| blob | fa1ad4f4459e813ae683baf44fe58b64c58a97ce |
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- E X P _ C H 4 --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2010, 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 ------------------------------------------------------------------------------
79 -----------------------
80 -- Local Subprograms --
81 -----------------------
85 -- Performs validity checks for a binary operator
87 procedure Build_Boolean_Array_Proc_Call
91 -- If a boolean array assignment can be done in place, build call to
92 -- corresponding library procedure.
95 -- Ada 2005 (AI-251): Subsidiary procedure to Expand_N_Allocator and
96 -- Expand_Allocator_Expression. Allocating class-wide interface objects
97 -- this routine displaces the pointer to the allocated object to reference
98 -- the component referencing the corresponding secondary dispatch table.
101 -- Subsidiary to Expand_N_Allocator, for the case when the expression
102 -- is a qualified expression or an aggregate.
105 -- This routine handles expansion of the comparison operators (N_Op_Lt,
106 -- N_Op_Le, N_Op_Gt, N_Op_Ge) when operating on an array type. The basic
107 -- code for these operators is similar, differing only in the details of
108 -- the actual comparison call that is made. Special processing (call a
109 -- run-time routine)
111 function Expand_Array_Equality
117 -- Expand an array equality into a call to a function implementing this
118 -- equality, and a call to it. Loc is the location for the generated nodes.
119 -- Lhs and Rhs are the array expressions to be compared. Bodies is a list
120 -- on which to attach bodies of local functions that are created in the
121 -- process. It is the responsibility of the caller to insert those bodies
122 -- at the right place. Nod provides the Sloc value for the generated code.
123 -- Normally the types used for the generated equality routine are taken
124 -- from Lhs and Rhs. However, in some situations of generated code, the
125 -- Etype fields of Lhs and Rhs are not set yet. In such cases, Typ supplies
126 -- the type to be used for the formal parameters.
129 -- Common expansion processing for Boolean operators (And, Or, Xor) for the
130 -- case of array type arguments.
133 -- Common expansion processing for short-circuit boolean operators
135 function Expand_Composite_Equality
141 -- Local recursive function used to expand equality for nested composite
142 -- types. Used by Expand_Record/Array_Equality, Bodies is a list on which
143 -- to attach bodies of local functions that are created in the process.
144 -- This is the responsibility of the caller to insert those bodies at the
145 -- right place. Nod provides the Sloc value for generated code. Lhs and Rhs
146 -- are the left and right sides for the comparison, and Typ is the type of
147 -- the arrays to compare.
150 -- Routine to expand concatenation of a sequence of two or more operands
151 -- (in the list Operands) and replace node Cnode with the result of the
152 -- concatenation. The operands can be of any appropriate type, and can
153 -- include both arrays and singleton elements.
156 -- N is a N_Op_Divide or N_Op_Multiply node whose result is universal
157 -- fixed. We do not have such a type at runtime, so the purpose of this
158 -- routine is to find the real type by looking up the tree. We also
159 -- determine if the operation must be rounded.
161 function Get_Allocator_Final_List
165 -- If the designated type is controlled, build final_list expression for
166 -- created object. If context is an access parameter, create a local access
167 -- type to have a usable finalization list.
170 -- Ada 2005 (AI-216): A view of an Unchecked_Union object has inferable
171 -- discriminants if it has a constrained nominal type, unless the object
172 -- is a component of an enclosing Unchecked_Union object that is subject
173 -- to a per-object constraint and the enclosing object lacks inferable
174 -- discriminants.
175 --
176 -- An expression of an Unchecked_Union type has inferable discriminants
177 -- if it is either a name of an object with inferable discriminants or a
178 -- qualified expression whose subtype mark denotes a constrained subtype.
181 -- N is an expression whose type is an access. When the type of the
182 -- associated storage pool is derived from Checked_Pool, generate a
183 -- call to the 'Dereference' primitive operation.
185 function Make_Array_Comparison_Op
188 -- Comparisons between arrays are expanded in line. This function produces
189 -- the body of the implementation of (a > b), where a and b are one-
190 -- dimensional arrays of some discrete type. The original node is then
191 -- expanded into the appropriate call to this function. Nod provides the
192 -- Sloc value for the generated code.
194 function Make_Boolean_Array_Op
197 -- Boolean operations on boolean arrays are expanded in line. This function
198 -- produce the body for the node N, which is (a and b), (a or b), or (a xor
199 -- b). It is used only the normal case and not the packed case. The type
200 -- involved, Typ, is the Boolean array type, and the logical operations in
201 -- the body are simple boolean operations. Note that Typ is always a
202 -- constrained type (the caller has ensured this by using
203 -- Convert_To_Actual_Subtype if necessary).
206 -- If N is the node for a comparison whose outcome can be determined at
207 -- compile time, then the node N can be rewritten with True or False. If
208 -- the outcome cannot be determined at compile time, the call has no
209 -- effect. If N is a type conversion, then this processing is applied to
210 -- its expression. If N is neither comparison nor a type conversion, the
211 -- call has no effect.
