1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- E X P _ P A K D -- 6-- -- 7-- B o d y -- 8-- -- 9-- Copyright (C) 1992-2014, Free Software Foundation, Inc. -- 10-- -- 11-- GNAT is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 3, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- 17-- for more details. You should have received a copy of the GNU General -- 18-- Public License distributed with GNAT; see file COPYING3. If not, go to -- 19-- http://www.gnu.org/licenses for a complete copy of the license. -- 20-- -- 21-- GNAT was originally developed by the GNAT team at New York University. -- 22-- Extensive contributions were provided by Ada Core Technologies Inc. -- 23-- -- 24------------------------------------------------------------------------------ 25 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 procedure Convert_To_PAT_Type (Aexp : Node_Id); 94 -- Given an expression of a packed array type, builds a corresponding 95 -- expression whose type is the implementation type used to represent 96 -- the packed array. Aexp is analyzed and resolved on entry and on exit. 97 98 procedure Get_Base_And_Bit_Offset 99 (N : Node_Id; 100 Base : out Node_Id; 101 Offset : out Node_Id); 102 -- Given a node N for a name which involves a packed array reference, 103 -- return the base object of the reference and build an expression of 104 -- type Standard.Integer representing the zero-based offset in bits 105 -- from Base'Address to the first bit of the reference. 106 107 function Known_Aligned_Enough (Obj : Node_Id; Csiz : Nat) return Boolean; 108 -- There are two versions of the Set routines, the ones used when the 109 -- object is known to be sufficiently well aligned given the number of 110 -- bits, and the ones used when the object is not known to be aligned. 111 -- This routine is used to determine which set to use. Obj is a reference 112 -- to the object, and Csiz is the component size of the packed array. 113 -- True is returned if the alignment of object is known to be sufficient, 114 -- defined as 1 for odd bit sizes, 4 for bit sizes divisible by 4, and 115 -- 2 otherwise. 116 117 function Make_Shift_Left (N : Node_Id; S : Node_Id) return Node_Id; 118 -- Build a left shift node, checking for the case of a shift count of zero 119 120 function Make_Shift_Right (N : Node_Id; S : Node_Id) return Node_Id; 121 -- Build a right shift node, checking for the case of a shift count of zero 122 123 function RJ_Unchecked_Convert_To 124 (Typ : Entity_Id; 125 Expr : Node_Id) return Node_Id; 126 -- The packed array code does unchecked conversions which in some cases 127 -- may involve non-discrete types with differing sizes. The semantics of 128 -- such conversions is potentially endianness dependent, and the effect 129 -- we want here for such a conversion is to do the conversion in size as 130 -- though numeric items are involved, and we extend or truncate on the 131 -- left side. This happens naturally in the little-endian case, but in 132 -- the big endian case we can get left justification, when what we want 133 -- is right justification. This routine does the unchecked conversion in 134 -- a stepwise manner to ensure that it gives the expected result. Hence 135 -- the name (RJ = Right justified). The parameters Typ and Expr are as 136 -- for the case of a normal Unchecked_Convert_To call. 137 138 procedure Setup_Enumeration_Packed_Array_Reference (N : Node_Id); 139 -- This routine is called in the Get and Set case for arrays that are 140 -- packed but not bit-packed, meaning that they have at least one 141 -- subscript that is of an enumeration type with a non-standard 142 -- representation. This routine modifies the given node to properly 143 -- reference the corresponding packed array type. 144 145 procedure Setup_Inline_Packed_Array_Reference 146 (N : Node_Id; 147 Atyp : Entity_Id; 148 Obj : in out Node_Id; 149 Cmask : out Uint; 150 Shift : out Node_Id); 151 -- This procedure performs common processing on the N_Indexed_Component 152 -- parameter given as N, whose prefix is a reference to a packed array. 153 -- This is used for the get and set when the component size is 1, 2, 4, 154 -- or for other component sizes when the packed array type is a modular 155 -- type (i.e. the cases that are handled with inline code). 156 -- 157 -- On entry: 158 -- 159 -- N is the N_Indexed_Component node for the packed array reference 160 -- 161 -- Atyp is the constrained array type (the actual subtype has been 162 -- computed if necessary to obtain the constraints, but this is still 163 -- the original array type, not the Packed_Array_Impl_Type value). 164 -- 165 -- Obj is the object which is to be indexed. It is always of type Atyp. 166 -- 167 -- On return: 168 -- 169 -- Obj is the object containing the desired bit field. It is of type 170 -- Unsigned, Long_Unsigned, or Long_Long_Unsigned, and is either the 171 -- entire value, for the small static case, or the proper selected byte 172 -- from the array in the large or dynamic case. This node is analyzed 173 -- and resolved on return. 174 -- 175 -- Shift is a node representing the shift count to be used in the 176 -- rotate right instruction that positions the field for access. 177 -- This node is analyzed and resolved on return. 178 -- 179 -- Cmask is a mask corresponding to the width of the component field. 180 -- Its value is 2 ** Csize - 1 (e.g. 2#1111# for component size of 4). 181 -- 182 -- Note: in some cases the call to this routine may generate actions 183 -- (for handling multi-use references and the generation of the packed 184 -- array type on the fly). Such actions are inserted into the tree 185 -- directly using Insert_Action. 186 187 function Revert_Storage_Order (N : Node_Id) return Node_Id; 188 -- Perform appropriate justification and byte ordering adjustments for N, 189 -- an element of a packed array type, when both the component type and 190 -- the enclosing packed array type have reverse scalar storage order. 191 -- On little-endian targets, the value is left justified before byte 192 -- swapping. The Etype of the returned expression is an integer type of 193 -- an appropriate power-of-2 size. 194 195 -------------------------- 196 -- Revert_Storage_Order -- 197 -------------------------- 198 199 function Revert_Storage_Order (N : Node_Id) return Node_Id is 200 Loc : constant Source_Ptr := Sloc (N); 201 T : constant Entity_Id := Etype (N); 202 T_Size : constant Uint := RM_Size (T); 203 204 Swap_RE : RE_Id; 205 Swap_F : Entity_Id; 206 Swap_T : Entity_Id; 207 -- Swapping function 208 209 Arg : Node_Id; 210 Adjusted : Node_Id; 211 Shift : Uint; 212 213 begin 214 if T_Size <= 8 then 215 216 -- Array component size is less than a byte: no swapping needed 217 218 Swap_F := Empty; 219 Swap_T := RTE (RE_Unsigned_8); 220 221 else 222 -- Select byte swapping function depending on array component size 223 224 if T_Size <= 16 then 225 Swap_RE := RE_Bswap_16; 226 227 elsif T_Size <= 32 then 228 Swap_RE := RE_Bswap_32; 229 230 else pragma Assert (T_Size <= 64); 231 Swap_RE := RE_Bswap_64; 232 end if; 233 234 Swap_F := RTE (Swap_RE); 235 Swap_T := Etype (Swap_F); 236 237 end if; 238 239 Shift := Esize (Swap_T) - T_Size; 240 241 Arg := RJ_Unchecked_Convert_To (Swap_T, N); 242 243 if not Bytes_Big_Endian and then Shift > Uint_0 then 244 Arg := 245 Make_Op_Shift_Left (Loc, 246 Left_Opnd => Arg, 247 Right_Opnd => Make_Integer_Literal (Loc, Shift)); 248 end if; 249 250 if Present (Swap_F) then 251 Adjusted := 252 Make_Function_Call (Loc, 253 Name => New_Occurrence_Of (Swap_F, Loc), 254 Parameter_Associations => New_List (Arg)); 255 else 256 Adjusted := Arg; 257 end if; 258 259 Set_Etype (Adjusted, Swap_T); 260 return Adjusted; 261 end Revert_Storage_Order; 262 263 ------------------------------ 264 -- Compute_Linear_Subscript -- 265 ------------------------------ 266 267 procedure Compute_Linear_Subscript 268 (Atyp : Entity_Id; 269 N : Node_Id; 270 Subscr : out Node_Id) 271 is 272 Loc : constant Source_Ptr := Sloc (N); 273 Oldsub : Node_Id; 274 Newsub : Node_Id; 275 Indx : Node_Id; 276 Styp : Entity_Id; 277 278 begin 279 Subscr := Empty; 280 281 -- Loop through dimensions 282 283 Indx := First_Index (Atyp); 284 Oldsub := First (Expressions (N)); 285 286 while Present (Indx) loop 287 Styp := Etype (Indx); 288 Newsub := Relocate_Node (Oldsub); 289 290 -- Get expression for the subscript value. First, if Do_Range_Check 291 -- is set on a subscript, then we must do a range check against the 292 -- original bounds (not the bounds of the packed array type). We do 293 -- this by introducing a subtype conversion. 294 295 if Do_Range_Check (Newsub) 296 and then Etype (Newsub) /= Styp 297 then 298 Newsub := Convert_To (Styp, Newsub); 299 end if; 300 301 -- Now evolve the expression for the subscript. First convert 302 -- the subscript to be zero based and of an integer type. 303 304 -- Case of integer type, where we just subtract to get lower bound 305 306 if Is_Integer_Type (Styp) then 307 308 -- If length of integer type is smaller than standard integer, 309 -- then we convert to integer first, then do the subtract 310 311 -- Integer (subscript) - Integer (Styp'First) 312 313 if Esize (Styp) < Esize (Standard_Integer) then 314 Newsub := 315 Make_Op_Subtract (Loc, 316 Left_Opnd => Convert_To (Standard_Integer, Newsub), 317 Right_Opnd => 318 Convert_To (Standard_Integer, 319 Make_Attribute_Reference (Loc, 320 Prefix => New_Occurrence_Of (Styp, Loc), 321 Attribute_Name => Name_First))); 322 323 -- For larger integer types, subtract first, then convert to 324 -- integer, this deals with strange long long integer bounds. 