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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- L A Y O U T --
-- --
-- B o d y --
-- --
-- Copyright (C) 2001-2014, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING3. If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with Atree; use Atree;
with Checks; use Checks;
with Debug; use Debug;
with Einfo; use Einfo;
with Errout; use Errout;
with Exp_Ch3; use Exp_Ch3;
with Exp_Util; use Exp_Util;
with Namet; use Namet;
with Nlists; use Nlists;
with Nmake; use Nmake;
with Opt; use Opt;
with Repinfo; use Repinfo;
with Sem; use Sem;
with Sem_Aux; use Sem_Aux;
with Sem_Case; use Sem_Case;
with Sem_Ch13; use Sem_Ch13;
with Sem_Eval; use Sem_Eval;
with Sem_Util; use Sem_Util;
with Sinfo; use Sinfo;
with Snames; use Snames;
with Stand; use Stand;
with Targparm; use Targparm;
with Tbuild; use Tbuild;
with Ttypes; use Ttypes;
with Uintp; use Uintp;
package body Layout is
------------------------
-- Local Declarations --
------------------------
SSU : constant Int := Ttypes.System_Storage_Unit;
-- Short hand for System_Storage_Unit
Vname : constant Name_Id := Name_uV;
-- Formal parameter name used for functions generated for size offset
-- values that depend on the discriminant. All such functions have the
-- following form:
--
-- function xxx (V : vtyp) return Unsigned is
-- begin
-- return ... expression involving V.discrim
-- end xxx;
-----------------------
-- Local Subprograms --
-----------------------
function Assoc_Add
(Loc : Source_Ptr;
Left_Opnd : Node_Id;
Right_Opnd : Node_Id) return Node_Id;
-- This is like Make_Op_Add except that it optimizes some cases knowing
-- that associative rearrangement is allowed for constant folding if one
-- of the operands is a compile time known value.
function Assoc_Multiply
(Loc : Source_Ptr;
Left_Opnd : Node_Id;
Right_Opnd : Node_Id) return Node_Id;
-- This is like Make_Op_Multiply except that it optimizes some cases
-- knowing that associative rearrangement is allowed for constant folding
-- if one of the operands is a compile time known value
function Assoc_Subtract
(Loc : Source_Ptr;
Left_Opnd : Node_Id;
Right_Opnd : Node_Id) return Node_Id;
-- This is like Make_Op_Subtract except that it optimizes some cases
-- knowing that associative rearrangement is allowed for constant folding
-- if one of the operands is a compile time known value
function Bits_To_SU (N : Node_Id) return Node_Id;
-- This is used when we cross the boundary from static sizes in bits to
-- dynamic sizes in storage units. If the argument N is anything other
-- than an integer literal, it is returned unchanged, but if it is an
-- integer literal, then it is taken as a size in bits, and is replaced
-- by the corresponding size in storage units.
function Compute_Length (Lo : Node_Id; Hi : Node_Id) return Node_Id;
-- Given expressions for the low bound (Lo) and the high bound (Hi),
-- Build an expression for the value hi-lo+1, converted to type
-- Standard.Unsigned. Takes care of the case where the operands
-- are of an enumeration type (so that the subtraction cannot be
-- done directly) by applying the Pos operator to Hi/Lo first.
procedure Compute_Size_Depends_On_Discriminant (E : Entity_Id);
-- Given an array type or an array subtype E, compute whether its size
-- depends on the value of one or more discriminants and set the flag
-- Size_Depends_On_Discriminant accordingly. This need not be called
-- in front end layout mode since it does the computation on its own.
function Expr_From_SO_Ref
(Loc : Source_Ptr;
D : SO_Ref;
Comp : Entity_Id := Empty) return Node_Id;
-- Given a value D from a size or offset field, return an expression
-- representing the value stored. If the value is known at compile time,
-- then an N_Integer_Literal is returned with the appropriate value. If
-- the value references a constant entity, then an N_Identifier node
-- referencing this entity is returned. If the value denotes a size
-- function, then returns a call node denoting the given function, with
-- a single actual parameter that either refers to the parameter V of
-- an enclosing size function (if Comp is Empty or its type doesn't match
-- the function's formal), or else is a selected component V.c when Comp
-- denotes a component c whose type matches that of the function formal.
-- The Loc value is used for the Sloc value of constructed notes.
function SO_Ref_From_Expr
(Expr : Node_Id;
Ins_Type : Entity_Id;
Vtype : Entity_Id := Empty;
Make_Func : Boolean := False) return Dynamic_SO_Ref;
-- This routine is used in the case where a size/offset value is dynamic
-- and is represented by the expression Expr. SO_Ref_From_Expr checks if
-- the Expr contains a reference to the identifier V, and if so builds
-- a function depending on discriminants of the formal parameter V which
-- is of type Vtype. Otherwise, if the parameter Make_Func is True, then
-- Expr will be encapsulated in a parameterless function; if Make_Func is
-- False, then a constant entity with the value Expr is built. The result
-- is a Dynamic_SO_Ref to the created entity. Note that Vtype can be
-- omitted if Expr does not contain any reference to V, the created entity.
-- The declaration created is inserted in the freeze actions of Ins_Type,
-- which also supplies the Sloc for created nodes. This function also takes
-- care of making sure that the expression is properly analyzed and
-- resolved (which may not be the case yet if we build the expression
-- in this unit).
function Get_Max_SU_Size (E : Entity_Id) return Node_Id;
-- E is an array type or subtype that has at least one index bound that
-- is the value of a record discriminant. For such an array, the function
-- computes an expression that yields the maximum possible size of the
-- array in storage units. The result is not defined for any other type,
-- or for arrays that do not depend on discriminants, and it is a fatal
-- error to call this unless Size_Depends_On_Discriminant (E) is True.
procedure Layout_Array_Type (E : Entity_Id);
-- Front-end layout of non-bit-packed array type or subtype
procedure Layout_Record_Type (E : Entity_Id);
-- Front-end layout of record type
procedure Rewrite_Integer (N : Node_Id; V : Uint);
-- Rewrite node N with an integer literal whose value is V. The Sloc for
-- the new node is taken from N, and the type of the literal is set to a
-- copy of the type of N on entry.
procedure Set_And_Check_Static_Size
(E : Entity_Id;
Esiz : SO_Ref;
RM_Siz : SO_Ref);
-- This procedure is called to check explicit given sizes (possibly stored
-- in the Esize and RM_Size fields of E) against computed Object_Size
-- (Esiz) and Value_Size (RM_Siz) values. Appropriate errors and warnings
-- are posted if specified sizes are inconsistent with specified sizes. On
-- return, Esize and RM_Size fields of E are set (either from previously
-- given values, or from the newly computed values, as appropriate).
procedure Set_Composite_Alignment (E : Entity_Id);
-- This procedure is called for record types and subtypes, and also for
-- atomic array types and subtypes. If no alignment is set, and the size
-- is 2 or 4 (or 8 if the word size is 8), then the alignment is set to
-- match the size.
----------------------------
-- Adjust_Esize_Alignment --
----------------------------
procedure Adjust_Esize_Alignment (E : Entity_Id) is
Abits : Int;
Esize_Set : Boolean;
begin
-- Nothing to do if size unknown
if Unknown_Esize (E) then
return;
end if;
-- Determine if size is constrained by an attribute definition clause
-- which must be obeyed. If so, we cannot increase the size in this
-- routine.
-- For a type, the issue is whether an object size clause has been set.
-- A normal size clause constrains only the value size (RM_Size)
if Is_Type (E) then
Esize_Set := Has_Object_Size_Clause (E);
-- For an object, the issue is whether a size clause is present
else
Esize_Set := Has_Size_Clause (E);
end if;
-- If size is known it must be a multiple of the storage unit size
if Esize (E) mod SSU /= 0 then
-- If not, and size specified, then give error
if Esize_Set then
Error_Msg_NE
("size for& not a multiple of storage unit size",
Size_Clause (E), E);
return;
-- Otherwise bump up size to a storage unit boundary
else
Set_Esize (E, (Esize (E) + SSU - 1) / SSU * SSU);
end if;
end if;
-- Now we have the size set, it must be a multiple of the alignment
-- nothing more we can do here if the alignment is unknown here.
if Unknown_Alignment (E) then
return;
end if;
-- At this point both the Esize and Alignment are known, so we need
-- to make sure they are consistent.
Abits := UI_To_Int (Alignment (E)) * SSU;
if Esize (E) mod Abits = 0 then
return;
end if;
-- Here we have a situation where the Esize is not a multiple of the
-- alignment. We must either increase Esize or reduce the alignment to
-- correct this situation.
-- The case in which we can decrease the alignment is where the
-- alignment was not set by an alignment clause, and the type in
-- question is a discrete type, where it is definitely safe to reduce
-- the alignment. For example:
-- t : integer range 1 .. 2;
-- for t'size use 8;
-- In this situation, the initial alignment of t is 4, copied from
-- the Integer base type, but it is safe to reduce it to 1 at this
-- stage, since we will only be loading a single storage unit.
if Is_Discrete_Type (Etype (E)) and then not Has_Alignment_Clause (E)
then
loop
Abits := Abits / 2;
exit when Esize (E) mod Abits = 0;
end loop;
Init_Alignment (E, Abits / SSU);
return;
end if;
-- Now the only possible approach left is to increase the Esize but we
-- can't do that if the size was set by a specific clause.
if Esize_Set then
Error_Msg_NE
("size for& is not a multiple of alignment",
Size_Clause (E), E);
-- Otherwise we can indeed increase the size to a multiple of alignment
else
Set_Esize (E, ((Esize (E) + (Abits - 1)) / Abits) * Abits);
end if;
end Adjust_Esize_Alignment;
---------------
-- Assoc_Add --
---------------
function Assoc_Add
(Loc : Source_Ptr;
Left_Opnd : Node_Id;
Right_Opnd : Node_Id) return Node_Id
is
L : Node_Id;
R : Uint;
begin
-- Case of right operand is a constant
if Compile_Time_Known_Value (Right_Opnd) then
L := Left_Opnd;
R := Expr_Value (Right_Opnd);
-- Case of left operand is a constant
elsif Compile_Time_Known_Value (Left_Opnd) then
L := Right_Opnd;
R := Expr_Value (Left_Opnd);
-- Neither operand is a constant, do the addition with no optimization
else
return Make_Op_Add (Loc, Left_Opnd, Right_Opnd);
end if;
-- Case of left operand is an addition
if Nkind (L) = N_Op_Add then
-- (C1 + E) + C2 = (C1 + C2) + E
if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
Rewrite_Integer
(Sinfo.Left_Opnd (L),
Expr_Value (Sinfo.Left_Opnd (L)) + R);
return L;
-- (E + C1) + C2 = E + (C1 + C2)
elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L)) then
Rewrite_Integer
(Sinfo.Right_Opnd (L),
Expr_Value (Sinfo.Right_Opnd (L)) + R);
return L;
end if;
-- Case of left operand is a subtraction
elsif Nkind (L) = N_Op_Subtract then
-- (C1 - E) + C2 = (C1 + C2) - E
if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
Rewrite_Integer
(Sinfo.Left_Opnd (L),
Expr_Value (Sinfo.Left_Opnd (L)) + R);
return L;
-- (E - C1) + C2 = E - (C1 - C2)
-- If the type is unsigned then only do the optimization if C1 >= C2,
-- to avoid creating a negative literal that can't be used with the
-- unsigned type.
elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L))
and then (not Is_Unsigned_Type (Etype (Sinfo.Right_Opnd (L)))
or else Expr_Value (Sinfo.Right_Opnd (L)) >= R)
then
Rewrite_Integer
(Sinfo.Right_Opnd (L),
Expr_Value (Sinfo.Right_Opnd (L)) - R);
return L;
end if;
end if;
-- Not optimizable, do the addition
return Make_Op_Add (Loc, Left_Opnd, Right_Opnd);
end Assoc_Add;
--------------------
-- Assoc_Multiply --
--------------------
function Assoc_Multiply
(Loc : Source_Ptr;
Left_Opnd : Node_Id;
Right_Opnd : Node_Id) return Node_Id
is
L : Node_Id;
R : Uint;
begin
-- Case of right operand is a constant
if Compile_Time_Known_Value (Right_Opnd) then
L := Left_Opnd;
R := Expr_Value (Right_Opnd);
-- Case of left operand is a constant
elsif Compile_Time_Known_Value (Left_Opnd) then
L := Right_Opnd;
R := Expr_Value (Left_Opnd);
-- Neither operand is a constant, do the multiply with no optimization
else
return Make_Op_Multiply (Loc, Left_Opnd, Right_Opnd);
end if;
-- Case of left operand is an multiplication
if Nkind (L) = N_Op_Multiply then
-- (C1 * E) * C2 = (C1 * C2) + E
if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
Rewrite_Integer
(Sinfo.Left_Opnd (L),
Expr_Value (Sinfo.Left_Opnd (L)) * R);
return L;
-- (E * C1) * C2 = E * (C1 * C2)
elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L)) then
Rewrite_Integer
(Sinfo.Right_Opnd (L),
Expr_Value (Sinfo.Right_Opnd (L)) * R);
return L;
end if;
end if;
-- Not optimizable, do the multiplication
return Make_Op_Multiply (Loc, Left_Opnd, Right_Opnd);
end Assoc_Multiply;
--------------------
-- Assoc_Subtract --
--------------------
function Assoc_Subtract
(Loc : Source_Ptr;
Left_Opnd : Node_Id;
Right_Opnd : Node_Id) return Node_Id
is
L : Node_Id;
R : Uint;
begin
-- Case of right operand is a constant
if Compile_Time_Known_Value (Right_Opnd) then
L := Left_Opnd;
R := Expr_Value (Right_Opnd);
-- Right operand is a constant, do the subtract with no optimization
else
return Make_Op_Subtract (Loc, Left_Opnd, Right_Opnd);
end if;
-- Case of left operand is an addition
if Nkind (L) = N_Op_Add then
-- (C1 + E) - C2 = (C1 - C2) + E
if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
Rewrite_Integer
(Sinfo.Left_Opnd (L),
Expr_Value (Sinfo.Left_Opnd (L)) - R);
return L;
-- (E + C1) - C2 = E + (C1 - C2)
elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L)) then
Rewrite_Integer
(Sinfo.Right_Opnd (L),
Expr_Value (Sinfo.Right_Opnd (L)) - R);
return L;
end if;
-- Case of left operand is a subtraction
elsif Nkind (L) = N_Op_Subtract then
-- (C1 - E) - C2 = (C1 - C2) + E
if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
Rewrite_Integer
(Sinfo.Left_Opnd (L),
Expr_Value (Sinfo.Left_Opnd (L)) + R);
return L;
-- (E - C1) - C2 = E - (C1 + C2)
elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L)) then
Rewrite_Integer
(Sinfo.Right_Opnd (L),
Expr_Value (Sinfo.Right_Opnd (L)) + R);
return L;
end if;
end if;
-- Not optimizable, do the subtraction
return Make_Op_Subtract (Loc, Left_Opnd, Right_Opnd);
end Assoc_Subtract;
----------------
-- Bits_To_SU --
----------------
function Bits_To_SU (N : Node_Id) return Node_Id is
begin
if Nkind (N) = N_Integer_Literal then
Set_Intval (N, (Intval (N) + (SSU - 1)) / SSU);
end if;
return N;
end Bits_To_SU;
--------------------
-- Compute_Length --
--------------------
function Compute_Length (Lo : Node_Id; Hi : Node_Id) return Node_Id is
Loc : constant Source_Ptr := Sloc (Lo);
Typ : constant Entity_Id := Etype (Lo);
Lo_Op : Node_Id;
Hi_Op : Node_Id;
Lo_Dim : Uint;
Hi_Dim : Uint;
begin
-- If the bounds are First and Last attributes for the same dimension
-- and both have prefixes that denotes the same entity, then we create
-- and return a Length attribute. This may allow the back end to
-- generate better code in cases where it already has the length.
if Nkind (Lo) = N_Attribute_Reference
and then Attribute_Name (Lo) = Name_First
and then Nkind (Hi) = N_Attribute_Reference
and then Attribute_Name (Hi) = Name_Last
and then Is_Entity_Name (Prefix (Lo))
and then Is_Entity_Name (Prefix (Hi))
and then Entity (Prefix (Lo)) = Entity (Prefix (Hi))
then
Lo_Dim := Uint_1;
Hi_Dim := Uint_1;
if Present (First (Expressions (Lo))) then
Lo_Dim := Expr_Value (First (Expressions (Lo)));
end if;
if Present (First (Expressions (Hi))) then
Hi_Dim := Expr_Value (First (Expressions (Hi)));
end if;
if Lo_Dim = Hi_Dim then
return
Make_Attribute_Reference (Loc,
Prefix => New_Occurrence_Of
(Entity (Prefix (Lo)), Loc),
Attribute_Name => Name_Length,
Expressions => New_List
(Make_Integer_Literal (Loc, Lo_Dim)));
end if;
end if;
Lo_Op := New_Copy_Tree (Lo);
Hi_Op := New_Copy_Tree (Hi);
-- If type is enumeration type, then use Pos attribute to convert
-- to integer type for which subtraction is a permitted operation.
if Is_Enumeration_Type (Typ) then
Lo_Op :=
Make_Attribute_Reference (Loc,
Prefix => New_Occurrence_Of (Typ, Loc),
Attribute_Name => Name_Pos,
Expressions => New_List (Lo_Op));
Hi_Op :=
Make_Attribute_Reference (Loc,
Prefix => New_Occurrence_Of (Typ, Loc),
Attribute_Name => Name_Pos,
Expressions => New_List (Hi_Op));
end if;
return
Assoc_Add (Loc,
Left_Opnd =>
Assoc_Subtract (Loc,
Left_Opnd => Hi_Op,
Right_Opnd => Lo_Op),
Right_Opnd => Make_Integer_Literal (Loc, 1));
end Compute_Length;
----------------------
-- Expr_From_SO_Ref --
----------------------
function Expr_From_SO_Ref
(Loc : Source_Ptr;
D : SO_Ref;
Comp : Entity_Id := Empty) return Node_Id
is
Ent : Entity_Id;
begin
if Is_Dynamic_SO_Ref (D) then
Ent := Get_Dynamic_SO_Entity (D);
if Is_Discrim_SO_Function (Ent) then
-- If a component is passed in whose type matches the type of
-- the function formal, then select that component from the "V"
-- parameter rather than passing "V" directly.
if Present (Comp)
and then Base_Type (Etype (Comp)) =
Base_Type (Etype (First_Formal (Ent)))
then
return
Make_Function_Call (Loc,
Name => New_Occurrence_Of (Ent, Loc),
Parameter_Associations => New_List (
Make_Selected_Component (Loc,
Prefix => Make_Identifier (Loc, Vname),
Selector_Name => New_Occurrence_Of (Comp, Loc))));
else
return
Make_Function_Call (Loc,
Name => New_Occurrence_Of (Ent, Loc),
Parameter_Associations => New_List (
Make_Identifier (Loc, Vname)));
end if;
else
return New_Occurrence_Of (Ent, Loc);
end if;
else
return Make_Integer_Literal (Loc, D);
end if;
end Expr_From_SO_Ref;
---------------------
-- Get_Max_SU_Size --
---------------------
function Get_Max_SU_Size (E : Entity_Id) return Node_Id is
Loc : constant Source_Ptr := Sloc (E);
Indx : Node_Id;
Ityp : Entity_Id;
Lo : Node_Id;
Hi : Node_Id;
S : Uint;
Len : Node_Id;
type Val_Status_Type is (Const, Dynamic);
type Val_Type (Status : Val_Status_Type := Const) is
record
case Status is
when Const => Val : Uint;
when Dynamic => Nod : Node_Id;
end case;
end record;
-- Shows the status of the value so far. Const means that the value is
-- constant, and Val is the current constant value. Dynamic means that
-- the value is dynamic, and in this case Nod is the Node_Id of the
-- expression to compute the value.
Size : Val_Type;
-- Calculated value so far if Size.Status = Const,
-- or expression value so far if Size.Status = Dynamic.
SU_Convert_Required : Boolean := False;
-- This is set to True if the final result must be converted from bits
-- to storage units (rounding up to a storage unit boundary).
-----------------------
-- Local Subprograms --
-----------------------
procedure Max_Discrim (N : in out Node_Id);
-- If the node N represents a discriminant, replace it by the maximum
-- value of the discriminant.
procedure Min_Discrim (N : in out Node_Id);
-- If the node N represents a discriminant, replace it by the minimum
-- value of the discriminant.
-----------------
-- Max_Discrim --
-----------------
procedure Max_Discrim (N : in out Node_Id) is
begin
if Nkind (N) = N_Identifier
and then Ekind (Entity (N)) = E_Discriminant
then
N := Type_High_Bound (Etype (N));
end if;
end Max_Discrim;
-----------------
-- Min_Discrim --
-----------------
procedure Min_Discrim (N : in out Node_Id) is
begin
if Nkind (N) = N_Identifier
and then Ekind (Entity (N)) = E_Discriminant
then
N := Type_Low_Bound (Etype (N));
end if;
end Min_Discrim;
-- Start of processing for Get_Max_SU_Size
begin
pragma Assert (Size_Depends_On_Discriminant (E));
-- Initialize status from component size
if Known_Static_Component_Size (E) then
Size := (Const, Component_Size (E));
else
Size := (Dynamic, Expr_From_SO_Ref (Loc, Component_Size (E)));
end if;
-- Loop through indexes
Indx := First_Index (E);
while Present (Indx) loop
Ityp := Etype (Indx);
Lo := Type_Low_Bound (Ityp);
Hi := Type_High_Bound (Ityp);
Min_Discrim (Lo);
Max_Discrim (Hi);
-- Value of the current subscript range is statically known
if Compile_Time_Known_Value (Lo)
and then
Compile_Time_Known_Value (Hi)
then
S := Expr_Value (Hi) - Expr_Value (Lo) + 1;
-- If known flat bound, entire size of array is zero
if S <= 0 then
return Make_Integer_Literal (Loc, 0);
end if;
-- Current value is constant, evolve value
if Size.Status = Const then
Size.Val := Size.Val * S;
-- Current value is dynamic
else
-- An interesting little optimization, if we have a pending
-- conversion from bits to storage units, and the current
-- length is a multiple of the storage unit size, then we
-- can take the factor out here statically, avoiding some
-- extra dynamic computations at the end.
if SU_Convert_Required and then S mod SSU = 0 then
S := S / SSU;
SU_Convert_Required := False;
end if;
Size.Nod :=
Assoc_Multiply (Loc,
Left_Opnd => Size.Nod,
Right_Opnd =>
Make_Integer_Literal (Loc, Intval => S));
end if;
-- Value of the current subscript range is dynamic
else
-- If the current size value is constant, then here is where we
-- make a transition to dynamic values, which are always stored
-- in storage units, However, we do not want to convert to SU's
-- too soon, consider the case of a packed array of single bits,
-- we want to do the SU conversion after computing the size in
-- this case.
if Size.Status = Const then
-- If the current value is a multiple of the storage unit,
-- then most certainly we can do the conversion now, simply
-- by dividing the current value by the storage unit value.
-- If this works, we set SU_Convert_Required to False.
if Size.Val mod SSU = 0 then
Size :=
(Dynamic, Make_Integer_Literal (Loc, Size.Val / SSU));
SU_Convert_Required := False;
-- Otherwise, we go ahead and convert the value in bits, and
-- set SU_Convert_Required to True to ensure that the final
-- value is indeed properly converted.
else
Size := (Dynamic, Make_Integer_Literal (Loc, Size.Val));
SU_Convert_Required := True;
end if;
end if;
-- Length is hi-lo+1
Len := Compute_Length (Lo, Hi);
-- Check possible range of Len
declare
OK : Boolean;
LLo : Uint;
LHi : Uint;
pragma Warnings (Off, LHi);
begin
Set_Parent (Len, E);
Determine_Range (Len, OK, LLo, LHi);
Len := Convert_To (Standard_Unsigned, Len);
-- If we cannot verify that range cannot be super-flat, we need
-- a max with zero, since length must be non-negative.
if not OK or else LLo < 0 then
Len :=
Make_Attribute_Reference (Loc,
Prefix =>
New_Occurrence_Of (Standard_Unsigned, Loc),
Attribute_Name => Name_Max,
Expressions => New_List (
Make_Integer_Literal (Loc, 0),
Len));
end if;
end;
end if;
Next_Index (Indx);
end loop;
-- Here after processing all bounds to set sizes. If the value is a
-- constant, then it is bits, so we convert to storage units.
if Size.Status = Const then
return Bits_To_SU (Make_Integer_Literal (Loc, Size.Val));
-- Case where the value is dynamic
else
-- Do convert from bits to SU's if needed
if SU_Convert_Required then
-- The expression required is (Size.Nod + SU - 1) / SU
Size.Nod :=
Make_Op_Divide (Loc,
Left_Opnd =>
Make_Op_Add (Loc,
Left_Opnd => Size.Nod,
Right_Opnd => Make_Integer_Literal (Loc, SSU - 1)),
Right_Opnd => Make_Integer_Literal (Loc, SSU));
end if;
return Size.Nod;
end if;
end Get_Max_SU_Size;
-----------------------
-- Layout_Array_Type --
-----------------------
procedure Layout_Array_Type (E : Entity_Id) is
Loc : constant Source_Ptr := Sloc (E);
Ctyp : constant Entity_Id := Component_Type (E);
Indx : Node_Id;
Ityp : Entity_Id;
Lo : Node_Id;
Hi : Node_Id;
S : Uint;
Len : Node_Id;
Insert_Typ : Entity_Id;
-- This is the type with which any generated constants or functions
-- will be associated (i.e. inserted into the freeze actions). This
-- is normally the type being laid out. The exception occurs when
-- we are laying out Itype's which are local to a record type, and
-- whose scope is this record type. Such types do not have freeze
-- nodes (because we have no place to put them).
