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* libgfortran.h (support_fpu_underflow_control,
[official-gcc.git] / gcc / ada / exp_pakd.adb
blob9569979960acfc0adff7e6fcf9fd26f032e82997
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- E X P _ P A K D --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2014, Free Software Foundation, Inc. --
10 -- --
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. --
20 -- --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
23 -- --
24 ------------------------------------------------------------------------------
25
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;
36 with Opt; use Opt;
37 with Rtsfind; use Rtsfind;
38 with Sem; use Sem;
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;
53
54 package body Exp_Pakd is
55
56 ---------------------------
57 -- Endian Considerations --
58 ---------------------------
59
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:
63
64 -- For little-endian machines, element zero is at the right hand end
65 -- (low order end) of a bit field.
66
67 -- For big-endian machines, element zero is at the left hand end
68 -- (high order end) of a bit field.
69
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.
79
80 ----------------------------------------------
81 -- Entity Tables for Packed Access Routines --
82 ----------------------------------------------
83
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.
86
87 type E_Array is array (Int range 01 .. 63) of RE_Id;
88
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.
93
94 Bits_Id : constant E_Array :=
95 (01 => RE_Bits_1,
96 02 => RE_Bits_2,
97 03 => RE_Bits_03,
98 04 => RE_Bits_4,
99 05 => RE_Bits_05,
100 06 => RE_Bits_06,
101 07 => RE_Bits_07,
102 08 => RE_Unsigned_8,
103 09 => RE_Bits_09,
104 10 => RE_Bits_10,
105 11 => RE_Bits_11,
106 12 => RE_Bits_12,
107 13 => RE_Bits_13,
108 14 => RE_Bits_14,
109 15 => RE_Bits_15,
110 16 => RE_Unsigned_16,
111 17 => RE_Bits_17,
112 18 => RE_Bits_18,
113 19 => RE_Bits_19,
114 20 => RE_Bits_20,
115 21 => RE_Bits_21,
116 22 => RE_Bits_22,
117 23 => RE_Bits_23,
118 24 => RE_Bits_24,
119 25 => RE_Bits_25,
120 26 => RE_Bits_26,
121 27 => RE_Bits_27,
122 28 => RE_Bits_28,
123 29 => RE_Bits_29,
124 30 => RE_Bits_30,
125 31 => RE_Bits_31,
126 32 => RE_Unsigned_32,
127 33 => RE_Bits_33,
128 34 => RE_Bits_34,
129 35 => RE_Bits_35,
130 36 => RE_Bits_36,
131 37 => RE_Bits_37,
132 38 => RE_Bits_38,
133 39 => RE_Bits_39,
134 40 => RE_Bits_40,
135 41 => RE_Bits_41,
136 42 => RE_Bits_42,
137 43 => RE_Bits_43,
138 44 => RE_Bits_44,
139 45 => RE_Bits_45,
140 46 => RE_Bits_46,
141 47 => RE_Bits_47,
142 48 => RE_Bits_48,
143 49 => RE_Bits_49,
144 50 => RE_Bits_50,
145 51 => RE_Bits_51,
146 52 => RE_Bits_52,
147 53 => RE_Bits_53,
148 54 => RE_Bits_54,
149 55 => RE_Bits_55,
150 56 => RE_Bits_56,
151 57 => RE_Bits_57,
152 58 => RE_Bits_58,
153 59 => RE_Bits_59,
154 60 => RE_Bits_60,
155 61 => RE_Bits_61,
156 62 => RE_Bits_62,
157 63 => RE_Bits_63);
158
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.
163
164 Get_Id : constant E_Array :=
165 (01 => RE_Null,
166 02 => RE_Null,
167 03 => RE_Get_03,
168 04 => RE_Null,
169 05 => RE_Get_05,
170 06 => RE_Get_06,
171 07 => RE_Get_07,
172 08 => RE_Null,
173 09 => RE_Get_09,
174 10 => RE_Get_10,
175 11 => RE_Get_11,
176 12 => RE_Get_12,
177 13 => RE_Get_13,
178 14 => RE_Get_14,
179 15 => RE_Get_15,
180 16 => RE_Null,
181 17 => RE_Get_17,
182 18 => RE_Get_18,
183 19 => RE_Get_19,
184 20 => RE_Get_20,
185 21 => RE_Get_21,
186 22 => RE_Get_22,
187 23 => RE_Get_23,
188 24 => RE_Get_24,
189 25 => RE_Get_25,
190 26 => RE_Get_26,
191 27 => RE_Get_27,
192 28 => RE_Get_28,
193 29 => RE_Get_29,
194 30 => RE_Get_30,
195 31 => RE_Get_31,
196 32 => RE_Null,
197 33 => RE_Get_33,
198 34 => RE_Get_34,
199 35 => RE_Get_35,
200 36 => RE_Get_36,
201 37 => RE_Get_37,
202 38 => RE_Get_38,
203 39 => RE_Get_39,
204 40 => RE_Get_40,
205 41 => RE_Get_41,
206 42 => RE_Get_42,
207 43 => RE_Get_43,
208 44 => RE_Get_44,
209 45 => RE_Get_45,
210 46 => RE_Get_46,
211 47 => RE_Get_47,
212 48 => RE_Get_48,
213 49 => RE_Get_49,
214 50 => RE_Get_50,
215 51 => RE_Get_51,
216 52 => RE_Get_52,
217 53 => RE_Get_53,
218 54 => RE_Get_54,
219 55 => RE_Get_55,
220 56 => RE_Get_56,
221 57 => RE_Get_57,
222 58 => RE_Get_58,
223 59 => RE_Get_59,
224 60 => RE_Get_60,
225 61 => RE_Get_61,
226 62 => RE_Get_62,
227 63 => RE_Get_63);
228
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.
233
234 GetU_Id : constant E_Array :=
235 (01 => RE_Null,
236 02 => RE_Null,
237 03 => RE_Get_03,
238 04 => RE_Null,
239 05 => RE_Get_05,
240 06 => RE_GetU_06,
241 07 => RE_Get_07,
242 08 => RE_Null,
243 09 => RE_Get_09,
244 10 => RE_GetU_10,
245 11 => RE_Get_11,
246 12 => RE_GetU_12,
247 13 => RE_Get_13,
248 14 => RE_GetU_14,
249 15 => RE_Get_15,
250 16 => RE_Null,
251 17 => RE_Get_17,
252 18 => RE_GetU_18,
253 19 => RE_Get_19,
254 20 => RE_GetU_20,
255 21 => RE_Get_21,
256 22 => RE_GetU_22,
257 23 => RE_Get_23,
258 24 => RE_GetU_24,
259 25 => RE_Get_25,
260 26 => RE_GetU_26,
261 27 => RE_Get_27,
262 28 => RE_GetU_28,
263 29 => RE_Get_29,
264 30 => RE_GetU_30,
265 31 => RE_Get_31,
266 32 => RE_Null,
267 33 => RE_Get_33,
268 34 => RE_GetU_34,
269 35 => RE_Get_35,
270 36 => RE_GetU_36,
271 37 => RE_Get_37,
272 38 => RE_GetU_38,
273 39 => RE_Get_39,
274 40 => RE_GetU_40,
275 41 => RE_Get_41,
276 42 => RE_GetU_42,
277 43 => RE_Get_43,
278 44 => RE_GetU_44,
279 45 => RE_Get_45,
280 46 => RE_GetU_46,
281 47 => RE_Get_47,
282 48 => RE_GetU_48,
283 49 => RE_Get_49,
284 50 => RE_GetU_50,
285 51 => RE_Get_51,
286 52 => RE_GetU_52,
287 53 => RE_Get_53,
288 54 => RE_GetU_54,
289 55 => RE_Get_55,
290 56 => RE_GetU_56,
291 57 => RE_Get_57,
292 58 => RE_GetU_58,
293 59 => RE_Get_59,
294 60 => RE_GetU_60,
295 61 => RE_Get_61,
296 62 => RE_GetU_62,
297 63 => RE_Get_63);
298
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.
303
304 Set_Id : constant E_Array :=
305 (01 => RE_Null,
306 02 => RE_Null,
307 03 => RE_Set_03,
308 04 => RE_Null,
309 05 => RE_Set_05,
310 06 => RE_Set_06,
311 07 => RE_Set_07,
312 08 => RE_Null,
313 09 => RE_Set_09,
314 10 => RE_Set_10,
315 11 => RE_Set_11,
316 12 => RE_Set_12,
317 13 => RE_Set_13,
318 14 => RE_Set_14,
319 15 => RE_Set_15,
320 16 => RE_Null,
321 17 => RE_Set_17,
322 18 => RE_Set_18,
323 19 => RE_Set_19,
324 20 => RE_Set_20,
325 21 => RE_Set_21,
326 22 => RE_Set_22,
327 23 => RE_Set_23,
328 24 => RE_Set_24,
329 25 => RE_Set_25,
330 26 => RE_Set_26,
331 27 => RE_Set_27,
332 28 => RE_Set_28,
333 29 => RE_Set_29,
334 30 => RE_Set_30,
335 31 => RE_Set_31,
336 32 => RE_Null,
337 33 => RE_Set_33,
338 34 => RE_Set_34,
339 35 => RE_Set_35,
340 36 => RE_Set_36,
341 37 => RE_Set_37,
342 38 => RE_Set_38,
343 39 => RE_Set_39,
344 40 => RE_Set_40,
345 41 => RE_Set_41,
346 42 => RE_Set_42,
347 43 => RE_Set_43,
348 44 => RE_Set_44,
349 45 => RE_Set_45,
350 46 => RE_Set_46,
351 47 => RE_Set_47,
352 48 => RE_Set_48,
353 49 => RE_Set_49,
354 50 => RE_Set_50,
355 51 => RE_Set_51,
356 52 => RE_Set_52,
357 53 => RE_Set_53,
358 54 => RE_Set_54,
359 55 => RE_Set_55,
360 56 => RE_Set_56,
361 57 => RE_Set_57,
362 58 => RE_Set_58,
363 59 => RE_Set_59,
364 60 => RE_Set_60,
365 61 => RE_Set_61,
366 62 => RE_Set_62,
367 63 => RE_Set_63);
368
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.
373
374 SetU_Id : constant E_Array :=
375 (01 => RE_Null,
376 02 => RE_Null,
377 03 => RE_Set_03,
378 04 => RE_Null,
379 05 => RE_Set_05,
380 06 => RE_SetU_06,
381 07 => RE_Set_07,
382 08 => RE_Null,
383 09 => RE_Set_09,
384 10 => RE_SetU_10,
385 11 => RE_Set_11,
386 12 => RE_SetU_12,
387 13 => RE_Set_13,
388 14 => RE_SetU_14,
389 15 => RE_Set_15,
390 16 => RE_Null,
391 17 => RE_Set_17,
392 18 => RE_SetU_18,
393 19 => RE_Set_19,
394 20 => RE_SetU_20,
395 21 => RE_Set_21,
396 22 => RE_SetU_22,
397 23 => RE_Set_23,
398 24 => RE_SetU_24,
399 25 => RE_Set_25,
400 26 => RE_SetU_26,
401 27 => RE_Set_27,
402 28 => RE_SetU_28,
403 29 => RE_Set_29,
404 30 => RE_SetU_30,
405 31 => RE_Set_31,
406 32 => RE_Null,
407 33 => RE_Set_33,
408 34 => RE_SetU_34,
409 35 => RE_Set_35,
410 36 => RE_SetU_36,
411 37 => RE_Set_37,
412 38 => RE_SetU_38,
413 39 => RE_Set_39,
414 40 => RE_SetU_40,
415 41 => RE_Set_41,
416 42 => RE_SetU_42,
417 43 => RE_Set_43,
418 44 => RE_SetU_44,
419 45 => RE_Set_45,
420 46 => RE_SetU_46,
421 47 => RE_Set_47,
422 48 => RE_SetU_48,
423 49 => RE_Set_49,
424 50 => RE_SetU_50,
425 51 => RE_Set_51,
426 52 => RE_SetU_52,
427 53 => RE_Set_53,
428 54 => RE_SetU_54,
429 55 => RE_Set_55,
430 56 => RE_SetU_56,
431 57 => RE_Set_57,
432 58 => RE_SetU_58,
433 59 => RE_Set_59,
434 60 => RE_SetU_60,
435 61 => RE_Set_61,
436 62 => RE_SetU_62,
437 63 => RE_Set_63);
438
439 -----------------------
440 -- Local Subprograms --
441 -----------------------
442
443 procedure Compute_Linear_Subscript
444 (Atyp : Entity_Id;
445 N : Node_Id;
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.