325 326 -- Integer (subscript - Styp'First) 327 328 else 329 Newsub := 330 Convert_To (Standard_Integer, 331 Make_Op_Subtract (Loc, 332 Left_Opnd => Newsub, 333 Right_Opnd => 334 Make_Attribute_Reference (Loc, 335 Prefix => New_Occurrence_Of (Styp, Loc), 336 Attribute_Name => Name_First))); 337 end if; 338 339 -- For the enumeration case, we have to use 'Pos to get the value 340 -- to work with before subtracting the lower bound. 341 342 -- Integer (Styp'Pos (subscr)) - Integer (Styp'Pos (Styp'First)); 343 344 -- This is not quite right for bizarre cases where the size of the 345 -- enumeration type is > Integer'Size bits due to rep clause ??? 346 347 else 348 pragma Assert (Is_Enumeration_Type (Styp)); 349 350 Newsub := 351 Make_Op_Subtract (Loc, 352 Left_Opnd => Convert_To (Standard_Integer, 353 Make_Attribute_Reference (Loc, 354 Prefix => New_Occurrence_Of (Styp, Loc), 355 Attribute_Name => Name_Pos, 356 Expressions => New_List (Newsub))), 357 358 Right_Opnd => 359 Convert_To (Standard_Integer, 360 Make_Attribute_Reference (Loc, 361 Prefix => New_Occurrence_Of (Styp, Loc), 362 Attribute_Name => Name_Pos, 363 Expressions => New_List ( 364 Make_Attribute_Reference (Loc, 365 Prefix => New_Occurrence_Of (Styp, Loc), 366 Attribute_Name => Name_First))))); 367 end if; 368 369 Set_Paren_Count (Newsub, 1); 370 371 -- For the first subscript, we just copy that subscript value 372 373 if No (Subscr) then 374 Subscr := Newsub; 375 376 -- Otherwise, we must multiply what we already have by the current 377 -- stride and then add in the new value to the evolving subscript. 378 379 else 380 Subscr := 381 Make_Op_Add (Loc, 382 Left_Opnd => 383 Make_Op_Multiply (Loc, 384 Left_Opnd => Subscr, 385 Right_Opnd => 386 Make_Attribute_Reference (Loc, 387 Attribute_Name => Name_Range_Length, 388 Prefix => New_Occurrence_Of (Styp, Loc))), 389 Right_Opnd => Newsub); 390 end if; 391 392 -- Move to next subscript 393 394 Next_Index (Indx); 395 Next (Oldsub); 396 end loop; 397 end Compute_Linear_Subscript; 398 399 ------------------------- 400 -- Convert_To_PAT_Type -- 401 ------------------------- 402 403 -- The PAT is always obtained from the actual subtype 404 405 procedure Convert_To_PAT_Type (Aexp : Node_Id) is 406 Act_ST : Entity_Id; 407 408 begin 409 Convert_To_Actual_Subtype (Aexp); 410 Act_ST := Underlying_Type (Etype (Aexp)); 411 Create_Packed_Array_Impl_Type (Act_ST); 412 413 -- Just replace the etype with the packed array type. This works because 414 -- the expression will not be further analyzed, and Gigi considers the 415 -- two types equivalent in any case. 416 417 -- This is not strictly the case ??? If the reference is an actual in 418 -- call, the expansion of the prefix is delayed, and must be reanalyzed, 419 -- see Reset_Packed_Prefix. On the other hand, if the prefix is a simple 420 -- array reference, reanalysis can produce spurious type errors when the 421 -- PAT type is replaced again with the original type of the array. Same 422 -- for the case of a dereference. Ditto for function calls: expansion 423 -- may introduce additional actuals which will trigger errors if call is 424 -- reanalyzed. The following is correct and minimal, but the handling of 425 -- more complex packed expressions in actuals is confused. Probably the 426 -- problem only remains for actuals in calls. 427 428 Set_Etype (Aexp, Packed_Array_Impl_Type (Act_ST)); 429 430 if Is_Entity_Name (Aexp) 431 or else 432 (Nkind (Aexp) = N_Indexed_Component 433 and then Is_Entity_Name (Prefix (Aexp))) 434 or else Nkind_In (Aexp, N_Explicit_Dereference, N_Function_Call) 435 then 436 Set_Analyzed (Aexp); 437 end if; 438 end Convert_To_PAT_Type; 439 440 ----------------------------------- 441 -- Create_Packed_Array_Impl_Type -- 442 ----------------------------------- 443 444 procedure Create_Packed_Array_Impl_Type (Typ : Entity_Id) is 445 Loc : constant Source_Ptr := Sloc (Typ); 446 Ctyp : constant Entity_Id := Component_Type (Typ); 447 Csize : constant Uint := Component_Size (Typ); 448 449 Ancest : Entity_Id; 450 PB_Type : Entity_Id; 451 PASize : Uint; 452 Decl : Node_Id; 453 PAT : Entity_Id; 454 Len_Dim : Node_Id; 455 Len_Expr : Node_Id; 456 Len_Bits : Uint; 457 Bits_U1 : Node_Id; 458 PAT_High : Node_Id; 459 Btyp : Entity_Id; 460 Lit : Node_Id; 461 462 procedure Install_PAT; 463 -- This procedure is called with Decl set to the declaration for the 464 -- packed array type. It creates the type and installs it as required. 465 466 procedure Set_PB_Type; 467 -- Sets PB_Type to Packed_Bytes{1,2,4} as required by the alignment 468 -- requirements (see documentation in the spec of this package). 469 470 ----------------- 471 -- Install_PAT -- 472 ----------------- 473 474 procedure Install_PAT is 475 Pushed_Scope : Boolean := False; 476 477 begin 478 -- We do not want to put the declaration we have created in the tree 479 -- since it is often hard, and sometimes impossible to find a proper 480 -- place for it (the impossible case arises for a packed array type 481 -- with bounds depending on the discriminant, a declaration cannot 482 -- be put inside the record, and the reference to the discriminant 483 -- cannot be outside the record). 484 485 -- The solution is to analyze the declaration while temporarily 486 -- attached to the tree at an appropriate point, and then we install 487 -- the resulting type as an Itype in the packed array type field of 488 -- the original type, so that no explicit declaration is required. 489 490 -- Note: the packed type is created in the scope of its parent type. 491 -- There are at least some cases where the current scope is deeper, 492 -- and so when this is the case, we temporarily reset the scope 493 -- for the definition. This is clearly safe, since the first use 494 -- of the packed array type will be the implicit reference from 495 -- the corresponding unpacked type when it is elaborated. 496 497 if Is_Itype (Typ) then 498 Set_Parent (Decl, Associated_Node_For_Itype (Typ)); 499 else 500 Set_Parent (Decl, Declaration_Node (Typ)); 501 end if; 502 503 if Scope (Typ) /= Current_Scope then 504 Push_Scope (Scope (Typ)); 505 Pushed_Scope := True; 506 end if; 507 508 Set_Is_Itype (PAT, True); 509 Set_Packed_Array_Impl_Type (Typ, PAT); 510 Analyze (Decl, Suppress => All_Checks); 511 512 if Pushed_Scope then 513 Pop_Scope; 514 end if; 515 516 -- Set Esize and RM_Size to the actual size of the packed object 517 -- Do not reset RM_Size if already set, as happens in the case of 518 -- a modular type. 519 520 if Unknown_Esize (PAT) then 521 Set_Esize (PAT, PASize); 522 end if; 523 524 if Unknown_RM_Size (PAT) then 525 Set_RM_Size (PAT, PASize); 526 end if; 527 528 Adjust_Esize_Alignment (PAT); 529 530 -- Set remaining fields of packed array type 531 532 Init_Alignment (PAT); 533 Set_Parent (PAT, Empty); 534 Set_Associated_Node_For_Itype (PAT, Typ); 535 Set_Is_Packed_Array_Impl_Type (PAT, True); 536 Set_Original_Array_Type (PAT, Typ); 537 538 -- For a non-bit-packed array, propagate reverse storage order 539 -- flag from original base type to packed array base type. 540 541 if not Is_Bit_Packed_Array (Typ) then 542 Set_Reverse_Storage_Order 543 (Etype (PAT), Reverse_Storage_Order (Base_Type (Typ))); 544 end if; 545 546 -- We definitely do not want to delay freezing for packed array 547 -- types. This is of particular importance for the itypes that are 548 -- generated for record components depending on discriminants where 549 -- there is no place to put the freeze node. 550 551 Set_Has_Delayed_Freeze (PAT, False); 552 Set_Has_Delayed_Freeze (Etype (PAT), False); 553 554 -- If we did allocate a freeze node, then clear out the reference 555 -- since it is obsolete (should we delete the freeze node???) 556 557 Set_Freeze_Node (PAT, Empty); 558 Set_Freeze_Node (Etype (PAT), Empty); 559 end Install_PAT; 560 561 ----------------- 562 -- Set_PB_Type -- 563 ----------------- 564 565 procedure Set_PB_Type is 566 begin 567 -- If the user has specified an explicit alignment for the 568 -- type or component, take it into account. 569 570 if Csize <= 2 or else Csize = 4 or else Csize mod 2 /= 0 571 or else Alignment (Typ) = 1 572 or else Component_Alignment (Typ) = Calign_Storage_Unit 573 then 574 PB_Type := RTE (RE_Packed_Bytes1); 575 576 elsif Csize mod 4 /= 0 577 or else Alignment (Typ) = 2 578 then 579 PB_Type := RTE (RE_Packed_Bytes2); 580 581 else 582 PB_Type := RTE (RE_Packed_Bytes4); 583 end if; 584 end Set_PB_Type; 585 586 -- Start of processing for Create_Packed_Array_Impl_Type 587 588 begin 589 -- If we already have a packed array type, nothing to do 590 591 if Present (Packed_Array_Impl_Type (Typ)) then 592 return; 593 end if; 594 595 -- If our immediate ancestor subtype is constrained, and it already 596 -- has a packed array type, then just share the same type, since the 597 -- bounds must be the same. If the ancestor is not an array type but 598 -- a private type, as can happen with multiple instantiations, create 599 -- a new packed type, to avoid privacy issues. 600 601 if Ekind (Typ) = E_Array_Subtype then 602 Ancest := Ancestor_Subtype (Typ); 603 604 if Present (Ancest) 605 and then Is_Array_Type (Ancest) 606 and then Is_Constrained (Ancest) 607 and then Present (Packed_Array_Impl_Type (Ancest)) 608 then 609 Set_Packed_Array_Impl_Type (Typ, Packed_Array_Impl_Type (Ancest)); 610 return; 611 end if; 612 end if; 613 614 -- We preset the result type size from the size of the original array 615 -- type, since this size clearly belongs to the packed array type. The 616 -- size of the conceptual unpacked type is always set to unknown. 617 618 PASize := RM_Size (Typ); 619 620 -- Case of an array where at least one index is of an enumeration 621 -- type with a non-standard representation, but the component size 622 -- is not appropriate for bit packing. This is the case where we 623 -- have Is_Packed set (we would never be in this unit otherwise), 624 -- but Is_Bit_Packed_Array is false. 