1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- E X P _ C H 5 -- 6-- -- 7-- B o d y -- 8-- -- 9-- Copyright (C) 1992-2015, 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 Ghost; use Ghost; 42with Inline; use Inline; 43with Namet; use Namet; 44with Nlists; use Nlists; 45with Nmake; use Nmake; 46with Opt; use Opt; 47with Restrict; use Restrict; 48with Rident; use Rident; 49with Rtsfind; use Rtsfind; 50with Sinfo; use Sinfo; 51with Sem; use Sem; 52with Sem_Aux; use Sem_Aux; 53with Sem_Ch3; use Sem_Ch3; 54with Sem_Ch8; use Sem_Ch8; 55with Sem_Ch13; use Sem_Ch13; 56with Sem_Eval; use Sem_Eval; 57with Sem_Res; use Sem_Res; 58with Sem_Util; use Sem_Util; 59with Snames; use Snames; 60with Stand; use Stand; 61with Stringt; use Stringt; 62with Targparm; use Targparm; 63with Tbuild; use Tbuild; 64with Uintp; use Uintp; 65with Validsw; use Validsw; 66 67package body Exp_Ch5 is 68 69 procedure Build_Formal_Container_Iteration 70 (N : Node_Id; 71 Container : Entity_Id; 72 Cursor : Entity_Id; 73 Init : out Node_Id; 74 Advance : out Node_Id; 75 New_Loop : out Node_Id); 76 -- Utility to create declarations and loop statement for both forms 77 -- of formal container iterators. 78 79 function Change_Of_Representation (N : Node_Id) return Boolean; 80 -- Determine if the right hand side of assignment N is a type conversion 81 -- which requires a change of representation. Called only for the array 82 -- and record cases. 83 84 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id); 85 -- N is an assignment which assigns an array value. This routine process 86 -- the various special cases and checks required for such assignments, 87 -- including change of representation. Rhs is normally simply the right 88 -- hand side of the assignment, except that if the right hand side is a 89 -- type conversion or a qualified expression, then the RHS is the actual 90 -- expression inside any such type conversions or qualifications. 91 92 function Expand_Assign_Array_Loop 93 (N : Node_Id; 94 Larray : Entity_Id; 95 Rarray : Entity_Id; 96 L_Type : Entity_Id; 97 R_Type : Entity_Id; 98 Ndim : Pos; 99 Rev : Boolean) return Node_Id; 100 -- N is an assignment statement which assigns an array value. This routine 101 -- expands the assignment into a loop (or nested loops for the case of a 102 -- multi-dimensional array) to do the assignment component by component. 103 -- Larray and Rarray are the entities of the actual arrays on the left 104 -- hand and right hand sides. L_Type and R_Type are the types of these 105 -- arrays (which may not be the same, due to either sliding, or to a 106 -- change of representation case). Ndim is the number of dimensions and 107 -- the parameter Rev indicates if the loops run normally (Rev = False), 108 -- or reversed (Rev = True). The value returned is the constructed 109 -- loop statement. Auxiliary declarations are inserted before node N 110 -- using the standard Insert_Actions mechanism. 111 112 procedure Expand_Assign_Record (N : Node_Id); 113 -- N is an assignment of an untagged record value. This routine handles 114 -- the case where the assignment must be made component by component, 115 -- either because the target is not byte aligned, or there is a change 116 -- of representation, or when we have a tagged type with a representation 117 -- clause (this last case is required because holes in the tagged type 118 -- might be filled with components from child types). 119 120 procedure Expand_Formal_Container_Loop (N : Node_Id); 121 -- Use the primitives specified in an Iterable aspect to expand a loop 122 -- over a so-called formal container, primarily for SPARK usage. 123 124 procedure Expand_Formal_Container_Element_Loop (N : Node_Id); 125 -- Same, for an iterator of the form " For E of C". In this case the 126 -- iterator provides the name of the element, and the cursor is generated 127 -- internally. 128 129 procedure Expand_Iterator_Loop (N : Node_Id); 130 -- Expand loop over arrays and containers that uses the form "for X of C" 131 -- with an optional subtype mark, or "for Y in C". 132 133 procedure Expand_Iterator_Loop_Over_Container 134 (N : Node_Id; 135 Isc : Node_Id; 136 I_Spec : Node_Id; 137 Container : Node_Id; 138 Container_Typ : Entity_Id); 139 -- Expand loop over containers that uses the form "for X of C" with an 140 -- optional subtype mark, or "for Y in C". Isc is the iteration scheme. 141 -- I_Spec is the iterator specification and Container is either the 142 -- Container (for OF) or the iterator (for IN). 143 144 procedure Expand_Predicated_Loop (N : Node_Id); 145 -- Expand for loop over predicated subtype 146 147 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id; 148 -- Generate the necessary code for controlled and tagged assignment, that 149 -- is to say, finalization of the target before, adjustment of the target 150 -- after and save and restore of the tag and finalization pointers which 151 -- are not 'part of the value' and must not be changed upon assignment. N 152 -- is the original Assignment node. 153 154 -------------------------------------- 155 -- Build_Formal_Container_iteration -- 156 -------------------------------------- 157 158 procedure Build_Formal_Container_Iteration 159 (N : Node_Id; 160 Container : Entity_Id; 161 Cursor : Entity_Id; 162 Init : out Node_Id; 163 Advance : out Node_Id; 164 New_Loop : out Node_Id) 165 is 166 Loc : constant Source_Ptr := Sloc (N); 167 Stats : constant List_Id := Statements (N); 168 Typ : constant Entity_Id := Base_Type (Etype (Container)); 169 First_Op : constant Entity_Id := 170 Get_Iterable_Type_Primitive (Typ, Name_First); 171 Next_Op : constant Entity_Id := 172 Get_Iterable_Type_Primitive (Typ, Name_Next); 173 174 Has_Element_Op : constant Entity_Id := 175 Get_Iterable_Type_Primitive (Typ, Name_Has_Element); 176 begin 177 -- Declaration for Cursor 178 179 Init := 180 Make_Object_Declaration (Loc, 181 Defining_Identifier => Cursor, 182 Object_Definition => New_Occurrence_Of (Etype (First_Op), Loc), 183 Expression => 184 Make_Function_Call (Loc, 185 Name => New_Occurrence_Of (First_Op, Loc), 186 Parameter_Associations => New_List ( 187 New_Occurrence_Of (Container, Loc)))); 188 189 -- Statement that advances cursor in loop 190 191 Advance := 192 Make_Assignment_Statement (Loc, 193 Name => New_Occurrence_Of (Cursor, Loc), 194 Expression => 195 Make_Function_Call (Loc, 196 Name => New_Occurrence_Of (Next_Op, Loc), 197 Parameter_Associations => New_List ( 198 New_Occurrence_Of (Container, Loc), 199 New_Occurrence_Of (Cursor, Loc)))); 200 201 -- Iterator is rewritten as a while_loop 202 203 New_Loop := 204 Make_Loop_Statement (Loc, 205 Iteration_Scheme => 206 Make_Iteration_Scheme (Loc, 207 Condition => 208 Make_Function_Call (Loc, 209 Name => New_Occurrence_Of (Has_Element_Op, Loc), 210 Parameter_Associations => New_List ( 211 New_Occurrence_Of (Container, Loc), 212 New_Occurrence_Of (Cursor, Loc)))), 213 Statements => Stats, 214 End_Label => Empty); 215 end Build_Formal_Container_Iteration; 216 217 ------------------------------ 218 -- Change_Of_Representation -- 219 ------------------------------ 220 221 function Change_Of_Representation (N : Node_Id) return Boolean is 222 Rhs : constant Node_Id := Expression (N); 223 begin 224 return 225 Nkind (Rhs) = N_Type_Conversion 226 and then 227 not Same_Representation (Etype (Rhs), Etype (Expression (Rhs))); 228 end Change_Of_Representation; 229 230 ------------------------- 231 -- Expand_Assign_Array -- 232 ------------------------- 233 234 -- There are two issues here. First, do we let Gigi do a block move, or 235 -- do we expand out into a loop? Second, we need to set the two flags 236 -- Forwards_OK and Backwards_OK which show whether the block move (or 237 -- corresponding loops) can be legitimately done in a forwards (low to 238 -- high) or backwards (high to low) manner. 239 240 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is 241 Loc : constant Source_Ptr := Sloc (N); 242 243 Lhs : constant Node_Id := Name (N); 244 245 Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs); 246 Act_Rhs : Node_Id := Get_Referenced_Object (Rhs); 247 248 L_Type : constant Entity_Id := 249 Underlying_Type (Get_Actual_Subtype (Act_Lhs)); 250 R_Type : Entity_Id := 251 Underlying_Type (Get_Actual_Subtype (Act_Rhs)); 252 253 L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice; 254 R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice; 255 256 Crep : constant Boolean := Change_Of_Representation (N); 257 258 Larray : Node_Id; 259 Rarray : Node_Id; 260 261 Ndim : constant Pos := Number_Dimensions (L_Type); 262 263 Loop_Required : Boolean := False; 264 -- This switch is set to True if the array move must be done using 265 -- an explicit front end generated loop. 266 267 procedure Apply_Dereference (Arg : Node_Id); 268 -- If the argument is an access to an array, and the assignment is 269 -- converted into a procedure call, apply explicit dereference. 270 271 function Has_Address_Clause (Exp : Node_Id) return Boolean; 272 -- Test if Exp is a reference to an array whose declaration has 273 -- an address clause, or it is a slice of such an array. 274 275 function Is_Formal_Array (Exp : Node_Id) return Boolean; 276 -- Test if Exp is a reference to an array which is either a formal 277 -- parameter or a slice of a formal parameter. These are the cases 278 -- where hidden aliasing can occur. 279 280 function Is_Non_Local_Array (Exp : Node_Id) return Boolean; 281 -- Determine if Exp is a reference to an array variable which is other 282 -- than an object defined in the current scope, or a slice of such 283 -- an object. Such objects can be aliased to parameters (unlike local 284 -- array references). 285 286 ----------------------- 287 -- Apply_Dereference -- 288 ----------------------- 289 290 procedure Apply_Dereference (Arg : Node_Id) is 291 Typ : constant Entity_Id := Etype (Arg); 292 begin 293 if Is_Access_Type (Typ) then 294 Rewrite (Arg, Make_Explicit_Dereference (Loc, 295 Prefix => Relocate_Node (Arg))); 296 Analyze_And_Resolve (Arg, Designated_Type (Typ)); 297 end if; 298 end Apply_Dereference; 299 300 ------------------------ 301 -- Has_Address_Clause -- 302 ------------------------ 303 304 function Has_Address_Clause (Exp : Node_Id) return Boolean is 305 begin 306 return 307 (Is_Entity_Name (Exp) and then 308 Present (Address_Clause (Entity (Exp)))) 309 or else 310 (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp))); 311 end Has_Address_Clause; 312 313 --------------------- 314 -- Is_Formal_Array -- 315 --------------------- 316 317 function Is_Formal_Array (Exp : Node_Id) return Boolean is 318 begin 319 return 320 (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp))) 321 or else 322 (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp))); 323 end Is_Formal_Array; 324 325 ------------------------ 326 -- Is_Non_Local_Array -- 327 ------------------------ 328 329 function Is_Non_Local_Array (Exp : Node_Id) return Boolean is 330 begin 331 return (Is_Entity_Name (Exp) 332 and then Scope (Entity (Exp)) /= Current_Scope) 333 or else (Nkind (Exp) = N_Slice 334 and then Is_Non_Local_Array (Prefix (Exp))); 335 end Is_Non_Local_Array; 336 337 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays 338 339 Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs); 340 Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs); 341 342 Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs); 343 Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs); 344 345 -- Start of processing for Expand_Assign_Array 346 347 begin 348 -- Deal with length check. Note that the length check is done with 349 -- respect to the right hand side as given, not a possible underlying 350 -- renamed object, since this would generate incorrect extra checks. 351 352 Apply_Length_Check (Rhs, L_Type); 353 354 -- We start by assuming that the move can be done in either direction, 355 -- i.e. that the two sides are completely disjoint. 356 357 Set_Forwards_OK (N, True); 358 Set_Backwards_OK (N, True); 359 360 -- Normally it is only the slice case that can lead to overlap, and 361 -- explicit checks for slices are made below. But there is one case 362 -- where the slice can be implicit and invisible to us: when we have a 363 -- one dimensional array, and either both operands are parameters, or 364 -- one is a parameter (which can be a slice passed by reference) and the 365 -- other is a non-local variable. In this case the parameter could be a 366 -- slice that overlaps with the other operand. 367 368 -- However, if the array subtype is a constrained first subtype in the 369 -- parameter case, then we don't have to worry about overlap, since 370 -- slice assignments aren't possible (other than for a slice denoting 371 -- the whole array). 372 373 -- Note: No overlap is possible if there is a change of representation, 374 -- so we can exclude this case. 375 376 if Ndim = 1 377 and then not Crep 378 and then 379 ((Lhs_Formal and Rhs_Formal) 380 or else 381 (Lhs_Formal and Rhs_Non_Local_Var) 382 or else 383 (Rhs_Formal and Lhs_Non_Local_Var)) 384 and then 385 (not Is_Constrained (Etype (Lhs)) 386 or else not Is_First_Subtype (Etype (Lhs))) 387 then 388 Set_Forwards_OK (N, False); 389 Set_Backwards_OK (N, False); 390 391 -- Note: the bit-packed case is not worrisome here, since if we have 392 -- a slice passed as a parameter, it is always aligned on a byte 393 -- boundary, and if there are no explicit slices, the assignment 394 -- can be performed directly. 395 end if; 396 397 -- If either operand has an address clause clear Backwards_OK and 398 -- Forwards_OK, since we cannot tell if the operands overlap. We 399 -- exclude this treatment when Rhs is an aggregate, since we know 400 -- that overlap can't occur. 401 402 if (Has_Address_Clause (Lhs) and then Nkind (Rhs) /= N_Aggregate) 403 or else Has_Address_Clause (Rhs) 404 then 405 Set_Forwards_OK (N, False); 406 Set_Backwards_OK (N, False); 407 end if; 408 409 -- We certainly must use a loop for change of representation and also 410 -- we use the operand of the conversion on the right hand side as the 411 -- effective right hand side (the component types must match in this 412 -- situation). 413 414 if Crep then 415 Act_Rhs := Get_Referenced_Object (Rhs); 416 R_Type := Get_Actual_Subtype (Act_Rhs); 417 Loop_Required := True; 418 419 -- We require a loop if the left side is possibly bit unaligned 420 421 elsif Possible_Bit_Aligned_Component (Lhs) 422 or else 423 Possible_Bit_Aligned_Component (Rhs) 424 then 425 Loop_Required := True; 426 427 -- Arrays with controlled components are expanded into a loop to force 428 -- calls to Adjust at the component level. 429 430 elsif Has_Controlled_Component (L_Type) then 431 Loop_Required := True; 432 433 -- If object is atomic/VFA, we cannot tolerate a loop 434 435 elsif Is_Atomic_Or_VFA_Object (Act_Lhs) 436 or else 437 Is_Atomic_Or_VFA_Object (Act_Rhs) 438 then 439 return; 440 441 -- Loop is required if we have atomic components since we have to 442 -- be sure to do any accesses on an element by element basis. 443 444 elsif Has_Atomic_Components (L_Type) 445 or else Has_Atomic_Components (R_Type) 446 or else Is_Atomic_Or_VFA (Component_Type (L_Type)) 447 or else Is_Atomic_Or_VFA (Component_Type (R_Type)) 448 then 449 Loop_Required := True; 450 451 -- Case where no slice is involved 452 453 elsif not L_Slice and not R_Slice then 454 455 -- The following code deals with the case of unconstrained bit packed 456 -- arrays. The problem is that the template for such arrays contains 457 -- the bounds of the actual source level array, but the copy of an 458 -- entire array requires the bounds of the underlying array. It would 459 -- be nice if the back end could take care of this, but right now it 460 -- does not know how, so if we have such a type, then we expand out 461 -- into a loop, which is inefficient but works correctly. If we don't 462 -- do this, we get the wrong length computed for the array to be 463 -- moved. The two cases we need to worry about are: 464 465 -- Explicit dereference of an unconstrained packed array type as in 466 -- the following example: 467 468 -- procedure C52 is 469 -- type BITS is array(INTEGER range <>) of BOOLEAN; 470 -- pragma PACK(BITS); 471 -- type A is access BITS; 472 -- P1,P2 : A; 473 -- begin 474 -- P1 := new BITS (1 .. 65_535); 475 -- P2 := new BITS (1 .. 65_535); 476 -- P2.ALL := P1.ALL; 477 -- end C52; 478 479 -- A formal parameter reference with an unconstrained bit array type 480 -- is the other case we need to worry about (here we assume the same 481 -- BITS type declared above): 482 483 -- procedure Write_All (File : out BITS; Contents : BITS); 484 -- begin 485 -- File.Storage := Contents; 486 -- end Write_All; 487 488 -- We expand to a loop in either of these two cases 489 490 -- Question for future thought. Another potentially more efficient 491 -- approach would be to create the actual subtype, and then do an 492 -- unchecked conversion to this actual subtype ??? 493 494 Check_Unconstrained_Bit_Packed_Array : declare 495 496 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean; 497 -- Function to perform required test for the first case, above 498 -- (dereference of an unconstrained bit packed array). 499 500 ----------------------- 501 -- Is_UBPA_Reference -- 502 ----------------------- 503 504 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is 505 Typ : constant Entity_Id := Underlying_Type (Etype (Opnd)); 506 P_Type : Entity_Id; 507 Des_Type : Entity_Id; 508 509 begin 510 if Present (Packed_Array_Impl_Type (Typ)) 511 and then Is_Array_Type (Packed_Array_Impl_Type (Typ)) 512 and then not Is_Constrained (Packed_Array_Impl_Type (Typ)) 513 then 514 return True; 515 516 elsif Nkind (Opnd) = N_Explicit_Dereference then 517 P_Type := Underlying_Type (Etype (Prefix (Opnd))); 518 519 if not Is_Access_Type (P_Type) then 520 return False; 521 522 else 523 Des_Type := Designated_Type (P_Type); 524 return 525 Is_Bit_Packed_Array (Des_Type) 526 and then not Is_Constrained (Des_Type); 527 end if; 528 529 else 530 return False; 531 end if; 532 end Is_UBPA_Reference; 533 534 -- Start of processing for Check_Unconstrained_Bit_Packed_Array 535 536 begin 537 if Is_UBPA_Reference (Lhs) 538 or else 539 Is_UBPA_Reference (Rhs) 540 then 541 Loop_Required := True; 542 543 -- Here if we do not have the case of a reference to a bit packed 544 -- unconstrained array case. In this case gigi can most certainly 545 -- handle the assignment if a forwards move is allowed. 