1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 2001-2009, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree; use Atree;
27 with Checks; use Checks;
28 with Debug; use Debug;
29 with Einfo; use Einfo;
30 with Errout; use Errout;
31 with Exp_Ch3; use Exp_Ch3;
32 with Exp_Util; use Exp_Util;
33 with Namet; use Namet;
34 with Nlists; use Nlists;
35 with Nmake; use Nmake;
37 with Repinfo; use Repinfo;
39 with Sem_Aux; use Sem_Aux;
40 with Sem_Ch13; use Sem_Ch13;
41 with Sem_Eval; use Sem_Eval;
42 with Sem_Util; use Sem_Util;
43 with Sinfo; use Sinfo;
44 with Snames; use Snames;
45 with Stand; use Stand;
46 with Targparm; use Targparm;
47 with Tbuild; use Tbuild;
48 with Ttypes; use Ttypes;
49 with Uintp; use Uintp;
51 package body Layout is
53 ------------------------
54 -- Local Declarations --
55 ------------------------
57 SSU : constant Int := Ttypes.System_Storage_Unit;
58 -- Short hand for System_Storage_Unit
60 Vname : constant Name_Id := Name_uV;
61 -- Formal parameter name used for functions generated for size offset
62 -- values that depend on the discriminant. All such functions have the
65 -- function xxx (V : vtyp) return Unsigned is
67 -- return ... expression involving V.discrim
70 -----------------------
71 -- Local Subprograms --
72 -----------------------
77 Right_Opnd : Node_Id) return Node_Id;
78 -- This is like Make_Op_Add except that it optimizes some cases knowing
79 -- that associative rearrangement is allowed for constant folding if one
80 -- of the operands is a compile time known value.
82 function Assoc_Multiply
85 Right_Opnd : Node_Id) return Node_Id;
86 -- This is like Make_Op_Multiply except that it optimizes some cases
87 -- knowing that associative rearrangement is allowed for constant folding
88 -- if one of the operands is a compile time known value
90 function Assoc_Subtract
93 Right_Opnd : Node_Id) return Node_Id;
94 -- This is like Make_Op_Subtract except that it optimizes some cases
95 -- knowing that associative rearrangement is allowed for constant folding
96 -- if one of the operands is a compile time known value
98 function Bits_To_SU (N : Node_Id) return Node_Id;
99 -- This is used when we cross the boundary from static sizes in bits to
100 -- dynamic sizes in storage units. If the argument N is anything other
101 -- than an integer literal, it is returned unchanged, but if it is an
102 -- integer literal, then it is taken as a size in bits, and is replaced
103 -- by the corresponding size in storage units.
105 function Compute_Length (Lo : Node_Id; Hi : Node_Id) return Node_Id;
106 -- Given expressions for the low bound (Lo) and the high bound (Hi),
107 -- Build an expression for the value hi-lo+1, converted to type
108 -- Standard.Unsigned. Takes care of the case where the operands
109 -- are of an enumeration type (so that the subtraction cannot be
110 -- done directly) by applying the Pos operator to Hi/Lo first.
112 function Expr_From_SO_Ref
115 Comp : Entity_Id := Empty) return Node_Id;
116 -- Given a value D from a size or offset field, return an expression
117 -- representing the value stored. If the value is known at compile time,
118 -- then an N_Integer_Literal is returned with the appropriate value. If
119 -- the value references a constant entity, then an N_Identifier node
120 -- referencing this entity is returned. If the value denotes a size
121 -- function, then returns a call node denoting the given function, with
122 -- a single actual parameter that either refers to the parameter V of
123 -- an enclosing size function (if Comp is Empty or its type doesn't match
124 -- the function's formal), or else is a selected component V.c when Comp
125 -- denotes a component c whose type matches that of the function formal.
126 -- The Loc value is used for the Sloc value of constructed notes.
128 function SO_Ref_From_Expr
130 Ins_Type : Entity_Id;
131 Vtype : Entity_Id := Empty;
132 Make_Func : Boolean := False) return Dynamic_SO_Ref;
133 -- This routine is used in the case where a size/offset value is dynamic
134 -- and is represented by the expression Expr. SO_Ref_From_Expr checks if
135 -- the Expr contains a reference to the identifier V, and if so builds
136 -- a function depending on discriminants of the formal parameter V which
137 -- is of type Vtype. Otherwise, if the parameter Make_Func is True, then
138 -- Expr will be encapsulated in a parameterless function; if Make_Func is
139 -- False, then a constant entity with the value Expr is built. The result
140 -- is a Dynamic_SO_Ref to the created entity. Note that Vtype can be
141 -- omitted if Expr does not contain any reference to V, the created entity.
142 -- The declaration created is inserted in the freeze actions of Ins_Type,
143 -- which also supplies the Sloc for created nodes. This function also takes
144 -- care of making sure that the expression is properly analyzed and
145 -- resolved (which may not be the case yet if we build the expression
148 function Get_Max_SU_Size (E : Entity_Id) return Node_Id;
149 -- E is an array type or subtype that has at least one index bound that
150 -- is the value of a record discriminant. For such an array, the function
151 -- computes an expression that yields the maximum possible size of the
152 -- array in storage units. The result is not defined for any other type,
153 -- or for arrays that do not depend on discriminants, and it is a fatal
154 -- error to call this unless Size_Depends_On_Discriminant (E) is True.
156 procedure Layout_Array_Type (E : Entity_Id);
157 -- Front-end layout of non-bit-packed array type or subtype
159 procedure Layout_Record_Type (E : Entity_Id);
160 -- Front-end layout of record type
162 procedure Rewrite_Integer (N : Node_Id; V : Uint);
163 -- Rewrite node N with an integer literal whose value is V. The Sloc for
164 -- the new node is taken from N, and the type of the literal is set to a
165 -- copy of the type of N on entry.
167 procedure Set_And_Check_Static_Size
171 -- This procedure is called to check explicit given sizes (possibly stored
172 -- in the Esize and RM_Size fields of E) against computed Object_Size
173 -- (Esiz) and Value_Size (RM_Siz) values. Appropriate errors and warnings
174 -- are posted if specified sizes are inconsistent with specified sizes. On
175 -- return, Esize and RM_Size fields of E are set (either from previously
176 -- given values, or from the newly computed values, as appropriate).
178 procedure Set_Composite_Alignment (E : Entity_Id);
179 -- This procedure is called for record types and subtypes, and also for
180 -- atomic array types and subtypes. If no alignment is set, and the size
181 -- is 2 or 4 (or 8 if the word size is 8), then the alignment is set to
184 ----------------------------
185 -- Adjust_Esize_Alignment --
186 ----------------------------
188 procedure Adjust_Esize_Alignment (E : Entity_Id) is
193 -- Nothing to do if size unknown
195 if Unknown_Esize (E) then
199 -- Determine if size is constrained by an attribute definition clause
200 -- which must be obeyed. If so, we cannot increase the size in this
203 -- For a type, the issue is whether an object size clause has been set.
204 -- A normal size clause constrains only the value size (RM_Size)
207 Esize_Set := Has_Object_Size_Clause (E);
209 -- For an object, the issue is whether a size clause is present
212 Esize_Set := Has_Size_Clause (E);
215 -- If size is known it must be a multiple of the storage unit size
217 if Esize (E) mod SSU /= 0 then
219 -- If not, and size specified, then give error
223 ("size for& not a multiple of storage unit size",
227 -- Otherwise bump up size to a storage unit boundary
230 Set_Esize (E, (Esize (E) + SSU - 1) / SSU * SSU);
234 -- Now we have the size set, it must be a multiple of the alignment
235 -- nothing more we can do here if the alignment is unknown here.
237 if Unknown_Alignment (E) then
241 -- At this point both the Esize and Alignment are known, so we need
242 -- to make sure they are consistent.
244 Abits := UI_To_Int (Alignment (E)) * SSU;
246 if Esize (E) mod Abits = 0 then
250 -- Here we have a situation where the Esize is not a multiple of the
251 -- alignment. We must either increase Esize or reduce the alignment to
252 -- correct this situation.
254 -- The case in which we can decrease the alignment is where the
255 -- alignment was not set by an alignment clause, and the type in
256 -- question is a discrete type, where it is definitely safe to reduce
257 -- the alignment. For example:
259 -- t : integer range 1 .. 2;
262 -- In this situation, the initial alignment of t is 4, copied from
263 -- the Integer base type, but it is safe to reduce it to 1 at this
264 -- stage, since we will only be loading a single storage unit.
266 if Is_Discrete_Type (Etype (E))
267 and then not Has_Alignment_Clause (E)
271 exit when Esize (E) mod Abits = 0;
274 Init_Alignment (E, Abits / SSU);
278 -- Now the only possible approach left is to increase the Esize but we
279 -- can't do that if the size was set by a specific clause.
