4776 lines
178 KiB
Ada
4776 lines
178 KiB
Ada
------------------------------------------------------------------------------
|
|
-- --
|
|
-- GNAT COMPILER COMPONENTS --
|
|
-- --
|
|
-- E X P _ C H 5 --
|
|
-- --
|
|
-- B o d y --
|
|
-- --
|
|
-- Copyright (C) 1992-2016, Free Software Foundation, Inc. --
|
|
-- --
|
|
-- GNAT is free software; you can redistribute it and/or modify it under --
|
|
-- terms of the GNU General Public License as published by the Free Soft- --
|
|
-- ware Foundation; either version 3, or (at your option) any later ver- --
|
|
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
|
|
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
|
|
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
|
|
-- for more details. You should have received a copy of the GNU General --
|
|
-- Public License distributed with GNAT; see file COPYING3. If not, go to --
|
|
-- http://www.gnu.org/licenses for a complete copy of the license. --
|
|
-- --
|
|
-- GNAT was originally developed by the GNAT team at New York University. --
|
|
-- Extensive contributions were provided by Ada Core Technologies Inc. --
|
|
-- --
|
|
------------------------------------------------------------------------------
|
|
|
|
with Aspects; use Aspects;
|
|
with Atree; use Atree;
|
|
with Checks; use Checks;
|
|
with Debug; use Debug;
|
|
with Einfo; use Einfo;
|
|
with Elists; use Elists;
|
|
with Errout; use Errout;
|
|
with Exp_Aggr; use Exp_Aggr;
|
|
with Exp_Ch6; use Exp_Ch6;
|
|
with Exp_Ch7; use Exp_Ch7;
|
|
with Exp_Ch11; use Exp_Ch11;
|
|
with Exp_Dbug; use Exp_Dbug;
|
|
with Exp_Pakd; use Exp_Pakd;
|
|
with Exp_Tss; use Exp_Tss;
|
|
with Exp_Util; use Exp_Util;
|
|
with Ghost; use Ghost;
|
|
with Inline; use Inline;
|
|
with Namet; use Namet;
|
|
with Nlists; use Nlists;
|
|
with Nmake; use Nmake;
|
|
with Opt; use Opt;
|
|
with Restrict; use Restrict;
|
|
with Rident; use Rident;
|
|
with Rtsfind; use Rtsfind;
|
|
with Sinfo; use Sinfo;
|
|
with Sem; use Sem;
|
|
with Sem_Aux; use Sem_Aux;
|
|
with Sem_Ch3; use Sem_Ch3;
|
|
with Sem_Ch8; use Sem_Ch8;
|
|
with Sem_Ch13; use Sem_Ch13;
|
|
with Sem_Eval; use Sem_Eval;
|
|
with Sem_Res; use Sem_Res;
|
|
with Sem_Util; use Sem_Util;
|
|
with Snames; use Snames;
|
|
with Stand; use Stand;
|
|
with Stringt; use Stringt;
|
|
with Tbuild; use Tbuild;
|
|
with Uintp; use Uintp;
|
|
with Validsw; use Validsw;
|
|
|
|
package body Exp_Ch5 is
|
|
|
|
procedure Build_Formal_Container_Iteration
|
|
(N : Node_Id;
|
|
Container : Entity_Id;
|
|
Cursor : Entity_Id;
|
|
Init : out Node_Id;
|
|
Advance : out Node_Id;
|
|
New_Loop : out Node_Id);
|
|
-- Utility to create declarations and loop statement for both forms
|
|
-- of formal container iterators.
|
|
|
|
function Change_Of_Representation (N : Node_Id) return Boolean;
|
|
-- Determine if the right hand side of assignment N is a type conversion
|
|
-- which requires a change of representation. Called only for the array
|
|
-- and record cases.
|
|
|
|
procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id);
|
|
-- N is an assignment which assigns an array value. This routine process
|
|
-- the various special cases and checks required for such assignments,
|
|
-- including change of representation. Rhs is normally simply the right
|
|
-- hand side of the assignment, except that if the right hand side is a
|
|
-- type conversion or a qualified expression, then the RHS is the actual
|
|
-- expression inside any such type conversions or qualifications.
|
|
|
|
function Expand_Assign_Array_Loop
|
|
(N : Node_Id;
|
|
Larray : Entity_Id;
|
|
Rarray : Entity_Id;
|
|
L_Type : Entity_Id;
|
|
R_Type : Entity_Id;
|
|
Ndim : Pos;
|
|
Rev : Boolean) return Node_Id;
|
|
-- N is an assignment statement which assigns an array value. This routine
|
|
-- expands the assignment into a loop (or nested loops for the case of a
|
|
-- multi-dimensional array) to do the assignment component by component.
|
|
-- Larray and Rarray are the entities of the actual arrays on the left
|
|
-- hand and right hand sides. L_Type and R_Type are the types of these
|
|
-- arrays (which may not be the same, due to either sliding, or to a
|
|
-- change of representation case). Ndim is the number of dimensions and
|
|
-- the parameter Rev indicates if the loops run normally (Rev = False),
|
|
-- or reversed (Rev = True). The value returned is the constructed
|
|
-- loop statement. Auxiliary declarations are inserted before node N
|
|
-- using the standard Insert_Actions mechanism.
|
|
|
|
procedure Expand_Assign_Record (N : Node_Id);
|
|
-- N is an assignment of an untagged record value. This routine handles
|
|
-- the case where the assignment must be made component by component,
|
|
-- either because the target is not byte aligned, or there is a change
|
|
-- of representation, or when we have a tagged type with a representation
|
|
-- clause (this last case is required because holes in the tagged type
|
|
-- might be filled with components from child types).
|
|
|
|
procedure Expand_Formal_Container_Loop (N : Node_Id);
|
|
-- Use the primitives specified in an Iterable aspect to expand a loop
|
|
-- over a so-called formal container, primarily for SPARK usage.
|
|
|
|
procedure Expand_Formal_Container_Element_Loop (N : Node_Id);
|
|
-- Same, for an iterator of the form " For E of C". In this case the
|
|
-- iterator provides the name of the element, and the cursor is generated
|
|
-- internally.
|
|
|
|
procedure Expand_Iterator_Loop (N : Node_Id);
|
|
-- Expand loop over arrays and containers that uses the form "for X of C"
|
|
-- with an optional subtype mark, or "for Y in C".
|
|
|
|
procedure Expand_Iterator_Loop_Over_Container
|
|
(N : Node_Id;
|
|
Isc : Node_Id;
|
|
I_Spec : Node_Id;
|
|
Container : Node_Id;
|
|
Container_Typ : Entity_Id);
|
|
-- Expand loop over containers that uses the form "for X of C" with an
|
|
-- optional subtype mark, or "for Y in C". Isc is the iteration scheme.
|
|
-- I_Spec is the iterator specification and Container is either the
|
|
-- Container (for OF) or the iterator (for IN).
|
|
|
|
procedure Expand_Predicated_Loop (N : Node_Id);
|
|
-- Expand for loop over predicated subtype
|
|
|
|
function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id;
|
|
-- Generate the necessary code for controlled and tagged assignment, that
|
|
-- is to say, finalization of the target before, adjustment of the target
|
|
-- after and save and restore of the tag and finalization pointers which
|
|
-- are not 'part of the value' and must not be changed upon assignment. N
|
|
-- is the original Assignment node.
|
|
|
|
--------------------------------------
|
|
-- Build_Formal_Container_iteration --
|
|
--------------------------------------
|
|
|
|
procedure Build_Formal_Container_Iteration
|
|
(N : Node_Id;
|
|
Container : Entity_Id;
|
|
Cursor : Entity_Id;
|
|
Init : out Node_Id;
|
|
Advance : out Node_Id;
|
|
New_Loop : out Node_Id)
|
|
is
|
|
Loc : constant Source_Ptr := Sloc (N);
|
|
Stats : constant List_Id := Statements (N);
|
|
Typ : constant Entity_Id := Base_Type (Etype (Container));
|
|
First_Op : constant Entity_Id :=
|
|
Get_Iterable_Type_Primitive (Typ, Name_First);
|
|
Next_Op : constant Entity_Id :=
|
|
Get_Iterable_Type_Primitive (Typ, Name_Next);
|
|
|
|
Has_Element_Op : constant Entity_Id :=
|
|
Get_Iterable_Type_Primitive (Typ, Name_Has_Element);
|
|
begin
|
|
-- Declaration for Cursor
|
|
|
|
Init :=
|
|
Make_Object_Declaration (Loc,
|
|
Defining_Identifier => Cursor,
|
|
Object_Definition => New_Occurrence_Of (Etype (First_Op), Loc),
|
|
Expression =>
|
|
Make_Function_Call (Loc,
|
|
Name => New_Occurrence_Of (First_Op, Loc),
|
|
Parameter_Associations => New_List (
|
|
New_Occurrence_Of (Container, Loc))));
|
|
|
|
-- Statement that advances cursor in loop
|
|
|
|
Advance :=
|
|
Make_Assignment_Statement (Loc,
|
|
Name => New_Occurrence_Of (Cursor, Loc),
|
|
Expression =>
|
|
Make_Function_Call (Loc,
|
|
Name => New_Occurrence_Of (Next_Op, Loc),
|
|
Parameter_Associations => New_List (
|
|
New_Occurrence_Of (Container, Loc),
|
|
New_Occurrence_Of (Cursor, Loc))));
|
|
|
|
-- Iterator is rewritten as a while_loop
|
|
|
|
New_Loop :=
|
|
Make_Loop_Statement (Loc,
|
|
Iteration_Scheme =>
|
|
Make_Iteration_Scheme (Loc,
|
|
Condition =>
|
|
Make_Function_Call (Loc,
|
|
Name => New_Occurrence_Of (Has_Element_Op, Loc),
|
|
Parameter_Associations => New_List (
|
|
New_Occurrence_Of (Container, Loc),
|
|
New_Occurrence_Of (Cursor, Loc)))),
|
|
Statements => Stats,
|
|
End_Label => Empty);
|
|
end Build_Formal_Container_Iteration;
|
|
|
|
------------------------------
|
|
-- 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 component 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
|
|
case Nkind (Exp) is
|
|
when N_Indexed_Component | N_Selected_Component | N_Slice =>
|
|
return Is_Non_Local_Array (Prefix (Exp));
|
|
|
|
when others =>
|
|
return
|
|
not (Is_Entity_Name (Exp)
|
|
and then Scope (Entity (Exp)) = Current_Scope);
|
|
end case;
|
|
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)))
|
|
then
|
|
Set_Forwards_OK (N, False);
|
|
Set_Backwards_OK (N, False);
|
|
|
|
-- Note: the bit-packed case is not worrisome here, since if we have
|
|
-- a slice passed as a parameter, it is always aligned on a byte
|
|
-- boundary, and if there are no explicit slices, the assignment
|
|
-- can be performed directly.
|
|
end if;
|
|
|
|
-- If either operand has an address clause clear Backwards_OK and
|
|
-- Forwards_OK, since we cannot tell if the operands overlap. We
|
|
-- exclude this treatment when Rhs is an aggregate, since we know
|
|
-- that overlap can't occur.
|
|
|
|
if (Has_Address_Clause (Lhs) and then Nkind (Rhs) /= N_Aggregate)
|
|
or else Has_Address_Clause (Rhs)
|
|
then
|
|
Set_Forwards_OK (N, False);
|
|
Set_Backwards_OK (N, False);
|
|
end if;
|
|
|
|
-- We certainly must use a loop for change of representation and also
|
|
-- we use the operand of the conversion on the right hand side as the
|
|
-- effective right hand side (the component types must match in this
|
|
-- situation).
|
|
|
|
if Crep then
|
|
Act_Rhs := Get_Referenced_Object (Rhs);
|
|
R_Type := Get_Actual_Subtype (Act_Rhs);
|
|
Loop_Required := True;
|
|
|
|
-- We require a loop if the left side is possibly bit unaligned
|
|
|
|
elsif Possible_Bit_Aligned_Component (Lhs)
|
|
or else
|
|
Possible_Bit_Aligned_Component (Rhs)
|
|
then
|
|
Loop_Required := True;
|
|
|
|
-- Arrays with controlled components are expanded into a loop to force
|
|
-- calls to Adjust at the component level.
|
|
|
|
elsif Has_Controlled_Component (L_Type) then
|
|
Loop_Required := True;
|
|
|
|
-- If object is atomic/VFA, we cannot tolerate a loop
|
|
|
|
elsif Is_Atomic_Or_VFA_Object (Act_Lhs)
|
|
or else
|
|
Is_Atomic_Or_VFA_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_Or_VFA (Component_Type (L_Type))
|
|
or else Is_Atomic_Or_VFA (Component_Type (R_Type))
|
|
then
|
|
Loop_Required := True;
|
|
|
|
-- Case where no slice is involved
|
|
|
|
elsif not L_Slice and not R_Slice then
|
|
|
|
-- The following code deals with the case of unconstrained bit packed
|
|
-- arrays. The problem is that the template for such arrays contains
|
|
-- the bounds of the actual source level array, but the copy of an
|
|
-- entire array requires the bounds of the underlying array. It would
|
|
-- be nice if the back end could take care of this, but right now it
|
|
-- does not know how, so if we have such a type, then we expand out
|
|
-- into a loop, which is inefficient but works correctly. If we don't
|
|
-- do this, we get the wrong length computed for the array to be
|
|
-- moved. The two cases we need to worry about are:
|
|
|
|
-- Explicit dereference of an unconstrained packed array type as in
|
|
-- the following example:
|
|
|
|
-- procedure C52 is
|
|
-- type BITS is array(INTEGER range <>) of BOOLEAN;
|
|
-- pragma PACK(BITS);
|
|
-- type A is access BITS;
|
|
-- P1,P2 : A;
|
|
-- begin
|
|
-- P1 := new BITS (1 .. 65_535);
|
|
-- P2 := new BITS (1 .. 65_535);
|
|
-- P2.ALL := P1.ALL;
|
|
-- end C52;
|
|
|
|
-- A formal parameter reference with an unconstrained bit array type
|
|
-- is the other case we need to worry about (here we assume the same
|
|
-- BITS type declared above):
|
|
|
|
-- procedure Write_All (File : out BITS; Contents : BITS);
|
|
-- begin
|
|
-- File.Storage := Contents;
|
|
-- end Write_All;
|
|
|
|
-- We expand to a loop in either of these two cases
|
|
|
|
-- Question for future thought. Another potentially more efficient
|
|
-- approach would be to create the actual subtype, and then do an
|
|
-- unchecked conversion to this actual subtype ???
|
|
|
|
Check_Unconstrained_Bit_Packed_Array : declare
|
|
|
|
function Is_UBPA_Reference (Opnd : Node_Id) return Boolean;
|
|
-- Function to perform required test for the first case, above
|
|
-- (dereference of an unconstrained bit packed array).
|
|
|
|
-----------------------
|
|
-- Is_UBPA_Reference --
|
|
-----------------------
|
|
|
|
function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is
|
|
Typ : constant Entity_Id := Underlying_Type (Etype (Opnd));
|
|
P_Type : Entity_Id;
|
|
Des_Type : Entity_Id;
|
|
|
|
begin
|
|
if Present (Packed_Array_Impl_Type (Typ))
|
|
and then Is_Array_Type (Packed_Array_Impl_Type (Typ))
|
|
and then not Is_Constrained (Packed_Array_Impl_Type (Typ))
|
|
then
|
|
return True;
|
|
|
|
elsif Nkind (Opnd) = N_Explicit_Dereference then
|
|
P_Type := Underlying_Type (Etype (Prefix (Opnd)));
|
|
|
|
if not Is_Access_Type (P_Type) then
|
|
return False;
|
|
|
|
else
|
|
Des_Type := Designated_Type (P_Type);
|
|
return
|
|
Is_Bit_Packed_Array (Des_Type)
|
|
and then not Is_Constrained (Des_Type);
|
|
end if;
|
|
|
|
else
|
|
return False;
|
|
end if;
|
|
end Is_UBPA_Reference;
|
|
|
|
-- Start of processing for Check_Unconstrained_Bit_Packed_Array
|
|
|
|
begin
|
|
if Is_UBPA_Reference (Lhs)
|
|
or else
|
|
Is_UBPA_Reference (Rhs)
|
|
then
|
|
Loop_Required := True;
|
|
|
|
-- Here if we do not have the case of a reference to a bit packed
|
|
-- unconstrained array case. In this case gigi can most certainly
|
|
-- handle the assignment if a forwards move is allowed.
|
|
|
|
-- (could it handle the backwards case also???)
|
|
|
|
elsif Forwards_OK (N) then
|
|
return;
|
|
end if;
|
|
end Check_Unconstrained_Bit_Packed_Array;
|
|
|
|
-- The back end can always handle the assignment if the right side is a
|
|
-- string literal (note that overlap is definitely impossible in this
|
|
-- case). If the type is packed, a string literal is always converted
|
|
-- into an aggregate, except in the case of a null slice, for which no
|
|
-- aggregate can be written. In that case, rewrite the assignment as a
|
|
-- null statement, a length check has already been emitted to verify
|
|
-- that the range of the left-hand side is empty.
|
|
|
|
-- Note that this code is not executed if we have an assignment of a
|
|
-- string literal to a non-bit aligned component of a record, a case
|
|
-- which cannot be handled by the backend.
|
|
|
|
elsif Nkind (Rhs) = N_String_Literal then
|
|
if String_Length (Strval (Rhs)) = 0
|
|
and then Is_Bit_Packed_Array (L_Type)
|
|
then
|
|
Rewrite (N, Make_Null_Statement (Loc));
|
|
Analyze (N);
|
|
end if;
|
|
|
|
return;
|
|
|
|
-- If either operand is bit packed, then we need a loop, since we can't
|
|
-- be sure that the slice is byte aligned. Similarly, if either operand
|
|
-- is a possibly unaligned slice, then we need a loop (since the back
|
|
-- end cannot handle unaligned slices).
|
|
|
|
elsif Is_Bit_Packed_Array (L_Type)
|
|
or else Is_Bit_Packed_Array (R_Type)
|
|
or else Is_Possibly_Unaligned_Slice (Lhs)
|
|
or else Is_Possibly_Unaligned_Slice (Rhs)
|
|
then
|
|
Loop_Required := True;
|
|
|
|
-- If we are not bit-packed, and we have only one slice, then no overlap
|
|
-- is possible except in the parameter case, so we can let the back end
|
|
-- handle things.
|
|
|
|
elsif not (L_Slice and R_Slice) then
|
|
if Forwards_OK (N) then
|
|
return;
|
|
end if;
|
|
end if;
|
|
|
|
-- If the right-hand side is a string literal, introduce a temporary for
|
|
-- it, for use in the generated loop that will follow.
|
|
|
|
if Nkind (Rhs) = N_String_Literal then
|
|
declare
|
|
Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Rhs);
|
|
Decl : Node_Id;
|
|
|
|
begin
|
|
Decl :=
|
|
Make_Object_Declaration (Loc,
|
|
Defining_Identifier => Temp,
|
|
Object_Definition => New_Occurrence_Of (L_Type, Loc),
|
|
Expression => Relocate_Node (Rhs));
|
|
|
|
Insert_Action (N, Decl);
|
|
Rewrite (Rhs, New_Occurrence_Of (Temp, Loc));
|
|
R_Type := Etype (Temp);
|
|
end;
|
|
end if;
|
|
|
|
-- Come here to complete the analysis
|
|
|
|
-- Loop_Required: Set to True if we know that a loop is required
|
|
-- regardless of overlap considerations.
|
|
|
|
-- Forwards_OK: Set to False if we already know that a forwards
|
|
-- move is not safe, else set to True.
|
|
|
|
-- Backwards_OK: Set to False if we already know that a backwards
|
|
-- move is not safe, else set to True
|
|
|
|
-- Our task at this stage is to complete the overlap analysis, which can
|
|
-- result in possibly setting Forwards_OK or Backwards_OK to False, and
|
|
-- then generating the final code, either by deciding that it is OK
|
|
-- after all to let Gigi handle it, or by generating appropriate code
|
|
-- in the front end.
|
|
|
|
declare
|
|
L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type));
|
|
R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type));
|
|
|
|
Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ);
|
|
Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ);
|
|
Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ);
|
|
Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ);
|
|
|
|
Act_L_Array : Node_Id;
|
|
Act_R_Array : Node_Id;
|
|
|
|
Cleft_Lo : Node_Id;
|
|
Cright_Lo : Node_Id;
|
|
Condition : Node_Id;
|
|
|
|
Cresult : Compare_Result;
|
|
|
|
begin
|
|
-- Get the expressions for the arrays. If we are dealing with a
|
|
-- private type, then convert to the underlying type. We can do
|
|
-- direct assignments to an array that is a private type, but we
|
|
-- cannot assign to elements of the array without this extra
|
|
-- unchecked conversion.
