+++ /dev/null
------------------------------------------------------------------------------
--- --
--- GNAT COMPILER COMPONENTS --
--- --
--- E X P _ C H 5 --
--- --
--- B o d y --
--- --
--- $Revision: 1.4.10.1 $
--- --
--- Copyright (C) 1992-2001, Free Software Foundation, Inc. --
--- --
--- GNAT is free software; you can redistribute it and/or modify it under --
--- terms of the GNU General Public License as published by the Free Soft- --
--- ware Foundation; either version 2, or (at your option) any later ver- --
--- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
--- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
--- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
--- for more details. You should have received a copy of the GNU General --
--- Public License distributed with GNAT; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
--- --
--- GNAT was originally developed by the GNAT team at New York University. --
--- Extensive contributions were provided by Ada Core Technologies Inc. --
--- --
-------------------------------------------------------------------------------
-
-with Atree; use Atree;
-with Checks; use Checks;
-with Einfo; use Einfo;
-with Exp_Aggr; use Exp_Aggr;
-with Exp_Ch7; use Exp_Ch7;
-with Exp_Ch11; use Exp_Ch11;
-with Exp_Dbug; use Exp_Dbug;
-with Exp_Pakd; use Exp_Pakd;
-with Exp_Util; use Exp_Util;
-with Hostparm; use Hostparm;
-with Nlists; use Nlists;
-with Nmake; use Nmake;
-with Opt; use Opt;
-with Restrict; use Restrict;
-with Rtsfind; use Rtsfind;
-with Sinfo; use Sinfo;
-with Sem; use Sem;
-with Sem_Ch8; use Sem_Ch8;
-with Sem_Ch13; use Sem_Ch13;
-with Sem_Eval; use Sem_Eval;
-with Sem_Res; use Sem_Res;
-with Sem_Util; use Sem_Util;
-with Snames; use Snames;
-with Stand; use Stand;
-with 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 special cases and checks required for such assignments, including
- -- change of representation.
-
- function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id;
- -- Generate the necessary code for controlled and Tagged assignment,
- -- that is to say, finalization of the target before, adjustement of
- -- the target after and save and restore of the tag and finalization
- -- pointers which are not 'part of the value' and must not be changed
- -- upon assignment. N is the original Assignment node.
-
- ------------------------------
- -- 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.
-
- 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).
-
- function Possible_Unaligned_Slice (Arg : Node_Id) return Boolean;
- -- Returns True if Arg (either the left or right hand side of the
- -- assignment) is a slice that could be unaligned wrt the array type.
- -- This is true if Arg is a component of a packed record, or is
- -- a record component to which a component clause applies. This
- -- is a little pessimistic, but the result of an unnecessary
- -- decision that something is possibly unaligned is only to
- -- generate a front end loop, which is not so terrible.
- -- It would really be better if backend handled this ???
-
- ------------------------
- -- 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;
-
- ------------------------------
- -- Possible_Unaligned_Slice --
- ------------------------------
-
- function Possible_Unaligned_Slice (Arg : Node_Id) return Boolean is
- begin
- -- No issue if this is not a slice, or else strict alignment
- -- is not required in any case.
-
- if Nkind (Arg) /= N_Slice
- or else not Target_Strict_Alignment
- then
- return False;
- end if;
-
- -- No issue if the component type is a byte or byte aligned
-
- declare
- Array_Typ : constant Entity_Id := Etype (Arg);
- Comp_Typ : constant Entity_Id := Component_Type (Array_Typ);
- Pref : constant Node_Id := Prefix (Arg);
-
- begin
- if Known_Alignment (Array_Typ) then
- if Alignment (Array_Typ) = 1 then
- return False;
- end if;
-
- elsif Known_Component_Size (Array_Typ) then
- if Component_Size (Array_Typ) = 1 then
- return False;
- end if;
-
- elsif Known_Esize (Comp_Typ) then
- if Esize (Comp_Typ) <= System_Storage_Unit then
- return False;
- end if;
- end if;
-
- -- No issue if this is not a selected component
-
- if Nkind (Pref) /= N_Selected_Component then
- return False;
- end if;
-
- -- Else we test for a possibly unaligned component
-
- return
- Is_Packed (Etype (Pref))
- or else
- Present (Component_Clause (Entity (Selector_Name (Pref))));
- end;
- end Possible_Unaligned_Slice;
-
- -- Determine if Lhs, Rhs are formal arrays or non-local arrays
-
- Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs);
- Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs);
-
- Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs);
- Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs);
-
- -- Start of processing for Expand_Assign_Array
-
- begin
- -- Deal with length check, note that the length check is done with
- -- respect to the right hand side as given, not a possible underlying
- -- renamed object, since this would generate incorrect extra checks.
-
- Apply_Length_Check (Rhs, L_Type);
-
- -- We start by assuming that the move can be done in either
- -- direction, i.e. that the two sides are completely disjoint.
-
- Set_Forwards_OK (N, True);
- Set_Backwards_OK (N, True);
-
- -- Normally it is only the slice case that can lead to overlap,
- -- and explicit checks for slices are made below. But there is
- -- one case where the slice can be implicit and invisible to us
- -- and that is the case where we have a one dimensional array,
- -- and either both operands are parameters, or one is a parameter
- -- and the other is a global variable. In this case the parameter
- -- could be a slice that overlaps with the other parameter.
-
- -- Check for the case of slices requiring an explicit loop. Normally
- -- it is only the explicit slice cases that bother us, but in the
- -- case of one dimensional arrays, parameters can be slices that
- -- are passed by reference, so we can have aliasing for assignments
- -- from one parameter to another, or assignments between parameters
- -- and non-local variables.
-
- -- Note: overlap is never possible if there is a change of
- -- representation, so we can exclude this case
-
- -- In the case of compiling for the Java Virtual Machine,
- -- slices are always passed by making a copy, so we don't
- -- have to worry about overlap. We also want to prevent
- -- generation of "<" comparisons for array addresses,
- -- since that's a meaningless operation on the JVM.
-
- 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 Java_VM
- then
- Set_Forwards_OK (N, False);
- Set_Backwards_OK (N, False);
-
- -- Note: the bit-packed case is not worrisome here, since if
- -- we have a slice passed as a parameter, it is always aligned
- -- on a byte boundary, and if there are no explicit slices, the
- -- assignment can be performed directly.
- end if;
-
- -- We certainly must use a loop for change of representation
- -- and also we use the operand of the conversion on the right
- -- hand side as the effective right hand side (the component
- -- types must match in this situation).
-
- if Crep then
- Act_Rhs := Get_Referenced_Object (Rhs);
- R_Type := Get_Actual_Subtype (Act_Rhs);
- Loop_Required := True;
-
- -- 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;
-
- -- The only remaining cases involve slice assignments. If no slices
- -- are involved, then the assignment can definitely be handled by gigi.
- -- unless we have the parameter case mentioned above.
-
- elsif not L_Slice and not R_Slice then
-
- -- The following is temporary code??? It is not clear why it is
- -- necessary. For further investigation, look at the following
- -- short program which fails:
-
- -- 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;
-
- -- To deal with the above, we expand out if either of the operands
- -- is an explicit dereference to an unconstrained bit packed array.
-
- Temporary_Code : declare
- function Is_Deref_Of_UBP (Opnd : Node_Id) return Boolean;
- -- Function to perform required test for special case above
-
- function Is_Deref_Of_UBP (Opnd : Node_Id) return Boolean is
- P_Type : Entity_Id;
- Des_Type : Entity_Id;
-
- begin
- if Nkind (Opnd) /= N_Explicit_Dereference then
- return False;
- else
- P_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;
- end if;
- end Is_Deref_Of_UBP;
-
- -- Start of processing for temporary code
-
- begin
- if Is_Deref_Of_UBP (Lhs)
- or else
- Is_Deref_Of_UBP (Rhs)
- then
- Loop_Required := True;
-
- -- Normal case (will be only case when above temp code removed ???
-
- elsif Forwards_OK (N) then
- return;
- end if;
- end Temporary_Code;
-
- -- Gigi can always handle the assignment if the right side is a string
- -- literal (note that overlap is definitely impossible in this case).
-
- elsif Nkind (Rhs) = N_String_Literal then
- return;
-
- -- If either operand is bit packed, then we need a loop, since we
- -- can't be sure that the slice is byte aligned. Similarly, if either
- -- operand is a possibly unaligned slice, then we need a loop (since
- -- gigi cannot handle unaligned slices).
-
- elsif Is_Bit_Packed_Array (L_Type)
- or else Is_Bit_Packed_Array (R_Type)
- or else Possible_Unaligned_Slice (Lhs)
- or else Possible_Unaligned_Slice (Rhs)
- then
- Loop_Required := True;
-
- -- If we are not bit-packed, and we have only one slice, then no
- -- overlap is possible except in the parameter case, so we can let
- -- gigi handle things.
-
- elsif not (L_Slice and R_Slice) then
- if Forwards_OK (N) then
- return;
- end if;
- end if;
-
- -- Come here to compelete the analysis
-
- -- Loop_Required: Set to True if we know that a loop is required
- -- regardless of overlap considerations.
-
- -- Forwards_OK: Set to False if we already know that a forwards
- -- move is not safe, else set to True.
-
- -- Backwards_OK: Set to False if we already know that a backwards
- -- move is not safe, else set to True
-
- -- Our task at this stage is to complete the overlap analysis, which
- -- can result in possibly setting Forwards_OK or Backwards_OK to
- -- False, and then generating the final code, either by deciding
- -- that it is OK after all to let Gigi handle it, or by generating
- -- appropriate code in the front end.
