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) 1992-2012, 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 26with Atree; use Atree; 27with Checks; use Checks; 28with Einfo; use Einfo; 29with Errout; use Errout; 30with Exp_Dbug; use Exp_Dbug; 31with Exp_Util; use Exp_Util; 32with Layout; use Layout; 33with Namet; use Namet; 34with Nlists; use Nlists; 35with Nmake; use Nmake; 36with Opt; use Opt; 37with Rtsfind; use Rtsfind; 38with Sem; use Sem; 39with Sem_Aux; use Sem_Aux; 40with Sem_Ch3; use Sem_Ch3; 41with Sem_Ch8; use Sem_Ch8; 42with Sem_Ch13; use Sem_Ch13; 43with Sem_Eval; use Sem_Eval; 44with Sem_Res; use Sem_Res; 45with Sem_Util; use Sem_Util; 46with Sinfo; use Sinfo; 47with Snames; use Snames; 48with Stand; use Stand; 49with Targparm; use Targparm; 50with Tbuild; use Tbuild; 51with Ttypes; use Ttypes; 52with Uintp; use Uintp; 53 54package 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 endian dependent, and the effect we 488 -- want here for such a conversion is to do the conversion in size as 489 -- though numeric items are involved, and we extend or truncate on the 490 -- left side. This happens naturally in the little-endian case, but in 491 -- the big endian case we can get left justification, when what we want 492 -- is right justification. This routine does the unchecked conversion in 493 -- a stepwise manner to ensure that it gives the expected result. Hence 494 -- the name (RJ = Right justified). The parameters Typ and Expr are as 495 -- for the case of a normal Unchecked_Convert_To call. 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 Byte_Swap (N : Node_Id) return Node_Id; 547 -- Wrap N in a call to a byte swapping function, with appropriate type 548 -- conversions. 549 550 --------------- 551 -- Byte_Swap -- 552 --------------- 553 554 function Byte_Swap (N : Node_Id) return Node_Id is 555 Loc : constant Source_Ptr := Sloc (N); 556 T : constant Entity_Id := Etype (N); 557 Swap_RE : RE_Id; 558 Swap_F : Entity_Id; 559 560 begin 561 pragma Assert (Esize (T) > 8); 562 563 if Esize (T) <= 16 then 564 Swap_RE := RE_Bswap_16; 565 elsif Esize (T) <= 32 then 566 Swap_RE := RE_Bswap_32; 567 else pragma Assert (Esize (T) <= 64); 568 Swap_RE := RE_Bswap_64; 569 end if; 570 571 Swap_F := RTE (Swap_RE); 572 573 return 574 Unchecked_Convert_To (T, 575 Make_Function_Call (Loc, 576 Name => New_Occurrence_Of (Swap_F, Loc), 577 Parameter_Associations => 578 New_List (Unchecked_Convert_To (Etype (Swap_F), N)))); 579 end Byte_Swap; 580 581 ------------------------------ 582 -- Compute_Linear_Subscript -- 583 ------------------------------ 584 585 procedure Compute_Linear_Subscript 586 (Atyp : Entity_Id; 587 N : Node_Id; 588 Subscr : out Node_Id) 589 is 590 Loc : constant Source_Ptr := Sloc (N); 591 Oldsub : Node_Id; 592 Newsub : Node_Id; 593 Indx : Node_Id; 594 Styp : Entity_Id; 595 596 begin 597 Subscr := Empty; 598 599 -- Loop through dimensions 600 601 Indx := First_Index (Atyp); 602 Oldsub := First (Expressions (N)); 603 604 while Present (Indx) loop 605 Styp := Etype (Indx); 606 Newsub := Relocate_Node (Oldsub); 607 608 -- Get expression for the subscript value. First, if Do_Range_Check 609 -- is set on a subscript, then we must do a range check against the 610 -- original bounds (not the bounds of the packed array type). We do 611 -- this by introducing a subtype conversion. 612 613 if Do_Range_Check (Newsub) 614 and then Etype (Newsub) /= Styp 615 then 616 Newsub := Convert_To (Styp, Newsub); 617 end if; 618 619 -- Now evolve the expression for the subscript. First convert 620 -- the subscript to be zero based and of an integer type. 621 622 -- Case of integer type, where we just subtract to get lower bound 623 624 if Is_Integer_Type (Styp) then 625 626 -- If length of integer type is smaller than standard integer, 627 -- then we convert to integer first, then do the subtract 628 629 -- Integer (subscript) - Integer (Styp'First) 630 631 if Esize (Styp) < Esize (Standard_Integer) then 632 Newsub := 633 Make_Op_Subtract (Loc, 634 Left_Opnd => Convert_To (Standard_Integer, Newsub), 635 Right_Opnd => 636 Convert_To (Standard_Integer, 637 Make_Attribute_Reference (Loc, 638 Prefix => New_Occurrence_Of (Styp, Loc), 639 Attribute_Name => Name_First))); 640 641 -- For larger integer types, subtract first, then convert to 642 -- integer, this deals with strange long long integer bounds. 643 644 -- Integer (subscript - Styp'First) 645 646 else 647 Newsub := 648 Convert_To (Standard_Integer, 649 Make_Op_Subtract (Loc, 650 Left_Opnd => Newsub, 651 Right_Opnd => 652 Make_Attribute_Reference (Loc, 653 Prefix => New_Occurrence_Of (Styp, Loc), 654 Attribute_Name => Name_First))); 655 end if; 656 657 -- For the enumeration case, we have to use 'Pos to get the value 658 -- to work with before subtracting the lower bound. 659 660 -- Integer (Styp'Pos (subscr)) - Integer (Styp'Pos (Styp'First)); 661 662 -- This is not quite right for bizarre cases where the size of the 663 -- enumeration type is > Integer'Size bits due to rep clause ??? 664 665 else 666 pragma Assert (Is_Enumeration_Type (Styp)); 667 668 Newsub := 669 Make_Op_Subtract (Loc, 670 Left_Opnd => Convert_To (Standard_Integer, 671 Make_Attribute_Reference (Loc, 672 Prefix => New_Occurrence_Of (Styp, Loc), 673 Attribute_Name => Name_Pos, 674 Expressions => New_List (Newsub))), 675 676 Right_Opnd => 677 Convert_To (Standard_Integer, 678 Make_Attribute_Reference (Loc, 679 Prefix => New_Occurrence_Of (Styp, Loc), 680 Attribute_Name => Name_Pos, 681 Expressions => New_List ( 682 Make_Attribute_Reference (Loc, 683 Prefix => New_Occurrence_Of (Styp, Loc), 684 Attribute_Name => Name_First))))); 685 end if; 686 687 Set_Paren_Count (Newsub, 1); 688 689 -- For the first subscript, we just copy that subscript value 690 691 if No (Subscr) then 692 Subscr := Newsub; 693 694 -- Otherwise, we must multiply what we already have by the current 695 -- stride and then add in the new value to the evolving subscript. 696 697 else 698 Subscr := 699 Make_Op_Add (Loc, 700 Left_Opnd => 701 Make_Op_Multiply (Loc, 702 Left_Opnd => Subscr, 703 Right_Opnd => 704 Make_Attribute_Reference (Loc, 705 Attribute_Name => Name_Range_Length, 706 Prefix => New_Occurrence_Of (Styp, Loc))), 707 Right_Opnd => Newsub); 708 end if; 709 710 -- Move to next subscript 711 712 Next_Index (Indx); 713 Next (Oldsub); 714 end loop; 715 end Compute_Linear_Subscript; 716 717 ------------------------- 718 -- Convert_To_PAT_Type -- 719 ------------------------- 720 721 -- The PAT is always obtained from the actual subtype 722 723 procedure Convert_To_PAT_Type (Aexp : Node_Id) is 724 Act_ST : Entity_Id; 725 726 begin 727 Convert_To_Actual_Subtype (Aexp); 728 Act_ST := Underlying_Type (Etype (Aexp)); 729 Create_Packed_Array_Type (Act_ST); 730 731 -- Just replace the etype with the packed array type. This works because 732 -- the expression will not be further analyzed, and Gigi considers the 733 -- two types equivalent in any case. 734 735 -- This is not strictly the case ??? If the reference is an actual in 736 -- call, the expansion of the prefix is delayed, and must be reanalyzed, 737 -- see Reset_Packed_Prefix. On the other hand, if the prefix is a simple 738 -- array reference, reanalysis can produce spurious type errors when the 739 -- PAT type is replaced again with the original type of the array. Same 740 -- for the case of a dereference. Ditto for function calls: expansion 741 -- may introduce additional actuals which will trigger errors if call is 742 -- reanalyzed. The following is correct and minimal, but the handling of 743 -- more complex packed expressions in actuals is confused. Probably the 744 -- problem only remains for actuals in calls. 745 746 Set_Etype (Aexp, Packed_Array_Type (Act_ST)); 747 748 if Is_Entity_Name (Aexp) 749 or else 750 (Nkind (Aexp) = N_Indexed_Component 751 and then Is_Entity_Name (Prefix (Aexp))) 752 or else Nkind_In (Aexp, N_Explicit_Dereference, N_Function_Call) 753 then 754 Set_Analyzed (Aexp); 755 end if; 756 end Convert_To_PAT_Type; 757 758 ------------------------------ 759 -- Create_Packed_Array_Type -- 760 ------------------------------ 761 762 procedure Create_Packed_Array_Type (Typ : Entity_Id) is 763 Loc : constant Source_Ptr := Sloc (Typ); 764 Ctyp : constant Entity_Id := Component_Type (Typ); 765 Csize : constant Uint := Component_Size (Typ); 766 767 Ancest : Entity_Id; 768 PB_Type : Entity_Id; 769 PASize : Uint; 770 Decl : Node_Id; 771 PAT : Entity_Id; 772 Len_Dim : Node_Id; 773 Len_Expr : Node_Id; 774 Len_Bits : Uint; 775 Bits_U1 : Node_Id; 776 PAT_High : Node_Id; 777 Btyp : Entity_Id; 778 Lit : Node_Id; 779 780 procedure Install_PAT; 781 -- This procedure is called with Decl set to the declaration for the 782 -- packed array type. It creates the type and installs it as required. 