|
|
|
|
-- Note: We propagate Parent to the conversion nodes to generate
|
|
-- a well-formed subtree.
|
|
|
|
if Nkind (Act_Lhs) = N_Slice then
|
|
Larray := Prefix (Act_Lhs);
|
|
else
|
|
Larray := Act_Lhs;
|
|
|
|
if Is_Private_Type (Etype (Larray)) then
|
|
declare
|
|
Par : constant Node_Id := Parent (Larray);
|
|
begin
|
|
Larray :=
|
|
Unchecked_Convert_To
|
|
(Underlying_Type (Etype (Larray)), Larray);
|
|
Set_Parent (Larray, Par);
|
|
end;
|
|
end if;
|
|
end if;
|
|
|
|
if Nkind (Act_Rhs) = N_Slice then
|
|
Rarray := Prefix (Act_Rhs);
|
|
else
|
|
Rarray := Act_Rhs;
|
|
|
|
if Is_Private_Type (Etype (Rarray)) then
|
|
declare
|
|
Par : constant Node_Id := Parent (Rarray);
|
|
begin
|
|
Rarray :=
|
|
Unchecked_Convert_To
|
|
(Underlying_Type (Etype (Rarray)), Rarray);
|
|
Set_Parent (Rarray, Par);
|
|
end;
|
|
end if;
|
|
end if;
|
|
|
|
-- If both sides are slices, we must figure out whether it is safe
|
|
-- to do the move in one direction or the other. It is always safe
|
|
-- if there is a change of representation since obviously two arrays
|
|
-- with different representations cannot possibly overlap.
|
|
|
|
if (not Crep) and L_Slice and R_Slice then
|
|
Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs));
|
|
Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs));
|
|
|
|
-- If both left and right hand arrays are entity names, and refer
|
|
-- to different entities, then we know that the move is safe (the
|
|
-- two storage areas are completely disjoint).
|
|
|
|
if Is_Entity_Name (Act_L_Array)
|
|
and then Is_Entity_Name (Act_R_Array)
|
|
and then Entity (Act_L_Array) /= Entity (Act_R_Array)
|
|
then
|
|
null;
|
|
|
|
-- Otherwise, we assume the worst, which is that the two arrays
|
|
-- are the same array. There is no need to check if we know that
|
|
-- is the case, because if we don't know it, we still have to
|
|
-- assume it.
|
|
|
|
-- Generally if the same array is involved, then we have an
|
|
-- overlapping case. We will have to really assume the worst (i.e.
|
|
-- set neither of the OK flags) unless we can determine the lower
|
|
-- or upper bounds at compile time and compare them.
|
|
|
|
else
|
|
Cresult :=
|
|
Compile_Time_Compare
|
|
(Left_Lo, Right_Lo, Assume_Valid => True);
|
|
|
|
if Cresult = Unknown then
|
|
Cresult :=
|
|
Compile_Time_Compare
|
|
(Left_Hi, Right_Hi, Assume_Valid => True);
|
|
end if;
|
|
|
|
case Cresult is
|
|
when LT | LE | EQ => Set_Backwards_OK (N, False);
|
|
when GT | GE => Set_Forwards_OK (N, False);
|
|
when NE | Unknown => Set_Backwards_OK (N, False);
|
|
Set_Forwards_OK (N, False);
|
|
end case;
|
|
end if;
|
|
end if;
|
|
|
|
-- If after that analysis Loop_Required is False, meaning that we
|
|
-- have not discovered some non-overlap reason for requiring a loop,
|
|
-- then the outcome depends on the capabilities of the back end.
|
|
|
|
if not Loop_Required then
|
|
-- Assume the back end can deal with all cases of overlap by
|
|
-- falling back to memmove if it cannot use a more efficient
|
|
-- approach.
|
|
|
|
return;
|
|
end if;
|
|
|
|
-- At this stage we have to generate an explicit loop, and we have
|
|
-- the following cases:
|
|
|
|
-- Forwards_OK = True
|
|
|
|
-- Rnn : right_index := right_index'First;
|
|
-- for Lnn in left-index loop
|
|
-- left (Lnn) := right (Rnn);
|
|
-- Rnn := right_index'Succ (Rnn);
|
|
-- end loop;
|
|
|
|
-- Note: the above code MUST be analyzed with checks off, because
|
|
-- otherwise the Succ could overflow. But in any case this is more
|
|
-- efficient.
|
|
|
|
-- Forwards_OK = False, Backwards_OK = True
|
|
|
|
-- Rnn : right_index := right_index'Last;
|
|
-- for Lnn in reverse left-index loop
|
|
-- left (Lnn) := right (Rnn);
|
|
-- Rnn := right_index'Pred (Rnn);
|
|
-- end loop;
|
|
|
|
-- Note: the above code MUST be analyzed with checks off, because
|
|
-- otherwise the Pred could overflow. But in any case this is more
|
|
-- efficient.
|
|
|
|
-- Forwards_OK = Backwards_OK = False
|
|
|
|
-- This only happens if we have the same array on each side. It is
|
|
-- possible to create situations using overlays that violate this,
|
|
-- but we simply do not promise to get this "right" in this case.
|
|
|
|
-- There are two possible subcases. If the No_Implicit_Conditionals
|
|
-- restriction is set, then we generate the following code:
|
|
|
|
-- declare
|
|
-- T : constant <operand-type> := rhs;
|
|
-- begin
|
|
-- lhs := T;
|
|
-- end;
|
|
|
|
-- If implicit conditionals are permitted, then we generate:
|
|
|
|
-- if Left_Lo <= Right_Lo then
|
|
-- <code for Forwards_OK = True above>
|
|
-- else
|
|
-- <code for Backwards_OK = True above>
|
|
-- end if;
|
|
|
|
-- In order to detect possible aliasing, we examine the renamed
|
|
-- expression when the source or target is a renaming. However,
|
|
-- the renaming may be intended to capture an address that may be
|
|
-- affected by subsequent code, and therefore we must recover
|
|
-- the actual entity for the expansion that follows, not the
|
|
-- object it renames. In particular, if source or target designate
|
|
-- a portion of a dynamically allocated object, the pointer to it
|
|
-- may be reassigned but the renaming preserves the proper location.
|
|
|
|
if Is_Entity_Name (Rhs)
|
|
and then
|
|
Nkind (Parent (Entity (Rhs))) = N_Object_Renaming_Declaration
|
|
and then Nkind (Act_Rhs) = N_Slice
|
|
then
|
|
Rarray := Rhs;
|
|
end if;
|
|
|
|
if Is_Entity_Name (Lhs)
|
|
and then
|
|
Nkind (Parent (Entity (Lhs))) = N_Object_Renaming_Declaration
|
|
and then Nkind (Act_Lhs) = N_Slice
|
|
then
|
|
Larray := Lhs;
|
|
end if;
|
|
|
|
-- Cases where either Forwards_OK or Backwards_OK is true
|
|
|
|
if Forwards_OK (N) or else Backwards_OK (N) then
|
|
if Needs_Finalization (Component_Type (L_Type))
|
|
and then Base_Type (L_Type) = Base_Type (R_Type)
|
|
and then Ndim = 1
|
|
and then not No_Ctrl_Actions (N)
|
|
then
|
|
declare
|
|
Proc : constant Entity_Id :=
|
|
TSS (Base_Type (L_Type), TSS_Slice_Assign);
|
|
Actuals : List_Id;
|
|
|
|
begin
|
|
Apply_Dereference (Larray);
|
|
Apply_Dereference (Rarray);
|
|
Actuals := New_List (
|
|
Duplicate_Subexpr (Larray, Name_Req => True),
|
|
Duplicate_Subexpr (Rarray, Name_Req => True),
|
|
Duplicate_Subexpr (Left_Lo, Name_Req => True),
|
|
Duplicate_Subexpr (Left_Hi, Name_Req => True),
|
|
Duplicate_Subexpr (Right_Lo, Name_Req => True),
|
|
Duplicate_Subexpr (Right_Hi, Name_Req => True));
|
|
|
|
Append_To (Actuals,
|
|
New_Occurrence_Of (
|
|
Boolean_Literals (not Forwards_OK (N)), Loc));
|
|
|
|
Rewrite (N,
|
|
Make_Procedure_Call_Statement (Loc,
|
|
Name => New_Occurrence_Of (Proc, Loc),
|
|
Parameter_Associations => Actuals));
|
|
end;
|
|
|
|
else
|
|
Rewrite (N,
|
|
Expand_Assign_Array_Loop
|
|
(N, Larray, Rarray, L_Type, R_Type, Ndim,
|
|
Rev => not Forwards_OK (N)));
|
|
end if;
|
|
|
|
-- Case of both are false with No_Implicit_Conditionals
|
|
|
|
elsif Restriction_Active (No_Implicit_Conditionals) then
|
|
declare
|
|
T : constant Entity_Id :=
|
|
Make_Defining_Identifier (Loc, Chars => Name_T);
|
|
|
|
begin
|
|
Rewrite (N,
|
|
Make_Block_Statement (Loc,
|
|
Declarations => New_List (
|
|
Make_Object_Declaration (Loc,
|
|
Defining_Identifier => T,
|
|
Constant_Present => True,
|
|
Object_Definition =>
|
|
New_Occurrence_Of (Etype (Rhs), Loc),
|
|
Expression => Relocate_Node (Rhs))),
|
|
|
|
Handled_Statement_Sequence =>
|
|
Make_Handled_Sequence_Of_Statements (Loc,
|
|
Statements => New_List (
|
|
Make_Assignment_Statement (Loc,
|
|
Name => Relocate_Node (Lhs),
|
|
Expression => New_Occurrence_Of (T, Loc))))));
|
|
end;
|
|
|
|
-- Case of both are false with implicit conditionals allowed
|
|
|
|
else
|
|
-- Before we generate this code, we must ensure that the left and
|
|
-- right side array types are defined. They may be itypes, and we
|
|
-- cannot let them be defined inside the if, since the first use
|
|
-- in the then may not be executed.
|
|
|
|
Ensure_Defined (L_Type, N);
|
|
Ensure_Defined (R_Type, N);
|
|
|
|
-- We normally compare addresses to find out which way round to
|
|
-- do the loop, since this is reliable, and handles the cases of
|
|
-- parameters, conversions etc. But we can't do that in the bit
|
|
-- packed case, because addresses don't work there.
|
|
|
|
if not Is_Bit_Packed_Array (L_Type) 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_Occurrence_Of
|
|
(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_Occurrence_Of
|
|
(R_Index_Typ, Loc),
|
|
Attribute_Name => Name_First))),
|
|
Attribute_Name => Name_Address)));
|
|
|
|
-- For the bit packed and VM cases we use the bounds. That's OK,
|
|
-- because we don't have to worry about parameters, since they
|
|
-- cannot cause overlap. Perhaps we should worry about weird slice
|
|
-- conversions ???
|
|
|
|
else
|
|
-- Copy the bounds
|
|
|
|
Cleft_Lo := New_Copy_Tree (Left_Lo);
|
|
Cright_Lo := New_Copy_Tree (Right_Lo);
|
|
|
|
-- If the types do not match we add an implicit conversion
|
|
-- here to ensure proper match
|
|
|
|
if Etype (Left_Lo) /= Etype (Right_Lo) then
|
|
Cright_Lo :=
|
|
Unchecked_Convert_To (Etype (Left_Lo), Cright_Lo);
|
|
end if;
|
|
|
|
-- Reset the Analyzed flag, because the bounds of the index
|
|
-- type itself may be universal, and must must be reanalyzed
|
|
-- to acquire the proper type for the back end.
|
|
|
|
Set_Analyzed (Cleft_Lo, False);
|
|
Set_Analyzed (Cright_Lo, False);
|
|
|
|
Condition :=
|
|
Make_Op_Le (Loc,
|
|
Left_Opnd => Cleft_Lo,
|
|
Right_Opnd => Cright_Lo);
|
|
end if;
|
|
|
|
if Needs_Finalization (Component_Type (L_Type))
|
|
and then Base_Type (L_Type) = Base_Type (R_Type)
|
|
and then Ndim = 1
|
|
and then not No_Ctrl_Actions (N)
|
|
then
|
|
|
|
-- Call TSS procedure for array assignment, passing the
|
|
-- explicit bounds of right and left hand sides.
|
|
|
|
declare
|
|
Proc : constant Entity_Id :=
|
|
TSS (Base_Type (L_Type), TSS_Slice_Assign);
|
|
Actuals : List_Id;
|
|
|
|
begin
|
|
Apply_Dereference (Larray);
|
|
Apply_Dereference (Rarray);
|
|
Actuals := New_List (
|
|
Duplicate_Subexpr (Larray, Name_Req => True),
|
|
Duplicate_Subexpr (Rarray, Name_Req => True),
|
|
Duplicate_Subexpr (Left_Lo, Name_Req => True),
|
|
Duplicate_Subexpr (Left_Hi, Name_Req => True),
|
|
Duplicate_Subexpr (Right_Lo, Name_Req => True),
|
|
Duplicate_Subexpr (Right_Hi, Name_Req => True));
|
|
|
|
Append_To (Actuals,
|
|
Make_Op_Not (Loc,
|
|
Right_Opnd => Condition));
|
|
|
|
Rewrite (N,
|
|
Make_Procedure_Call_Statement (Loc,
|
|
Name => New_Occurrence_Of (Proc, Loc),
|
|
Parameter_Associations => Actuals));
|
|
end;
|
|
|
|
else
|
|
Rewrite (N,
|
|
Make_Implicit_If_Statement (N,
|
|
Condition => Condition,
|
|
|
|
Then_Statements => New_List (
|
|
Expand_Assign_Array_Loop
|
|
(N, Larray, Rarray, L_Type, R_Type, Ndim,
|
|
Rev => False)),
|
|
|
|
Else_Statements => New_List (
|
|
Expand_Assign_Array_Loop
|
|
(N, Larray, Rarray, L_Type, R_Type, Ndim,
|
|
Rev => True))));
|
|
end if;
|
|
end if;
|
|
|
|
Analyze (N, Suppress => All_Checks);
|
|
end;
|
|
|
|
exception
|
|
when RE_Not_Available =>
|
|
return;
|
|
end Expand_Assign_Array;
|
|
|
|
------------------------------
|
|
-- Expand_Assign_Array_Loop --
|
|
------------------------------
|
|
|
|
-- The following is an example of the loop generated for the case of a
|
|
-- two-dimensional array:
|
|
|
|
-- declare
|
|
-- R2b : Tm1X1 := 1;
|
|
-- begin
|
|
-- for L1b in 1 .. 100 loop
|
|
-- declare
|
|
-- R4b : Tm1X2 := 1;
|
|
-- begin
|
|
-- for L3b in 1 .. 100 loop
|
|
-- vm1 (L1b, L3b) := vm2 (R2b, R4b);
|
|
-- R4b := Tm1X2'succ(R4b);
|
|
-- end loop;
|
|
-- end;
|
|
-- R2b := Tm1X1'succ(R2b);
|
|
-- end loop;
|
|
-- end;
|
|
|
|
-- Here Rev is False, and Tm1Xn are the subscript types for the right hand
|
|
-- side. The declarations of R2b and R4b are inserted before the original
|
|
-- assignment statement.
|
|
|
|
function Expand_Assign_Array_Loop
|
|
(N : Node_Id;
|
|
Larray : Entity_Id;
|
|
Rarray : Entity_Id;
|
|
L_Type : Entity_Id;
|
|
R_Type : Entity_Id;
|
|
Ndim : Pos;
|
|
Rev : Boolean) return Node_Id
|
|
is
|
|
Loc : constant Source_Ptr := Sloc (N);
|
|
|
|
Lnn : array (1 .. Ndim) of Entity_Id;
|
|
Rnn : array (1 .. Ndim) of Entity_Id;
|
|
-- Entities used as subscripts on left and right sides
|
|
|
|
L_Index_Type : array (1 .. Ndim) of Entity_Id;
|
|
R_Index_Type : array (1 .. Ndim) of Entity_Id;
|
|
-- Left and right index types
|
|
|
|
Assign : Node_Id;
|
|
|
|
F_Or_L : Name_Id;
|
|
S_Or_P : Name_Id;
|
|
|
|
function Build_Step (J : Nat) return Node_Id;
|
|
-- The increment step for the index of the right-hand side is written
|
|
-- as an attribute reference (Succ or Pred). This function returns
|
|
-- the corresponding node, which is placed at the end of the loop body.
|
|
|
|
----------------
|
|
-- Build_Step --
|
|
----------------
|
|
|
|
function Build_Step (J : Nat) return Node_Id is
|
|
Step : Node_Id;
|
|
Lim : Name_Id;
|
|
|
|
begin
|
|
if Rev then
|
|
Lim := Name_First;
|
|
else
|
|
Lim := Name_Last;
|
|
end if;
|
|
|
|
Step :=
|
|
Make_Assignment_Statement (Loc,
|
|
Name => New_Occurrence_Of (Rnn (J), Loc),
|
|
Expression =>
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix =>
|
|
New_Occurrence_Of (R_Index_Type (J), Loc),
|
|
Attribute_Name => S_Or_P,
|
|
Expressions => New_List (
|
|
New_Occurrence_Of (Rnn (J), Loc))));
|
|
|
|
-- Note that on the last iteration of the loop, the index is increased
|
|
-- (or decreased) past the corresponding bound. This is consistent with
|
|
-- the C semantics of the back-end, where such an off-by-one value on a
|
|
-- dead index variable is OK. However, in CodePeer mode this leads to
|
|
-- spurious warnings, and thus we place a guard around the attribute
|
|
-- reference. For obvious reasons we only do this for CodePeer.
|
|
|
|
if CodePeer_Mode then
|
|
Step :=
|
|
Make_If_Statement (Loc,
|
|
Condition =>
|
|
Make_Op_Ne (Loc,
|
|
Left_Opnd => New_Occurrence_Of (Lnn (J), Loc),
|
|
Right_Opnd =>
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix => New_Occurrence_Of (L_Index_Type (J), Loc),
|
|
Attribute_Name => Lim)),
|
|
Then_Statements => New_List (Step));
|
|
end if;
|
|
|
|
return Step;
|
|
end Build_Step;
|
|
|
|
-- Start of processing for Expand_Assign_Array_Loop
|
|
|
|
begin
|
|
if Rev then
|
|
F_Or_L := Name_Last;
|
|
S_Or_P := Name_Pred;
|
|
else
|
|
F_Or_L := Name_First;
|
|
S_Or_P := Name_Succ;
|
|
end if;
|
|
|
|
-- Setup index types and subscript entities
|
|
|
|
declare
|
|
L_Index : Node_Id;
|
|
R_Index : Node_Id;
|
|
|
|
begin
|
|
L_Index := First_Index (L_Type);
|
|
R_Index := First_Index (R_Type);
|
|
|
|
for J in 1 .. Ndim loop
|
|
Lnn (J) := Make_Temporary (Loc, 'L');
|
|
Rnn (J) := Make_Temporary (Loc, 'R');
|
|
|
|
L_Index_Type (J) := Etype (L_Index);
|
|
R_Index_Type (J) := Etype (R_Index);
|
|
|
|
Next_Index (L_Index);
|
|
Next_Index (R_Index);
|
|
end loop;
|
|
end;
|
|
|
|
-- Now construct the assignment statement
|
|
|
|
declare
|
|
ExprL : constant List_Id := New_List;
|
|
ExprR : constant List_Id := New_List;
|
|
|
|
begin
|
|
for J in 1 .. Ndim loop
|
|
Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc));
|
|
Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc));
|
|
end loop;
|
|
|
|
Assign :=
|
|
Make_Assignment_Statement (Loc,
|
|
Name =>
|
|
Make_Indexed_Component (Loc,
|
|
Prefix => Duplicate_Subexpr (Larray, Name_Req => True),
|
|
Expressions => ExprL),
|
|
Expression =>
|
|
Make_Indexed_Component (Loc,
|
|
Prefix => Duplicate_Subexpr (Rarray, Name_Req => True),
|
|
Expressions => ExprR));
|
|
|
|
-- We set assignment OK, since there are some cases, e.g. in object
|
|
-- declarations, where we are actually assigning into a constant.
|
|
-- If there really is an illegality, it was caught long before now,
|
|
-- and was flagged when the original assignment was analyzed.
|
|
|
|
Set_Assignment_OK (Name (Assign));
|
|
|
|
-- Propagate the No_Ctrl_Actions flag to individual assignments
|
|
|
|
Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N));
|
|
end;
|
|
|
|
-- Now construct the loop from the inside out, with the last subscript
|
|
-- varying most rapidly. Note that Assign is first the raw assignment
|
|
-- statement, and then subsequently the loop that wraps it up.
