1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2009, 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 Einfo; use Einfo;
29 with Errout; use Errout;
30 with Exp_Dbug; use Exp_Dbug;
31 with Exp_Util; use Exp_Util;
32 with Layout; use Layout;
33 with Namet; use Namet;
34 with Nlists; use Nlists;
35 with Nmake; use Nmake;
37 with Rtsfind; use Rtsfind;
39 with Sem_Aux; use Sem_Aux;
40 with Sem_Ch3; use Sem_Ch3;
41 with Sem_Ch8; use Sem_Ch8;
42 with Sem_Ch13; use Sem_Ch13;
43 with Sem_Eval; use Sem_Eval;
44 with Sem_Res; use Sem_Res;
45 with Sem_Util; use Sem_Util;
46 with Sinfo; use Sinfo;
47 with Snames; use Snames;
48 with Stand; use Stand;
49 with Targparm; use Targparm;
50 with Tbuild; use Tbuild;
51 with Ttypes; use Ttypes;
52 with Uintp; use Uintp;
54 package body Exp_Pakd is
56 ---------------------------
57 -- Endian Considerations --
58 ---------------------------
60 -- As described in the specification, bit numbering in a packed array
61 -- is consistent with bit numbering in a record representation clause,
62 -- and hence dependent on the endianness of the machine:
64 -- For little-endian machines, element zero is at the right hand end
65 -- (low order end) of a bit field.
67 -- For big-endian machines, element zero is at the left hand end
68 -- (high order end) of a bit field.
70 -- The shifts that are used to right justify a field therefore differ
71 -- in the two cases. For the little-endian case, we can simply use the
72 -- bit number (i.e. the element number * element size) as the count for
73 -- a right shift. For the big-endian case, we have to subtract the shift
74 -- count from an appropriate constant to use in the right shift. We use
75 -- rotates instead of shifts (which is necessary in the store case to
76 -- preserve other fields), and we expect that the backend will be able
77 -- to change the right rotate into a left rotate, avoiding the subtract,
78 -- if the architecture provides such an instruction.
80 ----------------------------------------------
81 -- Entity Tables for Packed Access Routines --
82 ----------------------------------------------
84 -- For the cases of component size = 3,5-7,9-15,17-31,33-63 we call
85 -- library routines. This table is used to obtain the entity for the
88 type E_Array is array (Int range 01 .. 63) of RE_Id;
90 -- Array of Bits_nn entities. Note that we do not use library routines
91 -- for the 8-bit and 16-bit cases, but we still fill in the table, using
92 -- entries from System.Unsigned, because we also use this table for
93 -- certain special unchecked conversions in the big-endian case.
95 Bits_Id : constant E_Array :=
111 16 => RE_Unsigned_16,
127 32 => RE_Unsigned_32,
160 -- Array of Get routine entities. These are used to obtain an element
161 -- from a packed array. The N'th entry is used to obtain elements from
162 -- a packed array whose component size is N. RE_Null is used as a null
163 -- entry, for the cases where a library routine is not used.
165 Get_Id : constant E_Array :=
230 -- Array of Get routine entities to be used in the case where the packed
231 -- array is itself a component of a packed structure, and therefore may
232 -- not be fully aligned. This only affects the even sizes, since for the
233 -- odd sizes, we do not get any fixed alignment in any case.
235 GetU_Id : constant E_Array :=
300 -- Array of Set routine entities. These are used to assign an element
301 -- of a packed array. The N'th entry is used to assign elements for
302 -- a packed array whose component size is N. RE_Null is used as a null
303 -- entry, for the cases where a library routine is not used.
305 Set_Id : constant E_Array :=
370 -- Array of Set routine entities to be used in the case where the packed
371 -- array is itself a component of a packed structure, and therefore may
372 -- not be fully aligned. This only affects the even sizes, since for the
373 -- odd sizes, we do not get any fixed alignment in any case.
375 SetU_Id : constant E_Array :=
440 -----------------------
441 -- Local Subprograms --
442 -----------------------
444 procedure Compute_Linear_Subscript
447 Subscr : out Node_Id);
448 -- Given a constrained array type Atyp, and an indexed component node
449 -- N referencing an array object of this type, build an expression of
450 -- type Standard.Integer representing the zero-based linear subscript
451 -- value. This expression includes any required range checks.
453 procedure Convert_To_PAT_Type (Aexp : Node_Id);
454 -- Given an expression of a packed array type, builds a corresponding
455 -- expression whose type is the implementation type used to represent
456 -- the packed array. Aexp is analyzed and resolved on entry and on exit.
458 function Known_Aligned_Enough (Obj : Node_Id; Csiz : Nat) return Boolean;
459 -- There are two versions of the Set routines, the ones used when the
460 -- object is known to be sufficiently well aligned given the number of
461 -- bits, and the ones used when the object is not known to be aligned.
462 -- This routine is used to determine which set to use. Obj is a reference
463 -- to the object, and Csiz is the component size of the packed array.
464 -- True is returned if the alignment of object is known to be sufficient,
465 -- defined as 1 for odd bit sizes, 4 for bit sizes divisible by 4, and
468 function Make_Shift_Left (N : Node_Id; S : Node_Id) return Node_Id;
469 -- Build a left shift node, checking for the case of a shift count of zero
471 function Make_Shift_Right (N : Node_Id; S : Node_Id) return Node_Id;
472 -- Build a right shift node, checking for the case of a shift count of zero
474 function RJ_Unchecked_Convert_To
476 Expr : Node_Id) return Node_Id;
477 -- The packed array code does unchecked conversions which in some cases
478 -- may involve non-discrete types with differing sizes. The semantics of
479 -- such conversions is potentially endian dependent, and the effect we
480 -- want here for such a conversion is to do the conversion in size as
481 -- though numeric items are involved, and we extend or truncate on the
482 -- left side. This happens naturally in the little-endian case, but in
483 -- the big endian case we can get left justification, when what we want
484 -- is right justification. This routine does the unchecked conversion in
485 -- a stepwise manner to ensure that it gives the expected result. Hence
486 -- the name (RJ = Right justified). The parameters Typ and Expr are as
487 -- for the case of a normal Unchecked_Convert_To call.
489 procedure Setup_Enumeration_Packed_Array_Reference (N : Node_Id);
490 -- This routine is called in the Get and Set case for arrays that are
491 -- packed but not bit-packed, meaning that they have at least one
492 -- subscript that is of an enumeration type with a non-standard
493 -- representation. This routine modifies the given node to properly
494 -- reference the corresponding packed array type.
496 procedure Setup_Inline_Packed_Array_Reference
499 Obj : in out Node_Id;
501 Shift : out Node_Id);
502 -- This procedure performs common processing on the N_Indexed_Component
503 -- parameter given as N, whose prefix is a reference to a packed array.
504 -- This is used for the get and set when the component size is 1,2,4
505 -- or for other component sizes when the packed array type is a modular
506 -- type (i.e. the cases that are handled with inline code).
510 -- N is the N_Indexed_Component node for the packed array reference
512 -- Atyp is the constrained array type (the actual subtype has been
513 -- computed if necessary to obtain the constraints, but this is still
514 -- the original array type, not the Packed_Array_Type value).
516 -- Obj is the object which is to be indexed. It is always of type Atyp.
520 -- Obj is the object containing the desired bit field. It is of type
521 -- Unsigned, Long_Unsigned, or Long_Long_Unsigned, and is either the
522 -- entire value, for the small static case, or the proper selected byte
523 -- from the array in the large or dynamic case. This node is analyzed
524 -- and resolved on return.
526 -- Shift is a node representing the shift count to be used in the
527 -- rotate right instruction that positions the field for access.
528 -- This node is analyzed and resolved on return.
530 -- Cmask is a mask corresponding to the width of the component field.
531 -- Its value is 2 ** Csize - 1 (e.g. 2#1111# for component size of 4).
533 -- Note: in some cases the call to this routine may generate actions
534 -- (for handling multi-use references and the generation of the packed
535 -- array type on the fly). Such actions are inserted into the tree
536 -- directly using Insert_Action.
538 ------------------------------
539 -- Compute_Linear_Subscript --
540 ------------------------------
542 procedure Compute_Linear_Subscript
545 Subscr : out Node_Id)
547 Loc : constant Source_Ptr := Sloc (N);
556 -- Loop through dimensions
558 Indx := First_Index (Atyp);
559 Oldsub := First (Expressions (N));
561 while Present (Indx) loop
562 Styp := Etype (Indx);
563 Newsub := Relocate_Node (Oldsub);
565 -- Get expression for the subscript value. First, if Do_Range_Check
566 -- is set on a subscript, then we must do a range check against the
567 -- original bounds (not the bounds of the packed array type). We do
568 -- this by introducing a subtype conversion.
