1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2017, 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 Lib
.Xref
; use Lib
.Xref
;
34 with Namet
; use Namet
;
35 with Nlists
; use Nlists
;
36 with Nmake
; use Nmake
;
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 -- Local Subprograms --
82 -----------------------
84 procedure Compute_Linear_Subscript
87 Subscr
: out Node_Id
);
88 -- Given a constrained array type Atyp, and an indexed component node N
89 -- referencing an array object of this type, build an expression of type
90 -- Standard.Integer representing the zero-based linear subscript value.
91 -- This expression includes any required range checks.
93 function Compute_Number_Components
95 Typ
: Entity_Id
) return Node_Id
;
96 -- Build an expression that multiplies the length of the dimensions of the
97 -- array, used to control array equality checks.
99 procedure Convert_To_PAT_Type
(Aexp
: Node_Id
);
100 -- Given an expression of a packed array type, builds a corresponding
101 -- expression whose type is the implementation type used to represent
102 -- the packed array. Aexp is analyzed and resolved on entry and on exit.
104 procedure Get_Base_And_Bit_Offset
107 Offset
: out Node_Id
);
108 -- Given a node N for a name which involves a packed array reference,
109 -- return the base object of the reference and build an expression of
110 -- type Standard.Integer representing the zero-based offset in bits
111 -- from Base'Address to the first bit of the reference.
113 function Known_Aligned_Enough
(Obj
: Node_Id
; Csiz
: Nat
) return Boolean;
114 -- There are two versions of the Set routines, the ones used when the
115 -- object is known to be sufficiently well aligned given the number of
116 -- bits, and the ones used when the object is not known to be aligned.
117 -- This routine is used to determine which set to use. Obj is a reference
118 -- to the object, and Csiz is the component size of the packed array.
119 -- True is returned if the alignment of object is known to be sufficient,
120 -- defined as 1 for odd bit sizes, 4 for bit sizes divisible by 4, and
123 function Make_Shift_Left
(N
: Node_Id
; S
: Node_Id
) return Node_Id
;
124 -- Build a left shift node, checking for the case of a shift count of zero
126 function Make_Shift_Right
(N
: Node_Id
; S
: Node_Id
) return Node_Id
;
127 -- Build a right shift node, checking for the case of a shift count of zero
129 function RJ_Unchecked_Convert_To
131 Expr
: Node_Id
) return Node_Id
;
132 -- The packed array code does unchecked conversions which in some cases
133 -- may involve non-discrete types with differing sizes. The semantics of
134 -- such conversions is potentially endianness dependent, and the effect
135 -- we want here for such a conversion is to do the conversion in size as
136 -- though numeric items are involved, and we extend or truncate on the
137 -- left side. This happens naturally in the little-endian case, but in
138 -- the big endian case we can get left justification, when what we want
139 -- is right justification. This routine does the unchecked conversion in
140 -- a stepwise manner to ensure that it gives the expected result. Hence
141 -- the name (RJ = Right justified). The parameters Typ and Expr are as
142 -- for the case of a normal Unchecked_Convert_To call.
144 procedure Setup_Enumeration_Packed_Array_Reference
(N
: Node_Id
);
145 -- This routine is called in the Get and Set case for arrays that are
146 -- packed but not bit-packed, meaning that they have at least one
147 -- subscript that is of an enumeration type with a non-standard
148 -- representation. This routine modifies the given node to properly
149 -- reference the corresponding packed array type.
151 procedure Setup_Inline_Packed_Array_Reference
154 Obj
: in out Node_Id
;
156 Shift
: out Node_Id
);
157 -- This procedure performs common processing on the N_Indexed_Component
158 -- parameter given as N, whose prefix is a reference to a packed array.
159 -- This is used for the get and set when the component size is 1, 2, 4,
160 -- or for other component sizes when the packed array type is a modular
161 -- type (i.e. the cases that are handled with inline code).
165 -- N is the N_Indexed_Component node for the packed array reference
167 -- Atyp is the constrained array type (the actual subtype has been
168 -- computed if necessary to obtain the constraints, but this is still
169 -- the original array type, not the Packed_Array_Impl_Type value).
171 -- Obj is the object which is to be indexed. It is always of type Atyp.
175 -- Obj is the object containing the desired bit field. It is of type
176 -- Unsigned, Long_Unsigned, or Long_Long_Unsigned, and is either the
177 -- entire value, for the small static case, or the proper selected byte
178 -- from the array in the large or dynamic case. This node is analyzed
179 -- and resolved on return.
181 -- Shift is a node representing the shift count to be used in the
182 -- rotate right instruction that positions the field for access.
183 -- This node is analyzed and resolved on return.
185 -- Cmask is a mask corresponding to the width of the component field.
186 -- Its value is 2 ** Csize - 1 (e.g. 2#1111# for component size of 4).
188 -- Note: in some cases the call to this routine may generate actions
189 -- (for handling multi-use references and the generation of the packed
190 -- array type on the fly). Such actions are inserted into the tree
191 -- directly using Insert_Action.
193 function Revert_Storage_Order
(N
: Node_Id
) return Node_Id
;
194 -- Perform appropriate justification and byte ordering adjustments for N,
195 -- an element of a packed array type, when both the component type and
196 -- the enclosing packed array type have reverse scalar storage order.
197 -- On little-endian targets, the value is left justified before byte
198 -- swapping. The Etype of the returned expression is an integer type of
199 -- an appropriate power-of-2 size.
201 --------------------------
202 -- Revert_Storage_Order --
203 --------------------------
205 function Revert_Storage_Order
(N
: Node_Id
) return Node_Id
is
206 Loc
: constant Source_Ptr
:= Sloc
(N
);
207 T
: constant Entity_Id
:= Etype
(N
);
208 T_Size
: constant Uint
:= RM_Size
(T
);
222 -- Array component size is less than a byte: no swapping needed
225 Swap_T
:= RTE
(RE_Unsigned_8
);
228 -- Select byte swapping function depending on array component size
231 Swap_RE
:= RE_Bswap_16
;
233 elsif T_Size
<= 32 then
234 Swap_RE
:= RE_Bswap_32
;
236 else pragma Assert
(T_Size
<= 64);
237 Swap_RE
:= RE_Bswap_64
;
240 Swap_F
:= RTE
(Swap_RE
);
241 Swap_T
:= Etype
(Swap_F
);
245 Shift
:= Esize
(Swap_T
) - T_Size
;
247 Arg
:= RJ_Unchecked_Convert_To
(Swap_T
, N
);
249 if not Bytes_Big_Endian
and then Shift
> Uint_0
then
251 Make_Op_Shift_Left
(Loc
,
253 Right_Opnd
=> Make_Integer_Literal
(Loc
, Shift
));
256 if Present
(Swap_F
) then
258 Make_Function_Call
(Loc
,
259 Name
=> New_Occurrence_Of
(Swap_F
, Loc
),
260 Parameter_Associations
=> New_List
(Arg
));
265 Set_Etype
(Adjusted
, Swap_T
);
267 end Revert_Storage_Order
;
269 ------------------------------
270 -- Compute_Linear_Subscript --
271 ------------------------------
273 procedure Compute_Linear_Subscript
276 Subscr
: out Node_Id
)
278 Loc
: constant Source_Ptr
:= Sloc
(N
);
287 -- Loop through dimensions
289 Indx
:= First_Index
(Atyp
);
290 Oldsub
:= First
(Expressions
(N
));
292 while Present
(Indx
) loop
293 Styp
:= Etype
(Indx
);
294 Newsub
:= Relocate_Node
(Oldsub
);
296 -- Get expression for the subscript value. First, if Do_Range_Check
297 -- is set on a subscript, then we must do a range check against the
298 -- original bounds (not the bounds of the packed array type). We do
299 -- this by introducing a subtype conversion.
301 if Do_Range_Check
(Newsub
)
302 and then Etype
(Newsub
) /= Styp
304 Newsub
:= Convert_To
(Styp
, Newsub
);
307 -- Now evolve the expression for the subscript. First convert
308 -- the subscript to be zero based and of an integer type.
310 -- Case of integer type, where we just subtract to get lower bound
312 if Is_Integer_Type
(Styp
) then
314 -- If length of integer type is smaller than standard integer,
315 -- then we convert to integer first, then do the subtract
317 -- Integer (subscript) - Integer (Styp'First)
319 if Esize
(Styp
) < Esize
(Standard_Integer
) then
321 Make_Op_Subtract
(Loc
,
322 Left_Opnd
=> Convert_To
(Standard_Integer
, Newsub
),
324 Convert_To
(Standard_Integer
,
325 Make_Attribute_Reference
(Loc
,
326 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
327 Attribute_Name
=> Name_First
)));
329 -- For larger integer types, subtract first, then convert to
330 -- integer, this deals with strange long long integer bounds.
332 -- Integer (subscript - Styp'First)
336 Convert_To
(Standard_Integer
,
337 Make_Op_Subtract
(Loc
,
340 Make_Attribute_Reference
(Loc
,
341 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
342 Attribute_Name
=> Name_First
)));
345 -- For the enumeration case, we have to use 'Pos to get the value
346 -- to work with before subtracting the lower bound.
348 -- Integer (Styp'Pos (subscr)) - Integer (Styp'Pos (Styp'First));
350 -- This is not quite right for bizarre cases where the size of the
351 -- enumeration type is > Integer'Size bits due to rep clause ???
