1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2011, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree
; use Atree
;
27 with Checks
; use Checks
;
28 with Einfo
; use Einfo
;
29 with Errout
; use Errout
;
30 with Exp_Dbug
; use Exp_Dbug
;
31 with Exp_Util
; use Exp_Util
;
32 with Layout
; use Layout
;
33 with Namet
; use Namet
;
34 with Nlists
; use Nlists
;
35 with Nmake
; use Nmake
;
37 with Rtsfind
; use Rtsfind
;
39 with Sem_Aux
; use Sem_Aux
;
40 with Sem_Ch3
; use Sem_Ch3
;
41 with Sem_Ch8
; use Sem_Ch8
;
42 with Sem_Ch13
; use Sem_Ch13
;
43 with Sem_Eval
; use Sem_Eval
;
44 with Sem_Res
; use Sem_Res
;
45 with Sem_Util
; use Sem_Util
;
46 with Sinfo
; use Sinfo
;
47 with Snames
; use Snames
;
48 with Stand
; use Stand
;
49 with Targparm
; use Targparm
;
50 with Tbuild
; use Tbuild
;
51 with Ttypes
; use Ttypes
;
52 with Uintp
; use Uintp
;
54 package body Exp_Pakd
is
56 ---------------------------
57 -- Endian Considerations --
58 ---------------------------
60 -- As described in the specification, bit numbering in a packed array
61 -- is consistent with bit numbering in a record representation clause,
62 -- and hence dependent on the endianness of the machine:
64 -- For little-endian machines, element zero is at the right hand end
65 -- (low order end) of a bit field.
67 -- For big-endian machines, element zero is at the left hand end
68 -- (high order end) of a bit field.
70 -- The shifts that are used to right justify a field therefore differ in
71 -- the two cases. For the little-endian case, we can simply use the bit
72 -- number (i.e. the element number * element size) as the count for a right
73 -- shift. For the big-endian case, we have to subtract the shift count from
74 -- an appropriate constant to use in the right shift. We use rotates
75 -- instead of shifts (which is necessary in the store case to preserve
76 -- other fields), and we expect that the backend will be able to change the
77 -- right rotate into a left rotate, avoiding the subtract, if the machine
78 -- architecture provides such an instruction.
80 ----------------------------------------------
81 -- Entity Tables for Packed Access Routines --
82 ----------------------------------------------
84 -- For the cases of component size = 3,5-7,9-15,17-31,33-63 we call library
85 -- routines. This table provides the entity for the proper routine.
87 type E_Array
is array (Int
range 01 .. 63) of RE_Id
;
89 -- Array of Bits_nn entities. Note that we do not use library routines
90 -- for the 8-bit and 16-bit cases, but we still fill in the table, using
91 -- entries from System.Unsigned, because we also use this table for
92 -- certain special unchecked conversions in the big-endian case.
94 Bits_Id
: constant E_Array
:=
110 16 => RE_Unsigned_16
,
126 32 => RE_Unsigned_32
,
159 -- Array of Get routine entities. These are used to obtain an element from
160 -- a packed array. The N'th entry is used to obtain elements from a packed
161 -- array whose component size is N. RE_Null is used as a null entry, for
162 -- the cases where a library routine is not used.
164 Get_Id
: constant E_Array
:=
229 -- Array of Get routine entities to be used in the case where the packed
230 -- array is itself a component of a packed structure, and therefore may not
231 -- be fully aligned. This only affects the even sizes, since for the odd
232 -- sizes, we do not get any fixed alignment in any case.
234 GetU_Id
: constant E_Array
:=
299 -- Array of Set routine entities. These are used to assign an element of a
300 -- packed array. The N'th entry is used to assign elements for a packed
301 -- array whose component size is N. RE_Null is used as a null entry, for
302 -- the cases where a library routine is not used.
304 Set_Id
: constant E_Array
:=
369 -- Array of Set routine entities to be used in the case where the packed
370 -- array is itself a component of a packed structure, and therefore may not
371 -- be fully aligned. This only affects the even sizes, since for the odd
372 -- sizes, we do not get any fixed alignment in any case.
374 SetU_Id
: constant E_Array
:=
439 -----------------------
440 -- Local Subprograms --
441 -----------------------
443 procedure Compute_Linear_Subscript
446 Subscr
: out Node_Id
);
447 -- Given a constrained array type Atyp, and an indexed component node N
448 -- referencing an array object of this type, build an expression of type
449 -- Standard.Integer representing the zero-based linear subscript value.
450 -- This expression includes any required range checks.
452 procedure Convert_To_PAT_Type
(Aexp
: Node_Id
);
453 -- Given an expression of a packed array type, builds a corresponding
454 -- expression whose type is the implementation type used to represent
455 -- the packed array. Aexp is analyzed and resolved on entry and on exit.
457 procedure Get_Base_And_Bit_Offset
460 Offset
: out Node_Id
);
461 -- Given a node N for a name which involves a packed array reference,
462 -- return the base object of the reference and build an expression of
463 -- type Standard.Integer representing the zero-based offset in bits
464 -- from Base'Address to the first bit of the reference.
466 function Known_Aligned_Enough
(Obj
: Node_Id
; Csiz
: Nat
) return Boolean;
467 -- There are two versions of the Set routines, the ones used when the
468 -- object is known to be sufficiently well aligned given the number of
469 -- bits, and the ones used when the object is not known to be aligned.
470 -- This routine is used to determine which set to use. Obj is a reference
471 -- to the object, and Csiz is the component size of the packed array.
472 -- True is returned if the alignment of object is known to be sufficient,
473 -- defined as 1 for odd bit sizes, 4 for bit sizes divisible by 4, and
476 function Make_Shift_Left
(N
: Node_Id
; S
: Node_Id
) return Node_Id
;
477 -- Build a left shift node, checking for the case of a shift count of zero
479 function Make_Shift_Right
(N
: Node_Id
; S
: Node_Id
) return Node_Id
;
480 -- Build a right shift node, checking for the case of a shift count of zero
482 function RJ_Unchecked_Convert_To
484 Expr
: Node_Id
) return Node_Id
;
485 -- The packed array code does unchecked conversions which in some cases
486 -- may involve non-discrete types with differing sizes. The semantics of
487 -- such conversions is potentially endian dependent, and the effect we
488 -- want here for such a conversion is to do the conversion in size as
489 -- though numeric items are involved, and we extend or truncate on the
490 -- left side. This happens naturally in the little-endian case, but in
491 -- the big endian case we can get left justification, when what we want
492 -- is right justification. This routine does the unchecked conversion in
493 -- a stepwise manner to ensure that it gives the expected result. Hence
494 -- the name (RJ = Right justified). The parameters Typ and Expr are as
495 -- for the case of a normal Unchecked_Convert_To call.
497 procedure Setup_Enumeration_Packed_Array_Reference
(N
: Node_Id
);
498 -- This routine is called in the Get and Set case for arrays that are
499 -- packed but not bit-packed, meaning that they have at least one
500 -- subscript that is of an enumeration type with a non-standard
501 -- representation. This routine modifies the given node to properly
502 -- reference the corresponding packed array type.
504 procedure Setup_Inline_Packed_Array_Reference
507 Obj
: in out Node_Id
;
509 Shift
: out Node_Id
);
510 -- This procedure performs common processing on the N_Indexed_Component
511 -- parameter given as N, whose prefix is a reference to a packed array.
512 -- This is used for the get and set when the component size is 1,2,4
513 -- or for other component sizes when the packed array type is a modular
514 -- type (i.e. the cases that are handled with inline code).
518 -- N is the N_Indexed_Component node for the packed array reference
520 -- Atyp is the constrained array type (the actual subtype has been
521 -- computed if necessary to obtain the constraints, but this is still
522 -- the original array type, not the Packed_Array_Type value).
524 -- Obj is the object which is to be indexed. It is always of type Atyp.
528 -- Obj is the object containing the desired bit field. It is of type
529 -- Unsigned, Long_Unsigned, or Long_Long_Unsigned, and is either the
530 -- entire value, for the small static case, or the proper selected byte
531 -- from the array in the large or dynamic case. This node is analyzed
532 -- and resolved on return.
534 -- Shift is a node representing the shift count to be used in the
535 -- rotate right instruction that positions the field for access.
536 -- This node is analyzed and resolved on return.
538 -- Cmask is a mask corresponding to the width of the component field.
539 -- Its value is 2 ** Csize - 1 (e.g. 2#1111# for component size of 4).
541 -- Note: in some cases the call to this routine may generate actions
542 -- (for handling multi-use references and the generation of the packed
543 -- array type on the fly). Such actions are inserted into the tree
544 -- directly using Insert_Action.
546 ------------------------------
547 -- Compute_Linear_Subscript --
548 ------------------------------
550 procedure Compute_Linear_Subscript
553 Subscr
: out Node_Id
)
555 Loc
: constant Source_Ptr
:= Sloc
(N
);
564 -- Loop through dimensions
566 Indx
:= First_Index
(Atyp
);
567 Oldsub
:= First
(Expressions
(N
));
569 while Present
(Indx
) loop
570 Styp
:= Etype
(Indx
);
571 Newsub
:= Relocate_Node
(Oldsub
);
573 -- Get expression for the subscript value. First, if Do_Range_Check
574 -- is set on a subscript, then we must do a range check against the
575 -- original bounds (not the bounds of the packed array type). We do
576 -- this by introducing a subtype conversion.