213 procedure Tagged_Membership
217 -- Construct the expression corresponding to the tagged membership test.
218 -- Deals with a second operand being (or not) a class-wide type.
220 function Safe_In_Place_Array_Op
224 -- In the context of an assignment, where the right-hand side is a boolean
225 -- operation on arrays, check whether operation can be performed in place.
229 -- Performs validity checks for a unary operator
231 -------------------------------
232 -- Binary_Op_Validity_Checks --
233 -------------------------------
236 begin
243 ------------------------------------
244 -- Build_Boolean_Array_Proc_Call --
245 ------------------------------------
247 procedure Build_Boolean_Array_Proc_Call
251 is
264 begin
268 -- Use negated version of the binary operators
280 Call_Node :=
285 Target,
298 else
301 Call_Node :=
305 Target,
316 else
317 -- We use the following equivalences:
319 -- (not X) or (not Y) = not (X and Y) = Nand (X, Y)
320 -- (not X) and (not Y) = not (X or Y) = Nor (X, Y)
321 -- (not X) xor (not Y) = X xor Y
322 -- X xor (not Y) = not (X xor Y) = Nxor (X, Y)
331 else
335 else
343 else
348 Call_Node :=
352 Target,
367 exception
372 --------------------------------
373 -- Displace_Allocator_Pointer --
374 --------------------------------
383 begin
384 -- Do nothing in case of VM targets: the virtual machine will handle
385 -- interfaces directly.
400 then
401 -- If the type of the allocator expression is not an interface type
402 -- we can generate code to reference the record component containing
403 -- the pointer to the secondary dispatch table.
406 declare
409 begin
410 -- 1) Get access to the allocated object
418 -- 2) Add the conversion to displace the pointer to reference
419 -- the secondary dispatch table.
424 -- 3) The 'access to the secondary dispatch table will be used
425 -- as the value returned by the allocator.
435 -- If the type of the allocator expression is an interface type we
436 -- generate a run-time call to displace "this" to reference the
437 -- component containing the pointer to the secondary dispatch table
438 -- or else raise Constraint_Error if the actual object does not
439 -- implement the target interface. This case corresponds with the
440 -- following example:
442 -- function Op (Obj : Iface_1'Class) return access Iface_2'Class is
443 -- begin
444 -- return new Iface_2'Class'(Obj);
445 -- end Op;
447 else
456 New_Occurrence_Of
458 (First_Elmt
460 Loc)))));
466 ---------------------------------
467 -- Expand_Allocator_Expression --
468 ---------------------------------
476 procedure Apply_Accessibility_Check
479 -- Ada 2005 (AI-344): For an allocator with a class-wide designated
480 -- type, generate an accessibility check to verify that the level of the
481 -- type of the created object is not deeper than the level of the access
482 -- type. If the type of the qualified expression is class- wide, then
483 -- always generate the check (except in the case where it is known to be
484 -- unnecessary, see comment below). Otherwise, only generate the check
485 -- if the level of the qualified expression type is statically deeper
486 -- than the access type.
487 --
488 -- Although the static accessibility will generally have been performed
489 -- as a legality check, it won't have been done in cases where the
490 -- allocator appears in generic body, so a run-time check is needed in
491 -- general. One special case is when the access type is declared in the
492 -- same scope as the class-wide allocator, in which case the check can
493 -- never fail, so it need not be generated.
494 --
495 -- As an open issue, there seem to be cases where the static level
496 -- associated with the class-wide object's underlying type is not
497 -- sufficient to perform the proper accessibility check, such as for
498 -- allocators in nested subprograms or accept statements initialized by
499 -- class-wide formals when the actual originates outside at a deeper
500 -- static level. The nested subprogram case might require passing
501 -- accessibility levels along with class-wide parameters, and the task
502 -- case seems to be an actual gap in the language rules that needs to
503 -- be fixed by the ARG. ???
505 -------------------------------
506 -- Apply_Accessibility_Check --
507 -------------------------------
509 procedure Apply_Accessibility_Check
512 is
515 begin
516 -- Note: we skip the accessibility check for the VM case, since
517 -- there does not seem to be any practical way of implementing it.
520 and then Tagged_Type_Expansion
523 and then
525 or else
528 then
529 -- If the allocator was built in place Ref is already a reference
530 -- to the access object initialized to the result of the allocator
531 -- (see Exp_Ch6.Make_Build_In_Place_Call_In_Allocator). Otherwise
532 -- it is the entity associated with the object containing the
533 -- address of the allocated object.