------------------------------------
-- How An Array Type is Laid Out --
------------------------------------
-- Here is what goes on. We need to multiply the component size of the
-- array (which has already been set) by the length of each of the
-- indexes. If all these values are known at compile time, then the
-- resulting size of the array is the appropriate constant value.
-- If the component size or at least one bound is dynamic (but no
-- discriminants are present), then the size will be computed as an
-- expression that calculates the proper size.
-- If there is at least one discriminant bound, then the size is also
-- computed as an expression, but this expression contains discriminant
-- values which are obtained by selecting from a function parameter, and
-- the size is given by a function that is passed the variant record in
-- question, and whose body is the expression.
type Val_Status_Type is (Const, Dynamic, Discrim);
type Val_Type (Status : Val_Status_Type := Const) is
record
case Status is
when Const =>
Val : Uint;
-- Calculated value so far if Val_Status = Const
when Dynamic | Discrim =>
Nod : Node_Id;
-- Expression value so far if Val_Status /= Const
end case;
end record;
-- Records the value or expression computed so far. Const means that
-- the value is constant, and Val is the current constant value.
-- Dynamic means that the value is dynamic, and in this case Nod is
-- the Node_Id of the expression to compute the value, and Discrim
-- means that at least one bound is a discriminant, in which case Nod
-- is the expression so far (which will be the body of the function).
Size : Val_Type;
-- Value of size computed so far. See comments above
Vtyp : Entity_Id := Empty;
-- Variant record type for the formal parameter of the discriminant
-- function V if Status = Discrim.
SU_Convert_Required : Boolean := False;
-- This is set to True if the final result must be converted from
-- bits to storage units (rounding up to a storage unit boundary).
Storage_Divisor : Uint := UI_From_Int (SSU);
-- This is the amount that a nonstatic computed size will be divided
-- by to convert it from bits to storage units. This is normally
-- equal to SSU, but can be reduced in the case of packed components
-- that fit evenly into a storage unit.
Make_Size_Function : Boolean := False;
-- Indicates whether to request that SO_Ref_From_Expr should
-- encapsulate the array size expression in a function.
procedure Discrimify (N : in out Node_Id);
-- If N represents a discriminant, then the Size.Status is set to
-- Discrim, and Vtyp is set. The parameter N is replaced with the
-- proper expression to extract the discriminant value from V.
----------------
-- Discrimify --
----------------
procedure Discrimify (N : in out Node_Id) is
Decl : Node_Id;
Typ : Entity_Id;
begin
if Nkind (N) = N_Identifier
and then Ekind (Entity (N)) = E_Discriminant
then
Set_Size_Depends_On_Discriminant (E);
if Size.Status /= Discrim then
Decl := Parent (Parent (Entity (N)));
Size := (Discrim, Size.Nod);
Vtyp := Defining_Identifier (Decl);
end if;
Typ := Etype (N);
N :=
Make_Selected_Component (Loc,
Prefix => Make_Identifier (Loc, Vname),
Selector_Name => New_Occurrence_Of (Entity (N), Loc));
-- Set the Etype attributes of the selected name and its prefix.
-- Analyze_And_Resolve can't be called here because the Vname
-- entity denoted by the prefix will not yet exist (it's created
-- by SO_Ref_From_Expr, called at the end of Layout_Array_Type).
Set_Etype (Prefix (N), Vtyp);
Set_Etype (N, Typ);
end if;
end Discrimify;
-- Start of processing for Layout_Array_Type
begin
-- Default alignment is component alignment
if Unknown_Alignment (E) then
Set_Alignment (E, Alignment (Ctyp));
end if;
-- Calculate proper type for insertions
if Is_Record_Type (Underlying_Type (Scope (E))) then
Insert_Typ := Underlying_Type (Scope (E));
else
Insert_Typ := E;
end if;
-- If the component type is a generic formal type then there's no point
-- in determining a size for the array type.
if Is_Generic_Type (Ctyp) then
return;
end if;
-- Deal with component size if base type
if Ekind (E) = E_Array_Type then
-- Cannot do anything if Esize of component type unknown
if Unknown_Esize (Ctyp) then
return;
end if;
-- Set component size if not set already
if Unknown_Component_Size (E) then
Set_Component_Size (E, Esize (Ctyp));
end if;
end if;
-- (RM 13.3 (48)) says that the size of an unconstrained array
-- is implementation defined. We choose to leave it as Unknown
-- here, and the actual behavior is determined by the back end.
if not Is_Constrained (E) then
return;
end if;
-- Initialize status from component size
if Known_Static_Component_Size (E) then
Size := (Const, Component_Size (E));
else
Size := (Dynamic, Expr_From_SO_Ref (Loc, Component_Size (E)));
end if;
-- Loop to process array indexes
Indx := First_Index (E);
while Present (Indx) loop
Ityp := Etype (Indx);
-- If an index of the array is a generic formal type then there is
-- no point in determining a size for the array type.
if Is_Generic_Type (Ityp) then
return;
end if;
Lo := Type_Low_Bound (Ityp);
Hi := Type_High_Bound (Ityp);
-- Value of the current subscript range is statically known
if Compile_Time_Known_Value (Lo)
and then
Compile_Time_Known_Value (Hi)
then
S := Expr_Value (Hi) - Expr_Value (Lo) + 1;
-- If known flat bound, entire size of array is zero
if S <= 0 then
Set_Esize (E, Uint_0);
Set_RM_Size (E, Uint_0);
return;
end if;
-- If constant, evolve value
if Size.Status = Const then
Size.Val := Size.Val * S;
-- Current value is dynamic
else
-- An interesting little optimization, if we have a pending
-- conversion from bits to storage units, and the current
-- length is a multiple of the storage unit size, then we
-- can take the factor out here statically, avoiding some
-- extra dynamic computations at the end.
if SU_Convert_Required and then S mod SSU = 0 then
S := S / SSU;
SU_Convert_Required := False;
end if;
-- Now go ahead and evolve the expression
Size.Nod :=
Assoc_Multiply (Loc,
Left_Opnd => Size.Nod,
Right_Opnd =>
Make_Integer_Literal (Loc, Intval => S));
end if;
-- Value of the current subscript range is dynamic
else
-- If the current size value is constant, then here is where we
-- make a transition to dynamic values, which are always stored
-- in storage units, However, we do not want to convert to SU's
-- too soon, consider the case of a packed array of single bits,
-- we want to do the SU conversion after computing the size in
-- this case.
if Size.Status = Const then
-- If the current value is a multiple of the storage unit,
-- then most certainly we can do the conversion now, simply
-- by dividing the current value by the storage unit value.
-- If this works, we set SU_Convert_Required to False.
if Size.Val mod SSU = 0 then
Size :=
(Dynamic, Make_Integer_Literal (Loc, Size.Val / SSU));
SU_Convert_Required := False;
-- If the current value is a factor of the storage unit, then
-- we can use a value of one for the size and reduce the
-- strength of the later division.
elsif SSU mod Size.Val = 0 then
Storage_Divisor := SSU / Size.Val;
Size := (Dynamic, Make_Integer_Literal (Loc, Uint_1));
SU_Convert_Required := True;
-- Otherwise, we go ahead and convert the value in bits, and
-- set SU_Convert_Required to True to ensure that the final
-- value is indeed properly converted.
else
Size := (Dynamic, Make_Integer_Literal (Loc, Size.Val));
SU_Convert_Required := True;
end if;
end if;
Discrimify (Lo);
Discrimify (Hi);
-- Length is hi-lo+1
Len := Compute_Length (Lo, Hi);
-- If Len isn't a Length attribute, then its range needs to be
-- checked a possible Max with zero needs to be computed.
if Nkind (Len) /= N_Attribute_Reference
or else Attribute_Name (Len) /= Name_Length
then
declare
OK : Boolean;
LLo : Uint;
LHi : Uint;
begin
-- Check possible range of Len
Set_Parent (Len, E);
Determine_Range (Len, OK, LLo, LHi);
Len := Convert_To (Standard_Unsigned, Len);
-- If range definitely flat or superflat, result size is 0
if OK and then LHi <= 0 then
Set_Esize (E, Uint_0);
Set_RM_Size (E, Uint_0);
return;
end if;
-- If we cannot verify that range cannot be super-flat, we
-- need a max with zero, since length cannot be negative.
if not OK or else LLo < 0 then
Len :=
Make_Attribute_Reference (Loc,
Prefix =>
New_Occurrence_Of (Standard_Unsigned, Loc),
Attribute_Name => Name_Max,
Expressions => New_List (
Make_Integer_Literal (Loc, 0),
Len));
end if;
end;
end if;
-- At this stage, Len has the expression for the length
Size.Nod :=
Assoc_Multiply (Loc,
Left_Opnd => Size.Nod,
Right_Opnd => Len);
end if;
Next_Index (Indx);
end loop;
-- Here after processing all bounds to set sizes. If the value is a
-- constant, then it is bits, and the only thing we need to do is to
-- check against explicit given size and do alignment adjust.
if Size.Status = Const then
Set_And_Check_Static_Size (E, Size.Val, Size.Val);
Adjust_Esize_Alignment (E);
-- Case where the value is dynamic
else
-- Do convert from bits to SU's if needed
if SU_Convert_Required then
-- The expression required is:
-- (Size.Nod + Storage_Divisor - 1) / Storage_Divisor
Size.Nod :=
Make_Op_Divide (Loc,
Left_Opnd =>
Make_Op_Add (Loc,
Left_Opnd => Size.Nod,
Right_Opnd => Make_Integer_Literal
(Loc, Storage_Divisor - 1)),
Right_Opnd => Make_Integer_Literal (Loc, Storage_Divisor));
end if;
-- If the array entity is not declared at the library level and its
-- not nested within a subprogram that is marked for inlining, then
-- we request that the size expression be encapsulated in a function.
-- Since this expression is not needed in most cases, we prefer not
-- to incur the overhead of the computation on calls to the enclosing
-- subprogram except for subprograms that require the size.
if not Is_Library_Level_Entity (E) then
Make_Size_Function := True;
declare
Parent_Subp : Entity_Id := Enclosing_Subprogram (E);
begin
while Present (Parent_Subp) loop
if Is_Inlined (Parent_Subp) then
Make_Size_Function := False;
exit;
end if;
Parent_Subp := Enclosing_Subprogram (Parent_Subp);
end loop;
end;
end if;
-- Now set the dynamic size (the Value_Size is always the same as the
-- Object_Size for arrays whose length is dynamic).
-- ??? If Size.Status = Dynamic, Vtyp will not have been set.
-- The added initialization sets it to Empty now, but is this
-- correct?