783 784 procedure Set_PB_Type; 785 -- Sets PB_Type to Packed_Bytes{1,2,4} as required by the alignment 786 -- requirements (see documentation in the spec of this package). 787 788 ----------------- 789 -- Install_PAT -- 790 ----------------- 791 792 procedure Install_PAT is 793 Pushed_Scope : Boolean := False; 794 795 begin 796 -- We do not want to put the declaration we have created in the tree 797 -- since it is often hard, and sometimes impossible to find a proper 798 -- place for it (the impossible case arises for a packed array type 799 -- with bounds depending on the discriminant, a declaration cannot 800 -- be put inside the record, and the reference to the discriminant 801 -- cannot be outside the record). 802 803 -- The solution is to analyze the declaration while temporarily 804 -- attached to the tree at an appropriate point, and then we install 805 -- the resulting type as an Itype in the packed array type field of 806 -- the original type, so that no explicit declaration is required. 807 808 -- Note: the packed type is created in the scope of its parent 809 -- type. There are at least some cases where the current scope 810 -- is deeper, and so when this is the case, we temporarily reset 811 -- the scope for the definition. This is clearly safe, since the 812 -- first use of the packed array type will be the implicit 813 -- reference from the corresponding unpacked type when it is 814 -- elaborated. 815 816 if Is_Itype (Typ) then 817 Set_Parent (Decl, Associated_Node_For_Itype (Typ)); 818 else 819 Set_Parent (Decl, Declaration_Node (Typ)); 820 end if; 821 822 if Scope (Typ) /= Current_Scope then 823 Push_Scope (Scope (Typ)); 824 Pushed_Scope := True; 825 end if; 826 827 Set_Is_Itype (PAT, True); 828 Set_Packed_Array_Type (Typ, PAT); 829 Analyze (Decl, Suppress => All_Checks); 830 831 if Pushed_Scope then 832 Pop_Scope; 833 end if; 834 835 -- Set Esize and RM_Size to the actual size of the packed object 836 -- Do not reset RM_Size if already set, as happens in the case of 837 -- a modular type. 838 839 if Unknown_Esize (PAT) then 840 Set_Esize (PAT, PASize); 841 end if; 842 843 if Unknown_RM_Size (PAT) then 844 Set_RM_Size (PAT, PASize); 845 end if; 846 847 Adjust_Esize_Alignment (PAT); 848 849 -- Set remaining fields of packed array type 850 851 Init_Alignment (PAT); 852 Set_Parent (PAT, Empty); 853 Set_Associated_Node_For_Itype (PAT, Typ); 854 Set_Is_Packed_Array_Type (PAT, True); 855 Set_Original_Array_Type (PAT, Typ); 856 857 -- We definitely do not want to delay freezing for packed array 858 -- types. This is of particular importance for the itypes that 859 -- are generated for record components depending on discriminants 860 -- where there is no place to put the freeze node. 861 862 Set_Has_Delayed_Freeze (PAT, False); 863 Set_Has_Delayed_Freeze (Etype (PAT), False); 864 865 -- If we did allocate a freeze node, then clear out the reference 866 -- since it is obsolete (should we delete the freeze node???) 867 868 Set_Freeze_Node (PAT, Empty); 869 Set_Freeze_Node (Etype (PAT), Empty); 870 end Install_PAT; 871 872 ----------------- 873 -- Set_PB_Type -- 874 ----------------- 875 876 procedure Set_PB_Type is 877 begin 878 -- If the user has specified an explicit alignment for the 879 -- type or component, take it into account. 880 881 if Csize <= 2 or else Csize = 4 or else Csize mod 2 /= 0 882 or else Alignment (Typ) = 1 883 or else Component_Alignment (Typ) = Calign_Storage_Unit 884 then 885 PB_Type := RTE (RE_Packed_Bytes1); 886 887 elsif Csize mod 4 /= 0 888 or else Alignment (Typ) = 2 889 then 890 PB_Type := RTE (RE_Packed_Bytes2); 891 892 else 893 PB_Type := RTE (RE_Packed_Bytes4); 894 end if; 895 end Set_PB_Type; 896 897 -- Start of processing for Create_Packed_Array_Type 898 899 begin 900 -- If we already have a packed array type, nothing to do 901 902 if Present (Packed_Array_Type (Typ)) then 903 return; 904 end if; 905 906 -- If our immediate ancestor subtype is constrained, and it already 907 -- has a packed array type, then just share the same type, since the 908 -- bounds must be the same. If the ancestor is not an array type but 909 -- a private type, as can happen with multiple instantiations, create 910 -- a new packed type, to avoid privacy issues. 911 912 if Ekind (Typ) = E_Array_Subtype then 913 Ancest := Ancestor_Subtype (Typ); 914 915 if Present (Ancest) 916 and then Is_Array_Type (Ancest) 917 and then Is_Constrained (Ancest) 918 and then Present (Packed_Array_Type (Ancest)) 919 then 920 Set_Packed_Array_Type (Typ, Packed_Array_Type (Ancest)); 921 return; 922 end if; 923 end if; 924 925 -- We preset the result type size from the size of the original array 926 -- type, since this size clearly belongs to the packed array type. The 927 -- size of the conceptual unpacked type is always set to unknown. 928 929 PASize := RM_Size (Typ); 930 931 -- Case of an array where at least one index is of an enumeration 932 -- type with a non-standard representation, but the component size 933 -- is not appropriate for bit packing. This is the case where we 934 -- have Is_Packed set (we would never be in this unit otherwise), 935 -- but Is_Bit_Packed_Array is false. 936 937 -- Note that if the component size is appropriate for bit packing, 938 -- then the circuit for the computation of the subscript properly 939 -- deals with the non-standard enumeration type case by taking the 940 -- Pos anyway. 941 942 if not Is_Bit_Packed_Array (Typ) then 943 944 -- Here we build a declaration: 945 946 -- type tttP is array (index1, index2, ...) of component_type 947 948 -- where index1, index2, are the index types. These are the same 949 -- as the index types of the original array, except for the non- 950 -- standard representation enumeration type case, where we have 951 -- two subcases. 952 953 -- For the unconstrained array case, we use 954 955 -- Natural range <> 956 957 -- For the constrained case, we use 958 959 -- Natural range Enum_Type'Pos (Enum_Type'First) .. 960 -- Enum_Type'Pos (Enum_Type'Last); 961 962 PAT := 963 Make_Defining_Identifier (Loc, 964 Chars => New_External_Name (Chars (Typ), 'P')); 965 966 Set_Packed_Array_Type (Typ, PAT); 967 968 declare 969 Indexes : constant List_Id := New_List; 970 Indx : Node_Id; 971 Indx_Typ : Entity_Id; 972 Enum_Case : Boolean; 973 Typedef : Node_Id; 974 975 begin 976 Indx := First_Index (Typ); 977 978 while Present (Indx) loop 979 Indx_Typ := Etype (Indx); 980 981 Enum_Case := Is_Enumeration_Type (Indx_Typ) 982 and then Has_Non_Standard_Rep (Indx_Typ); 983 984 -- Unconstrained case 985 986 if not Is_Constrained (Typ) then 987 if Enum_Case then 988 Indx_Typ := Standard_Natural; 989 end if; 990 991 Append_To (Indexes, New_Occurrence_Of (Indx_Typ, Loc)); 992 993 -- Constrained case 994 995 else 996 if not Enum_Case then 997 Append_To (Indexes, New_Occurrence_Of (Indx_Typ, Loc)); 998 999 else 1000 Append_To (Indexes, 1001 Make_Subtype_Indication (Loc, 1002 Subtype_Mark => 1003 New_Occurrence_Of (Standard_Natural, Loc), 1004 Constraint => 1005 Make_Range_Constraint (Loc, 1006 Range_Expression => 1007 Make_Range (Loc, 1008 Low_Bound => 1009 Make_Attribute_Reference (Loc, 1010 Prefix => 1011 New_Occurrence_Of (Indx_Typ, Loc), 1012 Attribute_Name => Name_Pos, 1013 Expressions => New_List ( 1014 Make_Attribute_Reference (Loc, 1015 Prefix => 1016 New_Occurrence_Of (Indx_Typ, Loc), 1017 Attribute_Name => Name_First))), 1018 1019 High_Bound => 1020 Make_Attribute_Reference (Loc, 1021 Prefix => 1022 New_Occurrence_Of (Indx_Typ, Loc), 1023 Attribute_Name => Name_Pos, 1024 Expressions => New_List ( 1025 Make_Attribute_Reference (Loc, 1026 Prefix => 1027 New_Occurrence_Of (Indx_Typ, Loc), 1028 Attribute_Name => Name_Last))))))); 1029 1030 end if; 1031 end if; 1032 1033 Next_Index (Indx); 1034 end loop; 1035 1036 if not Is_Constrained (Typ) then 1037 Typedef := 1038 Make_Unconstrained_Array_Definition (Loc, 1039 Subtype_Marks => Indexes, 1040 Component_Definition => 1041 Make_Component_Definition (Loc, 1042 Aliased_Present => False, 1043 Subtype_Indication => 1044 New_Occurrence_Of (Ctyp, Loc))); 1045 1046 else 1047 Typedef := 1048 Make_Constrained_Array_Definition (Loc, 1049 Discrete_Subtype_Definitions => Indexes, 1050 Component_Definition => 1051 Make_Component_Definition (Loc, 1052 Aliased_Present => False, 1053 Subtype_Indication => 1054 New_Occurrence_Of (Ctyp, Loc))); 1055 end if; 1056 1057 Decl := 1058 Make_Full_Type_Declaration (Loc, 1059 Defining_Identifier => PAT, 1060 Type_Definition => Typedef); 1061 end; 1062 1063 -- Set type as packed array type and install it 1064 1065 Set_Is_Packed_Array_Type (PAT); 1066 Install_PAT; 1067 return; 1068 1069 -- Case of bit-packing required for unconstrained array. We create 1070 -- a subtype that is equivalent to use Packed_Bytes{1,2,4} as needed. 