1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
10 -- Copyright (C) 1992-2002 Free Software Foundation, Inc. --
12 -- GNAT is free software; you can redistribute it and/or modify it under --
13 -- terms of the GNU General Public License as published by the Free Soft- --
14 -- ware Foundation; either version 2, or (at your option) any later ver- --
15 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
16 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
17 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
18 -- for more details. You should have received a copy of the GNU General --
19 -- Public License distributed with GNAT; see file COPYING. If not, write --
20 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
21 -- MA 02111-1307, USA. --
23 -- GNAT was originally developed by the GNAT team at New York University. --
24 -- Extensive contributions were provided by Ada Core Technologies Inc. --
26 ------------------------------------------------------------------------------
28 with Atree; use Atree;
29 with Checks; use Checks;
30 with Einfo; use Einfo;
31 with Exp_Dbug; use Exp_Dbug;
32 with Exp_Util; use Exp_Util;
33 with Nlists; use Nlists;
34 with Nmake; use Nmake;
36 with Rtsfind; use Rtsfind;
38 with Sem_Ch8; use Sem_Ch8;
39 with Sem_Ch13; use Sem_Ch13;
40 with Sem_Eval; use Sem_Eval;
41 with Sem_Res; use Sem_Res;
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 Exp_Pakd is
53 ---------------------------
54 -- Endian Considerations --
55 ---------------------------
57 -- As described in the specification, bit numbering in a packed array
58 -- is consistent with bit numbering in a record representation clause,
59 -- and hence dependent on the endianness of the machine:
61 -- For little-endian machines, element zero is at the right hand end
62 -- (low order end) of a bit field.
64 -- For big-endian machines, element zero is at the left hand end
65 -- (high order end) of a bit field.
67 -- The shifts that are used to right justify a field therefore differ
68 -- in the two cases. For the little-endian case, we can simply use the
69 -- bit number (i.e. the element number * element size) as the count for
70 -- a right shift. For the big-endian case, we have to subtract the shift
71 -- count from an appropriate constant to use in the right shift. We use
72 -- rotates instead of shifts (which is necessary in the store case to
73 -- preserve other fields), and we expect that the backend will be able
74 -- to change the right rotate into a left rotate, avoiding the subtract,
75 -- if the architecture provides such an instruction.
77 ----------------------------------------------
78 -- Entity Tables for Packed Access Routines --
79 ----------------------------------------------
81 -- For the cases of component size = 3,5-7,9-15,17-31,33-63 we call
82 -- library routines. This table is used to obtain the entity for the
85 type E_Array is array (Int range 01 .. 63) of RE_Id;
87 -- Array of Bits_nn entities. Note that we do not use library routines
88 -- for the 8-bit and 16-bit cases, but we still fill in the table, using
89 -- entries from System.Unsigned, because we also use this table for
90 -- certain special unchecked conversions in the big-endian case.
92 Bits_Id : constant E_Array :=
108 16 => RE_Unsigned_16,
124 32 => RE_Unsigned_32,
157 -- Array of Get routine entities. These are used to obtain an element
158 -- from a packed array. The N'th entry is used to obtain elements from
159 -- a packed array whose component size is N. RE_Null is used as a null
160 -- entry, for the cases where a library routine is not used.
162 Get_Id : constant E_Array :=
227 -- Array of Get routine entities to be used in the case where the packed
228 -- array is itself a component of a packed structure, and therefore may
229 -- not be fully aligned. This only affects the even sizes, since for the
230 -- odd sizes, we do not get any fixed alignment in any case.
232 GetU_Id : constant E_Array :=
297 -- Array of Set routine entities. These are used to assign an element
298 -- of a packed array. The N'th entry is used to assign elements for
299 -- a packed array whose component size is N. RE_Null is used as a null
300 -- entry, for the cases where a library routine is not used.
367 -- Array of Set routine entities to be used in the case where the packed
368 -- array is itself a component of a packed structure, and therefore may
369 -- not be fully aligned. This only affects the even sizes, since for the
370 -- odd sizes, we do not get any fixed alignment in any case.
437 -----------------------
438 -- Local Subprograms --
439 -----------------------
441 procedure Compute_Linear_Subscript
444 Subscr : out Node_Id);
445 -- Given a constrained array type Atyp, and an indexed component node
446 -- N referencing an array object of this type, build an expression of
447 -- type Standard.Integer representing the zero-based linear subscript
448 -- value. This expression includes any required range checks.
450 procedure Convert_To_PAT_Type (Aexp : Node_Id);
451 -- Given an expression of a packed array type, builds a corresponding
452 -- expression whose type is the implementation type used to represent
453 -- the packed array. Aexp is analyzed and resolved on entry and on exit.
455 function Known_Aligned_Enough (Obj : Node_Id; Csiz : Nat) return Boolean;
456 -- There are two versions of the Set routines, the ones used when the
457 -- object is known to be sufficiently well aligned given the number of
458 -- bits, and the ones used when the object is not known to be aligned.
459 -- This routine is used to determine which set to use. Obj is a reference
460 -- to the object, and Csiz is the component size of the packed array.
461 -- True is returned if the alignment of object is known to be sufficient,
462 -- defined as 1 for odd bit sizes, 4 for bit sizes divisible by 4, and
465 function Make_Shift_Left (N : Node_Id; S : Node_Id) return Node_Id;
466 -- Build a left shift node, checking for the case of a shift count of zero
468 function Make_Shift_Right (N : Node_Id; S : Node_Id) return Node_Id;
469 -- Build a right shift node, checking for the case of a shift count of zero
471 function RJ_Unchecked_Convert_To
475 -- The packed array code does unchecked conversions which in some cases
476 -- may involve non-discrete types with differing sizes. The semantics of
477 -- such conversions is potentially endian dependent, and the effect we
478 -- want here for such a conversion is to do the conversion in size as
479 -- though numeric items are involved, and we extend or truncate on the
480 -- left side. This happens naturally in the little-endian case, but in
481 -- the big endian case we can get left justification, when what we want
482 -- is right justification. This routine does the unchecked conversion in
483 -- a stepwise manner to ensure that it gives the expected result. Hence
484 -- the name (RJ = Right justified). The parameters Typ and Expr are as
485 -- for the case of a normal Unchecked_Convert_To call.
487 procedure Setup_Enumeration_Packed_Array_Reference (N : Node_Id);
488 -- This routine is called in the Get and Set case for arrays that are
489 -- packed but not bit-packed, meaning that they have at least one
490 -- subscript that is of an enumeration type with a non-standard
491 -- representation. This routine modifies the given node to properly
492 -- reference the corresponding packed array type.
494 procedure Setup_Inline_Packed_Array_Reference
497 Obj : in out Node_Id;
499 Shift : out Node_Id);
500 -- This procedure performs common processing on the N_Indexed_Component
501 -- parameter given as N, whose prefix is a reference to a packed array.
502 -- This is used for the get and set when the component size is 1,2,4
503 -- or for other component sizes when the packed array type is a modular
504 -- type (i.e. the cases that are handled with inline code).
508 -- N is the N_Indexed_Component node for the packed array reference
510 -- Atyp is the constrained array type (the actual subtype has been
511 -- computed if necessary to obtain the constraints, but this is still
512 -- the original array type, not the Packed_Array_Type value).
514 -- Obj is the object which is to be indexed. It is always of type Atyp.
518 -- Obj is the object containing the desired bit field. It is of type
519 -- Unsigned or Long_Long_Unsigned, and is either the entire value,
520 -- for the small static case, or the proper selected byte from the
521 -- array in the large or dynamic case. This node is analyzed and
522 -- resolved on return.
524 -- Shift is a node representing the shift count to be used in the
525 -- rotate right instruction that positions the field for access.
526 -- This node is analyzed and resolved on return.
528 -- Cmask is a mask corresponding to the width of the component field.
529 -- Its value is 2 ** Csize - 1 (e.g. 2#1111# for component size of 4).
531 -- Note: in some cases the call to this routine may generate actions
532 -- (for handling multi-use references and the generation of the packed
533 -- array type on the fly). Such actions are inserted into the tree
534 -- directly using Insert_Action.
