1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- E X P _ C H 5 -- 6-- -- 7-- B o d y -- 8-- -- 9-- Copyright (C) 1992-2013, 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 Aspects; use Aspects; 27with Atree; use Atree; 28with Checks; use Checks; 29with Debug; use Debug; 30with Einfo; use Einfo; 31with Elists; use Elists; 32with Errout; use Errout; 33with Exp_Aggr; use Exp_Aggr; 34with Exp_Ch6; use Exp_Ch6; 35with Exp_Ch7; use Exp_Ch7; 36with Exp_Ch11; use Exp_Ch11; 37with Exp_Dbug; use Exp_Dbug; 38with Exp_Pakd; use Exp_Pakd; 39with Exp_Tss; use Exp_Tss; 40with Exp_Util; use Exp_Util; 41with Namet; use Namet; 42with Nlists; use Nlists; 43with Nmake; use Nmake; 44with Opt; use Opt; 45with Restrict; use Restrict; 46with Rident; use Rident; 47with Rtsfind; use Rtsfind; 48with Sinfo; use Sinfo; 49with Sem; use Sem; 50with Sem_Aux; use Sem_Aux; 51with Sem_Ch3; use Sem_Ch3; 52with Sem_Ch8; use Sem_Ch8; 53with Sem_Ch13; use Sem_Ch13; 54with Sem_Eval; use Sem_Eval; 55with Sem_Res; use Sem_Res; 56with Sem_Util; use Sem_Util; 57with Snames; use Snames; 58with Stand; use Stand; 59with Stringt; use Stringt; 60with Targparm; use Targparm; 61with Tbuild; use Tbuild; 62with Validsw; use Validsw; 63 64package body Exp_Ch5 is 65 66 function Change_Of_Representation (N : Node_Id) return Boolean; 67 -- Determine if the right hand side of assignment N is a type conversion 68 -- which requires a change of representation. Called only for the array 69 -- and record cases. 70 71 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id); 72 -- N is an assignment which assigns an array value. This routine process 73 -- the various special cases and checks required for such assignments, 74 -- including change of representation. Rhs is normally simply the right 75 -- hand side of the assignment, except that if the right hand side is a 76 -- type conversion or a qualified expression, then the RHS is the actual 77 -- expression inside any such type conversions or qualifications. 78 79 function Expand_Assign_Array_Loop 80 (N : Node_Id; 81 Larray : Entity_Id; 82 Rarray : Entity_Id; 83 L_Type : Entity_Id; 84 R_Type : Entity_Id; 85 Ndim : Pos; 86 Rev : Boolean) return Node_Id; 87 -- N is an assignment statement which assigns an array value. This routine 88 -- expands the assignment into a loop (or nested loops for the case of a 89 -- multi-dimensional array) to do the assignment component by component. 90 -- Larray and Rarray are the entities of the actual arrays on the left 91 -- hand and right hand sides. L_Type and R_Type are the types of these 92 -- arrays (which may not be the same, due to either sliding, or to a 93 -- change of representation case). Ndim is the number of dimensions and 94 -- the parameter Rev indicates if the loops run normally (Rev = False), 95 -- or reversed (Rev = True). The value returned is the constructed 96 -- loop statement. Auxiliary declarations are inserted before node N 97 -- using the standard Insert_Actions mechanism. 98 99 procedure Expand_Assign_Record (N : Node_Id); 100 -- N is an assignment of a non-tagged record value. This routine handles 101 -- the case where the assignment must be made component by component, 102 -- either because the target is not byte aligned, or there is a change 103 -- of representation, or when we have a tagged type with a representation 104 -- clause (this last case is required because holes in the tagged type 105 -- might be filled with components from child types). 106 107 procedure Expand_Iterator_Loop (N : Node_Id); 108 -- Expand loop over arrays and containers that uses the form "for X of C" 109 -- with an optional subtype mark, or "for Y in C". 110 111 procedure Expand_Iterator_Loop_Over_Array (N : Node_Id); 112 -- Expand loop over arrays that uses the form "for X of C" 113 114 procedure Expand_Loop_Entry_Attributes (N : Node_Id); 115 -- Given a loop statement subject to at least one Loop_Entry attribute, 116 -- expand both the loop and all related Loop_Entry references. 117 118 procedure Expand_Predicated_Loop (N : Node_Id); 119 -- Expand for loop over predicated subtype 120 121 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id; 122 -- Generate the necessary code for controlled and tagged assignment, that 123 -- is to say, finalization of the target before, adjustment of the target 124 -- after and save and restore of the tag and finalization pointers which 125 -- are not 'part of the value' and must not be changed upon assignment. N 126 -- is the original Assignment node. 127 128 ------------------------------ 129 -- Change_Of_Representation -- 130 ------------------------------ 131 132 function Change_Of_Representation (N : Node_Id) return Boolean is 133 Rhs : constant Node_Id := Expression (N); 134 begin 135 return 136 Nkind (Rhs) = N_Type_Conversion 137 and then 138 not Same_Representation (Etype (Rhs), Etype (Expression (Rhs))); 139 end Change_Of_Representation; 140 141 ------------------------- 142 -- Expand_Assign_Array -- 143 ------------------------- 144 145 -- There are two issues here. First, do we let Gigi do a block move, or 146 -- do we expand out into a loop? Second, we need to set the two flags 147 -- Forwards_OK and Backwards_OK which show whether the block move (or 148 -- corresponding loops) can be legitimately done in a forwards (low to 149 -- high) or backwards (high to low) manner. 150 151 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is 152 Loc : constant Source_Ptr := Sloc (N); 153 154 Lhs : constant Node_Id := Name (N); 155 156 Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs); 157 Act_Rhs : Node_Id := Get_Referenced_Object (Rhs); 158 159 L_Type : constant Entity_Id := 160 Underlying_Type (Get_Actual_Subtype (Act_Lhs)); 161 R_Type : Entity_Id := 162 Underlying_Type (Get_Actual_Subtype (Act_Rhs)); 163 164 L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice; 165 R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice; 166 167 Crep : constant Boolean := Change_Of_Representation (N); 168 169 Larray : Node_Id; 170 Rarray : Node_Id; 171 172 Ndim : constant Pos := Number_Dimensions (L_Type); 173 174 Loop_Required : Boolean := False; 175 -- This switch is set to True if the array move must be done using 176 -- an explicit front end generated loop. 177 178 procedure Apply_Dereference (Arg : Node_Id); 179 -- If the argument is an access to an array, and the assignment is 180 -- converted into a procedure call, apply explicit dereference. 181 182 function Has_Address_Clause (Exp : Node_Id) return Boolean; 183 -- Test if Exp is a reference to an array whose declaration has 184 -- an address clause, or it is a slice of such an array. 185 186 function Is_Formal_Array (Exp : Node_Id) return Boolean; 187 -- Test if Exp is a reference to an array which is either a formal 188 -- parameter or a slice of a formal parameter. These are the cases 189 -- where hidden aliasing can occur. 190 191 function Is_Non_Local_Array (Exp : Node_Id) return Boolean; 192 -- Determine if Exp is a reference to an array variable which is other 193 -- than an object defined in the current scope, or a slice of such 194 -- an object. Such objects can be aliased to parameters (unlike local 195 -- array references). 196 197 ----------------------- 198 -- Apply_Dereference -- 199 ----------------------- 200 201 procedure Apply_Dereference (Arg : Node_Id) is 202 Typ : constant Entity_Id := Etype (Arg); 203 begin 204 if Is_Access_Type (Typ) then 205 Rewrite (Arg, Make_Explicit_Dereference (Loc, 206 Prefix => Relocate_Node (Arg))); 207 Analyze_And_Resolve (Arg, Designated_Type (Typ)); 208 end if; 209 end Apply_Dereference; 210 211 ------------------------ 212 -- Has_Address_Clause -- 213 ------------------------ 214 215 function Has_Address_Clause (Exp : Node_Id) return Boolean is 216 begin 217 return 218 (Is_Entity_Name (Exp) and then 219 Present (Address_Clause (Entity (Exp)))) 220 or else 221 (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp))); 222 end Has_Address_Clause; 223 224 --------------------- 225 -- Is_Formal_Array -- 226 --------------------- 227 228 function Is_Formal_Array (Exp : Node_Id) return Boolean is 229 begin 230 return 231 (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp))) 232 or else 233 (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp))); 234 end Is_Formal_Array; 235 236 ------------------------ 237 -- Is_Non_Local_Array -- 238 ------------------------ 239 240 function Is_Non_Local_Array (Exp : Node_Id) return Boolean is 241 begin 242 return (Is_Entity_Name (Exp) 243 and then Scope (Entity (Exp)) /= Current_Scope) 244 or else (Nkind (Exp) = N_Slice 245 and then Is_Non_Local_Array (Prefix (Exp))); 246 end Is_Non_Local_Array; 247 248 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays 249 250 Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs); 251 Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs); 252 253 Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs); 254 Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs); 255 256 -- Start of processing for Expand_Assign_Array 257 258 begin 259 -- Deal with length check. Note that the length check is done with 260 -- respect to the right hand side as given, not a possible underlying 261 -- renamed object, since this would generate incorrect extra checks. 262 263 Apply_Length_Check (Rhs, L_Type); 264 265 -- We start by assuming that the move can be done in either direction, 266 -- i.e. that the two sides are completely disjoint. 267 268 Set_Forwards_OK (N, True); 269 Set_Backwards_OK (N, True); 270 271 -- Normally it is only the slice case that can lead to overlap, and 272 -- explicit checks for slices are made below. But there is one case 273 -- where the slice can be implicit and invisible to us: when we have a 274 -- one dimensional array, and either both operands are parameters, or 275 -- one is a parameter (which can be a slice passed by reference) and the 276 -- other is a non-local variable. In this case the parameter could be a 277 -- slice that overlaps with the other operand. 278 279 -- However, if the array subtype is a constrained first subtype in the 280 -- parameter case, then we don't have to worry about overlap, since 281 -- slice assignments aren't possible (other than for a slice denoting 282 -- the whole array). 283 284 -- Note: No overlap is possible if there is a change of representation, 285 -- so we can exclude this case. 286 287 if Ndim = 1 288 and then not Crep 289 and then 290 ((Lhs_Formal and Rhs_Formal) 291 or else 292 (Lhs_Formal and Rhs_Non_Local_Var) 293 or else 294 (Rhs_Formal and Lhs_Non_Local_Var)) 295 and then 296 (not Is_Constrained (Etype (Lhs)) 297 or else not Is_First_Subtype (Etype (Lhs))) 298 299 -- In the case of compiling for the Java or .NET Virtual Machine, 300 -- slices are always passed by making a copy, so we don't have to 301 -- worry about overlap. We also want to prevent generation of "<" 302 -- comparisons for array addresses, since that's a meaningless 303 -- operation on the VM. 304 305 and then VM_Target = No_VM 306 then 307 Set_Forwards_OK (N, False); 308 Set_Backwards_OK (N, False); 309 310 -- Note: the bit-packed case is not worrisome here, since if we have 311 -- a slice passed as a parameter, it is always aligned on a byte 312 -- boundary, and if there are no explicit slices, the assignment 313 -- can be performed directly. 314 end if; 315 316 -- If either operand has an address clause clear Backwards_OK and 317 -- Forwards_OK, since we cannot tell if the operands overlap. We 318 -- exclude this treatment when Rhs is an aggregate, since we know 319 -- that overlap can't occur. 320 321 if (Has_Address_Clause (Lhs) and then Nkind (Rhs) /= N_Aggregate) 322 or else Has_Address_Clause (Rhs) 323 then 324 Set_Forwards_OK (N, False); 325 Set_Backwards_OK (N, False); 326 end if; 327 328 -- We certainly must use a loop for change of representation and also 329 -- we use the operand of the conversion on the right hand side as the 330 -- effective right hand side (the component types must match in this 331 -- situation). 332 333 if Crep then 334 Act_Rhs := Get_Referenced_Object (Rhs); 335 R_Type := Get_Actual_Subtype (Act_Rhs); 336 Loop_Required := True; 337 338 -- We require a loop if the left side is possibly bit unaligned 339 340 elsif Possible_Bit_Aligned_Component (Lhs) 341 or else 342 Possible_Bit_Aligned_Component (Rhs) 343 then 344 Loop_Required := True; 345 346 -- Arrays with controlled components are expanded into a loop to force 347 -- calls to Adjust at the component level. 348 349 elsif Has_Controlled_Component (L_Type) then 350 Loop_Required := True; 351 352 -- If object is atomic, we cannot tolerate a loop 353 354 elsif Is_Atomic_Object (Act_Lhs) 355 or else 356 Is_Atomic_Object (Act_Rhs) 357 then 358 return; 359 360 -- Loop is required if we have atomic components since we have to 361 -- be sure to do any accesses on an element by element basis. 362 363 elsif Has_Atomic_Components (L_Type) 364 or else Has_Atomic_Components (R_Type) 365 or else Is_Atomic (Component_Type (L_Type)) 366 or else Is_Atomic (Component_Type (R_Type)) 367 then 368 Loop_Required := True; 369 370 -- Case where no slice is involved 371 372 elsif not L_Slice and not R_Slice then 373 374 -- The following code deals with the case of unconstrained bit packed 375 -- arrays. The problem is that the template for such arrays contains 376 -- the bounds of the actual source level array, but the copy of an 377 -- entire array requires the bounds of the underlying array. It would 378 -- be nice if the back end could take care of this, but right now it 379 -- does not know how, so if we have such a type, then we expand out 380 -- into a loop, which is inefficient but works correctly. If we don't 381 -- do this, we get the wrong length computed for the array to be 382 -- moved. The two cases we need to worry about are: 383 384 -- Explicit dereference of an unconstrained packed array type as in 385 -- the following example: 386 387 -- procedure C52 is 388 -- type BITS is array(INTEGER range <>) of BOOLEAN; 389 -- pragma PACK(BITS); 390 -- type A is access BITS; 391 -- P1,P2 : A; 392 -- begin 393 -- P1 := new BITS (1 .. 65_535); 394 -- P2 := new BITS (1 .. 65_535); 395 -- P2.ALL := P1.ALL; 396 -- end C52; 397 398 -- A formal parameter reference with an unconstrained bit array type 399 -- is the other case we need to worry about (here we assume the same 400 -- BITS type declared above): 401 402 -- procedure Write_All (File : out BITS; Contents : BITS); 403 -- begin 404 -- File.Storage := Contents; 405 -- end Write_All; 406 407 -- We expand to a loop in either of these two cases 408 409 -- Question for future thought. Another potentially more efficient 410 -- approach would be to create the actual subtype, and then do an 411 -- unchecked conversion to this actual subtype ??? 412 413 Check_Unconstrained_Bit_Packed_Array : declare 414 415 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean; 416 -- Function to perform required test for the first case, above 417 -- (dereference of an unconstrained bit packed array). 418 419 ----------------------- 420 -- Is_UBPA_Reference -- 421 ----------------------- 422 423 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is 424 Typ : constant Entity_Id := Underlying_Type (Etype (Opnd)); 425 P_Type : Entity_Id; 426 Des_Type : Entity_Id; 427 428 begin 429 if Present (Packed_Array_Type (Typ)) 430 and then Is_Array_Type (Packed_Array_Type (Typ)) 431 and then not Is_Constrained (Packed_Array_Type (Typ)) 432 then 433 return True; 434 435 elsif Nkind (Opnd) = N_Explicit_Dereference then 436 P_Type := Underlying_Type (Etype (Prefix (Opnd))); 437 438 if not Is_Access_Type (P_Type) then 439 return False; 440 441 else 442 Des_Type := Designated_Type (P_Type); 443 return 444 Is_Bit_Packed_Array (Des_Type) 445 and then not Is_Constrained (Des_Type); 446 end if; 447 448 else 449 return False; 450 end if; 451 end Is_UBPA_Reference; 452 453 -- Start of processing for Check_Unconstrained_Bit_Packed_Array 454 455 begin 456 if Is_UBPA_Reference (Lhs) 457 or else 458 Is_UBPA_Reference (Rhs) 459 then 460 Loop_Required := True; 461 462 -- Here if we do not have the case of a reference to a bit packed 463 -- unconstrained array case. In this case gigi can most certainly 464 -- handle the assignment if a forwards move is allowed. 465 466 -- (could it handle the backwards case also???) 467 468 elsif Forwards_OK (N) then 469 return; 470 end if; 471 end Check_Unconstrained_Bit_Packed_Array; 472 473 -- The back end can always handle the assignment if the right side is a 474 -- string literal (note that overlap is definitely impossible in this 475 -- case). If the type is packed, a string literal is always converted 476 -- into an aggregate, except in the case of a null slice, for which no 477 -- aggregate can be written. In that case, rewrite the assignment as a 478 -- null statement, a length check has already been emitted to verify 479 -- that the range of the left-hand side is empty. 480 481 -- Note that this code is not executed if we have an assignment of a 482 -- string literal to a non-bit aligned component of a record, a case 483 -- which cannot be handled by the backend. 484 485 elsif Nkind (Rhs) = N_String_Literal then 486 if String_Length (Strval (Rhs)) = 0 487 and then Is_Bit_Packed_Array (L_Type) 488 then 489 Rewrite (N, Make_Null_Statement (Loc)); 490 Analyze (N); 491 end if; 492 493 return; 494 495 -- If either operand is bit packed, then we need a loop, since we can't 496 -- be sure that the slice is byte aligned. Similarly, if either operand 497 -- is a possibly unaligned slice, then we need a loop (since the back 498 -- end cannot handle unaligned slices). 