New_Reference_To (Proc, Loc),
+ Parameter_Associations => Actuals));
+ end;
+
+ else
+ Rewrite (N,
+ Make_Implicit_If_Statement (N,
+ Condition => Condition,
+
+ Then_Statements => New_List (
+ Expand_Assign_Array_Loop
+ (N, Larray, Rarray, L_Type, R_Type, Ndim,
+ Rev => False)),
+
+ Else_Statements => New_List (
+ Expand_Assign_Array_Loop
+ (N, Larray, Rarray, L_Type, R_Type, Ndim,
+ Rev => True))));
+ end if;
+ end if;
+
+ Analyze (N, Suppress => All_Checks);
+ end;
+
+ exception
+ when RE_Not_Available =>
+ return;
+ end Expand_Assign_Array;
+
+ ------------------------------
+ -- Expand_Assign_Array_Loop --
+ ------------------------------
+
+ -- The following is an example of the loop generated for the case of a
+ -- two-dimensional array:
+
+ -- declare
+ -- R2b : Tm1X1 := 1;
+ -- begin
+ -- for L1b in 1 .. 100 loop
+ -- declare
+ -- R4b : Tm1X2 := 1;
+ -- begin
+ -- for L3b in 1 .. 100 loop
+ -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
+ -- R4b := Tm1X2'succ(R4b);
+ -- end loop;
+ -- end;
+ -- R2b := Tm1X1'succ(R2b);
+ -- end loop;
+ -- end;
+
+ -- Here Rev is False, and Tm1Xn are the subscript types for the right hand
+ -- side. The declarations of R2b and R4b are inserted before the original
+ -- assignment statement.
+
+ function Expand_Assign_Array_Loop
+ (N : Node_Id;
+ Larray : Entity_Id;
+ Rarray : Entity_Id;
+ L_Type : Entity_Id;
+ R_Type : Entity_Id;
+ Ndim : Pos;
+ Rev : Boolean) return Node_Id
+ is
+ Loc : constant Source_Ptr := Sloc (N);
+
+ Lnn : array (1 .. Ndim) of Entity_Id;
+ Rnn : array (1 .. Ndim) of Entity_Id;
+ -- Entities used as subscripts on left and right sides
+
+ L_Index_Type : array (1 .. Ndim) of Entity_Id;
+ R_Index_Type : array (1 .. Ndim) of Entity_Id;
+ -- Left and right index types
+
+ Assign : Node_Id;
+
+ F_Or_L : Name_Id;
+ S_Or_P : Name_Id;
+
+ begin
+ if Rev then
+ F_Or_L := Name_Last;
+ S_Or_P := Name_Pred;
+ else
+ F_Or_L := Name_First;
+ S_Or_P := Name_Succ;
+ end if;
+
+ -- Setup index types and subscript entities
+
+ declare
+ L_Index : Node_Id;
+ R_Index : Node_Id;
+
+ begin
+ L_Index := First_Index (L_Type);
+ R_Index := First_Index (R_Type);
+
+ for J in 1 .. Ndim loop
+ Lnn (J) :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_Internal_Name ('L'));
+
+ Rnn (J) :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_Internal_Name ('R'));
+
+ L_Index_Type (J) := Etype (L_Index);
+ R_Index_Type (J) := Etype (R_Index);
+
+ Next_Index (L_Index);
+ Next_Index (R_Index);
+ end loop;
+ end;
+
+ -- Now construct the assignment statement
+
+ declare
+ ExprL : constant List_Id := New_List;
+ ExprR : constant List_Id := New_List;
+
+ begin
+ for J in 1 .. Ndim loop
+ Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc));
+ Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc));
+ end loop;
+
+ Assign :=
+ Make_Assignment_Statement (Loc,
+ Name =>
+ Make_Indexed_Component (Loc,
+ Prefix => Duplicate_Subexpr (Larray, Name_Req => True),
+ Expressions => ExprL),
+ Expression =>
+ Make_Indexed_Component (Loc,
+ Prefix => Duplicate_Subexpr (Rarray, Name_Req => True),
+ Expressions => ExprR));
+
+ -- We set assignment OK, since there are some cases, e.g. in object
+ -- declarations, where we are actually assigning into a constant.
+ -- If there really is an illegality, it was caught long before now,
+ -- and was flagged when the original assignment was analyzed.
+
+ Set_Assignment_OK (Name (Assign));
+
+ -- Propagate the No_Ctrl_Actions flag to individual assignments
+
+ Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N));
+ end;
+
+ -- Now construct the loop from the inside out, with the last subscript
+ -- varying most rapidly. Note that Assign is first the raw assignment
+ -- statement, and then subsequently the loop that wraps it up.
+
+ for J in reverse 1 .. Ndim loop
+ Assign :=
+ Make_Block_Statement (Loc,
+ Declarations => New_List (
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Rnn (J),
+ Object_Definition =>
+ New_Occurrence_Of (R_Index_Type (J), Loc),
+ Expression =>
+ Make_Attribute_Reference (Loc,
+ Prefix => New_Occurrence_Of (R_Index_Type (J), Loc),
+ Attribute_Name => F_Or_L))),
+
+ Handled_Statement_Sequence =>
+ Make_Handled_Sequence_Of_Statements (Loc,
+ Statements => New_List (
+ Make_Implicit_Loop_Statement (N,
+ Iteration_Scheme =>
+ Make_Iteration_Scheme (Loc,
+ Loop_Parameter_Specification =>
+ Make_Loop_Parameter_Specification (Loc,
+ Defining_Identifier => Lnn (J),
+ Reverse_Present => Rev,
+ Discrete_Subtype_Definition =>
+ New_Reference_To (L_Index_Type (J), Loc))),
+
+ Statements => New_List (
+ Assign,
+
+ Make_Assignment_Statement (Loc,
+ Name => New_Occurrence_Of (Rnn (J), Loc),
+ Expression =>
+ Make_Attribute_Reference (Loc,
+ Prefix =>
+ New_Occurrence_Of (R_Index_Type (J), Loc),
+ Attribute_Name => S_Or_P,
+ Expressions => New_List (
+ New_Occurrence_Of (Rnn (J), Loc)))))))));
+ end loop;
+
+ return Assign;
+ end Expand_Assign_Array_Loop;
+
+ --------------------------
+ -- Expand_Assign_Record --
+ --------------------------
+
+ -- The only processing required is in the change of representation case,
+ -- where we must expand the assignment to a series of field by field
+ -- assignments.
+
+ procedure Expand_Assign_Record (N : Node_Id) is
+ Lhs : constant Node_Id := Name (N);
+ Rhs : Node_Id := Expression (N);
+
+ begin
+ -- If change of representation, then extract the real right hand side
+ -- from the type conversion, and proceed with component-wise assignment,
+ -- since the two types are not the same as far as the back end is
+ -- concerned.
+
+ if Change_Of_Representation (N) then
+ Rhs := Expression (Rhs);
+
+ -- If this may be a case of a large bit aligned component, then proceed
+ -- with component-wise assignment, to avoid possible clobbering of other
+ -- components sharing bits in the first or last byte of the component to
+ -- be assigned.
+
+ elsif Possible_Bit_Aligned_Component (Lhs)
+ or
+ Possible_Bit_Aligned_Component (Rhs)
+ then
+ null;
+
+ -- If neither condition met, then nothing special to do, the back end
+ -- can handle assignment of the entire component as a single entity.
+
+ else
+ return;
+ end if;
+
+ -- At this stage we know that we must do a component wise assignment
+
+ declare
+ Loc : constant Source_Ptr := Sloc (N);
+ R_Typ : constant Entity_Id := Base_Type (Etype (Rhs));
+ L_Typ : constant Entity_Id := Base_Type (Etype (Lhs));
+ Decl : constant Node_Id := Declaration_Node (R_Typ);
+ RDef : Node_Id;
+ F : Entity_Id;
+
+ function Find_Component
+ (Typ : Entity_Id;
+ Comp : Entity_Id) return Entity_Id;
+ -- Find the component with the given name in the underlying record
+ -- declaration for Typ. We need to use the actual entity because the
+ -- type may be private and resolution by identifier alone would fail.
+
+ function Make_Component_List_Assign
+ (CL : Node_Id;
+ U_U : Boolean := False) return List_Id;
+ -- Returns a sequence of statements to assign the components that
+ -- are referenced in the given component list. The flag U_U is
+ -- used to force the usage of the inferred value of the variant
+ -- part expression as the switch for the generated case statement.
+
+ function Make_Field_Assign
+ (C : Entity_Id;
+ U_U : Boolean := False) return Node_Id;
+ -- Given C, the entity for a discriminant or component, build an
+ -- assignment for the corresponding field values. The flag U_U
+ -- signals the presence of an Unchecked_Union and forces the usage
+ -- of the inferred discriminant value of C as the right hand side
+ -- of the assignment.
+
+ function Make_Field_Assigns (CI : List_Id) return List_Id;
+ -- Given CI, a component items list, construct series of statements
+ -- for fieldwise assignment of the corresponding components.
+
+ --------------------
+ -- Find_Component --
+ --------------------
+
+ function Find_Component
+ (Typ : Entity_Id;
+ Comp : Entity_Id) return Entity_Id
+ is
+ Utyp : constant Entity_Id := Underlying_Type (Typ);
+ C : Entity_Id;
+
+ begin
+ C := First_Entity (Utyp);
+
+ while Present (C) loop
+ if Chars (C) = Chars (Comp) then
+ return C;
+ end if;
+ Next_Entity (C);
+ end loop;
+
+ raise Program_Error;
+ end Find_Component;
+
+ --------------------------------
+ -- Make_Component_List_Assign --
+ --------------------------------
+
+ function Make_Component_List_Assign
+ (CL : Node_Id;
+ U_U : Boolean := False) return List_Id
+ is
+ CI : constant List_Id := Component_Items (CL);
+ VP : constant Node_Id := Variant_Part (CL);
+
+ Alts : List_Id;
+ DC : Node_Id;
+ DCH : List_Id;
+ Expr : Node_Id;
+ Result : List_Id;
+ V : Node_Id;
+
+ begin
+ Result := Make_Field_Assigns (CI);
+
+ if Present (VP) then
+
+ V := First_Non_Pragma (Variants (VP));
+ Alts := New_List;
+ while Present (V) loop
+
+ DCH := New_List;
+ DC := First (Discrete_Choices (V));
+ while Present (DC) loop
+ Append_To (DCH, New_Copy_Tree (DC));
+ Next (DC);
+ end loop;
+
+ Append_To (Alts,
+ Make_Case_Statement_Alternative (Loc,
+ Discrete_Choices => DCH,
+ Statements =>
+ Make_Component_List_Assign (Component_List (V))));
+ Next_Non_Pragma (V);
+ end loop;
+
+ -- If we have an Unchecked_Union, use the value of the inferred
+ -- discriminant of the variant part expression as the switch
+ -- for the case statement. The case statement may later be
+ -- folded.
+
+ if U_U then
+ Expr :=
+ New_Copy (Get_Discriminant_Value (
+ Entity (Name (VP)),
+ Etype (Rhs),
+ Discriminant_Constraint (Etype (Rhs))));
+ else
+ Expr :=
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr (Rhs),
+ Selector_Name =>
+ Make_Identifier (Loc, Chars (Name (VP))));
+ end if;
+
+ Append_To (Result,
+ Make_Case_Statement (Loc,
+ Expression => Expr,
+ Alternatives => Alts));
+ end if;
+
+ return Result;
+ end Make_Component_List_Assign;
+
+ -----------------------
+ -- Make_Field_Assign --
+ -----------------------
+
+ function Make_Field_Assign
+ (C : Entity_Id;
+ U_U : Boolean := False) return Node_Id
+ is
+ A : Node_Id;
+ Expr : Node_Id;
+
+ begin
+ -- In the case of an Unchecked_Union, use the discriminant
+ -- constraint value as on the right hand side of the assignment.
+
+ if U_U then
+ Expr :=
+ New_Copy (Get_Discriminant_Value (C,
+ Etype (Rhs),
+ Discriminant_Constraint (Etype (Rhs))));
+ else
+ Expr :=
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr (Rhs),
+ Selector_Name => New_Occurrence_Of (C, Loc));
+ end if;
+
+ A :=
+ Make_Assignment_Statement (Loc,
+ Name =>
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr (Lhs),
+ Selector_Name =>
+ New_Occurrence_Of (Find_Component (L_Typ, C), Loc)),
+ Expression => Expr);
+
+ -- Set Assignment_OK, so discriminants can be assigned
+
+ Set_Assignment_OK (Name (A), True);
+ return A;
+ end Make_Field_Assign;
+
+ ------------------------
+ -- Make_Field_Assigns --
+ ------------------------
+
+ function Make_Field_Assigns (CI : List_Id) return List_Id is
+ Item : Node_Id;
+ Result : List_Id;
+
+ begin
+ Item := First (CI);
+ Result := New_List;
+ while Present (Item) loop
+ if Nkind (Item) = N_Component_Declaration then
+ Append_To
+ (Result, Make_Field_Assign (Defining_Identifier (Item)));
+ end if;
+
+ Next (Item);
+ end loop;
+
+ return Result;
+ end Make_Field_Assigns;
+
+ -- Start of processing for Expand_Assign_Record
+
+ begin
+ -- Note that we use the base types for this processing. This results
+ -- in some extra work in the constrained case, but the change of
+ -- representation case is so unusual that it is not worth the effort.
+
+ -- First copy the discriminants. This is done unconditionally. It
+ -- is required in the unconstrained left side case, and also in the
+ -- case where this assignment was constructed during the expansion
+ -- of a type conversion (since initialization of discriminants is
+ -- suppressed in this case). It is unnecessary but harmless in
+ -- other cases.
+
+ if Has_Discriminants (L_Typ) then
+ F := First_Discriminant (R_Typ);
+ while Present (F) loop
+
+ if Is_Unchecked_Union (Base_Type (R_Typ)) then
+ Insert_Action (N, Make_Field_Assign (F, True));
+ else
+ Insert_Action (N, Make_Field_Assign (F));
+ end if;
+
+ Next_Discriminant (F);
+ end loop;
+ end if;
+
+ -- We know the underlying type is a record, but its current view
+ -- may be private. We must retrieve the usable record declaration.
