1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- E X P _ C H 5 -- 6-- -- 7-- B o d y -- 8-- -- 9-- Copyright (C) 1992-2019, Free Software Foundation, Inc. -- 10-- -- 11-- GNAT is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 3, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- 17-- for more details. You should have received a copy of the GNU General -- 18-- Public License distributed with GNAT; see file COPYING3. If not, go to -- 19-- http://www.gnu.org/licenses for a complete copy of the license. -- 20-- -- 21-- GNAT was originally developed by the GNAT team at New York University. -- 22-- Extensive contributions were provided by Ada Core Technologies Inc. -- 23-- -- 24------------------------------------------------------------------------------ 25 26with 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 Inline; use Inline; 42with Namet; use Namet; 43with Nlists; use Nlists; 44with Nmake; use Nmake; 45with Opt; use Opt; 46with Restrict; use Restrict; 47with Rident; use Rident; 48with Rtsfind; use Rtsfind; 49with Sinfo; use Sinfo; 50with Sem; use Sem; 51with Sem_Aux; use Sem_Aux; 52with Sem_Ch3; use Sem_Ch3; 53with Sem_Ch8; use Sem_Ch8; 54with Sem_Ch13; use Sem_Ch13; 55with Sem_Eval; use Sem_Eval; 56with Sem_Res; use Sem_Res; 57with Sem_Util; use Sem_Util; 58with Snames; use Snames; 59with Stand; use Stand; 60with Stringt; use Stringt; 61with Tbuild; use Tbuild; 62with Uintp; use Uintp; 63with Validsw; use Validsw; 64 65package body Exp_Ch5 is 66 67 procedure Build_Formal_Container_Iteration 68 (N : Node_Id; 69 Container : Entity_Id; 70 Cursor : Entity_Id; 71 Init : out Node_Id; 72 Advance : out Node_Id; 73 New_Loop : out Node_Id); 74 -- Utility to create declarations and loop statement for both forms 75 -- of formal container iterators. 76 77 function Convert_To_Iterable_Type 78 (Container : Entity_Id; 79 Loc : Source_Ptr) return Node_Id; 80 -- Returns New_Occurrence_Of (Container), possibly converted to an ancestor 81 -- type, if the type of Container inherited the Iterable aspect from that 82 -- ancestor. 83 84 function Change_Of_Representation (N : Node_Id) return Boolean; 85 -- Determine if the right-hand side of assignment N is a type conversion 86 -- which requires a change of representation. Called only for the array 87 -- and record cases. 88 89 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id); 90 -- N is an assignment which assigns an array value. This routine process 91 -- the various special cases and checks required for such assignments, 92 -- including change of representation. Rhs is normally simply the right- 93 -- hand side of the assignment, except that if the right-hand side is a 94 -- type conversion or a qualified expression, then the RHS is the actual 95 -- expression inside any such type conversions or qualifications. 96 97 function Expand_Assign_Array_Loop 98 (N : Node_Id; 99 Larray : Entity_Id; 100 Rarray : Entity_Id; 101 L_Type : Entity_Id; 102 R_Type : Entity_Id; 103 Ndim : Pos; 104 Rev : Boolean) return Node_Id; 105 -- N is an assignment statement which assigns an array value. This routine 106 -- expands the assignment into a loop (or nested loops for the case of a 107 -- multi-dimensional array) to do the assignment component by component. 108 -- Larray and Rarray are the entities of the actual arrays on the left-hand 109 -- and right-hand sides. L_Type and R_Type are the types of these arrays 110 -- (which may not be the same, due to either sliding, or to a change of 111 -- representation case). Ndim is the number of dimensions and the parameter 112 -- Rev indicates if the loops run normally (Rev = False), or reversed 113 -- (Rev = True). The value returned is the constructed loop statement. 114 -- Auxiliary declarations are inserted before node N using the standard 115 -- Insert_Actions mechanism. 116 117 function Expand_Assign_Array_Bitfield 118 (N : Node_Id; 119 Larray : Entity_Id; 120 Rarray : Entity_Id; 121 L_Type : Entity_Id; 122 R_Type : Entity_Id; 123 Rev : Boolean) return Node_Id; 124 -- Alternative to Expand_Assign_Array_Loop for packed bitfields. Generates 125 -- a call to the System.Bitfields.Copy_Bitfield, which is more efficient 126 -- than copying component-by-component. 127 128 function Expand_Assign_Array_Loop_Or_Bitfield 129 (N : Node_Id; 130 Larray : Entity_Id; 131 Rarray : Entity_Id; 132 L_Type : Entity_Id; 133 R_Type : Entity_Id; 134 Ndim : Pos; 135 Rev : Boolean) return Node_Id; 136 -- Calls either Expand_Assign_Array_Loop or Expand_Assign_Array_Bitfield as 137 -- appropriate. 138 139 procedure Expand_Assign_Record (N : Node_Id); 140 -- N is an assignment of an untagged record value. This routine handles 141 -- the case where the assignment must be made component by component, 142 -- either because the target is not byte aligned, or there is a change 143 -- of representation, or when we have a tagged type with a representation 144 -- clause (this last case is required because holes in the tagged type 145 -- might be filled with components from child types). 146 147 procedure Expand_Assign_With_Target_Names (N : Node_Id); 148 -- (AI12-0125): N is an assignment statement whose RHS contains occurrences 149 -- of @ that designate the value of the LHS of the assignment. If the LHS 150 -- is side-effect free the target names can be replaced with a copy of the 151 -- LHS; otherwise the semantics of the assignment is described in terms of 152 -- a procedure with an in-out parameter, and expanded as such. 153 154 procedure Expand_Formal_Container_Loop (N : Node_Id); 155 -- Use the primitives specified in an Iterable aspect to expand a loop 156 -- over a so-called formal container, primarily for SPARK usage. 157 158 procedure Expand_Formal_Container_Element_Loop (N : Node_Id); 159 -- Same, for an iterator of the form " For E of C". In this case the 160 -- iterator provides the name of the element, and the cursor is generated 161 -- internally. 162 163 procedure Expand_Iterator_Loop (N : Node_Id); 164 -- Expand loop over arrays and containers that uses the form "for X of C" 165 -- with an optional subtype mark, or "for Y in C". 166 167 procedure Expand_Iterator_Loop_Over_Container 168 (N : Node_Id; 169 Isc : Node_Id; 170 I_Spec : Node_Id; 171 Container : Node_Id; 172 Container_Typ : Entity_Id); 173 -- Expand loop over containers that uses the form "for X of C" with an 174 -- optional subtype mark, or "for Y in C". Isc is the iteration scheme. 175 -- I_Spec is the iterator specification and Container is either the 176 -- Container (for OF) or the iterator (for IN). 177 178 procedure Expand_Predicated_Loop (N : Node_Id); 179 -- Expand for loop over predicated subtype 180 181 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id; 182 -- Generate the necessary code for controlled and tagged assignment, that 183 -- is to say, finalization of the target before, adjustment of the target 184 -- after and save and restore of the tag and finalization pointers which 185 -- are not 'part of the value' and must not be changed upon assignment. N 186 -- is the original Assignment node. 187 188 -------------------------------------- 189 -- Build_Formal_Container_Iteration -- 190 -------------------------------------- 191 192 procedure Build_Formal_Container_Iteration 193 (N : Node_Id; 194 Container : Entity_Id; 195 Cursor : Entity_Id; 196 Init : out Node_Id; 197 Advance : out Node_Id; 198 New_Loop : out Node_Id) 199 is 200 Loc : constant Source_Ptr := Sloc (N); 201 Stats : constant List_Id := Statements (N); 202 Typ : constant Entity_Id := Base_Type (Etype (Container)); 203 204 Has_Element_Op : constant Entity_Id := 205 Get_Iterable_Type_Primitive (Typ, Name_Has_Element); 206 207 First_Op : Entity_Id; 208 Next_Op : Entity_Id; 209 210 begin 211 -- Use the proper set of primitives depending on the direction of 212 -- iteration. The legality of a reverse iteration has been checked 213 -- during analysis. 214 215 if Reverse_Present (Iterator_Specification (Iteration_Scheme (N))) then 216 First_Op := Get_Iterable_Type_Primitive (Typ, Name_Last); 217 Next_Op := Get_Iterable_Type_Primitive (Typ, Name_Previous); 218 219 else 220 First_Op := Get_Iterable_Type_Primitive (Typ, Name_First); 221 Next_Op := Get_Iterable_Type_Primitive (Typ, Name_Next); 222 end if; 223 224 -- Declaration for Cursor 225 226 Init := 227 Make_Object_Declaration (Loc, 228 Defining_Identifier => Cursor, 229 Object_Definition => New_Occurrence_Of (Etype (First_Op), Loc), 230 Expression => 231 Make_Function_Call (Loc, 232 Name => New_Occurrence_Of (First_Op, Loc), 233 Parameter_Associations => New_List ( 234 Convert_To_Iterable_Type (Container, Loc)))); 235 236 -- Statement that advances (in the right direction) cursor in loop 237 238 Advance := 239 Make_Assignment_Statement (Loc, 240 Name => New_Occurrence_Of (Cursor, Loc), 241 Expression => 242 Make_Function_Call (Loc, 243 Name => New_Occurrence_Of (Next_Op, Loc), 244 Parameter_Associations => New_List ( 245 Convert_To_Iterable_Type (Container, Loc), 246 New_Occurrence_Of (Cursor, Loc)))); 247 248 -- Iterator is rewritten as a while_loop 249 250 New_Loop := 251 Make_Loop_Statement (Loc, 252 Iteration_Scheme => 253 Make_Iteration_Scheme (Loc, 254 Condition => 255 Make_Function_Call (Loc, 256 Name => New_Occurrence_Of (Has_Element_Op, Loc), 257 Parameter_Associations => New_List ( 258 Convert_To_Iterable_Type (Container, Loc), 259 New_Occurrence_Of (Cursor, Loc)))), 260 Statements => Stats, 261 End_Label => Empty); 262 263 -- If the contruct has a specified loop name, preserve it in the new 264 -- loop, for possible use in exit statements. 265 266 if Present (Identifier (N)) 267 and then Comes_From_Source (Identifier (N)) 268 then 269 Set_Identifier (New_Loop, Identifier (N)); 270 end if; 271 end Build_Formal_Container_Iteration; 272 273 ------------------------------ 274 -- Change_Of_Representation -- 275 ------------------------------ 276 277 function Change_Of_Representation (N : Node_Id) return Boolean is 278 Rhs : constant Node_Id := Expression (N); 279 begin 280 return 281 Nkind (Rhs) = N_Type_Conversion 282 and then 283 not Same_Representation (Etype (Rhs), Etype (Expression (Rhs))); 284 end Change_Of_Representation; 285 286 ------------------------------ 287 -- Convert_To_Iterable_Type -- 288 ------------------------------ 289 290 function Convert_To_Iterable_Type 291 (Container : Entity_Id; 292 Loc : Source_Ptr) return Node_Id 293 is 294 Typ : constant Entity_Id := Base_Type (Etype (Container)); 295 Aspect : constant Node_Id := Find_Aspect (Typ, Aspect_Iterable); 296 Result : Node_Id; 297 298 begin 299 Result := New_Occurrence_Of (Container, Loc); 300 301 if Entity (Aspect) /= Typ then 302 Result := 303 Make_Type_Conversion (Loc, 304 Subtype_Mark => New_Occurrence_Of (Entity (Aspect), Loc), 305 Expression => Result); 306 end if; 307 308 return Result; 309 end Convert_To_Iterable_Type; 310 311 ------------------------- 312 -- Expand_Assign_Array -- 313 ------------------------- 314 315 -- There are two issues here. First, do we let Gigi do a block move, or 316 -- do we expand out into a loop? Second, we need to set the two flags 317 -- Forwards_OK and Backwards_OK which show whether the block move (or 318 -- corresponding loops) can be legitimately done in a forwards (low to 319 -- high) or backwards (high to low) manner. 320 321 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is 322 Loc : constant Source_Ptr := Sloc (N); 323 324 Lhs : constant Node_Id := Name (N); 325 326 Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs); 327 Act_Rhs : Node_Id := Get_Referenced_Object (Rhs); 328 329 L_Type : constant Entity_Id := 330 Underlying_Type (Get_Actual_Subtype (Act_Lhs)); 331 R_Type : Entity_Id := 332 Underlying_Type (Get_Actual_Subtype (Act_Rhs)); 333 334 L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice; 335 R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice; 336 337 Crep : constant Boolean := Change_Of_Representation (N); 338 339 pragma Assert 340 (Crep 341 or else Is_Bit_Packed_Array (L_Type) = Is_Bit_Packed_Array (R_Type)); 342 343 Larray : Node_Id; 344 Rarray : Node_Id; 345 346 Ndim : constant Pos := Number_Dimensions (L_Type); 347 348 Loop_Required : Boolean := False; 349 -- This switch is set to True if the array move must be done using 350 -- an explicit front end generated loop. 351 352 procedure Apply_Dereference (Arg : Node_Id); 353 -- If the argument is an access to an array, and the assignment is 354 -- converted into a procedure call, apply explicit dereference. 355 356 function Has_Address_Clause (Exp : Node_Id) return Boolean; 357 -- Test if Exp is a reference to an array whose declaration has 358 -- an address clause, or it is a slice of such an array. 359 360 function Is_Formal_Array (Exp : Node_Id) return Boolean; 361 -- Test if Exp is a reference to an array which is either a formal 362 -- parameter or a slice of a formal parameter. These are the cases 363 -- where hidden aliasing can occur. 364 365 function Is_Non_Local_Array (Exp : Node_Id) return Boolean; 366 -- Determine if Exp is a reference to an array variable which is other 367 -- than an object defined in the current scope, or a component or a 368 -- slice of such an object. Such objects can be aliased to parameters 369 -- (unlike local array references). 370 371 ----------------------- 372 -- Apply_Dereference -- 373 ----------------------- 374 375 procedure Apply_Dereference (Arg : Node_Id) is 376 Typ : constant Entity_Id := Etype (Arg); 377 begin 378 if Is_Access_Type (Typ) then 379 Rewrite (Arg, Make_Explicit_Dereference (Loc, 380 Prefix => Relocate_Node (Arg))); 381 Analyze_And_Resolve (Arg, Designated_Type (Typ)); 382 end if; 383 end Apply_Dereference; 384 385 ------------------------ 386 -- Has_Address_Clause -- 387 ------------------------ 388 389 function Has_Address_Clause (Exp : Node_Id) return Boolean is 390 begin 391 return 392 (Is_Entity_Name (Exp) and then 393 Present (Address_Clause (Entity (Exp)))) 394 or else 395 (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp))); 396 end Has_Address_Clause; 397 398 --------------------- 399 -- Is_Formal_Array -- 400 --------------------- 401 402 function Is_Formal_Array (Exp : Node_Id) return Boolean is 403 begin 404 return 405 (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp))) 406 or else 407 (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp))); 408 end Is_Formal_Array; 409 410 ------------------------ 411 -- Is_Non_Local_Array -- 412 ------------------------ 413 414 function Is_Non_Local_Array (Exp : Node_Id) return Boolean is 415 begin 416 case Nkind (Exp) is 417 when N_Indexed_Component 418 | N_Selected_Component 419 | N_Slice 420 => 421 return Is_Non_Local_Array (Prefix (Exp)); 422 423 when others => 424 return 425 not (Is_Entity_Name (Exp) 426 and then Scope (Entity (Exp)) = Current_Scope); 427 end case; 428 end Is_Non_Local_Array; 429 430 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays 431 432 Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs); 433 Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs); 434 435 Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs); 436 Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs); 437 438 -- Start of processing for Expand_Assign_Array 439 440 begin 441 -- Deal with length check. Note that the length check is done with 442 -- respect to the right-hand side as given, not a possible underlying 443 -- renamed object, since this would generate incorrect extra checks. 444 445 Apply_Length_Check (Rhs, L_Type); 446 447 -- We start by assuming that the move can be done in either direction, 448 -- i.e. that the two sides are completely disjoint. 449 450 Set_Forwards_OK (N, True); 451 Set_Backwards_OK (N, True); 452 453 -- Normally it is only the slice case that can lead to overlap, and 454 -- explicit checks for slices are made below. But there is one case 455 -- where the slice can be implicit and invisible to us: when we have a 456 -- one dimensional array, and either both operands are parameters, or 457 -- one is a parameter (which can be a slice passed by reference) and the 458 -- other is a non-local variable. In this case the parameter could be a 459 -- slice that overlaps with the other operand. 460 461 -- However, if the array subtype is a constrained first subtype in the 462 -- parameter case, then we don't have to worry about overlap, since 463 -- slice assignments aren't possible (other than for a slice denoting 464 -- the whole array). 465 466 -- Note: No overlap is possible if there is a change of representation, 467 -- so we can exclude this case. 468 469 if Ndim = 1 470 and then not Crep 471 and then 472 ((Lhs_Formal and Rhs_Formal) 473 or else 474 (Lhs_Formal and Rhs_Non_Local_Var) 475 or else 476 (Rhs_Formal and Lhs_Non_Local_Var)) 477 and then 478 (not Is_Constrained (Etype (Lhs)) 479 or else not Is_First_Subtype (Etype (Lhs))) 480 then 481 Set_Forwards_OK (N, False); 482 Set_Backwards_OK (N, False); 483 484 -- Note: the bit-packed case is not worrisome here, since if we have 485 -- a slice passed as a parameter, it is always aligned on a byte 486 -- boundary, and if there are no explicit slices, the assignment 487 -- can be performed directly. 488 end if; 489 490 -- If either operand has an address clause clear Backwards_OK and 491 -- Forwards_OK, since we cannot tell if the operands overlap. We 492 -- exclude this treatment when Rhs is an aggregate, since we know 493 -- that overlap can't occur. 494 495 if (Has_Address_Clause (Lhs) and then Nkind (Rhs) /= N_Aggregate) 496 or else Has_Address_Clause (Rhs) 497 then 498 Set_Forwards_OK (N, False); 499 Set_Backwards_OK (N, False); 500 end if; 501 502 -- We certainly must use a loop for change of representation and also 503 -- we use the operand of the conversion on the right-hand side as the 504 -- effective right-hand side (the component types must match in this 505 -- situation). 506 507 if Crep then 508 Act_Rhs := Get_Referenced_Object (Rhs); 509 R_Type := Get_Actual_Subtype (Act_Rhs); 510 Loop_Required := True; 511 512 -- We require a loop if the left side is possibly bit unaligned 513 514 elsif Possible_Bit_Aligned_Component (Lhs) 515 or else 516 Possible_Bit_Aligned_Component (Rhs) 517 then 518 Loop_Required := True; 519 520 -- Arrays with controlled components are expanded into a loop to force 521 -- calls to Adjust at the component level. 522 523 elsif Has_Controlled_Component (L_Type) then 524 Loop_Required := True; 525 526 -- If object is atomic/VFA, we cannot tolerate a loop 527 528 elsif Is_Atomic_Or_VFA_Object (Act_Lhs) 529 or else 530 Is_Atomic_Or_VFA_Object (Act_Rhs) 531 then 532 return; 533 534 -- Loop is required if we have atomic components since we have to 535 -- be sure to do any accesses on an element by element basis. 536 537 elsif Has_Atomic_Components (L_Type) 538 or else Has_Atomic_Components (R_Type) 539 or else Is_Atomic_Or_VFA (Component_Type (L_Type)) 540 or else Is_Atomic_Or_VFA (Component_Type (R_Type)) 541 then 542 Loop_Required := True; 543 544 -- Case where no slice is involved 545 546 elsif not L_Slice and not R_Slice then 547 548 -- The following code deals with the case of unconstrained bit packed 549 -- arrays. The problem is that the template for such arrays contains 550 -- the bounds of the actual source level array, but the copy of an 551 -- entire array requires the bounds of the underlying array. It would 552 -- be nice if the back end could take care of this, but right now it 553 -- does not know how, so if we have such a type, then we expand out 554 -- into a loop, which is inefficient but works correctly. If we don't 555 -- do this, we get the wrong length computed for the array to be 556 -- moved. The two cases we need to worry about are: 557 558 -- Explicit dereference of an unconstrained packed array type as in 559 -- the following example: 560 561 -- procedure C52 is 562 -- type BITS is array(INTEGER range <>) of BOOLEAN; 563 -- pragma PACK(BITS); 564 -- type A is access BITS; 565 -- P1,P2 : A; 566 -- begin 567 -- P1 := new BITS (1 .. 65_535); 568 -- P2 := new BITS (1 .. 65_535); 569 -- P2.ALL := P1.ALL; 570 -- end C52; 571 572 -- A formal parameter reference with an unconstrained bit array type 573 -- is the other case we need to worry about (here we assume the same 574 -- BITS type declared above): 575 576 -- procedure Write_All (File : out BITS; Contents : BITS); 577 -- begin 578 -- File.Storage := Contents; 579 -- end Write_All; 580 581 -- We expand to a loop in either of these two cases 582 583 -- Question for future thought. Another potentially more efficient 584 -- approach would be to create the actual subtype, and then do an 585 -- unchecked conversion to this actual subtype ??? 586 587 Check_Unconstrained_Bit_Packed_Array : declare 588 589 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean; 590 -- Function to perform required test for the first case, above 591 -- (dereference of an unconstrained bit packed array). 592 593 ----------------------- 594 -- Is_UBPA_Reference -- 595 ----------------------- 596 597 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is 598 Typ : constant Entity_Id := Underlying_Type (Etype (Opnd)); 599 P_Type : Entity_Id; 600 Des_Type : Entity_Id; 601 602 begin 603 if Present (Packed_Array_Impl_Type (Typ)) 604 and then Is_Array_Type (Packed_Array_Impl_Type (Typ)) 605 and then not Is_Constrained (Packed_Array_Impl_Type (Typ)) 606 then 607 return True; 608 609 elsif Nkind (Opnd) = N_Explicit_Dereference then 610 P_Type := Underlying_Type (Etype (Prefix (Opnd))); 611 612 if not Is_Access_Type (P_Type) then 613 return False; 614 615 else 616 Des_Type := Designated_Type (P_Type); 617 return 618 Is_Bit_Packed_Array (Des_Type) 619 and then not Is_Constrained (Des_Type); 620 end if; 621 622 else 623 return False; 624 end if; 625 end Is_UBPA_Reference; 626 627 -- Start of processing for Check_Unconstrained_Bit_Packed_Array 628 629 begin 630 if Is_UBPA_Reference (Lhs) 631 or else 632 Is_UBPA_Reference (Rhs) 633 then 634 Loop_Required := True; 635 636 -- Here if we do not have the case of a reference to a bit packed 637 -- unconstrained array case. In this case gigi can most certainly 638 -- handle the assignment if a forwards move is allowed. 