|
|
|
|
for J in reverse 1 .. Ndim loop
|
|
Assign :=
|
|
Make_Block_Statement (Loc,
|
|
Declarations => New_List (
|
|
Make_Object_Declaration (Loc,
|
|
Defining_Identifier => Rnn (J),
|
|
Object_Definition =>
|
|
New_Occurrence_Of (R_Index_Type (J), Loc),
|
|
Expression =>
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix => New_Occurrence_Of (R_Index_Type (J), Loc),
|
|
Attribute_Name => F_Or_L))),
|
|
|
|
Handled_Statement_Sequence =>
|
|
Make_Handled_Sequence_Of_Statements (Loc,
|
|
Statements => New_List (
|
|
Make_Implicit_Loop_Statement (N,
|
|
Iteration_Scheme =>
|
|
Make_Iteration_Scheme (Loc,
|
|
Loop_Parameter_Specification =>
|
|
Make_Loop_Parameter_Specification (Loc,
|
|
Defining_Identifier => Lnn (J),
|
|
Reverse_Present => Rev,
|
|
Discrete_Subtype_Definition =>
|
|
New_Occurrence_Of (L_Index_Type (J), Loc))),
|
|
|
|
Statements => New_List (Assign, Build_Step (J))))));
|
|
end loop;
|
|
|
|
return Assign;
|
|
end Expand_Assign_Array_Loop;
|
|
|
|
--------------------------
|
|
-- Expand_Assign_Record --
|
|
--------------------------
|
|
|
|
procedure Expand_Assign_Record (N : Node_Id) is
|
|
Lhs : constant Node_Id := Name (N);
|
|
Rhs : Node_Id := Expression (N);
|
|
L_Typ : constant Entity_Id := Base_Type (Etype (Lhs));
|
|
|
|
begin
|
|
-- If change of representation, then extract the real right hand side
|
|
-- from the type conversion, and proceed with component-wise assignment,
|
|
-- since the two types are not the same as far as the back end is
|
|
-- concerned.
|
|
|
|
if Change_Of_Representation (N) then
|
|
Rhs := Expression (Rhs);
|
|
|
|
-- If this may be a case of a large bit aligned component, then proceed
|
|
-- with component-wise assignment, to avoid possible clobbering of other
|
|
-- components sharing bits in the first or last byte of the component to
|
|
-- be assigned.
|
|
|
|
elsif Possible_Bit_Aligned_Component (Lhs)
|
|
or
|
|
Possible_Bit_Aligned_Component (Rhs)
|
|
then
|
|
null;
|
|
|
|
-- If we have a tagged type that has a complete record representation
|
|
-- clause, we must do we must do component-wise assignments, since child
|
|
-- types may have used gaps for their components, and we might be
|
|
-- dealing with a view conversion.
|
|
|
|
elsif Is_Fully_Repped_Tagged_Type (L_Typ) then
|
|
null;
|
|
|
|
-- If neither condition met, then nothing special to do, the back end
|
|
-- can handle assignment of the entire component as a single entity.
|
|
|
|
else
|
|
return;
|
|
end if;
|
|
|
|
-- At this stage we know that we must do a component wise assignment
|
|
|
|
declare
|
|
Loc : constant Source_Ptr := Sloc (N);
|
|
R_Typ : constant Entity_Id := Base_Type (Etype (Rhs));
|
|
Decl : constant Node_Id := Declaration_Node (R_Typ);
|
|
RDef : Node_Id;
|
|
F : Entity_Id;
|
|
|
|
function Find_Component
|
|
(Typ : Entity_Id;
|
|
Comp : Entity_Id) return Entity_Id;
|
|
-- Find the component with the given name in the underlying record
|
|
-- declaration for Typ. We need to use the actual entity because the
|
|
-- type may be private and resolution by identifier alone would fail.
|
|
|
|
function Make_Component_List_Assign
|
|
(CL : Node_Id;
|
|
U_U : Boolean := False) return List_Id;
|
|
-- Returns a sequence of statements to assign the components that
|
|
-- are referenced in the given component list. The flag U_U is
|
|
-- used to force the usage of the inferred value of the variant
|
|
-- part expression as the switch for the generated case statement.
|
|
|
|
function Make_Field_Assign
|
|
(C : Entity_Id;
|
|
U_U : Boolean := False) return Node_Id;
|
|
-- Given C, the entity for a discriminant or component, build an
|
|
-- assignment for the corresponding field values. The flag U_U
|
|
-- signals the presence of an Unchecked_Union and forces the usage
|
|
-- of the inferred discriminant value of C as the right hand side
|
|
-- of the assignment.
|
|
|
|
function Make_Field_Assigns (CI : List_Id) return List_Id;
|
|
-- Given CI, a component items list, construct series of statements
|
|
-- for fieldwise assignment of the corresponding components.
|
|
|
|
--------------------
|
|
-- Find_Component --
|
|
--------------------
|
|
|
|
function Find_Component
|
|
(Typ : Entity_Id;
|
|
Comp : Entity_Id) return Entity_Id
|
|
is
|
|
Utyp : constant Entity_Id := Underlying_Type (Typ);
|
|
C : Entity_Id;
|
|
|
|
begin
|
|
C := First_Entity (Utyp);
|
|
while Present (C) loop
|
|
if Chars (C) = Chars (Comp) then
|
|
return C;
|
|
end if;
|
|
|
|
Next_Entity (C);
|
|
end loop;
|
|
|
|
raise Program_Error;
|
|
end Find_Component;
|
|
|
|
--------------------------------
|
|
-- Make_Component_List_Assign --
|
|
--------------------------------
|
|
|
|
function Make_Component_List_Assign
|
|
(CL : Node_Id;
|
|
U_U : Boolean := False) return List_Id
|
|
is
|
|
CI : constant List_Id := Component_Items (CL);
|
|
VP : constant Node_Id := Variant_Part (CL);
|
|
|
|
Alts : List_Id;
|
|
DC : Node_Id;
|
|
DCH : List_Id;
|
|
Expr : Node_Id;
|
|
Result : List_Id;
|
|
V : Node_Id;
|
|
|
|
begin
|
|
Result := Make_Field_Assigns (CI);
|
|
|
|
if Present (VP) then
|
|
V := First_Non_Pragma (Variants (VP));
|
|
Alts := New_List;
|
|
while Present (V) loop
|
|
DCH := New_List;
|
|
DC := First (Discrete_Choices (V));
|
|
while Present (DC) loop
|
|
Append_To (DCH, New_Copy_Tree (DC));
|
|
Next (DC);
|
|
end loop;
|
|
|
|
Append_To (Alts,
|
|
Make_Case_Statement_Alternative (Loc,
|
|
Discrete_Choices => DCH,
|
|
Statements =>
|
|
Make_Component_List_Assign (Component_List (V))));
|
|
Next_Non_Pragma (V);
|
|
end loop;
|
|
|
|
-- If we have an Unchecked_Union, use the value of the inferred
|
|
-- discriminant of the variant part expression as the switch
|
|
-- for the case statement. The case statement may later be
|
|
-- folded.
|
|
|
|
if U_U then
|
|
Expr :=
|
|
New_Copy (Get_Discriminant_Value (
|
|
Entity (Name (VP)),
|
|
Etype (Rhs),
|
|
Discriminant_Constraint (Etype (Rhs))));
|
|
else
|
|
Expr :=
|
|
Make_Selected_Component (Loc,
|
|
Prefix => Duplicate_Subexpr (Rhs),
|
|
Selector_Name =>
|
|
Make_Identifier (Loc, Chars (Name (VP))));
|
|
end if;
|
|
|
|
Append_To (Result,
|
|
Make_Case_Statement (Loc,
|
|
Expression => Expr,
|
|
Alternatives => Alts));
|
|
end if;
|
|
|
|
return Result;
|
|
end Make_Component_List_Assign;
|
|
|
|
-----------------------
|
|
-- Make_Field_Assign --
|
|
-----------------------
|
|
|
|
function Make_Field_Assign
|
|
(C : Entity_Id;
|
|
U_U : Boolean := False) return Node_Id
|
|
is
|
|
A : Node_Id;
|
|
Expr : Node_Id;
|
|
|
|
begin
|
|
-- In the case of an Unchecked_Union, use the discriminant
|
|
-- constraint value as on the right hand side of the assignment.
|
|
|
|
if U_U then
|
|
Expr :=
|
|
New_Copy (Get_Discriminant_Value (C,
|
|
Etype (Rhs),
|
|
Discriminant_Constraint (Etype (Rhs))));
|
|
else
|
|
Expr :=
|
|
Make_Selected_Component (Loc,
|
|
Prefix => Duplicate_Subexpr (Rhs),
|
|
Selector_Name => New_Occurrence_Of (C, Loc));
|
|
end if;
|
|
|
|
A :=
|
|
Make_Assignment_Statement (Loc,
|
|
Name =>
|
|
Make_Selected_Component (Loc,
|
|
Prefix => Duplicate_Subexpr (Lhs),
|
|
Selector_Name =>
|
|
New_Occurrence_Of (Find_Component (L_Typ, C), Loc)),
|
|
Expression => Expr);
|
|
|
|
-- Set Assignment_OK, so discriminants can be assigned
|
|
|
|
Set_Assignment_OK (Name (A), True);
|
|
|
|
if Componentwise_Assignment (N)
|
|
and then Nkind (Name (A)) = N_Selected_Component
|
|
and then Chars (Selector_Name (Name (A))) = Name_uParent
|
|
then
|
|
Set_Componentwise_Assignment (A);
|
|
end if;
|
|
|
|
return A;
|
|
end Make_Field_Assign;
|
|
|
|
------------------------
|
|
-- Make_Field_Assigns --
|
|
------------------------
|
|
|
|
function Make_Field_Assigns (CI : List_Id) return List_Id is
|
|
Item : Node_Id;
|
|
Result : List_Id;
|
|
|
|
begin
|
|
Item := First (CI);
|
|
Result := New_List;
|
|
|
|
while Present (Item) loop
|
|
|
|
-- Look for components, but exclude _tag field assignment if
|
|
-- the special Componentwise_Assignment flag is set.
|
|
|
|
if Nkind (Item) = N_Component_Declaration
|
|
and then not (Is_Tag (Defining_Identifier (Item))
|
|
and then Componentwise_Assignment (N))
|
|
then
|
|
Append_To
|
|
(Result, Make_Field_Assign (Defining_Identifier (Item)));
|
|
end if;
|
|
|
|
Next (Item);
|
|
end loop;
|
|
|
|
return Result;
|
|
end Make_Field_Assigns;
|
|
|
|
-- Start of processing for Expand_Assign_Record
|
|
|
|
begin
|
|
-- Note that we use the base types for this processing. This results
|
|
-- in some extra work in the constrained case, but the change of
|
|
-- representation case is so unusual that it is not worth the effort.
|
|
|
|
-- First copy the discriminants. This is done unconditionally. It
|
|
-- is required in the unconstrained left side case, and also in the
|
|
-- case where this assignment was constructed during the expansion
|
|
-- of a type conversion (since initialization of discriminants is
|
|
-- suppressed in this case). It is unnecessary but harmless in
|
|
-- other cases.
|
|
|
|
if Has_Discriminants (L_Typ) then
|
|
F := First_Discriminant (R_Typ);
|
|
while Present (F) loop
|
|
|
|
-- If we are expanding the initialization of a derived record
|
|
-- that constrains or renames discriminants of the parent, we
|
|
-- must use the corresponding discriminant in the parent.
|
|
|
|
declare
|
|
CF : Entity_Id;
|
|
|
|
begin
|
|
if Inside_Init_Proc
|
|
and then Present (Corresponding_Discriminant (F))
|
|
then
|
|
CF := Corresponding_Discriminant (F);
|
|
else
|
|
CF := F;
|
|
end if;
|
|
|
|
if Is_Unchecked_Union (Base_Type (R_Typ)) then
|
|
|
|
-- Within an initialization procedure this is the
|
|
-- assignment to an unchecked union component, in which
|
|
-- case there is no discriminant to initialize.
|
|
|
|
if Inside_Init_Proc then
|
|
null;
|
|
|
|
else
|
|
-- The assignment is part of a conversion from a
|
|
-- derived unchecked union type with an inferable
|
|
-- discriminant, to a parent type.
|
|
|
|
Insert_Action (N, Make_Field_Assign (CF, True));
|
|
end if;
|
|
|
|
else
|
|
Insert_Action (N, Make_Field_Assign (CF));
|
|
end if;
|
|
|
|
Next_Discriminant (F);
|
|
end;
|
|
end loop;
|
|
end if;
|
|
|
|
-- We know the underlying type is a record, but its current view
|
|
-- may be private. We must retrieve the usable record declaration.
|
|
|
|
if Nkind_In (Decl, N_Private_Type_Declaration,
|
|
N_Private_Extension_Declaration)
|
|
and then Present (Full_View (R_Typ))
|
|
then
|
|
RDef := Type_Definition (Declaration_Node (Full_View (R_Typ)));
|
|
else
|
|
RDef := Type_Definition (Decl);
|
|
end if;
|
|
|
|
if Nkind (RDef) = N_Derived_Type_Definition then
|
|
RDef := Record_Extension_Part (RDef);
|
|
end if;
|
|
|
|
if Nkind (RDef) = N_Record_Definition
|
|
and then Present (Component_List (RDef))
|
|
then
|
|
if Is_Unchecked_Union (R_Typ) then
|
|
Insert_Actions (N,
|
|
Make_Component_List_Assign (Component_List (RDef), True));
|
|
else
|
|
Insert_Actions
|
|
(N, Make_Component_List_Assign (Component_List (RDef)));
|
|
end if;
|
|
|
|
Rewrite (N, Make_Null_Statement (Loc));
|
|
end if;
|
|
end;
|
|
end Expand_Assign_Record;
|
|
|
|
-----------------------------------
|
|
-- Expand_N_Assignment_Statement --
|
|
-----------------------------------
|
|
|
|
-- This procedure implements various cases where an assignment statement
|
|
-- cannot just be passed on to the back end in untransformed state.
|
|
|
|
procedure Expand_N_Assignment_Statement (N : Node_Id) is
|
|
Crep : constant Boolean := Change_Of_Representation (N);
|
|
Lhs : constant Node_Id := Name (N);
|
|
Loc : constant Source_Ptr := Sloc (N);
|
|
Rhs : constant Node_Id := Expression (N);
|
|
Typ : constant Entity_Id := Underlying_Type (Etype (Lhs));
|
|
Exp : Node_Id;
|
|
|
|
Save_Ghost_Mode : constant Ghost_Mode_Type := Ghost_Mode;
|
|
|
|
begin
|
|
-- The assignment statement is Ghost when the left hand side is Ghost.
|
|
-- Set the mode now to ensure that any nodes generated during expansion
|
|
-- are properly marked as Ghost.
|
|
|
|
Set_Ghost_Mode (N);
|
|
|
|
-- Special case to check right away, if the Componentwise_Assignment
|
|
-- flag is set, this is a reanalysis from the expansion of the primitive
|
|
-- assignment procedure for a tagged type, and all we need to do is to
|
|
-- expand to assignment of components, because otherwise, we would get
|
|
-- infinite recursion (since this looks like a tagged assignment which
|
|
-- would normally try to *call* the primitive assignment procedure).
|
|
|
|
if Componentwise_Assignment (N) then
|
|
Expand_Assign_Record (N);
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
return;
|
|
end if;
|
|
|
|
-- Defend against invalid subscripts on left side if we are in standard
|
|
-- validity checking mode. No need to do this if we are checking all
|
|
-- subscripts.
|
|
|
|
-- Note that we do this right away, because there are some early return
|
|
-- paths in this procedure, and this is required on all paths.
|
|
|
|
if Validity_Checks_On
|
|
and then Validity_Check_Default
|
|
and then not Validity_Check_Subscripts
|
|
then
|
|
Check_Valid_Lvalue_Subscripts (Lhs);
|
|
end if;
|
|
|
|
-- Ada 2005 (AI-327): Handle assignment to priority of protected object
|
|
|
|
-- Rewrite an assignment to X'Priority into a run-time call
|
|
|
|
-- For example: X'Priority := New_Prio_Expr;
|
|
-- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr);
|
|
|
|
-- Note that although X'Priority is notionally an object, it is quite
|
|
-- deliberately not defined as an aliased object in the RM. This means
|
|
-- that it works fine to rewrite it as a call, without having to worry
|
|
-- about complications that would other arise from X'Priority'Access,
|
|
-- which is illegal, because of the lack of aliasing.
|
|
|
|
if Ada_Version >= Ada_2005 then
|
|
declare
|
|
Call : Node_Id;
|
|
Conctyp : Entity_Id;
|
|
Ent : Entity_Id;
|
|
Subprg : Entity_Id;
|
|
RT_Subprg_Name : Node_Id;
|
|
|
|
begin
|
|
-- Handle chains of renamings
|
|
|
|
Ent := Name (N);
|
|
while Nkind (Ent) in N_Has_Entity
|
|
and then Present (Entity (Ent))
|
|
and then Present (Renamed_Object (Entity (Ent)))
|
|
loop
|
|
Ent := Renamed_Object (Entity (Ent));
|
|
end loop;
|
|
|
|
-- The attribute Priority applied to protected objects has been
|
|
-- previously expanded into a call to the Get_Ceiling run-time
|
|
-- subprogram. In restricted profiles this is not available.
|
|
|
|
if Is_Expanded_Priority_Attribute (Ent) 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_Occurrence_Of (RTE (RE_Set_Ceiling), Loc);
|
|
else
|
|
RT_Subprg_Name :=
|
|
New_Occurrence_Of (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);
|
|
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
return;
|
|
end if;
|
|
end;
|
|
end if;
|
|
|
|
-- Deal with assignment checks unless suppressed
|
|
|
|
if not Suppress_Assignment_Checks (N) then
|
|
|
|
-- First deal with generation of range check if required
|
|
|
|
if Do_Range_Check (Rhs) then
|
|
Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed);
|
|
end if;
|
|
|
|
-- Then generate predicate check if required
|
|
|
|
Apply_Predicate_Check (Rhs, Typ);
|
|
end if;
|
|
|
|
-- Check for a special case where a high level transformation is
|
|
-- required. If we have either of:
|
|
|
|
-- P.field := rhs;
|
|
-- P (sub) := rhs;
|
|
|
|
-- where P is a reference to a bit packed array, then we have to unwind
|
|
-- the assignment. The exact meaning of being a reference to a bit
|
|
-- packed array is as follows:
|
|
|
|
-- An indexed component whose prefix is a bit packed array is a
|
|
-- reference to a bit packed array.
|
|
|
|
-- An indexed component or selected component whose prefix is a
|
|
-- reference to a bit packed array is itself a reference ot a
|
|
-- bit packed array.
|
|
|
|
-- The required transformation is
|
|
|
|
-- Tnn : prefix_type := P;
|
|
-- Tnn.field := rhs;
|
|
-- P := Tnn;
|
|
|
|
-- or
|
|
|
|
-- Tnn : prefix_type := P;
|
|
-- Tnn (subscr) := rhs;
|
|
-- P := Tnn;
|
|
|
|
-- Since P is going to be evaluated more than once, any subscripts
|
|
-- in P must have their evaluation forced.
|
|
|
|
if Nkind_In (Lhs, N_Indexed_Component, N_Selected_Component)
|
|
and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs))
|
|
then
|
|
declare
|
|
BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs));
|
|
BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr);
|
|
Tnn : constant Entity_Id :=
|
|
Make_Temporary (Loc, 'T', BPAR_Expr);
|
|
|
|
begin
|
|
-- Insert the post assignment first, because we want to copy the
|
|
-- BPAR_Expr tree before it gets analyzed in the context of the
|
|
-- pre assignment. Note that we do not analyze the post assignment
|
|
-- yet (we cannot till we have completed the analysis of the pre
|
|
-- assignment). As usual, the analysis of this post assignment
|
|
-- will happen on its own when we "run into" it after finishing
|
|
-- the current assignment.
|
|
|
|
Insert_After (N,
|
|
Make_Assignment_Statement (Loc,
|
|
Name => New_Copy_Tree (BPAR_Expr),
|
|
Expression => New_Occurrence_Of (Tnn, Loc)));
|
|
|
|
-- At this stage BPAR_Expr is a reference to a bit packed array
|
|
-- where the reference was not expanded in the original tree,
|
|
-- since it was on the left side of an assignment. But in the
|
|
-- pre-assignment statement (the object definition), BPAR_Expr
|
|
-- will end up on the right hand side, and must be reexpanded. To
|
|
-- achieve this, we reset the analyzed flag of all selected and
|
|
-- indexed components down to the actual indexed component for
|
|
-- the packed array.