625 626 -- Note that if the component size is appropriate for bit packing, 627 -- then the circuit for the computation of the subscript properly 628 -- deals with the non-standard enumeration type case by taking the 629 -- Pos anyway. 630 631 if not Is_Bit_Packed_Array (Typ) then 632 633 -- Here we build a declaration: 634 635 -- type tttP is array (index1, index2, ...) of component_type 636 637 -- where index1, index2, are the index types. These are the same 638 -- as the index types of the original array, except for the non- 639 -- standard representation enumeration type case, where we have 640 -- two subcases. 641 642 -- For the unconstrained array case, we use 643 644 -- Natural range <> 645 646 -- For the constrained case, we use 647 648 -- Natural range Enum_Type'Pos (Enum_Type'First) .. 649 -- Enum_Type'Pos (Enum_Type'Last); 650 651 -- Note that tttP is created even if no index subtype is a non 652 -- standard enumeration, because we still need to remove padding 653 -- normally inserted for component alignment. 654 655 PAT := 656 Make_Defining_Identifier (Loc, 657 Chars => New_External_Name (Chars (Typ), 'P')); 658 659 Set_Packed_Array_Impl_Type (Typ, PAT); 660 661 declare 662 Indexes : constant List_Id := New_List; 663 Indx : Node_Id; 664 Indx_Typ : Entity_Id; 665 Enum_Case : Boolean; 666 Typedef : Node_Id; 667 668 begin 669 Indx := First_Index (Typ); 670 671 while Present (Indx) loop 672 Indx_Typ := Etype (Indx); 673 674 Enum_Case := Is_Enumeration_Type (Indx_Typ) 675 and then Has_Non_Standard_Rep (Indx_Typ); 676 677 -- Unconstrained case 678 679 if not Is_Constrained (Typ) then 680 if Enum_Case then 681 Indx_Typ := Standard_Natural; 682 end if; 683 684 Append_To (Indexes, New_Occurrence_Of (Indx_Typ, Loc)); 685 686 -- Constrained case 687 688 else 689 if not Enum_Case then 690 Append_To (Indexes, New_Occurrence_Of (Indx_Typ, Loc)); 691 692 else 693 Append_To (Indexes, 694 Make_Subtype_Indication (Loc, 695 Subtype_Mark => 696 New_Occurrence_Of (Standard_Natural, Loc), 697 Constraint => 698 Make_Range_Constraint (Loc, 699 Range_Expression => 700 Make_Range (Loc, 701 Low_Bound => 702 Make_Attribute_Reference (Loc, 703 Prefix => 704 New_Occurrence_Of (Indx_Typ, Loc), 705 Attribute_Name => Name_Pos, 706 Expressions => New_List ( 707 Make_Attribute_Reference (Loc, 708 Prefix => 709 New_Occurrence_Of (Indx_Typ, Loc), 710 Attribute_Name => Name_First))), 711 712 High_Bound => 713 Make_Attribute_Reference (Loc, 714 Prefix => 715 New_Occurrence_Of (Indx_Typ, Loc), 716 Attribute_Name => Name_Pos, 717 Expressions => New_List ( 718 Make_Attribute_Reference (Loc, 719 Prefix => 720 New_Occurrence_Of (Indx_Typ, Loc), 721 Attribute_Name => Name_Last))))))); 722 723 end if; 724 end if; 725 726 Next_Index (Indx); 727 end loop; 728 729 if not Is_Constrained (Typ) then 730 Typedef := 731 Make_Unconstrained_Array_Definition (Loc, 732 Subtype_Marks => Indexes, 733 Component_Definition => 734 Make_Component_Definition (Loc, 735 Aliased_Present => False, 736 Subtype_Indication => 737 New_Occurrence_Of (Ctyp, Loc))); 738 739 else 740 Typedef := 741 Make_Constrained_Array_Definition (Loc, 742 Discrete_Subtype_Definitions => Indexes, 743 Component_Definition => 744 Make_Component_Definition (Loc, 745 Aliased_Present => False, 746 Subtype_Indication => 747 New_Occurrence_Of (Ctyp, Loc))); 748 end if; 749 750 Decl := 751 Make_Full_Type_Declaration (Loc, 752 Defining_Identifier => PAT, 753 Type_Definition => Typedef); 754 end; 755 756 -- Set type as packed array type and install it 757 758 Set_Is_Packed_Array_Impl_Type (PAT); 759 Install_PAT; 760 return; 761 762 -- Case of bit-packing required for unconstrained array. We create 763 -- a subtype that is equivalent to use Packed_Bytes{1,2,4} as needed. 764 765 elsif not Is_Constrained (Typ) then 766 767 -- When generating standard DWARF, the ___XP suffix will be stripped 768 -- by the back-end but generate it anyway to ease compiler debugging. 769 -- This will help to distinguish implementation types from original 770 -- packed arrays. 771 772 PAT := 773 Make_Defining_Identifier (Loc, 774 Chars => Make_Packed_Array_Impl_Type_Name (Typ, Csize)); 775 776 Set_Packed_Array_Impl_Type (Typ, PAT); 777 Set_PB_Type; 778 779 Decl := 780 Make_Subtype_Declaration (Loc, 781 Defining_Identifier => PAT, 782 Subtype_Indication => New_Occurrence_Of (PB_Type, Loc)); 783 Install_PAT; 784 return; 785 786 -- Remaining code is for the case of bit-packing for constrained array 787 788 -- The name of the packed array subtype is 789 790 -- ttt___XPsss 791 792 -- where sss is the component size in bits and ttt is the name of 793 -- the parent packed type. 794 795 else 796 PAT := 797 Make_Defining_Identifier (Loc, 798 Chars => Make_Packed_Array_Impl_Type_Name (Typ, Csize)); 799 800 Set_Packed_Array_Impl_Type (Typ, PAT); 801 802 -- Build an expression for the length of the array in bits. 803 -- This is the product of the length of each of the dimensions 804 805 declare 806 J : Nat := 1; 807 808 begin 809 Len_Expr := Empty; -- suppress junk warning 810 811 loop 812 Len_Dim := 813 Make_Attribute_Reference (Loc, 814 Attribute_Name => Name_Length, 815 Prefix => New_Occurrence_Of (Typ, Loc), 816 Expressions => New_List ( 817 Make_Integer_Literal (Loc, J))); 818 819 if J = 1 then 820 Len_Expr := Len_Dim; 821 822 else 823 Len_Expr := 824 Make_Op_Multiply (Loc, 825 Left_Opnd => Len_Expr, 826 Right_Opnd => Len_Dim); 827 end if; 828 829 J := J + 1; 830 exit when J > Number_Dimensions (Typ); 831 end loop; 832 end; 833 834 -- Temporarily attach the length expression to the tree and analyze 835 -- and resolve it, so that we can test its value. We assume that the 836 -- total length fits in type Integer. This expression may involve 837 -- discriminants, so we treat it as a default/per-object expression. 838 839 Set_Parent (Len_Expr, Typ); 840 Preanalyze_Spec_Expression (Len_Expr, Standard_Long_Long_Integer); 841 842 -- Use a modular type if possible. We can do this if we have 843 -- static bounds, and the length is small enough, and the length 844 -- is not zero. We exclude the zero length case because the size 845 -- of things is always at least one, and the zero length object 846 -- would have an anomalous size. 847 848 if Compile_Time_Known_Value (Len_Expr) then 849 Len_Bits := Expr_Value (Len_Expr) * Csize; 850 851 -- Check for size known to be too large 852 853 if Len_Bits > 854 Uint_2 ** (Standard_Integer_Size - 1) * System_Storage_Unit 855 then 856 if System_Storage_Unit = 8 then 857 Error_Msg_N 858 ("packed array size cannot exceed " & 859 "Integer''Last bytes", Typ); 860 else 861 Error_Msg_N 862 ("packed array size cannot exceed " & 863 "Integer''Last storage units", Typ); 864 end if; 865 866 -- Reset length to arbitrary not too high value to continue 867 868 Len_Expr := Make_Integer_Literal (Loc, 65535); 869 Analyze_And_Resolve (Len_Expr, Standard_Long_Long_Integer); 870 end if; 871 872 -- We normally consider small enough to mean no larger than the 873 -- value of System_Max_Binary_Modulus_Power, checking that in the 874 -- case of values longer than word size, we have long shifts. 875 876 if Len_Bits > 0 877 and then 878 (Len_Bits <= System_Word_Size 879 or else (Len_Bits <= System_Max_Binary_Modulus_Power 880 and then Support_Long_Shifts_On_Target)) 881 then 882 -- We can use the modular type, it has the form: 883 884 -- subtype tttPn is btyp 885 -- range 0 .. 2 ** ((Typ'Length (1) 886 -- * ... * Typ'Length (n)) * Csize) - 1; 887 888 -- The bounds are statically known, and btyp is one of the 889 -- unsigned types, depending on the length. 890 891 if Len_Bits <= Standard_Short_Short_Integer_Size then 892 Btyp := RTE (RE_Short_Short_Unsigned); 893 894 elsif Len_Bits <= Standard_Short_Integer_Size then 895 Btyp := RTE (RE_Short_Unsigned); 896 897 elsif Len_Bits <= Standard_Integer_Size then 898 Btyp := RTE (RE_Unsigned); 899 900 elsif Len_Bits <= Standard_Long_Integer_Size then 901 Btyp := RTE (RE_Long_Unsigned); 902 903 else 904 Btyp := RTE (RE_Long_Long_Unsigned); 905 end if; 906 907 Lit := Make_Integer_Literal (Loc, 2 ** Len_Bits - 1); 908 Set_Print_In_Hex (Lit); 909 910 Decl := 911 Make_Subtype_Declaration (Loc, 912 Defining_Identifier => PAT, 913 Subtype_Indication => 914 Make_Subtype_Indication (Loc, 915 Subtype_Mark => New_Occurrence_Of (Btyp, Loc), 916 917 Constraint => 918 Make_Range_Constraint (Loc, 919 Range_Expression => 920 Make_Range (Loc, 921 Low_Bound => 922 Make_Integer_Literal (Loc, 0), 923 High_Bound => Lit)))); 924 925 if PASize = Uint_0 then 926 PASize := Len_Bits; 927 end if; 928 929 Install_PAT; 930 931 -- Propagate a given alignment to the modular type. This can 932 -- cause it to be under-aligned, but that's OK. 933 934 if Present (Alignment_Clause (Typ)) then 935 Set_Alignment (PAT, Alignment (Typ)); 936 end if; 937 938 return; 939 end if; 940 end if; 941 942 -- Could not use a modular type, for all other cases, we build 943 -- a packed array subtype: 944 945 -- subtype tttPn is 946 -- System.Packed_Bytes{1,2,4} (0 .. (Bits + 7) / 8 - 1); 947 948 -- Bits is the length of the array in bits 949 950 Set_PB_Type; 951 952 Bits_U1 := 953 Make_Op_Add (Loc, 954 Left_Opnd => 955 Make_Op_Multiply (Loc, 956 Left_Opnd => 957 Make_Integer_Literal (Loc, Csize), 958 Right_Opnd => Len_Expr), 959 960 Right_Opnd => 961 Make_Integer_Literal (Loc, 7)); 962 963 Set_Paren_Count (Bits_U1, 1); 964 965 PAT_High := 966 Make_Op_Subtract (Loc, 967 Left_Opnd => 968 Make_Op_Divide (Loc, 969 Left_Opnd => Bits_U1, 970 Right_Opnd => Make_Integer_Literal (Loc, 8)), 971 Right_Opnd => Make_Integer_Literal (Loc, 1)); 972 973 Decl := 974 Make_Subtype_Declaration (Loc, 975 Defining_Identifier => PAT, 976 Subtype_Indication => 977 Make_Subtype_Indication (Loc, 978 Subtype_Mark => New_Occurrence_Of (PB_Type, Loc), 979 Constraint => 980 Make_Index_Or_Discriminant_Constraint (Loc, 981 Constraints => New_List ( 982 Make_Range (Loc, 983 Low_Bound => 984 Make_Integer_Literal (Loc, 0), 985 High_Bound => 986 Convert_To (Standard_Integer, PAT_High)))))); 987 988 Install_PAT; 989 990 -- Currently the code in this unit requires that packed arrays 991 -- represented by non-modular arrays of bytes be on a byte 992 -- boundary for bit sizes handled by System.Pack_nn units. 