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) 1992-2019, 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 Lib.Xref; use Lib.Xref; 34with Namet; use Namet; 35with Nlists; use Nlists; 36with Nmake; use Nmake; 37with Opt; use Opt; 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 -- Local Subprograms -- 82 ----------------------- 83 84 procedure Compute_Linear_Subscript 85 (Atyp : Entity_Id; 86 N : Node_Id; 87 Subscr : out Node_Id); 88 -- Given a constrained array type Atyp, and an indexed component node N 89 -- referencing an array object of this type, build an expression of type 90 -- Standard.Integer representing the zero-based linear subscript value. 91 -- This expression includes any required range checks. 92 93 function Compute_Number_Components 94 (N : Node_Id; 95 Typ : Entity_Id) return Node_Id; 96 -- Build an expression that multiplies the length of the dimensions of the 97 -- array, used to control array equality checks. 98 99 procedure Convert_To_PAT_Type (Aexp : Node_Id); 100 -- Given an expression of a packed array type, builds a corresponding 101 -- expression whose type is the implementation type used to represent 102 -- the packed array. Aexp is analyzed and resolved on entry and on exit. 103 104 procedure Get_Base_And_Bit_Offset 105 (N : Node_Id; 106 Base : out Node_Id; 107 Offset : out Node_Id); 108 -- Given a node N for a name which involves a packed array reference, 109 -- return the base object of the reference and build an expression of 110 -- type Standard.Integer representing the zero-based offset in bits 111 -- from Base'Address to the first bit of the reference. 112 113 function Known_Aligned_Enough (Obj : Node_Id; Csiz : Nat) return Boolean; 114 -- There are two versions of the Set routines, the ones used when the 115 -- object is known to be sufficiently well aligned given the number of 116 -- bits, and the ones used when the object is not known to be aligned. 117 -- This routine is used to determine which set to use. Obj is a reference 118 -- to the object, and Csiz is the component size of the packed array. 119 -- True is returned if the alignment of object is known to be sufficient, 120 -- defined as 1 for odd bit sizes, 4 for bit sizes divisible by 4, and 121 -- 2 otherwise. 122 123 function Make_Shift_Left (N : Node_Id; S : Node_Id) return Node_Id; 124 -- Build a left shift node, checking for the case of a shift count of zero 125 126 function Make_Shift_Right (N : Node_Id; S : Node_Id) return Node_Id; 127 -- Build a right shift node, checking for the case of a shift count of zero 128 129 function RJ_Unchecked_Convert_To 130 (Typ : Entity_Id; 131 Expr : Node_Id) return Node_Id; 132 -- The packed array code does unchecked conversions which in some cases 133 -- may involve non-discrete types with differing sizes. The semantics of 134 -- such conversions is potentially endianness dependent, and the effect 135 -- we want here for such a conversion is to do the conversion in size as 136 -- though numeric items are involved, and we extend or truncate on the 137 -- left side. This happens naturally in the little-endian case, but in 138 -- the big endian case we can get left justification, when what we want 139 -- is right justification. This routine does the unchecked conversion in 140 -- a stepwise manner to ensure that it gives the expected result. Hence 141 -- the name (RJ = Right justified). The parameters Typ and Expr are as 142 -- for the case of a normal Unchecked_Convert_To call. 143 144 procedure Setup_Enumeration_Packed_Array_Reference (N : Node_Id); 145 -- This routine is called in the Get and Set case for arrays that are 146 -- packed but not bit-packed, meaning that they have at least one 147 -- subscript that is of an enumeration type with a non-standard 148 -- representation. This routine modifies the given node to properly 149 -- reference the corresponding packed array type. 150 151 procedure Setup_Inline_Packed_Array_Reference 152 (N : Node_Id; 153 Atyp : Entity_Id; 154 Obj : in out Node_Id; 155 Cmask : out Uint; 156 Shift : out Node_Id); 157 -- This procedure performs common processing on the N_Indexed_Component 158 -- parameter given as N, whose prefix is a reference to a packed array. 159 -- This is used for the get and set when the component size is 1, 2, 4, 160 -- or for other component sizes when the packed array type is a modular 161 -- type (i.e. the cases that are handled with inline code). 162 -- 163 -- On entry: 164 -- 165 -- N is the N_Indexed_Component node for the packed array reference 166 -- 167 -- Atyp is the constrained array type (the actual subtype has been 168 -- computed if necessary to obtain the constraints, but this is still 169 -- the original array type, not the Packed_Array_Impl_Type value). 170 -- 171 -- Obj is the object which is to be indexed. It is always of type Atyp. 172 -- 173 -- On return: 174 -- 175 -- Obj is the object containing the desired bit field. It is of type 176 -- Unsigned, Long_Unsigned, or Long_Long_Unsigned, and is either the 177 -- entire value, for the small static case, or the proper selected byte 178 -- from the array in the large or dynamic case. This node is analyzed 179 -- and resolved on return. 180 -- 181 -- Shift is a node representing the shift count to be used in the 182 -- rotate right instruction that positions the field for access. 183 -- This node is analyzed and resolved on return. 184 -- 185 -- Cmask is a mask corresponding to the width of the component field. 186 -- Its value is 2 ** Csize - 1 (e.g. 2#1111# for component size of 4). 187 -- 188 -- Note: in some cases the call to this routine may generate actions 189 -- (for handling multi-use references and the generation of the packed 190 -- array type on the fly). Such actions are inserted into the tree 191 -- directly using Insert_Action. 192 193 function Revert_Storage_Order (N : Node_Id) return Node_Id; 194 -- Perform appropriate justification and byte ordering adjustments for N, 195 -- an element of a packed array type, when both the component type and 196 -- the enclosing packed array type have reverse scalar storage order. 197 -- On little-endian targets, the value is left justified before byte 198 -- swapping. The Etype of the returned expression is an integer type of 199 -- an appropriate power-of-2 size. 200 201 -------------------------- 202 -- Revert_Storage_Order -- 203 -------------------------- 204 205 function Revert_Storage_Order (N : Node_Id) return Node_Id is 206 Loc : constant Source_Ptr := Sloc (N); 207 T : constant Entity_Id := Etype (N); 208 T_Size : constant Uint := RM_Size (T); 209 210 Swap_RE : RE_Id; 211 Swap_F : Entity_Id; 212 Swap_T : Entity_Id; 213 -- Swapping function 214 215 Arg : Node_Id; 216 Adjusted : Node_Id; 217 Shift : Uint; 218 219 begin 220 if T_Size <= 8 then 221 222 -- Array component size is less than a byte: no swapping needed 223 224 Swap_F := Empty; 225 Swap_T := RTE (RE_Unsigned_8); 226 227 else 228 -- Select byte swapping function depending on array component size 229 230 if T_Size <= 16 then 231 Swap_RE := RE_Bswap_16; 232 233 elsif T_Size <= 32 then 234 Swap_RE := RE_Bswap_32; 235 236 else pragma Assert (T_Size <= 64); 237 Swap_RE := RE_Bswap_64; 238 end if; 239 240 Swap_F := RTE (Swap_RE); 241 Swap_T := Etype (Swap_F); 242 243 end if; 244 245 Shift := Esize (Swap_T) - T_Size; 246 247 Arg := RJ_Unchecked_Convert_To (Swap_T, N); 248 249 if not Bytes_Big_Endian and then Shift > Uint_0 then 250 Arg := 251 Make_Op_Shift_Left (Loc, 252 Left_Opnd => Arg, 253 Right_Opnd => Make_Integer_Literal (Loc, Shift)); 254 end if; 255 256 if Present (Swap_F) then 257 Adjusted := 258 Make_Function_Call (Loc, 259 Name => New_Occurrence_Of (Swap_F, Loc), 260 Parameter_Associations => New_List (Arg)); 261 else 262 Adjusted := Arg; 263 end if; 264 265 Set_Etype (Adjusted, Swap_T); 266 return Adjusted; 267 end Revert_Storage_Order; 268 269 ------------------------------ 270 -- Compute_Linear_Subscript -- 271 ------------------------------ 272 273 procedure Compute_Linear_Subscript 274 (Atyp : Entity_Id; 275 N : Node_Id; 276 Subscr : out Node_Id) 277 is 278 Loc : constant Source_Ptr := Sloc (N); 279 Oldsub : Node_Id; 280 Newsub : Node_Id; 281 Indx : Node_Id; 282 Styp : Entity_Id; 283 284 begin 285 Subscr := Empty; 286 287 -- Loop through dimensions 288 289 Indx := First_Index (Atyp); 290 Oldsub := First (Expressions (N)); 291 292 while Present (Indx) loop 293 Styp := Etype (Indx); 294 Newsub := Relocate_Node (Oldsub); 295 296 -- Get expression for the subscript value. First, if Do_Range_Check 297 -- is set on a subscript, then we must do a range check against the 298 -- original bounds (not the bounds of the packed array type). We do 299 -- this by introducing a subtype conversion. 300 301 if Do_Range_Check (Newsub) 302 and then Etype (Newsub) /= Styp 303 then 304 Newsub := Convert_To (Styp, Newsub); 305 end if; 306 307 -- Now evolve the expression for the subscript. First convert 308 -- the subscript to be zero based and of an integer type. 309 310 -- Case of integer type, where we just subtract to get lower bound 311 312 if Is_Integer_Type (Styp) then 313 314 -- If length of integer type is smaller than standard integer, 315 -- then we convert to integer first, then do the subtract 316 317 -- Integer (subscript) - Integer (Styp'First) 318 319 if Esize (Styp) < Esize (Standard_Integer) then 320 Newsub := 321 Make_Op_Subtract (Loc, 322 Left_Opnd => Convert_To (Standard_Integer, Newsub), 323 Right_Opnd => 324 Convert_To (Standard_Integer, 325 Make_Attribute_Reference (Loc, 326 Prefix => New_Occurrence_Of (Styp, Loc), 327 Attribute_Name => Name_First))); 328 329 -- For larger integer types, subtract first, then convert to 330 -- integer, this deals with strange long long integer bounds. 