578 if Do_Range_Check
(Newsub
)
579 and then Etype
(Newsub
) /= Styp
581 Newsub
:= Convert_To
(Styp
, Newsub
);
584 -- Now evolve the expression for the subscript. First convert
585 -- the subscript to be zero based and of an integer type.
587 -- Case of integer type, where we just subtract to get lower bound
589 if Is_Integer_Type
(Styp
) then
591 -- If length of integer type is smaller than standard integer,
592 -- then we convert to integer first, then do the subtract
594 -- Integer (subscript) - Integer (Styp'First)
596 if Esize
(Styp
) < Esize
(Standard_Integer
) then
598 Make_Op_Subtract
(Loc
,
599 Left_Opnd
=> Convert_To
(Standard_Integer
, Newsub
),
601 Convert_To
(Standard_Integer
,
602 Make_Attribute_Reference
(Loc
,
603 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
604 Attribute_Name
=> Name_First
)));
606 -- For larger integer types, subtract first, then convert to
607 -- integer, this deals with strange long long integer bounds.
609 -- Integer (subscript - Styp'First)
613 Convert_To
(Standard_Integer
,
614 Make_Op_Subtract
(Loc
,
617 Make_Attribute_Reference
(Loc
,
618 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
619 Attribute_Name
=> Name_First
)));
622 -- For the enumeration case, we have to use 'Pos to get the value
623 -- to work with before subtracting the lower bound.
625 -- Integer (Styp'Pos (subscr)) - Integer (Styp'Pos (Styp'First));
627 -- This is not quite right for bizarre cases where the size of the
628 -- enumeration type is > Integer'Size bits due to rep clause ???
631 pragma Assert
(Is_Enumeration_Type
(Styp
));
634 Make_Op_Subtract
(Loc
,
635 Left_Opnd
=> Convert_To
(Standard_Integer
,
636 Make_Attribute_Reference
(Loc
,
637 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
638 Attribute_Name
=> Name_Pos
,
639 Expressions
=> New_List
(Newsub
))),
642 Convert_To
(Standard_Integer
,
643 Make_Attribute_Reference
(Loc
,
644 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
645 Attribute_Name
=> Name_Pos
,
646 Expressions
=> New_List
(
647 Make_Attribute_Reference
(Loc
,
648 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
649 Attribute_Name
=> Name_First
)))));
652 Set_Paren_Count
(Newsub
, 1);
654 -- For the first subscript, we just copy that subscript value
659 -- Otherwise, we must multiply what we already have by the current
660 -- stride and then add in the new value to the evolving subscript.
666 Make_Op_Multiply
(Loc
,
669 Make_Attribute_Reference
(Loc
,
670 Attribute_Name
=> Name_Range_Length
,
671 Prefix
=> New_Occurrence_Of
(Styp
, Loc
))),
672 Right_Opnd
=> Newsub
);
675 -- Move to next subscript
680 end Compute_Linear_Subscript
;
682 -------------------------
683 -- Convert_To_PAT_Type --
684 -------------------------
686 -- The PAT is always obtained from the actual subtype
688 procedure Convert_To_PAT_Type
(Aexp
: Node_Id
) is
692 Convert_To_Actual_Subtype
(Aexp
);
693 Act_ST
:= Underlying_Type
(Etype
(Aexp
));
694 Create_Packed_Array_Type
(Act_ST
);
696 -- Just replace the etype with the packed array type. This works because
697 -- the expression will not be further analyzed, and Gigi considers the
698 -- two types equivalent in any case.
700 -- This is not strictly the case ??? If the reference is an actual in
701 -- call, the expansion of the prefix is delayed, and must be reanalyzed,
702 -- see Reset_Packed_Prefix. On the other hand, if the prefix is a simple
703 -- array reference, reanalysis can produce spurious type errors when the
704 -- PAT type is replaced again with the original type of the array. Same
705 -- for the case of a dereference. Ditto for function calls: expansion
706 -- may introduce additional actuals which will trigger errors if call is
707 -- reanalyzed. The following is correct and minimal, but the handling of
708 -- more complex packed expressions in actuals is confused. Probably the
709 -- problem only remains for actuals in calls.
711 Set_Etype
(Aexp
, Packed_Array_Type
(Act_ST
));
713 if Is_Entity_Name
(Aexp
)
715 (Nkind
(Aexp
) = N_Indexed_Component
716 and then Is_Entity_Name
(Prefix
(Aexp
)))
717 or else Nkind_In
(Aexp
, N_Explicit_Dereference
, N_Function_Call
)
721 end Convert_To_PAT_Type
;
723 ------------------------------
724 -- Create_Packed_Array_Type --
725 ------------------------------
727 procedure Create_Packed_Array_Type
(Typ
: Entity_Id
) is
728 Loc
: constant Source_Ptr
:= Sloc
(Typ
);
729 Ctyp
: constant Entity_Id
:= Component_Type
(Typ
);
730 Csize
: constant Uint
:= Component_Size
(Typ
);
745 procedure Install_PAT
;
746 -- This procedure is called with Decl set to the declaration for the
747 -- packed array type. It creates the type and installs it as required.
749 procedure Set_PB_Type
;
750 -- Sets PB_Type to Packed_Bytes{1,2,4} as required by the alignment
751 -- requirements (see documentation in the spec of this package).
757 procedure Install_PAT
is
758 Pushed_Scope
: Boolean := False;
761 -- We do not want to put the declaration we have created in the tree
762 -- since it is often hard, and sometimes impossible to find a proper
763 -- place for it (the impossible case arises for a packed array type
764 -- with bounds depending on the discriminant, a declaration cannot
765 -- be put inside the record, and the reference to the discriminant
766 -- cannot be outside the record).
768 -- The solution is to analyze the declaration while temporarily
769 -- attached to the tree at an appropriate point, and then we install
770 -- the resulting type as an Itype in the packed array type field of
771 -- the original type, so that no explicit declaration is required.
773 -- Note: the packed type is created in the scope of its parent
774 -- type. There are at least some cases where the current scope
775 -- is deeper, and so when this is the case, we temporarily reset
776 -- the scope for the definition. This is clearly safe, since the
777 -- first use of the packed array type will be the implicit
778 -- reference from the corresponding unpacked type when it is
781 if Is_Itype
(Typ
) then
782 Set_Parent
(Decl
, Associated_Node_For_Itype
(Typ
));
784 Set_Parent
(Decl
, Declaration_Node
(Typ
));
787 if Scope
(Typ
) /= Current_Scope
then
788 Push_Scope
(Scope
(Typ
));
789 Pushed_Scope
:= True;
792 Set_Is_Itype
(PAT
, True);
793 Set_Packed_Array_Type
(Typ
, PAT
);
794 Analyze
(Decl
, Suppress
=> All_Checks
);
800 -- Set Esize and RM_Size to the actual size of the packed object
801 -- Do not reset RM_Size if already set, as happens in the case of
804 if Unknown_Esize
(PAT
) then
805 Set_Esize
(PAT
, PASize
);
808 if Unknown_RM_Size
(PAT
) then
809 Set_RM_Size
(PAT
, PASize
);
812 Adjust_Esize_Alignment
(PAT
);
814 -- Set remaining fields of packed array type
816 Init_Alignment
(PAT
);
817 Set_Parent
(PAT
, Empty
);
818 Set_Associated_Node_For_Itype
(PAT
, Typ
);
819 Set_Is_Packed_Array_Type
(PAT
, True);
820 Set_Original_Array_Type
(PAT
, Typ
);
822 -- We definitely do not want to delay freezing for packed array
823 -- types. This is of particular importance for the itypes that
824 -- are generated for record components depending on discriminants
825 -- where there is no place to put the freeze node.
827 Set_Has_Delayed_Freeze
(PAT
, False);
828 Set_Has_Delayed_Freeze
(Etype
(PAT
), False);
830 -- If we did allocate a freeze node, then clear out the reference
831 -- since it is obsolete (should we delete the freeze node???)
833 Set_Freeze_Node
(PAT
, Empty
);
834 Set_Freeze_Node
(Etype
(PAT
), Empty
);
841 procedure Set_PB_Type
is
843 -- If the user has specified an explicit alignment for the
844 -- type or component, take it into account.
846 if Csize
<= 2 or else Csize
= 4 or else Csize
mod 2 /= 0
847 or else Alignment
(Typ
) = 1
848 or else Component_Alignment
(Typ
) = Calign_Storage_Unit
850 PB_Type
:= RTE
(RE_Packed_Bytes1
);
852 elsif Csize
mod 4 /= 0
853 or else Alignment
(Typ
) = 2
855 PB_Type
:= RTE
(RE_Packed_Bytes2
);
858 PB_Type
:= RTE
(RE_Packed_Bytes4
);
862 -- Start of processing for Create_Packed_Array_Type
865 -- If we already have a packed array type, nothing to do
867 if Present
(Packed_Array_Type
(Typ
)) then
871 -- If our immediate ancestor subtype is constrained, and it already
872 -- has a packed array type, then just share the same type, since the
873 -- bounds must be the same. If the ancestor is not an array type but
874 -- a private type, as can happen with multiple instantiations, create
875 -- a new packed type, to avoid privacy issues.
877 if Ekind
(Typ
) = E_Array_Subtype
then
878 Ancest
:= Ancestor_Subtype
(Typ
);
881 and then Is_Array_Type
(Ancest
)
882 and then Is_Constrained
(Ancest
)
883 and then Present
(Packed_Array_Type
(Ancest
))
885 Set_Packed_Array_Type
(Typ
, Packed_Array_Type
(Ancest
));
890 -- We preset the result type size from the size of the original array
891 -- type, since this size clearly belongs to the packed array type. The
892 -- size of the conceptual unpacked type is always set to unknown.