499 500 elsif Is_Bit_Packed_Array (L_Type) 501 or else Is_Bit_Packed_Array (R_Type) 502 or else Is_Possibly_Unaligned_Slice (Lhs) 503 or else Is_Possibly_Unaligned_Slice (Rhs) 504 then 505 Loop_Required := True; 506 507 -- If we are not bit-packed, and we have only one slice, then no overlap 508 -- is possible except in the parameter case, so we can let the back end 509 -- handle things. 510 511 elsif not (L_Slice and R_Slice) then 512 if Forwards_OK (N) then 513 return; 514 end if; 515 end if; 516 517 -- If the right-hand side is a string literal, introduce a temporary for 518 -- it, for use in the generated loop that will follow. 519 520 if Nkind (Rhs) = N_String_Literal then 521 declare 522 Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Rhs); 523 Decl : Node_Id; 524 525 begin 526 Decl := 527 Make_Object_Declaration (Loc, 528 Defining_Identifier => Temp, 529 Object_Definition => New_Occurrence_Of (L_Type, Loc), 530 Expression => Relocate_Node (Rhs)); 531 532 Insert_Action (N, Decl); 533 Rewrite (Rhs, New_Occurrence_Of (Temp, Loc)); 534 R_Type := Etype (Temp); 535 end; 536 end if; 537 538 -- Come here to complete the analysis 539 540 -- Loop_Required: Set to True if we know that a loop is required 541 -- regardless of overlap considerations. 542 543 -- Forwards_OK: Set to False if we already know that a forwards 544 -- move is not safe, else set to True. 545 546 -- Backwards_OK: Set to False if we already know that a backwards 547 -- move is not safe, else set to True 548 549 -- Our task at this stage is to complete the overlap analysis, which can 550 -- result in possibly setting Forwards_OK or Backwards_OK to False, and 551 -- then generating the final code, either by deciding that it is OK 552 -- after all to let Gigi handle it, or by generating appropriate code 553 -- in the front end. 554 555 declare 556 L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type)); 557 R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type)); 558 559 Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ); 560 Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ); 561 Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ); 562 Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ); 563 564 Act_L_Array : Node_Id; 565 Act_R_Array : Node_Id; 566 567 Cleft_Lo : Node_Id; 568 Cright_Lo : Node_Id; 569 Condition : Node_Id; 570 571 Cresult : Compare_Result; 572 573 begin 574 -- Get the expressions for the arrays. If we are dealing with a 575 -- private type, then convert to the underlying type. We can do 576 -- direct assignments to an array that is a private type, but we 577 -- cannot assign to elements of the array without this extra 578 -- unchecked conversion. 579 580 -- Note: We propagate Parent to the conversion nodes to generate 581 -- a well-formed subtree. 582 583 if Nkind (Act_Lhs) = N_Slice then 584 Larray := Prefix (Act_Lhs); 585 else 586 Larray := Act_Lhs; 587 588 if Is_Private_Type (Etype (Larray)) then 589 declare 590 Par : constant Node_Id := Parent (Larray); 591 begin 592 Larray := 593 Unchecked_Convert_To 594 (Underlying_Type (Etype (Larray)), Larray); 595 Set_Parent (Larray, Par); 596 end; 597 end if; 598 end if; 599 600 if Nkind (Act_Rhs) = N_Slice then 601 Rarray := Prefix (Act_Rhs); 602 else 603 Rarray := Act_Rhs; 604 605 if Is_Private_Type (Etype (Rarray)) then 606 declare 607 Par : constant Node_Id := Parent (Rarray); 608 begin 609 Rarray := 610 Unchecked_Convert_To 611 (Underlying_Type (Etype (Rarray)), Rarray); 612 Set_Parent (Rarray, Par); 613 end; 614 end if; 615 end if; 616 617 -- If both sides are slices, we must figure out whether it is safe 618 -- to do the move in one direction or the other. It is always safe 619 -- if there is a change of representation since obviously two arrays 620 -- with different representations cannot possibly overlap. 621 622 if (not Crep) and L_Slice and R_Slice then 623 Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs)); 624 Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs)); 625 626 -- If both left and right hand arrays are entity names, and refer 627 -- to different entities, then we know that the move is safe (the 628 -- two storage areas are completely disjoint). 629 630 if Is_Entity_Name (Act_L_Array) 631 and then Is_Entity_Name (Act_R_Array) 632 and then Entity (Act_L_Array) /= Entity (Act_R_Array) 633 then 634 null; 635 636 -- Otherwise, we assume the worst, which is that the two arrays 637 -- are the same array. There is no need to check if we know that 638 -- is the case, because if we don't know it, we still have to 639 -- assume it! 640 641 -- Generally if the same array is involved, then we have an 642 -- overlapping case. We will have to really assume the worst (i.e. 643 -- set neither of the OK flags) unless we can determine the lower 644 -- or upper bounds at compile time and compare them. 645 646 else 647 Cresult := 648 Compile_Time_Compare 649 (Left_Lo, Right_Lo, Assume_Valid => True); 650 651 if Cresult = Unknown then 652 Cresult := 653 Compile_Time_Compare 654 (Left_Hi, Right_Hi, Assume_Valid => True); 655 end if; 656 657 case Cresult is 658 when LT | LE | EQ => Set_Backwards_OK (N, False); 659 when GT | GE => Set_Forwards_OK (N, False); 660 when NE | Unknown => Set_Backwards_OK (N, False); 661 Set_Forwards_OK (N, False); 662 end case; 663 end if; 664 end if; 665 666 -- If after that analysis Loop_Required is False, meaning that we 667 -- have not discovered some non-overlap reason for requiring a loop, 668 -- then the outcome depends on the capabilities of the back end. 669 670 if not Loop_Required then 671 672 -- The GCC back end can deal with all cases of overlap by falling 673 -- back to memmove if it cannot use a more efficient approach. 674 675 if VM_Target = No_VM and not AAMP_On_Target then 676 return; 677 678 -- Assume other back ends can handle it if Forwards_OK is set 679 680 elsif Forwards_OK (N) then 681 return; 682 683 -- If Forwards_OK is not set, the back end will need something 684 -- like memmove to handle the move. For now, this processing is 685 -- activated using the .s debug flag (-gnatd.s). 686 687 elsif Debug_Flag_Dot_S then 688 return; 689 end if; 690 end if; 691 692 -- At this stage we have to generate an explicit loop, and we have 693 -- the following cases: 694 695 -- Forwards_OK = True 696 697 -- Rnn : right_index := right_index'First; 698 -- for Lnn in left-index loop 699 -- left (Lnn) := right (Rnn); 700 -- Rnn := right_index'Succ (Rnn); 701 -- end loop; 702 703 -- Note: the above code MUST be analyzed with checks off, because 704 -- otherwise the Succ could overflow. But in any case this is more 705 -- efficient! 706 707 -- Forwards_OK = False, Backwards_OK = True 708 709 -- Rnn : right_index := right_index'Last; 710 -- for Lnn in reverse left-index loop 711 -- left (Lnn) := right (Rnn); 712 -- Rnn := right_index'Pred (Rnn); 713 -- end loop; 714 715 -- Note: the above code MUST be analyzed with checks off, because 716 -- otherwise the Pred could overflow. But in any case this is more 717 -- efficient! 718 719 -- Forwards_OK = Backwards_OK = False 720 721 -- This only happens if we have the same array on each side. It is 722 -- possible to create situations using overlays that violate this, 723 -- but we simply do not promise to get this "right" in this case. 724 725 -- There are two possible subcases. If the No_Implicit_Conditionals 726 -- restriction is set, then we generate the following code: 727 728 -- declare 729 -- T : constant <operand-type> := rhs; 730 -- begin 731 -- lhs := T; 732 -- end; 733 734 -- If implicit conditionals are permitted, then we generate: 735 736 -- if Left_Lo <= Right_Lo then 737 -- <code for Forwards_OK = True above> 738 -- else 739 -- <code for Backwards_OK = True above> 740 -- end if; 741 742 -- In order to detect possible aliasing, we examine the renamed 743 -- expression when the source or target is a renaming. However, 744 -- the renaming may be intended to capture an address that may be 745 -- affected by subsequent code, and therefore we must recover 746 -- the actual entity for the expansion that follows, not the 747 -- object it renames. In particular, if source or target designate 748 -- a portion of a dynamically allocated object, the pointer to it 749 -- may be reassigned but the renaming preserves the proper location. 750 751 if Is_Entity_Name (Rhs) 752 and then 753 Nkind (Parent (Entity (Rhs))) = N_Object_Renaming_Declaration 754 and then Nkind (Act_Rhs) = N_Slice 755 then 756 Rarray := Rhs; 757 end if; 758 759 if Is_Entity_Name (Lhs) 760 and then 761 Nkind (Parent (Entity (Lhs))) = N_Object_Renaming_Declaration 762 and then Nkind (Act_Lhs) = N_Slice 763 then 764 Larray := Lhs; 765 end if; 766 767 -- Cases where either Forwards_OK or Backwards_OK is true 768 769 if Forwards_OK (N) or else Backwards_OK (N) then 770 if Needs_Finalization (Component_Type (L_Type)) 771 and then Base_Type (L_Type) = Base_Type (R_Type) 772 and then Ndim = 1 773 and then not No_Ctrl_Actions (N) 774 then 775 declare 776 Proc : constant Entity_Id := 777 TSS (Base_Type (L_Type), TSS_Slice_Assign); 778 Actuals : List_Id; 779 780 begin 781 Apply_Dereference (Larray); 782 Apply_Dereference (Rarray); 783 Actuals := New_List ( 784 Duplicate_Subexpr (Larray, Name_Req => True), 785 Duplicate_Subexpr (Rarray, Name_Req => True), 786 Duplicate_Subexpr (Left_Lo, Name_Req => True), 787 Duplicate_Subexpr (Left_Hi, Name_Req => True), 788 Duplicate_Subexpr (Right_Lo, Name_Req => True), 789 Duplicate_Subexpr (Right_Hi, Name_Req => True)); 790 791 Append_To (Actuals, 792 New_Occurrence_Of ( 793 Boolean_Literals (not Forwards_OK (N)), Loc)); 794 795 Rewrite (N, 796 Make_Procedure_Call_Statement (Loc, 797 Name => New_Reference_To (Proc, Loc), 798 Parameter_Associations => Actuals)); 799 end; 800 801 else 802 Rewrite (N, 803 Expand_Assign_Array_Loop 804 (N, Larray, Rarray, L_Type, R_Type, Ndim, 805 Rev => not Forwards_OK (N))); 806 end if; 807 808 -- Case of both are false with No_Implicit_Conditionals 809 810 elsif Restriction_Active (No_Implicit_Conditionals) then 811 declare 812 T : constant Entity_Id := 813 Make_Defining_Identifier (Loc, Chars => Name_T); 814 815 begin 816 Rewrite (N, 817 Make_Block_Statement (Loc, 818 Declarations => New_List ( 819 Make_Object_Declaration (Loc, 820 Defining_Identifier => T, 821 Constant_Present => True, 822 Object_Definition => 823 New_Occurrence_Of (Etype (Rhs), Loc), 824 Expression => Relocate_Node (Rhs))), 825 826 Handled_Statement_Sequence => 827 Make_Handled_Sequence_Of_Statements (Loc, 828 Statements => New_List ( 829 Make_Assignment_Statement (Loc, 830 Name => Relocate_Node (Lhs), 831 Expression => New_Occurrence_Of (T, Loc)))))); 832 end; 833 834 -- Case of both are false with implicit conditionals allowed 835 836 else 837 -- Before we generate this code, we must ensure that the left and 838 -- right side array types are defined. They may be itypes, and we 839 -- cannot let them be defined inside the if, since the first use 840 -- in the then may not be executed. 841 842 Ensure_Defined (L_Type, N); 843 Ensure_Defined (R_Type, N); 844 845 -- We normally compare addresses to find out which way round to 846 -- do the loop, since this is reliable, and handles the cases of 847 -- parameters, conversions etc. But we can't do that in the bit 848 -- packed case or the VM case, because addresses don't work there. 849 850 if not Is_Bit_Packed_Array (L_Type) and then VM_Target = No_VM then 851 Condition := 852 Make_Op_Le (Loc, 853 Left_Opnd => 854 Unchecked_Convert_To (RTE (RE_Integer_Address), 855 Make_Attribute_Reference (Loc, 856 Prefix => 857 Make_Indexed_Component (Loc, 858 Prefix => 859 Duplicate_Subexpr_Move_Checks (Larray, True), 860 Expressions => New_List ( 861 Make_Attribute_Reference (Loc, 862 Prefix => 863 New_Reference_To 864 (L_Index_Typ, Loc), 865 Attribute_Name => Name_First))), 866 Attribute_Name => Name_Address)), 867 868 Right_Opnd => 869 Unchecked_Convert_To (RTE (RE_Integer_Address), 870 Make_Attribute_Reference (Loc, 871 Prefix => 872 Make_Indexed_Component (Loc, 873 Prefix => 874 Duplicate_Subexpr_Move_Checks (Rarray, True), 875 Expressions => New_List ( 876 Make_Attribute_Reference (Loc, 877 Prefix => 878 New_Reference_To 879 (R_Index_Typ, Loc), 880 Attribute_Name => Name_First))), 881 Attribute_Name => Name_Address))); 882 883 -- For the bit packed and VM cases we use the bounds. That's OK, 884 -- because we don't have to worry about parameters, since they 885 -- cannot cause overlap. Perhaps we should worry about weird slice 886 -- conversions ??? 887 888 else 889 -- Copy the bounds 890 891 Cleft_Lo := New_Copy_Tree (Left_Lo); 892 Cright_Lo := New_Copy_Tree (Right_Lo); 893 894 -- If the types do not match we add an implicit conversion 895 -- here to ensure proper match 896 897 if Etype (Left_Lo) /= Etype (Right_Lo) then 898 Cright_Lo := 899 Unchecked_Convert_To (Etype (Left_Lo), Cright_Lo); 900 end if; 901 902 -- Reset the Analyzed flag, because the bounds of the index 903 -- type itself may be universal, and must must be reanalyzed 904 -- to acquire the proper type for the back end. 905 906 Set_Analyzed (Cleft_Lo, False); 907 Set_Analyzed (Cright_Lo, False); 908 909 Condition := 910 Make_Op_Le (Loc, 911 Left_Opnd => Cleft_Lo, 912 Right_Opnd => Cright_Lo); 913 end if; 914 915 if Needs_Finalization (Component_Type (L_Type)) 916 and then Base_Type (L_Type) = Base_Type (R_Type) 917 and then Ndim = 1 918 and then not No_Ctrl_Actions (N) 919 then 920 921 -- Call TSS procedure for array assignment, passing the 922 -- explicit bounds of right and left hand sides. 923 924 declare 925 Proc : constant Entity_Id := 926 TSS (Base_Type (L_Type), TSS_Slice_Assign); 927 Actuals : List_Id; 928 929 begin 930 Apply_Dereference (Larray); 931 Apply_Dereference (Rarray); 932 Actuals := New_List ( 933 Duplicate_Subexpr (Larray, Name_Req => True), 934 Duplicate_Subexpr (Rarray, Name_Req => True), 935 Duplicate_Subexpr (Left_Lo, Name_Req => True), 936 Duplicate_Subexpr (Left_Hi, Name_Req => True), 937 Duplicate_Subexpr (Right_Lo, Name_Req => True), 938 Duplicate_Subexpr (Right_Hi, Name_Req => True)); 939 940 Append_To (Actuals, 941 Make_Op_Not (Loc, 942 Right_Opnd => Condition)); 943 944 Rewrite (N, 945 Make_Procedure_Call_Statement (Loc, 946 Name => New_Reference_To (Proc, Loc), 947 Parameter_Associations => Actuals)); 948 end; 949 950 else 951 Rewrite (N, 952 Make_Implicit_If_Statement (N, 953 Condition => Condition, 954 955 Then_Statements => New_List ( 956 Expand_Assign_Array_Loop 957 (N, Larray, Rarray, L_Type, R_Type, Ndim, 958 Rev => False)), 959 960 Else_Statements => New_List ( 961 Expand_Assign_Array_Loop 962 (N, Larray, Rarray, L_Type, R_Type, Ndim, 963 Rev => True)))); 964 end if; 965 end if; 966 967 Analyze (N, Suppress => All_Checks); 968 end; 969 970 exception 971 when RE_Not_Available => 972 return; 973 end Expand_Assign_Array; 974 975 ------------------------------ 976 -- Expand_Assign_Array_Loop -- 977 ------------------------------ 978 979 -- The following is an example of the loop generated for the case of a 980 -- two-dimensional array: 981 982 -- declare 983 -- R2b : Tm1X1 := 1; 984 -- begin 985 -- for L1b in 1 .. 100 loop 986 -- declare 987 -- R4b : Tm1X2 := 1; 988 -- begin 989 -- for L3b in 1 .. 100 loop 990 -- vm1 (L1b, L3b) := vm2 (R2b, R4b); 991 -- R4b := Tm1X2'succ(R4b); 992 -- end loop; 993 -- end; 994 -- R2b := Tm1X1'succ(R2b); 995 -- end loop; 996 -- end; 997 998 -- Here Rev is False, and Tm1Xn are the subscript types for the right hand 999 -- side. The declarations of R2b and R4b are inserted before the original 1000 -- assignment statement. 1001 1002 function Expand_Assign_Array_Loop 1003 (N : Node_Id; 1004 Larray : Entity_Id; 1005 Rarray : Entity_Id; 1006 L_Type : Entity_Id; 1007 R_Type : Entity_Id; 1008 Ndim : Pos; 1009 Rev : Boolean) return Node_Id 1010 is 1011 Loc : constant Source_Ptr := Sloc (N); 1012 1013 Lnn : array (1 .. Ndim) of Entity_Id; 1014 Rnn : array (1 .. Ndim) of Entity_Id; 1015 -- Entities used as subscripts on left and right sides 1016 1017 L_Index_Type : array (1 .. Ndim) of Entity_Id; 1018 R_Index_Type : array (1 .. Ndim) of Entity_Id; 1019 -- Left and right index types 1020 1021 Assign : Node_Id; 1022 1023 F_Or_L : Name_Id; 1024 S_Or_P : Name_Id; 1025 1026 function Build_Step (J : Nat) return Node_Id; 1027 -- The increment step for the index of the right-hand side is written 1028 -- as an attribute reference (Succ or Pred). This function returns 1029 -- the corresponding node, which is placed at the end of the loop body. 1030 1031 ---------------- 1032 -- Build_Step -- 1033 ---------------- 1034 1035 function Build_Step (J : Nat) return Node_Id is 1036 Step : Node_Id; 1037 Lim : Name_Id; 1038 1039 begin 1040 if Rev then 1041 Lim := Name_First; 1042 else 1043 Lim := Name_Last; 1044 end if; 1045 1046 Step := 1047 Make_Assignment_Statement (Loc, 1048 Name => New_Occurrence_Of (Rnn (J), Loc), 1049 Expression => 1050 Make_Attribute_Reference (Loc, 1051 Prefix => 1052 New_Occurrence_Of (R_Index_Type (J), Loc), 1053 Attribute_Name => S_Or_P, 1054 Expressions => New_List ( 1055 New_Occurrence_Of (Rnn (J), Loc)))); 1056 1057 -- Note that on the last iteration of the loop, the index is increased 1058 -- (or decreased) past the corresponding bound. This is consistent with 1059 -- the C semantics of the back-end, where such an off-by-one value on a 1060 -- dead index variable is OK. However, in CodePeer mode this leads to 1061 -- spurious warnings, and thus we place a guard around the attribute 1062 -- reference. For obvious reasons we only do this for CodePeer. 