283 ("size for& is not a multiple of alignment",
286 -- Otherwise we can indeed increase the size to a multiple of alignment
289 Set_Esize (E, ((Esize (E) + (Abits - 1)) / Abits) * Abits);
291 end Adjust_Esize_Alignment;
300 Right_Opnd : Node_Id) return Node_Id
306 -- Case of right operand is a constant
308 if Compile_Time_Known_Value (Right_Opnd) then
310 R := Expr_Value (Right_Opnd);
312 -- Case of left operand is a constant
314 elsif Compile_Time_Known_Value (Left_Opnd) then
316 R := Expr_Value (Left_Opnd);
318 -- Neither operand is a constant, do the addition with no optimization
321 return Make_Op_Add (Loc, Left_Opnd, Right_Opnd);
324 -- Case of left operand is an addition
326 if Nkind (L) = N_Op_Add then
328 -- (C1 + E) + C2 = (C1 + C2) + E
330 if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
332 (Sinfo.Left_Opnd (L),
333 Expr_Value (Sinfo.Left_Opnd (L)) + R);
336 -- (E + C1) + C2 = E + (C1 + C2)
338 elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L)) then
340 (Sinfo.Right_Opnd (L),
341 Expr_Value (Sinfo.Right_Opnd (L)) + R);
345 -- Case of left operand is a subtraction
347 elsif Nkind (L) = N_Op_Subtract then
349 -- (C1 - E) + C2 = (C1 + C2) + E
351 if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
353 (Sinfo.Left_Opnd (L),
354 Expr_Value (Sinfo.Left_Opnd (L)) + R);
357 -- (E - C1) + C2 = E - (C1 - C2)
359 elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L)) then
361 (Sinfo.Right_Opnd (L),
362 Expr_Value (Sinfo.Right_Opnd (L)) - R);
367 -- Not optimizable, do the addition
369 return Make_Op_Add (Loc, Left_Opnd, Right_Opnd);
376 function Assoc_Multiply
379 Right_Opnd : Node_Id) return Node_Id
385 -- Case of right operand is a constant
387 if Compile_Time_Known_Value (Right_Opnd) then
389 R := Expr_Value (Right_Opnd);
391 -- Case of left operand is a constant
393 elsif Compile_Time_Known_Value (Left_Opnd) then
395 R := Expr_Value (Left_Opnd);
397 -- Neither operand is a constant, do the multiply with no optimization
400 return Make_Op_Multiply (Loc, Left_Opnd, Right_Opnd);
403 -- Case of left operand is an multiplication
405 if Nkind (L) = N_Op_Multiply then
407 -- (C1 * E) * C2 = (C1 * C2) + E
409 if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
411 (Sinfo.Left_Opnd (L),
412 Expr_Value (Sinfo.Left_Opnd (L)) * R);
415 -- (E * C1) * C2 = E * (C1 * C2)
417 elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L)) then
419 (Sinfo.Right_Opnd (L),
420 Expr_Value (Sinfo.Right_Opnd (L)) * R);
425 -- Not optimizable, do the multiplication
427 return Make_Op_Multiply (Loc, Left_Opnd, Right_Opnd);
434 function Assoc_Subtract
437 Right_Opnd : Node_Id) return Node_Id
443 -- Case of right operand is a constant
445 if Compile_Time_Known_Value (Right_Opnd) then
447 R := Expr_Value (Right_Opnd);
449 -- Right operand is a constant, do the subtract with no optimization
452 return Make_Op_Subtract (Loc, Left_Opnd, Right_Opnd);
455 -- Case of left operand is an addition
457 if Nkind (L) = N_Op_Add then
459 -- (C1 + E) - C2 = (C1 - C2) + E
461 if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
463 (Sinfo.Left_Opnd (L),
464 Expr_Value (Sinfo.Left_Opnd (L)) - R);
467 -- (E + C1) - C2 = E + (C1 - C2)
469 elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L)) then
471 (Sinfo.Right_Opnd (L),
472 Expr_Value (Sinfo.Right_Opnd (L)) - R);
476 -- Case of left operand is a subtraction
478 elsif Nkind (L) = N_Op_Subtract then
480 -- (C1 - E) - C2 = (C1 - C2) + E
482 if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
484 (Sinfo.Left_Opnd (L),
485 Expr_Value (Sinfo.Left_Opnd (L)) + R);
488 -- (E - C1) - C2 = E - (C1 + C2)
490 elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L)) then
492 (Sinfo.Right_Opnd (L),
493 Expr_Value (Sinfo.Right_Opnd (L)) + R);
498 -- Not optimizable, do the subtraction
500 return Make_Op_Subtract (Loc, Left_Opnd, Right_Opnd);
507 function Bits_To_SU (N : Node_Id) return Node_Id is
509 if Nkind (N) = N_Integer_Literal then
510 Set_Intval (N, (Intval (N) + (SSU - 1)) / SSU);
520 function Compute_Length (Lo : Node_Id; Hi : Node_Id) return Node_Id is
521 Loc : constant Source_Ptr := Sloc (Lo);
522 Typ : constant Entity_Id := Etype (Lo);
529 -- If the bounds are First and Last attributes for the same dimension
530 -- and both have prefixes that denotes the same entity, then we create
531 -- and return a Length attribute. This may allow the back end to
532 -- generate better code in cases where it already has the length.
534 if Nkind (Lo) = N_Attribute_Reference
535 and then Attribute_Name (Lo) = Name_First
536 and then Nkind (Hi) = N_Attribute_Reference
537 and then Attribute_Name (Hi) = Name_Last
538 and then Is_Entity_Name (Prefix (Lo))
539 and then Is_Entity_Name (Prefix (Hi))
540 and then Entity (Prefix (Lo)) = Entity (Prefix (Hi))
545 if Present (First (Expressions (Lo))) then
546 Lo_Dim := Expr_Value (First (Expressions (Lo)));
549 if Present (First (Expressions (Hi))) then
550 Hi_Dim := Expr_Value (First (Expressions (Hi)));
553 if Lo_Dim = Hi_Dim then
555 Make_Attribute_Reference (Loc,
556 Prefix => New_Occurrence_Of
557 (Entity (Prefix (Lo)), Loc),
558 Attribute_Name => Name_Length,
559 Expressions => New_List
560 (Make_Integer_Literal (Loc, Lo_Dim)));
564 Lo_Op := New_Copy_Tree (Lo);
565 Hi_Op := New_Copy_Tree (Hi);
567 -- If type is enumeration type, then use Pos attribute to convert
568 -- to integer type for which subtraction is a permitted operation.
570 if Is_Enumeration_Type (Typ) then
572 Make_Attribute_Reference (Loc,
573 Prefix => New_Occurrence_Of (Typ, Loc),
574 Attribute_Name => Name_Pos,
575 Expressions => New_List (Lo_Op));
578 Make_Attribute_Reference (Loc,
579 Prefix => New_Occurrence_Of (Typ, Loc),
580 Attribute_Name => Name_Pos,
581 Expressions => New_List (Hi_Op));
589 Right_Opnd => Lo_Op),
590 Right_Opnd => Make_Integer_Literal (Loc, 1));
593 ----------------------
594 -- Expr_From_SO_Ref --
595 ----------------------
597 function Expr_From_SO_Ref
600 Comp : Entity_Id := Empty) return Node_Id
605 if Is_Dynamic_SO_Ref (D) then
606 Ent := Get_Dynamic_SO_Entity (D);
608 if Is_Discrim_SO_Function (Ent) then
610 -- If a component is passed in whose type matches the type of
611 -- the function formal, then select that component from the "V"
612 -- parameter rather than passing "V" directly.
615 and then Base_Type (Etype (Comp))
616 = Base_Type (Etype (First_Formal (Ent)))
619 Make_Function_Call (Loc,
620 Name => New_Occurrence_Of (Ent, Loc),
621 Parameter_Associations => New_List (
622 Make_Selected_Component (Loc,
623 Prefix => Make_Identifier (Loc, Chars => Vname),
624 Selector_Name => New_Occurrence_Of (Comp, Loc))));
628 Make_Function_Call (Loc,
629 Name => New_Occurrence_Of (Ent, Loc),
630 Parameter_Associations => New_List (
631 Make_Identifier (Loc, Chars => Vname)));
635 return New_Occurrence_Of (Ent, Loc);
639 return Make_Integer_Literal (Loc, D);
641 end Expr_From_SO_Ref;
643 ---------------------
644 -- Get_Max_SU_Size --
645 ---------------------
647 function Get_Max_SU_Size (E : Entity_Id) return Node_Id is
648 Loc : constant Source_Ptr := Sloc (E);
656 type Val_Status_Type is (Const, Dynamic);
658 type Val_Type (Status : Val_Status_Type := Const) is
661 when Const => Val : Uint;
662 when Dynamic => Nod : Node_Id;
665 -- Shows the status of the value so far. Const means that the value is
666 -- constant, and Val is the current constant value. Dynamic means that
667 -- the value is dynamic, and in this case Nod is the Node_Id of the
668 -- expression to compute the value.
671 -- Calculated value so far if Size.Status = Const,
672 -- or expression value so far if Size.Status = Dynamic.
674 SU_Convert_Required : Boolean := False;
675 -- This is set to True if the final result must be converted from bits
676 -- to storage units (rounding up to a storage unit boundary).
678 -----------------------
679 -- Local Subprograms --
680 -----------------------
682 procedure Max_Discrim (N : in out Node_Id);
683 -- If the node N represents a discriminant, replace it by the maximum
684 -- value of the discriminant.
686 procedure Min_Discrim (N : in out Node_Id);
687 -- If the node N represents a discriminant, replace it by the minimum
688 -- value of the discriminant.
694 procedure Max_Discrim (N : in out Node_Id) is
696 if Nkind (N) = N_Identifier
697 and then Ekind (Entity (N)) = E_Discriminant
699 N := Type_High_Bound (Etype (N));
707 procedure Min_Discrim (N : in out Node_Id) is
709 if Nkind (N) = N_Identifier
710 and then Ekind (Entity (N)) = E_Discriminant
712 N := Type_Low_Bound (Etype (N));
716 -- Start of processing for Get_Max_SU_Size
719 pragma Assert (Size_Depends_On_Discriminant (E));
721 -- Initialize status from component size
723 if Known_Static_Component_Size (E) then
724 Size := (Const, Component_Size (E));
727 Size := (Dynamic, Expr_From_SO_Ref (Loc, Component_Size (E)));
730 -- Loop through indices
732 Indx := First_Index (E);
733 while Present (Indx) loop
734 Ityp := Etype (Indx);
735 Lo := Type_Low_Bound (Ityp);
736 Hi := Type_High_Bound (Ityp);
741 -- Value of the current subscript range is statically known
743 if Compile_Time_Known_Value (Lo)
744 and then Compile_Time_Known_Value (Hi)
746 S := Expr_Value (Hi) - Expr_Value (Lo) + 1;
748 -- If known flat bound, entire size of array is zero!
751 return Make_Integer_Literal (Loc, 0);
754 -- Current value is constant, evolve value
756 if Size.Status = Const then
757 Size.Val := Size.Val * S;
759 -- Current value is dynamic
762 -- An interesting little optimization, if we have a pending
763 -- conversion from bits to storage units, and the current
764 -- length is a multiple of the storage unit size, then we
765 -- can take the factor out here statically, avoiding some
766 -- extra dynamic computations at the end.
768 if SU_Convert_Required and then S mod SSU = 0 then
770 SU_Convert_Required := False;
775 Left_Opnd => Size.Nod,
777 Make_Integer_Literal (Loc, Intval => S));
780 -- Value of the current subscript range is dynamic
783 -- If the current size value is constant, then here is where we
784 -- make a transition to dynamic values, which are always stored
785 -- in storage units, However, we do not want to convert to SU's
786 -- too soon, consider the case of a packed array of single bits,
787 -- we want to do the SU conversion after computing the size in
790 if Size.Status = Const then
792 -- If the current value is a multiple of the storage unit,
793 -- then most certainly we can do the conversion now, simply
794 -- by dividing the current value by the storage unit value.
795 -- If this works, we set SU_Convert_Required to False.
797 if Size.Val mod SSU = 0 then
800 (Dynamic, Make_Integer_Literal (Loc, Size.Val / SSU));
801 SU_Convert_Required := False;
803 -- Otherwise, we go ahead and convert the value in bits, and
804 -- set SU_Convert_Required to True to ensure that the final
805 -- value is indeed properly converted.
808 Size := (Dynamic, Make_Integer_Literal (Loc, Size.Val));
809 SU_Convert_Required := True;
815 Len := Compute_Length (Lo, Hi);
817 -- Check possible range of Len
823 pragma Warnings (Off, LHi);
827 Determine_Range (Len, OK, LLo, LHi);
829 Len := Convert_To (Standard_Unsigned, Len);
831 -- If we cannot verify that range cannot be super-flat, we need
832 -- a max with zero, since length must be non-negative.
834 if not OK or else LLo < 0 then
836 Make_Attribute_Reference (Loc,
838 New_Occurrence_Of (Standard_Unsigned, Loc),
839 Attribute_Name => Name_Max,
840 Expressions => New_List (
841 Make_Integer_Literal (Loc, 0),
850 -- Here after processing all bounds to set sizes. If the value is a
851 -- constant, then it is bits, so we convert to storage units.