536 ------------------------------
537 -- Compute_Linear_Subcsript --
538 ------------------------------
540 procedure Compute_Linear_Subscript
543 Subscr : out Node_Id)
545 Loc : constant Source_Ptr := Sloc (N);
554 -- Loop through dimensions
556 Indx := First_Index (Atyp);
557 Oldsub := First (Expressions (N));
559 while Present (Indx) loop
560 Styp := Etype (Indx);
561 Newsub := Relocate_Node (Oldsub);
563 -- Get expression for the subscript value. First, if Do_Range_Check
564 -- is set on a subscript, then we must do a range check against the
565 -- original bounds (not the bounds of the packed array type). We do
566 -- this by introducing a subtype conversion.
568 if Do_Range_Check (Newsub)
569 and then Etype (Newsub) /= Styp
571 Newsub := Convert_To (Styp, Newsub);
574 -- Now evolve the expression for the subscript. First convert
575 -- the subscript to be zero based and of an integer type.
577 -- Case of integer type, where we just subtract to get lower bound
579 if Is_Integer_Type (Styp) then
581 -- If length of integer type is smaller than standard integer,
582 -- then we convert to integer first, then do the subtract
584 -- Integer (subscript) - Integer (Styp'First)
586 if Esize (Styp) < Esize (Standard_Integer) then
588 Make_Op_Subtract (Loc,
589 Left_Opnd => Convert_To (Standard_Integer, Newsub),
591 Convert_To (Standard_Integer,
592 Make_Attribute_Reference (Loc,
593 Prefix => New_Occurrence_Of (Styp, Loc),
594 Attribute_Name => Name_First)));
596 -- For larger integer types, subtract first, then convert to
597 -- integer, this deals with strange long long integer bounds.
599 -- Integer (subscript - Styp'First)
603 Convert_To (Standard_Integer,
604 Make_Op_Subtract (Loc,
607 Make_Attribute_Reference (Loc,
608 Prefix => New_Occurrence_Of (Styp, Loc),
609 Attribute_Name => Name_First)));
612 -- For the enumeration case, we have to use 'Pos to get the value
613 -- to work with before subtracting the lower bound.
615 -- Integer (Styp'Pos (subscr)) - Integer (Styp'Pos (Styp'First));
617 -- This is not quite right for bizarre cases where the size of the
618 -- enumeration type is > Integer'Size bits due to rep clause ???
621 pragma Assert (Is_Enumeration_Type (Styp));
624 Make_Op_Subtract (Loc,
625 Left_Opnd => Convert_To (Standard_Integer,
626 Make_Attribute_Reference (Loc,
627 Prefix => New_Occurrence_Of (Styp, Loc),
628 Attribute_Name => Name_Pos,
629 Expressions => New_List (Newsub))),
632 Convert_To (Standard_Integer,
633 Make_Attribute_Reference (Loc,
634 Prefix => New_Occurrence_Of (Styp, Loc),
635 Attribute_Name => Name_Pos,
636 Expressions => New_List (
637 Make_Attribute_Reference (Loc,
638 Prefix => New_Occurrence_Of (Styp, Loc),
639 Attribute_Name => Name_First)))));
642 Set_Paren_Count (Newsub, 1);
644 -- For the first subscript, we just copy that subscript value
649 -- Otherwise, we must multiply what we already have by the current
650 -- stride and then add in the new value to the evolving subscript.
656 Make_Op_Multiply (Loc,
659 Make_Attribute_Reference (Loc,
660 Attribute_Name => Name_Range_Length,
661 Prefix => New_Occurrence_Of (Styp, Loc))),
662 Right_Opnd => Newsub);
665 -- Move to next subscript
670 end Compute_Linear_Subscript;
672 -------------------------
673 -- Convert_To_PAT_Type --
674 -------------------------
676 -- The PAT is always obtained from the actual subtype
678 procedure Convert_To_PAT_Type (Aexp : Entity_Id) is
682 Convert_To_Actual_Subtype (Aexp);
683 Act_ST := Underlying_Type (Etype (Aexp));
684 Create_Packed_Array_Type (Act_ST);
686 -- Just replace the etype with the packed array type. This works
687 -- because the expression will not be further analyzed, and Gigi
688 -- considers the two types equivalent in any case.
690 Set_Etype (Aexp, Packed_Array_Type (Act_ST));
691 end Convert_To_PAT_Type;
693 ------------------------------
694 -- Create_Packed_Array_Type --
695 ------------------------------
697 procedure Create_Packed_Array_Type (Typ : Entity_Id) is
698 Loc : constant Source_Ptr := Sloc (Typ);
699 Ctyp : constant Entity_Id := Component_Type (Typ);
700 Csize : constant Uint := Component_Size (Typ);
715 procedure Install_PAT;
716 -- This procedure is called with Decl set to the declaration for the
717 -- packed array type. It creates the type and installs it as required.
719 procedure Set_PB_Type;
720 -- Sets PB_Type to Packed_Bytes{1,2,4} as required by the alignment
721 -- requirements (see documentation in the spec of this package).
727 procedure Install_PAT is
728 Pushed_Scope : Boolean := False;
731 -- We do not want to put the declaration we have created in the tree
732 -- since it is often hard, and sometimes impossible to find a proper
733 -- place for it (the impossible case arises for a packed array type
734 -- with bounds depending on the discriminant, a declaration cannot
735 -- be put inside the record, and the reference to the discriminant
736 -- cannot be outside the record).
738 -- The solution is to analyze the declaration while temporarily
739 -- attached to the tree at an appropriate point, and then we install
740 -- the resulting type as an Itype in the packed array type field of
741 -- the original type, so that no explicit declaration is required.
743 -- Note: the packed type is created in the scope of its parent
744 -- type. There are at least some cases where the current scope
745 -- is deeper, and so when this is the case, we temporarily reset
746 -- the scope for the definition. This is clearly safe, since the
747 -- first use of the packed array type will be the implicit
748 -- reference from the corresponding unpacked type when it is
751 if Is_Itype (Typ) then
752 Set_Parent (Decl, Associated_Node_For_Itype (Typ));
754 Set_Parent (Decl, Declaration_Node (Typ));
757 if Scope (Typ) /= Current_Scope then
758 New_Scope (Scope (Typ));
759 Pushed_Scope := True;
762 Set_Is_Itype (PAT, True);
763 Set_Packed_Array_Type (Typ, PAT);
764 Analyze (Decl, Suppress => All_Checks);
770 -- Set Esize and RM_Size to the actual size of the packed object
771 -- Do not reset RM_Size if already set, as happens in the case
774 Set_Esize (PAT, Esiz);
776 if Unknown_RM_Size (PAT) then
777 Set_RM_Size (PAT, Esiz);
780 -- Set remaining fields of packed array type
782 Init_Alignment (PAT);
783 Set_Parent (PAT, Empty);
784 Set_Associated_Node_For_Itype (PAT, Typ);
785 Set_Is_Packed_Array_Type (PAT, True);
786 Set_Original_Array_Type (PAT, Typ);
788 -- We definitely do not want to delay freezing for packed array
789 -- types. This is of particular importance for the itypes that
790 -- are generated for record components depending on discriminants
791 -- where there is no place to put the freeze node.
793 Set_Has_Delayed_Freeze (PAT, False);
794 Set_Has_Delayed_Freeze (Etype (PAT), False);
801 procedure Set_PB_Type is
803 -- If the user has specified an explicit alignment for the
804 -- type or component, take it into account.
806 if Csize <= 2 or else Csize = 4 or else Csize mod 2 /= 0
807 or else Alignment (Typ) = 1
808 or else Component_Alignment (Typ) = Calign_Storage_Unit
810 PB_Type := RTE (RE_Packed_Bytes1);
812 elsif Csize mod 4 /= 0
813 or else Alignment (Typ) = 2
815 PB_Type := RTE (RE_Packed_Bytes2);
818 PB_Type := RTE (RE_Packed_Bytes4);
822 -- Start of processing for Create_Packed_Array_Type
825 -- If we already have a packed array type, nothing to do
827 if Present (Packed_Array_Type (Typ)) then
831 -- If our immediate ancestor subtype is constrained, and it already
832 -- has a packed array type, then just share the same type, since the
833 -- bounds must be the same.