537 else
543 Condition =>
545 Left_Opnd =>
550 Right_Opnd =>
557 -- Local variables
566 -- Type used as source for tag assignment
569 -- Target reference for tag assignment
576 -- Start of processing for Expand_Allocator_Expression
578 begin
583 -- Generate:
584 -- Pnnn : constant ptr_T := new (T); Init (Pnnn.all,...); Pnnn
586 -- Allocate the object with no expression
591 -- Avoid its expansion to avoid generating a call to the default
592 -- C++ constructor
607 -- Locate the enclosing list and insert the C++ constructor call
609 declare
612 begin
620 Id_Ref =>
632 -- Ada 2005 (AI-318-02): If the initialization expression is a call
633 -- to a build-in-place function, then access to the allocated object
634 -- must be passed to the function. Currently we limit such functions
635 -- to those with constrained limited result subtypes, but eventually
636 -- we plan to expand the allowed forms of functions that are treated
637 -- as build-in-place.
641 then
647 -- Actions inserted before:
648 -- Temp : constant ptr_T := new T'(Expression);
649 -- <no CW> Temp._tag := T'tag;
650 -- <CTRL> Adjust (Finalizable (Temp.all));
651 -- <CTRL> Attach_To_Final_List (Finalizable (Temp.all));
653 -- We analyze by hand the new internal allocator to avoid
654 -- any recursion and inappropriate call to Initialize
656 -- We don't want to remove side effects when the expression must be
657 -- built in place. In the case of a build-in-place function call,
658 -- that could lead to a duplication of the call, which was already
659 -- substituted for the allocator.
667 -- For a class wide allocation generate the following code:
669 -- type Equiv_Record is record ... end record;
670 -- implicit subtype CW is <Class_Wide_Subytpe>;
671 -- temp : PtrT := new CW'(CW!(expr));
676 -- Ada 2005 (AI-251): If the expression is a class-wide interface
677 -- object we generate code to move up "this" to reference the
678 -- base of the object before allocating the new object.
680 -- Note that Exp'Address is recursively expanded into a call
681 -- to Base_Address (Exp.Tag)
685 and then Tagged_Type_Expansion
686 then
687 Set_Expression
696 else
697 Set_Expression
705 -- Keep separate the management of allocators returning interfaces
709 Tmp_Node :=
713 Expression =>
717 -- Copy the Comes_From_Source flag for the allocator we just
718 -- built, since logically this allocator is a replacement of
719 -- the original allocator node. This is for proper handling of
720 -- restriction No_Implicit_Heap_Allocations.
722 Set_Comes_From_Source
730 then
731 -- Create local finalization list for access parameter
738 else
749 -- Ada 2005 (AI-251): Handle allocators whose designated type is an
750 -- interface type. In this case we use the type of the qualified
751 -- expression to allocate the object.
753 else
754 declare
758 begin
759 New_Decl :=
762 Type_Definition =>
767 Subtype_Indication =>
772 -- Inherit the final chain to ensure that the expansion of the
773 -- aggregate is correct in case of controlled types
780 -- Declare the object using the previous type declaration
783 Tmp_Node :=
787 Expression =>
791 -- Copy the Comes_From_Source flag for the allocator we just
792 -- built, since logically this allocator is a replacement of
793 -- the original allocator node. This is for proper handling
794 -- of restriction No_Implicit_Heap_Allocations.
796 Set_Comes_From_Source
804 then
805 -- Create local finalization list for access parameter
807 Flist :=
812 else
823 -- Generate an additional object containing the address of the
824 -- returned object. The type of this second object declaration
825 -- is the correct type required for the common processing that
826 -- is still performed by this subprogram. The displacement of
827 -- this pointer to reference the component associated with the
828 -- interface type will be done at the end of common processing.
830 New_Decl :=
846 -- Generate the tag assignment
848 -- Suppress the tag assignment when VM_Target because VM tags are
849 -- represented implicitly in objects.
854 -- Ada 2005 (AI-251): Suppress the tag assignment with class-wide
855 -- interface objects because in this case the tag does not change.
868 then
870 TagR :=
877 Tag_Assign :=
879 Name =>
882 Selector_Name =>
885 Expression =>
887 New_Reference_To
889 Loc)));
891 -- The previous assignment has to be done in any case
899 then
900 declare
905 begin
906 -- If it is an allocation on the secondary stack (i.e. a value
907 -- returned from a function), the object is attached on the
908 -- caller side as soon as the call is completed (see
909 -- Expand_Ctrl_Function_Call)
912 declare
914 begin
918 Object_Definition =>
924 -- Normal case, not a secondary stack allocation
926 else
929 then
930 -- Create local finalization list for access parameter
932 Flist :=
934 else
941 -- Generate an Adjust call if the object will be moved. In Ada
942 -- 2005, the object may be inherently limited, in which case
943 -- there is no Adjust procedure, and the object is built in
944 -- place. In Ada 95, the object can be limited but not
945 -- inherently limited if this allocator came from a return
946 -- statement (we're allocating the result on the secondary
947 -- stack). In that case, the object will be moved, so we _do_
948 -- want to Adjust.