354 pragma Assert
(Is_Enumeration_Type
(Styp
));
357 Make_Op_Subtract
(Loc
,
358 Left_Opnd
=> Convert_To
(Standard_Integer
,
359 Make_Attribute_Reference
(Loc
,
360 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
361 Attribute_Name
=> Name_Pos
,
362 Expressions
=> New_List
(Newsub
))),
365 Convert_To
(Standard_Integer
,
366 Make_Attribute_Reference
(Loc
,
367 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
368 Attribute_Name
=> Name_Pos
,
369 Expressions
=> New_List
(
370 Make_Attribute_Reference
(Loc
,
371 Prefix
=> New_Occurrence_Of
(Styp
, Loc
),
372 Attribute_Name
=> Name_First
)))));
375 Set_Paren_Count
(Newsub
, 1);
377 -- For the first subscript, we just copy that subscript value
382 -- Otherwise, we must multiply what we already have by the current
383 -- stride and then add in the new value to the evolving subscript.
389 Make_Op_Multiply
(Loc
,
392 Make_Attribute_Reference
(Loc
,
393 Attribute_Name
=> Name_Range_Length
,
394 Prefix
=> New_Occurrence_Of
(Styp
, Loc
))),
395 Right_Opnd
=> Newsub
);
398 -- Move to next subscript
403 end Compute_Linear_Subscript
;
405 -------------------------------
406 -- Compute_Number_Components --
407 -------------------------------
409 function Compute_Number_Components
411 Typ
: Entity_Id
) return Node_Id
413 Loc
: constant Source_Ptr
:= Sloc
(N
);
418 Make_Attribute_Reference
(Loc
,
419 Attribute_Name
=> Name_Length
,
420 Prefix
=> New_Occurrence_Of
(Typ
, Loc
),
421 Expressions
=> New_List
(Make_Integer_Literal
(Loc
, 1)));
423 for J
in 2 .. Number_Dimensions
(Typ
) loop
425 Make_Op_Multiply
(Loc
,
426 Left_Opnd
=> Len_Expr
,
428 Make_Attribute_Reference
(Loc
,
429 Attribute_Name
=> Name_Length
,
430 Prefix
=> New_Occurrence_Of
(Typ
, Loc
),
431 Expressions
=> New_List
(Make_Integer_Literal
(Loc
, J
))));
435 end Compute_Number_Components
;
437 -------------------------
438 -- Convert_To_PAT_Type --
439 -------------------------
441 -- The PAT is always obtained from the actual subtype
443 procedure Convert_To_PAT_Type
(Aexp
: Node_Id
) is
447 Convert_To_Actual_Subtype
(Aexp
);
448 Act_ST
:= Underlying_Type
(Etype
(Aexp
));
449 Create_Packed_Array_Impl_Type
(Act_ST
);
451 -- Just replace the etype with the packed array type. This works because
452 -- the expression will not be further analyzed, and Gigi considers the
453 -- two types equivalent in any case.
455 -- This is not strictly the case ??? If the reference is an actual in
456 -- call, the expansion of the prefix is delayed, and must be reanalyzed,
457 -- see Reset_Packed_Prefix. On the other hand, if the prefix is a simple
458 -- array reference, reanalysis can produce spurious type errors when the
459 -- PAT type is replaced again with the original type of the array. Same
460 -- for the case of a dereference. Ditto for function calls: expansion
461 -- may introduce additional actuals which will trigger errors if call is
462 -- reanalyzed. The following is correct and minimal, but the handling of
463 -- more complex packed expressions in actuals is confused. Probably the
464 -- problem only remains for actuals in calls.
466 Set_Etype
(Aexp
, Packed_Array_Impl_Type
(Act_ST
));
468 if Is_Entity_Name
(Aexp
)
470 (Nkind
(Aexp
) = N_Indexed_Component
471 and then Is_Entity_Name
(Prefix
(Aexp
)))
472 or else Nkind_In
(Aexp
, N_Explicit_Dereference
, N_Function_Call
)
476 end Convert_To_PAT_Type
;
478 -----------------------------------
479 -- Create_Packed_Array_Impl_Type --
480 -----------------------------------
482 procedure Create_Packed_Array_Impl_Type
(Typ
: Entity_Id
) is
483 Loc
: constant Source_Ptr
:= Sloc
(Typ
);
484 Ctyp
: constant Entity_Id
:= Component_Type
(Typ
);
485 Csize
: constant Uint
:= Component_Size
(Typ
);
499 procedure Install_PAT
;
500 -- This procedure is called with Decl set to the declaration for the
501 -- packed array type. It creates the type and installs it as required.
503 procedure Set_PB_Type
;
504 -- Sets PB_Type to Packed_Bytes{1,2,4} as required by the alignment
505 -- requirements (see documentation in the spec of this package).
511 procedure Install_PAT
is
512 Pushed_Scope
: Boolean := False;
515 -- We do not want to put the declaration we have created in the tree
516 -- since it is often hard, and sometimes impossible to find a proper
517 -- place for it (the impossible case arises for a packed array type
518 -- with bounds depending on the discriminant, a declaration cannot
519 -- be put inside the record, and the reference to the discriminant
520 -- cannot be outside the record).
522 -- The solution is to analyze the declaration while temporarily
523 -- attached to the tree at an appropriate point, and then we install
524 -- the resulting type as an Itype in the packed array type field of
525 -- the original type, so that no explicit declaration is required.
527 -- Note: the packed type is created in the scope of its parent type.
528 -- There are at least some cases where the current scope is deeper,
529 -- and so when this is the case, we temporarily reset the scope
530 -- for the definition. This is clearly safe, since the first use
531 -- of the packed array type will be the implicit reference from
532 -- the corresponding unpacked type when it is elaborated.
534 if Is_Itype
(Typ
) then
535 Set_Parent
(Decl
, Associated_Node_For_Itype
(Typ
));
537 Set_Parent
(Decl
, Declaration_Node
(Typ
));
540 if Scope
(Typ
) /= Current_Scope
then
541 Push_Scope
(Scope
(Typ
));
542 Pushed_Scope
:= True;
545 Set_Is_Itype
(PAT
, True);
546 Set_Is_Packed_Array_Impl_Type
(PAT
, True);
547 Set_Packed_Array_Impl_Type
(Typ
, PAT
);
548 Analyze
(Decl
, Suppress
=> All_Checks
);
554 -- Set Esize and RM_Size to the actual size of the packed object
555 -- Do not reset RM_Size if already set, as happens in the case of
558 if Unknown_Esize
(PAT
) then
559 Set_Esize
(PAT
, PASize
);
562 if Unknown_RM_Size
(PAT
) then
563 Set_RM_Size
(PAT
, PASize
);
566 Adjust_Esize_Alignment
(PAT
);
568 -- Set remaining fields of packed array type
570 Init_Alignment
(PAT
);
571 Set_Parent
(PAT
, Empty
);
572 Set_Associated_Node_For_Itype
(PAT
, Typ
);
573 Set_Original_Array_Type
(PAT
, Typ
);
575 -- Propagate representation aspects
577 Set_Is_Atomic
(PAT
, Is_Atomic
(Typ
));
578 Set_Is_Independent
(PAT
, Is_Independent
(Typ
));
579 Set_Is_Volatile
(PAT
, Is_Volatile
(Typ
));
580 Set_Is_Volatile_Full_Access
(PAT
, Is_Volatile_Full_Access
(Typ
));
581 Set_Treat_As_Volatile
(PAT
, Treat_As_Volatile
(Typ
));
583 -- For a non-bit-packed array, propagate reverse storage order
584 -- flag from original base type to packed array base type.
586 if not Is_Bit_Packed_Array
(Typ
) then
587 Set_Reverse_Storage_Order
588 (Etype
(PAT
), Reverse_Storage_Order
(Base_Type
(Typ
)));
591 -- We definitely do not want to delay freezing for packed array
592 -- types. This is of particular importance for the itypes that are
593 -- generated for record components depending on discriminants where
594 -- there is no place to put the freeze node.
596 Set_Has_Delayed_Freeze
(PAT
, False);
597 Set_Has_Delayed_Freeze
(Etype
(PAT
), False);
599 -- If we did allocate a freeze node, then clear out the reference
600 -- since it is obsolete (should we delete the freeze node???)
602 Set_Freeze_Node
(PAT
, Empty
);
603 Set_Freeze_Node
(Etype
(PAT
), Empty
);
610 procedure Set_PB_Type
is
612 -- If the user has specified an explicit alignment for the
613 -- type or component, take it into account.
615 if Csize
<= 2 or else Csize
= 4 or else Csize
mod 2 /= 0
616 or else Alignment
(Typ
) = 1
617 or else Component_Alignment
(Typ
) = Calign_Storage_Unit
619 PB_Type
:= RTE
(RE_Packed_Bytes1
);
621 elsif Csize
mod 4 /= 0
622 or else Alignment
(Typ
) = 2
624 PB_Type
:= RTE
(RE_Packed_Bytes2
);
627 PB_Type
:= RTE
(RE_Packed_Bytes4
);
631 -- Start of processing for Create_Packed_Array_Impl_Type
634 -- If we already have a packed array type, nothing to do
636 if Present
(Packed_Array_Impl_Type
(Typ
)) then
640 -- If our immediate ancestor subtype is constrained, and it already
641 -- has a packed array type, then just share the same type, since the
642 -- bounds must be the same. If the ancestor is not an array type but
643 -- a private type, as can happen with multiple instantiations, create
644 -- a new packed type, to avoid privacy issues.
646 if Ekind
(Typ
) = E_Array_Subtype
then
647 Ancest
:= Ancestor_Subtype
(Typ
);
650 and then Is_Array_Type
(Ancest
)
651 and then Is_Constrained
(Ancest
)
652 and then Present
(Packed_Array_Impl_Type
(Ancest
))
654 Set_Packed_Array_Impl_Type
(Typ
, Packed_Array_Impl_Type
(Ancest
));
659 -- We preset the result type size from the size of the original array
660 -- type, since this size clearly belongs to the packed array type. The
661 -- size of the conceptual unpacked type is always set to unknown.
663 PASize
:= RM_Size
(Typ
);
665 -- Case of an array where at least one index is of an enumeration
666 -- type with a non-standard representation, but the component size
667 -- is not appropriate for bit packing. This is the case where we
668 -- have Is_Packed set (we would never be in this unit otherwise),
669 -- but Is_Bit_Packed_Array is false.