1063 1064 if CodePeer_Mode then 1065 Step := 1066 Make_If_Statement (Loc, 1067 Condition => 1068 Make_Op_Ne (Loc, 1069 Left_Opnd => New_Occurrence_Of (Lnn (J), Loc), 1070 Right_Opnd => 1071 Make_Attribute_Reference (Loc, 1072 Prefix => New_Occurrence_Of (L_Index_Type (J), Loc), 1073 Attribute_Name => Lim)), 1074 Then_Statements => New_List (Step)); 1075 end if; 1076 1077 return Step; 1078 end Build_Step; 1079 1080 -- Start of processing for Expand_Assign_Array_Loop 1081 1082 begin 1083 if Rev then 1084 F_Or_L := Name_Last; 1085 S_Or_P := Name_Pred; 1086 else 1087 F_Or_L := Name_First; 1088 S_Or_P := Name_Succ; 1089 end if; 1090 1091 -- Setup index types and subscript entities 1092 1093 declare 1094 L_Index : Node_Id; 1095 R_Index : Node_Id; 1096 1097 begin 1098 L_Index := First_Index (L_Type); 1099 R_Index := First_Index (R_Type); 1100 1101 for J in 1 .. Ndim loop 1102 Lnn (J) := Make_Temporary (Loc, 'L'); 1103 Rnn (J) := Make_Temporary (Loc, 'R'); 1104 1105 L_Index_Type (J) := Etype (L_Index); 1106 R_Index_Type (J) := Etype (R_Index); 1107 1108 Next_Index (L_Index); 1109 Next_Index (R_Index); 1110 end loop; 1111 end; 1112 1113 -- Now construct the assignment statement 1114 1115 declare 1116 ExprL : constant List_Id := New_List; 1117 ExprR : constant List_Id := New_List; 1118 1119 begin 1120 for J in 1 .. Ndim loop 1121 Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc)); 1122 Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc)); 1123 end loop; 1124 1125 Assign := 1126 Make_Assignment_Statement (Loc, 1127 Name => 1128 Make_Indexed_Component (Loc, 1129 Prefix => Duplicate_Subexpr (Larray, Name_Req => True), 1130 Expressions => ExprL), 1131 Expression => 1132 Make_Indexed_Component (Loc, 1133 Prefix => Duplicate_Subexpr (Rarray, Name_Req => True), 1134 Expressions => ExprR)); 1135 1136 -- We set assignment OK, since there are some cases, e.g. in object 1137 -- declarations, where we are actually assigning into a constant. 1138 -- If there really is an illegality, it was caught long before now, 1139 -- and was flagged when the original assignment was analyzed. 1140 1141 Set_Assignment_OK (Name (Assign)); 1142 1143 -- Propagate the No_Ctrl_Actions flag to individual assignments 1144 1145 Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N)); 1146 end; 1147 1148 -- Now construct the loop from the inside out, with the last subscript 1149 -- varying most rapidly. Note that Assign is first the raw assignment 1150 -- statement, and then subsequently the loop that wraps it up. 1151 1152 for J in reverse 1 .. Ndim loop 1153 Assign := 1154 Make_Block_Statement (Loc, 1155 Declarations => New_List ( 1156 Make_Object_Declaration (Loc, 1157 Defining_Identifier => Rnn (J), 1158 Object_Definition => 1159 New_Occurrence_Of (R_Index_Type (J), Loc), 1160 Expression => 1161 Make_Attribute_Reference (Loc, 1162 Prefix => New_Occurrence_Of (R_Index_Type (J), Loc), 1163 Attribute_Name => F_Or_L))), 1164 1165 Handled_Statement_Sequence => 1166 Make_Handled_Sequence_Of_Statements (Loc, 1167 Statements => New_List ( 1168 Make_Implicit_Loop_Statement (N, 1169 Iteration_Scheme => 1170 Make_Iteration_Scheme (Loc, 1171 Loop_Parameter_Specification => 1172 Make_Loop_Parameter_Specification (Loc, 1173 Defining_Identifier => Lnn (J), 1174 Reverse_Present => Rev, 1175 Discrete_Subtype_Definition => 1176 New_Reference_To (L_Index_Type (J), Loc))), 1177 1178 Statements => New_List (Assign, Build_Step (J)))))); 1179 end loop; 1180 1181 return Assign; 1182 end Expand_Assign_Array_Loop; 1183 1184 -------------------------- 1185 -- Expand_Assign_Record -- 1186 -------------------------- 1187 1188 procedure Expand_Assign_Record (N : Node_Id) is 1189 Lhs : constant Node_Id := Name (N); 1190 Rhs : Node_Id := Expression (N); 1191 L_Typ : constant Entity_Id := Base_Type (Etype (Lhs)); 1192 1193 begin 1194 -- If change of representation, then extract the real right hand side 1195 -- from the type conversion, and proceed with component-wise assignment, 1196 -- since the two types are not the same as far as the back end is 1197 -- concerned. 1198 1199 if Change_Of_Representation (N) then 1200 Rhs := Expression (Rhs); 1201 1202 -- If this may be a case of a large bit aligned component, then proceed 1203 -- with component-wise assignment, to avoid possible clobbering of other 1204 -- components sharing bits in the first or last byte of the component to 1205 -- be assigned. 1206 1207 elsif Possible_Bit_Aligned_Component (Lhs) 1208 or 1209 Possible_Bit_Aligned_Component (Rhs) 1210 then 1211 null; 1212 1213 -- If we have a tagged type that has a complete record representation 1214 -- clause, we must do we must do component-wise assignments, since child 1215 -- types may have used gaps for their components, and we might be 1216 -- dealing with a view conversion. 1217 1218 elsif Is_Fully_Repped_Tagged_Type (L_Typ) then 1219 null; 1220 1221 -- If neither condition met, then nothing special to do, the back end 1222 -- can handle assignment of the entire component as a single entity. 1223 1224 else 1225 return; 1226 end if; 1227 1228 -- At this stage we know that we must do a component wise assignment 1229 1230 declare 1231 Loc : constant Source_Ptr := Sloc (N); 1232 R_Typ : constant Entity_Id := Base_Type (Etype (Rhs)); 1233 Decl : constant Node_Id := Declaration_Node (R_Typ); 1234 RDef : Node_Id; 1235 F : Entity_Id; 1236 1237 function Find_Component 1238 (Typ : Entity_Id; 1239 Comp : Entity_Id) return Entity_Id; 1240 -- Find the component with the given name in the underlying record 1241 -- declaration for Typ. We need to use the actual entity because the 1242 -- type may be private and resolution by identifier alone would fail. 1243 1244 function Make_Component_List_Assign 1245 (CL : Node_Id; 1246 U_U : Boolean := False) return List_Id; 1247 -- Returns a sequence of statements to assign the components that 1248 -- are referenced in the given component list. The flag U_U is 1249 -- used to force the usage of the inferred value of the variant 1250 -- part expression as the switch for the generated case statement. 1251 1252 function Make_Field_Assign 1253 (C : Entity_Id; 1254 U_U : Boolean := False) return Node_Id; 1255 -- Given C, the entity for a discriminant or component, build an 1256 -- assignment for the corresponding field values. The flag U_U 1257 -- signals the presence of an Unchecked_Union and forces the usage 1258 -- of the inferred discriminant value of C as the right hand side 1259 -- of the assignment. 1260 1261 function Make_Field_Assigns (CI : List_Id) return List_Id; 1262 -- Given CI, a component items list, construct series of statements 1263 -- for fieldwise assignment of the corresponding components. 1264 1265 -------------------- 1266 -- Find_Component -- 1267 -------------------- 1268 1269 function Find_Component 1270 (Typ : Entity_Id; 1271 Comp : Entity_Id) return Entity_Id 1272 is 1273 Utyp : constant Entity_Id := Underlying_Type (Typ); 1274 C : Entity_Id; 1275 1276 begin 1277 C := First_Entity (Utyp); 1278 while Present (C) loop 1279 if Chars (C) = Chars (Comp) then 1280 return C; 1281 end if; 1282 1283 Next_Entity (C); 1284 end loop; 1285 1286 raise Program_Error; 1287 end Find_Component; 1288 1289 -------------------------------- 1290 -- Make_Component_List_Assign -- 1291 -------------------------------- 1292 1293 function Make_Component_List_Assign 1294 (CL : Node_Id; 1295 U_U : Boolean := False) return List_Id 1296 is 1297 CI : constant List_Id := Component_Items (CL); 1298 VP : constant Node_Id := Variant_Part (CL); 1299 1300 Alts : List_Id; 1301 DC : Node_Id; 1302 DCH : List_Id; 1303 Expr : Node_Id; 1304 Result : List_Id; 1305 V : Node_Id; 1306 1307 begin 1308 Result := Make_Field_Assigns (CI); 1309 1310 if Present (VP) then 1311 V := First_Non_Pragma (Variants (VP)); 1312 Alts := New_List; 1313 while Present (V) loop 1314 DCH := New_List; 1315 DC := First (Discrete_Choices (V)); 1316 while Present (DC) loop 1317 Append_To (DCH, New_Copy_Tree (DC)); 1318 Next (DC); 1319 end loop; 1320 1321 Append_To (Alts, 1322 Make_Case_Statement_Alternative (Loc, 1323 Discrete_Choices => DCH, 1324 Statements => 1325 Make_Component_List_Assign (Component_List (V)))); 1326 Next_Non_Pragma (V); 1327 end loop; 1328 1329 -- If we have an Unchecked_Union, use the value of the inferred 1330 -- discriminant of the variant part expression as the switch 1331 -- for the case statement. The case statement may later be 1332 -- folded. 1333 1334 if U_U then 1335 Expr := 1336 New_Copy (Get_Discriminant_Value ( 1337 Entity (Name (VP)), 1338 Etype (Rhs), 1339 Discriminant_Constraint (Etype (Rhs)))); 1340 else 1341 Expr := 1342 Make_Selected_Component (Loc, 1343 Prefix => Duplicate_Subexpr (Rhs), 1344 Selector_Name => 1345 Make_Identifier (Loc, Chars (Name (VP)))); 1346 end if; 1347 1348 Append_To (Result, 1349 Make_Case_Statement (Loc, 1350 Expression => Expr, 1351 Alternatives => Alts)); 1352 end if; 1353 1354 return Result; 1355 end Make_Component_List_Assign; 1356 1357 ----------------------- 1358 -- Make_Field_Assign -- 1359 ----------------------- 1360 1361 function Make_Field_Assign 1362 (C : Entity_Id; 1363 U_U : Boolean := False) return Node_Id 1364 is 1365 A : Node_Id; 1366 Expr : Node_Id; 1367 1368 begin 1369 -- In the case of an Unchecked_Union, use the discriminant 1370 -- constraint value as on the right hand side of the assignment. 1371 1372 if U_U then 1373 Expr := 1374 New_Copy (Get_Discriminant_Value (C, 1375 Etype (Rhs), 1376 Discriminant_Constraint (Etype (Rhs)))); 1377 else 1378 Expr := 1379 Make_Selected_Component (Loc, 1380 Prefix => Duplicate_Subexpr (Rhs), 1381 Selector_Name => New_Occurrence_Of (C, Loc)); 1382 end if; 1383 1384 A := 1385 Make_Assignment_Statement (Loc, 1386 Name => 1387 Make_Selected_Component (Loc, 1388 Prefix => Duplicate_Subexpr (Lhs), 1389 Selector_Name => 1390 New_Occurrence_Of (Find_Component (L_Typ, C), Loc)), 1391 Expression => Expr); 1392 1393 -- Set Assignment_OK, so discriminants can be assigned 1394 1395 Set_Assignment_OK (Name (A), True); 1396 1397 if Componentwise_Assignment (N) 1398 and then Nkind (Name (A)) = N_Selected_Component 1399 and then Chars (Selector_Name (Name (A))) = Name_uParent 1400 then 1401 Set_Componentwise_Assignment (A); 1402 end if; 1403 1404 return A; 1405 end Make_Field_Assign; 1406 1407 ------------------------ 1408 -- Make_Field_Assigns -- 1409 ------------------------ 1410 1411 function Make_Field_Assigns (CI : List_Id) return List_Id is 1412 Item : Node_Id; 1413 Result : List_Id; 1414 1415 begin 1416 Item := First (CI); 1417 Result := New_List; 1418 1419 while Present (Item) loop 1420 1421 -- Look for components, but exclude _tag field assignment if 1422 -- the special Componentwise_Assignment flag is set. 1423 1424 if Nkind (Item) = N_Component_Declaration 1425 and then not (Is_Tag (Defining_Identifier (Item)) 1426 and then Componentwise_Assignment (N)) 1427 then 1428 Append_To 1429 (Result, Make_Field_Assign (Defining_Identifier (Item))); 1430 end if; 1431 1432 Next (Item); 1433 end loop; 1434 1435 return Result; 1436 end Make_Field_Assigns; 1437 1438 -- Start of processing for Expand_Assign_Record 1439 1440 begin 1441 -- Note that we use the base types for this processing. This results 1442 -- in some extra work in the constrained case, but the change of 1443 -- representation case is so unusual that it is not worth the effort. 1444 1445 -- First copy the discriminants. This is done unconditionally. It 1446 -- is required in the unconstrained left side case, and also in the 1447 -- case where this assignment was constructed during the expansion 1448 -- of a type conversion (since initialization of discriminants is 1449 -- suppressed in this case). It is unnecessary but harmless in 1450 -- other cases. 1451 1452 if Has_Discriminants (L_Typ) then 1453 F := First_Discriminant (R_Typ); 1454 while Present (F) loop 1455 1456 -- If we are expanding the initialization of a derived record 1457 -- that constrains or renames discriminants of the parent, we 1458 -- must use the corresponding discriminant in the parent. 1459 1460 declare 1461 CF : Entity_Id; 1462 1463 begin 1464 if Inside_Init_Proc 1465 and then Present (Corresponding_Discriminant (F)) 1466 then 1467 CF := Corresponding_Discriminant (F); 1468 else 1469 CF := F; 1470 end if; 1471 1472 if Is_Unchecked_Union (Base_Type (R_Typ)) then 1473 1474 -- Within an initialization procedure this is the 1475 -- assignment to an unchecked union component, in which 1476 -- case there is no discriminant to initialize. 1477 1478 if Inside_Init_Proc then 1479 null; 1480 1481 else 1482 -- The assignment is part of a conversion from a 1483 -- derived unchecked union type with an inferable 1484 -- discriminant, to a parent type. 1485 1486 Insert_Action (N, Make_Field_Assign (CF, True)); 1487 end if; 1488 1489 else 1490 Insert_Action (N, Make_Field_Assign (CF)); 1491 end if; 1492 1493 Next_Discriminant (F); 1494 end; 1495 end loop; 1496 end if; 1497 1498 -- We know the underlying type is a record, but its current view 1499 -- may be private. We must retrieve the usable record declaration. 1500 1501 if Nkind_In (Decl, N_Private_Type_Declaration, 1502 N_Private_Extension_Declaration) 1503 and then Present (Full_View (R_Typ)) 1504 then 1505 RDef := Type_Definition (Declaration_Node (Full_View (R_Typ))); 1506 else 1507 RDef := Type_Definition (Decl); 1508 end if; 1509 1510 if Nkind (RDef) = N_Derived_Type_Definition then 1511 RDef := Record_Extension_Part (RDef); 1512 end if; 1513 1514 if Nkind (RDef) = N_Record_Definition 1515 and then Present (Component_List (RDef)) 1516 then 1517 if Is_Unchecked_Union (R_Typ) then 1518 Insert_Actions (N, 1519 Make_Component_List_Assign (Component_List (RDef), True)); 1520 else 1521 Insert_Actions 1522 (N, Make_Component_List_Assign (Component_List (RDef))); 1523 end if; 1524 1525 Rewrite (N, Make_Null_Statement (Loc)); 1526 end if; 1527 end; 1528 end Expand_Assign_Record; 1529 1530 ---------------------------------- 1531 -- Expand_Loop_Entry_Attributes -- 1532 ---------------------------------- 1533 1534 procedure Expand_Loop_Entry_Attributes (N : Node_Id) is 1535 procedure Build_Conditional_Block 1536 (Loc : Source_Ptr; 1537 Cond : Node_Id; 1538 Stmt : Node_Id; 1539 If_Stmt : out Node_Id; 1540 Blk_Stmt : out Node_Id); 1541 -- Create a block Blk_Stmt with an empty declarative list and a single 1542 -- statement Stmt. The block is encased in an if statement If_Stmt with 1543 -- condition Cond. If_Stmt is Empty when there is no condition provided. 1544 1545 function Is_Array_Iteration (N : Node_Id) return Boolean; 1546 -- Determine whether loop statement N denotes an Ada 2012 iteration over 1547 -- an array object. 1548 1549 ----------------------------- 1550 -- Build_Conditional_Block -- 1551 ----------------------------- 1552 1553 procedure Build_Conditional_Block 1554 (Loc : Source_Ptr; 1555 Cond : Node_Id; 1556 Stmt : Node_Id; 1557 If_Stmt : out Node_Id; 1558 Blk_Stmt : out Node_Id) 1559 is 1560 begin 1561 Blk_Stmt := 1562 Make_Block_Statement (Loc, 1563 Declarations => New_List, 1564 Handled_Statement_Sequence => 1565 Make_Handled_Sequence_Of_Statements (Loc, 1566 Statements => New_List (Stmt))); 1567 1568 if Present (Cond) then 1569 If_Stmt := 1570 Make_If_Statement (Loc, 1571 Condition => Cond, 1572 Then_Statements => New_List (Blk_Stmt)); 1573 else 1574 If_Stmt := Empty; 1575 end if; 1576 end Build_Conditional_Block; 1577 1578 ------------------------ 1579 -- Is_Array_Iteration -- 1580 ------------------------ 1581 1582 function Is_Array_Iteration (N : Node_Id) return Boolean is 1583 Stmt : constant Node_Id := Original_Node (N); 1584 Iter : Node_Id; 1585 1586 begin 1587 if Nkind (Stmt) = N_Loop_Statement 1588 and then Present (Iteration_Scheme (Stmt)) 1589 and then Present (Iterator_Specification (Iteration_Scheme (Stmt))) 1590 then 1591 Iter := Iterator_Specification (Iteration_Scheme (Stmt)); 1592 1593 return 1594 Of_Present (Iter) 1595 and then Is_Array_Type (Etype (Name (Iter))); 1596 end if; 1597 1598 return False; 1599 end Is_Array_Iteration; 1600 1601 -- Local variables 1602 1603 Loc : constant Source_Ptr := Sloc (N); 1604 Loop_Id : constant Entity_Id := Identifier (N); 1605 Scheme : constant Node_Id := Iteration_Scheme (N); 1606 Blk : Node_Id; 1607 LE : Node_Id; 1608 LE_Elmt : Elmt_Id; 1609 Result : Node_Id; 1610 Temp : Entity_Id; 1611 Typ : Entity_Id; 1612 1613 -- Start of processing for Expand_Loop_Entry_Attributes 1614 1615 begin 1616 -- The loop will never execute after it has been expanded, no point in 1617 -- processing it. 1618 1619 if Is_Null_Loop (N) then 1620 return; 1621 1622 -- A loop without an identifier cannot be referenced in 'Loop_Entry 1623 1624 elsif No (Loop_Id) then 1625 return; 1626 1627 -- The loop is not subject to 'Loop_Entry 1628 1629 elsif No (Loop_Entry_Attributes (Entity (Loop_Id))) then 1630 return; 1631 1632 -- Step 1: Loop transformations 1633 1634 -- While loops are transformed into: 1635 1636 -- if <Condition> then 1637 -- declare 1638 -- Temp1 : constant <type of Pref1> := <Pref1>; 1639 -- . . . 1640 -- TempN : constant <type of PrefN> := <PrefN>; 1641 -- begin 1642 -- loop 1643 -- <original source statements with attribute rewrites> 1644 -- exit when not <Condition>; 1645 -- end loop; 1646 -- end; 1647 -- end if; 1648 1649 -- Note that loops over iterators and containers are already converted 1650 -- into while loops. 