950 if not Aggr_In_Place
952 then
954 Make_Adjust_Call (
955 Ref =>
957 -- An unchecked conversion is needed in the classwide
958 -- case because the designated type can be an ancestor of
959 -- the subtype mark of the allocator.
976 -- Ada 2005 (AI-251): Displace the pointer to reference the record
977 -- component containing the secondary dispatch table of the interface
978 -- type.
986 Tmp_Node :=
993 -- Copy the Comes_From_Source flag for the allocator we just built,
994 -- since logically this allocator is a replacement of the original
995 -- allocator node. This is for proper handling of restriction
996 -- No_Implicit_Heap_Allocations.
998 Set_Comes_From_Source
1009 then
1015 then
1016 -- Apply constraint to designated subtype indication
1024 -- Propagate constraint_error to enclosing allocator
1028 else
1029 -- If we have:
1030 -- type A is access T1;
1031 -- X : A := new T2'(...);
1032 -- T1 and T2 can be different subtypes, and we might need to check
1033 -- both constraints. First check against the type of the qualified
1034 -- expression.
1043 -- A check is also needed in cases where the designated subtype is
1044 -- constrained and differs from the subtype given in the qualified
1045 -- expression. Note that the check on the qualified expression does
1046 -- not allow sliding, but this check does (a relaxation from Ada 83).
1050 then
1051 Apply_Constraint_Check
1060 -- For an access to unconstrained packed array, GIGI needs to see an
1061 -- expression with a constrained subtype in order to compute the
1062 -- proper size for the allocator.
1067 then
1068 declare
1071 begin
1075 Subtype_Indication =>
1082 -- Ada 2005 (AI-318-02): If the initialization expression is a call
1083 -- to a build-in-place function, then access to the allocated object
1084 -- must be passed to the function. Currently we limit such functions
1085 -- to those with constrained limited result subtypes, but eventually
1086 -- we plan to expand the allowed forms of functions that are treated
1087 -- as build-in-place.
1091 then
1096 exception
1101 -----------------------------
1102 -- Expand_Array_Comparison --
1103 -----------------------------
1105 -- Expansion is only required in the case of array types. For the unpacked
1106 -- case, an appropriate runtime routine is called. For packed cases, and
1107 -- also in some other cases where a runtime routine cannot be called, the
1108 -- form of the expansion is:
1110 -- [body for greater_nn; boolean_expression]
1112 -- The body is built by Make_Array_Comparison_Op, and the form of the
1113 -- Boolean expression depends on the operator involved.
1129 -- True for byte addressable target
1132 -- Returns True if the length of the given operand is known to be less
1133 -- than 4. Returns False if this length is known to be four or greater
1134 -- or is not known at compile time.
1136 ------------------------
1137 -- Length_Less_Than_4 --
1138 ------------------------
1143 begin
1147 else
1148 declare
1155 begin
1158 else
1164 else
1173 -- Start of processing for Expand_Array_Comparison
1175 begin
1176 -- Deal first with unpacked case, where we can call a runtime routine
1177 -- except that we avoid this for targets for which are not addressable
1178 -- by bytes, and for the JVM/CIL, since they do not support direct
1179 -- addressing of array components.
1182 and then Byte_Addressable
1184 then
1185 -- The call we generate is:
1187 -- Compare_Array_xn[_Unaligned]
1188 -- (left'address, right'address, left'length, right'length) <op> 0
1190 -- x = U for unsigned, S for signed
1191 -- n = 8,16,32,64 for component size
1192 -- Add _Unaligned if length < 4 and component size is 8.
1193 -- <op> is the standard comparison operator
1197 or else
1199 then
1202 else
1206 else
1209 else
1217 else
1224 else
1231 else
1269 -- Cases where we cannot make runtime call
1271 -- For (a <= b) we convert to not (a > b)
1276 Right_Opnd =>
1283 -- For < the Boolean expression is
1284 -- greater__nn (op2, op1)
1289 -- Switch operands
1294 -- For (a >= b) we convert to not (a < b)
1299 Right_Opnd =>
1306 -- For > the Boolean expression is
1307 -- greater__nn (op1, op2)
1309 else
1315 Expr :=
1324 exception
1329 ---------------------------
1330 -- Expand_Array_Equality --
1331 ---------------------------
1333 -- Expand an equality function for multi-dimensional arrays. Here is an
1334 -- example of such a function for Nb_Dimension = 2
1336 -- function Enn (A : atyp; B : btyp) return boolean is
1337 -- begin
1338 -- if (A'length (1) = 0 or else A'length (2) = 0)
1339 -- and then
1340 -- (B'length (1) = 0 or else B'length (2) = 0)
1341 -- then
1342 -- return True; -- RM 4.5.2(22)
1343 -- end if;
1345 -- if A'length (1) /= B'length (1)
1346 -- or else
1347 -- A'length (2) /= B'length (2)
1348 -- then
1349 -- return False; -- RM 4.5.2(23)
1350 -- end if;
1352 -- declare
1353 -- A1 : Index_T1 := A'first (1);
1354 -- B1 : Index_T1 := B'first (1);
1355 -- begin
1356 -- loop
1357 -- declare
1358 -- A2 : Index_T2 := A'first (2);
1359 -- B2 : Index_T2 := B'first (2);
1360 -- begin
1361 -- loop
1362 -- if A (A1, A2) /= B (B1, B2) then
1363 -- return False;
1364 -- end if;
1366 -- exit when A2 = A'last (2);
1367 -- A2 := Index_T2'succ (A2);
1368 -- B2 := Index_T2'succ (B2);
1369 -- end loop;
1370 -- end;
1372 -- exit when A1 = A'last (1);
1373 -- A1 := Index_T1'succ (A1);
1374 -- B1 := Index_T1'succ (B1);
1375 -- end loop;
1376 -- end;
1378 -- return true;
1379 -- end Enn;
1381 -- Note on the formal types used (atyp and btyp). If either of the arrays
1382 -- is of a private type, we use the underlying type, and do an unchecked
1383 -- conversion of the actual. If either of the arrays has a bound depending
1384 -- on a discriminant, then we use the base type since otherwise we have an
1385 -- escaped discriminant in the function.