853 if Size.Status = Const then
854 return Bits_To_SU (Make_Integer_Literal (Loc, Size.Val));
856 -- Case where the value is dynamic
859 -- Do convert from bits to SU's if needed
861 if SU_Convert_Required then
863 -- The expression required is (Size.Nod + SU - 1) / SU
869 Left_Opnd => Size.Nod,
870 Right_Opnd => Make_Integer_Literal (Loc, SSU - 1)),
871 Right_Opnd => Make_Integer_Literal (Loc, SSU));
878 -----------------------
879 -- Layout_Array_Type --
880 -----------------------
882 procedure Layout_Array_Type (E : Entity_Id) is
883 Loc : constant Source_Ptr := Sloc (E);
884 Ctyp : constant Entity_Id := Component_Type (E);
892 Insert_Typ : Entity_Id;
893 -- This is the type with which any generated constants or functions
894 -- will be associated (i.e. inserted into the freeze actions). This
895 -- is normally the type being laid out. The exception occurs when
896 -- we are laying out Itype's which are local to a record type, and
897 -- whose scope is this record type. Such types do not have freeze
898 -- nodes (because we have no place to put them).
900 ------------------------------------
901 -- How An Array Type is Laid Out --
902 ------------------------------------
904 -- Here is what goes on. We need to multiply the component size of the
905 -- array (which has already been set) by the length of each of the
906 -- indexes. If all these values are known at compile time, then the
907 -- resulting size of the array is the appropriate constant value.
909 -- If the component size or at least one bound is dynamic (but no
910 -- discriminants are present), then the size will be computed as an
911 -- expression that calculates the proper size.
913 -- If there is at least one discriminant bound, then the size is also
914 -- computed as an expression, but this expression contains discriminant
915 -- values which are obtained by selecting from a function parameter, and
916 -- the size is given by a function that is passed the variant record in
917 -- question, and whose body is the expression.
919 type Val_Status_Type is (Const, Dynamic, Discrim);
921 type Val_Type (Status : Val_Status_Type := Const) is
926 -- Calculated value so far if Val_Status = Const
928 when Dynamic | Discrim =>
930 -- Expression value so far if Val_Status /= Const
934 -- Records the value or expression computed so far. Const means that
935 -- the value is constant, and Val is the current constant value.
936 -- Dynamic means that the value is dynamic, and in this case Nod is
937 -- the Node_Id of the expression to compute the value, and Discrim
938 -- means that at least one bound is a discriminant, in which case Nod
939 -- is the expression so far (which will be the body of the function).
942 -- Value of size computed so far. See comments above
944 Vtyp : Entity_Id := Empty;
945 -- Variant record type for the formal parameter of the discriminant
946 -- function V if Status = Discrim.
948 SU_Convert_Required : Boolean := False;
949 -- This is set to True if the final result must be converted from
950 -- bits to storage units (rounding up to a storage unit boundary).
952 Storage_Divisor : Uint := UI_From_Int (SSU);
953 -- This is the amount that a nonstatic computed size will be divided
954 -- by to convert it from bits to storage units. This is normally
955 -- equal to SSU, but can be reduced in the case of packed components
956 -- that fit evenly into a storage unit.
958 Make_Size_Function : Boolean := False;
959 -- Indicates whether to request that SO_Ref_From_Expr should
960 -- encapsulate the array size expression in a function.
962 procedure Discrimify (N : in out Node_Id);
963 -- If N represents a discriminant, then the Size.Status is set to
964 -- Discrim, and Vtyp is set. The parameter N is replaced with the
965 -- proper expression to extract the discriminant value from V.
971 procedure Discrimify (N : in out Node_Id) is
976 if Nkind (N) = N_Identifier
977 and then Ekind (Entity (N)) = E_Discriminant
979 Set_Size_Depends_On_Discriminant (E);
981 if Size.Status /= Discrim then
982 Decl := Parent (Parent (Entity (N)));
983 Size := (Discrim, Size.Nod);
984 Vtyp := Defining_Identifier (Decl);
990 Make_Selected_Component (Loc,
991 Prefix => Make_Identifier (Loc, Chars => Vname),
992 Selector_Name => New_Occurrence_Of (Entity (N), Loc));
994 -- Set the Etype attributes of the selected name and its prefix.
995 -- Analyze_And_Resolve can't be called here because the Vname
996 -- entity denoted by the prefix will not yet exist (it's created
997 -- by SO_Ref_From_Expr, called at the end of Layout_Array_Type).
999 Set_Etype (Prefix (N), Vtyp);
1004 -- Start of processing for Layout_Array_Type
1007 -- Default alignment is component alignment
1009 if Unknown_Alignment (E) then
1010 Set_Alignment (E, Alignment (Ctyp));
1013 -- Calculate proper type for insertions
1015 if Is_Record_Type (Underlying_Type (Scope (E))) then
1016 Insert_Typ := Underlying_Type (Scope (E));
1021 -- If the component type is a generic formal type then there's no point
1022 -- in determining a size for the array type.
1024 if Is_Generic_Type (Ctyp) then
1028 -- Deal with component size if base type
1030 if Ekind (E) = E_Array_Type then
1032 -- Cannot do anything if Esize of component type unknown
1034 if Unknown_Esize (Ctyp) then
1038 -- Set component size if not set already
1040 if Unknown_Component_Size (E) then
1041 Set_Component_Size (E, Esize (Ctyp));
1045 -- (RM 13.3 (48)) says that the size of an unconstrained array
1046 -- is implementation defined. We choose to leave it as Unknown
1047 -- here, and the actual behavior is determined by the back end.
1049 if not Is_Constrained (E) then
1053 -- Initialize status from component size
1055 if Known_Static_Component_Size (E) then
1056 Size := (Const, Component_Size (E));
1059 Size := (Dynamic, Expr_From_SO_Ref (Loc, Component_Size (E)));
1062 -- Loop to process array indices
1064 Indx := First_Index (E);
1065 while Present (Indx) loop
1066 Ityp := Etype (Indx);
1068 -- If an index of the array is a generic formal type then there is
1069 -- no point in determining a size for the array type.
1071 if Is_Generic_Type (Ityp) then
1075 Lo := Type_Low_Bound (Ityp);
1076 Hi := Type_High_Bound (Ityp);
1078 -- Value of the current subscript range is statically known
1080 if Compile_Time_Known_Value (Lo)
1081 and then Compile_Time_Known_Value (Hi)
1083 S := Expr_Value (Hi) - Expr_Value (Lo) + 1;
1085 -- If known flat bound, entire size of array is zero!
1088 Set_Esize (E, Uint_0);
1089 Set_RM_Size (E, Uint_0);
1093 -- If constant, evolve value
1095 if Size.Status = Const then
1096 Size.Val := Size.Val * S;
1098 -- Current value is dynamic
1101 -- An interesting little optimization, if we have a pending
1102 -- conversion from bits to storage units, and the current
1103 -- length is a multiple of the storage unit size, then we
1104 -- can take the factor out here statically, avoiding some
1105 -- extra dynamic computations at the end.
1107 if SU_Convert_Required and then S mod SSU = 0 then
1109 SU_Convert_Required := False;
1112 -- Now go ahead and evolve the expression
1115 Assoc_Multiply (Loc,
1116 Left_Opnd => Size.Nod,
1118 Make_Integer_Literal (Loc, Intval => S));
1121 -- Value of the current subscript range is dynamic
1124 -- If the current size value is constant, then here is where we
1125 -- make a transition to dynamic values, which are always stored
1126 -- in storage units, However, we do not want to convert to SU's
1127 -- too soon, consider the case of a packed array of single bits,
1128 -- we want to do the SU conversion after computing the size in
1131 if Size.Status = Const then
1133 -- If the current value is a multiple of the storage unit,
1134 -- then most certainly we can do the conversion now, simply
1135 -- by dividing the current value by the storage unit value.
1136 -- If this works, we set SU_Convert_Required to False.
1138 if Size.Val mod SSU = 0 then
1140 (Dynamic, Make_Integer_Literal (Loc, Size.Val / SSU));
1141 SU_Convert_Required := False;
1143 -- If the current value is a factor of the storage unit, then
1144 -- we can use a value of one for the size and reduce the
1145 -- strength of the later division.
1147 elsif SSU mod Size.Val = 0 then
1148 Storage_Divisor := SSU / Size.Val;
1149 Size := (Dynamic, Make_Integer_Literal (Loc, Uint_1));
1150 SU_Convert_Required := True;
1152 -- Otherwise, we go ahead and convert the value in bits, and
1153 -- set SU_Convert_Required to True to ensure that the final
1154 -- value is indeed properly converted.
1157 Size := (Dynamic, Make_Integer_Literal (Loc, Size.Val));
1158 SU_Convert_Required := True;
1165 -- Length is hi-lo+1
1167 Len := Compute_Length (Lo, Hi);
1169 -- If Len isn't a Length attribute, then its range needs to be
1170 -- checked a possible Max with zero needs to be computed.
1172 if Nkind (Len) /= N_Attribute_Reference
1173 or else Attribute_Name (Len) /= Name_Length
1181 -- Check possible range of Len
1183 Set_Parent (Len, E);
1184 Determine_Range (Len, OK, LLo, LHi);
1186 Len := Convert_To (Standard_Unsigned, Len);
1188 -- If range definitely flat or superflat,
1189 -- result size is zero
1191 if OK and then LHi <= 0 then
1192 Set_Esize (E, Uint_0);
1193 Set_RM_Size (E, Uint_0);
1197 -- If we cannot verify that range cannot be super-flat, we
1198 -- need a max with zero, since length cannot be negative.
1200 if not OK or else LLo < 0 then
1202 Make_Attribute_Reference (Loc,
1204 New_Occurrence_Of (Standard_Unsigned, Loc),
1205 Attribute_Name => Name_Max,
1206 Expressions => New_List (
1207 Make_Integer_Literal (Loc, 0),
1213 -- At this stage, Len has the expression for the length
1216 Assoc_Multiply (Loc,
1217 Left_Opnd => Size.Nod,
1224 -- Here after processing all bounds to set sizes. If the value is a
1225 -- constant, then it is bits, and the only thing we need to do is to
1226 -- check against explicit given size and do alignment adjust.
1228 if Size.Status = Const then
1229 Set_And_Check_Static_Size (E, Size.Val, Size.Val);
1230 Adjust_Esize_Alignment (E);
1232 -- Case where the value is dynamic
1235 -- Do convert from bits to SU's if needed
1237 if SU_Convert_Required then
1239 -- The expression required is:
1240 -- (Size.Nod + Storage_Divisor - 1) / Storage_Divisor
1243 Make_Op_Divide (Loc,
1246 Left_Opnd => Size.Nod,
1247 Right_Opnd => Make_Integer_Literal
1248 (Loc, Storage_Divisor - 1)),
1249 Right_Opnd => Make_Integer_Literal (Loc, Storage_Divisor));
1252 -- If the array entity is not declared at the library level and its
1253 -- not nested within a subprogram that is marked for inlining, then
1254 -- we request that the size expression be encapsulated in a function.
1255 -- Since this expression is not needed in most cases, we prefer not
1256 -- to incur the overhead of the computation on calls to the enclosing
1257 -- subprogram except for subprograms that require the size.
1259 if not Is_Library_Level_Entity (E) then
1260 Make_Size_Function := True;
1263 Parent_Subp : Entity_Id := Enclosing_Subprogram (E);
1266 while Present (Parent_Subp) loop
1267 if Is_Inlined (Parent_Subp) then
1268 Make_Size_Function := False;
1272 Parent_Subp := Enclosing_Subprogram (Parent_Subp);
1277 -- Now set the dynamic size (the Value_Size is always the same
1278 -- as the Object_Size for arrays whose length is dynamic).