835 if Ekind (Typ) = E_Array_Subtype then
836 Ancest := Ancestor_Subtype (Typ);
839 and then Is_Constrained (Ancest)
840 and then Present (Packed_Array_Type (Ancest))
842 Set_Packed_Array_Type (Typ, Packed_Array_Type (Ancest));
847 -- We preset the result type size from the size of the original array
848 -- type, since this size clearly belongs to the packed array type. The
849 -- size of the conceptual unpacked type is always set to unknown.
853 -- Case of an array where at least one index is of an enumeration
854 -- type with a non-standard representation, but the component size
855 -- is not appropriate for bit packing. This is the case where we
856 -- have Is_Packed set (we would never be in this unit otherwise),
857 -- but Is_Bit_Packed_Array is false.
859 -- Note that if the component size is appropriate for bit packing,
860 -- then the circuit for the computation of the subscript properly
861 -- deals with the non-standard enumeration type case by taking the
864 if not Is_Bit_Packed_Array (Typ) then
866 -- Here we build a declaration:
868 -- type tttP is array (index1, index2, ...) of component_type
870 -- where index1, index2, are the index types. These are the same
871 -- as the index types of the original array, except for the non-
872 -- standard representation enumeration type case, where we have
875 -- For the unconstrained array case, we use
879 -- For the constrained case, we use
881 -- Natural range Enum_Type'Pos (Enum_Type'First) ..
882 -- Enum_Type'Pos (Enum_Type'Last);
885 Make_Defining_Identifier (Loc,
886 Chars => New_External_Name (Chars (Typ), 'P'));
888 Set_Packed_Array_Type (Typ, PAT);
891 Indexes : List_Id := New_List;
893 Indx_Typ : Entity_Id;
898 Indx := First_Index (Typ);
900 while Present (Indx) loop
901 Indx_Typ := Etype (Indx);
903 Enum_Case := Is_Enumeration_Type (Indx_Typ)
904 and then Has_Non_Standard_Rep (Indx_Typ);
906 -- Unconstrained case
908 if not Is_Constrained (Typ) then
910 Indx_Typ := Standard_Natural;
913 Append_To (Indexes, New_Occurrence_Of (Indx_Typ, Loc));
918 if not Enum_Case then
919 Append_To (Indexes, New_Occurrence_Of (Indx_Typ, Loc));
923 Make_Subtype_Indication (Loc,
925 New_Occurrence_Of (Standard_Natural, Loc),
927 Make_Range_Constraint (Loc,
931 Make_Attribute_Reference (Loc,
933 New_Occurrence_Of (Indx_Typ, Loc),
934 Attribute_Name => Name_Pos,
935 Expressions => New_List (
936 Make_Attribute_Reference (Loc,
938 New_Occurrence_Of (Indx_Typ, Loc),
939 Attribute_Name => Name_First))),
942 Make_Attribute_Reference (Loc,
944 New_Occurrence_Of (Indx_Typ, Loc),
945 Attribute_Name => Name_Pos,
946 Expressions => New_List (
947 Make_Attribute_Reference (Loc,
949 New_Occurrence_Of (Indx_Typ, Loc),
950 Attribute_Name => Name_Last)))))));
958 if not Is_Constrained (Typ) then
960 Make_Unconstrained_Array_Definition (Loc,
961 Subtype_Marks => Indexes,
962 Subtype_Indication =>
963 New_Occurrence_Of (Ctyp, Loc));
967 Make_Constrained_Array_Definition (Loc,
968 Discrete_Subtype_Definitions => Indexes,
969 Subtype_Indication =>
970 New_Occurrence_Of (Ctyp, Loc));
974 Make_Full_Type_Declaration (Loc,
975 Defining_Identifier => PAT,
976 Type_Definition => Typedef);
979 -- Set type as packed array type and install it
981 Set_Is_Packed_Array_Type (PAT);
985 -- Case of bit-packing required for unconstrained array. We create
986 -- a subtype that is equivalent to use Packed_Bytes{1,2,4} as needed.
988 elsif not Is_Constrained (Typ) then
990 Make_Defining_Identifier (Loc,
991 Chars => Make_Packed_Array_Type_Name (Typ, Csize));
993 Set_Packed_Array_Type (Typ, PAT);
997 Make_Subtype_Declaration (Loc,
998 Defining_Identifier => PAT,
999 Subtype_Indication => New_Occurrence_Of (PB_Type, Loc));
1003 -- Remaining code is for the case of bit-packing for constrained array
1005 -- The name of the packed array subtype is
1009 -- where sss is the component size in bits and ttt is the name of
1010 -- the parent packed type.
1014 Make_Defining_Identifier (Loc,
1015 Chars => Make_Packed_Array_Type_Name (Typ, Csize));
1017 Set_Packed_Array_Type (Typ, PAT);
1019 -- Build an expression for the length of the array in bits.
1020 -- This is the product of the length of each of the dimensions
1026 Len_Expr := Empty; -- suppress junk warning
1030 Make_Attribute_Reference (Loc,
1031 Attribute_Name => Name_Length,
1032 Prefix => New_Occurrence_Of (Typ, Loc),
1033 Expressions => New_List (
1034 Make_Integer_Literal (Loc, J)));
1037 Len_Expr := Len_Dim;
1041 Make_Op_Multiply (Loc,
1042 Left_Opnd => Len_Expr,
1043 Right_Opnd => Len_Dim);
1047 exit when J > Number_Dimensions (Typ);
1051 -- Temporarily attach the length expression to the tree and analyze
1052 -- and resolve it, so that we can test its value. We assume that the
1053 -- total length fits in type Integer.
1055 Set_Parent (Len_Expr, Typ);
1056 Analyze_And_Resolve (Len_Expr, Standard_Integer);
1058 -- Use a modular type if possible. We can do this if we are we
1059 -- have static bounds, and the length is small enough, and the
1060 -- length is not zero. We exclude the zero length case because the
1061 -- size of things is always at least one, and the zero length object
1062 -- would have an anomous size
1064 if Compile_Time_Known_Value (Len_Expr) then
1065 Len_Bits := Expr_Value (Len_Expr) * Csize;
1067 -- We normally consider small enough to mean no larger than the
1068 -- value of System_Max_Binary_Modulus_Power, except that in
1069 -- No_Run_Time mode, we use the Word Size on machines for
1070 -- which double length shifts are not generated in line.
1074 (Len_Bits <= System_Word_Size
1075 or else (Len_Bits <= System_Max_Binary_Modulus_Power
1076 and then (not No_Run_Time
1078 Long_Shifts_Inlined_On_Target)))
1080 -- We can use the modular type, it has the form:
1082 -- subtype tttPn is btyp
1083 -- range 0 .. 2 ** (Esize (Typ) * Csize) - 1;
1085 -- Here Siz is 1, 2 or 4, as computed above, and btyp is either
1086 -- Unsigned or Long_Long_Unsigned depending on the length.
1088 if Len_Bits <= Standard_Integer_Size then
1089 Btyp := RTE (RE_Unsigned);
1091 Btyp := RTE (RE_Long_Long_Unsigned);
1094 Lit := Make_Integer_Literal (Loc, 2 ** Len_Bits - 1);
1095 Set_Print_In_Hex (Lit);
1098 Make_Subtype_Declaration (Loc,
1099 Defining_Identifier => PAT,
1100 Subtype_Indication =>
1101 Make_Subtype_Indication (Loc,
1102 Subtype_Mark => New_Occurrence_Of (Btyp, Loc),
1105 Make_Range_Constraint (Loc,
1109 Make_Integer_Literal (Loc, 0),
1110 High_Bound => Lit))));
1112 if Esiz = Uint_0 then
1121 -- Could not use a modular type, for all other cases, we build
1122 -- a packed array subtype:
1125 -- System.Packed_Bytes{1,2,4} (0 .. (Bits + 7) / 8 - 1);
1127 -- Bits is the length of the array in bits.