993 -- That's because these units assume the array being accessed 994 -- starts on a byte boundary. 995 996 if Get_Id (UI_To_Int (Csize)) /= RE_Null then 997 Set_Must_Be_On_Byte_Boundary (Typ); 998 end if; 999 end if; 1000 end Create_Packed_Array_Impl_Type; 1001 1002 ----------------------------------- 1003 -- Expand_Bit_Packed_Element_Set -- 1004 ----------------------------------- 1005 1006 procedure Expand_Bit_Packed_Element_Set (N : Node_Id) is 1007 Loc : constant Source_Ptr := Sloc (N); 1008 Lhs : constant Node_Id := Name (N); 1009 1010 Ass_OK : constant Boolean := Assignment_OK (Lhs); 1011 -- Used to preserve assignment OK status when assignment is rewritten 1012 1013 Rhs : Node_Id := Expression (N); 1014 -- Initially Rhs is the right hand side value, it will be replaced 1015 -- later by an appropriate unchecked conversion for the assignment. 1016 1017 Obj : Node_Id; 1018 Atyp : Entity_Id; 1019 PAT : Entity_Id; 1020 Ctyp : Entity_Id; 1021 Csiz : Int; 1022 Cmask : Uint; 1023 1024 Shift : Node_Id; 1025 -- The expression for the shift value that is required 1026 1027 Shift_Used : Boolean := False; 1028 -- Set True if Shift has been used in the generated code at least once, 1029 -- so that it must be duplicated if used again. 1030 1031 New_Lhs : Node_Id; 1032 New_Rhs : Node_Id; 1033 1034 Rhs_Val_Known : Boolean; 1035 Rhs_Val : Uint; 1036 -- If the value of the right hand side as an integer constant is 1037 -- known at compile time, Rhs_Val_Known is set True, and Rhs_Val 1038 -- contains the value. Otherwise Rhs_Val_Known is set False, and 1039 -- the Rhs_Val is undefined. 1040 1041 function Get_Shift return Node_Id; 1042 -- Function used to get the value of Shift, making sure that it 1043 -- gets duplicated if the function is called more than once. 1044 1045 --------------- 1046 -- Get_Shift -- 1047 --------------- 1048 1049 function Get_Shift return Node_Id is 1050 begin 1051 -- If we used the shift value already, then duplicate it. We 1052 -- set a temporary parent in case actions have to be inserted. 1053 1054 if Shift_Used then 1055 Set_Parent (Shift, N); 1056 return Duplicate_Subexpr_No_Checks (Shift); 1057 1058 -- If first time, use Shift unchanged, and set flag for first use 1059 1060 else 1061 Shift_Used := True; 1062 return Shift; 1063 end if; 1064 end Get_Shift; 1065 1066 -- Start of processing for Expand_Bit_Packed_Element_Set 1067 1068 begin 1069 pragma Assert (Is_Bit_Packed_Array (Etype (Prefix (Lhs)))); 1070 1071 Obj := Relocate_Node (Prefix (Lhs)); 1072 Convert_To_Actual_Subtype (Obj); 1073 Atyp := Etype (Obj); 1074 PAT := Packed_Array_Impl_Type (Atyp); 1075 Ctyp := Component_Type (Atyp); 1076 Csiz := UI_To_Int (Component_Size (Atyp)); 1077 1078 -- We remove side effects, in case the rhs modifies the lhs, because we 1079 -- are about to transform the rhs into an expression that first READS 1080 -- the lhs, so we can do the necessary shifting and masking. Example: 1081 -- "X(2) := F(...);" where F modifies X(3). Otherwise, the side effect 1082 -- will be lost. 1083 1084 Remove_Side_Effects (Rhs); 1085 1086 -- We convert the right hand side to the proper subtype to ensure 1087 -- that an appropriate range check is made (since the normal range 1088 -- check from assignment will be lost in the transformations). This 1089 -- conversion is analyzed immediately so that subsequent processing 1090 -- can work with an analyzed Rhs (and e.g. look at its Etype) 1091 1092 -- If the right-hand side is a string literal, create a temporary for 1093 -- it, constant-folding is not ready to wrap the bit representation 1094 -- of a string literal. 1095 1096 if Nkind (Rhs) = N_String_Literal then 1097 declare 1098 Decl : Node_Id; 1099 begin 1100 Decl := 1101 Make_Object_Declaration (Loc, 1102 Defining_Identifier => Make_Temporary (Loc, 'T', Rhs), 1103 Object_Definition => New_Occurrence_Of (Ctyp, Loc), 1104 Expression => New_Copy_Tree (Rhs)); 1105 1106 Insert_Actions (N, New_List (Decl)); 1107 Rhs := New_Occurrence_Of (Defining_Identifier (Decl), Loc); 1108 end; 1109 end if; 1110 1111 Rhs := Convert_To (Ctyp, Rhs); 1112 Set_Parent (Rhs, N); 1113 1114 -- If we are building the initialization procedure for a packed array, 1115 -- and Initialize_Scalars is enabled, each component assignment is an 1116 -- out-of-range value by design. Compile this value without checks, 1117 -- because a call to the array init_proc must not raise an exception. 1118 1119 -- Condition is not consistent with description above, Within_Init_Proc 1120 -- is True also when we are building the IP for a record or protected 1121 -- type that has a packed array component??? 1122 1123 if Within_Init_Proc 1124 and then Initialize_Scalars 1125 then 1126 Analyze_And_Resolve (Rhs, Ctyp, Suppress => All_Checks); 1127 else 1128 Analyze_And_Resolve (Rhs, Ctyp); 1129 end if; 1130 1131 -- For the AAMP target, indexing of certain packed array is passed 1132 -- through to the back end without expansion, because the expansion 1133 -- results in very inefficient code on that target. This allows the 1134 -- GNAAMP back end to generate specialized macros that support more 1135 -- efficient indexing of packed arrays with components having sizes 1136 -- that are small powers of two. 1137 1138 if AAMP_On_Target 1139 and then (Csiz = 1 or else Csiz = 2 or else Csiz = 4) 1140 then 1141 return; 1142 end if; 1143 1144 -- Case of component size 1,2,4 or any component size for the modular 1145 -- case. These are the cases for which we can inline the code. 1146 1147 if Csiz = 1 or else Csiz = 2 or else Csiz = 4 1148 or else (Present (PAT) and then Is_Modular_Integer_Type (PAT)) 1149 then 1150 Setup_Inline_Packed_Array_Reference (Lhs, Atyp, Obj, Cmask, Shift); 1151 1152 -- The statement to be generated is: 1153 1154 -- Obj := atyp!((Obj and Mask1) or (shift_left (rhs, Shift))) 1155 1156 -- or in the case of a freestanding Reverse_Storage_Order object, 1157 1158 -- Obj := Swap (atyp!((Swap (Obj) and Mask1) 1159 -- or (shift_left (rhs, Shift)))) 1160 1161 -- where Mask1 is obtained by shifting Cmask left Shift bits 1162 -- and then complementing the result. 1163 1164 -- the "and Mask1" is omitted if rhs is constant and all 1 bits 1165 1166 -- the "or ..." is omitted if rhs is constant and all 0 bits 1167 1168 -- rhs is converted to the appropriate type 1169 1170 -- The result is converted back to the array type, since 1171 -- otherwise we lose knowledge of the packed nature. 1172 1173 -- Determine if right side is all 0 bits or all 1 bits 1174 1175 if Compile_Time_Known_Value (Rhs) then 1176 Rhs_Val := Expr_Rep_Value (Rhs); 1177 Rhs_Val_Known := True; 1178 1179 -- The following test catches the case of an unchecked conversion of 1180 -- an integer literal. This results from optimizing aggregates of 1181 -- packed types. 1182 1183 elsif Nkind (Rhs) = N_Unchecked_Type_Conversion 1184 and then Compile_Time_Known_Value (Expression (Rhs)) 1185 then 1186 Rhs_Val := Expr_Rep_Value (Expression (Rhs)); 1187 Rhs_Val_Known := True; 1188 1189 else 1190 Rhs_Val := No_Uint; 1191 Rhs_Val_Known := False; 1192 end if; 1193 1194 -- Some special checks for the case where the right hand value is 1195 -- known at compile time. Basically we have to take care of the 1196 -- implicit conversion to the subtype of the component object. 1197 1198 if Rhs_Val_Known then 1199 1200 -- If we have a biased component type then we must manually do the 1201 -- biasing, since we are taking responsibility in this case for 1202 -- constructing the exact bit pattern to be used. 1203 1204 if Has_Biased_Representation (Ctyp) then 1205 Rhs_Val := Rhs_Val - Expr_Rep_Value (Type_Low_Bound (Ctyp)); 1206 end if; 1207 1208 -- For a negative value, we manually convert the two's complement 1209 -- value to a corresponding unsigned value, so that the proper 1210 -- field width is maintained. If we did not do this, we would 1211 -- get too many leading sign bits later on. 1212 1213 if Rhs_Val < 0 then 1214 Rhs_Val := 2 ** UI_From_Int (Csiz) + Rhs_Val; 1215 end if; 1216 end if; 1217 1218 -- Now create copies removing side effects. Note that in some complex 1219 -- cases, this may cause the fact that we have already set a packed 1220 -- array type on Obj to get lost. So we save the type of Obj, and 1221 -- make sure it is reset properly. 1222 1223 New_Lhs := Duplicate_Subexpr (Obj, Name_Req => True); 1224 New_Rhs := Duplicate_Subexpr_No_Checks (Obj); 1225 1226 -- First we deal with the "and" 1227 1228 if not Rhs_Val_Known or else Rhs_Val /= Cmask then 1229 declare 1230 Mask1 : Node_Id; 1231 Lit : Node_Id; 1232 1233 begin 1234 if Compile_Time_Known_Value (Shift) then 1235 Mask1 := 1236 Make_Integer_Literal (Loc, 1237 Modulus (Etype (Obj)) - 1 - 1238 (Cmask * (2 ** Expr_Value (Get_Shift)))); 1239 Set_Print_In_Hex (Mask1); 1240 1241 else 1242 Lit := Make_Integer_Literal (Loc, Cmask); 1243 Set_Print_In_Hex (Lit); 1244 Mask1 := 1245 Make_Op_Not (Loc, 1246 Right_Opnd => Make_Shift_Left (Lit, Get_Shift)); 1247 end if; 1248 1249 New_Rhs := 1250 Make_Op_And (Loc, 1251 Left_Opnd => New_Rhs, 1252 Right_Opnd => Mask1); 1253 end; 1254 end if; 1255 1256 -- Then deal with the "or" 1257 1258 if not Rhs_Val_Known or else Rhs_Val /= 0 then 1259 declare 1260 Or_Rhs : Node_Id; 1261 1262 procedure Fixup_Rhs; 1263 -- Adjust Rhs by bias if biased representation for components 1264 -- or remove extraneous high order sign bits if signed. 