1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2006, 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 2, 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 COPYING. If not, write --
19 -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, USA. --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
25 ------------------------------------------------------------------------------
27 with Atree
; use Atree
;
28 with Checks
; use Checks
;
29 with Einfo
; use Einfo
;
30 with Errout
; use Errout
;
31 with Exp_Dbug
; use Exp_Dbug
;
32 with Exp_Util
; use Exp_Util
;
33 with Nlists
; use Nlists
;
34 with Nmake
; use Nmake
;
35 with Rtsfind
; use Rtsfind
;
37 with Sem_Ch3
; use Sem_Ch3
;
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.
302 Set_Id
: constant E_Array
:=
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.
372 SetU_Id
: constant E_Array
:=
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
473 Expr
: Node_Id
) return Node_Id
;
474 -- The packed array code does unchecked conversions which in some cases
475 -- may involve non-discrete types with differing sizes. The semantics of
476 -- such conversions is potentially endian dependent, and the effect we
477 -- want here for such a conversion is to do the conversion in size as
478 -- though numeric items are involved, and we extend or truncate on the
479 -- left side. This happens naturally in the little-endian case, but in
480 -- the big endian case we can get left justification, when what we want
481 -- is right justification. This routine does the unchecked conversion in
482 -- a stepwise manner to ensure that it gives the expected result. Hence
483 -- the name (RJ = Right justified). The parameters Typ and Expr are as
484 -- for the case of a normal Unchecked_Convert_To call.
486 procedure Setup_Enumeration_Packed_Array_Reference
(N
: Node_Id
);
487 -- This routine is called in the Get and Set case for arrays that are
488 -- packed but not bit-packed, meaning that they have at least one
489 -- subscript that is of an enumeration type with a non-standard
490 -- representation. This routine modifies the given node to properly
491 -- reference the corresponding packed array type.
493 procedure Setup_Inline_Packed_Array_Reference
496 Obj
: in out Node_Id
;
498 Shift
: out Node_Id
);
499 -- This procedure performs common processing on the N_Indexed_Component
500 -- parameter given as N, whose prefix is a reference to a packed array.
501 -- This is used for the get and set when the component size is 1,2,4
502 -- or for other component sizes when the packed array type is a modular
503 -- type (i.e. the cases that are handled with inline code).
507 -- N is the N_Indexed_Component node for the packed array reference
509 -- Atyp is the constrained array type (the actual subtype has been
510 -- computed if necessary to obtain the constraints, but this is still
511 -- the original array type, not the Packed_Array_Type value).
513 -- Obj is the object which is to be indexed. It is always of type Atyp.
517 -- Obj is the object containing the desired bit field. It is of type
518 -- Unsigned, Long_Unsigned, or Long_Long_Unsigned, and is either the
519 -- entire value, for the small static case, or the proper selected byte
520 -- from the array in the large or dynamic case. This node is analyzed
521 -- and resolved on return.
523 -- Shift is a node representing the shift count to be used in the
524 -- rotate right instruction that positions the field for access.
525 -- This node is analyzed and resolved on return.
527 -- Cmask is a mask corresponding to the width of the component field.
528 -- Its value is 2 ** Csize - 1 (e.g. 2#1111# for component size of 4).
530 -- Note: in some cases the call to this routine may generate actions
531 -- (for handling multi-use references and the generation of the packed
532 -- array type on the fly). Such actions are inserted into the tree
533 -- directly using Insert_Action.
535 ------------------------------
536 -- Compute_Linear_Subcsript --
537 ------------------------------
539 procedure Compute_Linear_Subscript
542 Subscr
: out Node_Id
)
544 Loc
: constant Source_Ptr
:= Sloc
(N
);
553 -- Loop through dimensions
555 Indx
:= First_Index
(Atyp
);
556 Oldsub
:= First
(Expressions
(N
));
558 while Present
(Indx
) loop
559 Styp
:= Etype
(Indx
);
560 Newsub
:= Relocate_Node
(Oldsub
);
562 -- Get expression for the subscript value. First, if Do_Range_Check
563 -- is set on a subscript, then we must do a range check against the
564 -- original bounds (not the bounds of the packed array type). We do
565 -- this by introducing a subtype conversion.
567 if Do_Range_Check
(Newsub
)
568 and then Etype
(Newsub
) /= Styp
570 Newsub
:= Convert_To
(Styp
, Newsub
);
573 -- Now evolve the expression for the subscript. First convert
574 -- the subscript to be zero based and of an integer type.
576 -- Case of integer type, where we just subtract to get lower bound
578 if Is_Integer_Type
(Styp
) then
580 -- If length of integer type is smaller than standard integer,
581 -- then we convert to integer first, then do the subtract
583 -- Integer (subscript) - Integer (Styp'First)
585 if Esize
(Styp
) < Esize
(Standard_Integer
) then
587 Make_Op_Subtract
(Loc
,
588 Left_Opnd
=> Convert_To
(Standard_Integer
, Newsub
),
590 Convert_To
(Standard_Integer
,
591 Make_Attribute_Reference
(Loc
,
592 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
593 Attribute_Name
=> Name_First
)));
595 -- For larger integer types, subtract first, then convert to
596 -- integer, this deals with strange long long integer bounds.
598 -- Integer (subscript - Styp'First)
602 Convert_To
(Standard_Integer
,
603 Make_Op_Subtract
(Loc
,
606 Make_Attribute_Reference
(Loc
,
607 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
608 Attribute_Name
=> Name_First
)));
611 -- For the enumeration case, we have to use 'Pos to get the value
612 -- to work with before subtracting the lower bound.
614 -- Integer (Styp'Pos (subscr)) - Integer (Styp'Pos (Styp'First));
616 -- This is not quite right for bizarre cases where the size of the
617 -- enumeration type is > Integer'Size bits due to rep clause ???
620 pragma Assert
(Is_Enumeration_Type
(Styp
));
623 Make_Op_Subtract
(Loc
,
624 Left_Opnd
=> Convert_To
(Standard_Integer
,
625 Make_Attribute_Reference
(Loc
,
626 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
627 Attribute_Name
=> Name_Pos
,
628 Expressions
=> New_List
(Newsub
))),
631 Convert_To
(Standard_Integer
,
632 Make_Attribute_Reference
(Loc
,
633 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
634 Attribute_Name
=> Name_Pos
,
635 Expressions
=> New_List
(
636 Make_Attribute_Reference
(Loc
,
637 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
638 Attribute_Name
=> Name_First
)))));
641 Set_Paren_Count
(Newsub
, 1);
643 -- For the first subscript, we just copy that subscript value
648 -- Otherwise, we must multiply what we already have by the current
649 -- stride and then add in the new value to the evolving subscript.
655 Make_Op_Multiply
(Loc
,
658 Make_Attribute_Reference
(Loc
,
659 Attribute_Name
=> Name_Range_Length
,
660 Prefix
=> New_Occurrence_Of
(Styp
, Loc
))),
661 Right_Opnd
=> Newsub
);
664 -- Move to next subscript
669 end Compute_Linear_Subscript
;
671 -------------------------
672 -- Convert_To_PAT_Type --
673 -------------------------
675 -- The PAT is always obtained from the actual subtype
677 procedure Convert_To_PAT_Type
(Aexp
: Node_Id
) is
681 Convert_To_Actual_Subtype
(Aexp
);
682 Act_ST
:= Underlying_Type
(Etype
(Aexp
));
683 Create_Packed_Array_Type
(Act_ST
);
685 -- Just replace the etype with the packed array type. This works because
686 -- the expression will not be further analyzed, and Gigi considers the
687 -- two types equivalent in any case.
689 -- This is not strictly the case ??? If the reference is an actual in
690 -- call, the expansion of the prefix is delayed, and must be reanalyzed,
691 -- see Reset_Packed_Prefix. On the other hand, if the prefix is a simple
692 -- array reference, reanalysis can produce spurious type errors when the
693 -- PAT type is replaced again with the original type of the array. Same
694 -- for the case of a dereference. The following is correct and minimal,
695 -- but the handling of more complex packed expressions in actuals is
696 -- confused. Probably the problem only remains for actuals in calls.
698 Set_Etype
(Aexp
, Packed_Array_Type
(Act_ST
));
700 if Is_Entity_Name
(Aexp
)
702 (Nkind
(Aexp
) = N_Indexed_Component
703 and then Is_Entity_Name
(Prefix
(Aexp
)))
704 or else Nkind
(Aexp
) = N_Explicit_Dereference
708 end Convert_To_PAT_Type
;
710 ------------------------------
711 -- Create_Packed_Array_Type --
712 ------------------------------
714 procedure Create_Packed_Array_Type
(Typ
: Entity_Id
) is
715 Loc
: constant Source_Ptr
:= Sloc
(Typ
);
716 Ctyp
: constant Entity_Id
:= Component_Type
(Typ
);
717 Csize
: constant Uint
:= Component_Size
(Typ
);
732 procedure Install_PAT
;
733 -- This procedure is called with Decl set to the declaration for the
734 -- packed array type. It creates the type and installs it as required.