671 -- Note that if the component size is appropriate for bit packing,
672 -- then the circuit for the computation of the subscript properly
673 -- deals with the non-standard enumeration type case by taking the
676 if not Is_Bit_Packed_Array
(Typ
) then
678 -- Here we build a declaration:
680 -- type tttP is array (index1, index2, ...) of component_type
682 -- where index1, index2, are the index types. These are the same
683 -- as the index types of the original array, except for the non-
684 -- standard representation enumeration type case, where we have
687 -- For the unconstrained array case, we use
691 -- For the constrained case, we use
693 -- Natural range Enum_Type'Pos (Enum_Type'First) ..
694 -- Enum_Type'Pos (Enum_Type'Last);
696 -- Note that tttP is created even if no index subtype is a non
697 -- standard enumeration, because we still need to remove padding
698 -- normally inserted for component alignment.
701 Make_Defining_Identifier
(Loc
,
702 Chars
=> New_External_Name
(Chars
(Typ
), 'P'));
705 Indexes
: constant List_Id
:= New_List
;
707 Indx_Typ
: Entity_Id
;
712 Indx
:= First_Index
(Typ
);
714 while Present
(Indx
) loop
715 Indx_Typ
:= Etype
(Indx
);
717 Enum_Case
:= Is_Enumeration_Type
(Indx_Typ
)
718 and then Has_Non_Standard_Rep
(Indx_Typ
);
720 -- Unconstrained case
722 if not Is_Constrained
(Typ
) then
724 Indx_Typ
:= Standard_Natural
;
727 Append_To
(Indexes
, New_Occurrence_Of
(Indx_Typ
, Loc
));
732 if not Enum_Case
then
733 Append_To
(Indexes
, New_Occurrence_Of
(Indx_Typ
, Loc
));
737 Make_Subtype_Indication
(Loc
,
739 New_Occurrence_Of
(Standard_Natural
, Loc
),
741 Make_Range_Constraint
(Loc
,
745 Make_Attribute_Reference
(Loc
,
747 New_Occurrence_Of
(Indx_Typ
, Loc
),
748 Attribute_Name
=> Name_Pos
,
749 Expressions
=> New_List
(
750 Make_Attribute_Reference
(Loc
,
752 New_Occurrence_Of
(Indx_Typ
, Loc
),
753 Attribute_Name
=> Name_First
))),
756 Make_Attribute_Reference
(Loc
,
758 New_Occurrence_Of
(Indx_Typ
, Loc
),
759 Attribute_Name
=> Name_Pos
,
760 Expressions
=> New_List
(
761 Make_Attribute_Reference
(Loc
,
763 New_Occurrence_Of
(Indx_Typ
, Loc
),
764 Attribute_Name
=> Name_Last
)))))));
772 if not Is_Constrained
(Typ
) then
774 Make_Unconstrained_Array_Definition
(Loc
,
775 Subtype_Marks
=> Indexes
,
776 Component_Definition
=>
777 Make_Component_Definition
(Loc
,
778 Aliased_Present
=> False,
779 Subtype_Indication
=>
780 New_Occurrence_Of
(Ctyp
, Loc
)));
784 Make_Constrained_Array_Definition
(Loc
,
785 Discrete_Subtype_Definitions
=> Indexes
,
786 Component_Definition
=>
787 Make_Component_Definition
(Loc
,
788 Aliased_Present
=> False,
789 Subtype_Indication
=>
790 New_Occurrence_Of
(Ctyp
, Loc
)));
794 Make_Full_Type_Declaration
(Loc
,
795 Defining_Identifier
=> PAT
,
796 Type_Definition
=> Typedef
);
802 -- Case of bit-packing required for unconstrained array. We create
803 -- a subtype that is equivalent to use Packed_Bytes{1,2,4} as needed.
805 elsif not Is_Constrained
(Typ
) then
807 -- When generating standard DWARF (i.e when GNAT_Encodings is
808 -- DWARF_GNAT_Encodings_Minimal), the ___XP suffix will be stripped
809 -- by the back-end but generate it anyway to ease compiler debugging.
810 -- This will help to distinguish implementation types from original
814 Make_Defining_Identifier
(Loc
,
815 Chars
=> Make_Packed_Array_Impl_Type_Name
(Typ
, Csize
));
820 Make_Subtype_Declaration
(Loc
,
821 Defining_Identifier
=> PAT
,
822 Subtype_Indication
=> New_Occurrence_Of
(PB_Type
, Loc
));
827 -- Remaining code is for the case of bit-packing for constrained array
829 -- The name of the packed array subtype is
833 -- where sss is the component size in bits and ttt is the name of
834 -- the parent packed type.
838 Make_Defining_Identifier
(Loc
,
839 Chars
=> Make_Packed_Array_Impl_Type_Name
(Typ
, Csize
));
841 -- Build an expression for the length of the array in bits.
842 -- This is the product of the length of each of the dimensions
844 Len_Expr
:= Compute_Number_Components
(Typ
, Typ
);
846 -- Temporarily attach the length expression to the tree and analyze
847 -- and resolve it, so that we can test its value. We assume that the
848 -- total length fits in type Integer. This expression may involve
849 -- discriminants, so we treat it as a default/per-object expression.
851 Set_Parent
(Len_Expr
, Typ
);
852 Preanalyze_Spec_Expression
(Len_Expr
, Standard_Long_Long_Integer
);
854 -- Use a modular type if possible. We can do this if we have
855 -- static bounds, and the length is small enough, and the length
856 -- is not zero. We exclude the zero length case because the size
857 -- of things is always at least one, and the zero length object
858 -- would have an anomalous size.
860 if Compile_Time_Known_Value
(Len_Expr
) then
861 Len_Bits
:= Expr_Value
(Len_Expr
) * Csize
;
863 -- Check for size known to be too large
866 Uint_2
** (Standard_Integer_Size
- 1) * System_Storage_Unit
868 if System_Storage_Unit
= 8 then
870 ("packed array size cannot exceed " &
871 "Integer''Last bytes", Typ
);
874 ("packed array size cannot exceed " &
875 "Integer''Last storage units", Typ
);
878 -- Reset length to arbitrary not too high value to continue
880 Len_Expr
:= Make_Integer_Literal
(Loc
, 65535);
881 Analyze_And_Resolve
(Len_Expr
, Standard_Long_Long_Integer
);
884 -- We normally consider small enough to mean no larger than the
885 -- value of System_Max_Binary_Modulus_Power, checking that in the
886 -- case of values longer than word size, we have long shifts.
890 (Len_Bits
<= System_Word_Size
891 or else (Len_Bits
<= System_Max_Binary_Modulus_Power
892 and then Support_Long_Shifts_On_Target
))
894 -- We can use the modular type, it has the form:
896 -- subtype tttPn is btyp
897 -- range 0 .. 2 ** ((Typ'Length (1)
898 -- * ... * Typ'Length (n)) * Csize) - 1;
900 -- The bounds are statically known, and btyp is one of the
901 -- unsigned types, depending on the length.
903 if Len_Bits
<= Standard_Short_Short_Integer_Size
then
904 Btyp
:= RTE
(RE_Short_Short_Unsigned
);
906 elsif Len_Bits
<= Standard_Short_Integer_Size
then
907 Btyp
:= RTE
(RE_Short_Unsigned
);
909 elsif Len_Bits
<= Standard_Integer_Size
then
910 Btyp
:= RTE
(RE_Unsigned
);
912 elsif Len_Bits
<= Standard_Long_Integer_Size
then
913 Btyp
:= RTE
(RE_Long_Unsigned
);
916 Btyp
:= RTE
(RE_Long_Long_Unsigned
);
919 Lit
:= Make_Integer_Literal
(Loc
, 2 ** Len_Bits
- 1);
920 Set_Print_In_Hex
(Lit
);
923 Make_Subtype_Declaration
(Loc
,
924 Defining_Identifier
=> PAT
,
925 Subtype_Indication
=>
926 Make_Subtype_Indication
(Loc
,
927 Subtype_Mark
=> New_Occurrence_Of
(Btyp
, Loc
),
930 Make_Range_Constraint
(Loc
,
934 Make_Integer_Literal
(Loc
, 0),
935 High_Bound
=> Lit
))));
937 if PASize
= Uint_0
then
943 -- Propagate a given alignment to the modular type. This can
944 -- cause it to be under-aligned, but that's OK.
946 if Present
(Alignment_Clause
(Typ
)) then
947 Set_Alignment
(PAT
, Alignment
(Typ
));
954 -- Could not use a modular type, for all other cases, we build
955 -- a packed array subtype:
958 -- System.Packed_Bytes{1,2,4} (0 .. (Bits + 7) / 8 - 1);
960 -- Bits is the length of the array in bits
967 Make_Op_Multiply
(Loc
,
969 Make_Integer_Literal
(Loc
, Csize
),
970 Right_Opnd
=> Len_Expr
),
973 Make_Integer_Literal
(Loc
, 7));
975 Set_Paren_Count
(Bits_U1
, 1);
978 Make_Op_Subtract
(Loc
,
981 Left_Opnd
=> Bits_U1
,
982 Right_Opnd
=> Make_Integer_Literal
(Loc
, 8)),
983 Right_Opnd
=> Make_Integer_Literal
(Loc
, 1));
986 Make_Subtype_Declaration
(Loc
,
987 Defining_Identifier
=> PAT
,
988 Subtype_Indication
=>
989 Make_Subtype_Indication
(Loc
,
990 Subtype_Mark
=> New_Occurrence_Of
(PB_Type
, Loc
),
992 Make_Index_Or_Discriminant_Constraint
(Loc
,
993 Constraints
=> New_List
(
996 Make_Integer_Literal
(Loc
, 0),
998 Convert_To
(Standard_Integer
, PAT_High
))))));
1002 -- Currently the code in this unit requires that packed arrays
1003 -- represented by non-modular arrays of bytes be on a byte
1004 -- boundary for bit sizes handled by System.Pack_nn units.