-
- declare
- L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type));
- R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type));
-
- Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ);
- Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ);
- Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ);
- Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ);
-
- Act_L_Array : Node_Id;
- Act_R_Array : Node_Id;
-
- Cleft_Lo : Node_Id;
- Cright_Lo : Node_Id;
- Condition : Node_Id;
-
- Cresult : Compare_Result;
-
- begin
- -- Get the expressions for the arrays. If we are dealing with a
- -- private type, then convert to the underlying type. We can do
- -- direct assignments to an array that is a private type, but
- -- we cannot assign to elements of the array without this extra
- -- unchecked conversion.
-
- if Nkind (Act_Lhs) = N_Slice then
- Larray := Prefix (Act_Lhs);
- else
- Larray := Act_Lhs;
-
- if Is_Private_Type (Etype (Larray)) then
- Larray :=
- Unchecked_Convert_To
- (Underlying_Type (Etype (Larray)), Larray);
- end if;
- end if;
-
- if Nkind (Act_Rhs) = N_Slice then
- Rarray := Prefix (Act_Rhs);
- else
- Rarray := Act_Rhs;
-
- if Is_Private_Type (Etype (Rarray)) then
- Rarray :=
- Unchecked_Convert_To
- (Underlying_Type (Etype (Rarray)), Rarray);
- end if;
- end if;
-
- -- If both sides are slices, we must figure out whether
- -- it is safe to do the move in one direction or the other
- -- It is always safe if there is a change of representation
- -- since obviously two arrays with different representations
- -- cannot possibly overlap.
-
- if (not Crep) and L_Slice and R_Slice then
- Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs));
- Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs));
-
- -- If both left and right hand arrays are entity names, and
- -- refer to different entities, then we know that the move
- -- is safe (the two storage areas are completely disjoint).
-
- if Is_Entity_Name (Act_L_Array)
- and then Is_Entity_Name (Act_R_Array)
- and then Entity (Act_L_Array) /= Entity (Act_R_Array)
- then
- null;
-
- -- Otherwise, we assume the worst, which is that the two
- -- arrays are the same array. There is no need to check if
- -- we know that is the case, because if we don't know it,
- -- we still have to assume it!
-
- -- Generally if the same array is involved, then we have
- -- an overlapping case. We will have to really assume the
- -- worst (i.e. set neither of the OK flags) unless we can
- -- determine the lower or upper bounds at compile time and
- -- compare them.
-
- else
- Cresult := Compile_Time_Compare (Left_Lo, Right_Lo);
-
- if Cresult = Unknown then
- Cresult := Compile_Time_Compare (Left_Hi, Right_Hi);
- end if;
-
- case Cresult is
- when LT | LE | EQ => Set_Backwards_OK (N, False);
- when GT | GE => Set_Forwards_OK (N, False);
- when NE | Unknown => Set_Backwards_OK (N, False);
- Set_Forwards_OK (N, False);
- end case;
- end if;
- end if;
-
- -- If after that analysis, Forwards_OK is still True, and
- -- Loop_Required is False, meaning that we have not discovered
- -- some non-overlap reason for requiring a loop, then we can
- -- still let gigi handle it.
-
- if not Loop_Required then
- if Forwards_OK (N) then
- return;
-
- else
- null;
- -- Here is where a memmove would be appropriate ???
- end if;
- end if;
-
- -- At this stage we have to generate an explicit loop, and
- -- we have the following cases:
-
- -- Forwards_OK = True
-
- -- Rnn : right_index := right_index'First;
- -- for Lnn in left-index loop
- -- left (Lnn) := right (Rnn);
- -- Rnn := right_index'Succ (Rnn);
- -- end loop;
-
- -- Note: the above code MUST be analyzed with checks off,
- -- because otherwise the Succ could overflow. But in any
- -- case this is more efficient!
-
- -- Forwards_OK = False, Backwards_OK = True
-
- -- Rnn : right_index := right_index'Last;
- -- for Lnn in reverse left-index loop
- -- left (Lnn) := right (Rnn);
- -- Rnn := right_index'Pred (Rnn);
- -- end loop;
-
- -- Note: the above code MUST be analyzed with checks off,
- -- because otherwise the Pred could overflow. But in any
- -- case this is more efficient!
-
- -- Forwards_OK = Backwards_OK = False
-
- -- This only happens if we have the same array on each side. It is
- -- possible to create situations using overlays that violate this,
- -- but we simply do not promise to get this "right" in this case.
-
- -- There are two possible subcases. If the No_Implicit_Conditionals
- -- restriction is set, then we generate the following code:
-
- -- declare
- -- T : constant <operand-type> := rhs;
- -- begin
- -- lhs := T;
- -- end;
-
- -- If implicit conditionals are permitted, then we generate:
-
- -- if Left_Lo <= Right_Lo then
- -- <code for Forwards_OK = True above>
- -- else
- -- <code for Backwards_OK = True above>
- -- end if;
-
- -- Cases where either Forwards_OK or Backwards_OK is true
-
- if Forwards_OK (N) or else Backwards_OK (N) then
- Rewrite (N,
- Expand_Assign_Array_Loop
- (N, Larray, Rarray, L_Type, R_Type, Ndim,
- Rev => not Forwards_OK (N)));
-
- -- Case of both are false with No_Implicit_Conditionals
-
- elsif Restrictions (No_Implicit_Conditionals) then
- declare
- T : Entity_Id := Make_Defining_Identifier (Loc,
- Chars => Name_T);
-
- begin
- Rewrite (N,
- Make_Block_Statement (Loc,
- Declarations => New_List (
- Make_Object_Declaration (Loc,
- Defining_Identifier => T,
- Constant_Present => True,
- Object_Definition =>
- New_Occurrence_Of (Etype (Rhs), Loc),
- Expression => Relocate_Node (Rhs))),
-
- Handled_Statement_Sequence =>
- Make_Handled_Sequence_Of_Statements (Loc,
- Statements => New_List (
- Make_Assignment_Statement (Loc,
- Name => Relocate_Node (Lhs),
- Expression => New_Occurrence_Of (T, Loc))))));
- end;
-
- -- Case of both are false with implicit conditionals allowed
-
- else
- -- Before we generate this code, we must ensure that the
- -- left and right side array types are defined. They may
- -- be itypes, and we cannot let them be defined inside the
- -- if, since the first use in the then may not be executed.
-
- Ensure_Defined (L_Type, N);
- Ensure_Defined (R_Type, N);
-
- -- We normally compare addresses to find out which way round
- -- to do the loop, since this is realiable, and handles the
- -- cases of parameters, conversions etc. But we can't do that
- -- in the bit packed case or the Java VM case, because addresses
- -- don't work there.
-
- if not Is_Bit_Packed_Array (L_Type) and then not Java_VM then
- Condition :=
- Make_Op_Le (Loc,
- Left_Opnd =>
- Unchecked_Convert_To (RTE (RE_Integer_Address),
- Make_Attribute_Reference (Loc,
- Prefix =>
- Make_Indexed_Component (Loc,
- Prefix =>
- Duplicate_Subexpr (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 (Rarray, True),
- Expressions => New_List (
- Make_Attribute_Reference (Loc,
- Prefix =>
- New_Reference_To
- (R_Index_Typ, Loc),
- Attribute_Name => Name_First))),
- Attribute_Name => Name_Address)));
-
- -- For the bit packed and Java VM cases we use the bounds.
- -- That's OK, because we don't have to worry about parameters,
- -- since they cannot cause overlap. Perhaps we should worry
- -- about weird slice conversions ???
-
- else
- -- Copy the bounds and reset the Analyzed flag, because the
- -- bounds of the index type itself may be universal, and must
- -- must be reaanalyzed to acquire the proper type for Gigi.
-
- Cleft_Lo := New_Copy_Tree (Left_Lo);
- Cright_Lo := New_Copy_Tree (Right_Lo);
- Set_Analyzed (Cleft_Lo, False);
- Set_Analyzed (Cright_Lo, False);
-
- Condition :=
- Make_Op_Le (Loc,
- Left_Opnd => Cleft_Lo,
- Right_Opnd => Cright_Lo);
- end if;
-
- 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;
-
- Analyze (N, Suppress => All_Checks);
- end;
- 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 : List_Id := New_List;
- ExprR : List_Id := New_List;
-
- begin
- for J in 1 .. Ndim loop
- Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc));
- Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc));
- end loop;
-
- Assign :=
- Make_Assignment_Statement (Loc,
- Name =>
- Make_Indexed_Component (Loc,
- Prefix => Duplicate_Subexpr (Larray, Name_Req => True),
- Expressions => ExprL),
- Expression =>
- Make_Indexed_Component (Loc,
- Prefix => Duplicate_Subexpr (Rarray, Name_Req => True),
- Expressions => ExprR));
-
- -- Propagate the No_Ctrl_Actions flag to individual assignments
-
- Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N));
- end;
-
- -- Now construct the loop from the inside out, with the last subscript
- -- varying most rapidly. Note that Assign is first the raw assignment
- -- statement, and then subsequently the loop that wraps it up.