736 procedure Set_PB_Type
;
737 -- Sets PB_Type to Packed_Bytes{1,2,4} as required by the alignment
738 -- requirements (see documentation in the spec of this package).
744 procedure Install_PAT
is
745 Pushed_Scope
: Boolean := False;
748 -- We do not want to put the declaration we have created in the tree
749 -- since it is often hard, and sometimes impossible to find a proper
750 -- place for it (the impossible case arises for a packed array type
751 -- with bounds depending on the discriminant, a declaration cannot
752 -- be put inside the record, and the reference to the discriminant
753 -- cannot be outside the record).
755 -- The solution is to analyze the declaration while temporarily
756 -- attached to the tree at an appropriate point, and then we install
757 -- the resulting type as an Itype in the packed array type field of
758 -- the original type, so that no explicit declaration is required.
760 -- Note: the packed type is created in the scope of its parent
761 -- type. There are at least some cases where the current scope
762 -- is deeper, and so when this is the case, we temporarily reset
763 -- the scope for the definition. This is clearly safe, since the
764 -- first use of the packed array type will be the implicit
765 -- reference from the corresponding unpacked type when it is
768 if Is_Itype
(Typ
) then
769 Set_Parent
(Decl
, Associated_Node_For_Itype
(Typ
));
771 Set_Parent
(Decl
, Declaration_Node
(Typ
));
774 if Scope
(Typ
) /= Current_Scope
then
775 New_Scope
(Scope
(Typ
));
776 Pushed_Scope
:= True;
779 Set_Is_Itype
(PAT
, True);
780 Set_Packed_Array_Type
(Typ
, PAT
);
781 Analyze
(Decl
, Suppress
=> All_Checks
);
787 -- Set Esize and RM_Size to the actual size of the packed object
788 -- Do not reset RM_Size if already set, as happens in the case
789 -- of a modular type.
791 Set_Esize
(PAT
, PASize
);
793 if Unknown_RM_Size
(PAT
) then
794 Set_RM_Size
(PAT
, PASize
);
797 -- Set remaining fields of packed array type
799 Init_Alignment
(PAT
);
800 Set_Parent
(PAT
, Empty
);
801 Set_Associated_Node_For_Itype
(PAT
, Typ
);
802 Set_Is_Packed_Array_Type
(PAT
, True);
803 Set_Original_Array_Type
(PAT
, Typ
);
805 -- We definitely do not want to delay freezing for packed array
806 -- types. This is of particular importance for the itypes that
807 -- are generated for record components depending on discriminants
808 -- where there is no place to put the freeze node.
810 Set_Has_Delayed_Freeze
(PAT
, False);
811 Set_Has_Delayed_Freeze
(Etype
(PAT
), False);
813 -- If we did allocate a freeze node, then clear out the reference
814 -- since it is obsolete (should we delete the freeze node???)
816 Set_Freeze_Node
(PAT
, Empty
);
817 Set_Freeze_Node
(Etype
(PAT
), Empty
);
824 procedure Set_PB_Type
is
826 -- If the user has specified an explicit alignment for the
827 -- type or component, take it into account.
829 if Csize
<= 2 or else Csize
= 4 or else Csize
mod 2 /= 0
830 or else Alignment
(Typ
) = 1
831 or else Component_Alignment
(Typ
) = Calign_Storage_Unit
833 PB_Type
:= RTE
(RE_Packed_Bytes1
);
835 elsif Csize
mod 4 /= 0
836 or else Alignment
(Typ
) = 2
838 PB_Type
:= RTE
(RE_Packed_Bytes2
);
841 PB_Type
:= RTE
(RE_Packed_Bytes4
);
845 -- Start of processing for Create_Packed_Array_Type
848 -- If we already have a packed array type, nothing to do
850 if Present
(Packed_Array_Type
(Typ
)) then
854 -- If our immediate ancestor subtype is constrained, and it already
855 -- has a packed array type, then just share the same type, since the
856 -- bounds must be the same. If the ancestor is not an array type but
857 -- a private type, as can happen with multiple instantiations, create
858 -- a new packed type, to avoid privacy issues.
860 if Ekind
(Typ
) = E_Array_Subtype
then
861 Ancest
:= Ancestor_Subtype
(Typ
);
864 and then Is_Array_Type
(Ancest
)
865 and then Is_Constrained
(Ancest
)
866 and then Present
(Packed_Array_Type
(Ancest
))
868 Set_Packed_Array_Type
(Typ
, Packed_Array_Type
(Ancest
));
873 -- We preset the result type size from the size of the original array
874 -- type, since this size clearly belongs to the packed array type. The
875 -- size of the conceptual unpacked type is always set to unknown.
877 PASize
:= Esize
(Typ
);
879 -- Case of an array where at least one index is of an enumeration
880 -- type with a non-standard representation, but the component size
881 -- is not appropriate for bit packing. This is the case where we
882 -- have Is_Packed set (we would never be in this unit otherwise),
883 -- but Is_Bit_Packed_Array is false.
885 -- Note that if the component size is appropriate for bit packing,
886 -- then the circuit for the computation of the subscript properly
887 -- deals with the non-standard enumeration type case by taking the
890 if not Is_Bit_Packed_Array
(Typ
) then
892 -- Here we build a declaration:
894 -- type tttP is array (index1, index2, ...) of component_type
896 -- where index1, index2, are the index types. These are the same
897 -- as the index types of the original array, except for the non-
898 -- standard representation enumeration type case, where we have
901 -- For the unconstrained array case, we use
905 -- For the constrained case, we use
907 -- Natural range Enum_Type'Pos (Enum_Type'First) ..
908 -- Enum_Type'Pos (Enum_Type'Last);
911 Make_Defining_Identifier
(Loc
,
912 Chars
=> New_External_Name
(Chars
(Typ
), 'P'));
914 Set_Packed_Array_Type
(Typ
, PAT
);
917 Indexes
: constant List_Id
:= New_List
;
919 Indx_Typ
: Entity_Id
;
924 Indx
:= First_Index
(Typ
);
926 while Present
(Indx
) loop
927 Indx_Typ
:= Etype
(Indx
);
929 Enum_Case
:= Is_Enumeration_Type
(Indx_Typ
)
930 and then Has_Non_Standard_Rep
(Indx_Typ
);
932 -- Unconstrained case
934 if not Is_Constrained
(Typ
) then
936 Indx_Typ
:= Standard_Natural
;
939 Append_To
(Indexes
, New_Occurrence_Of
(Indx_Typ
, Loc
));
944 if not Enum_Case
then
945 Append_To
(Indexes
, New_Occurrence_Of
(Indx_Typ
, Loc
));
949 Make_Subtype_Indication
(Loc
,
951 New_Occurrence_Of
(Standard_Natural
, Loc
),
953 Make_Range_Constraint
(Loc
,
957 Make_Attribute_Reference
(Loc
,
959 New_Occurrence_Of
(Indx_Typ
, Loc
),
960 Attribute_Name
=> Name_Pos
,
961 Expressions
=> New_List
(
962 Make_Attribute_Reference
(Loc
,
964 New_Occurrence_Of
(Indx_Typ
, Loc
),
965 Attribute_Name
=> Name_First
))),
968 Make_Attribute_Reference
(Loc
,
970 New_Occurrence_Of
(Indx_Typ
, Loc
),
971 Attribute_Name
=> Name_Pos
,
972 Expressions
=> New_List
(
973 Make_Attribute_Reference
(Loc
,
975 New_Occurrence_Of
(Indx_Typ
, Loc
),
976 Attribute_Name
=> Name_Last
)))))));
984 if not Is_Constrained
(Typ
) then
986 Make_Unconstrained_Array_Definition
(Loc
,
987 Subtype_Marks
=> Indexes
,
988 Component_Definition
=>
989 Make_Component_Definition
(Loc
,
990 Aliased_Present
=> False,
991 Subtype_Indication
=>
992 New_Occurrence_Of
(Ctyp
, Loc
)));
996 Make_Constrained_Array_Definition
(Loc
,
997 Discrete_Subtype_Definitions
=> Indexes
,
998 Component_Definition
=>
999 Make_Component_Definition
(Loc
,
1000 Aliased_Present
=> False,
1001 Subtype_Indication
=>
1002 New_Occurrence_Of
(Ctyp
, Loc
)));
1006 Make_Full_Type_Declaration
(Loc
,
1007 Defining_Identifier
=> PAT
,
1008 Type_Definition
=> Typedef
);
1011 -- Set type as packed array type and install it
1013 Set_Is_Packed_Array_Type
(PAT
);
1017 -- Case of bit-packing required for unconstrained array. We create
1018 -- a subtype that is equivalent to use Packed_Bytes{1,2,4} as needed.