+
+ if Nkind (Decl) = N_Private_Type_Declaration
+ and then Present (Full_View (R_Typ))
+ then
+ RDef := Type_Definition (Declaration_Node (Full_View (R_Typ)));
+ else
+ RDef := Type_Definition (Decl);
+ end if;
+
+ if Nkind (RDef) = N_Record_Definition
+ and then Present (Component_List (RDef))
+ then
+
+ if Is_Unchecked_Union (R_Typ) then
+ Insert_Actions (N,
+ Make_Component_List_Assign (Component_List (RDef), True));
+ else
+ Insert_Actions
+ (N, Make_Component_List_Assign (Component_List (RDef)));
+ end if;
+
+ Rewrite (N, Make_Null_Statement (Loc));
+ end if;
+
+ end;
+ end Expand_Assign_Record;
+
+ -----------------------------------
+ -- Expand_N_Assignment_Statement --
+ -----------------------------------
+
+ -- This procedure implements various cases where an assignment statement
+ -- cannot just be passed on to the back end in untransformed state.
+
+ procedure Expand_N_Assignment_Statement (N : Node_Id) is
+ Loc : constant Source_Ptr := Sloc (N);
+ Lhs : constant Node_Id := Name (N);
+ Rhs : constant Node_Id := Expression (N);
+ Typ : constant Entity_Id := Underlying_Type (Etype (Lhs));
+ Exp : Node_Id;
+
+ begin
+ -- Ada 2005 (AI-327): Handle assignment to priority of protected object
+
+ -- Rewrite an assignment to X'Priority into a run-time call
+
+ -- For example: X'Priority := New_Prio_Expr;
+ -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr);
+
+ -- Note that although X'Priority is notionally an object, it is quite
+ -- deliberately not defined as an aliased object in the RM. This means
+ -- that it works fine to rewrite it as a call, without having to worry
+ -- about complications that would other arise from X'Priority'Access,
+ -- which is illegal, because of the lack of aliasing.
+
+ if Ada_Version >= Ada_05 then
+ declare
+ Call : Node_Id;
+ Conctyp : Entity_Id;
+ Ent : Entity_Id;
+ Subprg : Entity_Id;
+ RT_Subprg_Name : Node_Id;
+
+ begin
+ -- Handle chains of renamings
+
+ Ent := Name (N);
+ while Nkind (Ent) in N_Has_Entity
+ and then Present (Entity (Ent))
+ and then Present (Renamed_Object (Entity (Ent)))
+ loop
+ Ent := Renamed_Object (Entity (Ent));
+ end loop;
+
+ -- The attribute Priority applied to protected objects has been
+ -- previously expanded into a call to the Get_Ceiling run-time
+ -- subprogram.
+
+ if Nkind (Ent) = N_Function_Call
+ and then (Entity (Name (Ent)) = RTE (RE_Get_Ceiling)
+ or else
+ Entity (Name (Ent)) = RTE (RO_PE_Get_Ceiling))
+ then
+ -- Look for the enclosing concurrent type
+
+ Conctyp := Current_Scope;
+ while not Is_Concurrent_Type (Conctyp) loop
+ Conctyp := Scope (Conctyp);
+ end loop;
+
+ pragma Assert (Is_Protected_Type (Conctyp));
+
+ -- Generate the first actual of the call
+
+ Subprg := Current_Scope;
+ while not Present (Protected_Body_Subprogram (Subprg)) loop
+ Subprg := Scope (Subprg);
+ end loop;
+
+ -- Select the appropriate run-time call
+
+ if Number_Entries (Conctyp) = 0 then
+ RT_Subprg_Name :=
+ New_Reference_To (RTE (RE_Set_Ceiling), Loc);
+ else
+ RT_Subprg_Name :=
+ New_Reference_To (RTE (RO_PE_Set_Ceiling), Loc);
+ end if;
+
+ Call :=
+ Make_Procedure_Call_Statement (Loc,
+ Name => RT_Subprg_Name,
+ Parameter_Associations => New_List (
+ New_Copy_Tree (First (Parameter_Associations (Ent))),
+ Relocate_Node (Expression (N))));
+
+ Rewrite (N, Call);
+ Analyze (N);
+ return;
+ end if;
+ end;
+ end if;
+
+ -- First deal with generation of range check if required. For now we do
+ -- this only for discrete types.
+
+ if Do_Range_Check (Rhs)
+ and then Is_Discrete_Type (Typ)
+ then
+ Set_Do_Range_Check (Rhs, False);
+ Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed);
+ end if;
+
+ -- Check for a special case where a high level transformation is
+ -- required. If we have either of:
+
+ -- P.field := rhs;
+ -- P (sub) := rhs;
+
+ -- where P is a reference to a bit packed array, then we have to unwind
+ -- the assignment. The exact meaning of being a reference to a bit
+ -- packed array is as follows:
+
+ -- An indexed component whose prefix is a bit packed array is a
+ -- reference to a bit packed array.
+
+ -- An indexed component or selected component whose prefix is a
+ -- reference to a bit packed array is itself a reference ot a
+ -- bit packed array.
+
+ -- The required transformation is
+
+ -- Tnn : prefix_type := P;
+ -- Tnn.field := rhs;
+ -- P := Tnn;
+
+ -- or
+
+ -- Tnn : prefix_type := P;
+ -- Tnn (subscr) := rhs;
+ -- P := Tnn;
+
+ -- Since P is going to be evaluated more than once, any subscripts
+ -- in P must have their evaluation forced.
+
+ if Nkind_In (Lhs, N_Indexed_Component, N_Selected_Component)
+ and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs))
+ then
+ declare
+ BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs));
+ BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr);
+ Tnn : constant Entity_Id :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_Internal_Name ('T'));
+
+ begin
+ -- Insert the post assignment first, because we want to copy the
+ -- BPAR_Expr tree before it gets analyzed in the context of the
+ -- pre assignment. Note that we do not analyze the post assignment
+ -- yet (we cannot till we have completed the analysis of the pre
+ -- assignment). As usual, the analysis of this post assignment
+ -- will happen on its own when we "run into" it after finishing
+ -- the current assignment.
+
+ Insert_After (N,
+ Make_Assignment_Statement (Loc,
+ Name => New_Copy_Tree (BPAR_Expr),
+ Expression => New_Occurrence_Of (Tnn, Loc)));
+
+ -- At this stage BPAR_Expr is a reference to a bit packed array
+ -- where the reference was not expanded in the original tree,
+ -- since it was on the left side of an assignment. But in the
+ -- pre-assignment statement (the object definition), BPAR_Expr
+ -- will end up on the right hand side, and must be reexpanded. To
+ -- achieve this, we reset the analyzed flag of all selected and
+ -- indexed components down to the actual indexed component for
+ -- the packed array.
+
+ Exp := BPAR_Expr;
+ loop
+ Set_Analyzed (Exp, False);
+
+ if Nkind_In
+ (Exp, N_Selected_Component, N_Indexed_Component)
+ then
+ Exp := Prefix (Exp);
+ else
+ exit;
+ end if;
+ end loop;
+
+ -- Now we can insert and analyze the pre-assignment
+
+ -- If the right-hand side requires a transient scope, it has
+ -- already been placed on the stack. However, the declaration is
+ -- inserted in the tree outside of this scope, and must reflect
+ -- the proper scope for its variable. This awkward bit is forced
+ -- by the stricter scope discipline imposed by GCC 2.97.
+
+ declare
+ Uses_Transient_Scope : constant Boolean :=
+ Scope_Is_Transient
+ and then N = Node_To_Be_Wrapped;
+
+ begin
+ if Uses_Transient_Scope then
+ Push_Scope (Scope (Current_Scope));
+ end if;
+
+ Insert_Before_And_Analyze (N,
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Tnn,
+ Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc),
+ Expression => BPAR_Expr));
+
+ if Uses_Transient_Scope then
+ Pop_Scope;
+ end if;
+ end;
+
+ -- Now fix up the original assignment and continue processing
+
+ Rewrite (Prefix (Lhs),
+ New_Occurrence_Of (Tnn, Loc));
+
+ -- We do not need to reanalyze that assignment, and we do not need
+ -- to worry about references to the temporary, but we do need to
+ -- make sure that the temporary is not marked as a true constant
+ -- since we now have a generated assignment to it!
+
+ Set_Is_True_Constant (Tnn, False);
+ end;
+ end if;
+
+ -- When we have the appropriate type of aggregate in the expression (it
+ -- has been determined during analysis of the aggregate by setting the
+ -- delay flag), let's perform in place assignment and thus avoid
+ -- creating a temporary.
+
+ if Is_Delayed_Aggregate (Rhs) then
+ Convert_Aggr_In_Assignment (N);
+ Rewrite (N, Make_Null_Statement (Loc));
+ Analyze (N);
+ return;
+ end if;
+
+ -- Apply discriminant check if required. If Lhs is an access type to a
+ -- designated type with discriminants, we must always check.
+
+ if Has_Discriminants (Etype (Lhs)) then
+
+ -- Skip discriminant check if change of representation. Will be
+ -- done when the change of representation is expanded out.
+
+ if not Change_Of_Representation (N) then
+ Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs);
+ end if;
+
+ -- If the type is private without discriminants, and the full type
+ -- has discriminants (necessarily with defaults) a check may still be
+ -- necessary if the Lhs is aliased. The private determinants must be
+ -- visible to build the discriminant constraints.
+
+ -- Only an explicit dereference that comes from source indicates
+ -- aliasing. Access to formals of protected operations and entries
+ -- create dereferences but are not semantic aliasings.
+
+ elsif Is_Private_Type (Etype (Lhs))
+ and then Has_Discriminants (Typ)
+ and then Nkind (Lhs) = N_Explicit_Dereference
+ and then Comes_From_Source (Lhs)
+ then
+ declare
+ Lt : constant Entity_Id := Etype (Lhs);
+ begin
+ Set_Etype (Lhs, Typ);
+ Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
+ Apply_Discriminant_Check (Rhs, Typ, Lhs);
+ Set_Etype (Lhs, Lt);
+ end;
+
+ -- If the Lhs has a private type with unknown discriminants, it
+ -- may have a full view with discriminants, but those are nameable
+ -- only in the underlying type, so convert the Rhs to it before
+ -- potential checking.
+
+ elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs)))
+ and then Has_Discriminants (Typ)
+ then
+ Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
+ Apply_Discriminant_Check (Rhs, Typ, Lhs);
+
+ -- In the access type case, we need the same discriminant check, and
+ -- also range checks if we have an access to constrained array.
+
+ elsif Is_Access_Type (Etype (Lhs))
+ and then Is_Constrained (Designated_Type (Etype (Lhs)))
+ then
+ if Has_Discriminants (Designated_Type (Etype (Lhs))) then
+
+ -- Skip discriminant check if change of representation. Will be
+ -- done when the change of representation is expanded out.
+
+ if not Change_Of_Representation (N) then
+ Apply_Discriminant_Check (Rhs, Etype (Lhs));
+ end if;
+
+ elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then
+ Apply_Range_Check (Rhs, Etype (Lhs));
+
+ if Is_Constrained (Etype (Lhs)) then
+ Apply_Length_Check (Rhs, Etype (Lhs));
+ end if;
+
+ if Nkind (Rhs) = N_Allocator then
+ declare
+ Target_Typ : constant Entity_Id := Etype (Expression (Rhs));
+ C_Es : Check_Result;
+
+ begin
+ C_Es :=
+ Get_Range_Checks
+ (Lhs,
+ Target_Typ,
+ Etype (Designated_Type (Etype (Lhs))));
+
+ Insert_Range_Checks
+ (C_Es,
+ N,
+ Target_Typ,
+ Sloc (Lhs),
+ Lhs);
+ end;
+ end if;
+ end if;
+
+ -- Apply range check for access type case
+
+ elsif Is_Access_Type (Etype (Lhs))
+ and then Nkind (Rhs) = N_Allocator
+ and then Nkind (Expression (Rhs)) = N_Qualified_Expression
+ then
+ Analyze_And_Resolve (Expression (Rhs));
+ Apply_Range_Check
+ (Expression (Rhs), Designated_Type (Etype (Lhs)));
+ end if;
+
+ -- Ada 2005 (AI-231): Generate the run-time check
+
+ if Is_Access_Type (Typ)
+ and then Can_Never_Be_Null (Etype (Lhs))
+ and then not Can_Never_Be_Null (Etype (Rhs))
+ then
+ Apply_Constraint_Check (Rhs, Etype (Lhs));
+ end if;
+
+ -- Case of assignment to a bit packed array element
+
+ if Nkind (Lhs) = N_Indexed_Component
+ and then Is_Bit_Packed_Array (Etype (Prefix (Lhs)))
+ then
+ Expand_Bit_Packed_Element_Set (N);
+ return;
+
+ -- Build-in-place function call case. Note that we're not yet doing
+ -- build-in-place for user-written assignment statements (the assignment
+ -- here came from an aggregate.)
+
+ elsif Ada_Version >= Ada_05
+ and then Is_Build_In_Place_Function_Call (Rhs)
+ then
+ Make_Build_In_Place_Call_In_Assignment (N, Rhs);
+
+ elsif Is_Tagged_Type (Typ) and then Is_Value_Type (Etype (Lhs)) then
+
+ -- Nothing to do for valuetypes
+ -- ??? Set_Scope_Is_Transient (False);
+
+ return;
+
+ elsif Is_Tagged_Type (Typ)
+ or else (Controlled_Type (Typ) and then not Is_Array_Type (Typ))
+ then
+ Tagged_Case : declare
+ L : List_Id := No_List;
+ Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N);
+
+ begin
+ -- In the controlled case, we need to make sure that function
+ -- calls are evaluated before finalizing the target. In all cases,
+ -- it makes the expansion easier if the side-effects are removed
+ -- first.
+
+ Remove_Side_Effects (Lhs);
+ Remove_Side_Effects (Rhs);
+
+ -- Avoid recursion in the mechanism
+
+ Set_Analyzed (N);
+
+ -- If dispatching assignment, we need to dispatch to _assign
+
+ if Is_Class_Wide_Type (Typ)
+
+ -- If the type is tagged, we may as well use the predefined
+ -- primitive assignment. This avoids inlining a lot of code
+ -- and in the class-wide case, the assignment is replaced by
+ -- dispatch call to _assign. Note that this cannot be done when
+ -- discriminant checks are locally suppressed (as in extension
+ -- aggregate expansions) because otherwise the discriminant
+ -- check will be performed within the _assign call. It is also
+ -- suppressed for assignmments created by the expander that
+ -- correspond to initializations, where we do want to copy the
+ -- tag (No_Ctrl_Actions flag set True). by the expander and we
+ -- do not need to mess with tags ever (Expand_Ctrl_Actions flag
+ -- is set True in this case).