546 547 -- (could it handle the backwards case also???) 548 549 elsif Forwards_OK (N) then 550 return; 551 end if; 552 end Check_Unconstrained_Bit_Packed_Array; 553 554 -- The back end can always handle the assignment if the right side is a 555 -- string literal (note that overlap is definitely impossible in this 556 -- case). If the type is packed, a string literal is always converted 557 -- into an aggregate, except in the case of a null slice, for which no 558 -- aggregate can be written. In that case, rewrite the assignment as a 559 -- null statement, a length check has already been emitted to verify 560 -- that the range of the left-hand side is empty. 561 562 -- Note that this code is not executed if we have an assignment of a 563 -- string literal to a non-bit aligned component of a record, a case 564 -- which cannot be handled by the backend. 565 566 elsif Nkind (Rhs) = N_String_Literal then 567 if String_Length (Strval (Rhs)) = 0 568 and then Is_Bit_Packed_Array (L_Type) 569 then 570 Rewrite (N, Make_Null_Statement (Loc)); 571 Analyze (N); 572 end if; 573 574 return; 575 576 -- If either operand is bit packed, then we need a loop, since we can't 577 -- be sure that the slice is byte aligned. Similarly, if either operand 578 -- is a possibly unaligned slice, then we need a loop (since the back 579 -- end cannot handle unaligned slices). 580 581 elsif Is_Bit_Packed_Array (L_Type) 582 or else Is_Bit_Packed_Array (R_Type) 583 or else Is_Possibly_Unaligned_Slice (Lhs) 584 or else Is_Possibly_Unaligned_Slice (Rhs) 585 then 586 Loop_Required := True; 587 588 -- If we are not bit-packed, and we have only one slice, then no overlap 589 -- is possible except in the parameter case, so we can let the back end 590 -- handle things. 591 592 elsif not (L_Slice and R_Slice) then 593 if Forwards_OK (N) then 594 return; 595 end if; 596 end if; 597 598 -- If the right-hand side is a string literal, introduce a temporary for 599 -- it, for use in the generated loop that will follow. 600 601 if Nkind (Rhs) = N_String_Literal then 602 declare 603 Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Rhs); 604 Decl : Node_Id; 605 606 begin 607 Decl := 608 Make_Object_Declaration (Loc, 609 Defining_Identifier => Temp, 610 Object_Definition => New_Occurrence_Of (L_Type, Loc), 611 Expression => Relocate_Node (Rhs)); 612 613 Insert_Action (N, Decl); 614 Rewrite (Rhs, New_Occurrence_Of (Temp, Loc)); 615 R_Type := Etype (Temp); 616 end; 617 end if; 618 619 -- Come here to complete the analysis 620 621 -- Loop_Required: Set to True if we know that a loop is required 622 -- regardless of overlap considerations. 623 624 -- Forwards_OK: Set to False if we already know that a forwards 625 -- move is not safe, else set to True. 626 627 -- Backwards_OK: Set to False if we already know that a backwards 628 -- move is not safe, else set to True 629 630 -- Our task at this stage is to complete the overlap analysis, which can 631 -- result in possibly setting Forwards_OK or Backwards_OK to False, and 632 -- then generating the final code, either by deciding that it is OK 633 -- after all to let Gigi handle it, or by generating appropriate code 634 -- in the front end. 635 636 declare 637 L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type)); 638 R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type)); 639 640 Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ); 641 Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ); 642 Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ); 643 Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ); 644 645 Act_L_Array : Node_Id; 646 Act_R_Array : Node_Id; 647 648 Cleft_Lo : Node_Id; 649 Cright_Lo : Node_Id; 650 Condition : Node_Id; 651 652 Cresult : Compare_Result; 653 654 begin 655 -- Get the expressions for the arrays. If we are dealing with a 656 -- private type, then convert to the underlying type. We can do 657 -- direct assignments to an array that is a private type, but we 658 -- cannot assign to elements of the array without this extra 659 -- unchecked conversion. 660 661 -- Note: We propagate Parent to the conversion nodes to generate 662 -- a well-formed subtree. 663 664 if Nkind (Act_Lhs) = N_Slice then 665 Larray := Prefix (Act_Lhs); 666 else 667 Larray := Act_Lhs; 668 669 if Is_Private_Type (Etype (Larray)) then 670 declare 671 Par : constant Node_Id := Parent (Larray); 672 begin 673 Larray := 674 Unchecked_Convert_To 675 (Underlying_Type (Etype (Larray)), Larray); 676 Set_Parent (Larray, Par); 677 end; 678 end if; 679 end if; 680 681 if Nkind (Act_Rhs) = N_Slice then 682 Rarray := Prefix (Act_Rhs); 683 else 684 Rarray := Act_Rhs; 685 686 if Is_Private_Type (Etype (Rarray)) then 687 declare 688 Par : constant Node_Id := Parent (Rarray); 689 begin 690 Rarray := 691 Unchecked_Convert_To 692 (Underlying_Type (Etype (Rarray)), Rarray); 693 Set_Parent (Rarray, Par); 694 end; 695 end if; 696 end if; 697 698 -- If both sides are slices, we must figure out whether it is safe 699 -- to do the move in one direction or the other. It is always safe 700 -- if there is a change of representation since obviously two arrays 701 -- with different representations cannot possibly overlap. 702 703 if (not Crep) and L_Slice and R_Slice then 704 Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs)); 705 Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs)); 706 707 -- If both left and right hand arrays are entity names, and refer 708 -- to different entities, then we know that the move is safe (the 709 -- two storage areas are completely disjoint). 710 711 if Is_Entity_Name (Act_L_Array) 712 and then Is_Entity_Name (Act_R_Array) 713 and then Entity (Act_L_Array) /= Entity (Act_R_Array) 714 then 715 null; 716 717 -- Otherwise, we assume the worst, which is that the two arrays 718 -- are the same array. There is no need to check if we know that 719 -- is the case, because if we don't know it, we still have to 720 -- assume it. 721 722 -- Generally if the same array is involved, then we have an 723 -- overlapping case. We will have to really assume the worst (i.e. 724 -- set neither of the OK flags) unless we can determine the lower 725 -- or upper bounds at compile time and compare them. 726 727 else 728 Cresult := 729 Compile_Time_Compare 730 (Left_Lo, Right_Lo, Assume_Valid => True); 731 732 if Cresult = Unknown then 733 Cresult := 734 Compile_Time_Compare 735 (Left_Hi, Right_Hi, Assume_Valid => True); 736 end if; 737 738 case Cresult is 739 when LT | LE | EQ => Set_Backwards_OK (N, False); 740 when GT | GE => Set_Forwards_OK (N, False); 741 when NE | Unknown => Set_Backwards_OK (N, False); 742 Set_Forwards_OK (N, False); 743 end case; 744 end if; 745 end if; 746 747 -- If after that analysis Loop_Required is False, meaning that we 748 -- have not discovered some non-overlap reason for requiring a loop, 749 -- then the outcome depends on the capabilities of the back end. 750 751 if not Loop_Required then 752 753 -- The GCC back end can deal with all cases of overlap by falling 754 -- back to memmove if it cannot use a more efficient approach. 755 756 if not AAMP_On_Target then 757 return; 758 759 -- Assume other back ends can handle it if Forwards_OK is set 760 761 elsif Forwards_OK (N) then 762 return; 763 764 -- If Forwards_OK is not set, the back end will need something 765 -- like memmove to handle the move. For now, this processing is 766 -- activated using the .s debug flag (-gnatd.s). 767 768 elsif Debug_Flag_Dot_S then 769 return; 770 end if; 771 end if; 772 773 -- At this stage we have to generate an explicit loop, and we have 774 -- the following cases: 775 776 -- Forwards_OK = True 777 778 -- Rnn : right_index := right_index'First; 779 -- for Lnn in left-index loop 780 -- left (Lnn) := right (Rnn); 781 -- Rnn := right_index'Succ (Rnn); 782 -- end loop; 783 784 -- Note: the above code MUST be analyzed with checks off, because 785 -- otherwise the Succ could overflow. But in any case this is more 786 -- efficient. 787 788 -- Forwards_OK = False, Backwards_OK = True 789 790 -- Rnn : right_index := right_index'Last; 791 -- for Lnn in reverse left-index loop 792 -- left (Lnn) := right (Rnn); 793 -- Rnn := right_index'Pred (Rnn); 794 -- end loop; 795 796 -- Note: the above code MUST be analyzed with checks off, because 797 -- otherwise the Pred could overflow. But in any case this is more 798 -- efficient. 799 800 -- Forwards_OK = Backwards_OK = False 801 802 -- This only happens if we have the same array on each side. It is 803 -- possible to create situations using overlays that violate this, 804 -- but we simply do not promise to get this "right" in this case. 805 806 -- There are two possible subcases. If the No_Implicit_Conditionals 807 -- restriction is set, then we generate the following code: 808 809 -- declare 810 -- T : constant <operand-type> := rhs; 811 -- begin 812 -- lhs := T; 813 -- end; 814 815 -- If implicit conditionals are permitted, then we generate: 816 817 -- if Left_Lo <= Right_Lo then 818 -- <code for Forwards_OK = True above> 819 -- else 820 -- <code for Backwards_OK = True above> 821 -- end if; 822 823 -- In order to detect possible aliasing, we examine the renamed 824 -- expression when the source or target is a renaming. However, 825 -- the renaming may be intended to capture an address that may be 826 -- affected by subsequent code, and therefore we must recover 827 -- the actual entity for the expansion that follows, not the 828 -- object it renames. In particular, if source or target designate 829 -- a portion of a dynamically allocated object, the pointer to it 830 -- may be reassigned but the renaming preserves the proper location. 831 832 if Is_Entity_Name (Rhs) 833 and then 834 Nkind (Parent (Entity (Rhs))) = N_Object_Renaming_Declaration 835 and then Nkind (Act_Rhs) = N_Slice 836 then 837 Rarray := Rhs; 838 end if; 839 840 if Is_Entity_Name (Lhs) 841 and then 842 Nkind (Parent (Entity (Lhs))) = N_Object_Renaming_Declaration 843 and then Nkind (Act_Lhs) = N_Slice 844 then 845 Larray := Lhs; 846 end if; 847 848 -- Cases where either Forwards_OK or Backwards_OK is true 849 850 if Forwards_OK (N) or else Backwards_OK (N) then 851 if Needs_Finalization (Component_Type (L_Type)) 852 and then Base_Type (L_Type) = Base_Type (R_Type) 853 and then Ndim = 1 854 and then not No_Ctrl_Actions (N) 855 then 856 declare 857 Proc : constant Entity_Id := 858 TSS (Base_Type (L_Type), TSS_Slice_Assign); 859 Actuals : List_Id; 860 861 begin 862 Apply_Dereference (Larray); 863 Apply_Dereference (Rarray); 864 Actuals := New_List ( 865 Duplicate_Subexpr (Larray, Name_Req => True), 866 Duplicate_Subexpr (Rarray, Name_Req => True), 867 Duplicate_Subexpr (Left_Lo, Name_Req => True), 868 Duplicate_Subexpr (Left_Hi, Name_Req => True), 869 Duplicate_Subexpr (Right_Lo, Name_Req => True), 870 Duplicate_Subexpr (Right_Hi, Name_Req => True)); 871 872 Append_To (Actuals, 873 New_Occurrence_Of ( 874 Boolean_Literals (not Forwards_OK (N)), Loc)); 875 876 Rewrite (N, 877 Make_Procedure_Call_Statement (Loc, 878 Name => New_Occurrence_Of (Proc, Loc), 879 Parameter_Associations => Actuals)); 880 end; 881 882 else 883 Rewrite (N, 884 Expand_Assign_Array_Loop 885 (N, Larray, Rarray, L_Type, R_Type, Ndim, 886 Rev => not Forwards_OK (N))); 887 end if; 888 889 -- Case of both are false with No_Implicit_Conditionals 890 891 elsif Restriction_Active (No_Implicit_Conditionals) then 892 declare 893 T : constant Entity_Id := 894 Make_Defining_Identifier (Loc, Chars => Name_T); 895 896 begin 897 Rewrite (N, 898 Make_Block_Statement (Loc, 899 Declarations => New_List ( 900 Make_Object_Declaration (Loc, 901 Defining_Identifier => T, 902 Constant_Present => True, 903 Object_Definition => 904 New_Occurrence_Of (Etype (Rhs), Loc), 905 Expression => Relocate_Node (Rhs))), 906 907 Handled_Statement_Sequence => 908 Make_Handled_Sequence_Of_Statements (Loc, 909 Statements => New_List ( 910 Make_Assignment_Statement (Loc, 911 Name => Relocate_Node (Lhs), 912 Expression => New_Occurrence_Of (T, Loc)))))); 913 end; 914 915 -- Case of both are false with implicit conditionals allowed 916 917 else 918 -- Before we generate this code, we must ensure that the left and 919 -- right side array types are defined. They may be itypes, and we 920 -- cannot let them be defined inside the if, since the first use 921 -- in the then may not be executed. 922 923 Ensure_Defined (L_Type, N); 924 Ensure_Defined (R_Type, N); 925 926 -- We normally compare addresses to find out which way round to 927 -- do the loop, since this is reliable, and handles the cases of 928 -- parameters, conversions etc. But we can't do that in the bit 929 -- packed case, because addresses don't work there. 930 931 if not Is_Bit_Packed_Array (L_Type) then 932 Condition := 933 Make_Op_Le (Loc, 934 Left_Opnd => 935 Unchecked_Convert_To (RTE (RE_Integer_Address), 936 Make_Attribute_Reference (Loc, 937 Prefix => 938 Make_Indexed_Component (Loc, 939 Prefix => 940 Duplicate_Subexpr_Move_Checks (Larray, True), 941 Expressions => New_List ( 942 Make_Attribute_Reference (Loc, 943 Prefix => 944 New_Occurrence_Of 945 (L_Index_Typ, Loc), 946 Attribute_Name => Name_First))), 947 Attribute_Name => Name_Address)), 948 949 Right_Opnd => 950 Unchecked_Convert_To (RTE (RE_Integer_Address), 951 Make_Attribute_Reference (Loc, 952 Prefix => 953 Make_Indexed_Component (Loc, 954 Prefix => 955 Duplicate_Subexpr_Move_Checks (Rarray, True), 956 Expressions => New_List ( 957 Make_Attribute_Reference (Loc, 958 Prefix => 959 New_Occurrence_Of 960 (R_Index_Typ, Loc), 961 Attribute_Name => Name_First))), 962 Attribute_Name => Name_Address))); 963 964 -- For the bit packed and VM cases we use the bounds. That's OK, 965 -- because we don't have to worry about parameters, since they 966 -- cannot cause overlap. Perhaps we should worry about weird slice 967 -- conversions ??? 968 969 else 970 -- Copy the bounds 971 972 Cleft_Lo := New_Copy_Tree (Left_Lo); 973 Cright_Lo := New_Copy_Tree (Right_Lo); 974 975 -- If the types do not match we add an implicit conversion 976 -- here to ensure proper match 977 978 if Etype (Left_Lo) /= Etype (Right_Lo) then 979 Cright_Lo := 980 Unchecked_Convert_To (Etype (Left_Lo), Cright_Lo); 981 end if; 982 983 -- Reset the Analyzed flag, because the bounds of the index 984 -- type itself may be universal, and must must be reanalyzed 985 -- to acquire the proper type for the back end. 986 987 Set_Analyzed (Cleft_Lo, False); 988 Set_Analyzed (Cright_Lo, False); 989 990 Condition := 991 Make_Op_Le (Loc, 992 Left_Opnd => Cleft_Lo, 993 Right_Opnd => Cright_Lo); 994 end if; 995 996 if Needs_Finalization (Component_Type (L_Type)) 997 and then Base_Type (L_Type) = Base_Type (R_Type) 998 and then Ndim = 1 999 and then not No_Ctrl_Actions (N) 1000 then 1001 1002 -- Call TSS procedure for array assignment, passing the 1003 -- explicit bounds of right and left hand sides. 1004 1005 declare 1006 Proc : constant Entity_Id := 1007 TSS (Base_Type (L_Type), TSS_Slice_Assign); 1008 Actuals : List_Id; 1009 1010 begin 1011 Apply_Dereference (Larray); 1012 Apply_Dereference (Rarray); 1013 Actuals := New_List ( 1014 Duplicate_Subexpr (Larray, Name_Req => True), 1015 Duplicate_Subexpr (Rarray, Name_Req => True), 1016 Duplicate_Subexpr (Left_Lo, Name_Req => True), 1017 Duplicate_Subexpr (Left_Hi, Name_Req => True), 1018 Duplicate_Subexpr (Right_Lo, Name_Req => True), 1019 Duplicate_Subexpr (Right_Hi, Name_Req => True)); 1020 1021 Append_To (Actuals, 1022 Make_Op_Not (Loc, 1023 Right_Opnd => Condition)); 1024 1025 Rewrite (N, 1026 Make_Procedure_Call_Statement (Loc, 1027 Name => New_Occurrence_Of (Proc, Loc), 1028 Parameter_Associations => Actuals)); 1029 end; 1030 1031 else 1032 Rewrite (N, 1033 Make_Implicit_If_Statement (N, 1034 Condition => Condition, 1035 1036 Then_Statements => New_List ( 1037 Expand_Assign_Array_Loop 1038 (N, Larray, Rarray, L_Type, R_Type, Ndim, 1039 Rev => False)), 1040 1041 Else_Statements => New_List ( 1042 Expand_Assign_Array_Loop 1043 (N, Larray, Rarray, L_Type, R_Type, Ndim, 1044 Rev => True)))); 1045 end if; 1046 end if; 1047 1048 Analyze (N, Suppress => All_Checks); 1049 end; 1050 1051 exception 1052 when RE_Not_Available => 1053 return; 1054 end Expand_Assign_Array; 1055 1056 ------------------------------ 1057 -- Expand_Assign_Array_Loop -- 1058 ------------------------------ 1059 1060 -- The following is an example of the loop generated for the case of a 1061 -- two-dimensional array: 1062 1063 -- declare 1064 -- R2b : Tm1X1 := 1; 1065 -- begin 1066 -- for L1b in 1 .. 100 loop 1067 -- declare 1068 -- R4b : Tm1X2 := 1; 1069 -- begin 1070 -- for L3b in 1 .. 100 loop 1071 -- vm1 (L1b, L3b) := vm2 (R2b, R4b); 1072 -- R4b := Tm1X2'succ(R4b); 1073 -- end loop; 1074 -- end; 1075 -- R2b := Tm1X1'succ(R2b); 1076 -- end loop; 1077 -- end; 1078 1079 -- Here Rev is False, and Tm1Xn are the subscript types for the right hand 1080 -- side. The declarations of R2b and R4b are inserted before the original 1081 -- assignment statement. 1082 1083 function Expand_Assign_Array_Loop 1084 (N : Node_Id; 1085 Larray : Entity_Id; 1086 Rarray : Entity_Id; 1087 L_Type : Entity_Id; 1088 R_Type : Entity_Id; 1089 Ndim : Pos; 1090 Rev : Boolean) return Node_Id 1091 is 1092 Loc : constant Source_Ptr := Sloc (N); 1093 1094 Lnn : array (1 .. Ndim) of Entity_Id; 1095 Rnn : array (1 .. Ndim) of Entity_Id; 1096 -- Entities used as subscripts on left and right sides 1097 1098 L_Index_Type : array (1 .. Ndim) of Entity_Id; 1099 R_Index_Type : array (1 .. Ndim) of Entity_Id; 1100 -- Left and right index types 1101 1102 Assign : Node_Id; 1103 1104 F_Or_L : Name_Id; 1105 S_Or_P : Name_Id; 1106 1107 function Build_Step (J : Nat) return Node_Id; 1108 -- The increment step for the index of the right-hand side is written 1109 -- as an attribute reference (Succ or Pred). This function returns 1110 -- the corresponding node, which is placed at the end of the loop body. 1111 1112 ---------------- 1113 -- Build_Step -- 1114 ---------------- 1115 1116 function Build_Step (J : Nat) return Node_Id is 1117 Step : Node_Id; 1118 Lim : Name_Id; 1119 1120 begin 1121 if Rev then 1122 Lim := Name_First; 1123 else 1124 Lim := Name_Last; 1125 end if; 1126 1127 Step := 1128 Make_Assignment_Statement (Loc, 1129 Name => New_Occurrence_Of (Rnn (J), Loc), 1130 Expression => 1131 Make_Attribute_Reference (Loc, 1132 Prefix => 1133 New_Occurrence_Of (R_Index_Type (J), Loc), 1134 Attribute_Name => S_Or_P, 1135 Expressions => New_List ( 1136 New_Occurrence_Of (Rnn (J), Loc)))); 1137 1138 -- Note that on the last iteration of the loop, the index is increased 1139 -- (or decreased) past the corresponding bound. This is consistent with 1140 -- the C semantics of the back-end, where such an off-by-one value on a 1141 -- dead index variable is OK. However, in CodePeer mode this leads to 1142 -- spurious warnings, and thus we place a guard around the attribute 1143 -- reference. For obvious reasons we only do this for CodePeer. 