1265 1266 procedure Fixup_Rhs is 1267 Etyp : constant Entity_Id := Etype (Rhs); 1268 1269 begin 1270 -- For biased case, do the required biasing by simply 1271 -- converting to the biased subtype (the conversion 1272 -- will generate the required bias). 1273 1274 if Has_Biased_Representation (Ctyp) then 1275 Rhs := Convert_To (Ctyp, Rhs); 1276 1277 -- For a signed integer type that is not biased, generate 1278 -- a conversion to unsigned to strip high order sign bits. 1279 1280 elsif Is_Signed_Integer_Type (Ctyp) then 1281 Rhs := Unchecked_Convert_To (RTE (Bits_Id (Csiz)), Rhs); 1282 end if; 1283 1284 -- Set Etype, since it can be referenced before the node is 1285 -- completely analyzed. 1286 1287 Set_Etype (Rhs, Etyp); 1288 1289 -- We now need to do an unchecked conversion of the 1290 -- result to the target type, but it is important that 1291 -- this conversion be a right justified conversion and 1292 -- not a left justified conversion. 1293 1294 Rhs := RJ_Unchecked_Convert_To (Etype (Obj), Rhs); 1295 end Fixup_Rhs; 1296 1297 begin 1298 if Rhs_Val_Known 1299 and then Compile_Time_Known_Value (Get_Shift) 1300 then 1301 Or_Rhs := 1302 Make_Integer_Literal (Loc, 1303 Rhs_Val * (2 ** Expr_Value (Get_Shift))); 1304 Set_Print_In_Hex (Or_Rhs); 1305 1306 else 1307 -- We have to convert the right hand side to Etype (Obj). 1308 -- A special case arises if what we have now is a Val 1309 -- attribute reference whose expression type is Etype (Obj). 1310 -- This happens for assignments of fields from the same 1311 -- array. In this case we get the required right hand side 1312 -- by simply removing the inner attribute reference. 1313 1314 if Nkind (Rhs) = N_Attribute_Reference 1315 and then Attribute_Name (Rhs) = Name_Val 1316 and then Etype (First (Expressions (Rhs))) = Etype (Obj) 1317 then 1318 Rhs := Relocate_Node (First (Expressions (Rhs))); 1319 Fixup_Rhs; 1320 1321 -- If the value of the right hand side is a known integer 1322 -- value, then just replace it by an untyped constant, 1323 -- which will be properly retyped when we analyze and 1324 -- resolve the expression. 1325 1326 elsif Rhs_Val_Known then 1327 1328 -- Note that Rhs_Val has already been normalized to 1329 -- be an unsigned value with the proper number of bits. 1330 1331 Rhs := Make_Integer_Literal (Loc, Rhs_Val); 1332 1333 -- Otherwise we need an unchecked conversion 1334 1335 else 1336 Fixup_Rhs; 1337 end if; 1338 1339 Or_Rhs := Make_Shift_Left (Rhs, Get_Shift); 1340 end if; 1341 1342 if Nkind (New_Rhs) = N_Op_And then 1343 Set_Paren_Count (New_Rhs, 1); 1344 Set_Etype (New_Rhs, Etype (Left_Opnd (New_Rhs))); 1345 end if; 1346 1347 New_Rhs := 1348 Make_Op_Or (Loc, 1349 Left_Opnd => New_Rhs, 1350 Right_Opnd => Or_Rhs); 1351 end; 1352 end if; 1353 1354 -- Now do the rewrite 1355 1356 Rewrite (N, 1357 Make_Assignment_Statement (Loc, 1358 Name => New_Lhs, 1359 Expression => 1360 Unchecked_Convert_To (Etype (New_Lhs), New_Rhs))); 1361 Set_Assignment_OK (Name (N), Ass_OK); 1362 1363 -- All other component sizes for non-modular case 1364 1365 else 1366 -- We generate 1367 1368 -- Set_nn (Arr'address, Subscr, Bits_nn!(Rhs)) 1369 1370 -- where Subscr is the computed linear subscript 1371 1372 declare 1373 Bits_nn : constant Entity_Id := RTE (Bits_Id (Csiz)); 1374 Set_nn : Entity_Id; 1375 Subscr : Node_Id; 1376 Atyp : Entity_Id; 1377 Rev_SSO : Node_Id; 1378 1379 begin 1380 if No (Bits_nn) then 1381 1382 -- Error, most likely High_Integrity_Mode restriction 1383 1384 return; 1385 end if; 1386 1387 -- Acquire proper Set entity. We use the aligned or unaligned 1388 -- case as appropriate. 1389 1390 if Known_Aligned_Enough (Obj, Csiz) then 1391 Set_nn := RTE (Set_Id (Csiz)); 1392 else 1393 Set_nn := RTE (SetU_Id (Csiz)); 1394 end if; 1395 1396 -- Now generate the set reference 1397 1398 Obj := Relocate_Node (Prefix (Lhs)); 1399 Convert_To_Actual_Subtype (Obj); 1400 Atyp := Etype (Obj); 1401 Compute_Linear_Subscript (Atyp, Lhs, Subscr); 1402 1403 -- Set indication of whether the packed array has reverse SSO 1404 1405 Rev_SSO := 1406 New_Occurrence_Of 1407 (Boolean_Literals (Reverse_Storage_Order (Atyp)), Loc); 1408 1409 -- Below we must make the assumption that Obj is 1410 -- at least byte aligned, since otherwise its address 1411 -- cannot be taken. The assumption holds since the 1412 -- only arrays that can be misaligned are small packed 1413 -- arrays which are implemented as a modular type, and 1414 -- that is not the case here. 1415 1416 Rewrite (N, 1417 Make_Procedure_Call_Statement (Loc, 1418 Name => New_Occurrence_Of (Set_nn, Loc), 1419 Parameter_Associations => New_List ( 1420 Make_Attribute_Reference (Loc, 1421 Prefix => Obj, 1422 Attribute_Name => Name_Address), 1423 Subscr, 1424 Unchecked_Convert_To (Bits_nn, Convert_To (Ctyp, Rhs)), 1425 Rev_SSO))); 1426 1427 end; 1428 end if; 1429 1430 Analyze (N, Suppress => All_Checks); 1431 end Expand_Bit_Packed_Element_Set; 1432 1433 ------------------------------------- 1434 -- Expand_Packed_Address_Reference -- 1435 ------------------------------------- 1436 1437 procedure Expand_Packed_Address_Reference (N : Node_Id) is 1438 Loc : constant Source_Ptr := Sloc (N); 1439 Base : Node_Id; 1440 Offset : Node_Id; 1441 1442 begin 1443 -- We build an expression that has the form 1444 1445 -- outer_object'Address 1446 -- + (linear-subscript * component_size for each array reference 1447 -- + field'Bit_Position for each record field 1448 -- + ... 1449 -- + ...) / Storage_Unit; 1450 1451 Get_Base_And_Bit_Offset (Prefix (N), Base, Offset); 1452 1453 Rewrite (N, 1454 Unchecked_Convert_To (RTE (RE_Address), 1455 Make_Op_Add (Loc, 1456 Left_Opnd => 1457 Unchecked_Convert_To (RTE (RE_Integer_Address), 1458 Make_Attribute_Reference (Loc, 1459 Prefix => Base, 1460 Attribute_Name => Name_Address)), 1461 1462 Right_Opnd => 1463 Unchecked_Convert_To (RTE (RE_Integer_Address), 1464 Make_Op_Divide (Loc, 1465 Left_Opnd => Offset, 1466 Right_Opnd => 1467 Make_Integer_Literal (Loc, System_Storage_Unit)))))); 1468 1469 Analyze_And_Resolve (N, RTE (RE_Address)); 1470 end Expand_Packed_Address_Reference; 1471 1472 --------------------------------- 1473 -- Expand_Packed_Bit_Reference -- 1474 --------------------------------- 1475 1476 procedure Expand_Packed_Bit_Reference (N : Node_Id) is 1477 Loc : constant Source_Ptr := Sloc (N); 1478 Base : Node_Id; 1479 Offset : Node_Id; 1480 1481 begin 1482 -- We build an expression that has the form 1483 1484 -- (linear-subscript * component_size for each array reference 1485 -- + field'Bit_Position for each record field 1486 -- + ... 1487 -- + ...) mod Storage_Unit; 1488 1489 Get_Base_And_Bit_Offset (Prefix (N), Base, Offset); 1490 1491 Rewrite (N, 1492 Unchecked_Convert_To (Universal_Integer, 1493 Make_Op_Mod (Loc, 1494 Left_Opnd => Offset, 1495 Right_Opnd => Make_Integer_Literal (Loc, System_Storage_Unit)))); 1496 1497 Analyze_And_Resolve (N, Universal_Integer); 1498 end Expand_Packed_Bit_Reference; 1499 1500 ------------------------------------ 1501 -- Expand_Packed_Boolean_Operator -- 1502 ------------------------------------ 1503 1504 -- This routine expands "a op b" for the packed cases 1505 1506 procedure Expand_Packed_Boolean_Operator (N : Node_Id) is 1507 Loc : constant Source_Ptr := Sloc (N); 1508 Typ : constant Entity_Id := Etype (N); 1509 L : constant Node_Id := Relocate_Node (Left_Opnd (N)); 1510 R : constant Node_Id := Relocate_Node (Right_Opnd (N)); 1511 1512 Ltyp : Entity_Id; 1513 Rtyp : Entity_Id; 1514 PAT : Entity_Id; 1515 1516 begin 1517 Convert_To_Actual_Subtype (L); 1518 Convert_To_Actual_Subtype (R); 1519 1520 Ensure_Defined (Etype (L), N); 1521 Ensure_Defined (Etype (R), N); 1522 1523 Apply_Length_Check (R, Etype (L)); 1524 1525 Ltyp := Etype (L); 1526 Rtyp := Etype (R); 1527 1528 -- Deal with silly case of XOR where the subcomponent has a range 1529 -- True .. True where an exception must be raised. 1530 1531 if Nkind (N) = N_Op_Xor then 1532 Silly_Boolean_Array_Xor_Test (N, Rtyp); 1533 end if; 1534 1535 -- Now that that silliness is taken care of, get packed array type 1536 1537 Convert_To_PAT_Type (L); 1538 Convert_To_PAT_Type (R); 1539 1540 PAT := Etype (L); 1541 1542 -- For the modular case, we expand a op b into 1543 1544 -- rtyp!(pat!(a) op pat!(b)) 1545 1546 -- where rtyp is the Etype of the left operand. Note that we do not 1547 -- convert to the base type, since this would be unconstrained, and 1548 -- hence not have a corresponding packed array type set. 1549 1550 -- Note that both operands must be modular for this code to be used 1551 1552 if Is_Modular_Integer_Type (PAT) 1553 and then 1554 Is_Modular_Integer_Type (Etype (R)) 1555 then 1556 declare 1557 P : Node_Id; 1558 1559 begin 1560 if Nkind (N) = N_Op_And then 1561 P := Make_Op_And (Loc, L, R); 1562 1563 elsif Nkind (N) = N_Op_Or then 1564 P := Make_Op_Or (Loc, L, R); 1565 1566 else -- Nkind (N) = N_Op_Xor 1567 P := Make_Op_Xor (Loc, L, R); 1568 end if; 1569 1570 Rewrite (N, Unchecked_Convert_To (Ltyp, P)); 1571 end; 1572 1573 -- For the array case, we insert the actions 1574 1575 -- Result : Ltype; 1576 1577 -- System.Bit_Ops.Bit_And/Or/Xor 1578 -- (Left'Address, 1579 -- Ltype'Length * Ltype'Component_Size; 1580 -- Right'Address, 1581 -- Rtype'Length * Rtype'Component_Size 1582 -- Result'Address); 1583 1584 -- where Left and Right are the Packed_Bytes{1,2,4} operands and 1585 -- the second argument and fourth arguments are the lengths of the 1586 -- operands in bits. Then we replace the expression by a reference 1587 -- to Result. 1588 1589 -- Note that if we are mixing a modular and array operand, everything 1590 -- works fine, since we ensure that the modular representation has the 1591 -- same physical layout as the array representation (that's what the 1592 -- left justified modular stuff in the big-endian case is about). 