1020 elsif not Is_Constrained
(Typ
) then
1022 Make_Defining_Identifier
(Loc
,
1023 Chars
=> Make_Packed_Array_Type_Name
(Typ
, Csize
));
1025 Set_Packed_Array_Type
(Typ
, PAT
);
1029 Make_Subtype_Declaration
(Loc
,
1030 Defining_Identifier
=> PAT
,
1031 Subtype_Indication
=> New_Occurrence_Of
(PB_Type
, Loc
));
1035 -- Remaining code is for the case of bit-packing for constrained array
1037 -- The name of the packed array subtype is
1041 -- where sss is the component size in bits and ttt is the name of
1042 -- the parent packed type.
1046 Make_Defining_Identifier
(Loc
,
1047 Chars
=> Make_Packed_Array_Type_Name
(Typ
, Csize
));
1049 Set_Packed_Array_Type
(Typ
, PAT
);
1051 -- Build an expression for the length of the array in bits.
1052 -- This is the product of the length of each of the dimensions
1058 Len_Expr
:= Empty
; -- suppress junk warning
1062 Make_Attribute_Reference
(Loc
,
1063 Attribute_Name
=> Name_Length
,
1064 Prefix
=> New_Occurrence_Of
(Typ
, Loc
),
1065 Expressions
=> New_List
(
1066 Make_Integer_Literal
(Loc
, J
)));
1069 Len_Expr
:= Len_Dim
;
1073 Make_Op_Multiply
(Loc
,
1074 Left_Opnd
=> Len_Expr
,
1075 Right_Opnd
=> Len_Dim
);
1079 exit when J
> Number_Dimensions
(Typ
);
1083 -- Temporarily attach the length expression to the tree and analyze
1084 -- and resolve it, so that we can test its value. We assume that the
1085 -- total length fits in type Integer. This expression may involve
1086 -- discriminants, so we treat it as a default/per-object expression.
1088 Set_Parent
(Len_Expr
, Typ
);
1089 Analyze_Per_Use_Expression
(Len_Expr
, Standard_Long_Long_Integer
);
1091 -- Use a modular type if possible. We can do this if we have
1092 -- static bounds, and the length is small enough, and the length
1093 -- is not zero. We exclude the zero length case because the size
1094 -- of things is always at least one, and the zero length object
1095 -- would have an anomalous size.
1097 if Compile_Time_Known_Value
(Len_Expr
) then
1098 Len_Bits
:= Expr_Value
(Len_Expr
) * Csize
;
1100 -- Check for size known to be too large
1103 Uint_2
** (Standard_Integer_Size
- 1) * System_Storage_Unit
1105 if System_Storage_Unit
= 8 then
1107 ("packed array size cannot exceed " &
1108 "Integer''Last bytes", Typ
);
1111 ("packed array size cannot exceed " &
1112 "Integer''Last storage units", Typ
);
1115 -- Reset length to arbitrary not too high value to continue
1117 Len_Expr
:= Make_Integer_Literal
(Loc
, 65535);
1118 Analyze_And_Resolve
(Len_Expr
, Standard_Long_Long_Integer
);
1121 -- We normally consider small enough to mean no larger than the
1122 -- value of System_Max_Binary_Modulus_Power, checking that in the
1123 -- case of values longer than word size, we have long shifts.
1127 (Len_Bits
<= System_Word_Size
1128 or else (Len_Bits
<= System_Max_Binary_Modulus_Power
1129 and then Support_Long_Shifts_On_Target
))
1131 -- Also test for alignment given. If an alignment is given which
1132 -- is smaller than the natural modular alignment, force the array
1133 -- of bytes representation to accommodate the alignment.
1136 (No
(Alignment_Clause
(Typ
))
1138 Alignment
(Typ
) >= ((Len_Bits
+ System_Storage_Unit
)
1139 / System_Storage_Unit
))
1141 -- We can use the modular type, it has the form:
1143 -- subtype tttPn is btyp
1144 -- range 0 .. 2 ** ((Typ'Length (1)
1145 -- * ... * Typ'Length (n)) * Csize) - 1;
1147 -- The bounds are statically known, and btyp is one
1148 -- of the unsigned types, depending on the length. If the
1149 -- type is its first subtype, i.e. it is a user-defined
1150 -- type, no object of the type will be larger, and it is
1151 -- worthwhile to use a small unsigned type.
1153 if Len_Bits
<= Standard_Short_Integer_Size
1154 and then First_Subtype
(Typ
) = Typ
1156 Btyp
:= RTE
(RE_Short_Unsigned
);
1158 elsif Len_Bits
<= Standard_Integer_Size
then
1159 Btyp
:= RTE
(RE_Unsigned
);
1161 elsif Len_Bits
<= Standard_Long_Integer_Size
then
1162 Btyp
:= RTE
(RE_Long_Unsigned
);
1165 Btyp
:= RTE
(RE_Long_Long_Unsigned
);
1168 Lit
:= Make_Integer_Literal
(Loc
, 2 ** Len_Bits
- 1);
1169 Set_Print_In_Hex
(Lit
);
1172 Make_Subtype_Declaration
(Loc
,
1173 Defining_Identifier
=> PAT
,
1174 Subtype_Indication
=>
1175 Make_Subtype_Indication
(Loc
,
1176 Subtype_Mark
=> New_Occurrence_Of
(Btyp
, Loc
),
1179 Make_Range_Constraint
(Loc
,
1183 Make_Integer_Literal
(Loc
, 0),
1184 High_Bound
=> Lit
))));
1186 if PASize
= Uint_0
then
1195 -- Could not use a modular type, for all other cases, we build
1196 -- a packed array subtype:
1199 -- System.Packed_Bytes{1,2,4} (0 .. (Bits + 7) / 8 - 1);
1201 -- Bits is the length of the array in bits
1208 Make_Op_Multiply
(Loc
,
1210 Make_Integer_Literal
(Loc
, Csize
),
1211 Right_Opnd
=> Len_Expr
),
1214 Make_Integer_Literal
(Loc
, 7));
1216 Set_Paren_Count
(Bits_U1
, 1);
1219 Make_Op_Subtract
(Loc
,
1221 Make_Op_Divide
(Loc
,
1222 Left_Opnd
=> Bits_U1
,
1223 Right_Opnd
=> Make_Integer_Literal
(Loc
, 8)),
1224 Right_Opnd
=> Make_Integer_Literal
(Loc
, 1));
1227 Make_Subtype_Declaration
(Loc
,
1228 Defining_Identifier
=> PAT
,
1229 Subtype_Indication
=>
1230 Make_Subtype_Indication
(Loc
,
1231 Subtype_Mark
=> New_Occurrence_Of
(PB_Type
, Loc
),
1233 Make_Index_Or_Discriminant_Constraint
(Loc
,
1234 Constraints
=> New_List
(
1237 Make_Integer_Literal
(Loc
, 0),
1239 Convert_To
(Standard_Integer
, PAT_High
))))));
1243 -- Currently the code in this unit requires that packed arrays
1244 -- represented by non-modular arrays of bytes be on a byte
1245 -- boundary for bit sizes handled by System.Pack_nn units.
1246 -- That's because these units assume the array being accessed
1247 -- starts on a byte boundary.
1249 if Get_Id
(UI_To_Int
(Csize
)) /= RE_Null
then
1250 Set_Must_Be_On_Byte_Boundary
(Typ
);
1253 end Create_Packed_Array_Type
;
1255 -----------------------------------
1256 -- Expand_Bit_Packed_Element_Set --
1257 -----------------------------------
1259 procedure Expand_Bit_Packed_Element_Set
(N
: Node_Id
) is
1260 Loc
: constant Source_Ptr
:= Sloc
(N
);
1261 Lhs
: constant Node_Id
:= Name
(N
);
1263 Ass_OK
: constant Boolean := Assignment_OK
(Lhs
);
1264 -- Used to preserve assignment OK status when assignment is rewritten
1266 Rhs
: Node_Id
:= Expression
(N
);
1267 -- Initially Rhs is the right hand side value, it will be replaced
1268 -- later by an appropriate unchecked conversion for the assignment.
1278 -- The expression for the shift value that is required
1280 Shift_Used
: Boolean := False;
1281 -- Set True if Shift has been used in the generated code at least
1282 -- once, so that it must be duplicated if used again
1287 Rhs_Val_Known
: Boolean;
1289 -- If the value of the right hand side as an integer constant is
1290 -- known at compile time, Rhs_Val_Known is set True, and Rhs_Val
1291 -- contains the value. Otherwise Rhs_Val_Known is set False, and
1292 -- the Rhs_Val is undefined.
1294 function Get_Shift
return Node_Id
;
1295 -- Function used to get the value of Shift, making sure that it
1296 -- gets duplicated if the function is called more than once.