451
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.
456
457 procedure Get_Base_And_Bit_Offset
458 (N : Node_Id;
459 Base : out Node_Id;
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.
465
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
474 -- 2 otherwise.
475
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
478
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
481
482 function RJ_Unchecked_Convert_To
483 (Typ : Entity_Id;
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 endianness dependent, and the effect
488 -- we 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.
496
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.
503
504 procedure Setup_Inline_Packed_Array_Reference
505 (N : Node_Id;
506 Atyp : Entity_Id;
507 Obj : in out Node_Id;
508 Cmask : out Uint;
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).
515 --
516 -- On entry:
517 --
518 -- N is the N_Indexed_Component node for the packed array reference
519 --
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).
523 --
524 -- Obj is the object which is to be indexed. It is always of type Atyp.
525 --
526 -- On return:
527 --
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.
533 --
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.
537 --
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).
540 --
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.
545
546 function Revert_Storage_Order (N : Node_Id) return Node_Id;
547 -- Perform appropriate justification and byte ordering adjustments for N,
548 -- an element of a packed array type, when both the component type and
549 -- the enclosing packed array type have reverse scalar storage order.
550 -- On little-endian targets, the value is left justified before byte
551 -- swapping. The Etype of the returned expression is an integer type of
552 -- an appropriate power-of-2 size.
553
554 --------------------------
555 -- Revert_Storage_Order --
556 --------------------------
557
558 function Revert_Storage_Order (N : Node_Id) return Node_Id is
559 Loc : constant Source_Ptr := Sloc (N);
560 T : constant Entity_Id := Etype (N);
561 T_Size : constant Uint := RM_Size (T);
562
563 Swap_RE : RE_Id;
564 Swap_F : Entity_Id;
565 Swap_T : Entity_Id;
566 -- Swapping function
567
568 Arg : Node_Id;
569 Adjusted : Node_Id;
570 Shift : Uint;
571
572 begin
573 if T_Size <= 8 then
574
575 -- Array component size is less than a byte: no swapping needed
576
577 Swap_F := Empty;
578 Swap_T := RTE (RE_Unsigned_8);
579
580 else
581 -- Select byte swapping function depending on array component size
582
583 if T_Size <= 16 then
584 Swap_RE := RE_Bswap_16;
585
586 elsif T_Size <= 32 then
587 Swap_RE := RE_Bswap_32;
588
589 else pragma Assert (T_Size <= 64);
590 Swap_RE := RE_Bswap_64;
591 end if;
592
593 Swap_F := RTE (Swap_RE);
594 Swap_T := Etype (Swap_F);
595
596 end if;
597
598 Shift := Esize (Swap_T) - T_Size;
599
600 Arg := RJ_Unchecked_Convert_To (Swap_T, N);
601
602 if not Bytes_Big_Endian and then Shift > Uint_0 then
603 Arg :=
604 Make_Op_Shift_Left (Loc,
605 Left_Opnd => Arg,
606 Right_Opnd => Make_Integer_Literal (Loc, Shift));
607 end if;
608
609 if Present (Swap_F) then
610 Adjusted :=
611 Make_Function_Call (Loc,
612 Name => New_Occurrence_Of (Swap_F, Loc),
613 Parameter_Associations => New_List (Arg));
614 else
615 Adjusted := Arg;
616 end if;
617
618 Set_Etype (Adjusted, Swap_T);
619 return Adjusted;
620 end Revert_Storage_Order;
621
622 ------------------------------
623 -- Compute_Linear_Subscript --
624 ------------------------------
625
626 procedure Compute_Linear_Subscript
627 (Atyp : Entity_Id;
628 N : Node_Id;
629 Subscr : out Node_Id)
630 is
631 Loc : constant Source_Ptr := Sloc (N);
632 Oldsub : Node_Id;
633 Newsub : Node_Id;
634 Indx : Node_Id;
635 Styp : Entity_Id;
636
637 begin
638 Subscr := Empty;
639
640 -- Loop through dimensions
641
642 Indx := First_Index (Atyp);
643 Oldsub := First (Expressions (N));
644
645 while Present (Indx) loop
646 Styp := Etype (Indx);
647 Newsub := Relocate_Node (Oldsub);
648
649 -- Get expression for the subscript value. First, if Do_Range_Check
650 -- is set on a subscript, then we must do a range check against the
651 -- original bounds (not the bounds of the packed array type). We do
652 -- this by introducing a subtype conversion.
653
654 if Do_Range_Check (Newsub)
655 and then Etype (Newsub) /= Styp
656 then
657 Newsub := Convert_To (Styp, Newsub);
658 end if;
659
660 -- Now evolve the expression for the subscript. First convert
661 -- the subscript to be zero based and of an integer type.
662
663 -- Case of integer type, where we just subtract to get lower bound
664
665 if Is_Integer_Type (Styp) then
666
667 -- If length of integer type is smaller than standard integer,
668 -- then we convert to integer first, then do the subtract
669
670 -- Integer (subscript) - Integer (Styp'First)
671
672 if Esize (Styp) < Esize (Standard_Integer) then
673 Newsub :=
674 Make_Op_Subtract (Loc,
675 Left_Opnd => Convert_To (Standard_Integer, Newsub),
676 Right_Opnd =>
677 Convert_To (Standard_Integer,
678 Make_Attribute_Reference (Loc,
679 Prefix => New_Occurrence_Of (Styp, Loc),
680 Attribute_Name => Name_First)));
681
682 -- For larger integer types, subtract first, then convert to
683 -- integer, this deals with strange long long integer bounds.
684
685 -- Integer (subscript - Styp'First)
686
687 else
688 Newsub :=
689 Convert_To (Standard_Integer,
690 Make_Op_Subtract (Loc,
691 Left_Opnd => Newsub,
692 Right_Opnd =>
693 Make_Attribute_Reference (Loc,
694 Prefix => New_Occurrence_Of (Styp, Loc),
695 Attribute_Name => Name_First)));
696 end if;
697
698 -- For the enumeration case, we have to use 'Pos to get the value
699 -- to work with before subtracting the lower bound.
700
701 -- Integer (Styp'Pos (subscr)) - Integer (Styp'Pos (Styp'First));
702
703 -- This is not quite right for bizarre cases where the size of the
704 -- enumeration type is > Integer'Size bits due to rep clause ???
705
706 else
707 pragma Assert (Is_Enumeration_Type (Styp));
708
709 Newsub :=
710 Make_Op_Subtract (Loc,
711 Left_Opnd => Convert_To (Standard_Integer,
712 Make_Attribute_Reference (Loc,
713 Prefix => New_Occurrence_Of (Styp, Loc),
714 Attribute_Name => Name_Pos,
715 Expressions => New_List (Newsub))),
716
717 Right_Opnd =>
718 Convert_To (Standard_Integer,
719 Make_Attribute_Reference (Loc,
720 Prefix => New_Occurrence_Of (Styp, Loc),
721 Attribute_Name => Name_Pos,
722 Expressions => New_List (
723 Make_Attribute_Reference (Loc,
724 Prefix => New_Occurrence_Of (Styp, Loc),
725 Attribute_Name => Name_First)))));
726 end if;
727
728 Set_Paren_Count (Newsub, 1);
729
730 -- For the first subscript, we just copy that subscript value
731
732 if No (Subscr) then
733 Subscr := Newsub;
734
735 -- Otherwise, we must multiply what we already have by the current
736 -- stride and then add in the new value to the evolving subscript.
737
738 else
739 Subscr :=
740 Make_Op_Add (Loc,
741 Left_Opnd =>
742 Make_Op_Multiply (Loc,
743 Left_Opnd => Subscr,
744 Right_Opnd =>
745 Make_Attribute_Reference (Loc,
746 Attribute_Name => Name_Range_Length,
747 Prefix => New_Occurrence_Of (Styp, Loc))),
748 Right_Opnd => Newsub);
749 end if;
750
751 -- Move to next subscript
752
753 Next_Index (Indx);
754 Next (Oldsub);
755 end loop;
756 end Compute_Linear_Subscript;
757
758 -------------------------
759 -- Convert_To_PAT_Type --
760 -------------------------
761
762 -- The PAT is always obtained from the actual subtype
763
764 procedure Convert_To_PAT_Type (Aexp : Node_Id) is
765 Act_ST : Entity_Id;
766
767 begin
768 Convert_To_Actual_Subtype (Aexp);
769 Act_ST := Underlying_Type (Etype (Aexp));
770 Create_Packed_Array_Type (Act_ST);
771
772 -- Just replace the etype with the packed array type. This works because
773 -- the expression will not be further analyzed, and Gigi considers the
774 -- two types equivalent in any case.
775
776 -- This is not strictly the case ??? If the reference is an actual in
777 -- call, the expansion of the prefix is delayed, and must be reanalyzed,
778 -- see Reset_Packed_Prefix. On the other hand, if the prefix is a simple
779 -- array reference, reanalysis can produce spurious type errors when the
780 -- PAT type is replaced again with the original type of the array. Same
781 -- for the case of a dereference. Ditto for function calls: expansion
782 -- may introduce additional actuals which will trigger errors if call is
783 -- reanalyzed. The following is correct and minimal, but the handling of
784 -- more complex packed expressions in actuals is confused. Probably the
785 -- problem only remains for actuals in calls.
786
787 Set_Etype (Aexp, Packed_Array_Type (Act_ST));
788
789 if Is_Entity_Name (Aexp)
790 or else
791 (Nkind (Aexp) = N_Indexed_Component
792 and then Is_Entity_Name (Prefix (Aexp)))
793 or else Nkind_In (Aexp, N_Explicit_Dereference, N_Function_Call)
794 then
795 Set_Analyzed (Aexp);
796 end if;
797 end Convert_To_PAT_Type;
798
799 ------------------------------
800 -- Create_Packed_Array_Type --
801 ------------------------------
802
803 procedure Create_Packed_Array_Type (Typ : Entity_Id) is
804 Loc : constant Source_Ptr := Sloc (Typ);
805 Ctyp : constant Entity_Id := Component_Type (Typ);
806 Csize : constant Uint := Component_Size (Typ);
807
808 Ancest : Entity_Id;
809 PB_Type : Entity_Id;
810 PASize : Uint;
811 Decl : Node_Id;
812 PAT : Entity_Id;
813 Len_Dim : Node_Id;
814 Len_Expr : Node_Id;
815 Len_Bits : Uint;
816 Bits_U1 : Node_Id;
817 PAT_High : Node_Id;
818 Btyp : Entity_Id;
819 Lit : Node_Id;
820
821 procedure Install_PAT;
822 -- This procedure is called with Decl set to the declaration for the
823 -- packed array type. It creates the type and installs it as required.
824
825 procedure Set_PB_Type;
826 -- Sets PB_Type to Packed_Bytes{1,2,4} as required by the alignment
827 -- requirements (see documentation in the spec of this package).
828
829 -----------------
830 -- Install_PAT --
831 -----------------
832
833 procedure Install_PAT is
834 Pushed_Scope : Boolean := False;
835
836 begin
837 -- We do not want to put the declaration we have created in the tree
838 -- since it is often hard, and sometimes impossible to find a proper
839 -- place for it (the impossible case arises for a packed array type
840 -- with bounds depending on the discriminant, a declaration cannot
841 -- be put inside the record, and the reference to the discriminant
842 -- cannot be outside the record).
843
844 -- The solution is to analyze the declaration while temporarily
845 -- attached to the tree at an appropriate point, and then we install
846 -- the resulting type as an Itype in the packed array type field of
847 -- the original type, so that no explicit declaration is required.
848
849 -- Note: the packed type is created in the scope of its parent
850 -- type. There are at least some cases where the current scope
851 -- is deeper, and so when this is the case, we temporarily reset
852 -- the scope for the definition. This is clearly safe, since the
853 -- first use of the packed array type will be the implicit
854 -- reference from the corresponding unpacked type when it is
855 -- elaborated.