1005 -- That's because these units assume the array being accessed
1006 -- starts on a byte boundary.
1008 if Get_Id
(UI_To_Int
(Csize
)) /= RE_Null
then
1009 Set_Must_Be_On_Byte_Boundary
(Typ
);
1012 end Create_Packed_Array_Impl_Type
;
1014 -----------------------------------
1015 -- Expand_Bit_Packed_Element_Set --
1016 -----------------------------------
1018 procedure Expand_Bit_Packed_Element_Set
(N
: Node_Id
) is
1019 Loc
: constant Source_Ptr
:= Sloc
(N
);
1020 Lhs
: constant Node_Id
:= Name
(N
);
1022 Ass_OK
: constant Boolean := Assignment_OK
(Lhs
);
1023 -- Used to preserve assignment OK status when assignment is rewritten
1025 Rhs
: Node_Id
:= Expression
(N
);
1026 -- Initially Rhs is the right hand side value, it will be replaced
1027 -- later by an appropriate unchecked conversion for the assignment.
1037 -- The expression for the shift value that is required
1039 Shift_Used
: Boolean := False;
1040 -- Set True if Shift has been used in the generated code at least once,
1041 -- so that it must be duplicated if used again.
1046 Rhs_Val_Known
: Boolean;
1048 -- If the value of the right hand side as an integer constant is
1049 -- known at compile time, Rhs_Val_Known is set True, and Rhs_Val
1050 -- contains the value. Otherwise Rhs_Val_Known is set False, and
1051 -- the Rhs_Val is undefined.
1053 function Get_Shift
return Node_Id
;
1054 -- Function used to get the value of Shift, making sure that it
1055 -- gets duplicated if the function is called more than once.
1061 function Get_Shift
return Node_Id
is
1063 -- If we used the shift value already, then duplicate it. We
1064 -- set a temporary parent in case actions have to be inserted.
1067 Set_Parent
(Shift
, N
);
1068 return Duplicate_Subexpr_No_Checks
(Shift
);
1070 -- If first time, use Shift unchanged, and set flag for first use
1078 -- Start of processing for Expand_Bit_Packed_Element_Set
1081 pragma Assert
(Is_Bit_Packed_Array
(Etype
(Prefix
(Lhs
))));
1083 Obj
:= Relocate_Node
(Prefix
(Lhs
));
1084 Convert_To_Actual_Subtype
(Obj
);
1085 Atyp
:= Etype
(Obj
);
1086 PAT
:= Packed_Array_Impl_Type
(Atyp
);
1087 Ctyp
:= Component_Type
(Atyp
);
1088 Csiz
:= UI_To_Int
(Component_Size
(Atyp
));
1090 -- We remove side effects, in case the rhs modifies the lhs, because we
1091 -- are about to transform the rhs into an expression that first READS
1092 -- the lhs, so we can do the necessary shifting and masking. Example:
1093 -- "X(2) := F(...);" where F modifies X(3). Otherwise, the side effect
1096 Remove_Side_Effects
(Rhs
);
1098 -- We convert the right hand side to the proper subtype to ensure
1099 -- that an appropriate range check is made (since the normal range
1100 -- check from assignment will be lost in the transformations). This
1101 -- conversion is analyzed immediately so that subsequent processing
1102 -- can work with an analyzed Rhs (and e.g. look at its Etype)
1104 -- If the right-hand side is a string literal, create a temporary for
1105 -- it, constant-folding is not ready to wrap the bit representation
1106 -- of a string literal.
1108 if Nkind
(Rhs
) = N_String_Literal
then
1113 Make_Object_Declaration
(Loc
,
1114 Defining_Identifier
=> Make_Temporary
(Loc
, 'T', Rhs
),
1115 Object_Definition
=> New_Occurrence_Of
(Ctyp
, Loc
),
1116 Expression
=> New_Copy_Tree
(Rhs
));
1118 Insert_Actions
(N
, New_List
(Decl
));
1119 Rhs
:= New_Occurrence_Of
(Defining_Identifier
(Decl
), Loc
);
1123 Rhs
:= Convert_To
(Ctyp
, Rhs
);
1124 Set_Parent
(Rhs
, N
);
1126 -- If we are building the initialization procedure for a packed array,
1127 -- and Initialize_Scalars is enabled, each component assignment is an
1128 -- out-of-range value by design. Compile this value without checks,
1129 -- because a call to the array init_proc must not raise an exception.
1131 -- Condition is not consistent with description above, Within_Init_Proc
1132 -- is True also when we are building the IP for a record or protected
1133 -- type that has a packed array component???
1136 and then Initialize_Scalars
1138 Analyze_And_Resolve
(Rhs
, Ctyp
, Suppress
=> All_Checks
);
1140 Analyze_And_Resolve
(Rhs
, Ctyp
);
1143 -- Case of component size 1,2,4 or any component size for the modular
1144 -- case. These are the cases for which we can inline the code.
1146 if Csiz
= 1 or else Csiz
= 2 or else Csiz
= 4
1147 or else (Present
(PAT
) and then Is_Modular_Integer_Type
(PAT
))
1149 Setup_Inline_Packed_Array_Reference
(Lhs
, Atyp
, Obj
, Cmask
, Shift
);
1151 -- The statement to be generated is:
1153 -- Obj := atyp!((Obj and Mask1) or (shift_left (rhs, Shift)))
1155 -- or in the case of a freestanding Reverse_Storage_Order object,
1157 -- Obj := Swap (atyp!((Swap (Obj) and Mask1)
1158 -- or (shift_left (rhs, Shift))))
1160 -- where Mask1 is obtained by shifting Cmask left Shift bits
1161 -- and then complementing the result.
1163 -- the "and Mask1" is omitted if rhs is constant and all 1 bits
1165 -- the "or ..." is omitted if rhs is constant and all 0 bits
1167 -- rhs is converted to the appropriate type
1169 -- The result is converted back to the array type, since
1170 -- otherwise we lose knowledge of the packed nature.
1172 -- Determine if right side is all 0 bits or all 1 bits
1174 if Compile_Time_Known_Value
(Rhs
) then
1175 Rhs_Val
:= Expr_Rep_Value
(Rhs
);
1176 Rhs_Val_Known
:= True;
1178 -- The following test catches the case of an unchecked conversion of
1179 -- an integer literal. This results from optimizing aggregates of
1182 elsif Nkind
(Rhs
) = N_Unchecked_Type_Conversion
1183 and then Compile_Time_Known_Value
(Expression
(Rhs
))
1185 Rhs_Val
:= Expr_Rep_Value
(Expression
(Rhs
));
1186 Rhs_Val_Known
:= True;
1190 Rhs_Val_Known
:= False;
1193 -- Some special checks for the case where the right hand value is
1194 -- known at compile time. Basically we have to take care of the
1195 -- implicit conversion to the subtype of the component object.
1197 if Rhs_Val_Known
then
1199 -- If we have a biased component type then we must manually do the
1200 -- biasing, since we are taking responsibility in this case for
1201 -- constructing the exact bit pattern to be used.
1203 if Has_Biased_Representation
(Ctyp
) then
1204 Rhs_Val
:= Rhs_Val
- Expr_Rep_Value
(Type_Low_Bound
(Ctyp
));
1207 -- For a negative value, we manually convert the two's complement
1208 -- value to a corresponding unsigned value, so that the proper
1209 -- field width is maintained. If we did not do this, we would
1210 -- get too many leading sign bits later on.
1213 Rhs_Val
:= 2 ** UI_From_Int
(Csiz
) + Rhs_Val
;
1217 -- Now create copies removing side effects. Note that in some complex
1218 -- cases, this may cause the fact that we have already set a packed
1219 -- array type on Obj to get lost. So we save the type of Obj, and
1220 -- make sure it is reset properly.
1222 New_Lhs
:= Duplicate_Subexpr
(Obj
, Name_Req
=> True);
1223 New_Rhs
:= Duplicate_Subexpr_No_Checks
(Obj
);
1225 -- First we deal with the "and"
1227 if not Rhs_Val_Known
or else Rhs_Val
/= Cmask
then
1233 if Compile_Time_Known_Value
(Shift
) then
1235 Make_Integer_Literal
(Loc
,
1236 Modulus
(Etype
(Obj
)) - 1 -
1237 (Cmask
* (2 ** Expr_Value
(Get_Shift
))));
1238 Set_Print_In_Hex
(Mask1
);
1241 Lit
:= Make_Integer_Literal
(Loc
, Cmask
);
1242 Set_Print_In_Hex
(Lit
);
1245 Right_Opnd
=> Make_Shift_Left
(Lit
, Get_Shift
));
1250 Left_Opnd
=> New_Rhs
,
1251 Right_Opnd
=> Mask1
);
1255 -- Then deal with the "or"
1257 if not Rhs_Val_Known
or else Rhs_Val
/= 0 then
1261 procedure Fixup_Rhs
;
1262 -- Adjust Rhs by bias if biased representation for components
1263 -- or remove extraneous high order sign bits if signed.
1265 procedure Fixup_Rhs
is
1266 Etyp
: constant Entity_Id
:= Etype
(Rhs
);
1269 -- For biased case, do the required biasing by simply
1270 -- converting to the biased subtype (the conversion
1271 -- will generate the required bias).
1273 if Has_Biased_Representation
(Ctyp
) then
1274 Rhs
:= Convert_To
(Ctyp
, Rhs
);
1276 -- For a signed integer type that is not biased, generate
1277 -- a conversion to unsigned to strip high order sign bits.