1593 1594 else 1595 declare 1596 Result_Ent : constant Entity_Id := Make_Temporary (Loc, 'T'); 1597 E_Id : RE_Id; 1598 1599 begin 1600 if Nkind (N) = N_Op_And then 1601 E_Id := RE_Bit_And; 1602 1603 elsif Nkind (N) = N_Op_Or then 1604 E_Id := RE_Bit_Or; 1605 1606 else -- Nkind (N) = N_Op_Xor 1607 E_Id := RE_Bit_Xor; 1608 end if; 1609 1610 Insert_Actions (N, New_List ( 1611 1612 Make_Object_Declaration (Loc, 1613 Defining_Identifier => Result_Ent, 1614 Object_Definition => New_Occurrence_Of (Ltyp, Loc)), 1615 1616 Make_Procedure_Call_Statement (Loc, 1617 Name => New_Occurrence_Of (RTE (E_Id), Loc), 1618 Parameter_Associations => New_List ( 1619 1620 Make_Byte_Aligned_Attribute_Reference (Loc, 1621 Prefix => L, 1622 Attribute_Name => Name_Address), 1623 1624 Make_Op_Multiply (Loc, 1625 Left_Opnd => 1626 Make_Attribute_Reference (Loc, 1627 Prefix => 1628 New_Occurrence_Of 1629 (Etype (First_Index (Ltyp)), Loc), 1630 Attribute_Name => Name_Range_Length), 1631 1632 Right_Opnd => 1633 Make_Integer_Literal (Loc, Component_Size (Ltyp))), 1634 1635 Make_Byte_Aligned_Attribute_Reference (Loc, 1636 Prefix => R, 1637 Attribute_Name => Name_Address), 1638 1639 Make_Op_Multiply (Loc, 1640 Left_Opnd => 1641 Make_Attribute_Reference (Loc, 1642 Prefix => 1643 New_Occurrence_Of 1644 (Etype (First_Index (Rtyp)), Loc), 1645 Attribute_Name => Name_Range_Length), 1646 1647 Right_Opnd => 1648 Make_Integer_Literal (Loc, Component_Size (Rtyp))), 1649 1650 Make_Byte_Aligned_Attribute_Reference (Loc, 1651 Prefix => New_Occurrence_Of (Result_Ent, Loc), 1652 Attribute_Name => Name_Address))))); 1653 1654 Rewrite (N, 1655 New_Occurrence_Of (Result_Ent, Loc)); 1656 end; 1657 end if; 1658 1659 Analyze_And_Resolve (N, Typ, Suppress => All_Checks); 1660 end Expand_Packed_Boolean_Operator; 1661 1662 ------------------------------------- 1663 -- Expand_Packed_Element_Reference -- 1664 ------------------------------------- 1665 1666 procedure Expand_Packed_Element_Reference (N : Node_Id) is 1667 Loc : constant Source_Ptr := Sloc (N); 1668 Obj : Node_Id; 1669 Atyp : Entity_Id; 1670 PAT : Entity_Id; 1671 Ctyp : Entity_Id; 1672 Csiz : Int; 1673 Shift : Node_Id; 1674 Cmask : Uint; 1675 Lit : Node_Id; 1676 Arg : Node_Id; 1677 1678 begin 1679 -- If the node is an actual in a call, the prefix has not been fully 1680 -- expanded, to account for the additional expansion for in-out actuals 1681 -- (see expand_actuals for details). If the prefix itself is a packed 1682 -- reference as well, we have to recurse to complete the transformation 1683 -- of the prefix. 1684 1685 if Nkind (Prefix (N)) = N_Indexed_Component 1686 and then not Analyzed (Prefix (N)) 1687 and then Is_Bit_Packed_Array (Etype (Prefix (Prefix (N)))) 1688 then 1689 Expand_Packed_Element_Reference (Prefix (N)); 1690 end if; 1691 1692 -- The prefix may be rewritten below as a conversion. If it is a source 1693 -- entity generate reference to it now, to prevent spurious warnings 1694 -- about unused entities. 1695 1696 if Is_Entity_Name (Prefix (N)) 1697 and then Comes_From_Source (Prefix (N)) 1698 then 1699 Generate_Reference (Entity (Prefix (N)), Prefix (N), 'r'); 1700 end if; 1701 1702 -- If not bit packed, we have the enumeration case, which is easily 1703 -- dealt with (just adjust the subscripts of the indexed component) 1704 1705 -- Note: this leaves the result as an indexed component, which is 1706 -- still a variable, so can be used in the assignment case, as is 1707 -- required in the enumeration case. 1708 1709 if not Is_Bit_Packed_Array (Etype (Prefix (N))) then 1710 Setup_Enumeration_Packed_Array_Reference (N); 1711 return; 1712 end if; 1713 1714 -- Remaining processing is for the bit-packed case 1715 1716 Obj := Relocate_Node (Prefix (N)); 1717 Convert_To_Actual_Subtype (Obj); 1718 Atyp := Etype (Obj); 1719 PAT := Packed_Array_Impl_Type (Atyp); 1720 Ctyp := Component_Type (Atyp); 1721 Csiz := UI_To_Int (Component_Size (Atyp)); 1722 1723 -- For the AAMP target, indexing of certain packed array is passed 1724 -- through to the back end without expansion, because the expansion 1725 -- results in very inefficient code on that target. This allows the 1726 -- GNAAMP back end to generate specialized macros that support more 1727 -- efficient indexing of packed arrays with components having sizes 1728 -- that are small powers of two. 1729 1730 if AAMP_On_Target 1731 and then (Csiz = 1 or else Csiz = 2 or else Csiz = 4) 1732 then 1733 return; 1734 end if; 1735 1736 -- Case of component size 1,2,4 or any component size for the modular 1737 -- case. These are the cases for which we can inline the code. 1738 1739 if Csiz = 1 or else Csiz = 2 or else Csiz = 4 1740 or else (Present (PAT) and then Is_Modular_Integer_Type (PAT)) 1741 then 1742 Setup_Inline_Packed_Array_Reference (N, Atyp, Obj, Cmask, Shift); 1743 Lit := Make_Integer_Literal (Loc, Cmask); 1744 Set_Print_In_Hex (Lit); 1745 1746 -- We generate a shift right to position the field, followed by a 1747 -- masking operation to extract the bit field, and we finally do an 1748 -- unchecked conversion to convert the result to the required target. 1749 1750 -- Note that the unchecked conversion automatically deals with the 1751 -- bias if we are dealing with a biased representation. What will 1752 -- happen is that we temporarily generate the biased representation, 1753 -- but almost immediately that will be converted to the original 1754 -- unbiased component type, and the bias will disappear. 1755 1756 Arg := 1757 Make_Op_And (Loc, 1758 Left_Opnd => Make_Shift_Right (Obj, Shift), 1759 Right_Opnd => Lit); 1760 Set_Etype (Arg, Ctyp); 1761 1762 -- Component extraction is performed on a native endianness scalar 1763 -- value: if Atyp has reverse storage order, then it has been byte 1764 -- swapped, and if the component being extracted is itself of a 1765 -- composite type with reverse storage order, then we need to swap 1766 -- it back to its expected endianness after extraction. 1767 1768 if Reverse_Storage_Order (Atyp) 1769 and then (Is_Record_Type (Ctyp) or else Is_Array_Type (Ctyp)) 1770 and then Reverse_Storage_Order (Ctyp) 1771 then 1772 Arg := Revert_Storage_Order (Arg); 1773 end if; 1774 1775 -- We needed to analyze this before we do the unchecked convert 1776 -- below, but we need it temporarily attached to the tree for 1777 -- this analysis (hence the temporary Set_Parent call). 1778 1779 Set_Parent (Arg, Parent (N)); 1780 Analyze_And_Resolve (Arg); 1781 1782 Rewrite (N, RJ_Unchecked_Convert_To (Ctyp, Arg)); 1783 1784 -- All other component sizes for non-modular case 1785 1786 else 1787 -- We generate 1788 1789 -- Component_Type!(Get_nn (Arr'address, Subscr)) 1790 1791 -- where Subscr is the computed linear subscript 1792 1793 declare 1794 Get_nn : Entity_Id; 1795 Subscr : Node_Id; 1796 Rev_SSO : constant Node_Id := 1797 New_Occurrence_Of 1798 (Boolean_Literals (Reverse_Storage_Order (Atyp)), Loc); 1799 1800 begin 1801 -- Acquire proper Get entity. We use the aligned or unaligned 1802 -- case as appropriate. 1803 1804 if Known_Aligned_Enough (Obj, Csiz) then 1805 Get_nn := RTE (Get_Id (Csiz)); 1806 else 1807 Get_nn := RTE (GetU_Id (Csiz)); 1808 end if; 1809 1810 -- Now generate the get reference 1811 1812 Compute_Linear_Subscript (Atyp, N, Subscr); 1813 1814 -- Below we make the assumption that Obj is at least byte 1815 -- aligned, since otherwise its address cannot be taken. 1816 -- The assumption holds since the only arrays that can be 1817 -- misaligned are small packed arrays which are implemented 1818 -- as a modular type, and that is not the case here. 1819 1820 Rewrite (N, 1821 Unchecked_Convert_To (Ctyp, 1822 Make_Function_Call (Loc, 1823 Name => New_Occurrence_Of (Get_nn, Loc), 1824 Parameter_Associations => New_List ( 1825 Make_Attribute_Reference (Loc, 1826 Prefix => Obj, 1827 Attribute_Name => Name_Address), 1828 Subscr, 1829 Rev_SSO)))); 1830 end; 1831 end if; 1832 1833 Analyze_And_Resolve (N, Ctyp, Suppress => All_Checks); 1834 end Expand_Packed_Element_Reference; 1835 1836 ---------------------- 1837 -- Expand_Packed_Eq -- 1838 ---------------------- 1839 1840 -- Handles expansion of "=" on packed array types 1841 1842 procedure Expand_Packed_Eq (N : Node_Id) is 1843 Loc : constant Source_Ptr := Sloc (N); 1844 L : constant Node_Id := Relocate_Node (Left_Opnd (N)); 1845 R : constant Node_Id := Relocate_Node (Right_Opnd (N)); 1846 1847 LLexpr : Node_Id; 1848 RLexpr : Node_Id; 1849 1850 Ltyp : Entity_Id; 1851 Rtyp : Entity_Id; 1852 PAT : Entity_Id; 1853 1854 begin 1855 Convert_To_Actual_Subtype (L); 1856 Convert_To_Actual_Subtype (R); 1857 Ltyp := Underlying_Type (Etype (L)); 1858 Rtyp := Underlying_Type (Etype (R)); 1859 1860 Convert_To_PAT_Type (L); 1861 Convert_To_PAT_Type (R); 1862 PAT := Etype (L); 1863 1864 LLexpr := 1865 Make_Op_Multiply (Loc, 1866 Left_Opnd => 1867 Make_Attribute_Reference (Loc, 1868 Prefix => New_Occurrence_Of (Ltyp, Loc), 1869 Attribute_Name => Name_Length), 1870 Right_Opnd => 1871 Make_Integer_Literal (Loc, Component_Size (Ltyp))); 1872 1873 RLexpr := 1874 Make_Op_Multiply (Loc, 1875 Left_Opnd => 1876 Make_Attribute_Reference (Loc, 1877 Prefix => New_Occurrence_Of (Rtyp, Loc), 1878 Attribute_Name => Name_Length), 1879 Right_Opnd => 1880 Make_Integer_Literal (Loc, Component_Size (Rtyp))); 1881 1882 -- For the modular case, we transform the comparison to: 1883 1884 -- Ltyp'Length = Rtyp'Length and then PAT!(L) = PAT!(R) 1885 1886 -- where PAT is the packed array type. This works fine, since in the 1887 -- modular case we guarantee that the unused bits are always zeroes. 