894 PASize
:= RM_Size
(Typ
);
896 -- Case of an array where at least one index is of an enumeration
897 -- type with a non-standard representation, but the component size
898 -- is not appropriate for bit packing. This is the case where we
899 -- have Is_Packed set (we would never be in this unit otherwise),
900 -- but Is_Bit_Packed_Array is false.
902 -- Note that if the component size is appropriate for bit packing,
903 -- then the circuit for the computation of the subscript properly
904 -- deals with the non-standard enumeration type case by taking the
907 if not Is_Bit_Packed_Array
(Typ
) then
909 -- Here we build a declaration:
911 -- type tttP is array (index1, index2, ...) of component_type
913 -- where index1, index2, are the index types. These are the same
914 -- as the index types of the original array, except for the non-
915 -- standard representation enumeration type case, where we have
918 -- For the unconstrained array case, we use
922 -- For the constrained case, we use
924 -- Natural range Enum_Type'Pos (Enum_Type'First) ..
925 -- Enum_Type'Pos (Enum_Type'Last);
928 Make_Defining_Identifier
(Loc
,
929 Chars
=> New_External_Name
(Chars
(Typ
), 'P'));
931 Set_Packed_Array_Type
(Typ
, PAT
);
934 Indexes
: constant List_Id
:= New_List
;
936 Indx_Typ
: Entity_Id
;
941 Indx
:= First_Index
(Typ
);
943 while Present
(Indx
) loop
944 Indx_Typ
:= Etype
(Indx
);
946 Enum_Case
:= Is_Enumeration_Type
(Indx_Typ
)
947 and then Has_Non_Standard_Rep
(Indx_Typ
);
949 -- Unconstrained case
951 if not Is_Constrained
(Typ
) then
953 Indx_Typ
:= Standard_Natural
;
956 Append_To
(Indexes
, New_Occurrence_Of
(Indx_Typ
, Loc
));
961 if not Enum_Case
then
962 Append_To
(Indexes
, New_Occurrence_Of
(Indx_Typ
, Loc
));
966 Make_Subtype_Indication
(Loc
,
968 New_Occurrence_Of
(Standard_Natural
, Loc
),
970 Make_Range_Constraint
(Loc
,
974 Make_Attribute_Reference
(Loc
,
976 New_Occurrence_Of
(Indx_Typ
, Loc
),
977 Attribute_Name
=> Name_Pos
,
978 Expressions
=> New_List
(
979 Make_Attribute_Reference
(Loc
,
981 New_Occurrence_Of
(Indx_Typ
, Loc
),
982 Attribute_Name
=> Name_First
))),
985 Make_Attribute_Reference
(Loc
,
987 New_Occurrence_Of
(Indx_Typ
, Loc
),
988 Attribute_Name
=> Name_Pos
,
989 Expressions
=> New_List
(
990 Make_Attribute_Reference
(Loc
,
992 New_Occurrence_Of
(Indx_Typ
, Loc
),
993 Attribute_Name
=> Name_Last
)))))));
1001 if not Is_Constrained
(Typ
) then
1003 Make_Unconstrained_Array_Definition
(Loc
,
1004 Subtype_Marks
=> Indexes
,
1005 Component_Definition
=>
1006 Make_Component_Definition
(Loc
,
1007 Aliased_Present
=> False,
1008 Subtype_Indication
=>
1009 New_Occurrence_Of
(Ctyp
, Loc
)));
1013 Make_Constrained_Array_Definition
(Loc
,
1014 Discrete_Subtype_Definitions
=> Indexes
,
1015 Component_Definition
=>
1016 Make_Component_Definition
(Loc
,
1017 Aliased_Present
=> False,
1018 Subtype_Indication
=>
1019 New_Occurrence_Of
(Ctyp
, Loc
)));
1023 Make_Full_Type_Declaration
(Loc
,
1024 Defining_Identifier
=> PAT
,
1025 Type_Definition
=> Typedef
);
1028 -- Set type as packed array type and install it
1030 Set_Is_Packed_Array_Type
(PAT
);
1034 -- Case of bit-packing required for unconstrained array. We create
1035 -- a subtype that is equivalent to use Packed_Bytes{1,2,4} as needed.
1037 elsif not Is_Constrained
(Typ
) then
1039 Make_Defining_Identifier
(Loc
,
1040 Chars
=> Make_Packed_Array_Type_Name
(Typ
, Csize
));
1042 Set_Packed_Array_Type
(Typ
, PAT
);
1046 Make_Subtype_Declaration
(Loc
,
1047 Defining_Identifier
=> PAT
,
1048 Subtype_Indication
=> New_Occurrence_Of
(PB_Type
, Loc
));
1052 -- Remaining code is for the case of bit-packing for constrained array
1054 -- The name of the packed array subtype is
1058 -- where sss is the component size in bits and ttt is the name of
1059 -- the parent packed type.
1063 Make_Defining_Identifier
(Loc
,
1064 Chars
=> Make_Packed_Array_Type_Name
(Typ
, Csize
));
1066 Set_Packed_Array_Type
(Typ
, PAT
);
1068 -- Build an expression for the length of the array in bits.
1069 -- This is the product of the length of each of the dimensions
1075 Len_Expr
:= Empty
; -- suppress junk warning
1079 Make_Attribute_Reference
(Loc
,
1080 Attribute_Name
=> Name_Length
,
1081 Prefix
=> New_Occurrence_Of
(Typ
, Loc
),
1082 Expressions
=> New_List
(
1083 Make_Integer_Literal
(Loc
, J
)));
1086 Len_Expr
:= Len_Dim
;
1090 Make_Op_Multiply
(Loc
,
1091 Left_Opnd
=> Len_Expr
,
1092 Right_Opnd
=> Len_Dim
);
1096 exit when J
> Number_Dimensions
(Typ
);
1100 -- Temporarily attach the length expression to the tree and analyze
1101 -- and resolve it, so that we can test its value. We assume that the
1102 -- total length fits in type Integer. This expression may involve
1103 -- discriminants, so we treat it as a default/per-object expression.
1105 Set_Parent
(Len_Expr
, Typ
);
1106 Preanalyze_Spec_Expression
(Len_Expr
, Standard_Long_Long_Integer
);
1108 -- Use a modular type if possible. We can do this if we have
1109 -- static bounds, and the length is small enough, and the length
1110 -- is not zero. We exclude the zero length case because the size
1111 -- of things is always at least one, and the zero length object
1112 -- would have an anomalous size.
1114 if Compile_Time_Known_Value
(Len_Expr
) then
1115 Len_Bits
:= Expr_Value
(Len_Expr
) * Csize
;
1117 -- Check for size known to be too large
1120 Uint_2
** (Standard_Integer_Size
- 1) * System_Storage_Unit
1122 if System_Storage_Unit
= 8 then
1124 ("packed array size cannot exceed " &
1125 "Integer''Last bytes", Typ
);
1128 ("packed array size cannot exceed " &
1129 "Integer''Last storage units", Typ
);
1132 -- Reset length to arbitrary not too high value to continue
1134 Len_Expr
:= Make_Integer_Literal
(Loc
, 65535);
1135 Analyze_And_Resolve
(Len_Expr
, Standard_Long_Long_Integer
);
1138 -- We normally consider small enough to mean no larger than the
1139 -- value of System_Max_Binary_Modulus_Power, checking that in the
1140 -- case of values longer than word size, we have long shifts.
1144 (Len_Bits
<= System_Word_Size
1145 or else (Len_Bits
<= System_Max_Binary_Modulus_Power
1146 and then Support_Long_Shifts_On_Target
))
1148 -- We can use the modular type, it has the form:
1150 -- subtype tttPn is btyp
1151 -- range 0 .. 2 ** ((Typ'Length (1)
1152 -- * ... * Typ'Length (n)) * Csize) - 1;
1154 -- The bounds are statically known, and btyp is one of the
1155 -- unsigned types, depending on the length.
1157 if Len_Bits
<= Standard_Short_Short_Integer_Size
then
1158 Btyp
:= RTE
(RE_Short_Short_Unsigned
);
1160 elsif Len_Bits
<= Standard_Short_Integer_Size
then
1161 Btyp
:= RTE
(RE_Short_Unsigned
);
1163 elsif Len_Bits
<= Standard_Integer_Size
then
1164 Btyp
:= RTE
(RE_Unsigned
);
1166 elsif Len_Bits
<= Standard_Long_Integer_Size
then
1167 Btyp
:= RTE
(RE_Long_Unsigned
);
1170 Btyp
:= RTE
(RE_Long_Long_Unsigned
);
1173 Lit
:= Make_Integer_Literal
(Loc
, 2 ** Len_Bits
- 1);
1174 Set_Print_In_Hex
(Lit
);
1177 Make_Subtype_Declaration
(Loc
,
1178 Defining_Identifier
=> PAT
,
1179 Subtype_Indication
=>
1180 Make_Subtype_Indication
(Loc
,
1181 Subtype_Mark
=> New_Occurrence_Of
(Btyp
, Loc
),
1184 Make_Range_Constraint
(Loc
,
1188 Make_Integer_Literal
(Loc
, 0),
1189 High_Bound
=> Lit
))));
1191 if PASize
= Uint_0
then
1197 -- Propagate a given alignment to the modular type. This can
1198 -- cause it to be under-aligned, but that's OK.