1279 elsif Is_Signed_Integer_Type
(Ctyp
) then
1280 Rhs
:= Unchecked_Convert_To
(RTE
(Bits_Id
(Csiz
)), Rhs
);
1283 -- Set Etype, since it can be referenced before the node is
1284 -- completely analyzed.
1286 Set_Etype
(Rhs
, Etyp
);
1288 -- We now need to do an unchecked conversion of the
1289 -- result to the target type, but it is important that
1290 -- this conversion be a right justified conversion and
1291 -- not a left justified conversion.
1293 Rhs
:= RJ_Unchecked_Convert_To
(Etype
(Obj
), Rhs
);
1298 and then Compile_Time_Known_Value
(Get_Shift
)
1301 Make_Integer_Literal
(Loc
,
1302 Rhs_Val
* (2 ** Expr_Value
(Get_Shift
)));
1303 Set_Print_In_Hex
(Or_Rhs
);
1306 -- We have to convert the right hand side to Etype (Obj).
1307 -- A special case arises if what we have now is a Val
1308 -- attribute reference whose expression type is Etype (Obj).
1309 -- This happens for assignments of fields from the same
1310 -- array. In this case we get the required right hand side
1311 -- by simply removing the inner attribute reference.
1313 if Nkind
(Rhs
) = N_Attribute_Reference
1314 and then Attribute_Name
(Rhs
) = Name_Val
1315 and then Etype
(First
(Expressions
(Rhs
))) = Etype
(Obj
)
1317 Rhs
:= Relocate_Node
(First
(Expressions
(Rhs
)));
1320 -- If the value of the right hand side is a known integer
1321 -- value, then just replace it by an untyped constant,
1322 -- which will be properly retyped when we analyze and
1323 -- resolve the expression.
1325 elsif Rhs_Val_Known
then
1327 -- Note that Rhs_Val has already been normalized to
1328 -- be an unsigned value with the proper number of bits.
1330 Rhs
:= Make_Integer_Literal
(Loc
, Rhs_Val
);
1332 -- Otherwise we need an unchecked conversion
1338 Or_Rhs
:= Make_Shift_Left
(Rhs
, Get_Shift
);
1341 if Nkind
(New_Rhs
) = N_Op_And
then
1342 Set_Paren_Count
(New_Rhs
, 1);
1343 Set_Etype
(New_Rhs
, Etype
(Left_Opnd
(New_Rhs
)));
1348 Left_Opnd
=> New_Rhs
,
1349 Right_Opnd
=> Or_Rhs
);
1353 -- Now do the rewrite
1356 Make_Assignment_Statement
(Loc
,
1359 Unchecked_Convert_To
(Etype
(New_Lhs
), New_Rhs
)));
1360 Set_Assignment_OK
(Name
(N
), Ass_OK
);
1362 -- All other component sizes for non-modular case
1367 -- Set_nn (Arr'address, Subscr, Bits_nn!(Rhs))
1369 -- where Subscr is the computed linear subscript
1372 Bits_nn
: constant Entity_Id
:= RTE
(Bits_Id
(Csiz
));
1379 if No
(Bits_nn
) then
1381 -- Error, most likely High_Integrity_Mode restriction
1386 -- Acquire proper Set entity. We use the aligned or unaligned
1387 -- case as appropriate.
1389 if Known_Aligned_Enough
(Obj
, Csiz
) then
1390 Set_nn
:= RTE
(Set_Id
(Csiz
));
1392 Set_nn
:= RTE
(SetU_Id
(Csiz
));
1395 -- Now generate the set reference
1397 Obj
:= Relocate_Node
(Prefix
(Lhs
));
1398 Convert_To_Actual_Subtype
(Obj
);
1399 Atyp
:= Etype
(Obj
);
1400 Compute_Linear_Subscript
(Atyp
, Lhs
, Subscr
);
1402 -- Set indication of whether the packed array has reverse SSO
1406 (Boolean_Literals
(Reverse_Storage_Order
(Atyp
)), Loc
);
1408 -- Below we must make the assumption that Obj is
1409 -- at least byte aligned, since otherwise its address
1410 -- cannot be taken. The assumption holds since the
1411 -- only arrays that can be misaligned are small packed
1412 -- arrays which are implemented as a modular type, and
1413 -- that is not the case here.
1416 Make_Procedure_Call_Statement
(Loc
,
1417 Name
=> New_Occurrence_Of
(Set_nn
, Loc
),
1418 Parameter_Associations
=> New_List
(
1419 Make_Attribute_Reference
(Loc
,
1421 Attribute_Name
=> Name_Address
),
1423 Unchecked_Convert_To
(Bits_nn
, Convert_To
(Ctyp
, Rhs
)),
1429 Analyze
(N
, Suppress
=> All_Checks
);
1430 end Expand_Bit_Packed_Element_Set
;
1432 -------------------------------------
1433 -- Expand_Packed_Address_Reference --
1434 -------------------------------------
1436 procedure Expand_Packed_Address_Reference
(N
: Node_Id
) is
1437 Loc
: constant Source_Ptr
:= Sloc
(N
);
1442 -- We build an expression that has the form
1444 -- outer_object'Address
1445 -- + (linear-subscript * component_size for each array reference
1446 -- + field'Bit_Position for each record field
1448 -- + ...) / Storage_Unit;
1450 Get_Base_And_Bit_Offset
(Prefix
(N
), Base
, Offset
);
1453 Unchecked_Convert_To
(RTE
(RE_Address
),
1456 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
1457 Make_Attribute_Reference
(Loc
,
1459 Attribute_Name
=> Name_Address
)),
1462 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
1463 Make_Op_Divide
(Loc
,
1464 Left_Opnd
=> Offset
,
1466 Make_Integer_Literal
(Loc
, System_Storage_Unit
))))));
1468 Analyze_And_Resolve
(N
, RTE
(RE_Address
));
1469 end Expand_Packed_Address_Reference
;
1471 ---------------------------------
1472 -- Expand_Packed_Bit_Reference --
1473 ---------------------------------
1475 procedure Expand_Packed_Bit_Reference
(N
: Node_Id
) is
1476 Loc
: constant Source_Ptr
:= Sloc
(N
);
1481 -- We build an expression that has the form
1483 -- (linear-subscript * component_size for each array reference
1484 -- + field'Bit_Position for each record field
1486 -- + ...) mod Storage_Unit;
1488 Get_Base_And_Bit_Offset
(Prefix
(N
), Base
, Offset
);
1491 Unchecked_Convert_To
(Universal_Integer
,
1493 Left_Opnd
=> Offset
,
1494 Right_Opnd
=> Make_Integer_Literal
(Loc
, System_Storage_Unit
))));
1496 Analyze_And_Resolve
(N
, Universal_Integer
);
1497 end Expand_Packed_Bit_Reference
;
1499 ------------------------------------
1500 -- Expand_Packed_Boolean_Operator --
1501 ------------------------------------
1503 -- This routine expands "a op b" for the packed cases
1505 procedure Expand_Packed_Boolean_Operator
(N
: Node_Id
) is
1506 Loc
: constant Source_Ptr
:= Sloc
(N
);
1507 Typ
: constant Entity_Id
:= Etype
(N
);
1508 L
: constant Node_Id
:= Relocate_Node
(Left_Opnd
(N
));
1509 R
: constant Node_Id
:= Relocate_Node
(Right_Opnd
(N
));
1516 Convert_To_Actual_Subtype
(L
);
1517 Convert_To_Actual_Subtype
(R
);
1519 Ensure_Defined
(Etype
(L
), N
);
1520 Ensure_Defined
(Etype
(R
), N
);
1522 Apply_Length_Check
(R
, Etype
(L
));
1527 -- Deal with silly case of XOR where the subcomponent has a range
1528 -- True .. True where an exception must be raised.
1530 if Nkind
(N
) = N_Op_Xor
then
1531 Silly_Boolean_Array_Xor_Test
(N
, Rtyp
);
1534 -- Now that that silliness is taken care of, get packed array type
1536 Convert_To_PAT_Type
(L
);
1537 Convert_To_PAT_Type
(R
);
1541 -- For the modular case, we expand a op b into
1543 -- rtyp!(pat!(a) op pat!(b))
1545 -- where rtyp is the Etype of the left operand. Note that we do not
1546 -- convert to the base type, since this would be unconstrained, and
1547 -- hence not have a corresponding packed array type set.
1549 -- Note that both operands must be modular for this code to be used
1551 if Is_Modular_Integer_Type
(PAT
)
1553 Is_Modular_Integer_Type
(Etype
(R
))
1559 if Nkind
(N
) = N_Op_And
then
1560 P
:= Make_Op_And
(Loc
, L
, R
);
1562 elsif Nkind
(N
) = N_Op_Or
then
1563 P
:= Make_Op_Or
(Loc
, L
, R
);
1565 else -- Nkind (N) = N_Op_Xor
1566 P
:= Make_Op_Xor
(Loc
, L
, R
);
1569 Rewrite
(N
, Unchecked_Convert_To
(Ltyp
, P
));
1572 -- For the array case, we insert the actions
1576 -- System.Bit_Ops.Bit_And/Or/Xor
1578 -- Ltype'Length * Ltype'Component_Size;
1580 -- Rtype'Length * Rtype'Component_Size
1583 -- where Left and Right are the Packed_Bytes{1,2,4} operands and
1584 -- the second argument and fourth arguments are the lengths of the
1585 -- operands in bits. Then we replace the expression by a reference
1588 -- Note that if we are mixing a modular and array operand, everything
1589 -- works fine, since we ensure that the modular representation has the
1590 -- same physical layout as the array representation (that's what the
1591 -- left justified modular stuff in the big-endian case is about).