+
+ or else (Is_Tagged_Type (Typ)
+ and then not Is_Value_Type (Etype (Lhs))
+ and then Chars (Current_Scope) /= Name_uAssign
+ and then Expand_Ctrl_Actions
+ and then not Discriminant_Checks_Suppressed (Empty))
+ then
+ -- Fetch the primitive op _assign and proper type to call it.
+ -- Because of possible conflits between private and full view
+ -- the proper type is fetched directly from the operation
+ -- profile.
+
+ declare
+ Op : constant Entity_Id :=
+ Find_Prim_Op (Typ, Name_uAssign);
+ F_Typ : Entity_Id := Etype (First_Formal (Op));
+
+ begin
+ -- If the assignment is dispatching, make sure to use the
+ -- proper type.
+
+ if Is_Class_Wide_Type (Typ) then
+ F_Typ := Class_Wide_Type (F_Typ);
+ end if;
+
+ L := New_List;
+
+ -- In case of assignment to a class-wide tagged type, before
+ -- the assignment we generate run-time check to ensure that
+ -- the tags of source and target match.
+
+ if Is_Class_Wide_Type (Typ)
+ and then Is_Tagged_Type (Typ)
+ and then Is_Tagged_Type (Underlying_Type (Etype (Rhs)))
+ then
+ Append_To (L,
+ Make_Raise_Constraint_Error (Loc,
+ Condition =>
+ Make_Op_Ne (Loc,
+ Left_Opnd =>
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr (Lhs),
+ Selector_Name =>
+ Make_Identifier (Loc,
+ Chars => Name_uTag)),
+ Right_Opnd =>
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr (Rhs),
+ Selector_Name =>
+ Make_Identifier (Loc,
+ Chars => Name_uTag))),
+ Reason => CE_Tag_Check_Failed));
+ end if;
+
+ Append_To (L,
+ Make_Procedure_Call_Statement (Loc,
+ Name => New_Reference_To (Op, Loc),
+ Parameter_Associations => New_List (
+ Unchecked_Convert_To (F_Typ,
+ Duplicate_Subexpr (Lhs)),
+ Unchecked_Convert_To (F_Typ,
+ Duplicate_Subexpr (Rhs)))));
+ end;
+
+ else
+ L := Make_Tag_Ctrl_Assignment (N);
+
+ -- We can't afford to have destructive Finalization Actions in
+ -- the Self assignment case, so if the target and the source
+ -- are not obviously different, code is generated to avoid the
+ -- self assignment case:
+
+ -- if lhs'address /= rhs'address then
+ -- <code for controlled and/or tagged assignment>
+ -- end if;
+
+ if not Statically_Different (Lhs, Rhs)
+ and then Expand_Ctrl_Actions
+ then
+ L := New_List (
+ Make_Implicit_If_Statement (N,
+ Condition =>
+ Make_Op_Ne (Loc,
+ Left_Opnd =>
+ Make_Attribute_Reference (Loc,
+ Prefix => Duplicate_Subexpr (Lhs),
+ Attribute_Name => Name_Address),
+
+ Right_Opnd =>
+ Make_Attribute_Reference (Loc,
+ Prefix => Duplicate_Subexpr (Rhs),
+ Attribute_Name => Name_Address)),
+
+ Then_Statements => L));
+ end if;
+
+ -- We need to set up an exception handler for implementing
+ -- 7.6.1(18). The remaining adjustments are tackled by the
+ -- implementation of adjust for record_controllers (see
+ -- s-finimp.adb).
+
+ -- This is skipped if we have no finalization
+
+ if Expand_Ctrl_Actions
+ and then not Restriction_Active (No_Finalization)
+ then
+ L := New_List (
+ Make_Block_Statement (Loc,
+ Handled_Statement_Sequence =>
+ Make_Handled_Sequence_Of_Statements (Loc,
+ Statements => L,
+ Exception_Handlers => New_List (
+ Make_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 assignement
+ -- for controlled objects as per 9.8(11).
+
+ if Controlled_Type (Typ)
+ and then Expand_Ctrl_Actions
+ and then Abort_Allowed
+ then
+ declare
+ Blk : constant Entity_Id :=
+ New_Internal_Entity
+ (E_Block, Current_Scope, Sloc (N), 'B');
+
+ begin
+ Set_Scope (Blk, Current_Scope);
+ Set_Etype (Blk, Standard_Void_Type);
+ Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N)));
+
+ Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer));
+ Set_At_End_Proc (Handled_Statement_Sequence (N),
+ New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc));
+ Expand_At_End_Handler
+ (Handled_Statement_Sequence (N), Blk);
+ end;
+ end if;
+
+ -- N has been rewritten to a block statement for which it is
+ -- known by construction that no checks are necessary: analyze
+ -- it with all checks suppressed.
+
+ Analyze (N, Suppress => All_Checks);
+ return;
+ end Tagged_Case;
+
+ -- Array types
+
+ elsif Is_Array_Type (Typ) then
+ declare
+ Actual_Rhs : Node_Id := Rhs;
+
+ begin
+ while Nkind_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 Is_Local_Variable_Reference (Lhs)
+ and then not Is_Known_Valid (Entity (Lhs))
+ and then In_Unconditional_Context (N)
+ then
+ Set_Is_Known_Valid (Entity (Lhs), True);
+ end if;
+
+ -- Case where right side may be invalid in the sense of the RM
+ -- reference above. The RM does not require that we check for the
+ -- validity on an assignment, but it does require that the assignment
+ -- of an invalid value not cause erroneous behavior.
+
+ -- The general approach in GNAT is to use the Is_Known_Valid flag
+ -- to avoid the need for validity checking on assignments. However
+ -- in some cases, we have to do validity checking in order to make
+ -- sure that the setting of this flag is correct.
+
+ else
+ -- Validate right side if we are validating copies
+
+ if Validity_Checks_On
+ and then Validity_Check_Copies
+ then
+ -- 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;
+
+ -- Defend against invalid subscripts on left side if we are in standard
+ -- validity checking mode. No need to do this if we are checking all
+ -- subscripts.
+
+ if Validity_Checks_On
+ and then Validity_Check_Default
+ and then not Validity_Check_Subscripts
+ then
+ Check_Valid_Lvalue_Subscripts (Lhs);
+ end if;
+
+ exception
+ when RE_Not_Available =>
+ return;
+ end Expand_N_Assignment_Statement;
+
+ ------------------------------
+ -- Expand_N_Block_Statement --
+ ------------------------------
+
+ -- Encode entity names defined in block statement
+
+ procedure Expand_N_Block_Statement (N : Node_Id) is
+ begin
+ Qualify_Entity_Names (N);
+ end Expand_N_Block_Statement;
+
+ -----------------------------
+ -- Expand_N_Case_Statement --
+ -----------------------------
+
+ procedure Expand_N_Case_Statement (N : Node_Id) is
+ Loc : constant Source_Ptr := Sloc (N);
+ Expr : constant Node_Id := Expression (N);
+ Alt : Node_Id;
+ Len : Nat;
+ Cond : Node_Id;
+ Choice : Node_Id;
+ Chlist : List_Id;
+
+ begin
+ -- Check for the situation where we know at compile time which branch
+ -- will be taken
+
+ if Compile_Time_Known_Value (Expr) then
+ Alt := Find_Static_Alternative (N);
+
+ -- Move statements from this alternative after the case statement.
+ -- They are already analyzed, so will be skipped by the analyzer.
+
+ Insert_List_After (N, Statements (Alt));
+
+ -- That leaves the case statement as a shell. So now we can kill all
+ -- other alternatives in the case statement.
+
+ Kill_Dead_Code (Expression (N));
+
+ declare
+ A : Node_Id;
+
+ begin
+ -- Loop through case alternatives, skipping pragmas, and skipping
+ -- the one alternative that we select (and therefore retain).
+
+ A := First (Alternatives (N));
+ while Present (A) loop
+ if A /= Alt
+ and then Nkind (A) = N_Case_Statement_Alternative
+ then
+ Kill_Dead_Code (Statements (A), Warn_On_Deleted_Code);
+ end if;
+
+ Next (A);
+ end loop;
+ end;
+
+ Rewrite (N, Make_Null_Statement (Loc));
+ return;
+ end if;
+
+ -- Here if the choice is not determined at compile time
+
+ declare
+ Last_Alt : constant Node_Id := Last (Alternatives (N));
+
+ Others_Present : Boolean;
+ Others_Node : Node_Id;
+
+ Then_Stms : List_Id;
+ Else_Stms : List_Id;
+
+ begin
+ if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then
+ Others_Present := True;
+ Others_Node := Last_Alt;
+ else
+ Others_Present := False;
+ end if;
+
+ -- First step is to worry about possible invalid argument. The RM
+ -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
+ -- outside the base range), then Constraint_Error must be raised.
+
+ -- Case of validity check required (validity checks are on, the
+ -- expression is not known to be valid, and the case statement
+ -- comes from source -- no need to validity check internally
+ -- generated case statements).
+
+ if Validity_Check_Default then
+ Ensure_Valid (Expr);
+ end if;
+
+ -- If there is only a single alternative, just replace it with the
+ -- sequence of statements since obviously that is what is going to
+ -- be executed in all cases.
+
+ Len := List_Length (Alternatives (N));
+
+ if Len = 1 then
+ -- We still need to evaluate the expression if it has any
+ -- side effects.
+
+ Remove_Side_Effects (Expression (N));
+
+ Insert_List_After (N, Statements (First (Alternatives (N))));
+
+ -- That leaves the case statement as a shell. The alternative that
+ -- will be executed is reset to a null list. So now we can kill
+ -- the entire case statement.
+
+ Kill_Dead_Code (Expression (N));
+ Rewrite (N, Make_Null_Statement (Loc));
+ return;
+ end if;
+
+ -- An optimization. If there are only two alternatives, and only
+ -- a single choice, then rewrite the whole case statement as an
+ -- if statement, since this can result in susbequent optimizations.
+ -- This helps not only with case statements in the source of a
+ -- simple form, but also with generated code (discriminant check
+ -- functions in particular)
+
+ if Len = 2 then
+ Chlist := Discrete_Choices (First (Alternatives (N)));
+
+ if List_Length (Chlist) = 1 then
+ Choice := First (Chlist);
+
+ Then_Stms := Statements (First (Alternatives (N)));
+ Else_Stms := Statements (Last (Alternatives (N)));
+
+ -- For TRUE, generate "expression", not expression = true
+
+ if Nkind (Choice) = N_Identifier
+ and then Entity (Choice) = Standard_True
+ then
+ Cond := Expression (N);
+
+ -- For FALSE, generate "expression" and switch then/else
+
+ elsif Nkind (Choice) = N_Identifier
+ and then Entity (Choice) = Standard_False
+ then
+ Cond := Expression (N);
+ Else_Stms := Statements (First (Alternatives (N)));
+ Then_Stms := Statements (Last (Alternatives (N)));
+
+ -- For a range, generate "expression in range"
+
+ elsif Nkind (Choice) = N_Range
+ or else (Nkind (Choice) = N_Attribute_Reference
+ and then Attribute_Name (Choice) = Name_Range)
+ or else (Is_Entity_Name (Choice)
+ and then Is_Type (Entity (Choice)))
+ or else Nkind (Choice) = N_Subtype_Indication
+ then
+ Cond :=
+ Make_In (Loc,
+ Left_Opnd => Expression (N),
+ Right_Opnd => Relocate_Node (Choice));
+
+ -- For any other subexpression "expression = value"
+
+ else
+ Cond :=
+ Make_Op_Eq (Loc,
+ Left_Opnd => Expression (N),
+ Right_Opnd => Relocate_Node (Choice));
+ end if;
+
+ -- Now rewrite the case as an IF
+
+ Rewrite (N,
+ Make_If_Statement (Loc,
+ Condition => Cond,
+ Then_Statements => Then_Stms,
+ Else_Statements => Else_Stms));
+ Analyze (N);
+ return;
+ end if;
+ end if;
+
+ -- If the last alternative is not an Others choice, replace it with
+ -- an N_Others_Choice. Note that we do not bother to call Analyze on
+ -- the modified case statement, since it's only effect would be to
+ -- compute the contents of the Others_Discrete_Choices which is not
+ -- needed by the back end anyway.
+
+ -- The reason we do this is that the back end always needs some
+ -- default for a switch, so if we have not supplied one in the
+ -- processing above for validity checking, then we need to supply
+ -- one here.
+
+ if not Others_Present then
+ Others_Node := Make_Others_Choice (Sloc (Last_Alt));
+ Set_Others_Discrete_Choices
+ (Others_Node, Discrete_Choices (Last_Alt));
+ Set_Discrete_Choices (Last_Alt, New_List (Others_Node));
+ end if;
+ end;
+ end Expand_N_Case_Statement;
+
+ -----------------------------
+ -- Expand_N_Exit_Statement --
+ -----------------------------
+
+ -- The only processing required is to deal with a possible C/Fortran
+ -- boolean value used as the condition for the exit statement.
+
+ procedure Expand_N_Exit_Statement (N : Node_Id) is
+ begin
+ Adjust_Condition (Condition (N));
+ end Expand_N_Exit_Statement;
+
+ ----------------------------------------
+ -- Expand_N_Extended_Return_Statement --
+ ----------------------------------------
+
+ -- If there is a Handled_Statement_Sequence, we rewrite this:
+
+ -- return Result : T := <expression> do
+ -- <handled_seq_of_stms>
+ -- end return;
+
+ -- to be:
+
+ -- declare
+ -- Result : T := <expression>;
+ -- begin
+ -- <handled_seq_of_stms>
+ -- return Result;
+ -- end;
+
+ -- Otherwise (no Handled_Statement_Sequence), we rewrite this:
+
+ -- return Result : T := <expression>;
+
+ -- to be:
+
+ -- return <expression>;
+
+ -- unless it's build-in-place or there's no <expression>, in which case
+ -- we generate:
+
+ -- declare
+ -- Result : T := <expression>;
+ -- begin
+ -- return Result;
+ -- end;
+
+ -- Note that this case could have been written by the user as an extended
+ -- return statement, or could have been transformed to this from a simple
+ -- return statement.
+
+ -- That is, we need to have a reified return object if there are statements
+ -- (which might refer to it) or if we're doing build-in-place (so we can
+ -- set its address to the final resting place or if there is no expression
+ -- (in which case default initial values might need to be set).