639 640 -- (could it handle the backwards case also???) 641 642 elsif Forwards_OK (N) then 643 return; 644 end if; 645 end Check_Unconstrained_Bit_Packed_Array; 646 647 -- The back end can always handle the assignment if the right side is a 648 -- string literal (note that overlap is definitely impossible in this 649 -- case). If the type is packed, a string literal is always converted 650 -- into an aggregate, except in the case of a null slice, for which no 651 -- aggregate can be written. In that case, rewrite the assignment as a 652 -- null statement, a length check has already been emitted to verify 653 -- that the range of the left-hand side is empty. 654 655 -- Note that this code is not executed if we have an assignment of a 656 -- string literal to a non-bit aligned component of a record, a case 657 -- which cannot be handled by the backend. 658 659 elsif Nkind (Rhs) = N_String_Literal then 660 if String_Length (Strval (Rhs)) = 0 661 and then Is_Bit_Packed_Array (L_Type) 662 then 663 Rewrite (N, Make_Null_Statement (Loc)); 664 Analyze (N); 665 end if; 666 667 return; 668 669 -- If either operand is bit packed, then we need a loop, since we can't 670 -- be sure that the slice is byte aligned. Similarly, if either operand 671 -- is a possibly unaligned slice, then we need a loop (since the back 672 -- end cannot handle unaligned slices). 673 674 elsif Is_Bit_Packed_Array (L_Type) 675 or else Is_Bit_Packed_Array (R_Type) 676 or else Is_Possibly_Unaligned_Slice (Lhs) 677 or else Is_Possibly_Unaligned_Slice (Rhs) 678 then 679 Loop_Required := True; 680 681 -- If we are not bit-packed, and we have only one slice, then no overlap 682 -- is possible except in the parameter case, so we can let the back end 683 -- handle things. 684 685 elsif not (L_Slice and R_Slice) then 686 if Forwards_OK (N) then 687 return; 688 end if; 689 end if; 690 691 -- If the right-hand side is a string literal, introduce a temporary for 692 -- it, for use in the generated loop that will follow. 693 694 if Nkind (Rhs) = N_String_Literal then 695 declare 696 Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Rhs); 697 Decl : Node_Id; 698 699 begin 700 Decl := 701 Make_Object_Declaration (Loc, 702 Defining_Identifier => Temp, 703 Object_Definition => New_Occurrence_Of (L_Type, Loc), 704 Expression => Relocate_Node (Rhs)); 705 706 Insert_Action (N, Decl); 707 Rewrite (Rhs, New_Occurrence_Of (Temp, Loc)); 708 R_Type := Etype (Temp); 709 end; 710 end if; 711 712 -- Come here to complete the analysis 713 714 -- Loop_Required: Set to True if we know that a loop is required 715 -- regardless of overlap considerations. 716 717 -- Forwards_OK: Set to False if we already know that a forwards 718 -- move is not safe, else set to True. 719 720 -- Backwards_OK: Set to False if we already know that a backwards 721 -- move is not safe, else set to True 722 723 -- Our task at this stage is to complete the overlap analysis, which can 724 -- result in possibly setting Forwards_OK or Backwards_OK to False, and 725 -- then generating the final code, either by deciding that it is OK 726 -- after all to let Gigi handle it, or by generating appropriate code 727 -- in the front end. 728 729 declare 730 L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type)); 731 R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type)); 732 733 Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ); 734 Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ); 735 Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ); 736 Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ); 737 738 Act_L_Array : Node_Id; 739 Act_R_Array : Node_Id; 740 741 Cleft_Lo : Node_Id; 742 Cright_Lo : Node_Id; 743 Condition : Node_Id; 744 745 Cresult : Compare_Result; 746 747 begin 748 -- Get the expressions for the arrays. If we are dealing with a 749 -- private type, then convert to the underlying type. We can do 750 -- direct assignments to an array that is a private type, but we 751 -- cannot assign to elements of the array without this extra 752 -- unchecked conversion. 753 754 -- Note: We propagate Parent to the conversion nodes to generate 755 -- a well-formed subtree. 756 757 if Nkind (Act_Lhs) = N_Slice then 758 Larray := Prefix (Act_Lhs); 759 else 760 Larray := Act_Lhs; 761 762 if Is_Private_Type (Etype (Larray)) then 763 declare 764 Par : constant Node_Id := Parent (Larray); 765 begin 766 Larray := 767 Unchecked_Convert_To 768 (Underlying_Type (Etype (Larray)), Larray); 769 Set_Parent (Larray, Par); 770 end; 771 end if; 772 end if; 773 774 if Nkind (Act_Rhs) = N_Slice then 775 Rarray := Prefix (Act_Rhs); 776 else 777 Rarray := Act_Rhs; 778 779 if Is_Private_Type (Etype (Rarray)) then 780 declare 781 Par : constant Node_Id := Parent (Rarray); 782 begin 783 Rarray := 784 Unchecked_Convert_To 785 (Underlying_Type (Etype (Rarray)), Rarray); 786 Set_Parent (Rarray, Par); 787 end; 788 end if; 789 end if; 790 791 -- If both sides are slices, we must figure out whether it is safe 792 -- to do the move in one direction or the other. It is always safe 793 -- if there is a change of representation since obviously two arrays 794 -- with different representations cannot possibly overlap. 795 796 if (not Crep) and L_Slice and R_Slice then 797 Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs)); 798 Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs)); 799 800 -- If both left- and right-hand arrays are entity names, and refer 801 -- to different entities, then we know that the move is safe (the 802 -- two storage areas are completely disjoint). 803 804 if Is_Entity_Name (Act_L_Array) 805 and then Is_Entity_Name (Act_R_Array) 806 and then Entity (Act_L_Array) /= Entity (Act_R_Array) 807 then 808 null; 809 810 -- Otherwise, we assume the worst, which is that the two arrays 811 -- are the same array. There is no need to check if we know that 812 -- is the case, because if we don't know it, we still have to 813 -- assume it. 814 815 -- Generally if the same array is involved, then we have an 816 -- overlapping case. We will have to really assume the worst (i.e. 817 -- set neither of the OK flags) unless we can determine the lower 818 -- or upper bounds at compile time and compare them. 819 820 else 821 Cresult := 822 Compile_Time_Compare 823 (Left_Lo, Right_Lo, Assume_Valid => True); 824 825 if Cresult = Unknown then 826 Cresult := 827 Compile_Time_Compare 828 (Left_Hi, Right_Hi, Assume_Valid => True); 829 end if; 830 831 case Cresult is 832 when EQ | LE | LT => 833 Set_Backwards_OK (N, False); 834 835 when GE | GT => 836 Set_Forwards_OK (N, False); 837 838 when NE | Unknown => 839 Set_Backwards_OK (N, False); 840 Set_Forwards_OK (N, False); 841 end case; 842 end if; 843 end if; 844 845 -- If after that analysis Loop_Required is False, meaning that we 846 -- have not discovered some non-overlap reason for requiring a loop, 847 -- then the outcome depends on the capabilities of the back end. 848 849 if not Loop_Required then 850 -- Assume the back end can deal with all cases of overlap by 851 -- falling back to memmove if it cannot use a more efficient 852 -- approach. 853 854 return; 855 end if; 856 857 -- At this stage we have to generate an explicit loop, and we have 858 -- the following cases: 859 860 -- Forwards_OK = True 861 862 -- Rnn : right_index := right_index'First; 863 -- for Lnn in left-index loop 864 -- left (Lnn) := right (Rnn); 865 -- Rnn := right_index'Succ (Rnn); 866 -- end loop; 867 868 -- Note: the above code MUST be analyzed with checks off, because 869 -- otherwise the Succ could overflow. But in any case this is more 870 -- efficient. 871 872 -- Forwards_OK = False, Backwards_OK = True 873 874 -- Rnn : right_index := right_index'Last; 875 -- for Lnn in reverse left-index loop 876 -- left (Lnn) := right (Rnn); 877 -- Rnn := right_index'Pred (Rnn); 878 -- end loop; 879 880 -- Note: the above code MUST be analyzed with checks off, because 881 -- otherwise the Pred could overflow. But in any case this is more 882 -- efficient. 883 884 -- Forwards_OK = Backwards_OK = False 885 886 -- This only happens if we have the same array on each side. It is 887 -- possible to create situations using overlays that violate this, 888 -- but we simply do not promise to get this "right" in this case. 889 890 -- There are two possible subcases. If the No_Implicit_Conditionals 891 -- restriction is set, then we generate the following code: 892 893 -- declare 894 -- T : constant <operand-type> := rhs; 895 -- begin 896 -- lhs := T; 897 -- end; 898 899 -- If implicit conditionals are permitted, then we generate: 900 901 -- if Left_Lo <= Right_Lo then 902 -- <code for Forwards_OK = True above> 903 -- else 904 -- <code for Backwards_OK = True above> 905 -- end if; 906 907 -- In order to detect possible aliasing, we examine the renamed 908 -- expression when the source or target is a renaming. However, 909 -- the renaming may be intended to capture an address that may be 910 -- affected by subsequent code, and therefore we must recover 911 -- the actual entity for the expansion that follows, not the 912 -- object it renames. In particular, if source or target designate 913 -- a portion of a dynamically allocated object, the pointer to it 914 -- may be reassigned but the renaming preserves the proper location. 915 916 if Is_Entity_Name (Rhs) 917 and then 918 Nkind (Parent (Entity (Rhs))) = N_Object_Renaming_Declaration 919 and then Nkind (Act_Rhs) = N_Slice 920 then 921 Rarray := Rhs; 922 end if; 923 924 if Is_Entity_Name (Lhs) 925 and then 926 Nkind (Parent (Entity (Lhs))) = N_Object_Renaming_Declaration 927 and then Nkind (Act_Lhs) = N_Slice 928 then 929 Larray := Lhs; 930 end if; 931 932 -- Cases where either Forwards_OK or Backwards_OK is true 933 934 if Forwards_OK (N) or else Backwards_OK (N) then 935 if Needs_Finalization (Component_Type (L_Type)) 936 and then Base_Type (L_Type) = Base_Type (R_Type) 937 and then Ndim = 1 938 and then not No_Ctrl_Actions (N) 939 then 940 declare 941 Proc : constant Entity_Id := 942 TSS (Base_Type (L_Type), TSS_Slice_Assign); 943 Actuals : List_Id; 944 945 begin 946 Apply_Dereference (Larray); 947 Apply_Dereference (Rarray); 948 Actuals := New_List ( 949 Duplicate_Subexpr (Larray, Name_Req => True), 950 Duplicate_Subexpr (Rarray, Name_Req => True), 951 Duplicate_Subexpr (Left_Lo, Name_Req => True), 952 Duplicate_Subexpr (Left_Hi, Name_Req => True), 953 Duplicate_Subexpr (Right_Lo, Name_Req => True), 954 Duplicate_Subexpr (Right_Hi, Name_Req => True)); 955 956 Append_To (Actuals, 957 New_Occurrence_Of ( 958 Boolean_Literals (not Forwards_OK (N)), Loc)); 959 960 Rewrite (N, 961 Make_Procedure_Call_Statement (Loc, 962 Name => New_Occurrence_Of (Proc, Loc), 963 Parameter_Associations => Actuals)); 964 end; 965 966 else 967 Rewrite (N, 968 Expand_Assign_Array_Loop_Or_Bitfield 969 (N, Larray, Rarray, L_Type, R_Type, Ndim, 970 Rev => not Forwards_OK (N))); 971 end if; 972 973 -- Case of both are false with No_Implicit_Conditionals 974 975 elsif Restriction_Active (No_Implicit_Conditionals) then 976 declare 977 T : constant Entity_Id := 978 Make_Defining_Identifier (Loc, Chars => Name_T); 979 980 begin 981 Rewrite (N, 982 Make_Block_Statement (Loc, 983 Declarations => New_List ( 984 Make_Object_Declaration (Loc, 985 Defining_Identifier => T, 986 Constant_Present => True, 987 Object_Definition => 988 New_Occurrence_Of (Etype (Rhs), Loc), 989 Expression => Relocate_Node (Rhs))), 990 991 Handled_Statement_Sequence => 992 Make_Handled_Sequence_Of_Statements (Loc, 993 Statements => New_List ( 994 Make_Assignment_Statement (Loc, 995 Name => Relocate_Node (Lhs), 996 Expression => New_Occurrence_Of (T, Loc)))))); 997 end; 998 999 -- Case of both are false with implicit conditionals allowed 1000 1001 else 1002 -- Before we generate this code, we must ensure that the left and 1003 -- right side array types are defined. They may be itypes, and we 1004 -- cannot let them be defined inside the if, since the first use 1005 -- in the then may not be executed. 1006 1007 Ensure_Defined (L_Type, N); 1008 Ensure_Defined (R_Type, N); 1009 1010 -- We normally compare addresses to find out which way round to 1011 -- do the loop, since this is reliable, and handles the cases of 1012 -- parameters, conversions etc. But we can't do that in the bit 1013 -- packed case, because addresses don't work there. 1014 1015 if not Is_Bit_Packed_Array (L_Type) then 1016 Condition := 1017 Make_Op_Le (Loc, 1018 Left_Opnd => 1019 Unchecked_Convert_To (RTE (RE_Integer_Address), 1020 Make_Attribute_Reference (Loc, 1021 Prefix => 1022 Make_Indexed_Component (Loc, 1023 Prefix => 1024 Duplicate_Subexpr_Move_Checks (Larray, True), 1025 Expressions => New_List ( 1026 Make_Attribute_Reference (Loc, 1027 Prefix => 1028 New_Occurrence_Of 1029 (L_Index_Typ, Loc), 1030 Attribute_Name => Name_First))), 1031 Attribute_Name => Name_Address)), 1032 1033 Right_Opnd => 1034 Unchecked_Convert_To (RTE (RE_Integer_Address), 1035 Make_Attribute_Reference (Loc, 1036 Prefix => 1037 Make_Indexed_Component (Loc, 1038 Prefix => 1039 Duplicate_Subexpr_Move_Checks (Rarray, True), 1040 Expressions => New_List ( 1041 Make_Attribute_Reference (Loc, 1042 Prefix => 1043 New_Occurrence_Of 1044 (R_Index_Typ, Loc), 1045 Attribute_Name => Name_First))), 1046 Attribute_Name => Name_Address))); 1047 1048 -- For the bit packed and VM cases we use the bounds. That's OK, 1049 -- because we don't have to worry about parameters, since they 1050 -- cannot cause overlap. Perhaps we should worry about weird slice 1051 -- conversions ??? 1052 1053 else 1054 -- Copy the bounds 1055 1056 Cleft_Lo := New_Copy_Tree (Left_Lo); 1057 Cright_Lo := New_Copy_Tree (Right_Lo); 1058 1059 -- If the types do not match we add an implicit conversion 1060 -- here to ensure proper match 1061 1062 if Etype (Left_Lo) /= Etype (Right_Lo) then 1063 Cright_Lo := 1064 Unchecked_Convert_To (Etype (Left_Lo), Cright_Lo); 1065 end if; 1066 1067 -- Reset the Analyzed flag, because the bounds of the index 1068 -- type itself may be universal, and must be reanalyzed to 1069 -- acquire the proper type for the back end. 1070 1071 Set_Analyzed (Cleft_Lo, False); 1072 Set_Analyzed (Cright_Lo, False); 1073 1074 Condition := 1075 Make_Op_Le (Loc, 1076 Left_Opnd => Cleft_Lo, 1077 Right_Opnd => Cright_Lo); 1078 end if; 1079 1080 if Needs_Finalization (Component_Type (L_Type)) 1081 and then Base_Type (L_Type) = Base_Type (R_Type) 1082 and then Ndim = 1 1083 and then not No_Ctrl_Actions (N) 1084 then 1085 1086 -- Call TSS procedure for array assignment, passing the 1087 -- explicit bounds of right- and left-hand sides. 1088 1089 declare 1090 Proc : constant Entity_Id := 1091 TSS (Base_Type (L_Type), TSS_Slice_Assign); 1092 Actuals : List_Id; 1093 1094 begin 1095 Apply_Dereference (Larray); 1096 Apply_Dereference (Rarray); 1097 Actuals := New_List ( 1098 Duplicate_Subexpr (Larray, Name_Req => True), 1099 Duplicate_Subexpr (Rarray, Name_Req => True), 1100 Duplicate_Subexpr (Left_Lo, Name_Req => True), 1101 Duplicate_Subexpr (Left_Hi, Name_Req => True), 1102 Duplicate_Subexpr (Right_Lo, Name_Req => True), 1103 Duplicate_Subexpr (Right_Hi, Name_Req => True)); 1104 1105 Append_To (Actuals, 1106 Make_Op_Not (Loc, 1107 Right_Opnd => Condition)); 1108 1109 Rewrite (N, 1110 Make_Procedure_Call_Statement (Loc, 1111 Name => New_Occurrence_Of (Proc, Loc), 1112 Parameter_Associations => Actuals)); 1113 end; 1114 1115 else 1116 Rewrite (N, 1117 Make_Implicit_If_Statement (N, 1118 Condition => Condition, 1119 1120 Then_Statements => New_List ( 1121 Expand_Assign_Array_Loop_Or_Bitfield 1122 (N, Larray, Rarray, L_Type, R_Type, Ndim, 1123 Rev => False)), 1124 1125 Else_Statements => New_List ( 1126 Expand_Assign_Array_Loop_Or_Bitfield 1127 (N, Larray, Rarray, L_Type, R_Type, Ndim, 1128 Rev => True)))); 1129 end if; 1130 end if; 1131 1132 Analyze (N, Suppress => All_Checks); 1133 end; 1134 1135 exception 1136 when RE_Not_Available => 1137 return; 1138 end Expand_Assign_Array; 1139 1140 ------------------------------ 1141 -- Expand_Assign_Array_Loop -- 1142 ------------------------------ 1143 1144 -- The following is an example of the loop generated for the case of a 1145 -- two-dimensional array: 1146 1147 -- declare 1148 -- R2b : Tm1X1 := 1; 1149 -- begin 1150 -- for L1b in 1 .. 100 loop 1151 -- declare 1152 -- R4b : Tm1X2 := 1; 1153 -- begin 1154 -- for L3b in 1 .. 100 loop 1155 -- vm1 (L1b, L3b) := vm2 (R2b, R4b); 1156 -- R4b := Tm1X2'succ(R4b); 1157 -- end loop; 1158 -- end; 1159 -- R2b := Tm1X1'succ(R2b); 1160 -- end loop; 1161 -- end; 1162 1163 -- Here Rev is False, and Tm1Xn are the subscript types for the right-hand 1164 -- side. The declarations of R2b and R4b are inserted before the original 1165 -- assignment statement. 1166 1167 function Expand_Assign_Array_Loop 1168 (N : Node_Id; 1169 Larray : Entity_Id; 1170 Rarray : Entity_Id; 1171 L_Type : Entity_Id; 1172 R_Type : Entity_Id; 1173 Ndim : Pos; 1174 Rev : Boolean) return Node_Id 1175 is 1176 Loc : constant Source_Ptr := Sloc (N); 1177 1178 Lnn : array (1 .. Ndim) of Entity_Id; 1179 Rnn : array (1 .. Ndim) of Entity_Id; 1180 -- Entities used as subscripts on left and right sides 1181 1182 L_Index_Type : array (1 .. Ndim) of Entity_Id; 1183 R_Index_Type : array (1 .. Ndim) of Entity_Id; 1184 -- Left and right index types 1185 1186 Assign : Node_Id; 1187 1188 F_Or_L : Name_Id; 1189 S_Or_P : Name_Id; 1190 1191 function Build_Step (J : Nat) return Node_Id; 1192 -- The increment step for the index of the right-hand side is written 1193 -- as an attribute reference (Succ or Pred). This function returns 1194 -- the corresponding node, which is placed at the end of the loop body. 1195 1196 ---------------- 1197 -- Build_Step -- 1198 ---------------- 1199 1200 function Build_Step (J : Nat) return Node_Id is 1201 Step : Node_Id; 1202 Lim : Name_Id; 1203 1204 begin 1205 if Rev then 1206 Lim := Name_First; 1207 else 1208 Lim := Name_Last; 1209 end if; 1210 1211 Step := 1212 Make_Assignment_Statement (Loc, 1213 Name => New_Occurrence_Of (Rnn (J), Loc), 1214 Expression => 1215 Make_Attribute_Reference (Loc, 1216 Prefix => 1217 New_Occurrence_Of (R_Index_Type (J), Loc), 1218 Attribute_Name => S_Or_P, 1219 Expressions => New_List ( 1220 New_Occurrence_Of (Rnn (J), Loc)))); 1221 1222 -- Note that on the last iteration of the loop, the index is increased 1223 -- (or decreased) past the corresponding bound. This is consistent with 1224 -- the C semantics of the back-end, where such an off-by-one value on a 1225 -- dead index variable is OK. However, in CodePeer mode this leads to 1226 -- spurious warnings, and thus we place a guard around the attribute 1227 -- reference. For obvious reasons we only do this for CodePeer. 1228 1229 if CodePeer_Mode then 1230 Step := 1231 Make_If_Statement (Loc, 1232 Condition => 1233 Make_Op_Ne (Loc, 1234 Left_Opnd => New_Occurrence_Of (Lnn (J), Loc), 1235 Right_Opnd => 1236 Make_Attribute_Reference (Loc, 1237 Prefix => New_Occurrence_Of (L_Index_Type (J), Loc), 1238 Attribute_Name => Lim)), 1239 Then_Statements => New_List (Step)); 1240 end if; 1241 1242 return Step; 1243 end Build_Step; 1244 1245 -- Start of processing for Expand_Assign_Array_Loop 1246 1247 begin 1248 if Rev then 1249 F_Or_L := Name_Last; 1250 S_Or_P := Name_Pred; 1251 else 1252 F_Or_L := Name_First; 1253 S_Or_P := Name_Succ; 1254 end if; 1255 1256 -- Setup index types and subscript entities 1257 1258 declare 1259 L_Index : Node_Id; 1260 R_Index : Node_Id; 1261 1262 begin 1263 L_Index := First_Index (L_Type); 1264 R_Index := First_Index (R_Type); 1265 1266 for J in 1 .. Ndim loop 1267 Lnn (J) := Make_Temporary (Loc, 'L'); 1268 Rnn (J) := Make_Temporary (Loc, 'R'); 1269 1270 L_Index_Type (J) := Etype (L_Index); 1271 R_Index_Type (J) := Etype (R_Index); 1272 1273 Next_Index (L_Index); 1274 Next_Index (R_Index); 1275 end loop; 1276 end; 1277 1278 -- Now construct the assignment statement 1279 1280 declare 1281 ExprL : constant List_Id := New_List; 1282 ExprR : constant List_Id := New_List; 1283 1284 begin 1285 for J in 1 .. Ndim loop 1286 Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc)); 1287 Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc)); 1288 end loop; 1289 1290 Assign := 1291 Make_Assignment_Statement (Loc, 1292 Name => 1293 Make_Indexed_Component (Loc, 1294 Prefix => Duplicate_Subexpr (Larray, Name_Req => True), 1295 Expressions => ExprL), 1296 Expression => 1297 Make_Indexed_Component (Loc, 1298 Prefix => Duplicate_Subexpr (Rarray, Name_Req => True), 1299 Expressions => ExprR)); 1300 1301 -- We set assignment OK, since there are some cases, e.g. in object 1302 -- declarations, where we are actually assigning into a constant. 1303 -- If there really is an illegality, it was caught long before now, 1304 -- and was flagged when the original assignment was analyzed. 