1144 1145 if CodePeer_Mode then 1146 Step := 1147 Make_If_Statement (Loc, 1148 Condition => 1149 Make_Op_Ne (Loc, 1150 Left_Opnd => New_Occurrence_Of (Lnn (J), Loc), 1151 Right_Opnd => 1152 Make_Attribute_Reference (Loc, 1153 Prefix => New_Occurrence_Of (L_Index_Type (J), Loc), 1154 Attribute_Name => Lim)), 1155 Then_Statements => New_List (Step)); 1156 end if; 1157 1158 return Step; 1159 end Build_Step; 1160 1161 -- Start of processing for Expand_Assign_Array_Loop 1162 1163 begin 1164 if Rev then 1165 F_Or_L := Name_Last; 1166 S_Or_P := Name_Pred; 1167 else 1168 F_Or_L := Name_First; 1169 S_Or_P := Name_Succ; 1170 end if; 1171 1172 -- Setup index types and subscript entities 1173 1174 declare 1175 L_Index : Node_Id; 1176 R_Index : Node_Id; 1177 1178 begin 1179 L_Index := First_Index (L_Type); 1180 R_Index := First_Index (R_Type); 1181 1182 for J in 1 .. Ndim loop 1183 Lnn (J) := Make_Temporary (Loc, 'L'); 1184 Rnn (J) := Make_Temporary (Loc, 'R'); 1185 1186 L_Index_Type (J) := Etype (L_Index); 1187 R_Index_Type (J) := Etype (R_Index); 1188 1189 Next_Index (L_Index); 1190 Next_Index (R_Index); 1191 end loop; 1192 end; 1193 1194 -- Now construct the assignment statement 1195 1196 declare 1197 ExprL : constant List_Id := New_List; 1198 ExprR : constant List_Id := New_List; 1199 1200 begin 1201 for J in 1 .. Ndim loop 1202 Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc)); 1203 Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc)); 1204 end loop; 1205 1206 Assign := 1207 Make_Assignment_Statement (Loc, 1208 Name => 1209 Make_Indexed_Component (Loc, 1210 Prefix => Duplicate_Subexpr (Larray, Name_Req => True), 1211 Expressions => ExprL), 1212 Expression => 1213 Make_Indexed_Component (Loc, 1214 Prefix => Duplicate_Subexpr (Rarray, Name_Req => True), 1215 Expressions => ExprR)); 1216 1217 -- We set assignment OK, since there are some cases, e.g. in object 1218 -- declarations, where we are actually assigning into a constant. 1219 -- If there really is an illegality, it was caught long before now, 1220 -- and was flagged when the original assignment was analyzed. 1221 1222 Set_Assignment_OK (Name (Assign)); 1223 1224 -- Propagate the No_Ctrl_Actions flag to individual assignments 1225 1226 Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N)); 1227 end; 1228 1229 -- Now construct the loop from the inside out, with the last subscript 1230 -- varying most rapidly. Note that Assign is first the raw assignment 1231 -- statement, and then subsequently the loop that wraps it up. 1232 1233 for J in reverse 1 .. Ndim loop 1234 Assign := 1235 Make_Block_Statement (Loc, 1236 Declarations => New_List ( 1237 Make_Object_Declaration (Loc, 1238 Defining_Identifier => Rnn (J), 1239 Object_Definition => 1240 New_Occurrence_Of (R_Index_Type (J), Loc), 1241 Expression => 1242 Make_Attribute_Reference (Loc, 1243 Prefix => New_Occurrence_Of (R_Index_Type (J), Loc), 1244 Attribute_Name => F_Or_L))), 1245 1246 Handled_Statement_Sequence => 1247 Make_Handled_Sequence_Of_Statements (Loc, 1248 Statements => New_List ( 1249 Make_Implicit_Loop_Statement (N, 1250 Iteration_Scheme => 1251 Make_Iteration_Scheme (Loc, 1252 Loop_Parameter_Specification => 1253 Make_Loop_Parameter_Specification (Loc, 1254 Defining_Identifier => Lnn (J), 1255 Reverse_Present => Rev, 1256 Discrete_Subtype_Definition => 1257 New_Occurrence_Of (L_Index_Type (J), Loc))), 1258 1259 Statements => New_List (Assign, Build_Step (J)))))); 1260 end loop; 1261 1262 return Assign; 1263 end Expand_Assign_Array_Loop; 1264 1265 -------------------------- 1266 -- Expand_Assign_Record -- 1267 -------------------------- 1268 1269 procedure Expand_Assign_Record (N : Node_Id) is 1270 Lhs : constant Node_Id := Name (N); 1271 Rhs : Node_Id := Expression (N); 1272 L_Typ : constant Entity_Id := Base_Type (Etype (Lhs)); 1273 1274 begin 1275 -- If change of representation, then extract the real right hand side 1276 -- from the type conversion, and proceed with component-wise assignment, 1277 -- since the two types are not the same as far as the back end is 1278 -- concerned. 1279 1280 if Change_Of_Representation (N) then 1281 Rhs := Expression (Rhs); 1282 1283 -- If this may be a case of a large bit aligned component, then proceed 1284 -- with component-wise assignment, to avoid possible clobbering of other 1285 -- components sharing bits in the first or last byte of the component to 1286 -- be assigned. 1287 1288 elsif Possible_Bit_Aligned_Component (Lhs) 1289 or 1290 Possible_Bit_Aligned_Component (Rhs) 1291 then 1292 null; 1293 1294 -- If we have a tagged type that has a complete record representation 1295 -- clause, we must do we must do component-wise assignments, since child 1296 -- types may have used gaps for their components, and we might be 1297 -- dealing with a view conversion. 1298 1299 elsif Is_Fully_Repped_Tagged_Type (L_Typ) then 1300 null; 1301 1302 -- If neither condition met, then nothing special to do, the back end 1303 -- can handle assignment of the entire component as a single entity. 1304 1305 else 1306 return; 1307 end if; 1308 1309 -- At this stage we know that we must do a component wise assignment 1310 1311 declare 1312 Loc : constant Source_Ptr := Sloc (N); 1313 R_Typ : constant Entity_Id := Base_Type (Etype (Rhs)); 1314 Decl : constant Node_Id := Declaration_Node (R_Typ); 1315 RDef : Node_Id; 1316 F : Entity_Id; 1317 1318 function Find_Component 1319 (Typ : Entity_Id; 1320 Comp : Entity_Id) return Entity_Id; 1321 -- Find the component with the given name in the underlying record 1322 -- declaration for Typ. We need to use the actual entity because the 1323 -- type may be private and resolution by identifier alone would fail. 1324 1325 function Make_Component_List_Assign 1326 (CL : Node_Id; 1327 U_U : Boolean := False) return List_Id; 1328 -- Returns a sequence of statements to assign the components that 1329 -- are referenced in the given component list. The flag U_U is 1330 -- used to force the usage of the inferred value of the variant 1331 -- part expression as the switch for the generated case statement. 1332 1333 function Make_Field_Assign 1334 (C : Entity_Id; 1335 U_U : Boolean := False) return Node_Id; 1336 -- Given C, the entity for a discriminant or component, build an 1337 -- assignment for the corresponding field values. The flag U_U 1338 -- signals the presence of an Unchecked_Union and forces the usage 1339 -- of the inferred discriminant value of C as the right hand side 1340 -- of the assignment. 1341 1342 function Make_Field_Assigns (CI : List_Id) return List_Id; 1343 -- Given CI, a component items list, construct series of statements 1344 -- for fieldwise assignment of the corresponding components. 1345 1346 -------------------- 1347 -- Find_Component -- 1348 -------------------- 1349 1350 function Find_Component 1351 (Typ : Entity_Id; 1352 Comp : Entity_Id) return Entity_Id 1353 is 1354 Utyp : constant Entity_Id := Underlying_Type (Typ); 1355 C : Entity_Id; 1356 1357 begin 1358 C := First_Entity (Utyp); 1359 while Present (C) loop 1360 if Chars (C) = Chars (Comp) then 1361 return C; 1362 end if; 1363 1364 Next_Entity (C); 1365 end loop; 1366 1367 raise Program_Error; 1368 end Find_Component; 1369 1370 -------------------------------- 1371 -- Make_Component_List_Assign -- 1372 -------------------------------- 1373 1374 function Make_Component_List_Assign 1375 (CL : Node_Id; 1376 U_U : Boolean := False) return List_Id 1377 is 1378 CI : constant List_Id := Component_Items (CL); 1379 VP : constant Node_Id := Variant_Part (CL); 1380 1381 Alts : List_Id; 1382 DC : Node_Id; 1383 DCH : List_Id; 1384 Expr : Node_Id; 1385 Result : List_Id; 1386 V : Node_Id; 1387 1388 begin 1389 Result := Make_Field_Assigns (CI); 1390 1391 if Present (VP) then 1392 V := First_Non_Pragma (Variants (VP)); 1393 Alts := New_List; 1394 while Present (V) loop 1395 DCH := New_List; 1396 DC := First (Discrete_Choices (V)); 1397 while Present (DC) loop 1398 Append_To (DCH, New_Copy_Tree (DC)); 1399 Next (DC); 1400 end loop; 1401 1402 Append_To (Alts, 1403 Make_Case_Statement_Alternative (Loc, 1404 Discrete_Choices => DCH, 1405 Statements => 1406 Make_Component_List_Assign (Component_List (V)))); 1407 Next_Non_Pragma (V); 1408 end loop; 1409 1410 -- If we have an Unchecked_Union, use the value of the inferred 1411 -- discriminant of the variant part expression as the switch 1412 -- for the case statement. The case statement may later be 1413 -- folded. 1414 1415 if U_U then 1416 Expr := 1417 New_Copy (Get_Discriminant_Value ( 1418 Entity (Name (VP)), 1419 Etype (Rhs), 1420 Discriminant_Constraint (Etype (Rhs)))); 1421 else 1422 Expr := 1423 Make_Selected_Component (Loc, 1424 Prefix => Duplicate_Subexpr (Rhs), 1425 Selector_Name => 1426 Make_Identifier (Loc, Chars (Name (VP)))); 1427 end if; 1428 1429 Append_To (Result, 1430 Make_Case_Statement (Loc, 1431 Expression => Expr, 1432 Alternatives => Alts)); 1433 end if; 1434 1435 return Result; 1436 end Make_Component_List_Assign; 1437 1438 ----------------------- 1439 -- Make_Field_Assign -- 1440 ----------------------- 1441 1442 function Make_Field_Assign 1443 (C : Entity_Id; 1444 U_U : Boolean := False) return Node_Id 1445 is 1446 A : Node_Id; 1447 Expr : Node_Id; 1448 1449 begin 1450 -- In the case of an Unchecked_Union, use the discriminant 1451 -- constraint value as on the right hand side of the assignment. 1452 1453 if U_U then 1454 Expr := 1455 New_Copy (Get_Discriminant_Value (C, 1456 Etype (Rhs), 1457 Discriminant_Constraint (Etype (Rhs)))); 1458 else 1459 Expr := 1460 Make_Selected_Component (Loc, 1461 Prefix => Duplicate_Subexpr (Rhs), 1462 Selector_Name => New_Occurrence_Of (C, Loc)); 1463 end if; 1464 1465 A := 1466 Make_Assignment_Statement (Loc, 1467 Name => 1468 Make_Selected_Component (Loc, 1469 Prefix => Duplicate_Subexpr (Lhs), 1470 Selector_Name => 1471 New_Occurrence_Of (Find_Component (L_Typ, C), Loc)), 1472 Expression => Expr); 1473 1474 -- Set Assignment_OK, so discriminants can be assigned 1475 1476 Set_Assignment_OK (Name (A), True); 1477 1478 if Componentwise_Assignment (N) 1479 and then Nkind (Name (A)) = N_Selected_Component 1480 and then Chars (Selector_Name (Name (A))) = Name_uParent 1481 then 1482 Set_Componentwise_Assignment (A); 1483 end if; 1484 1485 return A; 1486 end Make_Field_Assign; 1487 1488 ------------------------ 1489 -- Make_Field_Assigns -- 1490 ------------------------ 1491 1492 function Make_Field_Assigns (CI : List_Id) return List_Id is 1493 Item : Node_Id; 1494 Result : List_Id; 1495 1496 begin 1497 Item := First (CI); 1498 Result := New_List; 1499 1500 while Present (Item) loop 1501 1502 -- Look for components, but exclude _tag field assignment if 1503 -- the special Componentwise_Assignment flag is set. 1504 1505 if Nkind (Item) = N_Component_Declaration 1506 and then not (Is_Tag (Defining_Identifier (Item)) 1507 and then Componentwise_Assignment (N)) 1508 then 1509 Append_To 1510 (Result, Make_Field_Assign (Defining_Identifier (Item))); 1511 end if; 1512 1513 Next (Item); 1514 end loop; 1515 1516 return Result; 1517 end Make_Field_Assigns; 1518 1519 -- Start of processing for Expand_Assign_Record 1520 1521 begin 1522 -- Note that we use the base types for this processing. This results 1523 -- in some extra work in the constrained case, but the change of 1524 -- representation case is so unusual that it is not worth the effort. 1525 1526 -- First copy the discriminants. This is done unconditionally. It 1527 -- is required in the unconstrained left side case, and also in the 1528 -- case where this assignment was constructed during the expansion 1529 -- of a type conversion (since initialization of discriminants is 1530 -- suppressed in this case). It is unnecessary but harmless in 1531 -- other cases. 1532 1533 if Has_Discriminants (L_Typ) then 1534 F := First_Discriminant (R_Typ); 1535 while Present (F) loop 1536 1537 -- If we are expanding the initialization of a derived record 1538 -- that constrains or renames discriminants of the parent, we 1539 -- must use the corresponding discriminant in the parent. 1540 1541 declare 1542 CF : Entity_Id; 1543 1544 begin 1545 if Inside_Init_Proc 1546 and then Present (Corresponding_Discriminant (F)) 1547 then 1548 CF := Corresponding_Discriminant (F); 1549 else 1550 CF := F; 1551 end if; 1552 1553 if Is_Unchecked_Union (Base_Type (R_Typ)) then 1554 1555 -- Within an initialization procedure this is the 1556 -- assignment to an unchecked union component, in which 1557 -- case there is no discriminant to initialize. 1558 1559 if Inside_Init_Proc then 1560 null; 1561 1562 else 1563 -- The assignment is part of a conversion from a 1564 -- derived unchecked union type with an inferable 1565 -- discriminant, to a parent type. 1566 1567 Insert_Action (N, Make_Field_Assign (CF, True)); 1568 end if; 1569 1570 else 1571 Insert_Action (N, Make_Field_Assign (CF)); 1572 end if; 1573 1574 Next_Discriminant (F); 1575 end; 1576 end loop; 1577 end if; 1578 1579 -- We know the underlying type is a record, but its current view 1580 -- may be private. We must retrieve the usable record declaration. 1581 1582 if Nkind_In (Decl, N_Private_Type_Declaration, 1583 N_Private_Extension_Declaration) 1584 and then Present (Full_View (R_Typ)) 1585 then 1586 RDef := Type_Definition (Declaration_Node (Full_View (R_Typ))); 1587 else 1588 RDef := Type_Definition (Decl); 1589 end if; 1590 1591 if Nkind (RDef) = N_Derived_Type_Definition then 1592 RDef := Record_Extension_Part (RDef); 1593 end if; 1594 1595 if Nkind (RDef) = N_Record_Definition 1596 and then Present (Component_List (RDef)) 1597 then 1598 if Is_Unchecked_Union (R_Typ) then 1599 Insert_Actions (N, 1600 Make_Component_List_Assign (Component_List (RDef), True)); 1601 else 1602 Insert_Actions 1603 (N, Make_Component_List_Assign (Component_List (RDef))); 1604 end if; 1605 1606 Rewrite (N, Make_Null_Statement (Loc)); 1607 end if; 1608 end; 1609 end Expand_Assign_Record; 1610 1611 ----------------------------------- 1612 -- Expand_N_Assignment_Statement -- 1613 ----------------------------------- 1614 1615 -- This procedure implements various cases where an assignment statement 1616 -- cannot just be passed on to the back end in untransformed state. 1617 1618 procedure Expand_N_Assignment_Statement (N : Node_Id) is 1619 Crep : constant Boolean := Change_Of_Representation (N); 1620 Lhs : constant Node_Id := Name (N); 1621 Loc : constant Source_Ptr := Sloc (N); 1622 Rhs : constant Node_Id := Expression (N); 1623 Typ : constant Entity_Id := Underlying_Type (Etype (Lhs)); 1624 Exp : Node_Id; 1625 1626 Save_Ghost_Mode : constant Ghost_Mode_Type := Ghost_Mode; 1627 1628 begin 1629 -- The assignment statement is Ghost when the left hand side is Ghost. 1630 -- Set the mode now to ensure that any nodes generated during expansion 1631 -- are properly marked as Ghost. 1632 1633 Set_Ghost_Mode (N); 1634 1635 -- Special case to check right away, if the Componentwise_Assignment 1636 -- flag is set, this is a reanalysis from the expansion of the primitive 1637 -- assignment procedure for a tagged type, and all we need to do is to 1638 -- expand to assignment of components, because otherwise, we would get 1639 -- infinite recursion (since this looks like a tagged assignment which 1640 -- would normally try to *call* the primitive assignment procedure). 1641 1642 if Componentwise_Assignment (N) then 1643 Expand_Assign_Record (N); 1644 Ghost_Mode := Save_Ghost_Mode; 1645 return; 1646 end if; 1647 1648 -- Defend against invalid subscripts on left side if we are in standard 1649 -- validity checking mode. No need to do this if we are checking all 1650 -- subscripts. 1651 1652 -- Note that we do this right away, because there are some early return 1653 -- paths in this procedure, and this is required on all paths. 1654 1655 if Validity_Checks_On 1656 and then Validity_Check_Default 1657 and then not Validity_Check_Subscripts 1658 then 1659 Check_Valid_Lvalue_Subscripts (Lhs); 1660 end if; 1661 1662 -- Ada 2005 (AI-327): Handle assignment to priority of protected object 1663 1664 -- Rewrite an assignment to X'Priority into a run-time call 1665 1666 -- For example: X'Priority := New_Prio_Expr; 1667 -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr); 1668 1669 -- Note that although X'Priority is notionally an object, it is quite 1670 -- deliberately not defined as an aliased object in the RM. This means 1671 -- that it works fine to rewrite it as a call, without having to worry 1672 -- about complications that would other arise from X'Priority'Access, 1673 -- which is illegal, because of the lack of aliasing. 1674 1675 if Ada_Version >= Ada_2005 then 1676 declare 1677 Call : Node_Id; 1678 Conctyp : Entity_Id; 1679 Ent : Entity_Id; 1680 Subprg : Entity_Id; 1681 RT_Subprg_Name : Node_Id; 1682 1683 begin 1684 -- Handle chains of renamings 1685 1686 Ent := Name (N); 1687 while Nkind (Ent) in N_Has_Entity 1688 and then Present (Entity (Ent)) 1689 and then Present (Renamed_Object (Entity (Ent))) 1690 loop 1691 Ent := Renamed_Object (Entity (Ent)); 1692 end loop; 1693 1694 -- The attribute Priority applied to protected objects has been 1695 -- previously expanded into a call to the Get_Ceiling run-time 1696 -- subprogram. 1697 1698 if Nkind (Ent) = N_Function_Call 1699 and then (Entity (Name (Ent)) = RTE (RE_Get_Ceiling) 1700 or else 1701 Entity (Name (Ent)) = RTE (RO_PE_Get_Ceiling)) 1702 then 1703 -- Look for the enclosing concurrent type 1704 1705 Conctyp := Current_Scope; 1706 while not Is_Concurrent_Type (Conctyp) loop 1707 Conctyp := Scope (Conctyp); 1708 end loop; 1709 1710 pragma Assert (Is_Protected_Type (Conctyp)); 1711 1712 -- Generate the first actual of the call 1713 1714 Subprg := Current_Scope; 1715 while not Present (Protected_Body_Subprogram (Subprg)) loop 1716 Subprg := Scope (Subprg); 1717 end loop; 1718 1719 -- Select the appropriate run-time call 1720 1721 if Number_Entries (Conctyp) = 0 then 1722 RT_Subprg_Name := 1723 New_Occurrence_Of (RTE (RE_Set_Ceiling), Loc); 1724 else 1725 RT_Subprg_Name := 1726 New_Occurrence_Of (RTE (RO_PE_Set_Ceiling), Loc); 1727 end if; 1728 1729 Call := 1730 Make_Procedure_Call_Statement (Loc, 1731 Name => RT_Subprg_Name, 1732 Parameter_Associations => New_List ( 1733 New_Copy_Tree (First (Parameter_Associations (Ent))), 1734 Relocate_Node (Expression (N)))); 1735 1736 Rewrite (N, Call); 1737 Analyze (N); 1738 1739 Ghost_Mode := Save_Ghost_Mode; 1740 return; 1741 end if; 1742 end; 1743 end if; 1744 1745 -- Deal with assignment checks unless suppressed 1746 1747 if not Suppress_Assignment_Checks (N) then 1748 1749 -- First deal with generation of range check if required 1750 1751 if Do_Range_Check (Rhs) then 1752 Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed); 1753 end if; 1754 1755 -- Then generate predicate check if required 1756 1757 Apply_Predicate_Check (Rhs, Typ); 1758 end if; 1759 1760 -- Check for a special case where a high level transformation is 1761 -- required. If we have either of: 1762 1763 -- P.field := rhs; 1764 -- P (sub) := rhs; 1765 1766 -- where P is a reference to a bit packed array, then we have to unwind 1767 -- the assignment. The exact meaning of being a reference to a bit 1768 -- packed array is as follows: 1769 1770 -- An indexed component whose prefix is a bit packed array is a 1771 -- reference to a bit packed array. 