-
- for J in reverse 1 .. Ndim loop
- Assign :=
- Make_Block_Statement (Loc,
- Declarations => New_List (
- Make_Object_Declaration (Loc,
- Defining_Identifier => Rnn (J),
- Object_Definition =>
- New_Occurrence_Of (R_Index_Type (J), Loc),
- Expression =>
- Make_Attribute_Reference (Loc,
- Prefix => New_Occurrence_Of (R_Index_Type (J), Loc),
- Attribute_Name => F_Or_L))),
-
- Handled_Statement_Sequence =>
- Make_Handled_Sequence_Of_Statements (Loc,
- Statements => New_List (
- Make_Implicit_Loop_Statement (N,
- Iteration_Scheme =>
- Make_Iteration_Scheme (Loc,
- Loop_Parameter_Specification =>
- Make_Loop_Parameter_Specification (Loc,
- Defining_Identifier => Lnn (J),
- Reverse_Present => Rev,
- Discrete_Subtype_Definition =>
- New_Reference_To (L_Index_Type (J), Loc))),
-
- Statements => New_List (
- Assign,
-
- Make_Assignment_Statement (Loc,
- Name => New_Occurrence_Of (Rnn (J), Loc),
- Expression =>
- Make_Attribute_Reference (Loc,
- Prefix =>
- New_Occurrence_Of (R_Index_Type (J), Loc),
- Attribute_Name => S_Or_P,
- Expressions => New_List (
- New_Occurrence_Of (Rnn (J), Loc)))))))));
- end loop;
-
- return Assign;
- end Expand_Assign_Array_Loop;
-
- --------------------------
- -- Expand_Assign_Record --
- --------------------------
-
- -- The only processing required is in the change of representation
- -- case, where we must expand the assignment to a series of field
- -- by field assignments.
-
- procedure Expand_Assign_Record (N : Node_Id) is
- begin
- if not Change_Of_Representation (N) then
- return;
- end if;
-
- -- At this stage we know that the right hand side is a conversion
-
- declare
- Loc : constant Source_Ptr := Sloc (N);
- Lhs : constant Node_Id := Name (N);
- Rhs : constant Node_Id := Expression (Expression (N));
- R_Rec : constant Node_Id := Expression (Expression (N));
- R_Typ : constant Entity_Id := Base_Type (Etype (R_Rec));
- L_Typ : constant Entity_Id := Etype (Lhs);
- Decl : constant Node_Id := Declaration_Node (R_Typ);
- RDef : Node_Id;
- F : Entity_Id;
-
- function Find_Component
- (Typ : Entity_Id;
- Comp : Entity_Id)
- return Entity_Id;
- -- Find the component with the given name in the underlying record
- -- declaration for Typ. We need to use the actual entity because
- -- the type may be private and resolution by identifier alone would
- -- fail.
-
- function Make_Component_List_Assign (CL : Node_Id) return List_Id;
- -- Returns a sequence of statements to assign the components that
- -- are referenced in the given component list.
-
- function Make_Field_Assign (C : Entity_Id) return Node_Id;
- -- Given C, the entity for a discriminant or component, build
- -- an assignment for the corresponding field values.
-
- function Make_Field_Assigns (CI : List_Id) return List_Id;
- -- Given CI, a component items list, construct series of statements
- -- for fieldwise assignment of the corresponding components.
-
- --------------------
- -- Find_Component --
- --------------------
-
- function Find_Component
- (Typ : Entity_Id;
- Comp : Entity_Id)
- return Entity_Id
-
- is
- Utyp : constant Entity_Id := Underlying_Type (Typ);
- C : Entity_Id;
-
- begin
- C := First_Entity (Utyp);
-
- while Present (C) loop
- if Chars (C) = Chars (Comp) then
- return C;
- end if;
- Next_Entity (C);
- end loop;
-
- raise Program_Error;
- end Find_Component;
-
- --------------------------------
- -- Make_Component_List_Assign --
- --------------------------------
-
- function Make_Component_List_Assign (CL : Node_Id) return List_Id is
- CI : constant List_Id := Component_Items (CL);
- VP : constant Node_Id := Variant_Part (CL);
-
- Result : List_Id;
- Alts : List_Id;
- V : Node_Id;
- DC : Node_Id;
- DCH : List_Id;
-
- begin
- Result := Make_Field_Assigns (CI);
-
- if Present (VP) then
-
- V := First_Non_Pragma (Variants (VP));
- Alts := New_List;
- while Present (V) loop
-
- DCH := New_List;
- DC := First (Discrete_Choices (V));
- while Present (DC) loop
- Append_To (DCH, New_Copy_Tree (DC));
- Next (DC);
- end loop;
-
- Append_To (Alts,
- Make_Case_Statement_Alternative (Loc,
- Discrete_Choices => DCH,
- Statements =>
- Make_Component_List_Assign (Component_List (V))));
- Next_Non_Pragma (V);
- end loop;
-
- Append_To (Result,
- Make_Case_Statement (Loc,
- Expression =>
- Make_Selected_Component (Loc,
- Prefix => Duplicate_Subexpr (Rhs),
- Selector_Name =>
- Make_Identifier (Loc, Chars (Name (VP)))),
- Alternatives => Alts));
-
- end if;
-
- return Result;
- end Make_Component_List_Assign;
-
- -----------------------
- -- Make_Field_Assign --
- -----------------------
-
- function Make_Field_Assign (C : Entity_Id) return Node_Id is
- A : Node_Id;
-
- begin
- A :=
- Make_Assignment_Statement (Loc,
- Name =>
- Make_Selected_Component (Loc,
- Prefix => Duplicate_Subexpr (Lhs),
- Selector_Name =>
- New_Occurrence_Of (Find_Component (L_Typ, C), Loc)),
- Expression =>
- Make_Selected_Component (Loc,
- Prefix => Duplicate_Subexpr (Rhs),
- Selector_Name => New_Occurrence_Of (C, Loc)));
-
- -- Set Assignment_OK, so discriminants can be assigned
-
- Set_Assignment_OK (Name (A), True);
- return A;
- end Make_Field_Assign;
-
- ------------------------
- -- Make_Field_Assigns --
- ------------------------
-
- function Make_Field_Assigns (CI : List_Id) return List_Id is
- Item : Node_Id;
- Result : List_Id;
-
- begin
- Item := First (CI);
- Result := New_List;
-
- while Present (Item) loop
- if Nkind (Item) = N_Component_Declaration then
- Append_To
- (Result, Make_Field_Assign (Defining_Identifier (Item)));
- end if;
-
- Next (Item);
- end loop;
-
- return Result;
- end Make_Field_Assigns;
-
- -- Start of processing for Expand_Assign_Record
-
- begin
- -- Note that we use the base type for this processing. This results
- -- in some extra work in the constrained case, but the change of
- -- representation case is so unusual that it is not worth the effort.
-
- -- First copy the discriminants. This is done unconditionally. It
- -- is required in the unconstrained left side case, and also in the
- -- case where this assignment was constructed during the expansion
- -- of a type conversion (since initialization of discriminants is
- -- suppressed in this case). It is unnecessary but harmless in
- -- other cases.
-
- if Has_Discriminants (L_Typ) then
- F := First_Discriminant (R_Typ);
- while Present (F) loop
- Insert_Action (N, Make_Field_Assign (F));
- Next_Discriminant (F);
- end loop;
- end if;
-
- -- We know the underlying type is a record, but its current view
- -- may be private. We must retrieve the usable record declaration.
-
- if Nkind (Decl) = N_Private_Type_Declaration
- and then Present (Full_View (R_Typ))
- then
- RDef := Type_Definition (Declaration_Node (Full_View (R_Typ)));
- else
- RDef := Type_Definition (Decl);
- end if;
-
- if Nkind (RDef) = N_Record_Definition
- and then Present (Component_List (RDef))
- then
- Insert_Actions
- (N, Make_Component_List_Assign (Component_List (RDef)));
-
- Rewrite (N, Make_Null_Statement (Loc));
- end if;
-
- end;
- end Expand_Assign_Record;
-
- -----------------------------------
- -- Expand_N_Assignment_Statement --
- -----------------------------------
-
- -- For array types, deal with slice assignments and setting the flags
- -- to indicate if it can be statically determined which direction the
- -- move should go in. Also deal with generating length checks.
-
- procedure Expand_N_Assignment_Statement (N : Node_Id) is
- Loc : constant Source_Ptr := Sloc (N);
- Lhs : constant Node_Id := Name (N);
- Rhs : constant Node_Id := Expression (N);
- Typ : constant Entity_Id := Underlying_Type (Etype (Lhs));
- Exp : Node_Id;
-
- begin
- -- Check for a special case where a high level transformation is
- -- required. If we have either of:
-
- -- P.field := rhs;
- -- P (sub) := rhs;
-
- -- where P is a reference to a bit packed array, then we have to unwind
- -- the assignment. The exact meaning of being a reference to a bit
- -- packed array is as follows:
-
- -- An indexed component whose prefix is a bit packed array is a
- -- reference to a bit packed array.
-
- -- An indexed component or selected component whose prefix is a
- -- reference to a bit packed array is itself a reference ot a
- -- bit packed array.
-
- -- The required transformation is
-
- -- Tnn : prefix_type := P;
- -- Tnn.field := rhs;
- -- P := Tnn;
-
- -- or
-
- -- Tnn : prefix_type := P;
- -- Tnn (subscr) := rhs;
- -- P := Tnn;
-
- -- Since P is going to be evaluated more than once, any subscripts
- -- in P must have their evaluation forced.
-
- if (Nkind (Lhs) = N_Indexed_Component
- or else
- Nkind (Lhs) = N_Selected_Component)
- and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs))
- then
- declare
- BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs));
- BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr);
- Tnn : constant Entity_Id :=
- Make_Defining_Identifier (Loc,
- Chars => New_Internal_Name ('T'));
-
- begin
- -- Insert the post assignment first, because we want to copy
- -- the BPAR_Expr tree before it gets analyzed in the context
- -- of the pre assignment. Note that we do not analyze the
- -- post assignment yet (we cannot till we have completed the
- -- analysis of the pre assignment). As usual, the analysis
- -- of this post assignment will happen on its own when we
- -- "run into" it after finishing the current assignment.