Set_Esize
(E,
SO_Ref_From_Expr
(Size.Nod, Insert_Typ, Vtyp, Make_Func => Make_Size_Function));
Set_RM_Size (E, Esize (E));
end if;
end Layout_Array_Type;
------------------------------------------
-- Compute_Size_Depends_On_Discriminant --
------------------------------------------
procedure Compute_Size_Depends_On_Discriminant (E : Entity_Id) is
Indx : Node_Id;
Ityp : Entity_Id;
Lo : Node_Id;
Hi : Node_Id;
Res : Boolean := False;
begin
-- Loop to process array indexes
Indx := First_Index (E);
while Present (Indx) loop
Ityp := Etype (Indx);
-- If an index of the array is a generic formal type then there is
-- no point in determining a size for the array type.
if Is_Generic_Type (Ityp) then
return;
end if;
Lo := Type_Low_Bound (Ityp);
Hi := Type_High_Bound (Ityp);
if (Nkind (Lo) = N_Identifier
and then Ekind (Entity (Lo)) = E_Discriminant)
or else
(Nkind (Hi) = N_Identifier
and then Ekind (Entity (Hi)) = E_Discriminant)
then
Res := True;
end if;
Next_Index (Indx);
end loop;
if Res then
Set_Size_Depends_On_Discriminant (E);
end if;
end Compute_Size_Depends_On_Discriminant;
-------------------
-- Layout_Object --
-------------------
procedure Layout_Object (E : Entity_Id) is
T : constant Entity_Id := Etype (E);
begin
-- Nothing to do if backend does layout
if not Frontend_Layout_On_Target then
return;
end if;
-- Set size if not set for object and known for type. Use the RM_Size if
-- that is known for the type and Esize is not.
if Unknown_Esize (E) then
if Known_Esize (T) then
Set_Esize (E, Esize (T));
elsif Known_RM_Size (T) then
Set_Esize (E, RM_Size (T));
end if;
end if;
-- Set alignment from type if unknown and type alignment known
if Unknown_Alignment (E) and then Known_Alignment (T) then
Set_Alignment (E, Alignment (T));
end if;
-- Make sure size and alignment are consistent
Adjust_Esize_Alignment (E);
-- Final adjustment, if we don't know the alignment, and the Esize was
-- not set by an explicit Object_Size attribute clause, then we reset
-- the Esize to unknown, since we really don't know it.
if Unknown_Alignment (E) and then not Has_Size_Clause (E) then
Set_Esize (E, Uint_0);
end if;
end Layout_Object;
------------------------
-- Layout_Record_Type --
------------------------
procedure Layout_Record_Type (E : Entity_Id) is
Loc : constant Source_Ptr := Sloc (E);
Decl : Node_Id;
Comp : Entity_Id;
-- Current component being laid out
Prev_Comp : Entity_Id;
-- Previous laid out component
procedure Get_Next_Component_Location
(Prev_Comp : Entity_Id;
Align : Uint;
New_Npos : out SO_Ref;
New_Fbit : out SO_Ref;
New_NPMax : out SO_Ref;
Force_SU : Boolean);
-- Given the previous component in Prev_Comp, which is already laid
-- out, and the alignment of the following component, lays out the
-- following component, and returns its starting position in New_Npos
-- (Normalized_Position value), New_Fbit (Normalized_First_Bit value),
-- and New_NPMax (Normalized_Position_Max value). If Prev_Comp is empty
-- (no previous component is present), then New_Npos, New_Fbit and
-- New_NPMax are all set to zero on return. This procedure is also
-- used to compute the size of a record or variant by giving it the
-- last component, and the record alignment. Force_SU is used to force
-- the new component location to be aligned on a storage unit boundary,
-- even in a packed record, False means that the new position does not
-- need to be bumped to a storage unit boundary, True means a storage
-- unit boundary is always required.
procedure Layout_Component (Comp : Entity_Id; Prev_Comp : Entity_Id);
-- Lays out component Comp, given Prev_Comp, the previously laid-out
-- component (Prev_Comp = Empty if no components laid out yet). The
-- alignment of the record itself is also updated if needed. Both
-- Comp and Prev_Comp can be either components or discriminants.
procedure Layout_Components
(From : Entity_Id;
To : Entity_Id;
Esiz : out SO_Ref;
RM_Siz : out SO_Ref);
-- This procedure lays out the components of the given component list
-- which contains the components starting with From and ending with To.
-- The Next_Entity chain is used to traverse the components. On entry,
-- Prev_Comp is set to the component preceding the list, so that the
-- list is laid out after this component. Prev_Comp is set to Empty if
-- the component list is to be laid out starting at the start of the
-- record. On return, the components are all laid out, and Prev_Comp is
-- set to the last laid out component. On return, Esiz is set to the
-- resulting Object_Size value, which is the length of the record up
-- to and including the last laid out entity. For Esiz, the value is
-- adjusted to match the alignment of the record. RM_Siz is similarly
-- set to the resulting Value_Size value, which is the same length, but
-- not adjusted to meet the alignment. Note that in the case of variant
-- records, Esiz represents the maximum size.
procedure Layout_Non_Variant_Record;
-- Procedure called to lay out a non-variant record type or subtype
procedure Layout_Variant_Record;
-- Procedure called to lay out a variant record type. Decl is set to the
-- full type declaration for the variant record.
---------------------------------
-- Get_Next_Component_Location --
---------------------------------
procedure Get_Next_Component_Location
(Prev_Comp : Entity_Id;
Align : Uint;
New_Npos : out SO_Ref;
New_Fbit : out SO_Ref;
New_NPMax : out SO_Ref;
Force_SU : Boolean)
is
begin
-- No previous component, return zero position
if No (Prev_Comp) then
New_Npos := Uint_0;
New_Fbit := Uint_0;
New_NPMax := Uint_0;
return;
end if;
-- Here we have a previous component
declare
Loc : constant Source_Ptr := Sloc (Prev_Comp);
Old_Npos : constant SO_Ref := Normalized_Position (Prev_Comp);
Old_Fbit : constant SO_Ref := Normalized_First_Bit (Prev_Comp);
Old_NPMax : constant SO_Ref := Normalized_Position_Max (Prev_Comp);
Old_Esiz : constant SO_Ref := Esize (Prev_Comp);
Old_Maxsz : Node_Id;
-- Expression representing maximum size of previous component
begin
-- Case where previous field had a dynamic size
if Is_Dynamic_SO_Ref (Esize (Prev_Comp)) then
-- If the previous field had a dynamic length, then it is
-- required to occupy an integral number of storage units,
-- and start on a storage unit boundary. This means that
-- the Normalized_First_Bit value is zero in the previous
-- component, and the new value is also set to zero.
New_Fbit := Uint_0;
-- In this case, the new position is given by an expression
-- that is the sum of old normalized position and old size.
New_Npos :=
SO_Ref_From_Expr
(Assoc_Add (Loc,
Left_Opnd =>
Expr_From_SO_Ref (Loc, Old_Npos),
Right_Opnd =>
Expr_From_SO_Ref (Loc, Old_Esiz, Prev_Comp)),
Ins_Type => E,
Vtype => E);
-- Get maximum size of previous component
if Size_Depends_On_Discriminant (Etype (Prev_Comp)) then
Old_Maxsz := Get_Max_SU_Size (Etype (Prev_Comp));
else
Old_Maxsz := Expr_From_SO_Ref (Loc, Old_Esiz, Prev_Comp);
end if;
-- Now we can compute the new max position. If the max size
-- is static and the old position is static, then we can
-- compute the new position statically.
if Nkind (Old_Maxsz) = N_Integer_Literal
and then Known_Static_Normalized_Position_Max (Prev_Comp)
then
New_NPMax := Old_NPMax + Intval (Old_Maxsz);
-- Otherwise new max position is dynamic
else
New_NPMax :=
SO_Ref_From_Expr
(Assoc_Add (Loc,
Left_Opnd => Expr_From_SO_Ref (Loc, Old_NPMax),
Right_Opnd => Old_Maxsz),
Ins_Type => E,
Vtype => E);
end if;
-- Previous field has known static Esize
else
New_Fbit := Old_Fbit + Old_Esiz;
-- Bump New_Fbit to storage unit boundary if required
if New_Fbit /= 0 and then Force_SU then
New_Fbit := (New_Fbit + SSU - 1) / SSU * SSU;
end if;
-- If old normalized position is static, we can go ahead and
-- compute the new normalized position directly.
if Known_Static_Normalized_Position (Prev_Comp) then
New_Npos := Old_Npos;
if New_Fbit >= SSU then
New_Npos := New_Npos + New_Fbit / SSU;
New_Fbit := New_Fbit mod SSU;
end if;
-- Bump alignment if stricter than prev
if Align > Alignment (Etype (Prev_Comp)) then
New_Npos := (New_Npos + Align - 1) / Align * Align;
end if;
-- The max position is always equal to the position if
-- the latter is static, since arrays depending on the
-- values of discriminants never have static sizes.
New_NPMax := New_Npos;
return;
-- Case of old normalized position is dynamic
else
-- If new bit position is within the current storage unit,
-- we can just copy the old position as the result position
-- (we have already set the new first bit value).
if New_Fbit < SSU then
New_Npos := Old_Npos;
New_NPMax := Old_NPMax;
-- If new bit position is past the current storage unit, we
-- need to generate a new dynamic value for the position
-- ??? need to deal with alignment
else
New_Npos :=
SO_Ref_From_Expr
(Assoc_Add (Loc,
Left_Opnd => Expr_From_SO_Ref (Loc, Old_Npos),
Right_Opnd =>
Make_Integer_Literal (Loc,
Intval => New_Fbit / SSU)),
Ins_Type => E,
Vtype => E);
New_NPMax :=
SO_Ref_From_Expr
(Assoc_Add (Loc,
Left_Opnd => Expr_From_SO_Ref (Loc, Old_NPMax),
Right_Opnd =>
Make_Integer_Literal (Loc,
Intval => New_Fbit / SSU)),
Ins_Type => E,
Vtype => E);
New_Fbit := New_Fbit mod SSU;
end if;
end if;
end if;
end;
end Get_Next_Component_Location;
----------------------
-- Layout_Component --
----------------------
procedure Layout_Component (Comp : Entity_Id; Prev_Comp : Entity_Id) is
Ctyp : constant Entity_Id := Etype (Comp);
ORC : constant Entity_Id := Original_Record_Component (Comp);
Npos : SO_Ref;
Fbit : SO_Ref;
NPMax : SO_Ref;
Forc : Boolean;
begin
-- Increase alignment of record if necessary. Note that we do not
-- do this for packed records, which have an alignment of one by
-- default, or for records for which an explicit alignment was
-- specified with an alignment clause.
if not Is_Packed (E)
and then not Has_Alignment_Clause (E)
and then Alignment (Ctyp) > Alignment (E)
then
Set_Alignment (E, Alignment (Ctyp));
end if;
-- If original component set, then use same layout
if Present (ORC) and then ORC /= Comp then
Set_Normalized_Position (Comp, Normalized_Position (ORC));
Set_Normalized_First_Bit (Comp, Normalized_First_Bit (ORC));
Set_Normalized_Position_Max (Comp, Normalized_Position_Max (ORC));
Set_Component_Bit_Offset (Comp, Component_Bit_Offset (ORC));
Set_Esize (Comp, Esize (ORC));
return;
end if;
-- Parent field is always at start of record, this will overlap
-- the actual fields that are part of the parent, and that's fine
if Chars (Comp) = Name_uParent then
Set_Normalized_Position (Comp, Uint_0);
Set_Normalized_First_Bit (Comp, Uint_0);
Set_Normalized_Position_Max (Comp, Uint_0);
Set_Component_Bit_Offset (Comp, Uint_0);
Set_Esize (Comp, Esize (Ctyp));
return;
end if;
-- Check case of type of component has a scope of the record we are
-- laying out. When this happens, the type in question is an Itype
-- that has not yet been laid out (that's because such types do not
-- get frozen in the normal manner, because there is no place for
-- the freeze nodes).
if Scope (Ctyp) = E then
Layout_Type (Ctyp);
end if;
-- If component already laid out, then we are done
if Known_Normalized_Position (Comp) then
return;
end if;
-- Set size of component from type. We use the Esize except in a
-- packed record, where we use the RM_Size (since that is what the
-- RM_Size value, as distinct from the Object_Size is useful for).
if Is_Packed (E) then
Set_Esize (Comp, RM_Size (Ctyp));
else
Set_Esize (Comp, Esize (Ctyp));
end if;
-- Compute the component position from the previous one. See if
-- current component requires being on a storage unit boundary.