331 332 -- Integer (subscript - Styp'First) 333 334 else 335 Newsub := 336 Convert_To (Standard_Integer, 337 Make_Op_Subtract (Loc, 338 Left_Opnd => Newsub, 339 Right_Opnd => 340 Make_Attribute_Reference (Loc, 341 Prefix => New_Occurrence_Of (Styp, Loc), 342 Attribute_Name => Name_First))); 343 end if; 344 345 -- For the enumeration case, we have to use 'Pos to get the value 346 -- to work with before subtracting the lower bound. 347 348 -- Integer (Styp'Pos (subscr)) - Integer (Styp'Pos (Styp'First)); 349 350 -- This is not quite right for bizarre cases where the size of the 351 -- enumeration type is > Integer'Size bits due to rep clause ??? 352 353 else 354 pragma Assert (Is_Enumeration_Type (Styp)); 355 356 Newsub := 357 Make_Op_Subtract (Loc, 358 Left_Opnd => Convert_To (Standard_Integer, 359 Make_Attribute_Reference (Loc, 360 Prefix => New_Occurrence_Of (Styp, Loc), 361 Attribute_Name => Name_Pos, 362 Expressions => New_List (Newsub))), 363 364 Right_Opnd => 365 Convert_To (Standard_Integer, 366 Make_Attribute_Reference (Loc, 367 Prefix => New_Occurrence_Of (Styp, Loc), 368 Attribute_Name => Name_Pos, 369 Expressions => New_List ( 370 Make_Attribute_Reference (Loc, 371 Prefix => New_Occurrence_Of (Styp, Loc), 372 Attribute_Name => Name_First))))); 373 end if; 374 375 Set_Paren_Count (Newsub, 1); 376 377 -- For the first subscript, we just copy that subscript value 378 379 if No (Subscr) then 380 Subscr := Newsub; 381 382 -- Otherwise, we must multiply what we already have by the current 383 -- stride and then add in the new value to the evolving subscript. 384 385 else 386 Subscr := 387 Make_Op_Add (Loc, 388 Left_Opnd => 389 Make_Op_Multiply (Loc, 390 Left_Opnd => Subscr, 391 Right_Opnd => 392 Make_Attribute_Reference (Loc, 393 Attribute_Name => Name_Range_Length, 394 Prefix => New_Occurrence_Of (Styp, Loc))), 395 Right_Opnd => Newsub); 396 end if; 397 398 -- Move to next subscript 399 400 Next_Index (Indx); 401 Next (Oldsub); 402 end loop; 403 end Compute_Linear_Subscript; 404 405 ------------------------------- 406 -- Compute_Number_Components -- 407 ------------------------------- 408 409 function Compute_Number_Components 410 (N : Node_Id; 411 Typ : Entity_Id) return Node_Id 412 is 413 Loc : constant Source_Ptr := Sloc (N); 414 Len_Expr : Node_Id; 415 416 begin 417 Len_Expr := 418 Make_Attribute_Reference (Loc, 419 Attribute_Name => Name_Length, 420 Prefix => New_Occurrence_Of (Typ, Loc), 421 Expressions => New_List (Make_Integer_Literal (Loc, 1))); 422 423 for J in 2 .. Number_Dimensions (Typ) loop 424 Len_Expr := 425 Make_Op_Multiply (Loc, 426 Left_Opnd => Len_Expr, 427 Right_Opnd => 428 Make_Attribute_Reference (Loc, 429 Attribute_Name => Name_Length, 430 Prefix => New_Occurrence_Of (Typ, Loc), 431 Expressions => New_List (Make_Integer_Literal (Loc, J)))); 432 end loop; 433 434 return Len_Expr; 435 end Compute_Number_Components; 436 437 ------------------------- 438 -- Convert_To_PAT_Type -- 439 ------------------------- 440 441 -- The PAT is always obtained from the actual subtype 442 443 procedure Convert_To_PAT_Type (Aexp : Node_Id) is 444 Act_ST : Entity_Id; 445 446 begin 447 Convert_To_Actual_Subtype (Aexp); 448 Act_ST := Underlying_Type (Etype (Aexp)); 449 Create_Packed_Array_Impl_Type (Act_ST); 450 451 -- Just replace the etype with the packed array type. This works because 452 -- the expression will not be further analyzed, and Gigi considers the 453 -- two types equivalent in any case. 454 455 -- This is not strictly the case ??? If the reference is an actual in 456 -- call, the expansion of the prefix is delayed, and must be reanalyzed, 457 -- see Reset_Packed_Prefix. On the other hand, if the prefix is a simple 458 -- array reference, reanalysis can produce spurious type errors when the 459 -- PAT type is replaced again with the original type of the array. Same 460 -- for the case of a dereference. Ditto for function calls: expansion 461 -- may introduce additional actuals which will trigger errors if call is 462 -- reanalyzed. The following is correct and minimal, but the handling of 463 -- more complex packed expressions in actuals is confused. Probably the 464 -- problem only remains for actuals in calls. 465 466 Set_Etype (Aexp, Packed_Array_Impl_Type (Act_ST)); 467 468 if Is_Entity_Name (Aexp) 469 or else 470 (Nkind (Aexp) = N_Indexed_Component 471 and then Is_Entity_Name (Prefix (Aexp))) 472 or else Nkind_In (Aexp, N_Explicit_Dereference, N_Function_Call) 473 then 474 Set_Analyzed (Aexp); 475 end if; 476 end Convert_To_PAT_Type; 477 478 ----------------------------------- 479 -- Create_Packed_Array_Impl_Type -- 480 ----------------------------------- 481 482 procedure Create_Packed_Array_Impl_Type (Typ : Entity_Id) is 483 Loc : constant Source_Ptr := Sloc (Typ); 484 Ctyp : constant Entity_Id := Component_Type (Typ); 485 Csize : constant Uint := Component_Size (Typ); 486 487 Ancest : Entity_Id; 488 PB_Type : Entity_Id; 489 PASize : Uint; 490 Decl : Node_Id; 491 PAT : Entity_Id; 492 Len_Expr : Node_Id; 493 Len_Bits : Uint; 494 Bits_U1 : Node_Id; 495 PAT_High : Node_Id; 496 Btyp : Entity_Id; 497 Lit : Node_Id; 498 499 procedure Install_PAT; 500 -- This procedure is called with Decl set to the declaration for the 501 -- packed array type. It creates the type and installs it as required. 502 503 procedure Set_PB_Type; 504 -- Sets PB_Type to Packed_Bytes{1,2,4} as required by the alignment 505 -- requirements (see documentation in the spec of this package). 506 507 ----------------- 508 -- Install_PAT -- 509 ----------------- 510 511 procedure Install_PAT is 512 Pushed_Scope : Boolean := False; 513 514 begin 515 -- We do not want to put the declaration we have created in the tree 516 -- since it is often hard, and sometimes impossible to find a proper 517 -- place for it (the impossible case arises for a packed array type 518 -- with bounds depending on the discriminant, a declaration cannot 519 -- be put inside the record, and the reference to the discriminant 520 -- cannot be outside the record). 521 522 -- The solution is to analyze the declaration while temporarily 523 -- attached to the tree at an appropriate point, and then we install 524 -- the resulting type as an Itype in the packed array type field of 525 -- the original type, so that no explicit declaration is required. 526 527 -- Note: the packed type is created in the scope of its parent type. 528 -- There are at least some cases where the current scope is deeper, 529 -- and so when this is the case, we temporarily reset the scope 530 -- for the definition. This is clearly safe, since the first use 531 -- of the packed array type will be the implicit reference from 532 -- the corresponding unpacked type when it is elaborated. 533 534 if Is_Itype (Typ) then 535 Set_Parent (Decl, Associated_Node_For_Itype (Typ)); 536 else 537 Set_Parent (Decl, Declaration_Node (Typ)); 538 end if; 539 540 if Scope (Typ) /= Current_Scope then 541 Push_Scope (Scope (Typ)); 542 Pushed_Scope := True; 543 end if; 544 545 Set_Is_Itype (PAT, True); 546 Set_Is_Packed_Array_Impl_Type (PAT, True); 547 Set_Packed_Array_Impl_Type (Typ, PAT); 548 Analyze (Decl, Suppress => All_Checks); 549 550 if Pushed_Scope then 551 Pop_Scope; 552 end if; 553 554 -- Set Esize and RM_Size to the actual size of the packed object 555 -- Do not reset RM_Size if already set, as happens in the case of 556 -- a modular type. 557 558 if Unknown_Esize (PAT) then 559 Set_Esize (PAT, PASize); 560 end if; 561 562 if Unknown_RM_Size (PAT) then 563 Set_RM_Size (PAT, PASize); 564 end if; 565 566 Adjust_Esize_Alignment (PAT); 567 568 -- Set remaining fields of packed array type 569 570 Init_Alignment (PAT); 571 Set_Parent (PAT, Empty); 572 Set_Associated_Node_For_Itype (PAT, Typ); 573 Set_Original_Array_Type (PAT, Typ); 574 575 -- Propagate representation aspects 576 577 Set_Is_Atomic (PAT, Is_Atomic (Typ)); 578 Set_Is_Independent (PAT, Is_Independent (Typ)); 579 Set_Is_Volatile (PAT, Is_Volatile (Typ)); 580 Set_Is_Volatile_Full_Access (PAT, Is_Volatile_Full_Access (Typ)); 581 Set_Treat_As_Volatile (PAT, Treat_As_Volatile (Typ)); 582 583 -- For a non-bit-packed array, propagate reverse storage order 584 -- flag from original base type to packed array base type. 585 586 if not Is_Bit_Packed_Array (Typ) then 587 Set_Reverse_Storage_Order 588 (Etype (PAT), Reverse_Storage_Order (Base_Type (Typ))); 589 end if; 590 591 -- We definitely do not want to delay freezing for packed array 592 -- types. This is of particular importance for the itypes that are 593 -- generated for record components depending on discriminants where 594 -- there is no place to put the freeze node. 595 596 Set_Has_Delayed_Freeze (PAT, False); 597 Set_Has_Delayed_Freeze (Etype (PAT), False); 598 599 -- If we did allocate a freeze node, then clear out the reference 600 -- since it is obsolete (should we delete the freeze node???) 601 602 Set_Freeze_Node (PAT, Empty); 603 Set_Freeze_Node (Etype (PAT), Empty); 604 end Install_PAT; 605 606 ----------------- 607 -- Set_PB_Type -- 608 ----------------- 609 610 procedure Set_PB_Type is 611 begin 612 -- If the user has specified an explicit alignment for the 613 -- type or component, take it into account. 614 615 if Csize <= 2 or else Csize = 4 or else Csize mod 2 /= 0 616 or else Alignment (Typ) = 1 617 or else Component_Alignment (Typ) = Calign_Storage_Unit 618 then 619 PB_Type := RTE (RE_Packed_Bytes1); 620 621 elsif Csize mod 4 /= 0 622 or else Alignment (Typ) = 2 623 then 624 PB_Type := RTE (RE_Packed_Bytes2); 625 626 else 627 PB_Type := RTE (RE_Packed_Bytes4); 628 end if; 629 end Set_PB_Type; 630 631 -- Start of processing for Create_Packed_Array_Impl_Type 632 633 begin 634 -- If we already have a packed array type, nothing to do 635 636 if Present (Packed_Array_Impl_Type (Typ)) then 637 return; 638 end if; 639 640 -- If our immediate ancestor subtype is constrained, and it already 641 -- has a packed array type, then just share the same type, since the 642 -- bounds must be the same. If the ancestor is not an array type but 643 -- a private type, as can happen with multiple instantiations, create 644 -- a new packed type, to avoid privacy issues. 