856
857 if Is_Itype (Typ) then
858 Set_Parent (Decl, Associated_Node_For_Itype (Typ));
859 else
860 Set_Parent (Decl, Declaration_Node (Typ));
861 end if;
862
863 if Scope (Typ) /= Current_Scope then
864 Push_Scope (Scope (Typ));
865 Pushed_Scope := True;
866 end if;
867
868 Set_Is_Itype (PAT, True);
869 Set_Packed_Array_Type (Typ, PAT);
870 Analyze (Decl, Suppress => All_Checks);
871
872 if Pushed_Scope then
873 Pop_Scope;
874 end if;
875
876 -- Set Esize and RM_Size to the actual size of the packed object
877 -- Do not reset RM_Size if already set, as happens in the case of
878 -- a modular type.
879
880 if Unknown_Esize (PAT) then
881 Set_Esize (PAT, PASize);
882 end if;
883
884 if Unknown_RM_Size (PAT) then
885 Set_RM_Size (PAT, PASize);
886 end if;
887
888 Adjust_Esize_Alignment (PAT);
889
890 -- Set remaining fields of packed array type
891
892 Init_Alignment (PAT);
893 Set_Parent (PAT, Empty);
894 Set_Associated_Node_For_Itype (PAT, Typ);
895 Set_Is_Packed_Array_Type (PAT, True);
896 Set_Original_Array_Type (PAT, Typ);
897
898 -- We definitely do not want to delay freezing for packed array
899 -- types. This is of particular importance for the itypes that
900 -- are generated for record components depending on discriminants
901 -- where there is no place to put the freeze node.
902
903 Set_Has_Delayed_Freeze (PAT, False);
904 Set_Has_Delayed_Freeze (Etype (PAT), False);
905
906 -- If we did allocate a freeze node, then clear out the reference
907 -- since it is obsolete (should we delete the freeze node???)
908
909 Set_Freeze_Node (PAT, Empty);
910 Set_Freeze_Node (Etype (PAT), Empty);
911 end Install_PAT;
912
913 -----------------
914 -- Set_PB_Type --
915 -----------------
916
917 procedure Set_PB_Type is
918 begin
919 -- If the user has specified an explicit alignment for the
920 -- type or component, take it into account.
921
922 if Csize <= 2 or else Csize = 4 or else Csize mod 2 /= 0
923 or else Alignment (Typ) = 1
924 or else Component_Alignment (Typ) = Calign_Storage_Unit
925 then
926 PB_Type := RTE (RE_Packed_Bytes1);
927
928 elsif Csize mod 4 /= 0
929 or else Alignment (Typ) = 2
930 then
931 PB_Type := RTE (RE_Packed_Bytes2);
932
933 else
934 PB_Type := RTE (RE_Packed_Bytes4);
935 end if;
936 end Set_PB_Type;
937
938 -- Start of processing for Create_Packed_Array_Type
939
940 begin
941 -- If we already have a packed array type, nothing to do
942
943 if Present (Packed_Array_Type (Typ)) then
944 return;
945 end if;
946
947 -- If our immediate ancestor subtype is constrained, and it already
948 -- has a packed array type, then just share the same type, since the
949 -- bounds must be the same. If the ancestor is not an array type but
950 -- a private type, as can happen with multiple instantiations, create
951 -- a new packed type, to avoid privacy issues.
952
953 if Ekind (Typ) = E_Array_Subtype then
954 Ancest := Ancestor_Subtype (Typ);
955
956 if Present (Ancest)
957 and then Is_Array_Type (Ancest)
958 and then Is_Constrained (Ancest)
959 and then Present (Packed_Array_Type (Ancest))
960 then
961 Set_Packed_Array_Type (Typ, Packed_Array_Type (Ancest));
962 return;
963 end if;
964 end if;
965
966 -- We preset the result type size from the size of the original array
967 -- type, since this size clearly belongs to the packed array type. The
968 -- size of the conceptual unpacked type is always set to unknown.
969
970 PASize := RM_Size (Typ);
971
972 -- Case of an array where at least one index is of an enumeration
973 -- type with a non-standard representation, but the component size
974 -- is not appropriate for bit packing. This is the case where we
975 -- have Is_Packed set (we would never be in this unit otherwise),
976 -- but Is_Bit_Packed_Array is false.
977
978 -- Note that if the component size is appropriate for bit packing,
979 -- then the circuit for the computation of the subscript properly
980 -- deals with the non-standard enumeration type case by taking the
981 -- Pos anyway.
982
983 if not Is_Bit_Packed_Array (Typ) then
984
985 -- Here we build a declaration:
986
987 -- type tttP is array (index1, index2, ...) of component_type
988
989 -- where index1, index2, are the index types. These are the same
990 -- as the index types of the original array, except for the non-
991 -- standard representation enumeration type case, where we have
992 -- two subcases.
993
994 -- For the unconstrained array case, we use
995
996 -- Natural range <>
997
998 -- For the constrained case, we use
999
1000 -- Natural range Enum_Type'Pos (Enum_Type'First) ..
1001 -- Enum_Type'Pos (Enum_Type'Last);
1002
1003 PAT :=
1004 Make_Defining_Identifier (Loc,
1005 Chars => New_External_Name (Chars (Typ), 'P'));
1006
1007 Set_Packed_Array_Type (Typ, PAT);
1008
1009 declare
1010 Indexes : constant List_Id := New_List;
1011 Indx : Node_Id;
1012 Indx_Typ : Entity_Id;
1013 Enum_Case : Boolean;
1014 Typedef : Node_Id;
1015
1016 begin
1017 Indx := First_Index (Typ);
1018
1019 while Present (Indx) loop
1020 Indx_Typ := Etype (Indx);
1021
1022 Enum_Case := Is_Enumeration_Type (Indx_Typ)
1023 and then Has_Non_Standard_Rep (Indx_Typ);
1024
1025 -- Unconstrained case
1026
1027 if not Is_Constrained (Typ) then
1028 if Enum_Case then
1029 Indx_Typ := Standard_Natural;
1030 end if;
1031
1032 Append_To (Indexes, New_Occurrence_Of (Indx_Typ, Loc));
1033
1034 -- Constrained case
1035
1036 else
1037 if not Enum_Case then
1038 Append_To (Indexes, New_Occurrence_Of (Indx_Typ, Loc));
1039
1040 else
1041 Append_To (Indexes,
1042 Make_Subtype_Indication (Loc,
1043 Subtype_Mark =>
1044 New_Occurrence_Of (Standard_Natural, Loc),
1045 Constraint =>
1046 Make_Range_Constraint (Loc,
1047 Range_Expression =>
1048 Make_Range (Loc,
1049 Low_Bound =>
1050 Make_Attribute_Reference (Loc,
1051 Prefix =>
1052 New_Occurrence_Of (Indx_Typ, Loc),
1053 Attribute_Name => Name_Pos,
1054 Expressions => New_List (
1055 Make_Attribute_Reference (Loc,
1056 Prefix =>
1057 New_Occurrence_Of (Indx_Typ, Loc),
1058 Attribute_Name => Name_First))),
1059
1060 High_Bound =>
1061 Make_Attribute_Reference (Loc,
1062 Prefix =>
1063 New_Occurrence_Of (Indx_Typ, Loc),
1064 Attribute_Name => Name_Pos,
1065 Expressions => New_List (
1066 Make_Attribute_Reference (Loc,
1067 Prefix =>
1068 New_Occurrence_Of (Indx_Typ, Loc),
1069 Attribute_Name => Name_Last)))))));
1070
1071 end if;
1072 end if;
1073
1074 Next_Index (Indx);
1075 end loop;
1076
1077 if not Is_Constrained (Typ) then
1078 Typedef :=
1079 Make_Unconstrained_Array_Definition (Loc,
1080 Subtype_Marks => Indexes,
1081 Component_Definition =>
1082 Make_Component_Definition (Loc,
1083 Aliased_Present => False,
1084 Subtype_Indication =>
1085 New_Occurrence_Of (Ctyp, Loc)));
1086
1087 else
1088 Typedef :=
1089 Make_Constrained_Array_Definition (Loc,
1090 Discrete_Subtype_Definitions => Indexes,
1091 Component_Definition =>
1092 Make_Component_Definition (Loc,
1093 Aliased_Present => False,
1094 Subtype_Indication =>
1095 New_Occurrence_Of (Ctyp, Loc)));
1096 end if;
1097
1098 Decl :=
1099 Make_Full_Type_Declaration (Loc,
1100 Defining_Identifier => PAT,
1101 Type_Definition => Typedef);
1102 end;
1103
1104 -- Set type as packed array type and install it
1105
1106 Set_Is_Packed_Array_Type (PAT);
1107 Install_PAT;
1108 return;
1109
1110 -- Case of bit-packing required for unconstrained array. We create
1111 -- a subtype that is equivalent to use Packed_Bytes{1,2,4} as needed.
1112
1113 elsif not Is_Constrained (Typ) then
1114 PAT :=
1115 Make_Defining_Identifier (Loc,
1116 Chars => Make_Packed_Array_Type_Name (Typ, Csize));
1117
1118 Set_Packed_Array_Type (Typ, PAT);
1119 Set_PB_Type;
1120
1121 Decl :=
1122 Make_Subtype_Declaration (Loc,
1123 Defining_Identifier => PAT,
1124 Subtype_Indication => New_Occurrence_Of (PB_Type, Loc));
1125 Install_PAT;
1126 return;
1127
1128 -- Remaining code is for the case of bit-packing for constrained array
1129
1130 -- The name of the packed array subtype is
1131
1132 -- ttt___XPsss
1133
1134 -- where sss is the component size in bits and ttt is the name of
1135 -- the parent packed type.
1136
1137 else
1138 PAT :=
1139 Make_Defining_Identifier (Loc,
1140 Chars => Make_Packed_Array_Type_Name (Typ, Csize));
1141
1142 Set_Packed_Array_Type (Typ, PAT);
1143
1144 -- Build an expression for the length of the array in bits.
1145 -- This is the product of the length of each of the dimensions
1146
1147 declare
1148 J : Nat := 1;
1149
1150 begin
1151 Len_Expr := Empty; -- suppress junk warning
1152
1153 loop
1154 Len_Dim :=
1155 Make_Attribute_Reference (Loc,
1156 Attribute_Name => Name_Length,
1157 Prefix => New_Occurrence_Of (Typ, Loc),
1158 Expressions => New_List (
1159 Make_Integer_Literal (Loc, J)));
1160
1161 if J = 1 then
1162 Len_Expr := Len_Dim;
1163
1164 else
1165 Len_Expr :=
1166 Make_Op_Multiply (Loc,
1167 Left_Opnd => Len_Expr,
1168 Right_Opnd => Len_Dim);
1169 end if;
1170
1171 J := J + 1;
1172 exit when J > Number_Dimensions (Typ);
1173 end loop;
1174 end;
1175
1176 -- Temporarily attach the length expression to the tree and analyze
1177 -- and resolve it, so that we can test its value. We assume that the
1178 -- total length fits in type Integer. This expression may involve
1179 -- discriminants, so we treat it as a default/per-object expression.
1180
1181 Set_Parent (Len_Expr, Typ);
1182 Preanalyze_Spec_Expression (Len_Expr, Standard_Long_Long_Integer);
1183
1184 -- Use a modular type if possible. We can do this if we have
1185 -- static bounds, and the length is small enough, and the length
1186 -- is not zero. We exclude the zero length case because the size
1187 -- of things is always at least one, and the zero length object
1188 -- would have an anomalous size.
1189
1190 if Compile_Time_Known_Value (Len_Expr) then
1191 Len_Bits := Expr_Value (Len_Expr) * Csize;
1192
1193 -- Check for size known to be too large
1194
1195 if Len_Bits >
1196 Uint_2 ** (Standard_Integer_Size - 1) * System_Storage_Unit
1197 then
1198 if System_Storage_Unit = 8 then
1199 Error_Msg_N
1200 ("packed array size cannot exceed " &
1201 "Integer''Last bytes", Typ);
1202 else
1203 Error_Msg_N
1204 ("packed array size cannot exceed " &
1205 "Integer''Last storage units", Typ);
1206 end if;
1207
1208 -- Reset length to arbitrary not too high value to continue
1209
1210 Len_Expr := Make_Integer_Literal (Loc, 65535);
1211 Analyze_And_Resolve (Len_Expr, Standard_Long_Long_Integer);
1212 end if;
1213
1214 -- We normally consider small enough to mean no larger than the
1215 -- value of System_Max_Binary_Modulus_Power, checking that in the
1216 -- case of values longer than word size, we have long shifts.