570 if Do_Range_Check (Newsub)
571 and then Etype (Newsub) /= Styp
573 Newsub := Convert_To (Styp, Newsub);
576 -- Now evolve the expression for the subscript. First convert
577 -- the subscript to be zero based and of an integer type.
579 -- Case of integer type, where we just subtract to get lower bound
581 if Is_Integer_Type (Styp) then
583 -- If length of integer type is smaller than standard integer,
584 -- then we convert to integer first, then do the subtract
586 -- Integer (subscript) - Integer (Styp'First)
588 if Esize (Styp) < Esize (Standard_Integer) then
590 Make_Op_Subtract (Loc,
591 Left_Opnd => Convert_To (Standard_Integer, Newsub),
593 Convert_To (Standard_Integer,
594 Make_Attribute_Reference (Loc,
595 Prefix => New_Occurrence_Of (Styp, Loc),
596 Attribute_Name => Name_First)));
598 -- For larger integer types, subtract first, then convert to
599 -- integer, this deals with strange long long integer bounds.
601 -- Integer (subscript - Styp'First)
605 Convert_To (Standard_Integer,
606 Make_Op_Subtract (Loc,
609 Make_Attribute_Reference (Loc,
610 Prefix => New_Occurrence_Of (Styp, Loc),
611 Attribute_Name => Name_First)));
614 -- For the enumeration case, we have to use 'Pos to get the value
615 -- to work with before subtracting the lower bound.
617 -- Integer (Styp'Pos (subscr)) - Integer (Styp'Pos (Styp'First));
619 -- This is not quite right for bizarre cases where the size of the
620 -- enumeration type is > Integer'Size bits due to rep clause ???
623 pragma Assert (Is_Enumeration_Type (Styp));
626 Make_Op_Subtract (Loc,
627 Left_Opnd => Convert_To (Standard_Integer,
628 Make_Attribute_Reference (Loc,
629 Prefix => New_Occurrence_Of (Styp, Loc),
630 Attribute_Name => Name_Pos,
631 Expressions => New_List (Newsub))),
634 Convert_To (Standard_Integer,
635 Make_Attribute_Reference (Loc,
636 Prefix => New_Occurrence_Of (Styp, Loc),
637 Attribute_Name => Name_Pos,
638 Expressions => New_List (
639 Make_Attribute_Reference (Loc,
640 Prefix => New_Occurrence_Of (Styp, Loc),
641 Attribute_Name => Name_First)))));
644 Set_Paren_Count (Newsub, 1);
646 -- For the first subscript, we just copy that subscript value
651 -- Otherwise, we must multiply what we already have by the current
652 -- stride and then add in the new value to the evolving subscript.
658 Make_Op_Multiply (Loc,
661 Make_Attribute_Reference (Loc,
662 Attribute_Name => Name_Range_Length,
663 Prefix => New_Occurrence_Of (Styp, Loc))),
664 Right_Opnd => Newsub);
667 -- Move to next subscript
672 end Compute_Linear_Subscript;
674 -------------------------
675 -- Convert_To_PAT_Type --
676 -------------------------
678 -- The PAT is always obtained from the actual subtype
680 procedure Convert_To_PAT_Type (Aexp : Node_Id) is
684 Convert_To_Actual_Subtype (Aexp);
685 Act_ST := Underlying_Type (Etype (Aexp));
686 Create_Packed_Array_Type (Act_ST);
688 -- Just replace the etype with the packed array type. This works because
689 -- the expression will not be further analyzed, and Gigi considers the
690 -- two types equivalent in any case.
692 -- This is not strictly the case ??? If the reference is an actual in
693 -- call, the expansion of the prefix is delayed, and must be reanalyzed,
694 -- see Reset_Packed_Prefix. On the other hand, if the prefix is a simple
695 -- array reference, reanalysis can produce spurious type errors when the
696 -- PAT type is replaced again with the original type of the array. Same
697 -- for the case of a dereference. The following is correct and minimal,
698 -- but the handling of more complex packed expressions in actuals is
699 -- confused. Probably the problem only remains for actuals in calls.
701 Set_Etype (Aexp, Packed_Array_Type (Act_ST));
703 if Is_Entity_Name (Aexp)
705 (Nkind (Aexp) = N_Indexed_Component
706 and then Is_Entity_Name (Prefix (Aexp)))
707 or else Nkind (Aexp) = N_Explicit_Dereference
711 end Convert_To_PAT_Type;
713 ------------------------------
714 -- Create_Packed_Array_Type --
715 ------------------------------
717 procedure Create_Packed_Array_Type (Typ : Entity_Id) is
718 Loc : constant Source_Ptr := Sloc (Typ);
719 Ctyp : constant Entity_Id := Component_Type (Typ);
720 Csize : constant Uint := Component_Size (Typ);
735 procedure Install_PAT;
736 -- This procedure is called with Decl set to the declaration for the
737 -- packed array type. It creates the type and installs it as required.
739 procedure Set_PB_Type;
740 -- Sets PB_Type to Packed_Bytes{1,2,4} as required by the alignment
741 -- requirements (see documentation in the spec of this package).
747 procedure Install_PAT is
748 Pushed_Scope : Boolean := False;
751 -- We do not want to put the declaration we have created in the tree
752 -- since it is often hard, and sometimes impossible to find a proper
753 -- place for it (the impossible case arises for a packed array type
754 -- with bounds depending on the discriminant, a declaration cannot
755 -- be put inside the record, and the reference to the discriminant
756 -- cannot be outside the record).
758 -- The solution is to analyze the declaration while temporarily
759 -- attached to the tree at an appropriate point, and then we install
760 -- the resulting type as an Itype in the packed array type field of
761 -- the original type, so that no explicit declaration is required.
763 -- Note: the packed type is created in the scope of its parent
764 -- type. There are at least some cases where the current scope
765 -- is deeper, and so when this is the case, we temporarily reset
766 -- the scope for the definition. This is clearly safe, since the
767 -- first use of the packed array type will be the implicit
768 -- reference from the corresponding unpacked type when it is
771 if Is_Itype (Typ) then
772 Set_Parent (Decl, Associated_Node_For_Itype (Typ));
774 Set_Parent (Decl, Declaration_Node (Typ));
777 if Scope (Typ) /= Current_Scope then
778 Push_Scope (Scope (Typ));
779 Pushed_Scope := True;
782 Set_Is_Itype (PAT, True);
783 Set_Packed_Array_Type (Typ, PAT);
784 Analyze (Decl, Suppress => All_Checks);
790 -- Set Esize and RM_Size to the actual size of the packed object
791 -- Do not reset RM_Size if already set, as happens in the case of
794 if Unknown_Esize (PAT) then
795 Set_Esize (PAT, PASize);
798 if Unknown_RM_Size (PAT) then
799 Set_RM_Size (PAT, PASize);
802 Adjust_Esize_Alignment (PAT);
804 -- Set remaining fields of packed array type
806 Init_Alignment (PAT);
807 Set_Parent (PAT, Empty);
808 Set_Associated_Node_For_Itype (PAT, Typ);
809 Set_Is_Packed_Array_Type (PAT, True);
810 Set_Original_Array_Type (PAT, Typ);
812 -- We definitely do not want to delay freezing for packed array
813 -- types. This is of particular importance for the itypes that
814 -- are generated for record components depending on discriminants
815 -- where there is no place to put the freeze node.
817 Set_Has_Delayed_Freeze (PAT, False);
818 Set_Has_Delayed_Freeze (Etype (PAT), False);
820 -- If we did allocate a freeze node, then clear out the reference
821 -- since it is obsolete (should we delete the freeze node???)
823 Set_Freeze_Node (PAT, Empty);
824 Set_Freeze_Node (Etype (PAT), Empty);
831 procedure Set_PB_Type is
833 -- If the user has specified an explicit alignment for the
834 -- type or component, take it into account.
836 if Csize <= 2 or else Csize = 4 or else Csize mod 2 /= 0
837 or else Alignment (Typ) = 1
838 or else Component_Alignment (Typ) = Calign_Storage_Unit
840 PB_Type := RTE (RE_Packed_Bytes1);
842 elsif Csize mod 4 /= 0
843 or else Alignment (Typ) = 2
845 PB_Type := RTE (RE_Packed_Bytes2);
848 PB_Type := RTE (RE_Packed_Bytes4);
852 -- Start of processing for Create_Packed_Array_Type
855 -- If we already have a packed array type, nothing to do
857 if Present (Packed_Array_Type (Typ)) then
861 -- If our immediate ancestor subtype is constrained, and it already
862 -- has a packed array type, then just share the same type, since the
863 -- bounds must be the same. If the ancestor is not an array type but
864 -- a private type, as can happen with multiple instantiations, create
865 -- a new packed type, to avoid privacy issues.