645 646 if Ekind (Typ) = E_Array_Subtype then 647 Ancest := Ancestor_Subtype (Typ); 648 649 if Present (Ancest) 650 and then Is_Array_Type (Ancest) 651 and then Is_Constrained (Ancest) 652 and then Present (Packed_Array_Impl_Type (Ancest)) 653 then 654 Set_Packed_Array_Impl_Type (Typ, Packed_Array_Impl_Type (Ancest)); 655 return; 656 end if; 657 end if; 658 659 -- We preset the result type size from the size of the original array 660 -- type, since this size clearly belongs to the packed array type. The 661 -- size of the conceptual unpacked type is always set to unknown. 662 663 PASize := RM_Size (Typ); 664 665 -- Case of an array where at least one index is of an enumeration 666 -- type with a non-standard representation, but the component size 667 -- is not appropriate for bit packing. This is the case where we 668 -- have Is_Packed set (we would never be in this unit otherwise), 669 -- but Is_Bit_Packed_Array is false. 670 671 -- Note that if the component size is appropriate for bit packing, 672 -- then the circuit for the computation of the subscript properly 673 -- deals with the non-standard enumeration type case by taking the 674 -- Pos anyway. 675 676 if not Is_Bit_Packed_Array (Typ) then 677 678 -- Here we build a declaration: 679 680 -- type tttP is array (index1, index2, ...) of component_type 681 682 -- where index1, index2, are the index types. These are the same 683 -- as the index types of the original array, except for the non- 684 -- standard representation enumeration type case, where we have 685 -- two subcases. 686 687 -- For the unconstrained array case, we use 688 689 -- Natural range <> 690 691 -- For the constrained case, we use 692 693 -- Natural range Enum_Type'Pos (Enum_Type'First) .. 694 -- Enum_Type'Pos (Enum_Type'Last); 695 696 -- Note that tttP is created even if no index subtype is a non 697 -- standard enumeration, because we still need to remove padding 698 -- normally inserted for component alignment. 699 700 PAT := 701 Make_Defining_Identifier (Loc, 702 Chars => New_External_Name (Chars (Typ), 'P')); 703 704 declare 705 Indexes : constant List_Id := New_List; 706 Indx : Node_Id; 707 Indx_Typ : Entity_Id; 708 Enum_Case : Boolean; 709 Typedef : Node_Id; 710 711 begin 712 Indx := First_Index (Typ); 713 714 while Present (Indx) loop 715 Indx_Typ := Etype (Indx); 716 717 Enum_Case := Is_Enumeration_Type (Indx_Typ) 718 and then Has_Non_Standard_Rep (Indx_Typ); 719 720 -- Unconstrained case 721 722 if not Is_Constrained (Typ) then 723 if Enum_Case then 724 Indx_Typ := Standard_Natural; 725 end if; 726 727 Append_To (Indexes, New_Occurrence_Of (Indx_Typ, Loc)); 728 729 -- Constrained case 730 731 else 732 if not Enum_Case then 733 Append_To (Indexes, New_Occurrence_Of (Indx_Typ, Loc)); 734 735 else 736 Append_To (Indexes, 737 Make_Subtype_Indication (Loc, 738 Subtype_Mark => 739 New_Occurrence_Of (Standard_Natural, Loc), 740 Constraint => 741 Make_Range_Constraint (Loc, 742 Range_Expression => 743 Make_Range (Loc, 744 Low_Bound => 745 Make_Attribute_Reference (Loc, 746 Prefix => 747 New_Occurrence_Of (Indx_Typ, Loc), 748 Attribute_Name => Name_Pos, 749 Expressions => New_List ( 750 Make_Attribute_Reference (Loc, 751 Prefix => 752 New_Occurrence_Of (Indx_Typ, Loc), 753 Attribute_Name => Name_First))), 754 755 High_Bound => 756 Make_Attribute_Reference (Loc, 757 Prefix => 758 New_Occurrence_Of (Indx_Typ, Loc), 759 Attribute_Name => Name_Pos, 760 Expressions => New_List ( 761 Make_Attribute_Reference (Loc, 762 Prefix => 763 New_Occurrence_Of (Indx_Typ, Loc), 764 Attribute_Name => Name_Last))))))); 765 766 end if; 767 end if; 768 769 Next_Index (Indx); 770 end loop; 771 772 if not Is_Constrained (Typ) then 773 Typedef := 774 Make_Unconstrained_Array_Definition (Loc, 775 Subtype_Marks => Indexes, 776 Component_Definition => 777 Make_Component_Definition (Loc, 778 Aliased_Present => False, 779 Subtype_Indication => 780 New_Occurrence_Of (Ctyp, Loc))); 781 782 else 783 Typedef := 784 Make_Constrained_Array_Definition (Loc, 785 Discrete_Subtype_Definitions => Indexes, 786 Component_Definition => 787 Make_Component_Definition (Loc, 788 Aliased_Present => False, 789 Subtype_Indication => 790 New_Occurrence_Of (Ctyp, Loc))); 791 end if; 792 793 Decl := 794 Make_Full_Type_Declaration (Loc, 795 Defining_Identifier => PAT, 796 Type_Definition => Typedef); 797 end; 798 799 Install_PAT; 800 return; 801 802 -- Case of bit-packing required for unconstrained array. We create 803 -- a subtype that is equivalent to use Packed_Bytes{1,2,4} as needed. 804 805 elsif not Is_Constrained (Typ) then 806 807 -- When generating standard DWARF (i.e when GNAT_Encodings is 808 -- DWARF_GNAT_Encodings_Minimal), the ___XP suffix will be stripped 809 -- by the back-end but generate it anyway to ease compiler debugging. 810 -- This will help to distinguish implementation types from original 811 -- packed arrays. 812 813 PAT := 814 Make_Defining_Identifier (Loc, 815 Chars => Make_Packed_Array_Impl_Type_Name (Typ, Csize)); 816 817 Set_PB_Type; 818 819 Decl := 820 Make_Subtype_Declaration (Loc, 821 Defining_Identifier => PAT, 822 Subtype_Indication => New_Occurrence_Of (PB_Type, Loc)); 823 824 Install_PAT; 825 return; 826 827 -- Remaining code is for the case of bit-packing for constrained array 828 829 -- The name of the packed array subtype is 830 831 -- ttt___XPsss 832 833 -- where sss is the component size in bits and ttt is the name of 834 -- the parent packed type. 835 836 else 837 PAT := 838 Make_Defining_Identifier (Loc, 839 Chars => Make_Packed_Array_Impl_Type_Name (Typ, Csize)); 840 841 -- Build an expression for the length of the array in bits. 842 -- This is the product of the length of each of the dimensions 843 844 Len_Expr := Compute_Number_Components (Typ, Typ); 845 846 -- Temporarily attach the length expression to the tree and analyze 847 -- and resolve it, so that we can test its value. We assume that the 848 -- total length fits in type Integer. This expression may involve 849 -- discriminants, so we treat it as a default/per-object expression. 850 851 Set_Parent (Len_Expr, Typ); 852 Preanalyze_Spec_Expression (Len_Expr, Standard_Long_Long_Integer); 853 854 -- Use a modular type if possible. We can do this if we have 855 -- static bounds, and the length is small enough, and the length 856 -- is not zero. We exclude the zero length case because the size 857 -- of things is always at least one, and the zero length object 858 -- would have an anomalous size. 859 860 if Compile_Time_Known_Value (Len_Expr) then 861 Len_Bits := Expr_Value (Len_Expr) * Csize; 862 863 -- Check for size known to be too large 864 865 if Len_Bits > 866 Uint_2 ** (Standard_Integer_Size - 1) * System_Storage_Unit 867 then 868 if System_Storage_Unit = 8 then 869 Error_Msg_N 870 ("packed array size cannot exceed " & 871 "Integer''Last bytes", Typ); 872 else 873 Error_Msg_N 874 ("packed array size cannot exceed " & 875 "Integer''Last storage units", Typ); 876 end if; 877 878 -- Reset length to arbitrary not too high value to continue 879 880 Len_Expr := Make_Integer_Literal (Loc, 65535); 881 Analyze_And_Resolve (Len_Expr, Standard_Long_Long_Integer); 882 end if; 883 884 -- We normally consider small enough to mean no larger than the 885 -- value of System_Max_Binary_Modulus_Power, checking that in the 886 -- case of values longer than word size, we have long shifts. 887 888 if Len_Bits > 0 889 and then 890 (Len_Bits <= System_Word_Size 891 or else (Len_Bits <= System_Max_Binary_Modulus_Power 892 and then Support_Long_Shifts_On_Target)) 893 then 894 -- We can use the modular type, it has the form: 895 896 -- subtype tttPn is btyp 897 -- range 0 .. 2 ** ((Typ'Length (1) 898 -- * ... * Typ'Length (n)) * Csize) - 1; 899 900 -- The bounds are statically known, and btyp is one of the 901 -- unsigned types, depending on the length. 902 903 if Len_Bits <= Standard_Short_Short_Integer_Size then 904 Btyp := RTE (RE_Short_Short_Unsigned); 905 906 elsif Len_Bits <= Standard_Short_Integer_Size then 907 Btyp := RTE (RE_Short_Unsigned); 908 909 elsif Len_Bits <= Standard_Integer_Size then 910 Btyp := RTE (RE_Unsigned); 911 912 elsif Len_Bits <= Standard_Long_Integer_Size then 913 Btyp := RTE (RE_Long_Unsigned); 914 915 else 916 Btyp := RTE (RE_Long_Long_Unsigned); 917 end if; 918 919 Lit := Make_Integer_Literal (Loc, 2 ** Len_Bits - 1); 920 Set_Print_In_Hex (Lit); 921 922 Decl := 923 Make_Subtype_Declaration (Loc, 924 Defining_Identifier => PAT, 925 Subtype_Indication => 926 Make_Subtype_Indication (Loc, 927 Subtype_Mark => New_Occurrence_Of (Btyp, Loc), 928 929 Constraint => 930 Make_Range_Constraint (Loc, 931 Range_Expression => 932 Make_Range (Loc, 933 Low_Bound => 934 Make_Integer_Literal (Loc, 0), 935 High_Bound => Lit)))); 936 937 if PASize = Uint_0 then 938 PASize := Len_Bits; 939 end if; 940 941 Install_PAT; 942 943 -- Propagate a given alignment to the modular type. This can 944 -- cause it to be under-aligned, but that's OK. 945 946 if Present (Alignment_Clause (Typ)) then 947 Set_Alignment (PAT, Alignment (Typ)); 948 end if; 949 950 return; 951 end if; 952 end if; 953 954 -- Could not use a modular type, for all other cases, we build 955 -- a packed array subtype: 956 957 -- subtype tttPn is 958 -- System.Packed_Bytes{1,2,4} (0 .. (Bits + 7) / 8 - 1); 959 960 -- Bits is the length of the array in bits 961 962 Set_PB_Type; 963 964 Bits_U1 := 965 Make_Op_Add (Loc, 966 Left_Opnd => 967 Make_Op_Multiply (Loc, 968 Left_Opnd => 969 Make_Integer_Literal (Loc, Csize), 970 Right_Opnd => Len_Expr), 971 972 Right_Opnd => 973 Make_Integer_Literal (Loc, 7)); 974 975 Set_Paren_Count (Bits_U1, 1); 976 977 PAT_High := 978 Make_Op_Subtract (Loc, 979 Left_Opnd => 980 Make_Op_Divide (Loc, 981 Left_Opnd => Bits_U1, 982 Right_Opnd => Make_Integer_Literal (Loc, 8)), 983 Right_Opnd => Make_Integer_Literal (Loc, 1)); 984 985 Decl := 986 Make_Subtype_Declaration (Loc, 987 Defining_Identifier => PAT, 988 Subtype_Indication => 989 Make_Subtype_Indication (Loc, 990 Subtype_Mark => New_Occurrence_Of (PB_Type, Loc), 991 Constraint => 992 Make_Index_Or_Discriminant_Constraint (Loc, 993 Constraints => New_List ( 994 Make_Range (Loc, 995 Low_Bound => 996 Make_Integer_Literal (Loc, 0), 997 High_Bound => 998 Convert_To (Standard_Integer, PAT_High)))))); 999 1000 Install_PAT; 1001 1002 -- Currently the code in this unit requires that packed arrays 1003 -- represented by non-modular arrays of bytes be on a byte 1004 -- boundary for bit sizes handled by System.Pack_nn units. 