1217
1218 if Len_Bits > 0
1219 and then
1220 (Len_Bits <= System_Word_Size
1221 or else (Len_Bits <= System_Max_Binary_Modulus_Power
1222 and then Support_Long_Shifts_On_Target))
1223 then
1224 -- We can use the modular type, it has the form:
1225
1226 -- subtype tttPn is btyp
1227 -- range 0 .. 2 ** ((Typ'Length (1)
1228 -- * ... * Typ'Length (n)) * Csize) - 1;
1229
1230 -- The bounds are statically known, and btyp is one of the
1231 -- unsigned types, depending on the length.
1232
1233 if Len_Bits <= Standard_Short_Short_Integer_Size then
1234 Btyp := RTE (RE_Short_Short_Unsigned);
1235
1236 elsif Len_Bits <= Standard_Short_Integer_Size then
1237 Btyp := RTE (RE_Short_Unsigned);
1238
1239 elsif Len_Bits <= Standard_Integer_Size then
1240 Btyp := RTE (RE_Unsigned);
1241
1242 elsif Len_Bits <= Standard_Long_Integer_Size then
1243 Btyp := RTE (RE_Long_Unsigned);
1244
1245 else
1246 Btyp := RTE (RE_Long_Long_Unsigned);
1247 end if;
1248
1249 Lit := Make_Integer_Literal (Loc, 2 ** Len_Bits - 1);
1250 Set_Print_In_Hex (Lit);
1251
1252 Decl :=
1253 Make_Subtype_Declaration (Loc,
1254 Defining_Identifier => PAT,
1255 Subtype_Indication =>
1256 Make_Subtype_Indication (Loc,
1257 Subtype_Mark => New_Occurrence_Of (Btyp, Loc),
1258
1259 Constraint =>
1260 Make_Range_Constraint (Loc,
1261 Range_Expression =>
1262 Make_Range (Loc,
1263 Low_Bound =>
1264 Make_Integer_Literal (Loc, 0),
1265 High_Bound => Lit))));
1266
1267 if PASize = Uint_0 then
1268 PASize := Len_Bits;
1269 end if;
1270
1271 Install_PAT;
1272
1273 -- Propagate a given alignment to the modular type. This can
1274 -- cause it to be under-aligned, but that's OK.
1275
1276 if Present (Alignment_Clause (Typ)) then
1277 Set_Alignment (PAT, Alignment (Typ));
1278 end if;
1279
1280 return;
1281 end if;
1282 end if;
1283
1284 -- Could not use a modular type, for all other cases, we build
1285 -- a packed array subtype:
1286
1287 -- subtype tttPn is
1288 -- System.Packed_Bytes{1,2,4} (0 .. (Bits + 7) / 8 - 1);
1289
1290 -- Bits is the length of the array in bits
1291
1292 Set_PB_Type;
1293
1294 Bits_U1 :=
1295 Make_Op_Add (Loc,
1296 Left_Opnd =>
1297 Make_Op_Multiply (Loc,
1298 Left_Opnd =>
1299 Make_Integer_Literal (Loc, Csize),
1300 Right_Opnd => Len_Expr),
1301
1302 Right_Opnd =>
1303 Make_Integer_Literal (Loc, 7));
1304
1305 Set_Paren_Count (Bits_U1, 1);
1306
1307 PAT_High :=
1308 Make_Op_Subtract (Loc,
1309 Left_Opnd =>
1310 Make_Op_Divide (Loc,
1311 Left_Opnd => Bits_U1,
1312 Right_Opnd => Make_Integer_Literal (Loc, 8)),
1313 Right_Opnd => Make_Integer_Literal (Loc, 1));
1314
1315 Decl :=
1316 Make_Subtype_Declaration (Loc,
1317 Defining_Identifier => PAT,
1318 Subtype_Indication =>
1319 Make_Subtype_Indication (Loc,
1320 Subtype_Mark => New_Occurrence_Of (PB_Type, Loc),
1321 Constraint =>
1322 Make_Index_Or_Discriminant_Constraint (Loc,
1323 Constraints => New_List (
1324 Make_Range (Loc,
1325 Low_Bound =>
1326 Make_Integer_Literal (Loc, 0),
1327 High_Bound =>
1328 Convert_To (Standard_Integer, PAT_High))))));
1329
1330 Install_PAT;
1331
1332 -- Currently the code in this unit requires that packed arrays
1333 -- represented by non-modular arrays of bytes be on a byte
1334 -- boundary for bit sizes handled by System.Pack_nn units.
1335 -- That's because these units assume the array being accessed
1336 -- starts on a byte boundary.
1337
1338 if Get_Id (UI_To_Int (Csize)) /= RE_Null then
1339 Set_Must_Be_On_Byte_Boundary (Typ);
1340 end if;
1341 end if;
1342 end Create_Packed_Array_Type;
1343
1344 -----------------------------------
1345 -- Expand_Bit_Packed_Element_Set --
1346 -----------------------------------
1347
1348 procedure Expand_Bit_Packed_Element_Set (N : Node_Id) is
1349 Loc : constant Source_Ptr := Sloc (N);
1350 Lhs : constant Node_Id := Name (N);
1351
1352 Ass_OK : constant Boolean := Assignment_OK (Lhs);
1353 -- Used to preserve assignment OK status when assignment is rewritten
1354
1355 Rhs : Node_Id := Expression (N);
1356 -- Initially Rhs is the right hand side value, it will be replaced
1357 -- later by an appropriate unchecked conversion for the assignment.
1358
1359 Obj : Node_Id;
1360 Atyp : Entity_Id;
1361 PAT : Entity_Id;
1362 Ctyp : Entity_Id;
1363 Csiz : Int;
1364 Cmask : Uint;
1365
1366 Shift : Node_Id;
1367 -- The expression for the shift value that is required
1368
1369 Shift_Used : Boolean := False;
1370 -- Set True if Shift has been used in the generated code at least once,
1371 -- so that it must be duplicated if used again.
1372
1373 New_Lhs : Node_Id;
1374 New_Rhs : Node_Id;
1375
1376 Rhs_Val_Known : Boolean;
1377 Rhs_Val : Uint;
1378 -- If the value of the right hand side as an integer constant is
1379 -- known at compile time, Rhs_Val_Known is set True, and Rhs_Val
1380 -- contains the value. Otherwise Rhs_Val_Known is set False, and
1381 -- the Rhs_Val is undefined.
1382
1383 function Get_Shift return Node_Id;
1384 -- Function used to get the value of Shift, making sure that it
1385 -- gets duplicated if the function is called more than once.
1386
1387 ---------------
1388 -- Get_Shift --
1389 ---------------
1390
1391 function Get_Shift return Node_Id is
1392 begin
1393 -- If we used the shift value already, then duplicate it. We
1394 -- set a temporary parent in case actions have to be inserted.
1395
1396 if Shift_Used then
1397 Set_Parent (Shift, N);
1398 return Duplicate_Subexpr_No_Checks (Shift);
1399
1400 -- If first time, use Shift unchanged, and set flag for first use
1401
1402 else
1403 Shift_Used := True;
1404 return Shift;
1405 end if;
1406 end Get_Shift;
1407
1408 -- Start of processing for Expand_Bit_Packed_Element_Set
1409
1410 begin
1411 pragma Assert (Is_Bit_Packed_Array (Etype (Prefix (Lhs))));
1412
1413 Obj := Relocate_Node (Prefix (Lhs));
1414 Convert_To_Actual_Subtype (Obj);
1415 Atyp := Etype (Obj);
1416 PAT := Packed_Array_Type (Atyp);
1417 Ctyp := Component_Type (Atyp);
1418 Csiz := UI_To_Int (Component_Size (Atyp));
1419
1420 -- We remove side effects, in case the rhs modifies the lhs, because we
1421 -- are about to transform the rhs into an expression that first READS
1422 -- the lhs, so we can do the necessary shifting and masking. Example:
1423 -- "X(2) := F(...);" where F modifies X(3). Otherwise, the side effect
1424 -- will be lost.
1425
1426 Remove_Side_Effects (Rhs);
1427
1428 -- We convert the right hand side to the proper subtype to ensure
1429 -- that an appropriate range check is made (since the normal range
1430 -- check from assignment will be lost in the transformations). This
1431 -- conversion is analyzed immediately so that subsequent processing
1432 -- can work with an analyzed Rhs (and e.g. look at its Etype)
1433
1434 -- If the right-hand side is a string literal, create a temporary for
1435 -- it, constant-folding is not ready to wrap the bit representation
1436 -- of a string literal.
1437
1438 if Nkind (Rhs) = N_String_Literal then
1439 declare
1440 Decl : Node_Id;
1441 begin
1442 Decl :=
1443 Make_Object_Declaration (Loc,
1444 Defining_Identifier => Make_Temporary (Loc, 'T', Rhs),
1445 Object_Definition => New_Occurrence_Of (Ctyp, Loc),
1446 Expression => New_Copy_Tree (Rhs));
1447
1448 Insert_Actions (N, New_List (Decl));
1449 Rhs := New_Occurrence_Of (Defining_Identifier (Decl), Loc);
1450 end;
1451 end if;
1452
1453 Rhs := Convert_To (Ctyp, Rhs);
1454 Set_Parent (Rhs, N);
1455
1456 -- If we are building the initialization procedure for a packed array,
1457 -- and Initialize_Scalars is enabled, each component assignment is an
1458 -- out-of-range value by design. Compile this value without checks,
1459 -- because a call to the array init_proc must not raise an exception.
1460
1461 if Within_Init_Proc
1462 and then Initialize_Scalars
1463 then
1464 Analyze_And_Resolve (Rhs, Ctyp, Suppress => All_Checks);
1465 else
1466 Analyze_And_Resolve (Rhs, Ctyp);
1467 end if;
1468
1469 -- For the AAMP target, indexing of certain packed array is passed
1470 -- through to the back end without expansion, because the expansion
1471 -- results in very inefficient code on that target. This allows the
1472 -- GNAAMP back end to generate specialized macros that support more
1473 -- efficient indexing of packed arrays with components having sizes
1474 -- that are small powers of two.
1475
1476 if AAMP_On_Target
1477 and then (Csiz = 1 or else Csiz = 2 or else Csiz = 4)
1478 then
1479 return;
1480 end if;
1481
1482 -- Case of component size 1,2,4 or any component size for the modular
1483 -- case. These are the cases for which we can inline the code.
1484
1485 if Csiz = 1 or else Csiz = 2 or else Csiz = 4
1486 or else (Present (PAT) and then Is_Modular_Integer_Type (PAT))
1487 then
1488 Setup_Inline_Packed_Array_Reference (Lhs, Atyp, Obj, Cmask, Shift);
1489
1490 -- The statement to be generated is:
1491
1492 -- Obj := atyp!((Obj and Mask1) or (shift_left (rhs, Shift)))
1493
1494 -- or in the case of a freestanding Reverse_Storage_Order object,
1495
1496 -- Obj := Swap (atyp!((Swap (Obj) and Mask1)
1497 -- or (shift_left (rhs, Shift))))
1498
1499 -- where Mask1 is obtained by shifting Cmask left Shift bits
1500 -- and then complementing the result.
1501
1502 -- the "and Mask1" is omitted if rhs is constant and all 1 bits
1503
1504 -- the "or ..." is omitted if rhs is constant and all 0 bits
1505
1506 -- rhs is converted to the appropriate type
1507
1508 -- The result is converted back to the array type, since
1509 -- otherwise we lose knowledge of the packed nature.
1510
1511 -- Determine if right side is all 0 bits or all 1 bits
1512
1513 if Compile_Time_Known_Value (Rhs) then
1514 Rhs_Val := Expr_Rep_Value (Rhs);
1515 Rhs_Val_Known := True;
1516
1517 -- The following test catches the case of an unchecked conversion of
1518 -- an integer literal. This results from optimizing aggregates of
1519 -- packed types.
1520
1521 elsif Nkind (Rhs) = N_Unchecked_Type_Conversion
1522 and then Compile_Time_Known_Value (Expression (Rhs))
1523 then
1524 Rhs_Val := Expr_Rep_Value (Expression (Rhs));
1525 Rhs_Val_Known := True;
1526
1527 else
1528 Rhs_Val := No_Uint;
1529 Rhs_Val_Known := False;
1530 end if;
1531
1532 -- Some special checks for the case where the right hand value is
1533 -- known at compile time. Basically we have to take care of the
1534 -- implicit conversion to the subtype of the component object.