-- If record is not packed, we always go to a storage unit boundary
if not Is_Packed (E) then
Forc := True;
-- Packed cases
else
-- Elementary types do not need SU boundary in packed record
if Is_Elementary_Type (Ctyp) then
Forc := False;
-- Packed array types with a modular packed array type do not
-- force a storage unit boundary (since the code generation
-- treats these as equivalent to the underlying modular type),
elsif Is_Array_Type (Ctyp)
and then Is_Bit_Packed_Array (Ctyp)
and then Is_Modular_Integer_Type (Packed_Array_Impl_Type (Ctyp))
then
Forc := False;
-- Record types with known length less than or equal to the length
-- of long long integer can also be unaligned, since they can be
-- treated as scalars.
elsif Is_Record_Type (Ctyp)
and then not Is_Dynamic_SO_Ref (Esize (Ctyp))
and then Esize (Ctyp) <= Esize (Standard_Long_Long_Integer)
then
Forc := False;
-- All other cases force a storage unit boundary, even when packed
else
Forc := True;
end if;
end if;
-- Now get the next component location
Get_Next_Component_Location
(Prev_Comp, Alignment (Ctyp), Npos, Fbit, NPMax, Forc);
Set_Normalized_Position (Comp, Npos);
Set_Normalized_First_Bit (Comp, Fbit);
Set_Normalized_Position_Max (Comp, NPMax);
-- Set Component_Bit_Offset in the static case
if Known_Static_Normalized_Position (Comp)
and then Known_Normalized_First_Bit (Comp)
then
Set_Component_Bit_Offset (Comp, SSU * Npos + Fbit);
end if;
end Layout_Component;
-----------------------
-- Layout_Components --
-----------------------
procedure Layout_Components
(From : Entity_Id;
To : Entity_Id;
Esiz : out SO_Ref;
RM_Siz : out SO_Ref)
is
End_Npos : SO_Ref;
End_Fbit : SO_Ref;
End_NPMax : SO_Ref;
begin
-- Only lay out components if there are some to lay out
if Present (From) then
-- Lay out components with no component clauses
Comp := From;
loop
if Ekind (Comp) = E_Component
or else Ekind (Comp) = E_Discriminant
then
-- The compatibility of component clauses with composite
-- types isn't checked in Sem_Ch13, so we check it here.
if Present (Component_Clause (Comp)) then
if Is_Composite_Type (Etype (Comp))
and then Esize (Comp) < RM_Size (Etype (Comp))
then
Error_Msg_Uint_1 := RM_Size (Etype (Comp));
Error_Msg_NE
("size for & too small, minimum allowed is ^",
Component_Clause (Comp),
Comp);
end if;
else
Layout_Component (Comp, Prev_Comp);
Prev_Comp := Comp;
end if;
end if;
exit when Comp = To;
Next_Entity (Comp);
end loop;
end if;
-- Set size fields, both are zero if no components
if No (Prev_Comp) then
Esiz := Uint_0;
RM_Siz := Uint_0;
-- If record subtype with non-static discriminants, then we don't
-- know which variant will be the one which gets chosen. We don't
-- just want to set the maximum size from the base, because the
-- size should depend on the particular variant.
-- What we do is to use the RM_Size of the base type, which has
-- the necessary conditional computation of the size, using the
-- size information for the particular variant chosen. Records
-- with default discriminants for example have an Esize that is
-- set to the maximum of all variants, but that's not what we
-- want for a constrained subtype.
elsif Ekind (E) = E_Record_Subtype
and then not Has_Static_Discriminants (E)
then
declare
BT : constant Node_Id := Base_Type (E);
begin
Esiz := RM_Size (BT);
RM_Siz := RM_Size (BT);
Set_Alignment (E, Alignment (BT));
end;
else
-- First the object size, for which we align past the last field
-- to the alignment of the record (the object size is required to
-- be a multiple of the alignment).
Get_Next_Component_Location
(Prev_Comp,
Alignment (E),
End_Npos,
End_Fbit,
End_NPMax,
Force_SU => True);
-- If the resulting normalized position is a dynamic reference,
-- then the size is dynamic, and is stored in storage units. In
-- this case, we set the RM_Size to the same value, it is simply
-- not worth distinguishing Esize and RM_Size values in the
-- dynamic case, since the RM has nothing to say about them.
-- Note that a size cannot have been given in this case, since
-- size specifications cannot be given for variable length types.
declare
Align : constant Uint := Alignment (E);
begin
if Is_Dynamic_SO_Ref (End_Npos) then
RM_Siz := End_Npos;
-- Set the Object_Size allowing for the alignment. In the
-- dynamic case, we must do the actual runtime computation.
-- We can skip this in the non-packed record case if the
-- last component has a smaller alignment than the overall
-- record alignment.
if Is_Dynamic_SO_Ref (End_NPMax) then
Esiz := End_NPMax;
if Is_Packed (E)
or else Alignment (Etype (Prev_Comp)) < Align
then
-- The expression we build is:
-- (expr + align - 1) / align * align
Esiz :=
SO_Ref_From_Expr
(Expr =>
Make_Op_Multiply (Loc,
Left_Opnd =>
Make_Op_Divide (Loc,
Left_Opnd =>
Make_Op_Add (Loc,
Left_Opnd =>
Expr_From_SO_Ref (Loc, Esiz),
Right_Opnd =>
Make_Integer_Literal (Loc,
Intval => Align - 1)),
Right_Opnd =>
Make_Integer_Literal (Loc, Align)),
Right_Opnd =>
Make_Integer_Literal (Loc, Align)),
Ins_Type => E,
Vtype => E);
end if;
-- Here Esiz is static, so we can adjust the alignment
-- directly go give the required aligned value.
else
Esiz := (End_NPMax + Align - 1) / Align * Align * SSU;
end if;
-- Case where computed size is static
else
-- The ending size was computed in Npos in storage units,
-- but the actual size is stored in bits, so adjust
-- accordingly. We also adjust the size to match the
-- alignment here.
Esiz := (End_NPMax + Align - 1) / Align * Align * SSU;
-- Compute the resulting Value_Size (RM_Size). For this
-- purpose we do not force alignment of the record or
-- storage size alignment of the result.
Get_Next_Component_Location
(Prev_Comp,
Uint_0,
End_Npos,
End_Fbit,
End_NPMax,
Force_SU => False);
RM_Siz := End_Npos * SSU + End_Fbit;
Set_And_Check_Static_Size (E, Esiz, RM_Siz);
end if;
end;
end if;
end Layout_Components;
-------------------------------
-- Layout_Non_Variant_Record --
-------------------------------
procedure Layout_Non_Variant_Record is
Esiz : SO_Ref;
RM_Siz : SO_Ref;
begin
Layout_Components (First_Entity (E), Last_Entity (E), Esiz, RM_Siz);
Set_Esize (E, Esiz);
Set_RM_Size (E, RM_Siz);
end Layout_Non_Variant_Record;
---------------------------
-- Layout_Variant_Record --
---------------------------
procedure Layout_Variant_Record is
Tdef : constant Node_Id := Type_Definition (Decl);
First_Discr : Entity_Id;
Last_Discr : Entity_Id;
Esiz : SO_Ref;
RM_Siz : SO_Ref;
pragma Warnings (Off, SO_Ref);
RM_Siz_Expr : Node_Id := Empty;
-- Expression for the evolving RM_Siz value. This is typically an if
-- expression which involves tests of discriminant values that are
-- formed as references to the entity V. At the end of scanning all
-- the components, a suitable function is constructed in which V is
-- the parameter.
-----------------------
-- Local Subprograms --
-----------------------
procedure Layout_Component_List
(Clist : Node_Id;
Esiz : out SO_Ref;
RM_Siz_Expr : out Node_Id);
-- Recursive procedure, called to lay out one component list Esiz
-- and RM_Siz_Expr are set to the Object_Size and Value_Size values
-- respectively representing the record size up to and including the
-- last component in the component list (including any variants in
-- this component list). RM_Siz_Expr is returned as an expression
-- which may in the general case involve some references to the
-- discriminants of the current record value, referenced by selecting
-- from the entity V.
---------------------------
-- Layout_Component_List --
---------------------------
procedure Layout_Component_List
(Clist : Node_Id;
Esiz : out SO_Ref;
RM_Siz_Expr : out Node_Id)
is
Citems : constant List_Id := Component_Items (Clist);
Vpart : constant Node_Id := Variant_Part (Clist);
Prv : Node_Id;
Var : Node_Id;
RM_Siz : Uint;
RMS_Ent : Entity_Id;
begin
if Is_Non_Empty_List (Citems) then
Layout_Components
(From => Defining_Identifier (First (Citems)),
To => Defining_Identifier (Last (Citems)),
Esiz => Esiz,
RM_Siz => RM_Siz);
else
Layout_Components (Empty, Empty, Esiz, RM_Siz);
end if;
-- Case where no variants are present in the component list
if No (Vpart) then
-- The Esiz value has been correctly set by the call to
-- Layout_Components, so there is nothing more to be done.
-- For RM_Siz, we have an SO_Ref value, which we must convert
-- to an appropriate expression.
if Is_Static_SO_Ref (RM_Siz) then
RM_Siz_Expr :=
Make_Integer_Literal (Loc,
Intval => RM_Siz);
else
RMS_Ent := Get_Dynamic_SO_Entity (RM_Siz);
-- If the size is represented by a function, then we create
-- an appropriate function call using V as the parameter to
-- the call.
if Is_Discrim_SO_Function (RMS_Ent) then
RM_Siz_Expr :=
Make_Function_Call (Loc,
Name => New_Occurrence_Of (RMS_Ent, Loc),
Parameter_Associations => New_List (
Make_Identifier (Loc, Vname)));
-- If the size is represented by a constant, then the
-- expression we want is a reference to this constant
else
RM_Siz_Expr := New_Occurrence_Of (RMS_Ent, Loc);
end if;
end if;
-- Case where variants are present in this component list
else
declare
EsizV : SO_Ref;
RM_SizV : Node_Id;
Dchoice : Node_Id;
Discrim : Node_Id;
Dtest : Node_Id;
D_List : List_Id;
D_Entity : Entity_Id;
begin
RM_Siz_Expr := Empty;
Prv := Prev_Comp;
Var := Last (Variants (Vpart));
while Present (Var) loop
Prev_Comp := Prv;
Layout_Component_List
(Component_List (Var), EsizV, RM_SizV);
-- Set the Object_Size. If this is the first variant,
-- we just set the size of this first variant.
if Var = Last (Variants (Vpart)) then
Esiz := EsizV;
-- Otherwise the Object_Size is formed as a maximum
-- of Esiz so far from previous variants, and the new
-- Esiz value from the variant we just processed.
-- If both values are static, we can just compute the
-- maximum directly to save building junk nodes.
elsif not Is_Dynamic_SO_Ref (Esiz)
and then not Is_Dynamic_SO_Ref (EsizV)
then
Esiz := UI_Max (Esiz, EsizV);
-- If either value is dynamic, then we have to generate
-- an appropriate Standard_Unsigned'Max attribute call.
-- If one of the values is static then it needs to be
-- converted from bits to storage units to be compatible
-- with the dynamic value.
else
if Is_Static_SO_Ref (Esiz) then
Esiz := (Esiz + SSU - 1) / SSU;
end if;
if Is_Static_SO_Ref (EsizV) then
EsizV := (EsizV + SSU - 1) / SSU;
end if;
Esiz :=
SO_Ref_From_Expr
(Make_Attribute_Reference (Loc,
Attribute_Name => Name_Max,
Prefix =>
New_Occurrence_Of (Standard_Unsigned, Loc),
Expressions => New_List (
Expr_From_SO_Ref (Loc, Esiz),
Expr_From_SO_Ref (Loc, EsizV))),
Ins_Type => E,
Vtype => E);
end if;
-- Now deal with Value_Size (RM_Siz). We are aiming at
-- an expression that looks like:
-- if xxDx (V.disc) then rmsiz1
-- else if xxDx (V.disc) then rmsiz2
-- else ...
-- Where rmsiz1, rmsiz2... are the RM_Siz values for the
-- individual variants, and xxDx are the discriminant
-- checking functions generated for the variant type.
-- If this is the first variant, we simply set the result
-- as the expression. Note that this takes care of the
-- others case.
if No (RM_Siz_Expr) then
-- If this is the only variant and the size is a
-- literal, then use bit size as is, otherwise convert
-- to storage units and continue to the next variant.
if No (Prev (Var))
and then Nkind (RM_SizV) = N_Integer_Literal
then
RM_Siz_Expr := RM_SizV;
else
RM_Siz_Expr := Bits_To_SU (RM_SizV);
end if;
-- Otherwise construct the appropriate test
else
-- The test to be used in general is a call to the
-- discriminant checking function. However, it is
-- definitely worth special casing the very common
-- case where a single value is involved.