1305 1306 Set_Assignment_OK (Name (Assign)); 1307 1308 -- Propagate the No_Ctrl_Actions flag to individual assignments 1309 1310 Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N)); 1311 end; 1312 1313 -- Now construct the loop from the inside out, with the last subscript 1314 -- varying most rapidly. Note that Assign is first the raw assignment 1315 -- statement, and then subsequently the loop that wraps it up. 1316 1317 for J in reverse 1 .. Ndim loop 1318 Assign := 1319 Make_Block_Statement (Loc, 1320 Declarations => New_List ( 1321 Make_Object_Declaration (Loc, 1322 Defining_Identifier => Rnn (J), 1323 Object_Definition => 1324 New_Occurrence_Of (R_Index_Type (J), Loc), 1325 Expression => 1326 Make_Attribute_Reference (Loc, 1327 Prefix => New_Occurrence_Of (R_Index_Type (J), Loc), 1328 Attribute_Name => F_Or_L))), 1329 1330 Handled_Statement_Sequence => 1331 Make_Handled_Sequence_Of_Statements (Loc, 1332 Statements => New_List ( 1333 Make_Implicit_Loop_Statement (N, 1334 Iteration_Scheme => 1335 Make_Iteration_Scheme (Loc, 1336 Loop_Parameter_Specification => 1337 Make_Loop_Parameter_Specification (Loc, 1338 Defining_Identifier => Lnn (J), 1339 Reverse_Present => Rev, 1340 Discrete_Subtype_Definition => 1341 New_Occurrence_Of (L_Index_Type (J), Loc))), 1342 1343 Statements => New_List (Assign, Build_Step (J)))))); 1344 end loop; 1345 1346 return Assign; 1347 end Expand_Assign_Array_Loop; 1348 1349 ---------------------------------- 1350 -- Expand_Assign_Array_Bitfield -- 1351 ---------------------------------- 1352 1353 function Expand_Assign_Array_Bitfield 1354 (N : Node_Id; 1355 Larray : Entity_Id; 1356 Rarray : Entity_Id; 1357 L_Type : Entity_Id; 1358 R_Type : Entity_Id; 1359 Rev : Boolean) return Node_Id 1360 is 1361 pragma Assert (not Rev); 1362 -- Reverse copying is not yet supported by Copy_Bitfield. 1363 1364 pragma Assert (not Change_Of_Representation (N)); 1365 -- This won't work, for example, to copy a packed array to an unpacked 1366 -- array. 1367 1368 Loc : constant Source_Ptr := Sloc (N); 1369 1370 L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type)); 1371 R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type)); 1372 Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ); 1373 Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ); 1374 1375 L_Addr : constant Node_Id := 1376 Make_Attribute_Reference (Loc, 1377 Prefix => 1378 Make_Indexed_Component (Loc, 1379 Prefix => 1380 Duplicate_Subexpr (Larray, True), 1381 Expressions => New_List (New_Copy_Tree (Left_Lo))), 1382 Attribute_Name => Name_Address); 1383 1384 L_Bit : constant Node_Id := 1385 Make_Attribute_Reference (Loc, 1386 Prefix => 1387 Make_Indexed_Component (Loc, 1388 Prefix => 1389 Duplicate_Subexpr (Larray, True), 1390 Expressions => New_List (New_Copy_Tree (Left_Lo))), 1391 Attribute_Name => Name_Bit); 1392 1393 R_Addr : constant Node_Id := 1394 Make_Attribute_Reference (Loc, 1395 Prefix => 1396 Make_Indexed_Component (Loc, 1397 Prefix => 1398 Duplicate_Subexpr (Rarray, True), 1399 Expressions => New_List (New_Copy_Tree (Right_Lo))), 1400 Attribute_Name => Name_Address); 1401 1402 R_Bit : constant Node_Id := 1403 Make_Attribute_Reference (Loc, 1404 Prefix => 1405 Make_Indexed_Component (Loc, 1406 Prefix => 1407 Duplicate_Subexpr (Rarray, True), 1408 Expressions => New_List (New_Copy_Tree (Right_Lo))), 1409 Attribute_Name => Name_Bit); 1410 1411 -- Compute the Size of the bitfield 1412 1413 -- Note that the length check has already been done, so we can use the 1414 -- size of either L or R; they are equal. We can't use 'Size here, 1415 -- because sometimes bit fields get copied into a temp, and the 'Size 1416 -- ends up being the size of the temp (e.g. an 8-bit temp containing 1417 -- a 4-bit bit field). 1418 1419 Size : constant Node_Id := 1420 Make_Op_Multiply (Loc, 1421 Make_Attribute_Reference (Loc, 1422 Prefix => 1423 Duplicate_Subexpr (Name (N), True), 1424 Attribute_Name => Name_Length), 1425 Make_Attribute_Reference (Loc, 1426 Prefix => 1427 Duplicate_Subexpr (Name (N), True), 1428 Attribute_Name => Name_Component_Size)); 1429 1430 begin 1431 return Make_Procedure_Call_Statement (Loc, 1432 Name => New_Occurrence_Of (RTE (RE_Copy_Bitfield), Loc), 1433 Parameter_Associations => New_List ( 1434 R_Addr, R_Bit, L_Addr, L_Bit, Size)); 1435 end Expand_Assign_Array_Bitfield; 1436 1437 ------------------------------------------ 1438 -- Expand_Assign_Array_Loop_Or_Bitfield -- 1439 ------------------------------------------ 1440 1441 function Expand_Assign_Array_Loop_Or_Bitfield 1442 (N : Node_Id; 1443 Larray : Entity_Id; 1444 Rarray : Entity_Id; 1445 L_Type : Entity_Id; 1446 R_Type : Entity_Id; 1447 Ndim : Pos; 1448 Rev : Boolean) return Node_Id 1449 is 1450 Slices : constant Boolean := 1451 Nkind (Name (N)) = N_Slice or else Nkind (Expression (N)) = N_Slice; 1452 L_Prefix_Comp : constant Boolean := 1453 -- True if the left-hand side is a slice of a component or slice 1454 Nkind (Name (N)) = N_Slice 1455 and then Nkind_In (Prefix (Name (N)), 1456 N_Selected_Component, 1457 N_Indexed_Component, 1458 N_Slice); 1459 R_Prefix_Comp : constant Boolean := 1460 -- Likewise for the right-hand side 1461 Nkind (Expression (N)) = N_Slice 1462 and then Nkind_In (Prefix (Expression (N)), 1463 N_Selected_Component, 1464 N_Indexed_Component, 1465 N_Slice); 1466 begin 1467 -- Determine whether Copy_Bitfield is appropriate (will work, and will 1468 -- be more efficient than component-by-component copy). Copy_Bitfield 1469 -- doesn't work for reversed storage orders. It is efficient for slices 1470 -- of bit-packed arrays. Copy_Bitfield can read and write bits that are 1471 -- not part of the objects being copied, so we don't want to use it if 1472 -- there are volatile or independent components. If the Prefix of the 1473 -- slice is a component or slice, then it might be a part of an object 1474 -- with some other volatile or independent components, so we disable the 1475 -- optimization in that case as well. We could complicate this code by 1476 -- actually looking for such volatile and independent components. 1477 1478 if Is_Bit_Packed_Array (L_Type) 1479 and then Is_Bit_Packed_Array (R_Type) 1480 and then not Reverse_Storage_Order (L_Type) 1481 and then not Reverse_Storage_Order (R_Type) 1482 and then Ndim = 1 1483 and then not Rev 1484 and then Slices 1485 and then not Has_Volatile_Component (L_Type) 1486 and then not Has_Volatile_Component (R_Type) 1487 and then not Has_Independent_Components (L_Type) 1488 and then not Has_Independent_Components (R_Type) 1489 and then not L_Prefix_Comp 1490 and then not R_Prefix_Comp 1491 and then RTE_Available (RE_Copy_Bitfield) 1492 then 1493 return Expand_Assign_Array_Bitfield 1494 (N, Larray, Rarray, L_Type, R_Type, Rev); 1495 else 1496 return Expand_Assign_Array_Loop 1497 (N, Larray, Rarray, L_Type, R_Type, Ndim, Rev); 1498 end if; 1499 end Expand_Assign_Array_Loop_Or_Bitfield; 1500 1501 -------------------------- 1502 -- Expand_Assign_Record -- 1503 -------------------------- 1504 1505 procedure Expand_Assign_Record (N : Node_Id) is 1506 Lhs : constant Node_Id := Name (N); 1507 Rhs : Node_Id := Expression (N); 1508 L_Typ : constant Entity_Id := Base_Type (Etype (Lhs)); 1509 1510 begin 1511 -- If change of representation, then extract the real right-hand side 1512 -- from the type conversion, and proceed with component-wise assignment, 1513 -- since the two types are not the same as far as the back end is 1514 -- concerned. 1515 1516 if Change_Of_Representation (N) then 1517 Rhs := Expression (Rhs); 1518 1519 -- If this may be a case of a large bit aligned component, then proceed 1520 -- with component-wise assignment, to avoid possible clobbering of other 1521 -- components sharing bits in the first or last byte of the component to 1522 -- be assigned. 1523 1524 elsif Possible_Bit_Aligned_Component (Lhs) 1525 or 1526 Possible_Bit_Aligned_Component (Rhs) 1527 then 1528 null; 1529 1530 -- If we have a tagged type that has a complete record representation 1531 -- clause, we must do we must do component-wise assignments, since child 1532 -- types may have used gaps for their components, and we might be 1533 -- dealing with a view conversion. 1534 1535 elsif Is_Fully_Repped_Tagged_Type (L_Typ) then 1536 null; 1537 1538 -- If neither condition met, then nothing special to do, the back end 1539 -- can handle assignment of the entire component as a single entity. 1540 1541 else 1542 return; 1543 end if; 1544 1545 -- At this stage we know that we must do a component wise assignment 1546 1547 declare 1548 Loc : constant Source_Ptr := Sloc (N); 1549 R_Typ : constant Entity_Id := Base_Type (Etype (Rhs)); 1550 Decl : constant Node_Id := Declaration_Node (R_Typ); 1551 RDef : Node_Id; 1552 F : Entity_Id; 1553 1554 function Find_Component 1555 (Typ : Entity_Id; 1556 Comp : Entity_Id) return Entity_Id; 1557 -- Find the component with the given name in the underlying record 1558 -- declaration for Typ. We need to use the actual entity because the 1559 -- type may be private and resolution by identifier alone would fail. 1560 1561 function Make_Component_List_Assign 1562 (CL : Node_Id; 1563 U_U : Boolean := False) return List_Id; 1564 -- Returns a sequence of statements to assign the components that 1565 -- are referenced in the given component list. The flag U_U is 1566 -- used to force the usage of the inferred value of the variant 1567 -- part expression as the switch for the generated case statement. 1568 1569 function Make_Field_Assign 1570 (C : Entity_Id; 1571 U_U : Boolean := False) return Node_Id; 1572 -- Given C, the entity for a discriminant or component, build an 1573 -- assignment for the corresponding field values. The flag U_U 1574 -- signals the presence of an Unchecked_Union and forces the usage 1575 -- of the inferred discriminant value of C as the right-hand side 1576 -- of the assignment. 1577 1578 function Make_Field_Assigns (CI : List_Id) return List_Id; 1579 -- Given CI, a component items list, construct series of statements 1580 -- for fieldwise assignment of the corresponding components. 1581 1582 -------------------- 1583 -- Find_Component -- 1584 -------------------- 1585 1586 function Find_Component 1587 (Typ : Entity_Id; 1588 Comp : Entity_Id) return Entity_Id 1589 is 1590 Utyp : constant Entity_Id := Underlying_Type (Typ); 1591 C : Entity_Id; 1592 1593 begin 1594 C := First_Entity (Utyp); 1595 while Present (C) loop 1596 if Chars (C) = Chars (Comp) then 1597 return C; 1598 end if; 1599 1600 Next_Entity (C); 1601 end loop; 1602 1603 raise Program_Error; 1604 end Find_Component; 1605 1606 -------------------------------- 1607 -- Make_Component_List_Assign -- 1608 -------------------------------- 1609 1610 function Make_Component_List_Assign 1611 (CL : Node_Id; 1612 U_U : Boolean := False) return List_Id 1613 is 1614 CI : constant List_Id := Component_Items (CL); 1615 VP : constant Node_Id := Variant_Part (CL); 1616 1617 Alts : List_Id; 1618 DC : Node_Id; 1619 DCH : List_Id; 1620 Expr : Node_Id; 1621 Result : List_Id; 1622 V : Node_Id; 1623 1624 begin 1625 Result := Make_Field_Assigns (CI); 1626 1627 if Present (VP) then 1628 V := First_Non_Pragma (Variants (VP)); 1629 Alts := New_List; 1630 while Present (V) loop 1631 DCH := New_List; 1632 DC := First (Discrete_Choices (V)); 1633 while Present (DC) loop 1634 Append_To (DCH, New_Copy_Tree (DC)); 1635 Next (DC); 1636 end loop; 1637 1638 Append_To (Alts, 1639 Make_Case_Statement_Alternative (Loc, 1640 Discrete_Choices => DCH, 1641 Statements => 1642 Make_Component_List_Assign (Component_List (V)))); 1643 Next_Non_Pragma (V); 1644 end loop; 1645 1646 -- If we have an Unchecked_Union, use the value of the inferred 1647 -- discriminant of the variant part expression as the switch 1648 -- for the case statement. The case statement may later be 1649 -- folded. 1650 1651 if U_U then 1652 Expr := 1653 New_Copy (Get_Discriminant_Value ( 1654 Entity (Name (VP)), 1655 Etype (Rhs), 1656 Discriminant_Constraint (Etype (Rhs)))); 1657 else 1658 Expr := 1659 Make_Selected_Component (Loc, 1660 Prefix => Duplicate_Subexpr (Rhs), 1661 Selector_Name => 1662 Make_Identifier (Loc, Chars (Name (VP)))); 1663 end if; 1664 1665 Append_To (Result, 1666 Make_Case_Statement (Loc, 1667 Expression => Expr, 1668 Alternatives => Alts)); 1669 end if; 1670 1671 return Result; 1672 end Make_Component_List_Assign; 1673 1674 ----------------------- 1675 -- Make_Field_Assign -- 1676 ----------------------- 1677 1678 function Make_Field_Assign 1679 (C : Entity_Id; 1680 U_U : Boolean := False) return Node_Id 1681 is 1682 A : Node_Id; 1683 Disc : Entity_Id; 1684 Expr : Node_Id; 1685 1686 begin 1687 -- The discriminant entity to be used in the retrieval below must 1688 -- be one in the corresponding type, given that the assignment may 1689 -- be between derived and parent types. 1690 1691 if Is_Derived_Type (Etype (Rhs)) then 1692 Disc := Find_Component (R_Typ, C); 1693 else 1694 Disc := C; 1695 end if; 1696 1697 -- In the case of an Unchecked_Union, use the discriminant 1698 -- constraint value as on the right-hand side of the assignment. 1699 1700 if U_U then 1701 Expr := 1702 New_Copy (Get_Discriminant_Value (C, 1703 Etype (Rhs), 1704 Discriminant_Constraint (Etype (Rhs)))); 1705 else 1706 Expr := 1707 Make_Selected_Component (Loc, 1708 Prefix => Duplicate_Subexpr (Rhs), 1709 Selector_Name => New_Occurrence_Of (Disc, Loc)); 1710 end if; 1711 1712 -- Generate the assignment statement. When the left-hand side 1713 -- is an object with an address clause present, force generated 1714 -- temporaries to be renamings so as to correctly assign to any 1715 -- overlaid objects. 1716 1717 A := 1718 Make_Assignment_Statement (Loc, 1719 Name => 1720 Make_Selected_Component (Loc, 1721 Prefix => 1722 Duplicate_Subexpr 1723 (Exp => Lhs, 1724 Name_Req => False, 1725 Renaming_Req => 1726 Is_Entity_Name (Lhs) 1727 and then Present (Address_Clause (Entity (Lhs)))), 1728 Selector_Name => 1729 New_Occurrence_Of (Find_Component (L_Typ, C), Loc)), 1730 Expression => Expr); 1731 1732 -- Set Assignment_OK, so discriminants can be assigned 1733 1734 Set_Assignment_OK (Name (A), True); 1735 1736 if Componentwise_Assignment (N) 1737 and then Nkind (Name (A)) = N_Selected_Component 1738 and then Chars (Selector_Name (Name (A))) = Name_uParent 1739 then 1740 Set_Componentwise_Assignment (A); 1741 end if; 1742 1743 return A; 1744 end Make_Field_Assign; 1745 1746 ------------------------ 1747 -- Make_Field_Assigns -- 1748 ------------------------ 1749 1750 function Make_Field_Assigns (CI : List_Id) return List_Id is 1751 Item : Node_Id; 1752 Result : List_Id; 1753 1754 begin 1755 Item := First (CI); 1756 Result := New_List; 1757 1758 while Present (Item) loop 1759 1760 -- Look for components, but exclude _tag field assignment if 1761 -- the special Componentwise_Assignment flag is set. 1762 1763 if Nkind (Item) = N_Component_Declaration 1764 and then not (Is_Tag (Defining_Identifier (Item)) 1765 and then Componentwise_Assignment (N)) 1766 then 1767 Append_To 1768 (Result, Make_Field_Assign (Defining_Identifier (Item))); 1769 end if; 1770 1771 Next (Item); 1772 end loop; 1773 1774 return Result; 1775 end Make_Field_Assigns; 1776 1777 -- Start of processing for Expand_Assign_Record 1778 1779 begin 1780 -- Note that we use the base types for this processing. This results 1781 -- in some extra work in the constrained case, but the change of 1782 -- representation case is so unusual that it is not worth the effort. 1783 1784 -- First copy the discriminants. This is done unconditionally. It 1785 -- is required in the unconstrained left side case, and also in the 1786 -- case where this assignment was constructed during the expansion 1787 -- of a type conversion (since initialization of discriminants is 1788 -- suppressed in this case). It is unnecessary but harmless in 1789 -- other cases. 1790 1791 -- Special case: no copy if the target has no discriminants 1792 1793 if Has_Discriminants (L_Typ) 1794 and then Is_Unchecked_Union (Base_Type (L_Typ)) 1795 then 1796 null; 1797 1798 elsif Has_Discriminants (L_Typ) then 1799 F := First_Discriminant (R_Typ); 1800 while Present (F) loop 1801 1802 -- If we are expanding the initialization of a derived record 1803 -- that constrains or renames discriminants of the parent, we 1804 -- must use the corresponding discriminant in the parent. 1805 1806 declare 1807 CF : Entity_Id; 1808 1809 begin 1810 if Inside_Init_Proc 1811 and then Present (Corresponding_Discriminant (F)) 1812 then 1813 CF := Corresponding_Discriminant (F); 1814 else 1815 CF := F; 1816 end if; 1817 1818 if Is_Unchecked_Union (Base_Type (R_Typ)) then 1819 1820 -- Within an initialization procedure this is the 1821 -- assignment to an unchecked union component, in which 1822 -- case there is no discriminant to initialize. 1823 1824 if Inside_Init_Proc then 1825 null; 1826 1827 else 1828 -- The assignment is part of a conversion from a 1829 -- derived unchecked union type with an inferable 1830 -- discriminant, to a parent type. 1831 1832 Insert_Action (N, Make_Field_Assign (CF, True)); 1833 end if; 1834 1835 else 1836 Insert_Action (N, Make_Field_Assign (CF)); 1837 end if; 1838 1839 Next_Discriminant (F); 1840 end; 1841 end loop; 1842 1843 -- If the derived type has a stored constraint, assign the value 1844 -- of the corresponding discriminants explicitly, skipping those 1845 -- that are renamed discriminants. We cannot just retrieve them 1846 -- from the Rhs by selected component because they are invisible 1847 -- in the type of the right-hand side. 1848 1849 if Stored_Constraint (R_Typ) /= No_Elist then 1850 declare 1851 Assign : Node_Id; 1852 Discr_Val : Elmt_Id; 1853 1854 begin 1855 Discr_Val := First_Elmt (Stored_Constraint (R_Typ)); 1856 F := First_Entity (R_Typ); 1857 while Present (F) loop 1858 if Ekind (F) = E_Discriminant 1859 and then Is_Completely_Hidden (F) 1860 and then Present (Corresponding_Record_Component (F)) 1861 and then 1862 (not Is_Entity_Name (Node (Discr_Val)) 1863 or else Ekind (Entity (Node (Discr_Val))) /= 1864 E_Discriminant) 1865 then 1866 Assign := 1867 Make_Assignment_Statement (Loc, 1868 Name => 1869 Make_Selected_Component (Loc, 1870 Prefix => Duplicate_Subexpr (Lhs), 1871 Selector_Name => 1872 New_Occurrence_Of 1873 (Corresponding_Record_Component (F), Loc)), 1874 Expression => New_Copy (Node (Discr_Val))); 1875 1876 Set_Assignment_OK (Name (Assign)); 1877 Insert_Action (N, Assign); 1878 Next_Elmt (Discr_Val); 1879 end if; 1880 1881 Next_Entity (F); 1882 end loop; 1883 end; 1884 end if; 1885 end if; 1886 1887 -- We know the underlying type is a record, but its current view 1888 -- may be private. We must retrieve the usable record declaration. 1889 1890 if Nkind_In (Decl, N_Private_Type_Declaration, 1891 N_Private_Extension_Declaration) 1892 and then Present (Full_View (R_Typ)) 1893 then 1894 RDef := Type_Definition (Declaration_Node (Full_View (R_Typ))); 1895 else 1896 RDef := Type_Definition (Decl); 1897 end if; 1898 1899 if Nkind (RDef) = N_Derived_Type_Definition then 1900 RDef := Record_Extension_Part (RDef); 1901 end if; 1902 1903 if Nkind (RDef) = N_Record_Definition 1904 and then Present (Component_List (RDef)) 1905 then 1906 if Is_Unchecked_Union (R_Typ) then 1907 Insert_Actions (N, 1908 Make_Component_List_Assign (Component_List (RDef), True)); 1909 else 1910 Insert_Actions 1911 (N, Make_Component_List_Assign (Component_List (RDef))); 1912 end if; 1913 1914 Rewrite (N, Make_Null_Statement (Loc)); 1915 end if; 1916 end; 1917 end Expand_Assign_Record; 1918 1919 ------------------------------------- 1920 -- Expand_Assign_With_Target_Names -- 1921 ------------------------------------- 1922 1923 procedure Expand_Assign_With_Target_Names (N : Node_Id) is 1924 LHS : constant Node_Id := Name (N); 1925 LHS_Typ : constant Entity_Id := Etype (LHS); 1926 Loc : constant Source_Ptr := Sloc (N); 1927 RHS : constant Node_Id := Expression (N); 1928 1929 Ent : Entity_Id; 1930 -- The entity of the left-hand side 1931 1932 function Replace_Target (N : Node_Id) return Traverse_Result; 1933 -- Replace occurrences of the target name by the proper entity: either 1934 -- the entity of the LHS in simple cases, or the formal of the 1935 -- constructed procedure otherwise. 1936 1937 -------------------- 1938 -- Replace_Target -- 1939 -------------------- 1940 1941 function Replace_Target (N : Node_Id) return Traverse_Result is 1942 begin 1943 if Nkind (N) = N_Target_Name then 1944 Rewrite (N, New_Occurrence_Of (Ent, Sloc (N))); 1945 1946 -- The expression will be reanalyzed when the enclosing assignment 1947 -- is reanalyzed, so reset the entity, which may be a temporary 1948 -- created during analysis, e.g. a loop variable for an iterated 1949 -- component association. However, if entity is callable then 1950 -- resolution has established its proper identity (including in 1951 -- rewritten prefixed calls) so we must preserve it. 1952 1953 elsif Is_Entity_Name (N) then 1954 if Present (Entity (N)) 1955 and then not Is_Overloadable (Entity (N)) 1956 then 1957 Set_Entity (N, Empty); 1958 end if; 1959 end if; 1960 1961 Set_Analyzed (N, False); 1962 return OK; 1963 end Replace_Target; 1964 1965 procedure Replace_Target_Name is new Traverse_Proc (Replace_Target); 1966 1967 -- Local variables 1968 1969 New_RHS : Node_Id; 1970 Proc_Id : Entity_Id; 1971 1972 -- Start of processing for Expand_Assign_With_Target_Names 1973 1974 begin 1975 New_RHS := New_Copy_Tree (RHS); 1976 1977 -- The left-hand side is a direct name 1978 1979 if Is_Entity_Name (LHS) 1980 and then not Is_Renaming_Of_Object (Entity (LHS)) 1981 then 1982 Ent := Entity (LHS); 1983 Replace_Target_Name (New_RHS); 1984 1985 -- Generate: 1986 -- LHS := ... LHS ...; 1987 1988 Rewrite (N, 1989 Make_Assignment_Statement (Loc, 1990 Name => Relocate_Node (LHS), 1991 Expression => New_RHS)); 1992 1993 -- The left-hand side is not a direct name, but is side-effect free. 1994 -- Capture its value in a temporary to avoid multiple evaluations. 