+
+ procedure Expand_N_Extended_Return_Statement (N : Node_Id) is
+ Loc : constant Source_Ptr := Sloc (N);
+
+ Return_Object_Entity : constant Entity_Id :=
+ First_Entity (Return_Statement_Entity (N));
+ Return_Object_Decl : constant Node_Id :=
+ Parent (Return_Object_Entity);
+ Parent_Function : constant Entity_Id :=
+ Return_Applies_To (Return_Statement_Entity (N));
+ Is_Build_In_Place : constant Boolean :=
+ Is_Build_In_Place_Function (Parent_Function);
+
+ Return_Stm : Node_Id;
+ Statements : List_Id;
+ Handled_Stm_Seq : Node_Id;
+ Result : Node_Id;
+ Exp : Node_Id;
+
+ function Move_Activation_Chain return Node_Id;
+ -- Construct a call to System.Tasking.Stages.Move_Activation_Chain
+ -- with parameters:
+ -- From current activation chain
+ -- To activation chain passed in by the caller
+ -- New_Master master passed in by the caller
+
+ function Move_Final_List return Node_Id;
+ -- Construct call to System.Finalization_Implementation.Move_Final_List
+ -- with parameters:
+ --
+ -- From finalization list of the return statement
+ -- To finalization list passed in by the caller
+
+ ---------------------------
+ -- Move_Activation_Chain --
+ ---------------------------
+
+ function Move_Activation_Chain return Node_Id is
+ Activation_Chain_Formal : constant Entity_Id :=
+ Build_In_Place_Formal
+ (Parent_Function, BIP_Activation_Chain);
+ To : constant Node_Id :=
+ New_Reference_To
+ (Activation_Chain_Formal, Loc);
+ Master_Formal : constant Entity_Id :=
+ Build_In_Place_Formal
+ (Parent_Function, BIP_Master);
+ New_Master : constant Node_Id :=
+ New_Reference_To (Master_Formal, Loc);
+
+ Chain_Entity : Entity_Id;
+ From : Node_Id;
+
+ begin
+ Chain_Entity := First_Entity (Return_Statement_Entity (N));
+ while Chars (Chain_Entity) /= Name_uChain loop
+ Chain_Entity := Next_Entity (Chain_Entity);
+ end loop;
+
+ From :=
+ Make_Attribute_Reference (Loc,
+ Prefix => New_Reference_To (Chain_Entity, Loc),
+ Attribute_Name => Name_Unrestricted_Access);
+ -- ??? Not clear why "Make_Identifier (Loc, Name_uChain)" doesn't
+ -- work, instead of "New_Reference_To (Chain_Entity, Loc)" above.
+
+ return
+ Make_Procedure_Call_Statement (Loc,
+ Name => New_Reference_To (RTE (RE_Move_Activation_Chain), Loc),
+ Parameter_Associations => New_List (From, To, New_Master));
+ end Move_Activation_Chain;
+
+ ---------------------
+ -- Move_Final_List --
+ ---------------------
+
+ function Move_Final_List return Node_Id is
+ Flist : constant Entity_Id :=
+ Finalization_Chain_Entity (Return_Statement_Entity (N));
+
+ From : constant Node_Id := New_Reference_To (Flist, Loc);
+
+ Caller_Final_List : constant Entity_Id :=
+ Build_In_Place_Formal
+ (Parent_Function, BIP_Final_List);
+
+ To : constant Node_Id := New_Reference_To (Caller_Final_List, Loc);
+
+ begin
+ -- Catch cases where a finalization chain entity has not been
+ -- associated with the return statement entity.
+
+ pragma Assert (Present (Flist));
+
+ -- Build required call
+
+ return
+ Make_If_Statement (Loc,
+ Condition =>
+ Make_Op_Ne (Loc,
+ Left_Opnd => New_Copy (From),
+ Right_Opnd => New_Node (N_Null, Loc)),
+ Then_Statements =>
+ New_List (
+ Make_Procedure_Call_Statement (Loc,
+ Name => New_Reference_To (RTE (RE_Move_Final_List), Loc),
+ Parameter_Associations => New_List (From, To))));
+ end Move_Final_List;
+
+ -- Start of processing for Expand_N_Extended_Return_Statement
+
+ begin
+ if Nkind (Return_Object_Decl) = N_Object_Declaration then
+ Exp := Expression (Return_Object_Decl);
+ else
+ Exp := Empty;
+ end if;
+
+ Handled_Stm_Seq := Handled_Statement_Sequence (N);
+
+ -- Build a simple_return_statement that returns the return object when
+ -- there is a statement sequence, or no expression, or the result will
+ -- be built in place. Note however that we currently do this for all
+ -- composite cases, even though nonlimited composite results are not yet
+ -- built in place (though we plan to do so eventually).
+
+ if Present (Handled_Stm_Seq)
+ or else Is_Composite_Type (Etype (Parent_Function))
+ or else No (Exp)
+ then
+ if No (Handled_Stm_Seq) then
+ Statements := New_List;
+
+ -- If the extended return has a handled statement sequence, then wrap
+ -- it in a block and use the block as the first statement.
+
+ else
+ Statements :=
+ New_List (Make_Block_Statement (Loc,
+ Declarations => New_List,
+ Handled_Statement_Sequence => Handled_Stm_Seq));
+ end if;
+
+ -- If control gets past the above Statements, we have successfully
+ -- completed the return statement. If the result type has controlled
+ -- parts and the return is for a build-in-place function, then we
+ -- call Move_Final_List to transfer responsibility for finalization
+ -- of the return object to the caller. An alternative would be to
+ -- declare a Success flag in the function, initialize it to False,
+ -- and set it to True here. Then move the Move_Final_List call into
+ -- the cleanup code, and check Success. If Success then make a call
+ -- to Move_Final_List else do finalization. Then we can remove the
+ -- abort-deferral and the nulling-out of the From parameter from
+ -- Move_Final_List. Note that the current method is not quite correct
+ -- in the rather obscure case of a select-then-abort statement whose
+ -- abortable part contains the return statement.
+
+ -- We test the type of the expression as well as the return type
+ -- of the function, because the latter may be a class-wide type
+ -- which is always treated as controlled, while the expression itself
+ -- has to have a definite type. The expression may be absent if a
+ -- constrained aggregate has been expanded into component assignments
+ -- so we have to check for this as well.
+
+ if Is_Build_In_Place
+ and then Controlled_Type (Etype (Parent_Function))
+ then
+ if not Is_Class_Wide_Type (Etype (Parent_Function))
+ or else
+ (Present (Exp)
+ and then Controlled_Type (Etype (Exp)))
+ then
+ Append_To (Statements, Move_Final_List);
+ end if;
+ end if;
+
+ -- Similarly to the above Move_Final_List, if the result type
+ -- contains tasks, we call Move_Activation_Chain. Later, the cleanup
+ -- code will call Complete_Master, which will terminate any
+ -- unactivated tasks belonging to the return statement master. But
+ -- Move_Activation_Chain updates their master to be that of the
+ -- caller, so they will not be terminated unless the return statement
+ -- completes unsuccessfully due to exception, abort, goto, or exit.
+ -- As a formality, we test whether the function requires the result
+ -- to be built in place, though that's necessarily true for the case
+ -- of result types with task parts.
+
+ if Is_Build_In_Place and Has_Task (Etype (Parent_Function)) then
+ Append_To (Statements, Move_Activation_Chain);
+ end if;
+
+ -- Build a simple_return_statement that returns the return object
+
+ Return_Stm :=
+ Make_Simple_Return_Statement (Loc,
+ Expression => New_Occurrence_Of (Return_Object_Entity, Loc));
+ Append_To (Statements, Return_Stm);
+
+ Handled_Stm_Seq :=
+ Make_Handled_Sequence_Of_Statements (Loc, Statements);
+ end if;
+
+ -- Case where we build a block
+
+ if Present (Handled_Stm_Seq) then
+ Result :=
+ Make_Block_Statement (Loc,
+ Declarations => Return_Object_Declarations (N),
+ Handled_Statement_Sequence => Handled_Stm_Seq);
+
+ -- We set the entity of the new block statement to be that of the
+ -- return statement. This is necessary so that various fields, such
+ -- as Finalization_Chain_Entity carry over from the return statement
+ -- to the block. Note that this block is unusual, in that its entity
+ -- is an E_Return_Statement rather than an E_Block.
+
+ Set_Identifier
+ (Result, New_Occurrence_Of (Return_Statement_Entity (N), Loc));
+
+ -- If the object decl was already rewritten as a renaming, then
+ -- we don't want to do the object allocation and transformation of
+ -- of the return object declaration to a renaming. This case occurs
+ -- when the return object is initialized by a call to another
+ -- build-in-place function, and that function is responsible for the
+ -- allocation of the return object.
+
+ if Is_Build_In_Place
+ and then
+ Nkind (Return_Object_Decl) = N_Object_Renaming_Declaration
+ then
+ Set_By_Ref (Return_Stm); -- Return build-in-place results by ref
+
+ elsif Is_Build_In_Place then
+
+ -- Locate the implicit access parameter associated with the
+ -- caller-supplied return object and convert the return
+ -- statement's return object declaration to a renaming of a
+ -- dereference of the access parameter. If the return object's
+ -- declaration includes an expression that has not already been
+ -- expanded as separate assignments, then add an assignment
+ -- statement to ensure the return object gets initialized.
+
+ -- declare
+ -- Result : T [:= <expression>];
+ -- begin
+ -- ...
+
+ -- is converted to
+
+ -- declare
+ -- Result : T renames FuncRA.all;
+ -- [Result := <expression;]
+ -- begin
+ -- ...
+
+ declare
+ Return_Obj_Id : constant Entity_Id :=
+ Defining_Identifier (Return_Object_Decl);
+ Return_Obj_Typ : constant Entity_Id := Etype (Return_Obj_Id);
+ Return_Obj_Expr : constant Node_Id :=
+ Expression (Return_Object_Decl);
+ Result_Subt : constant Entity_Id :=
+ Etype (Parent_Function);
+ Constr_Result : constant Boolean :=
+ Is_Constrained (Result_Subt);
+ Obj_Alloc_Formal : Entity_Id;
+ Object_Access : Entity_Id;
+ Obj_Acc_Deref : Node_Id;
+ Init_Assignment : Node_Id := Empty;
+
+ begin
+ -- Build-in-place results must be returned by reference
+
+ Set_By_Ref (Return_Stm);
+
+ -- Retrieve the implicit access parameter passed by the caller
+
+ Object_Access :=
+ Build_In_Place_Formal (Parent_Function, BIP_Object_Access);
+
+ -- If the return object's declaration includes an expression
+ -- and the declaration isn't marked as No_Initialization, then
+ -- we need to generate an assignment to the object and insert
+ -- it after the declaration before rewriting it as a renaming
+ -- (otherwise we'll lose the initialization).
+
+ if Present (Return_Obj_Expr)
+ and then not No_Initialization (Return_Object_Decl)
+ then
+ Init_Assignment :=
+ Make_Assignment_Statement (Loc,
+ Name => New_Reference_To (Return_Obj_Id, Loc),
+ Expression => Relocate_Node (Return_Obj_Expr));
+ Set_Etype (Name (Init_Assignment), Etype (Return_Obj_Id));
+ Set_Assignment_OK (Name (Init_Assignment));
+ Set_No_Ctrl_Actions (Init_Assignment);
+
+ Set_Parent (Name (Init_Assignment), Init_Assignment);
+ Set_Parent (Expression (Init_Assignment), Init_Assignment);
+
+ Set_Expression (Return_Object_Decl, Empty);
+
+ if Is_Class_Wide_Type (Etype (Return_Obj_Id))
+ and then not Is_Class_Wide_Type
+ (Etype (Expression (Init_Assignment)))
+ then
+ Rewrite (Expression (Init_Assignment),
+ Make_Type_Conversion (Loc,
+ Subtype_Mark =>
+ New_Occurrence_Of
+ (Etype (Return_Obj_Id), Loc),
+ Expression =>
+ Relocate_Node (Expression (Init_Assignment))));
+ end if;
+
+ -- In the case of functions where the calling context can
+ -- determine the form of allocation needed, initialization
+ -- is done with each part of the if statement that handles
+ -- the different forms of allocation (this is true for
+ -- unconstrained and tagged result subtypes).
+
+ if Constr_Result
+ and then not Is_Tagged_Type (Underlying_Type (Result_Subt))
+ then
+ Insert_After (Return_Object_Decl, Init_Assignment);
+ end if;
+ end if;
+
+ -- When the function's subtype is unconstrained, a run-time
+ -- test is needed to determine the form of allocation to use
+ -- for the return object. The function has an implicit formal
+ -- parameter indicating this. If the BIP_Alloc_Form formal has
+ -- the value one, then the caller has passed access to an
+ -- existing object for use as the return object. If the value
+ -- is two, then the return object must be allocated on the
+ -- secondary stack. Otherwise, the object must be allocated in
+ -- a storage pool (currently only supported for the global
+ -- heap, user-defined storage pools TBD ???). We generate an
+ -- if statement to test the implicit allocation formal and
+ -- initialize a local access value appropriately, creating
+ -- allocators in the secondary stack and global heap cases.
+ -- The special formal also exists and must be tested when the
+ -- function has a tagged result, even when the result subtype
+ -- is constrained, because in general such functions can be
+ -- called in dispatching contexts and must be handled similarly
+ -- to functions with a class-wide result.
+
+ if not Constr_Result
+ or else Is_Tagged_Type (Underlying_Type (Result_Subt))
+ then
+ Obj_Alloc_Formal :=
+ Build_In_Place_Formal (Parent_Function, BIP_Alloc_Form);
+
+ declare
+ Ref_Type : Entity_Id;
+ Ptr_Type_Decl : Node_Id;
+ Alloc_Obj_Id : Entity_Id;
+ Alloc_Obj_Decl : Node_Id;
+ Alloc_If_Stmt : Node_Id;
+ SS_Allocator : Node_Id;
+ Heap_Allocator : Node_Id;
+
+ begin
+ -- Reuse the itype created for the function's implicit
+ -- access formal. This avoids the need to create a new
+ -- access type here, plus it allows assigning the access
+ -- formal directly without applying a conversion.
+
+ -- Ref_Type := Etype (Object_Access);
+
+ -- Create an access type designating the function's
+ -- result subtype.
+
+ Ref_Type :=
+ Make_Defining_Identifier (Loc, New_Internal_Name ('A'));
+
+ Ptr_Type_Decl :=
+ Make_Full_Type_Declaration (Loc,
+ Defining_Identifier => Ref_Type,
+ Type_Definition =>
+ Make_Access_To_Object_Definition (Loc,
+ All_Present => True,
+ Subtype_Indication =>
+ New_Reference_To (Return_Obj_Typ, Loc)));
+
+ Insert_Before (Return_Object_Decl, Ptr_Type_Decl);
+
+ -- Create an access object that will be initialized to an
+ -- access value denoting the return object, either coming
+ -- from an implicit access value passed in by the caller
+ -- or from the result of an allocator.