1387 -- If both arrays are constrained and have the same bounds, we can generate
1388 -- a loop with an explicit iteration scheme using a 'Range attribute over
1389 -- the first array.
1391 function Expand_Array_Equality
1397 is
1413 -- The parameter types to be used for the formals
1415 function Arr_Attr
1419 -- This builds the attribute reference Arr'Nam (Expr)
1422 -- Create one statement to compare corresponding components, designated
1423 -- by a full set of indexes.
1426 -- Given one of the arguments, computes the appropriate type to be used
1427 -- for that argument in the corresponding function formal
1429 function Handle_One_Dimension
1432 -- This procedure returns the following code
1433 --
1434 -- declare
1435 -- Bn : Index_T := B'First (N);
1436 -- begin
1437 -- loop
1438 -- xxx
1439 -- exit when An = A'Last (N);
1440 -- An := Index_T'Succ (An)
1441 -- Bn := Index_T'Succ (Bn)
1442 -- end loop;
1443 -- end;
1444 --
1445 -- If both indexes are constrained and identical, the procedure
1446 -- returns a simpler loop:
1447 --
1448 -- for An in A'Range (N) loop
1449 -- xxx
1450 -- end loop
1451 --
1452 -- N is the dimension for which we are generating a loop. Index is the
1453 -- N'th index node, whose Etype is Index_Type_n in the above code. The
1454 -- xxx statement is either the loop or declare for the next dimension
1455 -- or if this is the last dimension the comparison of corresponding
1456 -- components of the arrays.
1457 --
1458 -- The actual way the code works is to return the comparison of
1459 -- corresponding components for the N+1 call. That's neater!
1462 -- This function constructs the test for both arrays being empty
1463 -- (A'length (1) = 0 or else A'length (2) = 0 or else ...)
1464 -- and then
1465 -- (B'length (1) = 0 or else B'length (2) = 0 or else ...)
1468 -- This function constructs the test for arrays having different lengths
1469 -- in at least one index position, in which case the resulting code is:
1471 -- A'length (1) /= B'length (1)
1472 -- or else
1473 -- A'length (2) /= B'length (2)
1474 -- or else
1475 -- ...
1477 --------------
1478 -- Arr_Attr --
1479 --------------
1481 function Arr_Attr
1485 is
1486 begin
1487 return
1494 ------------------------
1495 -- Component_Equality --
1496 ------------------------
1502 begin
1503 -- if a(i1...) /= b(j1...) then return false; end if;
1505 L :=
1510 R :=
1515 Test := Expand_Composite_Equality
1518 -- If some (sub)component is an unchecked_union, the whole operation
1519 -- will raise program error.
1523 -- This node is going to be inserted at a location where a
1524 -- statement is expected: clear its Etype so analysis will set
1525 -- it to the expected Standard_Void_Type.
1530 else
1531 return
1540 ------------------
1541 -- Get_Arg_Type --
1542 ------------------
1548 begin
1554 else
1560 or else
1562 then
1574 --------------------------
1575 -- Handle_One_Dimension --
1576 ---------------------------
1578 function Handle_One_Dimension
1581 is
1583 Ltyp /= Rtyp
1585 -- If the index types are identical, and we are working with
1586 -- constrained types, then we can use the same index for both
1587 -- of the arrays.
1596 begin
1601 -- Case where we generate a loop
1607 else
1619 -- Generate guard for loop, followed by increments of indexes
1623 Condition =>
1631 Expression =>
1640 Expression =>
1647 -- If separate indexes, we need a declare block for An and Bn, and a
1648 -- loop without an iteration scheme.