1651 1652 elsif Present (Condition (Scheme)) then 1653 declare 1654 Cond : constant Node_Id := Condition (Scheme); 1655 1656 begin 1657 -- Transform the original while loop into an infinite loop where 1658 -- the last statement checks the negated condition. This placement 1659 -- ensures that the condition will not be evaluated twice on the 1660 -- first iteration. 1661 1662 -- Generate: 1663 -- exit when not <Cond>: 1664 1665 Append_To (Statements (N), 1666 Make_Exit_Statement (Loc, 1667 Condition => Make_Op_Not (Loc, New_Copy_Tree (Cond)))); 1668 1669 Build_Conditional_Block (Loc, 1670 Cond => Relocate_Node (Cond), 1671 Stmt => Relocate_Node (N), 1672 If_Stmt => Result, 1673 Blk_Stmt => Blk); 1674 end; 1675 1676 -- Ada 2012 iteration over an array is transformed into: 1677 1678 -- if <Array_Nam>'Length (1) > 0 1679 -- and then <Array_Nam>'Length (N) > 0 1680 -- then 1681 -- declare 1682 -- Temp1 : constant <type of Pref1> := <Pref1>; 1683 -- . . . 1684 -- TempN : constant <type of PrefN> := <PrefN>; 1685 -- begin 1686 -- for X in ... loop -- multiple loops depending on dims 1687 -- <original source statements with attribute rewrites> 1688 -- end loop; 1689 -- end; 1690 -- end if; 1691 1692 elsif Is_Array_Iteration (N) then 1693 declare 1694 Array_Nam : constant Entity_Id := 1695 Entity (Name (Iterator_Specification 1696 (Iteration_Scheme (Original_Node (N))))); 1697 Num_Dims : constant Pos := 1698 Number_Dimensions (Etype (Array_Nam)); 1699 Cond : Node_Id := Empty; 1700 Check : Node_Id; 1701 Top_Loop : Node_Id; 1702 1703 begin 1704 -- Generate a check which determines whether all dimensions of 1705 -- the array are non-null. 1706 1707 for Dim in 1 .. Num_Dims loop 1708 Check := 1709 Make_Op_Gt (Loc, 1710 Left_Opnd => 1711 Make_Attribute_Reference (Loc, 1712 Prefix => New_Reference_To (Array_Nam, Loc), 1713 Attribute_Name => Name_Length, 1714 Expressions => New_List ( 1715 Make_Integer_Literal (Loc, Dim))), 1716 Right_Opnd => 1717 Make_Integer_Literal (Loc, 0)); 1718 1719 if No (Cond) then 1720 Cond := Check; 1721 else 1722 Cond := 1723 Make_And_Then (Loc, 1724 Left_Opnd => Cond, 1725 Right_Opnd => Check); 1726 end if; 1727 end loop; 1728 1729 Top_Loop := Relocate_Node (N); 1730 Set_Analyzed (Top_Loop); 1731 1732 Build_Conditional_Block (Loc, 1733 Cond => Cond, 1734 Stmt => Top_Loop, 1735 If_Stmt => Result, 1736 Blk_Stmt => Blk); 1737 end; 1738 1739 -- For loops are transformed into: 1740 1741 -- if <Low> <= <High> then 1742 -- declare 1743 -- Temp1 : constant <type of Pref1> := <Pref1>; 1744 -- . . . 1745 -- TempN : constant <type of PrefN> := <PrefN>; 1746 -- begin 1747 -- for <Def_Id> in <Low> .. <High> loop 1748 -- <original source statements with attribute rewrites> 1749 -- end loop; 1750 -- end; 1751 -- end if; 1752 1753 elsif Present (Loop_Parameter_Specification (Scheme)) then 1754 declare 1755 Loop_Spec : constant Node_Id := 1756 Loop_Parameter_Specification (Scheme); 1757 Cond : Node_Id; 1758 Subt_Def : Node_Id; 1759 1760 begin 1761 Subt_Def := Discrete_Subtype_Definition (Loop_Spec); 1762 1763 -- When the loop iterates over a subtype indication with a range, 1764 -- use the low and high bounds of the subtype itself. 1765 1766 if Nkind (Subt_Def) = N_Subtype_Indication then 1767 Subt_Def := Scalar_Range (Etype (Subt_Def)); 1768 end if; 1769 1770 pragma Assert (Nkind (Subt_Def) = N_Range); 1771 1772 -- Generate 1773 -- Low <= High 1774 1775 Cond := 1776 Make_Op_Le (Loc, 1777 Left_Opnd => New_Copy_Tree (Low_Bound (Subt_Def)), 1778 Right_Opnd => New_Copy_Tree (High_Bound (Subt_Def))); 1779 1780 Build_Conditional_Block (Loc, 1781 Cond => Cond, 1782 Stmt => Relocate_Node (N), 1783 If_Stmt => Result, 1784 Blk_Stmt => Blk); 1785 end; 1786 1787 -- Infinite loops are transformed into: 1788 1789 -- declare 1790 -- Temp1 : constant <type of Pref1> := <Pref1>; 1791 -- . . . 1792 -- TempN : constant <type of PrefN> := <PrefN>; 1793 -- begin 1794 -- loop 1795 -- <original source statements with attribute rewrites> 1796 -- end loop; 1797 -- end; 1798 1799 else 1800 Build_Conditional_Block (Loc, 1801 Cond => Empty, 1802 Stmt => Relocate_Node (N), 1803 If_Stmt => Result, 1804 Blk_Stmt => Blk); 1805 1806 Result := Blk; 1807 end if; 1808 1809 -- Step 2: Loop_Entry attribute transformations 1810 1811 -- At this point the various loops have been augmented to contain a 1812 -- block. Populate the declarative list of the block with constants 1813 -- which store the value of their relative prefixes at the point of 1814 -- entry in the loop. 1815 1816 LE_Elmt := First_Elmt (Loop_Entry_Attributes (Entity (Loop_Id))); 1817 while Present (LE_Elmt) loop 1818 LE := Node (LE_Elmt); 1819 Typ := Etype (Prefix (LE)); 1820 1821 -- Declare a constant to capture the value of the previx of each 1822 -- Loop_Entry attribute. 1823 1824 -- Generate: 1825 -- Temp : constant <type of Pref> := <Pref>; 1826 1827 Temp := Make_Temporary (Loc, 'P'); 1828 1829 Append_To (Declarations (Blk), 1830 Make_Object_Declaration (Loc, 1831 Defining_Identifier => Temp, 1832 Constant_Present => True, 1833 Object_Definition => New_Reference_To (Typ, Loc), 1834 Expression => Relocate_Node (Prefix (LE)))); 1835 1836 -- Perform minor decoration as this information will be needed for 1837 -- the creation of index checks (if applicable). 1838 1839 Set_Ekind (Temp, E_Constant); 1840 Set_Etype (Temp, Typ); 1841 1842 -- Replace the original attribute with a reference to the constant 1843 1844 Rewrite (LE, New_Reference_To (Temp, Loc)); 1845 Set_Etype (LE, Typ); 1846 1847 -- Analysis converts attribute references of the following form 1848 1849 -- Prefix'Loop_Entry (Expr) 1850 -- Prefix'Loop_Entry (Expr1, Expr2, ... ExprN) 1851 1852 -- into indexed components for error detection purposes. Generate 1853 -- index checks now that 'Loop_Entry has been properly expanded. 1854 1855 if Nkind (Parent (LE)) = N_Indexed_Component then 1856 Generate_Index_Checks (Parent (LE)); 1857 end if; 1858 1859 Next_Elmt (LE_Elmt); 1860 end loop; 1861 1862 -- Destroy the list of Loop_Entry attributes to prevent the infinite 1863 -- expansion when analyzing and expanding the newly generated loops. 1864 1865 Set_Loop_Entry_Attributes (Entity (Loop_Id), No_Elist); 1866 1867 Rewrite (N, Result); 1868 Analyze (N); 1869 end Expand_Loop_Entry_Attributes; 1870 1871 ----------------------------------- 1872 -- Expand_N_Assignment_Statement -- 1873 ----------------------------------- 1874 1875 -- This procedure implements various cases where an assignment statement 1876 -- cannot just be passed on to the back end in untransformed state. 1877 1878 procedure Expand_N_Assignment_Statement (N : Node_Id) is 1879 Loc : constant Source_Ptr := Sloc (N); 1880 Crep : constant Boolean := Change_Of_Representation (N); 1881 Lhs : constant Node_Id := Name (N); 1882 Rhs : constant Node_Id := Expression (N); 1883 Typ : constant Entity_Id := Underlying_Type (Etype (Lhs)); 1884 Exp : Node_Id; 1885 1886 begin 1887 -- Special case to check right away, if the Componentwise_Assignment 1888 -- flag is set, this is a reanalysis from the expansion of the primitive 1889 -- assignment procedure for a tagged type, and all we need to do is to 1890 -- expand to assignment of components, because otherwise, we would get 1891 -- infinite recursion (since this looks like a tagged assignment which 1892 -- would normally try to *call* the primitive assignment procedure). 1893 1894 if Componentwise_Assignment (N) then 1895 Expand_Assign_Record (N); 1896 return; 1897 end if; 1898 1899 -- Defend against invalid subscripts on left side if we are in standard 1900 -- validity checking mode. No need to do this if we are checking all 1901 -- subscripts. 1902 1903 -- Note that we do this right away, because there are some early return 1904 -- paths in this procedure, and this is required on all paths. 1905 1906 if Validity_Checks_On 1907 and then Validity_Check_Default 1908 and then not Validity_Check_Subscripts 1909 then 1910 Check_Valid_Lvalue_Subscripts (Lhs); 1911 end if; 1912 1913 -- Ada 2005 (AI-327): Handle assignment to priority of protected object 1914 1915 -- Rewrite an assignment to X'Priority into a run-time call 1916 1917 -- For example: X'Priority := New_Prio_Expr; 1918 -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr); 1919 1920 -- Note that although X'Priority is notionally an object, it is quite 1921 -- deliberately not defined as an aliased object in the RM. This means 1922 -- that it works fine to rewrite it as a call, without having to worry 1923 -- about complications that would other arise from X'Priority'Access, 1924 -- which is illegal, because of the lack of aliasing. 1925 1926 if Ada_Version >= Ada_2005 then 1927 declare 1928 Call : Node_Id; 1929 Conctyp : Entity_Id; 1930 Ent : Entity_Id; 1931 Subprg : Entity_Id; 1932 RT_Subprg_Name : Node_Id; 1933 1934 begin 1935 -- Handle chains of renamings 1936 1937 Ent := Name (N); 1938 while Nkind (Ent) in N_Has_Entity 1939 and then Present (Entity (Ent)) 1940 and then Present (Renamed_Object (Entity (Ent))) 1941 loop 1942 Ent := Renamed_Object (Entity (Ent)); 1943 end loop; 1944 1945 -- The attribute Priority applied to protected objects has been 1946 -- previously expanded into a call to the Get_Ceiling run-time 1947 -- subprogram. 1948 1949 if Nkind (Ent) = N_Function_Call 1950 and then (Entity (Name (Ent)) = RTE (RE_Get_Ceiling) 1951 or else 1952 Entity (Name (Ent)) = RTE (RO_PE_Get_Ceiling)) 1953 then 1954 -- Look for the enclosing concurrent type 1955 1956 Conctyp := Current_Scope; 1957 while not Is_Concurrent_Type (Conctyp) loop 1958 Conctyp := Scope (Conctyp); 1959 end loop; 1960 1961 pragma Assert (Is_Protected_Type (Conctyp)); 1962 1963 -- Generate the first actual of the call 1964 1965 Subprg := Current_Scope; 1966 while not Present (Protected_Body_Subprogram (Subprg)) loop 1967 Subprg := Scope (Subprg); 1968 end loop; 1969 1970 -- Select the appropriate run-time call 1971 1972 if Number_Entries (Conctyp) = 0 then 1973 RT_Subprg_Name := 1974 New_Reference_To (RTE (RE_Set_Ceiling), Loc); 1975 else 1976 RT_Subprg_Name := 1977 New_Reference_To (RTE (RO_PE_Set_Ceiling), Loc); 1978 end if; 1979 1980 Call := 1981 Make_Procedure_Call_Statement (Loc, 1982 Name => RT_Subprg_Name, 1983 Parameter_Associations => New_List ( 1984 New_Copy_Tree (First (Parameter_Associations (Ent))), 1985 Relocate_Node (Expression (N)))); 1986 1987 Rewrite (N, Call); 1988 Analyze (N); 1989 return; 1990 end if; 1991 end; 1992 end if; 1993 1994 -- Deal with assignment checks unless suppressed 1995 1996 if not Suppress_Assignment_Checks (N) then 1997 1998 -- First deal with generation of range check if required 1999 2000 if Do_Range_Check (Rhs) then 2001 Set_Do_Range_Check (Rhs, False); 2002 Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed); 2003 end if; 2004 2005 -- Then generate predicate check if required 2006 2007 Apply_Predicate_Check (Rhs, Typ); 2008 end if; 2009 2010 -- Check for a special case where a high level transformation is 2011 -- required. If we have either of: 2012 2013 -- P.field := rhs; 2014 -- P (sub) := rhs; 2015 2016 -- where P is a reference to a bit packed array, then we have to unwind 2017 -- the assignment. The exact meaning of being a reference to a bit 2018 -- packed array is as follows: 2019 2020 -- An indexed component whose prefix is a bit packed array is a 2021 -- reference to a bit packed array. 2022 2023 -- An indexed component or selected component whose prefix is a 2024 -- reference to a bit packed array is itself a reference ot a 2025 -- bit packed array. 2026 2027 -- The required transformation is 2028 2029 -- Tnn : prefix_type := P; 2030 -- Tnn.field := rhs; 2031 -- P := Tnn; 2032 2033 -- or 2034 2035 -- Tnn : prefix_type := P; 2036 -- Tnn (subscr) := rhs; 2037 -- P := Tnn; 2038 2039 -- Since P is going to be evaluated more than once, any subscripts 2040 -- in P must have their evaluation forced. 2041 2042 if Nkind_In (Lhs, N_Indexed_Component, N_Selected_Component) 2043 and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs)) 2044 then 2045 declare 2046 BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs)); 2047 BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr); 2048 Tnn : constant Entity_Id := 2049 Make_Temporary (Loc, 'T', BPAR_Expr); 2050 2051 begin 2052 -- Insert the post assignment first, because we want to copy the 2053 -- BPAR_Expr tree before it gets analyzed in the context of the 2054 -- pre assignment. Note that we do not analyze the post assignment 2055 -- yet (we cannot till we have completed the analysis of the pre 2056 -- assignment). As usual, the analysis of this post assignment 2057 -- will happen on its own when we "run into" it after finishing 2058 -- the current assignment. 2059 2060 Insert_After (N, 2061 Make_Assignment_Statement (Loc, 2062 Name => New_Copy_Tree (BPAR_Expr), 2063 Expression => New_Occurrence_Of (Tnn, Loc))); 2064 2065 -- At this stage BPAR_Expr is a reference to a bit packed array 2066 -- where the reference was not expanded in the original tree, 2067 -- since it was on the left side of an assignment. But in the 2068 -- pre-assignment statement (the object definition), BPAR_Expr 2069 -- will end up on the right hand side, and must be reexpanded. To 2070 -- achieve this, we reset the analyzed flag of all selected and 2071 -- indexed components down to the actual indexed component for 2072 -- the packed array. 2073 2074 Exp := BPAR_Expr; 2075 loop 2076 Set_Analyzed (Exp, False); 2077 2078 if Nkind_In 2079 (Exp, N_Selected_Component, N_Indexed_Component) 2080 then 2081 Exp := Prefix (Exp); 2082 else 2083 exit; 2084 end if; 2085 end loop; 2086 2087 -- Now we can insert and analyze the pre-assignment 2088 2089 -- If the right-hand side requires a transient scope, it has 2090 -- already been placed on the stack. However, the declaration is 2091 -- inserted in the tree outside of this scope, and must reflect 2092 -- the proper scope for its variable. This awkward bit is forced 2093 -- by the stricter scope discipline imposed by GCC 2.97. 2094 2095 declare 2096 Uses_Transient_Scope : constant Boolean := 2097 Scope_Is_Transient 2098 and then N = Node_To_Be_Wrapped; 2099 2100 begin 2101 if Uses_Transient_Scope then 2102 Push_Scope (Scope (Current_Scope)); 2103 end if; 2104 2105 Insert_Before_And_Analyze (N, 2106 Make_Object_Declaration (Loc, 2107 Defining_Identifier => Tnn, 2108 Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc), 2109 Expression => BPAR_Expr)); 2110 2111 if Uses_Transient_Scope then 2112 Pop_Scope; 2113 end if; 2114 end; 2115 2116 -- Now fix up the original assignment and continue processing 2117 2118 Rewrite (Prefix (Lhs), 2119 New_Occurrence_Of (Tnn, Loc)); 2120 2121 -- We do not need to reanalyze that assignment, and we do not need 2122 -- to worry about references to the temporary, but we do need to 2123 -- make sure that the temporary is not marked as a true constant 2124 -- since we now have a generated assignment to it! 2125 2126 Set_Is_True_Constant (Tnn, False); 2127 end; 2128 end if; 2129 2130 -- When we have the appropriate type of aggregate in the expression (it 2131 -- has been determined during analysis of the aggregate by setting the 2132 -- delay flag), let's perform in place assignment and thus avoid 2133 -- creating a temporary. 2134 2135 if Is_Delayed_Aggregate (Rhs) then 2136 Convert_Aggr_In_Assignment (N); 2137 Rewrite (N, Make_Null_Statement (Loc)); 2138 Analyze (N); 2139 return; 2140 end if; 2141 2142 -- Apply discriminant check if required. If Lhs is an access type to a 2143 -- designated type with discriminants, we must always check. If the 2144 -- type has unknown discriminants, more elaborate processing below. 2145 2146 if Has_Discriminants (Etype (Lhs)) 2147 and then not Has_Unknown_Discriminants (Etype (Lhs)) 2148 then 2149 -- Skip discriminant check if change of representation. Will be 2150 -- done when the change of representation is expanded out. 2151 2152 if not Crep then 2153 Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs); 2154 end if; 2155 2156 -- If the type is private without discriminants, and the full type 2157 -- has discriminants (necessarily with defaults) a check may still be 2158 -- necessary if the Lhs is aliased. The private discriminants must be 2159 -- visible to build the discriminant constraints. 2160 2161 -- Only an explicit dereference that comes from source indicates 2162 -- aliasing. Access to formals of protected operations and entries 2163 -- create dereferences but are not semantic aliasings. 2164 2165 elsif Is_Private_Type (Etype (Lhs)) 2166 and then Has_Discriminants (Typ) 2167 and then Nkind (Lhs) = N_Explicit_Dereference 2168 and then Comes_From_Source (Lhs) 2169 then 2170 declare 2171 Lt : constant Entity_Id := Etype (Lhs); 2172 Ubt : Entity_Id := Base_Type (Typ); 2173 2174 begin 2175 -- In the case of an expander-generated record subtype whose base 2176 -- type still appears private, Typ will have been set to that 2177 -- private type rather than the underlying record type (because 2178 -- Underlying type will have returned the record subtype), so it's 2179 -- necessary to apply Underlying_Type again to the base type to 2180 -- get the record type we need for the discriminant check. Such 2181 -- subtypes can be created for assignments in certain cases, such 2182 -- as within an instantiation passed this kind of private type. 2183 -- It would be good to avoid this special test, but making changes 2184 -- to prevent this odd form of record subtype seems difficult. ??? 