1535
1536 if Rhs_Val_Known then
1537
1538 -- If we have a biased component type then we must manually do the
1539 -- biasing, since we are taking responsibility in this case for
1540 -- constructing the exact bit pattern to be used.
1541
1542 if Has_Biased_Representation (Ctyp) then
1543 Rhs_Val := Rhs_Val - Expr_Rep_Value (Type_Low_Bound (Ctyp));
1544 end if;
1545
1546 -- For a negative value, we manually convert the two's complement
1547 -- value to a corresponding unsigned value, so that the proper
1548 -- field width is maintained. If we did not do this, we would
1549 -- get too many leading sign bits later on.
1550
1551 if Rhs_Val < 0 then
1552 Rhs_Val := 2 ** UI_From_Int (Csiz) + Rhs_Val;
1553 end if;
1554 end if;
1555
1556 -- Now create copies removing side effects. Note that in some complex
1557 -- cases, this may cause the fact that we have already set a packed
1558 -- array type on Obj to get lost. So we save the type of Obj, and
1559 -- make sure it is reset properly.
1560
1561 New_Lhs := Duplicate_Subexpr (Obj, Name_Req => True);
1562 New_Rhs := Duplicate_Subexpr_No_Checks (Obj);
1563
1564 -- First we deal with the "and"
1565
1566 if not Rhs_Val_Known or else Rhs_Val /= Cmask then
1567 declare
1568 Mask1 : Node_Id;
1569 Lit : Node_Id;
1570
1571 begin
1572 if Compile_Time_Known_Value (Shift) then
1573 Mask1 :=
1574 Make_Integer_Literal (Loc,
1575 Modulus (Etype (Obj)) - 1 -
1576 (Cmask * (2 ** Expr_Value (Get_Shift))));
1577 Set_Print_In_Hex (Mask1);
1578
1579 else
1580 Lit := Make_Integer_Literal (Loc, Cmask);
1581 Set_Print_In_Hex (Lit);
1582 Mask1 :=
1583 Make_Op_Not (Loc,
1584 Right_Opnd => Make_Shift_Left (Lit, Get_Shift));
1585 end if;
1586
1587 New_Rhs :=
1588 Make_Op_And (Loc,
1589 Left_Opnd => New_Rhs,
1590 Right_Opnd => Mask1);
1591 end;
1592 end if;
1593
1594 -- Then deal with the "or"
1595
1596 if not Rhs_Val_Known or else Rhs_Val /= 0 then
1597 declare
1598 Or_Rhs : Node_Id;
1599
1600 procedure Fixup_Rhs;
1601 -- Adjust Rhs by bias if biased representation for components
1602 -- or remove extraneous high order sign bits if signed.
1603
1604 procedure Fixup_Rhs is
1605 Etyp : constant Entity_Id := Etype (Rhs);
1606
1607 begin
1608 -- For biased case, do the required biasing by simply
1609 -- converting to the biased subtype (the conversion
1610 -- will generate the required bias).
1611
1612 if Has_Biased_Representation (Ctyp) then
1613 Rhs := Convert_To (Ctyp, Rhs);
1614
1615 -- For a signed integer type that is not biased, generate
1616 -- a conversion to unsigned to strip high order sign bits.
1617
1618 elsif Is_Signed_Integer_Type (Ctyp) then
1619 Rhs := Unchecked_Convert_To (RTE (Bits_Id (Csiz)), Rhs);
1620 end if;
1621
1622 -- Set Etype, since it can be referenced before the node is
1623 -- completely analyzed.
1624
1625 Set_Etype (Rhs, Etyp);
1626
1627 -- We now need to do an unchecked conversion of the
1628 -- result to the target type, but it is important that
1629 -- this conversion be a right justified conversion and
1630 -- not a left justified conversion.
1631
1632 Rhs := RJ_Unchecked_Convert_To (Etype (Obj), Rhs);
1633 end Fixup_Rhs;
1634
1635 begin
1636 if Rhs_Val_Known
1637 and then Compile_Time_Known_Value (Get_Shift)
1638 then
1639 Or_Rhs :=
1640 Make_Integer_Literal (Loc,
1641 Rhs_Val * (2 ** Expr_Value (Get_Shift)));
1642 Set_Print_In_Hex (Or_Rhs);
1643
1644 else
1645 -- We have to convert the right hand side to Etype (Obj).
1646 -- A special case arises if what we have now is a Val
1647 -- attribute reference whose expression type is Etype (Obj).
1648 -- This happens for assignments of fields from the same
1649 -- array. In this case we get the required right hand side
1650 -- by simply removing the inner attribute reference.
1651
1652 if Nkind (Rhs) = N_Attribute_Reference
1653 and then Attribute_Name (Rhs) = Name_Val
1654 and then Etype (First (Expressions (Rhs))) = Etype (Obj)
1655 then
1656 Rhs := Relocate_Node (First (Expressions (Rhs)));
1657 Fixup_Rhs;
1658
1659 -- If the value of the right hand side is a known integer
1660 -- value, then just replace it by an untyped constant,
1661 -- which will be properly retyped when we analyze and
1662 -- resolve the expression.
1663
1664 elsif Rhs_Val_Known then
1665
1666 -- Note that Rhs_Val has already been normalized to
1667 -- be an unsigned value with the proper number of bits.
1668
1669 Rhs := Make_Integer_Literal (Loc, Rhs_Val);
1670
1671 -- Otherwise we need an unchecked conversion
1672
1673 else
1674 Fixup_Rhs;
1675 end if;
1676
1677 Or_Rhs := Make_Shift_Left (Rhs, Get_Shift);
1678 end if;
1679
1680 if Nkind (New_Rhs) = N_Op_And then
1681 Set_Paren_Count (New_Rhs, 1);
1682 Set_Etype (New_Rhs, Etype (Left_Opnd (New_Rhs)));
1683 end if;
1684
1685 New_Rhs :=
1686 Make_Op_Or (Loc,
1687 Left_Opnd => New_Rhs,
1688 Right_Opnd => Or_Rhs);
1689 end;
1690 end if;
1691
1692 -- Now do the rewrite
1693
1694 Rewrite (N,
1695 Make_Assignment_Statement (Loc,
1696 Name => New_Lhs,
1697 Expression =>
1698 Unchecked_Convert_To (Etype (New_Lhs), New_Rhs)));
1699 Set_Assignment_OK (Name (N), Ass_OK);
1700
1701 -- All other component sizes for non-modular case
1702
1703 else
1704 -- We generate
1705
1706 -- Set_nn (Arr'address, Subscr, Bits_nn!(Rhs))
1707
1708 -- where Subscr is the computed linear subscript
1709
1710 declare
1711 Bits_nn : constant Entity_Id := RTE (Bits_Id (Csiz));
1712 Set_nn : Entity_Id;
1713 Subscr : Node_Id;
1714 Atyp : Entity_Id;
1715
1716 begin
1717 if No (Bits_nn) then
1718
1719 -- Error, most likely High_Integrity_Mode restriction
1720
1721 return;
1722 end if;
1723
1724 -- Acquire proper Set entity. We use the aligned or unaligned
1725 -- case as appropriate.
1726
1727 if Known_Aligned_Enough (Obj, Csiz) then
1728 Set_nn := RTE (Set_Id (Csiz));
1729 else
1730 Set_nn := RTE (SetU_Id (Csiz));
1731 end if;
1732
1733 -- Now generate the set reference
1734
1735 Obj := Relocate_Node (Prefix (Lhs));
1736 Convert_To_Actual_Subtype (Obj);
1737 Atyp := Etype (Obj);
1738 Compute_Linear_Subscript (Atyp, Lhs, Subscr);
1739
1740 -- Below we must make the assumption that Obj is
1741 -- at least byte aligned, since otherwise its address
1742 -- cannot be taken. The assumption holds since the
1743 -- only arrays that can be misaligned are small packed
1744 -- arrays which are implemented as a modular type, and
1745 -- that is not the case here.
1746
1747 Rewrite (N,
1748 Make_Procedure_Call_Statement (Loc,
1749 Name => New_Occurrence_Of (Set_nn, Loc),
1750 Parameter_Associations => New_List (
1751 Make_Attribute_Reference (Loc,
1752 Prefix => Obj,
1753 Attribute_Name => Name_Address),
1754 Subscr,
1755 Unchecked_Convert_To (Bits_nn,
1756 Convert_To (Ctyp, Rhs)))));
1757
1758 end;
1759 end if;
1760
1761 Analyze (N, Suppress => All_Checks);
1762 end Expand_Bit_Packed_Element_Set;
1763
1764 -------------------------------------
1765 -- Expand_Packed_Address_Reference --
1766 -------------------------------------
1767
1768 procedure Expand_Packed_Address_Reference (N : Node_Id) is
1769 Loc : constant Source_Ptr := Sloc (N);
1770 Base : Node_Id;
1771 Offset : Node_Id;
1772
1773 begin
1774 -- We build an expression that has the form
1775
1776 -- outer_object'Address
1777 -- + (linear-subscript * component_size for each array reference
1778 -- + field'Bit_Position for each record field
1779 -- + ...
1780 -- + ...) / Storage_Unit;
1781
1782 Get_Base_And_Bit_Offset (Prefix (N), Base, Offset);
1783
1784 Rewrite (N,
1785 Unchecked_Convert_To (RTE (RE_Address),
1786 Make_Op_Add (Loc,
1787 Left_Opnd =>
1788 Unchecked_Convert_To (RTE (RE_Integer_Address),
1789 Make_Attribute_Reference (Loc,
1790 Prefix => Base,
1791 Attribute_Name => Name_Address)),
1792
1793 Right_Opnd =>
1794 Unchecked_Convert_To (RTE (RE_Integer_Address),
1795 Make_Op_Divide (Loc,
1796 Left_Opnd => Offset,
1797 Right_Opnd =>
1798 Make_Integer_Literal (Loc, System_Storage_Unit))))));
1799
1800 Analyze_And_Resolve (N, RTE (RE_Address));
1801 end Expand_Packed_Address_Reference;
1802
1803 ---------------------------------
1804 -- Expand_Packed_Bit_Reference --
1805 ---------------------------------
1806
1807 procedure Expand_Packed_Bit_Reference (N : Node_Id) is
1808 Loc : constant Source_Ptr := Sloc (N);
1809 Base : Node_Id;
1810 Offset : Node_Id;
1811
1812 begin
1813 -- We build an expression that has the form
1814
1815 -- (linear-subscript * component_size for each array reference
1816 -- + field'Bit_Position for each record field
1817 -- + ...
1818 -- + ...) mod Storage_Unit;
1819
1820 Get_Base_And_Bit_Offset (Prefix (N), Base, Offset);
1821
1822 Rewrite (N,
1823 Unchecked_Convert_To (Universal_Integer,
1824 Make_Op_Mod (Loc,
1825 Left_Opnd => Offset,
1826 Right_Opnd => Make_Integer_Literal (Loc, System_Storage_Unit))));
1827
1828 Analyze_And_Resolve (N, Universal_Integer);
1829 end Expand_Packed_Bit_Reference;
1830
1831 ------------------------------------
1832 -- Expand_Packed_Boolean_Operator --
1833 ------------------------------------
1834
1835 -- This routine expands "a op b" for the packed cases
1836
1837 procedure Expand_Packed_Boolean_Operator (N : Node_Id) is
1838 Loc : constant Source_Ptr := Sloc (N);
1839 Typ : constant Entity_Id := Etype (N);
1840 L : constant Node_Id := Relocate_Node (Left_Opnd (N));
1841 R : constant Node_Id := Relocate_Node (Right_Opnd (N));
1842
1843 Ltyp : Entity_Id;
1844 Rtyp : Entity_Id;
1845 PAT : Entity_Id;
1846
1847 begin
1848 Convert_To_Actual_Subtype (L);
1849 Convert_To_Actual_Subtype (R);
1850
1851 Ensure_Defined (Etype (L), N);
1852 Ensure_Defined (Etype (R), N);
1853
1854 Apply_Length_Check (R, Etype (L));
1855
1856 Ltyp := Etype (L);
1857 Rtyp := Etype (R);
1858
1859 -- Deal with silly case of XOR where the subcomponent has a range
1860 -- True .. True where an exception must be raised.