1005 -- That's because these units assume the array being accessed 1006 -- starts on a byte boundary. 1007 1008 if Get_Id (UI_To_Int (Csize)) /= RE_Null then 1009 Set_Must_Be_On_Byte_Boundary (Typ); 1010 end if; 1011 end if; 1012 end Create_Packed_Array_Impl_Type; 1013 1014 ----------------------------------- 1015 -- Expand_Bit_Packed_Element_Set -- 1016 ----------------------------------- 1017 1018 procedure Expand_Bit_Packed_Element_Set (N : Node_Id) is 1019 Loc : constant Source_Ptr := Sloc (N); 1020 Lhs : constant Node_Id := Name (N); 1021 1022 Ass_OK : constant Boolean := Assignment_OK (Lhs); 1023 -- Used to preserve assignment OK status when assignment is rewritten 1024 1025 Expr : Node_Id; 1026 1027 Rhs : Node_Id := Expression (N); 1028 -- Initially Rhs is the right hand side value, it will be replaced 1029 -- later by an appropriate unchecked conversion for the assignment. 1030 1031 Obj : Node_Id; 1032 Atyp : Entity_Id; 1033 PAT : Entity_Id; 1034 Ctyp : Entity_Id; 1035 Csiz : Int; 1036 Cmask : Uint; 1037 1038 Shift : Node_Id; 1039 -- The expression for the shift value that is required 1040 1041 Shift_Used : Boolean := False; 1042 -- Set True if Shift has been used in the generated code at least once, 1043 -- so that it must be duplicated if used again. 1044 1045 New_Lhs : Node_Id; 1046 New_Rhs : Node_Id; 1047 1048 Rhs_Val_Known : Boolean; 1049 Rhs_Val : Uint; 1050 -- If the value of the right hand side as an integer constant is 1051 -- known at compile time, Rhs_Val_Known is set True, and Rhs_Val 1052 -- contains the value. Otherwise Rhs_Val_Known is set False, and 1053 -- the Rhs_Val is undefined. 1054 1055 function Get_Shift return Node_Id; 1056 -- Function used to get the value of Shift, making sure that it 1057 -- gets duplicated if the function is called more than once. 1058 1059 --------------- 1060 -- Get_Shift -- 1061 --------------- 1062 1063 function Get_Shift return Node_Id is 1064 begin 1065 -- If we used the shift value already, then duplicate it. We 1066 -- set a temporary parent in case actions have to be inserted. 1067 1068 if Shift_Used then 1069 Set_Parent (Shift, N); 1070 return Duplicate_Subexpr_No_Checks (Shift); 1071 1072 -- If first time, use Shift unchanged, and set flag for first use 1073 1074 else 1075 Shift_Used := True; 1076 return Shift; 1077 end if; 1078 end Get_Shift; 1079 1080 -- Start of processing for Expand_Bit_Packed_Element_Set 1081 1082 begin 1083 pragma Assert (Is_Bit_Packed_Array (Etype (Prefix (Lhs)))); 1084 1085 Obj := Relocate_Node (Prefix (Lhs)); 1086 Convert_To_Actual_Subtype (Obj); 1087 Atyp := Etype (Obj); 1088 PAT := Packed_Array_Impl_Type (Atyp); 1089 Ctyp := Component_Type (Atyp); 1090 Csiz := UI_To_Int (Component_Size (Atyp)); 1091 1092 -- We remove side effects, in case the rhs modifies the lhs, because we 1093 -- are about to transform the rhs into an expression that first READS 1094 -- the lhs, so we can do the necessary shifting and masking. Example: 1095 -- "X(2) := F(...);" where F modifies X(3). Otherwise, the side effect 1096 -- will be lost. 1097 1098 Remove_Side_Effects (Rhs); 1099 1100 -- We convert the right hand side to the proper subtype to ensure 1101 -- that an appropriate range check is made (since the normal range 1102 -- check from assignment will be lost in the transformations). This 1103 -- conversion is analyzed immediately so that subsequent processing 1104 -- can work with an analyzed Rhs (and e.g. look at its Etype) 1105 1106 -- If the right-hand side is a string literal, create a temporary for 1107 -- it, constant-folding is not ready to wrap the bit representation 1108 -- of a string literal. 1109 1110 if Nkind (Rhs) = N_String_Literal then 1111 declare 1112 Decl : Node_Id; 1113 begin 1114 Decl := 1115 Make_Object_Declaration (Loc, 1116 Defining_Identifier => Make_Temporary (Loc, 'T', Rhs), 1117 Object_Definition => New_Occurrence_Of (Ctyp, Loc), 1118 Expression => New_Copy_Tree (Rhs)); 1119 1120 Insert_Actions (N, New_List (Decl)); 1121 Rhs := New_Occurrence_Of (Defining_Identifier (Decl), Loc); 1122 end; 1123 end if; 1124 1125 Rhs := Convert_To (Ctyp, Rhs); 1126 Set_Parent (Rhs, N); 1127 1128 -- If we are building the initialization procedure for a packed array, 1129 -- and Initialize_Scalars is enabled, each component assignment is an 1130 -- out-of-range value by design. Compile this value without checks, 1131 -- because a call to the array init_proc must not raise an exception. 1132 1133 -- Condition is not consistent with description above, Within_Init_Proc 1134 -- is True also when we are building the IP for a record or protected 1135 -- type that has a packed array component??? 1136 1137 if Within_Init_Proc 1138 and then Initialize_Scalars 1139 then 1140 Analyze_And_Resolve (Rhs, Ctyp, Suppress => All_Checks); 1141 else 1142 Analyze_And_Resolve (Rhs, Ctyp); 1143 end if; 1144 1145 -- If any of the indices has a nonstandard representation, introduce 1146 -- the proper Rep_To_Pos conversion, which in turn will generate index 1147 -- checks when needed. We do this on a copy of the index expression, 1148 -- rather that rewriting the LHS altogether. 1149 1150 Expr := First (Expressions (Lhs)); 1151 while Present (Expr) loop 1152 declare 1153 Expr_Typ : constant Entity_Id := Etype (Expr); 1154 Loc : constant Source_Ptr := Sloc (Expr); 1155 1156 Expr_Copy : Node_Id; 1157 1158 begin 1159 if Is_Enumeration_Type (Expr_Typ) 1160 and then Has_Non_Standard_Rep (Expr_Typ) 1161 then 1162 Expr_Copy := 1163 Make_Attribute_Reference (Loc, 1164 Prefix => New_Occurrence_Of (Expr_Typ, Loc), 1165 Attribute_Name => Name_Pos, 1166 Expressions => New_List (Relocate_Node (Expr))); 1167 Set_Parent (Expr_Copy, N); 1168 Analyze_And_Resolve (Expr_Copy, Standard_Natural); 1169 end if; 1170 end; 1171 1172 Next (Expr); 1173 end loop; 1174 1175 -- Case of component size 1,2,4 or any component size for the modular 1176 -- case. These are the cases for which we can inline the code. 1177 1178 if Csiz = 1 or else Csiz = 2 or else Csiz = 4 1179 or else (Present (PAT) and then Is_Modular_Integer_Type (PAT)) 1180 then 1181 Setup_Inline_Packed_Array_Reference (Lhs, Atyp, Obj, Cmask, Shift); 1182 1183 -- The statement to be generated is: 1184 1185 -- Obj := atyp!((Obj and Mask1) or (shift_left (rhs, Shift))) 1186 1187 -- or in the case of a freestanding Reverse_Storage_Order object, 1188 1189 -- Obj := Swap (atyp!((Swap (Obj) and Mask1) 1190 -- or (shift_left (rhs, Shift)))) 1191 1192 -- where Mask1 is obtained by shifting Cmask left Shift bits 1193 -- and then complementing the result. 1194 1195 -- the "and Mask1" is omitted if rhs is constant and all 1 bits 1196 1197 -- the "or ..." is omitted if rhs is constant and all 0 bits 1198 1199 -- rhs is converted to the appropriate type 1200 1201 -- The result is converted back to the array type, since 1202 -- otherwise we lose knowledge of the packed nature. 1203 1204 -- Determine if right side is all 0 bits or all 1 bits 1205 1206 if Compile_Time_Known_Value (Rhs) then 1207 Rhs_Val := Expr_Rep_Value (Rhs); 1208 Rhs_Val_Known := True; 1209 1210 -- The following test catches the case of an unchecked conversion of 1211 -- an integer literal. This results from optimizing aggregates of 1212 -- packed types. 1213 1214 elsif Nkind (Rhs) = N_Unchecked_Type_Conversion 1215 and then Compile_Time_Known_Value (Expression (Rhs)) 1216 then 1217 Rhs_Val := Expr_Rep_Value (Expression (Rhs)); 1218 Rhs_Val_Known := True; 1219 1220 else 1221 Rhs_Val := No_Uint; 1222 Rhs_Val_Known := False; 1223 end if; 1224 1225 -- Some special checks for the case where the right hand value is 1226 -- known at compile time. Basically we have to take care of the 1227 -- implicit conversion to the subtype of the component object. 1228 1229 if Rhs_Val_Known then 1230 1231 -- If we have a biased component type then we must manually do the 1232 -- biasing, since we are taking responsibility in this case for 1233 -- constructing the exact bit pattern to be used. 1234 1235 if Has_Biased_Representation (Ctyp) then 1236 Rhs_Val := Rhs_Val - Expr_Rep_Value (Type_Low_Bound (Ctyp)); 1237 end if; 1238 1239 -- For a negative value, we manually convert the two's complement 1240 -- value to a corresponding unsigned value, so that the proper 1241 -- field width is maintained. If we did not do this, we would 1242 -- get too many leading sign bits later on. 1243 1244 if Rhs_Val < 0 then 1245 Rhs_Val := 2 ** UI_From_Int (Csiz) + Rhs_Val; 1246 end if; 1247 end if; 1248 1249 -- Now create copies removing side effects. Note that in some complex 1250 -- cases, this may cause the fact that we have already set a packed 1251 -- array type on Obj to get lost. So we save the type of Obj, and 1252 -- make sure it is reset properly. 