1302 function Get_Shift
return Node_Id
is
1304 -- If we used the shift value already, then duplicate it. We
1305 -- set a temporary parent in case actions have to be inserted.
1308 Set_Parent
(Shift
, N
);
1309 return Duplicate_Subexpr_No_Checks
(Shift
);
1311 -- If first time, use Shift unchanged, and set flag for first use
1319 -- Start of processing for Expand_Bit_Packed_Element_Set
1322 pragma Assert
(Is_Bit_Packed_Array
(Etype
(Prefix
(Lhs
))));
1324 Obj
:= Relocate_Node
(Prefix
(Lhs
));
1325 Convert_To_Actual_Subtype
(Obj
);
1326 Atyp
:= Etype
(Obj
);
1327 PAT
:= Packed_Array_Type
(Atyp
);
1328 Ctyp
:= Component_Type
(Atyp
);
1329 Csiz
:= UI_To_Int
(Component_Size
(Atyp
));
1331 -- We convert the right hand side to the proper subtype to ensure
1332 -- that an appropriate range check is made (since the normal range
1333 -- check from assignment will be lost in the transformations). This
1334 -- conversion is analyzed immediately so that subsequent processing
1335 -- can work with an analyzed Rhs (and e.g. look at its Etype)
1337 -- If the right-hand side is a string literal, create a temporary for
1338 -- it, constant-folding is not ready to wrap the bit representation
1339 -- of a string literal.
1341 if Nkind
(Rhs
) = N_String_Literal
then
1346 Make_Object_Declaration
(Loc
,
1347 Defining_Identifier
=>
1348 Make_Defining_Identifier
(Loc
, New_Internal_Name
('T')),
1349 Object_Definition
=> New_Occurrence_Of
(Ctyp
, Loc
),
1350 Expression
=> New_Copy_Tree
(Rhs
));
1352 Insert_Actions
(N
, New_List
(Decl
));
1353 Rhs
:= New_Occurrence_Of
(Defining_Identifier
(Decl
), Loc
);
1357 Rhs
:= Convert_To
(Ctyp
, Rhs
);
1358 Set_Parent
(Rhs
, N
);
1359 Analyze_And_Resolve
(Rhs
, Ctyp
);
1361 -- Case of component size 1,2,4 or any component size for the modular
1362 -- case. These are the cases for which we can inline the code.
1364 if Csiz
= 1 or else Csiz
= 2 or else Csiz
= 4
1365 or else (Present
(PAT
) and then Is_Modular_Integer_Type
(PAT
))
1367 Setup_Inline_Packed_Array_Reference
(Lhs
, Atyp
, Obj
, Cmask
, Shift
);
1369 -- The statement to be generated is:
1371 -- Obj := atyp!((Obj and Mask1) or (shift_left (rhs, shift)))
1373 -- where mask1 is obtained by shifting Cmask left Shift bits
1374 -- and then complementing the result.
1376 -- the "and Mask1" is omitted if rhs is constant and all 1 bits
1378 -- the "or ..." is omitted if rhs is constant and all 0 bits
1380 -- rhs is converted to the appropriate type
1382 -- The result is converted back to the array type, since
1383 -- otherwise we lose knowledge of the packed nature.
1385 -- Determine if right side is all 0 bits or all 1 bits
1387 if Compile_Time_Known_Value
(Rhs
) then
1388 Rhs_Val
:= Expr_Rep_Value
(Rhs
);
1389 Rhs_Val_Known
:= True;
1391 -- The following test catches the case of an unchecked conversion
1392 -- of an integer literal. This results from optimizing aggregates
1395 elsif Nkind
(Rhs
) = N_Unchecked_Type_Conversion
1396 and then Compile_Time_Known_Value
(Expression
(Rhs
))
1398 Rhs_Val
:= Expr_Rep_Value
(Expression
(Rhs
));
1399 Rhs_Val_Known
:= True;
1403 Rhs_Val_Known
:= False;
1406 -- Some special checks for the case where the right hand value
1407 -- is known at compile time. Basically we have to take care of
1408 -- the implicit conversion to the subtype of the component object.
1410 if Rhs_Val_Known
then
1412 -- If we have a biased component type then we must manually do
1413 -- the biasing, since we are taking responsibility in this case
1414 -- for constructing the exact bit pattern to be used.
1416 if Has_Biased_Representation
(Ctyp
) then
1417 Rhs_Val
:= Rhs_Val
- Expr_Rep_Value
(Type_Low_Bound
(Ctyp
));
1420 -- For a negative value, we manually convert the twos complement
1421 -- value to a corresponding unsigned value, so that the proper
1422 -- field width is maintained. If we did not do this, we would
1423 -- get too many leading sign bits later on.
1426 Rhs_Val
:= 2 ** UI_From_Int
(Csiz
) + Rhs_Val
;
1430 New_Lhs
:= Duplicate_Subexpr
(Obj
, True);
1431 New_Rhs
:= Duplicate_Subexpr_No_Checks
(Obj
);
1433 -- First we deal with the "and"
1435 if not Rhs_Val_Known
or else Rhs_Val
/= Cmask
then
1441 if Compile_Time_Known_Value
(Shift
) then
1443 Make_Integer_Literal
(Loc
,
1444 Modulus
(Etype
(Obj
)) - 1 -
1445 (Cmask
* (2 ** Expr_Value
(Get_Shift
))));
1446 Set_Print_In_Hex
(Mask1
);
1449 Lit
:= Make_Integer_Literal
(Loc
, Cmask
);
1450 Set_Print_In_Hex
(Lit
);
1453 Right_Opnd
=> Make_Shift_Left
(Lit
, Get_Shift
));
1458 Left_Opnd
=> New_Rhs
,
1459 Right_Opnd
=> Mask1
);
1463 -- Then deal with the "or"
1465 if not Rhs_Val_Known
or else Rhs_Val
/= 0 then
1469 procedure Fixup_Rhs
;
1470 -- Adjust Rhs by bias if biased representation for components
1471 -- or remove extraneous high order sign bits if signed.
1473 procedure Fixup_Rhs
is
1474 Etyp
: constant Entity_Id
:= Etype
(Rhs
);
1477 -- For biased case, do the required biasing by simply
1478 -- converting to the biased subtype (the conversion
1479 -- will generate the required bias).
1481 if Has_Biased_Representation
(Ctyp
) then
1482 Rhs
:= Convert_To
(Ctyp
, Rhs
);
1484 -- For a signed integer type that is not biased, generate
1485 -- a conversion to unsigned to strip high order sign bits.
1487 elsif Is_Signed_Integer_Type
(Ctyp
) then
1488 Rhs
:= Unchecked_Convert_To
(RTE
(Bits_Id
(Csiz
)), Rhs
);
1491 -- Set Etype, since it can be referenced before the
1492 -- node is completely analyzed.
1494 Set_Etype
(Rhs
, Etyp
);
1496 -- We now need to do an unchecked conversion of the
1497 -- result to the target type, but it is important that
1498 -- this conversion be a right justified conversion and
1499 -- not a left justified conversion.
1501 Rhs
:= RJ_Unchecked_Convert_To
(Etype
(Obj
), Rhs
);
1507 and then Compile_Time_Known_Value
(Get_Shift
)
1510 Make_Integer_Literal
(Loc
,
1511 Rhs_Val
* (2 ** Expr_Value
(Get_Shift
)));
1512 Set_Print_In_Hex
(Or_Rhs
);
1515 -- We have to convert the right hand side to Etype (Obj).
1516 -- A special case case arises if what we have now is a Val
1517 -- attribute reference whose expression type is Etype (Obj).
1518 -- This happens for assignments of fields from the same
1519 -- array. In this case we get the required right hand side
1520 -- by simply removing the inner attribute reference.
1522 if Nkind
(Rhs
) = N_Attribute_Reference
1523 and then Attribute_Name
(Rhs
) = Name_Val
1524 and then Etype
(First
(Expressions
(Rhs
))) = Etype
(Obj
)
1526 Rhs
:= Relocate_Node
(First
(Expressions
(Rhs
)));
1529 -- If the value of the right hand side is a known integer
1530 -- value, then just replace it by an untyped constant,
1531 -- which will be properly retyped when we analyze and
1532 -- resolve the expression.
1534 elsif Rhs_Val_Known
then
1536 -- Note that Rhs_Val has already been normalized to
1537 -- be an unsigned value with the proper number of bits.