867 if Ekind (Typ) = E_Array_Subtype then
868 Ancest := Ancestor_Subtype (Typ);
871 and then Is_Array_Type (Ancest)
872 and then Is_Constrained (Ancest)
873 and then Present (Packed_Array_Type (Ancest))
875 Set_Packed_Array_Type (Typ, Packed_Array_Type (Ancest));
880 -- We preset the result type size from the size of the original array
881 -- type, since this size clearly belongs to the packed array type. The
882 -- size of the conceptual unpacked type is always set to unknown.
884 PASize := RM_Size (Typ);
886 -- Case of an array where at least one index is of an enumeration
887 -- type with a non-standard representation, but the component size
888 -- is not appropriate for bit packing. This is the case where we
889 -- have Is_Packed set (we would never be in this unit otherwise),
890 -- but Is_Bit_Packed_Array is false.
892 -- Note that if the component size is appropriate for bit packing,
893 -- then the circuit for the computation of the subscript properly
894 -- deals with the non-standard enumeration type case by taking the
897 if not Is_Bit_Packed_Array (Typ) then
899 -- Here we build a declaration:
901 -- type tttP is array (index1, index2, ...) of component_type
903 -- where index1, index2, are the index types. These are the same
904 -- as the index types of the original array, except for the non-
905 -- standard representation enumeration type case, where we have
908 -- For the unconstrained array case, we use
912 -- For the constrained case, we use
914 -- Natural range Enum_Type'Pos (Enum_Type'First) ..
915 -- Enum_Type'Pos (Enum_Type'Last);
918 Make_Defining_Identifier (Loc,
919 Chars => New_External_Name (Chars (Typ), 'P'));
921 Set_Packed_Array_Type (Typ, PAT);
924 Indexes : constant List_Id := New_List;
926 Indx_Typ : Entity_Id;
931 Indx := First_Index (Typ);
933 while Present (Indx) loop
934 Indx_Typ := Etype (Indx);
936 Enum_Case := Is_Enumeration_Type (Indx_Typ)
937 and then Has_Non_Standard_Rep (Indx_Typ);
939 -- Unconstrained case
941 if not Is_Constrained (Typ) then
943 Indx_Typ := Standard_Natural;
946 Append_To (Indexes, New_Occurrence_Of (Indx_Typ, Loc));
951 if not Enum_Case then
952 Append_To (Indexes, New_Occurrence_Of (Indx_Typ, Loc));
956 Make_Subtype_Indication (Loc,
958 New_Occurrence_Of (Standard_Natural, Loc),
960 Make_Range_Constraint (Loc,
964 Make_Attribute_Reference (Loc,
966 New_Occurrence_Of (Indx_Typ, Loc),
967 Attribute_Name => Name_Pos,
968 Expressions => New_List (
969 Make_Attribute_Reference (Loc,
971 New_Occurrence_Of (Indx_Typ, Loc),
972 Attribute_Name => Name_First))),
975 Make_Attribute_Reference (Loc,
977 New_Occurrence_Of (Indx_Typ, Loc),
978 Attribute_Name => Name_Pos,
979 Expressions => New_List (
980 Make_Attribute_Reference (Loc,
982 New_Occurrence_Of (Indx_Typ, Loc),
983 Attribute_Name => Name_Last)))))));
991 if not Is_Constrained (Typ) then
993 Make_Unconstrained_Array_Definition (Loc,
994 Subtype_Marks => Indexes,
995 Component_Definition =>
996 Make_Component_Definition (Loc,
997 Aliased_Present => False,
998 Subtype_Indication =>
999 New_Occurrence_Of (Ctyp, Loc)));
1003 Make_Constrained_Array_Definition (Loc,
1004 Discrete_Subtype_Definitions => Indexes,
1005 Component_Definition =>
1006 Make_Component_Definition (Loc,
1007 Aliased_Present => False,
1008 Subtype_Indication =>
1009 New_Occurrence_Of (Ctyp, Loc)));
1013 Make_Full_Type_Declaration (Loc,
1014 Defining_Identifier => PAT,
1015 Type_Definition => Typedef);
1018 -- Set type as packed array type and install it
1020 Set_Is_Packed_Array_Type (PAT);
1024 -- Case of bit-packing required for unconstrained array. We create
1025 -- a subtype that is equivalent to use Packed_Bytes{1,2,4} as needed.
1027 elsif not Is_Constrained (Typ) then
1029 Make_Defining_Identifier (Loc,
1030 Chars => Make_Packed_Array_Type_Name (Typ, Csize));
1032 Set_Packed_Array_Type (Typ, PAT);
1036 Make_Subtype_Declaration (Loc,
1037 Defining_Identifier => PAT,
1038 Subtype_Indication => New_Occurrence_Of (PB_Type, Loc));
1042 -- Remaining code is for the case of bit-packing for constrained array
1044 -- The name of the packed array subtype is
1048 -- where sss is the component size in bits and ttt is the name of
1049 -- the parent packed type.
1053 Make_Defining_Identifier (Loc,
1054 Chars => Make_Packed_Array_Type_Name (Typ, Csize));
1056 Set_Packed_Array_Type (Typ, PAT);
1058 -- Build an expression for the length of the array in bits.
1059 -- This is the product of the length of each of the dimensions
1065 Len_Expr := Empty; -- suppress junk warning
1069 Make_Attribute_Reference (Loc,
1070 Attribute_Name => Name_Length,
1071 Prefix => New_Occurrence_Of (Typ, Loc),
1072 Expressions => New_List (
1073 Make_Integer_Literal (Loc, J)));
1076 Len_Expr := Len_Dim;
1080 Make_Op_Multiply (Loc,
1081 Left_Opnd => Len_Expr,
1082 Right_Opnd => Len_Dim);
1086 exit when J > Number_Dimensions (Typ);
1090 -- Temporarily attach the length expression to the tree and analyze
1091 -- and resolve it, so that we can test its value. We assume that the
1092 -- total length fits in type Integer. This expression may involve
1093 -- discriminants, so we treat it as a default/per-object expression.
1095 Set_Parent (Len_Expr, Typ);
1096 Preanalyze_Spec_Expression (Len_Expr, Standard_Long_Long_Integer);
1098 -- Use a modular type if possible. We can do this if we have
1099 -- static bounds, and the length is small enough, and the length
1100 -- is not zero. We exclude the zero length case because the size
1101 -- of things is always at least one, and the zero length object
1102 -- would have an anomalous size.
1104 if Compile_Time_Known_Value (Len_Expr) then
1105 Len_Bits := Expr_Value (Len_Expr) * Csize;
1107 -- Check for size known to be too large
1110 Uint_2 ** (Standard_Integer_Size - 1) * System_Storage_Unit
1112 if System_Storage_Unit = 8 then
1114 ("packed array size cannot exceed " &
1115 "Integer''Last bytes", Typ);
1118 ("packed array size cannot exceed " &
1119 "Integer''Last storage units", Typ);
1122 -- Reset length to arbitrary not too high value to continue
1124 Len_Expr := Make_Integer_Literal (Loc, 65535);
1125 Analyze_And_Resolve (Len_Expr, Standard_Long_Long_Integer);
1128 -- We normally consider small enough to mean no larger than the
1129 -- value of System_Max_Binary_Modulus_Power, checking that in the
1130 -- case of values longer than word size, we have long shifts.
1134 (Len_Bits <= System_Word_Size
1135 or else (Len_Bits <= System_Max_Binary_Modulus_Power
1136 and then Support_Long_Shifts_On_Target))
1138 -- Also test for alignment given. If an alignment is given which
1139 -- is smaller than the natural modular alignment, force the array
1140 -- of bytes representation to accommodate the alignment.
1143 (No (Alignment_Clause (Typ))
1145 Alignment (Typ) >= ((Len_Bits + System_Storage_Unit)
1146 / System_Storage_Unit))
1148 -- We can use the modular type, it has the form:
1150 -- subtype tttPn is btyp
1151 -- range 0 .. 2 ** ((Typ'Length (1)
1152 -- * ... * Typ'Length (n)) * Csize) - 1;
1154 -- The bounds are statically known, and btyp is one of the
1155 -- unsigned types, depending on the length.