1772 1773 -- An indexed component or selected component whose prefix is a 1774 -- reference to a bit packed array is itself a reference ot a 1775 -- bit packed array. 1776 1777 -- The required transformation is 1778 1779 -- Tnn : prefix_type := P; 1780 -- Tnn.field := rhs; 1781 -- P := Tnn; 1782 1783 -- or 1784 1785 -- Tnn : prefix_type := P; 1786 -- Tnn (subscr) := rhs; 1787 -- P := Tnn; 1788 1789 -- Since P is going to be evaluated more than once, any subscripts 1790 -- in P must have their evaluation forced. 1791 1792 if Nkind_In (Lhs, N_Indexed_Component, N_Selected_Component) 1793 and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs)) 1794 then 1795 declare 1796 BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs)); 1797 BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr); 1798 Tnn : constant Entity_Id := 1799 Make_Temporary (Loc, 'T', BPAR_Expr); 1800 1801 begin 1802 -- Insert the post assignment first, because we want to copy the 1803 -- BPAR_Expr tree before it gets analyzed in the context of the 1804 -- pre assignment. Note that we do not analyze the post assignment 1805 -- yet (we cannot till we have completed the analysis of the pre 1806 -- assignment). As usual, the analysis of this post assignment 1807 -- will happen on its own when we "run into" it after finishing 1808 -- the current assignment. 1809 1810 Insert_After (N, 1811 Make_Assignment_Statement (Loc, 1812 Name => New_Copy_Tree (BPAR_Expr), 1813 Expression => New_Occurrence_Of (Tnn, Loc))); 1814 1815 -- At this stage BPAR_Expr is a reference to a bit packed array 1816 -- where the reference was not expanded in the original tree, 1817 -- since it was on the left side of an assignment. But in the 1818 -- pre-assignment statement (the object definition), BPAR_Expr 1819 -- will end up on the right hand side, and must be reexpanded. To 1820 -- achieve this, we reset the analyzed flag of all selected and 1821 -- indexed components down to the actual indexed component for 1822 -- the packed array. 1823 1824 Exp := BPAR_Expr; 1825 loop 1826 Set_Analyzed (Exp, False); 1827 1828 if Nkind_In 1829 (Exp, N_Selected_Component, N_Indexed_Component) 1830 then 1831 Exp := Prefix (Exp); 1832 else 1833 exit; 1834 end if; 1835 end loop; 1836 1837 -- Now we can insert and analyze the pre-assignment 1838 1839 -- If the right-hand side requires a transient scope, it has 1840 -- already been placed on the stack. However, the declaration is 1841 -- inserted in the tree outside of this scope, and must reflect 1842 -- the proper scope for its variable. This awkward bit is forced 1843 -- by the stricter scope discipline imposed by GCC 2.97. 1844 1845 declare 1846 Uses_Transient_Scope : constant Boolean := 1847 Scope_Is_Transient 1848 and then N = Node_To_Be_Wrapped; 1849 1850 begin 1851 if Uses_Transient_Scope then 1852 Push_Scope (Scope (Current_Scope)); 1853 end if; 1854 1855 Insert_Before_And_Analyze (N, 1856 Make_Object_Declaration (Loc, 1857 Defining_Identifier => Tnn, 1858 Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc), 1859 Expression => BPAR_Expr)); 1860 1861 if Uses_Transient_Scope then 1862 Pop_Scope; 1863 end if; 1864 end; 1865 1866 -- Now fix up the original assignment and continue processing 1867 1868 Rewrite (Prefix (Lhs), 1869 New_Occurrence_Of (Tnn, Loc)); 1870 1871 -- We do not need to reanalyze that assignment, and we do not need 1872 -- to worry about references to the temporary, but we do need to 1873 -- make sure that the temporary is not marked as a true constant 1874 -- since we now have a generated assignment to it. 1875 1876 Set_Is_True_Constant (Tnn, False); 1877 end; 1878 end if; 1879 1880 -- When we have the appropriate type of aggregate in the expression (it 1881 -- has been determined during analysis of the aggregate by setting the 1882 -- delay flag), let's perform in place assignment and thus avoid 1883 -- creating a temporary. 1884 1885 if Is_Delayed_Aggregate (Rhs) then 1886 Convert_Aggr_In_Assignment (N); 1887 Rewrite (N, Make_Null_Statement (Loc)); 1888 Analyze (N); 1889 1890 Ghost_Mode := Save_Ghost_Mode; 1891 return; 1892 end if; 1893 1894 -- Apply discriminant check if required. If Lhs is an access type to a 1895 -- designated type with discriminants, we must always check. If the 1896 -- type has unknown discriminants, more elaborate processing below. 1897 1898 if Has_Discriminants (Etype (Lhs)) 1899 and then not Has_Unknown_Discriminants (Etype (Lhs)) 1900 then 1901 -- Skip discriminant check if change of representation. Will be 1902 -- done when the change of representation is expanded out. 1903 1904 if not Crep then 1905 Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs); 1906 end if; 1907 1908 -- If the type is private without discriminants, and the full type 1909 -- has discriminants (necessarily with defaults) a check may still be 1910 -- necessary if the Lhs is aliased. The private discriminants must be 1911 -- visible to build the discriminant constraints. 1912 1913 -- Only an explicit dereference that comes from source indicates 1914 -- aliasing. Access to formals of protected operations and entries 1915 -- create dereferences but are not semantic aliasings. 1916 1917 elsif Is_Private_Type (Etype (Lhs)) 1918 and then Has_Discriminants (Typ) 1919 and then Nkind (Lhs) = N_Explicit_Dereference 1920 and then Comes_From_Source (Lhs) 1921 then 1922 declare 1923 Lt : constant Entity_Id := Etype (Lhs); 1924 Ubt : Entity_Id := Base_Type (Typ); 1925 1926 begin 1927 -- In the case of an expander-generated record subtype whose base 1928 -- type still appears private, Typ will have been set to that 1929 -- private type rather than the underlying record type (because 1930 -- Underlying type will have returned the record subtype), so it's 1931 -- necessary to apply Underlying_Type again to the base type to 1932 -- get the record type we need for the discriminant check. Such 1933 -- subtypes can be created for assignments in certain cases, such 1934 -- as within an instantiation passed this kind of private type. 1935 -- It would be good to avoid this special test, but making changes 1936 -- to prevent this odd form of record subtype seems difficult. ??? 1937 1938 if Is_Private_Type (Ubt) then 1939 Ubt := Underlying_Type (Ubt); 1940 end if; 1941 1942 Set_Etype (Lhs, Ubt); 1943 Rewrite (Rhs, OK_Convert_To (Base_Type (Ubt), Rhs)); 1944 Apply_Discriminant_Check (Rhs, Ubt, Lhs); 1945 Set_Etype (Lhs, Lt); 1946 end; 1947 1948 -- If the Lhs has a private type with unknown discriminants, it may 1949 -- have a full view with discriminants, but those are nameable only 1950 -- in the underlying type, so convert the Rhs to it before potential 1951 -- checking. Convert Lhs as well, otherwise the actual subtype might 1952 -- not be constructible. 1953 1954 elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs))) 1955 and then Has_Discriminants (Typ) 1956 then 1957 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs)); 1958 Rewrite (Lhs, OK_Convert_To (Base_Type (Typ), Lhs)); 1959 Apply_Discriminant_Check (Rhs, Typ, Lhs); 1960 1961 -- In the access type case, we need the same discriminant check, and 1962 -- also range checks if we have an access to constrained array. 1963 1964 elsif Is_Access_Type (Etype (Lhs)) 1965 and then Is_Constrained (Designated_Type (Etype (Lhs))) 1966 then 1967 if Has_Discriminants (Designated_Type (Etype (Lhs))) then 1968 1969 -- Skip discriminant check if change of representation. Will be 1970 -- done when the change of representation is expanded out. 1971 1972 if not Crep then 1973 Apply_Discriminant_Check (Rhs, Etype (Lhs)); 1974 end if; 1975 1976 elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then 1977 Apply_Range_Check (Rhs, Etype (Lhs)); 1978 1979 if Is_Constrained (Etype (Lhs)) then 1980 Apply_Length_Check (Rhs, Etype (Lhs)); 1981 end if; 1982 1983 if Nkind (Rhs) = N_Allocator then 1984 declare 1985 Target_Typ : constant Entity_Id := Etype (Expression (Rhs)); 1986 C_Es : Check_Result; 1987 1988 begin 1989 C_Es := 1990 Get_Range_Checks 1991 (Lhs, 1992 Target_Typ, 1993 Etype (Designated_Type (Etype (Lhs)))); 1994 1995 Insert_Range_Checks 1996 (C_Es, 1997 N, 1998 Target_Typ, 1999 Sloc (Lhs), 2000 Lhs); 2001 end; 2002 end if; 2003 end if; 2004 2005 -- Apply range check for access type case 2006 2007 elsif Is_Access_Type (Etype (Lhs)) 2008 and then Nkind (Rhs) = N_Allocator 2009 and then Nkind (Expression (Rhs)) = N_Qualified_Expression 2010 then 2011 Analyze_And_Resolve (Expression (Rhs)); 2012 Apply_Range_Check 2013 (Expression (Rhs), Designated_Type (Etype (Lhs))); 2014 end if; 2015 2016 -- Ada 2005 (AI-231): Generate the run-time check 2017 2018 if Is_Access_Type (Typ) 2019 and then Can_Never_Be_Null (Etype (Lhs)) 2020 and then not Can_Never_Be_Null (Etype (Rhs)) 2021 2022 -- If an actual is an out parameter of a null-excluding access 2023 -- type, there is access check on entry, so we set the flag 2024 -- Suppress_Assignment_Checks on the generated statement to 2025 -- assign the actual to the parameter block, and we do not want 2026 -- to generate an additional check at this point. 2027 2028 and then not Suppress_Assignment_Checks (N) 2029 then 2030 Apply_Constraint_Check (Rhs, Etype (Lhs)); 2031 end if; 2032 2033 -- Ada 2012 (AI05-148): Update current accessibility level if Rhs is a 2034 -- stand-alone obj of an anonymous access type. 2035 2036 if Is_Access_Type (Typ) 2037 and then Is_Entity_Name (Lhs) 2038 and then Present (Effective_Extra_Accessibility (Entity (Lhs))) 2039 then 2040 declare 2041 function Lhs_Entity return Entity_Id; 2042 -- Look through renames to find the underlying entity. 2043 -- For assignment to a rename, we don't care about the 2044 -- Enclosing_Dynamic_Scope of the rename declaration. 2045 2046 ---------------- 2047 -- Lhs_Entity -- 2048 ---------------- 2049 2050 function Lhs_Entity return Entity_Id is 2051 Result : Entity_Id := Entity (Lhs); 2052 2053 begin 2054 while Present (Renamed_Object (Result)) loop 2055 2056 -- Renamed_Object must return an Entity_Name here 2057 -- because of preceding "Present (E_E_A (...))" test. 2058 2059 Result := Entity (Renamed_Object (Result)); 2060 end loop; 2061 2062 return Result; 2063 end Lhs_Entity; 2064 2065 -- Local Declarations 2066 2067 Access_Check : constant Node_Id := 2068 Make_Raise_Program_Error (Loc, 2069 Condition => 2070 Make_Op_Gt (Loc, 2071 Left_Opnd => 2072 Dynamic_Accessibility_Level (Rhs), 2073 Right_Opnd => 2074 Make_Integer_Literal (Loc, 2075 Intval => 2076 Scope_Depth 2077 (Enclosing_Dynamic_Scope 2078 (Lhs_Entity)))), 2079 Reason => PE_Accessibility_Check_Failed); 2080 2081 Access_Level_Update : constant Node_Id := 2082 Make_Assignment_Statement (Loc, 2083 Name => 2084 New_Occurrence_Of 2085 (Effective_Extra_Accessibility 2086 (Entity (Lhs)), Loc), 2087 Expression => 2088 Dynamic_Accessibility_Level (Rhs)); 2089 2090 begin 2091 if not Accessibility_Checks_Suppressed (Entity (Lhs)) then 2092 Insert_Action (N, Access_Check); 2093 end if; 2094 2095 Insert_Action (N, Access_Level_Update); 2096 end; 2097 end if; 2098 2099 -- Case of assignment to a bit packed array element. If there is a 2100 -- change of representation this must be expanded into components, 2101 -- otherwise this is a bit-field assignment. 2102 2103 if Nkind (Lhs) = N_Indexed_Component 2104 and then Is_Bit_Packed_Array (Etype (Prefix (Lhs))) 2105 then 2106 -- Normal case, no change of representation 2107 2108 if not Crep then 2109 Expand_Bit_Packed_Element_Set (N); 2110 Ghost_Mode := Save_Ghost_Mode; 2111 return; 2112 2113 -- Change of representation case 2114 2115 else 2116 -- Generate the following, to force component-by-component 2117 -- assignments in an efficient way. Otherwise each component 2118 -- will require a temporary and two bit-field manipulations. 2119 2120 -- T1 : Elmt_Type; 2121 -- T1 := RhS; 2122 -- Lhs := T1; 2123 2124 declare 2125 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T'); 2126 Stats : List_Id; 2127 2128 begin 2129 Stats := 2130 New_List ( 2131 Make_Object_Declaration (Loc, 2132 Defining_Identifier => Tnn, 2133 Object_Definition => 2134 New_Occurrence_Of (Etype (Lhs), Loc)), 2135 Make_Assignment_Statement (Loc, 2136 Name => New_Occurrence_Of (Tnn, Loc), 2137 Expression => Relocate_Node (Rhs)), 2138 Make_Assignment_Statement (Loc, 2139 Name => Relocate_Node (Lhs), 2140 Expression => New_Occurrence_Of (Tnn, Loc))); 2141 2142 Insert_Actions (N, Stats); 2143 Rewrite (N, Make_Null_Statement (Loc)); 2144 Analyze (N); 2145 end; 2146 end if; 2147 2148 -- Build-in-place function call case. Note that we're not yet doing 2149 -- build-in-place for user-written assignment statements (the assignment 2150 -- here came from an aggregate.) 2151 2152 elsif Ada_Version >= Ada_2005 2153 and then Is_Build_In_Place_Function_Call (Rhs) 2154 then 2155 Make_Build_In_Place_Call_In_Assignment (N, Rhs); 2156 2157 elsif Is_Tagged_Type (Typ) 2158 or else (Needs_Finalization (Typ) and then not Is_Array_Type (Typ)) 2159 then 2160 Tagged_Case : declare 2161 L : List_Id := No_List; 2162 Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N); 2163 2164 begin 2165 -- In the controlled case, we ensure that function calls are 2166 -- evaluated before finalizing the target. In all cases, it makes 2167 -- the expansion easier if the side-effects are removed first. 2168 2169 Remove_Side_Effects (Lhs); 2170 Remove_Side_Effects (Rhs); 2171 2172 -- Avoid recursion in the mechanism 2173 2174 Set_Analyzed (N); 2175 2176 -- If dispatching assignment, we need to dispatch to _assign 2177 2178 if Is_Class_Wide_Type (Typ) 2179 2180 -- If the type is tagged, we may as well use the predefined 2181 -- primitive assignment. This avoids inlining a lot of code 2182 -- and in the class-wide case, the assignment is replaced 2183 -- by a dispatching call to _assign. It is suppressed in the 2184 -- case of assignments created by the expander that correspond 2185 -- to initializations, where we do want to copy the tag 2186 -- (Expand_Ctrl_Actions flag is set False in this case). It is 2187 -- also suppressed if restriction No_Dispatching_Calls is in 2188 -- force because in that case predefined primitives are not 2189 -- generated. 2190 2191 or else (Is_Tagged_Type (Typ) 2192 and then Chars (Current_Scope) /= Name_uAssign 2193 and then Expand_Ctrl_Actions 2194 and then 2195 not Restriction_Active (No_Dispatching_Calls)) 2196 then 2197 if Is_Limited_Type (Typ) then 2198 2199 -- This can happen in an instance when the formal is an 2200 -- extension of a limited interface, and the actual is 2201 -- limited. This is an error according to AI05-0087, but 2202 -- is not caught at the point of instantiation in earlier 2203 -- versions. 2204 2205 -- This is wrong, error messages cannot be issued during 2206 -- expansion, since they would be missed in -gnatc mode ??? 2207 2208 Error_Msg_N ("assignment not available on limited type", N); 2209 Ghost_Mode := Save_Ghost_Mode; 2210 return; 2211 end if; 2212 2213 -- Fetch the primitive op _assign and proper type to call it. 2214 -- Because of possible conflicts between private and full view, 2215 -- fetch the proper type directly from the operation profile. 2216 2217 declare 2218 Op : constant Entity_Id := 2219 Find_Prim_Op (Typ, Name_uAssign); 2220 F_Typ : Entity_Id := Etype (First_Formal (Op)); 2221 2222 begin 2223 -- If the assignment is dispatching, make sure to use the 2224 -- proper type. 2225 2226 if Is_Class_Wide_Type (Typ) then 2227 F_Typ := Class_Wide_Type (F_Typ); 2228 end if; 2229 2230 L := New_List; 2231 2232 -- In case of assignment to a class-wide tagged type, before 2233 -- the assignment we generate run-time check to ensure that 2234 -- the tags of source and target match. 2235 2236 if not Tag_Checks_Suppressed (Typ) 2237 and then Is_Class_Wide_Type (Typ) 2238 and then Is_Tagged_Type (Typ) 2239 and then Is_Tagged_Type (Underlying_Type (Etype (Rhs))) 2240 then 2241 Append_To (L, 2242 Make_Raise_Constraint_Error (Loc, 2243 Condition => 2244 Make_Op_Ne (Loc, 2245 Left_Opnd => 2246 Make_Selected_Component (Loc, 2247 Prefix => Duplicate_Subexpr (Lhs), 2248 Selector_Name => 2249 Make_Identifier (Loc, Name_uTag)), 2250 Right_Opnd => 2251 Make_Selected_Component (Loc, 2252 Prefix => Duplicate_Subexpr (Rhs), 2253 Selector_Name => 2254 Make_Identifier (Loc, Name_uTag))), 2255 Reason => CE_Tag_Check_Failed)); 2256 end if; 2257 2258 declare 2259 Left_N : Node_Id := Duplicate_Subexpr (Lhs); 2260 Right_N : Node_Id := Duplicate_Subexpr (Rhs); 2261 2262 begin 2263 -- In order to dispatch the call to _assign the type of 2264 -- the actuals must match. Add conversion (if required). 2265 2266 if Etype (Lhs) /= F_Typ then 2267 Left_N := Unchecked_Convert_To (F_Typ, Left_N); 2268 end if; 2269 2270 if Etype (Rhs) /= F_Typ then 2271 Right_N := Unchecked_Convert_To (F_Typ, Right_N); 2272 end if; 2273 2274 Append_To (L, 2275 Make_Procedure_Call_Statement (Loc, 2276 Name => New_Occurrence_Of (Op, Loc), 2277 Parameter_Associations => New_List ( 2278 Node1 => Left_N, 2279 Node2 => Right_N))); 2280 end; 2281 end; 2282 2283 else 2284 L := Make_Tag_Ctrl_Assignment (N); 2285 2286 -- We can't afford to have destructive Finalization Actions in 2287 -- the Self assignment case, so if the target and the source 2288 -- are not obviously different, code is generated to avoid the 2289 -- self assignment case: 2290 2291 -- if lhs'address /= rhs'address then 2292 -- <code for controlled and/or tagged assignment> 2293 -- end if; 2294 2295 -- Skip this if Restriction (No_Finalization) is active 2296 2297 if not Statically_Different (Lhs, Rhs) 2298 and then Expand_Ctrl_Actions 2299 and then not Restriction_Active (No_Finalization) 2300 then 2301 L := New_List ( 2302 Make_Implicit_If_Statement (N, 2303 Condition => 2304 Make_Op_Ne (Loc, 2305 Left_Opnd => 2306 Make_Attribute_Reference (Loc, 2307 Prefix => Duplicate_Subexpr (Lhs), 2308 Attribute_Name => Name_Address), 2309 2310 Right_Opnd => 2311 Make_Attribute_Reference (Loc, 2312 Prefix => Duplicate_Subexpr (Rhs), 2313 Attribute_Name => Name_Address)), 2314 2315 Then_Statements => L)); 2316 end if; 2317 2318 -- We need to set up an exception handler for implementing 2319 -- 7.6.1(18). The remaining adjustments are tackled by the 2320 -- implementation of adjust for record_controllers (see 2321 -- s-finimp.adb). 