+
+ Alloc_Obj_Id :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_Internal_Name ('R'));
+ Set_Etype (Alloc_Obj_Id, Ref_Type);
+
+ Alloc_Obj_Decl :=
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Alloc_Obj_Id,
+ Object_Definition => New_Reference_To
+ (Ref_Type, Loc));
+
+ Insert_Before (Return_Object_Decl, Alloc_Obj_Decl);
+
+ -- Create allocators for both the secondary stack and
+ -- global heap. If there's an initialization expression,
+ -- then create these as initialized allocators.
+
+ if Present (Return_Obj_Expr)
+ and then not No_Initialization (Return_Object_Decl)
+ then
+ Heap_Allocator :=
+ Make_Allocator (Loc,
+ Expression =>
+ Make_Qualified_Expression (Loc,
+ Subtype_Mark =>
+ New_Reference_To (Return_Obj_Typ, Loc),
+ Expression =>
+ New_Copy_Tree (Return_Obj_Expr)));
+
+ SS_Allocator := New_Copy_Tree (Heap_Allocator);
+
+ else
+ -- If the function returns a class-wide type we cannot
+ -- use the return type for the allocator. Instead we
+ -- use the type of the expression, which must be an
+ -- aggregate of a definite type.
+
+ if Is_Class_Wide_Type (Return_Obj_Typ) then
+ Heap_Allocator :=
+ Make_Allocator (Loc,
+ New_Reference_To
+ (Etype (Return_Obj_Expr), Loc));
+ else
+ Heap_Allocator :=
+ Make_Allocator (Loc,
+ New_Reference_To (Return_Obj_Typ, Loc));
+ end if;
+
+ -- If the object requires default initialization then
+ -- that will happen later following the elaboration of
+ -- the object renaming. If we don't turn it off here
+ -- then the object will be default initialized twice.
+
+ Set_No_Initialization (Heap_Allocator);
+
+ SS_Allocator := New_Copy_Tree (Heap_Allocator);
+ end if;
+
+ -- The allocator is returned on the secondary stack. We
+ -- don't do this on VM targets, since the SS is not used.
+
+ if VM_Target = No_VM then
+ Set_Storage_Pool (SS_Allocator, RTE (RE_SS_Pool));
+ Set_Procedure_To_Call
+ (SS_Allocator, RTE (RE_SS_Allocate));
+
+ -- The allocator is returned on the secondary stack,
+ -- so indicate that the function return, as well as
+ -- the block that encloses the allocator, must not
+ -- release it. The flags must be set now because the
+ -- decision to use the secondary stack is done very
+ -- late in the course of expanding the return
+ -- statement, past the point where these flags are
+ -- normally set.
+
+ Set_Sec_Stack_Needed_For_Return (Parent_Function);
+ Set_Sec_Stack_Needed_For_Return
+ (Return_Statement_Entity (N));
+ Set_Uses_Sec_Stack (Parent_Function);
+ Set_Uses_Sec_Stack (Return_Statement_Entity (N));
+ end if;
+
+ -- Create an if statement to test the BIP_Alloc_Form
+ -- formal and initialize the access object to either the
+ -- BIP_Object_Access formal (BIP_Alloc_Form = 0), the
+ -- result of allocating the object in the secondary stack
+ -- (BIP_Alloc_Form = 1), or else an allocator to create
+ -- the return object in the heap (BIP_Alloc_Form = 2).
+
+ -- ??? An unchecked type conversion must be made in the
+ -- case of assigning the access object formal to the
+ -- local access object, because a normal conversion would
+ -- be illegal in some cases (such as converting access-
+ -- to-unconstrained to access-to-constrained), but the
+ -- the unchecked conversion will presumably fail to work
+ -- right in just such cases. It's not clear at all how to
+ -- handle this. ???
+
+ Alloc_If_Stmt :=
+ Make_If_Statement (Loc,
+ Condition =>
+ Make_Op_Eq (Loc,
+ Left_Opnd =>
+ New_Reference_To (Obj_Alloc_Formal, Loc),
+ Right_Opnd =>
+ Make_Integer_Literal (Loc,
+ UI_From_Int (BIP_Allocation_Form'Pos
+ (Caller_Allocation)))),
+ Then_Statements =>
+ New_List (Make_Assignment_Statement (Loc,
+ Name =>
+ New_Reference_To
+ (Alloc_Obj_Id, Loc),
+ Expression =>
+ Make_Unchecked_Type_Conversion (Loc,
+ Subtype_Mark =>
+ New_Reference_To (Ref_Type, Loc),
+ Expression =>
+ New_Reference_To
+ (Object_Access, Loc)))),
+ Elsif_Parts =>
+ New_List (Make_Elsif_Part (Loc,
+ Condition =>
+ Make_Op_Eq (Loc,
+ Left_Opnd =>
+ New_Reference_To
+ (Obj_Alloc_Formal, Loc),
+ Right_Opnd =>
+ Make_Integer_Literal (Loc,
+ UI_From_Int (
+ BIP_Allocation_Form'Pos
+ (Secondary_Stack)))),
+ Then_Statements =>
+ New_List
+ (Make_Assignment_Statement (Loc,
+ Name =>
+ New_Reference_To
+ (Alloc_Obj_Id, Loc),
+ Expression =>
+ SS_Allocator)))),
+ Else_Statements =>
+ New_List (Make_Assignment_Statement (Loc,
+ Name =>
+ New_Reference_To
+ (Alloc_Obj_Id, Loc),
+ Expression =>
+ Heap_Allocator)));
+
+ -- If a separate initialization assignment was created
+ -- earlier, append that following the assignment of the
+ -- implicit access formal to the access object, to ensure
+ -- that the return object is initialized in that case.
+ -- In this situation, the target of the assignment must
+ -- be rewritten to denote a derference of the access to
+ -- the return object passed in by the caller.
+
+ if Present (Init_Assignment) then
+ Rewrite (Name (Init_Assignment),
+ Make_Explicit_Dereference (Loc,
+ Prefix => New_Reference_To (Alloc_Obj_Id, Loc)));
+ Set_Etype
+ (Name (Init_Assignment), Etype (Return_Obj_Id));
+
+ Append_To
+ (Then_Statements (Alloc_If_Stmt),
+ Init_Assignment);
+ end if;
+
+ Insert_Before (Return_Object_Decl, Alloc_If_Stmt);
+
+ -- Remember the local access object for use in the
+ -- dereference of the renaming created below.
+
+ Object_Access := Alloc_Obj_Id;
+ end;
+ end if;
+
+ -- Replace the return object declaration with a renaming of a
+ -- dereference of the access value designating the return
+ -- object.
+
+ Obj_Acc_Deref :=
+ Make_Explicit_Dereference (Loc,
+ Prefix => New_Reference_To (Object_Access, Loc));
+
+ Rewrite (Return_Object_Decl,
+ Make_Object_Renaming_Declaration (Loc,
+ Defining_Identifier => Return_Obj_Id,
+ Access_Definition => Empty,
+ Subtype_Mark => New_Occurrence_Of
+ (Return_Obj_Typ, Loc),
+ Name => Obj_Acc_Deref));
+
+ Set_Renamed_Object (Return_Obj_Id, Obj_Acc_Deref);
+ end;
+ end if;
+
+ -- Case where we do not build a block
+
+ else
+ -- We're about to drop Return_Object_Declarations on the floor, so
+ -- we need to insert it, in case it got expanded into useful code.
+
+ Insert_List_Before (N, Return_Object_Declarations (N));
+
+ -- Build simple_return_statement that returns the expression directly
+
+ Return_Stm := Make_Simple_Return_Statement (Loc, Expression => Exp);
+
+ Result := Return_Stm;
+ end if;
+
+ -- Set the flag to prevent infinite recursion
+
+ Set_Comes_From_Extended_Return_Statement (Return_Stm);
+
+ Rewrite (N, Result);
+ Analyze (N);
+ end Expand_N_Extended_Return_Statement;
+
+ -----------------------------
+ -- Expand_N_Goto_Statement --
+ -----------------------------
+
+ -- Add poll before goto if polling active
+
+ procedure Expand_N_Goto_Statement (N : Node_Id) is
+ begin
+ Generate_Poll_Call (N);
+ end Expand_N_Goto_Statement;
+
+ ---------------------------
+ -- Expand_N_If_Statement --
+ ---------------------------
+
+ -- First we deal with the case of C and Fortran convention boolean values,
+ -- with zero/non-zero semantics.
+
+ -- Second, we deal with the obvious rewriting for the cases where the
+ -- condition of the IF is known at compile time to be True or False.
+
+ -- Third, we remove elsif parts which have non-empty Condition_Actions
+ -- and rewrite as independent if statements. For example:
+
+ -- if x then xs
+ -- elsif y then ys
+ -- ...
+ -- end if;
+
+ -- becomes
+ --
+ -- if x then xs
+ -- else
+ -- <<condition actions of y>>
+ -- if y then ys
+ -- ...
+ -- end if;
+ -- end if;
+
+ -- This rewriting is needed if at least one elsif part has a non-empty
+ -- Condition_Actions list. We also do the same processing if there is a
+ -- constant condition in an elsif part (in conjunction with the first
+ -- processing step mentioned above, for the recursive call made to deal
+ -- with the created inner if, this deals with properly optimizing the
+ -- cases of constant elsif conditions).
+
+ procedure Expand_N_If_Statement (N : Node_Id) is
+ Loc : constant Source_Ptr := Sloc (N);
+ Hed : Node_Id;
+ E : Node_Id;
+ New_If : Node_Id;
+
+ Warn_If_Deleted : constant Boolean :=
+ Warn_On_Deleted_Code and then Comes_From_Source (N);
+ -- Indicates whether we want warnings when we delete branches of the
+ -- if statement based on constant condition analysis. We never want
+ -- these warnings for expander generated code.
+
+ begin
+ Adjust_Condition (Condition (N));
+
+ -- The following loop deals with constant conditions for the IF. We
+ -- need a loop because as we eliminate False conditions, we grab the
+ -- first elsif condition and use it as the primary condition.
+
+ while Compile_Time_Known_Value (Condition (N)) loop
+
+ -- If condition is True, we can simply rewrite the if statement now
+ -- by replacing it by the series of then statements.
+
+ if Is_True (Expr_Value (Condition (N))) then
+
+ -- All the else parts can be killed
+
+ Kill_Dead_Code (Elsif_Parts (N), Warn_If_Deleted);
+ Kill_Dead_Code (Else_Statements (N), Warn_If_Deleted);
+
+ Hed := Remove_Head (Then_Statements (N));
+ Insert_List_After (N, Then_Statements (N));
+ Rewrite (N, Hed);
+ return;
+
+ -- If condition is False, then we can delete the condition and
+ -- the Then statements
+
+ else
+ -- We do not delete the condition if constant condition warnings
+ -- are enabled, since otherwise we end up deleting the desired
+ -- warning. Of course the backend will get rid of this True/False
+ -- test anyway, so nothing is lost here.
+
+ if not Constant_Condition_Warnings then
+ Kill_Dead_Code (Condition (N));
+ end if;
+
+ Kill_Dead_Code (Then_Statements (N), Warn_If_Deleted);
+
+ -- If there are no elsif statements, then we simply replace the
+ -- entire if statement by the sequence of else statements.
+
+ if No (Elsif_Parts (N)) then
+ if No (Else_Statements (N))
+ or else Is_Empty_List (Else_Statements (N))
+ then
+ Rewrite (N,
+ Make_Null_Statement (Sloc (N)));
+ else
+ Hed := Remove_Head (Else_Statements (N));
+ Insert_List_After (N, Else_Statements (N));
+ Rewrite (N, Hed);
+ end if;
+
+ return;
+
+ -- If there are elsif statements, the first of them becomes the
+ -- if/then section of the rebuilt if statement This is the case
+ -- where we loop to reprocess this copied condition.
+
+ else
+ Hed := Remove_Head (Elsif_Parts (N));
+ Insert_Actions (N, Condition_Actions (Hed));
+ Set_Condition (N, Condition (Hed));
+ Set_Then_Statements (N, Then_Statements (Hed));
+
+ -- Hed might have been captured as the condition determining
+ -- the current value for an entity. Now it is detached from
+ -- the tree, so a Current_Value pointer in the condition might
+ -- need to be updated.
+
+ Set_Current_Value_Condition (N);
+
+ if Is_Empty_List (Elsif_Parts (N)) then
+ Set_Elsif_Parts (N, No_List);
+ end if;
+ end if;
+ end if;
+ end loop;
+
+ -- Loop through elsif parts, dealing with constant conditions and
+ -- possible expression actions that are present.
+
+ if Present (Elsif_Parts (N)) then
+ E := First (Elsif_Parts (N));
+ while Present (E) loop
+ Adjust_Condition (Condition (E));
+
+ -- If there are condition actions, then rewrite the if statement
+ -- as indicated above. We also do the same rewrite for a True or
+ -- False condition. The further processing of this constant
+ -- condition is then done by the recursive call to expand the
+ -- newly created if statement
+
+ if Present (Condition_Actions (E))
+ or else Compile_Time_Known_Value (Condition (E))
+ then
+ -- Note this is not an implicit if statement, since it is part
+ -- of an explicit if statement in the source (or of an implicit
+ -- if statement that has already been tested).