1157 if Len_Bits <= Standard_Short_Short_Integer_Size then
1158 Btyp := RTE (RE_Short_Short_Unsigned);
1160 elsif Len_Bits <= Standard_Short_Integer_Size then
1161 Btyp := RTE (RE_Short_Unsigned);
1163 elsif Len_Bits <= Standard_Integer_Size then
1164 Btyp := RTE (RE_Unsigned);
1166 elsif Len_Bits <= Standard_Long_Integer_Size then
1167 Btyp := RTE (RE_Long_Unsigned);
1170 Btyp := RTE (RE_Long_Long_Unsigned);
1173 Lit := Make_Integer_Literal (Loc, 2 ** Len_Bits - 1);
1174 Set_Print_In_Hex (Lit);
1177 Make_Subtype_Declaration (Loc,
1178 Defining_Identifier => PAT,
1179 Subtype_Indication =>
1180 Make_Subtype_Indication (Loc,
1181 Subtype_Mark => New_Occurrence_Of (Btyp, Loc),
1184 Make_Range_Constraint (Loc,
1188 Make_Integer_Literal (Loc, 0),
1189 High_Bound => Lit))));
1191 if PASize = Uint_0 then
1200 -- Could not use a modular type, for all other cases, we build
1201 -- a packed array subtype:
1204 -- System.Packed_Bytes{1,2,4} (0 .. (Bits + 7) / 8 - 1);
1206 -- Bits is the length of the array in bits
1213 Make_Op_Multiply (Loc,
1215 Make_Integer_Literal (Loc, Csize),
1216 Right_Opnd => Len_Expr),
1219 Make_Integer_Literal (Loc, 7));
1221 Set_Paren_Count (Bits_U1, 1);
1224 Make_Op_Subtract (Loc,
1226 Make_Op_Divide (Loc,
1227 Left_Opnd => Bits_U1,
1228 Right_Opnd => Make_Integer_Literal (Loc, 8)),
1229 Right_Opnd => Make_Integer_Literal (Loc, 1));
1232 Make_Subtype_Declaration (Loc,
1233 Defining_Identifier => PAT,
1234 Subtype_Indication =>
1235 Make_Subtype_Indication (Loc,
1236 Subtype_Mark => New_Occurrence_Of (PB_Type, Loc),
1238 Make_Index_Or_Discriminant_Constraint (Loc,
1239 Constraints => New_List (
1242 Make_Integer_Literal (Loc, 0),
1244 Convert_To (Standard_Integer, PAT_High))))));
1248 -- Currently the code in this unit requires that packed arrays
1249 -- represented by non-modular arrays of bytes be on a byte
1250 -- boundary for bit sizes handled by System.Pack_nn units.
1251 -- That's because these units assume the array being accessed
1252 -- starts on a byte boundary.
1254 if Get_Id (UI_To_Int (Csize)) /= RE_Null then
1255 Set_Must_Be_On_Byte_Boundary (Typ);
1258 end Create_Packed_Array_Type;
1260 -----------------------------------
1261 -- Expand_Bit_Packed_Element_Set --
1262 -----------------------------------
1264 procedure Expand_Bit_Packed_Element_Set (N : Node_Id) is
1265 Loc : constant Source_Ptr := Sloc (N);
1266 Lhs : constant Node_Id := Name (N);
1268 Ass_OK : constant Boolean := Assignment_OK (Lhs);
1269 -- Used to preserve assignment OK status when assignment is rewritten
1271 Rhs : Node_Id := Expression (N);
1272 -- Initially Rhs is the right hand side value, it will be replaced
1273 -- later by an appropriate unchecked conversion for the assignment.
1283 -- The expression for the shift value that is required
1285 Shift_Used : Boolean := False;
1286 -- Set True if Shift has been used in the generated code at least
1287 -- once, so that it must be duplicated if used again
1292 Rhs_Val_Known : Boolean;
1294 -- If the value of the right hand side as an integer constant is
1295 -- known at compile time, Rhs_Val_Known is set True, and Rhs_Val
1296 -- contains the value. Otherwise Rhs_Val_Known is set False, and
1297 -- the Rhs_Val is undefined.
1299 function Get_Shift return Node_Id;
1300 -- Function used to get the value of Shift, making sure that it
1301 -- gets duplicated if the function is called more than once.
1307 function Get_Shift return Node_Id is
1309 -- If we used the shift value already, then duplicate it. We
1310 -- set a temporary parent in case actions have to be inserted.
1313 Set_Parent (Shift, N);
1314 return Duplicate_Subexpr_No_Checks (Shift);
1316 -- If first time, use Shift unchanged, and set flag for first use
1324 -- Start of processing for Expand_Bit_Packed_Element_Set
1327 pragma Assert (Is_Bit_Packed_Array (Etype (Prefix (Lhs))));
1329 Obj := Relocate_Node (Prefix (Lhs));
1330 Convert_To_Actual_Subtype (Obj);
1331 Atyp := Etype (Obj);
1332 PAT := Packed_Array_Type (Atyp);
1333 Ctyp := Component_Type (Atyp);
1334 Csiz := UI_To_Int (Component_Size (Atyp));
1336 -- We convert the right hand side to the proper subtype to ensure
1337 -- that an appropriate range check is made (since the normal range
1338 -- check from assignment will be lost in the transformations). This
1339 -- conversion is analyzed immediately so that subsequent processing
1340 -- can work with an analyzed Rhs (and e.g. look at its Etype)
1342 -- If the right-hand side is a string literal, create a temporary for
1343 -- it, constant-folding is not ready to wrap the bit representation
1344 -- of a string literal.
1346 if Nkind (Rhs) = N_String_Literal then
1351 Make_Object_Declaration (Loc,
1352 Defining_Identifier =>
1353 Make_Defining_Identifier (Loc, New_Internal_Name ('T')),
1354 Object_Definition => New_Occurrence_Of (Ctyp, Loc),
1355 Expression => New_Copy_Tree (Rhs));
1357 Insert_Actions (N, New_List (Decl));
1358 Rhs := New_Occurrence_Of (Defining_Identifier (Decl), Loc);
1362 Rhs := Convert_To (Ctyp, Rhs);
1363 Set_Parent (Rhs, N);
1365 -- If we are building the initialization procedure for a packed array,
1366 -- and Initialize_Scalars is enabled, each component assignment is an
1367 -- out-of-range value by design. Compile this value without checks,
1368 -- because a call to the array init_proc must not raise an exception.
1371 and then Initialize_Scalars
1373 Analyze_And_Resolve (Rhs, Ctyp, Suppress => All_Checks);
1375 Analyze_And_Resolve (Rhs, Ctyp);
1378 -- Case of component size 1,2,4 or any component size for the modular
1379 -- case. These are the cases for which we can inline the code.
1381 if Csiz = 1 or else Csiz = 2 or else Csiz = 4
1382 or else (Present (PAT) and then Is_Modular_Integer_Type (PAT))
1384 Setup_Inline_Packed_Array_Reference (Lhs, Atyp, Obj, Cmask, Shift);
1386 -- The statement to be generated is:
1388 -- Obj := atyp!((Obj and Mask1) or (shift_left (rhs, shift)))
1390 -- where mask1 is obtained by shifting Cmask left Shift bits
1391 -- and then complementing the result.
1393 -- the "and Mask1" is omitted if rhs is constant and all 1 bits
1395 -- the "or ..." is omitted if rhs is constant and all 0 bits
1397 -- rhs is converted to the appropriate type
1399 -- The result is converted back to the array type, since
1400 -- otherwise we lose knowledge of the packed nature.
1402 -- Determine if right side is all 0 bits or all 1 bits
1404 if Compile_Time_Known_Value (Rhs) then
1405 Rhs_Val := Expr_Rep_Value (Rhs);
1406 Rhs_Val_Known := True;
1408 -- The following test catches the case of an unchecked conversion
1409 -- of an integer literal. This results from optimizing aggregates
1412 elsif Nkind (Rhs) = N_Unchecked_Type_Conversion
1413 and then Compile_Time_Known_Value (Expression (Rhs))
1415 Rhs_Val := Expr_Rep_Value (Expression (Rhs));
1416 Rhs_Val_Known := True;
1420 Rhs_Val_Known := False;
1423 -- Some special checks for the case where the right hand value
1424 -- is known at compile time. Basically we have to take care of
1425 -- the implicit conversion to the subtype of the component object.
1427 if Rhs_Val_Known then
1429 -- If we have a biased component type then we must manually do
1430 -- the biasing, since we are taking responsibility in this case
1431 -- for constructing the exact bit pattern to be used.
1433 if Has_Biased_Representation (Ctyp) then
1434 Rhs_Val := Rhs_Val - Expr_Rep_Value (Type_Low_Bound (Ctyp));
1437 -- For a negative value, we manually convert the twos complement
1438 -- value to a corresponding unsigned value, so that the proper
1439 -- field width is maintained. If we did not do this, we would
1440 -- get too many leading sign bits later on.
1443 Rhs_Val := 2 ** UI_From_Int (Csiz) + Rhs_Val;
1447 -- Now create copies removing side effects. Note that in some
1448 -- complex cases, this may cause the fact that we have already
1449 -- set a packed array type on Obj to get lost. So we save the
1450 -- type of Obj, and make sure it is reset properly.