-
- Insert_After (N,
- Make_Assignment_Statement (Loc,
- Name => New_Copy_Tree (BPAR_Expr),
- Expression => New_Occurrence_Of (Tnn, Loc)));
-
- -- At this stage BPAR_Expr is a reference to a bit packed
- -- array where the reference was not expanded in the original
- -- tree, since it was on the left side of an assignment. But
- -- in the pre-assignment statement (the object definition),
- -- BPAR_Expr will end up on the right hand side, and must be
- -- reexpanded. To achieve this, we reset the analyzed flag
- -- of all selected and indexed components down to the actual
- -- indexed component for the packed array.
-
- Exp := BPAR_Expr;
- loop
- Set_Analyzed (Exp, False);
-
- if Nkind (Exp) = N_Selected_Component
- or else
- Nkind (Exp) = N_Indexed_Component
- then
- Exp := Prefix (Exp);
- else
- exit;
- end if;
- end loop;
-
- -- Now we can insert and analyze the pre-assignment.
-
- -- If the right-hand side requires a transient scope, it has
- -- already been placed on the stack. However, the declaration is
- -- inserted in the tree outside of this scope, and must reflect
- -- the proper scope for its variable. This awkward bit is forced
- -- by the stricter scope discipline imposed by GCC 2.97.
-
- declare
- Uses_Transient_Scope : constant Boolean :=
- Scope_Is_Transient and then N = Node_To_Be_Wrapped;
-
- begin
- if Uses_Transient_Scope then
- New_Scope (Scope (Current_Scope));
- end if;
-
- Insert_Before_And_Analyze (N,
- Make_Object_Declaration (Loc,
- Defining_Identifier => Tnn,
- Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc),
- Expression => BPAR_Expr));
-
- if Uses_Transient_Scope then
- Pop_Scope;
- end if;
- end;
-
- -- Now fix up the original assignment and continue processing
-
- Rewrite (Prefix (Lhs),
- New_Occurrence_Of (Tnn, Loc));
- end;
- end if;
-
- -- When we have the appropriate type of aggregate in the
- -- expression (it has been determined during analysis of the
- -- aggregate by setting the delay flag), let's perform in place
- -- assignment and thus avoid creating a temporay.
-
- if Is_Delayed_Aggregate (Rhs) then
- Convert_Aggr_In_Assignment (N);
- Rewrite (N, Make_Null_Statement (Loc));
- Analyze (N);
- return;
- end if;
-
- -- Apply discriminant check if required. If Lhs is an access type
- -- to a designated type with discriminants, we must always check.
-
- if Has_Discriminants (Etype (Lhs)) then
-
- -- Skip discriminant check if change of representation. Will be
- -- done when the change of representation is expanded out.
-
- if not Change_Of_Representation (N) then
- Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs);
- end if;
-
- -- If the type is private without discriminants, and the full type
- -- has discriminants (necessarily with defaults) a check may still be
- -- necessary if the Lhs is aliased. The private determinants must be
- -- visible to build the discriminant constraints.
-
- elsif Is_Private_Type (Etype (Lhs))
- and then Has_Discriminants (Typ)
- and then Nkind (Lhs) = N_Explicit_Dereference
- then
- declare
- Lt : constant Entity_Id := Etype (Lhs);
- begin
- Set_Etype (Lhs, Typ);
- Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
- Apply_Discriminant_Check (Rhs, Typ, Lhs);
- Set_Etype (Lhs, Lt);
- end;
-
- -- If the Lhs has a private type with unknown discriminants, it
- -- may have a full view with discriminants, but those are nameable
- -- only in the underlying type, so convert the Rhs to it before
- -- potential checking.
-
- elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs)))
- and then Has_Discriminants (Typ)
- then
- Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
- Apply_Discriminant_Check (Rhs, Typ, Lhs);
-
- -- In the access type case, we need the same discriminant check,
- -- and also range checks if we have an access to constrained array.
-
- elsif Is_Access_Type (Etype (Lhs))
- and then Is_Constrained (Designated_Type (Etype (Lhs)))
- then
- if Has_Discriminants (Designated_Type (Etype (Lhs))) then
-
- -- Skip discriminant check if change of representation. Will be
- -- done when the change of representation is expanded out.
-
- if not Change_Of_Representation (N) then
- Apply_Discriminant_Check (Rhs, Etype (Lhs));
- end if;
-
- elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then
- Apply_Range_Check (Rhs, Etype (Lhs));
-
- if Is_Constrained (Etype (Lhs)) then
- Apply_Length_Check (Rhs, Etype (Lhs));
- end if;
-
- if Nkind (Rhs) = N_Allocator then
- declare
- Target_Typ : constant Entity_Id := Etype (Expression (Rhs));
- C_Es : Check_Result;
-
- begin
- C_Es :=
- Range_Check
- (Lhs,
- Target_Typ,
- Etype (Designated_Type (Etype (Lhs))));
-
- Insert_Range_Checks
- (C_Es,
- N,
- Target_Typ,
- Sloc (Lhs),
- Lhs);
- end;
- end if;
- end if;
-
- -- Apply range check for access type case
-
- elsif Is_Access_Type (Etype (Lhs))
- and then Nkind (Rhs) = N_Allocator
- and then Nkind (Expression (Rhs)) = N_Qualified_Expression
- then
- Analyze_And_Resolve (Expression (Rhs));
- Apply_Range_Check
- (Expression (Rhs), Designated_Type (Etype (Lhs)));
- end if;
-
- -- Case of assignment to a bit packed array element
-
- if Nkind (Lhs) = N_Indexed_Component
- and then Is_Bit_Packed_Array (Etype (Prefix (Lhs)))
- then
- Expand_Bit_Packed_Element_Set (N);
- return;
-
- -- Case of tagged type assignment
-
- elsif Is_Tagged_Type (Typ)
- or else (Controlled_Type (Typ) and then not Is_Array_Type (Typ))
- then
- Tagged_Case : declare
- L : List_Id := No_List;
- Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N);
-
- begin
- -- In the controlled case, we need to make sure that function
- -- calls are evaluated before finalizing the target. In all
- -- cases, it makes the expansion easier if the side-effects
- -- are removed first.
-
- Remove_Side_Effects (Lhs);
- Remove_Side_Effects (Rhs);
-
- -- Avoid recursion in the mechanism
-
- Set_Analyzed (N);
-
- -- If dispatching assignment, we need to dispatch to _assign
-
- if Is_Class_Wide_Type (Typ)
-
- -- If the type is tagged, we may as well use the predefined
- -- primitive assignment. This avoids inlining a lot of code
- -- and in the class-wide case, the assignment is replaced by
- -- a dispatch call to _assign. Note that this cannot be done
- -- when discriminant checks are locally suppressed (as in
- -- extension aggregate expansions) because otherwise the
- -- discriminant check will be performed within the _assign
- -- call.
-
- or else (Is_Tagged_Type (Typ)
- and then Chars (Current_Scope) /= Name_uAssign
- and then Expand_Ctrl_Actions
- and then not Discriminant_Checks_Suppressed (Empty))
- then
- -- Fetch the primitive op _assign and proper type to call
- -- it. Because of possible conflits between private and
- -- full view the proper type is fetched directly from the
- -- operation profile.
-
- declare
- Op : constant Entity_Id
- := Find_Prim_Op (Typ, Name_uAssign);
- F_Typ : Entity_Id := Etype (First_Formal (Op));
-
- begin
- -- If the assignment is dispatching, make sure to use the
- -- ??? where is rest of this comment ???
-
- if Is_Class_Wide_Type (Typ) then
- F_Typ := Class_Wide_Type (F_Typ);
- end if;
-
- L := New_List (
- Make_Procedure_Call_Statement (Loc,
- Name => New_Reference_To (Op, Loc),
- Parameter_Associations => New_List (
- Unchecked_Convert_To (F_Typ, Duplicate_Subexpr (Lhs)),
- Unchecked_Convert_To (F_Typ,
- Duplicate_Subexpr (Rhs)))));
- end;
-
- else
- L := Make_Tag_Ctrl_Assignment (N);
-
- -- We can't afford to have destructive Finalization Actions
- -- in the Self assignment case, so if the target and the
- -- source are not obviously different, code is generated to
- -- avoid the self assignment case
- --
- -- if lhs'address /= rhs'address then
- -- <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 in No_Run_Time mode, where we in any
- -- case exclude the possibility of finalization going on!