1071 1072 elsif not Is_Constrained (Typ) then 1073 PAT := 1074 Make_Defining_Identifier (Loc, 1075 Chars => Make_Packed_Array_Type_Name (Typ, Csize)); 1076 1077 Set_Packed_Array_Type (Typ, PAT); 1078 Set_PB_Type; 1079 1080 Decl := 1081 Make_Subtype_Declaration (Loc, 1082 Defining_Identifier => PAT, 1083 Subtype_Indication => New_Occurrence_Of (PB_Type, Loc)); 1084 Install_PAT; 1085 return; 1086 1087 -- Remaining code is for the case of bit-packing for constrained array 1088 1089 -- The name of the packed array subtype is 1090 1091 -- ttt___Xsss 1092 1093 -- where sss is the component size in bits and ttt is the name of 1094 -- the parent packed type. 1095 1096 else 1097 PAT := 1098 Make_Defining_Identifier (Loc, 1099 Chars => Make_Packed_Array_Type_Name (Typ, Csize)); 1100 1101 Set_Packed_Array_Type (Typ, PAT); 1102 1103 -- Build an expression for the length of the array in bits. 1104 -- This is the product of the length of each of the dimensions 1105 1106 declare 1107 J : Nat := 1; 1108 1109 begin 1110 Len_Expr := Empty; -- suppress junk warning 1111 1112 loop 1113 Len_Dim := 1114 Make_Attribute_Reference (Loc, 1115 Attribute_Name => Name_Length, 1116 Prefix => New_Occurrence_Of (Typ, Loc), 1117 Expressions => New_List ( 1118 Make_Integer_Literal (Loc, J))); 1119 1120 if J = 1 then 1121 Len_Expr := Len_Dim; 1122 1123 else 1124 Len_Expr := 1125 Make_Op_Multiply (Loc, 1126 Left_Opnd => Len_Expr, 1127 Right_Opnd => Len_Dim); 1128 end if; 1129 1130 J := J + 1; 1131 exit when J > Number_Dimensions (Typ); 1132 end loop; 1133 end; 1134 1135 -- Temporarily attach the length expression to the tree and analyze 1136 -- and resolve it, so that we can test its value. We assume that the 1137 -- total length fits in type Integer. This expression may involve 1138 -- discriminants, so we treat it as a default/per-object expression. 1139 1140 Set_Parent (Len_Expr, Typ); 1141 Preanalyze_Spec_Expression (Len_Expr, Standard_Long_Long_Integer); 1142 1143 -- Use a modular type if possible. We can do this if we have 1144 -- static bounds, and the length is small enough, and the length 1145 -- is not zero. We exclude the zero length case because the size 1146 -- of things is always at least one, and the zero length object 1147 -- would have an anomalous size. 1148 1149 if Compile_Time_Known_Value (Len_Expr) then 1150 Len_Bits := Expr_Value (Len_Expr) * Csize; 1151 1152 -- Check for size known to be too large 1153 1154 if Len_Bits > 1155 Uint_2 ** (Standard_Integer_Size - 1) * System_Storage_Unit 1156 then 1157 if System_Storage_Unit = 8 then 1158 Error_Msg_N 1159 ("packed array size cannot exceed " & 1160 "Integer''Last bytes", Typ); 1161 else 1162 Error_Msg_N 1163 ("packed array size cannot exceed " & 1164 "Integer''Last storage units", Typ); 1165 end if; 1166 1167 -- Reset length to arbitrary not too high value to continue 1168 1169 Len_Expr := Make_Integer_Literal (Loc, 65535); 1170 Analyze_And_Resolve (Len_Expr, Standard_Long_Long_Integer); 1171 end if; 1172 1173 -- We normally consider small enough to mean no larger than the 1174 -- value of System_Max_Binary_Modulus_Power, checking that in the 1175 -- case of values longer than word size, we have long shifts. 1176 1177 if Len_Bits > 0 1178 and then 1179 (Len_Bits <= System_Word_Size 1180 or else (Len_Bits <= System_Max_Binary_Modulus_Power 1181 and then Support_Long_Shifts_On_Target)) 1182 then 1183 -- We can use the modular type, it has the form: 1184 1185 -- subtype tttPn is btyp 1186 -- range 0 .. 2 ** ((Typ'Length (1) 1187 -- * ... * Typ'Length (n)) * Csize) - 1; 1188 1189 -- The bounds are statically known, and btyp is one of the 1190 -- unsigned types, depending on the length. 1191 1192 if Len_Bits <= Standard_Short_Short_Integer_Size then 1193 Btyp := RTE (RE_Short_Short_Unsigned); 1194 1195 elsif Len_Bits <= Standard_Short_Integer_Size then 1196 Btyp := RTE (RE_Short_Unsigned); 1197 1198 elsif Len_Bits <= Standard_Integer_Size then 1199 Btyp := RTE (RE_Unsigned); 1200 1201 elsif Len_Bits <= Standard_Long_Integer_Size then 1202 Btyp := RTE (RE_Long_Unsigned); 1203 1204 else 1205 Btyp := RTE (RE_Long_Long_Unsigned); 1206 end if; 1207 1208 Lit := Make_Integer_Literal (Loc, 2 ** Len_Bits - 1); 1209 Set_Print_In_Hex (Lit); 1210 1211 Decl := 1212 Make_Subtype_Declaration (Loc, 1213 Defining_Identifier => PAT, 1214 Subtype_Indication => 1215 Make_Subtype_Indication (Loc, 1216 Subtype_Mark => New_Occurrence_Of (Btyp, Loc), 1217 1218 Constraint => 1219 Make_Range_Constraint (Loc, 1220 Range_Expression => 1221 Make_Range (Loc, 1222 Low_Bound => 1223 Make_Integer_Literal (Loc, 0), 1224 High_Bound => Lit)))); 1225 1226 if PASize = Uint_0 then 1227 PASize := Len_Bits; 1228 end if; 1229 1230 Install_PAT; 1231 1232 -- Propagate a given alignment to the modular type. This can 1233 -- cause it to be under-aligned, but that's OK. 1234 1235 if Present (Alignment_Clause (Typ)) then 1236 Set_Alignment (PAT, Alignment (Typ)); 1237 end if; 1238 1239 return; 1240 end if; 1241 end if; 1242 1243 -- Could not use a modular type, for all other cases, we build 1244 -- a packed array subtype: 1245 1246 -- subtype tttPn is 1247 -- System.Packed_Bytes{1,2,4} (0 .. (Bits + 7) / 8 - 1); 1248 1249 -- Bits is the length of the array in bits 1250 1251 Set_PB_Type; 1252 1253 Bits_U1 := 1254 Make_Op_Add (Loc, 1255 Left_Opnd => 1256 Make_Op_Multiply (Loc, 1257 Left_Opnd => 1258 Make_Integer_Literal (Loc, Csize), 1259 Right_Opnd => Len_Expr), 1260 1261 Right_Opnd => 1262 Make_Integer_Literal (Loc, 7)); 1263 1264 Set_Paren_Count (Bits_U1, 1); 1265 1266 PAT_High := 1267 Make_Op_Subtract (Loc, 1268 Left_Opnd => 1269 Make_Op_Divide (Loc, 1270 Left_Opnd => Bits_U1, 1271 Right_Opnd => Make_Integer_Literal (Loc, 8)), 1272 Right_Opnd => Make_Integer_Literal (Loc, 1)); 1273 1274 Decl := 1275 Make_Subtype_Declaration (Loc, 1276 Defining_Identifier => PAT, 1277 Subtype_Indication => 1278 Make_Subtype_Indication (Loc, 1279 Subtype_Mark => New_Occurrence_Of (PB_Type, Loc), 1280 Constraint => 1281 Make_Index_Or_Discriminant_Constraint (Loc, 1282 Constraints => New_List ( 1283 Make_Range (Loc, 1284 Low_Bound => 1285 Make_Integer_Literal (Loc, 0), 1286 High_Bound => 1287 Convert_To (Standard_Integer, PAT_High)))))); 1288 1289 Install_PAT; 1290 1291 -- Currently the code in this unit requires that packed arrays 1292 -- represented by non-modular arrays of bytes be on a byte 1293 -- boundary for bit sizes handled by System.Pack_nn units. 1294 -- That's because these units assume the array being accessed 1295 -- starts on a byte boundary. 1296 1297 if Get_Id (UI_To_Int (Csize)) /= RE_Null then 1298 Set_Must_Be_On_Byte_Boundary (Typ); 1299 end if; 1300 end if; 1301 end Create_Packed_Array_Type; 1302 1303 ----------------------------------- 1304 -- Expand_Bit_Packed_Element_Set -- 1305 ----------------------------------- 1306 1307 procedure Expand_Bit_Packed_Element_Set (N : Node_Id) is 1308 Loc : constant Source_Ptr := Sloc (N); 1309 Lhs : constant Node_Id := Name (N); 1310 1311 Ass_OK : constant Boolean := Assignment_OK (Lhs); 1312 -- Used to preserve assignment OK status when assignment is rewritten 1313 1314 Rhs : Node_Id := Expression (N); 1315 -- Initially Rhs is the right hand side value, it will be replaced 1316 -- later by an appropriate unchecked conversion for the assignment. 1317 1318 Obj : Node_Id; 1319 Atyp : Entity_Id; 1320 PAT : Entity_Id; 1321 Ctyp : Entity_Id; 1322 Csiz : Int; 1323 Cmask : Uint; 1324 1325 Shift : Node_Id; 1326 -- The expression for the shift value that is required 1327 1328 Shift_Used : Boolean := False; 1329 -- Set True if Shift has been used in the generated code at least 1330 -- once, so that it must be duplicated if used again 1331 1332 New_Lhs : Node_Id; 1333 New_Rhs : Node_Id; 1334 1335 Rhs_Val_Known : Boolean; 1336 Rhs_Val : Uint; 1337 -- If the value of the right hand side as an integer constant is 1338 -- known at compile time, Rhs_Val_Known is set True, and Rhs_Val 1339 -- contains the value. Otherwise Rhs_Val_Known is set False, and 1340 -- the Rhs_Val is undefined. 1341 1342 Require_Byte_Swapping : Boolean := False; 1343 -- True if byte swapping required, for the Reverse_Storage_Order case 1344 -- when the packed array is a free-standing object. (If it is part 1345 -- of a composite type, and therefore potentially not aligned on a byte 1346 -- boundary, the swapping is done by the back-end). 1347 1348 function Get_Shift return Node_Id; 1349 -- Function used to get the value of Shift, making sure that it 1350 -- gets duplicated if the function is called more than once. 1351 1352 --------------- 1353 -- Get_Shift -- 1354 --------------- 1355 1356 function Get_Shift return Node_Id is 1357 begin 1358 -- If we used the shift value already, then duplicate it. We 1359 -- set a temporary parent in case actions have to be inserted. 