1200 if Present
(Alignment_Clause
(Typ
)) then
1201 Set_Alignment
(PAT
, Alignment
(Typ
));
1208 -- Could not use a modular type, for all other cases, we build
1209 -- a packed array subtype:
1212 -- System.Packed_Bytes{1,2,4} (0 .. (Bits + 7) / 8 - 1);
1214 -- Bits is the length of the array in bits
1221 Make_Op_Multiply
(Loc
,
1223 Make_Integer_Literal
(Loc
, Csize
),
1224 Right_Opnd
=> Len_Expr
),
1227 Make_Integer_Literal
(Loc
, 7));
1229 Set_Paren_Count
(Bits_U1
, 1);
1232 Make_Op_Subtract
(Loc
,
1234 Make_Op_Divide
(Loc
,
1235 Left_Opnd
=> Bits_U1
,
1236 Right_Opnd
=> Make_Integer_Literal
(Loc
, 8)),
1237 Right_Opnd
=> Make_Integer_Literal
(Loc
, 1));
1240 Make_Subtype_Declaration
(Loc
,
1241 Defining_Identifier
=> PAT
,
1242 Subtype_Indication
=>
1243 Make_Subtype_Indication
(Loc
,
1244 Subtype_Mark
=> New_Occurrence_Of
(PB_Type
, Loc
),
1246 Make_Index_Or_Discriminant_Constraint
(Loc
,
1247 Constraints
=> New_List
(
1250 Make_Integer_Literal
(Loc
, 0),
1252 Convert_To
(Standard_Integer
, PAT_High
))))));
1256 -- Currently the code in this unit requires that packed arrays
1257 -- represented by non-modular arrays of bytes be on a byte
1258 -- boundary for bit sizes handled by System.Pack_nn units.
1259 -- That's because these units assume the array being accessed
1260 -- starts on a byte boundary.
1262 if Get_Id
(UI_To_Int
(Csize
)) /= RE_Null
then
1263 Set_Must_Be_On_Byte_Boundary
(Typ
);
1266 end Create_Packed_Array_Type
;
1268 -----------------------------------
1269 -- Expand_Bit_Packed_Element_Set --
1270 -----------------------------------
1272 procedure Expand_Bit_Packed_Element_Set
(N
: Node_Id
) is
1273 Loc
: constant Source_Ptr
:= Sloc
(N
);
1274 Lhs
: constant Node_Id
:= Name
(N
);
1276 Ass_OK
: constant Boolean := Assignment_OK
(Lhs
);
1277 -- Used to preserve assignment OK status when assignment is rewritten
1279 Rhs
: Node_Id
:= Expression
(N
);
1280 -- Initially Rhs is the right hand side value, it will be replaced
1281 -- later by an appropriate unchecked conversion for the assignment.
1291 -- The expression for the shift value that is required
1293 Shift_Used
: Boolean := False;
1294 -- Set True if Shift has been used in the generated code at least
1295 -- once, so that it must be duplicated if used again
1300 Rhs_Val_Known
: Boolean;
1302 -- If the value of the right hand side as an integer constant is
1303 -- known at compile time, Rhs_Val_Known is set True, and Rhs_Val
1304 -- contains the value. Otherwise Rhs_Val_Known is set False, and
1305 -- the Rhs_Val is undefined.
1307 function Get_Shift
return Node_Id
;
1308 -- Function used to get the value of Shift, making sure that it
1309 -- gets duplicated if the function is called more than once.
1315 function Get_Shift
return Node_Id
is
1317 -- If we used the shift value already, then duplicate it. We
1318 -- set a temporary parent in case actions have to be inserted.
1321 Set_Parent
(Shift
, N
);
1322 return Duplicate_Subexpr_No_Checks
(Shift
);
1324 -- If first time, use Shift unchanged, and set flag for first use
1332 -- Start of processing for Expand_Bit_Packed_Element_Set
1335 pragma Assert
(Is_Bit_Packed_Array
(Etype
(Prefix
(Lhs
))));
1337 Obj
:= Relocate_Node
(Prefix
(Lhs
));
1338 Convert_To_Actual_Subtype
(Obj
);
1339 Atyp
:= Etype
(Obj
);
1340 PAT
:= Packed_Array_Type
(Atyp
);
1341 Ctyp
:= Component_Type
(Atyp
);
1342 Csiz
:= UI_To_Int
(Component_Size
(Atyp
));
1344 -- We remove side effects, in case the rhs modifies the lhs, because we
1345 -- are about to transform the rhs into an expression that first READS
1346 -- the lhs, so we can do the necessary shifting and masking. Example:
1347 -- "X(2) := F(...);" where F modifies X(3). Otherwise, the side effect
1350 Remove_Side_Effects
(Rhs
);
1352 -- We convert the right hand side to the proper subtype to ensure
1353 -- that an appropriate range check is made (since the normal range
1354 -- check from assignment will be lost in the transformations). This
1355 -- conversion is analyzed immediately so that subsequent processing
1356 -- can work with an analyzed Rhs (and e.g. look at its Etype)
1358 -- If the right-hand side is a string literal, create a temporary for
1359 -- it, constant-folding is not ready to wrap the bit representation
1360 -- of a string literal.
1362 if Nkind
(Rhs
) = N_String_Literal
then
1367 Make_Object_Declaration
(Loc
,
1368 Defining_Identifier
=> Make_Temporary
(Loc
, 'T', Rhs
),
1369 Object_Definition
=> New_Occurrence_Of
(Ctyp
, Loc
),
1370 Expression
=> New_Copy_Tree
(Rhs
));
1372 Insert_Actions
(N
, New_List
(Decl
));
1373 Rhs
:= New_Occurrence_Of
(Defining_Identifier
(Decl
), Loc
);
1377 Rhs
:= Convert_To
(Ctyp
, Rhs
);
1378 Set_Parent
(Rhs
, N
);
1380 -- If we are building the initialization procedure for a packed array,
1381 -- and Initialize_Scalars is enabled, each component assignment is an
1382 -- out-of-range value by design. Compile this value without checks,
1383 -- because a call to the array init_proc must not raise an exception.
1386 and then Initialize_Scalars
1388 Analyze_And_Resolve
(Rhs
, Ctyp
, Suppress
=> All_Checks
);
1390 Analyze_And_Resolve
(Rhs
, Ctyp
);
1393 -- For the AAMP target, indexing of certain packed array is passed
1394 -- through to the back end without expansion, because the expansion
1395 -- results in very inefficient code on that target. This allows the
1396 -- GNAAMP back end to generate specialized macros that support more
1397 -- efficient indexing of packed arrays with components having sizes
1398 -- that are small powers of two.
1401 and then (Csiz
= 1 or else Csiz
= 2 or else Csiz
= 4)
1406 -- Case of component size 1,2,4 or any component size for the modular
1407 -- case. These are the cases for which we can inline the code.
1409 if Csiz
= 1 or else Csiz
= 2 or else Csiz
= 4
1410 or else (Present
(PAT
) and then Is_Modular_Integer_Type
(PAT
))
1412 Setup_Inline_Packed_Array_Reference
(Lhs
, Atyp
, Obj
, Cmask
, Shift
);
1414 -- The statement to be generated is:
1416 -- Obj := atyp!((Obj and Mask1) or (shift_left (rhs, Shift)))
1418 -- where Mask1 is obtained by shifting Cmask left Shift bits
1419 -- and then complementing the result.
1421 -- the "and Mask1" is omitted if rhs is constant and all 1 bits
1423 -- the "or ..." is omitted if rhs is constant and all 0 bits
1425 -- rhs is converted to the appropriate type
1427 -- The result is converted back to the array type, since
1428 -- otherwise we lose knowledge of the packed nature.
1430 -- Determine if right side is all 0 bits or all 1 bits
1432 if Compile_Time_Known_Value
(Rhs
) then
1433 Rhs_Val
:= Expr_Rep_Value
(Rhs
);
1434 Rhs_Val_Known
:= True;
1436 -- The following test catches the case of an unchecked conversion
1437 -- of an integer literal. This results from optimizing aggregates
1440 elsif Nkind
(Rhs
) = N_Unchecked_Type_Conversion
1441 and then Compile_Time_Known_Value
(Expression
(Rhs
))
1443 Rhs_Val
:= Expr_Rep_Value
(Expression
(Rhs
));
1444 Rhs_Val_Known
:= True;
1448 Rhs_Val_Known
:= False;
1451 -- Some special checks for the case where the right hand value is
1452 -- known at compile time. Basically we have to take care of the
1453 -- implicit conversion to the subtype of the component object.
1455 if Rhs_Val_Known
then
1457 -- If we have a biased component type then we must manually do the
1458 -- biasing, since we are taking responsibility in this case for
1459 -- constructing the exact bit pattern to be used.
1461 if Has_Biased_Representation
(Ctyp
) then
1462 Rhs_Val
:= Rhs_Val
- Expr_Rep_Value
(Type_Low_Bound
(Ctyp
));
1465 -- For a negative value, we manually convert the two's complement
1466 -- value to a corresponding unsigned value, so that the proper
1467 -- field width is maintained. If we did not do this, we would
1468 -- get too many leading sign bits later on.
1471 Rhs_Val
:= 2 ** UI_From_Int
(Csiz
) + Rhs_Val
;
1475 -- Now create copies removing side effects. Note that in some
1476 -- complex cases, this may cause the fact that we have already
1477 -- set a packed array type on Obj to get lost. So we save the
1478 -- type of Obj, and make sure it is reset properly.