1888 -- We do have to compare the lengths because we could be comparing 1889 -- two different subtypes of the same base type. 1890 1891 if Is_Modular_Integer_Type (PAT) then 1892 Rewrite (N, 1893 Make_And_Then (Loc, 1894 Left_Opnd => 1895 Make_Op_Eq (Loc, 1896 Left_Opnd => LLexpr, 1897 Right_Opnd => RLexpr), 1898 1899 Right_Opnd => 1900 Make_Op_Eq (Loc, 1901 Left_Opnd => L, 1902 Right_Opnd => R))); 1903 1904 -- For the non-modular case, we call a runtime routine 1905 1906 -- System.Bit_Ops.Bit_Eq 1907 -- (L'Address, L_Length, R'Address, R_Length) 1908 1909 -- where PAT is the packed array type, and the lengths are the lengths 1910 -- in bits of the original packed arrays. This routine takes care of 1911 -- not comparing the unused bits in the last byte. 1912 1913 else 1914 Rewrite (N, 1915 Make_Function_Call (Loc, 1916 Name => New_Occurrence_Of (RTE (RE_Bit_Eq), Loc), 1917 Parameter_Associations => New_List ( 1918 Make_Byte_Aligned_Attribute_Reference (Loc, 1919 Prefix => L, 1920 Attribute_Name => Name_Address), 1921 1922 LLexpr, 1923 1924 Make_Byte_Aligned_Attribute_Reference (Loc, 1925 Prefix => R, 1926 Attribute_Name => Name_Address), 1927 1928 RLexpr))); 1929 end if; 1930 1931 Analyze_And_Resolve (N, Standard_Boolean, Suppress => All_Checks); 1932 end Expand_Packed_Eq; 1933 1934 ----------------------- 1935 -- Expand_Packed_Not -- 1936 ----------------------- 1937 1938 -- Handles expansion of "not" on packed array types 1939 1940 procedure Expand_Packed_Not (N : Node_Id) is 1941 Loc : constant Source_Ptr := Sloc (N); 1942 Typ : constant Entity_Id := Etype (N); 1943 Opnd : constant Node_Id := Relocate_Node (Right_Opnd (N)); 1944 1945 Rtyp : Entity_Id; 1946 PAT : Entity_Id; 1947 Lit : Node_Id; 1948 1949 begin 1950 Convert_To_Actual_Subtype (Opnd); 1951 Rtyp := Etype (Opnd); 1952 1953 -- Deal with silly False..False and True..True subtype case 1954 1955 Silly_Boolean_Array_Not_Test (N, Rtyp); 1956 1957 -- Now that the silliness is taken care of, get packed array type 1958 1959 Convert_To_PAT_Type (Opnd); 1960 PAT := Etype (Opnd); 1961 1962 -- For the case where the packed array type is a modular type, "not A" 1963 -- expands simply into: 1964 1965 -- Rtyp!(PAT!(A) xor Mask) 1966 1967 -- where PAT is the packed array type, Mask is a mask of all 1 bits of 1968 -- length equal to the size of this packed type, and Rtyp is the actual 1969 -- actual subtype of the operand. 1970 1971 Lit := Make_Integer_Literal (Loc, 2 ** RM_Size (PAT) - 1); 1972 Set_Print_In_Hex (Lit); 1973 1974 if not Is_Array_Type (PAT) then 1975 Rewrite (N, 1976 Unchecked_Convert_To (Rtyp, 1977 Make_Op_Xor (Loc, 1978 Left_Opnd => Opnd, 1979 Right_Opnd => Lit))); 1980 1981 -- For the array case, we insert the actions 1982 1983 -- Result : Typ; 1984 1985 -- System.Bit_Ops.Bit_Not 1986 -- (Opnd'Address, 1987 -- Typ'Length * Typ'Component_Size, 1988 -- Result'Address); 1989 1990 -- where Opnd is the Packed_Bytes{1,2,4} operand and the second argument 1991 -- is the length of the operand in bits. We then replace the expression 1992 -- with a reference to Result. 1993 1994 else 1995 declare 1996 Result_Ent : constant Entity_Id := Make_Temporary (Loc, 'T'); 1997 1998 begin 1999 Insert_Actions (N, New_List ( 2000 Make_Object_Declaration (Loc, 2001 Defining_Identifier => Result_Ent, 2002 Object_Definition => New_Occurrence_Of (Rtyp, Loc)), 2003 2004 Make_Procedure_Call_Statement (Loc, 2005 Name => New_Occurrence_Of (RTE (RE_Bit_Not), Loc), 2006 Parameter_Associations => New_List ( 2007 Make_Byte_Aligned_Attribute_Reference (Loc, 2008 Prefix => Opnd, 2009 Attribute_Name => Name_Address), 2010 2011 Make_Op_Multiply (Loc, 2012 Left_Opnd => 2013 Make_Attribute_Reference (Loc, 2014 Prefix => 2015 New_Occurrence_Of 2016 (Etype (First_Index (Rtyp)), Loc), 2017 Attribute_Name => Name_Range_Length), 2018 2019 Right_Opnd => 2020 Make_Integer_Literal (Loc, Component_Size (Rtyp))), 2021 2022 Make_Byte_Aligned_Attribute_Reference (Loc, 2023 Prefix => New_Occurrence_Of (Result_Ent, Loc), 2024 Attribute_Name => Name_Address))))); 2025 2026 Rewrite (N, New_Occurrence_Of (Result_Ent, Loc)); 2027 end; 2028 end if; 2029 2030 Analyze_And_Resolve (N, Typ, Suppress => All_Checks); 2031 end Expand_Packed_Not; 2032 2033 ----------------------------- 2034 -- Get_Base_And_Bit_Offset -- 2035 ----------------------------- 2036 2037 procedure Get_Base_And_Bit_Offset 2038 (N : Node_Id; 2039 Base : out Node_Id; 2040 Offset : out Node_Id) 2041 is 2042 Loc : Source_Ptr; 2043 Term : Node_Id; 2044 Atyp : Entity_Id; 2045 Subscr : Node_Id; 2046 2047 begin 2048 Base := N; 2049 Offset := Empty; 2050 2051 -- We build up an expression serially that has the form 2052 2053 -- linear-subscript * component_size for each array reference 2054 -- + field'Bit_Position for each record field 2055 -- + ... 2056 2057 loop 2058 Loc := Sloc (Base); 2059 2060 if Nkind (Base) = N_Indexed_Component then 2061 Convert_To_Actual_Subtype (Prefix (Base)); 2062 Atyp := Etype (Prefix (Base)); 2063 Compute_Linear_Subscript (Atyp, Base, Subscr); 2064 2065 Term := 2066 Make_Op_Multiply (Loc, 2067 Left_Opnd => Subscr, 2068 Right_Opnd => 2069 Make_Attribute_Reference (Loc, 2070 Prefix => New_Occurrence_Of (Atyp, Loc), 2071 Attribute_Name => Name_Component_Size)); 2072 2073 elsif Nkind (Base) = N_Selected_Component then 2074 Term := 2075 Make_Attribute_Reference (Loc, 2076 Prefix => Selector_Name (Base), 2077 Attribute_Name => Name_Bit_Position); 2078 2079 else 2080 return; 2081 end if; 2082 2083 if No (Offset) then 2084 Offset := Term; 2085 2086 else 2087 Offset := 2088 Make_Op_Add (Loc, 2089 Left_Opnd => Offset, 2090 Right_Opnd => Term); 2091 end if; 2092 2093 Base := Prefix (Base); 2094 end loop; 2095 end Get_Base_And_Bit_Offset; 2096 2097 ------------------------------------- 2098 -- Involves_Packed_Array_Reference -- 2099 ------------------------------------- 2100 2101 function Involves_Packed_Array_Reference (N : Node_Id) return Boolean is 2102 begin 2103 if Nkind (N) = N_Indexed_Component 2104 and then Is_Bit_Packed_Array (Etype (Prefix (N))) 2105 then 2106 return True; 2107 2108 elsif Nkind (N) = N_Selected_Component then 2109 return Involves_Packed_Array_Reference (Prefix (N)); 2110 2111 else 2112 return False; 2113 end if; 2114 end Involves_Packed_Array_Reference; 2115 2116 -------------------------- 2117 -- Known_Aligned_Enough -- 2118 -------------------------- 2119 2120 function Known_Aligned_Enough (Obj : Node_Id; Csiz : Nat) return Boolean is 2121 Typ : constant Entity_Id := Etype (Obj); 2122 2123 function In_Partially_Packed_Record (Comp : Entity_Id) return Boolean; 2124 -- If the component is in a record that contains previous packed 2125 -- components, consider it unaligned because the back-end might 2126 -- choose to pack the rest of the record. Lead to less efficient code, 2127 -- but safer vis-a-vis of back-end choices. 2128 2129 -------------------------------- 2130 -- In_Partially_Packed_Record -- 2131 -------------------------------- 2132 2133 function In_Partially_Packed_Record (Comp : Entity_Id) return Boolean is 2134 Rec_Type : constant Entity_Id := Scope (Comp); 2135 Prev_Comp : Entity_Id; 2136 2137 begin 2138 Prev_Comp := First_Entity (Rec_Type); 2139 while Present (Prev_Comp) loop 2140 if Is_Packed (Etype (Prev_Comp)) then 2141 return True; 2142 2143 elsif Prev_Comp = Comp then 2144 return False; 2145 end if; 2146 2147 Next_Entity (Prev_Comp); 2148 end loop; 2149 2150 return False; 2151 end In_Partially_Packed_Record; 2152 2153 -- Start of processing for Known_Aligned_Enough 2154 2155 begin 2156 -- Odd bit sizes don't need alignment anyway 2157 2158 if Csiz mod 2 = 1 then 2159 return True; 2160 2161 -- If we have a specified alignment, see if it is sufficient, if not 2162 -- then we can't possibly be aligned enough in any case. 2163 2164 elsif Known_Alignment (Etype (Obj)) then 2165 -- Alignment required is 4 if size is a multiple of 4, and 2166 -- 2 otherwise (e.g. 12 bits requires 4, 10 bits requires 2) 2167 2168 if Alignment (Etype (Obj)) < 4 - (Csiz mod 4) then 2169 return False; 2170 end if; 2171 end if; 2172 2173 -- OK, alignment should be sufficient, if object is aligned 2174 2175 -- If object is strictly aligned, then it is definitely aligned 2176 2177 if Strict_Alignment (Typ) then 2178 return True; 2179 2180 -- Case of subscripted array reference 2181 2182 elsif Nkind (Obj) = N_Indexed_Component then 2183 2184 -- If we have a pointer to an array, then this is definitely 2185 -- aligned, because pointers always point to aligned versions. 2186 2187 if Is_Access_Type (Etype (Prefix (Obj))) then 2188 return True; 2189 2190 -- Otherwise, go look at the prefix 2191 2192 else 2193 return Known_Aligned_Enough (Prefix (Obj), Csiz); 2194 end if; 2195 2196 -- Case of record field 2197 2198 elsif Nkind (Obj) = N_Selected_Component then 2199 2200 -- What is significant here is whether the record type is packed 2201 2202 if Is_Record_Type (Etype (Prefix (Obj))) 2203 and then Is_Packed (Etype (Prefix (Obj))) 2204 then 2205 return False; 2206 2207 -- Or the component has a component clause which might cause 2208 -- the component to become unaligned (we can't tell if the 2209 -- backend is doing alignment computations). 2210 2211 elsif Present (Component_Clause (Entity (Selector_Name (Obj)))) then 2212 return False; 2213 2214 elsif In_Partially_Packed_Record (Entity (Selector_Name (Obj))) then 2215 return False; 2216 2217 -- In all other cases, go look at prefix 2218 2219 else 2220 return Known_Aligned_Enough (Prefix (Obj), Csiz); 2221 end if; 2222 2223 elsif Nkind (Obj) = N_Type_Conversion then 2224 return Known_Aligned_Enough (Expression (Obj), Csiz); 2225 2226 -- For a formal parameter, it is safer to assume that it is not 2227 -- aligned, because the formal may be unconstrained while the actual 2228 -- is constrained. In this situation, a small constrained packed 2229 -- array, represented in modular form, may be unaligned. 