1453 T : constant Entity_Id := Etype (Obj);
1455 New_Lhs := Duplicate_Subexpr (Obj, True);
1456 New_Rhs := Duplicate_Subexpr_No_Checks (Obj);
1458 Set_Etype (New_Lhs, T);
1459 Set_Etype (New_Rhs, T);
1462 -- First we deal with the "and"
1464 if not Rhs_Val_Known or else Rhs_Val /= Cmask then
1470 if Compile_Time_Known_Value (Shift) then
1472 Make_Integer_Literal (Loc,
1473 Modulus (Etype (Obj)) - 1 -
1474 (Cmask * (2 ** Expr_Value (Get_Shift))));
1475 Set_Print_In_Hex (Mask1);
1478 Lit := Make_Integer_Literal (Loc, Cmask);
1479 Set_Print_In_Hex (Lit);
1482 Right_Opnd => Make_Shift_Left (Lit, Get_Shift));
1487 Left_Opnd => New_Rhs,
1488 Right_Opnd => Mask1);
1492 -- Then deal with the "or"
1494 if not Rhs_Val_Known or else Rhs_Val /= 0 then
1498 procedure Fixup_Rhs;
1499 -- Adjust Rhs by bias if biased representation for components
1500 -- or remove extraneous high order sign bits if signed.
1502 procedure Fixup_Rhs is
1503 Etyp : constant Entity_Id := Etype (Rhs);
1506 -- For biased case, do the required biasing by simply
1507 -- converting to the biased subtype (the conversion
1508 -- will generate the required bias).
1510 if Has_Biased_Representation (Ctyp) then
1511 Rhs := Convert_To (Ctyp, Rhs);
1513 -- For a signed integer type that is not biased, generate
1514 -- a conversion to unsigned to strip high order sign bits.
1516 elsif Is_Signed_Integer_Type (Ctyp) then
1517 Rhs := Unchecked_Convert_To (RTE (Bits_Id (Csiz)), Rhs);
1520 -- Set Etype, since it can be referenced before the
1521 -- node is completely analyzed.
1523 Set_Etype (Rhs, Etyp);
1525 -- We now need to do an unchecked conversion of the
1526 -- result to the target type, but it is important that
1527 -- this conversion be a right justified conversion and
1528 -- not a left justified conversion.
1530 Rhs := RJ_Unchecked_Convert_To (Etype (Obj), Rhs);
1536 and then Compile_Time_Known_Value (Get_Shift)
1539 Make_Integer_Literal (Loc,
1540 Rhs_Val * (2 ** Expr_Value (Get_Shift)));
1541 Set_Print_In_Hex (Or_Rhs);
1544 -- We have to convert the right hand side to Etype (Obj).
1545 -- A special case arises if what we have now is a Val
1546 -- attribute reference whose expression type is Etype (Obj).
1547 -- This happens for assignments of fields from the same
1548 -- array. In this case we get the required right hand side
1549 -- by simply removing the inner attribute reference.
1551 if Nkind (Rhs) = N_Attribute_Reference
1552 and then Attribute_Name (Rhs) = Name_Val
1553 and then Etype (First (Expressions (Rhs))) = Etype (Obj)
1555 Rhs := Relocate_Node (First (Expressions (Rhs)));
1558 -- If the value of the right hand side is a known integer
1559 -- value, then just replace it by an untyped constant,
1560 -- which will be properly retyped when we analyze and
1561 -- resolve the expression.
1563 elsif Rhs_Val_Known then
1565 -- Note that Rhs_Val has already been normalized to
1566 -- be an unsigned value with the proper number of bits.
1569 Make_Integer_Literal (Loc, Rhs_Val);
1571 -- Otherwise we need an unchecked conversion
1577 Or_Rhs := Make_Shift_Left (Rhs, Get_Shift);
1580 if Nkind (New_Rhs) = N_Op_And then
1581 Set_Paren_Count (New_Rhs, 1);
1586 Left_Opnd => New_Rhs,
1587 Right_Opnd => Or_Rhs);
1591 -- Now do the rewrite
1594 Make_Assignment_Statement (Loc,
1597 Unchecked_Convert_To (Etype (New_Lhs), New_Rhs)));
1598 Set_Assignment_OK (Name (N), Ass_OK);
1600 -- All other component sizes for non-modular case
1605 -- Set_nn (Arr'address, Subscr, Bits_nn!(Rhs))
1607 -- where Subscr is the computed linear subscript
1610 Bits_nn : constant Entity_Id := RTE (Bits_Id (Csiz));
1616 if No (Bits_nn) then
1618 -- Error, most likely High_Integrity_Mode restriction
1623 -- Acquire proper Set entity. We use the aligned or unaligned
1624 -- case as appropriate.
1626 if Known_Aligned_Enough (Obj, Csiz) then
1627 Set_nn := RTE (Set_Id (Csiz));
1629 Set_nn := RTE (SetU_Id (Csiz));
1632 -- Now generate the set reference
1634 Obj := Relocate_Node (Prefix (Lhs));
1635 Convert_To_Actual_Subtype (Obj);
1636 Atyp := Etype (Obj);
1637 Compute_Linear_Subscript (Atyp, Lhs, Subscr);
1639 -- Below we must make the assumption that Obj is
1640 -- at least byte aligned, since otherwise its address
1641 -- cannot be taken. The assumption holds since the
1642 -- only arrays that can be misaligned are small packed
1643 -- arrays which are implemented as a modular type, and
1644 -- that is not the case here.
1647 Make_Procedure_Call_Statement (Loc,
1648 Name => New_Occurrence_Of (Set_nn, Loc),
1649 Parameter_Associations => New_List (
1650 Make_Attribute_Reference (Loc,
1652 Attribute_Name => Name_Address),
1654 Unchecked_Convert_To (Bits_nn,
1655 Convert_To (Ctyp, Rhs)))));
1660 Analyze (N, Suppress => All_Checks);
1661 end Expand_Bit_Packed_Element_Set;
1663 -------------------------------------
1664 -- Expand_Packed_Address_Reference --
1665 -------------------------------------
1667 procedure Expand_Packed_Address_Reference (N : Node_Id) is
1668 Loc : constant Source_Ptr := Sloc (N);
1680 -- We build up an expression serially that has the form
1682 -- outer_object'Address
1683 -- + (linear-subscript * component_size for each array reference
1684 -- + field'Bit_Position for each record field
1686 -- + ...) / Storage_Unit;
1688 -- Some additional conversions are required to deal with the addition
1689 -- operation, which is not normally visible to generated code.
1692 Ploc := Sloc (Pref);
1694 if Nkind (Pref) = N_Indexed_Component then
1695 Convert_To_Actual_Subtype (Prefix (Pref));
1696 Atyp := Etype (Prefix (Pref));
1697 Compute_Linear_Subscript (Atyp, Pref, Subscr);
1700 Make_Op_Multiply (Ploc,
1701 Left_Opnd => Subscr,
1703 Make_Attribute_Reference (Ploc,
1704 Prefix => New_Occurrence_Of (Atyp, Ploc),
1705 Attribute_Name => Name_Component_Size));
1707 elsif Nkind (Pref) = N_Selected_Component then
1709 Make_Attribute_Reference (Ploc,
1710 Prefix => Selector_Name (Pref),
1711 Attribute_Name => Name_Bit_Position);
1717 Term := Convert_To (RTE (RE_Integer_Address), Term);
1726 Right_Opnd => Term);
1729 Pref := Prefix (Pref);
1733 Unchecked_Convert_To (RTE (RE_Address),
1736 Unchecked_Convert_To (RTE (RE_Integer_Address),
1737 Make_Attribute_Reference (Loc,
1739 Attribute_Name => Name_Address)),
1742 Make_Op_Divide (Loc,
1745 Make_Integer_Literal (Loc, System_Storage_Unit)))));
1747 Analyze_And_Resolve (N, RTE (RE_Address));
1748 end Expand_Packed_Address_Reference;
1750 ------------------------------------
1751 -- Expand_Packed_Boolean_Operator --
1752 ------------------------------------
1754 -- This routine expands "a op b" for the packed cases
1756 procedure Expand_Packed_Boolean_Operator (N : Node_Id) is
1757 Loc : constant Source_Ptr := Sloc (N);
1758 Typ : constant Entity_Id := Etype (N);
1759 L : constant Node_Id := Relocate_Node (Left_Opnd (N));
1760 R : constant Node_Id := Relocate_Node (Right_Opnd (N));
1767 Convert_To_Actual_Subtype (L);
1768 Convert_To_Actual_Subtype (R);
1770 Ensure_Defined (Etype (L), N);
1771 Ensure_Defined (Etype (R), N);
1773 Apply_Length_Check (R, Etype (L));
1778 -- Deal with silly case of XOR where the subcomponent has a range
1779 -- True .. True where an exception must be raised.