1360 1361 if Shift_Used then 1362 Set_Parent (Shift, N); 1363 return Duplicate_Subexpr_No_Checks (Shift); 1364 1365 -- If first time, use Shift unchanged, and set flag for first use 1366 1367 else 1368 Shift_Used := True; 1369 return Shift; 1370 end if; 1371 end Get_Shift; 1372 1373 -- Start of processing for Expand_Bit_Packed_Element_Set 1374 1375 begin 1376 pragma Assert (Is_Bit_Packed_Array (Etype (Prefix (Lhs)))); 1377 1378 Obj := Relocate_Node (Prefix (Lhs)); 1379 Convert_To_Actual_Subtype (Obj); 1380 Atyp := Etype (Obj); 1381 PAT := Packed_Array_Type (Atyp); 1382 Ctyp := Component_Type (Atyp); 1383 Csiz := UI_To_Int (Component_Size (Atyp)); 1384 1385 -- We remove side effects, in case the rhs modifies the lhs, because we 1386 -- are about to transform the rhs into an expression that first READS 1387 -- the lhs, so we can do the necessary shifting and masking. Example: 1388 -- "X(2) := F(...);" where F modifies X(3). Otherwise, the side effect 1389 -- will be lost. 1390 1391 Remove_Side_Effects (Rhs); 1392 1393 -- We convert the right hand side to the proper subtype to ensure 1394 -- that an appropriate range check is made (since the normal range 1395 -- check from assignment will be lost in the transformations). This 1396 -- conversion is analyzed immediately so that subsequent processing 1397 -- can work with an analyzed Rhs (and e.g. look at its Etype) 1398 1399 -- If the right-hand side is a string literal, create a temporary for 1400 -- it, constant-folding is not ready to wrap the bit representation 1401 -- of a string literal. 1402 1403 if Nkind (Rhs) = N_String_Literal then 1404 declare 1405 Decl : Node_Id; 1406 begin 1407 Decl := 1408 Make_Object_Declaration (Loc, 1409 Defining_Identifier => Make_Temporary (Loc, 'T', Rhs), 1410 Object_Definition => New_Occurrence_Of (Ctyp, Loc), 1411 Expression => New_Copy_Tree (Rhs)); 1412 1413 Insert_Actions (N, New_List (Decl)); 1414 Rhs := New_Occurrence_Of (Defining_Identifier (Decl), Loc); 1415 end; 1416 end if; 1417 1418 Rhs := Convert_To (Ctyp, Rhs); 1419 Set_Parent (Rhs, N); 1420 1421 -- If we are building the initialization procedure for a packed array, 1422 -- and Initialize_Scalars is enabled, each component assignment is an 1423 -- out-of-range value by design. Compile this value without checks, 1424 -- because a call to the array init_proc must not raise an exception. 1425 1426 if Within_Init_Proc 1427 and then Initialize_Scalars 1428 then 1429 Analyze_And_Resolve (Rhs, Ctyp, Suppress => All_Checks); 1430 else 1431 Analyze_And_Resolve (Rhs, Ctyp); 1432 end if; 1433 1434 -- For the AAMP target, indexing of certain packed array is passed 1435 -- through to the back end without expansion, because the expansion 1436 -- results in very inefficient code on that target. This allows the 1437 -- GNAAMP back end to generate specialized macros that support more 1438 -- efficient indexing of packed arrays with components having sizes 1439 -- that are small powers of two. 1440 1441 if AAMP_On_Target 1442 and then (Csiz = 1 or else Csiz = 2 or else Csiz = 4) 1443 then 1444 return; 1445 end if; 1446 1447 -- Case of component size 1,2,4 or any component size for the modular 1448 -- case. These are the cases for which we can inline the code. 1449 1450 if Csiz = 1 or else Csiz = 2 or else Csiz = 4 1451 or else (Present (PAT) and then Is_Modular_Integer_Type (PAT)) 1452 then 1453 Setup_Inline_Packed_Array_Reference (Lhs, Atyp, Obj, Cmask, Shift); 1454 1455 -- The statement to be generated is: 1456 1457 -- Obj := atyp!((Obj and Mask1) or (shift_left (rhs, Shift))) 1458 1459 -- or in the case of a freestanding Reverse_Storage_Order object, 1460 1461 -- Obj := Swap (atyp!((Swap (Obj) and Mask1) 1462 -- or (shift_left (rhs, Shift)))) 1463 1464 -- where Mask1 is obtained by shifting Cmask left Shift bits 1465 -- and then complementing the result. 1466 1467 -- the "and Mask1" is omitted if rhs is constant and all 1 bits 1468 1469 -- the "or ..." is omitted if rhs is constant and all 0 bits 1470 1471 -- rhs is converted to the appropriate type 1472 1473 -- The result is converted back to the array type, since 1474 -- otherwise we lose knowledge of the packed nature. 1475 1476 -- Determine if right side is all 0 bits or all 1 bits 1477 1478 if Compile_Time_Known_Value (Rhs) then 1479 Rhs_Val := Expr_Rep_Value (Rhs); 1480 Rhs_Val_Known := True; 1481 1482 -- The following test catches the case of an unchecked conversion of 1483 -- an integer literal. This results from optimizing aggregates of 1484 -- packed types. 1485 1486 elsif Nkind (Rhs) = N_Unchecked_Type_Conversion 1487 and then Compile_Time_Known_Value (Expression (Rhs)) 1488 then 1489 Rhs_Val := Expr_Rep_Value (Expression (Rhs)); 1490 Rhs_Val_Known := True; 1491 1492 else 1493 Rhs_Val := No_Uint; 1494 Rhs_Val_Known := False; 1495 end if; 1496 1497 -- Some special checks for the case where the right hand value is 1498 -- known at compile time. Basically we have to take care of the 1499 -- implicit conversion to the subtype of the component object. 1500 1501 if Rhs_Val_Known then 1502 1503 -- If we have a biased component type then we must manually do the 1504 -- biasing, since we are taking responsibility in this case for 1505 -- constructing the exact bit pattern to be used. 1506 1507 if Has_Biased_Representation (Ctyp) then 1508 Rhs_Val := Rhs_Val - Expr_Rep_Value (Type_Low_Bound (Ctyp)); 1509 end if; 1510 1511 -- For a negative value, we manually convert the two's complement 1512 -- value to a corresponding unsigned value, so that the proper 1513 -- field width is maintained. If we did not do this, we would 1514 -- get too many leading sign bits later on. 1515 1516 if Rhs_Val < 0 then 1517 Rhs_Val := 2 ** UI_From_Int (Csiz) + Rhs_Val; 1518 end if; 1519 end if; 1520 1521 -- Now create copies removing side effects. Note that in some complex 1522 -- cases, this may cause the fact that we have already set a packed 1523 -- array type on Obj to get lost. So we save the type of Obj, and 1524 -- make sure it is reset properly. 1525 1526 declare 1527 T : constant Entity_Id := Etype (Obj); 1528 begin 1529 New_Lhs := Duplicate_Subexpr (Obj, True); 1530 New_Rhs := Duplicate_Subexpr_No_Checks (Obj); 1531 Set_Etype (Obj, T); 1532 Set_Etype (New_Lhs, T); 1533 Set_Etype (New_Rhs, T); 1534 1535 if Reverse_Storage_Order (Base_Type (Atyp)) 1536 and then Esize (T) > 8 1537 and then not In_Reverse_Storage_Order_Object (Obj) 1538 then 1539 Require_Byte_Swapping := True; 1540 New_Rhs := Byte_Swap (New_Rhs); 1541 end if; 1542 end; 1543 1544 -- First we deal with the "and" 1545 1546 if not Rhs_Val_Known or else Rhs_Val /= Cmask then 1547 declare 1548 Mask1 : Node_Id; 1549 Lit : Node_Id; 1550 1551 begin 1552 if Compile_Time_Known_Value (Shift) then 1553 Mask1 := 1554 Make_Integer_Literal (Loc, 1555 Modulus (Etype (Obj)) - 1 - 1556 (Cmask * (2 ** Expr_Value (Get_Shift)))); 1557 Set_Print_In_Hex (Mask1); 1558 1559 else 1560 Lit := Make_Integer_Literal (Loc, Cmask); 1561 Set_Print_In_Hex (Lit); 1562 Mask1 := 1563 Make_Op_Not (Loc, 1564 Right_Opnd => Make_Shift_Left (Lit, Get_Shift)); 1565 end if; 1566 1567 New_Rhs := 1568 Make_Op_And (Loc, 1569 Left_Opnd => New_Rhs, 1570 Right_Opnd => Mask1); 1571 end; 1572 end if; 1573 1574 -- Then deal with the "or" 1575 1576 if not Rhs_Val_Known or else Rhs_Val /= 0 then 1577 declare 1578 Or_Rhs : Node_Id; 1579 1580 procedure Fixup_Rhs; 1581 -- Adjust Rhs by bias if biased representation for components 1582 -- or remove extraneous high order sign bits if signed. 1583 1584 procedure Fixup_Rhs is 1585 Etyp : constant Entity_Id := Etype (Rhs); 1586 1587 begin 1588 -- For biased case, do the required biasing by simply 1589 -- converting to the biased subtype (the conversion 1590 -- will generate the required bias). 1591 1592 if Has_Biased_Representation (Ctyp) then 1593 Rhs := Convert_To (Ctyp, Rhs); 1594 1595 -- For a signed integer type that is not biased, generate 1596 -- a conversion to unsigned to strip high order sign bits. 1597 1598 elsif Is_Signed_Integer_Type (Ctyp) then 1599 Rhs := Unchecked_Convert_To (RTE (Bits_Id (Csiz)), Rhs); 1600 end if; 1601 1602 -- Set Etype, since it can be referenced before the node is 1603 -- completely analyzed. 1604 1605 Set_Etype (Rhs, Etyp); 1606 1607 -- We now need to do an unchecked conversion of the 1608 -- result to the target type, but it is important that 1609 -- this conversion be a right justified conversion and 1610 -- not a left justified conversion. 1611 1612 Rhs := RJ_Unchecked_Convert_To (Etype (Obj), Rhs); 1613 1614 end Fixup_Rhs; 1615 1616 begin 1617 if Rhs_Val_Known 1618 and then Compile_Time_Known_Value (Get_Shift) 1619 then 1620 Or_Rhs := 1621 Make_Integer_Literal (Loc, 1622 Rhs_Val * (2 ** Expr_Value (Get_Shift))); 1623 Set_Print_In_Hex (Or_Rhs); 1624 1625 else 1626 -- We have to convert the right hand side to Etype (Obj). 1627 -- A special case arises if what we have now is a Val 1628 -- attribute reference whose expression type is Etype (Obj). 1629 -- This happens for assignments of fields from the same 1630 -- array. In this case we get the required right hand side 1631 -- by simply removing the inner attribute reference. 