2230 2231 elsif Is_Entity_Name (Obj) then 2232 return not Is_Formal (Entity (Obj)); 2233 else 2234 2235 -- If none of the above, must be aligned 2236 return True; 2237 end if; 2238 end Known_Aligned_Enough; 2239 2240 --------------------- 2241 -- Make_Shift_Left -- 2242 --------------------- 2243 2244 function Make_Shift_Left (N : Node_Id; S : Node_Id) return Node_Id is 2245 Nod : Node_Id; 2246 2247 begin 2248 if Compile_Time_Known_Value (S) and then Expr_Value (S) = 0 then 2249 return N; 2250 else 2251 Nod := 2252 Make_Op_Shift_Left (Sloc (N), 2253 Left_Opnd => N, 2254 Right_Opnd => S); 2255 Set_Shift_Count_OK (Nod, True); 2256 return Nod; 2257 end if; 2258 end Make_Shift_Left; 2259 2260 ---------------------- 2261 -- Make_Shift_Right -- 2262 ---------------------- 2263 2264 function Make_Shift_Right (N : Node_Id; S : Node_Id) return Node_Id is 2265 Nod : Node_Id; 2266 2267 begin 2268 if Compile_Time_Known_Value (S) and then Expr_Value (S) = 0 then 2269 return N; 2270 else 2271 Nod := 2272 Make_Op_Shift_Right (Sloc (N), 2273 Left_Opnd => N, 2274 Right_Opnd => S); 2275 Set_Shift_Count_OK (Nod, True); 2276 return Nod; 2277 end if; 2278 end Make_Shift_Right; 2279 2280 ----------------------------- 2281 -- RJ_Unchecked_Convert_To -- 2282 ----------------------------- 2283 2284 function RJ_Unchecked_Convert_To 2285 (Typ : Entity_Id; 2286 Expr : Node_Id) return Node_Id 2287 is 2288 Source_Typ : constant Entity_Id := Etype (Expr); 2289 Target_Typ : constant Entity_Id := Typ; 2290 2291 Src : Node_Id := Expr; 2292 2293 Source_Siz : Nat; 2294 Target_Siz : Nat; 2295 2296 begin 2297 Source_Siz := UI_To_Int (RM_Size (Source_Typ)); 2298 Target_Siz := UI_To_Int (RM_Size (Target_Typ)); 2299 2300 -- For a little-endian target type stored byte-swapped on a 2301 -- big-endian machine, do not mask to Target_Siz bits. 2302 2303 if Bytes_Big_Endian 2304 and then (Is_Record_Type (Target_Typ) 2305 or else 2306 Is_Array_Type (Target_Typ)) 2307 and then Reverse_Storage_Order (Target_Typ) 2308 then 2309 Source_Siz := Target_Siz; 2310 end if; 2311 2312 -- First step, if the source type is not a discrete type, then we first 2313 -- convert to a modular type of the source length, since otherwise, on 2314 -- a big-endian machine, we get left-justification. We do it for little- 2315 -- endian machines as well, because there might be junk bits that are 2316 -- not cleared if the type is not numeric. 2317 2318 if Source_Siz /= Target_Siz 2319 and then not Is_Discrete_Type (Source_Typ) 2320 then 2321 Src := Unchecked_Convert_To (RTE (Bits_Id (Source_Siz)), Src); 2322 end if; 2323 2324 -- In the big endian case, if the lengths of the two types differ, then 2325 -- we must worry about possible left justification in the conversion, 2326 -- and avoiding that is what this is all about. 2327 2328 if Bytes_Big_Endian and then Source_Siz /= Target_Siz then 2329 2330 -- Next step. If the target is not a discrete type, then we first 2331 -- convert to a modular type of the target length, since otherwise, 2332 -- on a big-endian machine, we get left-justification. 2333 2334 if not Is_Discrete_Type (Target_Typ) then 2335 Src := Unchecked_Convert_To (RTE (Bits_Id (Target_Siz)), Src); 2336 end if; 2337 end if; 2338 2339 -- And now we can do the final conversion to the target type 2340 2341 return Unchecked_Convert_To (Target_Typ, Src); 2342 end RJ_Unchecked_Convert_To; 2343 2344 ---------------------------------------------- 2345 -- Setup_Enumeration_Packed_Array_Reference -- 2346 ---------------------------------------------- 2347 2348 -- All we have to do here is to find the subscripts that correspond to the 2349 -- index positions that have non-standard enumeration types and insert a 2350 -- Pos attribute to get the proper subscript value. 2351 2352 -- Finally the prefix must be uncheck-converted to the corresponding packed 2353 -- array type. 2354 2355 -- Note that the component type is unchanged, so we do not need to fiddle 2356 -- with the types (Gigi always automatically takes the packed array type if 2357 -- it is set, as it will be in this case). 2358 2359 procedure Setup_Enumeration_Packed_Array_Reference (N : Node_Id) is 2360 Pfx : constant Node_Id := Prefix (N); 2361 Typ : constant Entity_Id := Etype (N); 2362 Exprs : constant List_Id := Expressions (N); 2363 Expr : Node_Id; 2364 2365 begin 2366 -- If the array is unconstrained, then we replace the array reference 2367 -- with its actual subtype. This actual subtype will have a packed array 2368 -- type with appropriate bounds. 2369 2370 if not Is_Constrained (Packed_Array_Impl_Type (Etype (Pfx))) then 2371 Convert_To_Actual_Subtype (Pfx); 2372 end if; 2373 2374 Expr := First (Exprs); 2375 while Present (Expr) loop 2376 declare 2377 Loc : constant Source_Ptr := Sloc (Expr); 2378 Expr_Typ : constant Entity_Id := Etype (Expr); 2379 2380 begin 2381 if Is_Enumeration_Type (Expr_Typ) 2382 and then Has_Non_Standard_Rep (Expr_Typ) 2383 then 2384 Rewrite (Expr, 2385 Make_Attribute_Reference (Loc, 2386 Prefix => New_Occurrence_Of (Expr_Typ, Loc), 2387 Attribute_Name => Name_Pos, 2388 Expressions => New_List (Relocate_Node (Expr)))); 2389 Analyze_And_Resolve (Expr, Standard_Natural); 2390 end if; 2391 end; 2392 2393 Next (Expr); 2394 end loop; 2395 2396 Rewrite (N, 2397 Make_Indexed_Component (Sloc (N), 2398 Prefix => 2399 Unchecked_Convert_To (Packed_Array_Impl_Type (Etype (Pfx)), Pfx), 2400 Expressions => Exprs)); 2401 2402 Analyze_And_Resolve (N, Typ); 2403 end Setup_Enumeration_Packed_Array_Reference; 2404 2405 ----------------------------------------- 2406 -- Setup_Inline_Packed_Array_Reference -- 2407 ----------------------------------------- 2408 2409 procedure Setup_Inline_Packed_Array_Reference 2410 (N : Node_Id; 2411 Atyp : Entity_Id; 2412 Obj : in out Node_Id; 2413 Cmask : out Uint; 2414 Shift : out Node_Id) 2415 is 2416 Loc : constant Source_Ptr := Sloc (N); 2417 PAT : Entity_Id; 2418 Otyp : Entity_Id; 2419 Csiz : Uint; 2420 Osiz : Uint; 2421 2422 begin 2423 Csiz := Component_Size (Atyp); 2424 2425 Convert_To_PAT_Type (Obj); 2426 PAT := Etype (Obj); 2427 2428 Cmask := 2 ** Csiz - 1; 2429 2430 if Is_Array_Type (PAT) then 2431 Otyp := Component_Type (PAT); 2432 Osiz := Component_Size (PAT); 2433 2434 else 2435 Otyp := PAT; 2436 2437 -- In the case where the PAT is a modular type, we want the actual 2438 -- size in bits of the modular value we use. This is neither the 2439 -- Object_Size nor the Value_Size, either of which may have been 2440 -- reset to strange values, but rather the minimum size. Note that 2441 -- since this is a modular type with full range, the issue of 2442 -- biased representation does not arise. 2443 2444 Osiz := UI_From_Int (Minimum_Size (Otyp)); 2445 end if; 2446 2447 Compute_Linear_Subscript (Atyp, N, Shift); 2448 2449 -- If the component size is not 1, then the subscript must be multiplied 2450 -- by the component size to get the shift count. 2451 2452 if Csiz /= 1 then 2453 Shift := 2454 Make_Op_Multiply (Loc, 2455 Left_Opnd => Make_Integer_Literal (Loc, Csiz), 2456 Right_Opnd => Shift); 2457 end if; 2458 2459 -- If we have the array case, then this shift count must be broken down 2460 -- into a byte subscript, and a shift within the byte. 2461 2462 if Is_Array_Type (PAT) then 2463 2464 declare 2465 New_Shift : Node_Id; 2466 2467 begin 2468 -- We must analyze shift, since we will duplicate it 2469 2470 Set_Parent (Shift, N); 2471 Analyze_And_Resolve 2472 (Shift, Standard_Integer, Suppress => All_Checks); 2473 2474 -- The shift count within the word is 2475 -- shift mod Osiz 2476 2477 New_Shift := 2478 Make_Op_Mod (Loc, 2479 Left_Opnd => Duplicate_Subexpr (Shift), 2480 Right_Opnd => Make_Integer_Literal (Loc, Osiz)); 2481 2482 -- The subscript to be used on the PAT array is 2483 -- shift / Osiz 2484 2485 Obj := 2486 Make_Indexed_Component (Loc, 2487 Prefix => Obj, 2488 Expressions => New_List ( 2489 Make_Op_Divide (Loc, 2490 Left_Opnd => Duplicate_Subexpr (Shift), 2491 Right_Opnd => Make_Integer_Literal (Loc, Osiz)))); 2492 2493 Shift := New_Shift; 2494 end; 2495 2496 -- For the modular integer case, the object to be manipulated is the 2497 -- entire array, so Obj is unchanged. Note that we will reset its type 2498 -- to PAT before returning to the caller. 2499 2500 else 2501 null; 2502 end if; 2503 2504 -- The one remaining step is to modify the shift count for the 2505 -- big-endian case. Consider the following example in a byte: 2506 2507 -- xxxxxxxx bits of byte 2508 -- vvvvvvvv bits of value 2509 -- 33221100 little-endian numbering 2510 -- 00112233 big-endian numbering 2511 2512 -- Here we have the case of 2-bit fields 2513 2514 -- For the little-endian case, we already have the proper shift count 2515 -- set, e.g. for element 2, the shift count is 2*2 = 4. 2516 2517 -- For the big endian case, we have to adjust the shift count, computing 2518 -- it as (N - F) - Shift, where N is the number of bits in an element of 2519 -- the array used to implement the packed array, F is the number of bits 2520 -- in a source array element, and Shift is the count so far computed. 2521 2522 -- We also have to adjust if the storage order is reversed 2523 2524 if Bytes_Big_Endian xor Reverse_Storage_Order (Base_Type (Atyp)) then 2525 Shift := 2526 Make_Op_Subtract (Loc, 2527 Left_Opnd => Make_Integer_Literal (Loc, Osiz - Csiz), 2528 Right_Opnd => Shift); 2529 end if; 2530 2531 Set_Parent (Shift, N); 2532 Set_Parent (Obj, N); 2533 Analyze_And_Resolve (Obj, Otyp, Suppress => All_Checks); 2534 Analyze_And_Resolve (Shift, Standard_Integer, Suppress => All_Checks); 2535 2536 -- Make sure final type of object is the appropriate packed type 2537 2538 Set_Etype (Obj, Otyp); 2539 2540 end Setup_Inline_Packed_Array_Reference; 2541 2542end Exp_Pakd; 2543