1280 -- ??? If Size.Status = Dynamic, Vtyp will not have been set.
1281 -- The added initialization sets it to Empty now, but is this
1287 (Size.Nod, Insert_Typ, Vtyp, Make_Func => Make_Size_Function));
1288 Set_RM_Size (E, Esize (E));
1290 end Layout_Array_Type;
1296 procedure Layout_Object (E : Entity_Id) is
1297 T : constant Entity_Id := Etype (E);
1300 -- Nothing to do if backend does layout
1302 if not Frontend_Layout_On_Target then
1306 -- Set size if not set for object and known for type. Use the RM_Size if
1307 -- that is known for the type and Esize is not.
1309 if Unknown_Esize (E) then
1310 if Known_Esize (T) then
1311 Set_Esize (E, Esize (T));
1313 elsif Known_RM_Size (T) then
1314 Set_Esize (E, RM_Size (T));
1318 -- Set alignment from type if unknown and type alignment known
1320 if Unknown_Alignment (E) and then Known_Alignment (T) then
1321 Set_Alignment (E, Alignment (T));
1324 -- Make sure size and alignment are consistent
1326 Adjust_Esize_Alignment (E);
1328 -- Final adjustment, if we don't know the alignment, and the Esize was
1329 -- not set by an explicit Object_Size attribute clause, then we reset
1330 -- the Esize to unknown, since we really don't know it.
1332 if Unknown_Alignment (E)
1333 and then not Has_Size_Clause (E)
1335 Set_Esize (E, Uint_0);
1339 ------------------------
1340 -- Layout_Record_Type --
1341 ------------------------
1343 procedure Layout_Record_Type (E : Entity_Id) is
1344 Loc : constant Source_Ptr := Sloc (E);
1348 -- Current component being laid out
1350 Prev_Comp : Entity_Id;
1351 -- Previous laid out component
1353 procedure Get_Next_Component_Location
1354 (Prev_Comp : Entity_Id;
1356 New_Npos : out SO_Ref;
1357 New_Fbit : out SO_Ref;
1358 New_NPMax : out SO_Ref;
1359 Force_SU : Boolean);
1360 -- Given the previous component in Prev_Comp, which is already laid
1361 -- out, and the alignment of the following component, lays out the
1362 -- following component, and returns its starting position in New_Npos
1363 -- (Normalized_Position value), New_Fbit (Normalized_First_Bit value),
1364 -- and New_NPMax (Normalized_Position_Max value). If Prev_Comp is empty
1365 -- (no previous component is present), then New_Npos, New_Fbit and
1366 -- New_NPMax are all set to zero on return. This procedure is also
1367 -- used to compute the size of a record or variant by giving it the
1368 -- last component, and the record alignment. Force_SU is used to force
1369 -- the new component location to be aligned on a storage unit boundary,
1370 -- even in a packed record, False means that the new position does not
1371 -- need to be bumped to a storage unit boundary, True means a storage
1372 -- unit boundary is always required.
1374 procedure Layout_Component (Comp : Entity_Id; Prev_Comp : Entity_Id);
1375 -- Lays out component Comp, given Prev_Comp, the previously laid-out
1376 -- component (Prev_Comp = Empty if no components laid out yet). The
1377 -- alignment of the record itself is also updated if needed. Both
1378 -- Comp and Prev_Comp can be either components or discriminants.
1380 procedure Layout_Components
1384 RM_Siz : out SO_Ref);
1385 -- This procedure lays out the components of the given component list
1386 -- which contains the components starting with From and ending with To.
1387 -- The Next_Entity chain is used to traverse the components. On entry,
1388 -- Prev_Comp is set to the component preceding the list, so that the
1389 -- list is laid out after this component. Prev_Comp is set to Empty if
1390 -- the component list is to be laid out starting at the start of the
1391 -- record. On return, the components are all laid out, and Prev_Comp is
1392 -- set to the last laid out component. On return, Esiz is set to the
1393 -- resulting Object_Size value, which is the length of the record up
1394 -- to and including the last laid out entity. For Esiz, the value is
1395 -- adjusted to match the alignment of the record. RM_Siz is similarly
1396 -- set to the resulting Value_Size value, which is the same length, but
1397 -- not adjusted to meet the alignment. Note that in the case of variant
1398 -- records, Esiz represents the maximum size.
1400 procedure Layout_Non_Variant_Record;
1401 -- Procedure called to lay out a non-variant record type or subtype
1403 procedure Layout_Variant_Record;
1404 -- Procedure called to lay out a variant record type. Decl is set to the
1405 -- full type declaration for the variant record.
1407 ---------------------------------
1408 -- Get_Next_Component_Location --
1409 ---------------------------------
1411 procedure Get_Next_Component_Location
1412 (Prev_Comp : Entity_Id;
1414 New_Npos : out SO_Ref;
1415 New_Fbit : out SO_Ref;
1416 New_NPMax : out SO_Ref;
1420 -- No previous component, return zero position
1422 if No (Prev_Comp) then
1425 New_NPMax := Uint_0;
1429 -- Here we have a previous component
1432 Loc : constant Source_Ptr := Sloc (Prev_Comp);
1434 Old_Npos : constant SO_Ref := Normalized_Position (Prev_Comp);
1435 Old_Fbit : constant SO_Ref := Normalized_First_Bit (Prev_Comp);
1436 Old_NPMax : constant SO_Ref := Normalized_Position_Max (Prev_Comp);
1437 Old_Esiz : constant SO_Ref := Esize (Prev_Comp);
1439 Old_Maxsz : Node_Id;
1440 -- Expression representing maximum size of previous component
1443 -- Case where previous field had a dynamic size
1445 if Is_Dynamic_SO_Ref (Esize (Prev_Comp)) then
1447 -- If the previous field had a dynamic length, then it is
1448 -- required to occupy an integral number of storage units,
1449 -- and start on a storage unit boundary. This means that
1450 -- the Normalized_First_Bit value is zero in the previous
1451 -- component, and the new value is also set to zero.
1455 -- In this case, the new position is given by an expression
1456 -- that is the sum of old normalized position and old size.
1462 Expr_From_SO_Ref (Loc, Old_Npos),
1464 Expr_From_SO_Ref (Loc, Old_Esiz, Prev_Comp)),
1468 -- Get maximum size of previous component
1470 if Size_Depends_On_Discriminant (Etype (Prev_Comp)) then
1471 Old_Maxsz := Get_Max_SU_Size (Etype (Prev_Comp));
1473 Old_Maxsz := Expr_From_SO_Ref (Loc, Old_Esiz, Prev_Comp);
1476 -- Now we can compute the new max position. If the max size
1477 -- is static and the old position is static, then we can
1478 -- compute the new position statically.
1480 if Nkind (Old_Maxsz) = N_Integer_Literal
1481 and then Known_Static_Normalized_Position_Max (Prev_Comp)
1483 New_NPMax := Old_NPMax + Intval (Old_Maxsz);
1485 -- Otherwise new max position is dynamic
1491 Left_Opnd => Expr_From_SO_Ref (Loc, Old_NPMax),
1492 Right_Opnd => Old_Maxsz),
1497 -- Previous field has known static Esize
1500 New_Fbit := Old_Fbit + Old_Esiz;
1502 -- Bump New_Fbit to storage unit boundary if required
1504 if New_Fbit /= 0 and then Force_SU then
1505 New_Fbit := (New_Fbit + SSU - 1) / SSU * SSU;
1508 -- If old normalized position is static, we can go ahead and
1509 -- compute the new normalized position directly.
1511 if Known_Static_Normalized_Position (Prev_Comp) then
1512 New_Npos := Old_Npos;
1514 if New_Fbit >= SSU then
1515 New_Npos := New_Npos + New_Fbit / SSU;
1516 New_Fbit := New_Fbit mod SSU;
1519 -- Bump alignment if stricter than prev
1521 if Align > Alignment (Etype (Prev_Comp)) then
1522 New_Npos := (New_Npos + Align - 1) / Align * Align;
1525 -- The max position is always equal to the position if
1526 -- the latter is static, since arrays depending on the
1527 -- values of discriminants never have static sizes.
1529 New_NPMax := New_Npos;
1532 -- Case of old normalized position is dynamic
1535 -- If new bit position is within the current storage unit,
1536 -- we can just copy the old position as the result position
1537 -- (we have already set the new first bit value).
1539 if New_Fbit < SSU then
1540 New_Npos := Old_Npos;
1541 New_NPMax := Old_NPMax;
1543 -- If new bit position is past the current storage unit, we
1544 -- need to generate a new dynamic value for the position
1545 -- ??? need to deal with alignment
1551 Left_Opnd => Expr_From_SO_Ref (Loc, Old_Npos),
1553 Make_Integer_Literal (Loc,
1554 Intval => New_Fbit / SSU)),
1561 Left_Opnd => Expr_From_SO_Ref (Loc, Old_NPMax),
1563 Make_Integer_Literal (Loc,
1564 Intval => New_Fbit / SSU)),
1567 New_Fbit := New_Fbit mod SSU;
1572 end Get_Next_Component_Location;
1574 ----------------------
1575 -- Layout_Component --
1576 ----------------------
1578 procedure Layout_Component (Comp : Entity_Id; Prev_Comp : Entity_Id) is
1579 Ctyp : constant Entity_Id := Etype (Comp);
1580 ORC : constant Entity_Id := Original_Record_Component (Comp);
1587 -- Increase alignment of record if necessary. Note that we do not
1588 -- do this for packed records, which have an alignment of one by
1589 -- default, or for records for which an explicit alignment was
1590 -- specified with an alignment clause.
1592 if not Is_Packed (E)
1593 and then not Has_Alignment_Clause (E)
1594 and then Alignment (Ctyp) > Alignment (E)
1596 Set_Alignment (E, Alignment (Ctyp));
1599 -- If original component set, then use same layout
1601 if Present (ORC) and then ORC /= Comp then
1602 Set_Normalized_Position (Comp, Normalized_Position (ORC));
1603 Set_Normalized_First_Bit (Comp, Normalized_First_Bit (ORC));
1604 Set_Normalized_Position_Max (Comp, Normalized_Position_Max (ORC));
1605 Set_Component_Bit_Offset (Comp, Component_Bit_Offset (ORC));
1606 Set_Esize (Comp, Esize (ORC));
1610 -- Parent field is always at start of record, this will overlap
1611 -- the actual fields that are part of the parent, and that's fine
1613 if Chars (Comp) = Name_uParent then
1614 Set_Normalized_Position (Comp, Uint_0);
1615 Set_Normalized_First_Bit (Comp, Uint_0);
1616 Set_Normalized_Position_Max (Comp, Uint_0);
1617 Set_Component_Bit_Offset (Comp, Uint_0);
1618 Set_Esize (Comp, Esize (Ctyp));
1622 -- Check case of type of component has a scope of the record we are
1623 -- laying out. When this happens, the type in question is an Itype
1624 -- that has not yet been laid out (that's because such types do not
1625 -- get frozen in the normal manner, because there is no place for
1626 -- the freeze nodes).