+
+ New_If :=
+ Make_If_Statement (Sloc (E),
+ Condition => Condition (E),
+ Then_Statements => Then_Statements (E),
+ Elsif_Parts => No_List,
+ Else_Statements => Else_Statements (N));
+
+ -- Elsif parts for new if come from remaining elsif's of parent
+
+ while Present (Next (E)) loop
+ if No (Elsif_Parts (New_If)) then
+ Set_Elsif_Parts (New_If, New_List);
+ end if;
+
+ Append (Remove_Next (E), Elsif_Parts (New_If));
+ end loop;
+
+ Set_Else_Statements (N, New_List (New_If));
+
+ if Present (Condition_Actions (E)) then
+ Insert_List_Before (New_If, Condition_Actions (E));
+ end if;
+
+ Remove (E);
+
+ if Is_Empty_List (Elsif_Parts (N)) then
+ Set_Elsif_Parts (N, No_List);
+ end if;
+
+ Analyze (New_If);
+ return;
+
+ -- No special processing for that elsif part, move to next
+
+ else
+ Next (E);
+ end if;
+ end loop;
+ end if;
+
+ -- Some more optimizations applicable if we still have an IF statement
+
+ if Nkind (N) /= N_If_Statement then
+ return;
+ end if;
+
+ -- Another optimization, special cases that can be simplified
+
+ -- if expression then
+ -- return true;
+ -- else
+ -- return false;
+ -- end if;
+
+ -- can be changed to:
+
+ -- return expression;
+
+ -- and
+
+ -- if expression then
+ -- return false;
+ -- else
+ -- return true;
+ -- end if;
+
+ -- can be changed to:
+
+ -- return not (expression);
+
+ 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 Expand_N_If_Statement;
+
+ -----------------------------
+ -- Expand_N_Loop_Statement --
+ -----------------------------
+
+ -- 1. Deal with while condition for C/Fortran boolean
+ -- 2. Deal with loops with a non-standard enumeration type range
+ -- 3. Deal with while loops where Condition_Actions is set
+ -- 4. Insert polling call if required
+
+ procedure Expand_N_Loop_Statement (N : Node_Id) is
+ Loc : constant Source_Ptr := Sloc (N);
+ Isc : constant Node_Id := Iteration_Scheme (N);
+
+ begin
+ if Present (Isc) then
+ Adjust_Condition (Condition (Isc));
+ end if;
+
+ if Is_Non_Empty_List (Statements (N)) then
+ Generate_Poll_Call (First (Statements (N)));
+ end if;
+
+ -- Nothing more to do for plain loop with no iteration scheme
+
+ if No (Isc) then
+ return;
+ end if;
+
+ -- Note: we do not have to worry about validity chekcing of the for loop
+ -- range bounds here, since they were frozen with constant declarations
+ -- and it is during that process that the validity checking is done.
+
+ -- Handle the case where we have a for loop with the range type being an
+ -- enumeration type with non-standard representation. In this case we
+ -- expand:
+
+ -- for x in [reverse] a .. b loop
+ -- ...
+ -- end loop;
+
+ -- to
+
+ -- for xP in [reverse] integer
+ -- range etype'Pos (a) .. etype'Pos (b) loop
+ -- declare
+ -- x : constant etype := Pos_To_Rep (xP);
+ -- begin
+ -- ...
+ -- end;
+ -- end loop;
+
+ if Present (Loop_Parameter_Specification (Isc)) then
+ declare
+ LPS : constant Node_Id := Loop_Parameter_Specification (Isc);
+ Loop_Id : constant Entity_Id := Defining_Identifier (LPS);
+ Ltype : constant Entity_Id := Etype (Loop_Id);
+ Btype : constant Entity_Id := Base_Type (Ltype);
+ Expr : Node_Id;
+ New_Id : Entity_Id;
+
+ begin
+ if not Is_Enumeration_Type (Btype)
+ or else No (Enum_Pos_To_Rep (Btype))
+ then
+ return;
+ end if;
+
+ New_Id :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_External_Name (Chars (Loop_Id), 'P'));
+
+ -- If the type has a contiguous representation, successive values
+ -- can be generated as offsets from the first literal.
+
+ if Has_Contiguous_Rep (Btype) then
+ Expr :=
+ Unchecked_Convert_To (Btype,
+ Make_Op_Add (Loc,
+ Left_Opnd =>
+ Make_Integer_Literal (Loc,
+ Enumeration_Rep (First_Literal (Btype))),
+ Right_Opnd => New_Reference_To (New_Id, Loc)));
+ else
+ -- Use the constructed array Enum_Pos_To_Rep
+
+ Expr :=
+ Make_Indexed_Component (Loc,
+ Prefix => New_Reference_To (Enum_Pos_To_Rep (Btype), Loc),
+ Expressions => New_List (New_Reference_To (New_Id, Loc)));
+ end if;
+
+ Rewrite (N,
+ Make_Loop_Statement (Loc,
+ Identifier => Identifier (N),
+
+ Iteration_Scheme =>
+ Make_Iteration_Scheme (Loc,
+ Loop_Parameter_Specification =>
+ Make_Loop_Parameter_Specification (Loc,
+ Defining_Identifier => New_Id,
+ Reverse_Present => Reverse_Present (LPS),
+
+ Discrete_Subtype_Definition =>
+ Make_Subtype_Indication (Loc,
+
+ Subtype_Mark =>
+ New_Reference_To (Standard_Natural, Loc),
+
+ Constraint =>
+ Make_Range_Constraint (Loc,
+ Range_Expression =>
+ Make_Range (Loc,
+
+ Low_Bound =>
+ Make_Attribute_Reference (Loc,
+ Prefix =>
+ New_Reference_To (Btype, Loc),
+
+ Attribute_Name => Name_Pos,
+
+ Expressions => New_List (
+ Relocate_Node
+ (Type_Low_Bound (Ltype)))),
+
+ High_Bound =>
+ Make_Attribute_Reference (Loc,
+ Prefix =>
+ New_Reference_To (Btype, Loc),
+
+ Attribute_Name => Name_Pos,
+
+ Expressions => New_List (
+ Relocate_Node
+ (Type_High_Bound (Ltype))))))))),
+
+ Statements => New_List (
+ Make_Block_Statement (Loc,
+ Declarations => New_List (
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Loop_Id,
+ Constant_Present => True,
+ Object_Definition => New_Reference_To (Ltype, Loc),
+ Expression => Expr)),
+
+ Handled_Statement_Sequence =>
+ Make_Handled_Sequence_Of_Statements (Loc,
+ Statements => Statements (N)))),
+
+ End_Label => End_Label (N)));
+ Analyze (N);
+ end;
+
+ -- Second case, if we have a while loop with Condition_Actions set, then
+ -- we change it into a plain loop:
+
+ -- while C loop
+ -- ...
+ -- end loop;
+
+ -- changed to:
+
+ -- loop
+ -- <<condition actions>>
+ -- exit when not C;
+ -- ...
+ -- end loop
+
+ elsif Present (Isc)
+ and then Present (Condition_Actions (Isc))
+ then
+ declare
+ ES : Node_Id;
+
+ begin
+ ES :=
+ Make_Exit_Statement (Sloc (Condition (Isc)),
+ Condition =>
+ Make_Op_Not (Sloc (Condition (Isc)),
+ Right_Opnd => Condition (Isc)));
+
+ Prepend (ES, Statements (N));
+ Insert_List_Before (ES, Condition_Actions (Isc));
+
+ -- This is not an implicit loop, since it is generated in response
+ -- to the loop statement being processed. If this is itself
+ -- implicit, the restriction has already been checked. If not,
+ -- it is an explicit loop.
+
+ Rewrite (N,
+ Make_Loop_Statement (Sloc (N),
+ Identifier => Identifier (N),
+ Statements => Statements (N),
+ End_Label => End_Label (N)));
+
+ Analyze (N);
+ end;
+ end if;
+ end Expand_N_Loop_Statement;
+
+ --------------------------------------
+ -- Expand_N_Simple_Return_Statement --
+ --------------------------------------
+
+ procedure Expand_N_Simple_Return_Statement (N : Node_Id) is
+ begin
+ -- Distinguish the function and non-function cases:
+
+ case Ekind (Return_Applies_To (Return_Statement_Entity (N))) is
+
+ when E_Function |
+ E_Generic_Function =>
+ Expand_Simple_Function_Return (N);
+
+ when E_Procedure |
+ E_Generic_Procedure |
+ E_Entry |
+ E_Entry_Family |
+ E_Return_Statement =>
+ Expand_Non_Function_Return (N);
+
+ when others =>
+ raise Program_Error;
+ end case;
+
+ exception
+ when RE_Not_Available =>
+ return;
+ end Expand_N_Simple_Return_Statement;
+
+ --------------------------------
+ -- Expand_Non_Function_Return --
+ --------------------------------
+
+ procedure Expand_Non_Function_Return (N : Node_Id) is
+ pragma Assert (No (Expression (N)));
+
+ Loc : constant Source_Ptr := Sloc (N);
+ Scope_Id : Entity_Id :=
+ Return_Applies_To (Return_Statement_Entity (N));
+ Kind : constant Entity_Kind := Ekind (Scope_Id);
+ Call : Node_Id;
+ Acc_Stat : Node_Id;
+ Goto_Stat : Node_Id;
+ Lab_Node : Node_Id;
+
+ begin
+ -- If it is a return from a procedure do no extra steps
+
+ if Kind = E_Procedure or else Kind = E_Generic_Procedure then
+ return;
+
+ -- If it is a nested return within an extended one, replace it with a
+ -- return of the previously declared return object.
+
+ elsif Kind = E_Return_Statement then
+ Rewrite (N,
+ Make_Simple_Return_Statement (Loc,
+ Expression =>
+ New_Occurrence_Of (First_Entity (Scope_Id), Loc)));
+ Set_Comes_From_Extended_Return_Statement (N);
+ Set_Return_Statement_Entity (N, Scope_Id);
+ Expand_Simple_Function_Return (N);
+ return;
+ end if;
+
+ pragma Assert (Is_Entry (Scope_Id));
+
+ -- Look at the enclosing block to see whether the return is from an
+ -- accept statement or an entry body.
+
+ for J in reverse 0 .. Scope_Stack.Last loop
+ Scope_Id := Scope_Stack.Table (J).Entity;
+ exit when Is_Concurrent_Type (Scope_Id);
+ end loop;
+
+ -- If it is a return from accept statement it is expanded as call to
+ -- RTS Complete_Rendezvous and a goto to the end of the accept body.
+
+ -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
+ -- Expand_N_Accept_Alternative in exp_ch9.adb)
+
+ if Is_Task_Type (Scope_Id) then
+
+ Call :=
+ Make_Procedure_Call_Statement (Loc,
+ Name => New_Reference_To
+ (RTE (RE_Complete_Rendezvous), Loc));
+ Insert_Before (N, Call);
+ -- why not insert actions here???
+ Analyze (Call);
+
+ Acc_Stat := Parent (N);
+ while Nkind (Acc_Stat) /= N_Accept_Statement loop
+ Acc_Stat := Parent (Acc_Stat);
+ end loop;
+
+ Lab_Node := Last (Statements
+ (Handled_Statement_Sequence (Acc_Stat)));
+
+ Goto_Stat := Make_Goto_Statement (Loc,
+ Name => New_Occurrence_Of
+ (Entity (Identifier (Lab_Node)), Loc));
+
+ Set_Analyzed (Goto_Stat);
+
+ Rewrite (N, Goto_Stat);
+ Analyze (N);
+
+ -- If it is a return from an entry body, put a Complete_Entry_Body call
+ -- in front of the return.
+
+ elsif Is_Protected_Type (Scope_Id) then
+ Call :=
+ Make_Procedure_Call_Statement (Loc,
+ Name => New_Reference_To
+ (RTE (RE_Complete_Entry_Body), Loc),
+ Parameter_Associations => New_List
+ (Make_Attribute_Reference (Loc,
+ Prefix =>
+ New_Reference_To
+ (Object_Ref
+ (Corresponding_Body (Parent (Scope_Id))),
+ Loc),
+ Attribute_Name => Name_Unchecked_Access)));
+
+ Insert_Before (N, Call);
+ Analyze (Call);
+ end if;
+ end Expand_Non_Function_Return;
+
+ -----------------------------------
+ -- Expand_Simple_Function_Return --
+ -----------------------------------
+
+ -- The "simple" comes from the syntax rule simple_return_statement.
+ -- The semantics are not at all simple!
+
+ procedure Expand_Simple_Function_Return (N : Node_Id) is
+ Loc : constant Source_Ptr := Sloc (N);
+
+ Scope_Id : constant Entity_Id :=
+ Return_Applies_To (Return_Statement_Entity (N));
+ -- The function we are returning from
+
+ R_Type : constant Entity_Id := Etype (Scope_Id);
+ -- The result type of the function
+
+ Utyp : constant Entity_Id := Underlying_Type (R_Type);
+
+ Exp : constant Node_Id := Expression (N);
+ pragma Assert (Present (Exp));
+
+ Exptyp : constant Entity_Id := Etype (Exp);
+ -- The type of the expression (not necessarily the same as R_Type)
+
+ begin
+ -- We rewrite "return <expression>;" to be:
+
+ -- return _anon_ : <return_subtype> := <expression>
+
+ -- The expansion produced by Expand_N_Extended_Return_Statement will
+ -- contain simple return statements (for example, a block containing
+ -- simple return of the return object), which brings us back here with
+ -- Comes_From_Extended_Return_Statement set. To avoid infinite
+ -- recursion, we do not transform into an extended return if
+ -- Comes_From_Extended_Return_Statement is True.
+
+ -- The reason for this design is that for Ada 2005 limited returns, we
+ -- need to reify the return object, so we can build it "in place", and
+ -- we need a block statement to hang finalization and tasking stuff.
+
+ -- ??? In order to avoid disruption, we avoid translating to extended
+ -- return except in the cases where we really need to (Ada 2005
+ -- inherently limited). We would prefer eventually to do this
+ -- translation in all cases except perhaps for the case of Ada 95
+ -- inherently limited, in order to fully exercise the code in
+ -- Expand_N_Extended_Return_Statement, and in order to do
+ -- build-in-place for efficiency when it is not required.
+
+ -- As before, we check the type of the return expression rather than the
+ -- return type of the function, because the latter may be a limited
+ -- class-wide interface type, which is not a limited type, even though
+ -- the type of the expression may be.
+
+ if not Comes_From_Extended_Return_Statement (N)
+ and then Is_Inherently_Limited_Type (Etype (Expression (N)))
+ and then Ada_Version >= Ada_05 -- ???
+ and then not Debug_Flag_Dot_L
+ then
+ declare
+ Return_Object_Entity : constant Entity_Id :=
+ Make_Defining_Identifier (Loc,
+ New_Internal_Name ('R'));
+
+ Subtype_Ind : constant Node_Id := New_Occurrence_Of (R_Type, Loc);
+
+ Obj_Decl : constant Node_Id :=
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Return_Object_Entity,
+ Object_Definition => Subtype_Ind,
+ Expression => Exp);
+
+ Ext : constant Node_Id := Make_Extended_Return_Statement (Loc,
+ Return_Object_Declarations => New_List (Obj_Decl));
+
+ begin
+ Rewrite (N, Ext);
+ Analyze (N);
+ return;
+ end;
+ end if;
+
+ -- Here we have a simple return statement that is part of the expansion
+ -- of an extended return statement (either written by the user, or
+ -- generated by the above code).
+
+ -- Always normalize C/Fortran boolean result. This is not always needed,
+ -- but it seems a good idea to minimize the passing around of non-
+ -- normalized values, and in any case this handles the processing of
+ -- barrier functions for protected types, which turn the condition into
+ -- a return statement.