1632 1633 if Nkind (Rhs) = N_Attribute_Reference 1634 and then Attribute_Name (Rhs) = Name_Val 1635 and then Etype (First (Expressions (Rhs))) = Etype (Obj) 1636 then 1637 Rhs := Relocate_Node (First (Expressions (Rhs))); 1638 Fixup_Rhs; 1639 1640 -- If the value of the right hand side is a known integer 1641 -- value, then just replace it by an untyped constant, 1642 -- which will be properly retyped when we analyze and 1643 -- resolve the expression. 1644 1645 elsif Rhs_Val_Known then 1646 1647 -- Note that Rhs_Val has already been normalized to 1648 -- be an unsigned value with the proper number of bits. 1649 1650 Rhs := Make_Integer_Literal (Loc, Rhs_Val); 1651 1652 -- Otherwise we need an unchecked conversion 1653 1654 else 1655 Fixup_Rhs; 1656 end if; 1657 1658 Or_Rhs := Make_Shift_Left (Rhs, Get_Shift); 1659 end if; 1660 1661 if Nkind (New_Rhs) = N_Op_And then 1662 Set_Paren_Count (New_Rhs, 1); 1663 end if; 1664 1665 New_Rhs := 1666 Make_Op_Or (Loc, 1667 Left_Opnd => New_Rhs, 1668 Right_Opnd => Or_Rhs); 1669 end; 1670 end if; 1671 1672 if Require_Byte_Swapping then 1673 Set_Etype (New_Rhs, Etype (Obj)); 1674 New_Rhs := Byte_Swap (New_Rhs); 1675 end if; 1676 1677 -- Now do the rewrite 1678 1679 Rewrite (N, 1680 Make_Assignment_Statement (Loc, 1681 Name => New_Lhs, 1682 Expression => 1683 Unchecked_Convert_To (Etype (New_Lhs), New_Rhs))); 1684 Set_Assignment_OK (Name (N), Ass_OK); 1685 1686 -- All other component sizes for non-modular case 1687 1688 else 1689 -- We generate 1690 1691 -- Set_nn (Arr'address, Subscr, Bits_nn!(Rhs)) 1692 1693 -- where Subscr is the computed linear subscript 1694 1695 declare 1696 Bits_nn : constant Entity_Id := RTE (Bits_Id (Csiz)); 1697 Set_nn : Entity_Id; 1698 Subscr : Node_Id; 1699 Atyp : Entity_Id; 1700 1701 begin 1702 if No (Bits_nn) then 1703 1704 -- Error, most likely High_Integrity_Mode restriction 1705 1706 return; 1707 end if; 1708 1709 -- Acquire proper Set entity. We use the aligned or unaligned 1710 -- case as appropriate. 1711 1712 if Known_Aligned_Enough (Obj, Csiz) then 1713 Set_nn := RTE (Set_Id (Csiz)); 1714 else 1715 Set_nn := RTE (SetU_Id (Csiz)); 1716 end if; 1717 1718 -- Now generate the set reference 1719 1720 Obj := Relocate_Node (Prefix (Lhs)); 1721 Convert_To_Actual_Subtype (Obj); 1722 Atyp := Etype (Obj); 1723 Compute_Linear_Subscript (Atyp, Lhs, Subscr); 1724 1725 -- Below we must make the assumption that Obj is 1726 -- at least byte aligned, since otherwise its address 1727 -- cannot be taken. The assumption holds since the 1728 -- only arrays that can be misaligned are small packed 1729 -- arrays which are implemented as a modular type, and 1730 -- that is not the case here. 1731 1732 Rewrite (N, 1733 Make_Procedure_Call_Statement (Loc, 1734 Name => New_Occurrence_Of (Set_nn, Loc), 1735 Parameter_Associations => New_List ( 1736 Make_Attribute_Reference (Loc, 1737 Prefix => Obj, 1738 Attribute_Name => Name_Address), 1739 Subscr, 1740 Unchecked_Convert_To (Bits_nn, 1741 Convert_To (Ctyp, Rhs))))); 1742 1743 end; 1744 end if; 1745 1746 Analyze (N, Suppress => All_Checks); 1747 end Expand_Bit_Packed_Element_Set; 1748 1749 ------------------------------------- 1750 -- Expand_Packed_Address_Reference -- 1751 ------------------------------------- 1752 1753 procedure Expand_Packed_Address_Reference (N : Node_Id) is 1754 Loc : constant Source_Ptr := Sloc (N); 1755 Base : Node_Id; 1756 Offset : Node_Id; 1757 1758 begin 1759 -- We build an expression that has the form 1760 1761 -- outer_object'Address 1762 -- + (linear-subscript * component_size for each array reference 1763 -- + field'Bit_Position for each record field 1764 -- + ... 1765 -- + ...) / Storage_Unit; 1766 1767 Get_Base_And_Bit_Offset (Prefix (N), Base, Offset); 1768 1769 Rewrite (N, 1770 Unchecked_Convert_To (RTE (RE_Address), 1771 Make_Op_Add (Loc, 1772 Left_Opnd => 1773 Unchecked_Convert_To (RTE (RE_Integer_Address), 1774 Make_Attribute_Reference (Loc, 1775 Prefix => Base, 1776 Attribute_Name => Name_Address)), 1777 1778 Right_Opnd => 1779 Unchecked_Convert_To (RTE (RE_Integer_Address), 1780 Make_Op_Divide (Loc, 1781 Left_Opnd => Offset, 1782 Right_Opnd => 1783 Make_Integer_Literal (Loc, System_Storage_Unit)))))); 1784 1785 Analyze_And_Resolve (N, RTE (RE_Address)); 1786 end Expand_Packed_Address_Reference; 1787 1788 --------------------------------- 1789 -- Expand_Packed_Bit_Reference -- 1790 --------------------------------- 1791 1792 procedure Expand_Packed_Bit_Reference (N : Node_Id) is 1793 Loc : constant Source_Ptr := Sloc (N); 1794 Base : Node_Id; 1795 Offset : Node_Id; 1796 1797 begin 1798 -- We build an expression that has the form 1799 1800 -- (linear-subscript * component_size for each array reference 1801 -- + field'Bit_Position for each record field 1802 -- + ... 1803 -- + ...) mod Storage_Unit; 1804 1805 Get_Base_And_Bit_Offset (Prefix (N), Base, Offset); 1806 1807 Rewrite (N, 1808 Unchecked_Convert_To (Universal_Integer, 1809 Make_Op_Mod (Loc, 1810 Left_Opnd => Offset, 1811 Right_Opnd => Make_Integer_Literal (Loc, System_Storage_Unit)))); 1812 1813 Analyze_And_Resolve (N, Universal_Integer); 1814 end Expand_Packed_Bit_Reference; 1815 1816 ------------------------------------ 1817 -- Expand_Packed_Boolean_Operator -- 1818 ------------------------------------ 1819 1820 -- This routine expands "a op b" for the packed cases 1821 1822 procedure Expand_Packed_Boolean_Operator (N : Node_Id) is 1823 Loc : constant Source_Ptr := Sloc (N); 1824 Typ : constant Entity_Id := Etype (N); 1825 L : constant Node_Id := Relocate_Node (Left_Opnd (N)); 1826 R : constant Node_Id := Relocate_Node (Right_Opnd (N)); 1827 1828 Ltyp : Entity_Id; 1829 Rtyp : Entity_Id; 1830 PAT : Entity_Id; 1831 1832 begin 1833 Convert_To_Actual_Subtype (L); 1834 Convert_To_Actual_Subtype (R); 1835 1836 Ensure_Defined (Etype (L), N); 1837 Ensure_Defined (Etype (R), N); 1838 1839 Apply_Length_Check (R, Etype (L)); 1840 1841 Ltyp := Etype (L); 1842 Rtyp := Etype (R); 1843 1844 -- Deal with silly case of XOR where the subcomponent has a range 1845 -- True .. True where an exception must be raised. 1846 1847 if Nkind (N) = N_Op_Xor then 1848 Silly_Boolean_Array_Xor_Test (N, Rtyp); 1849 end if; 1850 1851 -- Now that that silliness is taken care of, get packed array type 1852 1853 Convert_To_PAT_Type (L); 1854 Convert_To_PAT_Type (R); 1855 1856 PAT := Etype (L); 1857 1858 -- For the modular case, we expand a op b into 1859 1860 -- rtyp!(pat!(a) op pat!(b)) 1861 1862 -- where rtyp is the Etype of the left operand. Note that we do not 1863 -- convert to the base type, since this would be unconstrained, and 1864 -- hence not have a corresponding packed array type set. 1865 1866 -- Note that both operands must be modular for this code to be used 1867 1868 if Is_Modular_Integer_Type (PAT) 1869 and then 1870 Is_Modular_Integer_Type (Etype (R)) 1871 then 1872 declare 1873 P : Node_Id; 1874 1875 begin 1876 if Nkind (N) = N_Op_And then 1877 P := Make_Op_And (Loc, L, R); 1878 1879 elsif Nkind (N) = N_Op_Or then 1880 P := Make_Op_Or (Loc, L, R); 1881 1882 else -- Nkind (N) = N_Op_Xor 1883 P := Make_Op_Xor (Loc, L, R); 1884 end if; 1885 1886 Rewrite (N, Unchecked_Convert_To (Ltyp, P)); 1887 end; 1888 1889 -- For the array case, we insert the actions 1890 1891 -- Result : Ltype; 1892 1893 -- System.Bit_Ops.Bit_And/Or/Xor 1894 -- (Left'Address, 1895 -- Ltype'Length * Ltype'Component_Size; 1896 -- Right'Address, 1897 -- Rtype'Length * Rtype'Component_Size 1898 -- Result'Address); 1899 1900 -- where Left and Right are the Packed_Bytes{1,2,4} operands and 1901 -- the second argument and fourth arguments are the lengths of the 1902 -- operands in bits. Then we replace the expression by a reference 1903 -- to Result. 1904 1905 -- Note that if we are mixing a modular and array operand, everything 1906 -- works fine, since we ensure that the modular representation has the 1907 -- same physical layout as the array representation (that's what the 1908 -- left justified modular stuff in the big-endian case is about). 