|
|
|
|
Exp := BPAR_Expr;
|
|
loop
|
|
Set_Analyzed (Exp, False);
|
|
|
|
if Nkind_In
|
|
(Exp, N_Selected_Component, N_Indexed_Component)
|
|
then
|
|
Exp := Prefix (Exp);
|
|
else
|
|
exit;
|
|
end if;
|
|
end loop;
|
|
|
|
-- Now we can insert and analyze the pre-assignment
|
|
|
|
-- If the right-hand side requires a transient scope, it has
|
|
-- already been placed on the stack. However, the declaration is
|
|
-- inserted in the tree outside of this scope, and must reflect
|
|
-- the proper scope for its variable. This awkward bit is forced
|
|
-- by the stricter scope discipline imposed by GCC 2.97.
|
|
|
|
declare
|
|
Uses_Transient_Scope : constant Boolean :=
|
|
Scope_Is_Transient
|
|
and then N = Node_To_Be_Wrapped;
|
|
|
|
begin
|
|
if Uses_Transient_Scope then
|
|
Push_Scope (Scope (Current_Scope));
|
|
end if;
|
|
|
|
Insert_Before_And_Analyze (N,
|
|
Make_Object_Declaration (Loc,
|
|
Defining_Identifier => Tnn,
|
|
Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc),
|
|
Expression => BPAR_Expr));
|
|
|
|
if Uses_Transient_Scope then
|
|
Pop_Scope;
|
|
end if;
|
|
end;
|
|
|
|
-- Now fix up the original assignment and continue processing
|
|
|
|
Rewrite (Prefix (Lhs),
|
|
New_Occurrence_Of (Tnn, Loc));
|
|
|
|
-- We do not need to reanalyze that assignment, and we do not need
|
|
-- to worry about references to the temporary, but we do need to
|
|
-- make sure that the temporary is not marked as a true constant
|
|
-- since we now have a generated assignment to it.
|
|
|
|
Set_Is_True_Constant (Tnn, False);
|
|
end;
|
|
end if;
|
|
|
|
-- When we have the appropriate type of aggregate in the expression (it
|
|
-- has been determined during analysis of the aggregate by setting the
|
|
-- delay flag), let's perform in place assignment and thus avoid
|
|
-- creating a temporary.
|
|
|
|
if Is_Delayed_Aggregate (Rhs) then
|
|
Convert_Aggr_In_Assignment (N);
|
|
Rewrite (N, Make_Null_Statement (Loc));
|
|
Analyze (N);
|
|
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
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 the
|
|
-- type has unknown discriminants, more elaborate processing below.
|
|
|
|
if Has_Discriminants (Etype (Lhs))
|
|
and then not Has_Unknown_Discriminants (Etype (Lhs))
|
|
then
|
|
-- Skip discriminant check if change of representation. Will be
|
|
-- done when the change of representation is expanded out.
|
|
|
|
if not Crep then
|
|
Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs);
|
|
end if;
|
|
|
|
-- If the type is private without discriminants, and the full type
|
|
-- has discriminants (necessarily with defaults) a check may still be
|
|
-- necessary if the Lhs is aliased. The private discriminants must be
|
|
-- visible to build the discriminant constraints.
|
|
|
|
-- Only an explicit dereference that comes from source indicates
|
|
-- aliasing. Access to formals of protected operations and entries
|
|
-- create dereferences but are not semantic aliasings.
|
|
|
|
elsif Is_Private_Type (Etype (Lhs))
|
|
and then Has_Discriminants (Typ)
|
|
and then Nkind (Lhs) = N_Explicit_Dereference
|
|
and then Comes_From_Source (Lhs)
|
|
then
|
|
declare
|
|
Lt : constant Entity_Id := Etype (Lhs);
|
|
Ubt : Entity_Id := Base_Type (Typ);
|
|
|
|
begin
|
|
-- In the case of an expander-generated record subtype whose base
|
|
-- type still appears private, Typ will have been set to that
|
|
-- private type rather than the underlying record type (because
|
|
-- Underlying type will have returned the record subtype), so it's
|
|
-- necessary to apply Underlying_Type again to the base type to
|
|
-- get the record type we need for the discriminant check. Such
|
|
-- subtypes can be created for assignments in certain cases, such
|
|
-- as within an instantiation passed this kind of private type.
|
|
-- It would be good to avoid this special test, but making changes
|
|
-- to prevent this odd form of record subtype seems difficult. ???
|
|
|
|
if Is_Private_Type (Ubt) then
|
|
Ubt := Underlying_Type (Ubt);
|
|
end if;
|
|
|
|
Set_Etype (Lhs, Ubt);
|
|
Rewrite (Rhs, OK_Convert_To (Base_Type (Ubt), Rhs));
|
|
Apply_Discriminant_Check (Rhs, Ubt, Lhs);
|
|
Set_Etype (Lhs, Lt);
|
|
end;
|
|
|
|
-- If the Lhs has a private type with unknown discriminants, it may
|
|
-- have a full view with discriminants, but those are nameable only
|
|
-- in the underlying type, so convert the Rhs to it before potential
|
|
-- checking. Convert Lhs as well, otherwise the actual subtype might
|
|
-- not be constructible. If the discriminants have defaults the type
|
|
-- is unconstrained and there is nothing to check.
|
|
|
|
elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs)))
|
|
and then Has_Discriminants (Typ)
|
|
and then not Has_Defaulted_Discriminants (Typ)
|
|
then
|
|
Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
|
|
Rewrite (Lhs, OK_Convert_To (Base_Type (Typ), Lhs));
|
|
Apply_Discriminant_Check (Rhs, Typ, Lhs);
|
|
|
|
-- In the access type case, we need the same discriminant check, and
|
|
-- also range checks if we have an access to constrained array.
|
|
|
|
elsif Is_Access_Type (Etype (Lhs))
|
|
and then Is_Constrained (Designated_Type (Etype (Lhs)))
|
|
then
|
|
if Has_Discriminants (Designated_Type (Etype (Lhs))) then
|
|
|
|
-- Skip discriminant check if change of representation. Will be
|
|
-- done when the change of representation is expanded out.
|
|
|
|
if not Crep then
|
|
Apply_Discriminant_Check (Rhs, Etype (Lhs));
|
|
end if;
|
|
|
|
elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then
|
|
Apply_Range_Check (Rhs, Etype (Lhs));
|
|
|
|
if Is_Constrained (Etype (Lhs)) then
|
|
Apply_Length_Check (Rhs, Etype (Lhs));
|
|
end if;
|
|
|
|
if Nkind (Rhs) = N_Allocator then
|
|
declare
|
|
Target_Typ : constant Entity_Id := Etype (Expression (Rhs));
|
|
C_Es : Check_Result;
|
|
|
|
begin
|
|
C_Es :=
|
|
Get_Range_Checks
|
|
(Lhs,
|
|
Target_Typ,
|
|
Etype (Designated_Type (Etype (Lhs))));
|
|
|
|
Insert_Range_Checks
|
|
(C_Es,
|
|
N,
|
|
Target_Typ,
|
|
Sloc (Lhs),
|
|
Lhs);
|
|
end;
|
|
end if;
|
|
end if;
|
|
|
|
-- Apply range check for access type case
|
|
|
|
elsif Is_Access_Type (Etype (Lhs))
|
|
and then Nkind (Rhs) = N_Allocator
|
|
and then Nkind (Expression (Rhs)) = N_Qualified_Expression
|
|
then
|
|
Analyze_And_Resolve (Expression (Rhs));
|
|
Apply_Range_Check
|
|
(Expression (Rhs), Designated_Type (Etype (Lhs)));
|
|
end if;
|
|
|
|
-- Ada 2005 (AI-231): Generate the run-time check
|
|
|
|
if Is_Access_Type (Typ)
|
|
and then Can_Never_Be_Null (Etype (Lhs))
|
|
and then not Can_Never_Be_Null (Etype (Rhs))
|
|
|
|
-- If an actual is an out parameter of a null-excluding access
|
|
-- type, there is access check on entry, so we set the flag
|
|
-- Suppress_Assignment_Checks on the generated statement to
|
|
-- assign the actual to the parameter block, and we do not want
|
|
-- to generate an additional check at this point.
|
|
|
|
and then not Suppress_Assignment_Checks (N)
|
|
then
|
|
Apply_Constraint_Check (Rhs, Etype (Lhs));
|
|
end if;
|
|
|
|
-- Ada 2012 (AI05-148): Update current accessibility level if Rhs is a
|
|
-- stand-alone obj of an anonymous access type. Do not install the check
|
|
-- when the Lhs denotes a container cursor and the Next function employs
|
|
-- an access type, because this can never result in a dangling pointer.
|
|
|
|
if Is_Access_Type (Typ)
|
|
and then Is_Entity_Name (Lhs)
|
|
and then Ekind (Entity (Lhs)) /= E_Loop_Parameter
|
|
and then Present (Effective_Extra_Accessibility (Entity (Lhs)))
|
|
then
|
|
declare
|
|
function Lhs_Entity return Entity_Id;
|
|
-- Look through renames to find the underlying entity.
|
|
-- For assignment to a rename, we don't care about the
|
|
-- Enclosing_Dynamic_Scope of the rename declaration.
|
|
|
|
----------------
|
|
-- Lhs_Entity --
|
|
----------------
|
|
|
|
function Lhs_Entity return Entity_Id is
|
|
Result : Entity_Id := Entity (Lhs);
|
|
|
|
begin
|
|
while Present (Renamed_Object (Result)) loop
|
|
|
|
-- Renamed_Object must return an Entity_Name here
|
|
-- because of preceding "Present (E_E_A (...))" test.
|
|
|
|
Result := Entity (Renamed_Object (Result));
|
|
end loop;
|
|
|
|
return Result;
|
|
end Lhs_Entity;
|
|
|
|
-- Local Declarations
|
|
|
|
Access_Check : constant Node_Id :=
|
|
Make_Raise_Program_Error (Loc,
|
|
Condition =>
|
|
Make_Op_Gt (Loc,
|
|
Left_Opnd =>
|
|
Dynamic_Accessibility_Level (Rhs),
|
|
Right_Opnd =>
|
|
Make_Integer_Literal (Loc,
|
|
Intval =>
|
|
Scope_Depth
|
|
(Enclosing_Dynamic_Scope
|
|
(Lhs_Entity)))),
|
|
Reason => PE_Accessibility_Check_Failed);
|
|
|
|
Access_Level_Update : constant Node_Id :=
|
|
Make_Assignment_Statement (Loc,
|
|
Name =>
|
|
New_Occurrence_Of
|
|
(Effective_Extra_Accessibility
|
|
(Entity (Lhs)), Loc),
|
|
Expression =>
|
|
Dynamic_Accessibility_Level (Rhs));
|
|
|
|
begin
|
|
if not Accessibility_Checks_Suppressed (Entity (Lhs)) then
|
|
Insert_Action (N, Access_Check);
|
|
end if;
|
|
|
|
Insert_Action (N, Access_Level_Update);
|
|
end;
|
|
end if;
|
|
|
|
-- Case of assignment to a bit packed array element. If there is a
|
|
-- change of representation this must be expanded into components,
|
|
-- otherwise this is a bit-field assignment.
|
|
|
|
if Nkind (Lhs) = N_Indexed_Component
|
|
and then Is_Bit_Packed_Array (Etype (Prefix (Lhs)))
|
|
then
|
|
-- Normal case, no change of representation
|
|
|
|
if not Crep then
|
|
Expand_Bit_Packed_Element_Set (N);
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
return;
|
|
|
|
-- Change of representation case
|
|
|
|
else
|
|
-- Generate the following, to force component-by-component
|
|
-- assignments in an efficient way. Otherwise each component
|
|
-- will require a temporary and two bit-field manipulations.
|
|
|
|
-- T1 : Elmt_Type;
|
|
-- T1 := RhS;
|
|
-- Lhs := T1;
|
|
|
|
declare
|
|
Tnn : constant Entity_Id := Make_Temporary (Loc, 'T');
|
|
Stats : List_Id;
|
|
|
|
begin
|
|
Stats :=
|
|
New_List (
|
|
Make_Object_Declaration (Loc,
|
|
Defining_Identifier => Tnn,
|
|
Object_Definition =>
|
|
New_Occurrence_Of (Etype (Lhs), Loc)),
|
|
Make_Assignment_Statement (Loc,
|
|
Name => New_Occurrence_Of (Tnn, Loc),
|
|
Expression => Relocate_Node (Rhs)),
|
|
Make_Assignment_Statement (Loc,
|
|
Name => Relocate_Node (Lhs),
|
|
Expression => New_Occurrence_Of (Tnn, Loc)));
|
|
|
|
Insert_Actions (N, Stats);
|
|
Rewrite (N, Make_Null_Statement (Loc));
|
|
Analyze (N);
|
|
end;
|
|
end if;
|
|
|
|
-- Build-in-place function call case. Note that we're not yet doing
|
|
-- build-in-place for user-written assignment statements (the assignment
|
|
-- here came from an aggregate.)
|
|
|
|
elsif Ada_Version >= Ada_2005
|
|
and then Is_Build_In_Place_Function_Call (Rhs)
|
|
then
|
|
Make_Build_In_Place_Call_In_Assignment (N, Rhs);
|
|
|
|
elsif Is_Tagged_Type (Typ)
|
|
or else (Needs_Finalization (Typ) and then not Is_Array_Type (Typ))
|
|
then
|
|
Tagged_Case : declare
|
|
L : List_Id := No_List;
|
|
Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N);
|
|
|
|
begin
|
|
-- In the controlled case, we ensure that function calls are
|
|
-- evaluated before finalizing the target. In all cases, it makes
|
|
-- the expansion easier if the side-effects are removed first.
|
|
|
|
Remove_Side_Effects (Lhs);
|
|
Remove_Side_Effects (Rhs);
|
|
|
|
-- Avoid recursion in the mechanism
|
|
|
|
Set_Analyzed (N);
|
|
|
|
-- If dispatching assignment, we need to dispatch to _assign
|
|
|
|
if Is_Class_Wide_Type (Typ)
|
|
|
|
-- If the type is tagged, we may as well use the predefined
|
|
-- primitive assignment. This avoids inlining a lot of code
|
|
-- and in the class-wide case, the assignment is replaced
|
|
-- by a dispatching call to _assign. It is suppressed in the
|
|
-- case of assignments created by the expander that correspond
|
|
-- to initializations, where we do want to copy the tag
|
|
-- (Expand_Ctrl_Actions flag is set False in this case). It is
|
|
-- also suppressed if restriction No_Dispatching_Calls is in
|
|
-- force because in that case predefined primitives are not
|
|
-- generated.
|
|
|
|
or else (Is_Tagged_Type (Typ)
|
|
and then Chars (Current_Scope) /= Name_uAssign
|
|
and then Expand_Ctrl_Actions
|
|
and then
|
|
not Restriction_Active (No_Dispatching_Calls))
|
|
then
|
|
if Is_Limited_Type (Typ) then
|
|
|
|
-- This can happen in an instance when the formal is an
|
|
-- extension of a limited interface, and the actual is
|
|
-- limited. This is an error according to AI05-0087, but
|
|
-- is not caught at the point of instantiation in earlier
|
|
-- versions.
|
|
|
|
-- This is wrong, error messages cannot be issued during
|
|
-- expansion, since they would be missed in -gnatc mode ???
|
|
|
|
Error_Msg_N ("assignment not available on limited type", N);
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
return;
|
|
end if;
|
|
|
|
-- Fetch the primitive op _assign and proper type to call it.
|
|
-- Because of possible conflicts between private and full view,
|
|
-- fetch the proper type directly from the operation profile.
|
|
|
|
declare
|
|
Op : constant Entity_Id :=
|
|
Find_Prim_Op (Typ, Name_uAssign);
|
|
F_Typ : Entity_Id := Etype (First_Formal (Op));
|
|
|
|
begin
|
|
-- If the assignment is dispatching, make sure to use the
|
|
-- proper type.
|
|
|
|
if Is_Class_Wide_Type (Typ) then
|
|
F_Typ := Class_Wide_Type (F_Typ);
|
|
end if;
|
|
|
|
L := New_List;
|
|
|
|
-- In case of assignment to a class-wide tagged type, before
|
|
-- the assignment we generate run-time check to ensure that
|
|
-- the tags of source and target match.
|
|
|
|
if not Tag_Checks_Suppressed (Typ)
|
|
and then Is_Class_Wide_Type (Typ)
|
|
and then Is_Tagged_Type (Typ)
|
|
and then Is_Tagged_Type (Underlying_Type (Etype (Rhs)))
|
|
then
|
|
declare
|
|
Lhs_Tag : Node_Id;
|
|
Rhs_Tag : Node_Id;
|
|
|
|
begin
|
|
if not Is_Interface (Typ) then
|
|
Lhs_Tag :=
|
|
Make_Selected_Component (Loc,
|
|
Prefix => Duplicate_Subexpr (Lhs),
|
|
Selector_Name =>
|
|
Make_Identifier (Loc, Name_uTag));
|
|
Rhs_Tag :=
|
|
Make_Selected_Component (Loc,
|
|
Prefix => Duplicate_Subexpr (Rhs),
|
|
Selector_Name =>
|
|
Make_Identifier (Loc, Name_uTag));
|
|
else
|
|
-- Displace the pointer to the base of the objects
|
|
-- applying 'Address, which is later expanded into
|
|
-- a call to RE_Base_Address.
|
|
|
|
Lhs_Tag :=
|
|
Make_Explicit_Dereference (Loc,
|
|
Prefix =>
|
|
Unchecked_Convert_To (RTE (RE_Tag_Ptr),
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix => Duplicate_Subexpr (Lhs),
|
|
Attribute_Name => Name_Address)));
|
|
Rhs_Tag :=
|
|
Make_Explicit_Dereference (Loc,
|
|
Prefix =>
|
|
Unchecked_Convert_To (RTE (RE_Tag_Ptr),
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix => Duplicate_Subexpr (Rhs),
|
|
Attribute_Name => Name_Address)));
|
|
end if;
|
|
|
|
Append_To (L,
|
|
Make_Raise_Constraint_Error (Loc,
|
|
Condition =>
|
|
Make_Op_Ne (Loc,
|
|
Left_Opnd => Lhs_Tag,
|
|
Right_Opnd => Rhs_Tag),
|
|
Reason => CE_Tag_Check_Failed));
|
|
end;
|
|
end if;
|
|
|
|
declare
|
|
Left_N : Node_Id := Duplicate_Subexpr (Lhs);
|
|
Right_N : Node_Id := Duplicate_Subexpr (Rhs);
|
|
|
|
begin
|
|
-- In order to dispatch the call to _assign the type of
|
|
-- the actuals must match. Add conversion (if required).
|
|
|
|
if Etype (Lhs) /= F_Typ then
|
|
Left_N := Unchecked_Convert_To (F_Typ, Left_N);
|
|
end if;
|
|
|
|
if Etype (Rhs) /= F_Typ then
|
|
Right_N := Unchecked_Convert_To (F_Typ, Right_N);
|
|
end if;
|
|
|
|
Append_To (L,
|
|
Make_Procedure_Call_Statement (Loc,
|
|
Name => New_Occurrence_Of (Op, Loc),
|
|
Parameter_Associations => New_List (
|
|
Node1 => Left_N,
|
|
Node2 => Right_N)));
|
|
end;
|
|
end;
|
|
|
|
else
|
|
L := Make_Tag_Ctrl_Assignment (N);
|
|
|
|
-- We can't afford to have destructive Finalization Actions in
|
|
-- the Self assignment case, so if the target and the source
|
|
-- are not obviously different, code is generated to avoid the
|
|
-- self assignment case:
|
|
|
|
-- if lhs'address /= rhs'address then
|
|
-- <code for controlled and/or tagged assignment>
|
|
-- end if;
|
|
|
|
-- Skip this if Restriction (No_Finalization) is active
|
|
|
|
if not Statically_Different (Lhs, Rhs)
|
|
and then Expand_Ctrl_Actions
|
|
and then not Restriction_Active (No_Finalization)
|
|
then
|
|
L := New_List (
|
|
Make_Implicit_If_Statement (N,
|
|
Condition =>
|
|
Make_Op_Ne (Loc,
|
|
Left_Opnd =>
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix => Duplicate_Subexpr (Lhs),
|
|
Attribute_Name => Name_Address),
|
|
|
|
Right_Opnd =>
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix => Duplicate_Subexpr (Rhs),
|
|
Attribute_Name => Name_Address)),
|
|
|
|
Then_Statements => L));
|
|
end if;
|
|
|
|
-- We need to set up an exception handler for implementing
|
|
-- 7.6.1(18). The remaining adjustments are tackled by the
|
|
-- implementation of adjust for record_controllers (see
|
|
-- s-finimp.adb).