1481 T
: constant Entity_Id
:= Etype
(Obj
);
1483 New_Lhs
:= Duplicate_Subexpr
(Obj
, True);
1484 New_Rhs
:= Duplicate_Subexpr_No_Checks
(Obj
);
1486 Set_Etype
(New_Lhs
, T
);
1487 Set_Etype
(New_Rhs
, T
);
1490 -- First we deal with the "and"
1492 if not Rhs_Val_Known
or else Rhs_Val
/= Cmask
then
1498 if Compile_Time_Known_Value
(Shift
) then
1500 Make_Integer_Literal
(Loc
,
1501 Modulus
(Etype
(Obj
)) - 1 -
1502 (Cmask
* (2 ** Expr_Value
(Get_Shift
))));
1503 Set_Print_In_Hex
(Mask1
);
1506 Lit
:= Make_Integer_Literal
(Loc
, Cmask
);
1507 Set_Print_In_Hex
(Lit
);
1510 Right_Opnd
=> Make_Shift_Left
(Lit
, Get_Shift
));
1515 Left_Opnd
=> New_Rhs
,
1516 Right_Opnd
=> Mask1
);
1520 -- Then deal with the "or"
1522 if not Rhs_Val_Known
or else Rhs_Val
/= 0 then
1526 procedure Fixup_Rhs
;
1527 -- Adjust Rhs by bias if biased representation for components
1528 -- or remove extraneous high order sign bits if signed.
1530 procedure Fixup_Rhs
is
1531 Etyp
: constant Entity_Id
:= Etype
(Rhs
);
1534 -- For biased case, do the required biasing by simply
1535 -- converting to the biased subtype (the conversion
1536 -- will generate the required bias).
1538 if Has_Biased_Representation
(Ctyp
) then
1539 Rhs
:= Convert_To
(Ctyp
, Rhs
);
1541 -- For a signed integer type that is not biased, generate
1542 -- a conversion to unsigned to strip high order sign bits.
1544 elsif Is_Signed_Integer_Type
(Ctyp
) then
1545 Rhs
:= Unchecked_Convert_To
(RTE
(Bits_Id
(Csiz
)), Rhs
);
1548 -- Set Etype, since it can be referenced before the node is
1549 -- completely analyzed.
1551 Set_Etype
(Rhs
, Etyp
);
1553 -- We now need to do an unchecked conversion of the
1554 -- result to the target type, but it is important that
1555 -- this conversion be a right justified conversion and
1556 -- not a left justified conversion.
1558 Rhs
:= RJ_Unchecked_Convert_To
(Etype
(Obj
), Rhs
);
1564 and then Compile_Time_Known_Value
(Get_Shift
)
1567 Make_Integer_Literal
(Loc
,
1568 Rhs_Val
* (2 ** Expr_Value
(Get_Shift
)));
1569 Set_Print_In_Hex
(Or_Rhs
);
1572 -- We have to convert the right hand side to Etype (Obj).
1573 -- A special case arises if what we have now is a Val
1574 -- attribute reference whose expression type is Etype (Obj).
1575 -- This happens for assignments of fields from the same
1576 -- array. In this case we get the required right hand side
1577 -- by simply removing the inner attribute reference.
1579 if Nkind
(Rhs
) = N_Attribute_Reference
1580 and then Attribute_Name
(Rhs
) = Name_Val
1581 and then Etype
(First
(Expressions
(Rhs
))) = Etype
(Obj
)
1583 Rhs
:= Relocate_Node
(First
(Expressions
(Rhs
)));
1586 -- If the value of the right hand side is a known integer
1587 -- value, then just replace it by an untyped constant,
1588 -- which will be properly retyped when we analyze and
1589 -- resolve the expression.
1591 elsif Rhs_Val_Known
then
1593 -- Note that Rhs_Val has already been normalized to
1594 -- be an unsigned value with the proper number of bits.
1597 Make_Integer_Literal
(Loc
, Rhs_Val
);
1599 -- Otherwise we need an unchecked conversion
1605 Or_Rhs
:= Make_Shift_Left
(Rhs
, Get_Shift
);
1608 if Nkind
(New_Rhs
) = N_Op_And
then
1609 Set_Paren_Count
(New_Rhs
, 1);
1614 Left_Opnd
=> New_Rhs
,
1615 Right_Opnd
=> Or_Rhs
);
1619 -- Now do the rewrite
1622 Make_Assignment_Statement
(Loc
,
1625 Unchecked_Convert_To
(Etype
(New_Lhs
), New_Rhs
)));
1626 Set_Assignment_OK
(Name
(N
), Ass_OK
);
1628 -- All other component sizes for non-modular case
1633 -- Set_nn (Arr'address, Subscr, Bits_nn!(Rhs))
1635 -- where Subscr is the computed linear subscript
1638 Bits_nn
: constant Entity_Id
:= RTE
(Bits_Id
(Csiz
));
1644 if No
(Bits_nn
) then
1646 -- Error, most likely High_Integrity_Mode restriction
1651 -- Acquire proper Set entity. We use the aligned or unaligned
1652 -- case as appropriate.
1654 if Known_Aligned_Enough
(Obj
, Csiz
) then
1655 Set_nn
:= RTE
(Set_Id
(Csiz
));
1657 Set_nn
:= RTE
(SetU_Id
(Csiz
));
1660 -- Now generate the set reference
1662 Obj
:= Relocate_Node
(Prefix
(Lhs
));
1663 Convert_To_Actual_Subtype
(Obj
);
1664 Atyp
:= Etype
(Obj
);
1665 Compute_Linear_Subscript
(Atyp
, Lhs
, Subscr
);
1667 -- Below we must make the assumption that Obj is
1668 -- at least byte aligned, since otherwise its address
1669 -- cannot be taken. The assumption holds since the
1670 -- only arrays that can be misaligned are small packed
1671 -- arrays which are implemented as a modular type, and
1672 -- that is not the case here.
1675 Make_Procedure_Call_Statement
(Loc
,
1676 Name
=> New_Occurrence_Of
(Set_nn
, Loc
),
1677 Parameter_Associations
=> New_List
(
1678 Make_Attribute_Reference
(Loc
,
1680 Attribute_Name
=> Name_Address
),
1682 Unchecked_Convert_To
(Bits_nn
,
1683 Convert_To
(Ctyp
, Rhs
)))));
1688 Analyze
(N
, Suppress
=> All_Checks
);
1689 end Expand_Bit_Packed_Element_Set
;
1691 -------------------------------------
1692 -- Expand_Packed_Address_Reference --
1693 -------------------------------------
1695 procedure Expand_Packed_Address_Reference
(N
: Node_Id
) is
1696 Loc
: constant Source_Ptr
:= Sloc
(N
);
1701 -- We build an expression that has the form
1703 -- outer_object'Address
1704 -- + (linear-subscript * component_size for each array reference
1705 -- + field'Bit_Position for each record field
1707 -- + ...) / Storage_Unit;
1709 Get_Base_And_Bit_Offset
(Prefix
(N
), Base
, Offset
);
1712 Unchecked_Convert_To
(RTE
(RE_Address
),
1715 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
1716 Make_Attribute_Reference
(Loc
,
1718 Attribute_Name
=> Name_Address
)),
1721 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
1722 Make_Op_Divide
(Loc
,
1723 Left_Opnd
=> Offset
,
1725 Make_Integer_Literal
(Loc
, System_Storage_Unit
))))));
1727 Analyze_And_Resolve
(N
, RTE
(RE_Address
));
1728 end Expand_Packed_Address_Reference
;
1730 ---------------------------------
1731 -- Expand_Packed_Bit_Reference --
1732 ---------------------------------
1734 procedure Expand_Packed_Bit_Reference
(N
: Node_Id
) is
1735 Loc
: constant Source_Ptr
:= Sloc
(N
);
1740 -- We build an expression that has the form
1742 -- (linear-subscript * component_size for each array reference
1743 -- + field'Bit_Position for each record field
1745 -- + ...) mod Storage_Unit;
1747 Get_Base_And_Bit_Offset
(Prefix
(N
), Base
, Offset
);
1750 Unchecked_Convert_To
(Universal_Integer
,
1752 Left_Opnd
=> Offset
,
1753 Right_Opnd
=> Make_Integer_Literal
(Loc
, System_Storage_Unit
))));
1755 Analyze_And_Resolve
(N
, Universal_Integer
);
1756 end Expand_Packed_Bit_Reference
;
1758 ------------------------------------
1759 -- Expand_Packed_Boolean_Operator --
1760 ------------------------------------
1762 -- This routine expands "a op b" for the packed cases
1764 procedure Expand_Packed_Boolean_Operator
(N
: Node_Id
) is
1765 Loc
: constant Source_Ptr
:= Sloc
(N
);
1766 Typ
: constant Entity_Id
:= Etype
(N
);
1767 L
: constant Node_Id
:= Relocate_Node
(Left_Opnd
(N
));
1768 R
: constant Node_Id
:= Relocate_Node
(Right_Opnd
(N
));
1775 Convert_To_Actual_Subtype
(L
);
1776 Convert_To_Actual_Subtype
(R
);
1778 Ensure_Defined
(Etype
(L
), N
);
1779 Ensure_Defined
(Etype
(R
), N
);
1781 Apply_Length_Check
(R
, Etype
(L
));
1786 -- Deal with silly case of XOR where the subcomponent has a range
1787 -- True .. True where an exception must be raised.