1540 Make_Integer_Literal
(Loc
, Rhs_Val
);
1542 -- Otherwise we need an unchecked conversion
1548 Or_Rhs
:= Make_Shift_Left
(Rhs
, Get_Shift
);
1551 if Nkind
(New_Rhs
) = N_Op_And
then
1552 Set_Paren_Count
(New_Rhs
, 1);
1557 Left_Opnd
=> New_Rhs
,
1558 Right_Opnd
=> Or_Rhs
);
1562 -- Now do the rewrite
1565 Make_Assignment_Statement
(Loc
,
1568 Unchecked_Convert_To
(Etype
(New_Lhs
), New_Rhs
)));
1569 Set_Assignment_OK
(Name
(N
), Ass_OK
);
1571 -- All other component sizes for non-modular case
1576 -- Set_nn (Arr'address, Subscr, Bits_nn!(Rhs))
1578 -- where Subscr is the computed linear subscript
1581 Bits_nn
: constant Entity_Id
:= RTE
(Bits_Id
(Csiz
));
1587 if No
(Bits_nn
) then
1589 -- Error, most likely High_Integrity_Mode restriction
1594 -- Acquire proper Set entity. We use the aligned or unaligned
1595 -- case as appropriate.
1597 if Known_Aligned_Enough
(Obj
, Csiz
) then
1598 Set_nn
:= RTE
(Set_Id
(Csiz
));
1600 Set_nn
:= RTE
(SetU_Id
(Csiz
));
1603 -- Now generate the set reference
1605 Obj
:= Relocate_Node
(Prefix
(Lhs
));
1606 Convert_To_Actual_Subtype
(Obj
);
1607 Atyp
:= Etype
(Obj
);
1608 Compute_Linear_Subscript
(Atyp
, Lhs
, Subscr
);
1610 -- Below we must make the assumption that Obj is
1611 -- at least byte aligned, since otherwise its address
1612 -- cannot be taken. The assumption holds since the
1613 -- only arrays that can be misaligned are small packed
1614 -- arrays which are implemented as a modular type, and
1615 -- that is not the case here.
1618 Make_Procedure_Call_Statement
(Loc
,
1619 Name
=> New_Occurrence_Of
(Set_nn
, Loc
),
1620 Parameter_Associations
=> New_List
(
1621 Make_Attribute_Reference
(Loc
,
1622 Attribute_Name
=> Name_Address
,
1625 Unchecked_Convert_To
(Bits_nn
,
1626 Convert_To
(Ctyp
, Rhs
)))));
1631 Analyze
(N
, Suppress
=> All_Checks
);
1632 end Expand_Bit_Packed_Element_Set
;
1634 -------------------------------------
1635 -- Expand_Packed_Address_Reference --
1636 -------------------------------------
1638 procedure Expand_Packed_Address_Reference
(N
: Node_Id
) is
1639 Loc
: constant Source_Ptr
:= Sloc
(N
);
1651 -- We build up an expression serially that has the form
1653 -- outer_object'Address
1654 -- + (linear-subscript * component_size for each array reference
1655 -- + field'Bit_Position for each record field
1657 -- + ...) / Storage_Unit;
1659 -- Some additional conversions are required to deal with the addition
1660 -- operation, which is not normally visible to generated code.
1663 Ploc
:= Sloc
(Pref
);
1665 if Nkind
(Pref
) = N_Indexed_Component
then
1666 Convert_To_Actual_Subtype
(Prefix
(Pref
));
1667 Atyp
:= Etype
(Prefix
(Pref
));
1668 Compute_Linear_Subscript
(Atyp
, Pref
, Subscr
);
1671 Make_Op_Multiply
(Ploc
,
1672 Left_Opnd
=> Subscr
,
1674 Make_Attribute_Reference
(Ploc
,
1675 Prefix
=> New_Occurrence_Of
(Atyp
, Ploc
),
1676 Attribute_Name
=> Name_Component_Size
));
1678 elsif Nkind
(Pref
) = N_Selected_Component
then
1680 Make_Attribute_Reference
(Ploc
,
1681 Prefix
=> Selector_Name
(Pref
),
1682 Attribute_Name
=> Name_Bit_Position
);
1688 Term
:= Convert_To
(RTE
(RE_Integer_Address
), Term
);
1697 Right_Opnd
=> Term
);
1700 Pref
:= Prefix
(Pref
);
1704 Unchecked_Convert_To
(RTE
(RE_Address
),
1707 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
1708 Make_Attribute_Reference
(Loc
,
1710 Attribute_Name
=> Name_Address
)),
1713 Make_Op_Divide
(Loc
,
1716 Make_Integer_Literal
(Loc
, System_Storage_Unit
)))));
1718 Analyze_And_Resolve
(N
, RTE
(RE_Address
));
1719 end Expand_Packed_Address_Reference
;
1721 ------------------------------------
1722 -- Expand_Packed_Boolean_Operator --
1723 ------------------------------------
1725 -- This routine expands "a op b" for the packed cases
1727 procedure Expand_Packed_Boolean_Operator
(N
: Node_Id
) is
1728 Loc
: constant Source_Ptr
:= Sloc
(N
);
1729 Typ
: constant Entity_Id
:= Etype
(N
);
1730 L
: constant Node_Id
:= Relocate_Node
(Left_Opnd
(N
));
1731 R
: constant Node_Id
:= Relocate_Node
(Right_Opnd
(N
));
1738 Convert_To_Actual_Subtype
(L
);
1739 Convert_To_Actual_Subtype
(R
);
1741 Ensure_Defined
(Etype
(L
), N
);
1742 Ensure_Defined
(Etype
(R
), N
);
1744 Apply_Length_Check
(R
, Etype
(L
));
1749 -- First an odd and silly test. We explicitly check for the XOR
1750 -- case where the component type is True .. True, since this will
1751 -- raise constraint error. A special check is required since CE
1752 -- will not be required other wise (cf Expand_Packed_Not).
1754 -- No such check is required for AND and OR, since for both these
1755 -- cases False op False = False, and True op True = True.
1757 if Nkind
(N
) = N_Op_Xor
then
1759 CT
: constant Entity_Id
:= Component_Type
(Rtyp
);
1760 BT
: constant Entity_Id
:= Base_Type
(CT
);
1764 Make_Raise_Constraint_Error
(Loc
,
1770 Make_Attribute_Reference
(Loc
,
1771 Prefix
=> New_Occurrence_Of
(CT
, Loc
),
1772 Attribute_Name
=> Name_First
),
1776 New_Occurrence_Of
(Standard_True
, Loc
))),
1781 Make_Attribute_Reference
(Loc
,
1782 Prefix
=> New_Occurrence_Of
(CT
, Loc
),
1783 Attribute_Name
=> Name_Last
),
1787 New_Occurrence_Of
(Standard_True
, Loc
)))),
1788 Reason
=> CE_Range_Check_Failed
));
1792 -- Now that that silliness is taken care of, get packed array type
1794 Convert_To_PAT_Type
(L
);
1795 Convert_To_PAT_Type
(R
);
1799 -- For the modular case, we expand a op b into
1801 -- rtyp!(pat!(a) op pat!(b))
1803 -- where rtyp is the Etype of the left operand. Note that we do not
1804 -- convert to the base type, since this would be unconstrained, and
1805 -- hence not have a corresponding packed array type set.
1807 -- Note that both operands must be modular for this code to be used
1809 if Is_Modular_Integer_Type
(PAT
)
1811 Is_Modular_Integer_Type
(Etype
(R
))
1817 if Nkind
(N
) = N_Op_And
then
1818 P
:= Make_Op_And
(Loc
, L
, R
);
1820 elsif Nkind
(N
) = N_Op_Or
then
1821 P
:= Make_Op_Or
(Loc
, L
, R
);
1823 else -- Nkind (N) = N_Op_Xor
1824 P
:= Make_Op_Xor
(Loc
, L
, R
);
1827 Rewrite
(N
, Unchecked_Convert_To
(Rtyp
, P
));
1830 -- For the array case, we insert the actions
1834 -- System.Bitops.Bit_And/Or/Xor
1836 -- Ltype'Length * Ltype'Component_Size;
1838 -- Rtype'Length * Rtype'Component_Size
1841 -- where Left and Right are the Packed_Bytes{1,2,4} operands and
1842 -- the second argument and fourth arguments are the lengths of the
1843 -- operands in bits. Then we replace the expression by a reference
1846 -- Note that if we are mixing a modular and array operand, everything
1847 -- works fine, since we ensure that the modular representation has the
1848 -- same physical layout as the array representation (that's what the
1849 -- left justified modular stuff in the big-endian case is about).