2185 2186 if Is_Private_Type (Ubt) then 2187 Ubt := Underlying_Type (Ubt); 2188 end if; 2189 2190 Set_Etype (Lhs, Ubt); 2191 Rewrite (Rhs, OK_Convert_To (Base_Type (Ubt), Rhs)); 2192 Apply_Discriminant_Check (Rhs, Ubt, Lhs); 2193 Set_Etype (Lhs, Lt); 2194 end; 2195 2196 -- If the Lhs has a private type with unknown discriminants, it 2197 -- may have a full view with discriminants, but those are nameable 2198 -- only in the underlying type, so convert the Rhs to it before 2199 -- potential checking. 2200 2201 elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs))) 2202 and then Has_Discriminants (Typ) 2203 then 2204 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs)); 2205 Apply_Discriminant_Check (Rhs, Typ, Lhs); 2206 2207 -- In the access type case, we need the same discriminant check, and 2208 -- also range checks if we have an access to constrained array. 2209 2210 elsif Is_Access_Type (Etype (Lhs)) 2211 and then Is_Constrained (Designated_Type (Etype (Lhs))) 2212 then 2213 if Has_Discriminants (Designated_Type (Etype (Lhs))) then 2214 2215 -- Skip discriminant check if change of representation. Will be 2216 -- done when the change of representation is expanded out. 2217 2218 if not Crep then 2219 Apply_Discriminant_Check (Rhs, Etype (Lhs)); 2220 end if; 2221 2222 elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then 2223 Apply_Range_Check (Rhs, Etype (Lhs)); 2224 2225 if Is_Constrained (Etype (Lhs)) then 2226 Apply_Length_Check (Rhs, Etype (Lhs)); 2227 end if; 2228 2229 if Nkind (Rhs) = N_Allocator then 2230 declare 2231 Target_Typ : constant Entity_Id := Etype (Expression (Rhs)); 2232 C_Es : Check_Result; 2233 2234 begin 2235 C_Es := 2236 Get_Range_Checks 2237 (Lhs, 2238 Target_Typ, 2239 Etype (Designated_Type (Etype (Lhs)))); 2240 2241 Insert_Range_Checks 2242 (C_Es, 2243 N, 2244 Target_Typ, 2245 Sloc (Lhs), 2246 Lhs); 2247 end; 2248 end if; 2249 end if; 2250 2251 -- Apply range check for access type case 2252 2253 elsif Is_Access_Type (Etype (Lhs)) 2254 and then Nkind (Rhs) = N_Allocator 2255 and then Nkind (Expression (Rhs)) = N_Qualified_Expression 2256 then 2257 Analyze_And_Resolve (Expression (Rhs)); 2258 Apply_Range_Check 2259 (Expression (Rhs), Designated_Type (Etype (Lhs))); 2260 end if; 2261 2262 -- Ada 2005 (AI-231): Generate the run-time check 2263 2264 if Is_Access_Type (Typ) 2265 and then Can_Never_Be_Null (Etype (Lhs)) 2266 and then not Can_Never_Be_Null (Etype (Rhs)) 2267 then 2268 Apply_Constraint_Check (Rhs, Etype (Lhs)); 2269 end if; 2270 2271 -- Ada 2012 (AI05-148): Update current accessibility level if Rhs is a 2272 -- stand-alone obj of an anonymous access type. 2273 2274 if Is_Access_Type (Typ) 2275 and then Is_Entity_Name (Lhs) 2276 and then Present (Effective_Extra_Accessibility (Entity (Lhs))) then 2277 declare 2278 function Lhs_Entity return Entity_Id; 2279 -- Look through renames to find the underlying entity. 2280 -- For assignment to a rename, we don't care about the 2281 -- Enclosing_Dynamic_Scope of the rename declaration. 2282 2283 ---------------- 2284 -- Lhs_Entity -- 2285 ---------------- 2286 2287 function Lhs_Entity return Entity_Id is 2288 Result : Entity_Id := Entity (Lhs); 2289 2290 begin 2291 while Present (Renamed_Object (Result)) loop 2292 2293 -- Renamed_Object must return an Entity_Name here 2294 -- because of preceding "Present (E_E_A (...))" test. 2295 2296 Result := Entity (Renamed_Object (Result)); 2297 end loop; 2298 2299 return Result; 2300 end Lhs_Entity; 2301 2302 -- Local Declarations 2303 2304 Access_Check : constant Node_Id := 2305 Make_Raise_Program_Error (Loc, 2306 Condition => 2307 Make_Op_Gt (Loc, 2308 Left_Opnd => 2309 Dynamic_Accessibility_Level (Rhs), 2310 Right_Opnd => 2311 Make_Integer_Literal (Loc, 2312 Intval => 2313 Scope_Depth 2314 (Enclosing_Dynamic_Scope 2315 (Lhs_Entity)))), 2316 Reason => PE_Accessibility_Check_Failed); 2317 2318 Access_Level_Update : constant Node_Id := 2319 Make_Assignment_Statement (Loc, 2320 Name => 2321 New_Occurrence_Of 2322 (Effective_Extra_Accessibility 2323 (Entity (Lhs)), Loc), 2324 Expression => 2325 Dynamic_Accessibility_Level (Rhs)); 2326 2327 begin 2328 if not Accessibility_Checks_Suppressed (Entity (Lhs)) then 2329 Insert_Action (N, Access_Check); 2330 end if; 2331 2332 Insert_Action (N, Access_Level_Update); 2333 end; 2334 end if; 2335 2336 -- Case of assignment to a bit packed array element. If there is a 2337 -- change of representation this must be expanded into components, 2338 -- otherwise this is a bit-field assignment. 2339 2340 if Nkind (Lhs) = N_Indexed_Component 2341 and then Is_Bit_Packed_Array (Etype (Prefix (Lhs))) 2342 then 2343 -- Normal case, no change of representation 2344 2345 if not Crep then 2346 Expand_Bit_Packed_Element_Set (N); 2347 return; 2348 2349 -- Change of representation case 2350 2351 else 2352 -- Generate the following, to force component-by-component 2353 -- assignments in an efficient way. Otherwise each component 2354 -- will require a temporary and two bit-field manipulations. 2355 2356 -- T1 : Elmt_Type; 2357 -- T1 := RhS; 2358 -- Lhs := T1; 2359 2360 declare 2361 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T'); 2362 Stats : List_Id; 2363 2364 begin 2365 Stats := 2366 New_List ( 2367 Make_Object_Declaration (Loc, 2368 Defining_Identifier => Tnn, 2369 Object_Definition => 2370 New_Occurrence_Of (Etype (Lhs), Loc)), 2371 Make_Assignment_Statement (Loc, 2372 Name => New_Occurrence_Of (Tnn, Loc), 2373 Expression => Relocate_Node (Rhs)), 2374 Make_Assignment_Statement (Loc, 2375 Name => Relocate_Node (Lhs), 2376 Expression => New_Occurrence_Of (Tnn, Loc))); 2377 2378 Insert_Actions (N, Stats); 2379 Rewrite (N, Make_Null_Statement (Loc)); 2380 Analyze (N); 2381 end; 2382 end if; 2383 2384 -- Build-in-place function call case. Note that we're not yet doing 2385 -- build-in-place for user-written assignment statements (the assignment 2386 -- here came from an aggregate.) 2387 2388 elsif Ada_Version >= Ada_2005 2389 and then Is_Build_In_Place_Function_Call (Rhs) 2390 then 2391 Make_Build_In_Place_Call_In_Assignment (N, Rhs); 2392 2393 elsif Is_Tagged_Type (Typ) and then Is_Value_Type (Etype (Lhs)) then 2394 2395 -- Nothing to do for valuetypes 2396 -- ??? Set_Scope_Is_Transient (False); 2397 2398 return; 2399 2400 elsif Is_Tagged_Type (Typ) 2401 or else (Needs_Finalization (Typ) and then not Is_Array_Type (Typ)) 2402 then 2403 Tagged_Case : declare 2404 L : List_Id := No_List; 2405 Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N); 2406 2407 begin 2408 -- In the controlled case, we ensure that function calls are 2409 -- evaluated before finalizing the target. In all cases, it makes 2410 -- the expansion easier if the side-effects are removed first. 2411 2412 Remove_Side_Effects (Lhs); 2413 Remove_Side_Effects (Rhs); 2414 2415 -- Avoid recursion in the mechanism 2416 2417 Set_Analyzed (N); 2418 2419 -- If dispatching assignment, we need to dispatch to _assign 2420 2421 if Is_Class_Wide_Type (Typ) 2422 2423 -- If the type is tagged, we may as well use the predefined 2424 -- primitive assignment. This avoids inlining a lot of code 2425 -- and in the class-wide case, the assignment is replaced 2426 -- by a dispatching call to _assign. It is suppressed in the 2427 -- case of assignments created by the expander that correspond 2428 -- to initializations, where we do want to copy the tag 2429 -- (Expand_Ctrl_Actions flag is set True in this case). It is 2430 -- also suppressed if restriction No_Dispatching_Calls is in 2431 -- force because in that case predefined primitives are not 2432 -- generated. 2433 2434 or else (Is_Tagged_Type (Typ) 2435 and then not Is_Value_Type (Etype (Lhs)) 2436 and then Chars (Current_Scope) /= Name_uAssign 2437 and then Expand_Ctrl_Actions 2438 and then 2439 not Restriction_Active (No_Dispatching_Calls)) 2440 then 2441 if Is_Limited_Type (Typ) then 2442 2443 -- This can happen in an instance when the formal is an 2444 -- extension of a limited interface, and the actual is 2445 -- limited. This is an error according to AI05-0087, but 2446 -- is not caught at the point of instantiation in earlier 2447 -- versions. 2448 2449 -- This is wrong, error messages cannot be issued during 2450 -- expansion, since they would be missed in -gnatc mode ??? 2451 2452 Error_Msg_N ("assignment not available on limited type", N); 2453 return; 2454 end if; 2455 2456 -- Fetch the primitive op _assign and proper type to call it. 2457 -- Because of possible conflicts between private and full view, 2458 -- fetch the proper type directly from the operation profile. 2459 2460 declare 2461 Op : constant Entity_Id := 2462 Find_Prim_Op (Typ, Name_uAssign); 2463 F_Typ : Entity_Id := Etype (First_Formal (Op)); 2464 2465 begin 2466 -- If the assignment is dispatching, make sure to use the 2467 -- proper type. 2468 2469 if Is_Class_Wide_Type (Typ) then 2470 F_Typ := Class_Wide_Type (F_Typ); 2471 end if; 2472 2473 L := New_List; 2474 2475 -- In case of assignment to a class-wide tagged type, before 2476 -- the assignment we generate run-time check to ensure that 2477 -- the tags of source and target match. 2478 2479 if not Tag_Checks_Suppressed (Typ) 2480 and then Is_Class_Wide_Type (Typ) 2481 and then Is_Tagged_Type (Typ) 2482 and then Is_Tagged_Type (Underlying_Type (Etype (Rhs))) 2483 then 2484 Append_To (L, 2485 Make_Raise_Constraint_Error (Loc, 2486 Condition => 2487 Make_Op_Ne (Loc, 2488 Left_Opnd => 2489 Make_Selected_Component (Loc, 2490 Prefix => Duplicate_Subexpr (Lhs), 2491 Selector_Name => 2492 Make_Identifier (Loc, Name_uTag)), 2493 Right_Opnd => 2494 Make_Selected_Component (Loc, 2495 Prefix => Duplicate_Subexpr (Rhs), 2496 Selector_Name => 2497 Make_Identifier (Loc, Name_uTag))), 2498 Reason => CE_Tag_Check_Failed)); 2499 end if; 2500 2501 declare 2502 Left_N : Node_Id := Duplicate_Subexpr (Lhs); 2503 Right_N : Node_Id := Duplicate_Subexpr (Rhs); 2504 2505 begin 2506 -- In order to dispatch the call to _assign the type of 2507 -- the actuals must match. Add conversion (if required). 2508 2509 if Etype (Lhs) /= F_Typ then 2510 Left_N := Unchecked_Convert_To (F_Typ, Left_N); 2511 end if; 2512 2513 if Etype (Rhs) /= F_Typ then 2514 Right_N := Unchecked_Convert_To (F_Typ, Right_N); 2515 end if; 2516 2517 Append_To (L, 2518 Make_Procedure_Call_Statement (Loc, 2519 Name => New_Reference_To (Op, Loc), 2520 Parameter_Associations => New_List ( 2521 Node1 => Left_N, 2522 Node2 => Right_N))); 2523 end; 2524 end; 2525 2526 else 2527 L := Make_Tag_Ctrl_Assignment (N); 2528 2529 -- We can't afford to have destructive Finalization Actions in 2530 -- the Self assignment case, so if the target and the source 2531 -- are not obviously different, code is generated to avoid the 2532 -- self assignment case: 2533 2534 -- if lhs'address /= rhs'address then 2535 -- <code for controlled and/or tagged assignment> 2536 -- end if; 2537 2538 -- Skip this if Restriction (No_Finalization) is active 2539 2540 if not Statically_Different (Lhs, Rhs) 2541 and then Expand_Ctrl_Actions 2542 and then not Restriction_Active (No_Finalization) 2543 then 2544 L := New_List ( 2545 Make_Implicit_If_Statement (N, 2546 Condition => 2547 Make_Op_Ne (Loc, 2548 Left_Opnd => 2549 Make_Attribute_Reference (Loc, 2550 Prefix => Duplicate_Subexpr (Lhs), 2551 Attribute_Name => Name_Address), 2552 2553 Right_Opnd => 2554 Make_Attribute_Reference (Loc, 2555 Prefix => Duplicate_Subexpr (Rhs), 2556 Attribute_Name => Name_Address)), 2557 2558 Then_Statements => L)); 2559 end if; 2560 2561 -- We need to set up an exception handler for implementing 2562 -- 7.6.1(18). The remaining adjustments are tackled by the 2563 -- implementation of adjust for record_controllers (see 2564 -- s-finimp.adb). 2565 2566 -- This is skipped if we have no finalization 2567 2568 if Expand_Ctrl_Actions 2569 and then not Restriction_Active (No_Finalization) 2570 then 2571 L := New_List ( 2572 Make_Block_Statement (Loc, 2573 Handled_Statement_Sequence => 2574 Make_Handled_Sequence_Of_Statements (Loc, 2575 Statements => L, 2576 Exception_Handlers => New_List ( 2577 Make_Handler_For_Ctrl_Operation (Loc))))); 2578 end if; 2579 end if; 2580 2581 Rewrite (N, 2582 Make_Block_Statement (Loc, 2583 Handled_Statement_Sequence => 2584 Make_Handled_Sequence_Of_Statements (Loc, Statements => L))); 2585 2586 -- If no restrictions on aborts, protect the whole assignment 2587 -- for controlled objects as per 9.8(11). 2588 2589 if Needs_Finalization (Typ) 2590 and then Expand_Ctrl_Actions 2591 and then Abort_Allowed 2592 then 2593 declare 2594 Blk : constant Entity_Id := 2595 New_Internal_Entity 2596 (E_Block, Current_Scope, Sloc (N), 'B'); 2597 2598 begin 2599 Set_Scope (Blk, Current_Scope); 2600 Set_Etype (Blk, Standard_Void_Type); 2601 Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N))); 2602 2603 Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer)); 2604 Set_At_End_Proc (Handled_Statement_Sequence (N), 2605 New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc)); 2606 Expand_At_End_Handler 2607 (Handled_Statement_Sequence (N), Blk); 2608 end; 2609 end if; 2610 2611 -- N has been rewritten to a block statement for which it is 2612 -- known by construction that no checks are necessary: analyze 2613 -- it with all checks suppressed. 2614 2615 Analyze (N, Suppress => All_Checks); 2616 return; 2617 end Tagged_Case; 2618 2619 -- Array types 2620 2621 elsif Is_Array_Type (Typ) then 2622 declare 2623 Actual_Rhs : Node_Id := Rhs; 2624 2625 begin 2626 while Nkind_In (Actual_Rhs, N_Type_Conversion, 2627 N_Qualified_Expression) 2628 loop 2629 Actual_Rhs := Expression (Actual_Rhs); 2630 end loop; 2631 2632 Expand_Assign_Array (N, Actual_Rhs); 2633 return; 2634 end; 2635 2636 -- Record types 2637 2638 elsif Is_Record_Type (Typ) then 2639 Expand_Assign_Record (N); 2640 return; 2641 2642 -- Scalar types. This is where we perform the processing related to the 2643 -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid 2644 -- scalar values. 2645 2646 elsif Is_Scalar_Type (Typ) then 2647 2648 -- Case where right side is known valid 2649 2650 if Expr_Known_Valid (Rhs) then 2651 2652 -- Here the right side is valid, so it is fine. The case to deal 2653 -- with is when the left side is a local variable reference whose 2654 -- value is not currently known to be valid. If this is the case, 2655 -- and the assignment appears in an unconditional context, then 2656 -- we can mark the left side as now being valid if one of these 2657 -- conditions holds: 2658 2659 -- The expression of the right side has Do_Range_Check set so 2660 -- that we know a range check will be performed. Note that it 2661 -- can be the case that a range check is omitted because we 2662 -- make the assumption that we can assume validity for operands 2663 -- appearing in the right side in determining whether a range 2664 -- check is required 2665 2666 -- The subtype of the right side matches the subtype of the 2667 -- left side. In this case, even though we have not checked 2668 -- the range of the right side, we know it is in range of its 2669 -- subtype if the expression is valid. 2670 2671 if Is_Local_Variable_Reference (Lhs) 2672 and then not Is_Known_Valid (Entity (Lhs)) 2673 and then In_Unconditional_Context (N) 2674 then 2675 if Do_Range_Check (Rhs) 2676 or else Etype (Lhs) = Etype (Rhs) 2677 then 2678 Set_Is_Known_Valid (Entity (Lhs), True); 2679 end if; 2680 end if; 2681 2682 -- Case where right side may be invalid in the sense of the RM 2683 -- reference above. The RM does not require that we check for the 2684 -- validity on an assignment, but it does require that the assignment 2685 -- of an invalid value not cause erroneous behavior. 2686 2687 -- The general approach in GNAT is to use the Is_Known_Valid flag 2688 -- to avoid the need for validity checking on assignments. However 2689 -- in some cases, we have to do validity checking in order to make 2690 -- sure that the setting of this flag is correct. 2691 2692 else 2693 -- Validate right side if we are validating copies 2694 2695 if Validity_Checks_On 2696 and then Validity_Check_Copies 2697 then 2698 -- Skip this if left hand side is an array or record component 2699 -- and elementary component validity checks are suppressed. 2700 2701 if Nkind_In (Lhs, N_Selected_Component, N_Indexed_Component) 2702 and then not Validity_Check_Components 2703 then 2704 null; 2705 else 2706 Ensure_Valid (Rhs); 2707 end if; 2708 2709 -- We can propagate this to the left side where appropriate 2710 2711 if Is_Local_Variable_Reference (Lhs) 2712 and then not Is_Known_Valid (Entity (Lhs)) 2713 and then In_Unconditional_Context (N) 2714 then 2715 Set_Is_Known_Valid (Entity (Lhs), True); 2716 end if; 2717 2718 -- Otherwise check to see what should be done 2719 2720 -- If left side is a local variable, then we just set its flag to 2721 -- indicate that its value may no longer be valid, since we are 2722 -- copying a potentially invalid value. 2723 2724 elsif Is_Local_Variable_Reference (Lhs) then 2725 Set_Is_Known_Valid (Entity (Lhs), False); 2726 2727 -- Check for case of a nonlocal variable on the left side which 2728 -- is currently known to be valid. In this case, we simply ensure 2729 -- that the right side is valid. We only play the game of copying 2730 -- validity status for local variables, since we are doing this 2731 -- statically, not by tracing the full flow graph. 