1789 if Nkind
(N
) = N_Op_Xor
then
1790 Silly_Boolean_Array_Xor_Test
(N
, Rtyp
);
1793 -- Now that that silliness is taken care of, get packed array type
1795 Convert_To_PAT_Type
(L
);
1796 Convert_To_PAT_Type
(R
);
1800 -- For the modular case, we expand a op b into
1802 -- rtyp!(pat!(a) op pat!(b))
1804 -- where rtyp is the Etype of the left operand. Note that we do not
1805 -- convert to the base type, since this would be unconstrained, and
1806 -- hence not have a corresponding packed array type set.
1808 -- Note that both operands must be modular for this code to be used
1810 if Is_Modular_Integer_Type
(PAT
)
1812 Is_Modular_Integer_Type
(Etype
(R
))
1818 if Nkind
(N
) = N_Op_And
then
1819 P
:= Make_Op_And
(Loc
, L
, R
);
1821 elsif Nkind
(N
) = N_Op_Or
then
1822 P
:= Make_Op_Or
(Loc
, L
, R
);
1824 else -- Nkind (N) = N_Op_Xor
1825 P
:= Make_Op_Xor
(Loc
, L
, R
);
1828 Rewrite
(N
, Unchecked_Convert_To
(Ltyp
, P
));
1831 -- For the array case, we insert the actions
1835 -- System.Bit_Ops.Bit_And/Or/Xor
1837 -- Ltype'Length * Ltype'Component_Size;
1839 -- Rtype'Length * Rtype'Component_Size
1842 -- where Left and Right are the Packed_Bytes{1,2,4} operands and
1843 -- the second argument and fourth arguments are the lengths of the
1844 -- operands in bits. Then we replace the expression by a reference
1847 -- Note that if we are mixing a modular and array operand, everything
1848 -- works fine, since we ensure that the modular representation has the
1849 -- same physical layout as the array representation (that's what the
1850 -- left justified modular stuff in the big-endian case is about).
1854 Result_Ent
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T');
1858 if Nkind
(N
) = N_Op_And
then
1861 elsif Nkind
(N
) = N_Op_Or
then
1864 else -- Nkind (N) = N_Op_Xor
1868 Insert_Actions
(N
, New_List
(
1870 Make_Object_Declaration
(Loc
,
1871 Defining_Identifier
=> Result_Ent
,
1872 Object_Definition
=> New_Occurrence_Of
(Ltyp
, Loc
)),
1874 Make_Procedure_Call_Statement
(Loc
,
1875 Name
=> New_Occurrence_Of
(RTE
(E_Id
), Loc
),
1876 Parameter_Associations
=> New_List
(
1878 Make_Byte_Aligned_Attribute_Reference
(Loc
,
1880 Attribute_Name
=> Name_Address
),
1882 Make_Op_Multiply
(Loc
,
1884 Make_Attribute_Reference
(Loc
,
1887 (Etype
(First_Index
(Ltyp
)), Loc
),
1888 Attribute_Name
=> Name_Range_Length
),
1891 Make_Integer_Literal
(Loc
, Component_Size
(Ltyp
))),
1893 Make_Byte_Aligned_Attribute_Reference
(Loc
,
1895 Attribute_Name
=> Name_Address
),
1897 Make_Op_Multiply
(Loc
,
1899 Make_Attribute_Reference
(Loc
,
1902 (Etype
(First_Index
(Rtyp
)), Loc
),
1903 Attribute_Name
=> Name_Range_Length
),
1906 Make_Integer_Literal
(Loc
, Component_Size
(Rtyp
))),
1908 Make_Byte_Aligned_Attribute_Reference
(Loc
,
1909 Prefix
=> New_Occurrence_Of
(Result_Ent
, Loc
),
1910 Attribute_Name
=> Name_Address
)))));
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 -- For the AAMP target, indexing of certain packed array is passed
1959 -- through to the back end without expansion, because the expansion
1960 -- results in very inefficient code on that target. This allows the
1961 -- GNAAMP back end to generate specialized macros that support more
1962 -- efficient indexing of packed arrays with components having sizes
1963 -- that are small powers of two.
1966 and then (Csiz
= 1 or else Csiz
= 2 or else Csiz
= 4)
1971 -- Case of component size 1,2,4 or any component size for the modular
1972 -- case. These are the cases for which we can inline the code.
1974 if Csiz
= 1 or else Csiz
= 2 or else Csiz
= 4
1975 or else (Present
(PAT
) and then Is_Modular_Integer_Type
(PAT
))
1977 Setup_Inline_Packed_Array_Reference
(N
, Atyp
, Obj
, Cmask
, Shift
);
1978 Lit
:= Make_Integer_Literal
(Loc
, Cmask
);
1979 Set_Print_In_Hex
(Lit
);
1981 -- We generate a shift right to position the field, followed by a
1982 -- masking operation to extract the bit field, and we finally do an
1983 -- unchecked conversion to convert the result to the required target.
1985 -- Note that the unchecked conversion automatically deals with the
1986 -- bias if we are dealing with a biased representation. What will
1987 -- happen is that we temporarily generate the biased representation,
1988 -- but almost immediately that will be converted to the original
1989 -- unbiased component type, and the bias will disappear.
1993 Left_Opnd
=> Make_Shift_Right
(Obj
, Shift
),
1996 -- We needed to analyze this before we do the unchecked convert
1997 -- below, but we need it temporarily attached to the tree for
1998 -- this analysis (hence the temporary Set_Parent call).
2000 Set_Parent
(Arg
, Parent
(N
));
2001 Analyze_And_Resolve
(Arg
);
2003 Rewrite
(N
, RJ_Unchecked_Convert_To
(Ctyp
, Arg
));
2005 -- All other component sizes for non-modular case
2010 -- Component_Type!(Get_nn (Arr'address, Subscr))
2012 -- where Subscr is the computed linear subscript
2019 -- Acquire proper Get entity. We use the aligned or unaligned
2020 -- case as appropriate.
2022 if Known_Aligned_Enough
(Obj
, Csiz
) then
2023 Get_nn
:= RTE
(Get_Id
(Csiz
));
2025 Get_nn
:= RTE
(GetU_Id
(Csiz
));
2028 -- Now generate the get reference
2030 Compute_Linear_Subscript
(Atyp
, N
, Subscr
);
2032 -- Below we make the assumption that Obj is at least byte
2033 -- aligned, since otherwise its address cannot be taken.
2034 -- The assumption holds since the only arrays that can be
2035 -- misaligned are small packed arrays which are implemented
2036 -- as a modular type, and that is not the case here.
2039 Unchecked_Convert_To
(Ctyp
,
2040 Make_Function_Call
(Loc
,
2041 Name
=> New_Occurrence_Of
(Get_nn
, Loc
),
2042 Parameter_Associations
=> New_List
(
2043 Make_Attribute_Reference
(Loc
,
2045 Attribute_Name
=> Name_Address
),
2050 Analyze_And_Resolve
(N
, Ctyp
, Suppress
=> All_Checks
);
2052 end Expand_Packed_Element_Reference
;
2054 ----------------------
2055 -- Expand_Packed_Eq --
2056 ----------------------
2058 -- Handles expansion of "=" on packed array types
2060 procedure Expand_Packed_Eq
(N
: Node_Id
) is
2061 Loc
: constant Source_Ptr
:= Sloc
(N
);
2062 L
: constant Node_Id
:= Relocate_Node
(Left_Opnd
(N
));
2063 R
: constant Node_Id
:= Relocate_Node
(Right_Opnd
(N
));
2073 Convert_To_Actual_Subtype
(L
);
2074 Convert_To_Actual_Subtype
(R
);
2075 Ltyp
:= Underlying_Type
(Etype
(L
));
2076 Rtyp
:= Underlying_Type
(Etype
(R
));
2078 Convert_To_PAT_Type
(L
);
2079 Convert_To_PAT_Type
(R
);
2083 Make_Op_Multiply
(Loc
,
2085 Make_Attribute_Reference
(Loc
,
2086 Prefix
=> New_Occurrence_Of
(Ltyp
, Loc
),
2087 Attribute_Name
=> Name_Length
),
2089 Make_Integer_Literal
(Loc
, Component_Size
(Ltyp
)));
2092 Make_Op_Multiply
(Loc
,
2094 Make_Attribute_Reference
(Loc
,
2095 Prefix
=> New_Occurrence_Of
(Rtyp
, Loc
),
2096 Attribute_Name
=> Name_Length
),
2098 Make_Integer_Literal
(Loc
, Component_Size
(Rtyp
)));
2100 -- For the modular case, we transform the comparison to:
2102 -- Ltyp'Length = Rtyp'Length and then PAT!(L) = PAT!(R)
2104 -- where PAT is the packed array type. This works fine, since in the
2105 -- modular case we guarantee that the unused bits are always zeroes.
2106 -- We do have to compare the lengths because we could be comparing
2107 -- two different subtypes of the same base type.
2109 if Is_Modular_Integer_Type
(PAT
) then
2114 Left_Opnd
=> LLexpr
,
2115 Right_Opnd
=> RLexpr
),
2122 -- For the non-modular case, we call a runtime routine
2124 -- System.Bit_Ops.Bit_Eq
2125 -- (L'Address, L_Length, R'Address, R_Length)
2127 -- where PAT is the packed array type, and the lengths are the lengths
2128 -- in bits of the original packed arrays. This routine takes care of
2129 -- not comparing the unused bits in the last byte.