1861
1862 if Nkind (N) = N_Op_Xor then
1863 Silly_Boolean_Array_Xor_Test (N, Rtyp);
1864 end if;
1865
1866 -- Now that that silliness is taken care of, get packed array type
1867
1868 Convert_To_PAT_Type (L);
1869 Convert_To_PAT_Type (R);
1870
1871 PAT := Etype (L);
1872
1873 -- For the modular case, we expand a op b into
1874
1875 -- rtyp!(pat!(a) op pat!(b))
1876
1877 -- where rtyp is the Etype of the left operand. Note that we do not
1878 -- convert to the base type, since this would be unconstrained, and
1879 -- hence not have a corresponding packed array type set.
1880
1881 -- Note that both operands must be modular for this code to be used
1882
1883 if Is_Modular_Integer_Type (PAT)
1884 and then
1885 Is_Modular_Integer_Type (Etype (R))
1886 then
1887 declare
1888 P : Node_Id;
1889
1890 begin
1891 if Nkind (N) = N_Op_And then
1892 P := Make_Op_And (Loc, L, R);
1893
1894 elsif Nkind (N) = N_Op_Or then
1895 P := Make_Op_Or (Loc, L, R);
1896
1897 else -- Nkind (N) = N_Op_Xor
1898 P := Make_Op_Xor (Loc, L, R);
1899 end if;
1900
1901 Rewrite (N, Unchecked_Convert_To (Ltyp, P));
1902 end;
1903
1904 -- For the array case, we insert the actions
1905
1906 -- Result : Ltype;
1907
1908 -- System.Bit_Ops.Bit_And/Or/Xor
1909 -- (Left'Address,
1910 -- Ltype'Length * Ltype'Component_Size;
1911 -- Right'Address,
1912 -- Rtype'Length * Rtype'Component_Size
1913 -- Result'Address);
1914
1915 -- where Left and Right are the Packed_Bytes{1,2,4} operands and
1916 -- the second argument and fourth arguments are the lengths of the
1917 -- operands in bits. Then we replace the expression by a reference
1918 -- to Result.
1919
1920 -- Note that if we are mixing a modular and array operand, everything
1921 -- works fine, since we ensure that the modular representation has the
1922 -- same physical layout as the array representation (that's what the
1923 -- left justified modular stuff in the big-endian case is about).
1924
1925 else
1926 declare
1927 Result_Ent : constant Entity_Id := Make_Temporary (Loc, 'T');
1928 E_Id : RE_Id;
1929
1930 begin
1931 if Nkind (N) = N_Op_And then
1932 E_Id := RE_Bit_And;
1933
1934 elsif Nkind (N) = N_Op_Or then
1935 E_Id := RE_Bit_Or;
1936
1937 else -- Nkind (N) = N_Op_Xor
1938 E_Id := RE_Bit_Xor;
1939 end if;
1940
1941 Insert_Actions (N, New_List (
1942
1943 Make_Object_Declaration (Loc,
1944 Defining_Identifier => Result_Ent,
1945 Object_Definition => New_Occurrence_Of (Ltyp, Loc)),
1946
1947 Make_Procedure_Call_Statement (Loc,
1948 Name => New_Occurrence_Of (RTE (E_Id), Loc),
1949 Parameter_Associations => New_List (
1950
1951 Make_Byte_Aligned_Attribute_Reference (Loc,
1952 Prefix => L,
1953 Attribute_Name => Name_Address),
1954
1955 Make_Op_Multiply (Loc,
1956 Left_Opnd =>
1957 Make_Attribute_Reference (Loc,
1958 Prefix =>
1959 New_Occurrence_Of
1960 (Etype (First_Index (Ltyp)), Loc),
1961 Attribute_Name => Name_Range_Length),
1962
1963 Right_Opnd =>
1964 Make_Integer_Literal (Loc, Component_Size (Ltyp))),
1965
1966 Make_Byte_Aligned_Attribute_Reference (Loc,
1967 Prefix => R,
1968 Attribute_Name => Name_Address),
1969
1970 Make_Op_Multiply (Loc,
1971 Left_Opnd =>
1972 Make_Attribute_Reference (Loc,
1973 Prefix =>
1974 New_Occurrence_Of
1975 (Etype (First_Index (Rtyp)), Loc),
1976 Attribute_Name => Name_Range_Length),
1977
1978 Right_Opnd =>
1979 Make_Integer_Literal (Loc, Component_Size (Rtyp))),
1980
1981 Make_Byte_Aligned_Attribute_Reference (Loc,
1982 Prefix => New_Occurrence_Of (Result_Ent, Loc),
1983 Attribute_Name => Name_Address)))));
1984
1985 Rewrite (N,
1986 New_Occurrence_Of (Result_Ent, Loc));
1987 end;
1988 end if;
1989
1990 Analyze_And_Resolve (N, Typ, Suppress => All_Checks);
1991 end Expand_Packed_Boolean_Operator;
1992
1993 -------------------------------------
1994 -- Expand_Packed_Element_Reference --
1995 -------------------------------------
1996
1997 procedure Expand_Packed_Element_Reference (N : Node_Id) is
1998 Loc : constant Source_Ptr := Sloc (N);
1999 Obj : Node_Id;
2000 Atyp : Entity_Id;
2001 PAT : Entity_Id;
2002 Ctyp : Entity_Id;
2003 Csiz : Int;
2004 Shift : Node_Id;
2005 Cmask : Uint;
2006 Lit : Node_Id;
2007 Arg : Node_Id;
2008
2009 begin
2010 -- If the node is an actual in a call, the prefix has not been fully
2011 -- expanded, to account for the additional expansion for in-out actuals
2012 -- (see expand_actuals for details). If the prefix itself is a packed
2013 -- reference as well, we have to recurse to complete the transformation
2014 -- of the prefix.
2015
2016 if Nkind (Prefix (N)) = N_Indexed_Component
2017 and then not Analyzed (Prefix (N))
2018 and then Is_Bit_Packed_Array (Etype (Prefix (Prefix (N))))
2019 then
2020 Expand_Packed_Element_Reference (Prefix (N));
2021 end if;
2022
2023 -- If not bit packed, we have the enumeration case, which is easily
2024 -- dealt with (just adjust the subscripts of the indexed component)
2025
2026 -- Note: this leaves the result as an indexed component, which is
2027 -- still a variable, so can be used in the assignment case, as is
2028 -- required in the enumeration case.
2029
2030 if not Is_Bit_Packed_Array (Etype (Prefix (N))) then
2031 Setup_Enumeration_Packed_Array_Reference (N);
2032 return;
2033 end if;
2034
2035 -- Remaining processing is for the bit-packed case
2036
2037 Obj := Relocate_Node (Prefix (N));
2038 Convert_To_Actual_Subtype (Obj);
2039 Atyp := Etype (Obj);
2040 PAT := Packed_Array_Type (Atyp);
2041 Ctyp := Component_Type (Atyp);
2042 Csiz := UI_To_Int (Component_Size (Atyp));
2043
2044 -- For the AAMP target, indexing of certain packed array is passed
2045 -- through to the back end without expansion, because the expansion
2046 -- results in very inefficient code on that target. This allows the
2047 -- GNAAMP back end to generate specialized macros that support more
2048 -- efficient indexing of packed arrays with components having sizes
2049 -- that are small powers of two.
2050
2051 if AAMP_On_Target
2052 and then (Csiz = 1 or else Csiz = 2 or else Csiz = 4)
2053 then
2054 return;
2055 end if;
2056
2057 -- Case of component size 1,2,4 or any component size for the modular
2058 -- case. These are the cases for which we can inline the code.
2059
2060 if Csiz = 1 or else Csiz = 2 or else Csiz = 4
2061 or else (Present (PAT) and then Is_Modular_Integer_Type (PAT))
2062 then
2063 Setup_Inline_Packed_Array_Reference (N, Atyp, Obj, Cmask, Shift);
2064 Lit := Make_Integer_Literal (Loc, Cmask);
2065 Set_Print_In_Hex (Lit);
2066
2067 -- We generate a shift right to position the field, followed by a
2068 -- masking operation to extract the bit field, and we finally do an
2069 -- unchecked conversion to convert the result to the required target.
2070
2071 -- Note that the unchecked conversion automatically deals with the
2072 -- bias if we are dealing with a biased representation. What will
2073 -- happen is that we temporarily generate the biased representation,
2074 -- but almost immediately that will be converted to the original
2075 -- unbiased component type, and the bias will disappear.
2076
2077 Arg :=
2078 Make_Op_And (Loc,
2079 Left_Opnd => Make_Shift_Right (Obj, Shift),
2080 Right_Opnd => Lit);
2081 Set_Etype (Arg, Ctyp);
2082
2083 -- Component extraction is performed on a native endianness scalar
2084 -- value: if Atyp has reverse storage order, then it has been byte
2085 -- swapped, and if the component being extracted is itself of a
2086 -- composite type with reverse storage order, then we need to swap
2087 -- it back to its expected endianness after extraction.
2088
2089 if Reverse_Storage_Order (Atyp)
2090 and then (Is_Record_Type (Ctyp) or else Is_Array_Type (Ctyp))
2091 and then Reverse_Storage_Order (Ctyp)
2092 then
2093 Arg := Revert_Storage_Order (Arg);
2094 end if;
2095
2096 -- We needed to analyze this before we do the unchecked convert
2097 -- below, but we need it temporarily attached to the tree for
2098 -- this analysis (hence the temporary Set_Parent call).
2099
2100 Set_Parent (Arg, Parent (N));
2101 Analyze_And_Resolve (Arg);
2102
2103 Rewrite (N, RJ_Unchecked_Convert_To (Ctyp, Arg));
2104
2105 -- All other component sizes for non-modular case
2106
2107 else
2108 -- We generate
2109
2110 -- Component_Type!(Get_nn (Arr'address, Subscr))
2111
2112 -- where Subscr is the computed linear subscript
2113
2114 declare
2115 Get_nn : Entity_Id;
2116 Subscr : Node_Id;
2117
2118 begin
2119 -- Acquire proper Get entity. We use the aligned or unaligned
2120 -- case as appropriate.
2121
2122 if Known_Aligned_Enough (Obj, Csiz) then
2123 Get_nn := RTE (Get_Id (Csiz));
2124 else
2125 Get_nn := RTE (GetU_Id (Csiz));
2126 end if;
2127
2128 -- Now generate the get reference
2129
2130 Compute_Linear_Subscript (Atyp, N, Subscr);
2131
2132 -- Below we make the assumption that Obj is at least byte
2133 -- aligned, since otherwise its address cannot be taken.
2134 -- The assumption holds since the only arrays that can be
2135 -- misaligned are small packed arrays which are implemented
2136 -- as a modular type, and that is not the case here.
2137
2138 Rewrite (N,
2139 Unchecked_Convert_To (Ctyp,
2140 Make_Function_Call (Loc,
2141 Name => New_Occurrence_Of (Get_nn, Loc),
2142 Parameter_Associations => New_List (
2143 Make_Attribute_Reference (Loc,
2144 Prefix => Obj,
2145 Attribute_Name => Name_Address),
2146 Subscr))));
2147 end;
2148 end if;
2149
2150 Analyze_And_Resolve (N, Ctyp, Suppress => All_Checks);
2151
2152 end Expand_Packed_Element_Reference;
2153
2154 ----------------------
2155 -- Expand_Packed_Eq --
2156 ----------------------
2157
2158 -- Handles expansion of "=" on packed array types
2159
2160 procedure Expand_Packed_Eq (N : Node_Id) is
2161 Loc : constant Source_Ptr := Sloc (N);
2162 L : constant Node_Id := Relocate_Node (Left_Opnd (N));
2163 R : constant Node_Id := Relocate_Node (Right_Opnd (N));
2164
2165 LLexpr : Node_Id;
2166 RLexpr : Node_Id;
2167
2168 Ltyp : Entity_Id;
2169 Rtyp : Entity_Id;
2170 PAT : Entity_Id;
2171
2172 begin
2173 Convert_To_Actual_Subtype (L);
2174 Convert_To_Actual_Subtype (R);
2175 Ltyp := Underlying_Type (Etype (L));
2176 Rtyp := Underlying_Type (Etype (R));
2177
2178 Convert_To_PAT_Type (L);
2179 Convert_To_PAT_Type (R);
2180 PAT := Etype (L);
2181
2182 LLexpr :=
2183 Make_Op_Multiply (Loc,
2184 Left_Opnd =>
2185 Make_Attribute_Reference (Loc,
2186 Prefix => New_Occurrence_Of (Ltyp, Loc),
2187 Attribute_Name => Name_Length),
2188 Right_Opnd =>
2189 Make_Integer_Literal (Loc, Component_Size (Ltyp)));
2190
2191 RLexpr :=
2192 Make_Op_Multiply (Loc,
2193 Left_Opnd =>
2194 Make_Attribute_Reference (Loc,
2195 Prefix => New_Occurrence_Of (Rtyp, Loc),
2196 Attribute_Name => Name_Length),
2197 Right_Opnd =>
2198 Make_Integer_Literal (Loc, Component_Size (Rtyp)));
2199
2200 -- For the modular case, we transform the comparison to:
2201
2202 -- Ltyp'Length = Rtyp'Length and then PAT!(L) = PAT!(R)
2203
2204 -- where PAT is the packed array type. This works fine, since in the
2205 -- modular case we guarantee that the unused bits are always zeroes.