1651 Loop_Stm :=
1654 return
1667 Handled_Statement_Sequence =>
1671 -- If no separate indexes, return loop statement with explicit
1672 -- iteration scheme on its own
1674 else
1675 Loop_Stm :=
1678 Iteration_Scheme =>
1680 Loop_Parameter_Specification =>
1683 Discrete_Subtype_Definition =>
1689 -----------------------
1690 -- Test_Empty_Arrays --
1691 -----------------------
1700 begin
1704 Atest :=
1709 Btest :=
1718 else
1719 Alist :=
1724 Blist :=
1731 return
1737 -----------------------------
1738 -- Test_Lengths_Correspond --
1739 -----------------------------
1745 begin
1748 Rtest :=
1755 else
1756 Result :=
1766 -- Start of processing for Expand_Array_Equality
1768 begin
1772 -- For now, if the argument types are not the same, go to the base type,
1773 -- since the code assumes that the formals have the same type. This is
1774 -- fixable in future ???
1782 -- Build list of formals for function
1795 -- Build statement sequence for function
1797 Func_Body :=
1799 Specification =>
1807 Handled_Statement_Sequence =>
1815 Expression =>
1822 Expression =>
1833 -- If the array type is distinct from the type of the arguments, it
1834 -- is the full view of a private type. Apply an unchecked conversion
1835 -- to insure that analysis of the call succeeds.
1837 declare
1840 begin
1846 then
1852 then
1861 return
1867 -----------------------------
1868 -- Expand_Boolean_Operator --
1869 -----------------------------
1871 -- Note that we first get the actual subtypes of the operands, since we
1872 -- always want to deal with types that have bounds.
1877 begin
1878 -- Special case of bit packed array where both operands are known to be
1879 -- properly aligned. In this case we use an efficient run time routine
1880 -- to carry out the operation (see System.Bit_Ops).
1885 then
1890 -- For the normal non-packed case, the general expansion is to build
1891 -- function for carrying out the comparison (use Make_Boolean_Array_Op)
1892 -- and then inserting it into the tree. The original operator node is
1893 -- then rewritten as a call to this function. We also use this in the
1894 -- packed case if either operand is a possibly unaligned object.
1896 declare
1903 begin
1916 then
1921 and then
1923 then
1925 else
1931 -- Now rewrite the expression with a call
1936 Parameter_Associations =>
1937 New_List (
1938 L,
1939 Make_Type_Conversion
1947 -------------------------------
1948 -- Expand_Composite_Equality --
1949 -------------------------------
1951 -- This function is only called for comparing internal fields of composite
1952 -- types when these fields are themselves composites. This is a special
1953 -- case because it is not possible to respect normal Ada visibility rules.
1955 function Expand_Composite_Equality
1961 is
1967 begin
1970 else
1974 -- Defense against malformed private types with no completion the error
1975 -- will be diagnosed later by check_completion
1985 -- If the operand is an elementary type other than a floating-point
1986 -- type, then we can simply use the built-in block bitwise equality,
1987 -- since the predefined equality operators always apply and bitwise
1988 -- equality is fine for all these cases.
1992 then
1995 -- For composite component types, and floating-point types, use the
1996 -- expansion. This deals with tagged component types (where we use
1997 -- the applicable equality routine) and floating-point, (where we
1998 -- need to worry about negative zeroes), and also the case of any
1999 -- composite type recursively containing such fields.
2001 else
2007 -- Call the primitive operation "=" of this type
2013 -- If this is derived from an untagged private type completed with a
2014 -- tagged type, it does not have a full view, so we use the primitive
2015 -- operations of the private type. This check should no longer be
2016 -- necessary when these types receive their full views ???
2023 then
2025 else
2029 loop
2041 return
2044 Parameter_Associations =>
2045 New_List
2055 -- Inherited equality from parent type. Convert the actuals to
2056 -- match signature of operation.
2058 declare
2061 begin
2062 return
2065 Parameter_Associations =>
2070 else
2071 -- Comparison between Unchecked_Union components
2074 declare
2080 begin
2081 -- Lhs subtype
2087 -- Rhs subtype
2093 -- Lhs of the composite equality
2097 -- Since the enclosing record type can never be an
2098 -- Unchecked_Union (this code is executed for records
2099 -- that do not have variants), we may reference its
2100 -- discriminant(s).
2105 then
2106 Lhs_Discr_Val :=
2109 Selector_Name =>
2110 New_Copy (
2111 Get_Discriminant_Value (
2113 Lhs_Type,
2116 else
2118 Get_Discriminant_Value (
2120 Lhs_Type,
2124 else
2125 -- It is not possible to infer the discriminant since
2126 -- the subtype is not constrained.
2128 return
2133 -- Rhs of the composite equality
2139 then
2140 Rhs_Discr_Val :=
2143 Selector_Name =>
2144 New_Copy (
2145 Get_Discriminant_Value (
2147 Rhs_Type,
2150 else
2152 Get_Discriminant_Value (
2154 Rhs_Type,
2158 else
2159 return
2164 -- Call the TSS equality function with the inferred
2165 -- discriminant values.