1134 Make_Op_Multiply (Loc,
1136 Make_Integer_Literal (Loc, Csize),
1137 Right_Opnd => Len_Expr),
1140 Make_Integer_Literal (Loc, 7));
1142 Set_Paren_Count (Bits_U1, 1);
1145 Make_Op_Subtract (Loc,
1147 Make_Op_Divide (Loc,
1148 Left_Opnd => Bits_U1,
1149 Right_Opnd => Make_Integer_Literal (Loc, 8)),
1150 Right_Opnd => Make_Integer_Literal (Loc, 1));
1153 Make_Subtype_Declaration (Loc,
1154 Defining_Identifier => PAT,
1155 Subtype_Indication =>
1156 Make_Subtype_Indication (Loc,
1157 Subtype_Mark => New_Occurrence_Of (PB_Type, Loc),
1160 Make_Index_Or_Discriminant_Constraint (Loc,
1161 Constraints => New_List (
1164 Make_Integer_Literal (Loc, 0),
1165 High_Bound => PAT_High)))));
1169 end Create_Packed_Array_Type;
1171 -----------------------------------
1172 -- Expand_Bit_Packed_Element_Set --
1173 -----------------------------------
1175 procedure Expand_Bit_Packed_Element_Set (N : Node_Id) is
1176 Loc : constant Source_Ptr := Sloc (N);
1177 Lhs : constant Node_Id := Name (N);
1179 Ass_OK : constant Boolean := Assignment_OK (Lhs);
1180 -- Used to preserve assignment OK status when assignment is rewritten
1182 Rhs : Node_Id := Expression (N);
1183 -- Initially Rhs is the right hand side value, it will be replaced
1184 -- later by an appropriate unchecked conversion for the assignment.
1197 Rhs_Val_Known : Boolean;
1199 -- If the value of the right hand side as an integer constant is
1200 -- known at compile time, Rhs_Val_Known is set True, and Rhs_Val
1201 -- contains the value. Otherwise Rhs_Val_Known is set False, and
1202 -- the Rhs_Val is undefined.
1205 pragma Assert (Is_Bit_Packed_Array (Etype (Prefix (Lhs))));
1207 Obj := Relocate_Node (Prefix (Lhs));
1208 Convert_To_Actual_Subtype (Obj);
1209 Atyp := Etype (Obj);
1210 PAT := Packed_Array_Type (Atyp);
1211 Ctyp := Component_Type (Atyp);
1212 Csiz := UI_To_Int (Component_Size (Atyp));
1214 -- We convert the right hand side to the proper subtype to ensure
1215 -- that an appropriate range check is made (since the normal range
1216 -- check from assignment will be lost in the transformations). This
1217 -- conversion is analyzed immediately so that subsequent processing
1218 -- can work with an analyzed Rhs (and e.g. look at its Etype)
1220 Rhs := Convert_To (Ctyp, Rhs);
1221 Set_Parent (Rhs, N);
1222 Analyze_And_Resolve (Rhs, Ctyp);
1224 -- Case of component size 1,2,4 or any component size for the modular
1225 -- case. These are the cases for which we can inline the code.
1227 if Csiz = 1 or else Csiz = 2 or else Csiz = 4
1228 or else (Present (PAT) and then Is_Modular_Integer_Type (PAT))
1230 Setup_Inline_Packed_Array_Reference (Lhs, Atyp, Obj, Cmask, Shift);
1232 -- The statement to be generated is:
1234 -- Obj := atyp!((Obj and Mask1) or (shift_left (rhs, shift)))
1236 -- where mask1 is obtained by shifting Cmask left Shift bits
1237 -- and then complementing the result.
1239 -- the "and Mask1" is omitted if rhs is constant and all 1 bits
1241 -- the "or ..." is omitted if rhs is constant and all 0 bits
1243 -- rhs is converted to the appropriate type.
1245 -- The result is converted back to the array type, since
1246 -- otherwise we lose knowledge of the packed nature.
1248 -- Determine if right side is all 0 bits or all 1 bits
1250 if Compile_Time_Known_Value (Rhs) then
1251 Rhs_Val := Expr_Rep_Value (Rhs);
1252 Rhs_Val_Known := True;
1254 -- The following test catches the case of an unchecked conversion
1255 -- of an integer literal. This results from optimizing aggregates
1258 elsif Nkind (Rhs) = N_Unchecked_Type_Conversion
1259 and then Compile_Time_Known_Value (Expression (Rhs))
1261 Rhs_Val := Expr_Rep_Value (Expression (Rhs));
1262 Rhs_Val_Known := True;
1266 Rhs_Val_Known := False;
1269 -- Some special checks for the case where the right hand value
1270 -- is known at compile time. Basically we have to take care of
1271 -- the implicit conversion to the subtype of the component object.
1273 if Rhs_Val_Known then
1275 -- If we have a biased component type then we must manually do
1276 -- the biasing, since we are taking responsibility in this case
1277 -- for constructing the exact bit pattern to be used.
1279 if Has_Biased_Representation (Ctyp) then
1280 Rhs_Val := Rhs_Val - Expr_Rep_Value (Type_Low_Bound (Ctyp));
1283 -- For a negative value, we manually convert the twos complement
1284 -- value to a corresponding unsigned value, so that the proper
1285 -- field width is maintained. If we did not do this, we would
1286 -- get too many leading sign bits later on.
1289 Rhs_Val := 2 ** UI_From_Int (Csiz) + Rhs_Val;
1293 New_Lhs := Duplicate_Subexpr (Obj, True);
1294 New_Rhs := Duplicate_Subexpr (Obj);
1296 -- First we deal with the "and"
1298 if not Rhs_Val_Known or else Rhs_Val /= Cmask then
1304 if Compile_Time_Known_Value (Shift) then
1306 Make_Integer_Literal (Loc,
1307 Modulus (Etype (Obj)) - 1 -
1308 (Cmask * (2 ** Expr_Value (Shift))));
1309 Set_Print_In_Hex (Mask1);
1312 Lit := Make_Integer_Literal (Loc, Cmask);
1313 Set_Print_In_Hex (Lit);
1316 Right_Opnd => Make_Shift_Left (Lit, Shift));
1321 Left_Opnd => New_Rhs,
1322 Right_Opnd => Mask1);
1326 -- Then deal with the "or"
1328 if not Rhs_Val_Known or else Rhs_Val /= 0 then
1332 procedure Fixup_Rhs;
1333 -- Adjust Rhs by bias if biased representation for components
1334 -- or remove extraneous high order sign bits if signed.
1336 procedure Fixup_Rhs is
1337 Etyp : constant Entity_Id := Etype (Rhs);
1340 -- For biased case, do the required biasing by simply
1341 -- converting to the biased subtype (the conversion
1342 -- will generate the required bias).
1344 if Has_Biased_Representation (Ctyp) then
1345 Rhs := Convert_To (Ctyp, Rhs);
1347 -- For a signed integer type that is not biased, generate
1348 -- a conversion to unsigned to strip high order sign bits.
1350 elsif Is_Signed_Integer_Type (Ctyp) then
1351 Rhs := Unchecked_Convert_To (RTE (Bits_Id (Csiz)), Rhs);
1354 -- Set Etype, since it can be referenced before the
1355 -- node is completely analyzed.
1357 Set_Etype (Rhs, Etyp);
1359 -- We now need to do an unchecked conversion of the
1360 -- result to the target type, but it is important that
1361 -- this conversion be a right justified conversion and
1362 -- not a left justified conversion.
1364 Rhs := RJ_Unchecked_Convert_To (Etype (Obj), Rhs);
1370 and then Compile_Time_Known_Value (Shift)
1373 Make_Integer_Literal (Loc,
1374 Rhs_Val * (2 ** Expr_Value (Shift)));
1375 Set_Print_In_Hex (Or_Rhs);
1378 -- We have to convert the right hand side to Etype (Obj).