+
+ if Is_Boolean_Type (Exptyp)
+ and then Nonzero_Is_True (Exptyp)
+ then
+ Adjust_Condition (Exp);
+ Adjust_Result_Type (Exp, Exptyp);
+ end if;
+
+ -- Do validity check if enabled for returns
+
+ if Validity_Checks_On
+ and then Validity_Check_Returns
+ then
+ Ensure_Valid (Exp);
+ end if;
+
+ -- Check the result expression of a scalar function against the subtype
+ -- of the function by inserting a conversion. This conversion must
+ -- eventually be performed for other classes of types, but for now it's
+ -- only done for scalars.
+ -- ???
+
+ if Is_Scalar_Type (Exptyp) then
+ Rewrite (Exp, Convert_To (R_Type, Exp));
+ Analyze (Exp);
+ end if;
+
+ -- Deal with returning variable length objects and controlled types
+
+ -- Nothing to do if we are returning by reference, or this is not a
+ -- type that requires special processing (indicated by the fact that
+ -- it requires a cleanup scope for the secondary stack case).
+
+ if Is_Inherently_Limited_Type (Exptyp)
+ or else Is_Limited_Interface (Exptyp)
+ then
+ null;
+
+ elsif not Requires_Transient_Scope (R_Type) then
+
+ -- Mutable records with no variable length components are not
+ -- returned on the sec-stack, so we need to make sure that the
+ -- backend will only copy back the size of the actual value, and not
+ -- the maximum size. We create an actual subtype for this purpose.
+
+ declare
+ Ubt : constant Entity_Id := Underlying_Type (Base_Type (Exptyp));
+ Decl : Node_Id;
+ Ent : Entity_Id;
+ begin
+ if Has_Discriminants (Ubt)
+ and then not Is_Constrained (Ubt)
+ and then not Has_Unchecked_Union (Ubt)
+ then
+ Decl := Build_Actual_Subtype (Ubt, Exp);
+ Ent := Defining_Identifier (Decl);
+ Insert_Action (Exp, Decl);
+ Rewrite (Exp, Unchecked_Convert_To (Ent, Exp));
+ Analyze_And_Resolve (Exp);
+ end if;
+ end;
+
+ -- Here if secondary stack is used
+
+ else
+ -- Make sure that no surrounding block will reclaim the secondary
+ -- stack on which we are going to put the result. Not only may this
+ -- introduce secondary stack leaks but worse, if the reclamation is
+ -- done too early, then the result we are returning may get
+ -- clobbered.
+
+ declare
+ S : Entity_Id;
+ begin
+ S := Current_Scope;
+ while Ekind (S) = E_Block or else Ekind (S) = E_Loop loop
+ Set_Sec_Stack_Needed_For_Return (S, True);
+ S := Enclosing_Dynamic_Scope (S);
+ end loop;
+ end;
+
+ -- Optimize the case where the result is a function call. In this
+ -- case either the result is already on the secondary stack, or is
+ -- already being returned with the stack pointer depressed and no
+ -- further processing is required except to set the By_Ref flag to
+ -- ensure that gigi does not attempt an extra unnecessary copy.
+ -- (actually not just unnecessary but harmfully wrong in the case
+ -- of a controlled type, where gigi does not know how to do a copy).
+ -- To make up for a gcc 2.8.1 deficiency (???), we perform
+ -- the copy for array types if the constrained status of the
+ -- target type is different from that of the expression.
+
+ if Requires_Transient_Scope (Exptyp)
+ and then
+ (not Is_Array_Type (Exptyp)
+ or else Is_Constrained (Exptyp) = Is_Constrained (R_Type)
+ or else CW_Or_Controlled_Type (Utyp))
+ and then Nkind (Exp) = N_Function_Call
+ then
+ Set_By_Ref (N);
+
+ -- Remove side effects from the expression now so that other parts
+ -- of the expander do not have to reanalyze this node without this
+ -- optimization
+
+ Rewrite (Exp, Duplicate_Subexpr_No_Checks (Exp));
+
+ -- For controlled types, do the allocation on the secondary stack
+ -- manually in order to call adjust at the right time:
+
+ -- type Anon1 is access R_Type;
+ -- for Anon1'Storage_pool use ss_pool;
+ -- Anon2 : anon1 := new R_Type'(expr);
+ -- return Anon2.all;
+
+ -- We do the same for classwide types that are not potentially
+ -- controlled (by the virtue of restriction No_Finalization) because
+ -- gigi is not able to properly allocate class-wide types.
+
+ elsif CW_Or_Controlled_Type (Utyp) then
+ declare
+ Loc : constant Source_Ptr := Sloc (N);
+ Temp : constant Entity_Id :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_Internal_Name ('R'));
+ Acc_Typ : constant Entity_Id :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_Internal_Name ('A'));
+ Alloc_Node : Node_Id;
+
+ begin
+ Set_Ekind (Acc_Typ, E_Access_Type);
+
+ Set_Associated_Storage_Pool (Acc_Typ, RTE (RE_SS_Pool));
+
+ Alloc_Node :=
+ Make_Allocator (Loc,
+ Expression =>
+ Make_Qualified_Expression (Loc,
+ Subtype_Mark => New_Reference_To (Etype (Exp), Loc),
+ Expression => Relocate_Node (Exp)));
+
+ Insert_List_Before_And_Analyze (N, New_List (
+ Make_Full_Type_Declaration (Loc,
+ Defining_Identifier => Acc_Typ,
+ Type_Definition =>
+ Make_Access_To_Object_Definition (Loc,
+ Subtype_Indication =>
+ New_Reference_To (R_Type, Loc))),
+
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Temp,
+ Object_Definition => New_Reference_To (Acc_Typ, Loc),
+ Expression => Alloc_Node)));
+
+ Rewrite (Exp,
+ Make_Explicit_Dereference (Loc,
+ Prefix => New_Reference_To (Temp, Loc)));
+
+ Analyze_And_Resolve (Exp, R_Type);
+ end;
+
+ -- Otherwise use the gigi mechanism to allocate result on the
+ -- secondary stack.
+
+ else
+ Set_Storage_Pool (N, RTE (RE_SS_Pool));
+
+ -- If we are generating code for the VM do not use
+ -- SS_Allocate since everything is heap-allocated anyway.
+
+ if VM_Target = No_VM then
+ Set_Procedure_To_Call (N, RTE (RE_SS_Allocate));
+ end if;
+ end if;
+ end if;
+
+ -- Implement the rules of 6.5(8-10), which require a tag check in the
+ -- case of a limited tagged return type, and tag reassignment for
+ -- nonlimited tagged results. These actions are needed when the return
+ -- type is a specific tagged type and the result expression is a
+ -- conversion or a formal parameter, because in that case the tag of the
+ -- expression might differ from the tag of the specific result type.
+
+ if Is_Tagged_Type (Utyp)
+ and then not Is_Class_Wide_Type (Utyp)
+ and then (Nkind_In (Exp, N_Type_Conversion,
+ N_Unchecked_Type_Conversion)
+ or else (Is_Entity_Name (Exp)
+ and then Ekind (Entity (Exp)) in Formal_Kind))
+ then
+ -- When the return type is limited, perform a check that the
+ -- tag of the result is the same as the tag of the return type.
+
+ if Is_Limited_Type (R_Type) then
+ Insert_Action (Exp,
+ Make_Raise_Constraint_Error (Loc,
+ Condition =>
+ Make_Op_Ne (Loc,
+ Left_Opnd =>
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr (Exp),
+ Selector_Name =>
+ New_Reference_To (First_Tag_Component (Utyp), Loc)),
+ Right_Opnd =>
+ Unchecked_Convert_To (RTE (RE_Tag),
+ New_Reference_To
+ (Node (First_Elmt
+ (Access_Disp_Table (Base_Type (Utyp)))),
+ Loc))),
+ Reason => CE_Tag_Check_Failed));
+
+ -- If the result type is a specific nonlimited tagged type, then we
+ -- have to ensure that the tag of the result is that of the result
+ -- type. This is handled by making a copy of the expression in the
+ -- case where it might have a different tag, namely when the
+ -- expression is a conversion or a formal parameter. We create a new
+ -- object of the result type and initialize it from the expression,
+ -- which will implicitly force the tag to be set appropriately.
+
+ else
+ declare
+ Result_Id : constant Entity_Id :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_Internal_Name ('R'));
+ Result_Exp : constant Node_Id :=
+ New_Reference_To (Result_Id, Loc);
+ Result_Obj : constant Node_Id :=
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Result_Id,
+ Object_Definition =>
+ New_Reference_To (R_Type, Loc),
+ Constant_Present => True,
+ Expression => Relocate_Node (Exp));
+
+ begin
+ Set_Assignment_OK (Result_Obj);
+ Insert_Action (Exp, Result_Obj);
+
+ Rewrite (Exp, Result_Exp);
+ Analyze_And_Resolve (Exp, R_Type);
+ end;
+ end if;
+
+ -- Ada 2005 (AI-344): If the result type is class-wide, then insert
+ -- a check that the level of the return expression's underlying type
+ -- is not deeper than the level of the master enclosing the function.
+ -- Always generate the check when the type of the return expression
+ -- is class-wide, when it's a type conversion, or when it's a formal
+ -- parameter. Otherwise, suppress the check in the case where the
+ -- return expression has a specific type whose level is known not to
+ -- be statically deeper than the function's result type.
+
+ -- Note: accessibility check is skipped in the VM case, since there
+ -- does not seem to be any practical way to implement this check.
+
+ elsif Ada_Version >= Ada_05
+ and then VM_Target = No_VM
+ and then Is_Class_Wide_Type (R_Type)
+ and then not Scope_Suppress (Accessibility_Check)
+ and then
+ (Is_Class_Wide_Type (Etype (Exp))
+ or else Nkind_In (Exp, N_Type_Conversion,
+ N_Unchecked_Type_Conversion)
+ or else (Is_Entity_Name (Exp)
+ and then Ekind (Entity (Exp)) in Formal_Kind)
+ or else Scope_Depth (Enclosing_Dynamic_Scope (Etype (Exp))) >
+ Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))
+ then
+ declare
+ Tag_Node : Node_Id;
+
+ begin
+ -- Ada 2005 (AI-251): In class-wide interface objects we displace
+ -- "this" to reference the base of the object --- required to get
+ -- access to the TSD of the object.
+
+ if Is_Class_Wide_Type (Etype (Exp))
+ and then Is_Interface (Etype (Exp))
+ and then Nkind (Exp) = N_Explicit_Dereference
+ then
+ Tag_Node :=
+ Make_Explicit_Dereference (Loc,
+ Unchecked_Convert_To (RTE (RE_Tag_Ptr),
+ Make_Function_Call (Loc,
+ Name => New_Reference_To (RTE (RE_Base_Address), Loc),
+ Parameter_Associations => New_List (
+ Unchecked_Convert_To (RTE (RE_Address),
+ Duplicate_Subexpr (Prefix (Exp)))))));
+ else
+ Tag_Node :=
+ Make_Attribute_Reference (Loc,
+ Prefix => Duplicate_Subexpr (Exp),
+ Attribute_Name => Name_Tag);
+ end if;
+
+ Insert_Action (Exp,
+ Make_Raise_Program_Error (Loc,
+ Condition =>
+ Make_Op_Gt (Loc,
+ Left_Opnd =>
+ Build_Get_Access_Level (Loc, Tag_Node),
+ Right_Opnd =>
+ Make_Integer_Literal (Loc,
+ Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))),
+ Reason => PE_Accessibility_Check_Failed));
+ end;
+ end if;
+ end Expand_Simple_Function_Return;
+
+ ------------------------------
+ -- Make_Tag_Ctrl_Assignment --
+ ------------------------------
+
+ function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is
+ Loc : constant Source_Ptr := Sloc (N);
+ L : constant Node_Id := Name (N);
+ T : constant Entity_Id := Underlying_Type (Etype (L));
+
+ Ctrl_Act : constant Boolean := Controlled_Type (T)
+ and then not No_Ctrl_Actions (N);
+
+ Save_Tag : constant Boolean := Is_Tagged_Type (T)
+ and then not No_Ctrl_Actions (N)
+ and then VM_Target = No_VM;
+ -- Tags are not saved and restored when VM_Target because VM tags are
+ -- represented implicitly in objects.
+
+ Res : List_Id;
+ Tag_Tmp : Entity_Id;
+
+ Prev_Tmp : Entity_Id;
+ Next_Tmp : Entity_Id;
+ Ctrl_Ref : Node_Id;
+
+ begin
+ Res := New_List;
+
+ -- Finalize the target of the assignment when controlled.
+ -- We have two exceptions here:
+
+ -- 1. If we are in an init proc since it is an initialization
+ -- more than an assignment
+
+ -- 2. If the left-hand side is a temporary that was not initialized
+ -- (or the parent part of a temporary since it is the case in
+ -- extension aggregates). Such a temporary does not come from
+ -- source. We must examine the original node for the prefix, because
+ -- it may be a component of an entry formal, in which case it has
+ -- been rewritten and does not appear to come from source either.
+
+ -- Case of init proc
+
+ if not Ctrl_Act then
+ null;
+
+ -- The left hand side is an uninitialized temporary
+
+ elsif Nkind (L) = N_Type_Conversion
+ and then Is_Entity_Name (Expression (L))
+ and then No_Initialization (Parent (Entity (Expression (L))))
+ then
+ null;
+ else
+ Append_List_To (Res,
+ Make_Final_Call (
+ Ref => Duplicate_Subexpr_No_Checks (L),
+ Typ => Etype (L),
+ With_Detach => New_Reference_To (Standard_False, Loc)));
+ end if;
+
+ -- Save the Tag in a local variable Tag_Tmp
+
+ if Save_Tag then
+ Tag_Tmp :=
+ Make_Defining_Identifier (Loc, New_Internal_Name ('A'));
+
+ Append_To (Res,
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Tag_Tmp,
+ Object_Definition => New_Reference_To (RTE (RE_Tag), Loc),
+ Expression =>
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr_No_Checks (L),
+ Selector_Name => New_Reference_To (First_Tag_Component (T),
+ Loc))));
+
+ -- Otherwise Tag_Tmp not used
+
+ else
+ Tag_Tmp := Empty;
+ end if;
+
+ if Ctrl_Act then
+ if VM_Target /= No_VM then
+
+ -- Cannot assign part of the object in a VM context, so instead
+ -- fallback to the previous mechanism, even though it is not
+ -- completely correct ???