1253 1254 New_Lhs := Duplicate_Subexpr (Obj, Name_Req => True); 1255 New_Rhs := Duplicate_Subexpr_No_Checks (Obj); 1256 1257 -- First we deal with the "and" 1258 1259 if not Rhs_Val_Known or else Rhs_Val /= Cmask then 1260 declare 1261 Mask1 : Node_Id; 1262 Lit : Node_Id; 1263 1264 begin 1265 if Compile_Time_Known_Value (Shift) then 1266 Mask1 := 1267 Make_Integer_Literal (Loc, 1268 Modulus (Etype (Obj)) - 1 - 1269 (Cmask * (2 ** Expr_Value (Get_Shift)))); 1270 Set_Print_In_Hex (Mask1); 1271 1272 else 1273 Lit := Make_Integer_Literal (Loc, Cmask); 1274 Set_Print_In_Hex (Lit); 1275 Mask1 := 1276 Make_Op_Not (Loc, 1277 Right_Opnd => Make_Shift_Left (Lit, Get_Shift)); 1278 end if; 1279 1280 New_Rhs := 1281 Make_Op_And (Loc, 1282 Left_Opnd => New_Rhs, 1283 Right_Opnd => Mask1); 1284 end; 1285 end if; 1286 1287 -- Then deal with the "or" 1288 1289 if not Rhs_Val_Known or else Rhs_Val /= 0 then 1290 declare 1291 Or_Rhs : Node_Id; 1292 1293 procedure Fixup_Rhs; 1294 -- Adjust Rhs by bias if biased representation for components 1295 -- or remove extraneous high order sign bits if signed. 1296 1297 procedure Fixup_Rhs is 1298 Etyp : constant Entity_Id := Etype (Rhs); 1299 1300 begin 1301 -- For biased case, do the required biasing by simply 1302 -- converting to the biased subtype (the conversion 1303 -- will generate the required bias). 1304 1305 if Has_Biased_Representation (Ctyp) then 1306 Rhs := Convert_To (Ctyp, Rhs); 1307 1308 -- For a signed integer type that is not biased, generate 1309 -- a conversion to unsigned to strip high order sign bits. 1310 1311 elsif Is_Signed_Integer_Type (Ctyp) then 1312 Rhs := Unchecked_Convert_To (RTE (Bits_Id (Csiz)), Rhs); 1313 end if; 1314 1315 -- Set Etype, since it can be referenced before the node is 1316 -- completely analyzed. 1317 1318 Set_Etype (Rhs, Etyp); 1319 1320 -- We now need to do an unchecked conversion of the 1321 -- result to the target type, but it is important that 1322 -- this conversion be a right justified conversion and 1323 -- not a left justified conversion. 1324 1325 Rhs := RJ_Unchecked_Convert_To (Etype (Obj), Rhs); 1326 end Fixup_Rhs; 1327 1328 begin 1329 if Rhs_Val_Known 1330 and then Compile_Time_Known_Value (Get_Shift) 1331 then 1332 Or_Rhs := 1333 Make_Integer_Literal (Loc, 1334 Rhs_Val * (2 ** Expr_Value (Get_Shift))); 1335 Set_Print_In_Hex (Or_Rhs); 1336 1337 else 1338 -- We have to convert the right hand side to Etype (Obj). 1339 -- A special case arises if what we have now is a Val 1340 -- attribute reference whose expression type is Etype (Obj). 1341 -- This happens for assignments of fields from the same 1342 -- array. In this case we get the required right hand side 1343 -- by simply removing the inner attribute reference. 1344 1345 if Nkind (Rhs) = N_Attribute_Reference 1346 and then Attribute_Name (Rhs) = Name_Val 1347 and then Etype (First (Expressions (Rhs))) = Etype (Obj) 1348 then 1349 Rhs := Relocate_Node (First (Expressions (Rhs))); 1350 Fixup_Rhs; 1351 1352 -- If the value of the right hand side is a known integer 1353 -- value, then just replace it by an untyped constant, 1354 -- which will be properly retyped when we analyze and 1355 -- resolve the expression. 1356 1357 elsif Rhs_Val_Known then 1358 1359 -- Note that Rhs_Val has already been normalized to 1360 -- be an unsigned value with the proper number of bits. 1361 1362 Rhs := Make_Integer_Literal (Loc, Rhs_Val); 1363 1364 -- Otherwise we need an unchecked conversion 1365 1366 else 1367 Fixup_Rhs; 1368 end if; 1369 1370 Or_Rhs := Make_Shift_Left (Rhs, Get_Shift); 1371 end if; 1372 1373 if Nkind (New_Rhs) = N_Op_And then 1374 Set_Paren_Count (New_Rhs, 1); 1375 Set_Etype (New_Rhs, Etype (Left_Opnd (New_Rhs))); 1376 end if; 1377 1378 New_Rhs := 1379 Make_Op_Or (Loc, 1380 Left_Opnd => New_Rhs, 1381 Right_Opnd => Or_Rhs); 1382 end; 1383 end if; 1384 1385 -- Now do the rewrite 1386 1387 Rewrite (N, 1388 Make_Assignment_Statement (Loc, 1389 Name => New_Lhs, 1390 Expression => 1391 Unchecked_Convert_To (Etype (New_Lhs), New_Rhs))); 1392 Set_Assignment_OK (Name (N), Ass_OK); 1393 1394 -- All other component sizes for non-modular case 1395 1396 else 1397 -- We generate 1398 1399 -- Set_nn (Arr'address, Subscr, Bits_nn!(Rhs)) 1400 1401 -- where Subscr is the computed linear subscript 1402 1403 declare 1404 Bits_nn : constant Entity_Id := RTE (Bits_Id (Csiz)); 1405 Set_nn : Entity_Id; 1406 Subscr : Node_Id; 1407 Atyp : Entity_Id; 1408 Rev_SSO : Node_Id; 1409 1410 begin 1411 if No (Bits_nn) then 1412 1413 -- Error, most likely High_Integrity_Mode restriction 1414 1415 return; 1416 end if; 1417 1418 -- Acquire proper Set entity. We use the aligned or unaligned 1419 -- case as appropriate. 1420 1421 if Known_Aligned_Enough (Obj, Csiz) then 1422 Set_nn := RTE (Set_Id (Csiz)); 1423 else 1424 Set_nn := RTE (SetU_Id (Csiz)); 1425 end if; 1426 1427 -- Now generate the set reference 1428 1429 Obj := Relocate_Node (Prefix (Lhs)); 1430 Convert_To_Actual_Subtype (Obj); 1431 Atyp := Etype (Obj); 1432 Compute_Linear_Subscript (Atyp, Lhs, Subscr); 1433 1434 -- Set indication of whether the packed array has reverse SSO 1435 1436 Rev_SSO := 1437 New_Occurrence_Of 1438 (Boolean_Literals (Reverse_Storage_Order (Atyp)), Loc); 1439 1440 -- Below we must make the assumption that Obj is 1441 -- at least byte aligned, since otherwise its address 1442 -- cannot be taken. The assumption holds since the 1443 -- only arrays that can be misaligned are small packed 1444 -- arrays which are implemented as a modular type, and 1445 -- that is not the case here. 1446 1447 Rewrite (N, 1448 Make_Procedure_Call_Statement (Loc, 1449 Name => New_Occurrence_Of (Set_nn, Loc), 1450 Parameter_Associations => New_List ( 1451 Make_Attribute_Reference (Loc, 1452 Prefix => Obj, 1453 Attribute_Name => Name_Address), 1454 Subscr, 1455 Unchecked_Convert_To (Bits_nn, Convert_To (Ctyp, Rhs)), 1456 Rev_SSO))); 1457 1458 end; 1459 end if; 1460 1461 Analyze (N, Suppress => All_Checks); 1462 end Expand_Bit_Packed_Element_Set; 1463 1464 ------------------------------------- 1465 -- Expand_Packed_Address_Reference -- 1466 ------------------------------------- 1467 1468 procedure Expand_Packed_Address_Reference (N : Node_Id) is 1469 Loc : constant Source_Ptr := Sloc (N); 1470 Base : Node_Id; 1471 Offset : Node_Id; 1472 1473 begin 1474 -- We build an expression that has the form 1475 1476 -- outer_object'Address 1477 -- + (linear-subscript * component_size for each array reference 1478 -- + field'Bit_Position for each record field 1479 -- + ... 1480 -- + ...) / Storage_Unit; 1481 1482 Get_Base_And_Bit_Offset (Prefix (N), Base, Offset); 1483 1484 Rewrite (N, 1485 Unchecked_Convert_To (RTE (RE_Address), 1486 Make_Op_Add (Loc, 1487 Left_Opnd => 1488 Unchecked_Convert_To (RTE (RE_Integer_Address), 1489 Make_Attribute_Reference (Loc, 1490 Prefix => Base, 1491 Attribute_Name => Name_Address)), 1492 1493 Right_Opnd => 1494 Unchecked_Convert_To (RTE (RE_Integer_Address), 1495 Make_Op_Divide (Loc, 1496 Left_Opnd => Offset, 1497 Right_Opnd => 1498 Make_Integer_Literal (Loc, System_Storage_Unit)))))); 1499 1500 Analyze_And_Resolve (N, RTE (RE_Address)); 1501 end Expand_Packed_Address_Reference; 1502 1503 --------------------------------- 1504 -- Expand_Packed_Bit_Reference -- 1505 --------------------------------- 1506 1507 procedure Expand_Packed_Bit_Reference (N : Node_Id) is 1508 Loc : constant Source_Ptr := Sloc (N); 1509 Base : Node_Id; 1510 Offset : Node_Id; 1511 1512 begin 1513 -- We build an expression that has the form 1514 1515 -- (linear-subscript * component_size for each array reference 1516 -- + field'Bit_Position for each record field 1517 -- + ... 1518 -- + ...) mod Storage_Unit; 1519 1520 Get_Base_And_Bit_Offset (Prefix (N), Base, Offset); 1521 1522 Rewrite (N, 1523 Unchecked_Convert_To (Universal_Integer, 1524 Make_Op_Mod (Loc, 1525 Left_Opnd => Offset, 1526 Right_Opnd => Make_Integer_Literal (Loc, System_Storage_Unit)))); 1527 1528 Analyze_And_Resolve (N, Universal_Integer); 1529 end Expand_Packed_Bit_Reference; 1530 1531 ------------------------------------ 1532 -- Expand_Packed_Boolean_Operator -- 1533 ------------------------------------ 1534 1535 -- This routine expands "a op b" for the packed cases 1536 1537 procedure Expand_Packed_Boolean_Operator (N : Node_Id) is 1538 Loc : constant Source_Ptr := Sloc (N); 1539 Typ : constant Entity_Id := Etype (N); 1540 L : constant Node_Id := Relocate_Node (Left_Opnd (N)); 1541 R : Node_Id := Relocate_Node (Right_Opnd (N)); 1542 1543 Ltyp : Entity_Id; 1544 Rtyp : Entity_Id; 1545 PAT : Entity_Id; 1546 1547 begin 1548 Convert_To_Actual_Subtype (L); 1549 Convert_To_Actual_Subtype (R); 1550 1551 Ensure_Defined (Etype (L), N); 1552 Ensure_Defined (Etype (R), N); 1553 1554 Apply_Length_Check (R, Etype (L)); 1555 1556 Ltyp := Etype (L); 1557 Rtyp := Etype (R); 1558 1559 -- Deal with silly case of XOR where the subcomponent has a range 1560 -- True .. True where an exception must be raised. 1561 1562 if Nkind (N) = N_Op_Xor then 1563 R := Duplicate_Subexpr (R); 1564 Silly_Boolean_Array_Xor_Test (N, R, Rtyp); 1565 end if; 1566 1567 -- Now that silliness is taken care of, get packed array type 1568 1569 Convert_To_PAT_Type (L); 1570 Convert_To_PAT_Type (R); 1571 1572 PAT := Etype (L); 1573 1574 -- For the modular case, we expand a op b into 1575 1576 -- rtyp!(pat!(a) op pat!(b)) 1577 1578 -- where rtyp is the Etype of the left operand. Note that we do not 1579 -- convert to the base type, since this would be unconstrained, and 1580 -- hence not have a corresponding packed array type set. 1581 1582 -- Note that both operands must be modular for this code to be used 1583 1584 if Is_Modular_Integer_Type (PAT) 1585 and then 1586 Is_Modular_Integer_Type (Etype (R)) 1587 then 1588 declare 1589 P : Node_Id; 1590 1591 begin 1592 if Nkind (N) = N_Op_And then 1593 P := Make_Op_And (Loc, L, R); 1594 1595 elsif Nkind (N) = N_Op_Or then 1596 P := Make_Op_Or (Loc, L, R); 1597 1598 else -- Nkind (N) = N_Op_Xor 1599 P := Make_Op_Xor (Loc, L, R); 1600 end if; 1601 1602 Rewrite (N, Unchecked_Convert_To (Ltyp, P)); 1603 end; 1604 1605 -- For the array case, we insert the actions 1606 1607 -- Result : Ltype; 1608 1609 -- System.Bit_Ops.Bit_And/Or/Xor 1610 -- (Left'Address, 1611 -- Ltype'Length * Ltype'Component_Size; 1612 -- Right'Address, 1613 -- Rtype'Length * Rtype'Component_Size 1614 -- Result'Address); 1615 1616 -- where Left and Right are the Packed_Bytes{1,2,4} operands and 1617 -- the second argument and fourth arguments are the lengths of the 1618 -- operands in bits. Then we replace the expression by a reference 1619 -- to Result. 