1379 -- A special case case arises if what we have now is a Val
1380 -- attribute reference whose expression type is Etype (Obj).
1381 -- This happens for assignments of fields from the same
1382 -- array. In this case we get the required right hand side
1383 -- by simply removing the inner attribute reference.
1385 if Nkind (Rhs) = N_Attribute_Reference
1386 and then Attribute_Name (Rhs) = Name_Val
1387 and then Etype (First (Expressions (Rhs))) = Etype (Obj)
1389 Rhs := Relocate_Node (First (Expressions (Rhs)));
1392 -- If the value of the right hand side is a known integer
1393 -- value, then just replace it by an untyped constant,
1394 -- which will be properly retyped when we analyze and
1395 -- resolve the expression.
1397 elsif Rhs_Val_Known then
1399 -- Note that Rhs_Val has already been normalized to
1400 -- be an unsigned value with the proper number of bits.
1403 Make_Integer_Literal (Loc, Rhs_Val);
1405 -- Otherwise we need an unchecked conversion
1411 Or_Rhs := Make_Shift_Left (Rhs, Shift);
1414 if Nkind (New_Rhs) = N_Op_And then
1415 Set_Paren_Count (New_Rhs, 1);
1420 Left_Opnd => New_Rhs,
1421 Right_Opnd => Or_Rhs);
1425 -- Now do the rewrite
1428 Make_Assignment_Statement (Loc,
1431 Unchecked_Convert_To (Etype (New_Lhs), New_Rhs)));
1432 Set_Assignment_OK (Name (N), Ass_OK);
1434 -- All other component sizes for non-modular case
1439 -- Set_nn (Arr'address, Subscr, Bits_nn!(Rhs))
1441 -- where Subscr is the computed linear subscript.
1444 Bits_nn : constant Entity_Id := RTE (Bits_Id (Csiz));
1450 -- Acquire proper Set entity. We use the aligned or unaligned
1451 -- case as appropriate.
1453 if Known_Aligned_Enough (Obj, Csiz) then
1454 Set_nn := RTE (Set_Id (Csiz));
1456 Set_nn := RTE (SetU_Id (Csiz));
1459 -- Now generate the set reference
1461 Obj := Relocate_Node (Prefix (Lhs));
1462 Convert_To_Actual_Subtype (Obj);
1463 Atyp := Etype (Obj);
1464 Compute_Linear_Subscript (Atyp, Lhs, Subscr);
1467 Make_Procedure_Call_Statement (Loc,
1468 Name => New_Occurrence_Of (Set_nn, Loc),
1469 Parameter_Associations => New_List (
1470 Make_Byte_Aligned_Attribute_Reference (Loc,
1471 Attribute_Name => Name_Address,
1474 Unchecked_Convert_To (Bits_nn,
1475 Convert_To (Ctyp, Rhs)))));
1480 Analyze (N, Suppress => All_Checks);
1481 end Expand_Bit_Packed_Element_Set;
1483 -------------------------------------
1484 -- Expand_Packed_Address_Reference --
1485 -------------------------------------
1487 procedure Expand_Packed_Address_Reference (N : Node_Id) is
1488 Loc : constant Source_Ptr := Sloc (N);
1500 -- We build up an expression serially that has the form
1502 -- outer_object'Address
1503 -- + (linear-subscript * component_size for each array reference
1504 -- + field'Bit_Position for each record field
1506 -- + ...) / Storage_Unit;
1508 -- Some additional conversions are required to deal with the addition
1509 -- operation, which is not normally visible to generated code.
1512 Ploc := Sloc (Pref);
1514 if Nkind (Pref) = N_Indexed_Component then
1515 Convert_To_Actual_Subtype (Prefix (Pref));
1516 Atyp := Etype (Prefix (Pref));
1517 Compute_Linear_Subscript (Atyp, Pref, Subscr);
1520 Make_Op_Multiply (Ploc,
1521 Left_Opnd => Subscr,
1523 Make_Attribute_Reference (Ploc,
1524 Prefix => New_Occurrence_Of (Atyp, Ploc),
1525 Attribute_Name => Name_Component_Size));
1527 elsif Nkind (Pref) = N_Selected_Component then
1529 Make_Attribute_Reference (Ploc,
1530 Prefix => Selector_Name (Pref),
1531 Attribute_Name => Name_Bit_Position);
1537 Term := Convert_To (RTE (RE_Integer_Address), Term);
1546 Right_Opnd => Term);
1549 Pref := Prefix (Pref);
1553 Unchecked_Convert_To (RTE (RE_Address),
1556 Unchecked_Convert_To (RTE (RE_Integer_Address),
1557 Make_Attribute_Reference (Loc,
1559 Attribute_Name => Name_Address)),
1562 Make_Op_Divide (Loc,
1565 Make_Integer_Literal (Loc, System_Storage_Unit)))));
1567 Analyze_And_Resolve (N, RTE (RE_Address));
1568 end Expand_Packed_Address_Reference;
1570 ------------------------------------
1571 -- Expand_Packed_Boolean_Operator --
1572 ------------------------------------
1574 -- This routine expands "a op b" for the packed cases
1576 procedure Expand_Packed_Boolean_Operator (N : Node_Id) is
1577 Loc : constant Source_Ptr := Sloc (N);
1578 Typ : constant Entity_Id := Etype (N);
1579 L : constant Node_Id := Relocate_Node (Left_Opnd (N));
1580 R : constant Node_Id := Relocate_Node (Right_Opnd (N));
1587 Convert_To_Actual_Subtype (L);
1588 Convert_To_Actual_Subtype (R);
1590 Ensure_Defined (Etype (L), N);
1591 Ensure_Defined (Etype (R), N);
1593 Apply_Length_Check (R, Etype (L));
1598 -- First an odd and silly test. We explicitly check for the XOR
1599 -- case where the component type is True .. True, since this will
1600 -- raise constraint error. A special check is required since CE
1601 -- will not be required other wise (cf Expand_Packed_Not).
1603 -- No such check is required for AND and OR, since for both these
1604 -- cases False op False = False, and True op True = True.
1606 if Nkind (N) = N_Op_Xor then
1608 CT : constant Entity_Id := Component_Type (Rtyp);
1609 BT : constant Entity_Id := Base_Type (CT);
1613 Make_Raise_Constraint_Error (Loc,
1619 Make_Attribute_Reference (Loc,
1620 Prefix => New_Occurrence_Of (CT, Loc),
1621 Attribute_Name => Name_First),
1625 New_Occurrence_Of (Standard_True, Loc))),
1630 Make_Attribute_Reference (Loc,
1631 Prefix => New_Occurrence_Of (CT, Loc),
1632 Attribute_Name => Name_Last),
1636 New_Occurrence_Of (Standard_True, Loc)))),
1637 Reason => CE_Range_Check_Failed));
1641 -- Now that that silliness is taken care of, get packed array type
1643 Convert_To_PAT_Type (L);
1644 Convert_To_PAT_Type (R);
1648 -- For the modular case, we expand a op b into
1650 -- rtyp!(pat!(a) op pat!(b))
1652 -- where rtyp is the Etype of the left operand. Note that we do not
1653 -- convert to the base type, since this would be unconstrained, and
1654 -- hence not have a corresponding packed array type set.