1853 Result_Ent
: constant Entity_Id
:=
1854 Make_Defining_Identifier
(Loc
,
1855 Chars
=> New_Internal_Name
('T'));
1860 if Nkind
(N
) = N_Op_And
then
1863 elsif Nkind
(N
) = N_Op_Or
then
1866 else -- Nkind (N) = N_Op_Xor
1870 Insert_Actions
(N
, New_List
(
1872 Make_Object_Declaration
(Loc
,
1873 Defining_Identifier
=> Result_Ent
,
1874 Object_Definition
=> New_Occurrence_Of
(Ltyp
, Loc
)),
1876 Make_Procedure_Call_Statement
(Loc
,
1877 Name
=> New_Occurrence_Of
(RTE
(E_Id
), Loc
),
1878 Parameter_Associations
=> New_List
(
1880 Make_Byte_Aligned_Attribute_Reference
(Loc
,
1881 Attribute_Name
=> Name_Address
,
1884 Make_Op_Multiply
(Loc
,
1886 Make_Attribute_Reference
(Loc
,
1889 (Etype
(First_Index
(Ltyp
)), Loc
),
1890 Attribute_Name
=> Name_Range_Length
),
1892 Make_Integer_Literal
(Loc
, Component_Size
(Ltyp
))),
1894 Make_Byte_Aligned_Attribute_Reference
(Loc
,
1895 Attribute_Name
=> Name_Address
,
1898 Make_Op_Multiply
(Loc
,
1900 Make_Attribute_Reference
(Loc
,
1903 (Etype
(First_Index
(Rtyp
)), Loc
),
1904 Attribute_Name
=> Name_Range_Length
),
1906 Make_Integer_Literal
(Loc
, Component_Size
(Rtyp
))),
1908 Make_Byte_Aligned_Attribute_Reference
(Loc
,
1909 Attribute_Name
=> Name_Address
,
1910 Prefix
=> New_Occurrence_Of
(Result_Ent
, Loc
))))));
1913 New_Occurrence_Of
(Result_Ent
, Loc
));
1917 Analyze_And_Resolve
(N
, Typ
, Suppress
=> All_Checks
);
1918 end Expand_Packed_Boolean_Operator
;
1920 -------------------------------------
1921 -- Expand_Packed_Element_Reference --
1922 -------------------------------------
1924 procedure Expand_Packed_Element_Reference
(N
: Node_Id
) is
1925 Loc
: constant Source_Ptr
:= Sloc
(N
);
1937 -- If not bit packed, we have the enumeration case, which is easily
1938 -- dealt with (just adjust the subscripts of the indexed component)
1940 -- Note: this leaves the result as an indexed component, which is
1941 -- still a variable, so can be used in the assignment case, as is
1942 -- required in the enumeration case.
1944 if not Is_Bit_Packed_Array
(Etype
(Prefix
(N
))) then
1945 Setup_Enumeration_Packed_Array_Reference
(N
);
1949 -- Remaining processing is for the bit-packed case
1951 Obj
:= Relocate_Node
(Prefix
(N
));
1952 Convert_To_Actual_Subtype
(Obj
);
1953 Atyp
:= Etype
(Obj
);
1954 PAT
:= Packed_Array_Type
(Atyp
);
1955 Ctyp
:= Component_Type
(Atyp
);
1956 Csiz
:= UI_To_Int
(Component_Size
(Atyp
));
1958 -- Case of component size 1,2,4 or any component size for the modular
1959 -- case. These are the cases for which we can inline the code.
1961 if Csiz
= 1 or else Csiz
= 2 or else Csiz
= 4
1962 or else (Present
(PAT
) and then Is_Modular_Integer_Type
(PAT
))
1964 Setup_Inline_Packed_Array_Reference
(N
, Atyp
, Obj
, Cmask
, Shift
);
1965 Lit
:= Make_Integer_Literal
(Loc
, Cmask
);
1966 Set_Print_In_Hex
(Lit
);
1968 -- We generate a shift right to position the field, followed by a
1969 -- masking operation to extract the bit field, and we finally do an
1970 -- unchecked conversion to convert the result to the required target.
1972 -- Note that the unchecked conversion automatically deals with the
1973 -- bias if we are dealing with a biased representation. What will
1974 -- happen is that we temporarily generate the biased representation,
1975 -- but almost immediately that will be converted to the original
1976 -- unbiased component type, and the bias will disappear.
1980 Left_Opnd
=> Make_Shift_Right
(Obj
, Shift
),
1983 -- We neded to analyze this before we do the unchecked convert
1984 -- below, but we need it temporarily attached to the tree for
1985 -- this analysis (hence the temporary Set_Parent call).
1987 Set_Parent
(Arg
, Parent
(N
));
1988 Analyze_And_Resolve
(Arg
);
1991 RJ_Unchecked_Convert_To
(Ctyp
, Arg
));
1993 -- All other component sizes for non-modular case
1998 -- Component_Type!(Get_nn (Arr'address, Subscr))
2000 -- where Subscr is the computed linear subscript
2007 -- Acquire proper Get entity. We use the aligned or unaligned
2008 -- case as appropriate.
2010 if Known_Aligned_Enough
(Obj
, Csiz
) then
2011 Get_nn
:= RTE
(Get_Id
(Csiz
));
2013 Get_nn
:= RTE
(GetU_Id
(Csiz
));
2016 -- Now generate the get reference
2018 Compute_Linear_Subscript
(Atyp
, N
, Subscr
);
2020 -- Below we make the assumption that Obj is at least byte
2021 -- aligned, since otherwise its address cannot be taken.
2022 -- The assumption holds since the only arrays that can be
2023 -- misaligned are small packed arrays which are implemented
2024 -- as a modular type, and that is not the case here.
2027 Unchecked_Convert_To
(Ctyp
,
2028 Make_Function_Call
(Loc
,
2029 Name
=> New_Occurrence_Of
(Get_nn
, Loc
),
2030 Parameter_Associations
=> New_List
(
2031 Make_Attribute_Reference
(Loc
,
2032 Attribute_Name
=> Name_Address
,
2038 Analyze_And_Resolve
(N
, Ctyp
, Suppress
=> All_Checks
);
2040 end Expand_Packed_Element_Reference
;
2042 ----------------------
2043 -- Expand_Packed_Eq --
2044 ----------------------
2046 -- Handles expansion of "=" on packed array types
2048 procedure Expand_Packed_Eq
(N
: Node_Id
) is
2049 Loc
: constant Source_Ptr
:= Sloc
(N
);
2050 L
: constant Node_Id
:= Relocate_Node
(Left_Opnd
(N
));
2051 R
: constant Node_Id
:= Relocate_Node
(Right_Opnd
(N
));
2061 Convert_To_Actual_Subtype
(L
);
2062 Convert_To_Actual_Subtype
(R
);
2063 Ltyp
:= Underlying_Type
(Etype
(L
));
2064 Rtyp
:= Underlying_Type
(Etype
(R
));
2066 Convert_To_PAT_Type
(L
);
2067 Convert_To_PAT_Type
(R
);
2071 Make_Op_Multiply
(Loc
,
2073 Make_Attribute_Reference
(Loc
,
2074 Attribute_Name
=> Name_Length
,
2075 Prefix
=> New_Occurrence_Of
(Ltyp
, Loc
)),
2077 Make_Integer_Literal
(Loc
, Component_Size
(Ltyp
)));
2080 Make_Op_Multiply
(Loc
,
2082 Make_Attribute_Reference
(Loc
,
2083 Attribute_Name
=> Name_Length
,
2084 Prefix
=> New_Occurrence_Of
(Rtyp
, Loc
)),
2086 Make_Integer_Literal
(Loc
, Component_Size
(Rtyp
)));
2088 -- For the modular case, we transform the comparison to:
2090 -- Ltyp'Length = Rtyp'Length and then PAT!(L) = PAT!(R)
2092 -- where PAT is the packed array type. This works fine, since in the
2093 -- modular case we guarantee that the unused bits are always zeroes.
2094 -- We do have to compare the lengths because we could be comparing
2095 -- two different subtypes of the same base type.
2097 if Is_Modular_Integer_Type
(PAT
) then
2102 Left_Opnd
=> LLexpr
,
2103 Right_Opnd
=> RLexpr
),
2110 -- For the non-modular case, we call a runtime routine
2112 -- System.Bit_Ops.Bit_Eq
2113 -- (L'Address, L_Length, R'Address, R_Length)
2115 -- where PAT is the packed array type, and the lengths are the lengths
2116 -- in bits of the original packed arrays. This routine takes care of
2117 -- not comparing the unused bits in the last byte.
2121 Make_Function_Call
(Loc
,
2122 Name
=> New_Occurrence_Of
(RTE
(RE_Bit_Eq
), Loc
),
2123 Parameter_Associations
=> New_List
(
2124 Make_Byte_Aligned_Attribute_Reference
(Loc
,
2125 Attribute_Name
=> Name_Address
,
2130 Make_Byte_Aligned_Attribute_Reference
(Loc
,
2131 Attribute_Name
=> Name_Address
,
2137 Analyze_And_Resolve
(N
, Standard_Boolean
, Suppress
=> All_Checks
);
2138 end Expand_Packed_Eq
;
2140 -----------------------
2141 -- Expand_Packed_Not --
2142 -----------------------
2144 -- Handles expansion of "not" on packed array types
2146 procedure Expand_Packed_Not
(N
: Node_Id
) is
2147 Loc
: constant Source_Ptr
:= Sloc
(N
);
2148 Typ
: constant Entity_Id
:= Etype
(N
);
2149 Opnd
: constant Node_Id
:= Relocate_Node
(Right_Opnd
(N
));
2156 Convert_To_Actual_Subtype
(Opnd
);
2157 Rtyp
:= Etype
(Opnd
);
2159 -- First an odd and silly test. We explicitly check for the case
2160 -- where the 'First of the component type is equal to the 'Last of
2161 -- this component type, and if this is the case, we make sure that
2162 -- constraint error is raised. The reason is that the NOT is bound
2163 -- to cause CE in this case, and we will not otherwise catch it.