2322 2323 -- This is skipped if we have no finalization 2324 2325 if Expand_Ctrl_Actions 2326 and then not Restriction_Active (No_Finalization) 2327 then 2328 L := New_List ( 2329 Make_Block_Statement (Loc, 2330 Handled_Statement_Sequence => 2331 Make_Handled_Sequence_Of_Statements (Loc, 2332 Statements => L, 2333 Exception_Handlers => New_List ( 2334 Make_Handler_For_Ctrl_Operation (Loc))))); 2335 end if; 2336 end if; 2337 2338 Rewrite (N, 2339 Make_Block_Statement (Loc, 2340 Handled_Statement_Sequence => 2341 Make_Handled_Sequence_Of_Statements (Loc, Statements => L))); 2342 2343 -- If no restrictions on aborts, protect the whole assignment 2344 -- for controlled objects as per 9.8(11). 2345 2346 if Needs_Finalization (Typ) 2347 and then Expand_Ctrl_Actions 2348 and then Abort_Allowed 2349 then 2350 declare 2351 Blk : constant Entity_Id := 2352 New_Internal_Entity 2353 (E_Block, Current_Scope, Sloc (N), 'B'); 2354 AUD : constant Entity_Id := RTE (RE_Abort_Undefer_Direct); 2355 2356 begin 2357 Set_Scope (Blk, Current_Scope); 2358 Set_Etype (Blk, Standard_Void_Type); 2359 Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N))); 2360 2361 Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer)); 2362 Set_At_End_Proc (Handled_Statement_Sequence (N), 2363 New_Occurrence_Of (AUD, Loc)); 2364 2365 -- Present the Abort_Undefer_Direct function to the backend 2366 -- so that it can inline the call to the function. 2367 2368 Add_Inlined_Body (AUD, N); 2369 2370 Expand_At_End_Handler 2371 (Handled_Statement_Sequence (N), Blk); 2372 end; 2373 end if; 2374 2375 -- N has been rewritten to a block statement for which it is 2376 -- known by construction that no checks are necessary: analyze 2377 -- it with all checks suppressed. 2378 2379 Analyze (N, Suppress => All_Checks); 2380 Ghost_Mode := Save_Ghost_Mode; 2381 return; 2382 end Tagged_Case; 2383 2384 -- Array types 2385 2386 elsif Is_Array_Type (Typ) then 2387 declare 2388 Actual_Rhs : Node_Id := Rhs; 2389 2390 begin 2391 while Nkind_In (Actual_Rhs, N_Type_Conversion, 2392 N_Qualified_Expression) 2393 loop 2394 Actual_Rhs := Expression (Actual_Rhs); 2395 end loop; 2396 2397 Expand_Assign_Array (N, Actual_Rhs); 2398 Ghost_Mode := Save_Ghost_Mode; 2399 return; 2400 end; 2401 2402 -- Record types 2403 2404 elsif Is_Record_Type (Typ) then 2405 Expand_Assign_Record (N); 2406 Ghost_Mode := Save_Ghost_Mode; 2407 return; 2408 2409 -- Scalar types. This is where we perform the processing related to the 2410 -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid 2411 -- scalar values. 2412 2413 elsif Is_Scalar_Type (Typ) then 2414 2415 -- Case where right side is known valid 2416 2417 if Expr_Known_Valid (Rhs) then 2418 2419 -- Here the right side is valid, so it is fine. The case to deal 2420 -- with is when the left side is a local variable reference whose 2421 -- value is not currently known to be valid. If this is the case, 2422 -- and the assignment appears in an unconditional context, then 2423 -- we can mark the left side as now being valid if one of these 2424 -- conditions holds: 2425 2426 -- The expression of the right side has Do_Range_Check set so 2427 -- that we know a range check will be performed. Note that it 2428 -- can be the case that a range check is omitted because we 2429 -- make the assumption that we can assume validity for operands 2430 -- appearing in the right side in determining whether a range 2431 -- check is required 2432 2433 -- The subtype of the right side matches the subtype of the 2434 -- left side. In this case, even though we have not checked 2435 -- the range of the right side, we know it is in range of its 2436 -- subtype if the expression is valid. 2437 2438 if Is_Local_Variable_Reference (Lhs) 2439 and then not Is_Known_Valid (Entity (Lhs)) 2440 and then In_Unconditional_Context (N) 2441 then 2442 if Do_Range_Check (Rhs) 2443 or else Etype (Lhs) = Etype (Rhs) 2444 then 2445 Set_Is_Known_Valid (Entity (Lhs), True); 2446 end if; 2447 end if; 2448 2449 -- Case where right side may be invalid in the sense of the RM 2450 -- reference above. The RM does not require that we check for the 2451 -- validity on an assignment, but it does require that the assignment 2452 -- of an invalid value not cause erroneous behavior. 2453 2454 -- The general approach in GNAT is to use the Is_Known_Valid flag 2455 -- to avoid the need for validity checking on assignments. However 2456 -- in some cases, we have to do validity checking in order to make 2457 -- sure that the setting of this flag is correct. 2458 2459 else 2460 -- Validate right side if we are validating copies 2461 2462 if Validity_Checks_On 2463 and then Validity_Check_Copies 2464 then 2465 -- Skip this if left hand side is an array or record component 2466 -- and elementary component validity checks are suppressed. 2467 2468 if Nkind_In (Lhs, N_Selected_Component, N_Indexed_Component) 2469 and then not Validity_Check_Components 2470 then 2471 null; 2472 else 2473 Ensure_Valid (Rhs); 2474 end if; 2475 2476 -- We can propagate this to the left side where appropriate 2477 2478 if Is_Local_Variable_Reference (Lhs) 2479 and then not Is_Known_Valid (Entity (Lhs)) 2480 and then In_Unconditional_Context (N) 2481 then 2482 Set_Is_Known_Valid (Entity (Lhs), True); 2483 end if; 2484 2485 -- Otherwise check to see what should be done 2486 2487 -- If left side is a local variable, then we just set its flag to 2488 -- indicate that its value may no longer be valid, since we are 2489 -- copying a potentially invalid value. 2490 2491 elsif Is_Local_Variable_Reference (Lhs) then 2492 Set_Is_Known_Valid (Entity (Lhs), False); 2493 2494 -- Check for case of a nonlocal variable on the left side which 2495 -- is currently known to be valid. In this case, we simply ensure 2496 -- that the right side is valid. We only play the game of copying 2497 -- validity status for local variables, since we are doing this 2498 -- statically, not by tracing the full flow graph. 2499 2500 elsif Is_Entity_Name (Lhs) 2501 and then Is_Known_Valid (Entity (Lhs)) 2502 then 2503 -- Note: If Validity_Checking mode is set to none, we ignore 2504 -- the Ensure_Valid call so don't worry about that case here. 2505 2506 Ensure_Valid (Rhs); 2507 2508 -- In all other cases, we can safely copy an invalid value without 2509 -- worrying about the status of the left side. Since it is not a 2510 -- variable reference it will not be considered 2511 -- as being known to be valid in any case. 2512 2513 else 2514 null; 2515 end if; 2516 end if; 2517 end if; 2518 2519 Ghost_Mode := Save_Ghost_Mode; 2520 2521 exception 2522 when RE_Not_Available => 2523 Ghost_Mode := Save_Ghost_Mode; 2524 return; 2525 end Expand_N_Assignment_Statement; 2526 2527 ------------------------------ 2528 -- Expand_N_Block_Statement -- 2529 ------------------------------ 2530 2531 -- Encode entity names defined in block statement 2532 2533 procedure Expand_N_Block_Statement (N : Node_Id) is 2534 begin 2535 Qualify_Entity_Names (N); 2536 end Expand_N_Block_Statement; 2537 2538 ----------------------------- 2539 -- Expand_N_Case_Statement -- 2540 ----------------------------- 2541 2542 procedure Expand_N_Case_Statement (N : Node_Id) is 2543 Loc : constant Source_Ptr := Sloc (N); 2544 Expr : constant Node_Id := Expression (N); 2545 Alt : Node_Id; 2546 Len : Nat; 2547 Cond : Node_Id; 2548 Choice : Node_Id; 2549 Chlist : List_Id; 2550 2551 begin 2552 -- Check for the situation where we know at compile time which branch 2553 -- will be taken. 2554 2555 -- If the value is static but its subtype is predicated and the value 2556 -- does not obey the predicate, the value is marked non-static, and 2557 -- there can be no corresponding static alternative. In that case we 2558 -- replace the case statement with an exception, regardless of whether 2559 -- assertions are enabled or not. 2560 2561 if Compile_Time_Known_Value (Expr) 2562 and then Has_Predicates (Etype (Expr)) 2563 and then not Is_OK_Static_Expression (Expr) 2564 then 2565 Rewrite (N, 2566 Make_Raise_Constraint_Error (Loc, Reason => CE_Invalid_Data)); 2567 Analyze (N); 2568 return; 2569 2570 elsif Compile_Time_Known_Value (Expr) 2571 and then (not Has_Predicates (Etype (Expr)) 2572 or else Is_Static_Expression (Expr)) 2573 then 2574 Alt := Find_Static_Alternative (N); 2575 2576 -- Do not consider controlled objects found in a case statement which 2577 -- actually models a case expression because their early finalization 2578 -- will affect the result of the expression. 2579 2580 if not From_Conditional_Expression (N) then 2581 Process_Statements_For_Controlled_Objects (Alt); 2582 end if; 2583 2584 -- Move statements from this alternative after the case statement. 2585 -- They are already analyzed, so will be skipped by the analyzer. 2586 2587 Insert_List_After (N, Statements (Alt)); 2588 2589 -- That leaves the case statement as a shell. So now we can kill all 2590 -- other alternatives in the case statement. 2591 2592 Kill_Dead_Code (Expression (N)); 2593 2594 declare 2595 Dead_Alt : Node_Id; 2596 2597 begin 2598 -- Loop through case alternatives, skipping pragmas, and skipping 2599 -- the one alternative that we select (and therefore retain). 2600 2601 Dead_Alt := First (Alternatives (N)); 2602 while Present (Dead_Alt) loop 2603 if Dead_Alt /= Alt 2604 and then Nkind (Dead_Alt) = N_Case_Statement_Alternative 2605 then 2606 Kill_Dead_Code (Statements (Dead_Alt), Warn_On_Deleted_Code); 2607 end if; 2608 2609 Next (Dead_Alt); 2610 end loop; 2611 end; 2612 2613 Rewrite (N, Make_Null_Statement (Loc)); 2614 return; 2615 end if; 2616 2617 -- Here if the choice is not determined at compile time 2618 2619 declare 2620 Last_Alt : constant Node_Id := Last (Alternatives (N)); 2621 2622 Others_Present : Boolean; 2623 Others_Node : Node_Id; 2624 2625 Then_Stms : List_Id; 2626 Else_Stms : List_Id; 2627 2628 begin 2629 if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then 2630 Others_Present := True; 2631 Others_Node := Last_Alt; 2632 else 2633 Others_Present := False; 2634 end if; 2635 2636 -- First step is to worry about possible invalid argument. The RM 2637 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is 2638 -- outside the base range), then Constraint_Error must be raised. 2639 2640 -- Case of validity check required (validity checks are on, the 2641 -- expression is not known to be valid, and the case statement 2642 -- comes from source -- no need to validity check internally 2643 -- generated case statements). 2644 2645 if Validity_Check_Default then 2646 Ensure_Valid (Expr); 2647 end if; 2648 2649 -- If there is only a single alternative, just replace it with the 2650 -- sequence of statements since obviously that is what is going to 2651 -- be executed in all cases. 2652 2653 Len := List_Length (Alternatives (N)); 2654 2655 if Len = 1 then 2656 2657 -- We still need to evaluate the expression if it has any side 2658 -- effects. 2659 2660 Remove_Side_Effects (Expression (N)); 2661 Alt := First (Alternatives (N)); 2662 2663 -- Do not consider controlled objects found in a case statement 2664 -- which actually models a case expression because their early 2665 -- finalization will affect the result of the expression. 2666 2667 if not From_Conditional_Expression (N) then 2668 Process_Statements_For_Controlled_Objects (Alt); 2669 end if; 2670 2671 Insert_List_After (N, Statements (Alt)); 2672 2673 -- That leaves the case statement as a shell. The alternative that 2674 -- will be executed is reset to a null list. So now we can kill 2675 -- the entire case statement. 2676 2677 Kill_Dead_Code (Expression (N)); 2678 Rewrite (N, Make_Null_Statement (Loc)); 2679 return; 2680 2681 -- An optimization. If there are only two alternatives, and only 2682 -- a single choice, then rewrite the whole case statement as an 2683 -- if statement, since this can result in subsequent optimizations. 2684 -- This helps not only with case statements in the source of a 2685 -- simple form, but also with generated code (discriminant check 2686 -- functions in particular). 2687 2688 -- Note: it is OK to do this before expanding out choices for any 2689 -- static predicates, since the if statement processing will handle 2690 -- the static predicate case fine. 2691 2692 elsif Len = 2 then 2693 Chlist := Discrete_Choices (First (Alternatives (N))); 2694 2695 if List_Length (Chlist) = 1 then 2696 Choice := First (Chlist); 2697 2698 Then_Stms := Statements (First (Alternatives (N))); 2699 Else_Stms := Statements (Last (Alternatives (N))); 2700 2701 -- For TRUE, generate "expression", not expression = true 2702 2703 if Nkind (Choice) = N_Identifier 2704 and then Entity (Choice) = Standard_True 2705 then 2706 Cond := Expression (N); 2707 2708 -- For FALSE, generate "expression" and switch then/else 2709 2710 elsif Nkind (Choice) = N_Identifier 2711 and then Entity (Choice) = Standard_False 2712 then 2713 Cond := Expression (N); 2714 Else_Stms := Statements (First (Alternatives (N))); 2715 Then_Stms := Statements (Last (Alternatives (N))); 2716 2717 -- For a range, generate "expression in range" 2718 2719 elsif Nkind (Choice) = N_Range 2720 or else (Nkind (Choice) = N_Attribute_Reference 2721 and then Attribute_Name (Choice) = Name_Range) 2722 or else (Is_Entity_Name (Choice) 2723 and then Is_Type (Entity (Choice))) 2724 then 2725 Cond := 2726 Make_In (Loc, 2727 Left_Opnd => Expression (N), 2728 Right_Opnd => Relocate_Node (Choice)); 2729 2730 -- A subtype indication is not a legal operator in a membership 2731 -- test, so retrieve its range. 2732 2733 elsif Nkind (Choice) = N_Subtype_Indication then 2734 Cond := 2735 Make_In (Loc, 2736 Left_Opnd => Expression (N), 2737 Right_Opnd => 2738 Relocate_Node 2739 (Range_Expression (Constraint (Choice)))); 2740 2741 -- For any other subexpression "expression = value" 2742 2743 else 2744 Cond := 2745 Make_Op_Eq (Loc, 2746 Left_Opnd => Expression (N), 2747 Right_Opnd => Relocate_Node (Choice)); 2748 end if; 2749 2750 -- Now rewrite the case as an IF 2751 2752 Rewrite (N, 2753 Make_If_Statement (Loc, 2754 Condition => Cond, 2755 Then_Statements => Then_Stms, 2756 Else_Statements => Else_Stms)); 2757 Analyze (N); 2758 return; 2759 end if; 2760 end if; 2761 2762 -- If the last alternative is not an Others choice, replace it with 2763 -- an N_Others_Choice. Note that we do not bother to call Analyze on 2764 -- the modified case statement, since it's only effect would be to 2765 -- compute the contents of the Others_Discrete_Choices which is not 2766 -- needed by the back end anyway. 2767 2768 -- The reason for this is that the back end always needs some default 2769 -- for a switch, so if we have not supplied one in the processing 2770 -- above for validity checking, then we need to supply one here. 2771 2772 if not Others_Present then 2773 Others_Node := Make_Others_Choice (Sloc (Last_Alt)); 2774 Set_Others_Discrete_Choices 2775 (Others_Node, Discrete_Choices (Last_Alt)); 2776 Set_Discrete_Choices (Last_Alt, New_List (Others_Node)); 2777 end if; 2778 2779 -- Deal with possible declarations of controlled objects, and also 2780 -- with rewriting choice sequences for static predicate references. 2781 2782 Alt := First_Non_Pragma (Alternatives (N)); 2783 while Present (Alt) loop 2784 2785 -- Do not consider controlled objects found in a case statement 2786 -- which actually models a case expression because their early 2787 -- finalization will affect the result of the expression. 2788 2789 if not From_Conditional_Expression (N) then 2790 Process_Statements_For_Controlled_Objects (Alt); 2791 end if; 2792 2793 if Has_SP_Choice (Alt) then 2794 Expand_Static_Predicates_In_Choices (Alt); 2795 end if; 2796 2797 Next_Non_Pragma (Alt); 2798 end loop; 2799 end; 2800 end Expand_N_Case_Statement; 2801 2802 ----------------------------- 2803 -- Expand_N_Exit_Statement -- 2804 ----------------------------- 2805 2806 -- The only processing required is to deal with a possible C/Fortran 2807 -- boolean value used as the condition for the exit statement. 2808 2809 procedure Expand_N_Exit_Statement (N : Node_Id) is 2810 begin 2811 Adjust_Condition (Condition (N)); 2812 end Expand_N_Exit_Statement; 2813 2814 ---------------------------------- 2815 -- Expand_Formal_Container_Loop -- 2816 ---------------------------------- 2817 2818 procedure Expand_Formal_Container_Loop (N : Node_Id) is 2819 Loc : constant Source_Ptr := Sloc (N); 2820 Isc : constant Node_Id := Iteration_Scheme (N); 2821 I_Spec : constant Node_Id := Iterator_Specification (Isc); 2822 Cursor : constant Entity_Id := Defining_Identifier (I_Spec); 2823 Container : constant Node_Id := Entity (Name (I_Spec)); 2824 Stats : constant List_Id := Statements (N); 2825 2826 Advance : Node_Id; 2827 Blk_Nod : Node_Id; 2828 Init : Node_Id; 2829 New_Loop : Node_Id; 2830 2831 begin 2832 -- The expansion resembles the one for Ada containers, but the 2833 -- primitives mention the domain of iteration explicitly, and 2834 -- function First applied to the container yields a cursor directly. 2835 2836 -- Cursor : Cursor_type := First (Container); 2837 -- while Has_Element (Cursor, Container) loop 2838 -- <original loop statements> 2839 -- Cursor := Next (Container, Cursor); 2840 -- end loop; 2841 2842 Build_Formal_Container_Iteration 2843 (N, Container, Cursor, Init, Advance, New_Loop); 2844 2845 Set_Ekind (Cursor, E_Variable); 2846 Append_To (Stats, Advance); 2847 2848 -- Build block to capture declaration of cursor entity. 2849 2850 Blk_Nod := 2851 Make_Block_Statement (Loc, 2852 Declarations => New_List (Init), 2853 Handled_Statement_Sequence => 2854 Make_Handled_Sequence_Of_Statements (Loc, 2855 Statements => New_List (New_Loop))); 2856 2857 Rewrite (N, Blk_Nod); 2858 Analyze (N); 2859 end Expand_Formal_Container_Loop; 2860 2861 ------------------------------------------ 2862 -- Expand_Formal_Container_Element_Loop -- 2863 ------------------------------------------ 2864 2865 procedure Expand_Formal_Container_Element_Loop (N : Node_Id) is 2866 Loc : constant Source_Ptr := Sloc (N); 2867 Isc : constant Node_Id := Iteration_Scheme (N); 2868 I_Spec : constant Node_Id := Iterator_Specification (Isc); 2869 Element : constant Entity_Id := Defining_Identifier (I_Spec); 2870 Container : constant Node_Id := Entity (Name (I_Spec)); 2871 Container_Typ : constant Entity_Id := Base_Type (Etype (Container)); 2872 Stats : constant List_Id := Statements (N); 2873 2874 Cursor : constant Entity_Id := 2875 Make_Defining_Identifier (Loc, 2876 Chars => New_External_Name (Chars (Element), 'C')); 2877 Elmt_Decl : Node_Id; 2878 Elmt_Ref : Node_Id; 2879 2880 Element_Op : constant Entity_Id := 2881 Get_Iterable_Type_Primitive (Container_Typ, Name_Element); 2882 2883 Advance : Node_Id; 2884 Init : Node_Id; 2885 New_Loop : Node_Id; 2886 2887 begin 2888 -- For an element iterator, the Element aspect must be present, 2889 -- (this is checked during analysis) and the expansion takes the form: 2890 2891 -- Cursor : Cursor_type := First (Container); 2892 -- Elmt : Element_Type; 2893 -- while Has_Element (Cursor, Container) loop 2894 -- Elmt := Element (Container, Cursor); 2895 -- <original loop statements> 2896 -- Cursor := Next (Container, Cursor); 2897 -- end loop; 2898 2899 -- However this expansion is not legal if the element is indefinite. 