1995 1996 elsif Side_Effect_Free (LHS) then 1997 Ent := Make_Temporary (Loc, 'T'); 1998 Replace_Target_Name (New_RHS); 1999 2000 -- Generate: 2001 -- T : LHS_Typ := LHS; 2002 2003 Insert_Before_And_Analyze (N, 2004 Make_Object_Declaration (Loc, 2005 Defining_Identifier => Ent, 2006 Object_Definition => New_Occurrence_Of (LHS_Typ, Loc), 2007 Expression => New_Copy_Tree (LHS))); 2008 2009 -- Generate: 2010 -- LHS := ... T ...; 2011 2012 Rewrite (N, 2013 Make_Assignment_Statement (Loc, 2014 Name => Relocate_Node (LHS), 2015 Expression => New_RHS)); 2016 2017 -- Otherwise wrap the whole assignment statement in a procedure with an 2018 -- IN OUT parameter. The original assignment then becomes a call to the 2019 -- procedure with the left-hand side as an actual. 2020 2021 else 2022 Ent := Make_Temporary (Loc, 'T'); 2023 Replace_Target_Name (New_RHS); 2024 2025 -- Generate: 2026 -- procedure P (T : in out LHS_Typ) is 2027 -- begin 2028 -- T := ... T ...; 2029 -- end P; 2030 2031 Proc_Id := Make_Temporary (Loc, 'P'); 2032 2033 Insert_Before_And_Analyze (N, 2034 Make_Subprogram_Body (Loc, 2035 Specification => 2036 Make_Procedure_Specification (Loc, 2037 Defining_Unit_Name => Proc_Id, 2038 Parameter_Specifications => New_List ( 2039 Make_Parameter_Specification (Loc, 2040 Defining_Identifier => Ent, 2041 In_Present => True, 2042 Out_Present => True, 2043 Parameter_Type => 2044 New_Occurrence_Of (LHS_Typ, Loc)))), 2045 2046 Declarations => Empty_List, 2047 2048 Handled_Statement_Sequence => 2049 Make_Handled_Sequence_Of_Statements (Loc, 2050 Statements => New_List ( 2051 Make_Assignment_Statement (Loc, 2052 Name => New_Occurrence_Of (Ent, Loc), 2053 Expression => New_RHS))))); 2054 2055 -- Generate: 2056 -- P (LHS); 2057 2058 Rewrite (N, 2059 Make_Procedure_Call_Statement (Loc, 2060 Name => New_Occurrence_Of (Proc_Id, Loc), 2061 Parameter_Associations => New_List (Relocate_Node (LHS)))); 2062 end if; 2063 2064 -- Analyze rewritten node, either as assignment or procedure call 2065 2066 Analyze (N); 2067 end Expand_Assign_With_Target_Names; 2068 2069 ----------------------------------- 2070 -- Expand_N_Assignment_Statement -- 2071 ----------------------------------- 2072 2073 -- This procedure implements various cases where an assignment statement 2074 -- cannot just be passed on to the back end in untransformed state. 2075 2076 procedure Expand_N_Assignment_Statement (N : Node_Id) is 2077 Crep : constant Boolean := Change_Of_Representation (N); 2078 Lhs : constant Node_Id := Name (N); 2079 Loc : constant Source_Ptr := Sloc (N); 2080 Rhs : constant Node_Id := Expression (N); 2081 Typ : constant Entity_Id := Underlying_Type (Etype (Lhs)); 2082 Exp : Node_Id; 2083 2084 begin 2085 -- Special case to check right away, if the Componentwise_Assignment 2086 -- flag is set, this is a reanalysis from the expansion of the primitive 2087 -- assignment procedure for a tagged type, and all we need to do is to 2088 -- expand to assignment of components, because otherwise, we would get 2089 -- infinite recursion (since this looks like a tagged assignment which 2090 -- would normally try to *call* the primitive assignment procedure). 2091 2092 if Componentwise_Assignment (N) then 2093 Expand_Assign_Record (N); 2094 return; 2095 end if; 2096 2097 -- Defend against invalid subscripts on left side if we are in standard 2098 -- validity checking mode. No need to do this if we are checking all 2099 -- subscripts. 2100 2101 -- Note that we do this right away, because there are some early return 2102 -- paths in this procedure, and this is required on all paths. 2103 2104 if Validity_Checks_On 2105 and then Validity_Check_Default 2106 and then not Validity_Check_Subscripts 2107 then 2108 Check_Valid_Lvalue_Subscripts (Lhs); 2109 end if; 2110 2111 -- Separate expansion if RHS contain target names. Note that assignment 2112 -- may already have been expanded if RHS is aggregate. 2113 2114 if Nkind (N) = N_Assignment_Statement and then Has_Target_Names (N) then 2115 Expand_Assign_With_Target_Names (N); 2116 return; 2117 end if; 2118 2119 -- Ada 2005 (AI-327): Handle assignment to priority of protected object 2120 2121 -- Rewrite an assignment to X'Priority into a run-time call 2122 2123 -- For example: X'Priority := New_Prio_Expr; 2124 -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr); 2125 2126 -- Note that although X'Priority is notionally an object, it is quite 2127 -- deliberately not defined as an aliased object in the RM. This means 2128 -- that it works fine to rewrite it as a call, without having to worry 2129 -- about complications that would other arise from X'Priority'Access, 2130 -- which is illegal, because of the lack of aliasing. 2131 2132 if Ada_Version >= Ada_2005 then 2133 declare 2134 Call : Node_Id; 2135 Conctyp : Entity_Id; 2136 Ent : Entity_Id; 2137 Subprg : Entity_Id; 2138 RT_Subprg_Name : Node_Id; 2139 2140 begin 2141 -- Handle chains of renamings 2142 2143 Ent := Name (N); 2144 while Nkind (Ent) in N_Has_Entity 2145 and then Present (Entity (Ent)) 2146 and then Present (Renamed_Object (Entity (Ent))) 2147 loop 2148 Ent := Renamed_Object (Entity (Ent)); 2149 end loop; 2150 2151 -- The attribute Priority applied to protected objects has been 2152 -- previously expanded into a call to the Get_Ceiling run-time 2153 -- subprogram. In restricted profiles this is not available. 2154 2155 if Is_Expanded_Priority_Attribute (Ent) then 2156 2157 -- Look for the enclosing concurrent type 2158 2159 Conctyp := Current_Scope; 2160 while not Is_Concurrent_Type (Conctyp) loop 2161 Conctyp := Scope (Conctyp); 2162 end loop; 2163 2164 pragma Assert (Is_Protected_Type (Conctyp)); 2165 2166 -- Generate the first actual of the call 2167 2168 Subprg := Current_Scope; 2169 while not Present (Protected_Body_Subprogram (Subprg)) loop 2170 Subprg := Scope (Subprg); 2171 end loop; 2172 2173 -- Select the appropriate run-time call 2174 2175 if Number_Entries (Conctyp) = 0 then 2176 RT_Subprg_Name := 2177 New_Occurrence_Of (RTE (RE_Set_Ceiling), Loc); 2178 else 2179 RT_Subprg_Name := 2180 New_Occurrence_Of (RTE (RO_PE_Set_Ceiling), Loc); 2181 end if; 2182 2183 Call := 2184 Make_Procedure_Call_Statement (Loc, 2185 Name => RT_Subprg_Name, 2186 Parameter_Associations => New_List ( 2187 New_Copy_Tree (First (Parameter_Associations (Ent))), 2188 Relocate_Node (Expression (N)))); 2189 2190 Rewrite (N, Call); 2191 Analyze (N); 2192 2193 return; 2194 end if; 2195 end; 2196 end if; 2197 2198 -- Deal with assignment checks unless suppressed 2199 2200 if not Suppress_Assignment_Checks (N) then 2201 2202 -- First deal with generation of range check if required, 2203 -- and then predicate checks if the type carries a predicate. 2204 -- If the Rhs is an expression these tests may have been applied 2205 -- already. This is the case if the RHS is a type conversion. 2206 -- Other such redundant checks could be removed ??? 2207 2208 if Nkind (Rhs) /= N_Type_Conversion 2209 or else Entity (Subtype_Mark (Rhs)) /= Typ 2210 then 2211 if Do_Range_Check (Rhs) then 2212 Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed); 2213 end if; 2214 2215 Apply_Predicate_Check (Rhs, Typ); 2216 end if; 2217 end if; 2218 2219 -- Check for a special case where a high level transformation is 2220 -- required. If we have either of: 2221 2222 -- P.field := rhs; 2223 -- P (sub) := rhs; 2224 2225 -- where P is a reference to a bit packed array, then we have to unwind 2226 -- the assignment. The exact meaning of being a reference to a bit 2227 -- packed array is as follows: 2228 2229 -- An indexed component whose prefix is a bit packed array is a 2230 -- reference to a bit packed array. 2231 2232 -- An indexed component or selected component whose prefix is a 2233 -- reference to a bit packed array is itself a reference ot a 2234 -- bit packed array. 2235 2236 -- The required transformation is 2237 2238 -- Tnn : prefix_type := P; 2239 -- Tnn.field := rhs; 2240 -- P := Tnn; 2241 2242 -- or 2243 2244 -- Tnn : prefix_type := P; 2245 -- Tnn (subscr) := rhs; 2246 -- P := Tnn; 2247 2248 -- Since P is going to be evaluated more than once, any subscripts 2249 -- in P must have their evaluation forced. 2250 2251 if Nkind_In (Lhs, N_Indexed_Component, N_Selected_Component) 2252 and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs)) 2253 then 2254 declare 2255 BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs)); 2256 BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr); 2257 Tnn : constant Entity_Id := 2258 Make_Temporary (Loc, 'T', BPAR_Expr); 2259 2260 begin 2261 -- Insert the post assignment first, because we want to copy the 2262 -- BPAR_Expr tree before it gets analyzed in the context of the 2263 -- pre assignment. Note that we do not analyze the post assignment 2264 -- yet (we cannot till we have completed the analysis of the pre 2265 -- assignment). As usual, the analysis of this post assignment 2266 -- will happen on its own when we "run into" it after finishing 2267 -- the current assignment. 2268 2269 Insert_After (N, 2270 Make_Assignment_Statement (Loc, 2271 Name => New_Copy_Tree (BPAR_Expr), 2272 Expression => New_Occurrence_Of (Tnn, Loc))); 2273 2274 -- At this stage BPAR_Expr is a reference to a bit packed array 2275 -- where the reference was not expanded in the original tree, 2276 -- since it was on the left side of an assignment. But in the 2277 -- pre-assignment statement (the object definition), BPAR_Expr 2278 -- will end up on the right-hand side, and must be reexpanded. To 2279 -- achieve this, we reset the analyzed flag of all selected and 2280 -- indexed components down to the actual indexed component for 2281 -- the packed array. 2282 2283 Exp := BPAR_Expr; 2284 loop 2285 Set_Analyzed (Exp, False); 2286 2287 if Nkind_In (Exp, N_Indexed_Component, 2288 N_Selected_Component) 2289 then 2290 Exp := Prefix (Exp); 2291 else 2292 exit; 2293 end if; 2294 end loop; 2295 2296 -- Now we can insert and analyze the pre-assignment 2297 2298 -- If the right-hand side requires a transient scope, it has 2299 -- already been placed on the stack. However, the declaration is 2300 -- inserted in the tree outside of this scope, and must reflect 2301 -- the proper scope for its variable. This awkward bit is forced 2302 -- by the stricter scope discipline imposed by GCC 2.97. 2303 2304 declare 2305 Uses_Transient_Scope : constant Boolean := 2306 Scope_Is_Transient 2307 and then N = Node_To_Be_Wrapped; 2308 2309 begin 2310 if Uses_Transient_Scope then 2311 Push_Scope (Scope (Current_Scope)); 2312 end if; 2313 2314 Insert_Before_And_Analyze (N, 2315 Make_Object_Declaration (Loc, 2316 Defining_Identifier => Tnn, 2317 Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc), 2318 Expression => BPAR_Expr)); 2319 2320 if Uses_Transient_Scope then 2321 Pop_Scope; 2322 end if; 2323 end; 2324 2325 -- Now fix up the original assignment and continue processing 2326 2327 Rewrite (Prefix (Lhs), 2328 New_Occurrence_Of (Tnn, Loc)); 2329 2330 -- We do not need to reanalyze that assignment, and we do not need 2331 -- to worry about references to the temporary, but we do need to 2332 -- make sure that the temporary is not marked as a true constant 2333 -- since we now have a generated assignment to it. 2334 2335 Set_Is_True_Constant (Tnn, False); 2336 end; 2337 end if; 2338 2339 -- When we have the appropriate type of aggregate in the expression (it 2340 -- has been determined during analysis of the aggregate by setting the 2341 -- delay flag), let's perform in place assignment and thus avoid 2342 -- creating a temporary. 2343 2344 if Is_Delayed_Aggregate (Rhs) then 2345 Convert_Aggr_In_Assignment (N); 2346 Rewrite (N, Make_Null_Statement (Loc)); 2347 Analyze (N); 2348 2349 return; 2350 end if; 2351 2352 -- Apply discriminant check if required. If Lhs is an access type to a 2353 -- designated type with discriminants, we must always check. If the 2354 -- type has unknown discriminants, more elaborate processing below. 2355 2356 if Has_Discriminants (Etype (Lhs)) 2357 and then not Has_Unknown_Discriminants (Etype (Lhs)) 2358 then 2359 -- Skip discriminant check if change of representation. Will be 2360 -- done when the change of representation is expanded out. 2361 2362 if not Crep then 2363 Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs); 2364 end if; 2365 2366 -- If the type is private without discriminants, and the full type 2367 -- has discriminants (necessarily with defaults) a check may still be 2368 -- necessary if the Lhs is aliased. The private discriminants must be 2369 -- visible to build the discriminant constraints. 2370 2371 -- Only an explicit dereference that comes from source indicates 2372 -- aliasing. Access to formals of protected operations and entries 2373 -- create dereferences but are not semantic aliasings. 2374 2375 elsif Is_Private_Type (Etype (Lhs)) 2376 and then Has_Discriminants (Typ) 2377 and then Nkind (Lhs) = N_Explicit_Dereference 2378 and then Comes_From_Source (Lhs) 2379 then 2380 declare 2381 Lt : constant Entity_Id := Etype (Lhs); 2382 Ubt : Entity_Id := Base_Type (Typ); 2383 2384 begin 2385 -- In the case of an expander-generated record subtype whose base 2386 -- type still appears private, Typ will have been set to that 2387 -- private type rather than the underlying record type (because 2388 -- Underlying type will have returned the record subtype), so it's 2389 -- necessary to apply Underlying_Type again to the base type to 2390 -- get the record type we need for the discriminant check. Such 2391 -- subtypes can be created for assignments in certain cases, such 2392 -- as within an instantiation passed this kind of private type. 2393 -- It would be good to avoid this special test, but making changes 2394 -- to prevent this odd form of record subtype seems difficult. ??? 2395 2396 if Is_Private_Type (Ubt) then 2397 Ubt := Underlying_Type (Ubt); 2398 end if; 2399 2400 Set_Etype (Lhs, Ubt); 2401 Rewrite (Rhs, OK_Convert_To (Base_Type (Ubt), Rhs)); 2402 Apply_Discriminant_Check (Rhs, Ubt, Lhs); 2403 Set_Etype (Lhs, Lt); 2404 end; 2405 2406 -- If the Lhs has a private type with unknown discriminants, it may 2407 -- have a full view with discriminants, but those are nameable only 2408 -- in the underlying type, so convert the Rhs to it before potential 2409 -- checking. Convert Lhs as well, otherwise the actual subtype might 2410 -- not be constructible. If the discriminants have defaults the type 2411 -- is unconstrained and there is nothing to check. 2412 -- Ditto if a private type with unknown discriminants has a full view 2413 -- that is an unconstrained array, in which case a length check is 2414 -- needed. 2415 2416 elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs))) then 2417 if Has_Discriminants (Typ) 2418 and then not Has_Defaulted_Discriminants (Typ) 2419 then 2420 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs)); 2421 Rewrite (Lhs, OK_Convert_To (Base_Type (Typ), Lhs)); 2422 Apply_Discriminant_Check (Rhs, Typ, Lhs); 2423 2424 elsif Is_Array_Type (Typ) and then Is_Constrained (Typ) then 2425 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs)); 2426 Rewrite (Lhs, OK_Convert_To (Base_Type (Typ), Lhs)); 2427 Apply_Length_Check (Rhs, Typ); 2428 end if; 2429 2430 -- In the access type case, we need the same discriminant check, and 2431 -- also range checks if we have an access to constrained array. 2432 2433 elsif Is_Access_Type (Etype (Lhs)) 2434 and then Is_Constrained (Designated_Type (Etype (Lhs))) 2435 then 2436 if Has_Discriminants (Designated_Type (Etype (Lhs))) then 2437 2438 -- Skip discriminant check if change of representation. Will be 2439 -- done when the change of representation is expanded out. 2440 2441 if not Crep then 2442 Apply_Discriminant_Check (Rhs, Etype (Lhs)); 2443 end if; 2444 2445 elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then 2446 Apply_Range_Check (Rhs, Etype (Lhs)); 2447 2448 if Is_Constrained (Etype (Lhs)) then 2449 Apply_Length_Check (Rhs, Etype (Lhs)); 2450 end if; 2451 2452 if Nkind (Rhs) = N_Allocator then 2453 declare 2454 Target_Typ : constant Entity_Id := Etype (Expression (Rhs)); 2455 C_Es : Check_Result; 2456 2457 begin 2458 C_Es := 2459 Get_Range_Checks 2460 (Lhs, 2461 Target_Typ, 2462 Etype (Designated_Type (Etype (Lhs)))); 2463 2464 Insert_Range_Checks 2465 (C_Es, 2466 N, 2467 Target_Typ, 2468 Sloc (Lhs), 2469 Lhs); 2470 end; 2471 end if; 2472 end if; 2473 2474 -- Apply range check for access type case 2475 2476 elsif Is_Access_Type (Etype (Lhs)) 2477 and then Nkind (Rhs) = N_Allocator 2478 and then Nkind (Expression (Rhs)) = N_Qualified_Expression 2479 then 2480 Analyze_And_Resolve (Expression (Rhs)); 2481 Apply_Range_Check 2482 (Expression (Rhs), Designated_Type (Etype (Lhs))); 2483 end if; 2484 2485 -- Ada 2005 (AI-231): Generate the run-time check 2486 2487 if Is_Access_Type (Typ) 2488 and then Can_Never_Be_Null (Etype (Lhs)) 2489 and then not Can_Never_Be_Null (Etype (Rhs)) 2490 2491 -- If an actual is an out parameter of a null-excluding access 2492 -- type, there is access check on entry, so we set the flag 2493 -- Suppress_Assignment_Checks on the generated statement to 2494 -- assign the actual to the parameter block, and we do not want 2495 -- to generate an additional check at this point. 2496 2497 and then not Suppress_Assignment_Checks (N) 2498 then 2499 Apply_Constraint_Check (Rhs, Etype (Lhs)); 2500 end if; 2501 2502 -- Ada 2012 (AI05-148): Update current accessibility level if Rhs is a 2503 -- stand-alone obj of an anonymous access type. Do not install the check 2504 -- when the Lhs denotes a container cursor and the Next function employs 2505 -- an access type, because this can never result in a dangling pointer. 2506 2507 if Is_Access_Type (Typ) 2508 and then Is_Entity_Name (Lhs) 2509 and then Ekind (Entity (Lhs)) /= E_Loop_Parameter 2510 and then Present (Effective_Extra_Accessibility (Entity (Lhs))) 2511 then 2512 declare 2513 function Lhs_Entity return Entity_Id; 2514 -- Look through renames to find the underlying entity. 2515 -- For assignment to a rename, we don't care about the 2516 -- Enclosing_Dynamic_Scope of the rename declaration. 2517 2518 ---------------- 2519 -- Lhs_Entity -- 2520 ---------------- 2521 2522 function Lhs_Entity return Entity_Id is 2523 Result : Entity_Id := Entity (Lhs); 2524 2525 begin 2526 while Present (Renamed_Object (Result)) loop 2527 2528 -- Renamed_Object must return an Entity_Name here 2529 -- because of preceding "Present (E_E_A (...))" test. 2530 2531 Result := Entity (Renamed_Object (Result)); 2532 end loop; 2533 2534 return Result; 2535 end Lhs_Entity; 2536 2537 -- Local Declarations 2538 2539 Access_Check : constant Node_Id := 2540 Make_Raise_Program_Error (Loc, 2541 Condition => 2542 Make_Op_Gt (Loc, 2543 Left_Opnd => 2544 Dynamic_Accessibility_Level (Rhs), 2545 Right_Opnd => 2546 Make_Integer_Literal (Loc, 2547 Intval => 2548 Scope_Depth 2549 (Enclosing_Dynamic_Scope 2550 (Lhs_Entity)))), 2551 Reason => PE_Accessibility_Check_Failed); 2552 2553 Access_Level_Update : constant Node_Id := 2554 Make_Assignment_Statement (Loc, 2555 Name => 2556 New_Occurrence_Of 2557 (Effective_Extra_Accessibility 2558 (Entity (Lhs)), Loc), 2559 Expression => 2560 Dynamic_Accessibility_Level (Rhs)); 2561 2562 begin 2563 if not Accessibility_Checks_Suppressed (Entity (Lhs)) then 2564 Insert_Action (N, Access_Check); 2565 end if; 2566 2567 Insert_Action (N, Access_Level_Update); 2568 end; 2569 end if; 2570 2571 -- Case of assignment to a bit packed array element. If there is a 2572 -- change of representation this must be expanded into components, 2573 -- otherwise this is a bit-field assignment. 2574 2575 if Nkind (Lhs) = N_Indexed_Component 2576 and then Is_Bit_Packed_Array (Etype (Prefix (Lhs))) 2577 then 2578 -- Normal case, no change of representation 2579 2580 if not Crep then 2581 Expand_Bit_Packed_Element_Set (N); 2582 return; 2583 2584 -- Change of representation case 2585 2586 else 2587 -- Generate the following, to force component-by-component 2588 -- assignments in an efficient way. Otherwise each component 2589 -- will require a temporary and two bit-field manipulations. 2590 2591 -- T1 : Elmt_Type; 2592 -- T1 := RhS; 2593 -- Lhs := T1; 2594 2595 declare 2596 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T'); 2597 Stats : List_Id; 2598 2599 begin 2600 Stats := 2601 New_List ( 2602 Make_Object_Declaration (Loc, 2603 Defining_Identifier => Tnn, 2604 Object_Definition => 2605 New_Occurrence_Of (Etype (Lhs), Loc)), 2606 Make_Assignment_Statement (Loc, 2607 Name => New_Occurrence_Of (Tnn, Loc), 2608 Expression => Relocate_Node (Rhs)), 2609 Make_Assignment_Statement (Loc, 2610 Name => Relocate_Node (Lhs), 2611 Expression => New_Occurrence_Of (Tnn, Loc))); 2612 2613 Insert_Actions (N, Stats); 2614 Rewrite (N, Make_Null_Statement (Loc)); 2615 Analyze (N); 2616 end; 2617 end if; 2618 2619 -- Build-in-place function call case. This is for assignment statements 2620 -- that come from aggregate component associations or from init procs. 2621 -- User-written assignment statements with b-i-p calls are handled 2622 -- elsewhere. 2623 2624 elsif Is_Build_In_Place_Function_Call (Rhs) then 2625 pragma Assert (not Comes_From_Source (N)); 2626 Make_Build_In_Place_Call_In_Assignment (N, Rhs); 2627 2628 elsif Is_Tagged_Type (Typ) 2629 or else (Needs_Finalization (Typ) and then not Is_Array_Type (Typ)) 2630 then 2631 Tagged_Case : declare 2632 L : List_Id := No_List; 2633 Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N); 2634 2635 begin 2636 -- In the controlled case, we ensure that function calls are 2637 -- evaluated before finalizing the target. In all cases, it makes 2638 -- the expansion easier if the side effects are removed first. 