2167 return
2171 Lhs,
2172 Rhs,
2173 Lhs_Discr_Val,
2174 Rhs_Discr_Val));
2177 else
2178 return
2187 -- if no TSS has been created for the type, check whether there is
2188 -- a primitive equality declared for it. If it is abstract replace
2189 -- the call with an explicit raise (AI05-0123).
2191 declare
2194 begin
2198 -- Locate primitive equality with the right signature
2204 then
2206 return
2209 else
2210 return
2221 -- Use predefined equality iff no user-defined primitive exists
2225 else
2229 else
2230 -- If not array or record type, it is predefined equality.
2236 ------------------------
2237 -- Expand_Concatenate --
2238 ------------------------
2244 -- Result type of concatenation
2247 -- Component type. Elements of this component type can appear as one
2248 -- of the operands of concatenation as well as arrays.
2251 -- Index subtype
2254 -- Index type. This is the base type of the index subtype, and is used
2255 -- for all computed bounds (which may be out of range of Istyp in the
2256 -- case of null ranges).
2259 -- This is the type we use to do arithmetic to compute the bounds and
2260 -- lengths of operands. The choice of this type is a little subtle and
2261 -- is discussed in a separate section at the start of the body code.
2264 -- Raised if concatenation is sure to raise a CE
2267 -- Reset to False if at least one operand is encountered which is known
2268 -- at compile time to be non-null. Used for handling the special case
2269 -- of setting the high bound to the last operand high bound for a null
2270 -- result, thus ensuring a proper high bound in the super-flat case.
2273 -- Number of concatenation operands including possibly null operands
2276 -- Number of operands excluding any known to be null, except that the
2277 -- last operand is always retained, in case it provides the bounds for
2278 -- a null result.
2281 -- Current operand being processed in the loop through operands. After
2282 -- this loop is complete, always contains the last operand (which is not
2283 -- the same as Operands (NN), since null operands are skipped).
2285 -- Arrays describing the operands, only the first NN entries of each
2286 -- array are set (NN < N when we exclude known null operands).
2289 -- True if length of corresponding operand known at compile time
2292 -- Set to the corresponding entry in the Opnds list (but note that null
2293 -- operands are excluded, so not all entries in the list are stored).
2296 -- Set to length of operand. Entries in this array are set only if the
2297 -- corresponding entry in Is_Fixed_Length is True.
2300 -- Set to lower bound of operand. Either an integer literal in the case
2301 -- where the bound is known at compile time, else actual lower bound.
2302 -- The operand low bound is of type Ityp.
2305 -- Set to an entity of type Natural that contains the length of an
2306 -- operand whose length is not known at compile time. Entries in this
2307 -- array are set only if the corresponding entry in Is_Fixed_Length
2308 -- is False. The entity is of type Artyp.
2311 -- The J'th entry in an expression node that represents the total length
2312 -- of operands 1 through J. It is either an integer literal node, or a
2313 -- reference to a constant entity with the right value, so it is fine
2314 -- to just do a Copy_Node to get an appropriate copy. The extra zero'th
2315 -- entry always is set to zero. The length is of type Artyp.
2318 -- A tree node representing the low bound of the result (of type Ityp).
2319 -- This is either an integer literal node, or an identifier reference to
2320 -- a constant entity initialized to the appropriate value.
2323 -- A tree node representing the high bound of the last operand. This
2324 -- need only be set if the result could be null. It is used for the
2325 -- special case of setting the right high bound for a null result.
2326 -- This is of type Ityp.
2329 -- A tree node representing the high bound of the result (of type Ityp)
2332 -- Result of the concatenation (of type Ityp)
2335 -- Collect actions to be inserted if Save_Space is False
2339 -- Set to True if we are saving generated code space by calling routines
2340 -- in packages System.Concat_n.
2343 -- Set True during generation of the assignments of operands into
2344 -- result once an operand known to be non-null has been seen.
2347 -- This function makes an N_Integer_Literal node that is returned in
2348 -- analyzed form with the type set to Artyp. Importantly this literal
2349 -- is not flagged as static, so that if we do computations with it that
2350 -- result in statically detected out of range conditions, we will not
2351 -- generate error messages but instead warning messages.
2354 -- Given a node of type Ityp, returns the corresponding value of type
2355 -- Artyp. For non-enumeration types, this is a plain integer conversion.
2356 -- For enum types, the Pos of the value is returned.
2359 -- The inverse function (uses Val in the case of enumeration types)
2361 ------------------------
2362 -- Make_Artyp_Literal --
2363 ------------------------
2367 begin
2374 --------------
2375 -- To_Artyp --
2376 --------------
2379 begin
2384 return
2390 else
2395 -------------
2396 -- To_Ityp --
2397 -------------
2400 begin
2402 return
2408 -- Case where we will do a type conversion
2410 else
2413 else
2419 -- Local Declarations
2428 begin
2429 -- Choose an appropriate computational type
2431 -- We will be doing calculations of lengths and bounds in this routine
2432 -- and computing one from the other in some cases, e.g. getting the high
2433 -- bound by adding the length-1 to the low bound.