-
- if Expand_Ctrl_Actions and then not No_Run_Time then
- L := New_List (
- Make_Block_Statement (Loc,
- Handled_Statement_Sequence =>
- Make_Handled_Sequence_Of_Statements (Loc,
- Statements => L,
- Exception_Handlers => New_List (
- Make_Exception_Handler (Loc,
- Exception_Choices =>
- New_List (Make_Others_Choice (Loc)),
- Statements => New_List (
- Make_Raise_Program_Error (Loc)))))));
- end if;
- end if;
-
- Rewrite (N,
- Make_Block_Statement (Loc,
- Handled_Statement_Sequence =>
- Make_Handled_Sequence_Of_Statements (Loc, Statements => L)));
-
- -- If no restrictions on aborts, protect the whole assignement
- -- for controlled objects as per 9.8(11)
-
- if Controlled_Type (Typ)
- and then Expand_Ctrl_Actions
- and then Abort_Allowed
- then
- declare
- Blk : constant Entity_Id :=
- New_Internal_Entity (
- E_Block, Current_Scope, Sloc (N), 'B');
-
- begin
- Set_Scope (Blk, Current_Scope);
- Set_Etype (Blk, Standard_Void_Type);
- Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N)));
-
- Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer));
- Set_At_End_Proc (Handled_Statement_Sequence (N),
- New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc));
- Expand_At_End_Handler
- (Handled_Statement_Sequence (N), Blk);
- end;
- end if;
-
- Analyze (N);
- return;
- end Tagged_Case;
-
- -- Array types
-
- elsif Is_Array_Type (Typ) then
- declare
- Actual_Rhs : Node_Id := Rhs;
-
- begin
- while Nkind (Actual_Rhs) = N_Type_Conversion
- or else
- Nkind (Actual_Rhs) = N_Qualified_Expression
- loop
- Actual_Rhs := Expression (Actual_Rhs);
- end loop;
-
- Expand_Assign_Array (N, Actual_Rhs);
- return;
- end;
-
- -- Record types
-
- elsif Is_Record_Type (Typ) then
- Expand_Assign_Record (N);
- return;
-
- -- Scalar types. This is where we perform the processing related
- -- to the requirements of (RM 13.9.1(9-11)) concerning the handling
- -- of invalid scalar values.
-
- elsif Is_Scalar_Type (Typ) then
-
- -- Case where right side is known valid
-
- if Expr_Known_Valid (Rhs) then
-
- -- Here the right side is valid, so it is fine. The case to
- -- deal with is when the left side is a local variable reference
- -- whose value is not currently known to be valid. If this is
- -- the case, and the assignment appears in an unconditional
- -- context, then we can mark the left side as now being valid.
-
- if Is_Local_Variable_Reference (Lhs)
- and then not Is_Known_Valid (Entity (Lhs))
- and then In_Unconditional_Context (N)
- then
- Set_Is_Known_Valid (Entity (Lhs), True);
- end if;
-
- -- Case where right side may be invalid in the sense of the RM
- -- reference above. The RM does not require that we check for
- -- the validity on an assignment, but it does require that the
- -- assignment of an invalid value not cause erroneous behavior.
-
- -- The general approach in GNAT is to use the Is_Known_Valid flag
- -- to avoid the need for validity checking on assignments. However
- -- in some cases, we have to do validity checking in order to make
- -- sure that the setting of this flag is correct.
-
- else
- -- Validate right side if we are validating copies
-
- if Validity_Checks_On
- and then Validity_Check_Copies
- then
- Ensure_Valid (Rhs);
-
- -- We can propagate this to the left side where appropriate
-
- if Is_Local_Variable_Reference (Lhs)
- and then not Is_Known_Valid (Entity (Lhs))
- and then In_Unconditional_Context (N)
- then
- Set_Is_Known_Valid (Entity (Lhs), True);
- end if;
-
- -- Otherwise check to see what should be done
-
- -- If left side is a local variable, then we just set its
- -- flag to indicate that its value may no longer be valid,
- -- since we are copying a potentially invalid value.
-
- elsif Is_Local_Variable_Reference (Lhs) then
- Set_Is_Known_Valid (Entity (Lhs), False);
-
- -- Check for case of a non-local variable on the left side
- -- which is currently known to be valid. In this case, we
- -- simply ensure that the right side is valid. We only play
- -- the game of copying validity status for local variables,
- -- since we are doing this statically, not by tracing the
- -- full flow graph.
-
- elsif Is_Entity_Name (Lhs)
- and then Is_Known_Valid (Entity (Lhs))
- then
- -- Note that the Ensure_Valid call is ignored if the
- -- Validity_Checking mode is set to none so we do not
- -- need to worry about that case here.
-
- Ensure_Valid (Rhs);
-
- -- In all other cases, we can safely copy an invalid value
- -- without worrying about the status of the left side. Since
- -- it is not a variable reference it will not be considered
- -- as being known to be valid in any case.
-
- else
- null;
- end if;
- end if;
- end if;
-
- -- Defend against invalid subscripts on left side if we are in
- -- standard validity checking mode. No need to do this if we
- -- are checking all subscripts.
-
- if Validity_Checks_On
- and then Validity_Check_Default
- and then not Validity_Check_Subscripts
- then
- Check_Valid_Lvalue_Subscripts (Lhs);
- end if;
- 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);
-
- begin
- -- Check for the situation where we know at compile time which
- -- branch will be taken
-
- if Compile_Time_Known_Value (Expr) then
- declare
- Val : constant Uint := Expr_Value (Expr);
- Alt : Node_Id;
- Choice : Node_Id;
-
- begin
- Alt := First (Alternatives (N));
- Search : loop
- Choice := First (Discrete_Choices (Alt));
- while Present (Choice) loop
-
- -- Others choice, always matches
-
- if Nkind (Choice) = N_Others_Choice then
- exit Search;
-
- -- Range, check if value is in the range
-
- elsif Nkind (Choice) = N_Range then
- exit Search when
- Val >= Expr_Value (Low_Bound (Choice))
- and then
- Val <= Expr_Value (High_Bound (Choice));
-
- -- Choice is a subtype name. Note that we know it must
- -- be a static subtype, since otherwise it would have
- -- been diagnosed as illegal.
-
- elsif Is_Entity_Name (Choice)
- and then Is_Type (Entity (Choice))
- then
- exit when Is_In_Range (Expr, Etype (Choice));
-
- -- Choice is a subtype indication
-
- elsif Nkind (Choice) = N_Subtype_Indication then
- declare
- C : constant Node_Id := Constraint (Choice);
- R : constant Node_Id := Range_Expression (C);
-
- begin
- exit Search when
- Val >= Expr_Value (Low_Bound (R))
- and then
- Val <= Expr_Value (High_Bound (R));
- end;
-
- -- Choice is a simple expression
-
- else
- exit Search when Val = Expr_Value (Choice);
- end if;
-
- Next (Choice);
- end loop;
-
- Next (Alt);
- pragma Assert (Present (Alt));
- end loop Search;
-
- -- The above loop *must* terminate by finding a match, since
- -- we know the case statement is valid, and the value of the
- -- expression is known at compile time. When we fall out of
- -- the loop, Alt points to the alternative that we know will
- -- be selected at run time.
-
- -- Move the statements from this alternative after the case
- -- statement. They are already analyzed, so will be skipped
- -- by the analyzer.
-
- Insert_List_After (N, Statements (Alt));
-
- -- That leaves the case statement as a shell. The alternative
- -- that wlil be executed is reset to a null list. So now we can
- -- kill the entire case statement.
-
- Kill_Dead_Code (Expression (N));
- Kill_Dead_Code (Alternatives (N));
- Rewrite (N, Make_Null_Statement (Loc));
- end;
-
- -- Here if the choice is not determined at compile time
-
- -- 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 node laboriously, and of
- -- course we already know the list of choices that corresponds to the
- -- others choice (it's the list we are replacing!)
-
- else
- declare
- Altnode : constant Node_Id := Last (Alternatives (N));
- Others_Node : Node_Id;
-
- begin
- if Nkind (First (Discrete_Choices (Altnode)))
- /= N_Others_Choice
- then
- Others_Node := Make_Others_Choice (Sloc (Altnode));
- Set_Others_Discrete_Choices
- (Others_Node, Discrete_Choices (Altnode));
- Set_Discrete_Choices (Altnode, New_List (Others_Node));
- end if;
-
- -- If checks are on, ensure argument is valid (RM 5.4(13)). This
- -- is only done for case statements frpm in the source program.
- -- We don't just call Ensure_Valid here, because the requirement
- -- is more strenous than usual, in that it is required that
- -- Constraint_Error be raised.
-
- if Comes_From_Source (N)
- and then Validity_Checks_On
- and then Validity_Check_Default
- and then not Expr_Known_Valid (Expr)
- then
- Insert_Valid_Check (Expr);
- end if;
- end;
- end if;
- end Expand_N_Case_Statement;
-
- -----------------------------
- -- Expand_N_Exit_Statement --
- -----------------------------
-
- -- The only processing required is to deal with a possible C/Fortran
- -- boolean value used as the condition for the exit statement.
-
- procedure Expand_N_Exit_Statement (N : Node_Id) is
- begin
- Adjust_Condition (Condition (N));
- end Expand_N_Exit_Statement;
-
- -----------------------------
- -- Expand_N_Goto_Statement --
- -----------------------------
-
- -- Add poll before goto if polling active
-
- procedure Expand_N_Goto_Statement (N : Node_Id) is
- begin
- Generate_Poll_Call (N);
- end Expand_N_Goto_Statement;
-
- ---------------------------
- -- Expand_N_If_Statement --
- ---------------------------
-
- -- First we deal with the case of C and Fortran convention boolean
- -- values, with zero/non-zero semantics.
-
- -- Second, we deal with the obvious rewriting for the cases where the
- -- condition of the IF is known at compile time to be True or False.
-
- -- Third, we remove elsif parts which have non-empty Condition_Actions
- -- and rewrite as independent if statements. For example:
-
- -- if x then xs
- -- elsif y then ys
- -- ...
- -- end if;
-
- -- becomes
- --
- -- if x then xs
- -- else
- -- <<condition actions of y>>
- -- if y then ys
- -- ...