1656 if Is_Modular_Integer_Type (PAT) then
1661 if Nkind (N) = N_Op_And then
1662 P := Make_Op_And (Loc, L, R);
1664 elsif Nkind (N) = N_Op_Or then
1665 P := Make_Op_Or (Loc, L, R);
1667 else -- Nkind (N) = N_Op_Xor
1668 P := Make_Op_Xor (Loc, L, R);
1671 Rewrite (N, Unchecked_Convert_To (Rtyp, P));
1674 -- For the array case, we insert the actions
1678 -- System.Bitops.Bit_And/Or/Xor
1680 -- Ltype'Length * Ltype'Component_Size;
1682 -- Rtype'Length * Rtype'Component_Size
1685 -- where Left and Right are the Packed_Bytes{1,2,4} operands and
1686 -- the second argument and fourth arguments are the lengths of the
1687 -- operands in bits. Then we replace the expression by a reference
1692 Result_Ent : constant Entity_Id :=
1693 Make_Defining_Identifier (Loc,
1694 Chars => New_Internal_Name ('T'));
1699 if Nkind (N) = N_Op_And then
1702 elsif Nkind (N) = N_Op_Or then
1705 else -- Nkind (N) = N_Op_Xor
1709 Insert_Actions (N, New_List (
1711 Make_Object_Declaration (Loc,
1712 Defining_Identifier => Result_Ent,
1713 Object_Definition => New_Occurrence_Of (Ltyp, Loc)),
1715 Make_Procedure_Call_Statement (Loc,
1716 Name => New_Occurrence_Of (RTE (E_Id), Loc),
1717 Parameter_Associations => New_List (
1719 Make_Byte_Aligned_Attribute_Reference (Loc,
1720 Attribute_Name => Name_Address,
1723 Make_Op_Multiply (Loc,
1725 Make_Attribute_Reference (Loc,
1728 (Etype (First_Index (Ltyp)), Loc),
1729 Attribute_Name => Name_Range_Length),
1731 Make_Integer_Literal (Loc, Component_Size (Ltyp))),
1733 Make_Byte_Aligned_Attribute_Reference (Loc,
1734 Attribute_Name => Name_Address,
1737 Make_Op_Multiply (Loc,
1739 Make_Attribute_Reference (Loc,
1742 (Etype (First_Index (Rtyp)), Loc),
1743 Attribute_Name => Name_Range_Length),
1745 Make_Integer_Literal (Loc, Component_Size (Rtyp))),
1747 Make_Byte_Aligned_Attribute_Reference (Loc,
1748 Attribute_Name => Name_Address,
1749 Prefix => New_Occurrence_Of (Result_Ent, Loc))))));
1752 New_Occurrence_Of (Result_Ent, Loc));
1756 Analyze_And_Resolve (N, Typ, Suppress => All_Checks);
1757 end Expand_Packed_Boolean_Operator;
1759 -------------------------------------
1760 -- Expand_Packed_Element_Reference --
1761 -------------------------------------
1763 procedure Expand_Packed_Element_Reference (N : Node_Id) is
1764 Loc : constant Source_Ptr := Sloc (N);
1776 -- If not bit packed, we have the enumeration case, which is easily
1777 -- dealt with (just adjust the subscripts of the indexed component)
1779 -- Note: this leaves the result as an indexed component, which is
1780 -- still a variable, so can be used in the assignment case, as is
1781 -- required in the enumeration case.
1783 if not Is_Bit_Packed_Array (Etype (Prefix (N))) then
1784 Setup_Enumeration_Packed_Array_Reference (N);
1788 -- Remaining processing is for the bit-packed case.
1790 Obj := Relocate_Node (Prefix (N));
1791 Convert_To_Actual_Subtype (Obj);
1792 Atyp := Etype (Obj);
1793 PAT := Packed_Array_Type (Atyp);
1794 Ctyp := Component_Type (Atyp);
1795 Csiz := UI_To_Int (Component_Size (Atyp));
1797 -- Case of component size 1,2,4 or any component size for the modular
1798 -- case. These are the cases for which we can inline the code.
1800 if Csiz = 1 or else Csiz = 2 or else Csiz = 4
1801 or else (Present (PAT) and then Is_Modular_Integer_Type (PAT))
1803 Setup_Inline_Packed_Array_Reference (N, Atyp, Obj, Cmask, Shift);
1804 Lit := Make_Integer_Literal (Loc, Cmask);
1805 Set_Print_In_Hex (Lit);
1807 -- We generate a shift right to position the field, followed by a
1808 -- masking operation to extract the bit field, and we finally do an
1809 -- unchecked conversion to convert the result to the required target.
1811 -- Note that the unchecked conversion automatically deals with the
1812 -- bias if we are dealing with a biased representation. What will
1813 -- happen is that we temporarily generate the biased representation,
1814 -- but almost immediately that will be converted to the original
1815 -- unbiased component type, and the bias will disappear.
1819 Left_Opnd => Make_Shift_Right (Obj, Shift),
1822 Analyze_And_Resolve (Arg);
1825 RJ_Unchecked_Convert_To (Ctyp, Arg));
1827 -- All other component sizes for non-modular case
1832 -- Component_Type!(Get_nn (Arr'address, Subscr))
1834 -- where Subscr is the computed linear subscript.
1841 -- Acquire proper Get entity. We use the aligned or unaligned
1842 -- case as appropriate.
1844 if Known_Aligned_Enough (Obj, Csiz) then
1845 Get_nn := RTE (Get_Id (Csiz));
1847 Get_nn := RTE (GetU_Id (Csiz));
1850 -- Now generate the get reference
1852 Compute_Linear_Subscript (Atyp, N, Subscr);
1855 Unchecked_Convert_To (Ctyp,
1856 Make_Function_Call (Loc,
1857 Name => New_Occurrence_Of (Get_nn, Loc),
1858 Parameter_Associations => New_List (
1859 Make_Byte_Aligned_Attribute_Reference (Loc,
1860 Attribute_Name => Name_Address,
1866 Analyze_And_Resolve (N, Ctyp, Suppress => All_Checks);
1868 end Expand_Packed_Element_Reference;
1870 ----------------------
1871 -- Expand_Packed_Eq --
1872 ----------------------
1874 -- Handles expansion of "=" on packed array types
1876 procedure Expand_Packed_Eq (N : Node_Id) is
1877 Loc : constant Source_Ptr := Sloc (N);
1878 L : constant Node_Id := Relocate_Node (Left_Opnd (N));
1879 R : constant Node_Id := Relocate_Node (Right_Opnd (N));
1889 Convert_To_Actual_Subtype (L);
1890 Convert_To_Actual_Subtype (R);
1891 Ltyp := Underlying_Type (Etype (L));
1892 Rtyp := Underlying_Type (Etype (R));
1894 Convert_To_PAT_Type (L);
1895 Convert_To_PAT_Type (R);
1899 Make_Op_Multiply (Loc,
1901 Make_Attribute_Reference (Loc,
1902 Attribute_Name => Name_Length,
1903 Prefix => New_Occurrence_Of (Ltyp, Loc)),
1905 Make_Integer_Literal (Loc, Component_Size (Ltyp)));
1908 Make_Op_Multiply (Loc,
1910 Make_Attribute_Reference (Loc,
1911 Attribute_Name => Name_Length,
1912 Prefix => New_Occurrence_Of (Rtyp, Loc)),
1914 Make_Integer_Literal (Loc, Component_Size (Rtyp)));
1916 -- For the modular case, we transform the comparison to:
1918 -- Ltyp'Length = Rtyp'Length and then PAT!(L) = PAT!(R)
1920 -- where PAT is the packed array type. This works fine, since in the
1921 -- modular case we guarantee that the unused bits are always zeroes.
1922 -- We do have to compare the lengths because we could be comparing
1923 -- two different subtypes of the same base type.
1925 if Is_Modular_Integer_Type (PAT) then
1930 Left_Opnd => LLexpr,
1931 Right_Opnd => RLexpr),
1938 -- For the non-modular case, we call a runtime routine
1940 -- System.Bit_Ops.Bit_Eq
1941 -- (L'Address, L_Length, R'Address, R_Length)
1943 -- where PAT is the packed array type, and the lengths are the lengths
1944 -- in bits of the original packed arrays. This routine takes care of
1945 -- not comparing the unused bits in the last byte.