1909 1910 else 1911 declare 1912 Result_Ent : constant Entity_Id := Make_Temporary (Loc, 'T'); 1913 E_Id : RE_Id; 1914 1915 begin 1916 if Nkind (N) = N_Op_And then 1917 E_Id := RE_Bit_And; 1918 1919 elsif Nkind (N) = N_Op_Or then 1920 E_Id := RE_Bit_Or; 1921 1922 else -- Nkind (N) = N_Op_Xor 1923 E_Id := RE_Bit_Xor; 1924 end if; 1925 1926 Insert_Actions (N, New_List ( 1927 1928 Make_Object_Declaration (Loc, 1929 Defining_Identifier => Result_Ent, 1930 Object_Definition => New_Occurrence_Of (Ltyp, Loc)), 1931 1932 Make_Procedure_Call_Statement (Loc, 1933 Name => New_Occurrence_Of (RTE (E_Id), Loc), 1934 Parameter_Associations => New_List ( 1935 1936 Make_Byte_Aligned_Attribute_Reference (Loc, 1937 Prefix => L, 1938 Attribute_Name => Name_Address), 1939 1940 Make_Op_Multiply (Loc, 1941 Left_Opnd => 1942 Make_Attribute_Reference (Loc, 1943 Prefix => 1944 New_Occurrence_Of 1945 (Etype (First_Index (Ltyp)), Loc), 1946 Attribute_Name => Name_Range_Length), 1947 1948 Right_Opnd => 1949 Make_Integer_Literal (Loc, Component_Size (Ltyp))), 1950 1951 Make_Byte_Aligned_Attribute_Reference (Loc, 1952 Prefix => R, 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 (Rtyp)), Loc), 1961 Attribute_Name => Name_Range_Length), 1962 1963 Right_Opnd => 1964 Make_Integer_Literal (Loc, Component_Size (Rtyp))), 1965 1966 Make_Byte_Aligned_Attribute_Reference (Loc, 1967 Prefix => New_Occurrence_Of (Result_Ent, Loc), 1968 Attribute_Name => Name_Address))))); 1969 1970 Rewrite (N, 1971 New_Occurrence_Of (Result_Ent, Loc)); 1972 end; 1973 end if; 1974 1975 Analyze_And_Resolve (N, Typ, Suppress => All_Checks); 1976 end Expand_Packed_Boolean_Operator; 1977 1978 ------------------------------------- 1979 -- Expand_Packed_Element_Reference -- 1980 ------------------------------------- 1981 1982 procedure Expand_Packed_Element_Reference (N : Node_Id) is 1983 Loc : constant Source_Ptr := Sloc (N); 1984 Obj : Node_Id; 1985 Atyp : Entity_Id; 1986 PAT : Entity_Id; 1987 Ctyp : Entity_Id; 1988 Csiz : Int; 1989 Shift : Node_Id; 1990 Cmask : Uint; 1991 Lit : Node_Id; 1992 Arg : Node_Id; 1993 1994 begin 1995 -- If not bit packed, we have the enumeration case, which is easily 1996 -- dealt with (just adjust the subscripts of the indexed component) 1997 1998 -- Note: this leaves the result as an indexed component, which is 1999 -- still a variable, so can be used in the assignment case, as is 2000 -- required in the enumeration case. 2001 2002 if not Is_Bit_Packed_Array (Etype (Prefix (N))) then 2003 Setup_Enumeration_Packed_Array_Reference (N); 2004 return; 2005 end if; 2006 2007 -- Remaining processing is for the bit-packed case 2008 2009 Obj := Relocate_Node (Prefix (N)); 2010 Convert_To_Actual_Subtype (Obj); 2011 Atyp := Etype (Obj); 2012 PAT := Packed_Array_Type (Atyp); 2013 Ctyp := Component_Type (Atyp); 2014 Csiz := UI_To_Int (Component_Size (Atyp)); 2015 2016 -- For the AAMP target, indexing of certain packed array is passed 2017 -- through to the back end without expansion, because the expansion 2018 -- results in very inefficient code on that target. This allows the 2019 -- GNAAMP back end to generate specialized macros that support more 2020 -- efficient indexing of packed arrays with components having sizes 2021 -- that are small powers of two. 2022 2023 if AAMP_On_Target 2024 and then (Csiz = 1 or else Csiz = 2 or else Csiz = 4) 2025 then 2026 return; 2027 end if; 2028 2029 -- Case of component size 1,2,4 or any component size for the modular 2030 -- case. These are the cases for which we can inline the code. 2031 2032 if Csiz = 1 or else Csiz = 2 or else Csiz = 4 2033 or else (Present (PAT) and then Is_Modular_Integer_Type (PAT)) 2034 then 2035 Setup_Inline_Packed_Array_Reference (N, Atyp, Obj, Cmask, Shift); 2036 Lit := Make_Integer_Literal (Loc, Cmask); 2037 Set_Print_In_Hex (Lit); 2038 2039 -- Byte swapping required for the Reverse_Storage_Order case, but 2040 -- only for a free-standing object (see note on Require_Byte_Swapping 2041 -- in Expand_Bit_Packed_Element_Set). 2042 2043 if Reverse_Storage_Order (Atyp) 2044 and then Esize (Atyp) > 8 2045 and then not In_Reverse_Storage_Order_Object (Obj) 2046 then 2047 Obj := Byte_Swap (Obj); 2048 end if; 2049 2050 -- We generate a shift right to position the field, followed by a 2051 -- masking operation to extract the bit field, and we finally do an 2052 -- unchecked conversion to convert the result to the required target. 2053 2054 -- Note that the unchecked conversion automatically deals with the 2055 -- bias if we are dealing with a biased representation. What will 2056 -- happen is that we temporarily generate the biased representation, 2057 -- but almost immediately that will be converted to the original 2058 -- unbiased component type, and the bias will disappear. 2059 2060 Arg := 2061 Make_Op_And (Loc, 2062 Left_Opnd => Make_Shift_Right (Obj, Shift), 2063 Right_Opnd => Lit); 2064 2065 -- We needed to analyze this before we do the unchecked convert 2066 -- below, but we need it temporarily attached to the tree for 2067 -- this analysis (hence the temporary Set_Parent call). 2068 2069 Set_Parent (Arg, Parent (N)); 2070 Analyze_And_Resolve (Arg); 2071 2072 Rewrite (N, RJ_Unchecked_Convert_To (Ctyp, Arg)); 2073 2074 -- All other component sizes for non-modular case 2075 2076 else 2077 -- We generate 2078 2079 -- Component_Type!(Get_nn (Arr'address, Subscr)) 2080 2081 -- where Subscr is the computed linear subscript 2082 2083 declare 2084 Get_nn : Entity_Id; 2085 Subscr : Node_Id; 2086 2087 begin 2088 -- Acquire proper Get entity. We use the aligned or unaligned 2089 -- case as appropriate. 2090 2091 if Known_Aligned_Enough (Obj, Csiz) then 2092 Get_nn := RTE (Get_Id (Csiz)); 2093 else 2094 Get_nn := RTE (GetU_Id (Csiz)); 2095 end if; 2096 2097 -- Now generate the get reference 2098 2099 Compute_Linear_Subscript (Atyp, N, Subscr); 2100 2101 -- Below we make the assumption that Obj is at least byte 2102 -- aligned, since otherwise its address cannot be taken. 2103 -- The assumption holds since the only arrays that can be 2104 -- misaligned are small packed arrays which are implemented 2105 -- as a modular type, and that is not the case here. 2106 2107 Rewrite (N, 2108 Unchecked_Convert_To (Ctyp, 2109 Make_Function_Call (Loc, 2110 Name => New_Occurrence_Of (Get_nn, Loc), 2111 Parameter_Associations => New_List ( 2112 Make_Attribute_Reference (Loc, 2113 Prefix => Obj, 2114 Attribute_Name => Name_Address), 2115 Subscr)))); 2116 end; 2117 end if; 2118 2119 Analyze_And_Resolve (N, Ctyp, Suppress => All_Checks); 2120 2121 end Expand_Packed_Element_Reference; 2122 2123 ---------------------- 2124 -- Expand_Packed_Eq -- 2125 ---------------------- 2126 2127 -- Handles expansion of "=" on packed array types 2128 2129 procedure Expand_Packed_Eq (N : Node_Id) is 2130 Loc : constant Source_Ptr := Sloc (N); 2131 L : constant Node_Id := Relocate_Node (Left_Opnd (N)); 2132 R : constant Node_Id := Relocate_Node (Right_Opnd (N)); 2133 2134 LLexpr : Node_Id; 2135 RLexpr : Node_Id; 2136 2137 Ltyp : Entity_Id; 2138 Rtyp : Entity_Id; 2139 PAT : Entity_Id; 2140 2141 begin 2142 Convert_To_Actual_Subtype (L); 2143 Convert_To_Actual_Subtype (R); 2144 Ltyp := Underlying_Type (Etype (L)); 2145 Rtyp := Underlying_Type (Etype (R)); 2146 2147 Convert_To_PAT_Type (L); 2148 Convert_To_PAT_Type (R); 2149 PAT := Etype (L); 2150 2151 LLexpr := 2152 Make_Op_Multiply (Loc, 2153 Left_Opnd => 2154 Make_Attribute_Reference (Loc, 2155 Prefix => New_Occurrence_Of (Ltyp, Loc), 2156 Attribute_Name => Name_Length), 2157 Right_Opnd => 2158 Make_Integer_Literal (Loc, Component_Size (Ltyp))); 2159 2160 RLexpr := 2161 Make_Op_Multiply (Loc, 2162 Left_Opnd => 2163 Make_Attribute_Reference (Loc, 2164 Prefix => New_Occurrence_Of (Rtyp, Loc), 2165 Attribute_Name => Name_Length), 2166 Right_Opnd => 2167 Make_Integer_Literal (Loc, Component_Size (Rtyp))); 2168 2169 -- For the modular case, we transform the comparison to: 2170 2171 -- Ltyp'Length = Rtyp'Length and then PAT!(L) = PAT!(R) 2172 2173 -- where PAT is the packed array type. This works fine, since in the 2174 -- modular case we guarantee that the unused bits are always zeroes. 2175 -- We do have to compare the lengths because we could be comparing 2176 -- two different subtypes of the same base type. 2177 2178 if Is_Modular_Integer_Type (PAT) then 2179 Rewrite (N, 2180 Make_And_Then (Loc, 2181 Left_Opnd => 2182 Make_Op_Eq (Loc, 2183 Left_Opnd => LLexpr, 2184 Right_Opnd => RLexpr), 2185 2186 Right_Opnd => 2187 Make_Op_Eq (Loc, 2188 Left_Opnd => L, 2189 Right_Opnd => R))); 2190 2191 -- For the non-modular case, we call a runtime routine 2192 2193 -- System.Bit_Ops.Bit_Eq 2194 -- (L'Address, L_Length, R'Address, R_Length) 2195 2196 -- where PAT is the packed array type, and the lengths are the lengths 2197 -- in bits of the original packed arrays. This routine takes care of 2198 -- not comparing the unused bits in the last byte. 2199 2200 else 2201 Rewrite (N, 2202 Make_Function_Call (Loc, 2203 Name => New_Occurrence_Of (RTE (RE_Bit_Eq), Loc), 2204 Parameter_Associations => New_List ( 2205 Make_Byte_Aligned_Attribute_Reference (Loc, 2206 Prefix => L, 2207 Attribute_Name => Name_Address), 2208 2209 LLexpr, 2210 2211 Make_Byte_Aligned_Attribute_Reference (Loc, 2212 Prefix => R, 2213 Attribute_Name => Name_Address), 2214 2215 RLexpr))); 2216 end if; 2217 2218 Analyze_And_Resolve (N, Standard_Boolean, Suppress => All_Checks); 2219 end Expand_Packed_Eq; 2220 2221 ----------------------- 2222 -- Expand_Packed_Not -- 2223 ----------------------- 2224 2225 -- Handles expansion of "not" on packed array types 2226 2227 procedure Expand_Packed_Not (N : Node_Id) is 2228 Loc : constant Source_Ptr := Sloc (N); 2229 Typ : constant Entity_Id := Etype (N); 2230 Opnd : constant Node_Id := Relocate_Node (Right_Opnd (N)); 2231 2232 Rtyp : Entity_Id; 2233 PAT : Entity_Id; 2234 Lit : Node_Id; 2235 2236 begin 2237 Convert_To_Actual_Subtype (Opnd); 2238 Rtyp := Etype (Opnd); 2239 2240 -- Deal with silly False..False and True..True subtype case 2241 2242 Silly_Boolean_Array_Not_Test (N, Rtyp); 2243 2244 -- Now that the silliness is taken care of, get packed array type 2245 2246 Convert_To_PAT_Type (Opnd); 2247 PAT := Etype (Opnd); 2248 2249 -- For the case where the packed array type is a modular type, "not A" 2250 -- expands simply into: 2251 2252 -- Rtyp!