- -- end if;
- -- end if;
-
- -- This rewriting is needed if at least one elsif part has a non-empty
- -- Condition_Actions list. We also do the same processing if there is
- -- a constant condition in an elsif part (in conjunction with the first
- -- processing step mentioned above, for the recursive call made to deal
- -- with the created inner if, this deals with properly optimizing the
- -- cases of constant elsif conditions).
-
- procedure Expand_N_If_Statement (N : Node_Id) is
- Hed : Node_Id;
- E : Node_Id;
- New_If : Node_Id;
-
- begin
- Adjust_Condition (Condition (N));
-
- -- The following loop deals with constant conditions for the IF. We
- -- need a loop because as we eliminate False conditions, we grab the
- -- first elsif condition and use it as the primary condition.
-
- while Compile_Time_Known_Value (Condition (N)) loop
-
- -- If condition is True, we can simply rewrite the if statement
- -- now by replacing it by the series of then statements.
-
- if Is_True (Expr_Value (Condition (N))) then
-
- -- All the else parts can be killed
-
- Kill_Dead_Code (Elsif_Parts (N));
- Kill_Dead_Code (Else_Statements (N));
-
- Hed := Remove_Head (Then_Statements (N));
- Insert_List_After (N, Then_Statements (N));
- Rewrite (N, Hed);
- return;
-
- -- If condition is False, then we can delete the condition and
- -- the Then statements
-
- else
- -- We do not delete the condition if constant condition
- -- warnings are enabled, since otherwise we end up deleting
- -- the desired warning. Of course the backend will get rid
- -- of this True/False test anyway, so nothing is lost here.
-
- if not Constant_Condition_Warnings then
- Kill_Dead_Code (Condition (N));
- end if;
-
- Kill_Dead_Code (Then_Statements (N));
-
- -- If there are no elsif statements, then we simply replace
- -- the entire if statement by the sequence of else statements.
-
- if No (Elsif_Parts (N)) then
-
- if No (Else_Statements (N))
- or else Is_Empty_List (Else_Statements (N))
- then
- Rewrite (N,
- Make_Null_Statement (Sloc (N)));
-
- else
- Hed := Remove_Head (Else_Statements (N));
- Insert_List_After (N, Else_Statements (N));
- Rewrite (N, Hed);
- end if;
-
- return;
-
- -- If there are elsif statements, the first of them becomes
- -- the if/then section of the rebuilt if statement This is
- -- the case where we loop to reprocess this copied condition.
-
- else
- Hed := Remove_Head (Elsif_Parts (N));
- Insert_Actions (N, Condition_Actions (Hed));
- Set_Condition (N, Condition (Hed));
- Set_Then_Statements (N, Then_Statements (Hed));
-
- if Is_Empty_List (Elsif_Parts (N)) then
- Set_Elsif_Parts (N, No_List);
- end if;
- end if;
- end if;
- end loop;
-
- -- Loop through elsif parts, dealing with constant conditions and
- -- possible expression actions that are present.
-
- if Present (Elsif_Parts (N)) then
- E := First (Elsif_Parts (N));
- while Present (E) loop
- Adjust_Condition (Condition (E));
-
- -- If there are condition actions, then we rewrite the if
- -- statement as indicated above. We also do the same rewrite
- -- if the condition is True or False. The further processing
- -- of this constant condition is then done by the recursive
- -- call to expand the newly created if statement
-
- if Present (Condition_Actions (E))
- or else Compile_Time_Known_Value (Condition (E))
- then
- -- Note this is not an implicit if statement, since it is
- -- part of an explicit if statement in the source (or of an
- -- implicit if statement that has already been tested).
-
- New_If :=
- Make_If_Statement (Sloc (E),
- Condition => Condition (E),
- Then_Statements => Then_Statements (E),
- Elsif_Parts => No_List,
- Else_Statements => Else_Statements (N));
-
- -- Elsif parts for new if come from remaining elsif's of parent
-
- while Present (Next (E)) loop
- if No (Elsif_Parts (New_If)) then
- Set_Elsif_Parts (New_If, New_List);
- end if;
-
- Append (Remove_Next (E), Elsif_Parts (New_If));
- end loop;
-
- Set_Else_Statements (N, New_List (New_If));
-
- if Present (Condition_Actions (E)) then
- Insert_List_Before (New_If, Condition_Actions (E));
- end if;
-
- Remove (E);
-
- if Is_Empty_List (Elsif_Parts (N)) then
- Set_Elsif_Parts (N, No_List);
- end if;
-
- Analyze (New_If);
- return;
-
- -- No special processing for that elsif part, move to next
-
- else
- Next (E);
- end if;
- end loop;
- end if;
- end Expand_N_If_Statement;
-
- -----------------------------
- -- Expand_N_Loop_Statement --
- -----------------------------
-
- -- 1. Deal with while condition for C/Fortran boolean
- -- 2. Deal with loops with a non-standard enumeration type range
- -- 3. Deal with while loops where Condition_Actions is set
- -- 4. Insert polling call if required
-
- procedure Expand_N_Loop_Statement (N : Node_Id) is
- Loc : constant Source_Ptr := Sloc (N);
- Isc : constant Node_Id := Iteration_Scheme (N);
-
- begin
- if Present (Isc) then
- Adjust_Condition (Condition (Isc));
- end if;
-
- if Is_Non_Empty_List (Statements (N)) then
- Generate_Poll_Call (First (Statements (N)));
- end if;
-
- if No (Isc) then
- return;
- end if;
-
- -- Handle the case where we have a for loop with the range type being
- -- an enumeration type with non-standard representation. In this case
- -- we expand:
-
- -- for x in [reverse] a .. b loop
- -- ...
- -- end loop;
-
- -- to
-
- -- for xP in [reverse] integer
- -- range etype'Pos (a) .. etype'Pos (b) loop
- -- declare
- -- x : constant etype := Pos_To_Rep (xP);
- -- begin
- -- ...
- -- end;
- -- end loop;
-
- if Present (Loop_Parameter_Specification (Isc)) then
- declare
- LPS : constant Node_Id := Loop_Parameter_Specification (Isc);
- Loop_Id : constant Entity_Id := Defining_Identifier (LPS);
- Ltype : constant Entity_Id := Etype (Loop_Id);
- Btype : constant Entity_Id := Base_Type (Ltype);
- New_Id : Entity_Id;
- Lo, Hi : Node_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'));
-
- Lo := Type_Low_Bound (Ltype);
- Hi := Type_High_Bound (Ltype);
-
- 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 =>
- Make_Indexed_Component (Loc,
- Prefix =>
- New_Reference_To (Enum_Pos_To_Rep (Btype), Loc),
- Expressions => New_List (
- New_Reference_To (New_Id, Loc))))),
-
- Handled_Statement_Sequence =>
- Make_Handled_Sequence_Of_Statements (Loc,
- Statements => Statements (N)))),
-
- End_Label => End_Label (N)));
-
- Analyze (N);
- end;
-
- -- Second case, if we have a while loop with Condition_Actions set,
- -- then we change it into a plain loop:
-
- -- while C loop
- -- ...
- -- end loop;
-
- -- changed to:
-
- -- loop
- -- <<condition actions>>
- -- exit when not C;
- -- ...
- -- end loop
-
- elsif Present (Isc)
- and then Present (Condition_Actions (Isc))
- then
- declare
- ES : Node_Id;
-
- begin
- ES :=
- Make_Exit_Statement (Sloc (Condition (Isc)),
- Condition =>
- Make_Op_Not (Sloc (Condition (Isc)),
- Right_Opnd => Condition (Isc)));
-
- Prepend (ES, Statements (N));
- Insert_List_Before (ES, Condition_Actions (Isc));
-
- -- This is not an implicit loop, since it is generated in
- -- response to the loop statement being processed. If this
- -- is itself implicit, the restriction has already been
- -- checked. If not, it is an explicit loop.
-
- Rewrite (N,
- Make_Loop_Statement (Sloc (N),
- Identifier => Identifier (N),
- Statements => Statements (N),
- End_Label => End_Label (N)));
-
- Analyze (N);
- end;
- end if;
- end Expand_N_Loop_Statement;
-
- -------------------------------
- -- Expand_N_Return_Statement --
- -------------------------------
-
- procedure Expand_N_Return_Statement (N : Node_Id) is
- Loc : constant Source_Ptr := Sloc (N);
- Exp : constant Node_Id := Expression (N);
- Exptyp : Entity_Id;
- T : Entity_Id;
- Utyp : Entity_Id;
- Scope_Id : Entity_Id;
- Kind : Entity_Kind;
- Call : Node_Id;
- Acc_Stat : Node_Id;
- Goto_Stat : Node_Id;
- Lab_Node : Node_Id;
- Cur_Idx : Nat;
- Return_Type : Entity_Id;
- Result_Exp : Node_Id;
- Result_Id : Entity_Id;
- Result_Obj : Node_Id;
-
- begin
- -- Case where returned expression is present
-
- if Present (Exp) then
-
- -- Always normalize C/Fortran boolean result. This is not always
- -- necessary, but it seems a good idea to minimize the passing
- -- around of non-normalized values, and in any case this handles
- -- the processing of barrier functions for protected types, which
- -- turn the condition into a return statement.