2732 2733 elsif Is_Entity_Name (Lhs) 2734 and then Is_Known_Valid (Entity (Lhs)) 2735 then 2736 -- Note: If Validity_Checking mode is set to none, we ignore 2737 -- the Ensure_Valid call so don't worry about that case here. 2738 2739 Ensure_Valid (Rhs); 2740 2741 -- In all other cases, we can safely copy an invalid value without 2742 -- worrying about the status of the left side. Since it is not a 2743 -- variable reference it will not be considered 2744 -- as being known to be valid in any case. 2745 2746 else 2747 null; 2748 end if; 2749 end if; 2750 end if; 2751 2752 exception 2753 when RE_Not_Available => 2754 return; 2755 end Expand_N_Assignment_Statement; 2756 2757 ------------------------------ 2758 -- Expand_N_Block_Statement -- 2759 ------------------------------ 2760 2761 -- Encode entity names defined in block statement 2762 2763 procedure Expand_N_Block_Statement (N : Node_Id) is 2764 begin 2765 Qualify_Entity_Names (N); 2766 end Expand_N_Block_Statement; 2767 2768 ----------------------------- 2769 -- Expand_N_Case_Statement -- 2770 ----------------------------- 2771 2772 procedure Expand_N_Case_Statement (N : Node_Id) is 2773 Loc : constant Source_Ptr := Sloc (N); 2774 Expr : constant Node_Id := Expression (N); 2775 Alt : Node_Id; 2776 Len : Nat; 2777 Cond : Node_Id; 2778 Choice : Node_Id; 2779 Chlist : List_Id; 2780 2781 begin 2782 -- Check for the situation where we know at compile time which branch 2783 -- will be taken 2784 2785 if Compile_Time_Known_Value (Expr) then 2786 Alt := Find_Static_Alternative (N); 2787 2788 Process_Statements_For_Controlled_Objects (Alt); 2789 2790 -- Move statements from this alternative after the case statement. 2791 -- They are already analyzed, so will be skipped by the analyzer. 2792 2793 Insert_List_After (N, Statements (Alt)); 2794 2795 -- That leaves the case statement as a shell. So now we can kill all 2796 -- other alternatives in the case statement. 2797 2798 Kill_Dead_Code (Expression (N)); 2799 2800 declare 2801 Dead_Alt : Node_Id; 2802 2803 begin 2804 -- Loop through case alternatives, skipping pragmas, and skipping 2805 -- the one alternative that we select (and therefore retain). 2806 2807 Dead_Alt := First (Alternatives (N)); 2808 while Present (Dead_Alt) loop 2809 if Dead_Alt /= Alt 2810 and then Nkind (Dead_Alt) = N_Case_Statement_Alternative 2811 then 2812 Kill_Dead_Code (Statements (Dead_Alt), Warn_On_Deleted_Code); 2813 end if; 2814 2815 Next (Dead_Alt); 2816 end loop; 2817 end; 2818 2819 Rewrite (N, Make_Null_Statement (Loc)); 2820 return; 2821 end if; 2822 2823 -- Here if the choice is not determined at compile time 2824 2825 declare 2826 Last_Alt : constant Node_Id := Last (Alternatives (N)); 2827 2828 Others_Present : Boolean; 2829 Others_Node : Node_Id; 2830 2831 Then_Stms : List_Id; 2832 Else_Stms : List_Id; 2833 2834 begin 2835 if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then 2836 Others_Present := True; 2837 Others_Node := Last_Alt; 2838 else 2839 Others_Present := False; 2840 end if; 2841 2842 -- First step is to worry about possible invalid argument. The RM 2843 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is 2844 -- outside the base range), then Constraint_Error must be raised. 2845 2846 -- Case of validity check required (validity checks are on, the 2847 -- expression is not known to be valid, and the case statement 2848 -- comes from source -- no need to validity check internally 2849 -- generated case statements). 2850 2851 if Validity_Check_Default then 2852 Ensure_Valid (Expr); 2853 end if; 2854 2855 -- If there is only a single alternative, just replace it with the 2856 -- sequence of statements since obviously that is what is going to 2857 -- be executed in all cases. 2858 2859 Len := List_Length (Alternatives (N)); 2860 2861 if Len = 1 then 2862 2863 -- We still need to evaluate the expression if it has any side 2864 -- effects. 2865 2866 Remove_Side_Effects (Expression (N)); 2867 2868 Alt := First (Alternatives (N)); 2869 2870 Process_Statements_For_Controlled_Objects (Alt); 2871 Insert_List_After (N, Statements (Alt)); 2872 2873 -- That leaves the case statement as a shell. The alternative that 2874 -- will be executed is reset to a null list. So now we can kill 2875 -- the entire case statement. 2876 2877 Kill_Dead_Code (Expression (N)); 2878 Rewrite (N, Make_Null_Statement (Loc)); 2879 return; 2880 2881 -- An optimization. If there are only two alternatives, and only 2882 -- a single choice, then rewrite the whole case statement as an 2883 -- if statement, since this can result in subsequent optimizations. 2884 -- This helps not only with case statements in the source of a 2885 -- simple form, but also with generated code (discriminant check 2886 -- functions in particular) 2887 2888 elsif Len = 2 then 2889 Chlist := Discrete_Choices (First (Alternatives (N))); 2890 2891 if List_Length (Chlist) = 1 then 2892 Choice := First (Chlist); 2893 2894 Then_Stms := Statements (First (Alternatives (N))); 2895 Else_Stms := Statements (Last (Alternatives (N))); 2896 2897 -- For TRUE, generate "expression", not expression = true 2898 2899 if Nkind (Choice) = N_Identifier 2900 and then Entity (Choice) = Standard_True 2901 then 2902 Cond := Expression (N); 2903 2904 -- For FALSE, generate "expression" and switch then/else 2905 2906 elsif Nkind (Choice) = N_Identifier 2907 and then Entity (Choice) = Standard_False 2908 then 2909 Cond := Expression (N); 2910 Else_Stms := Statements (First (Alternatives (N))); 2911 Then_Stms := Statements (Last (Alternatives (N))); 2912 2913 -- For a range, generate "expression in range" 2914 2915 elsif Nkind (Choice) = N_Range 2916 or else (Nkind (Choice) = N_Attribute_Reference 2917 and then Attribute_Name (Choice) = Name_Range) 2918 or else (Is_Entity_Name (Choice) 2919 and then Is_Type (Entity (Choice))) 2920 or else Nkind (Choice) = N_Subtype_Indication 2921 then 2922 Cond := 2923 Make_In (Loc, 2924 Left_Opnd => Expression (N), 2925 Right_Opnd => Relocate_Node (Choice)); 2926 2927 -- For any other subexpression "expression = value" 2928 2929 else 2930 Cond := 2931 Make_Op_Eq (Loc, 2932 Left_Opnd => Expression (N), 2933 Right_Opnd => Relocate_Node (Choice)); 2934 end if; 2935 2936 -- Now rewrite the case as an IF 2937 2938 Rewrite (N, 2939 Make_If_Statement (Loc, 2940 Condition => Cond, 2941 Then_Statements => Then_Stms, 2942 Else_Statements => Else_Stms)); 2943 Analyze (N); 2944 return; 2945 end if; 2946 end if; 2947 2948 -- If the last alternative is not an Others choice, replace it with 2949 -- an N_Others_Choice. Note that we do not bother to call Analyze on 2950 -- the modified case statement, since it's only effect would be to 2951 -- compute the contents of the Others_Discrete_Choices which is not 2952 -- needed by the back end anyway. 2953 2954 -- The reason we do this is that the back end always needs some 2955 -- default for a switch, so if we have not supplied one in the 2956 -- processing above for validity checking, then we need to supply 2957 -- one here. 2958 2959 if not Others_Present then 2960 Others_Node := Make_Others_Choice (Sloc (Last_Alt)); 2961 Set_Others_Discrete_Choices 2962 (Others_Node, Discrete_Choices (Last_Alt)); 2963 Set_Discrete_Choices (Last_Alt, New_List (Others_Node)); 2964 end if; 2965 2966 Alt := First (Alternatives (N)); 2967 while Present (Alt) 2968 and then Nkind (Alt) = N_Case_Statement_Alternative 2969 loop 2970 Process_Statements_For_Controlled_Objects (Alt); 2971 Next (Alt); 2972 end loop; 2973 end; 2974 end Expand_N_Case_Statement; 2975 2976 ----------------------------- 2977 -- Expand_N_Exit_Statement -- 2978 ----------------------------- 2979 2980 -- The only processing required is to deal with a possible C/Fortran 2981 -- boolean value used as the condition for the exit statement. 2982 2983 procedure Expand_N_Exit_Statement (N : Node_Id) is 2984 begin 2985 Adjust_Condition (Condition (N)); 2986 end Expand_N_Exit_Statement; 2987 2988 ----------------------------- 2989 -- Expand_N_Goto_Statement -- 2990 ----------------------------- 2991 2992 -- Add poll before goto if polling active 2993 2994 procedure Expand_N_Goto_Statement (N : Node_Id) is 2995 begin 2996 Generate_Poll_Call (N); 2997 end Expand_N_Goto_Statement; 2998 2999 --------------------------- 3000 -- Expand_N_If_Statement -- 3001 --------------------------- 3002 3003 -- First we deal with the case of C and Fortran convention boolean values, 3004 -- with zero/non-zero semantics. 3005 3006 -- Second, we deal with the obvious rewriting for the cases where the 3007 -- condition of the IF is known at compile time to be True or False. 3008 3009 -- Third, we remove elsif parts which have non-empty Condition_Actions and 3010 -- rewrite as independent if statements. For example: 3011 3012 -- if x then xs 3013 -- elsif y then ys 3014 -- ... 3015 -- end if; 3016 3017 -- becomes 3018 -- 3019 -- if x then xs 3020 -- else 3021 -- <<condition actions of y>> 3022 -- if y then ys 3023 -- ... 3024 -- end if; 3025 -- end if; 3026 3027 -- This rewriting is needed if at least one elsif part has a non-empty 3028 -- Condition_Actions list. We also do the same processing if there is a 3029 -- constant condition in an elsif part (in conjunction with the first 3030 -- processing step mentioned above, for the recursive call made to deal 3031 -- with the created inner if, this deals with properly optimizing the 3032 -- cases of constant elsif conditions). 3033 3034 procedure Expand_N_If_Statement (N : Node_Id) is 3035 Loc : constant Source_Ptr := Sloc (N); 3036 Hed : Node_Id; 3037 E : Node_Id; 3038 New_If : Node_Id; 3039 3040 Warn_If_Deleted : constant Boolean := 3041 Warn_On_Deleted_Code and then Comes_From_Source (N); 3042 -- Indicates whether we want warnings when we delete branches of the 3043 -- if statement based on constant condition analysis. We never want 3044 -- these warnings for expander generated code. 3045 3046 begin 3047 Process_Statements_For_Controlled_Objects (N); 3048 3049 Adjust_Condition (Condition (N)); 3050 3051 -- The following loop deals with constant conditions for the IF. We 3052 -- need a loop because as we eliminate False conditions, we grab the 3053 -- first elsif condition and use it as the primary condition. 3054 3055 while Compile_Time_Known_Value (Condition (N)) loop 3056 3057 -- If condition is True, we can simply rewrite the if statement now 3058 -- by replacing it by the series of then statements. 3059 3060 if Is_True (Expr_Value (Condition (N))) then 3061 3062 -- All the else parts can be killed 3063 3064 Kill_Dead_Code (Elsif_Parts (N), Warn_If_Deleted); 3065 Kill_Dead_Code (Else_Statements (N), Warn_If_Deleted); 3066 3067 Hed := Remove_Head (Then_Statements (N)); 3068 Insert_List_After (N, Then_Statements (N)); 3069 Rewrite (N, Hed); 3070 return; 3071 3072 -- If condition is False, then we can delete the condition and 3073 -- the Then statements 3074 3075 else 3076 -- We do not delete the condition if constant condition warnings 3077 -- are enabled, since otherwise we end up deleting the desired 3078 -- warning. Of course the backend will get rid of this True/False 3079 -- test anyway, so nothing is lost here. 3080 3081 if not Constant_Condition_Warnings then 3082 Kill_Dead_Code (Condition (N)); 3083 end if; 3084 3085 Kill_Dead_Code (Then_Statements (N), Warn_If_Deleted); 3086 3087 -- If there are no elsif statements, then we simply replace the 3088 -- entire if statement by the sequence of else statements. 3089 3090 if No (Elsif_Parts (N)) then 3091 if No (Else_Statements (N)) 3092 or else Is_Empty_List (Else_Statements (N)) 3093 then 3094 Rewrite (N, 3095 Make_Null_Statement (Sloc (N))); 3096 else 3097 Hed := Remove_Head (Else_Statements (N)); 3098 Insert_List_After (N, Else_Statements (N)); 3099 Rewrite (N, Hed); 3100 end if; 3101 3102 return; 3103 3104 -- If there are elsif statements, the first of them becomes the 3105 -- if/then section of the rebuilt if statement This is the case 3106 -- where we loop to reprocess this copied condition. 3107 3108 else 3109 Hed := Remove_Head (Elsif_Parts (N)); 3110 Insert_Actions (N, Condition_Actions (Hed)); 3111 Set_Condition (N, Condition (Hed)); 3112 Set_Then_Statements (N, Then_Statements (Hed)); 3113 3114 -- Hed might have been captured as the condition determining 3115 -- the current value for an entity. Now it is detached from 3116 -- the tree, so a Current_Value pointer in the condition might 3117 -- need to be updated. 3118 3119 Set_Current_Value_Condition (N); 3120 3121 if Is_Empty_List (Elsif_Parts (N)) then 3122 Set_Elsif_Parts (N, No_List); 3123 end if; 3124 end if; 3125 end if; 3126 end loop; 3127 3128 -- Loop through elsif parts, dealing with constant conditions and 3129 -- possible condition actions that are present. 3130 3131 if Present (Elsif_Parts (N)) then 3132 E := First (Elsif_Parts (N)); 3133 while Present (E) loop 3134 Process_Statements_For_Controlled_Objects (E); 3135 3136 Adjust_Condition (Condition (E)); 3137 3138 -- If there are condition actions, then rewrite the if statement 3139 -- as indicated above. We also do the same rewrite for a True or 3140 -- False condition. The further processing of this constant 3141 -- condition is then done by the recursive call to expand the 3142 -- newly created if statement 3143 3144 if Present (Condition_Actions (E)) 3145 or else Compile_Time_Known_Value (Condition (E)) 3146 then 3147 -- Note this is not an implicit if statement, since it is part 3148 -- of an explicit if statement in the source (or of an implicit 3149 -- if statement that has already been tested). 3150 3151 New_If := 3152 Make_If_Statement (Sloc (E), 3153 Condition => Condition (E), 3154 Then_Statements => Then_Statements (E), 3155 Elsif_Parts => No_List, 3156 Else_Statements => Else_Statements (N)); 3157 3158 -- Elsif parts for new if come from remaining elsif's of parent 3159 3160 while Present (Next (E)) loop 3161 if No (Elsif_Parts (New_If)) then 3162 Set_Elsif_Parts (New_If, New_List); 3163 end if; 3164 3165 Append (Remove_Next (E), Elsif_Parts (New_If)); 3166 end loop; 3167 3168 Set_Else_Statements (N, New_List (New_If)); 3169 3170 if Present (Condition_Actions (E)) then 3171 Insert_List_Before (New_If, Condition_Actions (E)); 3172 end if; 3173 3174 Remove (E); 3175 3176 if Is_Empty_List (Elsif_Parts (N)) then 3177 Set_Elsif_Parts (N, No_List); 3178 end if; 3179 3180 Analyze (New_If); 3181 return; 3182 3183 -- No special processing for that elsif part, move to next 3184 3185 else 3186 Next (E); 3187 end if; 3188 end loop; 3189 end if; 3190 3191 -- Some more optimizations applicable if we still have an IF statement 3192 3193 if Nkind (N) /= N_If_Statement then 3194 return; 3195 end if; 3196 3197 -- Another optimization, special cases that can be simplified 3198 3199 -- if expression then 3200 -- return true; 3201 -- else 3202 -- return false; 3203 -- end if; 3204 3205 -- can be changed to: 3206 3207 -- return expression; 3208 3209 -- and 3210 3211 -- if expression then 3212 -- return false; 3213 -- else 3214 -- return true; 3215 -- end if; 3216 3217 -- can be changed to: 3218 3219 -- return not (expression); 3220 3221 -- Only do these optimizations if we are at least at -O1 level and 3222 -- do not do them if control flow optimizations are suppressed. 3223 3224 if Optimization_Level > 0 3225 and then not Opt.Suppress_Control_Flow_Optimizations 3226 then 3227 if Nkind (N) = N_If_Statement 3228 and then No (Elsif_Parts (N)) 3229 and then Present (Else_Statements (N)) 3230 and then List_Length (Then_Statements (N)) = 1 3231 and then List_Length (Else_Statements (N)) = 1 3232 then 3233 declare 3234 Then_Stm : constant Node_Id := First (Then_Statements (N)); 3235 Else_Stm : constant Node_Id := First (Else_Statements (N)); 3236 3237 begin 3238 if Nkind (Then_Stm) = N_Simple_Return_Statement 3239 and then 3240 Nkind (Else_Stm) = N_Simple_Return_Statement 3241 then 3242 declare 3243 Then_Expr : constant Node_Id := Expression (Then_Stm); 3244 Else_Expr : constant Node_Id := Expression (Else_Stm); 3245 3246 begin 3247 if Nkind (Then_Expr) = N_Identifier 3248 and then 3249 Nkind (Else_Expr) = N_Identifier 3250 then 3251 if Entity (Then_Expr) = Standard_True 3252 and then Entity (Else_Expr) = Standard_False 3253 then 3254 Rewrite (N, 3255 Make_Simple_Return_Statement (Loc, 3256 Expression => Relocate_Node (Condition (N)))); 3257 Analyze (N); 3258 return; 3259 3260 elsif Entity (Then_Expr) = Standard_False 3261 and then Entity (Else_Expr) = Standard_True 3262 then 3263 Rewrite (N, 3264 Make_Simple_Return_Statement (Loc, 3265 Expression => 3266 Make_Op_Not (Loc, 3267 Right_Opnd => 3268 Relocate_Node (Condition (N))))); 3269 Analyze (N); 3270 return; 3271 end if; 3272 end if; 3273 end; 3274 end if; 3275 end; 3276 end if; 3277 end if; 3278 end Expand_N_If_Statement; 3279 3280 -------------------------- 3281 -- Expand_Iterator_Loop -- 3282 -------------------------- 3283 3284 procedure Expand_Iterator_Loop (N : Node_Id) is 3285 Isc : constant Node_Id := Iteration_Scheme (N); 3286 I_Spec : constant Node_Id := Iterator_Specification (Isc); 3287 Id : constant Entity_Id := Defining_Identifier (I_Spec); 3288 Loc : constant Source_Ptr := Sloc (N); 3289 3290 Container : constant Node_Id := Name (I_Spec); 3291 Container_Typ : constant Entity_Id := Base_Type (Etype (Container)); 3292 Cursor : Entity_Id; 3293 Iterator : Entity_Id; 3294 New_Loop : Node_Id; 3295 Stats : List_Id := Statements (N); 3296 3297 begin 3298 -- Processing for arrays 3299 3300 if Is_Array_Type (Container_Typ) then 3301 Expand_Iterator_Loop_Over_Array (N); 3302 return; 3303 end if; 3304 3305 -- Processing for containers 3306 3307 -- For an "of" iterator the name is a container expression, which 3308 -- is transformed into a call to the default iterator. 