2900 -- In that case we create a block to hold a variable declaration 2901 -- initialized with a call to Element, and generate: 2902 2903 -- Cursor : Cursor_type := First (Container); 2904 -- while Has_Element (Cursor, Container) loop 2905 -- declare 2906 -- Elmt : Element-Type := Element (Container, Cursor); 2907 -- begin 2908 -- <original loop statements> 2909 -- Cursor := Next (Container, Cursor); 2910 -- end; 2911 -- end loop; 2912 2913 Build_Formal_Container_Iteration 2914 (N, Container, Cursor, Init, Advance, New_Loop); 2915 Append_To (Stats, Advance); 2916 2917 Set_Ekind (Cursor, E_Variable); 2918 Insert_Action (N, Init); 2919 2920 -- Declaration for Element. 2921 2922 Elmt_Decl := 2923 Make_Object_Declaration (Loc, 2924 Defining_Identifier => Element, 2925 Object_Definition => New_Occurrence_Of (Etype (Element_Op), Loc)); 2926 2927 if not Is_Constrained (Etype (Element_Op)) then 2928 Set_Expression (Elmt_Decl, 2929 Make_Function_Call (Loc, 2930 Name => New_Occurrence_Of (Element_Op, Loc), 2931 Parameter_Associations => New_List ( 2932 New_Occurrence_Of (Container, Loc), 2933 New_Occurrence_Of (Cursor, Loc)))); 2934 2935 Set_Statements (New_Loop, 2936 New_List 2937 (Make_Block_Statement (Loc, 2938 Declarations => New_List (Elmt_Decl), 2939 Handled_Statement_Sequence => 2940 Make_Handled_Sequence_Of_Statements (Loc, 2941 Statements => Stats)))); 2942 2943 else 2944 Elmt_Ref := 2945 Make_Assignment_Statement (Loc, 2946 Name => New_Occurrence_Of (Element, Loc), 2947 Expression => 2948 Make_Function_Call (Loc, 2949 Name => New_Occurrence_Of (Element_Op, Loc), 2950 Parameter_Associations => New_List ( 2951 New_Occurrence_Of (Container, Loc), 2952 New_Occurrence_Of (Cursor, Loc)))); 2953 2954 Prepend (Elmt_Ref, Stats); 2955 2956 -- The element is assignable in the expanded code 2957 2958 Set_Assignment_OK (Name (Elmt_Ref)); 2959 2960 -- The loop is rewritten as a block, to hold the element declaration 2961 2962 New_Loop := 2963 Make_Block_Statement (Loc, 2964 Declarations => New_List (Elmt_Decl), 2965 Handled_Statement_Sequence => 2966 Make_Handled_Sequence_Of_Statements (Loc, 2967 Statements => New_List (New_Loop))); 2968 end if; 2969 2970 -- The element is only modified in expanded code, so it appears as 2971 -- unassigned to the warning machinery. We must suppress this spurious 2972 -- warning explicitly. 2973 2974 Set_Warnings_Off (Element); 2975 2976 Rewrite (N, New_Loop); 2977 2978 -- The loop parameter is declared by an object declaration, but within 2979 -- the loop we must prevent user assignments to it, so we analyze the 2980 -- declaration and reset the entity kind, before analyzing the rest of 2981 -- the loop; 2982 2983 Analyze (Elmt_Decl); 2984 Set_Ekind (Defining_Identifier (Elmt_Decl), E_Loop_Parameter); 2985 2986 Analyze (N); 2987 end Expand_Formal_Container_Element_Loop; 2988 2989 ----------------------------- 2990 -- Expand_N_Goto_Statement -- 2991 ----------------------------- 2992 2993 -- Add poll before goto if polling active 2994 2995 procedure Expand_N_Goto_Statement (N : Node_Id) is 2996 begin 2997 Generate_Poll_Call (N); 2998 end Expand_N_Goto_Statement; 2999 3000 --------------------------- 3001 -- Expand_N_If_Statement -- 3002 --------------------------- 3003 3004 -- First we deal with the case of C and Fortran convention boolean values, 3005 -- with zero/non-zero semantics. 3006 3007 -- Second, we deal with the obvious rewriting for the cases where the 3008 -- condition of the IF is known at compile time to be True or False. 3009 3010 -- Third, we remove elsif parts which have non-empty Condition_Actions and 3011 -- rewrite as independent if statements. For example: 3012 3013 -- if x then xs 3014 -- elsif y then ys 3015 -- ... 3016 -- end if; 3017 3018 -- becomes 3019 -- 3020 -- if x then xs 3021 -- else 3022 -- <<condition actions of y>> 3023 -- if y then ys 3024 -- ... 3025 -- end if; 3026 -- end if; 3027 3028 -- This rewriting is needed if at least one elsif part has a non-empty 3029 -- Condition_Actions list. We also do the same processing if there is a 3030 -- constant condition in an elsif part (in conjunction with the first 3031 -- processing step mentioned above, for the recursive call made to deal 3032 -- with the created inner if, this deals with properly optimizing the 3033 -- cases of constant elsif conditions). 3034 3035 procedure Expand_N_If_Statement (N : Node_Id) is 3036 Loc : constant Source_Ptr := Sloc (N); 3037 Hed : Node_Id; 3038 E : Node_Id; 3039 New_If : Node_Id; 3040 3041 Warn_If_Deleted : constant Boolean := 3042 Warn_On_Deleted_Code and then Comes_From_Source (N); 3043 -- Indicates whether we want warnings when we delete branches of the 3044 -- if statement based on constant condition analysis. We never want 3045 -- these warnings for expander generated code. 3046 3047 begin 3048 -- Do not consider controlled objects found in an if statement which 3049 -- actually models an if expression because their early finalization 3050 -- will affect the result of the expression. 3051 3052 if not From_Conditional_Expression (N) then 3053 Process_Statements_For_Controlled_Objects (N); 3054 end if; 3055 3056 Adjust_Condition (Condition (N)); 3057 3058 -- The following loop deals with constant conditions for the IF. We 3059 -- need a loop because as we eliminate False conditions, we grab the 3060 -- first elsif condition and use it as the primary condition. 3061 3062 while Compile_Time_Known_Value (Condition (N)) loop 3063 3064 -- If condition is True, we can simply rewrite the if statement now 3065 -- by replacing it by the series of then statements. 3066 3067 if Is_True (Expr_Value (Condition (N))) then 3068 3069 -- All the else parts can be killed 3070 3071 Kill_Dead_Code (Elsif_Parts (N), Warn_If_Deleted); 3072 Kill_Dead_Code (Else_Statements (N), Warn_If_Deleted); 3073 3074 Hed := Remove_Head (Then_Statements (N)); 3075 Insert_List_After (N, Then_Statements (N)); 3076 Rewrite (N, Hed); 3077 return; 3078 3079 -- If condition is False, then we can delete the condition and 3080 -- the Then statements 3081 3082 else 3083 -- We do not delete the condition if constant condition warnings 3084 -- are enabled, since otherwise we end up deleting the desired 3085 -- warning. Of course the backend will get rid of this True/False 3086 -- test anyway, so nothing is lost here. 3087 3088 if not Constant_Condition_Warnings then 3089 Kill_Dead_Code (Condition (N)); 3090 end if; 3091 3092 Kill_Dead_Code (Then_Statements (N), Warn_If_Deleted); 3093 3094 -- If there are no elsif statements, then we simply replace the 3095 -- entire if statement by the sequence of else statements. 3096 3097 if No (Elsif_Parts (N)) then 3098 if No (Else_Statements (N)) 3099 or else Is_Empty_List (Else_Statements (N)) 3100 then 3101 Rewrite (N, 3102 Make_Null_Statement (Sloc (N))); 3103 else 3104 Hed := Remove_Head (Else_Statements (N)); 3105 Insert_List_After (N, Else_Statements (N)); 3106 Rewrite (N, Hed); 3107 end if; 3108 3109 return; 3110 3111 -- If there are elsif statements, the first of them becomes the 3112 -- if/then section of the rebuilt if statement This is the case 3113 -- where we loop to reprocess this copied condition. 3114 3115 else 3116 Hed := Remove_Head (Elsif_Parts (N)); 3117 Insert_Actions (N, Condition_Actions (Hed)); 3118 Set_Condition (N, Condition (Hed)); 3119 Set_Then_Statements (N, Then_Statements (Hed)); 3120 3121 -- Hed might have been captured as the condition determining 3122 -- the current value for an entity. Now it is detached from 3123 -- the tree, so a Current_Value pointer in the condition might 3124 -- need to be updated. 3125 3126 Set_Current_Value_Condition (N); 3127 3128 if Is_Empty_List (Elsif_Parts (N)) then 3129 Set_Elsif_Parts (N, No_List); 3130 end if; 3131 end if; 3132 end if; 3133 end loop; 3134 3135 -- Loop through elsif parts, dealing with constant conditions and 3136 -- possible condition actions that are present. 3137 3138 if Present (Elsif_Parts (N)) then 3139 E := First (Elsif_Parts (N)); 3140 while Present (E) loop 3141 3142 -- Do not consider controlled objects found in an if statement 3143 -- which actually models an if expression because their early 3144 -- finalization will affect the result of the expression. 3145 3146 if not From_Conditional_Expression (N) then 3147 Process_Statements_For_Controlled_Objects (E); 3148 end if; 3149 3150 Adjust_Condition (Condition (E)); 3151 3152 -- If there are condition actions, then rewrite the if statement 3153 -- as indicated above. We also do the same rewrite for a True or 3154 -- False condition. The further processing of this constant 3155 -- condition is then done by the recursive call to expand the 3156 -- newly created if statement 3157 3158 if Present (Condition_Actions (E)) 3159 or else Compile_Time_Known_Value (Condition (E)) 3160 then 3161 -- Note this is not an implicit if statement, since it is part 3162 -- of an explicit if statement in the source (or of an implicit 3163 -- if statement that has already been tested). 3164 3165 New_If := 3166 Make_If_Statement (Sloc (E), 3167 Condition => Condition (E), 3168 Then_Statements => Then_Statements (E), 3169 Elsif_Parts => No_List, 3170 Else_Statements => Else_Statements (N)); 3171 3172 -- Elsif parts for new if come from remaining elsif's of parent 3173 3174 while Present (Next (E)) loop 3175 if No (Elsif_Parts (New_If)) then 3176 Set_Elsif_Parts (New_If, New_List); 3177 end if; 3178 3179 Append (Remove_Next (E), Elsif_Parts (New_If)); 3180 end loop; 3181 3182 Set_Else_Statements (N, New_List (New_If)); 3183 3184 if Present (Condition_Actions (E)) then 3185 Insert_List_Before (New_If, Condition_Actions (E)); 3186 end if; 3187 3188 Remove (E); 3189 3190 if Is_Empty_List (Elsif_Parts (N)) then 3191 Set_Elsif_Parts (N, No_List); 3192 end if; 3193 3194 Analyze (New_If); 3195 return; 3196 3197 -- No special processing for that elsif part, move to next 3198 3199 else 3200 Next (E); 3201 end if; 3202 end loop; 3203 end if; 3204 3205 -- Some more optimizations applicable if we still have an IF statement 3206 3207 if Nkind (N) /= N_If_Statement then 3208 return; 3209 end if; 3210 3211 -- Another optimization, special cases that can be simplified 3212 3213 -- if expression then 3214 -- return true; 3215 -- else 3216 -- return false; 3217 -- end if; 3218 3219 -- can be changed to: 3220 3221 -- return expression; 3222 3223 -- and 3224 3225 -- if expression then 3226 -- return false; 3227 -- else 3228 -- return true; 3229 -- end if; 3230 3231 -- can be changed to: 3232 3233 -- return not (expression); 3234 3235 -- Only do these optimizations if we are at least at -O1 level and 3236 -- do not do them if control flow optimizations are suppressed. 3237 3238 if Optimization_Level > 0 3239 and then not Opt.Suppress_Control_Flow_Optimizations 3240 then 3241 if Nkind (N) = N_If_Statement 3242 and then No (Elsif_Parts (N)) 3243 and then Present (Else_Statements (N)) 3244 and then List_Length (Then_Statements (N)) = 1 3245 and then List_Length (Else_Statements (N)) = 1 3246 then 3247 declare 3248 Then_Stm : constant Node_Id := First (Then_Statements (N)); 3249 Else_Stm : constant Node_Id := First (Else_Statements (N)); 3250 3251 begin 3252 if Nkind (Then_Stm) = N_Simple_Return_Statement 3253 and then 3254 Nkind (Else_Stm) = N_Simple_Return_Statement 3255 then 3256 declare 3257 Then_Expr : constant Node_Id := Expression (Then_Stm); 3258 Else_Expr : constant Node_Id := Expression (Else_Stm); 3259 3260 begin 3261 if Nkind (Then_Expr) = N_Identifier 3262 and then 3263 Nkind (Else_Expr) = N_Identifier 3264 then 3265 if Entity (Then_Expr) = Standard_True 3266 and then Entity (Else_Expr) = Standard_False 3267 then 3268 Rewrite (N, 3269 Make_Simple_Return_Statement (Loc, 3270 Expression => Relocate_Node (Condition (N)))); 3271 Analyze (N); 3272 return; 3273 3274 elsif Entity (Then_Expr) = Standard_False 3275 and then Entity (Else_Expr) = Standard_True 3276 then 3277 Rewrite (N, 3278 Make_Simple_Return_Statement (Loc, 3279 Expression => 3280 Make_Op_Not (Loc, 3281 Right_Opnd => 3282 Relocate_Node (Condition (N))))); 3283 Analyze (N); 3284 return; 3285 end if; 3286 end if; 3287 end; 3288 end if; 3289 end; 3290 end if; 3291 end if; 3292 end Expand_N_If_Statement; 3293 3294 -------------------------- 3295 -- Expand_Iterator_Loop -- 3296 -------------------------- 3297 3298 procedure Expand_Iterator_Loop (N : Node_Id) is 3299 Isc : constant Node_Id := Iteration_Scheme (N); 3300 I_Spec : constant Node_Id := Iterator_Specification (Isc); 3301 3302 Container : constant Node_Id := Name (I_Spec); 3303 Container_Typ : constant Entity_Id := Base_Type (Etype (Container)); 3304 3305 begin 3306 -- Processing for arrays 3307 3308 if Is_Array_Type (Container_Typ) then 3309 pragma Assert (Of_Present (I_Spec)); 3310 Expand_Iterator_Loop_Over_Array (N); 3311 3312 elsif Has_Aspect (Container_Typ, Aspect_Iterable) then 3313 if Of_Present (I_Spec) then 3314 Expand_Formal_Container_Element_Loop (N); 3315 else 3316 Expand_Formal_Container_Loop (N); 3317 end if; 3318 3319 -- Processing for containers 3320 3321 else 3322 Expand_Iterator_Loop_Over_Container 3323 (N, Isc, I_Spec, Container, Container_Typ); 3324 end if; 3325 end Expand_Iterator_Loop; 3326 3327 ------------------------------------- 3328 -- Expand_Iterator_Loop_Over_Array -- 3329 ------------------------------------- 3330 3331 procedure Expand_Iterator_Loop_Over_Array (N : Node_Id) is 3332 Isc : constant Node_Id := Iteration_Scheme (N); 3333 I_Spec : constant Node_Id := Iterator_Specification (Isc); 3334 Array_Node : constant Node_Id := Name (I_Spec); 3335 Array_Typ : constant Entity_Id := Base_Type (Etype (Array_Node)); 3336 Array_Dim : constant Pos := Number_Dimensions (Array_Typ); 3337 Id : constant Entity_Id := Defining_Identifier (I_Spec); 3338 Loc : constant Source_Ptr := Sloc (N); 3339 Stats : constant List_Id := Statements (N); 3340 Core_Loop : Node_Id; 3341 Dim1 : Int; 3342 Ind_Comp : Node_Id; 3343 Iterator : Entity_Id; 3344 3345 -- Start of processing for Expand_Iterator_Loop_Over_Array 3346 3347 begin 3348 -- for Element of Array loop 3349 3350 -- It requires an internally generated cursor to iterate over the array 3351 3352 pragma Assert (Of_Present (I_Spec)); 3353 3354 Iterator := Make_Temporary (Loc, 'C'); 3355 3356 -- Generate: 3357 -- Element : Component_Type renames Array (Iterator); 3358 -- Iterator is the index value, or a list of index values 3359 -- in the case of a multidimensional array. 3360 3361 Ind_Comp := 3362 Make_Indexed_Component (Loc, 3363 Prefix => Relocate_Node (Array_Node), 3364 Expressions => New_List (New_Occurrence_Of (Iterator, Loc))); 3365 3366 Prepend_To (Stats, 3367 Make_Object_Renaming_Declaration (Loc, 3368 Defining_Identifier => Id, 3369 Subtype_Mark => 3370 New_Occurrence_Of (Component_Type (Array_Typ), Loc), 3371 Name => Ind_Comp)); 3372 3373 -- Mark the loop variable as needing debug info, so that expansion 3374 -- of the renaming will result in Materialize_Entity getting set via 3375 -- Debug_Renaming_Declaration. (This setting is needed here because 3376 -- the setting in Freeze_Entity comes after the expansion, which is 3377 -- too late. ???) 3378 3379 Set_Debug_Info_Needed (Id); 3380 3381 -- Generate: 3382 3383 -- for Iterator in [reverse] Array'Range (Array_Dim) loop 3384 -- Element : Component_Type renames Array (Iterator); 3385 -- <original loop statements> 3386 -- end loop; 3387 3388 -- If this is an iteration over a multidimensional array, the 3389 -- innermost loop is over the last dimension in Ada, and over 3390 -- the first dimension in Fortran. 3391 3392 if Convention (Array_Typ) = Convention_Fortran then 3393 Dim1 := 1; 3394 else 3395 Dim1 := Array_Dim; 3396 end if; 3397 3398 Core_Loop := 3399 Make_Loop_Statement (Loc, 3400 Iteration_Scheme => 3401 Make_Iteration_Scheme (Loc, 3402 Loop_Parameter_Specification => 3403 Make_Loop_Parameter_Specification (Loc, 3404 Defining_Identifier => Iterator, 3405 Discrete_Subtype_Definition => 3406 Make_Attribute_Reference (Loc, 3407 Prefix => Relocate_Node (Array_Node), 3408 Attribute_Name => Name_Range, 3409 Expressions => New_List ( 3410 Make_Integer_Literal (Loc, Dim1))), 3411 Reverse_Present => Reverse_Present (I_Spec))), 3412 Statements => Stats, 3413 End_Label => Empty); 3414 3415 -- Processing for multidimensional array. The body of each loop is 3416 -- a loop over a previous dimension, going in decreasing order in Ada 3417 -- and in increasing order in Fortran. 3418 3419 if Array_Dim > 1 then 3420 for Dim in 1 .. Array_Dim - 1 loop 3421 if Convention (Array_Typ) = Convention_Fortran then 3422 Dim1 := Dim + 1; 3423 else 3424 Dim1 := Array_Dim - Dim; 3425 end if; 3426 3427 Iterator := Make_Temporary (Loc, 'C'); 3428 3429 -- Generate the dimension loops starting from the innermost one 3430 3431 -- for Iterator in [reverse] Array'Range (Array_Dim - Dim) loop 3432 -- <core loop> 3433 -- end loop; 3434 3435 Core_Loop := 3436 Make_Loop_Statement (Loc, 3437 Iteration_Scheme => 3438 Make_Iteration_Scheme (Loc, 3439 Loop_Parameter_Specification => 3440 Make_Loop_Parameter_Specification (Loc, 3441 Defining_Identifier => Iterator, 3442 Discrete_Subtype_Definition => 3443 Make_Attribute_Reference (Loc, 3444 Prefix => Relocate_Node (Array_Node), 3445 Attribute_Name => Name_Range, 3446 Expressions => New_List ( 3447 Make_Integer_Literal (Loc, Dim1))), 3448 Reverse_Present => Reverse_Present (I_Spec))), 3449 Statements => New_List (Core_Loop), 3450 End_Label => Empty); 3451 3452 -- Update the previously created object renaming declaration with 3453 -- the new iterator, by adding the index of the next loop to the 3454 -- indexed component, in the order that corresponds to the 3455 -- convention. 3456 3457 if Convention (Array_Typ) = Convention_Fortran then 3458 Append_To (Expressions (Ind_Comp), 3459 New_Occurrence_Of (Iterator, Loc)); 3460 else 3461 Prepend_To (Expressions (Ind_Comp), 3462 New_Occurrence_Of (Iterator, Loc)); 3463 end if; 3464 end loop; 3465 end if; 3466 3467 -- Inherit the loop identifier from the original loop. This ensures that 3468 -- the scope stack is consistent after the rewriting. 