1628 if Scope (Ctyp) = E then
1632 -- If component already laid out, then we are done
1634 if Known_Normalized_Position (Comp) then
1638 -- Set size of component from type. We use the Esize except in a
1639 -- packed record, where we use the RM_Size (since that is what the
1640 -- RM_Size value, as distinct from the Object_Size is useful for!)
1642 if Is_Packed (E) then
1643 Set_Esize (Comp, RM_Size (Ctyp));
1645 Set_Esize (Comp, Esize (Ctyp));
1648 -- Compute the component position from the previous one. See if
1649 -- current component requires being on a storage unit boundary.
1651 -- If record is not packed, we always go to a storage unit boundary
1653 if not Is_Packed (E) then
1659 -- Elementary types do not need SU boundary in packed record
1661 if Is_Elementary_Type (Ctyp) then
1664 -- Packed array types with a modular packed array type do not
1665 -- force a storage unit boundary (since the code generation
1666 -- treats these as equivalent to the underlying modular type),
1668 elsif Is_Array_Type (Ctyp)
1669 and then Is_Bit_Packed_Array (Ctyp)
1670 and then Is_Modular_Integer_Type (Packed_Array_Type (Ctyp))
1674 -- Record types with known length less than or equal to the length
1675 -- of long long integer can also be unaligned, since they can be
1676 -- treated as scalars.
1678 elsif Is_Record_Type (Ctyp)
1679 and then not Is_Dynamic_SO_Ref (Esize (Ctyp))
1680 and then Esize (Ctyp) <= Esize (Standard_Long_Long_Integer)
1684 -- All other cases force a storage unit boundary, even when packed
1691 -- Now get the next component location
1693 Get_Next_Component_Location
1694 (Prev_Comp, Alignment (Ctyp), Npos, Fbit, NPMax, Forc);
1695 Set_Normalized_Position (Comp, Npos);
1696 Set_Normalized_First_Bit (Comp, Fbit);
1697 Set_Normalized_Position_Max (Comp, NPMax);
1699 -- Set Component_Bit_Offset in the static case
1701 if Known_Static_Normalized_Position (Comp)
1702 and then Known_Normalized_First_Bit (Comp)
1704 Set_Component_Bit_Offset (Comp, SSU * Npos + Fbit);
1706 end Layout_Component;
1708 -----------------------
1709 -- Layout_Components --
1710 -----------------------
1712 procedure Layout_Components
1716 RM_Siz : out SO_Ref)
1723 -- Only lay out components if there are some to lay out!
1725 if Present (From) then
1727 -- Lay out components with no component clauses
1731 if Ekind (Comp) = E_Component
1732 or else Ekind (Comp) = E_Discriminant
1734 -- The compatibility of component clauses with composite
1735 -- types isn't checked in Sem_Ch13, so we check it here.
1737 if Present (Component_Clause (Comp)) then
1738 if Is_Composite_Type (Etype (Comp))
1739 and then Esize (Comp) < RM_Size (Etype (Comp))
1741 Error_Msg_Uint_1 := RM_Size (Etype (Comp));
1743 ("size for & too small, minimum allowed is ^",
1744 Component_Clause (Comp),
1749 Layout_Component (Comp, Prev_Comp);
1754 exit when Comp = To;
1759 -- Set size fields, both are zero if no components
1761 if No (Prev_Comp) then
1765 -- If record subtype with non-static discriminants, then we don't
1766 -- know which variant will be the one which gets chosen. We don't
1767 -- just want to set the maximum size from the base, because the
1768 -- size should depend on the particular variant.
1770 -- What we do is to use the RM_Size of the base type, which has
1771 -- the necessary conditional computation of the size, using the
1772 -- size information for the particular variant chosen. Records
1773 -- with default discriminants for example have an Esize that is
1774 -- set to the maximum of all variants, but that's not what we
1775 -- want for a constrained subtype.
1777 elsif Ekind (E) = E_Record_Subtype
1778 and then not Has_Static_Discriminants (E)
1781 BT : constant Node_Id := Base_Type (E);
1783 Esiz := RM_Size (BT);
1784 RM_Siz := RM_Size (BT);
1785 Set_Alignment (E, Alignment (BT));
1789 -- First the object size, for which we align past the last field
1790 -- to the alignment of the record (the object size is required to
1791 -- be a multiple of the alignment).
1793 Get_Next_Component_Location
1801 -- If the resulting normalized position is a dynamic reference,
1802 -- then the size is dynamic, and is stored in storage units. In
1803 -- this case, we set the RM_Size to the same value, it is simply
1804 -- not worth distinguishing Esize and RM_Size values in the
1805 -- dynamic case, since the RM has nothing to say about them.
1807 -- Note that a size cannot have been given in this case, since
1808 -- size specifications cannot be given for variable length types.
1811 Align : constant Uint := Alignment (E);
1814 if Is_Dynamic_SO_Ref (End_Npos) then
1817 -- Set the Object_Size allowing for the alignment. In the
1818 -- dynamic case, we must do the actual runtime computation.
1819 -- We can skip this in the non-packed record case if the
1820 -- last component has a smaller alignment than the overall
1821 -- record alignment.
1823 if Is_Dynamic_SO_Ref (End_NPMax) then
1827 or else Alignment (Etype (Prev_Comp)) < Align
1829 -- The expression we build is:
1830 -- (expr + align - 1) / align * align
1835 Make_Op_Multiply (Loc,
1837 Make_Op_Divide (Loc,
1841 Expr_From_SO_Ref (Loc, Esiz),
1843 Make_Integer_Literal (Loc,
1844 Intval => Align - 1)),
1846 Make_Integer_Literal (Loc, Align)),
1848 Make_Integer_Literal (Loc, Align)),
1853 -- Here Esiz is static, so we can adjust the alignment
1854 -- directly go give the required aligned value.
1857 Esiz := (End_NPMax + Align - 1) / Align * Align * SSU;
1860 -- Case where computed size is static
1863 -- The ending size was computed in Npos in storage units,
1864 -- but the actual size is stored in bits, so adjust
1865 -- accordingly. We also adjust the size to match the
1868 Esiz := (End_NPMax + Align - 1) / Align * Align * SSU;
1870 -- Compute the resulting Value_Size (RM_Size). For this
1871 -- purpose we do not force alignment of the record or
1872 -- storage size alignment of the result.
1874 Get_Next_Component_Location
1882 RM_Siz := End_Npos * SSU + End_Fbit;
1883 Set_And_Check_Static_Size (E, Esiz, RM_Siz);
1887 end Layout_Components;
1889 -------------------------------
1890 -- Layout_Non_Variant_Record --
1891 -------------------------------
1893 procedure Layout_Non_Variant_Record is
1897 Layout_Components (First_Entity (E), Last_Entity (E), Esiz, RM_Siz);
1898 Set_Esize (E, Esiz);
1899 Set_RM_Size (E, RM_Siz);
1900 end Layout_Non_Variant_Record;
1902 ---------------------------
1903 -- Layout_Variant_Record --
1904 ---------------------------
1906 procedure Layout_Variant_Record is
1907 Tdef : constant Node_Id := Type_Definition (Decl);
1908 First_Discr : Entity_Id;
1909 Last_Discr : Entity_Id;
1913 pragma Warnings (Off, SO_Ref);
1915 RM_Siz_Expr : Node_Id := Empty;
1916 -- Expression for the evolving RM_Siz value. This is typically a
1917 -- conditional expression which involves tests of discriminant values
1918 -- that are formed as references to the entity V. At the end of
1919 -- scanning all the components, a suitable function is constructed
1920 -- in which V is the parameter.
1922 -----------------------
1923 -- Local Subprograms --
1924 -----------------------
1926 procedure Layout_Component_List
1929 RM_Siz_Expr : out Node_Id);
1930 -- Recursive procedure, called to lay out one component list Esiz
1931 -- and RM_Siz_Expr are set to the Object_Size and Value_Size values
1932 -- respectively representing the record size up to and including the
1933 -- last component in the component list (including any variants in
1934 -- this component list). RM_Siz_Expr is returned as an expression
1935 -- which may in the general case involve some references to the
1936 -- discriminants of the current record value, referenced by selecting
1937 -- from the entity V.
1939 ---------------------------
1940 -- Layout_Component_List --
1941 ---------------------------
1943 procedure Layout_Component_List
1946 RM_Siz_Expr : out Node_Id)
1948 Citems : constant List_Id := Component_Items (Clist);
1949 Vpart : constant Node_Id := Variant_Part (Clist);
1953 RMS_Ent : Entity_Id;
1956 if Is_Non_Empty_List (Citems) then
1958 (From => Defining_Identifier (First (Citems)),
1959 To => Defining_Identifier (Last (Citems)),
1963 Layout_Components (Empty, Empty, Esiz, RM_Siz);
1966 -- Case where no variants are present in the component list
1970 -- The Esiz value has been correctly set by the call to
1971 -- Layout_Components, so there is nothing more to be done.
1973 -- For RM_Siz, we have an SO_Ref value, which we must convert
1974 -- to an appropriate expression.
1976 if Is_Static_SO_Ref (RM_Siz) then
1978 Make_Integer_Literal (Loc,
1982 RMS_Ent := Get_Dynamic_SO_Entity (RM_Siz);
1984 -- If the size is represented by a function, then we create
1985 -- an appropriate function call using V as the parameter to
1988 if Is_Discrim_SO_Function (RMS_Ent) then
1990 Make_Function_Call (Loc,
1991 Name => New_Occurrence_Of (RMS_Ent, Loc),
1992 Parameter_Associations => New_List (
1993 Make_Identifier (Loc, Chars => Vname)));
1995 -- If the size is represented by a constant, then the
1996 -- expression we want is a reference to this constant
1999 RM_Siz_Expr := New_Occurrence_Of (RMS_Ent, Loc);
2003 -- Case where variants are present in this component list
2013 D_Entity : Entity_Id;
2016 RM_Siz_Expr := Empty;
2019 Var := Last (Variants (Vpart));
2020 while Present (Var) loop
2022 Layout_Component_List
2023 (Component_List (Var), EsizV, RM_SizV);
2025 -- Set the Object_Size. If this is the first variant,
2026 -- we just set the size of this first variant.
2028 if Var = Last (Variants (Vpart)) then
2031 -- Otherwise the Object_Size is formed as a maximum
2032 -- of Esiz so far from previous variants, and the new
2033 -- Esiz value from the variant we just processed.
2035 -- If both values are static, we can just compute the
2036 -- maximum directly to save building junk nodes.
2038 elsif not Is_Dynamic_SO_Ref (Esiz)
2039 and then not Is_Dynamic_SO_Ref (EsizV)
2041 Esiz := UI_Max (Esiz, EsizV);
2043 -- If either value is dynamic, then we have to generate
2044 -- an appropriate Standard_Unsigned'Max attribute call.
2045 -- If one of the values is static then it needs to be
2046 -- converted from bits to storage units to be compatible
2047 -- with the dynamic value.