3309 3310 -- For an iterator of the form "in" the name is a function call 3311 -- that delivers an iterator type. 3312 3313 -- In both cases, analysis of the iterator has introduced an object 3314 -- declaration to capture the domain, so that Container is an entity. 3315 3316 -- The for loop is expanded into a while loop which uses a container 3317 -- specific cursor to desgnate each element. 3318 3319 -- Iter : Iterator_Type := Container.Iterate; 3320 -- Cursor : Cursor_type := First (Iter); 3321 -- while Has_Element (Iter) loop 3322 -- declare 3323 -- -- The block is added when Element_Type is controlled 3324 3325 -- Obj : Pack.Element_Type := Element (Cursor); 3326 -- -- for the "of" loop form 3327 -- begin 3328 -- <original loop statements> 3329 -- end; 3330 3331 -- Cursor := Iter.Next (Cursor); 3332 -- end loop; 3333 3334 -- If "reverse" is present, then the initialization of the cursor 3335 -- uses Last and the step becomes Prev. Pack is the name of the 3336 -- scope where the container package is instantiated. 3337 3338 declare 3339 Element_Type : constant Entity_Id := Etype (Id); 3340 Iter_Type : Entity_Id; 3341 Pack : Entity_Id; 3342 Decl : Node_Id; 3343 Name_Init : Name_Id; 3344 Name_Step : Name_Id; 3345 3346 begin 3347 -- The type of the iterator is the return type of the Iterate 3348 -- function used. For the "of" form this is the default iterator 3349 -- for the type, otherwise it is the type of the explicit 3350 -- function used in the iterator specification. The most common 3351 -- case will be an Iterate function in the container package. 3352 3353 -- The primitive operations of the container type may not be 3354 -- use-visible, so we introduce the name of the enclosing package 3355 -- in the declarations below. The Iterator type is declared in a 3356 -- an instance within the container package itself. 3357 3358 -- If the container type is a derived type, the cursor type is 3359 -- found in the package of the parent type. 3360 3361 if Is_Derived_Type (Container_Typ) then 3362 Pack := Scope (Root_Type (Container_Typ)); 3363 else 3364 Pack := Scope (Container_Typ); 3365 end if; 3366 3367 Iter_Type := Etype (Name (I_Spec)); 3368 3369 -- The "of" case uses an internally generated cursor whose type 3370 -- is found in the container package. The domain of iteration 3371 -- is expanded into a call to the default Iterator function, but 3372 -- this expansion does not take place in quantified expressions 3373 -- that are analyzed with expansion disabled, and in that case the 3374 -- type of the iterator must be obtained from the aspect. 3375 3376 if Of_Present (I_Spec) then 3377 declare 3378 Default_Iter : constant Entity_Id := 3379 Entity 3380 (Find_Aspect 3381 (Etype (Container), 3382 Aspect_Default_Iterator)); 3383 3384 Container_Arg : Node_Id; 3385 Ent : Entity_Id; 3386 3387 begin 3388 Cursor := Make_Temporary (Loc, 'I'); 3389 3390 -- For an container element iterator, the iterator type 3391 -- is obtained from the corresponding aspect, whose return 3392 -- type is descended from the corresponding interface type 3393 -- in some instance of Ada.Iterator_Interfaces. The actuals 3394 -- of that instantiation are Cursor and Has_Element. 3395 3396 Iter_Type := Etype (Default_Iter); 3397 3398 -- The iterator type, which is a class_wide type, may itself 3399 -- be derived locally, so the desired instantiation is the 3400 -- scope of the root type of the iterator type. 3401 3402 Pack := Scope (Root_Type (Etype (Iter_Type))); 3403 3404 -- Rewrite domain of iteration as a call to the default 3405 -- iterator for the container type. If the container is 3406 -- a derived type and the aspect is inherited, convert 3407 -- container to parent type. The Cursor type is also 3408 -- inherited from the scope of the parent. 3409 3410 if Base_Type (Etype (Container)) = 3411 Base_Type (Etype (First_Formal (Default_Iter))) 3412 then 3413 Container_Arg := New_Copy_Tree (Container); 3414 3415 else 3416 Container_Arg := 3417 Make_Type_Conversion (Loc, 3418 Subtype_Mark => 3419 New_Occurrence_Of 3420 (Etype (First_Formal (Default_Iter)), Loc), 3421 Expression => New_Copy_Tree (Container)); 3422 end if; 3423 3424 Rewrite (Name (I_Spec), 3425 Make_Function_Call (Loc, 3426 Name => New_Occurrence_Of (Default_Iter, Loc), 3427 Parameter_Associations => 3428 New_List (Container_Arg))); 3429 Analyze_And_Resolve (Name (I_Spec)); 3430 3431 -- Find cursor type in proper iterator package, which is an 3432 -- instantiation of Iterator_Interfaces. 3433 3434 Ent := First_Entity (Pack); 3435 while Present (Ent) loop 3436 if Chars (Ent) = Name_Cursor then 3437 Set_Etype (Cursor, Etype (Ent)); 3438 exit; 3439 end if; 3440 Next_Entity (Ent); 3441 end loop; 3442 3443 -- Generate: 3444 -- Id : Element_Type renames Container (Cursor); 3445 -- This assumes that the container type has an indexing 3446 -- operation with Cursor. The check that this operation 3447 -- exists is performed in Check_Container_Indexing. 3448 3449 Decl := 3450 Make_Object_Renaming_Declaration (Loc, 3451 Defining_Identifier => Id, 3452 Subtype_Mark => 3453 New_Reference_To (Element_Type, Loc), 3454 Name => 3455 Make_Indexed_Component (Loc, 3456 Prefix => Relocate_Node (Container_Arg), 3457 Expressions => 3458 New_List (New_Occurrence_Of (Cursor, Loc)))); 3459 3460 -- The defining identifier in the iterator is user-visible 3461 -- and must be visible in the debugger. 3462 3463 Set_Debug_Info_Needed (Id); 3464 3465 -- If the container holds controlled objects, wrap the loop 3466 -- statements and element renaming declaration with a block. 3467 -- This ensures that the result of Element (Cusor) is 3468 -- cleaned up after each iteration of the loop. 3469 3470 if Needs_Finalization (Element_Type) then 3471 3472 -- Generate: 3473 -- declare 3474 -- Id : Element_Type := Element (curosr); 3475 -- begin 3476 -- <original loop statements> 3477 -- end; 3478 3479 Stats := New_List ( 3480 Make_Block_Statement (Loc, 3481 Declarations => New_List (Decl), 3482 Handled_Statement_Sequence => 3483 Make_Handled_Sequence_Of_Statements (Loc, 3484 Statements => Stats))); 3485 3486 -- Elements do not need finalization 3487 3488 else 3489 Prepend_To (Stats, Decl); 3490 end if; 3491 end; 3492 3493 -- X in Iterate (S) : type of iterator is type of explicitly 3494 -- given Iterate function, and the loop variable is the cursor. 3495 -- It will be assigned in the loop and must be a variable. 3496 3497 else 3498 Cursor := Id; 3499 Set_Ekind (Cursor, E_Variable); 3500 end if; 3501 3502 Iterator := Make_Temporary (Loc, 'I'); 3503 3504 -- Determine the advancement and initialization steps for the 3505 -- cursor. 3506 3507 -- Analysis of the expanded loop will verify that the container 3508 -- has a reverse iterator. 3509 3510 if Reverse_Present (I_Spec) then 3511 Name_Init := Name_Last; 3512 Name_Step := Name_Previous; 3513 3514 else 3515 Name_Init := Name_First; 3516 Name_Step := Name_Next; 3517 end if; 3518 3519 -- For both iterator forms, add a call to the step operation to 3520 -- advance the cursor. Generate: 3521 3522 -- Cursor := Iterator.Next (Cursor); 3523 3524 -- or else 3525 3526 -- Cursor := Next (Cursor); 3527 3528 declare 3529 Rhs : Node_Id; 3530 3531 begin 3532 Rhs := 3533 Make_Function_Call (Loc, 3534 Name => 3535 Make_Selected_Component (Loc, 3536 Prefix => New_Reference_To (Iterator, Loc), 3537 Selector_Name => Make_Identifier (Loc, Name_Step)), 3538 Parameter_Associations => New_List ( 3539 New_Reference_To (Cursor, Loc))); 3540 3541 Append_To (Stats, 3542 Make_Assignment_Statement (Loc, 3543 Name => New_Occurrence_Of (Cursor, Loc), 3544 Expression => Rhs)); 3545 end; 3546 3547 -- Generate: 3548 -- while Iterator.Has_Element loop 3549 -- <Stats> 3550 -- end loop; 3551 3552 -- Has_Element is the second actual in the iterator package 3553 3554 New_Loop := 3555 Make_Loop_Statement (Loc, 3556 Iteration_Scheme => 3557 Make_Iteration_Scheme (Loc, 3558 Condition => 3559 Make_Function_Call (Loc, 3560 Name => 3561 New_Occurrence_Of ( 3562 Next_Entity (First_Entity (Pack)), Loc), 3563 Parameter_Associations => 3564 New_List (New_Reference_To (Cursor, Loc)))), 3565 3566 Statements => Stats, 3567 End_Label => Empty); 3568 3569 -- If present, preserve identifier of loop, which can be used in 3570 -- an exit statement in the body. 3571 3572 if Present (Identifier (N)) then 3573 Set_Identifier (New_Loop, Relocate_Node (Identifier (N))); 3574 end if; 3575 3576 -- Create the declarations for Iterator and cursor and insert them 3577 -- before the source loop. Given that the domain of iteration is 3578 -- already an entity, the iterator is just a renaming of that 3579 -- entity. Possible optimization ??? 3580 -- Generate: 3581 3582 -- I : Iterator_Type renames Container; 3583 -- C : Cursor_Type := Container.[First | Last]; 3584 3585 Insert_Action (N, 3586 Make_Object_Renaming_Declaration (Loc, 3587 Defining_Identifier => Iterator, 3588 Subtype_Mark => New_Occurrence_Of (Iter_Type, Loc), 3589 Name => Relocate_Node (Name (I_Spec)))); 3590 3591 -- Create declaration for cursor 3592 3593 declare 3594 Decl : Node_Id; 3595 3596 begin 3597 Decl := 3598 Make_Object_Declaration (Loc, 3599 Defining_Identifier => Cursor, 3600 Object_Definition => 3601 New_Occurrence_Of (Etype (Cursor), Loc), 3602 Expression => 3603 Make_Selected_Component (Loc, 3604 Prefix => New_Reference_To (Iterator, Loc), 3605 Selector_Name => 3606 Make_Identifier (Loc, Name_Init))); 3607 3608 -- The cursor is only modified in expanded code, so it appears 3609 -- as unassigned to the warning machinery. We must suppress 3610 -- this spurious warning explicitly. 3611 3612 Set_Warnings_Off (Cursor); 3613 Set_Assignment_OK (Decl); 3614 3615 Insert_Action (N, Decl); 3616 end; 3617 3618 -- If the range of iteration is given by a function call that 3619 -- returns a container, the finalization actions have been saved 3620 -- in the Condition_Actions of the iterator. Insert them now at 3621 -- the head of the loop. 3622 3623 if Present (Condition_Actions (Isc)) then 3624 Insert_List_Before (N, Condition_Actions (Isc)); 3625 end if; 3626 end; 3627 3628 Rewrite (N, New_Loop); 3629 Analyze (N); 3630 end Expand_Iterator_Loop; 3631 3632 ------------------------------------- 3633 -- Expand_Iterator_Loop_Over_Array -- 3634 ------------------------------------- 3635 3636 procedure Expand_Iterator_Loop_Over_Array (N : Node_Id) is 3637 Isc : constant Node_Id := Iteration_Scheme (N); 3638 I_Spec : constant Node_Id := Iterator_Specification (Isc); 3639 Array_Node : constant Node_Id := Name (I_Spec); 3640 Array_Typ : constant Entity_Id := Base_Type (Etype (Array_Node)); 3641 Array_Dim : constant Pos := Number_Dimensions (Array_Typ); 3642 Id : constant Entity_Id := Defining_Identifier (I_Spec); 3643 Loc : constant Source_Ptr := Sloc (N); 3644 Stats : constant List_Id := Statements (N); 3645 Core_Loop : Node_Id; 3646 Ind_Comp : Node_Id; 3647 Iterator : Entity_Id; 3648 3649 -- Start of processing for Expand_Iterator_Loop_Over_Array 3650 3651 begin 3652 -- for Element of Array loop 3653 3654 -- This case requires an internally generated cursor to iterate over 3655 -- the array. 3656 3657 if Of_Present (I_Spec) then 3658 Iterator := Make_Temporary (Loc, 'C'); 3659 3660 -- Generate: 3661 -- Element : Component_Type renames Array (Iterator); 3662 3663 Ind_Comp := 3664 Make_Indexed_Component (Loc, 3665 Prefix => Relocate_Node (Array_Node), 3666 Expressions => New_List (New_Reference_To (Iterator, Loc))); 3667 3668 Prepend_To (Stats, 3669 Make_Object_Renaming_Declaration (Loc, 3670 Defining_Identifier => Id, 3671 Subtype_Mark => 3672 New_Reference_To (Component_Type (Array_Typ), Loc), 3673 Name => Ind_Comp)); 3674 3675 -- Mark the loop variable as needing debug info, so that expansion 3676 -- of the renaming will result in Materialize_Entity getting set via 3677 -- Debug_Renaming_Declaration. (This setting is needed here because 3678 -- the setting in Freeze_Entity comes after the expansion, which is 3679 -- too late. ???) 3680 3681 Set_Debug_Info_Needed (Id); 3682 3683 -- for Index in Array loop 3684 3685 -- This case utilizes the already given iterator name 3686 3687 else 3688 Iterator := Id; 3689 end if; 3690 3691 -- Generate: 3692 3693 -- for Iterator in [reverse] Array'Range (Array_Dim) loop 3694 -- Element : Component_Type renames Array (Iterator); 3695 -- <original loop statements> 3696 -- end loop; 3697 3698 Core_Loop := 3699 Make_Loop_Statement (Loc, 3700 Iteration_Scheme => 3701 Make_Iteration_Scheme (Loc, 3702 Loop_Parameter_Specification => 3703 Make_Loop_Parameter_Specification (Loc, 3704 Defining_Identifier => Iterator, 3705 Discrete_Subtype_Definition => 3706 Make_Attribute_Reference (Loc, 3707 Prefix => Relocate_Node (Array_Node), 3708 Attribute_Name => Name_Range, 3709 Expressions => New_List ( 3710 Make_Integer_Literal (Loc, Array_Dim))), 3711 Reverse_Present => Reverse_Present (I_Spec))), 3712 Statements => Stats, 3713 End_Label => Empty); 3714 3715 -- Processing for multidimensional array 3716 3717 if Array_Dim > 1 then 3718 for Dim in 1 .. Array_Dim - 1 loop 3719 Iterator := Make_Temporary (Loc, 'C'); 3720 3721 -- Generate the dimension loops starting from the innermost one 3722 3723 -- for Iterator in [reverse] Array'Range (Array_Dim - Dim) loop 3724 -- <core loop> 3725 -- end loop; 3726 3727 Core_Loop := 3728 Make_Loop_Statement (Loc, 3729 Iteration_Scheme => 3730 Make_Iteration_Scheme (Loc, 3731 Loop_Parameter_Specification => 3732 Make_Loop_Parameter_Specification (Loc, 3733 Defining_Identifier => Iterator, 3734 Discrete_Subtype_Definition => 3735 Make_Attribute_Reference (Loc, 3736 Prefix => Relocate_Node (Array_Node), 3737 Attribute_Name => Name_Range, 3738 Expressions => New_List ( 3739 Make_Integer_Literal (Loc, Array_Dim - Dim))), 3740 Reverse_Present => Reverse_Present (I_Spec))), 3741 Statements => New_List (Core_Loop), 3742 End_Label => Empty); 3743 3744 -- Update the previously created object renaming declaration with 3745 -- the new iterator. 3746 3747 Prepend_To (Expressions (Ind_Comp), 3748 New_Reference_To (Iterator, Loc)); 3749 end loop; 3750 end if; 3751 3752 -- If original loop has a source name, preserve it so it can be 3753 -- recognized by an exit statement in the body of the rewritten loop. 3754 -- This only concerns source names: the generated name of an anonymous 3755 -- loop will be create again during the subsequent analysis below. 3756 3757 if Present (Identifier (N)) 3758 and then Comes_From_Source (Identifier (N)) 3759 then 3760 Set_Identifier (Core_Loop, Relocate_Node (Identifier (N))); 3761 end if; 3762 3763 Rewrite (N, Core_Loop); 3764 Analyze (N); 3765 end Expand_Iterator_Loop_Over_Array; 3766 3767 ----------------------------- 3768 -- Expand_N_Loop_Statement -- 3769 ----------------------------- 3770 3771 -- 1. Remove null loop entirely 3772 -- 2. Deal with while condition for C/Fortran boolean 3773 -- 3. Deal with loops with a non-standard enumeration type range 3774 -- 4. Deal with while loops where Condition_Actions is set 3775 -- 5. Deal with loops over predicated subtypes 3776 -- 6. Deal with loops with iterators over arrays and containers 3777 -- 7. Insert polling call if required 3778 3779 procedure Expand_N_Loop_Statement (N : Node_Id) is 3780 Loc : constant Source_Ptr := Sloc (N); 3781 Isc : constant Node_Id := Iteration_Scheme (N); 3782 3783 begin 3784 -- Delete null loop 3785 3786 if Is_Null_Loop (N) then 3787 Rewrite (N, Make_Null_Statement (Loc)); 3788 return; 3789 end if; 3790 3791 Process_Statements_For_Controlled_Objects (N); 3792 3793 -- Deal with condition for C/Fortran Boolean 3794 3795 if Present (Isc) then 3796 Adjust_Condition (Condition (Isc)); 3797 end if; 3798 3799 -- Generate polling call 3800 3801 if Is_Non_Empty_List (Statements (N)) then 3802 Generate_Poll_Call (First (Statements (N))); 3803 end if; 3804 3805 -- Nothing more to do for plain loop with no iteration scheme 3806 3807 if No (Isc) then 3808 null; 3809 3810 -- Case of for loop (Loop_Parameter_Specification present) 3811 3812 -- Note: we do not have to worry about validity checking of the for loop 3813 -- range bounds here, since they were frozen with constant declarations 3814 -- and it is during that process that the validity checking is done. 3815 3816 elsif Present (Loop_Parameter_Specification (Isc)) then 3817 declare 3818 LPS : constant Node_Id := Loop_Parameter_Specification (Isc); 3819 Loop_Id : constant Entity_Id := Defining_Identifier (LPS); 3820 Ltype : constant Entity_Id := Etype (Loop_Id); 3821 Btype : constant Entity_Id := Base_Type (Ltype); 3822 Expr : Node_Id; 3823 Decls : List_Id; 3824 New_Id : Entity_Id; 3825 3826 begin 3827 -- Deal with loop over predicates 3828 3829 if Is_Discrete_Type (Ltype) 3830 and then Present (Predicate_Function (Ltype)) 3831 then 3832 Expand_Predicated_Loop (N); 3833 3834 -- Handle the case where we have a for loop with the range type 3835 -- being an enumeration type with non-standard representation. 3836 -- In this case we expand: 3837 3838 -- for x in [reverse] a .. b loop 3839 -- ... 3840 -- end loop; 3841 3842 -- to 3843 3844 -- for xP in [reverse] integer 3845 -- range etype'Pos (a) .. etype'Pos (b) 3846 -- loop 3847 -- declare 3848 -- x : constant etype := Pos_To_Rep (xP); 3849 -- begin 3850 -- ... 