-
- Exptyp := Etype (Exp);
-
- if Is_Boolean_Type (Exptyp)
- and then Nonzero_Is_True (Exptyp)
- then
- Adjust_Condition (Exp);
- Adjust_Result_Type (Exp, Exptyp);
- end if;
-
- -- Do validity check if enabled for returns
-
- if Validity_Checks_On
- and then Validity_Check_Returns
- then
- Ensure_Valid (Exp);
- end if;
- end if;
-
- -- Find relevant enclosing scope from which return is returning
-
- Cur_Idx := Scope_Stack.Last;
- loop
- Scope_Id := Scope_Stack.Table (Cur_Idx).Entity;
-
- if Ekind (Scope_Id) /= E_Block
- and then Ekind (Scope_Id) /= E_Loop
- then
- exit;
-
- else
- Cur_Idx := Cur_Idx - 1;
- pragma Assert (Cur_Idx >= 0);
- end if;
- end loop;
-
- if No (Exp) then
- Kind := Ekind (Scope_Id);
-
- -- If it is a return from procedures do no extra steps.
-
- if Kind = E_Procedure or else Kind = E_Generic_Procedure then
- return;
- end if;
-
- pragma Assert (Is_Entry (Scope_Id));
-
- -- Look at the enclosing block to see whether the return is from
- -- an accept statement or an entry body.
-
- for J in reverse 0 .. Cur_Idx loop
- Scope_Id := Scope_Stack.Table (J).Entity;
- exit when Is_Concurrent_Type (Scope_Id);
- end loop;
-
- -- If it is a return from accept statement it should be expanded
- -- as a call to RTS Complete_Rendezvous and a goto to the end of
- -- the accept body.
-
- -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
- -- Expand_N_Accept_Alternative in exp_ch9.adb)
-
- if Is_Task_Type (Scope_Id) then
-
- Call := (Make_Procedure_Call_Statement (Loc,
- Name => New_Reference_To
- (RTE (RE_Complete_Rendezvous), Loc)));
- Insert_Before (N, Call);
- -- why not insert actions here???
- Analyze (Call);
-
- Acc_Stat := Parent (N);
- while Nkind (Acc_Stat) /= N_Accept_Statement loop
- Acc_Stat := Parent (Acc_Stat);
- end loop;
-
- Lab_Node := Last (Statements
- (Handled_Statement_Sequence (Acc_Stat)));
-
- Goto_Stat := Make_Goto_Statement (Loc,
- Name => New_Occurrence_Of
- (Entity (Identifier (Lab_Node)), Loc));
-
- Set_Analyzed (Goto_Stat);
-
- Rewrite (N, Goto_Stat);
- Analyze (N);
-
- -- If it is a return from an entry body, put a Complete_Entry_Body
- -- call in front of the return.
-
- elsif Is_Protected_Type (Scope_Id) then
-
- Call :=
- Make_Procedure_Call_Statement (Loc,
- Name => New_Reference_To
- (RTE (RE_Complete_Entry_Body), Loc),
- Parameter_Associations => New_List
- (Make_Attribute_Reference (Loc,
- Prefix =>
- New_Reference_To
- (Object_Ref
- (Corresponding_Body (Parent (Scope_Id))),
- Loc),
- Attribute_Name => Name_Unchecked_Access)));
-
- Insert_Before (N, Call);
- Analyze (Call);
-
- end if;
-
- return;
- end if;
-
- T := Etype (Exp);
- Return_Type := Etype (Scope_Id);
- Utyp := Underlying_Type (Return_Type);
-
- -- Check the result expression of a scalar function against
- -- the subtype of the function by inserting a conversion.
- -- This conversion must eventually be performed for other
- -- classes of types, but for now it's only done for scalars.
- -- ???
-
- if Is_Scalar_Type (T) then
- Rewrite (Exp, Convert_To (Return_Type, Exp));
- Analyze (Exp);
- end if;
-
- -- Implement the rules of 6.5(8-10), which require a tag check in
- -- the case of a limited tagged return type, and tag reassignment
- -- for nonlimited tagged results. These actions are needed when
- -- the return type is a specific tagged type and the result
- -- expression is a conversion or a formal parameter, because in
- -- that case the tag of the expression might differ from the tag
- -- of the specific result type.
-
- if Is_Tagged_Type (Utyp)
- and then not Is_Class_Wide_Type (Utyp)
- and then (Nkind (Exp) = N_Type_Conversion
- or else Nkind (Exp) = N_Unchecked_Type_Conversion
- or else (Is_Entity_Name (Exp)
- and then Ekind (Entity (Exp)) in Formal_Kind))
- then
- -- When the return type is limited, perform a check that the
- -- tag of the result is the same as the tag of the return type.
-
- if Is_Limited_Type (Return_Type) then
- Insert_Action (Exp,
- Make_Raise_Constraint_Error (Loc,
- Condition =>
- Make_Op_Ne (Loc,
- Left_Opnd =>
- Make_Selected_Component (Loc,
- Prefix => Duplicate_Subexpr (Exp),
- Selector_Name =>
- New_Reference_To (Tag_Component (Utyp), Loc)),
- Right_Opnd =>
- Unchecked_Convert_To (RTE (RE_Tag),
- New_Reference_To
- (Access_Disp_Table (Base_Type (Utyp)), Loc)))));
-
- -- If the result type is a specific nonlimited tagged type,
- -- then we have to ensure that the tag of the result is that
- -- of the result type. This is handled by making a copy of the
- -- expression in the case where it might have a different tag,
- -- namely when the expression is a conversion or a formal
- -- parameter. We create a new object of the result type and
- -- initialize it from the expression, which will implicitly
- -- force the tag to be set appropriately.
-
- else
- Result_Id :=
- Make_Defining_Identifier (Loc, New_Internal_Name ('R'));
- Result_Exp := New_Reference_To (Result_Id, Loc);
-
- Result_Obj :=
- Make_Object_Declaration (Loc,
- Defining_Identifier => Result_Id,
- Object_Definition => New_Reference_To (Return_Type, Loc),
- Constant_Present => True,
- Expression => Relocate_Node (Exp));
-
- Set_Assignment_OK (Result_Obj);
- Insert_Action (Exp, Result_Obj);
-
- Rewrite (Exp, Result_Exp);
- Analyze_And_Resolve (Exp, Return_Type);
- end if;
- end if;
-
- -- Deal with returning variable length objects and controlled types
-
- -- Nothing to do if we are returning by reference, or this is not
- -- a type that requires special processing (indicated by the fact
- -- that it requires a cleanup scope for the secondary stack case)
-
- if Is_Return_By_Reference_Type (T)
- or else not Requires_Transient_Scope (Return_Type)
- then
- null;
-
- -- Case of secondary stack not used
-
- elsif Function_Returns_With_DSP (Scope_Id) then
-
- -- Here what we need to do is to always return by reference, since
- -- we will return with the stack pointer depressed. We may need to
- -- do a copy to a local temporary before doing this return.
-
- No_Secondary_Stack_Case : declare
- Local_Copy_Required : Boolean := False;
- -- Set to True if a local copy is required
-
- Copy_Ent : Entity_Id;
- -- Used for the target entity if a copy is required
-
- Decl : Node_Id;
- -- Declaration used to create copy if needed
-
- procedure Test_Copy_Required (Expr : Node_Id);
- -- Determines if Expr represents a return value for which a
- -- copy is required. More specifically, a copy is not required
- -- if Expr represents an object or component of an object that
- -- is either in the local subprogram frame, or is constant.
- -- If a copy is required, then Local_Copy_Required is set True.
-
- ------------------------
- -- Test_Copy_Required --
- ------------------------
-
- procedure Test_Copy_Required (Expr : Node_Id) is
- Ent : Entity_Id;
-
- begin
- -- If component, test prefix (object containing component)
-
- if Nkind (Expr) = N_Indexed_Component
- or else
- Nkind (Expr) = N_Selected_Component
- then
- Test_Copy_Required (Prefix (Expr));
- return;
-
- -- See if we have an entity name
-
- elsif Is_Entity_Name (Expr) then
- Ent := Entity (Expr);
-
- -- Constant entity is always OK, no copy required
-
- if Ekind (Ent) = E_Constant then
- return;
-
- -- No copy required for local variable
-
- elsif Ekind (Ent) = E_Variable
- and then Scope (Ent) = Current_Subprogram
- then
- return;
- end if;
- end if;
-
- -- All other cases require a copy
-
- Local_Copy_Required := True;
- end Test_Copy_Required;
-
- -- Start of processing for No_Secondary_Stack_Case
-
- begin
- -- No copy needed if result is from a function call for the
- -- same type with the same constrainedness (is the latter a
- -- necessary check, or could gigi produce the bounds ???).
- -- In this case the result is already being returned by
- -- reference with the stack pointer depressed.
-
- if Requires_Transient_Scope (T)
- and then Is_Constrained (T) = Is_Constrained (Return_Type)
- and then (Nkind (Exp) = N_Function_Call
- or else
- Nkind (Original_Node (Exp)) = N_Function_Call)
- then
- Set_By_Ref (N);
-
- -- We always need a local copy for a controlled type, since
- -- we are required to finalize the local value before return.
- -- The copy will automatically include the required finalize.
- -- Moreover, gigi cannot make this copy, since we need special
- -- processing to ensure proper behavior for finalization.
-
- -- Note: the reason we are returning with a depressed stack
- -- pointer in the controlled case (even if the type involved
- -- is constrained) is that we must make a local copy to deal
- -- properly with the requirement that the local result be
- -- finalized.
-
- elsif Controlled_Type (Utyp) then
- Copy_Ent :=
- Make_Defining_Identifier (Loc,
- Chars => New_Internal_Name ('R'));
-
- -- Build declaration to do the copy, and insert it, setting
- -- Assignment_OK, because we may be copying a limited type.