2050 if Is_Static_SO_Ref (Esiz) then
2051 Esiz := (Esiz + SSU - 1) / SSU;
2054 if Is_Static_SO_Ref (EsizV) then
2055 EsizV := (EsizV + SSU - 1) / SSU;
2060 (Make_Attribute_Reference (Loc,
2061 Attribute_Name => Name_Max,
2063 New_Occurrence_Of (Standard_Unsigned, Loc),
2064 Expressions => New_List (
2065 Expr_From_SO_Ref (Loc, Esiz),
2066 Expr_From_SO_Ref (Loc, EsizV))),
2071 -- Now deal with Value_Size (RM_Siz). We are aiming at
2072 -- an expression that looks like:
2074 -- if xxDx (V.disc) then rmsiz1
2075 -- else if xxDx (V.disc) then rmsiz2
2078 -- Where rmsiz1, rmsiz2... are the RM_Siz values for the
2079 -- individual variants, and xxDx are the discriminant
2080 -- checking functions generated for the variant type.
2082 -- If this is the first variant, we simply set the result
2083 -- as the expression. Note that this takes care of the
2086 if No (RM_Siz_Expr) then
2087 RM_Siz_Expr := Bits_To_SU (RM_SizV);
2089 -- Otherwise construct the appropriate test
2092 -- The test to be used in general is a call to the
2093 -- discriminant checking function. However, it is
2094 -- definitely worth special casing the very common
2095 -- case where a single value is involved.
2097 Dchoice := First (Discrete_Choices (Var));
2099 if No (Next (Dchoice))
2100 and then Nkind (Dchoice) /= N_Range
2102 -- Discriminant to be tested
2105 Make_Selected_Component (Loc,
2107 Make_Identifier (Loc, Chars => Vname),
2110 (Entity (Name (Vpart)), Loc));
2114 Left_Opnd => Discrim,
2115 Right_Opnd => New_Copy (Dchoice));
2117 -- Generate a call to the discriminant-checking
2118 -- function for the variant. Note that the result
2119 -- has to be complemented since the function returns
2120 -- False when the passed discriminant value matches.
2123 -- The checking function takes all of the type's
2124 -- discriminants as parameters, so a list of all
2125 -- the selected discriminants must be constructed.
2128 D_Entity := First_Discriminant (E);
2129 while Present (D_Entity) loop
2131 Make_Selected_Component (Loc,
2133 Make_Identifier (Loc, Chars => Vname),
2139 D_Entity := Next_Discriminant (D_Entity);
2145 Make_Function_Call (Loc,
2148 (Dcheck_Function (Var), Loc),
2149 Parameter_Associations =>
2154 Make_Conditional_Expression (Loc,
2157 (Dtest, Bits_To_SU (RM_SizV), RM_Siz_Expr));
2164 end Layout_Component_List;
2166 -- Start of processing for Layout_Variant_Record
2169 -- We need the discriminant checking functions, since we generate
2170 -- calls to these functions for the RM_Size expression, so make
2171 -- sure that these functions have been constructed in time.
2173 Build_Discr_Checking_Funcs (Decl);
2175 -- Lay out the discriminants
2177 First_Discr := First_Discriminant (E);
2178 Last_Discr := First_Discr;
2179 while Present (Next_Discriminant (Last_Discr)) loop
2180 Next_Discriminant (Last_Discr);
2184 (From => First_Discr,
2189 -- Lay out the main component list (this will make recursive calls
2190 -- to lay out all component lists nested within variants).
2192 Layout_Component_List (Component_List (Tdef), Esiz, RM_Siz_Expr);
2193 Set_Esize (E, Esiz);
2195 -- If the RM_Size is a literal, set its value
2197 if Nkind (RM_Siz_Expr) = N_Integer_Literal then
2198 Set_RM_Size (E, Intval (RM_Siz_Expr));
2200 -- Otherwise we construct a dynamic SO_Ref
2209 end Layout_Variant_Record;
2211 -- Start of processing for Layout_Record_Type
2214 -- If this is a cloned subtype, just copy the size fields from the
2215 -- original, nothing else needs to be done in this case, since the
2216 -- components themselves are all shared.
2218 if (Ekind (E) = E_Record_Subtype
2220 Ekind (E) = E_Class_Wide_Subtype)
2221 and then Present (Cloned_Subtype (E))
2223 Set_Esize (E, Esize (Cloned_Subtype (E)));
2224 Set_RM_Size (E, RM_Size (Cloned_Subtype (E)));
2225 Set_Alignment (E, Alignment (Cloned_Subtype (E)));
2227 -- Another special case, class-wide types. The RM says that the size
2228 -- of such types is implementation defined (RM 13.3(48)). What we do
2229 -- here is to leave the fields set as unknown values, and the backend
2230 -- determines the actual behavior.
2232 elsif Ekind (E) = E_Class_Wide_Type then
2238 -- Initialize alignment conservatively to 1. This value will be
2239 -- increased as necessary during processing of the record.
2241 if Unknown_Alignment (E) then
2242 Set_Alignment (E, Uint_1);
2245 -- Initialize previous component. This is Empty unless there are
2246 -- components which have already been laid out by component clauses.
2247 -- If there are such components, we start our lay out of the
2248 -- remaining components following the last such component.
2252 Comp := First_Component_Or_Discriminant (E);
2253 while Present (Comp) loop
2254 if Present (Component_Clause (Comp)) then
2257 Component_Bit_Offset (Comp) >
2258 Component_Bit_Offset (Prev_Comp)
2264 Next_Component_Or_Discriminant (Comp);
2267 -- We have two separate circuits, one for non-variant records and
2268 -- one for variant records. For non-variant records, we simply go
2269 -- through the list of components. This handles all the non-variant
2270 -- cases including those cases of subtypes where there is no full
2271 -- type declaration, so the tree cannot be used to drive the layout.
2272 -- For variant records, we have to drive the layout from the tree
2273 -- since we need to understand the variant structure in this case.
2275 if Present (Full_View (E)) then
2276 Decl := Declaration_Node (Full_View (E));
2278 Decl := Declaration_Node (E);
2281 -- Scan all the components
2283 if Nkind (Decl) = N_Full_Type_Declaration
2284 and then Has_Discriminants (E)
2285 and then Nkind (Type_Definition (Decl)) = N_Record_Definition
2286 and then Present (Component_List (Type_Definition (Decl)))
2288 Present (Variant_Part (Component_List (Type_Definition (Decl))))
2290 Layout_Variant_Record;
2292 Layout_Non_Variant_Record;
2295 end Layout_Record_Type;
2301 procedure Layout_Type (E : Entity_Id) is
2302 Desig_Type : Entity_Id;
2305 -- For string literal types, for now, kill the size always, this is
2306 -- because gigi does not like or need the size to be set ???
2308 if Ekind (E) = E_String_Literal_Subtype then
2309 Set_Esize (E, Uint_0);
2310 Set_RM_Size (E, Uint_0);
2314 -- For access types, set size/alignment. This is system address size,
2315 -- except for fat pointers (unconstrained array access types), where the
2316 -- size is two times the address size, to accommodate the two pointers
2317 -- that are required for a fat pointer (data and template). Note that
2318 -- E_Access_Protected_Subprogram_Type is not an access type for this
2319 -- purpose since it is not a pointer but is equivalent to a record. For
2320 -- access subtypes, copy the size from the base type since Gigi
2321 -- represents them the same way.
2323 if Is_Access_Type (E) then
2325 Desig_Type := Underlying_Type (Designated_Type (E));
2327 -- If we only have a limited view of the type, see whether the
2328 -- non-limited view is available.
2330 if From_With_Type (Designated_Type (E))
2331 and then Ekind (Designated_Type (E)) = E_Incomplete_Type
2332 and then Present (Non_Limited_View (Designated_Type (E)))
2334 Desig_Type := Non_Limited_View (Designated_Type (E));
2337 -- If Esize already set (e.g. by a size clause), then nothing further
2340 if Known_Esize (E) then
2343 -- Access to subprogram is a strange beast, and we let the backend
2344 -- figure out what is needed (it may be some kind of fat pointer,
2345 -- including the static link for example.
2347 elsif Is_Access_Protected_Subprogram_Type (E) then
2350 -- For access subtypes, copy the size information from base type
2352 elsif Ekind (E) = E_Access_Subtype then
2353 Set_Size_Info (E, Base_Type (E));
2354 Set_RM_Size (E, RM_Size (Base_Type (E)));
2356 -- For other access types, we use either address size, or, if a fat
2357 -- pointer is used (pointer-to-unconstrained array case), twice the
2358 -- address size to accommodate a fat pointer.
2360 elsif Present (Desig_Type)
2361 and then Is_Array_Type (Desig_Type)
2362 and then not Is_Constrained (Desig_Type)
2363 and then not Has_Completion_In_Body (Desig_Type)
2364 and then not Debug_Flag_6
2366 Init_Size (E, 2 * System_Address_Size);
2368 -- Check for bad convention set
2370 if Warn_On_Export_Import
2372 (Convention (E) = Convention_C
2374 Convention (E) = Convention_CPP)
2377 ("?this access type does not correspond to C pointer", E);
2380 -- If the designated type is a limited view it is unanalyzed. We can
2381 -- examine the declaration itself to determine whether it will need a
2384 elsif Present (Desig_Type)
2385 and then Present (Parent (Desig_Type))
2386 and then Nkind (Parent (Desig_Type)) = N_Full_Type_Declaration
2388 Nkind (Type_Definition (Parent (Desig_Type)))
2389 = N_Unconstrained_Array_Definition
2391 Init_Size (E, 2 * System_Address_Size);
2393 -- When the target is AAMP, access-to-subprogram types are fat
2394 -- pointers consisting of the subprogram address and a static link
2395 -- (with the exception of library-level access types, where a simple
2396 -- subprogram address is used).
2398 elsif AAMP_On_Target
2400 (Ekind (E) = E_Anonymous_Access_Subprogram_Type
2401 or else (Ekind (E) = E_Access_Subprogram_Type
2402 and then Present (Enclosing_Subprogram (E))))
2404 Init_Size (E, 2 * System_Address_Size);
2407 Init_Size (E, System_Address_Size);
2410 -- On VMS, reset size to 32 for convention C access type if no
2411 -- explicit size clause is given and the default size is 64. Really
2412 -- we do not know the size, since depending on options for the VMS
2413 -- compiler, the size of a pointer type can be 32 or 64, but choosing
2414 -- 32 as the default improves compatibility with legacy VMS code.
2416 -- Note: we do not use Has_Size_Clause in the test below, because we
2417 -- want to catch the case of a derived type inheriting a size clause.
2418 -- We want to consider this to be an explicit size clause for this
2419 -- purpose, since it would be weird not to inherit the size in this
2422 -- We do NOT do this if we are in -gnatdm mode on a non-VMS target
2423 -- since in that case we want the normal pointer representation.
2425 if Opt.True_VMS_Target
2426 and then (Convention (E) = Convention_C
2428 Convention (E) = Convention_CPP)
2429 and then No (Get_Attribute_Definition_Clause (E, Attribute_Size))
2430 and then Esize (E) = 64
2435 Set_Elem_Alignment (E);
2437 -- Scalar types: set size and alignment
2439 elsif Is_Scalar_Type (E) then
2441 -- For discrete types, the RM_Size and Esize must be set already,
2442 -- since this is part of the earlier processing and the front end is
2443 -- always required to lay out the sizes of such types (since they are
2444 -- available as static attributes). All we do is to check that this
2445 -- rule is indeed obeyed!