1781 if Nkind (N) = N_Op_Xor then
1782 Silly_Boolean_Array_Xor_Test (N, Rtyp);
1785 -- Now that that silliness is taken care of, get packed array type
1787 Convert_To_PAT_Type (L);
1788 Convert_To_PAT_Type (R);
1792 -- For the modular case, we expand a op b into
1794 -- rtyp!(pat!(a) op pat!(b))
1796 -- where rtyp is the Etype of the left operand. Note that we do not
1797 -- convert to the base type, since this would be unconstrained, and
1798 -- hence not have a corresponding packed array type set.
1800 -- Note that both operands must be modular for this code to be used
1802 if Is_Modular_Integer_Type (PAT)
1804 Is_Modular_Integer_Type (Etype (R))
1810 if Nkind (N) = N_Op_And then
1811 P := Make_Op_And (Loc, L, R);
1813 elsif Nkind (N) = N_Op_Or then
1814 P := Make_Op_Or (Loc, L, R);
1816 else -- Nkind (N) = N_Op_Xor
1817 P := Make_Op_Xor (Loc, L, R);
1820 Rewrite (N, Unchecked_Convert_To (Ltyp, P));
1823 -- For the array case, we insert the actions
1827 -- System.Bit_Ops.Bit_And/Or/Xor
1829 -- Ltype'Length * Ltype'Component_Size;
1831 -- Rtype'Length * Rtype'Component_Size
1834 -- where Left and Right are the Packed_Bytes{1,2,4} operands and
1835 -- the second argument and fourth arguments are the lengths of the
1836 -- operands in bits. Then we replace the expression by a reference
1839 -- Note that if we are mixing a modular and array operand, everything
1840 -- works fine, since we ensure that the modular representation has the
1841 -- same physical layout as the array representation (that's what the
1842 -- left justified modular stuff in the big-endian case is about).
1846 Result_Ent : constant Entity_Id :=
1847 Make_Defining_Identifier (Loc,
1848 Chars => New_Internal_Name ('T'));
1853 if Nkind (N) = N_Op_And then
1856 elsif Nkind (N) = N_Op_Or then
1859 else -- Nkind (N) = N_Op_Xor
1863 Insert_Actions (N, New_List (
1865 Make_Object_Declaration (Loc,
1866 Defining_Identifier => Result_Ent,
1867 Object_Definition => New_Occurrence_Of (Ltyp, Loc)),
1869 Make_Procedure_Call_Statement (Loc,
1870 Name => New_Occurrence_Of (RTE (E_Id), Loc),
1871 Parameter_Associations => New_List (
1873 Make_Byte_Aligned_Attribute_Reference (Loc,
1875 Attribute_Name => Name_Address),
1877 Make_Op_Multiply (Loc,
1879 Make_Attribute_Reference (Loc,
1882 (Etype (First_Index (Ltyp)), Loc),
1883 Attribute_Name => Name_Range_Length),
1886 Make_Integer_Literal (Loc, Component_Size (Ltyp))),
1888 Make_Byte_Aligned_Attribute_Reference (Loc,
1890 Attribute_Name => Name_Address),
1892 Make_Op_Multiply (Loc,
1894 Make_Attribute_Reference (Loc,
1897 (Etype (First_Index (Rtyp)), Loc),
1898 Attribute_Name => Name_Range_Length),
1901 Make_Integer_Literal (Loc, Component_Size (Rtyp))),
1903 Make_Byte_Aligned_Attribute_Reference (Loc,
1904 Prefix => New_Occurrence_Of (Result_Ent, Loc),
1905 Attribute_Name => Name_Address)))));
1908 New_Occurrence_Of (Result_Ent, Loc));
1912 Analyze_And_Resolve (N, Typ, Suppress => All_Checks);
1913 end Expand_Packed_Boolean_Operator;
1915 -------------------------------------
1916 -- Expand_Packed_Element_Reference --
1917 -------------------------------------
1919 procedure Expand_Packed_Element_Reference (N : Node_Id) is
1920 Loc : constant Source_Ptr := Sloc (N);
1932 -- If not bit packed, we have the enumeration case, which is easily
1933 -- dealt with (just adjust the subscripts of the indexed component)
1935 -- Note: this leaves the result as an indexed component, which is
1936 -- still a variable, so can be used in the assignment case, as is
1937 -- required in the enumeration case.
1939 if not Is_Bit_Packed_Array (Etype (Prefix (N))) then
1940 Setup_Enumeration_Packed_Array_Reference (N);
1944 -- Remaining processing is for the bit-packed case
1946 Obj := Relocate_Node (Prefix (N));
1947 Convert_To_Actual_Subtype (Obj);
1948 Atyp := Etype (Obj);
1949 PAT := Packed_Array_Type (Atyp);
1950 Ctyp := Component_Type (Atyp);
1951 Csiz := UI_To_Int (Component_Size (Atyp));
1953 -- Case of component size 1,2,4 or any component size for the modular
1954 -- case. These are the cases for which we can inline the code.
1956 if Csiz = 1 or else Csiz = 2 or else Csiz = 4
1957 or else (Present (PAT) and then Is_Modular_Integer_Type (PAT))
1959 Setup_Inline_Packed_Array_Reference (N, Atyp, Obj, Cmask, Shift);
1960 Lit := Make_Integer_Literal (Loc, Cmask);
1961 Set_Print_In_Hex (Lit);
1963 -- We generate a shift right to position the field, followed by a
1964 -- masking operation to extract the bit field, and we finally do an
1965 -- unchecked conversion to convert the result to the required target.
1967 -- Note that the unchecked conversion automatically deals with the
1968 -- bias if we are dealing with a biased representation. What will
1969 -- happen is that we temporarily generate the biased representation,
1970 -- but almost immediately that will be converted to the original
1971 -- unbiased component type, and the bias will disappear.
1975 Left_Opnd => Make_Shift_Right (Obj, Shift),
1978 -- We needed to analyze this before we do the unchecked convert
1979 -- below, but we need it temporarily attached to the tree for
1980 -- this analysis (hence the temporary Set_Parent call).
1982 Set_Parent (Arg, Parent (N));
1983 Analyze_And_Resolve (Arg);
1986 RJ_Unchecked_Convert_To (Ctyp, Arg));
1988 -- All other component sizes for non-modular case
1993 -- Component_Type!(Get_nn (Arr'address, Subscr))
1995 -- where Subscr is the computed linear subscript
2002 -- Acquire proper Get entity. We use the aligned or unaligned
2003 -- case as appropriate.
2005 if Known_Aligned_Enough (Obj, Csiz) then
2006 Get_nn := RTE (Get_Id (Csiz));
2008 Get_nn := RTE (GetU_Id (Csiz));
2011 -- Now generate the get reference
2013 Compute_Linear_Subscript (Atyp, N, Subscr);
2015 -- Below we make the assumption that Obj is at least byte
2016 -- aligned, since otherwise its address cannot be taken.
2017 -- The assumption holds since the only arrays that can be
2018 -- misaligned are small packed arrays which are implemented
2019 -- as a modular type, and that is not the case here.
2022 Unchecked_Convert_To (Ctyp,
2023 Make_Function_Call (Loc,
2024 Name => New_Occurrence_Of (Get_nn, Loc),
2025 Parameter_Associations => New_List (
2026 Make_Attribute_Reference (Loc,
2028 Attribute_Name => Name_Address),
2033 Analyze_And_Resolve (N, Ctyp, Suppress => All_Checks);
2035 end Expand_Packed_Element_Reference;
2037 ----------------------
2038 -- Expand_Packed_Eq --
2039 ----------------------
2041 -- Handles expansion of "=" on packed array types
2043 procedure Expand_Packed_Eq (N : Node_Id) is
2044 Loc : constant Source_Ptr := Sloc (N);
2045 L : constant Node_Id := Relocate_Node (Left_Opnd (N));
2046 R : constant Node_Id := Relocate_Node (Right_Opnd (N));
2056 Convert_To_Actual_Subtype (L);
2057 Convert_To_Actual_Subtype (R);
2058 Ltyp := Underlying_Type (Etype (L));
2059 Rtyp := Underlying_Type (Etype (R));
2061 Convert_To_PAT_Type (L);
2062 Convert_To_PAT_Type (R);
2066 Make_Op_Multiply (Loc,
2068 Make_Attribute_Reference (Loc,
2069 Prefix => New_Occurrence_Of (Ltyp, Loc),
2070 Attribute_Name => Name_Length),
2072 Make_Integer_Literal (Loc, Component_Size (Ltyp)));
2075 Make_Op_Multiply (Loc,
2077 Make_Attribute_Reference (Loc,
2078 Prefix => New_Occurrence_Of (Rtyp, Loc),
2079 Attribute_Name => Name_Length),
2081 Make_Integer_Literal (Loc, Component_Size (Rtyp)));
2083 -- For the modular case, we transform the comparison to:
2085 -- Ltyp'Length = Rtyp'Length and then PAT!(L) = PAT!(R)
2087 -- where PAT is the packed array type. This works fine, since in the
2088 -- modular case we guarantee that the unused bits are always zeroes.