|
|
|
|
-- This is skipped if we have no finalization
|
|
|
|
if Expand_Ctrl_Actions
|
|
and then not Restriction_Active (No_Finalization)
|
|
then
|
|
L := New_List (
|
|
Make_Block_Statement (Loc,
|
|
Handled_Statement_Sequence =>
|
|
Make_Handled_Sequence_Of_Statements (Loc,
|
|
Statements => L,
|
|
Exception_Handlers => New_List (
|
|
Make_Handler_For_Ctrl_Operation (Loc)))));
|
|
end if;
|
|
end if;
|
|
|
|
Rewrite (N,
|
|
Make_Block_Statement (Loc,
|
|
Handled_Statement_Sequence =>
|
|
Make_Handled_Sequence_Of_Statements (Loc, Statements => L)));
|
|
|
|
-- If no restrictions on aborts, protect the whole assignment
|
|
-- for controlled objects as per 9.8(11).
|
|
|
|
if Needs_Finalization (Typ)
|
|
and then Expand_Ctrl_Actions
|
|
and then Abort_Allowed
|
|
then
|
|
declare
|
|
Blk : constant Entity_Id :=
|
|
New_Internal_Entity
|
|
(E_Block, Current_Scope, Sloc (N), 'B');
|
|
AUD : constant Entity_Id := RTE (RE_Abort_Undefer_Direct);
|
|
|
|
begin
|
|
Set_Is_Abort_Block (N);
|
|
|
|
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 (AUD, Loc));
|
|
|
|
-- Present the Abort_Undefer_Direct function to the backend
|
|
-- so that it can inline the call to the function.
|
|
|
|
Add_Inlined_Body (AUD, N);
|
|
|
|
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);
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
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);
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
return;
|
|
end;
|
|
|
|
-- Record types
|
|
|
|
elsif Is_Record_Type (Typ) then
|
|
Expand_Assign_Record (N);
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
return;
|
|
|
|
-- Scalar types. This is where we perform the processing related to the
|
|
-- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid
|
|
-- scalar values.
|
|
|
|
elsif Is_Scalar_Type (Typ) then
|
|
|
|
-- Case where right side is known valid
|
|
|
|
if Expr_Known_Valid (Rhs) then
|
|
|
|
-- Here the right side is valid, so it is fine. The case to deal
|
|
-- with is when the left side is a local variable reference whose
|
|
-- value is not currently known to be valid. If this is the case,
|
|
-- and the assignment appears in an unconditional context, then
|
|
-- we can mark the left side as now being valid if one of these
|
|
-- conditions holds:
|
|
|
|
-- The expression of the right side has Do_Range_Check set so
|
|
-- that we know a range check will be performed. Note that it
|
|
-- can be the case that a range check is omitted because we
|
|
-- make the assumption that we can assume validity for operands
|
|
-- appearing in the right side in determining whether a range
|
|
-- check is required
|
|
|
|
-- The subtype of the right side matches the subtype of the
|
|
-- left side. In this case, even though we have not checked
|
|
-- the range of the right side, we know it is in range of its
|
|
-- subtype if the expression is valid.
|
|
|
|
if Is_Local_Variable_Reference (Lhs)
|
|
and then not Is_Known_Valid (Entity (Lhs))
|
|
and then In_Unconditional_Context (N)
|
|
then
|
|
if Do_Range_Check (Rhs)
|
|
or else Etype (Lhs) = Etype (Rhs)
|
|
then
|
|
Set_Is_Known_Valid (Entity (Lhs), True);
|
|
end if;
|
|
end if;
|
|
|
|
-- Case where right side may be invalid in the sense of the RM
|
|
-- reference above. The RM does not require that we check for the
|
|
-- validity on an assignment, but it does require that the assignment
|
|
-- of an invalid value not cause erroneous behavior.
|
|
|
|
-- The general approach in GNAT is to use the Is_Known_Valid flag
|
|
-- to avoid the need for validity checking on assignments. However
|
|
-- in some cases, we have to do validity checking in order to make
|
|
-- sure that the setting of this flag is correct.
|
|
|
|
else
|
|
-- Validate right side if we are validating copies
|
|
|
|
if Validity_Checks_On
|
|
and then Validity_Check_Copies
|
|
then
|
|
-- Skip this if left hand side is an array or record component
|
|
-- and elementary component validity checks are suppressed.
|
|
|
|
if Nkind_In (Lhs, N_Selected_Component, N_Indexed_Component)
|
|
and then not Validity_Check_Components
|
|
then
|
|
null;
|
|
else
|
|
Ensure_Valid (Rhs);
|
|
end if;
|
|
|
|
-- We can propagate this to the left side where appropriate
|
|
|
|
if Is_Local_Variable_Reference (Lhs)
|
|
and then not Is_Known_Valid (Entity (Lhs))
|
|
and then In_Unconditional_Context (N)
|
|
then
|
|
Set_Is_Known_Valid (Entity (Lhs), True);
|
|
end if;
|
|
|
|
-- Otherwise check to see what should be done
|
|
|
|
-- If left side is a local variable, then we just set its flag to
|
|
-- indicate that its value may no longer be valid, since we are
|
|
-- copying a potentially invalid value.
|
|
|
|
elsif Is_Local_Variable_Reference (Lhs) then
|
|
Set_Is_Known_Valid (Entity (Lhs), False);
|
|
|
|
-- Check for case of a nonlocal variable on the left side which
|
|
-- is currently known to be valid. In this case, we simply ensure
|
|
-- that the right side is valid. We only play the game of copying
|
|
-- validity status for local variables, since we are doing this
|
|
-- statically, not by tracing the full flow graph.
|
|
|
|
elsif Is_Entity_Name (Lhs)
|
|
and then Is_Known_Valid (Entity (Lhs))
|
|
then
|
|
-- Note: If Validity_Checking mode is set to none, we ignore
|
|
-- the Ensure_Valid call so don't worry about that case here.
|
|
|
|
Ensure_Valid (Rhs);
|
|
|
|
-- In all other cases, we can safely copy an invalid value without
|
|
-- worrying about the status of the left side. Since it is not a
|
|
-- variable reference it will not be considered
|
|
-- as being known to be valid in any case.
|
|
|
|
else
|
|
null;
|
|
end if;
|
|
end if;
|
|
end if;
|
|
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
|
|
exception
|
|
when RE_Not_Available =>
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
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 the value is static but its subtype is predicated and the value
|
|
-- does not obey the predicate, the value is marked non-static, and
|
|
-- there can be no corresponding static alternative. In that case we
|
|
-- replace the case statement with an exception, regardless of whether
|
|
-- assertions are enabled or not, unless predicates are ignored.
|
|
|
|
if Compile_Time_Known_Value (Expr)
|
|
and then Has_Predicates (Etype (Expr))
|
|
and then not Predicates_Ignored (Etype (Expr))
|
|
and then not Is_OK_Static_Expression (Expr)
|
|
then
|
|
Rewrite (N,
|
|
Make_Raise_Constraint_Error (Loc, Reason => CE_Invalid_Data));
|
|
Analyze (N);
|
|
return;
|
|
|
|
elsif Compile_Time_Known_Value (Expr)
|
|
and then (not Has_Predicates (Etype (Expr))
|
|
or else Is_Static_Expression (Expr))
|
|
then
|
|
Alt := Find_Static_Alternative (N);
|
|
|
|
-- Do not consider controlled objects found in a case statement which
|
|
-- actually models a case expression because their early finalization
|
|
-- will affect the result of the expression.
|
|
|
|
if not From_Conditional_Expression (N) then
|
|
Process_Statements_For_Controlled_Objects (Alt);
|
|
end if;
|
|
|
|
-- Move statements from this alternative after the case statement.
|
|
-- They are already analyzed, so will be skipped by the analyzer.
|
|
|
|
Insert_List_After (N, Statements (Alt));
|
|
|
|
-- That leaves the case statement as a shell. So now we can kill all
|
|
-- other alternatives in the case statement.
|
|
|
|
Kill_Dead_Code (Expression (N));
|
|
|
|
declare
|
|
Dead_Alt : Node_Id;
|
|
|
|
begin
|
|
-- Loop through case alternatives, skipping pragmas, and skipping
|
|
-- the one alternative that we select (and therefore retain).
|
|
|
|
Dead_Alt := First (Alternatives (N));
|
|
while Present (Dead_Alt) loop
|
|
if Dead_Alt /= Alt
|
|
and then Nkind (Dead_Alt) = N_Case_Statement_Alternative
|
|
then
|
|
Kill_Dead_Code (Statements (Dead_Alt), Warn_On_Deleted_Code);
|
|
end if;
|
|
|
|
Next (Dead_Alt);
|
|
end loop;
|
|
end;
|
|
|
|
Rewrite (N, Make_Null_Statement (Loc));
|
|
return;
|
|
end if;
|
|
|
|
-- Here if the choice is not determined at compile time
|
|
|
|
declare
|
|
Last_Alt : constant Node_Id := Last (Alternatives (N));
|
|
|
|
Others_Present : Boolean;
|
|
Others_Node : Node_Id;
|
|
|
|
Then_Stms : List_Id;
|
|
Else_Stms : List_Id;
|
|
|
|
begin
|
|
if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then
|
|
Others_Present := True;
|
|
Others_Node := Last_Alt;
|
|
else
|
|
Others_Present := False;
|
|
end if;
|
|
|
|
-- First step is to worry about possible invalid argument. The RM
|
|
-- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
|
|
-- outside the base range), then Constraint_Error must be raised.
|
|
|
|
-- Case of validity check required (validity checks are on, the
|
|
-- expression is not known to be valid, and the case statement
|
|
-- comes from source -- no need to validity check internally
|
|
-- generated case statements).
|
|
|
|
if Validity_Check_Default
|
|
and then not Predicates_Ignored (Etype (Expr))
|
|
then
|
|
Ensure_Valid (Expr);
|
|
end if;
|
|
|
|
-- If there is only a single alternative, just replace it with the
|
|
-- sequence of statements since obviously that is what is going to
|
|
-- be executed in all cases.
|
|
|
|
Len := List_Length (Alternatives (N));
|
|
|
|
if Len = 1 then
|
|
|
|
-- We still need to evaluate the expression if it has any side
|
|
-- effects.
|
|
|
|
Remove_Side_Effects (Expression (N));
|
|
Alt := First (Alternatives (N));
|
|
|
|
-- Do not consider controlled objects found in a case statement
|
|
-- which actually models a case expression because their early
|
|
-- finalization will affect the result of the expression.
|
|
|
|
if not From_Conditional_Expression (N) then
|
|
Process_Statements_For_Controlled_Objects (Alt);
|
|
end if;
|
|
|
|
Insert_List_After (N, Statements (Alt));
|
|
|
|
-- That leaves the case statement as a shell. The alternative that
|
|
-- will be executed is reset to a null list. So now we can kill
|
|
-- the entire case statement.
|
|
|
|
Kill_Dead_Code (Expression (N));
|
|
Rewrite (N, Make_Null_Statement (Loc));
|
|
return;
|
|
|
|
-- An optimization. If there are only two alternatives, and only
|
|
-- a single choice, then rewrite the whole case statement as an
|
|
-- if statement, since this can result in subsequent optimizations.
|
|
-- This helps not only with case statements in the source of a
|
|
-- simple form, but also with generated code (discriminant check
|
|
-- functions in particular).
|
|
|
|
-- Note: it is OK to do this before expanding out choices for any
|
|
-- static predicates, since the if statement processing will handle
|
|
-- the static predicate case fine.
|
|
|
|
elsif Len = 2 then
|
|
Chlist := Discrete_Choices (First (Alternatives (N)));
|
|
|
|
if List_Length (Chlist) = 1 then
|
|
Choice := First (Chlist);
|
|
|
|
Then_Stms := Statements (First (Alternatives (N)));
|
|
Else_Stms := Statements (Last (Alternatives (N)));
|
|
|
|
-- For TRUE, generate "expression", not expression = true
|
|
|
|
if Nkind (Choice) = N_Identifier
|
|
and then Entity (Choice) = Standard_True
|
|
then
|
|
Cond := Expression (N);
|
|
|
|
-- For FALSE, generate "expression" and switch then/else
|
|
|
|
elsif Nkind (Choice) = N_Identifier
|
|
and then Entity (Choice) = Standard_False
|
|
then
|
|
Cond := Expression (N);
|
|
Else_Stms := Statements (First (Alternatives (N)));
|
|
Then_Stms := Statements (Last (Alternatives (N)));
|
|
|
|
-- For a range, generate "expression in range"
|
|
|
|
elsif Nkind (Choice) = N_Range
|
|
or else (Nkind (Choice) = N_Attribute_Reference
|
|
and then Attribute_Name (Choice) = Name_Range)
|
|
or else (Is_Entity_Name (Choice)
|
|
and then Is_Type (Entity (Choice)))
|
|
then
|
|
Cond :=
|
|
Make_In (Loc,
|
|
Left_Opnd => Expression (N),
|
|
Right_Opnd => Relocate_Node (Choice));
|
|
|
|
-- A subtype indication is not a legal operator in a membership
|
|
-- test, so retrieve its range.
|
|
|
|
elsif Nkind (Choice) = N_Subtype_Indication then
|
|
Cond :=
|
|
Make_In (Loc,
|
|
Left_Opnd => Expression (N),
|
|
Right_Opnd =>
|
|
Relocate_Node
|
|
(Range_Expression (Constraint (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 for 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));
|
|
|
|
-- If Predicates_Ignored is true the value does not satisfy the
|
|
-- predicate, and there is no Others choice, Constraint_Error
|
|
-- must be raised (4.5.7 (21/3)).
|
|
|
|
if Predicates_Ignored (Etype (Expr)) then
|
|
declare
|
|
Except : constant Node_Id :=
|
|
Make_Raise_Constraint_Error (Loc,
|
|
Reason => CE_Invalid_Data);
|
|
New_Alt : constant Node_Id :=
|
|
Make_Case_Statement_Alternative (Loc,
|
|
Discrete_Choices => New_List (
|
|
Make_Others_Choice (Loc)),
|
|
Statements => New_List (Except));
|
|
|
|
begin
|
|
Append (New_Alt, Alternatives (N));
|
|
Analyze_And_Resolve (Except);
|
|
end;
|
|
|
|
else
|
|
Set_Others_Discrete_Choices
|
|
(Others_Node, Discrete_Choices (Last_Alt));
|
|
Set_Discrete_Choices (Last_Alt, New_List (Others_Node));
|
|
end if;
|
|
|
|
end if;
|
|
|
|
-- Deal with possible declarations of controlled objects, and also
|
|
-- with rewriting choice sequences for static predicate references.
|
|
|
|
Alt := First_Non_Pragma (Alternatives (N));
|
|
while Present (Alt) loop
|
|
|
|
-- Do not consider controlled objects found in a case statement
|
|
-- which actually models a case expression because their early
|
|
-- finalization will affect the result of the expression.
|
|
|
|
if not From_Conditional_Expression (N) then
|
|
Process_Statements_For_Controlled_Objects (Alt);
|
|
end if;
|
|
|
|
if Has_SP_Choice (Alt) then
|
|
Expand_Static_Predicates_In_Choices (Alt);
|
|
end if;
|
|
|
|
Next_Non_Pragma (Alt);
|
|
end loop;
|
|
end;
|
|
end Expand_N_Case_Statement;
|
|
|
|
-----------------------------
|
|
-- Expand_N_Exit_Statement --
|
|
-----------------------------
|
|
|
|
-- The only processing required is to deal with a possible C/Fortran
|
|
-- boolean value used as the condition for the exit statement.
|
|
|
|
procedure Expand_N_Exit_Statement (N : Node_Id) is
|
|
begin
|
|
Adjust_Condition (Condition (N));
|
|
end Expand_N_Exit_Statement;
|
|
|
|
----------------------------------
|
|
-- Expand_Formal_Container_Loop --
|
|
----------------------------------
|
|
|
|
procedure Expand_Formal_Container_Loop (N : Node_Id) is
|
|
Loc : constant Source_Ptr := Sloc (N);
|
|
Isc : constant Node_Id := Iteration_Scheme (N);
|
|
I_Spec : constant Node_Id := Iterator_Specification (Isc);
|
|
Cursor : constant Entity_Id := Defining_Identifier (I_Spec);
|
|
Container : constant Node_Id := Entity (Name (I_Spec));
|
|
Stats : constant List_Id := Statements (N);
|
|
|
|
Advance : Node_Id;
|
|
Blk_Nod : Node_Id;
|
|
Init : Node_Id;
|
|
New_Loop : Node_Id;
|
|
|
|
begin
|
|
-- The expansion resembles the one for Ada containers, but the
|
|
-- primitives mention the domain of iteration explicitly, and
|
|
-- function First applied to the container yields a cursor directly.
|
|
|
|
-- Cursor : Cursor_type := First (Container);
|
|
-- while Has_Element (Cursor, Container) loop
|
|
-- <original loop statements>
|
|
-- Cursor := Next (Container, Cursor);
|
|
-- end loop;
|
|
|
|
Build_Formal_Container_Iteration
|
|
(N, Container, Cursor, Init, Advance, New_Loop);
|
|
|
|
Set_Ekind (Cursor, E_Variable);
|
|
Append_To (Stats, Advance);
|
|
|
|
-- Build block to capture declaration of cursor entity.
|
|
|
|
Blk_Nod :=
|
|
Make_Block_Statement (Loc,
|
|
Declarations => New_List (Init),
|
|
Handled_Statement_Sequence =>
|
|
Make_Handled_Sequence_Of_Statements (Loc,
|
|
Statements => New_List (New_Loop)));
|
|
|
|
Rewrite (N, Blk_Nod);
|
|
Analyze (N);
|
|
end Expand_Formal_Container_Loop;
|
|
|
|
------------------------------------------
|
|
-- Expand_Formal_Container_Element_Loop --
|
|
------------------------------------------
|
|
|
|
procedure Expand_Formal_Container_Element_Loop (N : Node_Id) is
|
|
Loc : constant Source_Ptr := Sloc (N);
|
|
Isc : constant Node_Id := Iteration_Scheme (N);
|
|
I_Spec : constant Node_Id := Iterator_Specification (Isc);
|
|
Element : constant Entity_Id := Defining_Identifier (I_Spec);
|
|
Container : constant Node_Id := Entity (Name (I_Spec));
|
|
Container_Typ : constant Entity_Id := Base_Type (Etype (Container));
|
|
Stats : constant List_Id := Statements (N);
|
|
|
|
Cursor : constant Entity_Id :=
|
|
Make_Defining_Identifier (Loc,
|
|
Chars => New_External_Name (Chars (Element), 'C'));
|
|
Elmt_Decl : Node_Id;
|
|
Elmt_Ref : Node_Id;
|
|
|
|
Element_Op : constant Entity_Id :=
|
|
Get_Iterable_Type_Primitive (Container_Typ, Name_Element);
|
|
|
|
Advance : Node_Id;
|
|
Init : Node_Id;
|
|
New_Loop : Node_Id;
|
|
|
|
begin
|
|
-- For an element iterator, the Element aspect must be present,
|
|
-- (this is checked during analysis) and the expansion takes the form:
|
|
|
|
-- Cursor : Cursor_type := First (Container);
|
|
-- Elmt : Element_Type;
|
|
-- while Has_Element (Cursor, Container) loop
|
|
-- Elmt := Element (Container, Cursor);
|
|
-- <original loop statements>
|
|
-- Cursor := Next (Container, Cursor);
|
|
-- end loop;
|
|
|
|
-- However this expansion is not legal if the element is indefinite.
|
|
-- In that case we create a block to hold a variable declaration
|
|
-- initialized with a call to Element, and generate:
|
|
|
|
-- Cursor : Cursor_type := First (Container);
|
|
-- while Has_Element (Cursor, Container) loop
|
|
-- declare
|
|
-- Elmt : Element-Type := Element (Container, Cursor);
|
|
-- begin
|
|
-- <original loop statements>
|
|
-- Cursor := Next (Container, Cursor);
|
|
-- end;
|
|
-- end loop;
|
|
|
|
Build_Formal_Container_Iteration
|
|
(N, Container, Cursor, Init, Advance, New_Loop);
|
|
Append_To (Stats, Advance);
|
|
|
|
Set_Ekind (Cursor, E_Variable);
|
|
Insert_Action (N, Init);
|
|
|
|
-- Declaration for Element.