- -- In addition we set the special flag to inhibit finalize
- -- attachment if this is a controlled type (since this attach
- -- must be done by the caller, otherwise if we attach it here
- -- we will finalize the returned result prematurely).
-
- Decl :=
- Make_Object_Declaration (Loc,
- Defining_Identifier => Copy_Ent,
- Object_Definition => New_Occurrence_Of (Return_Type, Loc),
- Expression => Relocate_Node (Exp));
-
- Set_Assignment_OK (Decl);
- Set_Delay_Finalize_Attach (Decl);
- Insert_Action (N, Decl);
-
- -- Now the actual return uses the copied value
-
- Rewrite (Exp, New_Occurrence_Of (Copy_Ent, Loc));
- Analyze_And_Resolve (Exp, Return_Type);
-
- -- Since we have made the copy, gigi does not have to, so
- -- we set the By_Ref flag to prevent another copy being made.
-
- Set_By_Ref (N);
-
- -- Non-controlled cases
-
- else
- Test_Copy_Required (Exp);
-
- -- If a local copy is required, then gigi will make the
- -- copy, otherwise, we can return the result directly,
- -- so set By_Ref to suppress the gigi copy.
-
- if not Local_Copy_Required then
- Set_By_Ref (N);
- end if;
- end if;
- end No_Secondary_Stack_Case;
-
- -- Here if secondary stack is used
-
- else
- -- Make sure that no surrounding block will reclaim the
- -- secondary-stack on which we are going to put the result.
- -- Not only may this introduce secondary stack leaks but worse,
- -- if the reclamation is done too early, then the result we are
- -- returning may get clobbered. See example in 7417-003.
-
- declare
- S : Entity_Id := Current_Scope;
-
- begin
- while Ekind (S) = E_Block or else Ekind (S) = E_Loop loop
- Set_Sec_Stack_Needed_For_Return (S, True);
- S := Enclosing_Dynamic_Scope (S);
- end loop;
- end;
-
- -- Optimize the case where the result is from a function call for
- -- the same type with the same constrainedness (is the latter a
- -- necessary check, or could gigi produce the bounds ???). 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).
-
- if Requires_Transient_Scope (T)
- and then Is_Constrained (T) = Is_Constrained (Return_Type)
- and then (Nkind (Exp) = N_Function_Call
- or else Nkind (Original_Node (Exp)) = N_Function_Call)
- then
- Set_By_Ref (N);
-
- -- For controlled types, do the allocation on the sec-stack
- -- manually in order to call adjust at the right time
- -- type Anon1 is access Return_Type;
- -- for Anon1'Storage_pool use ss_pool;
- -- Anon2 : anon1 := new Return_Type'(expr);
- -- return Anon2.all;
-
- elsif Controlled_Type (Utyp) then
- declare
- Loc : constant Source_Ptr := Sloc (N);
- Temp : constant Entity_Id :=
- Make_Defining_Identifier (Loc,
- Chars => New_Internal_Name ('R'));
- Acc_Typ : constant Entity_Id :=
- Make_Defining_Identifier (Loc,
- Chars => New_Internal_Name ('A'));
- Alloc_Node : Node_Id;
-
- begin
- Set_Ekind (Acc_Typ, E_Access_Type);
-
- Set_Associated_Storage_Pool (Acc_Typ, RTE (RE_SS_Pool));
-
- Alloc_Node :=
- Make_Allocator (Loc,
- Expression =>
- Make_Qualified_Expression (Loc,
- Subtype_Mark => New_Reference_To (Etype (Exp), Loc),
- Expression => Relocate_Node (Exp)));
-
- Insert_List_Before_And_Analyze (N, New_List (
- Make_Full_Type_Declaration (Loc,
- Defining_Identifier => Acc_Typ,
- Type_Definition =>
- Make_Access_To_Object_Definition (Loc,
- Subtype_Indication =>
- New_Reference_To (Return_Type, Loc))),
-
- Make_Object_Declaration (Loc,
- Defining_Identifier => Temp,
- Object_Definition => New_Reference_To (Acc_Typ, Loc),
- Expression => Alloc_Node)));
-
- Rewrite (Exp,
- Make_Explicit_Dereference (Loc,
- Prefix => New_Reference_To (Temp, Loc)));
-
- Analyze_And_Resolve (Exp, Return_Type);
- end;
-
- -- Otherwise use the gigi mechanism to allocate result on the
- -- secondary stack.
-
- else
- Set_Storage_Pool (N, RTE (RE_SS_Pool));
-
- -- If we are generating code for the Java VM do not use
- -- SS_Allocate since everything is heap-allocated anyway.
-
- if not Java_VM then
- Set_Procedure_To_Call (N, RTE (RE_SS_Allocate));
- end if;
- end if;
- end if;
- end Expand_N_Return_Statement;
-
- ------------------------------
- -- Make_Tag_Ctrl_Assignment --
- ------------------------------
-
- function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is
- Loc : constant Source_Ptr := Sloc (N);
- L : constant Node_Id := Name (N);
- T : constant Entity_Id := Underlying_Type (Etype (L));
-
- Ctrl_Act : constant Boolean := Controlled_Type (T)
- and then not No_Ctrl_Actions (N);
-
- Save_Tag : constant Boolean := Is_Tagged_Type (T)
- and then not No_Ctrl_Actions (N)
- and then not Java_VM;
- -- Tags are not saved and restored when Java_VM because JVM tags
- -- are represented implicitly in objects.
-
- Res : List_Id;
- Tag_Tmp : Entity_Id;
- Prev_Tmp : Entity_Id;
- Next_Tmp : Entity_Id;
- Ctrl_Ref : Node_Id;
-
- 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.
-
- -- Init_Proc case
-
- 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;
-
- elsif Nkind (L) = N_Indexed_Component
- and then Is_Entity_Name (Original_Node (Prefix (L)))
- and then Is_Entry_Formal (Entity (Original_Node (Prefix (L))))
- then
- null;
-
- else
- Append_List_To (Res,
- Make_Final_Call (
- Ref => Duplicate_Subexpr (L),
- Typ => Etype (L),
- With_Detach => New_Reference_To (Standard_False, Loc)));
- end if;
-
- Next_Tmp := Make_Defining_Identifier (Loc, New_Internal_Name ('C'));
-
- -- Save the Tag in a local variable Tag_Tmp
-
- if Save_Tag then
- Tag_Tmp :=
- Make_Defining_Identifier (Loc, New_Internal_Name ('A'));
-
- Append_To (Res,
- Make_Object_Declaration (Loc,
- Defining_Identifier => Tag_Tmp,
- Object_Definition => New_Reference_To (RTE (RE_Tag), Loc),
- Expression =>
- Make_Selected_Component (Loc,
- Prefix => Duplicate_Subexpr (L),
- Selector_Name => New_Reference_To (Tag_Component (T), Loc))));
-
- -- Otherwise Tag_Tmp not used
-
- else
- Tag_Tmp := Empty;
- end if;
-
- -- Save the Finalization Pointers in local variables Prev_Tmp and
- -- Next_Tmp. For objects with Has_Controlled_Component set, these
- -- pointers are in the Record_Controller
-
- if Ctrl_Act then
- 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, New_Internal_Name ('C'));
-
- Append_To (Res,
- Make_Object_Declaration (Loc,
- Defining_Identifier => Next_Tmp,
-
- Object_Definition =>
- New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
-
- Expression =>
- Make_Selected_Component (Loc,
- Prefix =>
- Unchecked_Convert_To (RTE (RE_Finalizable),
- New_Copy_Tree (Ctrl_Ref)),
- Selector_Name => Make_Identifier (Loc, Name_Next))));
-
- -- If not controlled type, then Prev_Tmp and Ctrl_Ref unused
-
- else
- Prev_Tmp := Empty;
- Ctrl_Ref := Empty;
- end if;
-
- -- Do the Assignment
-
- Append_To (Res, Relocate_Node (N));
-
- -- Restore the Tag
-
- if Save_Tag then
- Append_To (Res,
- Make_Assignment_Statement (Loc,
- Name =>
- Make_Selected_Component (Loc,
- Prefix => Duplicate_Subexpr (L),
- Selector_Name => New_Reference_To (Tag_Component (T), Loc)),
- Expression => New_Reference_To (Tag_Tmp, Loc)));
- end if;
-
- -- Restore the finalization pointers
-
- if Ctrl_Act then
- Append_To (Res,
- Make_Assignment_Statement (Loc,
- Name =>
- Make_Selected_Component (Loc,
- Prefix =>
- Unchecked_Convert_To (RTE (RE_Finalizable),
- New_Copy_Tree (Ctrl_Ref)),
- Selector_Name => Make_Identifier (Loc, Name_Prev)),
- Expression => New_Reference_To (Prev_Tmp, Loc)));
-
- Append_To (Res,
- Make_Assignment_Statement (Loc,
- Name =>
- Make_Selected_Component (Loc,
- Prefix =>
- Unchecked_Convert_To (RTE (RE_Finalizable),
- New_Copy_Tree (Ctrl_Ref)),
- Selector_Name => Make_Identifier (Loc, Name_Next)),
- Expression => New_Reference_To (Next_Tmp, Loc)));
- end if;
-
- -- Adjust the target after the assignment when controlled. (not in
- -- the init_proc since it is an initialization more than an
- -- assignment)
-
- if Ctrl_Act then
- Append_List_To (Res,
- Make_Adjust_Call (
- Ref => Duplicate_Subexpr (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;
- end Make_Tag_Ctrl_Assignment;
-
-end Exp_Ch5;
projects / msp430-gcc.git / blobdiff