2133 Make_Function_Call
(Loc
,
2134 Name
=> New_Occurrence_Of
(RTE
(RE_Bit_Eq
), Loc
),
2135 Parameter_Associations
=> New_List
(
2136 Make_Byte_Aligned_Attribute_Reference
(Loc
,
2138 Attribute_Name
=> Name_Address
),
2142 Make_Byte_Aligned_Attribute_Reference
(Loc
,
2144 Attribute_Name
=> Name_Address
),
2149 Analyze_And_Resolve
(N
, Standard_Boolean
, Suppress
=> All_Checks
);
2150 end Expand_Packed_Eq
;
2152 -----------------------
2153 -- Expand_Packed_Not --
2154 -----------------------
2156 -- Handles expansion of "not" on packed array types
2158 procedure Expand_Packed_Not
(N
: Node_Id
) is
2159 Loc
: constant Source_Ptr
:= Sloc
(N
);
2160 Typ
: constant Entity_Id
:= Etype
(N
);
2161 Opnd
: constant Node_Id
:= Relocate_Node
(Right_Opnd
(N
));
2168 Convert_To_Actual_Subtype
(Opnd
);
2169 Rtyp
:= Etype
(Opnd
);
2171 -- Deal with silly False..False and True..True subtype case
2173 Silly_Boolean_Array_Not_Test
(N
, Rtyp
);
2175 -- Now that the silliness is taken care of, get packed array type
2177 Convert_To_PAT_Type
(Opnd
);
2178 PAT
:= Etype
(Opnd
);
2180 -- For the case where the packed array type is a modular type, "not A"
2181 -- expands simply into:
2183 -- Rtyp!(PAT!(A) xor Mask)
2185 -- where PAT is the packed array type, Mask is a mask of all 1 bits of
2186 -- length equal to the size of this packed type, and Rtyp is the actual
2187 -- actual subtype of the operand.
2189 Lit
:= Make_Integer_Literal
(Loc
, 2 ** RM_Size
(PAT
) - 1);
2190 Set_Print_In_Hex
(Lit
);
2192 if not Is_Array_Type
(PAT
) then
2194 Unchecked_Convert_To
(Rtyp
,
2197 Right_Opnd
=> Lit
)));
2199 -- For the array case, we insert the actions
2203 -- System.Bit_Ops.Bit_Not
2205 -- Typ'Length * Typ'Component_Size,
2208 -- where Opnd is the Packed_Bytes{1,2,4} operand and the second argument
2209 -- is the length of the operand in bits. We then replace the expression
2210 -- with a reference to Result.
2214 Result_Ent
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T');
2217 Insert_Actions
(N
, New_List
(
2218 Make_Object_Declaration
(Loc
,
2219 Defining_Identifier
=> Result_Ent
,
2220 Object_Definition
=> New_Occurrence_Of
(Rtyp
, Loc
)),
2222 Make_Procedure_Call_Statement
(Loc
,
2223 Name
=> New_Occurrence_Of
(RTE
(RE_Bit_Not
), Loc
),
2224 Parameter_Associations
=> New_List
(
2225 Make_Byte_Aligned_Attribute_Reference
(Loc
,
2227 Attribute_Name
=> Name_Address
),
2229 Make_Op_Multiply
(Loc
,
2231 Make_Attribute_Reference
(Loc
,
2234 (Etype
(First_Index
(Rtyp
)), Loc
),
2235 Attribute_Name
=> Name_Range_Length
),
2238 Make_Integer_Literal
(Loc
, Component_Size
(Rtyp
))),
2240 Make_Byte_Aligned_Attribute_Reference
(Loc
,
2241 Prefix
=> New_Occurrence_Of
(Result_Ent
, Loc
),
2242 Attribute_Name
=> Name_Address
)))));
2244 Rewrite
(N
, New_Occurrence_Of
(Result_Ent
, Loc
));
2248 Analyze_And_Resolve
(N
, Typ
, Suppress
=> All_Checks
);
2249 end Expand_Packed_Not
;
2251 -----------------------------
2252 -- Get_Base_And_Bit_Offset --
2253 -----------------------------
2255 procedure Get_Base_And_Bit_Offset
2258 Offset
: out Node_Id
)
2269 -- We build up an expression serially that has the form
2271 -- linear-subscript * component_size for each array reference
2272 -- + field'Bit_Position for each record field
2278 if Nkind
(Base
) = N_Indexed_Component
then
2279 Convert_To_Actual_Subtype
(Prefix
(Base
));
2280 Atyp
:= Etype
(Prefix
(Base
));
2281 Compute_Linear_Subscript
(Atyp
, Base
, Subscr
);
2284 Make_Op_Multiply
(Loc
,
2285 Left_Opnd
=> Subscr
,
2287 Make_Attribute_Reference
(Loc
,
2288 Prefix
=> New_Occurrence_Of
(Atyp
, Loc
),
2289 Attribute_Name
=> Name_Component_Size
));
2291 elsif Nkind
(Base
) = N_Selected_Component
then
2293 Make_Attribute_Reference
(Loc
,
2294 Prefix
=> Selector_Name
(Base
),
2295 Attribute_Name
=> Name_Bit_Position
);
2307 Left_Opnd
=> Offset
,
2308 Right_Opnd
=> Term
);
2311 Base
:= Prefix
(Base
);
2313 end Get_Base_And_Bit_Offset
;
2315 -------------------------------------
2316 -- Involves_Packed_Array_Reference --
2317 -------------------------------------
2319 function Involves_Packed_Array_Reference
(N
: Node_Id
) return Boolean is
2321 if Nkind
(N
) = N_Indexed_Component
2322 and then Is_Bit_Packed_Array
(Etype
(Prefix
(N
)))
2326 elsif Nkind
(N
) = N_Selected_Component
then
2327 return Involves_Packed_Array_Reference
(Prefix
(N
));
2332 end Involves_Packed_Array_Reference
;
2334 --------------------------
2335 -- Known_Aligned_Enough --
2336 --------------------------
2338 function Known_Aligned_Enough
(Obj
: Node_Id
; Csiz
: Nat
) return Boolean is
2339 Typ
: constant Entity_Id
:= Etype
(Obj
);
2341 function In_Partially_Packed_Record
(Comp
: Entity_Id
) return Boolean;
2342 -- If the component is in a record that contains previous packed
2343 -- components, consider it unaligned because the back-end might
2344 -- choose to pack the rest of the record. Lead to less efficient code,
2345 -- but safer vis-a-vis of back-end choices.
2347 --------------------------------
2348 -- In_Partially_Packed_Record --
2349 --------------------------------
2351 function In_Partially_Packed_Record
(Comp
: Entity_Id
) return Boolean is
2352 Rec_Type
: constant Entity_Id
:= Scope
(Comp
);
2353 Prev_Comp
: Entity_Id
;
2356 Prev_Comp
:= First_Entity
(Rec_Type
);
2357 while Present
(Prev_Comp
) loop
2358 if Is_Packed
(Etype
(Prev_Comp
)) then
2361 elsif Prev_Comp
= Comp
then
2365 Next_Entity
(Prev_Comp
);
2369 end In_Partially_Packed_Record
;
2371 -- Start of processing for Known_Aligned_Enough
2374 -- Odd bit sizes don't need alignment anyway
2376 if Csiz
mod 2 = 1 then
2379 -- If we have a specified alignment, see if it is sufficient, if not
2380 -- then we can't possibly be aligned enough in any case.
2382 elsif Known_Alignment
(Etype
(Obj
)) then
2383 -- Alignment required is 4 if size is a multiple of 4, and
2384 -- 2 otherwise (e.g. 12 bits requires 4, 10 bits requires 2)
2386 if Alignment
(Etype
(Obj
)) < 4 - (Csiz
mod 4) then
2391 -- OK, alignment should be sufficient, if object is aligned
2393 -- If object is strictly aligned, then it is definitely aligned
2395 if Strict_Alignment
(Typ
) then
2398 -- Case of subscripted array reference
2400 elsif Nkind
(Obj
) = N_Indexed_Component
then
2402 -- If we have a pointer to an array, then this is definitely
2403 -- aligned, because pointers always point to aligned versions.
2405 if Is_Access_Type
(Etype
(Prefix
(Obj
))) then
2408 -- Otherwise, go look at the prefix
2411 return Known_Aligned_Enough
(Prefix
(Obj
), Csiz
);
2414 -- Case of record field
2416 elsif Nkind
(Obj
) = N_Selected_Component
then
2418 -- What is significant here is whether the record type is packed
2420 if Is_Record_Type
(Etype
(Prefix
(Obj
)))
2421 and then Is_Packed
(Etype
(Prefix
(Obj
)))
2425 -- Or the component has a component clause which might cause
2426 -- the component to become unaligned (we can't tell if the
2427 -- backend is doing alignment computations).
2429 elsif Present
(Component_Clause
(Entity
(Selector_Name
(Obj
)))) then
2432 elsif In_Partially_Packed_Record
(Entity
(Selector_Name
(Obj
))) then
2435 -- In all other cases, go look at prefix
2438 return Known_Aligned_Enough
(Prefix
(Obj
), Csiz
);
2441 elsif Nkind
(Obj
) = N_Type_Conversion
then
2442 return Known_Aligned_Enough
(Expression
(Obj
), Csiz
);
2444 -- For a formal parameter, it is safer to assume that it is not
2445 -- aligned, because the formal may be unconstrained while the actual
2446 -- is constrained. In this situation, a small constrained packed
2447 -- array, represented in modular form, may be unaligned.