2165 -- Believe it or not, this was reported as a bug. Note that nearly
2166 -- always, the test will evaluate statically to False, so the code
2167 -- will be statically removed, and no extra overhead caused.
2170 CT
: constant Entity_Id
:= Component_Type
(Rtyp
);
2174 Make_Raise_Constraint_Error
(Loc
,
2178 Make_Attribute_Reference
(Loc
,
2179 Prefix
=> New_Occurrence_Of
(CT
, Loc
),
2180 Attribute_Name
=> Name_First
),
2183 Make_Attribute_Reference
(Loc
,
2184 Prefix
=> New_Occurrence_Of
(CT
, Loc
),
2185 Attribute_Name
=> Name_Last
)),
2186 Reason
=> CE_Range_Check_Failed
));
2189 -- Now that that silliness is taken care of, get packed array type
2191 Convert_To_PAT_Type
(Opnd
);
2192 PAT
:= Etype
(Opnd
);
2194 -- For the case where the packed array type is a modular type,
2195 -- not A expands simply into:
2197 -- rtyp!(PAT!(A) xor mask)
2199 -- where PAT is the packed array type, and mask is a mask of all
2200 -- one bits of length equal to the size of this packed type and
2201 -- rtyp is the actual subtype of the operand
2203 Lit
:= Make_Integer_Literal
(Loc
, 2 ** Esize
(PAT
) - 1);
2204 Set_Print_In_Hex
(Lit
);
2206 if not Is_Array_Type
(PAT
) then
2208 Unchecked_Convert_To
(Rtyp
,
2211 Right_Opnd
=> Lit
)));
2213 -- For the array case, we insert the actions
2217 -- System.Bitops.Bit_Not
2219 -- Typ'Length * Typ'Component_Size;
2222 -- where Opnd is the Packed_Bytes{1,2,4} operand and the second
2223 -- argument is the length of the operand in bits. Then we replace
2224 -- the expression by a reference to Result.
2228 Result_Ent
: constant Entity_Id
:=
2229 Make_Defining_Identifier
(Loc
,
2230 Chars
=> New_Internal_Name
('T'));
2233 Insert_Actions
(N
, New_List
(
2235 Make_Object_Declaration
(Loc
,
2236 Defining_Identifier
=> Result_Ent
,
2237 Object_Definition
=> New_Occurrence_Of
(Rtyp
, Loc
)),
2239 Make_Procedure_Call_Statement
(Loc
,
2240 Name
=> New_Occurrence_Of
(RTE
(RE_Bit_Not
), Loc
),
2241 Parameter_Associations
=> New_List
(
2243 Make_Byte_Aligned_Attribute_Reference
(Loc
,
2244 Attribute_Name
=> Name_Address
,
2247 Make_Op_Multiply
(Loc
,
2249 Make_Attribute_Reference
(Loc
,
2252 (Etype
(First_Index
(Rtyp
)), Loc
),
2253 Attribute_Name
=> Name_Range_Length
),
2255 Make_Integer_Literal
(Loc
, Component_Size
(Rtyp
))),
2257 Make_Byte_Aligned_Attribute_Reference
(Loc
,
2258 Attribute_Name
=> Name_Address
,
2259 Prefix
=> New_Occurrence_Of
(Result_Ent
, Loc
))))));
2262 New_Occurrence_Of
(Result_Ent
, Loc
));
2266 Analyze_And_Resolve
(N
, Typ
, Suppress
=> All_Checks
);
2268 end Expand_Packed_Not
;
2270 -------------------------------------
2271 -- Involves_Packed_Array_Reference --
2272 -------------------------------------
2274 function Involves_Packed_Array_Reference
(N
: Node_Id
) return Boolean is
2276 if Nkind
(N
) = N_Indexed_Component
2277 and then Is_Bit_Packed_Array
(Etype
(Prefix
(N
)))
2281 elsif Nkind
(N
) = N_Selected_Component
then
2282 return Involves_Packed_Array_Reference
(Prefix
(N
));
2287 end Involves_Packed_Array_Reference
;
2289 --------------------------
2290 -- Known_Aligned_Enough --
2291 --------------------------
2293 function Known_Aligned_Enough
(Obj
: Node_Id
; Csiz
: Nat
) return Boolean is
2294 Typ
: constant Entity_Id
:= Etype
(Obj
);
2296 function In_Partially_Packed_Record
(Comp
: Entity_Id
) return Boolean;
2297 -- If the component is in a record that contains previous packed
2298 -- components, consider it unaligned because the back-end might
2299 -- choose to pack the rest of the record. Lead to less efficient code,
2300 -- but safer vis-a-vis of back-end choices.
2302 --------------------------------
2303 -- In_Partially_Packed_Record --
2304 --------------------------------
2306 function In_Partially_Packed_Record
(Comp
: Entity_Id
) return Boolean is
2307 Rec_Type
: constant Entity_Id
:= Scope
(Comp
);
2308 Prev_Comp
: Entity_Id
;
2311 Prev_Comp
:= First_Entity
(Rec_Type
);
2312 while Present
(Prev_Comp
) loop
2313 if Is_Packed
(Etype
(Prev_Comp
)) then
2316 elsif Prev_Comp
= Comp
then
2320 Next_Entity
(Prev_Comp
);
2324 end In_Partially_Packed_Record
;
2326 -- Start of processing for Known_Aligned_Enough
2329 -- Odd bit sizes don't need alignment anyway
2331 if Csiz
mod 2 = 1 then
2334 -- If we have a specified alignment, see if it is sufficient, if not
2335 -- then we can't possibly be aligned enough in any case.
2337 elsif Known_Alignment
(Etype
(Obj
)) then
2338 -- Alignment required is 4 if size is a multiple of 4, and
2339 -- 2 otherwise (e.g. 12 bits requires 4, 10 bits requires 2)
2341 if Alignment
(Etype
(Obj
)) < 4 - (Csiz
mod 4) then
2346 -- OK, alignment should be sufficient, if object is aligned
2348 -- If object is strictly aligned, then it is definitely aligned
2350 if Strict_Alignment
(Typ
) then
2353 -- Case of subscripted array reference
2355 elsif Nkind
(Obj
) = N_Indexed_Component
then
2357 -- If we have a pointer to an array, then this is definitely
2358 -- aligned, because pointers always point to aligned versions.
2360 if Is_Access_Type
(Etype
(Prefix
(Obj
))) then
2363 -- Otherwise, go look at the prefix
2366 return Known_Aligned_Enough
(Prefix
(Obj
), Csiz
);
2369 -- Case of record field
2371 elsif Nkind
(Obj
) = N_Selected_Component
then
2373 -- What is significant here is whether the record type is packed
2375 if Is_Record_Type
(Etype
(Prefix
(Obj
)))
2376 and then Is_Packed
(Etype
(Prefix
(Obj
)))
2380 -- Or the component has a component clause which might cause
2381 -- the component to become unaligned (we can't tell if the
2382 -- backend is doing alignment computations).
2384 elsif Present
(Component_Clause
(Entity
(Selector_Name
(Obj
)))) then
2387 elsif In_Partially_Packed_Record
(Entity
(Selector_Name
(Obj
))) then
2390 -- In all other cases, go look at prefix
2393 return Known_Aligned_Enough
(Prefix
(Obj
), Csiz
);
2396 elsif Nkind
(Obj
) = N_Type_Conversion
then
2397 return Known_Aligned_Enough
(Expression
(Obj
), Csiz
);
2399 -- For a formal parameter, it is safer to assume that it is not
2400 -- aligned, because the formal may be unconstrained while the actual
2401 -- is constrained. In this situation, a small constrained packed
2402 -- array, represented in modular form, may be unaligned.