|
|
|
|
Elmt_Decl :=
|
|
Make_Object_Declaration (Loc,
|
|
Defining_Identifier => Element,
|
|
Object_Definition => New_Occurrence_Of (Etype (Element_Op), Loc));
|
|
|
|
if not Is_Constrained (Etype (Element_Op)) then
|
|
Set_Expression (Elmt_Decl,
|
|
Make_Function_Call (Loc,
|
|
Name => New_Occurrence_Of (Element_Op, Loc),
|
|
Parameter_Associations => New_List (
|
|
New_Occurrence_Of (Container, Loc),
|
|
New_Occurrence_Of (Cursor, Loc))));
|
|
|
|
Set_Statements (New_Loop,
|
|
New_List
|
|
(Make_Block_Statement (Loc,
|
|
Declarations => New_List (Elmt_Decl),
|
|
Handled_Statement_Sequence =>
|
|
Make_Handled_Sequence_Of_Statements (Loc,
|
|
Statements => Stats))));
|
|
|
|
else
|
|
Elmt_Ref :=
|
|
Make_Assignment_Statement (Loc,
|
|
Name => New_Occurrence_Of (Element, Loc),
|
|
Expression =>
|
|
Make_Function_Call (Loc,
|
|
Name => New_Occurrence_Of (Element_Op, Loc),
|
|
Parameter_Associations => New_List (
|
|
New_Occurrence_Of (Container, Loc),
|
|
New_Occurrence_Of (Cursor, Loc))));
|
|
|
|
Prepend (Elmt_Ref, Stats);
|
|
|
|
-- The element is assignable in the expanded code
|
|
|
|
Set_Assignment_OK (Name (Elmt_Ref));
|
|
|
|
-- The loop is rewritten as a block, to hold the element declaration
|
|
|
|
New_Loop :=
|
|
Make_Block_Statement (Loc,
|
|
Declarations => New_List (Elmt_Decl),
|
|
Handled_Statement_Sequence =>
|
|
Make_Handled_Sequence_Of_Statements (Loc,
|
|
Statements => New_List (New_Loop)));
|
|
end if;
|
|
|
|
-- The element is only modified in expanded code, so it appears as
|
|
-- unassigned to the warning machinery. We must suppress this spurious
|
|
-- warning explicitly.
|
|
|
|
Set_Warnings_Off (Element);
|
|
|
|
Rewrite (N, New_Loop);
|
|
|
|
-- The loop parameter is declared by an object declaration, but within
|
|
-- the loop we must prevent user assignments to it, so we analyze the
|
|
-- declaration and reset the entity kind, before analyzing the rest of
|
|
-- the loop;
|
|
|
|
Analyze (Elmt_Decl);
|
|
Set_Ekind (Defining_Identifier (Elmt_Decl), E_Loop_Parameter);
|
|
|
|
Analyze (N);
|
|
end Expand_Formal_Container_Element_Loop;
|
|
|
|
-----------------------------
|
|
-- 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
|
|
-- Do not consider controlled objects found in an if statement which
|
|
-- actually models an if expression because their early finalization
|
|
-- will affect the result of the expression.
|
|
|
|
if not From_Conditional_Expression (N) then
|
|
Process_Statements_For_Controlled_Objects (N);
|
|
end if;
|
|
|
|
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 condition actions that are present.
|
|
|
|
if Present (Elsif_Parts (N)) then
|
|
E := First (Elsif_Parts (N));
|
|
while Present (E) loop
|
|
|
|
-- Do not consider controlled objects found in an if statement
|
|
-- which actually models an if expression because their early
|
|
-- finalization will affect the result of the expression.
|
|
|
|
if not From_Conditional_Expression (N) then
|
|
Process_Statements_For_Controlled_Objects (E);
|
|
end if;
|
|
|
|
Adjust_Condition (Condition (E));
|
|
|
|
-- If there are condition actions, then rewrite the if statement
|
|
-- as indicated above. We also do the same rewrite for a True or
|
|
-- False condition. The further processing of this constant
|
|
-- condition is then done by the recursive call to expand the
|
|
-- newly created if statement
|
|
|
|
if Present (Condition_Actions (E))
|
|
or else Compile_Time_Known_Value (Condition (E))
|
|
then
|
|
-- Note this is not an implicit if statement, since it is part
|
|
-- of an explicit if statement in the source (or of an implicit
|
|
-- if statement that has already been tested).
|
|
|
|
New_If :=
|
|
Make_If_Statement (Sloc (E),
|
|
Condition => Condition (E),
|
|
Then_Statements => Then_Statements (E),
|
|
Elsif_Parts => No_List,
|
|
Else_Statements => Else_Statements (N));
|
|
|
|
-- Elsif parts for new if come from remaining elsif's of parent
|
|
|
|
while Present (Next (E)) loop
|
|
if No (Elsif_Parts (New_If)) then
|
|
Set_Elsif_Parts (New_If, New_List);
|
|
end if;
|
|
|
|
Append (Remove_Next (E), Elsif_Parts (New_If));
|
|
end loop;
|
|
|
|
Set_Else_Statements (N, New_List (New_If));
|
|
|
|
if Present (Condition_Actions (E)) then
|
|
Insert_List_Before (New_If, Condition_Actions (E));
|
|
end if;
|
|
|
|
Remove (E);
|
|
|
|
if Is_Empty_List (Elsif_Parts (N)) then
|
|
Set_Elsif_Parts (N, No_List);
|
|
end if;
|
|
|
|
Analyze (New_If);
|
|
return;
|
|
|
|
-- No special processing for that elsif part, move to next
|
|
|
|
else
|
|
Next (E);
|
|
end if;
|
|
end loop;
|
|
end if;
|
|
|
|
-- Some more optimizations applicable if we still have an IF statement
|
|
|
|
if Nkind (N) /= N_If_Statement then
|
|
return;
|
|
end if;
|
|
|
|
-- Another optimization, special cases that can be simplified
|
|
|
|
-- if expression then
|
|
-- return true;
|
|
-- else
|
|
-- return false;
|
|
-- end if;
|
|
|
|
-- can be changed to:
|
|
|
|
-- return expression;
|
|
|
|
-- and
|
|
|
|
-- if expression then
|
|
-- return false;
|
|
-- else
|
|
-- return true;
|
|
-- end if;
|
|
|
|
-- can be changed to:
|
|
|
|
-- return not (expression);
|
|
|
|
-- Only do these optimizations if we are at least at -O1 level and
|
|
-- do not do them if control flow optimizations are suppressed.
|
|
|
|
if Optimization_Level > 0
|
|
and then not Opt.Suppress_Control_Flow_Optimizations
|
|
then
|
|
if Nkind (N) = N_If_Statement
|
|
and then No (Elsif_Parts (N))
|
|
and then Present (Else_Statements (N))
|
|
and then List_Length (Then_Statements (N)) = 1
|
|
and then List_Length (Else_Statements (N)) = 1
|
|
then
|
|
declare
|
|
Then_Stm : constant Node_Id := First (Then_Statements (N));
|
|
Else_Stm : constant Node_Id := First (Else_Statements (N));
|
|
|
|
begin
|
|
if Nkind (Then_Stm) = N_Simple_Return_Statement
|
|
and then
|
|
Nkind (Else_Stm) = N_Simple_Return_Statement
|
|
then
|
|
declare
|
|
Then_Expr : constant Node_Id := Expression (Then_Stm);
|
|
Else_Expr : constant Node_Id := Expression (Else_Stm);
|
|
|
|
begin
|
|
if Nkind (Then_Expr) = N_Identifier
|
|
and then
|
|
Nkind (Else_Expr) = N_Identifier
|
|
then
|
|
if Entity (Then_Expr) = Standard_True
|
|
and then Entity (Else_Expr) = Standard_False
|
|
then
|
|
Rewrite (N,
|
|
Make_Simple_Return_Statement (Loc,
|
|
Expression => Relocate_Node (Condition (N))));
|
|
Analyze (N);
|
|
return;
|
|
|
|
elsif Entity (Then_Expr) = Standard_False
|
|
and then Entity (Else_Expr) = Standard_True
|
|
then
|
|
Rewrite (N,
|
|
Make_Simple_Return_Statement (Loc,
|
|
Expression =>
|
|
Make_Op_Not (Loc,
|
|
Right_Opnd =>
|
|
Relocate_Node (Condition (N)))));
|
|
Analyze (N);
|
|
return;
|
|
end if;
|
|
end if;
|
|
end;
|
|
end if;
|
|
end;
|
|
end if;
|
|
end if;
|
|
end Expand_N_If_Statement;
|
|
|
|
--------------------------
|
|
-- Expand_Iterator_Loop --
|
|
--------------------------
|
|
|
|
procedure Expand_Iterator_Loop (N : Node_Id) is
|
|
Isc : constant Node_Id := Iteration_Scheme (N);
|
|
I_Spec : constant Node_Id := Iterator_Specification (Isc);
|
|
|
|
Container : constant Node_Id := Name (I_Spec);
|
|
Container_Typ : constant Entity_Id := Base_Type (Etype (Container));
|
|
|
|
begin
|
|
-- Processing for arrays
|
|
|
|
if Is_Array_Type (Container_Typ) then
|
|
pragma Assert (Of_Present (I_Spec));
|
|
Expand_Iterator_Loop_Over_Array (N);
|
|
|
|
elsif Has_Aspect (Container_Typ, Aspect_Iterable) then
|
|
if Of_Present (I_Spec) then
|
|
Expand_Formal_Container_Element_Loop (N);
|
|
else
|
|
Expand_Formal_Container_Loop (N);
|
|
end if;
|
|
|
|
-- Processing for containers
|
|
|
|
else
|
|
Expand_Iterator_Loop_Over_Container
|
|
(N, Isc, I_Spec, Container, Container_Typ);
|
|
end if;
|
|
end Expand_Iterator_Loop;
|
|
|
|
-------------------------------------
|
|
-- Expand_Iterator_Loop_Over_Array --
|
|
-------------------------------------
|
|
|
|
procedure Expand_Iterator_Loop_Over_Array (N : Node_Id) is
|
|
Isc : constant Node_Id := Iteration_Scheme (N);
|
|
I_Spec : constant Node_Id := Iterator_Specification (Isc);
|
|
Array_Node : constant Node_Id := Name (I_Spec);
|
|
Array_Typ : constant Entity_Id := Base_Type (Etype (Array_Node));
|
|
Array_Dim : constant Pos := Number_Dimensions (Array_Typ);
|
|
Id : constant Entity_Id := Defining_Identifier (I_Spec);
|
|
Loc : constant Source_Ptr := Sloc (N);
|
|
Stats : constant List_Id := Statements (N);
|
|
Core_Loop : Node_Id;
|
|
Dim1 : Int;
|
|
Ind_Comp : Node_Id;
|
|
Iterator : Entity_Id;
|
|
|
|
-- Start of processing for Expand_Iterator_Loop_Over_Array
|
|
|
|
begin
|
|
-- for Element of Array loop
|
|
|
|
-- It requires an internally generated cursor to iterate over the array
|
|
|
|
pragma Assert (Of_Present (I_Spec));
|
|
|
|
Iterator := Make_Temporary (Loc, 'C');
|
|
|
|
-- Generate:
|
|
-- Element : Component_Type renames Array (Iterator);
|
|
-- Iterator is the index value, or a list of index values
|
|
-- in the case of a multidimensional array.
|
|
|
|
Ind_Comp :=
|
|
Make_Indexed_Component (Loc,
|
|
Prefix => Relocate_Node (Array_Node),
|
|
Expressions => New_List (New_Occurrence_Of (Iterator, Loc)));
|
|
|
|
Prepend_To (Stats,
|
|
Make_Object_Renaming_Declaration (Loc,
|
|
Defining_Identifier => Id,
|
|
Subtype_Mark =>
|
|
New_Occurrence_Of (Component_Type (Array_Typ), Loc),
|
|
Name => Ind_Comp));
|
|
|
|
-- Mark the loop variable as needing debug info, so that expansion
|
|
-- of the renaming will result in Materialize_Entity getting set via
|
|
-- Debug_Renaming_Declaration. (This setting is needed here because
|
|
-- the setting in Freeze_Entity comes after the expansion, which is
|
|
-- too late. ???)
|
|
|
|
Set_Debug_Info_Needed (Id);
|
|
|
|
-- Generate:
|
|
|
|
-- for Iterator in [reverse] Array'Range (Array_Dim) loop
|
|
-- Element : Component_Type renames Array (Iterator);
|
|
-- <original loop statements>
|
|
-- end loop;
|
|
|
|
-- If this is an iteration over a multidimensional array, the
|
|
-- innermost loop is over the last dimension in Ada, and over
|
|
-- the first dimension in Fortran.
|
|
|
|
if Convention (Array_Typ) = Convention_Fortran then
|
|
Dim1 := 1;
|
|
else
|
|
Dim1 := Array_Dim;
|
|
end if;
|
|
|
|
Core_Loop :=
|
|
Make_Loop_Statement (Loc,
|
|
Iteration_Scheme =>
|
|
Make_Iteration_Scheme (Loc,
|
|
Loop_Parameter_Specification =>
|
|
Make_Loop_Parameter_Specification (Loc,
|
|
Defining_Identifier => Iterator,
|
|
Discrete_Subtype_Definition =>
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix => Relocate_Node (Array_Node),
|
|
Attribute_Name => Name_Range,
|
|
Expressions => New_List (
|
|
Make_Integer_Literal (Loc, Dim1))),
|
|
Reverse_Present => Reverse_Present (I_Spec))),
|
|
Statements => Stats,
|
|
End_Label => Empty);
|
|
|
|
-- Processing for multidimensional array. The body of each loop is
|
|
-- a loop over a previous dimension, going in decreasing order in Ada
|
|
-- and in increasing order in Fortran.
|
|
|
|
if Array_Dim > 1 then
|
|
for Dim in 1 .. Array_Dim - 1 loop
|
|
if Convention (Array_Typ) = Convention_Fortran then
|
|
Dim1 := Dim + 1;
|
|
else
|
|
Dim1 := Array_Dim - Dim;
|
|
end if;
|
|
|
|
Iterator := Make_Temporary (Loc, 'C');
|
|
|
|
-- Generate the dimension loops starting from the innermost one
|
|
|
|
-- for Iterator in [reverse] Array'Range (Array_Dim - Dim) loop
|
|
-- <core loop>
|
|
-- end loop;
|
|
|
|
Core_Loop :=
|
|
Make_Loop_Statement (Loc,
|
|
Iteration_Scheme =>
|
|
Make_Iteration_Scheme (Loc,
|
|
Loop_Parameter_Specification =>
|
|
Make_Loop_Parameter_Specification (Loc,
|
|
Defining_Identifier => Iterator,
|
|
Discrete_Subtype_Definition =>
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix => Relocate_Node (Array_Node),
|
|
Attribute_Name => Name_Range,
|
|
Expressions => New_List (
|
|
Make_Integer_Literal (Loc, Dim1))),
|
|
Reverse_Present => Reverse_Present (I_Spec))),
|
|
Statements => New_List (Core_Loop),
|
|
End_Label => Empty);
|
|
|
|
-- Update the previously created object renaming declaration with
|
|
-- the new iterator, by adding the index of the next loop to the
|
|
-- indexed component, in the order that corresponds to the
|
|
-- convention.
|
|
|
|
if Convention (Array_Typ) = Convention_Fortran then
|
|
Append_To (Expressions (Ind_Comp),
|
|
New_Occurrence_Of (Iterator, Loc));
|
|
else
|
|
Prepend_To (Expressions (Ind_Comp),
|
|
New_Occurrence_Of (Iterator, Loc));
|
|
end if;
|
|
end loop;
|
|
end if;
|
|
|
|
-- Inherit the loop identifier from the original loop. This ensures that
|
|
-- the scope stack is consistent after the rewriting.
|
|
|
|
if Present (Identifier (N)) then
|
|
Set_Identifier (Core_Loop, Relocate_Node (Identifier (N)));
|
|
end if;
|
|
|
|
Rewrite (N, Core_Loop);
|
|
Analyze (N);
|
|
end Expand_Iterator_Loop_Over_Array;
|
|
|
|
-----------------------------------------
|
|
-- Expand_Iterator_Loop_Over_Container --
|
|
-----------------------------------------
|
|
|
|
-- For a 'for ... in' loop, such as:
|
|
|
|
-- for Cursor in Iterator_Function (...) loop
|
|
-- ...
|
|
-- end loop;
|
|
|
|
-- we generate:
|
|
|
|
-- Iter : Iterator_Type := Iterator_Function (...);
|
|
-- Cursor : Cursor_type := First (Iter); -- or Last for "reverse"
|
|
-- while Has_Element (Cursor) loop
|
|
-- ...
|
|
--
|
|
-- Cursor := Iter.Next (Cursor); -- or Prev for "reverse"
|
|
-- end loop;
|
|
|
|
-- For a 'for ... of' loop, such as:
|
|
|
|
-- for X of Container loop
|
|
-- ...
|
|
-- end loop;
|
|
|
|
-- the RM implies the generation of:
|
|
|
|
-- Iter : Iterator_Type := Container.Iterate; -- the Default_Iterator
|
|
-- Cursor : Cursor_Type := First (Iter); -- or Last for "reverse"
|
|
-- while Has_Element (Cursor) loop
|
|
-- declare
|
|
-- X : Element_Type renames Element (Cursor).Element.all;
|
|
-- -- or Constant_Element
|
|
-- begin
|
|
-- ...
|
|
-- end;
|
|
-- Cursor := Iter.Next (Cursor); -- or Prev for "reverse"
|
|
-- end loop;
|
|
|
|
-- In the general case, we do what the RM says. However, the operations
|
|
-- Element and Iter.Next are slow, which is bad inside a loop, because they
|
|
-- involve dispatching via interfaces, secondary stack manipulation,
|
|
-- Busy/Lock incr/decr, and adjust/finalization/at-end handling. So for the
|
|
-- predefined containers, we use an equivalent but optimized expansion.
|
|
|
|
-- In the optimized case, we make use of these:
|
|
|
|
-- procedure Next (Position : in out Cursor); -- instead of Iter.Next
|
|
|
|
-- function Pseudo_Reference
|
|
-- (Container : aliased Vector'Class) return Reference_Control_Type;
|
|
|
|
-- type Element_Access is access all Element_Type;
|
|
|
|
-- function Get_Element_Access
|
|
-- (Position : Cursor) return not null Element_Access;
|
|
|
|
-- Next is declared in the visible part of the container packages.
|
|
-- The other three are added in the private part. (We're not supposed to
|
|
-- pollute the namespace for clients. The compiler has no trouble breaking
|
|
-- privacy to call things in the private part of an instance.)
|
|
|
|
-- Source:
|
|
|
|
-- for X of My_Vector loop
|
|
-- X.Count := X.Count + 1;
|
|
-- ...
|
|
-- end loop;
|
|
|
|
-- The compiler will generate:
|
|
|
|
-- Iter : Reversible_Iterator'Class := Iterate (My_Vector);
|
|
-- -- Reversible_Iterator is an interface. Iterate is the
|
|
-- -- Default_Iterator aspect of Vector. This increments Lock,
|
|
-- -- disallowing tampering with cursors. Unfortunately, it does not
|
|
-- -- increment Busy. The result of Iterate is Limited_Controlled;
|
|
-- -- finalization will decrement Lock. This is a build-in-place
|
|
-- -- dispatching call to Iterate.
|
|
|
|
-- Cur : Cursor := First (Iter); -- or Last
|
|
-- -- Dispatching call via interface.
|
|
|
|
-- Control : Reference_Control_Type := Pseudo_Reference (My_Vector);
|
|
-- -- Pseudo_Reference increments Busy, to detect tampering with
|
|
-- -- elements, as required by RM. Also redundantly increment
|
|
-- -- Lock. Finalization of Control will decrement both Busy and
|
|
-- -- Lock. Pseudo_Reference returns a record containing a pointer to
|
|
-- -- My_Vector, used by Finalize.
|
|
-- --
|
|
-- -- Control is not used below, except to finalize it -- it's purely
|
|
-- -- an RAII thing. This is needed because we are eliminating the
|
|
-- -- call to Reference within the loop.
|
|
|
|
-- while Has_Element (Cur) loop
|
|
-- declare
|
|
-- X : My_Element renames Get_Element_Access (Cur).all;
|
|
-- -- Get_Element_Access returns a pointer to the element
|
|
-- -- designated by Cur. No dispatching here, and no horsing
|
|
-- -- around with access discriminants. This is instead of the
|
|
-- -- existing
|
|
-- --
|
|
-- -- X : My_Element renames Reference (Cur).Element.all;
|
|
-- --
|
|
-- -- which creates a controlled object.
|
|
-- begin
|
|
-- -- Any attempt to tamper with My_Vector here in the loop
|
|
-- -- will correctly raise Program_Error, because of the
|
|
-- -- Control.
|
|
--
|
|
-- X.Count := X.Count + 1;
|
|
-- ...
|
|
--
|
|
-- Next (Cur); -- or Prev
|
|
-- -- This is instead of "Cur := Next (Iter, Cur);"
|
|
-- end;
|
|
-- -- No finalization here
|
|
-- end loop;
|
|
-- Finalize Iter and Control here, decrementing Lock twice and Busy
|
|
-- once.