(PAT!(A) xor Mask) 2253 2254 -- where PAT is the packed array type, Mask is a mask of all 1 bits of 2255 -- length equal to the size of this packed type, and Rtyp is the actual 2256 -- actual subtype of the operand. 2257 2258 Lit := Make_Integer_Literal (Loc, 2 ** RM_Size (PAT) - 1); 2259 Set_Print_In_Hex (Lit); 2260 2261 if not Is_Array_Type (PAT) then 2262 Rewrite (N, 2263 Unchecked_Convert_To (Rtyp, 2264 Make_Op_Xor (Loc, 2265 Left_Opnd => Opnd, 2266 Right_Opnd => Lit))); 2267 2268 -- For the array case, we insert the actions 2269 2270 -- Result : Typ; 2271 2272 -- System.Bit_Ops.Bit_Not 2273 -- (Opnd'Address, 2274 -- Typ'Length * Typ'Component_Size, 2275 -- Result'Address); 2276 2277 -- where Opnd is the Packed_Bytes{1,2,4} operand and the second argument 2278 -- is the length of the operand in bits. We then replace the expression 2279 -- with a reference to Result. 2280 2281 else 2282 declare 2283 Result_Ent : constant Entity_Id := Make_Temporary (Loc, 'T'); 2284 2285 begin 2286 Insert_Actions (N, New_List ( 2287 Make_Object_Declaration (Loc, 2288 Defining_Identifier => Result_Ent, 2289 Object_Definition => New_Occurrence_Of (Rtyp, Loc)), 2290 2291 Make_Procedure_Call_Statement (Loc, 2292 Name => New_Occurrence_Of (RTE (RE_Bit_Not), Loc), 2293 Parameter_Associations => New_List ( 2294 Make_Byte_Aligned_Attribute_Reference (Loc, 2295 Prefix => Opnd, 2296 Attribute_Name => Name_Address), 2297 2298 Make_Op_Multiply (Loc, 2299 Left_Opnd => 2300 Make_Attribute_Reference (Loc, 2301 Prefix => 2302 New_Occurrence_Of 2303 (Etype (First_Index (Rtyp)), Loc), 2304 Attribute_Name => Name_Range_Length), 2305 2306 Right_Opnd => 2307 Make_Integer_Literal (Loc, Component_Size (Rtyp))), 2308 2309 Make_Byte_Aligned_Attribute_Reference (Loc, 2310 Prefix => New_Occurrence_Of (Result_Ent, Loc), 2311 Attribute_Name => Name_Address))))); 2312 2313 Rewrite (N, New_Occurrence_Of (Result_Ent, Loc)); 2314 end; 2315 end if; 2316 2317 Analyze_And_Resolve (N, Typ, Suppress => All_Checks); 2318 end Expand_Packed_Not; 2319 2320 ----------------------------- 2321 -- Get_Base_And_Bit_Offset -- 2322 ----------------------------- 2323 2324 procedure Get_Base_And_Bit_Offset 2325 (N : Node_Id; 2326 Base : out Node_Id; 2327 Offset : out Node_Id) 2328 is 2329 Loc : Source_Ptr; 2330 Term : Node_Id; 2331 Atyp : Entity_Id; 2332 Subscr : Node_Id; 2333 2334 begin 2335 Base := N; 2336 Offset := Empty; 2337 2338 -- We build up an expression serially that has the form 2339 2340 -- linear-subscript * component_size for each array reference 2341 -- + field'Bit_Position for each record field 2342 -- + ... 2343 2344 loop 2345 Loc := Sloc (Base); 2346 2347 if Nkind (Base) = N_Indexed_Component then 2348 Convert_To_Actual_Subtype (Prefix (Base)); 2349 Atyp := Etype (Prefix (Base)); 2350 Compute_Linear_Subscript (Atyp, Base, Subscr); 2351 2352 Term := 2353 Make_Op_Multiply (Loc, 2354 Left_Opnd => Subscr, 2355 Right_Opnd => 2356 Make_Attribute_Reference (Loc, 2357 Prefix => New_Occurrence_Of (Atyp, Loc), 2358 Attribute_Name => Name_Component_Size)); 2359 2360 elsif Nkind (Base) = N_Selected_Component then 2361 Term := 2362 Make_Attribute_Reference (Loc, 2363 Prefix => Selector_Name (Base), 2364 Attribute_Name => Name_Bit_Position); 2365 2366 else 2367 return; 2368 end if; 2369 2370 if No (Offset) then 2371 Offset := Term; 2372 2373 else 2374 Offset := 2375 Make_Op_Add (Loc, 2376 Left_Opnd => Offset, 2377 Right_Opnd => Term); 2378 end if; 2379 2380 Base := Prefix (Base); 2381 end loop; 2382 end Get_Base_And_Bit_Offset; 2383 2384 ------------------------------------- 2385 -- Involves_Packed_Array_Reference -- 2386 ------------------------------------- 2387 2388 function Involves_Packed_Array_Reference (N : Node_Id) return Boolean is 2389 begin 2390 if Nkind (N) = N_Indexed_Component 2391 and then Is_Bit_Packed_Array (Etype (Prefix (N))) 2392 then 2393 return True; 2394 2395 elsif Nkind (N) = N_Selected_Component then 2396 return Involves_Packed_Array_Reference (Prefix (N)); 2397 2398 else 2399 return False; 2400 end if; 2401 end Involves_Packed_Array_Reference; 2402 2403 -------------------------- 2404 -- Known_Aligned_Enough -- 2405 -------------------------- 2406 2407 function Known_Aligned_Enough (Obj : Node_Id; Csiz : Nat) return Boolean is 2408 Typ : constant Entity_Id := Etype (Obj); 2409 2410 function In_Partially_Packed_Record (Comp : Entity_Id) return Boolean; 2411 -- If the component is in a record that contains previous packed 2412 -- components, consider it unaligned because the back-end might 2413 -- choose to pack the rest of the record. Lead to less efficient code, 2414 -- but safer vis-a-vis of back-end choices. 2415 2416 -------------------------------- 2417 -- In_Partially_Packed_Record -- 2418 -------------------------------- 2419 2420 function In_Partially_Packed_Record (Comp : Entity_Id) return Boolean is 2421 Rec_Type : constant Entity_Id := Scope (Comp); 2422 Prev_Comp : Entity_Id; 2423 2424 begin 2425 Prev_Comp := First_Entity (Rec_Type); 2426 while Present (Prev_Comp) loop 2427 if Is_Packed (Etype (Prev_Comp)) then 2428 return True; 2429 2430 elsif Prev_Comp = Comp then 2431 return False; 2432 end if; 2433 2434 Next_Entity (Prev_Comp); 2435 end loop; 2436 2437 return False; 2438 end In_Partially_Packed_Record; 2439 2440 -- Start of processing for Known_Aligned_Enough 2441 2442 begin 2443 -- Odd bit sizes don't need alignment anyway 2444 2445 if Csiz mod 2 = 1 then 2446 return True; 2447 2448 -- If we have a specified alignment, see if it is sufficient, if not 2449 -- then we can't possibly be aligned enough in any case. 2450 2451 elsif Known_Alignment (Etype (Obj)) then 2452 -- Alignment required is 4 if size is a multiple of 4, and 2453 -- 2 otherwise (e.g. 12 bits requires 4, 10 bits requires 2) 2454 2455 if Alignment (Etype (Obj)) < 4 - (Csiz mod 4) then 2456 return False; 2457 end if; 2458 end if; 2459 2460 -- OK, alignment should be sufficient, if object is aligned 2461 2462 -- If object is strictly aligned, then it is definitely aligned 2463 2464 if Strict_Alignment (Typ) then 2465 return True; 2466 2467 -- Case of subscripted array reference 2468 2469 elsif Nkind (Obj) = N_Indexed_Component then 2470 2471 -- If we have a pointer to an array, then this is definitely 2472 -- aligned, because pointers always point to aligned versions. 2473 2474 if Is_Access_Type (Etype (Prefix (Obj))) then 2475 return True; 2476 2477 -- Otherwise, go look at the prefix 2478 2479 else 2480 return Known_Aligned_Enough (Prefix (Obj), Csiz); 2481 end if; 2482 2483 -- Case of record field 2484 2485 elsif Nkind (Obj) = N_Selected_Component then 2486 2487 -- What is significant here is whether the record type is packed 2488 2489 if Is_Record_Type (Etype (Prefix (Obj))) 2490 and then Is_Packed (Etype (Prefix (Obj))) 2491 then 2492 return False; 2493 2494 -- Or the component has a component clause which might cause 2495 -- the component to become unaligned (we can't tell if the 2496 -- backend is doing alignment computations). 2497 2498 elsif Present (Component_Clause (Entity (Selector_Name (Obj)))) then 2499 return False; 2500 2501 elsif In_Partially_Packed_Record (Entity (Selector_Name (Obj))) then 2502 return False; 2503 2504 -- In all other cases, go look at prefix 2505 2506 else 2507 return Known_Aligned_Enough (Prefix (Obj), Csiz); 2508 end if; 2509 2510 elsif Nkind (Obj) = N_Type_Conversion then 2511 return Known_Aligned_Enough (Expression (Obj), Csiz); 2512 2513 -- For a formal parameter, it is safer to assume that it is not 2514 -- aligned, because the formal may be unconstrained while the actual 2515 -- is constrained. In this situation, a small constrained packed 2516 -- array, represented in modular form, may be unaligned. 