Dchoice := First (Discrete_Choices (Var));
if No (Next (Dchoice))
and then Nkind (Dchoice) /= N_Range
then
-- Discriminant to be tested
Discrim :=
Make_Selected_Component (Loc,
Prefix =>
Make_Identifier (Loc, Vname),
Selector_Name =>
New_Occurrence_Of
(Entity (Name (Vpart)), Loc));
Dtest :=
Make_Op_Eq (Loc,
Left_Opnd => Discrim,
Right_Opnd => New_Copy (Dchoice));
-- Generate a call to the discriminant-checking
-- function for the variant. Note that the result
-- has to be complemented since the function returns
-- False when the passed discriminant value matches.
else
-- The checking function takes all of the type's
-- discriminants as parameters, so a list of all
-- the selected discriminants must be constructed.
D_List := New_List;
D_Entity := First_Discriminant (E);
while Present (D_Entity) loop
Append_To (D_List,
Make_Selected_Component (Loc,
Prefix =>
Make_Identifier (Loc, Vname),
Selector_Name =>
New_Occurrence_Of (D_Entity, Loc)));
D_Entity := Next_Discriminant (D_Entity);
end loop;
Dtest :=
Make_Op_Not (Loc,
Right_Opnd =>
Make_Function_Call (Loc,
Name =>
New_Occurrence_Of
(Dcheck_Function (Var), Loc),
Parameter_Associations =>
D_List));
end if;
RM_Siz_Expr :=
Make_If_Expression (Loc,
Expressions =>
New_List
(Dtest, Bits_To_SU (RM_SizV), RM_Siz_Expr));
end if;
Prev (Var);
end loop;
end;
end if;
end Layout_Component_List;
Others_Present : Boolean;
pragma Warnings (Off, Others_Present);
-- Indicates others present, not used in this case
procedure Non_Static_Choice_Error (Choice : Node_Id);
-- Error routine invoked by the generic instantiation below when
-- the variant part has a nonstatic choice.
package Variant_Choices_Processing is new
Generic_Check_Choices
(Process_Empty_Choice => No_OP,
Process_Non_Static_Choice => Non_Static_Choice_Error,
Process_Associated_Node => No_OP);
use Variant_Choices_Processing;
-----------------------------
-- Non_Static_Choice_Error --
-----------------------------
procedure Non_Static_Choice_Error (Choice : Node_Id) is
begin
Flag_Non_Static_Expr
("choice given in case expression is not static!", Choice);
end Non_Static_Choice_Error;
-- Start of processing for Layout_Variant_Record
begin
-- Call Check_Choices here to ensure that Others_Discrete_Choices
-- gets set on any 'others' choice before the discriminant-checking
-- functions are generated. Otherwise the function for the 'others'
-- alternative will unconditionally return True, causing discriminant
-- checks to fail. However, Check_Choices is now normally delayed
-- until the type's freeze entity is processed, due to requirements
-- coming from subtype predicates, so doing it at this point is
-- probably not right in general, but it's not clear how else to deal
-- with this situation. Perhaps we should only generate declarations
-- for the checking functions here, and somehow delay generation of
-- their bodies, but that would be a nontrivial change. ???
declare
VP : constant Node_Id :=
Variant_Part (Component_List (Type_Definition (Decl)));
begin
Check_Choices
(VP, Variants (VP), Etype (Name (VP)), Others_Present);
end;
-- We need the discriminant checking functions, since we generate
-- calls to these functions for the RM_Size expression, so make
-- sure that these functions have been constructed in time.
Build_Discr_Checking_Funcs (Decl);
-- Lay out the discriminants
First_Discr := First_Discriminant (E);
Last_Discr := First_Discr;
while Present (Next_Discriminant (Last_Discr)) loop
Next_Discriminant (Last_Discr);
end loop;
Layout_Components
(From => First_Discr,
To => Last_Discr,
Esiz => Esiz,
RM_Siz => RM_Siz);
-- Lay out the main component list (this will make recursive calls
-- to lay out all component lists nested within variants).
Layout_Component_List (Component_List (Tdef), Esiz, RM_Siz_Expr);
Set_Esize (E, Esiz);
-- If the RM_Size is a literal, set its value
if Nkind (RM_Siz_Expr) = N_Integer_Literal then
Set_RM_Size (E, Intval (RM_Siz_Expr));
-- Otherwise we construct a dynamic SO_Ref
else
Set_RM_Size (E,
SO_Ref_From_Expr
(RM_Siz_Expr,
Ins_Type => E,
Vtype => E));
end if;
end Layout_Variant_Record;
-- Start of processing for Layout_Record_Type
begin
-- If this is a cloned subtype, just copy the size fields from the
-- original, nothing else needs to be done in this case, since the
-- components themselves are all shared.
if Ekind_In (E, E_Record_Subtype, E_Class_Wide_Subtype)
and then Present (Cloned_Subtype (E))
then
Set_Esize (E, Esize (Cloned_Subtype (E)));
Set_RM_Size (E, RM_Size (Cloned_Subtype (E)));
Set_Alignment (E, Alignment (Cloned_Subtype (E)));
-- Another special case, class-wide types. The RM says that the size
-- of such types is implementation defined (RM 13.3(48)). What we do
-- here is to leave the fields set as unknown values, and the backend
-- determines the actual behavior.
elsif Ekind (E) = E_Class_Wide_Type then
null;
-- All other cases
else
-- Initialize alignment conservatively to 1. This value will be
-- increased as necessary during processing of the record.
if Unknown_Alignment (E) then
Set_Alignment (E, Uint_1);
end if;
-- Initialize previous component. This is Empty unless there are
-- components which have already been laid out by component clauses.
-- If there are such components, we start our lay out of the
-- remaining components following the last such component.
Prev_Comp := Empty;
Comp := First_Component_Or_Discriminant (E);
while Present (Comp) loop
if Present (Component_Clause (Comp)) then
if No (Prev_Comp)
or else
Component_Bit_Offset (Comp) >
Component_Bit_Offset (Prev_Comp)
then
Prev_Comp := Comp;
end if;
end if;
Next_Component_Or_Discriminant (Comp);
end loop;
-- We have two separate circuits, one for non-variant records and
-- one for variant records. For non-variant records, we simply go
-- through the list of components. This handles all the non-variant
-- cases including those cases of subtypes where there is no full
-- type declaration, so the tree cannot be used to drive the layout.
-- For variant records, we have to drive the layout from the tree
-- since we need to understand the variant structure in this case.
if Present (Full_View (E)) then
Decl := Declaration_Node (Full_View (E));
else
Decl := Declaration_Node (E);
end if;
-- Scan all the components
if Nkind (Decl) = N_Full_Type_Declaration
and then Has_Discriminants (E)
and then Nkind (Type_Definition (Decl)) = N_Record_Definition
and then Present (Component_List (Type_Definition (Decl)))
and then
Present (Variant_Part (Component_List (Type_Definition (Decl))))
then
Layout_Variant_Record;
else
Layout_Non_Variant_Record;
end if;
end if;
end Layout_Record_Type;
-----------------
-- Layout_Type --
-----------------
procedure Layout_Type (E : Entity_Id) is
Desig_Type : Entity_Id;
begin
-- For string literal types, for now, kill the size always, this is
-- because gigi does not like or need the size to be set ???
if Ekind (E) = E_String_Literal_Subtype then
Set_Esize (E, Uint_0);
Set_RM_Size (E, Uint_0);
return;
end if;
-- For access types, set size/alignment. This is system address size,
-- except for fat pointers (unconstrained array access types), where the
-- size is two times the address size, to accommodate the two pointers
-- that are required for a fat pointer (data and template). Note that
-- E_Access_Protected_Subprogram_Type is not an access type for this
-- purpose since it is not a pointer but is equivalent to a record. For
-- access subtypes, copy the size from the base type since Gigi
-- represents them the same way.
if Is_Access_Type (E) then
Desig_Type := Underlying_Type (Designated_Type (E));
-- If we only have a limited view of the type, see whether the
-- non-limited view is available.
if From_Limited_With (Designated_Type (E))
and then Ekind (Designated_Type (E)) = E_Incomplete_Type
and then Present (Non_Limited_View (Designated_Type (E)))
then
Desig_Type := Non_Limited_View (Designated_Type (E));
end if;
-- If Esize already set (e.g. by a size clause), then nothing further
-- to be done here.
if Known_Esize (E) then
null;
-- Access to subprogram is a strange beast, and we let the backend
-- figure out what is needed (it may be some kind of fat pointer,
-- including the static link for example.
elsif Is_Access_Protected_Subprogram_Type (E) then
null;
-- For access subtypes, copy the size information from base type
elsif Ekind (E) = E_Access_Subtype then
Set_Size_Info (E, Base_Type (E));
Set_RM_Size (E, RM_Size (Base_Type (E)));
-- For other access types, we use either address size, or, if a fat
-- pointer is used (pointer-to-unconstrained array case), twice the
-- address size to accommodate a fat pointer.
elsif Present (Desig_Type)
and then Is_Array_Type (Desig_Type)
and then not Is_Constrained (Desig_Type)
and then not Has_Completion_In_Body (Desig_Type)
-- Debug Flag -gnatd6 says make all pointers to unconstrained thin
and then not Debug_Flag_6
then
Init_Size (E, 2 * System_Address_Size);
-- Check for bad convention set
if Warn_On_Export_Import
and then
(Convention (E) = Convention_C
or else
Convention (E) = Convention_CPP)
then
Error_Msg_N
("?x?this access type does not correspond to C pointer", E);
end if;
-- If the designated type is a limited view it is unanalyzed. We can
-- examine the declaration itself to determine whether it will need a
-- fat pointer.
elsif Present (Desig_Type)
and then Present (Parent (Desig_Type))
and then Nkind (Parent (Desig_Type)) = N_Full_Type_Declaration
and then Nkind (Type_Definition (Parent (Desig_Type))) =
N_Unconstrained_Array_Definition
and then not Debug_Flag_6
then
Init_Size (E, 2 * System_Address_Size);
-- When the target is AAMP, access-to-subprogram types are fat
-- pointers consisting of the subprogram address and a static link,
-- with the exception of library-level access types (including
-- library-level anonymous access types, such as for components),
-- where a simple subprogram address is used.
elsif AAMP_On_Target
and then
((Ekind (E) = E_Access_Subprogram_Type
and then Present (Enclosing_Subprogram (E)))
or else
(Ekind (E) = E_Anonymous_Access_Subprogram_Type
and then
(not Is_Local_Anonymous_Access (E)
or else Present (Enclosing_Subprogram (E)))))
then
Init_Size (E, 2 * System_Address_Size);
-- Normal case of thin pointer
else
Init_Size (E, System_Address_Size);
end if;
Set_Elem_Alignment (E);
-- Scalar types: set size and alignment
elsif Is_Scalar_Type (E) then
-- For discrete types, the RM_Size and Esize must be set already,
-- since this is part of the earlier processing and the front end is
-- always required to lay out the sizes of such types (since they are
-- available as static attributes). All we do is to check that this
-- rule is indeed obeyed.
if Is_Discrete_Type (E) then
-- If the RM_Size is not set, then here is where we set it
-- Note: an RM_Size of zero looks like not set here, but this
-- is a rare case, and we can simply reset it without any harm.
if not Known_RM_Size (E) then
Set_Discrete_RM_Size (E);
end if;
-- If Esize for a discrete type is not set then set it
if not Known_Esize (E) then
declare
S : Int := 8;
begin
loop
-- If size is big enough, set it and exit
if S >= RM_Size (E) then
Init_Esize (E, S);
exit;
-- If the RM_Size is greater than 64 (happens only when
-- strange values are specified by the user, then Esize
-- is simply a copy of RM_Size, it will be further
-- refined later on)
elsif S = 64 then
Set_Esize (E, RM_Size (E));
exit;
-- Otherwise double possible size and keep trying
else
S := S * 2;
end if;
end loop;
end;
end if;
-- For non-discrete scalar types, if the RM_Size is not set, then set
-- it now to a copy of the Esize if the Esize is set.
else
if Known_Esize (E) and then Unknown_RM_Size (E) then
Set_RM_Size (E, Esize (E));
end if;
end if;
Set_Elem_Alignment (E);
-- Non-elementary (composite) types
else
-- For packed arrays, take size and alignment values from the packed
-- array type if a packed array type has been created and the fields
-- are not currently set.
if Is_Array_Type (E)
and then Present (Packed_Array_Impl_Type (E))
then
declare
PAT : constant Entity_Id := Packed_Array_Impl_Type (E);
begin
if Unknown_Esize (E) then
Set_Esize (E, Esize (PAT));
end if;
if Unknown_RM_Size (E) then
Set_RM_Size (E, RM_Size (PAT));
end if;
if Unknown_Alignment (E) then
Set_Alignment (E, Alignment (PAT));
end if;
end;
end if;
-- If Esize is set, and RM_Size is not, RM_Size is copied from Esize.