3469 3470 if Present (Identifier (N)) then 3471 Set_Identifier (Core_Loop, Relocate_Node (Identifier (N))); 3472 end if; 3473 3474 Rewrite (N, Core_Loop); 3475 Analyze (N); 3476 end Expand_Iterator_Loop_Over_Array; 3477 3478 ----------------------------------------- 3479 -- Expand_Iterator_Loop_Over_Container -- 3480 ----------------------------------------- 3481 3482 -- For a 'for ... in' loop, such as: 3483 3484 -- for Cursor in Iterator_Function (...) loop 3485 -- ... 3486 -- end loop; 3487 3488 -- we generate: 3489 3490 -- Iter : Iterator_Type := Iterator_Function (...); 3491 -- Cursor : Cursor_type := First (Iter); -- or Last for "reverse" 3492 -- while Has_Element (Cursor) loop 3493 -- ... 3494 -- 3495 -- Cursor := Iter.Next (Cursor); -- or Prev for "reverse" 3496 -- end loop; 3497 3498 -- For a 'for ... of' loop, such as: 3499 3500 -- for X of Container loop 3501 -- ... 3502 -- end loop; 3503 3504 -- the RM implies the generation of: 3505 3506 -- Iter : Iterator_Type := Container.Iterate; -- the Default_Iterator 3507 -- Cursor : Cursor_Type := First (Iter); -- or Last for "reverse" 3508 -- while Has_Element (Cursor) loop 3509 -- declare 3510 -- X : Element_Type renames Element (Cursor).Element.all; 3511 -- -- or Constant_Element 3512 -- begin 3513 -- ... 3514 -- end; 3515 -- Cursor := Iter.Next (Cursor); -- or Prev for "reverse" 3516 -- end loop; 3517 3518 -- In the general case, we do what the RM says. However, the operations 3519 -- Element and Iter.Next are slow, which is bad inside a loop, because they 3520 -- involve dispatching via interfaces, secondary stack manipulation, 3521 -- Busy/Lock incr/decr, and adjust/finalization/at-end handling. So for the 3522 -- predefined containers, we use an equivalent but optimized expansion. 3523 3524 -- In the optimized case, we make use of these: 3525 3526 -- procedure Next (Position : in out Cursor); -- instead of Iter.Next 3527 3528 -- function Pseudo_Reference 3529 -- (Container : aliased Vector'Class) return Reference_Control_Type; 3530 3531 -- type Element_Access is access all Element_Type; 3532 3533 -- function Get_Element_Access 3534 -- (Position : Cursor) return not null Element_Access; 3535 3536 -- Next is declared in the visible part of the container packages. 3537 -- The other three are added in the private part. (We're not supposed to 3538 -- pollute the namespace for clients. The compiler has no trouble breaking 3539 -- privacy to call things in the private part of an instance.) 3540 3541 -- Source: 3542 3543 -- for X of My_Vector loop 3544 -- X.Count := X.Count + 1; 3545 -- ... 3546 -- end loop; 3547 3548 -- The compiler will generate: 3549 3550 -- Iter : Reversible_Iterator'Class := Iterate (My_Vector); 3551 -- -- Reversible_Iterator is an interface. Iterate is the 3552 -- -- Default_Iterator aspect of Vector. This increments Lock, 3553 -- -- disallowing tampering with cursors. Unfortunately, it does not 3554 -- -- increment Busy. The result of Iterate is Limited_Controlled; 3555 -- -- finalization will decrement Lock. This is a build-in-place 3556 -- -- dispatching call to Iterate. 3557 3558 -- Cur : Cursor := First (Iter); -- or Last 3559 -- -- Dispatching call via interface. 3560 3561 -- Control : Reference_Control_Type := Pseudo_Reference (My_Vector); 3562 -- -- Pseudo_Reference increments Busy, to detect tampering with 3563 -- -- elements, as required by RM. Also redundantly increment 3564 -- -- Lock. Finalization of Control will decrement both Busy and 3565 -- -- Lock. Pseudo_Reference returns a record containing a pointer to 3566 -- -- My_Vector, used by Finalize. 3567 -- -- 3568 -- -- Control is not used below, except to finalize it -- it's purely 3569 -- -- an RAII thing. This is needed because we are eliminating the 3570 -- -- call to Reference within the loop. 3571 3572 -- while Has_Element (Cur) loop 3573 -- declare 3574 -- X : My_Element renames Get_Element_Access (Cur).all; 3575 -- -- Get_Element_Access returns a pointer to the element 3576 -- -- designated by Cur. No dispatching here, and no horsing 3577 -- -- around with access discriminants. This is instead of the 3578 -- -- existing 3579 -- -- 3580 -- -- X : My_Element renames Reference (Cur).Element.all; 3581 -- -- 3582 -- -- which creates a controlled object. 3583 -- begin 3584 -- -- Any attempt to tamper with My_Vector here in the loop 3585 -- -- will correctly raise Program_Error, because of the 3586 -- -- Control. 3587 -- 3588 -- X.Count := X.Count + 1; 3589 -- ... 3590 -- 3591 -- Next (Cur); -- or Prev 3592 -- -- This is instead of "Cur := Next (Iter, Cur);" 3593 -- end; 3594 -- -- No finalization here 3595 -- end loop; 3596 -- Finalize Iter and Control here, decrementing Lock twice and Busy 3597 -- once. 3598 3599 -- This optimization makes "for ... of" loops over 30 times faster in cases 3600 -- measured. 3601 3602 procedure Expand_Iterator_Loop_Over_Container 3603 (N : Node_Id; 3604 Isc : Node_Id; 3605 I_Spec : Node_Id; 3606 Container : Node_Id; 3607 Container_Typ : Entity_Id) 3608 is 3609 Id : constant Entity_Id := Defining_Identifier (I_Spec); 3610 Loc : constant Source_Ptr := Sloc (N); 3611 3612 I_Kind : constant Entity_Kind := Ekind (Id); 3613 Cursor : Entity_Id; 3614 Iterator : Entity_Id; 3615 New_Loop : Node_Id; 3616 Stats : constant List_Id := Statements (N); 3617 3618 Element_Type : constant Entity_Id := Etype (Id); 3619 Iter_Type : Entity_Id; 3620 Pack : Entity_Id; 3621 Decl : Node_Id; 3622 Name_Init : Name_Id; 3623 Name_Step : Name_Id; 3624 3625 Fast_Element_Access_Op, Fast_Step_Op : Entity_Id := Empty; 3626 -- Only for optimized version of "for ... of" 3627 3628 begin 3629 -- Determine the advancement and initialization steps for the cursor. 3630 -- Analysis of the expanded loop will verify that the container has a 3631 -- reverse iterator. 3632 3633 if Reverse_Present (I_Spec) then 3634 Name_Init := Name_Last; 3635 Name_Step := Name_Previous; 3636 else 3637 Name_Init := Name_First; 3638 Name_Step := Name_Next; 3639 end if; 3640 3641 -- The type of the iterator is the return type of the Iterate function 3642 -- used. For the "of" form this is the default iterator for the type, 3643 -- otherwise it is the type of the explicit function used in the 3644 -- iterator specification. The most common case will be an Iterate 3645 -- function in the container package. 3646 3647 -- The Iterator type is declared in an instance within the container 3648 -- package itself, for example: 3649 3650 -- package Vector_Iterator_Interfaces is new 3651 -- Ada.Iterator_Interfaces (Cursor, Has_Element); 3652 3653 -- If the container type is a derived type, the cursor type is found in 3654 -- the package of the ultimate ancestor type. 3655 3656 if Is_Derived_Type (Container_Typ) then 3657 Pack := Scope (Root_Type (Container_Typ)); 3658 else 3659 Pack := Scope (Container_Typ); 3660 end if; 3661 3662 Iter_Type := Etype (Name (I_Spec)); 3663 3664 if Of_Present (I_Spec) then 3665 Handle_Of : declare 3666 Container_Arg : Node_Id; 3667 3668 function Get_Default_Iterator 3669 (T : Entity_Id) return Entity_Id; 3670 -- If the container is a derived type, the aspect holds the parent 3671 -- operation. The required one is a primitive of the derived type 3672 -- and is either inherited or overridden. Also sets Container_Arg. 3673 3674 -------------------------- 3675 -- Get_Default_Iterator -- 3676 -------------------------- 3677 3678 function Get_Default_Iterator 3679 (T : Entity_Id) return Entity_Id 3680 is 3681 Iter : constant Entity_Id := 3682 Entity (Find_Value_Of_Aspect (T, Aspect_Default_Iterator)); 3683 Prim : Elmt_Id; 3684 Op : Entity_Id; 3685 3686 begin 3687 Container_Arg := New_Copy_Tree (Container); 3688 3689 -- A previous version of GNAT allowed indexing aspects to 3690 -- be redefined on derived container types, while the 3691 -- default iterator was inherited from the parent type. 3692 -- This non-standard extension is preserved temporarily for 3693 -- use by the modelling project under debug flag d.X. 3694 3695 if Debug_Flag_Dot_XX then 3696 if Base_Type (Etype (Container)) /= 3697 Base_Type (Etype (First_Formal (Iter))) 3698 then 3699 Container_Arg := 3700 Make_Type_Conversion (Loc, 3701 Subtype_Mark => 3702 New_Occurrence_Of 3703 (Etype (First_Formal (Iter)), Loc), 3704 Expression => Container_Arg); 3705 end if; 3706 3707 return Iter; 3708 3709 elsif Is_Derived_Type (T) then 3710 3711 -- The default iterator must be a primitive operation of the 3712 -- type, at the same dispatch slot position. 3713 3714 Prim := First_Elmt (Primitive_Operations (T)); 3715 while Present (Prim) loop 3716 Op := Node (Prim); 3717 3718 if Chars (Op) = Chars (Iter) 3719 and then DT_Position (Op) = DT_Position (Iter) 3720 then 3721 return Op; 3722 end if; 3723 3724 Next_Elmt (Prim); 3725 end loop; 3726 3727 -- Default iterator must exist 3728 3729 pragma Assert (False); 3730 3731 -- Otherwise not a derived type 3732 3733 else 3734 return Iter; 3735 end if; 3736 end Get_Default_Iterator; 3737 3738 Default_Iter : Entity_Id; 3739 Ent : Entity_Id; 3740 3741 Reference_Control_Type : Entity_Id := Empty; 3742 Pseudo_Reference : Entity_Id := Empty; 3743 3744 -- Start of processing for Handle_Of 3745 3746 begin 3747 if Is_Class_Wide_Type (Container_Typ) then 3748 Default_Iter := 3749 Get_Default_Iterator (Etype (Base_Type (Container_Typ))); 3750 else 3751 Default_Iter := Get_Default_Iterator (Etype (Container)); 3752 end if; 3753 3754 Cursor := Make_Temporary (Loc, 'C'); 3755 3756 -- For a container element iterator, the iterator type is obtained 3757 -- from the corresponding aspect, whose return type is descended 3758 -- from the corresponding interface type in some instance of 3759 -- Ada.Iterator_Interfaces. The actuals of that instantiation 3760 -- are Cursor and Has_Element. 3761 3762 Iter_Type := Etype (Default_Iter); 3763 3764 -- Find declarations needed for "for ... of" optimization 3765 3766 Ent := First_Entity (Pack); 3767 while Present (Ent) loop 3768 if Chars (Ent) = Name_Get_Element_Access then 3769 Fast_Element_Access_Op := Ent; 3770 3771 elsif Chars (Ent) = Name_Step 3772 and then Ekind (Ent) = E_Procedure 3773 then 3774 Fast_Step_Op := Ent; 3775 3776 elsif Chars (Ent) = Name_Reference_Control_Type then 3777 Reference_Control_Type := Ent; 3778 3779 elsif Chars (Ent) = Name_Pseudo_Reference then 3780 Pseudo_Reference := Ent; 3781 end if; 3782 3783 Next_Entity (Ent); 3784 end loop; 3785 3786 if Present (Reference_Control_Type) 3787 and then Present (Pseudo_Reference) 3788 then 3789 Insert_Action (N, 3790 Make_Object_Declaration (Loc, 3791 Defining_Identifier => Make_Temporary (Loc, 'D'), 3792 Object_Definition => 3793 New_Occurrence_Of (Reference_Control_Type, Loc), 3794 Expression => 3795 Make_Function_Call (Loc, 3796 Name => 3797 New_Occurrence_Of (Pseudo_Reference, Loc), 3798 Parameter_Associations => 3799 New_List (New_Copy_Tree (Container_Arg))))); 3800 end if; 3801 3802 -- The iterator type, which is a class-wide type, may itself be 3803 -- derived locally, so the desired instantiation is the scope of 3804 -- the root type of the iterator type. Currently, Pack is the 3805 -- container instance; this overwrites it with the iterator 3806 -- package. 3807 3808 Pack := Scope (Root_Type (Etype (Iter_Type))); 3809 3810 -- Rewrite domain of iteration as a call to the default iterator 3811 -- for the container type. 3812 3813 Rewrite (Name (I_Spec), 3814 Make_Function_Call (Loc, 3815 Name => 3816 New_Occurrence_Of (Default_Iter, Loc), 3817 Parameter_Associations => New_List (Container_Arg))); 3818 Analyze_And_Resolve (Name (I_Spec)); 3819 3820 -- Find cursor type in proper iterator package, which is an 3821 -- instantiation of Iterator_Interfaces. 3822 3823 Ent := First_Entity (Pack); 3824 while Present (Ent) loop 3825 if Chars (Ent) = Name_Cursor then 3826 Set_Etype (Cursor, Etype (Ent)); 3827 exit; 3828 end if; 3829 3830 Next_Entity (Ent); 3831 end loop; 3832 3833 if Present (Fast_Element_Access_Op) then 3834 Decl := 3835 Make_Object_Renaming_Declaration (Loc, 3836 Defining_Identifier => Id, 3837 Subtype_Mark => 3838 New_Occurrence_Of (Element_Type, Loc), 3839 Name => 3840 Make_Explicit_Dereference (Loc, 3841 Prefix => 3842 Make_Function_Call (Loc, 3843 Name => 3844 New_Occurrence_Of (Fast_Element_Access_Op, Loc), 3845 Parameter_Associations => 3846 New_List (New_Occurrence_Of (Cursor, Loc))))); 3847 3848 else 3849 Decl := 3850 Make_Object_Renaming_Declaration (Loc, 3851 Defining_Identifier => Id, 3852 Subtype_Mark => 3853 New_Occurrence_Of (Element_Type, Loc), 3854 Name => 3855 Make_Indexed_Component (Loc, 3856 Prefix => Relocate_Node (Container_Arg), 3857 Expressions => 3858 New_List (New_Occurrence_Of (Cursor, Loc)))); 3859 end if; 3860 3861 -- The defining identifier in the iterator is user-visible 3862 -- and must be visible in the debugger. 3863 3864 Set_Debug_Info_Needed (Id); 3865 3866 -- If the container does not have a variable indexing aspect, 3867 -- the element is a constant in the loop. The container itself 3868 -- may be constant, in which case the element is a constant as 3869 -- well. The container has been rewritten as a call to Iterate, 3870 -- so examine original node. 3871 3872 if No (Find_Value_Of_Aspect 3873 (Container_Typ, Aspect_Variable_Indexing)) 3874 or else not Is_Variable (Original_Node (Container)) 3875 then 3876 Set_Ekind (Id, E_Constant); 3877 end if; 3878 3879 Prepend_To (Stats, Decl); 3880 end Handle_Of; 3881 3882 -- X in Iterate (S) : type of iterator is type of explicitly 3883 -- given Iterate function, and the loop variable is the cursor. 3884 -- It will be assigned in the loop and must be a variable. 3885 3886 else 3887 Cursor := Id; 3888 end if; 3889 3890 Iterator := Make_Temporary (Loc, 'I'); 3891 3892 -- For both iterator forms, add a call to the step operation to 3893 -- advance the cursor. Generate: 3894 3895 -- Cursor := Iterator.Next (Cursor); 3896 3897 -- or else 3898 3899 -- Cursor := Next (Cursor); 3900 3901 if Present (Fast_Element_Access_Op) and then Present (Fast_Step_Op) then 3902 declare 3903 Step_Call : Node_Id; 3904 Curs_Name : constant Node_Id := New_Occurrence_Of (Cursor, Loc); 3905 begin 3906 Step_Call := 3907 Make_Procedure_Call_Statement (Loc, 3908 Name => 3909 New_Occurrence_Of (Fast_Step_Op, Loc), 3910 Parameter_Associations => New_List (Curs_Name)); 3911 3912 Append_To (Stats, Step_Call); 3913 Set_Assignment_OK (Curs_Name); 3914 end; 3915 3916 else 3917 declare 3918 Rhs : Node_Id; 3919 3920 begin 3921 Rhs := 3922 Make_Function_Call (Loc, 3923 Name => 3924 Make_Selected_Component (Loc, 3925 Prefix => New_Occurrence_Of (Iterator, Loc), 3926 Selector_Name => Make_Identifier (Loc, Name_Step)), 3927 Parameter_Associations => New_List ( 3928 New_Occurrence_Of (Cursor, Loc))); 3929 3930 Append_To (Stats, 3931 Make_Assignment_Statement (Loc, 3932 Name => New_Occurrence_Of (Cursor, Loc), 3933 Expression => Rhs)); 3934 Set_Assignment_OK (Name (Last (Stats))); 3935 end; 3936 end if; 3937 3938 -- Generate: 3939 -- while Has_Element (Cursor) loop 3940 -- <Stats> 3941 -- end loop; 3942 3943 -- Has_Element is the second actual in the iterator package 3944 3945 New_Loop := 3946 Make_Loop_Statement (Loc, 3947 Iteration_Scheme => 3948 Make_Iteration_Scheme (Loc, 3949 Condition => 3950 Make_Function_Call (Loc, 3951 Name => 3952 New_Occurrence_Of ( 3953 Next_Entity (First_Entity (Pack)), Loc), 3954 Parameter_Associations => 3955 New_List (New_Occurrence_Of (Cursor, Loc)))), 3956 3957 Statements => Stats, 3958 End_Label => Empty); 3959 3960 -- If present, preserve identifier of loop, which can be used in 3961 -- an exit statement in the body. 3962 3963 if Present (Identifier (N)) then 3964 Set_Identifier (New_Loop, Relocate_Node (Identifier (N))); 3965 end if; 3966 3967 -- Create the declarations for Iterator and cursor and insert them 3968 -- before the source loop. Given that the domain of iteration is already 3969 -- an entity, the iterator is just a renaming of that entity. Possible 3970 -- optimization ??? 3971 3972 Insert_Action (N, 3973 Make_Object_Renaming_Declaration (Loc, 3974 Defining_Identifier => Iterator, 3975 Subtype_Mark => New_Occurrence_Of (Iter_Type, Loc), 3976 Name => Relocate_Node (Name (I_Spec)))); 3977 3978 -- Create declaration for cursor 3979 3980 declare 3981 Cursor_Decl : constant Node_Id := 3982 Make_Object_Declaration (Loc, 3983 Defining_Identifier => Cursor, 3984 Object_Definition => 3985 New_Occurrence_Of (Etype (Cursor), Loc), 3986 Expression => 3987 Make_Selected_Component (Loc, 3988 Prefix => New_Occurrence_Of (Iterator, Loc), 3989 Selector_Name => 3990 Make_Identifier (Loc, Name_Init))); 3991 3992 begin 3993 -- The cursor is only modified in expanded code, so it appears 3994 -- as unassigned to the warning machinery. We must suppress this 3995 -- spurious warning explicitly. The cursor's kind is that of the 3996 -- original loop parameter (it is a constant if the domain of 3997 -- iteration is constant). 3998 3999 Set_Warnings_Off (Cursor); 4000 Set_Assignment_OK (Cursor_Decl); 4001 4002 Insert_Action (N, Cursor_Decl); 4003 Set_Ekind (Cursor, I_Kind); 4004 end; 4005 4006 -- If the range of iteration is given by a function call that returns 4007 -- a container, the finalization actions have been saved in the 4008 -- Condition_Actions of the iterator. Insert them now at the head of 4009 -- the loop. 4010 4011 if Present (Condition_Actions (Isc)) then 4012 Insert_List_Before (N, Condition_Actions (Isc)); 4013 end if; 4014 4015 Rewrite (N, New_Loop); 4016 Analyze (N); 4017 end Expand_Iterator_Loop_Over_Container; 4018 4019 ----------------------------- 4020 -- Expand_N_Loop_Statement -- 4021 ----------------------------- 4022 4023 -- 1. Remove null loop entirely 4024 -- 2. Deal with while condition for C/Fortran boolean 4025 -- 3. Deal with loops with a non-standard enumeration type range 4026 -- 4. Deal with while loops where Condition_Actions is set 4027 -- 5. Deal with loops over predicated subtypes 4028 -- 6. Deal with loops with iterators over arrays and containers 4029 -- 7. Insert polling call if required 4030 4031 procedure Expand_N_Loop_Statement (N : Node_Id) is 4032 Loc : constant Source_Ptr := Sloc (N); 4033 Scheme : constant Node_Id := Iteration_Scheme (N); 4034 Stmt : Node_Id; 4035 4036 begin 4037 -- Delete null loop 4038 4039 if Is_Null_Loop (N) then 4040 Rewrite (N, Make_Null_Statement (Loc)); 4041 return; 4042 end if; 4043 4044 -- Deal with condition for C/Fortran Boolean 4045 4046 if Present (Scheme) then 4047 Adjust_Condition (Condition (Scheme)); 4048 end if; 4049 4050 -- Generate polling call 4051 4052 if Is_Non_Empty_List (Statements (N)) then 4053 Generate_Poll_Call (First (Statements (N))); 4054 end if; 4055 4056 -- Nothing more to do for plain loop with no iteration scheme 4057 4058 if No (Scheme) then 4059 null; 4060 4061 -- Case of for loop (Loop_Parameter_Specification present) 4062 4063 -- Note: we do not have to worry about validity checking of the for loop 4064 -- range bounds here, since they were frozen with constant declarations 4065 -- and it is during that process that the validity checking is done. 4066 4067 elsif Present (Loop_Parameter_Specification (Scheme)) then 4068 declare 4069 LPS : constant Node_Id := 4070 Loop_Parameter_Specification (Scheme); 4071 Loop_Id : constant Entity_Id := Defining_Identifier (LPS); 4072 Ltype : constant Entity_Id := Etype (Loop_Id); 4073 Btype : constant Entity_Id := Base_Type (Ltype); 4074 Expr : Node_Id; 4075 Decls : List_Id; 4076 New_Id : Entity_Id; 4077 4078 begin 4079 -- Deal with loop over predicates 4080 4081 if Is_Discrete_Type (Ltype) 4082 and then Present (Predicate_Function (Ltype)) 4083 then 4084 Expand_Predicated_Loop (N); 4085 4086 -- Handle the case where we have a for loop with the range type 4087 -- being an enumeration type with non-standard representation. 