2206 -- We do have to compare the lengths because we could be comparing
2207 -- two different subtypes of the same base type.
2208
2209 if Is_Modular_Integer_Type (PAT) then
2210 Rewrite (N,
2211 Make_And_Then (Loc,
2212 Left_Opnd =>
2213 Make_Op_Eq (Loc,
2214 Left_Opnd => LLexpr,
2215 Right_Opnd => RLexpr),
2216
2217 Right_Opnd =>
2218 Make_Op_Eq (Loc,
2219 Left_Opnd => L,
2220 Right_Opnd => R)));
2221
2222 -- For the non-modular case, we call a runtime routine
2223
2224 -- System.Bit_Ops.Bit_Eq
2225 -- (L'Address, L_Length, R'Address, R_Length)
2226
2227 -- where PAT is the packed array type, and the lengths are the lengths
2228 -- in bits of the original packed arrays. This routine takes care of
2229 -- not comparing the unused bits in the last byte.
2230
2231 else
2232 Rewrite (N,
2233 Make_Function_Call (Loc,
2234 Name => New_Occurrence_Of (RTE (RE_Bit_Eq), Loc),
2235 Parameter_Associations => New_List (
2236 Make_Byte_Aligned_Attribute_Reference (Loc,
2237 Prefix => L,
2238 Attribute_Name => Name_Address),
2239
2240 LLexpr,
2241
2242 Make_Byte_Aligned_Attribute_Reference (Loc,
2243 Prefix => R,
2244 Attribute_Name => Name_Address),
2245
2246 RLexpr)));
2247 end if;
2248
2249 Analyze_And_Resolve (N, Standard_Boolean, Suppress => All_Checks);
2250 end Expand_Packed_Eq;
2251
2252 -----------------------
2253 -- Expand_Packed_Not --
2254 -----------------------
2255
2256 -- Handles expansion of "not" on packed array types
2257
2258 procedure Expand_Packed_Not (N : Node_Id) is
2259 Loc : constant Source_Ptr := Sloc (N);
2260 Typ : constant Entity_Id := Etype (N);
2261 Opnd : constant Node_Id := Relocate_Node (Right_Opnd (N));
2262
2263 Rtyp : Entity_Id;
2264 PAT : Entity_Id;
2265 Lit : Node_Id;
2266
2267 begin
2268 Convert_To_Actual_Subtype (Opnd);
2269 Rtyp := Etype (Opnd);
2270
2271 -- Deal with silly False..False and True..True subtype case
2272
2273 Silly_Boolean_Array_Not_Test (N, Rtyp);
2274
2275 -- Now that the silliness is taken care of, get packed array type
2276
2277 Convert_To_PAT_Type (Opnd);
2278 PAT := Etype (Opnd);
2279
2280 -- For the case where the packed array type is a modular type, "not A"
2281 -- expands simply into:
2282
2283 -- Rtyp!(PAT!(A) xor Mask)
2284
2285 -- where PAT is the packed array type, Mask is a mask of all 1 bits of
2286 -- length equal to the size of this packed type, and Rtyp is the actual
2287 -- actual subtype of the operand.
2288
2289 Lit := Make_Integer_Literal (Loc, 2 ** RM_Size (PAT) - 1);
2290 Set_Print_In_Hex (Lit);
2291
2292 if not Is_Array_Type (PAT) then
2293 Rewrite (N,
2294 Unchecked_Convert_To (Rtyp,
2295 Make_Op_Xor (Loc,
2296 Left_Opnd => Opnd,
2297 Right_Opnd => Lit)));
2298
2299 -- For the array case, we insert the actions
2300
2301 -- Result : Typ;
2302
2303 -- System.Bit_Ops.Bit_Not
2304 -- (Opnd'Address,
2305 -- Typ'Length * Typ'Component_Size,
2306 -- Result'Address);
2307
2308 -- where Opnd is the Packed_Bytes{1,2,4} operand and the second argument
2309 -- is the length of the operand in bits. We then replace the expression
2310 -- with a reference to Result.
2311
2312 else
2313 declare
2314 Result_Ent : constant Entity_Id := Make_Temporary (Loc, 'T');
2315
2316 begin
2317 Insert_Actions (N, New_List (
2318 Make_Object_Declaration (Loc,
2319 Defining_Identifier => Result_Ent,
2320 Object_Definition => New_Occurrence_Of (Rtyp, Loc)),
2321
2322 Make_Procedure_Call_Statement (Loc,
2323 Name => New_Occurrence_Of (RTE (RE_Bit_Not), Loc),
2324 Parameter_Associations => New_List (
2325 Make_Byte_Aligned_Attribute_Reference (Loc,
2326 Prefix => Opnd,
2327 Attribute_Name => Name_Address),
2328
2329 Make_Op_Multiply (Loc,
2330 Left_Opnd =>
2331 Make_Attribute_Reference (Loc,
2332 Prefix =>
2333 New_Occurrence_Of
2334 (Etype (First_Index (Rtyp)), Loc),
2335 Attribute_Name => Name_Range_Length),
2336
2337 Right_Opnd =>
2338 Make_Integer_Literal (Loc, Component_Size (Rtyp))),
2339
2340 Make_Byte_Aligned_Attribute_Reference (Loc,
2341 Prefix => New_Occurrence_Of (Result_Ent, Loc),
2342 Attribute_Name => Name_Address)))));
2343
2344 Rewrite (N, New_Occurrence_Of (Result_Ent, Loc));
2345 end;
2346 end if;
2347
2348 Analyze_And_Resolve (N, Typ, Suppress => All_Checks);
2349 end Expand_Packed_Not;
2350
2351 -----------------------------
2352 -- Get_Base_And_Bit_Offset --
2353 -----------------------------
2354
2355 procedure Get_Base_And_Bit_Offset
2356 (N : Node_Id;
2357 Base : out Node_Id;
2358 Offset : out Node_Id)
2359 is
2360 Loc : Source_Ptr;
2361 Term : Node_Id;
2362 Atyp : Entity_Id;
2363 Subscr : Node_Id;
2364
2365 begin
2366 Base := N;
2367 Offset := Empty;
2368
2369 -- We build up an expression serially that has the form
2370
2371 -- linear-subscript * component_size for each array reference
2372 -- + field'Bit_Position for each record field
2373 -- + ...
2374
2375 loop
2376 Loc := Sloc (Base);
2377
2378 if Nkind (Base) = N_Indexed_Component then
2379 Convert_To_Actual_Subtype (Prefix (Base));
2380 Atyp := Etype (Prefix (Base));
2381 Compute_Linear_Subscript (Atyp, Base, Subscr);
2382
2383 Term :=
2384 Make_Op_Multiply (Loc,
2385 Left_Opnd => Subscr,
2386 Right_Opnd =>
2387 Make_Attribute_Reference (Loc,
2388 Prefix => New_Occurrence_Of (Atyp, Loc),
2389 Attribute_Name => Name_Component_Size));
2390
2391 elsif Nkind (Base) = N_Selected_Component then
2392 Term :=
2393 Make_Attribute_Reference (Loc,
2394 Prefix => Selector_Name (Base),
2395 Attribute_Name => Name_Bit_Position);
2396
2397 else
2398 return;
2399 end if;
2400
2401 if No (Offset) then
2402 Offset := Term;
2403
2404 else
2405 Offset :=
2406 Make_Op_Add (Loc,
2407 Left_Opnd => Offset,
2408 Right_Opnd => Term);
2409 end if;
2410
2411 Base := Prefix (Base);
2412 end loop;
2413 end Get_Base_And_Bit_Offset;
2414
2415 -------------------------------------
2416 -- Involves_Packed_Array_Reference --
2417 -------------------------------------
2418
2419 function Involves_Packed_Array_Reference (N : Node_Id) return Boolean is
2420 begin
2421 if Nkind (N) = N_Indexed_Component
2422 and then Is_Bit_Packed_Array (Etype (Prefix (N)))
2423 then
2424 return True;
2425
2426 elsif Nkind (N) = N_Selected_Component then
2427 return Involves_Packed_Array_Reference (Prefix (N));
2428
2429 else
2430 return False;
2431 end if;
2432 end Involves_Packed_Array_Reference;
2433
2434 --------------------------
2435 -- Known_Aligned_Enough --
2436 --------------------------
2437
2438 function Known_Aligned_Enough (Obj : Node_Id; Csiz : Nat) return Boolean is
2439 Typ : constant Entity_Id := Etype (Obj);
2440
2441 function In_Partially_Packed_Record (Comp : Entity_Id) return Boolean;
2442 -- If the component is in a record that contains previous packed
2443 -- components, consider it unaligned because the back-end might
2444 -- choose to pack the rest of the record. Lead to less efficient code,
2445 -- but safer vis-a-vis of back-end choices.
2446
2447 --------------------------------
2448 -- In_Partially_Packed_Record --
2449 --------------------------------
2450
2451 function In_Partially_Packed_Record (Comp : Entity_Id) return Boolean is
2452 Rec_Type : constant Entity_Id := Scope (Comp);
2453 Prev_Comp : Entity_Id;
2454
2455 begin
2456 Prev_Comp := First_Entity (Rec_Type);
2457 while Present (Prev_Comp) loop
2458 if Is_Packed (Etype (Prev_Comp)) then
2459 return True;
2460
2461 elsif Prev_Comp = Comp then
2462 return False;
2463 end if;
2464
2465 Next_Entity (Prev_Comp);
2466 end loop;
2467
2468 return False;
2469 end In_Partially_Packed_Record;
2470
2471 -- Start of processing for Known_Aligned_Enough
2472
2473 begin
2474 -- Odd bit sizes don't need alignment anyway
2475
2476 if Csiz mod 2 = 1 then
2477 return True;
2478
2479 -- If we have a specified alignment, see if it is sufficient, if not
2480 -- then we can't possibly be aligned enough in any case.
2481
2482 elsif Known_Alignment (Etype (Obj)) then
2483 -- Alignment required is 4 if size is a multiple of 4, and
2484 -- 2 otherwise (e.g. 12 bits requires 4, 10 bits requires 2)
2485
2486 if Alignment (Etype (Obj)) < 4 - (Csiz mod 4) then
2487 return False;
2488 end if;
2489 end if;
2490
2491 -- OK, alignment should be sufficient, if object is aligned
2492
2493 -- If object is strictly aligned, then it is definitely aligned
2494
2495 if Strict_Alignment (Typ) then
2496 return True;
2497
2498 -- Case of subscripted array reference
2499
2500 elsif Nkind (Obj) = N_Indexed_Component then
2501
2502 -- If we have a pointer to an array, then this is definitely
2503 -- aligned, because pointers always point to aligned versions.
2504
2505 if Is_Access_Type (Etype (Prefix (Obj))) then
2506 return True;
2507
2508 -- Otherwise, go look at the prefix
2509
2510 else
2511 return Known_Aligned_Enough (Prefix (Obj), Csiz);
2512 end if;
2513
2514 -- Case of record field
2515
2516 elsif Nkind (Obj) = N_Selected_Component then
2517
2518 -- What is significant here is whether the record type is packed
2519
2520 if Is_Record_Type (Etype (Prefix (Obj)))
2521 and then Is_Packed (Etype (Prefix (Obj)))
2522 then
2523 return False;
2524
2525 -- Or the component has a component clause which might cause
2526 -- the component to become unaligned (we can't tell if the
2527 -- backend is doing alignment computations).