-- At least for now this seems reasonable, and is in any case needed
-- for compatibility with old versions of gigi.
if Known_Esize (E) and then Unknown_RM_Size (E) then
Set_RM_Size (E, Esize (E));
end if;
-- For array base types, set component size if object size of the
-- component type is known and is a small power of 2 (8, 16, 32, 64),
-- since this is what will always be used.
if Ekind (E) = E_Array_Type and then Unknown_Component_Size (E) then
declare
CT : constant Entity_Id := Component_Type (E);
begin
-- For some reason, access types can cause trouble, So let's
-- just do this for scalar types ???
if Present (CT)
and then Is_Scalar_Type (CT)
and then Known_Static_Esize (CT)
then
declare
S : constant Uint := Esize (CT);
begin
if Addressable (S) then
Set_Component_Size (E, S);
end if;
end;
end if;
end;
end if;
end if;
-- Lay out array and record types if front end layout set
if Frontend_Layout_On_Target then
if Is_Array_Type (E) and then not Is_Bit_Packed_Array (E) then
Layout_Array_Type (E);
elsif Is_Record_Type (E) then
Layout_Record_Type (E);
end if;
-- Case of backend layout, we still do a little in the front end
else
-- Processing for record types
if Is_Record_Type (E) then
-- Special remaining processing for record types with a known
-- size of 16, 32, or 64 bits whose alignment is not yet set.
-- For these types, we set a corresponding alignment matching
-- the size if possible, or as large as possible if not.
if Convention (E) = Convention_Ada and then not Debug_Flag_Q then
Set_Composite_Alignment (E);
end if;
-- Processing for array types
elsif Is_Array_Type (E) then
-- For arrays that are required to be atomic, we do the same
-- processing as described above for short records, since we
-- really need to have the alignment set for the whole array.
if Is_Atomic (E) and then not Debug_Flag_Q then
Set_Composite_Alignment (E);
end if;
-- For unpacked array types, set an alignment of 1 if we know
-- that the component alignment is not greater than 1. The reason
-- we do this is to avoid unnecessary copying of slices of such
-- arrays when passed to subprogram parameters (see special test
-- in Exp_Ch6.Expand_Actuals).
if not Is_Packed (E) and then Unknown_Alignment (E) then
if Known_Static_Component_Size (E)
and then Component_Size (E) = 1
then
Set_Alignment (E, Uint_1);
end if;
end if;
-- We need to know whether the size depends on the value of one
-- or more discriminants to select the return mechanism. Skip if
-- errors are present, to prevent cascaded messages.
if Serious_Errors_Detected = 0 then
Compute_Size_Depends_On_Discriminant (E);
end if;
end if;
end if;
-- Final step is to check that Esize and RM_Size are compatible
if Known_Static_Esize (E) and then Known_Static_RM_Size (E) then
if Esize (E) < RM_Size (E) then
-- Esize is less than RM_Size. That's not good. First we test
-- whether this was set deliberately with an Object_Size clause
-- and if so, object to the clause.
if Has_Object_Size_Clause (E) then
Error_Msg_Uint_1 := RM_Size (E);
Error_Msg_F
("object size is too small, minimum allowed is ^",
Expression (Get_Attribute_Definition_Clause
(E, Attribute_Object_Size)));
end if;
-- Adjust Esize up to RM_Size value
declare
Size : constant Uint := RM_Size (E);
begin
Set_Esize (E, RM_Size (E));
-- For scalar types, increase Object_Size to power of 2, but
-- not less than a storage unit in any case (i.e., normally
-- this means it will be storage-unit addressable).
if Is_Scalar_Type (E) then
if Size <= System_Storage_Unit then
Init_Esize (E, System_Storage_Unit);
elsif Size <= 16 then
Init_Esize (E, 16);
elsif Size <= 32 then
Init_Esize (E, 32);
else
Set_Esize (E, (Size + 63) / 64 * 64);
end if;
-- Finally, make sure that alignment is consistent with
-- the newly assigned size.
while Alignment (E) * System_Storage_Unit < Esize (E)
and then Alignment (E) < Maximum_Alignment
loop
Set_Alignment (E, 2 * Alignment (E));
end loop;
end if;
end;
end if;
end if;
end Layout_Type;
---------------------
-- Rewrite_Integer --
---------------------
procedure Rewrite_Integer (N : Node_Id; V : Uint) is
Loc : constant Source_Ptr := Sloc (N);
Typ : constant Entity_Id := Etype (N);
begin
Rewrite (N, Make_Integer_Literal (Loc, Intval => V));
Set_Etype (N, Typ);
end Rewrite_Integer;
-------------------------------
-- Set_And_Check_Static_Size --
-------------------------------
procedure Set_And_Check_Static_Size
(E : Entity_Id;
Esiz : SO_Ref;
RM_Siz : SO_Ref)
is
SC : Node_Id;
procedure Check_Size_Too_Small (Spec : Uint; Min : Uint);
-- Spec is the number of bit specified in the size clause, and Min is
-- the minimum computed size. An error is given that the specified size
-- is too small if Spec < Min, and in this case both Esize and RM_Size
-- are set to unknown in E. The error message is posted on node SC.
procedure Check_Unused_Bits (Spec : Uint; Max : Uint);
-- Spec is the number of bits specified in the size clause, and Max is
-- the maximum computed size. A warning is given about unused bits if
-- Spec > Max. This warning is posted on node SC.
--------------------------
-- Check_Size_Too_Small --
--------------------------
procedure Check_Size_Too_Small (Spec : Uint; Min : Uint) is
begin
if Spec < Min then
Error_Msg_Uint_1 := Min;
Error_Msg_NE ("size for & too small, minimum allowed is ^", SC, E);
Init_Esize (E);
Init_RM_Size (E);
end if;
end Check_Size_Too_Small;
-----------------------
-- Check_Unused_Bits --
-----------------------
procedure Check_Unused_Bits (Spec : Uint; Max : Uint) is
begin
if Spec > Max then
Error_Msg_Uint_1 := Spec - Max;
Error_Msg_NE ("??^ bits of & unused", SC, E);
end if;
end Check_Unused_Bits;
-- Start of processing for Set_And_Check_Static_Size
begin
-- Case where Object_Size (Esize) is already set by a size clause
if Known_Static_Esize (E) then
SC := Size_Clause (E);
if No (SC) then
SC := Get_Attribute_Definition_Clause (E, Attribute_Object_Size);
end if;
-- Perform checks on specified size against computed sizes
if Present (SC) then
Check_Unused_Bits (Esize (E), Esiz);
Check_Size_Too_Small (Esize (E), RM_Siz);
end if;
end if;
-- Case where Value_Size (RM_Size) is set by specific Value_Size clause
-- (we do not need to worry about Value_Size being set by a Size clause,
-- since that will have set Esize as well, and we already took care of
-- that case).
if Known_Static_RM_Size (E) then
SC := Get_Attribute_Definition_Clause (E, Attribute_Value_Size);
-- Perform checks on specified size against computed sizes
if Present (SC) then
Check_Unused_Bits (RM_Size (E), Esiz);
Check_Size_Too_Small (RM_Size (E), RM_Siz);
end if;
end if;
-- Set sizes if unknown
if Unknown_Esize (E) then
Set_Esize (E, Esiz);
end if;
if Unknown_RM_Size (E) then
Set_RM_Size (E, RM_Siz);
end if;
end Set_And_Check_Static_Size;
-----------------------------
-- Set_Composite_Alignment --
-----------------------------
procedure Set_Composite_Alignment (E : Entity_Id) is
Siz : Uint;
Align : Nat;
begin
-- If alignment is already set, then nothing to do
if Known_Alignment (E) then
return;
end if;
-- Alignment is not known, see if we can set it, taking into account
-- the setting of the Optimize_Alignment mode.
-- If Optimize_Alignment is set to Space, then we try to give packed
-- records an aligmment of 1, unless there is some reason we can't.
if Optimize_Alignment_Space (E)
and then Is_Record_Type (E)
and then Is_Packed (E)
then
-- No effect for record with atomic components
if Is_Atomic (E) then
Error_Msg_N ("Optimize_Alignment has no effect for &??", E);
Error_Msg_N ("\pragma ignored for atomic record??", E);
return;
end if;
-- No effect if independent components
if Has_Independent_Components (E) then
Error_Msg_N ("Optimize_Alignment has no effect for &??", E);
Error_Msg_N
("\pragma ignored for record with independent components??", E);
return;
end if;
-- No effect if any component is atomic or is a by reference type
declare
Ent : Entity_Id;
begin
Ent := First_Component_Or_Discriminant (E);
while Present (Ent) loop
if Is_By_Reference_Type (Etype (Ent))
or else Is_Atomic (Etype (Ent))
or else Is_Atomic (Ent)
then
Error_Msg_N ("Optimize_Alignment has no effect for &??", E);
Error_Msg_N
("\pragma is ignored if atomic components present??", E);
return;
else
Next_Component_Or_Discriminant (Ent);
end if;
end loop;
end;
-- Optimize_Alignment has no effect on variable length record
if not Size_Known_At_Compile_Time (E) then
Error_Msg_N ("Optimize_Alignment has no effect for &??", E);
Error_Msg_N ("\pragma is ignored for variable length record??", E);
return;
end if;
-- All tests passed, we can set alignment to 1
Align := 1;
-- Not a record, or not packed
else
-- The only other cases we worry about here are where the size is
-- statically known at compile time.
if Known_Static_Esize (E) then
Siz := Esize (E);
elsif Unknown_Esize (E) and then Known_Static_RM_Size (E) then
Siz := RM_Size (E);
else
return;
end if;
-- Size is known, alignment is not set
-- Reset alignment to match size if the known size is exactly 2, 4,
-- or 8 storage units.
if Siz = 2 * System_Storage_Unit then
Align := 2;
elsif Siz = 4 * System_Storage_Unit then
Align := 4;
elsif Siz = 8 * System_Storage_Unit then
Align := 8;
-- If Optimize_Alignment is set to Space, then make sure the
-- alignment matches the size, for example, if the size is 17
-- bytes then we want an alignment of 1 for the type.
elsif Optimize_Alignment_Space (E) then
if Siz mod (8 * System_Storage_Unit) = 0 then
Align := 8;
elsif Siz mod (4 * System_Storage_Unit) = 0 then
Align := 4;
elsif Siz mod (2 * System_Storage_Unit) = 0 then
Align := 2;
else
Align := 1;
end if;
-- If Optimize_Alignment is set to Time, then we reset for odd
-- "in between sizes", for example a 17 bit record is given an
-- alignment of 4.
elsif Optimize_Alignment_Time (E)
and then Siz > System_Storage_Unit
and then Siz <= 8 * System_Storage_Unit
then
if Siz <= 2 * System_Storage_Unit then
Align := 2;
elsif Siz <= 4 * System_Storage_Unit then
Align := 4;
else -- Siz <= 8 * System_Storage_Unit then
Align := 8;
end if;
-- No special alignment fiddling needed
else
return;
end if;
end if;
-- Here we have Set Align to the proposed improved value. Make sure the
-- value set does not exceed Maximum_Alignment for the target.
if Align > Maximum_Alignment then
Align := Maximum_Alignment;
end if;
-- Further processing for record types only to reduce the alignment
-- set by the above processing in some specific cases. We do not
-- do this for atomic records, since we need max alignment there,
if Is_Record_Type (E) and then not Is_Atomic (E) then
-- For records, there is generally no point in setting alignment
-- higher than word size since we cannot do better than move by
-- words in any case. Omit this if we are optimizing for time,
-- since conceivably we may be able to do better.
if Align > System_Word_Size / System_Storage_Unit
and then not Optimize_Alignment_Time (E)
then
Align := System_Word_Size / System_Storage_Unit;
end if;
-- Check components. If any component requires a higher alignment,
-- then we set that higher alignment in any case. Don't do this if
-- we have Optimize_Alignment set to Space. Note that that covers
-- the case of packed records, where we already set alignment to 1.
if not Optimize_Alignment_Space (E) then
declare
Comp : Entity_Id;
begin
Comp := First_Component (E);
while Present (Comp) loop
if Known_Alignment (Etype (Comp)) then
declare
Calign : constant Uint := Alignment (Etype (Comp));
begin
-- The cases to process are when the alignment of the
-- component type is larger than the alignment we have
-- so far, and either there is no component clause for
-- the component, or the length set by the component
-- clause matches the length of the component type.
if Calign > Align
and then
(Unknown_Esize (Comp)
or else (Known_Static_Esize (Comp)
and then
Esize (Comp) =
Calign * System_Storage_Unit))
then
Align := UI_To_Int (Calign);
end if;
end;
end if;
Next_Component (Comp);
end loop;
end;
end if;
end if;
-- Set chosen alignment, and increase Esize if necessary to match the
-- chosen alignment.