2089 -- We do have to compare the lengths because we could be comparing
2090 -- two different subtypes of the same base type.
2092 if Is_Modular_Integer_Type (PAT) then
2097 Left_Opnd => LLexpr,
2098 Right_Opnd => RLexpr),
2105 -- For the non-modular case, we call a runtime routine
2107 -- System.Bit_Ops.Bit_Eq
2108 -- (L'Address, L_Length, R'Address, R_Length)
2110 -- where PAT is the packed array type, and the lengths are the lengths
2111 -- in bits of the original packed arrays. This routine takes care of
2112 -- not comparing the unused bits in the last byte.
2116 Make_Function_Call (Loc,
2117 Name => New_Occurrence_Of (RTE (RE_Bit_Eq), Loc),
2118 Parameter_Associations => New_List (
2119 Make_Byte_Aligned_Attribute_Reference (Loc,
2121 Attribute_Name => Name_Address),
2125 Make_Byte_Aligned_Attribute_Reference (Loc,
2127 Attribute_Name => Name_Address),
2132 Analyze_And_Resolve (N, Standard_Boolean, Suppress => All_Checks);
2133 end Expand_Packed_Eq;
2135 -----------------------
2136 -- Expand_Packed_Not --
2137 -----------------------
2139 -- Handles expansion of "not" on packed array types
2141 procedure Expand_Packed_Not (N : Node_Id) is
2142 Loc : constant Source_Ptr := Sloc (N);
2143 Typ : constant Entity_Id := Etype (N);
2144 Opnd : constant Node_Id := Relocate_Node (Right_Opnd (N));
2151 Convert_To_Actual_Subtype (Opnd);
2152 Rtyp := Etype (Opnd);
2154 -- Deal with silly False..False and True..True subtype case
2156 Silly_Boolean_Array_Not_Test (N, Rtyp);
2158 -- Now that the silliness is taken care of, get packed array type
2160 Convert_To_PAT_Type (Opnd);
2161 PAT := Etype (Opnd);
2163 -- For the case where the packed array type is a modular type,
2164 -- not A expands simply into:
2166 -- rtyp!(PAT!(A) xor mask)
2168 -- where PAT is the packed array type, and mask is a mask of all
2169 -- one bits of length equal to the size of this packed type and
2170 -- rtyp is the actual subtype of the operand
2172 Lit := Make_Integer_Literal (Loc, 2 ** RM_Size (PAT) - 1);
2173 Set_Print_In_Hex (Lit);
2175 if not Is_Array_Type (PAT) then
2177 Unchecked_Convert_To (Rtyp,
2180 Right_Opnd => Lit)));
2182 -- For the array case, we insert the actions
2186 -- System.Bit_Ops.Bit_Not
2188 -- Typ'Length * Typ'Component_Size;
2191 -- where Opnd is the Packed_Bytes{1,2,4} operand and the second
2192 -- argument is the length of the operand in bits. Then we replace
2193 -- the expression by a reference to Result.
2197 Result_Ent : constant Entity_Id :=
2198 Make_Defining_Identifier (Loc,
2199 Chars => New_Internal_Name ('T'));
2202 Insert_Actions (N, New_List (
2204 Make_Object_Declaration (Loc,
2205 Defining_Identifier => Result_Ent,
2206 Object_Definition => New_Occurrence_Of (Rtyp, Loc)),
2208 Make_Procedure_Call_Statement (Loc,
2209 Name => New_Occurrence_Of (RTE (RE_Bit_Not), Loc),
2210 Parameter_Associations => New_List (
2212 Make_Byte_Aligned_Attribute_Reference (Loc,
2214 Attribute_Name => Name_Address),
2216 Make_Op_Multiply (Loc,
2218 Make_Attribute_Reference (Loc,
2221 (Etype (First_Index (Rtyp)), Loc),
2222 Attribute_Name => Name_Range_Length),
2225 Make_Integer_Literal (Loc, Component_Size (Rtyp))),
2227 Make_Byte_Aligned_Attribute_Reference (Loc,
2228 Prefix => New_Occurrence_Of (Result_Ent, Loc),
2229 Attribute_Name => Name_Address)))));
2232 New_Occurrence_Of (Result_Ent, Loc));
2236 Analyze_And_Resolve (N, Typ, Suppress => All_Checks);
2238 end Expand_Packed_Not;
2240 -------------------------------------
2241 -- Involves_Packed_Array_Reference --
2242 -------------------------------------
2244 function Involves_Packed_Array_Reference (N : Node_Id) return Boolean is
2246 if Nkind (N) = N_Indexed_Component
2247 and then Is_Bit_Packed_Array (Etype (Prefix (N)))
2251 elsif Nkind (N) = N_Selected_Component then
2252 return Involves_Packed_Array_Reference (Prefix (N));
2257 end Involves_Packed_Array_Reference;
2259 --------------------------
2260 -- Known_Aligned_Enough --
2261 --------------------------
2263 function Known_Aligned_Enough (Obj : Node_Id; Csiz : Nat) return Boolean is
2264 Typ : constant Entity_Id := Etype (Obj);
2266 function In_Partially_Packed_Record (Comp : Entity_Id) return Boolean;
2267 -- If the component is in a record that contains previous packed
2268 -- components, consider it unaligned because the back-end might
2269 -- choose to pack the rest of the record. Lead to less efficient code,
2270 -- but safer vis-a-vis of back-end choices.
2272 --------------------------------
2273 -- In_Partially_Packed_Record --
2274 --------------------------------
2276 function In_Partially_Packed_Record (Comp : Entity_Id) return Boolean is
2277 Rec_Type : constant Entity_Id := Scope (Comp);
2278 Prev_Comp : Entity_Id;
2281 Prev_Comp := First_Entity (Rec_Type);
2282 while Present (Prev_Comp) loop
2283 if Is_Packed (Etype (Prev_Comp)) then
2286 elsif Prev_Comp = Comp then
2290 Next_Entity (Prev_Comp);
2294 end In_Partially_Packed_Record;
2296 -- Start of processing for Known_Aligned_Enough
2299 -- Odd bit sizes don't need alignment anyway
2301 if Csiz mod 2 = 1 then
2304 -- If we have a specified alignment, see if it is sufficient, if not
2305 -- then we can't possibly be aligned enough in any case.
2307 elsif Known_Alignment (Etype (Obj)) then
2308 -- Alignment required is 4 if size is a multiple of 4, and
2309 -- 2 otherwise (e.g. 12 bits requires 4, 10 bits requires 2)
2311 if Alignment (Etype (Obj)) < 4 - (Csiz mod 4) then
2316 -- OK, alignment should be sufficient, if object is aligned
2318 -- If object is strictly aligned, then it is definitely aligned
2320 if Strict_Alignment (Typ) then
2323 -- Case of subscripted array reference
2325 elsif Nkind (Obj) = N_Indexed_Component then
2327 -- If we have a pointer to an array, then this is definitely
2328 -- aligned, because pointers always point to aligned versions.
2330 if Is_Access_Type (Etype (Prefix (Obj))) then
2333 -- Otherwise, go look at the prefix
2336 return Known_Aligned_Enough (Prefix (Obj), Csiz);
2339 -- Case of record field
2341 elsif Nkind (Obj) = N_Selected_Component then
2343 -- What is significant here is whether the record type is packed
2345 if Is_Record_Type (Etype (Prefix (Obj)))
2346 and then Is_Packed (Etype (Prefix (Obj)))
2350 -- Or the component has a component clause which might cause
2351 -- the component to become unaligned (we can't tell if the
2352 -- backend is doing alignment computations).
2354 elsif Present (Component_Clause (Entity (Selector_Name (Obj)))) then
2357 elsif In_Partially_Packed_Record (Entity (Selector_Name (Obj))) then
2360 -- In all other cases, go look at prefix
2363 return Known_Aligned_Enough (Prefix (Obj), Csiz);
2366 elsif Nkind (Obj) = N_Type_Conversion then
2367 return Known_Aligned_Enough (Expression (Obj), Csiz);
2369 -- For a formal parameter, it is safer to assume that it is not
2370 -- aligned, because the formal may be unconstrained while the actual
2371 -- is constrained. In this situation, a small constrained packed
2372 -- array, represented in modular form, may be unaligned.