|
|
|
|
-- This optimization makes "for ... of" loops over 30 times faster in cases
|
|
-- measured.
|
|
|
|
procedure Expand_Iterator_Loop_Over_Container
|
|
(N : Node_Id;
|
|
Isc : Node_Id;
|
|
I_Spec : Node_Id;
|
|
Container : Node_Id;
|
|
Container_Typ : Entity_Id)
|
|
is
|
|
Id : constant Entity_Id := Defining_Identifier (I_Spec);
|
|
Elem_Typ : constant Entity_Id := Etype (Id);
|
|
Id_Kind : constant Entity_Kind := Ekind (Id);
|
|
Loc : constant Source_Ptr := Sloc (N);
|
|
Stats : constant List_Id := Statements (N);
|
|
|
|
Cursor : Entity_Id;
|
|
Decl : Node_Id;
|
|
Iter_Type : Entity_Id;
|
|
Iterator : Entity_Id;
|
|
Name_Init : Name_Id;
|
|
Name_Step : Name_Id;
|
|
New_Loop : Node_Id;
|
|
|
|
Fast_Element_Access_Op : Entity_Id := Empty;
|
|
Fast_Step_Op : Entity_Id := Empty;
|
|
-- Only for optimized version of "for ... of"
|
|
|
|
Iter_Pack : Entity_Id;
|
|
-- The package in which the iterator interface is instantiated. This is
|
|
-- typically an instance within the container package.
|
|
|
|
Pack : Entity_Id;
|
|
-- The package in which the container type is declared
|
|
|
|
begin
|
|
-- Determine the advancement and initialization steps for the cursor.
|
|
-- Analysis of the expanded loop will verify that the container has a
|
|
-- reverse iterator.
|
|
|
|
if Reverse_Present (I_Spec) then
|
|
Name_Init := Name_Last;
|
|
Name_Step := Name_Previous;
|
|
else
|
|
Name_Init := Name_First;
|
|
Name_Step := Name_Next;
|
|
end if;
|
|
|
|
-- The type of the iterator is the return type of the Iterate function
|
|
-- used. For the "of" form this is the default iterator for the type,
|
|
-- otherwise it is the type of the explicit function used in the
|
|
-- iterator specification. The most common case will be an Iterate
|
|
-- function in the container package.
|
|
|
|
-- The Iterator type is declared in an instance within the container
|
|
-- package itself, for example:
|
|
|
|
-- package Vector_Iterator_Interfaces is new
|
|
-- Ada.Iterator_Interfaces (Cursor, Has_Element);
|
|
|
|
-- If the container type is a derived type, the cursor type is found in
|
|
-- the package of the ultimate ancestor type.
|
|
|
|
if Is_Derived_Type (Container_Typ) then
|
|
Pack := Scope (Root_Type (Container_Typ));
|
|
else
|
|
Pack := Scope (Container_Typ);
|
|
end if;
|
|
|
|
if Of_Present (I_Spec) then
|
|
Handle_Of : declare
|
|
Container_Arg : Node_Id;
|
|
|
|
function Get_Default_Iterator
|
|
(T : Entity_Id) return Entity_Id;
|
|
-- If the container is a derived type, the aspect holds the parent
|
|
-- operation. The required one is a primitive of the derived type
|
|
-- and is either inherited or overridden. Also sets Container_Arg.
|
|
|
|
--------------------------
|
|
-- Get_Default_Iterator --
|
|
--------------------------
|
|
|
|
function Get_Default_Iterator
|
|
(T : Entity_Id) return Entity_Id
|
|
is
|
|
Iter : constant Entity_Id :=
|
|
Entity (Find_Value_Of_Aspect (T, Aspect_Default_Iterator));
|
|
Prim : Elmt_Id;
|
|
Op : Entity_Id;
|
|
|
|
begin
|
|
Container_Arg := New_Copy_Tree (Container);
|
|
|
|
-- A previous version of GNAT allowed indexing aspects to
|
|
-- be redefined on derived container types, while the
|
|
-- default iterator was inherited from the parent type.
|
|
-- This non-standard extension is preserved temporarily for
|
|
-- use by the modelling project under debug flag d.X.
|
|
|
|
if Debug_Flag_Dot_XX then
|
|
if Base_Type (Etype (Container)) /=
|
|
Base_Type (Etype (First_Formal (Iter)))
|
|
then
|
|
Container_Arg :=
|
|
Make_Type_Conversion (Loc,
|
|
Subtype_Mark =>
|
|
New_Occurrence_Of
|
|
(Etype (First_Formal (Iter)), Loc),
|
|
Expression => Container_Arg);
|
|
end if;
|
|
|
|
return Iter;
|
|
|
|
elsif Is_Derived_Type (T) then
|
|
|
|
-- The default iterator must be a primitive operation of the
|
|
-- type, at the same dispatch slot position.
|
|
|
|
Prim := First_Elmt (Primitive_Operations (T));
|
|
while Present (Prim) loop
|
|
Op := Node (Prim);
|
|
|
|
if Chars (Op) = Chars (Iter)
|
|
and then DT_Position (Op) = DT_Position (Iter)
|
|
then
|
|
return Op;
|
|
end if;
|
|
|
|
Next_Elmt (Prim);
|
|
end loop;
|
|
|
|
-- Default iterator must exist
|
|
|
|
pragma Assert (False);
|
|
|
|
-- Otherwise not a derived type
|
|
|
|
else
|
|
return Iter;
|
|
end if;
|
|
end Get_Default_Iterator;
|
|
|
|
-- Local variables
|
|
|
|
Default_Iter : Entity_Id;
|
|
Ent : Entity_Id;
|
|
|
|
Reference_Control_Type : Entity_Id := Empty;
|
|
Pseudo_Reference : Entity_Id := Empty;
|
|
|
|
-- Start of processing for Handle_Of
|
|
|
|
begin
|
|
if Is_Class_Wide_Type (Container_Typ) then
|
|
Default_Iter :=
|
|
Get_Default_Iterator (Etype (Base_Type (Container_Typ)));
|
|
else
|
|
Default_Iter := Get_Default_Iterator (Etype (Container));
|
|
end if;
|
|
|
|
Cursor := Make_Temporary (Loc, 'C');
|
|
|
|
-- For a container element iterator, the iterator type is obtained
|
|
-- from the corresponding aspect, whose return type is descended
|
|
-- from the corresponding interface type in some instance of
|
|
-- Ada.Iterator_Interfaces. The actuals of that instantiation
|
|
-- are Cursor and Has_Element.
|
|
|
|
Iter_Type := Etype (Default_Iter);
|
|
|
|
-- The iterator type, which is a class-wide type, may itself be
|
|
-- derived locally, so the desired instantiation is the scope of
|
|
-- the root type of the iterator type.
|
|
|
|
Iter_Pack := Scope (Root_Type (Etype (Iter_Type)));
|
|
|
|
-- Find declarations needed for "for ... of" optimization
|
|
|
|
Ent := First_Entity (Pack);
|
|
while Present (Ent) loop
|
|
if Chars (Ent) = Name_Get_Element_Access then
|
|
Fast_Element_Access_Op := Ent;
|
|
|
|
elsif Chars (Ent) = Name_Step
|
|
and then Ekind (Ent) = E_Procedure
|
|
then
|
|
Fast_Step_Op := Ent;
|
|
|
|
elsif Chars (Ent) = Name_Reference_Control_Type then
|
|
Reference_Control_Type := Ent;
|
|
|
|
elsif Chars (Ent) = Name_Pseudo_Reference then
|
|
Pseudo_Reference := Ent;
|
|
end if;
|
|
|
|
Next_Entity (Ent);
|
|
end loop;
|
|
|
|
if Present (Reference_Control_Type)
|
|
and then Present (Pseudo_Reference)
|
|
then
|
|
Insert_Action (N,
|
|
Make_Object_Declaration (Loc,
|
|
Defining_Identifier => Make_Temporary (Loc, 'D'),
|
|
Object_Definition =>
|
|
New_Occurrence_Of (Reference_Control_Type, Loc),
|
|
Expression =>
|
|
Make_Function_Call (Loc,
|
|
Name =>
|
|
New_Occurrence_Of (Pseudo_Reference, Loc),
|
|
Parameter_Associations =>
|
|
New_List (New_Copy_Tree (Container_Arg)))));
|
|
end if;
|
|
|
|
-- Rewrite domain of iteration as a call to the default iterator
|
|
-- for the container type. The formal may be an access parameter
|
|
-- in which case we must build a reference to the container.
|
|
|
|
declare
|
|
Arg : Node_Id;
|
|
begin
|
|
if Is_Access_Type (Etype (First_Entity (Default_Iter))) then
|
|
Arg :=
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix => Container_Arg,
|
|
Attribute_Name => Name_Unrestricted_Access);
|
|
else
|
|
Arg := Container_Arg;
|
|
end if;
|
|
|
|
Rewrite (Name (I_Spec),
|
|
Make_Function_Call (Loc,
|
|
Name =>
|
|
New_Occurrence_Of (Default_Iter, Loc),
|
|
Parameter_Associations => New_List (Arg)));
|
|
end;
|
|
|
|
Analyze_And_Resolve (Name (I_Spec));
|
|
|
|
-- Find cursor type in proper iterator package, which is an
|
|
-- instantiation of Iterator_Interfaces.
|
|
|
|
Ent := First_Entity (Iter_Pack);
|
|
while Present (Ent) loop
|
|
if Chars (Ent) = Name_Cursor then
|
|
Set_Etype (Cursor, Etype (Ent));
|
|
exit;
|
|
end if;
|
|
|
|
Next_Entity (Ent);
|
|
end loop;
|
|
|
|
if Present (Fast_Element_Access_Op) then
|
|
Decl :=
|
|
Make_Object_Renaming_Declaration (Loc,
|
|
Defining_Identifier => Id,
|
|
Subtype_Mark =>
|
|
New_Occurrence_Of (Elem_Typ, Loc),
|
|
Name =>
|
|
Make_Explicit_Dereference (Loc,
|
|
Prefix =>
|
|
Make_Function_Call (Loc,
|
|
Name =>
|
|
New_Occurrence_Of (Fast_Element_Access_Op, Loc),
|
|
Parameter_Associations =>
|
|
New_List (New_Occurrence_Of (Cursor, Loc)))));
|
|
|
|
else
|
|
Decl :=
|
|
Make_Object_Renaming_Declaration (Loc,
|
|
Defining_Identifier => Id,
|
|
Subtype_Mark =>
|
|
New_Occurrence_Of (Elem_Typ, Loc),
|
|
Name =>
|
|
Make_Indexed_Component (Loc,
|
|
Prefix => Relocate_Node (Container_Arg),
|
|
Expressions =>
|
|
New_List (New_Occurrence_Of (Cursor, Loc))));
|
|
end if;
|
|
|
|
-- The defining identifier in the iterator is user-visible and
|
|
-- must be visible in the debugger.
|
|
|
|
Set_Debug_Info_Needed (Id);
|
|
|
|
-- If the container does not have a variable indexing aspect,
|
|
-- the element is a constant in the loop. The container itself
|
|
-- may be constant, in which case the element is a constant as
|
|
-- well. The container has been rewritten as a call to Iterate,
|
|
-- so examine original node.
|
|
|
|
if No (Find_Value_Of_Aspect
|
|
(Container_Typ, Aspect_Variable_Indexing))
|
|
or else not Is_Variable (Original_Node (Container))
|
|
then
|
|
Set_Ekind (Id, E_Constant);
|
|
end if;
|
|
|
|
Prepend_To (Stats, Decl);
|
|
end Handle_Of;
|
|
|
|
-- X in Iterate (S) : type of iterator is type of explicitly given
|
|
-- Iterate function, and the loop variable is the cursor. It will be
|
|
-- assigned in the loop and must be a variable.
|
|
|
|
else
|
|
Iter_Type := Etype (Name (I_Spec));
|
|
|
|
-- The iterator type, which is a class-wide type, may itself be
|
|
-- derived locally, so the desired instantiation is the scope of
|
|
-- the root type of the iterator type, as in the "of" case.
|
|
|
|
Iter_Pack := Scope (Root_Type (Etype (Iter_Type)));
|
|
Cursor := Id;
|
|
end if;
|
|
|
|
Iterator := Make_Temporary (Loc, 'I');
|
|
|
|
-- For both iterator forms, add a call to the step operation to advance
|
|
-- the cursor. Generate:
|
|
|
|
-- Cursor := Iterator.Next (Cursor);
|
|
|
|
-- or else
|
|
|
|
-- Cursor := Next (Cursor);
|
|
|
|
if Present (Fast_Element_Access_Op) and then Present (Fast_Step_Op) then
|
|
declare
|
|
Curs_Name : constant Node_Id := New_Occurrence_Of (Cursor, Loc);
|
|
Step_Call : Node_Id;
|
|
|
|
begin
|
|
Step_Call :=
|
|
Make_Procedure_Call_Statement (Loc,
|
|
Name =>
|
|
New_Occurrence_Of (Fast_Step_Op, Loc),
|
|
Parameter_Associations => New_List (Curs_Name));
|
|
|
|
Append_To (Stats, Step_Call);
|
|
Set_Assignment_OK (Curs_Name);
|
|
end;
|
|
|
|
else
|
|
declare
|
|
Rhs : Node_Id;
|
|
|
|
begin
|
|
Rhs :=
|
|
Make_Function_Call (Loc,
|
|
Name =>
|
|
Make_Selected_Component (Loc,
|
|
Prefix => New_Occurrence_Of (Iterator, Loc),
|
|
Selector_Name => Make_Identifier (Loc, Name_Step)),
|
|
Parameter_Associations => New_List (
|
|
New_Occurrence_Of (Cursor, Loc)));
|
|
|
|
Append_To (Stats,
|
|
Make_Assignment_Statement (Loc,
|
|
Name => New_Occurrence_Of (Cursor, Loc),
|
|
Expression => Rhs));
|
|
Set_Assignment_OK (Name (Last (Stats)));
|
|
end;
|
|
end if;
|
|
|
|
-- Generate:
|
|
-- while Has_Element (Cursor) loop
|
|
-- <Stats>
|
|
-- end loop;
|
|
|
|
-- Has_Element is the second actual in the iterator package
|
|
|
|
New_Loop :=
|
|
Make_Loop_Statement (Loc,
|
|
Iteration_Scheme =>
|
|
Make_Iteration_Scheme (Loc,
|
|
Condition =>
|
|
Make_Function_Call (Loc,
|
|
Name =>
|
|
New_Occurrence_Of
|
|
(Next_Entity (First_Entity (Iter_Pack)), Loc),
|
|
Parameter_Associations => New_List (
|
|
New_Occurrence_Of (Cursor, Loc)))),
|
|
|
|
Statements => Stats,
|
|
End_Label => Empty);
|
|
|
|
-- If present, preserve identifier of loop, which can be used in an exit
|
|
-- statement in the body.
|
|
|
|
if Present (Identifier (N)) then
|
|
Set_Identifier (New_Loop, Relocate_Node (Identifier (N)));
|
|
end if;
|
|
|
|
-- Create the declarations for Iterator and cursor and insert them
|
|
-- before the source loop. Given that the domain of iteration is already
|
|
-- an entity, the iterator is just a renaming of that entity. Possible
|
|
-- optimization ???
|
|
|
|
Insert_Action (N,
|
|
Make_Object_Renaming_Declaration (Loc,
|
|
Defining_Identifier => Iterator,
|
|
Subtype_Mark => New_Occurrence_Of (Iter_Type, Loc),
|
|
Name => Relocate_Node (Name (I_Spec))));
|
|
|
|
-- Create declaration for cursor
|
|
|
|
declare
|
|
Cursor_Decl : constant Node_Id :=
|
|
Make_Object_Declaration (Loc,
|
|
Defining_Identifier => Cursor,
|
|
Object_Definition =>
|
|
New_Occurrence_Of (Etype (Cursor), Loc),
|
|
Expression =>
|
|
Make_Selected_Component (Loc,
|
|
Prefix =>
|
|
New_Occurrence_Of (Iterator, Loc),
|
|
Selector_Name =>
|
|
Make_Identifier (Loc, Name_Init)));
|
|
|
|
begin
|
|
-- The cursor is only modified in expanded code, so it appears
|
|
-- as unassigned to the warning machinery. We must suppress this
|
|
-- spurious warning explicitly. The cursor's kind is that of the
|
|
-- original loop parameter (it is a constant if the domain of
|
|
-- iteration is constant).
|
|
|
|
Set_Warnings_Off (Cursor);
|
|
Set_Assignment_OK (Cursor_Decl);
|
|
|
|
Insert_Action (N, Cursor_Decl);
|
|
Set_Ekind (Cursor, Id_Kind);
|
|
end;
|
|
|
|
-- If the range of iteration is given by a function call that returns
|
|
-- a container, the finalization actions have been saved in the
|
|
-- Condition_Actions of the iterator. Insert them now at the head of
|
|
-- the loop.
|
|
|
|
if Present (Condition_Actions (Isc)) then
|
|
Insert_List_Before (N, Condition_Actions (Isc));
|
|
end if;
|
|
|
|
Rewrite (N, New_Loop);
|
|
Analyze (N);
|
|
end Expand_Iterator_Loop_Over_Container;
|
|
|
|
-----------------------------
|
|
-- Expand_N_Loop_Statement --
|
|
-----------------------------
|
|
|
|
-- 1. Remove null loop entirely
|
|
-- 2. Deal with while condition for C/Fortran boolean
|
|
-- 3. Deal with loops with a non-standard enumeration type range
|
|
-- 4. Deal with while loops where Condition_Actions is set
|
|
-- 5. Deal with loops over predicated subtypes
|
|
-- 6. Deal with loops with iterators over arrays and containers
|
|
-- 7. Insert polling call if required
|
|
|
|
procedure Expand_N_Loop_Statement (N : Node_Id) is
|
|
Loc : constant Source_Ptr := Sloc (N);
|
|
Scheme : constant Node_Id := Iteration_Scheme (N);
|
|
Stmt : Node_Id;
|
|
|
|
begin
|
|
-- Delete null loop
|
|
|
|
if Is_Null_Loop (N) then
|
|
Rewrite (N, Make_Null_Statement (Loc));
|
|
return;
|
|
end if;
|
|
|
|
-- Deal with condition for C/Fortran Boolean
|
|
|
|
if Present (Scheme) then
|
|
Adjust_Condition (Condition (Scheme));
|
|
end if;
|
|
|
|
-- Generate polling call
|
|
|
|
if Is_Non_Empty_List (Statements (N)) then
|
|
Generate_Poll_Call (First (Statements (N)));
|
|
end if;
|
|
|
|
-- Nothing more to do for plain loop with no iteration scheme
|
|
|
|
if No (Scheme) then
|
|
null;
|
|
|
|
-- Case of for loop (Loop_Parameter_Specification present)
|
|
|
|
-- Note: we do not have to worry about validity checking of the for loop
|
|
-- range bounds here, since they were frozen with constant declarations
|
|
-- and it is during that process that the validity checking is done.
|
|
|
|
elsif Present (Loop_Parameter_Specification (Scheme)) then
|
|
declare
|
|
LPS : constant Node_Id :=
|
|
Loop_Parameter_Specification (Scheme);
|
|
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;
|
|
Decls : List_Id;
|
|
New_Id : Entity_Id;
|
|
|
|
begin
|
|
-- Deal with loop over predicates
|
|
|
|
if Is_Discrete_Type (Ltype)
|
|
and then Present (Predicate_Function (Ltype))
|
|
then
|
|
Expand_Predicated_Loop (N);
|
|
|
|
-- Handle the case where we have a for loop with the range type
|
|
-- being an enumeration type with non-standard representation.
|
|
-- In this case we expand:
|
|
|
|
-- for x in [reverse] a .. b loop
|
|
-- ...
|
|
-- end loop;
|
|
|
|
-- to
|
|
|
|
-- for xP in [reverse] integer
|
|
-- range etype'Pos (a) .. etype'Pos (b)
|
|
-- loop
|
|
-- declare
|
|
-- x : constant etype := Pos_To_Rep (xP);
|
|
-- begin
|
|
-- ...
|
|
-- end;
|
|
-- end loop;
|
|
|
|
elsif Is_Enumeration_Type (Btype)
|
|
and then Present (Enum_Pos_To_Rep (Btype))
|
|
then
|
|
New_Id :=
|
|
Make_Defining_Identifier (Loc,
|
|
Chars => New_External_Name (Chars (Loop_Id), 'P'));
|
|
|
|
-- If the type has a contiguous representation, successive
|
|
-- values can be generated as offsets from the first literal.