4088 -- In this case we expand: 4089 4090 -- for x in [reverse] a .. b loop 4091 -- ... 4092 -- end loop; 4093 4094 -- to 4095 4096 -- for xP in [reverse] integer 4097 -- range etype'Pos (a) .. etype'Pos (b) 4098 -- loop 4099 -- declare 4100 -- x : constant etype := Pos_To_Rep (xP); 4101 -- begin 4102 -- ... 4103 -- end; 4104 -- end loop; 4105 4106 elsif Is_Enumeration_Type (Btype) 4107 and then Present (Enum_Pos_To_Rep (Btype)) 4108 then 4109 New_Id := 4110 Make_Defining_Identifier (Loc, 4111 Chars => New_External_Name (Chars (Loop_Id), 'P')); 4112 4113 -- If the type has a contiguous representation, successive 4114 -- values can be generated as offsets from the first literal. 4115 4116 if Has_Contiguous_Rep (Btype) then 4117 Expr := 4118 Unchecked_Convert_To (Btype, 4119 Make_Op_Add (Loc, 4120 Left_Opnd => 4121 Make_Integer_Literal (Loc, 4122 Enumeration_Rep (First_Literal (Btype))), 4123 Right_Opnd => New_Occurrence_Of (New_Id, Loc))); 4124 else 4125 -- Use the constructed array Enum_Pos_To_Rep 4126 4127 Expr := 4128 Make_Indexed_Component (Loc, 4129 Prefix => 4130 New_Occurrence_Of (Enum_Pos_To_Rep (Btype), Loc), 4131 Expressions => 4132 New_List (New_Occurrence_Of (New_Id, Loc))); 4133 end if; 4134 4135 -- Build declaration for loop identifier 4136 4137 Decls := 4138 New_List ( 4139 Make_Object_Declaration (Loc, 4140 Defining_Identifier => Loop_Id, 4141 Constant_Present => True, 4142 Object_Definition => New_Occurrence_Of (Ltype, Loc), 4143 Expression => Expr)); 4144 4145 Rewrite (N, 4146 Make_Loop_Statement (Loc, 4147 Identifier => Identifier (N), 4148 4149 Iteration_Scheme => 4150 Make_Iteration_Scheme (Loc, 4151 Loop_Parameter_Specification => 4152 Make_Loop_Parameter_Specification (Loc, 4153 Defining_Identifier => New_Id, 4154 Reverse_Present => Reverse_Present (LPS), 4155 4156 Discrete_Subtype_Definition => 4157 Make_Subtype_Indication (Loc, 4158 4159 Subtype_Mark => 4160 New_Occurrence_Of (Standard_Natural, Loc), 4161 4162 Constraint => 4163 Make_Range_Constraint (Loc, 4164 Range_Expression => 4165 Make_Range (Loc, 4166 4167 Low_Bound => 4168 Make_Attribute_Reference (Loc, 4169 Prefix => 4170 New_Occurrence_Of (Btype, Loc), 4171 4172 Attribute_Name => Name_Pos, 4173 4174 Expressions => New_List ( 4175 Relocate_Node 4176 (Type_Low_Bound (Ltype)))), 4177 4178 High_Bound => 4179 Make_Attribute_Reference (Loc, 4180 Prefix => 4181 New_Occurrence_Of (Btype, Loc), 4182 4183 Attribute_Name => Name_Pos, 4184 4185 Expressions => New_List ( 4186 Relocate_Node 4187 (Type_High_Bound 4188 (Ltype))))))))), 4189 4190 Statements => New_List ( 4191 Make_Block_Statement (Loc, 4192 Declarations => Decls, 4193 Handled_Statement_Sequence => 4194 Make_Handled_Sequence_Of_Statements (Loc, 4195 Statements => Statements (N)))), 4196 4197 End_Label => End_Label (N))); 4198 4199 -- The loop parameter's entity must be removed from the loop 4200 -- scope's entity list and rendered invisible, since it will 4201 -- now be located in the new block scope. Any other entities 4202 -- already associated with the loop scope, such as the loop 4203 -- parameter's subtype, will remain there. 4204 4205 -- In an element loop, the loop will contain a declaration for 4206 -- a cursor variable; otherwise the loop id is the first entity 4207 -- in the scope constructed for the loop. 4208 4209 if Comes_From_Source (Loop_Id) then 4210 pragma Assert (First_Entity (Scope (Loop_Id)) = Loop_Id); 4211 null; 4212 end if; 4213 4214 Set_First_Entity (Scope (Loop_Id), Next_Entity (Loop_Id)); 4215 Remove_Homonym (Loop_Id); 4216 4217 if Last_Entity (Scope (Loop_Id)) = Loop_Id then 4218 Set_Last_Entity (Scope (Loop_Id), Empty); 4219 end if; 4220 4221 Analyze (N); 4222 4223 -- Nothing to do with other cases of for loops 4224 4225 else 4226 null; 4227 end if; 4228 end; 4229 4230 -- Second case, if we have a while loop with Condition_Actions set, then 4231 -- we change it into a plain loop: 4232 4233 -- while C loop 4234 -- ... 4235 -- end loop; 4236 4237 -- changed to: 4238 4239 -- loop 4240 -- <<condition actions>> 4241 -- exit when not C; 4242 -- ... 4243 -- end loop 4244 4245 elsif Present (Scheme) 4246 and then Present (Condition_Actions (Scheme)) 4247 and then Present (Condition (Scheme)) 4248 then 4249 declare 4250 ES : Node_Id; 4251 4252 begin 4253 ES := 4254 Make_Exit_Statement (Sloc (Condition (Scheme)), 4255 Condition => 4256 Make_Op_Not (Sloc (Condition (Scheme)), 4257 Right_Opnd => Condition (Scheme))); 4258 4259 Prepend (ES, Statements (N)); 4260 Insert_List_Before (ES, Condition_Actions (Scheme)); 4261 4262 -- This is not an implicit loop, since it is generated in response 4263 -- to the loop statement being processed. If this is itself 4264 -- implicit, the restriction has already been checked. If not, 4265 -- it is an explicit loop. 4266 4267 Rewrite (N, 4268 Make_Loop_Statement (Sloc (N), 4269 Identifier => Identifier (N), 4270 Statements => Statements (N), 4271 End_Label => End_Label (N))); 4272 4273 Analyze (N); 4274 end; 4275 4276 -- Here to deal with iterator case 4277 4278 elsif Present (Scheme) 4279 and then Present (Iterator_Specification (Scheme)) 4280 then 4281 Expand_Iterator_Loop (N); 4282 4283 -- An iterator loop may generate renaming declarations for elements 4284 -- that require debug information. This is the case in particular 4285 -- with element iterators, where debug information must be generated 4286 -- for the temporary that holds the element value. These temporaries 4287 -- are created within a transient block whose local declarations are 4288 -- transferred to the loop, which now has nontrivial local objects. 4289 4290 if Nkind (N) = N_Loop_Statement 4291 and then Present (Identifier (N)) 4292 then 4293 Qualify_Entity_Names (N); 4294 end if; 4295 end if; 4296 4297 -- When the iteration scheme mentiones attribute 'Loop_Entry, the loop 4298 -- is transformed into a conditional block where the original loop is 4299 -- the sole statement. Inspect the statements of the nested loop for 4300 -- controlled objects. 4301 4302 Stmt := N; 4303 4304 if Subject_To_Loop_Entry_Attributes (Stmt) then 4305 Stmt := Find_Loop_In_Conditional_Block (Stmt); 4306 end if; 4307 4308 Process_Statements_For_Controlled_Objects (Stmt); 4309 end Expand_N_Loop_Statement; 4310 4311 ---------------------------- 4312 -- Expand_Predicated_Loop -- 4313 ---------------------------- 4314 4315 -- Note: the expander can handle generation of loops over predicated 4316 -- subtypes for both the dynamic and static cases. Depending on what 4317 -- we decide is allowed in Ada 2012 mode and/or extensions allowed 4318 -- mode, the semantic analyzer may disallow one or both forms. 4319 4320 procedure Expand_Predicated_Loop (N : Node_Id) is 4321 Loc : constant Source_Ptr := Sloc (N); 4322 Isc : constant Node_Id := Iteration_Scheme (N); 4323 LPS : constant Node_Id := Loop_Parameter_Specification (Isc); 4324 Loop_Id : constant Entity_Id := Defining_Identifier (LPS); 4325 Ltype : constant Entity_Id := Etype (Loop_Id); 4326 Stat : constant List_Id := Static_Discrete_Predicate (Ltype); 4327 Stmts : constant List_Id := Statements (N); 4328 4329 begin 4330 -- Case of iteration over non-static predicate, should not be possible 4331 -- since this is not allowed by the semantics and should have been 4332 -- caught during analysis of the loop statement. 4333 4334 if No (Stat) then 4335 raise Program_Error; 4336 4337 -- If the predicate list is empty, that corresponds to a predicate of 4338 -- False, in which case the loop won't run at all, and we rewrite the 4339 -- entire loop as a null statement. 4340 4341 elsif Is_Empty_List (Stat) then 4342 Rewrite (N, Make_Null_Statement (Loc)); 4343 Analyze (N); 4344 4345 -- For expansion over a static predicate we generate the following 4346 4347 -- declare 4348 -- J : Ltype := min-val; 4349 -- begin 4350 -- loop 4351 -- body 4352 -- case J is 4353 -- when endpoint => J := startpoint; 4354 -- when endpoint => J := startpoint; 4355 -- ... 4356 -- when max-val => exit; 4357 -- when others => J := Lval'Succ (J); 4358 -- end case; 4359 -- end loop; 4360 -- end; 4361 4362 -- with min-val replaced by max-val and Succ replaced by Pred if the 4363 -- loop parameter specification carries a Reverse indicator. 4364 4365 -- To make this a little clearer, let's take a specific example: 4366 4367 -- type Int is range 1 .. 10; 4368 -- subtype StaticP is Int with 4369 -- predicate => StaticP in 3 | 10 | 5 .. 7; 4370 -- ... 4371 -- for L in StaticP loop 4372 -- Put_Line ("static:" & J'Img); 4373 -- end loop; 4374 4375 -- In this case, the loop is transformed into 4376 4377 -- begin 4378 -- J : L := 3; 4379 -- loop 4380 -- body 4381 -- case J is 4382 -- when 3 => J := 5; 4383 -- when 7 => J := 10; 4384 -- when 10 => exit; 4385 -- when others => J := L'Succ (J); 4386 -- end case; 4387 -- end loop; 4388 -- end; 4389 4390 else 4391 Static_Predicate : declare 4392 S : Node_Id; 4393 D : Node_Id; 4394 P : Node_Id; 4395 Alts : List_Id; 4396 Cstm : Node_Id; 4397 4398 function Lo_Val (N : Node_Id) return Node_Id; 4399 -- Given static expression or static range, returns an identifier 4400 -- whose value is the low bound of the expression value or range. 4401 4402 function Hi_Val (N : Node_Id) return Node_Id; 4403 -- Given static expression or static range, returns an identifier 4404 -- whose value is the high bound of the expression value or range. 4405 4406 ------------ 4407 -- Hi_Val -- 4408 ------------ 4409 4410 function Hi_Val (N : Node_Id) return Node_Id is 4411 begin 4412 if Is_OK_Static_Expression (N) then 4413 return New_Copy (N); 4414 else 4415 pragma Assert (Nkind (N) = N_Range); 4416 return New_Copy (High_Bound (N)); 4417 end if; 4418 end Hi_Val; 4419 4420 ------------ 4421 -- Lo_Val -- 4422 ------------ 4423 4424 function Lo_Val (N : Node_Id) return Node_Id is 4425 begin 4426 if Is_OK_Static_Expression (N) then 4427 return New_Copy (N); 4428 else 4429 pragma Assert (Nkind (N) = N_Range); 4430 return New_Copy (Low_Bound (N)); 4431 end if; 4432 end Lo_Val; 4433 4434 -- Start of processing for Static_Predicate 4435 4436 begin 4437 -- Convert loop identifier to normal variable and reanalyze it so 4438 -- that this conversion works. We have to use the same defining 4439 -- identifier, since there may be references in the loop body. 4440 4441 Set_Analyzed (Loop_Id, False); 4442 Set_Ekind (Loop_Id, E_Variable); 4443 4444 -- In most loops the loop variable is assigned in various 4445 -- alternatives in the body. However, in the rare case when 4446 -- the range specifies a single element, the loop variable 4447 -- may trigger a spurious warning that is could be constant. 4448 -- This warning might as well be suppressed. 4449 4450 Set_Warnings_Off (Loop_Id); 4451 4452 -- Loop to create branches of case statement 4453 4454 Alts := New_List; 4455 4456 if Reverse_Present (LPS) then 4457 4458 -- Initial value is largest value in predicate. 4459 4460 D := 4461 Make_Object_Declaration (Loc, 4462 Defining_Identifier => Loop_Id, 4463 Object_Definition => New_Occurrence_Of (Ltype, Loc), 4464 Expression => Hi_Val (Last (Stat))); 4465 4466 P := Last (Stat); 4467 while Present (P) loop 4468 if No (Prev (P)) then 4469 S := Make_Exit_Statement (Loc); 4470 else 4471 S := 4472 Make_Assignment_Statement (Loc, 4473 Name => New_Occurrence_Of (Loop_Id, Loc), 4474 Expression => Hi_Val (Prev (P))); 4475 Set_Suppress_Assignment_Checks (S); 4476 end if; 4477 4478 Append_To (Alts, 4479 Make_Case_Statement_Alternative (Loc, 4480 Statements => New_List (S), 4481 Discrete_Choices => New_List (Lo_Val (P)))); 4482 4483 Prev (P); 4484 end loop; 4485 4486 else 4487 4488 -- Initial value is smallest value in predicate. 4489 4490 D := 4491 Make_Object_Declaration (Loc, 4492 Defining_Identifier => Loop_Id, 4493 Object_Definition => New_Occurrence_Of (Ltype, Loc), 4494 Expression => Lo_Val (First (Stat))); 4495 4496 P := First (Stat); 4497 while Present (P) loop 4498 if No (Next (P)) then 4499 S := Make_Exit_Statement (Loc); 4500 else 4501 S := 4502 Make_Assignment_Statement (Loc, 4503 Name => New_Occurrence_Of (Loop_Id, Loc), 4504 Expression => Lo_Val (Next (P))); 4505 Set_Suppress_Assignment_Checks (S); 4506 end if; 4507 4508 Append_To (Alts, 4509 Make_Case_Statement_Alternative (Loc, 4510 Statements => New_List (S), 4511 Discrete_Choices => New_List (Hi_Val (P)))); 4512 4513 Next (P); 4514 end loop; 4515 end if; 4516 4517 -- Add others choice 4518 4519 declare 4520 Name_Next : Name_Id; 4521 4522 begin 4523 if Reverse_Present (LPS) then 4524 Name_Next := Name_Pred; 4525 else 4526 Name_Next := Name_Succ; 4527 end if; 4528 4529 S := 4530 Make_Assignment_Statement (Loc, 4531 Name => New_Occurrence_Of (Loop_Id, Loc), 4532 Expression => 4533 Make_Attribute_Reference (Loc, 4534 Prefix => New_Occurrence_Of (Ltype, Loc), 4535 Attribute_Name => Name_Next, 4536 Expressions => New_List ( 4537 New_Occurrence_Of (Loop_Id, Loc)))); 4538 Set_Suppress_Assignment_Checks (S); 4539 end; 4540 4541 Append_To (Alts, 4542 Make_Case_Statement_Alternative (Loc, 4543 Discrete_Choices => New_List (Make_Others_Choice (Loc)), 4544 Statements => New_List (S))); 4545 4546 -- Construct case statement and append to body statements 4547 4548 Cstm := 4549 Make_Case_Statement (Loc, 4550 Expression => New_Occurrence_Of (Loop_Id, Loc), 4551 Alternatives => Alts); 4552 Append_To (Stmts, Cstm); 4553 4554 -- Rewrite the loop 4555 4556 Set_Suppress_Assignment_Checks (D); 4557 4558 Rewrite (N, 4559 Make_Block_Statement (Loc, 4560 Declarations => New_List (D), 4561 Handled_Statement_Sequence => 4562 Make_Handled_Sequence_Of_Statements (Loc, 4563 Statements => New_List ( 4564 Make_Loop_Statement (Loc, 4565 Statements => Stmts, 4566 End_Label => Empty))))); 4567 4568 Analyze (N); 4569 end Static_Predicate; 4570 end if; 4571 end Expand_Predicated_Loop; 4572 4573 ------------------------------ 4574 -- Make_Tag_Ctrl_Assignment -- 4575 ------------------------------ 4576 4577 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is 4578 Asn : constant Node_Id := Relocate_Node (N); 4579 L : constant Node_Id := Name (N); 4580 Loc : constant Source_Ptr := Sloc (N); 4581 Res : constant List_Id := New_List; 4582 T : constant Entity_Id := Underlying_Type (Etype (L)); 4583 4584 Comp_Asn : constant Boolean := Is_Fully_Repped_Tagged_Type (T); 4585 Ctrl_Act : constant Boolean := Needs_Finalization (T) 4586 and then not No_Ctrl_Actions (N); 4587 Save_Tag : constant Boolean := Is_Tagged_Type (T) 4588 and then not Comp_Asn 4589 and then not No_Ctrl_Actions (N) 4590 and then Tagged_Type_Expansion; 4591 Tag_Id : Entity_Id; 4592 4593 begin 4594 -- Finalize the target of the assignment when controlled 4595 4596 -- We have two exceptions here: 4597 4598 -- 1. If we are in an init proc since it is an initialization more 4599 -- than an assignment. 4600 4601 -- 2. If the left-hand side is a temporary that was not initialized 4602 -- (or the parent part of a temporary since it is the case in 4603 -- extension aggregates). Such a temporary does not come from 4604 -- source. We must examine the original node for the prefix, because 4605 -- it may be a component of an entry formal, in which case it has 4606 -- been rewritten and does not appear to come from source either. 4607 4608 -- Case of init proc 4609 4610 if not Ctrl_Act then 4611 null; 4612 4613 -- The left hand side is an uninitialized temporary object 4614 4615 elsif Nkind (L) = N_Type_Conversion 4616 and then Is_Entity_Name (Expression (L)) 4617 and then Nkind (Parent (Entity (Expression (L)))) = 4618 N_Object_Declaration 4619 and then No_Initialization (Parent (Entity (Expression (L)))) 4620 then 4621 null; 4622 4623 else 4624 Append_To (Res, 4625 Make_Final_Call 4626 (Obj_Ref => Duplicate_Subexpr_No_Checks (L), 4627 Typ => Etype (L))); 4628 end if; 4629 4630 -- Save the Tag in a local variable Tag_Id 4631 4632 if Save_Tag then 4633 Tag_Id := Make_Temporary (Loc, 'A'); 4634 4635 Append_To (Res, 4636 Make_Object_Declaration (Loc, 4637 Defining_Identifier => Tag_Id, 4638 Object_Definition => New_Occurrence_Of (RTE (RE_Tag), Loc), 4639 Expression => 4640 Make_Selected_Component (Loc, 4641 Prefix => Duplicate_Subexpr_No_Checks (L), 4642 Selector_Name => 4643 New_Occurrence_Of (First_Tag_Component (T), Loc)))); 4644 4645 -- Otherwise Tag_Id is not used 4646 4647 else 4648 Tag_Id := Empty; 4649 end if; 4650 4651 -- If the tagged type has a full rep clause, expand the assignment into 4652 -- component-wise assignments. Mark the node as unanalyzed in order to 4653 -- generate the proper code and propagate this scenario by setting a 4654 -- flag to avoid infinite recursion. 4655 4656 if Comp_Asn then 4657 Set_Analyzed (Asn, False); 4658 Set_Componentwise_Assignment (Asn, True); 4659 end if; 4660 4661 Append_To (Res, Asn); 4662 4663 -- Restore the tag 4664 4665 if Save_Tag then 4666 Append_To (Res, 4667 Make_Assignment_Statement (Loc, 4668 Name => 4669 Make_Selected_Component (Loc, 4670 Prefix => Duplicate_Subexpr_No_Checks (L), 4671 Selector_Name => 4672 New_Occurrence_Of (First_Tag_Component (T), Loc)), 4673 Expression => New_Occurrence_Of (Tag_Id, Loc))); 4674 end if; 4675 4676 -- Adjust the target after the assignment when controlled (not in the 4677 -- init proc since it is an initialization more than an assignment). 4678 4679 if Ctrl_Act then 4680 Append_To (Res, 4681 Make_Adjust_Call 4682 (Obj_Ref => Duplicate_Subexpr_Move_Checks (L), 4683 Typ => Etype (L))); 4684 end if; 4685 4686 return Res; 4687 4688 exception 4689 4690 -- Could use comment here ??? 4691 4692 when RE_Not_Available => 4693 return Empty_List; 4694 end Make_Tag_Ctrl_Assignment; 4695 4696end Exp_Ch5; 4697