2517 2518 elsif Is_Entity_Name (Obj) then 2519 return not Is_Formal (Entity (Obj)); 2520 else 2521 2522 -- If none of the above, must be aligned 2523 return True; 2524 end if; 2525 end Known_Aligned_Enough; 2526 2527 --------------------- 2528 -- Make_Shift_Left -- 2529 --------------------- 2530 2531 function Make_Shift_Left (N : Node_Id; S : Node_Id) return Node_Id is 2532 Nod : Node_Id; 2533 2534 begin 2535 if Compile_Time_Known_Value (S) and then Expr_Value (S) = 0 then 2536 return N; 2537 else 2538 Nod := 2539 Make_Op_Shift_Left (Sloc (N), 2540 Left_Opnd => N, 2541 Right_Opnd => S); 2542 Set_Shift_Count_OK (Nod, True); 2543 return Nod; 2544 end if; 2545 end Make_Shift_Left; 2546 2547 ---------------------- 2548 -- Make_Shift_Right -- 2549 ---------------------- 2550 2551 function Make_Shift_Right (N : Node_Id; S : Node_Id) return Node_Id is 2552 Nod : Node_Id; 2553 2554 begin 2555 if Compile_Time_Known_Value (S) and then Expr_Value (S) = 0 then 2556 return N; 2557 else 2558 Nod := 2559 Make_Op_Shift_Right (Sloc (N), 2560 Left_Opnd => N, 2561 Right_Opnd => S); 2562 Set_Shift_Count_OK (Nod, True); 2563 return Nod; 2564 end if; 2565 end Make_Shift_Right; 2566 2567 ----------------------------- 2568 -- RJ_Unchecked_Convert_To -- 2569 ----------------------------- 2570 2571 function RJ_Unchecked_Convert_To 2572 (Typ : Entity_Id; 2573 Expr : Node_Id) return Node_Id 2574 is 2575 Source_Typ : constant Entity_Id := Etype (Expr); 2576 Target_Typ : constant Entity_Id := Typ; 2577 2578 Src : Node_Id := Expr; 2579 2580 Source_Siz : Nat; 2581 Target_Siz : Nat; 2582 2583 begin 2584 Source_Siz := UI_To_Int (RM_Size (Source_Typ)); 2585 Target_Siz := UI_To_Int (RM_Size (Target_Typ)); 2586 2587 -- First step, if the source type is not a discrete type, then we first 2588 -- convert to a modular type of the source length, since otherwise, on 2589 -- a big-endian machine, we get left-justification. We do it for little- 2590 -- endian machines as well, because there might be junk bits that are 2591 -- not cleared if the type is not numeric. 2592 2593 if Source_Siz /= Target_Siz 2594 and then not Is_Discrete_Type (Source_Typ) 2595 then 2596 Src := Unchecked_Convert_To (RTE (Bits_Id (Source_Siz)), Src); 2597 end if; 2598 2599 -- In the big endian case, if the lengths of the two types differ, then 2600 -- we must worry about possible left justification in the conversion, 2601 -- and avoiding that is what this is all about. 2602 2603 if Bytes_Big_Endian and then Source_Siz /= Target_Siz then 2604 2605 -- Next step. If the target is not a discrete type, then we first 2606 -- convert to a modular type of the target length, since otherwise, 2607 -- on a big-endian machine, we get left-justification. 2608 2609 if not Is_Discrete_Type (Target_Typ) then 2610 Src := Unchecked_Convert_To (RTE (Bits_Id (Target_Siz)), Src); 2611 end if; 2612 end if; 2613 2614 -- And now we can do the final conversion to the target type 2615 2616 return Unchecked_Convert_To (Target_Typ, Src); 2617 end RJ_Unchecked_Convert_To; 2618 2619 ---------------------------------------------- 2620 -- Setup_Enumeration_Packed_Array_Reference -- 2621 ---------------------------------------------- 2622 2623 -- All we have to do here is to find the subscripts that correspond to the 2624 -- index positions that have non-standard enumeration types and insert a 2625 -- Pos attribute to get the proper subscript value. 2626 2627 -- Finally the prefix must be uncheck-converted to the corresponding packed 2628 -- array type. 2629 2630 -- Note that the component type is unchanged, so we do not need to fiddle 2631 -- with the types (Gigi always automatically takes the packed array type if 2632 -- it is set, as it will be in this case). 2633 2634 procedure Setup_Enumeration_Packed_Array_Reference (N : Node_Id) is 2635 Pfx : constant Node_Id := Prefix (N); 2636 Typ : constant Entity_Id := Etype (N); 2637 Exprs : constant List_Id := Expressions (N); 2638 Expr : Node_Id; 2639 2640 begin 2641 -- If the array is unconstrained, then we replace the array reference 2642 -- with its actual subtype. This actual subtype will have a packed array 2643 -- type with appropriate bounds. 2644 2645 if not Is_Constrained (Packed_Array_Type (Etype (Pfx))) then 2646 Convert_To_Actual_Subtype (Pfx); 2647 end if; 2648 2649 Expr := First (Exprs); 2650 while Present (Expr) loop 2651 declare 2652 Loc : constant Source_Ptr := Sloc (Expr); 2653 Expr_Typ : constant Entity_Id := Etype (Expr); 2654 2655 begin 2656 if Is_Enumeration_Type (Expr_Typ) 2657 and then Has_Non_Standard_Rep (Expr_Typ) 2658 then 2659 Rewrite (Expr, 2660 Make_Attribute_Reference (Loc, 2661 Prefix => New_Occurrence_Of (Expr_Typ, Loc), 2662 Attribute_Name => Name_Pos, 2663 Expressions => New_List (Relocate_Node (Expr)))); 2664 Analyze_And_Resolve (Expr, Standard_Natural); 2665 end if; 2666 end; 2667 2668 Next (Expr); 2669 end loop; 2670 2671 Rewrite (N, 2672 Make_Indexed_Component (Sloc (N), 2673 Prefix => 2674 Unchecked_Convert_To (Packed_Array_Type (Etype (Pfx)), Pfx), 2675 Expressions => Exprs)); 2676 2677 Analyze_And_Resolve (N, Typ); 2678 end Setup_Enumeration_Packed_Array_Reference; 2679 2680 ----------------------------------------- 2681 -- Setup_Inline_Packed_Array_Reference -- 2682 ----------------------------------------- 2683 2684 procedure Setup_Inline_Packed_Array_Reference 2685 (N : Node_Id; 2686 Atyp : Entity_Id; 2687 Obj : in out Node_Id; 2688 Cmask : out Uint; 2689 Shift : out Node_Id) 2690 is 2691 Loc : constant Source_Ptr := Sloc (N); 2692 PAT : Entity_Id; 2693 Otyp : Entity_Id; 2694 Csiz : Uint; 2695 Osiz : Uint; 2696 2697 begin 2698 Csiz := Component_Size (Atyp); 2699 2700 Convert_To_PAT_Type (Obj); 2701 PAT := Etype (Obj); 2702 2703 Cmask := 2 ** Csiz - 1; 2704 2705 if Is_Array_Type (PAT) then 2706 Otyp := Component_Type (PAT); 2707 Osiz := Component_Size (PAT); 2708 2709 else 2710 Otyp := PAT; 2711 2712 -- In the case where the PAT is a modular type, we want the actual 2713 -- size in bits of the modular value we use. This is neither the 2714 -- Object_Size nor the Value_Size, either of which may have been 2715 -- reset to strange values, but rather the minimum size. Note that 2716 -- since this is a modular type with full range, the issue of 2717 -- biased representation does not arise. 2718 2719 Osiz := UI_From_Int (Minimum_Size (Otyp)); 2720 end if; 2721 2722 Compute_Linear_Subscript (Atyp, N, Shift); 2723 2724 -- If the component size is not 1, then the subscript must be multiplied 2725 -- by the component size to get the shift count. 2726 2727 if Csiz /= 1 then 2728 Shift := 2729 Make_Op_Multiply (Loc, 2730 Left_Opnd => Make_Integer_Literal (Loc, Csiz), 2731 Right_Opnd => Shift); 2732 end if; 2733 2734 -- If we have the array case, then this shift count must be broken down 2735 -- into a byte subscript, and a shift within the byte. 2736 2737 if Is_Array_Type (PAT) then 2738 2739 declare 2740 New_Shift : Node_Id; 2741 2742 begin 2743 -- We must analyze shift, since we will duplicate it 2744 2745 Set_Parent (Shift, N); 2746 Analyze_And_Resolve 2747 (Shift, Standard_Integer, Suppress => All_Checks); 2748 2749 -- The shift count within the word is 2750 -- shift mod Osiz 2751 2752 New_Shift := 2753 Make_Op_Mod (Loc, 2754 Left_Opnd => Duplicate_Subexpr (Shift), 2755 Right_Opnd => Make_Integer_Literal (Loc, Osiz)); 2756 2757 -- The subscript to be used on the PAT array is 2758 -- shift / Osiz 2759 2760 Obj := 2761 Make_Indexed_Component (Loc, 2762 Prefix => Obj, 2763 Expressions => New_List ( 2764 Make_Op_Divide (Loc, 2765 Left_Opnd => Duplicate_Subexpr (Shift), 2766 Right_Opnd => Make_Integer_Literal (Loc, Osiz)))); 2767 2768 Shift := New_Shift; 2769 end; 2770 2771 -- For the modular integer case, the object to be manipulated is the 2772 -- entire array, so Obj is unchanged. Note that we will reset its type 2773 -- to PAT before returning to the caller. 2774 2775 else 2776 null; 2777 end if; 2778 2779 -- The one remaining step is to modify the shift count for the 2780 -- big-endian case. Consider the following example in a byte: 2781 2782 -- xxxxxxxx bits of byte 2783 -- vvvvvvvv bits of value 2784 -- 33221100 little-endian numbering 2785 -- 00112233 big-endian numbering 2786 2787 -- Here we have the case of 2-bit fields 2788 2789 -- For the little-endian case, we already have the proper shift count 2790 -- set, e.g. for element 2, the shift count is 2*2 = 4. 2791 2792 -- For the big endian case, we have to adjust the shift count, computing 2793 -- it as (N - F) - Shift, where N is the number of bits in an element of 2794 -- the array used to implement the packed array, F is the number of bits 2795 -- in a source array element, and Shift is the count so far computed. 2796 2797 -- We also have to adjust if the storage order is reversed 2798 2799 if Bytes_Big_Endian xor Reverse_Storage_Order (Base_Type (Atyp)) then 2800 Shift := 2801 Make_Op_Subtract (Loc, 2802 Left_Opnd => Make_Integer_Literal (Loc, Osiz - Csiz), 2803 Right_Opnd => Shift); 2804 end if; 2805 2806 Set_Parent (Shift, N); 2807 Set_Parent (Obj, N); 2808 Analyze_And_Resolve (Obj, Otyp, Suppress => All_Checks); 2809 Analyze_And_Resolve (Shift, Standard_Integer, Suppress => All_Checks); 2810 2811 -- Make sure final type of object is the appropriate packed type 2812 2813 Set_Etype (Obj, Otyp); 2814 2815 end Setup_Inline_Packed_Array_Reference; 2816 2817end Exp_Pakd; 2818