1620 1621 -- Note that if we are mixing a modular and array operand, everything 1622 -- works fine, since we ensure that the modular representation has the 1623 -- same physical layout as the array representation (that's what the 1624 -- left justified modular stuff in the big-endian case is about). 1625 1626 else 1627 declare 1628 Result_Ent : constant Entity_Id := Make_Temporary (Loc, 'T'); 1629 E_Id : RE_Id; 1630 1631 begin 1632 if Nkind (N) = N_Op_And then 1633 E_Id := RE_Bit_And; 1634 1635 elsif Nkind (N) = N_Op_Or then 1636 E_Id := RE_Bit_Or; 1637 1638 else -- Nkind (N) = N_Op_Xor 1639 E_Id := RE_Bit_Xor; 1640 end if; 1641 1642 Insert_Actions (N, New_List ( 1643 1644 Make_Object_Declaration (Loc, 1645 Defining_Identifier => Result_Ent, 1646 Object_Definition => New_Occurrence_Of (Ltyp, Loc)), 1647 1648 Make_Procedure_Call_Statement (Loc, 1649 Name => New_Occurrence_Of (RTE (E_Id), Loc), 1650 Parameter_Associations => New_List ( 1651 1652 Make_Byte_Aligned_Attribute_Reference (Loc, 1653 Prefix => L, 1654 Attribute_Name => Name_Address), 1655 1656 Make_Op_Multiply (Loc, 1657 Left_Opnd => 1658 Make_Attribute_Reference (Loc, 1659 Prefix => 1660 New_Occurrence_Of 1661 (Etype (First_Index (Ltyp)), Loc), 1662 Attribute_Name => Name_Range_Length), 1663 1664 Right_Opnd => 1665 Make_Integer_Literal (Loc, Component_Size (Ltyp))), 1666 1667 Make_Byte_Aligned_Attribute_Reference (Loc, 1668 Prefix => R, 1669 Attribute_Name => Name_Address), 1670 1671 Make_Op_Multiply (Loc, 1672 Left_Opnd => 1673 Make_Attribute_Reference (Loc, 1674 Prefix => 1675 New_Occurrence_Of 1676 (Etype (First_Index (Rtyp)), Loc), 1677 Attribute_Name => Name_Range_Length), 1678 1679 Right_Opnd => 1680 Make_Integer_Literal (Loc, Component_Size (Rtyp))), 1681 1682 Make_Byte_Aligned_Attribute_Reference (Loc, 1683 Prefix => New_Occurrence_Of (Result_Ent, Loc), 1684 Attribute_Name => Name_Address))))); 1685 1686 Rewrite (N, 1687 New_Occurrence_Of (Result_Ent, Loc)); 1688 end; 1689 end if; 1690 1691 Analyze_And_Resolve (N, Typ, Suppress => All_Checks); 1692 end Expand_Packed_Boolean_Operator; 1693 1694 ------------------------------------- 1695 -- Expand_Packed_Element_Reference -- 1696 ------------------------------------- 1697 1698 procedure Expand_Packed_Element_Reference (N : Node_Id) is 1699 Loc : constant Source_Ptr := Sloc (N); 1700 Obj : Node_Id; 1701 Atyp : Entity_Id; 1702 PAT : Entity_Id; 1703 Ctyp : Entity_Id; 1704 Csiz : Int; 1705 Shift : Node_Id; 1706 Cmask : Uint; 1707 Lit : Node_Id; 1708 Arg : Node_Id; 1709 1710 begin 1711 -- If the node is an actual in a call, the prefix has not been fully 1712 -- expanded, to account for the additional expansion for in-out actuals 1713 -- (see expand_actuals for details). If the prefix itself is a packed 1714 -- reference as well, we have to recurse to complete the transformation 1715 -- of the prefix. 1716 1717 if Nkind (Prefix (N)) = N_Indexed_Component 1718 and then not Analyzed (Prefix (N)) 1719 and then Is_Bit_Packed_Array (Etype (Prefix (Prefix (N)))) 1720 then 1721 Expand_Packed_Element_Reference (Prefix (N)); 1722 end if; 1723 1724 -- The prefix may be rewritten below as a conversion. If it is a source 1725 -- entity generate reference to it now, to prevent spurious warnings 1726 -- about unused entities. 1727 1728 if Is_Entity_Name (Prefix (N)) 1729 and then Comes_From_Source (Prefix (N)) 1730 then 1731 Generate_Reference (Entity (Prefix (N)), Prefix (N), 'r'); 1732 end if; 1733 1734 -- If not bit packed, we have the enumeration case, which is easily 1735 -- dealt with (just adjust the subscripts of the indexed component) 1736 1737 -- Note: this leaves the result as an indexed component, which is 1738 -- still a variable, so can be used in the assignment case, as is 1739 -- required in the enumeration case. 1740 1741 if not Is_Bit_Packed_Array (Etype (Prefix (N))) then 1742 Setup_Enumeration_Packed_Array_Reference (N); 1743 return; 1744 end if; 1745 1746 -- Remaining processing is for the bit-packed case 1747 1748 Obj := Relocate_Node (Prefix (N)); 1749 Convert_To_Actual_Subtype (Obj); 1750 Atyp := Etype (Obj); 1751 PAT := Packed_Array_Impl_Type (Atyp); 1752 Ctyp := Component_Type (Atyp); 1753 Csiz := UI_To_Int (Component_Size (Atyp)); 1754 1755 -- Case of component size 1,2,4 or any component size for the modular 1756 -- case. These are the cases for which we can inline the code. 1757 1758 if Csiz = 1 or else Csiz = 2 or else Csiz = 4 1759 or else (Present (PAT) and then Is_Modular_Integer_Type (PAT)) 1760 then 1761 Setup_Inline_Packed_Array_Reference (N, Atyp, Obj, Cmask, Shift); 1762 Lit := Make_Integer_Literal (Loc, Cmask); 1763 Set_Print_In_Hex (Lit); 1764 1765 -- We generate a shift right to position the field, followed by a 1766 -- masking operation to extract the bit field, and we finally do an 1767 -- unchecked conversion to convert the result to the required target. 1768 1769 -- Note that the unchecked conversion automatically deals with the 1770 -- bias if we are dealing with a biased representation. What will 1771 -- happen is that we temporarily generate the biased representation, 1772 -- but almost immediately that will be converted to the original 1773 -- unbiased component type, and the bias will disappear. 1774 1775 Arg := 1776 Make_Op_And (Loc, 1777 Left_Opnd => Make_Shift_Right (Obj, Shift), 1778 Right_Opnd => Lit); 1779 Set_Etype (Arg, Ctyp); 1780 1781 -- Component extraction is performed on a native endianness scalar 1782 -- value: if Atyp has reverse storage order, then it has been byte 1783 -- swapped, and if the component being extracted is itself of a 1784 -- composite type with reverse storage order, then we need to swap 1785 -- it back to its expected endianness after extraction. 1786 1787 if Reverse_Storage_Order (Atyp) 1788 and then (Is_Record_Type (Ctyp) or else Is_Array_Type (Ctyp)) 1789 and then Reverse_Storage_Order (Ctyp) 1790 then 1791 Arg := Revert_Storage_Order (Arg); 1792 end if; 1793 1794 -- We needed to analyze this before we do the unchecked convert 1795 -- below, but we need it temporarily attached to the tree for 1796 -- this analysis (hence the temporary Set_Parent call). 1797 1798 Set_Parent (Arg, Parent (N)); 1799 Analyze_And_Resolve (Arg); 1800 1801 Rewrite (N, RJ_Unchecked_Convert_To (Ctyp, Arg)); 1802 1803 -- All other component sizes for non-modular case 1804 1805 else 1806 -- We generate 1807 1808 -- Component_Type!(Get_nn (Arr'address, Subscr)) 1809 1810 -- where Subscr is the computed linear subscript 1811 1812 declare 1813 Get_nn : Entity_Id; 1814 Subscr : Node_Id; 1815 Rev_SSO : constant Node_Id := 1816 New_Occurrence_Of 1817 (Boolean_Literals (Reverse_Storage_Order (Atyp)), Loc); 1818 1819 begin 1820 -- Acquire proper Get entity. We use the aligned or unaligned 1821 -- case as appropriate. 1822 1823 if Known_Aligned_Enough (Obj, Csiz) then 1824 Get_nn := RTE (Get_Id (Csiz)); 1825 else 1826 Get_nn := RTE (GetU_Id (Csiz)); 1827 end if; 1828 1829 -- Now generate the get reference 1830 1831 Compute_Linear_Subscript (Atyp, N, Subscr); 1832 1833 -- Below we make the assumption that Obj is at least byte 1834 -- aligned, since otherwise its address cannot be taken. 1835 -- The assumption holds since the only arrays that can be 1836 -- misaligned are small packed arrays which are implemented 1837 -- as a modular type, and that is not the case here. 1838 1839 Rewrite (N, 1840 Unchecked_Convert_To (Ctyp, 1841 Make_Function_Call (Loc, 1842 Name => New_Occurrence_Of (Get_nn, Loc), 1843 Parameter_Associations => New_List ( 1844 Make_Attribute_Reference (Loc, 1845 Prefix => Obj, 1846 Attribute_Name => Name_Address), 1847 Subscr, 1848 Rev_SSO)))); 1849 end; 1850 end if; 1851 1852 Analyze_And_Resolve (N, Ctyp, Suppress => All_Checks); 1853 end Expand_Packed_Element_Reference; 1854 1855 ---------------------- 1856 -- Expand_Packed_Eq -- 1857 ---------------------- 1858 1859 -- Handles expansion of "=" on packed array types 1860 1861 procedure Expand_Packed_Eq (N : Node_Id) is 1862 Loc : constant Source_Ptr := Sloc (N); 1863 L : constant Node_Id := Relocate_Node (Left_Opnd (N)); 1864 R : constant Node_Id := Relocate_Node (Right_Opnd (N)); 1865 1866 LLexpr : Node_Id; 1867 RLexpr : Node_Id; 1868 1869 Ltyp : Entity_Id; 1870 Rtyp : Entity_Id; 1871 PAT : Entity_Id; 1872 1873 begin 1874 Convert_To_Actual_Subtype (L); 1875 Convert_To_Actual_Subtype (R); 1876 Ltyp := Underlying_Type (Etype (L)); 1877 Rtyp := Underlying_Type (Etype (R)); 1878 1879 Convert_To_PAT_Type (L); 1880 Convert_To_PAT_Type (R); 1881 PAT := Etype (L); 1882 1883 LLexpr := 1884 Make_Op_Multiply (Loc, 1885 Left_Opnd => Compute_Number_Components (N, Ltyp), 1886 Right_Opnd => Make_Integer_Literal (Loc, Component_Size (Ltyp))); 1887 1888 RLexpr := 1889 Make_Op_Multiply (Loc, 1890 Left_Opnd => Compute_Number_Components (N, Rtyp), 1891 Right_Opnd => Make_Integer_Literal (Loc, Component_Size (Rtyp))); 1892 1893 -- For the modular case, we transform the comparison to: 1894 1895 -- Ltyp'Length = Rtyp'Length and then PAT!(L) = PAT!(R) 1896 1897 -- where PAT is the packed array type. This works fine, since in the 1898 -- modular case we guarantee that the unused bits are always zeroes. 