2639 2640 Remove_Side_Effects (Lhs); 2641 Remove_Side_Effects (Rhs); 2642 2643 -- Avoid recursion in the mechanism 2644 2645 Set_Analyzed (N); 2646 2647 -- If dispatching assignment, we need to dispatch to _assign 2648 2649 if Is_Class_Wide_Type (Typ) 2650 2651 -- If the type is tagged, we may as well use the predefined 2652 -- primitive assignment. This avoids inlining a lot of code 2653 -- and in the class-wide case, the assignment is replaced 2654 -- by a dispatching call to _assign. It is suppressed in the 2655 -- case of assignments created by the expander that correspond 2656 -- to initializations, where we do want to copy the tag 2657 -- (Expand_Ctrl_Actions flag is set False in this case). It is 2658 -- also suppressed if restriction No_Dispatching_Calls is in 2659 -- force because in that case predefined primitives are not 2660 -- generated. 2661 2662 or else (Is_Tagged_Type (Typ) 2663 and then Chars (Current_Scope) /= Name_uAssign 2664 and then Expand_Ctrl_Actions 2665 and then 2666 not Restriction_Active (No_Dispatching_Calls)) 2667 then 2668 if Is_Limited_Type (Typ) then 2669 2670 -- This can happen in an instance when the formal is an 2671 -- extension of a limited interface, and the actual is 2672 -- limited. This is an error according to AI05-0087, but 2673 -- is not caught at the point of instantiation in earlier 2674 -- versions. We also must verify that the limited type does 2675 -- not come from source as corner cases may exist where 2676 -- an assignment was not intended like the pathological case 2677 -- of a raise expression within a return statement. 2678 2679 -- This is wrong, error messages cannot be issued during 2680 -- expansion, since they would be missed in -gnatc mode ??? 2681 2682 if Comes_From_Source (N) then 2683 Error_Msg_N 2684 ("assignment not available on limited type", N); 2685 end if; 2686 2687 return; 2688 end if; 2689 2690 -- Fetch the primitive op _assign and proper type to call it. 2691 -- Because of possible conflicts between private and full view, 2692 -- fetch the proper type directly from the operation profile. 2693 2694 declare 2695 Op : constant Entity_Id := 2696 Find_Prim_Op (Typ, Name_uAssign); 2697 F_Typ : Entity_Id := Etype (First_Formal (Op)); 2698 2699 begin 2700 -- If the assignment is dispatching, make sure to use the 2701 -- proper type. 2702 2703 if Is_Class_Wide_Type (Typ) then 2704 F_Typ := Class_Wide_Type (F_Typ); 2705 end if; 2706 2707 L := New_List; 2708 2709 -- In case of assignment to a class-wide tagged type, before 2710 -- the assignment we generate run-time check to ensure that 2711 -- the tags of source and target match. 2712 2713 if not Tag_Checks_Suppressed (Typ) 2714 and then Is_Class_Wide_Type (Typ) 2715 and then Is_Tagged_Type (Typ) 2716 and then Is_Tagged_Type (Underlying_Type (Etype (Rhs))) 2717 then 2718 declare 2719 Lhs_Tag : Node_Id; 2720 Rhs_Tag : Node_Id; 2721 2722 begin 2723 if not Is_Interface (Typ) then 2724 Lhs_Tag := 2725 Make_Selected_Component (Loc, 2726 Prefix => Duplicate_Subexpr (Lhs), 2727 Selector_Name => 2728 Make_Identifier (Loc, Name_uTag)); 2729 Rhs_Tag := 2730 Make_Selected_Component (Loc, 2731 Prefix => Duplicate_Subexpr (Rhs), 2732 Selector_Name => 2733 Make_Identifier (Loc, Name_uTag)); 2734 else 2735 -- Displace the pointer to the base of the objects 2736 -- applying 'Address, which is later expanded into 2737 -- a call to RE_Base_Address. 2738 2739 Lhs_Tag := 2740 Make_Explicit_Dereference (Loc, 2741 Prefix => 2742 Unchecked_Convert_To (RTE (RE_Tag_Ptr), 2743 Make_Attribute_Reference (Loc, 2744 Prefix => Duplicate_Subexpr (Lhs), 2745 Attribute_Name => Name_Address))); 2746 Rhs_Tag := 2747 Make_Explicit_Dereference (Loc, 2748 Prefix => 2749 Unchecked_Convert_To (RTE (RE_Tag_Ptr), 2750 Make_Attribute_Reference (Loc, 2751 Prefix => Duplicate_Subexpr (Rhs), 2752 Attribute_Name => Name_Address))); 2753 end if; 2754 2755 Append_To (L, 2756 Make_Raise_Constraint_Error (Loc, 2757 Condition => 2758 Make_Op_Ne (Loc, 2759 Left_Opnd => Lhs_Tag, 2760 Right_Opnd => Rhs_Tag), 2761 Reason => CE_Tag_Check_Failed)); 2762 end; 2763 end if; 2764 2765 declare 2766 Left_N : Node_Id := Duplicate_Subexpr (Lhs); 2767 Right_N : Node_Id := Duplicate_Subexpr (Rhs); 2768 2769 begin 2770 -- In order to dispatch the call to _assign the type of 2771 -- the actuals must match. Add conversion (if required). 2772 2773 if Etype (Lhs) /= F_Typ then 2774 Left_N := Unchecked_Convert_To (F_Typ, Left_N); 2775 end if; 2776 2777 if Etype (Rhs) /= F_Typ then 2778 Right_N := Unchecked_Convert_To (F_Typ, Right_N); 2779 end if; 2780 2781 Append_To (L, 2782 Make_Procedure_Call_Statement (Loc, 2783 Name => New_Occurrence_Of (Op, Loc), 2784 Parameter_Associations => New_List ( 2785 Node1 => Left_N, 2786 Node2 => Right_N))); 2787 end; 2788 end; 2789 2790 else 2791 L := Make_Tag_Ctrl_Assignment (N); 2792 2793 -- We can't afford to have destructive Finalization Actions in 2794 -- the Self assignment case, so if the target and the source 2795 -- are not obviously different, code is generated to avoid the 2796 -- self assignment case: 2797 2798 -- if lhs'address /= rhs'address then 2799 -- <code for controlled and/or tagged assignment> 2800 -- end if; 2801 2802 -- Skip this if Restriction (No_Finalization) is active 2803 2804 if not Statically_Different (Lhs, Rhs) 2805 and then Expand_Ctrl_Actions 2806 and then not Restriction_Active (No_Finalization) 2807 then 2808 L := New_List ( 2809 Make_Implicit_If_Statement (N, 2810 Condition => 2811 Make_Op_Ne (Loc, 2812 Left_Opnd => 2813 Make_Attribute_Reference (Loc, 2814 Prefix => Duplicate_Subexpr (Lhs), 2815 Attribute_Name => Name_Address), 2816 2817 Right_Opnd => 2818 Make_Attribute_Reference (Loc, 2819 Prefix => Duplicate_Subexpr (Rhs), 2820 Attribute_Name => Name_Address)), 2821 2822 Then_Statements => L)); 2823 end if; 2824 2825 -- We need to set up an exception handler for implementing 2826 -- 7.6.1(18). The remaining adjustments are tackled by the 2827 -- implementation of adjust for record_controllers (see 2828 -- s-finimp.adb). 2829 2830 -- This is skipped if we have no finalization 2831 2832 if Expand_Ctrl_Actions 2833 and then not Restriction_Active (No_Finalization) 2834 then 2835 L := New_List ( 2836 Make_Block_Statement (Loc, 2837 Handled_Statement_Sequence => 2838 Make_Handled_Sequence_Of_Statements (Loc, 2839 Statements => L, 2840 Exception_Handlers => New_List ( 2841 Make_Handler_For_Ctrl_Operation (Loc))))); 2842 end if; 2843 end if; 2844 2845 Rewrite (N, 2846 Make_Block_Statement (Loc, 2847 Handled_Statement_Sequence => 2848 Make_Handled_Sequence_Of_Statements (Loc, Statements => L))); 2849 2850 -- If no restrictions on aborts, protect the whole assignment 2851 -- for controlled objects as per 9.8(11). 2852 2853 if Needs_Finalization (Typ) 2854 and then Expand_Ctrl_Actions 2855 and then Abort_Allowed 2856 then 2857 declare 2858 Blk : constant Entity_Id := 2859 New_Internal_Entity 2860 (E_Block, Current_Scope, Sloc (N), 'B'); 2861 AUD : constant Entity_Id := RTE (RE_Abort_Undefer_Direct); 2862 2863 begin 2864 Set_Is_Abort_Block (N); 2865 2866 Set_Scope (Blk, Current_Scope); 2867 Set_Etype (Blk, Standard_Void_Type); 2868 Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N))); 2869 2870 Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer)); 2871 Set_At_End_Proc (Handled_Statement_Sequence (N), 2872 New_Occurrence_Of (AUD, Loc)); 2873 2874 -- Present the Abort_Undefer_Direct function to the backend 2875 -- so that it can inline the call to the function. 2876 2877 Add_Inlined_Body (AUD, N); 2878 2879 Expand_At_End_Handler 2880 (Handled_Statement_Sequence (N), Blk); 2881 end; 2882 end if; 2883 2884 -- N has been rewritten to a block statement for which it is 2885 -- known by construction that no checks are necessary: analyze 2886 -- it with all checks suppressed. 2887 2888 Analyze (N, Suppress => All_Checks); 2889 return; 2890 end Tagged_Case; 2891 2892 -- Array types 2893 2894 elsif Is_Array_Type (Typ) then 2895 declare 2896 Actual_Rhs : Node_Id := Rhs; 2897 2898 begin 2899 while Nkind_In (Actual_Rhs, N_Type_Conversion, 2900 N_Qualified_Expression) 2901 loop 2902 Actual_Rhs := Expression (Actual_Rhs); 2903 end loop; 2904 2905 Expand_Assign_Array (N, Actual_Rhs); 2906 return; 2907 end; 2908 2909 -- Record types 2910 2911 elsif Is_Record_Type (Typ) then 2912 Expand_Assign_Record (N); 2913 return; 2914 2915 -- Scalar types. This is where we perform the processing related to the 2916 -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid 2917 -- scalar values. 2918 2919 elsif Is_Scalar_Type (Typ) then 2920 2921 -- Case where right side is known valid 2922 2923 if Expr_Known_Valid (Rhs) then 2924 2925 -- Here the right side is valid, so it is fine. The case to deal 2926 -- with is when the left side is a local variable reference whose 2927 -- value is not currently known to be valid. If this is the case, 2928 -- and the assignment appears in an unconditional context, then 2929 -- we can mark the left side as now being valid if one of these 2930 -- conditions holds: 2931 2932 -- The expression of the right side has Do_Range_Check set so 2933 -- that we know a range check will be performed. Note that it 2934 -- can be the case that a range check is omitted because we 2935 -- make the assumption that we can assume validity for operands 2936 -- appearing in the right side in determining whether a range 2937 -- check is required 2938 2939 -- The subtype of the right side matches the subtype of the 2940 -- left side. In this case, even though we have not checked 2941 -- the range of the right side, we know it is in range of its 2942 -- subtype if the expression is valid. 2943 2944 if Is_Local_Variable_Reference (Lhs) 2945 and then not Is_Known_Valid (Entity (Lhs)) 2946 and then In_Unconditional_Context (N) 2947 then 2948 if Do_Range_Check (Rhs) 2949 or else Etype (Lhs) = Etype (Rhs) 2950 then 2951 Set_Is_Known_Valid (Entity (Lhs), True); 2952 end if; 2953 end if; 2954 2955 -- Case where right side may be invalid in the sense of the RM 2956 -- reference above. The RM does not require that we check for the 2957 -- validity on an assignment, but it does require that the assignment 2958 -- of an invalid value not cause erroneous behavior. 2959 2960 -- The general approach in GNAT is to use the Is_Known_Valid flag 2961 -- to avoid the need for validity checking on assignments. However 2962 -- in some cases, we have to do validity checking in order to make 2963 -- sure that the setting of this flag is correct. 2964 2965 else 2966 -- Validate right side if we are validating copies 2967 2968 if Validity_Checks_On 2969 and then Validity_Check_Copies 2970 then 2971 -- Skip this if left-hand side is an array or record component 2972 -- and elementary component validity checks are suppressed. 2973 2974 if Nkind_In (Lhs, N_Selected_Component, N_Indexed_Component) 2975 and then not Validity_Check_Components 2976 then 2977 null; 2978 else 2979 Ensure_Valid (Rhs); 2980 end if; 2981 2982 -- We can propagate this to the left side where appropriate 2983 2984 if Is_Local_Variable_Reference (Lhs) 2985 and then not Is_Known_Valid (Entity (Lhs)) 2986 and then In_Unconditional_Context (N) 2987 then 2988 Set_Is_Known_Valid (Entity (Lhs), True); 2989 end if; 2990 2991 -- Otherwise check to see what should be done 2992 2993 -- If left side is a local variable, then we just set its flag to 2994 -- indicate that its value may no longer be valid, since we are 2995 -- copying a potentially invalid value. 2996 2997 elsif Is_Local_Variable_Reference (Lhs) then 2998 Set_Is_Known_Valid (Entity (Lhs), False); 2999 3000 -- Check for case of a nonlocal variable on the left side which 3001 -- is currently known to be valid. In this case, we simply ensure 3002 -- that the right side is valid. We only play the game of copying 3003 -- validity status for local variables, since we are doing this 3004 -- statically, not by tracing the full flow graph. 3005 3006 elsif Is_Entity_Name (Lhs) 3007 and then Is_Known_Valid (Entity (Lhs)) 3008 then 3009 -- Note: If Validity_Checking mode is set to none, we ignore 3010 -- the Ensure_Valid call so don't worry about that case here. 3011 3012 Ensure_Valid (Rhs); 3013 3014 -- In all other cases, we can safely copy an invalid value without 3015 -- worrying about the status of the left side. Since it is not a 3016 -- variable reference it will not be considered 3017 -- as being known to be valid in any case. 3018 3019 else 3020 null; 3021 end if; 3022 end if; 3023 end if; 3024 3025 exception 3026 when RE_Not_Available => 3027 return; 3028 end Expand_N_Assignment_Statement; 3029 3030 ------------------------------ 3031 -- Expand_N_Block_Statement -- 3032 ------------------------------ 3033 3034 -- Encode entity names defined in block statement 3035 3036 procedure Expand_N_Block_Statement (N : Node_Id) is 3037 begin 3038 Qualify_Entity_Names (N); 3039 end Expand_N_Block_Statement; 3040 3041 ----------------------------- 3042 -- Expand_N_Case_Statement -- 3043 ----------------------------- 3044 3045 procedure Expand_N_Case_Statement (N : Node_Id) is 3046 Loc : constant Source_Ptr := Sloc (N); 3047 Expr : constant Node_Id := Expression (N); 3048 From_Cond_Expr : constant Boolean := From_Conditional_Expression (N); 3049 Alt : Node_Id; 3050 Len : Nat; 3051 Cond : Node_Id; 3052 Choice : Node_Id; 3053 Chlist : List_Id; 3054 3055 begin 3056 -- Check for the situation where we know at compile time which branch 3057 -- will be taken. 3058 3059 -- If the value is static but its subtype is predicated and the value 3060 -- does not obey the predicate, the value is marked non-static, and 3061 -- there can be no corresponding static alternative. In that case we 3062 -- replace the case statement with an exception, regardless of whether 3063 -- assertions are enabled or not, unless predicates are ignored. 3064 3065 if Compile_Time_Known_Value (Expr) 3066 and then Has_Predicates (Etype (Expr)) 3067 and then not Predicates_Ignored (Etype (Expr)) 3068 and then not Is_OK_Static_Expression (Expr) 3069 then 3070 Rewrite (N, 3071 Make_Raise_Constraint_Error (Loc, Reason => CE_Invalid_Data)); 3072 Analyze (N); 3073 return; 3074 3075 elsif Compile_Time_Known_Value (Expr) 3076 and then (not Has_Predicates (Etype (Expr)) 3077 or else Is_Static_Expression (Expr)) 3078 then 3079 Alt := Find_Static_Alternative (N); 3080 3081 -- Do not consider controlled objects found in a case statement which 3082 -- actually models a case expression because their early finalization 3083 -- will affect the result of the expression. 3084 3085 if not From_Conditional_Expression (N) then 3086 Process_Statements_For_Controlled_Objects (Alt); 3087 end if; 3088 3089 -- Move statements from this alternative after the case statement. 3090 -- They are already analyzed, so will be skipped by the analyzer. 3091 3092 Insert_List_After (N, Statements (Alt)); 3093 3094 -- That leaves the case statement as a shell. So now we can kill all 3095 -- other alternatives in the case statement. 3096 3097 Kill_Dead_Code (Expression (N)); 3098 3099 declare 3100 Dead_Alt : Node_Id; 3101 3102 begin 3103 -- Loop through case alternatives, skipping pragmas, and skipping 3104 -- the one alternative that we select (and therefore retain). 3105 3106 Dead_Alt := First (Alternatives (N)); 3107 while Present (Dead_Alt) loop 3108 if Dead_Alt /= Alt 3109 and then Nkind (Dead_Alt) = N_Case_Statement_Alternative 3110 then 3111 Kill_Dead_Code (Statements (Dead_Alt), Warn_On_Deleted_Code); 3112 end if; 3113 3114 Next (Dead_Alt); 3115 end loop; 3116 end; 3117 3118 Rewrite (N, Make_Null_Statement (Loc)); 3119 return; 3120 end if; 3121 3122 -- Here if the choice is not determined at compile time 3123 3124 declare 3125 Last_Alt : constant Node_Id := Last (Alternatives (N)); 3126 3127 Others_Present : Boolean; 3128 Others_Node : Node_Id; 3129 3130 Then_Stms : List_Id; 3131 Else_Stms : List_Id; 3132 3133 begin 3134 if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then 3135 Others_Present := True; 3136 Others_Node := Last_Alt; 3137 else 3138 Others_Present := False; 3139 end if; 3140 3141 -- First step is to worry about possible invalid argument. The RM 3142 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is 3143 -- outside the base range), then Constraint_Error must be raised. 3144 3145 -- Case of validity check required (validity checks are on, the 3146 -- expression is not known to be valid, and the case statement 3147 -- comes from source -- no need to validity check internally 3148 -- generated case statements). 3149 3150 if Validity_Check_Default 3151 and then not Predicates_Ignored (Etype (Expr)) 3152 then 3153 Ensure_Valid (Expr); 3154 end if; 3155 3156 -- If there is only a single alternative, just replace it with the 3157 -- sequence of statements since obviously that is what is going to 3158 -- be executed in all cases. 3159 3160 Len := List_Length (Alternatives (N)); 3161 3162 if Len = 1 then 3163 3164 -- We still need to evaluate the expression if it has any side 3165 -- effects. 3166 3167 Remove_Side_Effects (Expression (N)); 3168 Alt := First (Alternatives (N)); 3169 3170 -- Do not consider controlled objects found in a case statement 3171 -- which actually models a case expression because their early 3172 -- finalization will affect the result of the expression. 3173 3174 if not From_Conditional_Expression (N) then 3175 Process_Statements_For_Controlled_Objects (Alt); 3176 end if; 3177 3178 Insert_List_After (N, Statements (Alt)); 3179 3180 -- That leaves the case statement as a shell. The alternative that 3181 -- will be executed is reset to a null list. So now we can kill 3182 -- the entire case statement. 3183 3184 Kill_Dead_Code (Expression (N)); 3185 Rewrite (N, Make_Null_Statement (Loc)); 3186 return; 3187 3188 -- An optimization. If there are only two alternatives, and only 3189 -- a single choice, then rewrite the whole case statement as an 3190 -- if statement, since this can result in subsequent optimizations. 3191 -- This helps not only with case statements in the source of a 3192 -- simple form, but also with generated code (discriminant check 3193 -- functions in particular). 3194 3195 -- Note: it is OK to do this before expanding out choices for any 3196 -- static predicates, since the if statement processing will handle 3197 -- the static predicate case fine. 3198 3199 elsif Len = 2 then 3200 Chlist := Discrete_Choices (First (Alternatives (N))); 3201 3202 if List_Length (Chlist) = 1 then 3203 Choice := First (Chlist); 3204 3205 Then_Stms := Statements (First (Alternatives (N))); 3206 Else_Stms := Statements (Last (Alternatives (N))); 3207 3208 -- For TRUE, generate "expression", not expression = true 3209 3210 if Nkind (Choice) = N_Identifier 3211 and then Entity (Choice) = Standard_True 3212 then 3213 Cond := Expression (N); 3214 3215 -- For FALSE, generate "expression" and switch then/else 3216 3217 elsif Nkind (Choice) = N_Identifier 3218 and then Entity (Choice) = Standard_False 3219 then 3220 Cond := Expression (N); 3221 Else_Stms := Statements (First (Alternatives (N))); 3222 Then_Stms := Statements (Last (Alternatives (N))); 3223 3224 -- For a range, generate "expression in range" 3225 3226 elsif Nkind (Choice) = N_Range 3227 or else (Nkind (Choice) = N_Attribute_Reference 3228 and then Attribute_Name (Choice) = Name_Range) 3229 or else (Is_Entity_Name (Choice) 3230 and then Is_Type (Entity (Choice))) 3231 then 3232 Cond := 3233 Make_In (Loc, 3234 Left_Opnd => Expression (N), 3235 Right_Opnd => Relocate_Node (Choice)); 3236 3237 -- A subtype indication is not a legal operator in a membership 3238 -- test, so retrieve its range. 3239 3240 elsif Nkind (Choice) = N_Subtype_Indication then 3241 Cond := 3242 Make_In (Loc, 3243 Left_Opnd => Expression (N), 3244 Right_Opnd => 3245 Relocate_Node 3246 (Range_Expression (Constraint (Choice)))); 3247 3248 -- For any other subexpression "expression = value" 3249 3250 else 3251 Cond := 3252 Make_Op_Eq (Loc, 3253 Left_Opnd => Expression (N), 3254 Right_Opnd => Relocate_Node (Choice)); 3255 end if; 3256 3257 -- Now rewrite the case as an IF 3258 3259 Rewrite (N, 3260 Make_If_Statement (Loc, 3261 Condition => Cond, 3262 Then_Statements => Then_Stms, 3263 Else_Statements => Else_Stms)); 3264 3265 -- The rewritten if statement needs to inherit whether the 3266 -- case statement was expanded from a conditional expression, 3267 -- for proper handling of nested controlled objects. 3268 3269 Set_From_Conditional_Expression (N, From_Cond_Expr); 3270 3271 Analyze (N); 3272 3273 return; 3274 end if; 3275 end if; 3276 3277 -- If the last alternative is not an Others choice, replace it with 3278 -- an N_Others_Choice. Note that we do not bother to call Analyze on 3279 -- the modified case statement, since it's only effect would be to 3280 -- compute the contents of the Others_Discrete_Choices which is not 3281 -- needed by the back end anyway. 3282 3283 -- The reason for this is that the back end always needs some default 3284 -- for a switch, so if we have not supplied one in the processing 3285 -- above for validity checking, then we need to supply one here. 3286 3287 if not Others_Present then 3288 Others_Node := Make_Others_Choice (Sloc (Last_Alt)); 3289 3290 -- If Predicates_Ignored is true the value does not satisfy the 3291 -- predicate, and there is no Others choice, Constraint_Error 3292 -- must be raised (4.5.7 (21/3)). 