1595 Result_Ent
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T');
1599 if Nkind
(N
) = N_Op_And
then
1602 elsif Nkind
(N
) = N_Op_Or
then
1605 else -- Nkind (N) = N_Op_Xor
1609 Insert_Actions
(N
, New_List
(
1611 Make_Object_Declaration
(Loc
,
1612 Defining_Identifier
=> Result_Ent
,
1613 Object_Definition
=> New_Occurrence_Of
(Ltyp
, Loc
)),
1615 Make_Procedure_Call_Statement
(Loc
,
1616 Name
=> New_Occurrence_Of
(RTE
(E_Id
), Loc
),
1617 Parameter_Associations
=> New_List
(
1619 Make_Byte_Aligned_Attribute_Reference
(Loc
,
1621 Attribute_Name
=> Name_Address
),
1623 Make_Op_Multiply
(Loc
,
1625 Make_Attribute_Reference
(Loc
,
1628 (Etype
(First_Index
(Ltyp
)), Loc
),
1629 Attribute_Name
=> Name_Range_Length
),
1632 Make_Integer_Literal
(Loc
, Component_Size
(Ltyp
))),
1634 Make_Byte_Aligned_Attribute_Reference
(Loc
,
1636 Attribute_Name
=> Name_Address
),
1638 Make_Op_Multiply
(Loc
,
1640 Make_Attribute_Reference
(Loc
,
1643 (Etype
(First_Index
(Rtyp
)), Loc
),
1644 Attribute_Name
=> Name_Range_Length
),
1647 Make_Integer_Literal
(Loc
, Component_Size
(Rtyp
))),
1649 Make_Byte_Aligned_Attribute_Reference
(Loc
,
1650 Prefix
=> New_Occurrence_Of
(Result_Ent
, Loc
),
1651 Attribute_Name
=> Name_Address
)))));
1654 New_Occurrence_Of
(Result_Ent
, Loc
));
1658 Analyze_And_Resolve
(N
, Typ
, Suppress
=> All_Checks
);
1659 end Expand_Packed_Boolean_Operator
;
1661 -------------------------------------
1662 -- Expand_Packed_Element_Reference --
1663 -------------------------------------
1665 procedure Expand_Packed_Element_Reference
(N
: Node_Id
) is
1666 Loc
: constant Source_Ptr
:= Sloc
(N
);
1678 -- If the node is an actual in a call, the prefix has not been fully
1679 -- expanded, to account for the additional expansion for in-out actuals
1680 -- (see expand_actuals for details). If the prefix itself is a packed
1681 -- reference as well, we have to recurse to complete the transformation
1684 if Nkind
(Prefix
(N
)) = N_Indexed_Component
1685 and then not Analyzed
(Prefix
(N
))
1686 and then Is_Bit_Packed_Array
(Etype
(Prefix
(Prefix
(N
))))
1688 Expand_Packed_Element_Reference
(Prefix
(N
));
1691 -- The prefix may be rewritten below as a conversion. If it is a source
1692 -- entity generate reference to it now, to prevent spurious warnings
1693 -- about unused entities.
1695 if Is_Entity_Name
(Prefix
(N
))
1696 and then Comes_From_Source
(Prefix
(N
))
1698 Generate_Reference
(Entity
(Prefix
(N
)), Prefix
(N
), 'r');
1701 -- If not bit packed, we have the enumeration case, which is easily
1702 -- dealt with (just adjust the subscripts of the indexed component)
1704 -- Note: this leaves the result as an indexed component, which is
1705 -- still a variable, so can be used in the assignment case, as is
1706 -- required in the enumeration case.
1708 if not Is_Bit_Packed_Array
(Etype
(Prefix
(N
))) then
1709 Setup_Enumeration_Packed_Array_Reference
(N
);
1713 -- Remaining processing is for the bit-packed case
1715 Obj
:= Relocate_Node
(Prefix
(N
));
1716 Convert_To_Actual_Subtype
(Obj
);
1717 Atyp
:= Etype
(Obj
);
1718 PAT
:= Packed_Array_Impl_Type
(Atyp
);
1719 Ctyp
:= Component_Type
(Atyp
);
1720 Csiz
:= UI_To_Int
(Component_Size
(Atyp
));
1722 -- Case of component size 1,2,4 or any component size for the modular
1723 -- case. These are the cases for which we can inline the code.
1725 if Csiz
= 1 or else Csiz
= 2 or else Csiz
= 4
1726 or else (Present
(PAT
) and then Is_Modular_Integer_Type
(PAT
))
1728 Setup_Inline_Packed_Array_Reference
(N
, Atyp
, Obj
, Cmask
, Shift
);
1729 Lit
:= Make_Integer_Literal
(Loc
, Cmask
);
1730 Set_Print_In_Hex
(Lit
);
1732 -- We generate a shift right to position the field, followed by a
1733 -- masking operation to extract the bit field, and we finally do an
1734 -- unchecked conversion to convert the result to the required target.
1736 -- Note that the unchecked conversion automatically deals with the
1737 -- bias if we are dealing with a biased representation. What will
1738 -- happen is that we temporarily generate the biased representation,
1739 -- but almost immediately that will be converted to the original
1740 -- unbiased component type, and the bias will disappear.
1744 Left_Opnd
=> Make_Shift_Right
(Obj
, Shift
),
1746 Set_Etype
(Arg
, Ctyp
);
1748 -- Component extraction is performed on a native endianness scalar
1749 -- value: if Atyp has reverse storage order, then it has been byte
1750 -- swapped, and if the component being extracted is itself of a
1751 -- composite type with reverse storage order, then we need to swap
1752 -- it back to its expected endianness after extraction.
1754 if Reverse_Storage_Order
(Atyp
)
1755 and then (Is_Record_Type
(Ctyp
) or else Is_Array_Type
(Ctyp
))
1756 and then Reverse_Storage_Order
(Ctyp
)
1758 Arg
:= Revert_Storage_Order
(Arg
);
1761 -- We needed to analyze this before we do the unchecked convert
1762 -- below, but we need it temporarily attached to the tree for
1763 -- this analysis (hence the temporary Set_Parent call).
1765 Set_Parent
(Arg
, Parent
(N
));
1766 Analyze_And_Resolve
(Arg
);
1768 Rewrite
(N
, RJ_Unchecked_Convert_To
(Ctyp
, Arg
));
1770 -- All other component sizes for non-modular case
1775 -- Component_Type!(Get_nn (Arr'address, Subscr))
1777 -- where Subscr is the computed linear subscript
1782 Rev_SSO
: constant Node_Id
:=
1784 (Boolean_Literals
(Reverse_Storage_Order
(Atyp
)), Loc
);
1787 -- Acquire proper Get entity. We use the aligned or unaligned
1788 -- case as appropriate.
1790 if Known_Aligned_Enough
(Obj
, Csiz
) then
1791 Get_nn
:= RTE
(Get_Id
(Csiz
));
1793 Get_nn
:= RTE
(GetU_Id
(Csiz
));
1796 -- Now generate the get reference
1798 Compute_Linear_Subscript
(Atyp
, N
, Subscr
);
1800 -- Below we make the assumption that Obj is at least byte
1801 -- aligned, since otherwise its address cannot be taken.
1802 -- The assumption holds since the only arrays that can be
1803 -- misaligned are small packed arrays which are implemented
1804 -- as a modular type, and that is not the case here.
1807 Unchecked_Convert_To
(Ctyp
,
1808 Make_Function_Call
(Loc
,
1809 Name
=> New_Occurrence_Of
(Get_nn
, Loc
),
1810 Parameter_Associations
=> New_List
(
1811 Make_Attribute_Reference
(Loc
,
1813 Attribute_Name
=> Name_Address
),
1819 Analyze_And_Resolve
(N
, Ctyp
, Suppress
=> All_Checks
);
1820 end Expand_Packed_Element_Reference
;
1822 ----------------------
1823 -- Expand_Packed_Eq --
1824 ----------------------
1826 -- Handles expansion of "=" on packed array types
1828 procedure Expand_Packed_Eq
(N
: Node_Id
) is
1829 Loc
: constant Source_Ptr
:= Sloc
(N
);
1830 L
: constant Node_Id
:= Relocate_Node
(Left_Opnd
(N
));
1831 R
: constant Node_Id
:= Relocate_Node
(Right_Opnd
(N
));
1841 Convert_To_Actual_Subtype
(L
);
1842 Convert_To_Actual_Subtype
(R
);
1843 Ltyp
:= Underlying_Type
(Etype
(L
));
1844 Rtyp
:= Underlying_Type
(Etype
(R
));
1846 Convert_To_PAT_Type
(L
);
1847 Convert_To_PAT_Type
(R
);
1851 Make_Op_Multiply
(Loc
,
1852 Left_Opnd
=> Compute_Number_Components
(N
, Ltyp
),
1853 Right_Opnd
=> Make_Integer_Literal
(Loc
, Component_Size
(Ltyp
)));
1856 Make_Op_Multiply
(Loc
,
1857 Left_Opnd
=> Compute_Number_Components
(N
, Rtyp
),
1858 Right_Opnd
=> Make_Integer_Literal
(Loc
, Component_Size
(Rtyp
)));
1860 -- For the modular case, we transform the comparison to:
1862 -- Ltyp'Length = Rtyp'Length and then PAT!(L) = PAT!(R)
1864 -- where PAT is the packed array type. This works fine, since in the
1865 -- modular case we guarantee that the unused bits are always zeroes.
1866 -- We do have to compare the lengths because we could be comparing
1867 -- two different subtypes of the same base type.
1869 if Is_Modular_Integer_Type
(PAT
) then
1874 Left_Opnd
=> LLexpr
,
1875 Right_Opnd
=> RLexpr
),
1882 -- For the non-modular case, we call a runtime routine
1884 -- System.Bit_Ops.Bit_Eq
1885 -- (L'Address, L_Length, R'Address, R_Length)
1887 -- where PAT is the packed array type, and the lengths are the lengths
1888 -- in bits of the original packed arrays. This routine takes care of
1889 -- not comparing the unused bits in the last byte.