2374 elsif Is_Entity_Name (Obj) then
2375 return not Is_Formal (Entity (Obj));
2378 -- If none of the above, must be aligned
2381 end Known_Aligned_Enough;
2383 ---------------------
2384 -- Make_Shift_Left --
2385 ---------------------
2387 function Make_Shift_Left (N : Node_Id; S : Node_Id) return Node_Id is
2391 if Compile_Time_Known_Value (S) and then Expr_Value (S) = 0 then
2395 Make_Op_Shift_Left (Sloc (N),
2398 Set_Shift_Count_OK (Nod, True);
2401 end Make_Shift_Left;
2403 ----------------------
2404 -- Make_Shift_Right --
2405 ----------------------
2407 function Make_Shift_Right (N : Node_Id; S : Node_Id) return Node_Id is
2411 if Compile_Time_Known_Value (S) and then Expr_Value (S) = 0 then
2415 Make_Op_Shift_Right (Sloc (N),
2418 Set_Shift_Count_OK (Nod, True);
2421 end Make_Shift_Right;
2423 -----------------------------
2424 -- RJ_Unchecked_Convert_To --
2425 -----------------------------
2427 function RJ_Unchecked_Convert_To
2429 Expr : Node_Id) return Node_Id
2431 Source_Typ : constant Entity_Id := Etype (Expr);
2432 Target_Typ : constant Entity_Id := Typ;
2434 Src : Node_Id := Expr;
2440 Source_Siz := UI_To_Int (RM_Size (Source_Typ));
2441 Target_Siz := UI_To_Int (RM_Size (Target_Typ));
2443 -- First step, if the source type is not a discrete type, then we
2444 -- first convert to a modular type of the source length, since
2445 -- otherwise, on a big-endian machine, we get left-justification.
2446 -- We do it for little-endian machines as well, because there might
2447 -- be junk bits that are not cleared if the type is not numeric.
2449 if Source_Siz /= Target_Siz
2450 and then not Is_Discrete_Type (Source_Typ)
2452 Src := Unchecked_Convert_To (RTE (Bits_Id (Source_Siz)), Src);
2455 -- In the big endian case, if the lengths of the two types differ,
2456 -- then we must worry about possible left justification in the
2457 -- conversion, and avoiding that is what this is all about.
2459 if Bytes_Big_Endian and then Source_Siz /= Target_Siz then
2461 -- Next step. If the target is not a discrete type, then we first
2462 -- convert to a modular type of the target length, since
2463 -- otherwise, on a big-endian machine, we get left-justification.
2465 if not Is_Discrete_Type (Target_Typ) then
2466 Src := Unchecked_Convert_To (RTE (Bits_Id (Target_Siz)), Src);
2470 -- And now we can do the final conversion to the target type
2472 return Unchecked_Convert_To (Target_Typ, Src);
2473 end RJ_Unchecked_Convert_To;
2475 ----------------------------------------------
2476 -- Setup_Enumeration_Packed_Array_Reference --
2477 ----------------------------------------------
2479 -- All we have to do here is to find the subscripts that correspond
2480 -- to the index positions that have non-standard enumeration types
2481 -- and insert a Pos attribute to get the proper subscript value.
2483 -- Finally the prefix must be uncheck converted to the corresponding
2484 -- packed array type.
2486 -- Note that the component type is unchanged, so we do not need to
2487 -- fiddle with the types (Gigi always automatically takes the packed
2488 -- array type if it is set, as it will be in this case).
2490 procedure Setup_Enumeration_Packed_Array_Reference (N : Node_Id) is
2491 Pfx : constant Node_Id := Prefix (N);
2492 Typ : constant Entity_Id := Etype (N);
2493 Exprs : constant List_Id := Expressions (N);
2497 -- If the array is unconstrained, then we replace the array
2498 -- reference with its actual subtype. This actual subtype will
2499 -- have a packed array type with appropriate bounds.
2501 if not Is_Constrained (Packed_Array_Type (Etype (Pfx))) then
2502 Convert_To_Actual_Subtype (Pfx);
2505 Expr := First (Exprs);
2506 while Present (Expr) loop
2508 Loc : constant Source_Ptr := Sloc (Expr);
2509 Expr_Typ : constant Entity_Id := Etype (Expr);
2512 if Is_Enumeration_Type (Expr_Typ)
2513 and then Has_Non_Standard_Rep (Expr_Typ)
2516 Make_Attribute_Reference (Loc,
2517 Prefix => New_Occurrence_Of (Expr_Typ, Loc),
2518 Attribute_Name => Name_Pos,
2519 Expressions => New_List (Relocate_Node (Expr))));
2520 Analyze_And_Resolve (Expr, Standard_Natural);
2528 Make_Indexed_Component (Sloc (N),
2530 Unchecked_Convert_To (Packed_Array_Type (Etype (Pfx)), Pfx),
2531 Expressions => Exprs));
2533 Analyze_And_Resolve (N, Typ);
2535 end Setup_Enumeration_Packed_Array_Reference;
2537 -----------------------------------------
2538 -- Setup_Inline_Packed_Array_Reference --
2539 -----------------------------------------
2541 procedure Setup_Inline_Packed_Array_Reference
2544 Obj : in out Node_Id;
2546 Shift : out Node_Id)
2548 Loc : constant Source_Ptr := Sloc (N);
2555 Csiz := Component_Size (Atyp);
2557 Convert_To_PAT_Type (Obj);
2560 Cmask := 2 ** Csiz - 1;
2562 if Is_Array_Type (PAT) then
2563 Otyp := Component_Type (PAT);
2564 Osiz := Component_Size (PAT);
2569 -- In the case where the PAT is a modular type, we want the actual
2570 -- size in bits of the modular value we use. This is neither the
2571 -- Object_Size nor the Value_Size, either of which may have been
2572 -- reset to strange values, but rather the minimum size. Note that
2573 -- since this is a modular type with full range, the issue of
2574 -- biased representation does not arise.
2576 Osiz := UI_From_Int (Minimum_Size (Otyp));
2579 Compute_Linear_Subscript (Atyp, N, Shift);
2581 -- If the component size is not 1, then the subscript must be
2582 -- multiplied by the component size to get the shift count.
2586 Make_Op_Multiply (Loc,
2587 Left_Opnd => Make_Integer_Literal (Loc, Csiz),
2588 Right_Opnd => Shift);
2591 -- If we have the array case, then this shift count must be broken
2592 -- down into a byte subscript, and a shift within the byte.
2594 if Is_Array_Type (PAT) then
2597 New_Shift : Node_Id;
2600 -- We must analyze shift, since we will duplicate it
2602 Set_Parent (Shift, N);
2604 (Shift, Standard_Integer, Suppress => All_Checks);
2606 -- The shift count within the word is
2611 Left_Opnd => Duplicate_Subexpr (Shift),
2612 Right_Opnd => Make_Integer_Literal (Loc, Osiz));
2614 -- The subscript to be used on the PAT array is
2618 Make_Indexed_Component (Loc,
2620 Expressions => New_List (
2621 Make_Op_Divide (Loc,
2622 Left_Opnd => Duplicate_Subexpr (Shift),
2623 Right_Opnd => Make_Integer_Literal (Loc, Osiz))));
2628 -- For the modular integer case, the object to be manipulated is
2629 -- the entire array, so Obj is unchanged. Note that we will reset
2630 -- its type to PAT before returning to the caller.
2636 -- The one remaining step is to modify the shift count for the
2637 -- big-endian case. Consider the following example in a byte:
2639 -- xxxxxxxx bits of byte
2640 -- vvvvvvvv bits of value
2641 -- 33221100 little-endian numbering
2642 -- 00112233 big-endian numbering
2644 -- Here we have the case of 2-bit fields
2646 -- For the little-endian case, we already have the proper shift
2647 -- count set, e.g. for element 2, the shift count is 2*2 = 4.
2649 -- For the big endian case, we have to adjust the shift count,
2650 -- computing it as (N - F) - shift, where N is the number of bits
2651 -- in an element of the array used to implement the packed array,
2652 -- F is the number of bits in a source level array element, and
2653 -- shift is the count so far computed.
2655 if Bytes_Big_Endian then
2657 Make_Op_Subtract (Loc,
2658 Left_Opnd => Make_Integer_Literal (Loc, Osiz - Csiz),
2659 Right_Opnd => Shift);
2662 Set_Parent (Shift, N);
2663 Set_Parent (Obj, N);
2664 Analyze_And_Resolve (Obj, Otyp, Suppress => All_Checks);
2665 Analyze_And_Resolve (Shift, Standard_Integer, Suppress => All_Checks);
2667 -- Make sure final type of object is the appropriate packed type
2669 Set_Etype (Obj, Otyp);
2671 end Setup_Inline_Packed_Array_Reference;