3293 3294 if Predicates_Ignored (Etype (Expr)) then 3295 declare 3296 Except : constant Node_Id := 3297 Make_Raise_Constraint_Error (Loc, 3298 Reason => CE_Invalid_Data); 3299 New_Alt : constant Node_Id := 3300 Make_Case_Statement_Alternative (Loc, 3301 Discrete_Choices => New_List ( 3302 Make_Others_Choice (Loc)), 3303 Statements => New_List (Except)); 3304 3305 begin 3306 Append (New_Alt, Alternatives (N)); 3307 Analyze_And_Resolve (Except); 3308 end; 3309 3310 else 3311 Set_Others_Discrete_Choices 3312 (Others_Node, Discrete_Choices (Last_Alt)); 3313 Set_Discrete_Choices (Last_Alt, New_List (Others_Node)); 3314 end if; 3315 3316 end if; 3317 3318 -- Deal with possible declarations of controlled objects, and also 3319 -- with rewriting choice sequences for static predicate references. 3320 3321 Alt := First_Non_Pragma (Alternatives (N)); 3322 while Present (Alt) loop 3323 3324 -- Do not consider controlled objects found in a case statement 3325 -- which actually models a case expression because their early 3326 -- finalization will affect the result of the expression. 3327 3328 if not From_Conditional_Expression (N) then 3329 Process_Statements_For_Controlled_Objects (Alt); 3330 end if; 3331 3332 if Has_SP_Choice (Alt) then 3333 Expand_Static_Predicates_In_Choices (Alt); 3334 end if; 3335 3336 Next_Non_Pragma (Alt); 3337 end loop; 3338 end; 3339 end Expand_N_Case_Statement; 3340 3341 ----------------------------- 3342 -- Expand_N_Exit_Statement -- 3343 ----------------------------- 3344 3345 -- The only processing required is to deal with a possible C/Fortran 3346 -- boolean value used as the condition for the exit statement. 3347 3348 procedure Expand_N_Exit_Statement (N : Node_Id) is 3349 begin 3350 Adjust_Condition (Condition (N)); 3351 end Expand_N_Exit_Statement; 3352 3353 ---------------------------------- 3354 -- Expand_Formal_Container_Loop -- 3355 ---------------------------------- 3356 3357 procedure Expand_Formal_Container_Loop (N : Node_Id) is 3358 Loc : constant Source_Ptr := Sloc (N); 3359 Isc : constant Node_Id := Iteration_Scheme (N); 3360 I_Spec : constant Node_Id := Iterator_Specification (Isc); 3361 Cursor : constant Entity_Id := Defining_Identifier (I_Spec); 3362 Container : constant Node_Id := Entity (Name (I_Spec)); 3363 Stats : constant List_Id := Statements (N); 3364 3365 Advance : Node_Id; 3366 Init_Decl : Node_Id; 3367 Init_Name : Entity_Id; 3368 New_Loop : Node_Id; 3369 3370 begin 3371 -- The expansion of a formal container loop resembles the one for Ada 3372 -- containers. The only difference is that the primitives mention the 3373 -- domain of iteration explicitly, and function First applied to the 3374 -- container yields a cursor directly. 3375 3376 -- Cursor : Cursor_type := First (Container); 3377 -- while Has_Element (Cursor, Container) loop 3378 -- <original loop statements> 3379 -- Cursor := Next (Container, Cursor); 3380 -- end loop; 3381 3382 Build_Formal_Container_Iteration 3383 (N, Container, Cursor, Init_Decl, Advance, New_Loop); 3384 3385 Append_To (Stats, Advance); 3386 3387 -- Build a block to capture declaration of the cursor 3388 3389 Rewrite (N, 3390 Make_Block_Statement (Loc, 3391 Declarations => New_List (Init_Decl), 3392 Handled_Statement_Sequence => 3393 Make_Handled_Sequence_Of_Statements (Loc, 3394 Statements => New_List (New_Loop)))); 3395 3396 -- The loop parameter is declared by an object declaration, but within 3397 -- the loop we must prevent user assignments to it, so we analyze the 3398 -- declaration and reset the entity kind, before analyzing the rest of 3399 -- the loop. 3400 3401 Analyze (Init_Decl); 3402 Init_Name := Defining_Identifier (Init_Decl); 3403 Set_Ekind (Init_Name, E_Loop_Parameter); 3404 3405 -- The cursor was marked as a loop parameter to prevent user assignments 3406 -- to it, however this renders the advancement step illegal as it is not 3407 -- possible to change the value of a constant. Flag the advancement step 3408 -- as a legal form of assignment to remedy this side effect. 3409 3410 Set_Assignment_OK (Name (Advance)); 3411 Analyze (N); 3412 3413 -- Because we have to analyze the initial declaration of the loop 3414 -- parameter multiple times its scope is incorrectly set at this point 3415 -- to the one surrounding the block statement - so set the scope 3416 -- manually to be the actual block statement, and indicate that it is 3417 -- not visible after the block has been analyzed. 3418 3419 Set_Scope (Init_Name, Entity (Identifier (N))); 3420 Set_Is_Immediately_Visible (Init_Name, False); 3421 end Expand_Formal_Container_Loop; 3422 3423 ------------------------------------------ 3424 -- Expand_Formal_Container_Element_Loop -- 3425 ------------------------------------------ 3426 3427 procedure Expand_Formal_Container_Element_Loop (N : Node_Id) is 3428 Loc : constant Source_Ptr := Sloc (N); 3429 Isc : constant Node_Id := Iteration_Scheme (N); 3430 I_Spec : constant Node_Id := Iterator_Specification (Isc); 3431 Element : constant Entity_Id := Defining_Identifier (I_Spec); 3432 Container : constant Node_Id := Entity (Name (I_Spec)); 3433 Container_Typ : constant Entity_Id := Base_Type (Etype (Container)); 3434 Stats : constant List_Id := Statements (N); 3435 3436 Cursor : constant Entity_Id := 3437 Make_Defining_Identifier (Loc, 3438 Chars => New_External_Name (Chars (Element), 'C')); 3439 Elmt_Decl : Node_Id; 3440 Elmt_Ref : Node_Id; 3441 3442 Element_Op : constant Entity_Id := 3443 Get_Iterable_Type_Primitive (Container_Typ, Name_Element); 3444 3445 Advance : Node_Id; 3446 Init : Node_Id; 3447 New_Loop : Node_Id; 3448 3449 begin 3450 -- For an element iterator, the Element aspect must be present, 3451 -- (this is checked during analysis) and the expansion takes the form: 3452 3453 -- Cursor : Cursor_Type := First (Container); 3454 -- Elmt : Element_Type; 3455 -- while Has_Element (Cursor, Container) loop 3456 -- Elmt := Element (Container, Cursor); 3457 -- <original loop statements> 3458 -- Cursor := Next (Container, Cursor); 3459 -- end loop; 3460 3461 -- However this expansion is not legal if the element is indefinite. 3462 -- In that case we create a block to hold a variable declaration 3463 -- initialized with a call to Element, and generate: 3464 3465 -- Cursor : Cursor_Type := First (Container); 3466 -- while Has_Element (Cursor, Container) loop 3467 -- declare 3468 -- Elmt : Element_Type := Element (Container, Cursor); 3469 -- begin 3470 -- <original loop statements> 3471 -- Cursor := Next (Container, Cursor); 3472 -- end; 3473 -- end loop; 3474 3475 Build_Formal_Container_Iteration 3476 (N, Container, Cursor, Init, Advance, New_Loop); 3477 Append_To (Stats, Advance); 3478 3479 Set_Ekind (Cursor, E_Variable); 3480 Insert_Action (N, Init); 3481 3482 -- The loop parameter is declared by an object declaration, but within 3483 -- the loop we must prevent user assignments to it; the following flag 3484 -- accomplishes that. 3485 3486 Set_Is_Loop_Parameter (Element); 3487 3488 -- Declaration for Element 3489 3490 Elmt_Decl := 3491 Make_Object_Declaration (Loc, 3492 Defining_Identifier => Element, 3493 Object_Definition => New_Occurrence_Of (Etype (Element_Op), Loc)); 3494 3495 if not Is_Constrained (Etype (Element_Op)) then 3496 Set_Expression (Elmt_Decl, 3497 Make_Function_Call (Loc, 3498 Name => New_Occurrence_Of (Element_Op, Loc), 3499 Parameter_Associations => New_List ( 3500 Convert_To_Iterable_Type (Container, Loc), 3501 New_Occurrence_Of (Cursor, Loc)))); 3502 3503 Set_Statements (New_Loop, 3504 New_List 3505 (Make_Block_Statement (Loc, 3506 Declarations => New_List (Elmt_Decl), 3507 Handled_Statement_Sequence => 3508 Make_Handled_Sequence_Of_Statements (Loc, 3509 Statements => Stats)))); 3510 3511 else 3512 Elmt_Ref := 3513 Make_Assignment_Statement (Loc, 3514 Name => New_Occurrence_Of (Element, Loc), 3515 Expression => 3516 Make_Function_Call (Loc, 3517 Name => New_Occurrence_Of (Element_Op, Loc), 3518 Parameter_Associations => New_List ( 3519 Convert_To_Iterable_Type (Container, Loc), 3520 New_Occurrence_Of (Cursor, Loc)))); 3521 3522 Prepend (Elmt_Ref, Stats); 3523 3524 -- The element is assignable in the expanded code 3525 3526 Set_Assignment_OK (Name (Elmt_Ref)); 3527 3528 -- The loop is rewritten as a block, to hold the element declaration 3529 3530 New_Loop := 3531 Make_Block_Statement (Loc, 3532 Declarations => New_List (Elmt_Decl), 3533 Handled_Statement_Sequence => 3534 Make_Handled_Sequence_Of_Statements (Loc, 3535 Statements => New_List (New_Loop))); 3536 end if; 3537 3538 -- The element is only modified in expanded code, so it appears as 3539 -- unassigned to the warning machinery. We must suppress this spurious 3540 -- warning explicitly. 3541 3542 Set_Warnings_Off (Element); 3543 3544 Rewrite (N, New_Loop); 3545 Analyze (N); 3546 end Expand_Formal_Container_Element_Loop; 3547 3548 ----------------------------- 3549 -- Expand_N_Goto_Statement -- 3550 ----------------------------- 3551 3552 -- Add poll before goto if polling active 3553 3554 procedure Expand_N_Goto_Statement (N : Node_Id) is 3555 begin 3556 Generate_Poll_Call (N); 3557 end Expand_N_Goto_Statement; 3558 3559 --------------------------- 3560 -- Expand_N_If_Statement -- 3561 --------------------------- 3562 3563 -- First we deal with the case of C and Fortran convention boolean values, 3564 -- with zero/non-zero semantics. 3565 3566 -- Second, we deal with the obvious rewriting for the cases where the 3567 -- condition of the IF is known at compile time to be True or False. 3568 3569 -- Third, we remove elsif parts which have non-empty Condition_Actions and 3570 -- rewrite as independent if statements. For example: 3571 3572 -- if x then xs 3573 -- elsif y then ys 3574 -- ... 3575 -- end if; 3576 3577 -- becomes 3578 -- 3579 -- if x then xs 3580 -- else 3581 -- <<condition actions of y>> 3582 -- if y then ys 3583 -- ... 3584 -- end if; 3585 -- end if; 3586 3587 -- This rewriting is needed if at least one elsif part has a non-empty 3588 -- Condition_Actions list. We also do the same processing if there is a 3589 -- constant condition in an elsif part (in conjunction with the first 3590 -- processing step mentioned above, for the recursive call made to deal 3591 -- with the created inner if, this deals with properly optimizing the 3592 -- cases of constant elsif conditions). 3593 3594 procedure Expand_N_If_Statement (N : Node_Id) is 3595 Loc : constant Source_Ptr := Sloc (N); 3596 Hed : Node_Id; 3597 E : Node_Id; 3598 New_If : Node_Id; 3599 3600 Warn_If_Deleted : constant Boolean := 3601 Warn_On_Deleted_Code and then Comes_From_Source (N); 3602 -- Indicates whether we want warnings when we delete branches of the 3603 -- if statement based on constant condition analysis. We never want 3604 -- these warnings for expander generated code. 3605 3606 begin 3607 -- Do not consider controlled objects found in an if statement which 3608 -- actually models an if expression because their early finalization 3609 -- will affect the result of the expression. 3610 3611 if not From_Conditional_Expression (N) then 3612 Process_Statements_For_Controlled_Objects (N); 3613 end if; 3614 3615 Adjust_Condition (Condition (N)); 3616 3617 -- The following loop deals with constant conditions for the IF. We 3618 -- need a loop because as we eliminate False conditions, we grab the 3619 -- first elsif condition and use it as the primary condition. 3620 3621 while Compile_Time_Known_Value (Condition (N)) loop 3622 3623 -- If condition is True, we can simply rewrite the if statement now 3624 -- by replacing it by the series of then statements. 3625 3626 if Is_True (Expr_Value (Condition (N))) then 3627 3628 -- All the else parts can be killed 3629 3630 Kill_Dead_Code (Elsif_Parts (N), Warn_If_Deleted); 3631 Kill_Dead_Code (Else_Statements (N), Warn_If_Deleted); 3632 3633 Hed := Remove_Head (Then_Statements (N)); 3634 Insert_List_After (N, Then_Statements (N)); 3635 Rewrite (N, Hed); 3636 return; 3637 3638 -- If condition is False, then we can delete the condition and 3639 -- the Then statements 3640 3641 else 3642 -- We do not delete the condition if constant condition warnings 3643 -- are enabled, since otherwise we end up deleting the desired 3644 -- warning. Of course the backend will get rid of this True/False 3645 -- test anyway, so nothing is lost here. 3646 3647 if not Constant_Condition_Warnings then 3648 Kill_Dead_Code (Condition (N)); 3649 end if; 3650 3651 Kill_Dead_Code (Then_Statements (N), Warn_If_Deleted); 3652 3653 -- If there are no elsif statements, then we simply replace the 3654 -- entire if statement by the sequence of else statements. 3655 3656 if No (Elsif_Parts (N)) then 3657 if No (Else_Statements (N)) 3658 or else Is_Empty_List (Else_Statements (N)) 3659 then 3660 Rewrite (N, 3661 Make_Null_Statement (Sloc (N))); 3662 else 3663 Hed := Remove_Head (Else_Statements (N)); 3664 Insert_List_After (N, Else_Statements (N)); 3665 Rewrite (N, Hed); 3666 end if; 3667 3668 return; 3669 3670 -- If there are elsif statements, the first of them becomes the 3671 -- if/then section of the rebuilt if statement This is the case 3672 -- where we loop to reprocess this copied condition. 3673 3674 else 3675 Hed := Remove_Head (Elsif_Parts (N)); 3676 Insert_Actions (N, Condition_Actions (Hed)); 3677 Set_Condition (N, Condition (Hed)); 3678 Set_Then_Statements (N, Then_Statements (Hed)); 3679 3680 -- Hed might have been captured as the condition determining 3681 -- the current value for an entity. Now it is detached from 3682 -- the tree, so a Current_Value pointer in the condition might 3683 -- need to be updated. 3684 3685 Set_Current_Value_Condition (N); 3686 3687 if Is_Empty_List (Elsif_Parts (N)) then 3688 Set_Elsif_Parts (N, No_List); 3689 end if; 3690 end if; 3691 end if; 3692 end loop; 3693 3694 -- Loop through elsif parts, dealing with constant conditions and 3695 -- possible condition actions that are present. 3696 3697 if Present (Elsif_Parts (N)) then 3698 E := First (Elsif_Parts (N)); 3699 while Present (E) loop 3700 3701 -- Do not consider controlled objects found in an if statement 3702 -- which actually models an if expression because their early 3703 -- finalization will affect the result of the expression. 3704 3705 if not From_Conditional_Expression (N) then 3706 Process_Statements_For_Controlled_Objects (E); 3707 end if; 3708 3709 Adjust_Condition (Condition (E)); 3710 3711 -- If there are condition actions, then rewrite the if statement 3712 -- as indicated above. We also do the same rewrite for a True or 3713 -- False condition. The further processing of this constant 3714 -- condition is then done by the recursive call to expand the 3715 -- newly created if statement 3716 3717 if Present (Condition_Actions (E)) 3718 or else Compile_Time_Known_Value (Condition (E)) 3719 then 3720 New_If := 3721 Make_If_Statement (Sloc (E), 3722 Condition => Condition (E), 3723 Then_Statements => Then_Statements (E), 3724 Elsif_Parts => No_List, 3725 Else_Statements => Else_Statements (N)); 3726 3727 -- Elsif parts for new if come from remaining elsif's of parent 3728 3729 while Present (Next (E)) loop 3730 if No (Elsif_Parts (New_If)) then 3731 Set_Elsif_Parts (New_If, New_List); 3732 end if; 3733 3734 Append (Remove_Next (E), Elsif_Parts (New_If)); 3735 end loop; 3736 3737 Set_Else_Statements (N, New_List (New_If)); 3738 3739 if Present (Condition_Actions (E)) then 3740 Insert_List_Before (New_If, Condition_Actions (E)); 3741 end if; 3742 3743 Remove (E); 3744 3745 if Is_Empty_List (Elsif_Parts (N)) then 3746 Set_Elsif_Parts (N, No_List); 3747 end if; 3748 3749 Analyze (New_If); 3750 3751 -- Note this is not an implicit if statement, since it is part 3752 -- of an explicit if statement in the source (or of an implicit 3753 -- if statement that has already been tested). We set the flag 3754 -- after calling Analyze to avoid generating extra warnings 3755 -- specific to pure if statements, however (see 3756 -- Sem_Ch5.Analyze_If_Statement). 3757 3758 Set_Comes_From_Source (New_If, Comes_From_Source (N)); 3759 return; 3760 3761 -- No special processing for that elsif part, move to next 3762 3763 else 3764 Next (E); 3765 end if; 3766 end loop; 3767 end if; 3768 3769 -- Some more optimizations applicable if we still have an IF statement 3770 3771 if Nkind (N) /= N_If_Statement then 3772 return; 3773 end if; 3774 3775 -- Another optimization, special cases that can be simplified 3776 3777 -- if expression then 3778 -- return true; 3779 -- else 3780 -- return false; 3781 -- end if; 3782 3783 -- can be changed to: 3784 3785 -- return expression; 3786 3787 -- and 3788 3789 -- if expression then 3790 -- return false; 3791 -- else 3792 -- return true; 3793 -- end if; 3794 3795 -- can be changed to: 3796 3797 -- return not (expression); 3798 3799 -- Only do these optimizations if we are at least at -O1 level and 3800 -- do not do them if control flow optimizations are suppressed. 3801 3802 if Optimization_Level > 0 3803 and then not Opt.Suppress_Control_Flow_Optimizations 3804 then 3805 if Nkind (N) = N_If_Statement 3806 and then No (Elsif_Parts (N)) 3807 and then Present (Else_Statements (N)) 3808 and then List_Length (Then_Statements (N)) = 1 3809 and then List_Length (Else_Statements (N)) = 1 3810 then 3811 declare 3812 Then_Stm : constant Node_Id := First (Then_Statements (N)); 3813 Else_Stm : constant Node_Id := First (Else_Statements (N)); 3814 3815 begin 3816 if Nkind (Then_Stm) = N_Simple_Return_Statement 3817 and then 3818 Nkind (Else_Stm) = N_Simple_Return_Statement 3819 then 3820 declare 3821 Then_Expr : constant Node_Id := Expression (Then_Stm); 3822 Else_Expr : constant Node_Id := Expression (Else_Stm); 3823 3824 begin 3825 if Nkind (Then_Expr) = N_Identifier 3826 and then 3827 Nkind (Else_Expr) = N_Identifier 3828 then 3829 if Entity (Then_Expr) = Standard_True 3830 and then Entity (Else_Expr) = Standard_False 3831 then 3832 Rewrite (N, 3833 Make_Simple_Return_Statement (Loc, 3834 Expression => Relocate_Node (Condition (N)))); 3835 Analyze (N); 3836 return; 3837 3838 elsif Entity (Then_Expr) = Standard_False 3839 and then Entity (Else_Expr) = Standard_True 3840 then 3841 Rewrite (N, 3842 Make_Simple_Return_Statement (Loc, 3843 Expression => 3844 Make_Op_Not (Loc, 3845 Right_Opnd => 3846 Relocate_Node (Condition (N))))); 3847 Analyze (N); 3848 return; 3849 end if; 3850 end if; 3851 end; 3852 end if; 3853 end; 3854 end if; 3855 end if; 3856 end Expand_N_If_Statement; 3857 3858 -------------------------- 3859 -- Expand_Iterator_Loop -- 3860 -------------------------- 3861 3862 procedure Expand_Iterator_Loop (N : Node_Id) is 3863 Isc : constant Node_Id := Iteration_Scheme (N); 3864 I_Spec : constant Node_Id := Iterator_Specification (Isc); 3865 3866 Container : constant Node_Id := Name (I_Spec); 3867 Container_Typ : constant Entity_Id := Base_Type (Etype (Container)); 3868 3869 begin 3870 -- Processing for arrays 3871 3872 if Is_Array_Type (Container_Typ) then 3873 pragma Assert (Of_Present (I_Spec)); 3874 Expand_Iterator_Loop_Over_Array (N); 3875 3876 elsif Has_Aspect (Container_Typ, Aspect_Iterable) then 3877 if Of_Present (I_Spec) then 3878 Expand_Formal_Container_Element_Loop (N); 3879 else 3880 Expand_Formal_Container_Loop (N); 3881 end if; 3882 3883 -- Processing for containers 3884 3885 else 3886 Expand_Iterator_Loop_Over_Container 3887 (N, Isc, I_Spec, Container, Container_Typ); 3888 end if; 3889 end Expand_Iterator_Loop; 3890 3891 ------------------------------------- 3892 -- Expand_Iterator_Loop_Over_Array -- 3893 ------------------------------------- 3894 3895 procedure Expand_Iterator_Loop_Over_Array (N : Node_Id) is 3896 Isc : constant Node_Id := Iteration_Scheme (N); 3897 I_Spec : constant Node_Id := Iterator_Specification (Isc); 3898 Array_Node : constant Node_Id := Name (I_Spec); 3899 Array_Typ : constant Entity_Id := Base_Type (Etype (Array_Node)); 3900 Array_Dim : constant Pos := Number_Dimensions (Array_Typ); 3901 Id : constant Entity_Id := Defining_Identifier (I_Spec); 3902 Loc : constant Source_Ptr := Sloc (Isc); 3903 Stats : constant List_Id := Statements (N); 3904 Core_Loop : Node_Id; 3905 Dim1 : Int; 3906 Ind_Comp : Node_Id; 3907 Iterator : Entity_Id; 3908 3909 -- Start of processing for Expand_Iterator_Loop_Over_Array 3910 3911 begin 3912 -- for Element of Array loop 3913 3914 -- It requires an internally generated cursor to iterate over the array 3915 3916 pragma Assert (Of_Present (I_Spec)); 3917 3918 Iterator := Make_Temporary (Loc, 'C'); 3919 3920 -- Generate: 3921 -- Element : Component_Type renames Array (Iterator); 3922 -- Iterator is the index value, or a list of index values 3923 -- in the case of a multidimensional array. 3924 3925 Ind_Comp := 3926 Make_Indexed_Component (Loc, 3927 Prefix => New_Copy_Tree (Array_Node), 3928 Expressions => New_List (New_Occurrence_Of (Iterator, Loc))); 3929 3930 -- Propagate the original node to the copy since the analysis of the 3931 -- following object renaming declaration relies on the original node. 3932 3933 Set_Original_Node (Prefix (Ind_Comp), Original_Node (Array_Node)); 3934 3935 Prepend_To (Stats, 3936 Make_Object_Renaming_Declaration (Loc, 3937 Defining_Identifier => Id, 3938 Subtype_Mark => 3939 New_Occurrence_Of (Component_Type (Array_Typ), Loc), 3940 Name => Ind_Comp)); 3941 3942 -- Mark the loop variable as needing debug info, so that expansion 3943 -- of the renaming will result in Materialize_Entity getting set via 3944 -- Debug_Renaming_Declaration. (This setting is needed here because 3945 -- the setting in Freeze_Entity comes after the expansion, which is 3946 -- too late. ???) 