+
+ -- Save the Finalization Pointers in local variables Prev_Tmp and
+ -- Next_Tmp. For objects with Has_Controlled_Component set, these
+ -- pointers are in the Record_Controller
+
+ Ctrl_Ref := Duplicate_Subexpr (L);
+
+ if Has_Controlled_Component (T) then
+ Ctrl_Ref :=
+ Make_Selected_Component (Loc,
+ Prefix => Ctrl_Ref,
+ Selector_Name =>
+ New_Reference_To (Controller_Component (T), Loc));
+ end if;
+
+ Prev_Tmp :=
+ Make_Defining_Identifier (Loc, New_Internal_Name ('B'));
+
+ Append_To (Res,
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Prev_Tmp,
+
+ Object_Definition =>
+ New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
+
+ Expression =>
+ Make_Selected_Component (Loc,
+ Prefix =>
+ Unchecked_Convert_To (RTE (RE_Finalizable), Ctrl_Ref),
+ Selector_Name => Make_Identifier (Loc, Name_Prev))));
+
+ Next_Tmp :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_Internal_Name ('C'));
+
+ Append_To (Res,
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Next_Tmp,
+
+ Object_Definition =>
+ New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
+
+ Expression =>
+ Make_Selected_Component (Loc,
+ Prefix =>
+ Unchecked_Convert_To (RTE (RE_Finalizable),
+ New_Copy_Tree (Ctrl_Ref)),
+ Selector_Name => Make_Identifier (Loc, Name_Next))));
+
+ -- Do the Assignment
+
+ Append_To (Res, Relocate_Node (N));
+
+ else
+ -- Regular (non VM) processing for controlled types and types with
+ -- controlled components
+
+ -- Variables of such types contain pointers used to chain them in
+ -- finalization lists, in addition to user data. These pointers
+ -- are specific to each object of the type, not to the value being
+ -- assigned.
+
+ -- Thus they need to be left intact during the assignment. We
+ -- achieve this by constructing a Storage_Array subtype, and by
+ -- overlaying objects of this type on the source and target of the
+ -- assignment. The assignment is then rewritten to assignments of
+ -- slices of these arrays, copying the user data, and leaving the
+ -- pointers untouched.
+
+ Controlled_Actions : declare
+ Prev_Ref : Node_Id;
+ -- A reference to the Prev component of the record controller
+
+ First_After_Root : Node_Id := Empty;
+ -- Index of first byte to be copied (used to skip
+ -- Root_Controlled in controlled objects).
+
+ Last_Before_Hole : Node_Id := Empty;
+ -- Index of last byte to be copied before outermost record
+ -- controller data.
+
+ Hole_Length : Node_Id := Empty;
+ -- Length of record controller data (Prev and Next pointers)
+
+ First_After_Hole : Node_Id := Empty;
+ -- Index of first byte to be copied after outermost record
+ -- controller data.
+
+ Expr, Source_Size : Node_Id;
+ Source_Actual_Subtype : Entity_Id;
+ -- Used for computation of the size of the data to be copied
+
+ Range_Type : Entity_Id;
+ Opaque_Type : Entity_Id;
+
+ function Build_Slice
+ (Rec : Entity_Id;
+ Lo : Node_Id;
+ Hi : Node_Id) return Node_Id;
+ -- Build and return a slice of an array of type S overlaid on
+ -- object Rec, with bounds specified by Lo and Hi. If either
+ -- bound is empty, a default of S'First (respectively S'Last)
+ -- is used.
+
+ -----------------
+ -- Build_Slice --
+ -----------------
+
+ function Build_Slice
+ (Rec : Node_Id;
+ Lo : Node_Id;
+ Hi : Node_Id) return Node_Id
+ is
+ Lo_Bound : Node_Id;
+ Hi_Bound : Node_Id;
+
+ Opaque : constant Node_Id :=
+ Unchecked_Convert_To (Opaque_Type,
+ Make_Attribute_Reference (Loc,
+ Prefix => Rec,
+ Attribute_Name => Name_Address));
+ -- Access value designating an opaque storage array of type
+ -- S overlaid on record Rec.
+
+ begin
+ -- Compute slice bounds using S'First (1) and S'Last as
+ -- default values when not specified by the caller.
+
+ if No (Lo) then
+ Lo_Bound := Make_Integer_Literal (Loc, 1);
+ else
+ Lo_Bound := Lo;
+ end if;
+
+ if No (Hi) then
+ Hi_Bound := Make_Attribute_Reference (Loc,
+ Prefix => New_Occurrence_Of (Range_Type, Loc),
+ Attribute_Name => Name_Last);
+ else
+ Hi_Bound := Hi;
+ end if;
+
+ return Make_Slice (Loc,
+ Prefix =>
+ Opaque,
+ Discrete_Range => Make_Range (Loc,
+ Lo_Bound, Hi_Bound));
+ end Build_Slice;
+
+ -- Start of processing for Controlled_Actions
+
+ begin
+ -- Create a constrained subtype of Storage_Array whose size
+ -- corresponds to the value being assigned.
+
+ -- subtype G is Storage_Offset range
+ -- 1 .. (Expr'Size + Storage_Unit - 1) / Storage_Unit
+
+ Expr := Duplicate_Subexpr_No_Checks (Expression (N));
+
+ if Nkind (Expr) = N_Qualified_Expression then
+ Expr := Expression (Expr);
+ end if;
+
+ Source_Actual_Subtype := Etype (Expr);
+
+ if Has_Discriminants (Source_Actual_Subtype)
+ and then not Is_Constrained (Source_Actual_Subtype)
+ then
+ Append_To (Res,
+ Build_Actual_Subtype (Source_Actual_Subtype, Expr));
+ Source_Actual_Subtype := Defining_Identifier (Last (Res));
+ end if;
+
+ Source_Size :=
+ Make_Op_Add (Loc,
+ Left_Opnd =>
+ Make_Attribute_Reference (Loc,
+ Prefix =>
+ New_Occurrence_Of (Source_Actual_Subtype, Loc),
+ Attribute_Name => Name_Size),
+ Right_Opnd =>
+ Make_Integer_Literal (Loc,
+ Intval => System_Storage_Unit - 1));
+
+ Source_Size :=
+ Make_Op_Divide (Loc,
+ Left_Opnd => Source_Size,
+ Right_Opnd =>
+ Make_Integer_Literal (Loc,
+ Intval => System_Storage_Unit));
+
+ Range_Type :=
+ Make_Defining_Identifier (Loc,
+ New_Internal_Name ('G'));
+
+ Append_To (Res,
+ Make_Subtype_Declaration (Loc,
+ Defining_Identifier => Range_Type,
+ Subtype_Indication =>
+ Make_Subtype_Indication (Loc,
+ Subtype_Mark =>
+ New_Reference_To (RTE (RE_Storage_Offset), Loc),
+ Constraint => Make_Range_Constraint (Loc,
+ Range_Expression =>
+ Make_Range (Loc,
+ Low_Bound => Make_Integer_Literal (Loc, 1),
+ High_Bound => Source_Size)))));
+
+ -- subtype S is Storage_Array (G)
+
+ Append_To (Res,
+ Make_Subtype_Declaration (Loc,
+ Defining_Identifier =>
+ Make_Defining_Identifier (Loc,
+ New_Internal_Name ('S')),
+ Subtype_Indication =>
+ Make_Subtype_Indication (Loc,
+ Subtype_Mark =>
+ New_Reference_To (RTE (RE_Storage_Array), Loc),
+ Constraint =>
+ Make_Index_Or_Discriminant_Constraint (Loc,
+ Constraints =>
+ New_List (New_Reference_To (Range_Type, Loc))))));
+
+ -- type A is access S
+
+ Opaque_Type :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_Internal_Name ('A'));
+
+ Append_To (Res,
+ Make_Full_Type_Declaration (Loc,
+ Defining_Identifier => Opaque_Type,
+ Type_Definition =>
+ Make_Access_To_Object_Definition (Loc,
+ Subtype_Indication =>
+ New_Occurrence_Of (
+ Defining_Identifier (Last (Res)), Loc))));
+
+ -- Generate appropriate slice assignments
+
+ First_After_Root := Make_Integer_Literal (Loc, 1);
+
+ -- For the case of a controlled object, skip the
+ -- Root_Controlled part.
+
+ if Is_Controlled (T) then
+ First_After_Root :=
+ Make_Op_Add (Loc,
+ First_After_Root,
+ Make_Op_Divide (Loc,
+ Make_Attribute_Reference (Loc,
+ Prefix =>
+ New_Occurrence_Of (RTE (RE_Root_Controlled), Loc),
+ Attribute_Name => Name_Size),
+ Make_Integer_Literal (Loc, System_Storage_Unit)));
+ end if;
+
+ -- For the case of a record with controlled components, skip
+ -- the Prev and Next components of the record controller.
+ -- These components constitute a 'hole' in the middle of the
+ -- data to be copied.
+
+ if Has_Controlled_Component (T) then
+ Prev_Ref :=
+ Make_Selected_Component (Loc,
+ Prefix =>
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr_No_Checks (L),
+ Selector_Name =>
+ New_Reference_To (Controller_Component (T), Loc)),
+ Selector_Name => Make_Identifier (Loc, Name_Prev));
+
+ -- Last index before hole: determined by position of
+ -- the _Controller.Prev component.
+
+ Last_Before_Hole :=
+ Make_Defining_Identifier (Loc,
+ New_Internal_Name ('L'));
+
+ Append_To (Res,
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Last_Before_Hole,
+ Object_Definition => New_Occurrence_Of (
+ RTE (RE_Storage_Offset), Loc),
+ Constant_Present => True,
+ Expression => Make_Op_Add (Loc,
+ Make_Attribute_Reference (Loc,
+ Prefix => Prev_Ref,
+ Attribute_Name => Name_Position),
+ Make_Attribute_Reference (Loc,
+ Prefix => New_Copy_Tree (Prefix (Prev_Ref)),
+ Attribute_Name => Name_Position))));
+
+ -- Hole length: size of the Prev and Next components
+
+ Hole_Length :=
+ Make_Op_Multiply (Loc,
+ Left_Opnd => Make_Integer_Literal (Loc, Uint_2),
+ Right_Opnd =>
+ Make_Op_Divide (Loc,
+ Left_Opnd =>
+ Make_Attribute_Reference (Loc,
+ Prefix => New_Copy_Tree (Prev_Ref),
+ Attribute_Name => Name_Size),
+ Right_Opnd =>
+ Make_Integer_Literal (Loc,
+ Intval => System_Storage_Unit)));
+
+ -- First index after hole
+
+ First_After_Hole :=
+ Make_Defining_Identifier (Loc,
+ New_Internal_Name ('F'));
+
+ Append_To (Res,
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => First_After_Hole,
+ Object_Definition => New_Occurrence_Of (
+ RTE (RE_Storage_Offset), Loc),
+ Constant_Present => True,
+ Expression =>
+ Make_Op_Add (Loc,
+ Left_Opnd =>
+ Make_Op_Add (Loc,
+ Left_Opnd =>
+ New_Occurrence_Of (Last_Before_Hole, Loc),
+ Right_Opnd => Hole_Length),
+ Right_Opnd => Make_Integer_Literal (Loc, 1))));
+
+ Last_Before_Hole :=
+ New_Occurrence_Of (Last_Before_Hole, Loc);
+ First_After_Hole :=
+ New_Occurrence_Of (First_After_Hole, Loc);
+ end if;
+
+ -- Assign the first slice (possibly skipping Root_Controlled,
+ -- up to the beginning of the record controller if present,
+ -- up to the end of the object if not).
+
+ Append_To (Res, Make_Assignment_Statement (Loc,
+ Name => Build_Slice (
+ Rec => Duplicate_Subexpr_No_Checks (L),
+ Lo => First_After_Root,
+ Hi => Last_Before_Hole),
+
+ Expression => Build_Slice (
+ Rec => Expression (N),
+ Lo => First_After_Root,
+ Hi => New_Copy_Tree (Last_Before_Hole))));
+
+ if Present (First_After_Hole) then
+
+ -- If a record controller is present, copy the second slice,
+ -- from right after the _Controller.Next component up to the
+ -- end of the object.
+
+ Append_To (Res, Make_Assignment_Statement (Loc,
+ Name => Build_Slice (
+ Rec => Duplicate_Subexpr_No_Checks (L),
+ Lo => First_After_Hole,
+ Hi => Empty),
+ Expression => Build_Slice (
+ Rec => Duplicate_Subexpr_No_Checks (Expression (N)),
+ Lo => New_Copy_Tree (First_After_Hole),
+ Hi => Empty)));
+ end if;
+ end Controlled_Actions;
+ end if;
+
+ else
+ Append_To (Res, Relocate_Node (N));
+ end if;
+
+ -- Restore the tag
+
+ if Save_Tag then
+ Append_To (Res,
+ Make_Assignment_Statement (Loc,
+ Name =>
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr_No_Checks (L),
+ Selector_Name => New_Reference_To (First_Tag_Component (T),
+ Loc)),
+ Expression => New_Reference_To (Tag_Tmp, Loc)));
+ end if;
+
+ if Ctrl_Act then
+ if VM_Target /= No_VM then
+ -- Restore the finalization pointers
+
+ Append_To (Res,
+ Make_Assignment_Statement (Loc,
+ Name =>
+ Make_Selected_Component (Loc,
+ Prefix =>
+ Unchecked_Convert_To (RTE (RE_Finalizable),
+ New_Copy_Tree (Ctrl_Ref)),
+ Selector_Name => Make_Identifier (Loc, Name_Prev)),
+ Expression => New_Reference_To (Prev_Tmp, Loc)));
+
+ Append_To (Res,
+ Make_Assignment_Statement (Loc,
+ Name =>
+ Make_Selected_Component (Loc,
+ Prefix =>
+ Unchecked_Convert_To (RTE (RE_Finalizable),
+ New_Copy_Tree (Ctrl_Ref)),
+ Selector_Name => Make_Identifier (Loc, Name_Next)),
+ Expression => New_Reference_To (Next_Tmp, Loc)));
+ end if;
+
+ -- Adjust the target after the assignment when controlled (not in the
+ -- init proc since it is an initialization more than an assignment).
+
+ Append_List_To (Res,
+ Make_Adjust_Call (
+ Ref => Duplicate_Subexpr_Move_Checks (L),
+ Typ => Etype (L),
+ Flist_Ref => New_Reference_To (RTE (RE_Global_Final_List), Loc),
+ With_Attach => Make_Integer_Literal (Loc, 0)));
+ end if;
+
+ return Res;
+
+ exception
+ -- Could use comment here ???
+
+ when RE_Not_Available =>
+ return Empty_List;
+ end Make_Tag_Ctrl_Assignment;
+
+end Exp_Ch5;