2528
2529 elsif Present (Component_Clause (Entity (Selector_Name (Obj)))) then
2530 return False;
2531
2532 elsif In_Partially_Packed_Record (Entity (Selector_Name (Obj))) then
2533 return False;
2534
2535 -- In all other cases, go look at prefix
2536
2537 else
2538 return Known_Aligned_Enough (Prefix (Obj), Csiz);
2539 end if;
2540
2541 elsif Nkind (Obj) = N_Type_Conversion then
2542 return Known_Aligned_Enough (Expression (Obj), Csiz);
2543
2544 -- For a formal parameter, it is safer to assume that it is not
2545 -- aligned, because the formal may be unconstrained while the actual
2546 -- is constrained. In this situation, a small constrained packed
2547 -- array, represented in modular form, may be unaligned.
2548
2549 elsif Is_Entity_Name (Obj) then
2550 return not Is_Formal (Entity (Obj));
2551 else
2552
2553 -- If none of the above, must be aligned
2554 return True;
2555 end if;
2556 end Known_Aligned_Enough;
2557
2558 ---------------------
2559 -- Make_Shift_Left --
2560 ---------------------
2561
2562 function Make_Shift_Left (N : Node_Id; S : Node_Id) return Node_Id is
2563 Nod : Node_Id;
2564
2565 begin
2566 if Compile_Time_Known_Value (S) and then Expr_Value (S) = 0 then
2567 return N;
2568 else
2569 Nod :=
2570 Make_Op_Shift_Left (Sloc (N),
2571 Left_Opnd => N,
2572 Right_Opnd => S);
2573 Set_Shift_Count_OK (Nod, True);
2574 return Nod;
2575 end if;
2576 end Make_Shift_Left;
2577
2578 ----------------------
2579 -- Make_Shift_Right --
2580 ----------------------
2581
2582 function Make_Shift_Right (N : Node_Id; S : Node_Id) return Node_Id is
2583 Nod : Node_Id;
2584
2585 begin
2586 if Compile_Time_Known_Value (S) and then Expr_Value (S) = 0 then
2587 return N;
2588 else
2589 Nod :=
2590 Make_Op_Shift_Right (Sloc (N),
2591 Left_Opnd => N,
2592 Right_Opnd => S);
2593 Set_Shift_Count_OK (Nod, True);
2594 return Nod;
2595 end if;
2596 end Make_Shift_Right;
2597
2598 -----------------------------
2599 -- RJ_Unchecked_Convert_To --
2600 -----------------------------
2601
2602 function RJ_Unchecked_Convert_To
2603 (Typ : Entity_Id;
2604 Expr : Node_Id) return Node_Id
2605 is
2606 Source_Typ : constant Entity_Id := Etype (Expr);
2607 Target_Typ : constant Entity_Id := Typ;
2608
2609 Src : Node_Id := Expr;
2610
2611 Source_Siz : Nat;
2612 Target_Siz : Nat;
2613
2614 begin
2615 Source_Siz := UI_To_Int (RM_Size (Source_Typ));
2616 Target_Siz := UI_To_Int (RM_Size (Target_Typ));
2617
2618 -- For a little-endian target type stored byte-swapped on a
2619 -- big-endian machine, do not mask to Target_Siz bits.
2620
2621 if Bytes_Big_Endian
2622 and then (Is_Record_Type (Target_Typ)
2623 or else
2624 Is_Array_Type (Target_Typ))
2625 and then Reverse_Storage_Order (Target_Typ)
2626 then
2627 Source_Siz := Target_Siz;
2628 end if;
2629
2630 -- First step, if the source type is not a discrete type, then we first
2631 -- convert to a modular type of the source length, since otherwise, on
2632 -- a big-endian machine, we get left-justification. We do it for little-
2633 -- endian machines as well, because there might be junk bits that are
2634 -- not cleared if the type is not numeric.
2635
2636 if Source_Siz /= Target_Siz
2637 and then not Is_Discrete_Type (Source_Typ)
2638 then
2639 Src := Unchecked_Convert_To (RTE (Bits_Id (Source_Siz)), Src);
2640 end if;
2641
2642 -- In the big endian case, if the lengths of the two types differ, then
2643 -- we must worry about possible left justification in the conversion,
2644 -- and avoiding that is what this is all about.
2645
2646 if Bytes_Big_Endian and then Source_Siz /= Target_Siz then
2647
2648 -- Next step. If the target is not a discrete type, then we first
2649 -- convert to a modular type of the target length, since otherwise,
2650 -- on a big-endian machine, we get left-justification.
2651
2652 if not Is_Discrete_Type (Target_Typ) then
2653 Src := Unchecked_Convert_To (RTE (Bits_Id (Target_Siz)), Src);
2654 end if;
2655 end if;
2656
2657 -- And now we can do the final conversion to the target type
2658
2659 return Unchecked_Convert_To (Target_Typ, Src);
2660 end RJ_Unchecked_Convert_To;
2661
2662 ----------------------------------------------
2663 -- Setup_Enumeration_Packed_Array_Reference --
2664 ----------------------------------------------
2665
2666 -- All we have to do here is to find the subscripts that correspond to the
2667 -- index positions that have non-standard enumeration types and insert a
2668 -- Pos attribute to get the proper subscript value.
2669
2670 -- Finally the prefix must be uncheck-converted to the corresponding packed
2671 -- array type.
2672
2673 -- Note that the component type is unchanged, so we do not need to fiddle
2674 -- with the types (Gigi always automatically takes the packed array type if
2675 -- it is set, as it will be in this case).
2676
2677 procedure Setup_Enumeration_Packed_Array_Reference (N : Node_Id) is
2678 Pfx : constant Node_Id := Prefix (N);
2679 Typ : constant Entity_Id := Etype (N);
2680 Exprs : constant List_Id := Expressions (N);
2681 Expr : Node_Id;
2682
2683 begin
2684 -- If the array is unconstrained, then we replace the array reference
2685 -- with its actual subtype. This actual subtype will have a packed array
2686 -- type with appropriate bounds.
2687
2688 if not Is_Constrained (Packed_Array_Type (Etype (Pfx))) then
2689 Convert_To_Actual_Subtype (Pfx);
2690 end if;
2691
2692 Expr := First (Exprs);
2693 while Present (Expr) loop
2694 declare
2695 Loc : constant Source_Ptr := Sloc (Expr);
2696 Expr_Typ : constant Entity_Id := Etype (Expr);
2697
2698 begin
2699 if Is_Enumeration_Type (Expr_Typ)
2700 and then Has_Non_Standard_Rep (Expr_Typ)
2701 then
2702 Rewrite (Expr,
2703 Make_Attribute_Reference (Loc,
2704 Prefix => New_Occurrence_Of (Expr_Typ, Loc),
2705 Attribute_Name => Name_Pos,
2706 Expressions => New_List (Relocate_Node (Expr))));
2707 Analyze_And_Resolve (Expr, Standard_Natural);
2708 end if;
2709 end;
2710
2711 Next (Expr);
2712 end loop;
2713
2714 Rewrite (N,
2715 Make_Indexed_Component (Sloc (N),
2716 Prefix =>
2717 Unchecked_Convert_To (Packed_Array_Type (Etype (Pfx)), Pfx),
2718 Expressions => Exprs));
2719
2720 Analyze_And_Resolve (N, Typ);
2721 end Setup_Enumeration_Packed_Array_Reference;
2722
2723 -----------------------------------------
2724 -- Setup_Inline_Packed_Array_Reference --
2725 -----------------------------------------
2726
2727 procedure Setup_Inline_Packed_Array_Reference
2728 (N : Node_Id;
2729 Atyp : Entity_Id;
2730 Obj : in out Node_Id;
2731 Cmask : out Uint;
2732 Shift : out Node_Id)
2733 is
2734 Loc : constant Source_Ptr := Sloc (N);
2735 PAT : Entity_Id;
2736 Otyp : Entity_Id;
2737 Csiz : Uint;
2738 Osiz : Uint;
2739
2740 begin
2741 Csiz := Component_Size (Atyp);
2742
2743 Convert_To_PAT_Type (Obj);
2744 PAT := Etype (Obj);
2745
2746 Cmask := 2 ** Csiz - 1;
2747
2748 if Is_Array_Type (PAT) then
2749 Otyp := Component_Type (PAT);
2750 Osiz := Component_Size (PAT);
2751
2752 else
2753 Otyp := PAT;
2754
2755 -- In the case where the PAT is a modular type, we want the actual
2756 -- size in bits of the modular value we use. This is neither the
2757 -- Object_Size nor the Value_Size, either of which may have been
2758 -- reset to strange values, but rather the minimum size. Note that
2759 -- since this is a modular type with full range, the issue of
2760 -- biased representation does not arise.
2761
2762 Osiz := UI_From_Int (Minimum_Size (Otyp));
2763 end if;
2764
2765 Compute_Linear_Subscript (Atyp, N, Shift);
2766
2767 -- If the component size is not 1, then the subscript must be multiplied
2768 -- by the component size to get the shift count.
2769
2770 if Csiz /= 1 then
2771 Shift :=
2772 Make_Op_Multiply (Loc,
2773 Left_Opnd => Make_Integer_Literal (Loc, Csiz),
2774 Right_Opnd => Shift);
2775 end if;
2776
2777 -- If we have the array case, then this shift count must be broken down
2778 -- into a byte subscript, and a shift within the byte.
2779
2780 if Is_Array_Type (PAT) then
2781
2782 declare
2783 New_Shift : Node_Id;
2784
2785 begin
2786 -- We must analyze shift, since we will duplicate it
2787
2788 Set_Parent (Shift, N);
2789 Analyze_And_Resolve
2790 (Shift, Standard_Integer, Suppress => All_Checks);
2791
2792 -- The shift count within the word is
2793 -- shift mod Osiz
2794
2795 New_Shift :=
2796 Make_Op_Mod (Loc,
2797 Left_Opnd => Duplicate_Subexpr (Shift),
2798 Right_Opnd => Make_Integer_Literal (Loc, Osiz));
2799
2800 -- The subscript to be used on the PAT array is
2801 -- shift / Osiz
2802
2803 Obj :=
2804 Make_Indexed_Component (Loc,
2805 Prefix => Obj,
2806 Expressions => New_List (
2807 Make_Op_Divide (Loc,
2808 Left_Opnd => Duplicate_Subexpr (Shift),
2809 Right_Opnd => Make_Integer_Literal (Loc, Osiz))));
2810
2811 Shift := New_Shift;
2812 end;
2813
2814 -- For the modular integer case, the object to be manipulated is the
2815 -- entire array, so Obj is unchanged. Note that we will reset its type
2816 -- to PAT before returning to the caller.
2817
2818 else
2819 null;
2820 end if;
2821
2822 -- The one remaining step is to modify the shift count for the
2823 -- big-endian case. Consider the following example in a byte:
2824
2825 -- xxxxxxxx bits of byte
2826 -- vvvvvvvv bits of value
2827 -- 33221100 little-endian numbering
2828 -- 00112233 big-endian numbering
2829
2830 -- Here we have the case of 2-bit fields
2831
2832 -- For the little-endian case, we already have the proper shift count
2833 -- set, e.g. for element 2, the shift count is 2*2 = 4.
2834
2835 -- For the big endian case, we have to adjust the shift count, computing
2836 -- it as (N - F) - Shift, where N is the number of bits in an element of
2837 -- the array used to implement the packed array, F is the number of bits
2838 -- in a source array element, and Shift is the count so far computed.
2839
2840 -- We also have to adjust if the storage order is reversed
2841
2842 if Bytes_Big_Endian xor Reverse_Storage_Order (Base_Type (Atyp)) then
2843 Shift :=
2844 Make_Op_Subtract (Loc,
2845 Left_Opnd => Make_Integer_Literal (Loc, Osiz - Csiz),
2846 Right_Opnd => Shift);
2847 end if;
2848
2849 Set_Parent (Shift, N);
2850 Set_Parent (Obj, N);
2851 Analyze_And_Resolve (Obj, Otyp, Suppress => All_Checks);
2852 Analyze_And_Resolve (Shift, Standard_Integer, Suppress => All_Checks);
2853
2854 -- Make sure final type of object is the appropriate packed type
2855
2856 Set_Etype (Obj, Otyp);
2857
2858 end Setup_Inline_Packed_Array_Reference;
2859
2860 end Exp_Pakd;
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