3947 3948 Set_Debug_Info_Needed (Id); 3949 3950 -- Generate: 3951 3952 -- for Iterator in [reverse] Array'Range (Array_Dim) loop 3953 -- Element : Component_Type renames Array (Iterator); 3954 -- <original loop statements> 3955 -- end loop; 3956 3957 -- If this is an iteration over a multidimensional array, the 3958 -- innermost loop is over the last dimension in Ada, and over 3959 -- the first dimension in Fortran. 3960 3961 if Convention (Array_Typ) = Convention_Fortran then 3962 Dim1 := 1; 3963 else 3964 Dim1 := Array_Dim; 3965 end if; 3966 3967 Core_Loop := 3968 Make_Loop_Statement (Sloc (N), 3969 Iteration_Scheme => 3970 Make_Iteration_Scheme (Loc, 3971 Loop_Parameter_Specification => 3972 Make_Loop_Parameter_Specification (Loc, 3973 Defining_Identifier => Iterator, 3974 Discrete_Subtype_Definition => 3975 Make_Attribute_Reference (Loc, 3976 Prefix => New_Copy_Tree (Array_Node), 3977 Attribute_Name => Name_Range, 3978 Expressions => New_List ( 3979 Make_Integer_Literal (Loc, Dim1))), 3980 Reverse_Present => Reverse_Present (I_Spec))), 3981 Statements => Stats, 3982 End_Label => Empty); 3983 3984 -- Processing for multidimensional array. The body of each loop is 3985 -- a loop over a previous dimension, going in decreasing order in Ada 3986 -- and in increasing order in Fortran. 3987 3988 if Array_Dim > 1 then 3989 for Dim in 1 .. Array_Dim - 1 loop 3990 if Convention (Array_Typ) = Convention_Fortran then 3991 Dim1 := Dim + 1; 3992 else 3993 Dim1 := Array_Dim - Dim; 3994 end if; 3995 3996 Iterator := Make_Temporary (Loc, 'C'); 3997 3998 -- Generate the dimension loops starting from the innermost one 3999 4000 -- for Iterator in [reverse] Array'Range (Array_Dim - Dim) loop 4001 -- <core loop> 4002 -- end loop; 4003 4004 Core_Loop := 4005 Make_Loop_Statement (Sloc (N), 4006 Iteration_Scheme => 4007 Make_Iteration_Scheme (Loc, 4008 Loop_Parameter_Specification => 4009 Make_Loop_Parameter_Specification (Loc, 4010 Defining_Identifier => Iterator, 4011 Discrete_Subtype_Definition => 4012 Make_Attribute_Reference (Loc, 4013 Prefix => New_Copy_Tree (Array_Node), 4014 Attribute_Name => Name_Range, 4015 Expressions => New_List ( 4016 Make_Integer_Literal (Loc, Dim1))), 4017 Reverse_Present => Reverse_Present (I_Spec))), 4018 Statements => New_List (Core_Loop), 4019 End_Label => Empty); 4020 4021 -- Update the previously created object renaming declaration with 4022 -- the new iterator, by adding the index of the next loop to the 4023 -- indexed component, in the order that corresponds to the 4024 -- convention. 4025 4026 if Convention (Array_Typ) = Convention_Fortran then 4027 Append_To (Expressions (Ind_Comp), 4028 New_Occurrence_Of (Iterator, Loc)); 4029 else 4030 Prepend_To (Expressions (Ind_Comp), 4031 New_Occurrence_Of (Iterator, Loc)); 4032 end if; 4033 end loop; 4034 end if; 4035 4036 -- Inherit the loop identifier from the original loop. This ensures that 4037 -- the scope stack is consistent after the rewriting. 4038 4039 if Present (Identifier (N)) then 4040 Set_Identifier (Core_Loop, Relocate_Node (Identifier (N))); 4041 end if; 4042 4043 Rewrite (N, Core_Loop); 4044 Analyze (N); 4045 end Expand_Iterator_Loop_Over_Array; 4046 4047 ----------------------------------------- 4048 -- Expand_Iterator_Loop_Over_Container -- 4049 ----------------------------------------- 4050 4051 -- For a 'for ... in' loop, such as: 4052 4053 -- for Cursor in Iterator_Function (...) loop 4054 -- ... 4055 -- end loop; 4056 4057 -- we generate: 4058 4059 -- Iter : Iterator_Type := Iterator_Function (...); 4060 -- Cursor : Cursor_type := First (Iter); -- or Last for "reverse" 4061 -- while Has_Element (Cursor) loop 4062 -- ... 4063 -- 4064 -- Cursor := Iter.Next (Cursor); -- or Prev for "reverse" 4065 -- end loop; 4066 4067 -- For a 'for ... of' loop, such as: 4068 4069 -- for X of Container loop 4070 -- ... 4071 -- end loop; 4072 4073 -- the RM implies the generation of: 4074 4075 -- Iter : Iterator_Type := Container.Iterate; -- the Default_Iterator 4076 -- Cursor : Cursor_Type := First (Iter); -- or Last for "reverse" 4077 -- while Has_Element (Cursor) loop 4078 -- declare 4079 -- X : Element_Type renames Element (Cursor).Element.all; 4080 -- -- or Constant_Element 4081 -- begin 4082 -- ... 4083 -- end; 4084 -- Cursor := Iter.Next (Cursor); -- or Prev for "reverse" 4085 -- end loop; 4086 4087 -- In the general case, we do what the RM says. However, the operations 4088 -- Element and Iter.Next are slow, which is bad inside a loop, because they 4089 -- involve dispatching via interfaces, secondary stack manipulation, 4090 -- Busy/Lock incr/decr, and adjust/finalization/at-end handling. So for the 4091 -- predefined containers, we use an equivalent but optimized expansion. 4092 4093 -- In the optimized case, we make use of these: 4094 4095 -- procedure Next (Position : in out Cursor); -- instead of Iter.Next 4096 4097 -- function Pseudo_Reference 4098 -- (Container : aliased Vector'Class) return Reference_Control_Type; 4099 4100 -- type Element_Access is access all Element_Type; 4101 4102 -- function Get_Element_Access 4103 -- (Position : Cursor) return not null Element_Access; 4104 4105 -- Next is declared in the visible part of the container packages. 4106 -- The other three are added in the private part. (We're not supposed to 4107 -- pollute the namespace for clients. The compiler has no trouble breaking 4108 -- privacy to call things in the private part of an instance.) 4109 4110 -- Source: 4111 4112 -- for X of My_Vector loop 4113 -- X.Count := X.Count + 1; 4114 -- ... 4115 -- end loop; 4116 4117 -- The compiler will generate: 4118 4119 -- Iter : Reversible_Iterator'Class := Iterate (My_Vector); 4120 -- -- Reversible_Iterator is an interface. Iterate is the 4121 -- -- Default_Iterator aspect of Vector. This increments Lock, 4122 -- -- disallowing tampering with cursors. Unfortunately, it does not 4123 -- -- increment Busy. The result of Iterate is Limited_Controlled; 4124 -- -- finalization will decrement Lock. This is a build-in-place 4125 -- -- dispatching call to Iterate. 4126 4127 -- Cur : Cursor := First (Iter); -- or Last 4128 -- -- Dispatching call via interface. 4129 4130 -- Control : Reference_Control_Type := Pseudo_Reference (My_Vector); 4131 -- -- Pseudo_Reference increments Busy, to detect tampering with 4132 -- -- elements, as required by RM. Also redundantly increment 4133 -- -- Lock. Finalization of Control will decrement both Busy and 4134 -- -- Lock. Pseudo_Reference returns a record containing a pointer to 4135 -- -- My_Vector, used by Finalize. 4136 -- -- 4137 -- -- Control is not used below, except to finalize it -- it's purely 4138 -- -- an RAII thing. This is needed because we are eliminating the 4139 -- -- call to Reference within the loop. 4140 4141 -- while Has_Element (Cur) loop 4142 -- declare 4143 -- X : My_Element renames Get_Element_Access (Cur).all; 4144 -- -- Get_Element_Access returns a pointer to the element 4145 -- -- designated by Cur. No dispatching here, and no horsing 4146 -- -- around with access discriminants. This is instead of the 4147 -- -- existing 4148 -- -- 4149 -- -- X : My_Element renames Reference (Cur).Element.all; 4150 -- -- 4151 -- -- which creates a controlled object. 4152 -- begin 4153 -- -- Any attempt to tamper with My_Vector here in the loop 4154 -- -- will correctly raise Program_Error, because of the 4155 -- -- Control. 4156 -- 4157 -- X.Count := X.Count + 1; 4158 -- ... 4159 -- 4160 -- Next (Cur); -- or Prev 4161 -- -- This is instead of "Cur := Next (Iter, Cur);" 4162 -- end; 4163 -- -- No finalization here 4164 -- end loop; 4165 -- Finalize Iter and Control here, decrementing Lock twice and Busy 4166 -- once. 4167 4168 -- This optimization makes "for ... of" loops over 30 times faster in cases 4169 -- measured. 4170 4171 procedure Expand_Iterator_Loop_Over_Container 4172 (N : Node_Id; 4173 Isc : Node_Id; 4174 I_Spec : Node_Id; 4175 Container : Node_Id; 4176 Container_Typ : Entity_Id) 4177 is 4178 Id : constant Entity_Id := Defining_Identifier (I_Spec); 4179 Elem_Typ : constant Entity_Id := Etype (Id); 4180 Id_Kind : constant Entity_Kind := Ekind (Id); 4181 Loc : constant Source_Ptr := Sloc (N); 4182 Stats : constant List_Id := Statements (N); 4183 4184 Cursor : Entity_Id; 4185 Decl : Node_Id; 4186 Iter_Type : Entity_Id; 4187 Iterator : Entity_Id; 4188 Name_Init : Name_Id; 4189 Name_Step : Name_Id; 4190 New_Loop : Node_Id; 4191 4192 Fast_Element_Access_Op : Entity_Id := Empty; 4193 Fast_Step_Op : Entity_Id := Empty; 4194 -- Only for optimized version of "for ... of" 4195 4196 Iter_Pack : Entity_Id; 4197 -- The package in which the iterator interface is instantiated. This is 4198 -- typically an instance within the container package. 4199 4200 Pack : Entity_Id; 4201 -- The package in which the container type is declared 4202 4203 begin 4204 -- Determine the advancement and initialization steps for the cursor. 4205 -- Analysis of the expanded loop will verify that the container has a 4206 -- reverse iterator. 4207 4208 if Reverse_Present (I_Spec) then 4209 Name_Init := Name_Last; 4210 Name_Step := Name_Previous; 4211 else 4212 Name_Init := Name_First; 4213 Name_Step := Name_Next; 4214 end if; 4215 4216 -- The type of the iterator is the return type of the Iterate function 4217 -- used. For the "of" form this is the default iterator for the type, 4218 -- otherwise it is the type of the explicit function used in the 4219 -- iterator specification. The most common case will be an Iterate 4220 -- function in the container package. 4221 4222 -- The Iterator type is declared in an instance within the container 4223 -- package itself, for example: 4224 4225 -- package Vector_Iterator_Interfaces is new 4226 -- Ada.Iterator_Interfaces (Cursor, Has_Element); 4227 4228 -- If the container type is a derived type, the cursor type is found in 4229 -- the package of the ultimate ancestor type. 4230 4231 if Is_Derived_Type (Container_Typ) then 4232 Pack := Scope (Root_Type (Container_Typ)); 4233 else 4234 Pack := Scope (Container_Typ); 4235 end if; 4236 4237 if Of_Present (I_Spec) then 4238 Handle_Of : declare 4239 Container_Arg : Node_Id; 4240 4241 function Get_Default_Iterator 4242 (T : Entity_Id) return Entity_Id; 4243 -- Return the default iterator for a specific type. If the type is 4244 -- derived, we return the inherited or overridden one if 4245 -- appropriate. 4246 4247 -------------------------- 4248 -- Get_Default_Iterator -- 4249 -------------------------- 4250 4251 function Get_Default_Iterator 4252 (T : Entity_Id) return Entity_Id 4253 is 4254 Iter : constant Entity_Id := 4255 Entity (Find_Value_Of_Aspect (T, Aspect_Default_Iterator)); 4256 Prim : Elmt_Id; 4257 Op : Entity_Id; 4258 4259 begin 4260 Container_Arg := New_Copy_Tree (Container); 4261 4262 -- A previous version of GNAT allowed indexing aspects to be 4263 -- redefined on derived container types, while the default 4264 -- iterator was inherited from the parent type. This 4265 -- nonstandard extension is preserved for use by the 4266 -- modeling project under debug flag -gnatd.X. 4267 4268 if Debug_Flag_Dot_XX then 4269 if Base_Type (Etype (Container)) /= 4270 Base_Type (Etype (First_Formal (Iter))) 4271 then 4272 Container_Arg := 4273 Make_Type_Conversion (Loc, 4274 Subtype_Mark => 4275 New_Occurrence_Of 4276 (Etype (First_Formal (Iter)), Loc), 4277 Expression => Container_Arg); 4278 end if; 4279 4280 return Iter; 4281 4282 elsif Is_Derived_Type (T) then 4283 4284 -- The default iterator must be a primitive operation of the 4285 -- type, at the same dispatch slot position. The DT position 4286 -- may not be established if type is not frozen yet. 4287 4288 Prim := First_Elmt (Primitive_Operations (T)); 4289 while Present (Prim) loop 4290 Op := Node (Prim); 4291 4292 if Alias (Op) = Iter 4293 or else 4294 (Chars (Op) = Chars (Iter) 4295 and then Present (DTC_Entity (Op)) 4296 and then DT_Position (Op) = DT_Position (Iter)) 4297 then 4298 return Op; 4299 end if; 4300 4301 Next_Elmt (Prim); 4302 end loop; 4303 4304 -- If we didn't find it, then our parent type is not 4305 -- iterable, so we return the Default_Iterator aspect of 4306 -- this type. 4307 4308 return Iter; 4309 4310 -- Otherwise not a derived type 4311 4312 else 4313 return Iter; 4314 end if; 4315 end Get_Default_Iterator; 4316 4317 -- Local variables 4318 4319 Default_Iter : Entity_Id; 4320 Ent : Entity_Id; 4321 4322 Reference_Control_Type : Entity_Id := Empty; 4323 Pseudo_Reference : Entity_Id := Empty; 4324 4325 -- Start of processing for Handle_Of 4326 4327 begin 4328 if Is_Class_Wide_Type (Container_Typ) then 4329 Default_Iter := 4330 Get_Default_Iterator (Etype (Base_Type (Container_Typ))); 4331 else 4332 Default_Iter := Get_Default_Iterator (Etype (Container)); 4333 end if; 4334 4335 Cursor := Make_Temporary (Loc, 'C'); 4336 4337 -- For a container element iterator, the iterator type is obtained 4338 -- from the corresponding aspect, whose return type is descended 4339 -- from the corresponding interface type in some instance of 4340 -- Ada.Iterator_Interfaces. The actuals of that instantiation 4341 -- are Cursor and Has_Element. 4342 4343 Iter_Type := Etype (Default_Iter); 4344 4345 -- The iterator type, which is a class-wide type, may itself be 4346 -- derived locally, so the desired instantiation is the scope of 4347 -- the root type of the iterator type. 4348 4349 Iter_Pack := Scope (Root_Type (Etype (Iter_Type))); 4350 4351 -- Find declarations needed for "for ... of" optimization 4352 4353 Ent := First_Entity (Pack); 4354 while Present (Ent) loop 4355 if Chars (Ent) = Name_Get_Element_Access then 4356 Fast_Element_Access_Op := Ent; 4357 4358 elsif Chars (Ent) = Name_Step 4359 and then Ekind (Ent) = E_Procedure 4360 then 4361 Fast_Step_Op := Ent; 4362 4363 elsif Chars (Ent) = Name_Reference_Control_Type then 4364 Reference_Control_Type := Ent; 4365 4366 elsif Chars (Ent) = Name_Pseudo_Reference then 4367 Pseudo_Reference := Ent; 4368 end if; 4369 4370 Next_Entity (Ent); 4371 end loop; 4372 4373 if Present (Reference_Control_Type) 4374 and then Present (Pseudo_Reference) 4375 then 4376 Insert_Action (N, 4377 Make_Object_Declaration (Loc, 4378 Defining_Identifier => Make_Temporary (Loc, 'D'), 4379 Object_Definition => 4380 New_Occurrence_Of (Reference_Control_Type, Loc), 4381 Expression => 4382 Make_Function_Call (Loc, 4383 Name => 4384 New_Occurrence_Of (Pseudo_Reference, Loc), 4385 Parameter_Associations => 4386 New_List (New_Copy_Tree (Container_Arg))))); 4387 end if; 4388 4389 -- Rewrite domain of iteration as a call to the default iterator 4390 -- for the container type. The formal may be an access parameter 4391 -- in which case we must build a reference to the container. 4392 4393 declare 4394 Arg : Node_Id; 4395 begin 4396 if Is_Access_Type (Etype (First_Entity (Default_Iter))) then 4397 Arg := 4398 Make_Attribute_Reference (Loc, 4399 Prefix => Container_Arg, 4400 Attribute_Name => Name_Unrestricted_Access); 4401 else 4402 Arg := Container_Arg; 4403 end if; 4404 4405 Rewrite (Name (I_Spec), 4406 Make_Function_Call (Loc, 4407 Name => 4408 New_Occurrence_Of (Default_Iter, Loc), 4409 Parameter_Associations => New_List (Arg))); 4410 end; 4411 4412 Analyze_And_Resolve (Name (I_Spec)); 4413 4414 -- Find cursor type in proper iterator package, which is an 4415 -- instantiation of Iterator_Interfaces. 4416 4417 Ent := First_Entity (Iter_Pack); 4418 while Present (Ent) loop 4419 if Chars (Ent) = Name_Cursor then 4420 Set_Etype (Cursor, Etype (Ent)); 4421 exit; 4422 end if; 4423 4424 Next_Entity (Ent); 4425 end loop; 4426 4427 if Present (Fast_Element_Access_Op) then 4428 Decl := 4429 Make_Object_Renaming_Declaration (Loc, 4430 Defining_Identifier => Id, 4431 Subtype_Mark => 4432 New_Occurrence_Of (Elem_Typ, Loc), 4433 Name => 4434 Make_Explicit_Dereference (Loc, 4435 Prefix => 4436 Make_Function_Call (Loc, 4437 Name => 4438 New_Occurrence_Of (Fast_Element_Access_Op, Loc), 4439 Parameter_Associations => 4440 New_List (New_Occurrence_Of (Cursor, Loc))))); 4441 4442 else 4443 Decl := 4444 Make_Object_Renaming_Declaration (Loc, 4445 Defining_Identifier => Id, 4446 Subtype_Mark => 4447 New_Occurrence_Of (Elem_Typ, Loc), 4448 Name => 4449 Make_Indexed_Component (Loc, 4450 Prefix => Relocate_Node (Container_Arg), 4451 Expressions => 4452 New_List (New_Occurrence_Of (Cursor, Loc)))); 4453 end if; 4454 4455 -- The defining identifier in the iterator is user-visible and 4456 -- must be visible in the debugger. 4457 4458 Set_Debug_Info_Needed (Id); 4459 4460 -- If the container does not have a variable indexing aspect, 4461 -- the element is a constant in the loop. The container itself 4462 -- may be constant, in which case the element is a constant as 4463 -- well. The container has been rewritten as a call to Iterate, 4464 -- so examine original node. 4465 4466 if No (Find_Value_Of_Aspect 4467 (Container_Typ, Aspect_Variable_Indexing)) 4468 or else not Is_Variable (Original_Node (Container)) 4469 then 4470 Set_Ekind (Id, E_Constant); 4471 end if; 4472 4473 Prepend_To (Stats, Decl); 4474 end Handle_Of; 4475 4476 -- X in Iterate (S) : type of iterator is type of explicitly given 4477 -- Iterate function, and the loop variable is the cursor. It will be 4478 -- assigned in the loop and must be a variable. 4479 4480 else 4481 Iter_Type := Etype (Name (I_Spec)); 4482 4483 -- The iterator type, which is a class-wide type, may itself be 4484 -- derived locally, so the desired instantiation is the scope of 4485 -- the root type of the iterator type, as in the "of" case. 4486 4487 Iter_Pack := Scope (Root_Type (Etype (Iter_Type))); 4488 Cursor := Id; 4489 end if; 4490 4491 Iterator := Make_Temporary (Loc, 'I'); 4492 4493 -- For both iterator forms, add a call to the step operation to advance 4494 -- the cursor. Generate: 4495 4496 -- Cursor := Iterator.Next (Cursor); 4497 4498 -- or else 4499 4500 -- Cursor := Next (Cursor); 4501 4502 if Present (Fast_Element_Access_Op) and then Present (Fast_Step_Op) then 4503 declare 4504 Curs_Name : constant Node_Id := New_Occurrence_Of (Cursor, Loc); 4505 Step_Call : Node_Id; 4506 4507 begin 4508 Step_Call := 4509 Make_Procedure_Call_Statement (Loc, 4510 Name => 4511 New_Occurrence_Of (Fast_Step_Op, Loc), 4512 Parameter_Associations => New_List (Curs_Name)); 4513 4514 Append_To (Stats, Step_Call); 4515 Set_Assignment_OK (Curs_Name); 4516 end; 4517 4518 else 4519 declare 4520 Rhs : Node_Id; 4521 4522 begin 4523 Rhs := 4524 Make_Function_Call (Loc, 4525 Name => 4526 Make_Selected_Component (Loc, 4527 Prefix => New_Occurrence_Of (Iterator, Loc), 4528 Selector_Name => Make_Identifier (Loc, Name_Step)), 4529 Parameter_Associations => New_List ( 4530 New_Occurrence_Of (Cursor, Loc))); 4531 4532 Append_To (Stats, 4533 Make_Assignment_Statement (Loc, 4534 Name => New_Occurrence_Of (Cursor, Loc), 4535 Expression => Rhs)); 4536 Set_Assignment_OK (Name (Last (Stats))); 4537 end; 4538 end if; 4539 4540 -- Generate: 4541 -- while Has_Element (Cursor) loop 4542 -- <Stats> 4543 -- end loop; 4544 4545 -- Has_Element is the second actual in the iterator package 4546 4547 New_Loop := 4548 Make_Loop_Statement (Loc, 4549 Iteration_Scheme => 4550 Make_Iteration_Scheme (Loc, 4551 Condition => 4552 Make_Function_Call (Loc, 4553 Name => 4554 New_Occurrence_Of 4555 (Next_Entity (First_Entity (Iter_Pack)), Loc), 4556 Parameter_Associations => New_List ( 4557 New_Occurrence_Of (Cursor, Loc)))), 4558 4559 Statements => Stats, 4560 End_Label => Empty); 4561 4562 -- If present, preserve identifier of loop, which can be used in an exit 4563 -- statement in the body. 4564 4565 if Present (Identifier (N)) then 4566 Set_Identifier (New_Loop, Relocate_Node (Identifier (N))); 4567 end if; 4568 4569 -- Create the declarations for Iterator and cursor and insert them 4570 -- before the source loop. Given that the domain of iteration is already 4571 -- an entity, the iterator is just a renaming of that entity. Possible 4572 -- optimization ??? 4573 4574 Insert_Action (N, 4575 Make_Object_Renaming_Declaration (Loc, 4576 Defining_Identifier => Iterator, 4577 Subtype_Mark => New_Occurrence_Of (Iter_Type, Loc), 4578 Name => Relocate_Node (Name (I_Spec)))); 4579 4580 -- Create declaration for cursor 4581 4582 declare 4583 Cursor_Decl : constant Node_Id := 4584 Make_Object_Declaration (Loc, 4585 Defining_Identifier => Cursor, 4586 Object_Definition => 4587 New_Occurrence_Of (Etype (Cursor), Loc), 4588 Expression => 4589 Make_Selected_Component (Loc, 4590 Prefix => 4591 New_Occurrence_Of (Iterator, Loc), 4592 Selector_Name => 4593 Make_Identifier (Loc, Name_Init))); 4594 4595 begin 4596 -- The cursor is only modified in expanded code, so it appears 4597 -- as unassigned to the warning machinery. We must suppress this 4598 -- spurious warning explicitly. The cursor's kind is that of the 4599 -- original loop parameter (it is a constant if the domain of 4600 -- iteration is constant). 