1893 Make_Function_Call
(Loc
,
1894 Name
=> New_Occurrence_Of
(RTE
(RE_Bit_Eq
), Loc
),
1895 Parameter_Associations
=> New_List
(
1896 Make_Byte_Aligned_Attribute_Reference
(Loc
,
1898 Attribute_Name
=> Name_Address
),
1902 Make_Byte_Aligned_Attribute_Reference
(Loc
,
1904 Attribute_Name
=> Name_Address
),
1909 Analyze_And_Resolve
(N
, Standard_Boolean
, Suppress
=> All_Checks
);
1910 end Expand_Packed_Eq
;
1912 -----------------------
1913 -- Expand_Packed_Not --
1914 -----------------------
1916 -- Handles expansion of "not" on packed array types
1918 procedure Expand_Packed_Not
(N
: Node_Id
) is
1919 Loc
: constant Source_Ptr
:= Sloc
(N
);
1920 Typ
: constant Entity_Id
:= Etype
(N
);
1921 Opnd
: constant Node_Id
:= Relocate_Node
(Right_Opnd
(N
));
1928 Convert_To_Actual_Subtype
(Opnd
);
1929 Rtyp
:= Etype
(Opnd
);
1931 -- Deal with silly False..False and True..True subtype case
1933 Silly_Boolean_Array_Not_Test
(N
, Rtyp
);
1935 -- Now that the silliness is taken care of, get packed array type
1937 Convert_To_PAT_Type
(Opnd
);
1938 PAT
:= Etype
(Opnd
);
1940 -- For the case where the packed array type is a modular type, "not A"
1941 -- expands simply into:
1943 -- Rtyp!(PAT!(A) xor Mask)
1945 -- where PAT is the packed array type, Mask is a mask of all 1 bits of
1946 -- length equal to the size of this packed type, and Rtyp is the actual
1947 -- actual subtype of the operand.
1949 Lit
:= Make_Integer_Literal
(Loc
, 2 ** RM_Size
(PAT
) - 1);
1950 Set_Print_In_Hex
(Lit
);
1952 if not Is_Array_Type
(PAT
) then
1954 Unchecked_Convert_To
(Rtyp
,
1957 Right_Opnd
=> Lit
)));
1959 -- For the array case, we insert the actions
1963 -- System.Bit_Ops.Bit_Not
1965 -- Typ'Length * Typ'Component_Size,
1968 -- where Opnd is the Packed_Bytes{1,2,4} operand and the second argument
1969 -- is the length of the operand in bits. We then replace the expression
1970 -- with a reference to Result.
1974 Result_Ent
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T');
1977 Insert_Actions
(N
, New_List
(
1978 Make_Object_Declaration
(Loc
,
1979 Defining_Identifier
=> Result_Ent
,
1980 Object_Definition
=> New_Occurrence_Of
(Rtyp
, Loc
)),
1982 Make_Procedure_Call_Statement
(Loc
,
1983 Name
=> New_Occurrence_Of
(RTE
(RE_Bit_Not
), Loc
),
1984 Parameter_Associations
=> New_List
(
1985 Make_Byte_Aligned_Attribute_Reference
(Loc
,
1987 Attribute_Name
=> Name_Address
),
1989 Make_Op_Multiply
(Loc
,
1991 Make_Attribute_Reference
(Loc
,
1994 (Etype
(First_Index
(Rtyp
)), Loc
),
1995 Attribute_Name
=> Name_Range_Length
),
1998 Make_Integer_Literal
(Loc
, Component_Size
(Rtyp
))),
2000 Make_Byte_Aligned_Attribute_Reference
(Loc
,
2001 Prefix
=> New_Occurrence_Of
(Result_Ent
, Loc
),
2002 Attribute_Name
=> Name_Address
)))));
2004 Rewrite
(N
, New_Occurrence_Of
(Result_Ent
, Loc
));
2008 Analyze_And_Resolve
(N
, Typ
, Suppress
=> All_Checks
);
2009 end Expand_Packed_Not
;
2011 -----------------------------
2012 -- Get_Base_And_Bit_Offset --
2013 -----------------------------
2015 procedure Get_Base_And_Bit_Offset
2018 Offset
: out Node_Id
)
2029 -- We build up an expression serially that has the form
2031 -- linear-subscript * component_size for each array reference
2032 -- + field'Bit_Position for each record field
2038 if Nkind
(Base
) = N_Indexed_Component
then
2039 Convert_To_Actual_Subtype
(Prefix
(Base
));
2040 Atyp
:= Etype
(Prefix
(Base
));
2041 Compute_Linear_Subscript
(Atyp
, Base
, Subscr
);
2044 Make_Op_Multiply
(Loc
,
2045 Left_Opnd
=> Subscr
,
2047 Make_Attribute_Reference
(Loc
,
2048 Prefix
=> New_Occurrence_Of
(Atyp
, Loc
),
2049 Attribute_Name
=> Name_Component_Size
));
2051 elsif Nkind
(Base
) = N_Selected_Component
then
2053 Make_Attribute_Reference
(Loc
,
2054 Prefix
=> Selector_Name
(Base
),
2055 Attribute_Name
=> Name_Bit_Position
);
2067 Left_Opnd
=> Offset
,
2068 Right_Opnd
=> Term
);
2071 Base
:= Prefix
(Base
);
2073 end Get_Base_And_Bit_Offset
;
2075 -------------------------------------
2076 -- Involves_Packed_Array_Reference --
2077 -------------------------------------
2079 function Involves_Packed_Array_Reference
(N
: Node_Id
) return Boolean is
2081 if Nkind
(N
) = N_Indexed_Component
2082 and then Is_Bit_Packed_Array
(Etype
(Prefix
(N
)))
2086 elsif Nkind
(N
) = N_Selected_Component
then
2087 return Involves_Packed_Array_Reference
(Prefix
(N
));
2092 end Involves_Packed_Array_Reference
;
2094 --------------------------
2095 -- Known_Aligned_Enough --
2096 --------------------------
2098 function Known_Aligned_Enough
(Obj
: Node_Id
; Csiz
: Nat
) return Boolean is
2099 Typ
: constant Entity_Id
:= Etype
(Obj
);
2101 function In_Partially_Packed_Record
(Comp
: Entity_Id
) return Boolean;
2102 -- If the component is in a record that contains previous packed
2103 -- components, consider it unaligned because the back-end might
2104 -- choose to pack the rest of the record. Lead to less efficient code,
2105 -- but safer vis-a-vis of back-end choices.
2107 --------------------------------
2108 -- In_Partially_Packed_Record --
2109 --------------------------------
2111 function In_Partially_Packed_Record
(Comp
: Entity_Id
) return Boolean is
2112 Rec_Type
: constant Entity_Id
:= Scope
(Comp
);
2113 Prev_Comp
: Entity_Id
;
2116 Prev_Comp
:= First_Entity
(Rec_Type
);
2117 while Present
(Prev_Comp
) loop
2118 if Is_Packed
(Etype
(Prev_Comp
)) then
2121 elsif Prev_Comp
= Comp
then
2125 Next_Entity
(Prev_Comp
);
2129 end In_Partially_Packed_Record
;
2131 -- Start of processing for Known_Aligned_Enough
2134 -- Odd bit sizes don't need alignment anyway
2136 if Csiz
mod 2 = 1 then
2139 -- If we have a specified alignment, see if it is sufficient, if not
2140 -- then we can't possibly be aligned enough in any case.
2142 elsif Known_Alignment
(Etype
(Obj
)) then
2143 -- Alignment required is 4 if size is a multiple of 4, and
2144 -- 2 otherwise (e.g. 12 bits requires 4, 10 bits requires 2)
2146 if Alignment
(Etype
(Obj
)) < 4 - (Csiz
mod 4) then
2151 -- OK, alignment should be sufficient, if object is aligned
2153 -- If object is strictly aligned, then it is definitely aligned
2155 if Strict_Alignment
(Typ
) then
2158 -- Case of subscripted array reference
2160 elsif Nkind
(Obj
) = N_Indexed_Component
then
2162 -- If we have a pointer to an array, then this is definitely
2163 -- aligned, because pointers always point to aligned versions.
2165 if Is_Access_Type
(Etype
(Prefix
(Obj
))) then
2168 -- Otherwise, go look at the prefix
2171 return Known_Aligned_Enough
(Prefix
(Obj
), Csiz
);
2174 -- Case of record field
2176 elsif Nkind
(Obj
) = N_Selected_Component
then
2178 -- What is significant here is whether the record type is packed
2180 if Is_Record_Type
(Etype
(Prefix
(Obj
)))
2181 and then Is_Packed
(Etype
(Prefix
(Obj
)))
2185 -- Or the component has a component clause which might cause
2186 -- the component to become unaligned (we can't tell if the
2187 -- backend is doing alignment computations).
2189 elsif Present
(Component_Clause
(Entity
(Selector_Name
(Obj
)))) then
2192 elsif In_Partially_Packed_Record
(Entity
(Selector_Name
(Obj
))) then
2195 -- In all other cases, go look at prefix
2198 return Known_Aligned_Enough
(Prefix
(Obj
), Csiz
);
2201 elsif Nkind
(Obj
) = N_Type_Conversion
then
2202 return Known_Aligned_Enough
(Expression
(Obj
), Csiz
);
2204 -- For a formal parameter, it is safer to assume that it is not
2205 -- aligned, because the formal may be unconstrained while the actual
2206 -- is constrained. In this situation, a small constrained packed
2207 -- array, represented in modular form, may be unaligned.