3851 -- end; 3852 -- end loop; 3853 3854 elsif Is_Enumeration_Type (Btype) 3855 and then Present (Enum_Pos_To_Rep (Btype)) 3856 then 3857 New_Id := 3858 Make_Defining_Identifier (Loc, 3859 Chars => New_External_Name (Chars (Loop_Id), 'P')); 3860 3861 -- If the type has a contiguous representation, successive 3862 -- values can be generated as offsets from the first literal. 3863 3864 if Has_Contiguous_Rep (Btype) then 3865 Expr := 3866 Unchecked_Convert_To (Btype, 3867 Make_Op_Add (Loc, 3868 Left_Opnd => 3869 Make_Integer_Literal (Loc, 3870 Enumeration_Rep (First_Literal (Btype))), 3871 Right_Opnd => New_Reference_To (New_Id, Loc))); 3872 else 3873 -- Use the constructed array Enum_Pos_To_Rep 3874 3875 Expr := 3876 Make_Indexed_Component (Loc, 3877 Prefix => 3878 New_Reference_To (Enum_Pos_To_Rep (Btype), Loc), 3879 Expressions => 3880 New_List (New_Reference_To (New_Id, Loc))); 3881 end if; 3882 3883 -- Build declaration for loop identifier 3884 3885 Decls := 3886 New_List ( 3887 Make_Object_Declaration (Loc, 3888 Defining_Identifier => Loop_Id, 3889 Constant_Present => True, 3890 Object_Definition => New_Reference_To (Ltype, Loc), 3891 Expression => Expr)); 3892 3893 Rewrite (N, 3894 Make_Loop_Statement (Loc, 3895 Identifier => Identifier (N), 3896 3897 Iteration_Scheme => 3898 Make_Iteration_Scheme (Loc, 3899 Loop_Parameter_Specification => 3900 Make_Loop_Parameter_Specification (Loc, 3901 Defining_Identifier => New_Id, 3902 Reverse_Present => Reverse_Present (LPS), 3903 3904 Discrete_Subtype_Definition => 3905 Make_Subtype_Indication (Loc, 3906 3907 Subtype_Mark => 3908 New_Reference_To (Standard_Natural, Loc), 3909 3910 Constraint => 3911 Make_Range_Constraint (Loc, 3912 Range_Expression => 3913 Make_Range (Loc, 3914 3915 Low_Bound => 3916 Make_Attribute_Reference (Loc, 3917 Prefix => 3918 New_Reference_To (Btype, Loc), 3919 3920 Attribute_Name => Name_Pos, 3921 3922 Expressions => New_List ( 3923 Relocate_Node 3924 (Type_Low_Bound (Ltype)))), 3925 3926 High_Bound => 3927 Make_Attribute_Reference (Loc, 3928 Prefix => 3929 New_Reference_To (Btype, Loc), 3930 3931 Attribute_Name => Name_Pos, 3932 3933 Expressions => New_List ( 3934 Relocate_Node 3935 (Type_High_Bound 3936 (Ltype))))))))), 3937 3938 Statements => New_List ( 3939 Make_Block_Statement (Loc, 3940 Declarations => Decls, 3941 Handled_Statement_Sequence => 3942 Make_Handled_Sequence_Of_Statements (Loc, 3943 Statements => Statements (N)))), 3944 3945 End_Label => End_Label (N))); 3946 3947 -- The loop parameter's entity must be removed from the loop 3948 -- scope's entity list and rendered invisible, since it will 3949 -- now be located in the new block scope. Any other entities 3950 -- already associated with the loop scope, such as the loop 3951 -- parameter's subtype, will remain there. 3952 3953 -- In an element loop, the loop will contain a declaration for 3954 -- a cursor variable; otherwise the loop id is the first entity 3955 -- in the scope constructed for the loop. 3956 3957 if Comes_From_Source (Loop_Id) then 3958 pragma Assert (First_Entity (Scope (Loop_Id)) = Loop_Id); 3959 null; 3960 end if; 3961 3962 Set_First_Entity (Scope (Loop_Id), Next_Entity (Loop_Id)); 3963 Remove_Homonym (Loop_Id); 3964 3965 if Last_Entity (Scope (Loop_Id)) = Loop_Id then 3966 Set_Last_Entity (Scope (Loop_Id), Empty); 3967 end if; 3968 3969 Analyze (N); 3970 3971 -- Nothing to do with other cases of for loops 3972 3973 else 3974 null; 3975 end if; 3976 end; 3977 3978 -- Second case, if we have a while loop with Condition_Actions set, then 3979 -- we change it into a plain loop: 3980 3981 -- while C loop 3982 -- ... 3983 -- end loop; 3984 3985 -- changed to: 3986 3987 -- loop 3988 -- <<condition actions>> 3989 -- exit when not C; 3990 -- ... 3991 -- end loop 3992 3993 elsif Present (Isc) 3994 and then Present (Condition_Actions (Isc)) 3995 and then Present (Condition (Isc)) 3996 then 3997 declare 3998 ES : Node_Id; 3999 4000 begin 4001 ES := 4002 Make_Exit_Statement (Sloc (Condition (Isc)), 4003 Condition => 4004 Make_Op_Not (Sloc (Condition (Isc)), 4005 Right_Opnd => Condition (Isc))); 4006 4007 Prepend (ES, Statements (N)); 4008 Insert_List_Before (ES, Condition_Actions (Isc)); 4009 4010 -- This is not an implicit loop, since it is generated in response 4011 -- to the loop statement being processed. If this is itself 4012 -- implicit, the restriction has already been checked. If not, 4013 -- it is an explicit loop. 4014 4015 Rewrite (N, 4016 Make_Loop_Statement (Sloc (N), 4017 Identifier => Identifier (N), 4018 Statements => Statements (N), 4019 End_Label => End_Label (N))); 4020 4021 Analyze (N); 4022 end; 4023 4024 -- Here to deal with iterator case 4025 4026 elsif Present (Isc) 4027 and then Present (Iterator_Specification (Isc)) 4028 then 4029 Expand_Iterator_Loop (N); 4030 end if; 4031 4032 -- If the loop is subject to at least one Loop_Entry attribute, it 4033 -- requires additional processing. 4034 4035 if Nkind (N) = N_Loop_Statement then 4036 Expand_Loop_Entry_Attributes (N); 4037 end if; 4038 end Expand_N_Loop_Statement; 4039 4040 ---------------------------- 4041 -- Expand_Predicated_Loop -- 4042 ---------------------------- 4043 4044 -- Note: the expander can handle generation of loops over predicated 4045 -- subtypes for both the dynamic and static cases. Depending on what 4046 -- we decide is allowed in Ada 2012 mode and/or extensions allowed 4047 -- mode, the semantic analyzer may disallow one or both forms. 4048 4049 procedure Expand_Predicated_Loop (N : Node_Id) is 4050 Loc : constant Source_Ptr := Sloc (N); 4051 Isc : constant Node_Id := Iteration_Scheme (N); 4052 LPS : constant Node_Id := Loop_Parameter_Specification (Isc); 4053 Loop_Id : constant Entity_Id := Defining_Identifier (LPS); 4054 Ltype : constant Entity_Id := Etype (Loop_Id); 4055 Stat : constant List_Id := Static_Predicate (Ltype); 4056 Stmts : constant List_Id := Statements (N); 4057 4058 begin 4059 -- Case of iteration over non-static predicate, should not be possible 4060 -- since this is not allowed by the semantics and should have been 4061 -- caught during analysis of the loop statement. 4062 4063 if No (Stat) then 4064 raise Program_Error; 4065 4066 -- If the predicate list is empty, that corresponds to a predicate of 4067 -- False, in which case the loop won't run at all, and we rewrite the 4068 -- entire loop as a null statement. 4069 4070 elsif Is_Empty_List (Stat) then 4071 Rewrite (N, Make_Null_Statement (Loc)); 4072 Analyze (N); 4073 4074 -- For expansion over a static predicate we generate the following 4075 4076 -- declare 4077 -- J : Ltype := min-val; 4078 -- begin 4079 -- loop 4080 -- body 4081 -- case J is 4082 -- when endpoint => J := startpoint; 4083 -- when endpoint => J := startpoint; 4084 -- ... 4085 -- when max-val => exit; 4086 -- when others => J := Lval'Succ (J); 4087 -- end case; 4088 -- end loop; 4089 -- end; 4090 4091 -- To make this a little clearer, let's take a specific example: 4092 4093 -- type Int is range 1 .. 10; 4094 -- subtype L is Int with 4095 -- predicate => L in 3 | 10 | 5 .. 7; 4096 -- ... 4097 -- for L in StaticP loop 4098 -- Put_Line ("static:" & J'Img); 4099 -- end loop; 4100 4101 -- In this case, the loop is transformed into 4102 4103 -- begin 4104 -- J : L := 3; 4105 -- loop 4106 -- body 4107 -- case J is 4108 -- when 3 => J := 5; 4109 -- when 7 => J := 10; 4110 -- when 10 => exit; 4111 -- when others => J := L'Succ (J); 4112 -- end case; 4113 -- end loop; 4114 -- end; 4115 4116 else 4117 Static_Predicate : declare 4118 S : Node_Id; 4119 D : Node_Id; 4120 P : Node_Id; 4121 Alts : List_Id; 4122 Cstm : Node_Id; 4123 4124 function Lo_Val (N : Node_Id) return Node_Id; 4125 -- Given static expression or static range, returns an identifier 4126 -- whose value is the low bound of the expression value or range. 4127 4128 function Hi_Val (N : Node_Id) return Node_Id; 4129 -- Given static expression or static range, returns an identifier 4130 -- whose value is the high bound of the expression value or range. 4131 4132 ------------ 4133 -- Hi_Val -- 4134 ------------ 4135 4136 function Hi_Val (N : Node_Id) return Node_Id is 4137 begin 4138 if Is_Static_Expression (N) then 4139 return New_Copy (N); 4140 else 4141 pragma Assert (Nkind (N) = N_Range); 4142 return New_Copy (High_Bound (N)); 4143 end if; 4144 end Hi_Val; 4145 4146 ------------ 4147 -- Lo_Val -- 4148 ------------ 4149 4150 function Lo_Val (N : Node_Id) return Node_Id is 4151 begin 4152 if Is_Static_Expression (N) then 4153 return New_Copy (N); 4154 else 4155 pragma Assert (Nkind (N) = N_Range); 4156 return New_Copy (Low_Bound (N)); 4157 end if; 4158 end Lo_Val; 4159 4160 -- Start of processing for Static_Predicate 4161 4162 begin 4163 -- Convert loop identifier to normal variable and reanalyze it so 4164 -- that this conversion works. We have to use the same defining 4165 -- identifier, since there may be references in the loop body. 4166 4167 Set_Analyzed (Loop_Id, False); 4168 Set_Ekind (Loop_Id, E_Variable); 4169 4170 -- In most loops the loop variable is assigned in various 4171 -- alternatives in the body. However, in the rare case when 4172 -- the range specifies a single element, the loop variable 4173 -- may trigger a spurious warning that is could be constant. 4174 -- This warning might as well be suppressed. 4175 4176 Set_Warnings_Off (Loop_Id); 4177 4178 -- Loop to create branches of case statement 4179 4180 Alts := New_List; 4181 P := First (Stat); 4182 while Present (P) loop 4183 if No (Next (P)) then 4184 S := Make_Exit_Statement (Loc); 4185 else 4186 S := 4187 Make_Assignment_Statement (Loc, 4188 Name => New_Occurrence_Of (Loop_Id, Loc), 4189 Expression => Lo_Val (Next (P))); 4190 Set_Suppress_Assignment_Checks (S); 4191 end if; 4192 4193 Append_To (Alts, 4194 Make_Case_Statement_Alternative (Loc, 4195 Statements => New_List (S), 4196 Discrete_Choices => New_List (Hi_Val (P)))); 4197 4198 Next (P); 4199 end loop; 4200 4201 -- Add others choice 4202 4203 S := 4204 Make_Assignment_Statement (Loc, 4205 Name => New_Occurrence_Of (Loop_Id, Loc), 4206 Expression => 4207 Make_Attribute_Reference (Loc, 4208 Prefix => New_Occurrence_Of (Ltype, Loc), 4209 Attribute_Name => Name_Succ, 4210 Expressions => New_List ( 4211 New_Occurrence_Of (Loop_Id, Loc)))); 4212 Set_Suppress_Assignment_Checks (S); 4213 4214 Append_To (Alts, 4215 Make_Case_Statement_Alternative (Loc, 4216 Discrete_Choices => New_List (Make_Others_Choice (Loc)), 4217 Statements => New_List (S))); 4218 4219 -- Construct case statement and append to body statements 4220 4221 Cstm := 4222 Make_Case_Statement (Loc, 4223 Expression => New_Occurrence_Of (Loop_Id, Loc), 4224 Alternatives => Alts); 4225 Append_To (Stmts, Cstm); 4226 4227 -- Rewrite the loop 4228 4229 D := 4230 Make_Object_Declaration (Loc, 4231 Defining_Identifier => Loop_Id, 4232 Object_Definition => New_Occurrence_Of (Ltype, Loc), 4233 Expression => Lo_Val (First (Stat))); 4234 Set_Suppress_Assignment_Checks (D); 4235 4236 Rewrite (N, 4237 Make_Block_Statement (Loc, 4238 Declarations => New_List (D), 4239 Handled_Statement_Sequence => 4240 Make_Handled_Sequence_Of_Statements (Loc, 4241 Statements => New_List ( 4242 Make_Loop_Statement (Loc, 4243 Statements => Stmts, 4244 End_Label => Empty))))); 4245 4246 Analyze (N); 4247 end Static_Predicate; 4248 end if; 4249 end Expand_Predicated_Loop; 4250 4251 ------------------------------ 4252 -- Make_Tag_Ctrl_Assignment -- 4253 ------------------------------ 4254 4255 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is 4256 Asn : constant Node_Id := Relocate_Node (N); 4257 L : constant Node_Id := Name (N); 4258 Loc : constant Source_Ptr := Sloc (N); 4259 Res : constant List_Id := New_List; 4260 T : constant Entity_Id := Underlying_Type (Etype (L)); 4261 4262 Comp_Asn : constant Boolean := Is_Fully_Repped_Tagged_Type (T); 4263 Ctrl_Act : constant Boolean := Needs_Finalization (T) 4264 and then not No_Ctrl_Actions (N); 4265 Save_Tag : constant Boolean := Is_Tagged_Type (T) 4266 and then not Comp_Asn 4267 and then not No_Ctrl_Actions (N) 4268 and then Tagged_Type_Expansion; 4269 -- Tags are not saved and restored when VM_Target because VM tags are 4270 -- represented implicitly in objects. 4271 4272 Next_Id : Entity_Id; 4273 Prev_Id : Entity_Id; 4274 Tag_Id : Entity_Id; 4275 4276 begin 4277 -- Finalize the target of the assignment when controlled 4278 4279 -- We have two exceptions here: 4280 4281 -- 1. If we are in an init proc since it is an initialization more 4282 -- than an assignment. 4283 4284 -- 2. If the left-hand side is a temporary that was not initialized 4285 -- (or the parent part of a temporary since it is the case in 4286 -- extension aggregates). Such a temporary does not come from 4287 -- source. We must examine the original node for the prefix, because 4288 -- it may be a component of an entry formal, in which case it has 4289 -- been rewritten and does not appear to come from source either. 4290 4291 -- Case of init proc 4292 4293 if not Ctrl_Act then 4294 null; 4295 4296 -- The left hand side is an uninitialized temporary object 4297 4298 elsif Nkind (L) = N_Type_Conversion 4299 and then Is_Entity_Name (Expression (L)) 4300 and then Nkind (Parent (Entity (Expression (L)))) = 4301 N_Object_Declaration 4302 and then No_Initialization (Parent (Entity (Expression (L)))) 4303 then 4304 null; 4305 4306 else 4307 Append_To (Res, 4308 Make_Final_Call 4309 (Obj_Ref => Duplicate_Subexpr_No_Checks (L), 4310 Typ => Etype (L))); 4311 end if; 4312 4313 -- Save the Tag in a local variable Tag_Id 4314 4315 if Save_Tag then 4316 Tag_Id := Make_Temporary (Loc, 'A'); 4317 4318 Append_To (Res, 4319 Make_Object_Declaration (Loc, 4320 Defining_Identifier => Tag_Id, 4321 Object_Definition => New_Reference_To (RTE (RE_Tag), Loc), 4322 Expression => 4323 Make_Selected_Component (Loc, 4324 Prefix => Duplicate_Subexpr_No_Checks (L), 4325 Selector_Name => 4326 New_Reference_To (First_Tag_Component (T), Loc)))); 4327 4328 -- Otherwise Tag_Id is not used 4329 4330 else 4331 Tag_Id := Empty; 4332 end if; 4333 4334 -- Save the Prev and Next fields on .NET/JVM. This is not needed on non 4335 -- VM targets since the fields are not part of the object. 4336 4337 if VM_Target /= No_VM 4338 and then Is_Controlled (T) 4339 then 4340 Prev_Id := Make_Temporary (Loc, 'P'); 4341 Next_Id := Make_Temporary (Loc, 'N'); 4342 4343 -- Generate: 4344 -- Pnn : Root_Controlled_Ptr := Root_Controlled (L).Prev; 4345 4346 Append_To (Res, 4347 Make_Object_Declaration (Loc, 4348 Defining_Identifier => Prev_Id, 4349 Object_Definition => 4350 New_Reference_To (RTE (RE_Root_Controlled_Ptr), Loc), 4351 Expression => 4352 Make_Selected_Component (Loc, 4353 Prefix => 4354 Unchecked_Convert_To 4355 (RTE (RE_Root_Controlled), New_Copy_Tree (L)), 4356 Selector_Name => 4357 Make_Identifier (Loc, Name_Prev)))); 4358 4359 -- Generate: 4360 -- Nnn : Root_Controlled_Ptr := Root_Controlled (L).Next; 4361 4362 Append_To (Res, 4363 Make_Object_Declaration (Loc, 4364 Defining_Identifier => Next_Id, 4365 Object_Definition => 4366 New_Reference_To (RTE (RE_Root_Controlled_Ptr), Loc), 4367 Expression => 4368 Make_Selected_Component (Loc, 4369 Prefix => 4370 Unchecked_Convert_To 4371 (RTE (RE_Root_Controlled), New_Copy_Tree (L)), 4372 Selector_Name => 4373 Make_Identifier (Loc, Name_Next)))); 4374 end if; 4375 4376 -- If the tagged type has a full rep clause, expand the assignment into 4377 -- component-wise assignments. Mark the node as unanalyzed in order to 4378 -- generate the proper code and propagate this scenario by setting a 4379 -- flag to avoid infinite recursion. 4380 4381 if Comp_Asn then 4382 Set_Analyzed (Asn, False); 4383 Set_Componentwise_Assignment (Asn, True); 4384 end if; 4385 4386 Append_To (Res, Asn); 4387 4388 -- Restore the tag 4389 4390 if Save_Tag then 4391 Append_To (Res, 4392 Make_Assignment_Statement (Loc, 4393 Name => 4394 Make_Selected_Component (Loc, 4395 Prefix => Duplicate_Subexpr_No_Checks (L), 4396 Selector_Name => 4397 New_Reference_To (First_Tag_Component (T), Loc)), 4398 Expression => New_Reference_To (Tag_Id, Loc))); 4399 end if; 4400 4401 -- Restore the Prev and Next fields on .NET/JVM 4402 4403 if VM_Target /= No_VM 4404 and then Is_Controlled (T) 4405 then 4406 -- Generate: 4407 -- Root_Controlled (L).Prev := Prev_Id; 4408 4409 Append_To (Res, 4410 Make_Assignment_Statement (Loc, 4411 Name => 4412 Make_Selected_Component (Loc, 4413 Prefix => 4414 Unchecked_Convert_To 4415 (RTE (RE_Root_Controlled), New_Copy_Tree (L)), 4416 Selector_Name => 4417 Make_Identifier (Loc, Name_Prev)), 4418 Expression => New_Reference_To (Prev_Id, Loc))); 4419 4420 -- Generate: 4421 -- Root_Controlled (L).Next := Next_Id; 4422 4423 Append_To (Res, 4424 Make_Assignment_Statement (Loc, 4425 Name => 4426 Make_Selected_Component (Loc, 4427 Prefix => 4428 Unchecked_Convert_To 4429 (RTE (RE_Root_Controlled), New_Copy_Tree (L)), 4430 Selector_Name => Make_Identifier (Loc, Name_Next)), 4431 Expression => New_Reference_To (Next_Id, Loc))); 4432 end if; 4433 4434 -- Adjust the target after the assignment when controlled (not in the 4435 -- init proc since it is an initialization more than an assignment). 4436 4437 if Ctrl_Act then 4438 Append_To (Res, 4439 Make_Adjust_Call 4440 (Obj_Ref => Duplicate_Subexpr_Move_Checks (L), 4441 Typ => Etype (L))); 4442 end if; 4443 4444 return Res; 4445 4446 exception 4447 4448 -- Could use comment here ??? 4449 4450 when RE_Not_Available => 4451 return Empty_List; 4452 end Make_Tag_Ctrl_Assignment; 4453 4454end Exp_Ch5; 4455