1949 Make_Function_Call (Loc,
1950 Name => New_Occurrence_Of (RTE (RE_Bit_Eq), Loc),
1951 Parameter_Associations => New_List (
1952 Make_Byte_Aligned_Attribute_Reference (Loc,
1953 Attribute_Name => Name_Address,
1958 Make_Byte_Aligned_Attribute_Reference (Loc,
1959 Attribute_Name => Name_Address,
1965 Analyze_And_Resolve (N, Standard_Boolean, Suppress => All_Checks);
1966 end Expand_Packed_Eq;
1968 -----------------------
1969 -- Expand_Packed_Not --
1970 -----------------------
1972 -- Handles expansion of "not" on packed array types
1974 procedure Expand_Packed_Not (N : Node_Id) is
1975 Loc : constant Source_Ptr := Sloc (N);
1976 Typ : constant Entity_Id := Etype (N);
1977 Opnd : constant Node_Id := Relocate_Node (Right_Opnd (N));
1984 Convert_To_Actual_Subtype (Opnd);
1985 Rtyp := Etype (Opnd);
1987 -- First an odd and silly test. We explicitly check for the case
1988 -- where the 'First of the component type is equal to the 'Last of
1989 -- this component type, and if this is the case, we make sure that
1990 -- constraint error is raised. The reason is that the NOT is bound
1991 -- to cause CE in this case, and we will not otherwise catch it.
1993 -- Believe it or not, this was reported as a bug. Note that nearly
1994 -- always, the test will evaluate statically to False, so the code
1995 -- will be statically removed, and no extra overhead caused.
1998 CT : constant Entity_Id := Component_Type (Rtyp);
2002 Make_Raise_Constraint_Error (Loc,
2006 Make_Attribute_Reference (Loc,
2007 Prefix => New_Occurrence_Of (CT, Loc),
2008 Attribute_Name => Name_First),
2011 Make_Attribute_Reference (Loc,
2012 Prefix => New_Occurrence_Of (CT, Loc),
2013 Attribute_Name => Name_Last)),
2014 Reason => CE_Range_Check_Failed));
2017 -- Now that that silliness is taken care of, get packed array type
2019 Convert_To_PAT_Type (Opnd);
2020 PAT := Etype (Opnd);
2022 -- For the case where the packed array type is a modular type,
2023 -- not A expands simply into:
2025 -- rtyp!(PAT!(A) xor mask)
2027 -- where PAT is the packed array type, and mask is a mask of all
2028 -- one bits of length equal to the size of this packed type and
2029 -- rtyp is the actual subtype of the operand
2031 Lit := Make_Integer_Literal (Loc, 2 ** Esize (PAT) - 1);
2032 Set_Print_In_Hex (Lit);
2034 if not Is_Array_Type (PAT) then
2036 Unchecked_Convert_To (Rtyp,
2039 Right_Opnd => Lit)));
2041 -- For the array case, we insert the actions
2045 -- System.Bitops.Bit_Not
2047 -- Typ'Length * Typ'Component_Size;
2050 -- where Opnd is the Packed_Bytes{1,2,4} operand and the second
2051 -- argument is the length of the operand in bits. Then we replace
2052 -- the expression by a reference to Result.
2056 Result_Ent : constant Entity_Id :=
2057 Make_Defining_Identifier (Loc,
2058 Chars => New_Internal_Name ('T'));
2061 Insert_Actions (N, New_List (
2063 Make_Object_Declaration (Loc,
2064 Defining_Identifier => Result_Ent,
2065 Object_Definition => New_Occurrence_Of (Rtyp, Loc)),
2067 Make_Procedure_Call_Statement (Loc,
2068 Name => New_Occurrence_Of (RTE (RE_Bit_Not), Loc),
2069 Parameter_Associations => New_List (
2071 Make_Byte_Aligned_Attribute_Reference (Loc,
2072 Attribute_Name => Name_Address,
2075 Make_Op_Multiply (Loc,
2077 Make_Attribute_Reference (Loc,
2080 (Etype (First_Index (Rtyp)), Loc),
2081 Attribute_Name => Name_Range_Length),
2083 Make_Integer_Literal (Loc, Component_Size (Rtyp))),
2085 Make_Byte_Aligned_Attribute_Reference (Loc,
2086 Attribute_Name => Name_Address,
2087 Prefix => New_Occurrence_Of (Result_Ent, Loc))))));
2090 New_Occurrence_Of (Result_Ent, Loc));
2094 Analyze_And_Resolve (N, Typ, Suppress => All_Checks);
2096 end Expand_Packed_Not;
2098 -------------------------------------
2099 -- Involves_Packed_Array_Reference --
2100 -------------------------------------
2102 function Involves_Packed_Array_Reference (N : Node_Id) return Boolean is
2104 if Nkind (N) = N_Indexed_Component
2105 and then Is_Bit_Packed_Array (Etype (Prefix (N)))
2109 elsif Nkind (N) = N_Selected_Component then
2110 return Involves_Packed_Array_Reference (Prefix (N));
2115 end Involves_Packed_Array_Reference;
2117 --------------------------
2118 -- Known_Aligned_Enough --
2119 --------------------------
2121 function Known_Aligned_Enough (Obj : Node_Id; Csiz : Nat) return Boolean is
2122 Typ : constant Entity_Id := Etype (Obj);
2124 function In_Partially_Packed_Record (Comp : Entity_Id) return Boolean;
2125 -- If the component is in a record that contains previous packed
2126 -- components, consider it unaligned because the back-end might
2127 -- choose to pack the rest of the record. Lead to less efficient code,
2128 -- but safer vis-a-vis of back-end choices.
2130 --------------------------------
2131 -- In_Partially_Packed_Record --
2132 --------------------------------
2134 function In_Partially_Packed_Record (Comp : Entity_Id) return Boolean is
2135 Rec_Type : constant Entity_Id := Scope (Comp);
2136 Prev_Comp : Entity_Id;
2139 Prev_Comp := First_Entity (Rec_Type);
2140 while Present (Prev_Comp) loop
2141 if Is_Packed (Etype (Prev_Comp)) then
2144 elsif Prev_Comp = Comp then
2148 Next_Entity (Prev_Comp);
2152 end In_Partially_Packed_Record;
2154 -- Start of processing for Known_Aligned_Enough
2157 -- Odd bit sizes don't need alignment anyway
2159 if Csiz mod 2 = 1 then
2162 -- If we have a specified alignment, see if it is sufficient, if not
2163 -- then we can't possibly be aligned enough in any case.
2165 elsif Known_Alignment (Etype (Obj)) then
2166 -- Alignment required is 4 if size is a multiple of 4, and
2167 -- 2 otherwise (e.g. 12 bits requires 4, 10 bits requires 2)
2169 if Alignment (Etype (Obj)) < 4 - (Csiz mod 4) then
2174 -- OK, alignment should be sufficient, if object is aligned
2176 -- If object is strictly aligned, then it is definitely aligned
2178 if Strict_Alignment (Typ) then
2181 -- Case of subscripted array reference
2183 elsif Nkind (Obj) = N_Indexed_Component then
2185 -- If we have a pointer to an array, then this is definitely
2186 -- aligned, because pointers always point to aligned versions.
2188 if Is_Access_Type (Etype (Prefix (Obj))) then
2191 -- Otherwise, go look at the prefix
2194 return Known_Aligned_Enough (Prefix (Obj), Csiz);
2197 -- Case of record field
2199 elsif Nkind (Obj) = N_Selected_Component then
2201 -- What is significant here is whether the record type is packed
2203 if Is_Record_Type (Etype (Prefix (Obj)))
2204 and then Is_Packed (Etype (Prefix (Obj)))
2208 -- Or the component has a component clause which might cause
2209 -- the component to become unaligned (we can't tell if the
2210 -- backend is doing alignment computations).