|
|
|
|
if Has_Contiguous_Rep (Btype) then
|
|
Expr :=
|
|
Unchecked_Convert_To (Btype,
|
|
Make_Op_Add (Loc,
|
|
Left_Opnd =>
|
|
Make_Integer_Literal (Loc,
|
|
Enumeration_Rep (First_Literal (Btype))),
|
|
Right_Opnd => New_Occurrence_Of (New_Id, Loc)));
|
|
else
|
|
-- Use the constructed array Enum_Pos_To_Rep
|
|
|
|
Expr :=
|
|
Make_Indexed_Component (Loc,
|
|
Prefix =>
|
|
New_Occurrence_Of (Enum_Pos_To_Rep (Btype), Loc),
|
|
Expressions =>
|
|
New_List (New_Occurrence_Of (New_Id, Loc)));
|
|
end if;
|
|
|
|
-- Build declaration for loop identifier
|
|
|
|
Decls :=
|
|
New_List (
|
|
Make_Object_Declaration (Loc,
|
|
Defining_Identifier => Loop_Id,
|
|
Constant_Present => True,
|
|
Object_Definition => New_Occurrence_Of (Ltype, Loc),
|
|
Expression => Expr));
|
|
|
|
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_Occurrence_Of (Standard_Natural, Loc),
|
|
|
|
Constraint =>
|
|
Make_Range_Constraint (Loc,
|
|
Range_Expression =>
|
|
Make_Range (Loc,
|
|
|
|
Low_Bound =>
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix =>
|
|
New_Occurrence_Of (Btype, Loc),
|
|
|
|
Attribute_Name => Name_Pos,
|
|
|
|
Expressions => New_List (
|
|
Relocate_Node
|
|
(Type_Low_Bound (Ltype)))),
|
|
|
|
High_Bound =>
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix =>
|
|
New_Occurrence_Of (Btype, Loc),
|
|
|
|
Attribute_Name => Name_Pos,
|
|
|
|
Expressions => New_List (
|
|
Relocate_Node
|
|
(Type_High_Bound
|
|
(Ltype))))))))),
|
|
|
|
Statements => New_List (
|
|
Make_Block_Statement (Loc,
|
|
Declarations => Decls,
|
|
Handled_Statement_Sequence =>
|
|
Make_Handled_Sequence_Of_Statements (Loc,
|
|
Statements => Statements (N)))),
|
|
|
|
End_Label => End_Label (N)));
|
|
|
|
-- The loop parameter's entity must be removed from the loop
|
|
-- scope's entity list and rendered invisible, since it will
|
|
-- now be located in the new block scope. Any other entities
|
|
-- already associated with the loop scope, such as the loop
|
|
-- parameter's subtype, will remain there.
|
|
|
|
-- In an element loop, the loop will contain a declaration for
|
|
-- a cursor variable; otherwise the loop id is the first entity
|
|
-- in the scope constructed for the loop.
|
|
|
|
if Comes_From_Source (Loop_Id) then
|
|
pragma Assert (First_Entity (Scope (Loop_Id)) = Loop_Id);
|
|
null;
|
|
end if;
|
|
|
|
Set_First_Entity (Scope (Loop_Id), Next_Entity (Loop_Id));
|
|
Remove_Homonym (Loop_Id);
|
|
|
|
if Last_Entity (Scope (Loop_Id)) = Loop_Id then
|
|
Set_Last_Entity (Scope (Loop_Id), Empty);
|
|
end if;
|
|
|
|
Analyze (N);
|
|
|
|
-- Nothing to do with other cases of for loops
|
|
|
|
else
|
|
null;
|
|
end if;
|
|
end;
|
|
|
|
-- Second case, if we have a while loop with Condition_Actions set, then
|
|
-- we change it into a plain loop:
|
|
|
|
-- while C loop
|
|
-- ...
|
|
-- end loop;
|
|
|
|
-- changed to:
|
|
|
|
-- loop
|
|
-- <<condition actions>>
|
|
-- exit when not C;
|
|
-- ...
|
|
-- end loop
|
|
|
|
elsif Present (Scheme)
|
|
and then Present (Condition_Actions (Scheme))
|
|
and then Present (Condition (Scheme))
|
|
then
|
|
declare
|
|
ES : Node_Id;
|
|
|
|
begin
|
|
ES :=
|
|
Make_Exit_Statement (Sloc (Condition (Scheme)),
|
|
Condition =>
|
|
Make_Op_Not (Sloc (Condition (Scheme)),
|
|
Right_Opnd => Condition (Scheme)));
|
|
|
|
Prepend (ES, Statements (N));
|
|
Insert_List_Before (ES, Condition_Actions (Scheme));
|
|
|
|
-- This is not an implicit loop, since it is generated in response
|
|
-- to the loop statement being processed. If this is itself
|
|
-- implicit, the restriction has already been checked. If not,
|
|
-- it is an explicit loop.
|
|
|
|
Rewrite (N,
|
|
Make_Loop_Statement (Sloc (N),
|
|
Identifier => Identifier (N),
|
|
Statements => Statements (N),
|
|
End_Label => End_Label (N)));
|
|
|
|
Analyze (N);
|
|
end;
|
|
|
|
-- Here to deal with iterator case
|
|
|
|
elsif Present (Scheme)
|
|
and then Present (Iterator_Specification (Scheme))
|
|
then
|
|
Expand_Iterator_Loop (N);
|
|
|
|
-- An iterator loop may generate renaming declarations for elements
|
|
-- that require debug information. This is the case in particular
|
|
-- with element iterators, where debug information must be generated
|
|
-- for the temporary that holds the element value. These temporaries
|
|
-- are created within a transient block whose local declarations are
|
|
-- transferred to the loop, which now has nontrivial local objects.
|
|
|
|
if Nkind (N) = N_Loop_Statement
|
|
and then Present (Identifier (N))
|
|
then
|
|
Qualify_Entity_Names (N);
|
|
end if;
|
|
end if;
|
|
|
|
-- When the iteration scheme mentiones attribute 'Loop_Entry, the loop
|
|
-- is transformed into a conditional block where the original loop is
|
|
-- the sole statement. Inspect the statements of the nested loop for
|
|
-- controlled objects.
|
|
|
|
Stmt := N;
|
|
|
|
if Subject_To_Loop_Entry_Attributes (Stmt) then
|
|
Stmt := Find_Loop_In_Conditional_Block (Stmt);
|
|
end if;
|
|
|
|
Process_Statements_For_Controlled_Objects (Stmt);
|
|
end Expand_N_Loop_Statement;
|
|
|
|
----------------------------
|
|
-- Expand_Predicated_Loop --
|
|
----------------------------
|
|
|
|
-- Note: the expander can handle generation of loops over predicated
|
|
-- subtypes for both the dynamic and static cases. Depending on what
|
|
-- we decide is allowed in Ada 2012 mode and/or extensions allowed
|
|
-- mode, the semantic analyzer may disallow one or both forms.
|
|
|
|
procedure Expand_Predicated_Loop (N : Node_Id) is
|
|
Loc : constant Source_Ptr := Sloc (N);
|
|
Isc : constant Node_Id := Iteration_Scheme (N);
|
|
LPS : constant Node_Id := Loop_Parameter_Specification (Isc);
|
|
Loop_Id : constant Entity_Id := Defining_Identifier (LPS);
|
|
Ltype : constant Entity_Id := Etype (Loop_Id);
|
|
Stat : constant List_Id := Static_Discrete_Predicate (Ltype);
|
|
Stmts : constant List_Id := Statements (N);
|
|
|
|
begin
|
|
-- Case of iteration over non-static predicate, should not be possible
|
|
-- since this is not allowed by the semantics and should have been
|
|
-- caught during analysis of the loop statement.
|
|
|
|
if No (Stat) then
|
|
raise Program_Error;
|
|
|
|
-- If the predicate list is empty, that corresponds to a predicate of
|
|
-- False, in which case the loop won't run at all, and we rewrite the
|
|
-- entire loop as a null statement.
|
|
|
|
elsif Is_Empty_List (Stat) then
|
|
Rewrite (N, Make_Null_Statement (Loc));
|
|
Analyze (N);
|
|
|
|
-- For expansion over a static predicate we generate the following
|
|
|
|
-- declare
|
|
-- J : Ltype := min-val;
|
|
-- begin
|
|
-- loop
|
|
-- body
|
|
-- case J is
|
|
-- when endpoint => J := startpoint;
|
|
-- when endpoint => J := startpoint;
|
|
-- ...
|
|
-- when max-val => exit;
|
|
-- when others => J := Lval'Succ (J);
|
|
-- end case;
|
|
-- end loop;
|
|
-- end;
|
|
|
|
-- with min-val replaced by max-val and Succ replaced by Pred if the
|
|
-- loop parameter specification carries a Reverse indicator.
|
|
|
|
-- To make this a little clearer, let's take a specific example:
|
|
|
|
-- type Int is range 1 .. 10;
|
|
-- subtype StaticP is Int with
|
|
-- predicate => StaticP in 3 | 10 | 5 .. 7;
|
|
-- ...
|
|
-- for L in StaticP loop
|
|
-- Put_Line ("static:" & J'Img);
|
|
-- end loop;
|
|
|
|
-- In this case, the loop is transformed into
|
|
|
|
-- begin
|
|
-- J : L := 3;
|
|
-- loop
|
|
-- body
|
|
-- case J is
|
|
-- when 3 => J := 5;
|
|
-- when 7 => J := 10;
|
|
-- when 10 => exit;
|
|
-- when others => J := L'Succ (J);
|
|
-- end case;
|
|
-- end loop;
|
|
-- end;
|
|
|
|
else
|
|
Static_Predicate : declare
|
|
S : Node_Id;
|
|
D : Node_Id;
|
|
P : Node_Id;
|
|
Alts : List_Id;
|
|
Cstm : Node_Id;
|
|
|
|
function Lo_Val (N : Node_Id) return Node_Id;
|
|
-- Given static expression or static range, returns an identifier
|
|
-- whose value is the low bound of the expression value or range.
|
|
|
|
function Hi_Val (N : Node_Id) return Node_Id;
|
|
-- Given static expression or static range, returns an identifier
|
|
-- whose value is the high bound of the expression value or range.
|
|
|
|
------------
|
|
-- Hi_Val --
|
|
------------
|
|
|
|
function Hi_Val (N : Node_Id) return Node_Id is
|
|
begin
|
|
if Is_OK_Static_Expression (N) then
|
|
return New_Copy (N);
|
|
else
|
|
pragma Assert (Nkind (N) = N_Range);
|
|
return New_Copy (High_Bound (N));
|
|
end if;
|
|
end Hi_Val;
|
|
|
|
------------
|
|
-- Lo_Val --
|
|
------------
|
|
|
|
function Lo_Val (N : Node_Id) return Node_Id is
|
|
begin
|
|
if Is_OK_Static_Expression (N) then
|
|
return New_Copy (N);
|
|
else
|
|
pragma Assert (Nkind (N) = N_Range);
|
|
return New_Copy (Low_Bound (N));
|
|
end if;
|
|
end Lo_Val;
|
|
|
|
-- Start of processing for Static_Predicate
|
|
|
|
begin
|
|
-- Convert loop identifier to normal variable and reanalyze it so
|
|
-- that this conversion works. We have to use the same defining
|
|
-- identifier, since there may be references in the loop body.
|
|
|
|
Set_Analyzed (Loop_Id, False);
|
|
Set_Ekind (Loop_Id, E_Variable);
|
|
|
|
-- In most loops the loop variable is assigned in various
|
|
-- alternatives in the body. However, in the rare case when
|
|
-- the range specifies a single element, the loop variable
|
|
-- may trigger a spurious warning that is could be constant.
|
|
-- This warning might as well be suppressed.
|
|
|
|
Set_Warnings_Off (Loop_Id);
|
|
|
|
-- Loop to create branches of case statement
|
|
|
|
Alts := New_List;
|
|
|
|
if Reverse_Present (LPS) then
|
|
|
|
-- Initial value is largest value in predicate.
|
|
|
|
D :=
|
|
Make_Object_Declaration (Loc,
|
|
Defining_Identifier => Loop_Id,
|
|
Object_Definition => New_Occurrence_Of (Ltype, Loc),
|
|
Expression => Hi_Val (Last (Stat)));
|
|
|
|
P := Last (Stat);
|
|
while Present (P) loop
|
|
if No (Prev (P)) then
|
|
S := Make_Exit_Statement (Loc);
|
|
else
|
|
S :=
|
|
Make_Assignment_Statement (Loc,
|
|
Name => New_Occurrence_Of (Loop_Id, Loc),
|
|
Expression => Hi_Val (Prev (P)));
|
|
Set_Suppress_Assignment_Checks (S);
|
|
end if;
|
|
|
|
Append_To (Alts,
|
|
Make_Case_Statement_Alternative (Loc,
|
|
Statements => New_List (S),
|
|
Discrete_Choices => New_List (Lo_Val (P))));
|
|
|
|
Prev (P);
|
|
end loop;
|
|
|
|
else
|
|
|
|
-- Initial value is smallest value in predicate.
|
|
|
|
D :=
|
|
Make_Object_Declaration (Loc,
|
|
Defining_Identifier => Loop_Id,
|
|
Object_Definition => New_Occurrence_Of (Ltype, Loc),
|
|
Expression => Lo_Val (First (Stat)));
|
|
|
|
P := First (Stat);
|
|
while Present (P) loop
|
|
if No (Next (P)) then
|
|
S := Make_Exit_Statement (Loc);
|
|
else
|
|
S :=
|
|
Make_Assignment_Statement (Loc,
|
|
Name => New_Occurrence_Of (Loop_Id, Loc),
|
|
Expression => Lo_Val (Next (P)));
|
|
Set_Suppress_Assignment_Checks (S);
|
|
end if;
|
|
|
|
Append_To (Alts,
|
|
Make_Case_Statement_Alternative (Loc,
|
|
Statements => New_List (S),
|
|
Discrete_Choices => New_List (Hi_Val (P))));
|
|
|
|
Next (P);
|
|
end loop;
|
|
end if;
|
|
|
|
-- Add others choice
|
|
|
|
declare
|
|
Name_Next : Name_Id;
|
|
|
|
begin
|
|
if Reverse_Present (LPS) then
|
|
Name_Next := Name_Pred;
|
|
else
|
|
Name_Next := Name_Succ;
|
|
end if;
|
|
|
|
S :=
|
|
Make_Assignment_Statement (Loc,
|
|
Name => New_Occurrence_Of (Loop_Id, Loc),
|
|
Expression =>
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix => New_Occurrence_Of (Ltype, Loc),
|
|
Attribute_Name => Name_Next,
|
|
Expressions => New_List (
|
|
New_Occurrence_Of (Loop_Id, Loc))));
|
|
Set_Suppress_Assignment_Checks (S);
|
|
end;
|
|
|
|
Append_To (Alts,
|
|
Make_Case_Statement_Alternative (Loc,
|
|
Discrete_Choices => New_List (Make_Others_Choice (Loc)),
|
|
Statements => New_List (S)));
|
|
|
|
-- Construct case statement and append to body statements
|
|
|
|
Cstm :=
|
|
Make_Case_Statement (Loc,
|
|
Expression => New_Occurrence_Of (Loop_Id, Loc),
|
|
Alternatives => Alts);
|
|
Append_To (Stmts, Cstm);
|
|
|
|
-- Rewrite the loop
|
|
|
|
Set_Suppress_Assignment_Checks (D);
|
|
|
|
Rewrite (N,
|
|
Make_Block_Statement (Loc,
|
|
Declarations => New_List (D),
|
|
Handled_Statement_Sequence =>
|
|
Make_Handled_Sequence_Of_Statements (Loc,
|
|
Statements => New_List (
|
|
Make_Loop_Statement (Loc,
|
|
Statements => Stmts,
|
|
End_Label => Empty)))));
|
|
|
|
Analyze (N);
|
|
end Static_Predicate;
|
|
end if;
|
|
end Expand_Predicated_Loop;
|
|
|
|
------------------------------
|
|
-- Make_Tag_Ctrl_Assignment --
|
|
------------------------------
|
|
|
|
function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is
|
|
Asn : constant Node_Id := Relocate_Node (N);
|
|
L : constant Node_Id := Name (N);
|
|
Loc : constant Source_Ptr := Sloc (N);
|
|
Res : constant List_Id := New_List;
|
|
T : constant Entity_Id := Underlying_Type (Etype (L));
|
|
|
|
Comp_Asn : constant Boolean := Is_Fully_Repped_Tagged_Type (T);
|
|
Ctrl_Act : constant Boolean := Needs_Finalization (T)
|
|
and then not No_Ctrl_Actions (N);
|
|
Save_Tag : constant Boolean := Is_Tagged_Type (T)
|
|
and then not Comp_Asn
|
|
and then not No_Ctrl_Actions (N)
|
|
and then Tagged_Type_Expansion;
|
|
Tag_Id : Entity_Id;
|
|
|
|
begin
|
|
-- Finalize the target of the assignment when controlled
|
|
|
|
-- We have two exceptions here:
|
|
|
|
-- 1. If we are in an init proc since it is an initialization more
|
|
-- than an assignment.
|
|
|
|
-- 2. If the left-hand side is a temporary that was not initialized
|
|
-- (or the parent part of a temporary since it is the case in
|
|
-- extension aggregates). Such a temporary does not come from
|
|
-- source. We must examine the original node for the prefix, because
|
|
-- it may be a component of an entry formal, in which case it has
|
|
-- been rewritten and does not appear to come from source either.
|
|
|
|
-- Case of init proc
|
|
|
|
if not Ctrl_Act then
|
|
null;
|
|
|
|
-- The left hand side is an uninitialized temporary object
|
|
|
|
elsif Nkind (L) = N_Type_Conversion
|
|
and then Is_Entity_Name (Expression (L))
|
|
and then Nkind (Parent (Entity (Expression (L)))) =
|
|
N_Object_Declaration
|
|
and then No_Initialization (Parent (Entity (Expression (L))))
|
|
then
|
|
null;
|
|
|
|
else
|
|
Append_To (Res,
|
|
Make_Final_Call
|
|
(Obj_Ref => Duplicate_Subexpr_No_Checks (L),
|
|
Typ => Etype (L)));
|
|
end if;
|
|
|
|
-- Save the Tag in a local variable Tag_Id
|
|
|
|
if Save_Tag then
|
|
Tag_Id := Make_Temporary (Loc, 'A');
|
|
|
|
Append_To (Res,
|
|
Make_Object_Declaration (Loc,
|
|
Defining_Identifier => Tag_Id,
|
|
Object_Definition => New_Occurrence_Of (RTE (RE_Tag), Loc),
|
|
Expression =>
|
|
Make_Selected_Component (Loc,
|
|
Prefix => Duplicate_Subexpr_No_Checks (L),
|
|
Selector_Name =>
|
|
New_Occurrence_Of (First_Tag_Component (T), Loc))));
|
|
|
|
-- Otherwise Tag_Id is not used
|
|
|
|
else
|
|
Tag_Id := Empty;
|
|
end if;
|
|
|
|
-- If the tagged type has a full rep clause, expand the assignment into
|
|
-- component-wise assignments. Mark the node as unanalyzed in order to
|
|
-- generate the proper code and propagate this scenario by setting a
|
|
-- flag to avoid infinite recursion.
|
|
|
|
if Comp_Asn then
|
|
Set_Analyzed (Asn, False);
|
|
Set_Componentwise_Assignment (Asn, True);
|
|
end if;
|
|
|
|
Append_To (Res, Asn);
|
|
|
|
-- Restore the tag
|
|
|
|
if Save_Tag then
|
|
Append_To (Res,
|
|
Make_Assignment_Statement (Loc,
|
|
Name =>
|
|
Make_Selected_Component (Loc,
|
|
Prefix => Duplicate_Subexpr_No_Checks (L),
|
|
Selector_Name =>
|
|
New_Occurrence_Of (First_Tag_Component (T), Loc)),
|
|
Expression => New_Occurrence_Of (Tag_Id, Loc)));
|
|
end if;
|
|
|
|
-- Adjust the target after the assignment when controlled (not in the
|
|
-- init proc since it is an initialization more than an assignment).
|
|
|
|
if Ctrl_Act then
|
|
Append_To (Res,
|
|
Make_Adjust_Call
|
|
(Obj_Ref => Duplicate_Subexpr_Move_Checks (L),
|
|
Typ => Etype (L)));
|
|
end if;
|
|
|
|
return Res;
|
|
|
|
exception
|
|
|
|
-- Could use comment here ???
|
|
|
|
when RE_Not_Available =>
|
|
return Empty_List;
|
|
end Make_Tag_Ctrl_Assignment;
|
|
|
|
end Exp_Ch5;
|