4601 4602 Set_Warnings_Off (Cursor); 4603 Set_Assignment_OK (Cursor_Decl); 4604 4605 Insert_Action (N, Cursor_Decl); 4606 Set_Ekind (Cursor, Id_Kind); 4607 end; 4608 4609 -- If the range of iteration is given by a function call that returns 4610 -- a container, the finalization actions have been saved in the 4611 -- Condition_Actions of the iterator. Insert them now at the head of 4612 -- the loop. 4613 4614 if Present (Condition_Actions (Isc)) then 4615 Insert_List_Before (N, Condition_Actions (Isc)); 4616 end if; 4617 4618 Rewrite (N, New_Loop); 4619 Analyze (N); 4620 end Expand_Iterator_Loop_Over_Container; 4621 4622 ----------------------------- 4623 -- Expand_N_Loop_Statement -- 4624 ----------------------------- 4625 4626 -- 1. Remove null loop entirely 4627 -- 2. Deal with while condition for C/Fortran boolean 4628 -- 3. Deal with loops with a non-standard enumeration type range 4629 -- 4. Deal with while loops where Condition_Actions is set 4630 -- 5. Deal with loops over predicated subtypes 4631 -- 6. Deal with loops with iterators over arrays and containers 4632 -- 7. Insert polling call if required 4633 4634 procedure Expand_N_Loop_Statement (N : Node_Id) is 4635 Loc : constant Source_Ptr := Sloc (N); 4636 Scheme : constant Node_Id := Iteration_Scheme (N); 4637 Stmt : Node_Id; 4638 4639 begin 4640 -- Delete null loop 4641 4642 if Is_Null_Loop (N) then 4643 Rewrite (N, Make_Null_Statement (Loc)); 4644 return; 4645 end if; 4646 4647 -- Deal with condition for C/Fortran Boolean 4648 4649 if Present (Scheme) then 4650 Adjust_Condition (Condition (Scheme)); 4651 end if; 4652 4653 -- Generate polling call 4654 4655 if Is_Non_Empty_List (Statements (N)) then 4656 Generate_Poll_Call (First (Statements (N))); 4657 end if; 4658 4659 -- Nothing more to do for plain loop with no iteration scheme 4660 4661 if No (Scheme) then 4662 null; 4663 4664 -- Case of for loop (Loop_Parameter_Specification present) 4665 4666 -- Note: we do not have to worry about validity checking of the for loop 4667 -- range bounds here, since they were frozen with constant declarations 4668 -- and it is during that process that the validity checking is done. 4669 4670 elsif Present (Loop_Parameter_Specification (Scheme)) then 4671 declare 4672 LPS : constant Node_Id := 4673 Loop_Parameter_Specification (Scheme); 4674 Loop_Id : constant Entity_Id := Defining_Identifier (LPS); 4675 Ltype : constant Entity_Id := Etype (Loop_Id); 4676 Btype : constant Entity_Id := Base_Type (Ltype); 4677 Expr : Node_Id; 4678 Decls : List_Id; 4679 New_Id : Entity_Id; 4680 4681 begin 4682 -- Deal with loop over predicates 4683 4684 if Is_Discrete_Type (Ltype) 4685 and then Present (Predicate_Function (Ltype)) 4686 then 4687 Expand_Predicated_Loop (N); 4688 4689 -- Handle the case where we have a for loop with the range type 4690 -- being an enumeration type with non-standard representation. 4691 -- In this case we expand: 4692 4693 -- for x in [reverse] a .. b loop 4694 -- ... 4695 -- end loop; 4696 4697 -- to 4698 4699 -- for xP in [reverse] integer 4700 -- range etype'Pos (a) .. etype'Pos (b) 4701 -- loop 4702 -- declare 4703 -- x : constant etype := Pos_To_Rep (xP); 4704 -- begin 4705 -- ... 4706 -- end; 4707 -- end loop; 4708 4709 elsif Is_Enumeration_Type (Btype) 4710 and then Present (Enum_Pos_To_Rep (Btype)) 4711 then 4712 New_Id := 4713 Make_Defining_Identifier (Loc, 4714 Chars => New_External_Name (Chars (Loop_Id), 'P')); 4715 4716 -- If the type has a contiguous representation, successive 4717 -- values can be generated as offsets from the first literal. 4718 4719 if Has_Contiguous_Rep (Btype) then 4720 Expr := 4721 Unchecked_Convert_To (Btype, 4722 Make_Op_Add (Loc, 4723 Left_Opnd => 4724 Make_Integer_Literal (Loc, 4725 Enumeration_Rep (First_Literal (Btype))), 4726 Right_Opnd => New_Occurrence_Of (New_Id, Loc))); 4727 else 4728 -- Use the constructed array Enum_Pos_To_Rep 4729 4730 Expr := 4731 Make_Indexed_Component (Loc, 4732 Prefix => 4733 New_Occurrence_Of (Enum_Pos_To_Rep (Btype), Loc), 4734 Expressions => 4735 New_List (New_Occurrence_Of (New_Id, Loc))); 4736 end if; 4737 4738 -- Build declaration for loop identifier 4739 4740 Decls := 4741 New_List ( 4742 Make_Object_Declaration (Loc, 4743 Defining_Identifier => Loop_Id, 4744 Constant_Present => True, 4745 Object_Definition => New_Occurrence_Of (Ltype, Loc), 4746 Expression => Expr)); 4747 4748 Rewrite (N, 4749 Make_Loop_Statement (Loc, 4750 Identifier => Identifier (N), 4751 4752 Iteration_Scheme => 4753 Make_Iteration_Scheme (Loc, 4754 Loop_Parameter_Specification => 4755 Make_Loop_Parameter_Specification (Loc, 4756 Defining_Identifier => New_Id, 4757 Reverse_Present => Reverse_Present (LPS), 4758 4759 Discrete_Subtype_Definition => 4760 Make_Subtype_Indication (Loc, 4761 4762 Subtype_Mark => 4763 New_Occurrence_Of (Standard_Natural, Loc), 4764 4765 Constraint => 4766 Make_Range_Constraint (Loc, 4767 Range_Expression => 4768 Make_Range (Loc, 4769 4770 Low_Bound => 4771 Make_Attribute_Reference (Loc, 4772 Prefix => 4773 New_Occurrence_Of (Btype, Loc), 4774 4775 Attribute_Name => Name_Pos, 4776 4777 Expressions => New_List ( 4778 Relocate_Node 4779 (Type_Low_Bound (Ltype)))), 4780 4781 High_Bound => 4782 Make_Attribute_Reference (Loc, 4783 Prefix => 4784 New_Occurrence_Of (Btype, Loc), 4785 4786 Attribute_Name => Name_Pos, 4787 4788 Expressions => New_List ( 4789 Relocate_Node 4790 (Type_High_Bound 4791 (Ltype))))))))), 4792 4793 Statements => New_List ( 4794 Make_Block_Statement (Loc, 4795 Declarations => Decls, 4796 Handled_Statement_Sequence => 4797 Make_Handled_Sequence_Of_Statements (Loc, 4798 Statements => Statements (N)))), 4799 4800 End_Label => End_Label (N))); 4801 4802 -- The loop parameter's entity must be removed from the loop 4803 -- scope's entity list and rendered invisible, since it will 4804 -- now be located in the new block scope. Any other entities 4805 -- already associated with the loop scope, such as the loop 4806 -- parameter's subtype, will remain there. 4807 4808 -- In an element loop, the loop will contain a declaration for 4809 -- a cursor variable; otherwise the loop id is the first entity 4810 -- in the scope constructed for the loop. 4811 4812 if Comes_From_Source (Loop_Id) then 4813 pragma Assert (First_Entity (Scope (Loop_Id)) = Loop_Id); 4814 null; 4815 end if; 4816 4817 Set_First_Entity (Scope (Loop_Id), Next_Entity (Loop_Id)); 4818 Remove_Homonym (Loop_Id); 4819 4820 if Last_Entity (Scope (Loop_Id)) = Loop_Id then 4821 Set_Last_Entity (Scope (Loop_Id), Empty); 4822 end if; 4823 4824 Analyze (N); 4825 4826 -- Nothing to do with other cases of for loops 4827 4828 else 4829 null; 4830 end if; 4831 end; 4832 4833 -- Second case, if we have a while loop with Condition_Actions set, then 4834 -- we change it into a plain loop: 4835 4836 -- while C loop 4837 -- ... 4838 -- end loop; 4839 4840 -- changed to: 4841 4842 -- loop 4843 -- <<condition actions>> 4844 -- exit when not C; 4845 -- ... 4846 -- end loop 4847 4848 elsif Present (Scheme) 4849 and then Present (Condition_Actions (Scheme)) 4850 and then Present (Condition (Scheme)) 4851 then 4852 declare 4853 ES : Node_Id; 4854 4855 begin 4856 ES := 4857 Make_Exit_Statement (Sloc (Condition (Scheme)), 4858 Condition => 4859 Make_Op_Not (Sloc (Condition (Scheme)), 4860 Right_Opnd => Condition (Scheme))); 4861 4862 Prepend (ES, Statements (N)); 4863 Insert_List_Before (ES, Condition_Actions (Scheme)); 4864 4865 -- This is not an implicit loop, since it is generated in response 4866 -- to the loop statement being processed. If this is itself 4867 -- implicit, the restriction has already been checked. If not, 4868 -- it is an explicit loop. 4869 4870 Rewrite (N, 4871 Make_Loop_Statement (Sloc (N), 4872 Identifier => Identifier (N), 4873 Statements => Statements (N), 4874 End_Label => End_Label (N))); 4875 4876 Analyze (N); 4877 end; 4878 4879 -- Here to deal with iterator case 4880 4881 elsif Present (Scheme) 4882 and then Present (Iterator_Specification (Scheme)) 4883 then 4884 Expand_Iterator_Loop (N); 4885 4886 -- An iterator loop may generate renaming declarations for elements 4887 -- that require debug information. This is the case in particular 4888 -- with element iterators, where debug information must be generated 4889 -- for the temporary that holds the element value. These temporaries 4890 -- are created within a transient block whose local declarations are 4891 -- transferred to the loop, which now has nontrivial local objects. 4892 4893 if Nkind (N) = N_Loop_Statement 4894 and then Present (Identifier (N)) 4895 then 4896 Qualify_Entity_Names (N); 4897 end if; 4898 end if; 4899 4900 -- When the iteration scheme mentiones attribute 'Loop_Entry, the loop 4901 -- is transformed into a conditional block where the original loop is 4902 -- the sole statement. Inspect the statements of the nested loop for 4903 -- controlled objects. 4904 4905 Stmt := N; 4906 4907 if Subject_To_Loop_Entry_Attributes (Stmt) then 4908 Stmt := Find_Loop_In_Conditional_Block (Stmt); 4909 end if; 4910 4911 Process_Statements_For_Controlled_Objects (Stmt); 4912 end Expand_N_Loop_Statement; 4913 4914 ---------------------------- 4915 -- Expand_Predicated_Loop -- 4916 ---------------------------- 4917 4918 -- Note: the expander can handle generation of loops over predicated 4919 -- subtypes for both the dynamic and static cases. Depending on what 4920 -- we decide is allowed in Ada 2012 mode and/or extensions allowed 4921 -- mode, the semantic analyzer may disallow one or both forms. 4922 4923 procedure Expand_Predicated_Loop (N : Node_Id) is 4924 Loc : constant Source_Ptr := Sloc (N); 4925 Isc : constant Node_Id := Iteration_Scheme (N); 4926 LPS : constant Node_Id := Loop_Parameter_Specification (Isc); 4927 Loop_Id : constant Entity_Id := Defining_Identifier (LPS); 4928 Ltype : constant Entity_Id := Etype (Loop_Id); 4929 Stat : constant List_Id := Static_Discrete_Predicate (Ltype); 4930 Stmts : constant List_Id := Statements (N); 4931 4932 begin 4933 -- Case of iteration over non-static predicate, should not be possible 4934 -- since this is not allowed by the semantics and should have been 4935 -- caught during analysis of the loop statement. 4936 4937 if No (Stat) then 4938 raise Program_Error; 4939 4940 -- If the predicate list is empty, that corresponds to a predicate of 4941 -- False, in which case the loop won't run at all, and we rewrite the 4942 -- entire loop as a null statement. 4943 4944 elsif Is_Empty_List (Stat) then 4945 Rewrite (N, Make_Null_Statement (Loc)); 4946 Analyze (N); 4947 4948 -- For expansion over a static predicate we generate the following 4949 4950 -- declare 4951 -- J : Ltype := min-val; 4952 -- begin 4953 -- loop 4954 -- body 4955 -- case J is 4956 -- when endpoint => J := startpoint; 4957 -- when endpoint => J := startpoint; 4958 -- ... 4959 -- when max-val => exit; 4960 -- when others => J := Lval'Succ (J); 4961 -- end case; 4962 -- end loop; 4963 -- end; 4964 4965 -- with min-val replaced by max-val and Succ replaced by Pred if the 4966 -- loop parameter specification carries a Reverse indicator. 4967 4968 -- To make this a little clearer, let's take a specific example: 4969 4970 -- type Int is range 1 .. 10; 4971 -- subtype StaticP is Int with 4972 -- predicate => StaticP in 3 | 10 | 5 .. 7; 4973 -- ... 4974 -- for L in StaticP loop 4975 -- Put_Line ("static:" & J'Img); 4976 -- end loop; 4977 4978 -- In this case, the loop is transformed into 4979 4980 -- begin 4981 -- J : L := 3; 4982 -- loop 4983 -- body 4984 -- case J is 4985 -- when 3 => J := 5; 4986 -- when 7 => J := 10; 4987 -- when 10 => exit; 4988 -- when others => J := L'Succ (J); 4989 -- end case; 4990 -- end loop; 4991 -- end; 4992 4993 -- In addition, if the loop specification is given by a subtype 4994 -- indication that constrains a predicated type, the bounds of 4995 -- iteration are given by those of the subtype indication. 4996 4997 else 4998 Static_Predicate : declare 4999 S : Node_Id; 5000 D : Node_Id; 5001 P : Node_Id; 5002 Alts : List_Id; 5003 Cstm : Node_Id; 5004 5005 -- If the domain is an itype, note the bounds of its range. 5006 5007 L_Hi : Node_Id := Empty; 5008 L_Lo : Node_Id := Empty; 5009 5010 function Lo_Val (N : Node_Id) return Node_Id; 5011 -- Given static expression or static range, returns an identifier 5012 -- whose value is the low bound of the expression value or range. 5013 5014 function Hi_Val (N : Node_Id) return Node_Id; 5015 -- Given static expression or static range, returns an identifier 5016 -- whose value is the high bound of the expression value or range. 5017 5018 ------------ 5019 -- Hi_Val -- 5020 ------------ 5021 5022 function Hi_Val (N : Node_Id) return Node_Id is 5023 begin 5024 if Is_OK_Static_Expression (N) then 5025 return New_Copy (N); 5026 else 5027 pragma Assert (Nkind (N) = N_Range); 5028 return New_Copy (High_Bound (N)); 5029 end if; 5030 end Hi_Val; 5031 5032 ------------ 5033 -- Lo_Val -- 5034 ------------ 5035 5036 function Lo_Val (N : Node_Id) return Node_Id is 5037 begin 5038 if Is_OK_Static_Expression (N) then 5039 return New_Copy (N); 5040 else 5041 pragma Assert (Nkind (N) = N_Range); 5042 return New_Copy (Low_Bound (N)); 5043 end if; 5044 end Lo_Val; 5045 5046 -- Start of processing for Static_Predicate 5047 5048 begin 5049 -- Convert loop identifier to normal variable and reanalyze it so 5050 -- that this conversion works. We have to use the same defining 5051 -- identifier, since there may be references in the loop body. 5052 5053 Set_Analyzed (Loop_Id, False); 5054 Set_Ekind (Loop_Id, E_Variable); 5055 5056 -- In most loops the loop variable is assigned in various 5057 -- alternatives in the body. However, in the rare case when 5058 -- the range specifies a single element, the loop variable 5059 -- may trigger a spurious warning that is could be constant. 5060 -- This warning might as well be suppressed. 5061 5062 Set_Warnings_Off (Loop_Id); 5063 5064 if Is_Itype (Ltype) then 5065 L_Hi := High_Bound (Scalar_Range (Ltype)); 5066 L_Lo := Low_Bound (Scalar_Range (Ltype)); 5067 end if; 5068 5069 -- Loop to create branches of case statement 5070 5071 Alts := New_List; 5072 5073 if Reverse_Present (LPS) then 5074 5075 -- Initial value is largest value in predicate. 5076 5077 if Is_Itype (Ltype) then 5078 D := 5079 Make_Object_Declaration (Loc, 5080 Defining_Identifier => Loop_Id, 5081 Object_Definition => New_Occurrence_Of (Ltype, Loc), 5082 Expression => L_Hi); 5083 5084 else 5085 D := 5086 Make_Object_Declaration (Loc, 5087 Defining_Identifier => Loop_Id, 5088 Object_Definition => New_Occurrence_Of (Ltype, Loc), 5089 Expression => Hi_Val (Last (Stat))); 5090 end if; 5091 5092 P := Last (Stat); 5093 while Present (P) loop 5094 if No (Prev (P)) then 5095 S := Make_Exit_Statement (Loc); 5096 else 5097 S := 5098 Make_Assignment_Statement (Loc, 5099 Name => New_Occurrence_Of (Loop_Id, Loc), 5100 Expression => Hi_Val (Prev (P))); 5101 Set_Suppress_Assignment_Checks (S); 5102 end if; 5103 5104 Append_To (Alts, 5105 Make_Case_Statement_Alternative (Loc, 5106 Statements => New_List (S), 5107 Discrete_Choices => New_List (Lo_Val (P)))); 5108 5109 Prev (P); 5110 end loop; 5111 5112 if Is_Itype (Ltype) 5113 and then Is_OK_Static_Expression (L_Lo) 5114 and then 5115 Expr_Value (L_Lo) /= Expr_Value (Lo_Val (First (Stat))) 5116 then 5117 Append_To (Alts, 5118 Make_Case_Statement_Alternative (Loc, 5119 Statements => New_List (Make_Exit_Statement (Loc)), 5120 Discrete_Choices => New_List (L_Lo))); 5121 end if; 5122 5123 else 5124 -- Initial value is smallest value in predicate 5125 5126 if Is_Itype (Ltype) then 5127 D := 5128 Make_Object_Declaration (Loc, 5129 Defining_Identifier => Loop_Id, 5130 Object_Definition => New_Occurrence_Of (Ltype, Loc), 5131 Expression => L_Lo); 5132 else 5133 D := 5134 Make_Object_Declaration (Loc, 5135 Defining_Identifier => Loop_Id, 5136 Object_Definition => New_Occurrence_Of (Ltype, Loc), 5137 Expression => Lo_Val (First (Stat))); 5138 end if; 5139 5140 P := First (Stat); 5141 while Present (P) loop 5142 if No (Next (P)) then 5143 S := Make_Exit_Statement (Loc); 5144 else 5145 S := 5146 Make_Assignment_Statement (Loc, 5147 Name => New_Occurrence_Of (Loop_Id, Loc), 5148 Expression => Lo_Val (Next (P))); 5149 Set_Suppress_Assignment_Checks (S); 5150 end if; 5151 5152 Append_To (Alts, 5153 Make_Case_Statement_Alternative (Loc, 5154 Statements => New_List (S), 5155 Discrete_Choices => New_List (Hi_Val (P)))); 5156 5157 Next (P); 5158 end loop; 5159 5160 if Is_Itype (Ltype) 5161 and then Is_OK_Static_Expression (L_Hi) 5162 and then 5163 Expr_Value (L_Hi) /= Expr_Value (Lo_Val (Last (Stat))) 5164 then 5165 Append_To (Alts, 5166 Make_Case_Statement_Alternative (Loc, 5167 Statements => New_List (Make_Exit_Statement (Loc)), 5168 Discrete_Choices => New_List (L_Hi))); 5169 end if; 5170 end if; 5171 5172 -- Add others choice 5173 5174 declare 5175 Name_Next : Name_Id; 5176 5177 begin 5178 if Reverse_Present (LPS) then 5179 Name_Next := Name_Pred; 5180 else 5181 Name_Next := Name_Succ; 5182 end if; 5183 5184 S := 5185 Make_Assignment_Statement (Loc, 5186 Name => New_Occurrence_Of (Loop_Id, Loc), 5187 Expression => 5188 Make_Attribute_Reference (Loc, 5189 Prefix => New_Occurrence_Of (Ltype, Loc), 5190 Attribute_Name => Name_Next, 5191 Expressions => New_List ( 5192 New_Occurrence_Of (Loop_Id, Loc)))); 5193 Set_Suppress_Assignment_Checks (S); 5194 end; 5195 5196 Append_To (Alts, 5197 Make_Case_Statement_Alternative (Loc, 5198 Discrete_Choices => New_List (Make_Others_Choice (Loc)), 5199 Statements => New_List (S))); 5200 5201 -- Construct case statement and append to body statements 5202 5203 Cstm := 5204 Make_Case_Statement (Loc, 5205 Expression => New_Occurrence_Of (Loop_Id, Loc), 5206 Alternatives => Alts); 5207 Append_To (Stmts, Cstm); 5208 5209 -- Rewrite the loop 5210 5211 Set_Suppress_Assignment_Checks (D); 5212 5213 Rewrite (N, 5214 Make_Block_Statement (Loc, 5215 Declarations => New_List (D), 5216 Handled_Statement_Sequence => 5217 Make_Handled_Sequence_Of_Statements (Loc, 5218 Statements => New_List ( 5219 Make_Loop_Statement (Loc, 5220 Statements => Stmts, 5221 End_Label => Empty))))); 5222 5223 Analyze (N); 5224 end Static_Predicate; 5225 end if; 5226 end Expand_Predicated_Loop; 5227 5228 ------------------------------ 5229 -- Make_Tag_Ctrl_Assignment -- 5230 ------------------------------ 5231 5232 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is 5233 Asn : constant Node_Id := Relocate_Node (N); 5234 L : constant Node_Id := Name (N); 5235 Loc : constant Source_Ptr := Sloc (N); 5236 Res : constant List_Id := New_List; 5237 T : constant Entity_Id := Underlying_Type (Etype (L)); 5238 5239 Comp_Asn : constant Boolean := Is_Fully_Repped_Tagged_Type (T); 5240 Ctrl_Act : constant Boolean := Needs_Finalization (T) 5241 and then not No_Ctrl_Actions (N); 5242 Save_Tag : constant Boolean := Is_Tagged_Type (T) 5243 and then not Comp_Asn 5244 and then not No_Ctrl_Actions (N) 5245 and then Tagged_Type_Expansion; 5246 Adj_Call : Node_Id; 5247 Fin_Call : Node_Id; 5248 Tag_Id : Entity_Id; 5249 5250 begin 5251 -- Finalize the target of the assignment when controlled 5252 5253 -- We have two exceptions here: 5254 5255 -- 1. If we are in an init proc since it is an initialization more 5256 -- than an assignment. 5257 5258 -- 2. If the left-hand side is a temporary that was not initialized 5259 -- (or the parent part of a temporary since it is the case in 5260 -- extension aggregates). Such a temporary does not come from 5261 -- source. We must examine the original node for the prefix, because 5262 -- it may be a component of an entry formal, in which case it has 5263 -- been rewritten and does not appear to come from source either. 5264 5265 -- Case of init proc 5266 5267 if not Ctrl_Act then 5268 null; 5269 5270 -- The left-hand side is an uninitialized temporary object 5271 5272 elsif Nkind (L) = N_Type_Conversion 5273 and then Is_Entity_Name (Expression (L)) 5274 and then Nkind (Parent (Entity (Expression (L)))) = 5275 N_Object_Declaration 5276 and then No_Initialization (Parent (Entity (Expression (L)))) 5277 then 5278 null; 5279 5280 else 5281 Fin_Call := 5282 Make_Final_Call 5283 (Obj_Ref => Duplicate_Subexpr_No_Checks (L), 5284 Typ => Etype (L)); 5285 5286 if Present (Fin_Call) then 5287 Append_To (Res, Fin_Call); 5288 end if; 5289 end if; 5290 5291 -- Save the Tag in a local variable Tag_Id 5292 5293 if Save_Tag then 5294 Tag_Id := Make_Temporary (Loc, 'A'); 5295 5296 Append_To (Res, 5297 Make_Object_Declaration (Loc, 5298 Defining_Identifier => Tag_Id, 5299 Object_Definition => New_Occurrence_Of (RTE (RE_Tag), Loc), 5300 Expression => 5301 Make_Selected_Component (Loc, 5302 Prefix => Duplicate_Subexpr_No_Checks (L), 5303 Selector_Name => 5304 New_Occurrence_Of (First_Tag_Component (T), Loc)))); 5305 5306 -- Otherwise Tag_Id is not used 5307 5308 else 5309 Tag_Id := Empty; 5310 end if; 5311 5312 -- If the tagged type has a full rep clause, expand the assignment into 5313 -- component-wise assignments. Mark the node as unanalyzed in order to 5314 -- generate the proper code and propagate this scenario by setting a 5315 -- flag to avoid infinite recursion. 5316 5317 if Comp_Asn then 5318 Set_Analyzed (Asn, False); 5319 Set_Componentwise_Assignment (Asn, True); 5320 end if; 5321 5322 Append_To (Res, Asn); 5323 5324 -- Restore the tag 5325 5326 if Save_Tag then 5327 Append_To (Res, 5328 Make_Assignment_Statement (Loc, 5329 Name => 5330 Make_Selected_Component (Loc, 5331 Prefix => Duplicate_Subexpr_No_Checks (L), 5332 Selector_Name => 5333 New_Occurrence_Of (First_Tag_Component (T), Loc)), 5334 Expression => New_Occurrence_Of (Tag_Id, Loc))); 5335 end if; 5336 5337 -- Adjust the target after the assignment when controlled (not in the 5338 -- init proc since it is an initialization more than an assignment). 5339 5340 if Ctrl_Act then 5341 Adj_Call := 5342 Make_Adjust_Call 5343 (Obj_Ref => Duplicate_Subexpr_Move_Checks (L), 5344 Typ => Etype (L)); 5345 5346 if Present (Adj_Call) then 5347 Append_To (Res, Adj_Call); 5348 end if; 5349 end if; 5350 5351 return Res; 5352 5353 exception 5354 5355 -- Could use comment here ??? 5356 5357 when RE_Not_Available => 5358 return Empty_List; 5359 end Make_Tag_Ctrl_Assignment; 5360 5361end Exp_Ch5; 5362