1899 -- We do have to compare the lengths because we could be comparing 1900 -- two different subtypes of the same base type. 1901 1902 if Is_Modular_Integer_Type (PAT) then 1903 Rewrite (N, 1904 Make_And_Then (Loc, 1905 Left_Opnd => 1906 Make_Op_Eq (Loc, 1907 Left_Opnd => LLexpr, 1908 Right_Opnd => RLexpr), 1909 1910 Right_Opnd => 1911 Make_Op_Eq (Loc, 1912 Left_Opnd => L, 1913 Right_Opnd => R))); 1914 1915 -- For the non-modular case, we call a runtime routine 1916 1917 -- System.Bit_Ops.Bit_Eq 1918 -- (L'Address, L_Length, R'Address, R_Length) 1919 1920 -- where PAT is the packed array type, and the lengths are the lengths 1921 -- in bits of the original packed arrays. This routine takes care of 1922 -- not comparing the unused bits in the last byte. 1923 1924 else 1925 Rewrite (N, 1926 Make_Function_Call (Loc, 1927 Name => New_Occurrence_Of (RTE (RE_Bit_Eq), Loc), 1928 Parameter_Associations => New_List ( 1929 Make_Byte_Aligned_Attribute_Reference (Loc, 1930 Prefix => L, 1931 Attribute_Name => Name_Address), 1932 1933 LLexpr, 1934 1935 Make_Byte_Aligned_Attribute_Reference (Loc, 1936 Prefix => R, 1937 Attribute_Name => Name_Address), 1938 1939 RLexpr))); 1940 end if; 1941 1942 Analyze_And_Resolve (N, Standard_Boolean, Suppress => All_Checks); 1943 end Expand_Packed_Eq; 1944 1945 ----------------------- 1946 -- Expand_Packed_Not -- 1947 ----------------------- 1948 1949 -- Handles expansion of "not" on packed array types 1950 1951 procedure Expand_Packed_Not (N : Node_Id) is 1952 Loc : constant Source_Ptr := Sloc (N); 1953 Typ : constant Entity_Id := Etype (N); 1954 Opnd : constant Node_Id := Relocate_Node (Right_Opnd (N)); 1955 1956 Rtyp : Entity_Id; 1957 PAT : Entity_Id; 1958 Lit : Node_Id; 1959 1960 begin 1961 Convert_To_Actual_Subtype (Opnd); 1962 Rtyp := Etype (Opnd); 1963 1964 -- Deal with silly False..False and True..True subtype case 1965 1966 Silly_Boolean_Array_Not_Test (N, Rtyp); 1967 1968 -- Now that the silliness is taken care of, get packed array type 1969 1970 Convert_To_PAT_Type (Opnd); 1971 PAT := Etype (Opnd); 1972 1973 -- For the case where the packed array type is a modular type, "not A" 1974 -- expands simply into: 1975 1976 -- Rtyp!(PAT!(A) xor Mask) 1977 1978 -- where PAT is the packed array type, Mask is a mask of all 1 bits of 1979 -- length equal to the size of this packed type, and Rtyp is the actual 1980 -- actual subtype of the operand. 1981 1982 Lit := Make_Integer_Literal (Loc, 2 ** RM_Size (PAT) - 1); 1983 Set_Print_In_Hex (Lit); 1984 1985 if not Is_Array_Type (PAT) then 1986 Rewrite (N, 1987 Unchecked_Convert_To (Rtyp, 1988 Make_Op_Xor (Loc, 1989 Left_Opnd => Opnd, 1990 Right_Opnd => Lit))); 1991 1992 -- For the array case, we insert the actions 1993 1994 -- Result : Typ; 1995 1996 -- System.Bit_Ops.Bit_Not 1997 -- (Opnd'Address, 1998 -- Typ'Length * Typ'Component_Size, 1999 -- Result'Address); 2000 2001 -- where Opnd is the Packed_Bytes{1,2,4} operand and the second argument 2002 -- is the length of the operand in bits. We then replace the expression 2003 -- with a reference to Result. 2004 2005 else 2006 declare 2007 Result_Ent : constant Entity_Id := Make_Temporary (Loc, 'T'); 2008 2009 begin 2010 Insert_Actions (N, New_List ( 2011 Make_Object_Declaration (Loc, 2012 Defining_Identifier => Result_Ent, 2013 Object_Definition => New_Occurrence_Of (Rtyp, Loc)), 2014 2015 Make_Procedure_Call_Statement (Loc, 2016 Name => New_Occurrence_Of (RTE (RE_Bit_Not), Loc), 2017 Parameter_Associations => New_List ( 2018 Make_Byte_Aligned_Attribute_Reference (Loc, 2019 Prefix => Opnd, 2020 Attribute_Name => Name_Address), 2021 2022 Make_Op_Multiply (Loc, 2023 Left_Opnd => 2024 Make_Attribute_Reference (Loc, 2025 Prefix => 2026 New_Occurrence_Of 2027 (Etype (First_Index (Rtyp)), Loc), 2028 Attribute_Name => Name_Range_Length), 2029 2030 Right_Opnd => 2031 Make_Integer_Literal (Loc, Component_Size (Rtyp))), 2032 2033 Make_Byte_Aligned_Attribute_Reference (Loc, 2034 Prefix => New_Occurrence_Of (Result_Ent, Loc), 2035 Attribute_Name => Name_Address))))); 2036 2037 Rewrite (N, New_Occurrence_Of (Result_Ent, Loc)); 2038 end; 2039 end if; 2040 2041 Analyze_And_Resolve (N, Typ, Suppress => All_Checks); 2042 end Expand_Packed_Not; 2043 2044 ----------------------------- 2045 -- Get_Base_And_Bit_Offset -- 2046 ----------------------------- 2047 2048 procedure Get_Base_And_Bit_Offset 2049 (N : Node_Id; 2050 Base : out Node_Id; 2051 Offset : out Node_Id) 2052 is 2053 Loc : Source_Ptr; 2054 Term : Node_Id; 2055 Atyp : Entity_Id; 2056 Subscr : Node_Id; 2057 2058 begin 2059 Base := N; 2060 Offset := Empty; 2061 2062 -- We build up an expression serially that has the form 2063 2064 -- linear-subscript * component_size for each array reference 2065 -- + field'Bit_Position for each record field 2066 -- + ... 2067 2068 loop 2069 Loc := Sloc (Base); 2070 2071 if Nkind (Base) = N_Indexed_Component then 2072 Convert_To_Actual_Subtype (Prefix (Base)); 2073 Atyp := Etype (Prefix (Base)); 2074 Compute_Linear_Subscript (Atyp, Base, Subscr); 2075 2076 Term := 2077 Make_Op_Multiply (Loc, 2078 Left_Opnd => Subscr, 2079 Right_Opnd => 2080 Make_Attribute_Reference (Loc, 2081 Prefix => New_Occurrence_Of (Atyp, Loc), 2082 Attribute_Name => Name_Component_Size)); 2083 2084 elsif Nkind (Base) = N_Selected_Component then 2085 Term := 2086 Make_Attribute_Reference (Loc, 2087 Prefix => Selector_Name (Base), 2088 Attribute_Name => Name_Bit_Position); 2089 2090 else 2091 return; 2092 end if; 2093 2094 if No (Offset) then 2095 Offset := Term; 2096 2097 else 2098 Offset := 2099 Make_Op_Add (Loc, 2100 Left_Opnd => Offset, 2101 Right_Opnd => Term); 2102 end if; 2103 2104 Base := Prefix (Base); 2105 end loop; 2106 end Get_Base_And_Bit_Offset; 2107 2108 ------------------------------------- 2109 -- Involves_Packed_Array_Reference -- 2110 ------------------------------------- 2111 2112 function Involves_Packed_Array_Reference (N : Node_Id) return Boolean is 2113 begin 2114 if Nkind (N) = N_Indexed_Component 2115 and then Is_Bit_Packed_Array (Etype (Prefix (N))) 2116 then 2117 return True; 2118 2119 elsif Nkind (N) = N_Selected_Component then 2120 return Involves_Packed_Array_Reference (Prefix (N)); 2121 2122 else 2123 return False; 2124 end if; 2125 end Involves_Packed_Array_Reference; 2126 2127 -------------------------- 2128 -- Known_Aligned_Enough -- 2129 -------------------------- 2130 2131 function Known_Aligned_Enough (Obj : Node_Id; Csiz : Nat) return Boolean is 2132 Typ : constant Entity_Id := Etype (Obj); 2133 2134 function In_Partially_Packed_Record (Comp : Entity_Id) return Boolean; 2135 -- If the component is in a record that contains previous packed 2136 -- components, consider it unaligned because the back-end might 2137 -- choose to pack the rest of the record. Lead to less efficient code, 2138 -- but safer vis-a-vis of back-end choices. 2139 2140 -------------------------------- 2141 -- In_Partially_Packed_Record -- 2142 -------------------------------- 2143 2144 function In_Partially_Packed_Record (Comp : Entity_Id) return Boolean is 2145 Rec_Type : constant Entity_Id := Scope (Comp); 2146 Prev_Comp : Entity_Id; 2147 2148 begin 2149 Prev_Comp := First_Entity (Rec_Type); 2150 while Present (Prev_Comp) loop 2151 if Is_Packed (Etype (Prev_Comp)) then 2152 return True; 2153 2154 elsif Prev_Comp = Comp then 2155 return False; 2156 end if; 2157 2158 Next_Entity (Prev_Comp); 2159 end loop; 2160 2161 return False; 2162 end In_Partially_Packed_Record; 2163 2164 -- Start of processing for Known_Aligned_Enough 2165 2166 begin 2167 -- Odd bit sizes don't need alignment anyway 2168 2169 if Csiz mod 2 = 1 then 2170 return True; 2171 2172 -- If we have a specified alignment, see if it is sufficient, if not 2173 -- then we can't possibly be aligned enough in any case. 2174 2175 elsif Known_Alignment (Etype (Obj)) then 2176 -- Alignment required is 4 if size is a multiple of 4, and 2177 -- 2 otherwise (e.g. 12 bits requires 4, 10 bits requires 2) 2178 2179 if Alignment (Etype (Obj)) < 4 - (Csiz mod 4) then 2180 return False; 2181 end if; 2182 end if; 2183 2184 -- OK, alignment should be sufficient, if object is aligned 2185 2186 -- If object is strictly aligned, then it is definitely aligned 2187 2188 if Strict_Alignment (Typ) then 2189 return True; 2190 2191 -- Case of subscripted array reference 2192 2193 elsif Nkind (Obj) = N_Indexed_Component then 2194 2195 -- If we have a pointer to an array, then this is definitely 2196 -- aligned, because pointers always point to aligned versions. 2197 2198 if Is_Access_Type (Etype (Prefix (Obj))) then 2199 return True; 2200 2201 -- Otherwise, go look at the prefix 2202 2203 else 2204 return Known_Aligned_Enough (Prefix (Obj), Csiz); 2205 end if; 2206 2207 -- Case of record field 2208 2209 elsif Nkind (Obj) = N_Selected_Component then 2210 2211 -- What is significant here is whether the record type is packed 2212 2213 if Is_Record_Type (Etype (Prefix (Obj))) 2214 and then Is_Packed (Etype (Prefix (Obj))) 2215 then 2216 return False; 2217 2218 -- Or the component has a component clause which might cause 2219 -- the component to become unaligned (we can't tell if the 2220 -- backend is doing alignment computations). 2221 2222 elsif Present (Component_Clause (Entity (Selector_Name (Obj)))) then 2223 return False; 2224 2225 elsif In_Partially_Packed_Record (Entity (Selector_Name (Obj))) then 2226 return False; 2227 2228 -- In all other cases, go look at prefix 2229 2230 else 2231 return Known_Aligned_Enough (Prefix (Obj), Csiz); 2232 end if; 2233 2234 elsif Nkind (Obj) = N_Type_Conversion then 2235 return Known_Aligned_Enough (Expression (Obj), Csiz); 2236 2237 -- For a formal parameter, it is safer to assume that it is not 2238 -- aligned, because the formal may be unconstrained while the actual 2239 -- is constrained. In this situation, a small constrained packed 2240 -- array, represented in modular form, may be unaligned. 