2447 if Is_Discrete_Type (E) then
2449 -- If the RM_Size is not set, then here is where we set it
2451 -- Note: an RM_Size of zero looks like not set here, but this
2452 -- is a rare case, and we can simply reset it without any harm.
2454 if not Known_RM_Size (E) then
2455 Set_Discrete_RM_Size (E);
2458 -- If Esize for a discrete type is not set then set it
2460 if not Known_Esize (E) then
2466 -- If size is big enough, set it and exit
2468 if S >= RM_Size (E) then
2472 -- If the RM_Size is greater than 64 (happens only when
2473 -- strange values are specified by the user, then Esize
2474 -- is simply a copy of RM_Size, it will be further
2475 -- refined later on)
2478 Set_Esize (E, RM_Size (E));
2481 -- Otherwise double possible size and keep trying
2490 -- For non-discrete scalar types, if the RM_Size is not set, then set
2491 -- it now to a copy of the Esize if the Esize is set.
2494 if Known_Esize (E) and then Unknown_RM_Size (E) then
2495 Set_RM_Size (E, Esize (E));
2499 Set_Elem_Alignment (E);
2501 -- Non-elementary (composite) types
2504 -- For packed arrays, take size and alignment values from the packed
2505 -- array type if a packed array type has been created and the fields
2506 -- are not currently set.
2508 if Is_Array_Type (E) and then Present (Packed_Array_Type (E)) then
2510 PAT : constant Entity_Id := Packed_Array_Type (E);
2513 if Unknown_Esize (E) then
2514 Set_Esize (E, Esize (PAT));
2517 if Unknown_RM_Size (E) then
2518 Set_RM_Size (E, RM_Size (PAT));
2521 if Unknown_Alignment (E) then
2522 Set_Alignment (E, Alignment (PAT));
2527 -- If RM_Size is known, set Esize if not known
2529 if Known_RM_Size (E) and then Unknown_Esize (E) then
2531 -- If the alignment is known, we bump the Esize up to the next
2532 -- alignment boundary if it is not already on one.
2534 if Known_Alignment (E) then
2536 A : constant Uint := Alignment_In_Bits (E);
2537 S : constant SO_Ref := RM_Size (E);
2539 Set_Esize (E, (S + A - 1) / A * A);
2543 -- If Esize is set, and RM_Size is not, RM_Size is copied from Esize.
2544 -- At least for now this seems reasonable, and is in any case needed
2545 -- for compatibility with old versions of gigi.
2547 elsif Known_Esize (E) and then Unknown_RM_Size (E) then
2548 Set_RM_Size (E, Esize (E));
2551 -- For array base types, set component size if object size of the
2552 -- component type is known and is a small power of 2 (8, 16, 32, 64),
2553 -- since this is what will always be used.
2555 if Ekind (E) = E_Array_Type
2556 and then Unknown_Component_Size (E)
2559 CT : constant Entity_Id := Component_Type (E);
2562 -- For some reasons, access types can cause trouble, So let's
2563 -- just do this for discrete types ???
2566 and then Is_Discrete_Type (CT)
2567 and then Known_Static_Esize (CT)
2570 S : constant Uint := Esize (CT);
2578 Set_Component_Size (E, Esize (CT));
2586 -- Lay out array and record types if front end layout set
2588 if Frontend_Layout_On_Target then
2589 if Is_Array_Type (E) and then not Is_Bit_Packed_Array (E) then
2590 Layout_Array_Type (E);
2591 elsif Is_Record_Type (E) then
2592 Layout_Record_Type (E);
2595 -- Case of backend layout, we still do a little in the front end
2598 -- Processing for record types
2600 if Is_Record_Type (E) then
2602 -- Special remaining processing for record types with a known
2603 -- size of 16, 32, or 64 bits whose alignment is not yet set.
2604 -- For these types, we set a corresponding alignment matching
2605 -- the size if possible, or as large as possible if not.
2607 if Convention (E) = Convention_Ada
2608 and then not Debug_Flag_Q
2610 Set_Composite_Alignment (E);
2613 -- Processing for array types
2615 elsif Is_Array_Type (E) then
2617 -- For arrays that are required to be atomic, we do the same
2618 -- processing as described above for short records, since we
2619 -- really need to have the alignment set for the whole array.
2621 if Is_Atomic (E) and then not Debug_Flag_Q then
2622 Set_Composite_Alignment (E);
2625 -- For unpacked array types, set an alignment of 1 if we know
2626 -- that the component alignment is not greater than 1. The reason
2627 -- we do this is to avoid unnecessary copying of slices of such
2628 -- arrays when passed to subprogram parameters (see special test
2629 -- in Exp_Ch6.Expand_Actuals).
2631 if not Is_Packed (E)
2632 and then Unknown_Alignment (E)
2634 if Known_Static_Component_Size (E)
2635 and then Component_Size (E) = 1
2637 Set_Alignment (E, Uint_1);
2643 -- Final step is to check that Esize and RM_Size are compatible
2645 if Known_Static_Esize (E) and then Known_Static_RM_Size (E) then
2646 if Esize (E) < RM_Size (E) then
2648 -- Esize is less than RM_Size. That's not good. First we test
2649 -- whether this was set deliberately with an Object_Size clause
2650 -- and if so, object to the clause.
2652 if Has_Object_Size_Clause (E) then
2653 Error_Msg_Uint_1 := RM_Size (E);
2655 ("object size is too small, minimum allowed is ^",
2656 Expression (Get_Attribute_Definition_Clause
2657 (E, Attribute_Object_Size)));
2660 -- Adjust Esize up to RM_Size value
2663 Size : constant Uint := RM_Size (E);
2666 Set_Esize (E, RM_Size (E));
2668 -- For scalar types, increase Object_Size to power of 2, but
2669 -- not less than a storage unit in any case (i.e., normally
2670 -- this means it will be storage-unit addressable).
2672 if Is_Scalar_Type (E) then
2673 if Size <= System_Storage_Unit then
2674 Init_Esize (E, System_Storage_Unit);
2675 elsif Size <= 16 then
2677 elsif Size <= 32 then
2680 Set_Esize (E, (Size + 63) / 64 * 64);
2683 -- Finally, make sure that alignment is consistent with
2684 -- the newly assigned size.
2686 while Alignment (E) * System_Storage_Unit < Esize (E)
2687 and then Alignment (E) < Maximum_Alignment
2689 Set_Alignment (E, 2 * Alignment (E));
2697 ---------------------
2698 -- Rewrite_Integer --
2699 ---------------------
2701 procedure Rewrite_Integer (N : Node_Id; V : Uint) is
2702 Loc : constant Source_Ptr := Sloc (N);
2703 Typ : constant Entity_Id := Etype (N);
2705 Rewrite (N, Make_Integer_Literal (Loc, Intval => V));
2707 end Rewrite_Integer;
2709 -------------------------------
2710 -- Set_And_Check_Static_Size --
2711 -------------------------------
2713 procedure Set_And_Check_Static_Size
2720 procedure Check_Size_Too_Small (Spec : Uint; Min : Uint);
2721 -- Spec is the number of bit specified in the size clause, and Min is
2722 -- the minimum computed size. An error is given that the specified size
2723 -- is too small if Spec < Min, and in this case both Esize and RM_Size
2724 -- are set to unknown in E. The error message is posted on node SC.
2726 procedure Check_Unused_Bits (Spec : Uint; Max : Uint);
2727 -- Spec is the number of bits specified in the size clause, and Max is
2728 -- the maximum computed size. A warning is given about unused bits if
2729 -- Spec > Max. This warning is posted on node SC.
2731 --------------------------
2732 -- Check_Size_Too_Small --
2733 --------------------------
2735 procedure Check_Size_Too_Small (Spec : Uint; Min : Uint) is
2738 Error_Msg_Uint_1 := Min;
2740 ("size for & too small, minimum allowed is ^", SC, E);
2744 end Check_Size_Too_Small;
2746 -----------------------
2747 -- Check_Unused_Bits --
2748 -----------------------
2750 procedure Check_Unused_Bits (Spec : Uint; Max : Uint) is
2753 Error_Msg_Uint_1 := Spec - Max;
2754 Error_Msg_NE ("?^ bits of & unused", SC, E);
2756 end Check_Unused_Bits;
2758 -- Start of processing for Set_And_Check_Static_Size
2761 -- Case where Object_Size (Esize) is already set by a size clause
2763 if Known_Static_Esize (E) then
2764 SC := Size_Clause (E);
2767 SC := Get_Attribute_Definition_Clause (E, Attribute_Object_Size);
2770 -- Perform checks on specified size against computed sizes
2772 if Present (SC) then
2773 Check_Unused_Bits (Esize (E), Esiz);
2774 Check_Size_Too_Small (Esize (E), RM_Siz);
2778 -- Case where Value_Size (RM_Size) is set by specific Value_Size clause
2779 -- (we do not need to worry about Value_Size being set by a Size clause,
2780 -- since that will have set Esize as well, and we already took care of
2783 if Known_Static_RM_Size (E) then
2784 SC := Get_Attribute_Definition_Clause (E, Attribute_Value_Size);
2786 -- Perform checks on specified size against computed sizes
2788 if Present (SC) then
2789 Check_Unused_Bits (RM_Size (E), Esiz);
2790 Check_Size_Too_Small (RM_Size (E), RM_Siz);
2794 -- Set sizes if unknown
2796 if Unknown_Esize (E) then
2797 Set_Esize (E, Esiz);
2800 if Unknown_RM_Size (E) then
2801 Set_RM_Size (E, RM_Siz);
2803 end Set_And_Check_Static_Size;
2805 -----------------------------
2806 -- Set_Composite_Alignment --
2807 -----------------------------
2809 procedure Set_Composite_Alignment (E : Entity_Id) is
2814 -- If alignment is already set, then nothing to do
2816 if Known_Alignment (E) then
2820 -- Alignment is not known, see if we can set it, taking into account
2821 -- the setting of the Optimize_Alignment mode.
2823 -- If Optimize_Alignment is set to Space, then packed records always
2824 -- have an alignment of 1. But don't do anything for atomic records
2825 -- since we may need higher alignment for indivisible access.
2827 if Optimize_Alignment_Space (E)
2828 and then Is_Record_Type (E)
2829 and then Is_Packed (E)
2830 and then not Is_Atomic (E)
2834 -- Not a record, or not packed
2837 -- The only other cases we worry about here are where the size is
2838 -- statically known at compile time.
2840 if Known_Static_Esize (E) then
2843 elsif Unknown_Esize (E)
2844 and then Known_Static_RM_Size (E)
2852 -- Size is known, alignment is not set
2854 -- Reset alignment to match size if the known size is exactly 2, 4,
2855 -- or 8 storage units.
2857 if Siz = 2 * System_Storage_Unit then
2859 elsif Siz = 4 * System_Storage_Unit then
2861 elsif Siz = 8 * System_Storage_Unit then
2864 -- If Optimize_Alignment is set to Space, then make sure the
2865 -- alignment matches the size, for example, if the size is 17
2866 -- bytes then we want an alignment of 1 for the type.