2404 elsif Is_Entity_Name
(Obj
) then
2405 return not Is_Formal
(Entity
(Obj
));
2408 -- If none of the above, must be aligned
2411 end Known_Aligned_Enough
;
2413 ---------------------
2414 -- Make_Shift_Left --
2415 ---------------------
2417 function Make_Shift_Left
(N
: Node_Id
; S
: Node_Id
) return Node_Id
is
2421 if Compile_Time_Known_Value
(S
) and then Expr_Value
(S
) = 0 then
2425 Make_Op_Shift_Left
(Sloc
(N
),
2428 Set_Shift_Count_OK
(Nod
, True);
2431 end Make_Shift_Left
;
2433 ----------------------
2434 -- Make_Shift_Right --
2435 ----------------------
2437 function Make_Shift_Right
(N
: Node_Id
; S
: Node_Id
) return Node_Id
is
2441 if Compile_Time_Known_Value
(S
) and then Expr_Value
(S
) = 0 then
2445 Make_Op_Shift_Right
(Sloc
(N
),
2448 Set_Shift_Count_OK
(Nod
, True);
2451 end Make_Shift_Right
;
2453 -----------------------------
2454 -- RJ_Unchecked_Convert_To --
2455 -----------------------------
2457 function RJ_Unchecked_Convert_To
2459 Expr
: Node_Id
) return Node_Id
2461 Source_Typ
: constant Entity_Id
:= Etype
(Expr
);
2462 Target_Typ
: constant Entity_Id
:= Typ
;
2464 Src
: Node_Id
:= Expr
;
2470 Source_Siz
:= UI_To_Int
(RM_Size
(Source_Typ
));
2471 Target_Siz
:= UI_To_Int
(RM_Size
(Target_Typ
));
2473 -- First step, if the source type is not a discrete type, then we
2474 -- first convert to a modular type of the source length, since
2475 -- otherwise, on a big-endian machine, we get left-justification.
2476 -- We do it for little-endian machines as well, because there might
2477 -- be junk bits that are not cleared if the type is not numeric.
2479 if Source_Siz
/= Target_Siz
2480 and then not Is_Discrete_Type
(Source_Typ
)
2482 Src
:= Unchecked_Convert_To
(RTE
(Bits_Id
(Source_Siz
)), Src
);
2485 -- In the big endian case, if the lengths of the two types differ,
2486 -- then we must worry about possible left justification in the
2487 -- conversion, and avoiding that is what this is all about.
2489 if Bytes_Big_Endian
and then Source_Siz
/= Target_Siz
then
2491 -- Next step. If the target is not a discrete type, then we first
2492 -- convert to a modular type of the target length, since
2493 -- otherwise, on a big-endian machine, we get left-justification.
2495 if not Is_Discrete_Type
(Target_Typ
) then
2496 Src
:= Unchecked_Convert_To
(RTE
(Bits_Id
(Target_Siz
)), Src
);
2500 -- And now we can do the final conversion to the target type
2502 return Unchecked_Convert_To
(Target_Typ
, Src
);
2503 end RJ_Unchecked_Convert_To
;
2505 ----------------------------------------------
2506 -- Setup_Enumeration_Packed_Array_Reference --
2507 ----------------------------------------------
2509 -- All we have to do here is to find the subscripts that correspond
2510 -- to the index positions that have non-standard enumeration types
2511 -- and insert a Pos attribute to get the proper subscript value.
2513 -- Finally the prefix must be uncheck converted to the corresponding
2514 -- packed array type.
2516 -- Note that the component type is unchanged, so we do not need to
2517 -- fiddle with the types (Gigi always automatically takes the packed
2518 -- array type if it is set, as it will be in this case).
2520 procedure Setup_Enumeration_Packed_Array_Reference
(N
: Node_Id
) is
2521 Pfx
: constant Node_Id
:= Prefix
(N
);
2522 Typ
: constant Entity_Id
:= Etype
(N
);
2523 Exprs
: constant List_Id
:= Expressions
(N
);
2527 -- If the array is unconstrained, then we replace the array
2528 -- reference with its actual subtype. This actual subtype will
2529 -- have a packed array type with appropriate bounds.
2531 if not Is_Constrained
(Packed_Array_Type
(Etype
(Pfx
))) then
2532 Convert_To_Actual_Subtype
(Pfx
);
2535 Expr
:= First
(Exprs
);
2536 while Present
(Expr
) loop
2538 Loc
: constant Source_Ptr
:= Sloc
(Expr
);
2539 Expr_Typ
: constant Entity_Id
:= Etype
(Expr
);
2542 if Is_Enumeration_Type
(Expr_Typ
)
2543 and then Has_Non_Standard_Rep
(Expr_Typ
)
2546 Make_Attribute_Reference
(Loc
,
2547 Prefix
=> New_Occurrence_Of
(Expr_Typ
, Loc
),
2548 Attribute_Name
=> Name_Pos
,
2549 Expressions
=> New_List
(Relocate_Node
(Expr
))));
2550 Analyze_And_Resolve
(Expr
, Standard_Natural
);
2558 Make_Indexed_Component
(Sloc
(N
),
2560 Unchecked_Convert_To
(Packed_Array_Type
(Etype
(Pfx
)), Pfx
),
2561 Expressions
=> Exprs
));
2563 Analyze_And_Resolve
(N
, Typ
);
2565 end Setup_Enumeration_Packed_Array_Reference
;
2567 -----------------------------------------
2568 -- Setup_Inline_Packed_Array_Reference --
2569 -----------------------------------------
2571 procedure Setup_Inline_Packed_Array_Reference
2574 Obj
: in out Node_Id
;
2576 Shift
: out Node_Id
)
2578 Loc
: constant Source_Ptr
:= Sloc
(N
);
2585 Csiz
:= Component_Size
(Atyp
);
2587 Convert_To_PAT_Type
(Obj
);
2590 Cmask
:= 2 ** Csiz
- 1;
2592 if Is_Array_Type
(PAT
) then
2593 Otyp
:= Component_Type
(PAT
);
2594 Osiz
:= Component_Size
(PAT
);
2599 -- In the case where the PAT is a modular type, we want the actual
2600 -- size in bits of the modular value we use. This is neither the
2601 -- Object_Size nor the Value_Size, either of which may have been
2602 -- reset to strange values, but rather the minimum size. Note that
2603 -- since this is a modular type with full range, the issue of
2604 -- biased representation does not arise.
2606 Osiz
:= UI_From_Int
(Minimum_Size
(Otyp
));
2609 Compute_Linear_Subscript
(Atyp
, N
, Shift
);
2611 -- If the component size is not 1, then the subscript must be
2612 -- multiplied by the component size to get the shift count.
2616 Make_Op_Multiply
(Loc
,
2617 Left_Opnd
=> Make_Integer_Literal
(Loc
, Csiz
),
2618 Right_Opnd
=> Shift
);
2621 -- If we have the array case, then this shift count must be broken
2622 -- down into a byte subscript, and a shift within the byte.
2624 if Is_Array_Type
(PAT
) then
2627 New_Shift
: Node_Id
;
2630 -- We must analyze shift, since we will duplicate it
2632 Set_Parent
(Shift
, N
);
2634 (Shift
, Standard_Integer
, Suppress
=> All_Checks
);
2636 -- The shift count within the word is
2641 Left_Opnd
=> Duplicate_Subexpr
(Shift
),
2642 Right_Opnd
=> Make_Integer_Literal
(Loc
, Osiz
));
2644 -- The subscript to be used on the PAT array is
2648 Make_Indexed_Component
(Loc
,
2650 Expressions
=> New_List
(
2651 Make_Op_Divide
(Loc
,
2652 Left_Opnd
=> Duplicate_Subexpr
(Shift
),
2653 Right_Opnd
=> Make_Integer_Literal
(Loc
, Osiz
))));
2658 -- For the modular integer case, the object to be manipulated is
2659 -- the entire array, so Obj is unchanged. Note that we will reset
2660 -- its type to PAT before returning to the caller.
2666 -- The one remaining step is to modify the shift count for the
2667 -- big-endian case. Consider the following example in a byte:
2669 -- xxxxxxxx bits of byte
2670 -- vvvvvvvv bits of value
2671 -- 33221100 little-endian numbering
2672 -- 00112233 big-endian numbering
2674 -- Here we have the case of 2-bit fields
2676 -- For the little-endian case, we already have the proper shift
2677 -- count set, e.g. for element 2, the shift count is 2*2 = 4.
2679 -- For the big endian case, we have to adjust the shift count,
2680 -- computing it as (N - F) - shift, where N is the number of bits
2681 -- in an element of the array used to implement the packed array,
2682 -- F is the number of bits in a source level array element, and
2683 -- shift is the count so far computed.
2685 if Bytes_Big_Endian
then
2687 Make_Op_Subtract
(Loc
,
2688 Left_Opnd
=> Make_Integer_Literal
(Loc
, Osiz
- Csiz
),
2689 Right_Opnd
=> Shift
);
2692 Set_Parent
(Shift
, N
);
2693 Set_Parent
(Obj
, N
);
2694 Analyze_And_Resolve
(Obj
, Otyp
, Suppress
=> All_Checks
);
2695 Analyze_And_Resolve
(Shift
, Standard_Integer
, Suppress
=> All_Checks
);
2697 -- Make sure final type of object is the appropriate packed type
2699 Set_Etype
(Obj
, Otyp
);
2701 end Setup_Inline_Packed_Array_Reference
;