Set_Alignment (E, UI_From_Int (Align));
if Known_Static_Esize (E)
and then Esize (E) < Align * System_Storage_Unit
then
Set_Esize (E, UI_From_Int (Align * System_Storage_Unit));
end if;
end Set_Composite_Alignment;
--------------------------
-- Set_Discrete_RM_Size --
--------------------------
procedure Set_Discrete_RM_Size (Def_Id : Entity_Id) is
FST : constant Entity_Id := First_Subtype (Def_Id);
begin
-- All discrete types except for the base types in standard are
-- constrained, so indicate this by setting Is_Constrained.
Set_Is_Constrained (Def_Id);
-- Set generic types to have an unknown size, since the representation
-- of a generic type is irrelevant, in view of the fact that they have
-- nothing to do with code.
if Is_Generic_Type (Root_Type (FST)) then
Set_RM_Size (Def_Id, Uint_0);
-- If the subtype statically matches the first subtype, then it is
-- required to have exactly the same layout. This is required by
-- aliasing considerations.
elsif Def_Id /= FST and then
Subtypes_Statically_Match (Def_Id, FST)
then
Set_RM_Size (Def_Id, RM_Size (FST));
Set_Size_Info (Def_Id, FST);
-- In all other cases the RM_Size is set to the minimum size. Note that
-- this routine is never called for subtypes for which the RM_Size is
-- set explicitly by an attribute clause.
else
Set_RM_Size (Def_Id, UI_From_Int (Minimum_Size (Def_Id)));
end if;
end Set_Discrete_RM_Size;
------------------------
-- Set_Elem_Alignment --
------------------------
procedure Set_Elem_Alignment (E : Entity_Id) is
begin
-- Do not set alignment for packed array types, unless we are doing
-- front end layout, because otherwise this is always handled in the
-- backend.
if Is_Packed_Array_Impl_Type (E)
and then not Frontend_Layout_On_Target
then
return;
-- If there is an alignment clause, then we respect it
elsif Has_Alignment_Clause (E) then
return;
-- If the size is not set, then don't attempt to set the alignment. This
-- happens in the backend layout case for access-to-subprogram types.
elsif not Known_Static_Esize (E) then
return;
-- For access types, do not set the alignment if the size is less than
-- the allowed minimum size. This avoids cascaded error messages.
elsif Is_Access_Type (E) and then Esize (E) < System_Address_Size then
return;
end if;
-- Here we calculate the alignment as the largest power of two multiple
-- of System.Storage_Unit that does not exceed either the object size of
-- the type, or the maximum allowed alignment.
declare
S : Int;
A : Nat;
Max_Alignment : Nat;
begin
-- The given Esize may be larger that int'last because of a previous
-- error, and the call to UI_To_Int will fail, so use default.
if Esize (E) / SSU > Ttypes.Maximum_Alignment then
S := Ttypes.Maximum_Alignment;
-- If this is an access type and the target doesn't have strict
-- alignment and we are not doing front end layout, then cap the
-- alignment to that of a regular access type. This will avoid
-- giving fat pointers twice the usual alignment for no practical
-- benefit since the misalignment doesn't really matter.
elsif Is_Access_Type (E)
and then not Target_Strict_Alignment
and then not Frontend_Layout_On_Target
then
S := System_Address_Size / SSU;
else
S := UI_To_Int (Esize (E)) / SSU;
end if;
-- If the default alignment of "double" floating-point types is
-- specifically capped, enforce the cap.
if Ttypes.Target_Double_Float_Alignment > 0
and then S = 8
and then Is_Floating_Point_Type (E)
then
Max_Alignment := Ttypes.Target_Double_Float_Alignment;
-- If the default alignment of "double" or larger scalar types is
-- specifically capped, enforce the cap.
elsif Ttypes.Target_Double_Scalar_Alignment > 0
and then S >= 8
and then Is_Scalar_Type (E)
then
Max_Alignment := Ttypes.Target_Double_Scalar_Alignment;
-- Otherwise enforce the overall alignment cap
else
Max_Alignment := Ttypes.Maximum_Alignment;
end if;
A := 1;
while 2 * A <= Max_Alignment and then 2 * A <= S loop
A := 2 * A;
end loop;
-- If alignment is currently not set, then we can safetly set it to
-- this new calculated value.
if Unknown_Alignment (E) then
Init_Alignment (E, A);
-- Cases where we have inherited an alignment
-- For constructed types, always reset the alignment, these are
-- Generally invisible to the user anyway, and that way we are
-- sure that no constructed types have weird alignments.
elsif not Comes_From_Source (E) then
Init_Alignment (E, A);
-- If this inherited alignment is the same as the one we computed,
-- then obviously everything is fine, and we do not need to reset it.
elsif Alignment (E) = A then
null;
-- Now we come to the difficult cases where we have inherited an
-- alignment and size, but overridden the size but not the alignment.
elsif Has_Size_Clause (E) or else Has_Object_Size_Clause (E) then
-- This is tricky, it might be thought that we should try to
-- inherit the alignment, since that's what the RM implies, but
-- that leads to complex rules and oddities. Consider for example:
-- type R is new Character;
-- for R'Size use 16;
-- It seems quite bogus in this case to inherit an alignment of 1
-- from the parent type Character. Furthermore, if that's what the
-- programmer really wanted for some odd reason, then they could
-- specify the alignment they wanted.
-- Furthermore we really don't want to inherit the alignment in
-- the case of a specified Object_Size for a subtype, since then
-- there would be no way of overriding to give a reasonable value
-- (we don't have an Object_Subtype attribute). Consider:
-- subtype R is new Character;
-- for R'Object_Size use 16;
-- If we inherit the alignment of 1, then we have an odd
-- inefficient alignment for the subtype, which cannot be fixed.
-- So we make the decision that if Size (or Object_Size) is given
-- (and, in the case of a first subtype, the alignment is not set
-- with a specific alignment clause). We reset the alignment to
-- the appropriate value for the specified size. This is a nice
-- simple rule to implement and document.
-- There is one slight glitch, which is that a confirming size
-- clause can now change the alignment, which, if we really think
-- that confirming rep clauses should have no effect, is a no-no.
-- type R is new Character;
-- for R'Alignment use 2;
-- type S is new R;
-- for S'Size use Character'Size;
-- Now the alignment of S is 1 instead of 2, as a result of
-- applying the above rule to the confirming rep clause for S. Not
-- clear this is worth worrying about. If we recorded whether a
-- size clause was confirming we could avoid this, but right now
-- we have no way of doing that or easily figuring it out, so we
-- don't bother.
-- Historical note. In versions of GNAT prior to Nov 6th, 2010, an
-- odd distinction was made between inherited alignments greater
-- than the computed alignment (where the larger alignment was
-- inherited) and inherited alignments smaller than the computed
-- alignment (where the smaller alignment was overridden). This
-- was a dubious fix to get around an ACATS problem which seems
-- to have disappeared anyway, and in any case, this peculiarity
-- was never documented.
Init_Alignment (E, A);
-- If no Size (or Object_Size) was specified, then we inherited the
-- object size, so we should inherit the alignment as well and not
-- modify it. This takes care of cases like:
-- type R is new Integer;
-- for R'Alignment use 1;
-- subtype S is R;
-- Here we have R has a default Object_Size of 32, and a specified
-- alignment of 1, and it seeems right for S to inherit both values.
else
null;
end if;
end;
end Set_Elem_Alignment;
----------------------
-- SO_Ref_From_Expr --
----------------------
function SO_Ref_From_Expr
(Expr : Node_Id;
Ins_Type : Entity_Id;
Vtype : Entity_Id := Empty;
Make_Func : Boolean := False) return Dynamic_SO_Ref
is
Loc : constant Source_Ptr := Sloc (Ins_Type);
K : constant Entity_Id := Make_Temporary (Loc, 'K');
Decl : Node_Id;
Vtype_Primary_View : Entity_Id;
function Check_Node_V_Ref (N : Node_Id) return Traverse_Result;
-- Function used to check one node for reference to V
function Has_V_Ref is new Traverse_Func (Check_Node_V_Ref);
-- Function used to traverse tree to check for reference to V
----------------------
-- Check_Node_V_Ref --
----------------------
function Check_Node_V_Ref (N : Node_Id) return Traverse_Result is
begin
if Nkind (N) = N_Identifier then
if Chars (N) = Vname then
return Abandon;
else
return Skip;
end if;
else
return OK;
end if;
end Check_Node_V_Ref;
-- Start of processing for SO_Ref_From_Expr
begin
-- Case of expression is an integer literal, in this case we just
-- return the value (which must always be non-negative, since size
-- and offset values can never be negative).
if Nkind (Expr) = N_Integer_Literal then
pragma Assert (Intval (Expr) >= 0);
return Intval (Expr);
end if;
-- Case where there is a reference to V, create function
if Has_V_Ref (Expr) = Abandon then
pragma Assert (Present (Vtype));
-- Check whether Vtype is a view of a private type and ensure that
-- we use the primary view of the type (which is denoted by its
-- Etype, whether it's the type's partial or full view entity).
-- This is needed to make sure that we use the same (primary) view
-- of the type for all V formals, whether the current view of the
-- type is the partial or full view, so that types will always
-- match on calls from one size function to another.
if Has_Private_Declaration (Vtype) then
Vtype_Primary_View := Etype (Vtype);
else
Vtype_Primary_View := Vtype;
end if;
Set_Is_Discrim_SO_Function (K);
Decl :=
Make_Subprogram_Body (Loc,
Specification =>
Make_Function_Specification (Loc,
Defining_Unit_Name => K,
Parameter_Specifications => New_List (
Make_Parameter_Specification (Loc,
Defining_Identifier =>
Make_Defining_Identifier (Loc, Chars => Vname),
Parameter_Type =>
New_Occurrence_Of (Vtype_Primary_View, Loc))),
Result_Definition =>
New_Occurrence_Of (Standard_Unsigned, Loc)),
Declarations => Empty_List,
Handled_Statement_Sequence =>
Make_Handled_Sequence_Of_Statements (Loc,
Statements => New_List (
Make_Simple_Return_Statement (Loc,
Expression => Expr))));
-- The caller requests that the expression be encapsulated in a
-- parameterless function.
elsif Make_Func then
Decl :=
Make_Subprogram_Body (Loc,
Specification =>
Make_Function_Specification (Loc,
Defining_Unit_Name => K,
Parameter_Specifications => Empty_List,
Result_Definition =>
New_Occurrence_Of (Standard_Unsigned, Loc)),
Declarations => Empty_List,
Handled_Statement_Sequence =>
Make_Handled_Sequence_Of_Statements (Loc,
Statements => New_List (
Make_Simple_Return_Statement (Loc, Expression => Expr))));
-- No reference to V and function not requested, so create a constant
else
Decl :=
Make_Object_Declaration (Loc,
Defining_Identifier => K,
Object_Definition =>
New_Occurrence_Of (Standard_Unsigned, Loc),
Constant_Present => True,
Expression => Expr);
end if;
Append_Freeze_Action (Ins_Type, Decl);
Analyze (Decl);
return Create_Dynamic_SO_Ref (K);
end SO_Ref_From_Expr;
end Layout;