2449 elsif Is_Entity_Name
(Obj
) then
2450 return not Is_Formal
(Entity
(Obj
));
2453 -- If none of the above, must be aligned
2456 end Known_Aligned_Enough
;
2458 ---------------------
2459 -- Make_Shift_Left --
2460 ---------------------
2462 function Make_Shift_Left
(N
: Node_Id
; S
: Node_Id
) return Node_Id
is
2466 if Compile_Time_Known_Value
(S
) and then Expr_Value
(S
) = 0 then
2470 Make_Op_Shift_Left
(Sloc
(N
),
2473 Set_Shift_Count_OK
(Nod
, True);
2476 end Make_Shift_Left
;
2478 ----------------------
2479 -- Make_Shift_Right --
2480 ----------------------
2482 function Make_Shift_Right
(N
: Node_Id
; S
: Node_Id
) return Node_Id
is
2486 if Compile_Time_Known_Value
(S
) and then Expr_Value
(S
) = 0 then
2490 Make_Op_Shift_Right
(Sloc
(N
),
2493 Set_Shift_Count_OK
(Nod
, True);
2496 end Make_Shift_Right
;
2498 -----------------------------
2499 -- RJ_Unchecked_Convert_To --
2500 -----------------------------
2502 function RJ_Unchecked_Convert_To
2504 Expr
: Node_Id
) return Node_Id
2506 Source_Typ
: constant Entity_Id
:= Etype
(Expr
);
2507 Target_Typ
: constant Entity_Id
:= Typ
;
2509 Src
: Node_Id
:= Expr
;
2515 Source_Siz
:= UI_To_Int
(RM_Size
(Source_Typ
));
2516 Target_Siz
:= UI_To_Int
(RM_Size
(Target_Typ
));
2518 -- First step, if the source type is not a discrete type, then we first
2519 -- convert to a modular type of the source length, since otherwise, on
2520 -- a big-endian machine, we get left-justification. We do it for little-
2521 -- endian machines as well, because there might be junk bits that are
2522 -- not cleared if the type is not numeric.
2524 if Source_Siz
/= Target_Siz
2525 and then not Is_Discrete_Type
(Source_Typ
)
2527 Src
:= Unchecked_Convert_To
(RTE
(Bits_Id
(Source_Siz
)), Src
);
2530 -- In the big endian case, if the lengths of the two types differ, then
2531 -- we must worry about possible left justification in the conversion,
2532 -- and avoiding that is what this is all about.
2534 if Bytes_Big_Endian
and then Source_Siz
/= Target_Siz
then
2536 -- Next step. If the target is not a discrete type, then we first
2537 -- convert to a modular type of the target length, since otherwise,
2538 -- on a big-endian machine, we get left-justification.
2540 if not Is_Discrete_Type
(Target_Typ
) then
2541 Src
:= Unchecked_Convert_To
(RTE
(Bits_Id
(Target_Siz
)), Src
);
2545 -- And now we can do the final conversion to the target type
2547 return Unchecked_Convert_To
(Target_Typ
, Src
);
2548 end RJ_Unchecked_Convert_To
;
2550 ----------------------------------------------
2551 -- Setup_Enumeration_Packed_Array_Reference --
2552 ----------------------------------------------
2554 -- All we have to do here is to find the subscripts that correspond to the
2555 -- index positions that have non-standard enumeration types and insert a
2556 -- Pos attribute to get the proper subscript value.
2558 -- Finally the prefix must be uncheck-converted to the corresponding packed
2561 -- Note that the component type is unchanged, so we do not need to fiddle
2562 -- with the types (Gigi always automatically takes the packed array type if
2563 -- it is set, as it will be in this case).
2565 procedure Setup_Enumeration_Packed_Array_Reference
(N
: Node_Id
) is
2566 Pfx
: constant Node_Id
:= Prefix
(N
);
2567 Typ
: constant Entity_Id
:= Etype
(N
);
2568 Exprs
: constant List_Id
:= Expressions
(N
);
2572 -- If the array is unconstrained, then we replace the array reference
2573 -- with its actual subtype. This actual subtype will have a packed array
2574 -- type with appropriate bounds.
2576 if not Is_Constrained
(Packed_Array_Type
(Etype
(Pfx
))) then
2577 Convert_To_Actual_Subtype
(Pfx
);
2580 Expr
:= First
(Exprs
);
2581 while Present
(Expr
) loop
2583 Loc
: constant Source_Ptr
:= Sloc
(Expr
);
2584 Expr_Typ
: constant Entity_Id
:= Etype
(Expr
);
2587 if Is_Enumeration_Type
(Expr_Typ
)
2588 and then Has_Non_Standard_Rep
(Expr_Typ
)
2591 Make_Attribute_Reference
(Loc
,
2592 Prefix
=> New_Occurrence_Of
(Expr_Typ
, Loc
),
2593 Attribute_Name
=> Name_Pos
,
2594 Expressions
=> New_List
(Relocate_Node
(Expr
))));
2595 Analyze_And_Resolve
(Expr
, Standard_Natural
);
2603 Make_Indexed_Component
(Sloc
(N
),
2605 Unchecked_Convert_To
(Packed_Array_Type
(Etype
(Pfx
)), Pfx
),
2606 Expressions
=> Exprs
));
2608 Analyze_And_Resolve
(N
, Typ
);
2609 end Setup_Enumeration_Packed_Array_Reference
;
2611 -----------------------------------------
2612 -- Setup_Inline_Packed_Array_Reference --
2613 -----------------------------------------
2615 procedure Setup_Inline_Packed_Array_Reference
2618 Obj
: in out Node_Id
;
2620 Shift
: out Node_Id
)
2622 Loc
: constant Source_Ptr
:= Sloc
(N
);
2629 Csiz
:= Component_Size
(Atyp
);
2631 Convert_To_PAT_Type
(Obj
);
2634 Cmask
:= 2 ** Csiz
- 1;
2636 if Is_Array_Type
(PAT
) then
2637 Otyp
:= Component_Type
(PAT
);
2638 Osiz
:= Component_Size
(PAT
);
2643 -- In the case where the PAT is a modular type, we want the actual
2644 -- size in bits of the modular value we use. This is neither the
2645 -- Object_Size nor the Value_Size, either of which may have been
2646 -- reset to strange values, but rather the minimum size. Note that
2647 -- since this is a modular type with full range, the issue of
2648 -- biased representation does not arise.
2650 Osiz
:= UI_From_Int
(Minimum_Size
(Otyp
));
2653 Compute_Linear_Subscript
(Atyp
, N
, Shift
);
2655 -- If the component size is not 1, then the subscript must be multiplied
2656 -- by the component size to get the shift count.
2660 Make_Op_Multiply
(Loc
,
2661 Left_Opnd
=> Make_Integer_Literal
(Loc
, Csiz
),
2662 Right_Opnd
=> Shift
);
2665 -- If we have the array case, then this shift count must be broken down
2666 -- into a byte subscript, and a shift within the byte.
2668 if Is_Array_Type
(PAT
) then
2671 New_Shift
: Node_Id
;
2674 -- We must analyze shift, since we will duplicate it
2676 Set_Parent
(Shift
, N
);
2678 (Shift
, Standard_Integer
, Suppress
=> All_Checks
);
2680 -- The shift count within the word is
2685 Left_Opnd
=> Duplicate_Subexpr
(Shift
),
2686 Right_Opnd
=> Make_Integer_Literal
(Loc
, Osiz
));
2688 -- The subscript to be used on the PAT array is
2692 Make_Indexed_Component
(Loc
,
2694 Expressions
=> New_List
(
2695 Make_Op_Divide
(Loc
,
2696 Left_Opnd
=> Duplicate_Subexpr
(Shift
),
2697 Right_Opnd
=> Make_Integer_Literal
(Loc
, Osiz
))));
2702 -- For the modular integer case, the object to be manipulated is the
2703 -- entire array, so Obj is unchanged. Note that we will reset its type
2704 -- to PAT before returning to the caller.
2710 -- The one remaining step is to modify the shift count for the
2711 -- big-endian case. Consider the following example in a byte:
2713 -- xxxxxxxx bits of byte
2714 -- vvvvvvvv bits of value
2715 -- 33221100 little-endian numbering
2716 -- 00112233 big-endian numbering
2718 -- Here we have the case of 2-bit fields
2720 -- For the little-endian case, we already have the proper shift count
2721 -- set, e.g. for element 2, the shift count is 2*2 = 4.
2723 -- For the big endian case, we have to adjust the shift count, computing
2724 -- it as (N - F) - Shift, where N is the number of bits in an element of
2725 -- the array used to implement the packed array, F is the number of bits
2726 -- in a source array element, and Shift is the count so far computed.
2728 if Bytes_Big_Endian
then
2730 Make_Op_Subtract
(Loc
,
2731 Left_Opnd
=> Make_Integer_Literal
(Loc
, Osiz
- Csiz
),
2732 Right_Opnd
=> Shift
);
2735 Set_Parent
(Shift
, N
);
2736 Set_Parent
(Obj
, N
);
2737 Analyze_And_Resolve
(Obj
, Otyp
, Suppress
=> All_Checks
);
2738 Analyze_And_Resolve
(Shift
, Standard_Integer
, Suppress
=> All_Checks
);
2740 -- Make sure final type of object is the appropriate packed type
2742 Set_Etype
(Obj
, Otyp
);
2744 end Setup_Inline_Packed_Array_Reference
;