2212 elsif Present (Component_Clause (Entity (Selector_Name (Obj)))) then
2215 elsif In_Partially_Packed_Record (Entity (Selector_Name (Obj))) then
2218 -- In all other cases, go look at prefix
2221 return Known_Aligned_Enough (Prefix (Obj), Csiz);
2224 -- If not selected or indexed component, must be aligned
2229 end Known_Aligned_Enough;
2231 ---------------------
2232 -- Make_Shift_Left --
2233 ---------------------
2235 function Make_Shift_Left (N : Node_Id; S : Node_Id) return Node_Id is
2239 if Compile_Time_Known_Value (S) and then Expr_Value (S) = 0 then
2243 Make_Op_Shift_Left (Sloc (N),
2246 Set_Shift_Count_OK (Nod, True);
2249 end Make_Shift_Left;
2251 ----------------------
2252 -- Make_Shift_Right --
2253 ----------------------
2255 function Make_Shift_Right (N : Node_Id; S : Node_Id) return Node_Id is
2259 if Compile_Time_Known_Value (S) and then Expr_Value (S) = 0 then
2263 Make_Op_Shift_Right (Sloc (N),
2266 Set_Shift_Count_OK (Nod, True);
2269 end Make_Shift_Right;
2271 -----------------------------
2272 -- RJ_Unchecked_Convert_To --
2273 -----------------------------
2275 function RJ_Unchecked_Convert_To
2280 Source_Typ : constant Entity_Id := Etype (Expr);
2281 Target_Typ : constant Entity_Id := Typ;
2283 Src : Node_Id := Expr;
2289 Source_Siz := UI_To_Int (RM_Size (Source_Typ));
2290 Target_Siz := UI_To_Int (RM_Size (Target_Typ));
2292 -- In the big endian case, if the lengths of the two types differ,
2293 -- then we must worry about possible left justification in the
2294 -- conversion, and avoiding that is what this is all about.
2296 if Bytes_Big_Endian and then Source_Siz /= Target_Siz then
2298 -- First step, if the source type is not a discrete type, then we
2299 -- first convert to a modular type of the source length, since
2300 -- otherwise, on a big-endian machine, we get left-justification.
2302 if not Is_Discrete_Type (Source_Typ) then
2303 Src := Unchecked_Convert_To (RTE (Bits_Id (Source_Siz)), Src);
2306 -- Next step. If the target is not a discrete type, then we first
2307 -- convert to a modular type of the target length, since
2308 -- otherwise, on a big-endian machine, we get left-justification.
2310 if not Is_Discrete_Type (Target_Typ) then
2311 Src := Unchecked_Convert_To (RTE (Bits_Id (Target_Siz)), Src);
2315 -- And now we can do the final conversion to the target type
2317 return Unchecked_Convert_To (Target_Typ, Src);
2318 end RJ_Unchecked_Convert_To;
2320 ----------------------------------------------
2321 -- Setup_Enumeration_Packed_Array_Reference --
2322 ----------------------------------------------
2324 -- All we have to do here is to find the subscripts that correspond
2325 -- to the index positions that have non-standard enumeration types
2326 -- and insert a Pos attribute to get the proper subscript value.
2328 -- Finally the prefix must be uncheck converted to the corresponding
2329 -- packed array type.
2331 -- Note that the component type is unchanged, so we do not need to
2332 -- fiddle with the types (Gigi always automatically takes the packed
2333 -- array type if it is set, as it will be in this case).
2335 procedure Setup_Enumeration_Packed_Array_Reference (N : Node_Id) is
2336 Pfx : constant Node_Id := Prefix (N);
2337 Typ : constant Entity_Id := Etype (N);
2338 Exprs : constant List_Id := Expressions (N);
2342 -- If the array is unconstrained, then we replace the array
2343 -- reference with its actual subtype. This actual subtype will
2344 -- have a packed array type with appropriate bounds.
2346 if not Is_Constrained (Packed_Array_Type (Etype (Pfx))) then
2347 Convert_To_Actual_Subtype (Pfx);
2350 Expr := First (Exprs);
2351 while Present (Expr) loop
2353 Loc : constant Source_Ptr := Sloc (Expr);
2354 Expr_Typ : constant Entity_Id := Etype (Expr);
2357 if Is_Enumeration_Type (Expr_Typ)
2358 and then Has_Non_Standard_Rep (Expr_Typ)
2361 Make_Attribute_Reference (Loc,
2362 Prefix => New_Occurrence_Of (Expr_Typ, Loc),
2363 Attribute_Name => Name_Pos,
2364 Expressions => New_List (Relocate_Node (Expr))));
2365 Analyze_And_Resolve (Expr, Standard_Natural);
2373 Make_Indexed_Component (Sloc (N),
2375 Unchecked_Convert_To (Packed_Array_Type (Etype (Pfx)), Pfx),
2376 Expressions => Exprs));
2378 Analyze_And_Resolve (N, Typ);
2380 end Setup_Enumeration_Packed_Array_Reference;
2382 -----------------------------------------
2383 -- Setup_Inline_Packed_Array_Reference --
2384 -----------------------------------------
2386 procedure Setup_Inline_Packed_Array_Reference
2389 Obj : in out Node_Id;
2391 Shift : out Node_Id)
2393 Loc : constant Source_Ptr := Sloc (N);
2401 Ctyp := Component_Type (Atyp);
2402 Csiz := Component_Size (Atyp);
2404 Convert_To_PAT_Type (Obj);
2407 Cmask := 2 ** Csiz - 1;
2409 if Is_Array_Type (PAT) then
2410 Otyp := Component_Type (PAT);
2411 Osiz := Esize (Otyp);
2416 -- In the case where the PAT is a modular type, we want the actual
2417 -- size in bits of the modular value we use. This is neither the
2418 -- Object_Size nor the Value_Size, either of which may have been
2419 -- reset to strange values, but rather the minimum size. Note that
2420 -- since this is a modular type with full range, the issue of
2421 -- biased representation does not arise.
2423 Osiz := UI_From_Int (Minimum_Size (Otyp));
2426 Compute_Linear_Subscript (Atyp, N, Shift);
2428 -- If the component size is not 1, then the subscript must be
2429 -- multiplied by the component size to get the shift count.
2433 Make_Op_Multiply (Loc,
2434 Left_Opnd => Make_Integer_Literal (Loc, Csiz),
2435 Right_Opnd => Shift);
2438 -- If we have the array case, then this shift count must be broken
2439 -- down into a byte subscript, and a shift within the byte.
2441 if Is_Array_Type (PAT) then
2444 New_Shift : Node_Id;
2447 -- We must analyze shift, since we will duplicate it
2449 Set_Parent (Shift, N);
2451 (Shift, Standard_Integer, Suppress => All_Checks);
2453 -- The shift count within the word is
2458 Left_Opnd => Duplicate_Subexpr (Shift),
2459 Right_Opnd => Make_Integer_Literal (Loc, Osiz));
2461 -- The subscript to be used on the PAT array is
2465 Make_Indexed_Component (Loc,
2467 Expressions => New_List (
2468 Make_Op_Divide (Loc,
2469 Left_Opnd => Duplicate_Subexpr (Shift),
2470 Right_Opnd => Make_Integer_Literal (Loc, Osiz))));
2475 -- For the modular integer case, the object to be manipulated is
2476 -- the entire array, so Obj is unchanged. Note that we will reset
2477 -- its type to PAT before returning to the caller.
2483 -- The one remaining step is to modify the shift count for the
2484 -- big-endian case. Consider the following example in a byte:
2486 -- xxxxxxxx bits of byte
2487 -- vvvvvvvv bits of value
2488 -- 33221100 little-endian numbering
2489 -- 00112233 big-endian numbering
2491 -- Here we have the case of 2-bit fields
2493 -- For the little-endian case, we already have the proper shift
2494 -- count set, e.g. for element 2, the shift count is 2*2 = 4.
2496 -- For the big endian case, we have to adjust the shift count,
2497 -- computing it as (N - F) - shift, where N is the number of bits
2498 -- in an element of the array used to implement the packed array,
2499 -- F is the number of bits in a source level array element, and
2500 -- shift is the count so far computed.
2502 if Bytes_Big_Endian then
2504 Make_Op_Subtract (Loc,
2505 Left_Opnd => Make_Integer_Literal (Loc, Osiz - Csiz),
2506 Right_Opnd => Shift);
2509 Set_Parent (Shift, N);
2510 Set_Parent (Obj, N);
2511 Analyze_And_Resolve (Obj, Otyp, Suppress => All_Checks);
2512 Analyze_And_Resolve (Shift, Standard_Integer, Suppress => All_Checks);
2514 -- Make sure final type of object is the appropriate packed type
2516 Set_Etype (Obj, Otyp);
2518 end Setup_Inline_Packed_Array_Reference;