2241 2242 elsif Is_Entity_Name (Obj) then 2243 return not Is_Formal (Entity (Obj)); 2244 else 2245 2246 -- If none of the above, must be aligned 2247 return True; 2248 end if; 2249 end Known_Aligned_Enough; 2250 2251 --------------------- 2252 -- Make_Shift_Left -- 2253 --------------------- 2254 2255 function Make_Shift_Left (N : Node_Id; S : Node_Id) return Node_Id is 2256 Nod : Node_Id; 2257 2258 begin 2259 if Compile_Time_Known_Value (S) and then Expr_Value (S) = 0 then 2260 return N; 2261 else 2262 Nod := 2263 Make_Op_Shift_Left (Sloc (N), 2264 Left_Opnd => N, 2265 Right_Opnd => S); 2266 Set_Shift_Count_OK (Nod, True); 2267 return Nod; 2268 end if; 2269 end Make_Shift_Left; 2270 2271 ---------------------- 2272 -- Make_Shift_Right -- 2273 ---------------------- 2274 2275 function Make_Shift_Right (N : Node_Id; S : Node_Id) return Node_Id is 2276 Nod : Node_Id; 2277 2278 begin 2279 if Compile_Time_Known_Value (S) and then Expr_Value (S) = 0 then 2280 return N; 2281 else 2282 Nod := 2283 Make_Op_Shift_Right (Sloc (N), 2284 Left_Opnd => N, 2285 Right_Opnd => S); 2286 Set_Shift_Count_OK (Nod, True); 2287 return Nod; 2288 end if; 2289 end Make_Shift_Right; 2290 2291 ----------------------------- 2292 -- RJ_Unchecked_Convert_To -- 2293 ----------------------------- 2294 2295 function RJ_Unchecked_Convert_To 2296 (Typ : Entity_Id; 2297 Expr : Node_Id) return Node_Id 2298 is 2299 Source_Typ : constant Entity_Id := Etype (Expr); 2300 Target_Typ : constant Entity_Id := Typ; 2301 2302 Src : Node_Id := Expr; 2303 2304 Source_Siz : Nat; 2305 Target_Siz : Nat; 2306 2307 begin 2308 Source_Siz := UI_To_Int (RM_Size (Source_Typ)); 2309 Target_Siz := UI_To_Int (RM_Size (Target_Typ)); 2310 2311 -- For a little-endian target type stored byte-swapped on a 2312 -- big-endian machine, do not mask to Target_Siz bits. 2313 2314 if Bytes_Big_Endian 2315 and then (Is_Record_Type (Target_Typ) 2316 or else 2317 Is_Array_Type (Target_Typ)) 2318 and then Reverse_Storage_Order (Target_Typ) 2319 then 2320 Source_Siz := Target_Siz; 2321 end if; 2322 2323 -- First step, if the source type is not a discrete type, then we first 2324 -- convert to a modular type of the source length, since otherwise, on 2325 -- a big-endian machine, we get left-justification. We do it for little- 2326 -- endian machines as well, because there might be junk bits that are 2327 -- not cleared if the type is not numeric. This can be done only if the 2328 -- source siz is different from 0 (i.e. known), otherwise we must trust 2329 -- the type declarations (case of non-discrete components). 2330 2331 if Source_Siz /= 0 2332 and then Source_Siz /= Target_Siz 2333 and then not Is_Discrete_Type (Source_Typ) 2334 then 2335 Src := Unchecked_Convert_To (RTE (Bits_Id (Source_Siz)), Src); 2336 end if; 2337 2338 -- In the big endian case, if the lengths of the two types differ, then 2339 -- we must worry about possible left justification in the conversion, 2340 -- and avoiding that is what this is all about. 2341 2342 if Bytes_Big_Endian and then Source_Siz /= Target_Siz then 2343 2344 -- Next step. If the target is not a discrete type, then we first 2345 -- convert to a modular type of the target length, since otherwise, 2346 -- on a big-endian machine, we get left-justification. 2347 2348 if not Is_Discrete_Type (Target_Typ) then 2349 Src := Unchecked_Convert_To (RTE (Bits_Id (Target_Siz)), Src); 2350 end if; 2351 end if; 2352 2353 -- And now we can do the final conversion to the target type 2354 2355 return Unchecked_Convert_To (Target_Typ, Src); 2356 end RJ_Unchecked_Convert_To; 2357 2358 ---------------------------------------------- 2359 -- Setup_Enumeration_Packed_Array_Reference -- 2360 ---------------------------------------------- 2361 2362 -- All we have to do here is to find the subscripts that correspond to the 2363 -- index positions that have non-standard enumeration types and insert a 2364 -- Pos attribute to get the proper subscript value. 2365 2366 -- Finally the prefix must be uncheck-converted to the corresponding packed 2367 -- array type. 2368 2369 -- Note that the component type is unchanged, so we do not need to fiddle 2370 -- with the types (Gigi always automatically takes the packed array type if 2371 -- it is set, as it will be in this case). 2372 2373 procedure Setup_Enumeration_Packed_Array_Reference (N : Node_Id) is 2374 Pfx : constant Node_Id := Prefix (N); 2375 Typ : constant Entity_Id := Etype (N); 2376 Exprs : constant List_Id := Expressions (N); 2377 Expr : Node_Id; 2378 2379 begin 2380 -- If the array is unconstrained, then we replace the array reference 2381 -- with its actual subtype. This actual subtype will have a packed array 2382 -- type with appropriate bounds. 2383 2384 if not Is_Constrained (Packed_Array_Impl_Type (Etype (Pfx))) then 2385 Convert_To_Actual_Subtype (Pfx); 2386 end if; 2387 2388 Expr := First (Exprs); 2389 while Present (Expr) loop 2390 declare 2391 Loc : constant Source_Ptr := Sloc (Expr); 2392 Expr_Typ : constant Entity_Id := Etype (Expr); 2393 2394 begin 2395 if Is_Enumeration_Type (Expr_Typ) 2396 and then Has_Non_Standard_Rep (Expr_Typ) 2397 then 2398 Rewrite (Expr, 2399 Make_Attribute_Reference (Loc, 2400 Prefix => New_Occurrence_Of (Expr_Typ, Loc), 2401 Attribute_Name => Name_Pos, 2402 Expressions => New_List (Relocate_Node (Expr)))); 2403 Analyze_And_Resolve (Expr, Standard_Natural); 2404 end if; 2405 end; 2406 2407 Next (Expr); 2408 end loop; 2409 2410 Rewrite (N, 2411 Make_Indexed_Component (Sloc (N), 2412 Prefix => 2413 Unchecked_Convert_To (Packed_Array_Impl_Type (Etype (Pfx)), Pfx), 2414 Expressions => Exprs)); 2415 2416 Analyze_And_Resolve (N, Typ); 2417 end Setup_Enumeration_Packed_Array_Reference; 2418 2419 ----------------------------------------- 2420 -- Setup_Inline_Packed_Array_Reference -- 2421 ----------------------------------------- 2422 2423 procedure Setup_Inline_Packed_Array_Reference 2424 (N : Node_Id; 2425 Atyp : Entity_Id; 2426 Obj : in out Node_Id; 2427 Cmask : out Uint; 2428 Shift : out Node_Id) 2429 is 2430 Loc : constant Source_Ptr := Sloc (N); 2431 PAT : Entity_Id; 2432 Otyp : Entity_Id; 2433 Csiz : Uint; 2434 Osiz : Uint; 2435 2436 begin 2437 Csiz := Component_Size (Atyp); 2438 2439 Convert_To_PAT_Type (Obj); 2440 PAT := Etype (Obj); 2441 2442 Cmask := 2 ** Csiz - 1; 2443 2444 if Is_Array_Type (PAT) then 2445 Otyp := Component_Type (PAT); 2446 Osiz := Component_Size (PAT); 2447 2448 else 2449 Otyp := PAT; 2450 2451 -- In the case where the PAT is a modular type, we want the actual 2452 -- size in bits of the modular value we use. This is neither the 2453 -- Object_Size nor the Value_Size, either of which may have been 2454 -- reset to strange values, but rather the minimum size. Note that 2455 -- since this is a modular type with full range, the issue of 2456 -- biased representation does not arise. 2457 2458 Osiz := UI_From_Int (Minimum_Size (Otyp)); 2459 end if; 2460 2461 Compute_Linear_Subscript (Atyp, N, Shift); 2462 2463 -- If the component size is not 1, then the subscript must be multiplied 2464 -- by the component size to get the shift count. 2465 2466 if Csiz /= 1 then 2467 Shift := 2468 Make_Op_Multiply (Loc, 2469 Left_Opnd => Make_Integer_Literal (Loc, Csiz), 2470 Right_Opnd => Shift); 2471 end if; 2472 2473 -- If we have the array case, then this shift count must be broken down 2474 -- into a byte subscript, and a shift within the byte. 2475 2476 if Is_Array_Type (PAT) then 2477 2478 declare 2479 New_Shift : Node_Id; 2480 2481 begin 2482 -- We must analyze shift, since we will duplicate it 2483 2484 Set_Parent (Shift, N); 2485 Analyze_And_Resolve 2486 (Shift, Standard_Integer, Suppress => All_Checks); 2487 2488 -- The shift count within the word is 2489 -- shift mod Osiz 2490 2491 New_Shift := 2492 Make_Op_Mod (Loc, 2493 Left_Opnd => Duplicate_Subexpr (Shift), 2494 Right_Opnd => Make_Integer_Literal (Loc, Osiz)); 2495 2496 -- The subscript to be used on the PAT array is 2497 -- shift / Osiz 2498 2499 Obj := 2500 Make_Indexed_Component (Loc, 2501 Prefix => Obj, 2502 Expressions => New_List ( 2503 Make_Op_Divide (Loc, 2504 Left_Opnd => Duplicate_Subexpr (Shift), 2505 Right_Opnd => Make_Integer_Literal (Loc, Osiz)))); 2506 2507 Shift := New_Shift; 2508 end; 2509 2510 -- For the modular integer case, the object to be manipulated is the 2511 -- entire array, so Obj is unchanged. Note that we will reset its type 2512 -- to PAT before returning to the caller. 2513 2514 else 2515 null; 2516 end if; 2517 2518 -- The one remaining step is to modify the shift count for the 2519 -- big-endian case. Consider the following example in a byte: 2520 2521 -- xxxxxxxx bits of byte 2522 -- vvvvvvvv bits of value 2523 -- 33221100 little-endian numbering 2524 -- 00112233 big-endian numbering 2525 2526 -- Here we have the case of 2-bit fields 2527 2528 -- For the little-endian case, we already have the proper shift count 2529 -- set, e.g. for element 2, the shift count is 2*2 = 4. 2530 2531 -- For the big endian case, we have to adjust the shift count, computing 2532 -- it as (N - F) - Shift, where N is the number of bits in an element of 2533 -- the array used to implement the packed array, F is the number of bits 2534 -- in a source array element, and Shift is the count so far computed. 2535 2536 -- We also have to adjust if the storage order is reversed 2537 2538 if Bytes_Big_Endian xor Reverse_Storage_Order (Base_Type (Atyp)) then 2539 Shift := 2540 Make_Op_Subtract (Loc, 2541 Left_Opnd => Make_Integer_Literal (Loc, Osiz - Csiz), 2542 Right_Opnd => Shift); 2543 end if; 2544 2545 Set_Parent (Shift, N); 2546 Set_Parent (Obj, N); 2547 Analyze_And_Resolve (Obj, Otyp, Suppress => All_Checks); 2548 Analyze_And_Resolve (Shift, Standard_Integer, Suppress => All_Checks); 2549 2550 -- Make sure final type of object is the appropriate packed type 2551 2552 Set_Etype (Obj, Otyp); 2553 2554 end Setup_Inline_Packed_Array_Reference; 2555 2556end Exp_Pakd; 2557