2868 elsif Optimize_Alignment_Space (E) then
2869 if Siz mod (8 * System_Storage_Unit) = 0 then
2871 elsif Siz mod (4 * System_Storage_Unit) = 0 then
2873 elsif Siz mod (2 * System_Storage_Unit) = 0 then
2879 -- If Optimize_Alignment is set to Time, then we reset for odd
2880 -- "in between sizes", for example a 17 bit record is given an
2881 -- alignment of 4. Note that this matches the old VMS behavior
2882 -- in versions of GNAT prior to 6.1.1.
2884 elsif Optimize_Alignment_Time (E)
2885 and then Siz > System_Storage_Unit
2886 and then Siz <= 8 * System_Storage_Unit
2888 if Siz <= 2 * System_Storage_Unit then
2890 elsif Siz <= 4 * System_Storage_Unit then
2892 else -- Siz <= 8 * System_Storage_Unit then
2896 -- No special alignment fiddling needed
2903 -- Here we have Set Align to the proposed improved value. Make sure the
2904 -- value set does not exceed Maximum_Alignment for the target.
2906 if Align > Maximum_Alignment then
2907 Align := Maximum_Alignment;
2910 -- Further processing for record types only to reduce the alignment
2911 -- set by the above processing in some specific cases. We do not
2912 -- do this for atomic records, since we need max alignment there,
2914 if Is_Record_Type (E) and then not Is_Atomic (E) then
2916 -- For records, there is generally no point in setting alignment
2917 -- higher than word size since we cannot do better than move by
2918 -- words in any case. Omit this if we are optimizing for time,
2919 -- since conceivably we may be able to do better.
2921 if Align > System_Word_Size / System_Storage_Unit
2922 and then not Optimize_Alignment_Time (E)
2924 Align := System_Word_Size / System_Storage_Unit;
2927 -- Check components. If any component requires a higher alignment,
2928 -- then we set that higher alignment in any case. Don't do this if
2929 -- we have Optimize_Alignment set to Space. Note that that covers
2930 -- the case of packed records, where we already set alignment to 1.
2932 if not Optimize_Alignment_Space (E) then
2937 Comp := First_Component (E);
2938 while Present (Comp) loop
2939 if Known_Alignment (Etype (Comp)) then
2941 Calign : constant Uint := Alignment (Etype (Comp));
2944 -- The cases to process are when the alignment of the
2945 -- component type is larger than the alignment we have
2946 -- so far, and either there is no component clause for
2947 -- the component, or the length set by the component
2948 -- clause matches the length of the component type.
2952 (Unknown_Esize (Comp)
2953 or else (Known_Static_Esize (Comp)
2956 Calign * System_Storage_Unit))
2958 Align := UI_To_Int (Calign);
2963 Next_Component (Comp);
2969 -- Set chosen alignment, and increase Esize if necessary to match the
2970 -- chosen alignment.
2972 Set_Alignment (E, UI_From_Int (Align));
2974 if Known_Static_Esize (E)
2975 and then Esize (E) < Align * System_Storage_Unit
2977 Set_Esize (E, UI_From_Int (Align * System_Storage_Unit));
2979 end Set_Composite_Alignment;
2981 --------------------------
2982 -- Set_Discrete_RM_Size --
2983 --------------------------
2985 procedure Set_Discrete_RM_Size (Def_Id : Entity_Id) is
2986 FST : constant Entity_Id := First_Subtype (Def_Id);
2989 -- All discrete types except for the base types in standard are
2990 -- constrained, so indicate this by setting Is_Constrained.
2992 Set_Is_Constrained (Def_Id);
2994 -- Set generic types to have an unknown size, since the representation
2995 -- of a generic type is irrelevant, in view of the fact that they have
2996 -- nothing to do with code.
2998 if Is_Generic_Type (Root_Type (FST)) then
2999 Set_RM_Size (Def_Id, Uint_0);
3001 -- If the subtype statically matches the first subtype, then it is
3002 -- required to have exactly the same layout. This is required by
3003 -- aliasing considerations.
3005 elsif Def_Id /= FST and then
3006 Subtypes_Statically_Match (Def_Id, FST)
3008 Set_RM_Size (Def_Id, RM_Size (FST));
3009 Set_Size_Info (Def_Id, FST);
3011 -- In all other cases the RM_Size is set to the minimum size. Note that
3012 -- this routine is never called for subtypes for which the RM_Size is
3013 -- set explicitly by an attribute clause.
3016 Set_RM_Size (Def_Id, UI_From_Int (Minimum_Size (Def_Id)));
3018 end Set_Discrete_RM_Size;
3020 ------------------------
3021 -- Set_Elem_Alignment --
3022 ------------------------
3024 procedure Set_Elem_Alignment (E : Entity_Id) is
3026 -- Do not set alignment for packed array types, unless we are doing
3027 -- front end layout, because otherwise this is always handled in the
3030 if Is_Packed_Array_Type (E) and then not Frontend_Layout_On_Target then
3033 -- If there is an alignment clause, then we respect it
3035 elsif Has_Alignment_Clause (E) then
3038 -- If the size is not set, then don't attempt to set the alignment. This
3039 -- happens in the backend layout case for access-to-subprogram types.
3041 elsif not Known_Static_Esize (E) then
3044 -- For access types, do not set the alignment if the size is less than
3045 -- the allowed minimum size. This avoids cascaded error messages.
3047 elsif Is_Access_Type (E)
3048 and then Esize (E) < System_Address_Size
3053 -- Here we calculate the alignment as the largest power of two multiple
3054 -- of System.Storage_Unit that does not exceed either the actual size of
3055 -- the type, or the maximum allowed alignment.
3058 S : constant Int := UI_To_Int (Esize (E)) / SSU;
3060 Max_Alignment : Nat;
3063 -- If the default alignment of "double" floating-point types is
3064 -- specifically capped, enforce the cap.
3066 if Ttypes.Target_Double_Float_Alignment > 0
3068 and then Is_Floating_Point_Type (E)
3070 Max_Alignment := Ttypes.Target_Double_Float_Alignment;
3072 -- If the default alignment of "double" or larger scalar types is
3073 -- specifically capped, enforce the cap.
3075 elsif Ttypes.Target_Double_Scalar_Alignment > 0
3077 and then Is_Scalar_Type (E)
3079 Max_Alignment := Ttypes.Target_Double_Scalar_Alignment;
3081 -- Otherwise enforce the overall alignment cap
3084 Max_Alignment := Ttypes.Maximum_Alignment;
3088 while 2 * A <= Max_Alignment and then 2 * A <= S loop
3092 -- Now we think we should set the alignment to A, but we skip this if
3093 -- an alignment is already set to a value greater than A (happens for
3096 -- However, if the alignment is known and too small it must be
3097 -- increased, this happens in a case like:
3099 -- type R is new Character;
3100 -- for R'Size use 16;
3102 -- Here the alignment inherited from Character is 1, but it must be
3103 -- increased to 2 to reflect the increased size.
3105 if Unknown_Alignment (E) or else Alignment (E) < A then
3106 Init_Alignment (E, A);
3109 end Set_Elem_Alignment;
3111 ----------------------
3112 -- SO_Ref_From_Expr --
3113 ----------------------
3115 function SO_Ref_From_Expr
3117 Ins_Type : Entity_Id;
3118 Vtype : Entity_Id := Empty;
3119 Make_Func : Boolean := False) return Dynamic_SO_Ref
3121 Loc : constant Source_Ptr := Sloc (Ins_Type);
3123 K : constant Entity_Id :=
3124 Make_Defining_Identifier (Loc,
3125 Chars => New_Internal_Name ('K'));
3129 Vtype_Primary_View : Entity_Id;
3131 function Check_Node_V_Ref (N : Node_Id) return Traverse_Result;
3132 -- Function used to check one node for reference to V
3134 function Has_V_Ref is new Traverse_Func (Check_Node_V_Ref);
3135 -- Function used to traverse tree to check for reference to V
3137 ----------------------
3138 -- Check_Node_V_Ref --
3139 ----------------------
3141 function Check_Node_V_Ref (N : Node_Id) return Traverse_Result is
3143 if Nkind (N) = N_Identifier then
3144 if Chars (N) = Vname then
3153 end Check_Node_V_Ref;
3155 -- Start of processing for SO_Ref_From_Expr
3158 -- Case of expression is an integer literal, in this case we just
3159 -- return the value (which must always be non-negative, since size
3160 -- and offset values can never be negative).
3162 if Nkind (Expr) = N_Integer_Literal then
3163 pragma Assert (Intval (Expr) >= 0);
3164 return Intval (Expr);
3167 -- Case where there is a reference to V, create function
3169 if Has_V_Ref (Expr) = Abandon then
3171 pragma Assert (Present (Vtype));
3173 -- Check whether Vtype is a view of a private type and ensure that
3174 -- we use the primary view of the type (which is denoted by its
3175 -- Etype, whether it's the type's partial or full view entity).
3176 -- This is needed to make sure that we use the same (primary) view
3177 -- of the type for all V formals, whether the current view of the
3178 -- type is the partial or full view, so that types will always
3179 -- match on calls from one size function to another.
3181 if Has_Private_Declaration (Vtype) then
3182 Vtype_Primary_View := Etype (Vtype);
3184 Vtype_Primary_View := Vtype;
3187 Set_Is_Discrim_SO_Function (K);
3190 Make_Subprogram_Body (Loc,
3193 Make_Function_Specification (Loc,
3194 Defining_Unit_Name => K,
3195 Parameter_Specifications => New_List (
3196 Make_Parameter_Specification (Loc,
3197 Defining_Identifier =>
3198 Make_Defining_Identifier (Loc, Chars => Vname),
3200 New_Occurrence_Of (Vtype_Primary_View, Loc))),
3201 Result_Definition =>
3202 New_Occurrence_Of (Standard_Unsigned, Loc)),
3204 Declarations => Empty_List,
3206 Handled_Statement_Sequence =>
3207 Make_Handled_Sequence_Of_Statements (Loc,
3208 Statements => New_List (
3209 Make_Simple_Return_Statement (Loc,
3210 Expression => Expr))));
3212 -- The caller requests that the expression be encapsulated in a
3213 -- parameterless function.
3215 elsif Make_Func then
3217 Make_Subprogram_Body (Loc,
3220 Make_Function_Specification (Loc,
3221 Defining_Unit_Name => K,
3222 Parameter_Specifications => Empty_List,
3223 Result_Definition =>
3224 New_Occurrence_Of (Standard_Unsigned, Loc)),
3226 Declarations => Empty_List,
3228 Handled_Statement_Sequence =>
3229 Make_Handled_Sequence_Of_Statements (Loc,
3230 Statements => New_List (
3231 Make_Simple_Return_Statement (Loc, Expression => Expr))));
3233 -- No reference to V and function not requested, so create a constant
3237 Make_Object_Declaration (Loc,
3238 Defining_Identifier => K,
3239 Object_Definition =>
3240 New_Occurrence_Of (Standard_Unsigned, Loc),
3241 Constant_Present => True,
3242 Expression => Expr);
3245 Append_Freeze_Action (Ins_Type, Decl);
3247 return Create_Dynamic_SO_Ref (K);
3248 end SO_Ref_From_Expr;