2209 elsif Is_Entity_Name
(Obj
) then
2210 return not Is_Formal
(Entity
(Obj
));
2213 -- If none of the above, must be aligned
2216 end Known_Aligned_Enough
;
2218 ---------------------
2219 -- Make_Shift_Left --
2220 ---------------------
2222 function Make_Shift_Left
(N
: Node_Id
; S
: Node_Id
) return Node_Id
is
2226 if Compile_Time_Known_Value
(S
) and then Expr_Value
(S
) = 0 then
2230 Make_Op_Shift_Left
(Sloc
(N
),
2233 Set_Shift_Count_OK
(Nod
, True);
2236 end Make_Shift_Left
;
2238 ----------------------
2239 -- Make_Shift_Right --
2240 ----------------------
2242 function Make_Shift_Right
(N
: Node_Id
; S
: Node_Id
) return Node_Id
is
2246 if Compile_Time_Known_Value
(S
) and then Expr_Value
(S
) = 0 then
2250 Make_Op_Shift_Right
(Sloc
(N
),
2253 Set_Shift_Count_OK
(Nod
, True);
2256 end Make_Shift_Right
;
2258 -----------------------------
2259 -- RJ_Unchecked_Convert_To --
2260 -----------------------------
2262 function RJ_Unchecked_Convert_To
2264 Expr
: Node_Id
) return Node_Id
2266 Source_Typ
: constant Entity_Id
:= Etype
(Expr
);
2267 Target_Typ
: constant Entity_Id
:= Typ
;
2269 Src
: Node_Id
:= Expr
;
2275 Source_Siz
:= UI_To_Int
(RM_Size
(Source_Typ
));
2276 Target_Siz
:= UI_To_Int
(RM_Size
(Target_Typ
));
2278 -- For a little-endian target type stored byte-swapped on a
2279 -- big-endian machine, do not mask to Target_Siz bits.
2282 and then (Is_Record_Type
(Target_Typ
)
2284 Is_Array_Type
(Target_Typ
))
2285 and then Reverse_Storage_Order
(Target_Typ
)
2287 Source_Siz
:= Target_Siz
;
2290 -- First step, if the source type is not a discrete type, then we first
2291 -- convert to a modular type of the source length, since otherwise, on
2292 -- a big-endian machine, we get left-justification. We do it for little-
2293 -- endian machines as well, because there might be junk bits that are
2294 -- not cleared if the type is not numeric. This can be done only if the
2295 -- source siz is different from 0 (i.e. known), otherwise we must trust
2296 -- the type declarations (case of non-discrete components).
2299 and then Source_Siz
/= Target_Siz
2300 and then not Is_Discrete_Type
(Source_Typ
)
2302 Src
:= Unchecked_Convert_To
(RTE
(Bits_Id
(Source_Siz
)), Src
);
2305 -- In the big endian case, if the lengths of the two types differ, then
2306 -- we must worry about possible left justification in the conversion,
2307 -- and avoiding that is what this is all about.
2309 if Bytes_Big_Endian
and then Source_Siz
/= Target_Siz
then
2311 -- Next step. If the target is not a discrete type, then we first
2312 -- convert to a modular type of the target length, since otherwise,
2313 -- on a big-endian machine, we get left-justification.
2315 if not Is_Discrete_Type
(Target_Typ
) then
2316 Src
:= Unchecked_Convert_To
(RTE
(Bits_Id
(Target_Siz
)), Src
);
2320 -- And now we can do the final conversion to the target type
2322 return Unchecked_Convert_To
(Target_Typ
, Src
);
2323 end RJ_Unchecked_Convert_To
;
2325 ----------------------------------------------
2326 -- Setup_Enumeration_Packed_Array_Reference --
2327 ----------------------------------------------
2329 -- All we have to do here is to find the subscripts that correspond to the
2330 -- index positions that have non-standard enumeration types and insert a
2331 -- Pos attribute to get the proper subscript value.
2333 -- Finally the prefix must be uncheck-converted to the corresponding packed
2336 -- Note that the component type is unchanged, so we do not need to fiddle
2337 -- with the types (Gigi always automatically takes the packed array type if
2338 -- it is set, as it will be in this case).
2340 procedure Setup_Enumeration_Packed_Array_Reference
(N
: Node_Id
) is
2341 Pfx
: constant Node_Id
:= Prefix
(N
);
2342 Typ
: constant Entity_Id
:= Etype
(N
);
2343 Exprs
: constant List_Id
:= Expressions
(N
);
2347 -- If the array is unconstrained, then we replace the array reference
2348 -- with its actual subtype. This actual subtype will have a packed array
2349 -- type with appropriate bounds.
2351 if not Is_Constrained
(Packed_Array_Impl_Type
(Etype
(Pfx
))) then
2352 Convert_To_Actual_Subtype
(Pfx
);
2355 Expr
:= First
(Exprs
);
2356 while Present
(Expr
) loop
2358 Loc
: constant Source_Ptr
:= Sloc
(Expr
);
2359 Expr_Typ
: constant Entity_Id
:= Etype
(Expr
);
2362 if Is_Enumeration_Type
(Expr_Typ
)
2363 and then Has_Non_Standard_Rep
(Expr_Typ
)
2366 Make_Attribute_Reference
(Loc
,
2367 Prefix
=> New_Occurrence_Of
(Expr_Typ
, Loc
),
2368 Attribute_Name
=> Name_Pos
,
2369 Expressions
=> New_List
(Relocate_Node
(Expr
))));
2370 Analyze_And_Resolve
(Expr
, Standard_Natural
);
2378 Make_Indexed_Component
(Sloc
(N
),
2380 Unchecked_Convert_To
(Packed_Array_Impl_Type
(Etype
(Pfx
)), Pfx
),
2381 Expressions
=> Exprs
));
2383 Analyze_And_Resolve
(N
, Typ
);
2384 end Setup_Enumeration_Packed_Array_Reference
;
2386 -----------------------------------------
2387 -- Setup_Inline_Packed_Array_Reference --
2388 -----------------------------------------
2390 procedure Setup_Inline_Packed_Array_Reference
2393 Obj
: in out Node_Id
;
2395 Shift
: out Node_Id
)
2397 Loc
: constant Source_Ptr
:= Sloc
(N
);
2404 Csiz
:= Component_Size
(Atyp
);
2406 Convert_To_PAT_Type
(Obj
);
2409 Cmask
:= 2 ** Csiz
- 1;
2411 if Is_Array_Type
(PAT
) then
2412 Otyp
:= Component_Type
(PAT
);
2413 Osiz
:= Component_Size
(PAT
);
2418 -- In the case where the PAT is a modular type, we want the actual
2419 -- size in bits of the modular value we use. This is neither the
2420 -- Object_Size nor the Value_Size, either of which may have been
2421 -- reset to strange values, but rather the minimum size. Note that
2422 -- since this is a modular type with full range, the issue of
2423 -- biased representation does not arise.
2425 Osiz
:= UI_From_Int
(Minimum_Size
(Otyp
));
2428 Compute_Linear_Subscript
(Atyp
, N
, Shift
);
2430 -- If the component size is not 1, then the subscript must be multiplied
2431 -- by the component size to get the shift count.
2435 Make_Op_Multiply
(Loc
,
2436 Left_Opnd
=> Make_Integer_Literal
(Loc
, Csiz
),
2437 Right_Opnd
=> Shift
);
2440 -- If we have the array case, then this shift count must be broken down
2441 -- into a byte subscript, and a shift within the byte.
2443 if Is_Array_Type
(PAT
) then
2446 New_Shift
: Node_Id
;
2449 -- We must analyze shift, since we will duplicate it
2451 Set_Parent
(Shift
, N
);
2453 (Shift
, Standard_Integer
, Suppress
=> All_Checks
);
2455 -- The shift count within the word is
2460 Left_Opnd
=> Duplicate_Subexpr
(Shift
),
2461 Right_Opnd
=> Make_Integer_Literal
(Loc
, Osiz
));
2463 -- The subscript to be used on the PAT array is
2467 Make_Indexed_Component
(Loc
,
2469 Expressions
=> New_List
(
2470 Make_Op_Divide
(Loc
,
2471 Left_Opnd
=> Duplicate_Subexpr
(Shift
),
2472 Right_Opnd
=> Make_Integer_Literal
(Loc
, Osiz
))));
2477 -- For the modular integer case, the object to be manipulated is the
2478 -- entire array, so Obj is unchanged. Note that we will reset its type
2479 -- to PAT before returning to the caller.
2485 -- The one remaining step is to modify the shift count for the
2486 -- big-endian case. Consider the following example in a byte:
2488 -- xxxxxxxx bits of byte
2489 -- vvvvvvvv bits of value
2490 -- 33221100 little-endian numbering
2491 -- 00112233 big-endian numbering
2493 -- Here we have the case of 2-bit fields
2495 -- For the little-endian case, we already have the proper shift count
2496 -- set, e.g. for element 2, the shift count is 2*2 = 4.
2498 -- For the big endian case, we have to adjust the shift count, computing
2499 -- it as (N - F) - Shift, where N is the number of bits in an element of
2500 -- the array used to implement the packed array, F is the number of bits
2501 -- in a source array element, and Shift is the count so far computed.
2503 -- We also have to adjust if the storage order is reversed
2505 if Bytes_Big_Endian
xor Reverse_Storage_Order
(Base_Type
(Atyp
)) then
2507 Make_Op_Subtract
(Loc
,
2508 Left_Opnd
=> Make_Integer_Literal
(Loc
, Osiz
- Csiz
),
2509 Right_Opnd
=> Shift
);
2512 Set_Parent
(Shift
, N
);
2513 Set_Parent
(Obj
, N
);
2514 Analyze_And_Resolve
(Obj
, Otyp
, Suppress
=> All_Checks
);
2515 Analyze_And_Resolve
(Shift
, Standard_Integer
, Suppress
=> All_Checks
);
2517 -- Make sure final type of object is the appropriate packed type
2519 Set_Etype
(Obj
, Otyp
);
2521 end Setup_Inline_Packed_Array_Reference
;