2435 -- We can't just use the index type, or even its base type for this
2436 -- purpose for two reasons. First it might be an enumeration type which
2437 -- is not suitable for computations of any kind, and second it may
2438 -- simply not have enough range. For example if the index type is
2439 -- -128..+127 then lengths can be up to 256, which is out of range of
2440 -- the type.
2442 -- For enumeration types, we can simply use Standard_Integer, this is
2443 -- sufficient since the actual number of enumeration literals cannot
2444 -- possibly exceed the range of integer (remember we will be doing the
2445 -- arithmetic with POS values, not representation values).
2450 -- If index type is Positive, we use the standard unsigned type, to give
2451 -- more room on the top of the range, obviating the need for an overflow
2452 -- check when creating the upper bound. This is needed to avoid junk
2453 -- overflow checks in the common case of String types.
2455 -- ??? Disabled for now
2457 -- elsif Istyp = Standard_Positive then
2458 -- Artyp := Standard_Unsigned;
2460 -- For modular types, we use a 32-bit modular type for types whose size
2461 -- is in the range 1-31 bits. For 32-bit unsigned types, we use the
2462 -- identity type, and for larger unsigned types we use 64-bits.
2469 else
2473 -- Similar treatment for signed types
2475 else
2480 else
2485 -- Supply dummy entry at start of length array
2489 -- Go through operands setting up the above arrays
2496 -- The parent got messed up when we put the operands in a list,
2497 -- so now put back the proper parent for the saved operand, that
2498 -- is to say the concatenation node, to make sure that each operand
2499 -- is seen as a subexpression, e.g. if actions must be inserted.
2503 -- Set will be True when we have setup one entry in the array
2507 -- Singleton element (or character literal) case
2516 -- Set low bound of operand (no need to set Last_Opnd_High_Bound
2517 -- since we know that the result cannot be null).
2526 -- String literal case (can only occur for strings of course)
2535 -- Capture last operand high bound if result could be null
2538 Last_Opnd_High_Bound :=
2540 Left_Opnd =>
2545 -- Skip null string literal
2555 -- Set length and bounds
2564 -- All other cases
2566 else
2567 -- Check constrained case with known bounds
2570 declare
2576 begin
2577 -- Fixed length constrained array type with known at compile
2578 -- time bounds is last case of fixed length operand.
2581 and then
2583 then
2584 declare
2590 begin
2595 -- Capture last operand bound if result could be null
2598 Last_Opnd_High_Bound :=
2604 -- Exclude null length case unless last operand
2625 -- All cases where the length is not known at compile time, or the
2626 -- special case of an operand which is known to be null but has a
2627 -- lower bound other than 1 or is other than a string type.
2632 -- Capture operand bounds
2636 Prefix =>
2641 Last_Opnd_High_Bound :=
2644 Prefix =>
2649 -- Capture length of operand in entity
2661 Object_Definition =>
2664 Expression =>
2666 Prefix =>
2672 -- Set next entry in aggregate length array
2674 -- For first entry, make either integer literal for fixed length
2675 -- or a reference to the saved length for variable length.
2682 else
2687 -- If entry is fixed length and only fixed lengths so far, make
2688 -- appropriate new integer literal adding new length.
2692 then
2697 -- All other cases, construct an addition node for the length and
2698 -- create an entity initialized to this length.
2700 else
2705 else
2714 Object_Definition =>
2717 Expression =>
2729 -- If we have only skipped null operands, return the last operand
2736 -- If we have only one non-null operand, return it and we are done.
2737 -- There is one case in which this cannot be done, and that is when
2738 -- the sole operand is of the element type, in which case it must be
2739 -- converted to an array, and the easiest way of doing that is to go
2740 -- through the normal general circuit.
2744 then
2749 -- Cases where we have a real concatenation
2751 -- Next step is to find the low bound for the result array that we
2752 -- will allocate. The rules for this are in (RM 4.5.6(5-7)).
2754 -- If the ultimate ancestor of the index subtype is a constrained array
2755 -- definition, then the lower bound is that of the index subtype as
2756 -- specified by (RM 4.5.3(6)).
2758 -- The right test here is to go to the root type, and then the ultimate
2759 -- ancestor is the first subtype of this root type.
2762 Low_Bound :=
2764 Prefix =>
2768 -- If the first operand in the list has known length we know that
2769 -- the lower bound of the result is the lower bound of this operand.
2774 -- OK, we don't know the lower bound, we have to build a horrible
2775 -- expression actions node of the form
2777 -- if Cond1'Length /= 0 then
2778 -- Opnd1 low bound
2779 -- else
2780 -- if Opnd2'Length /= 0 then
2781 -- Opnd2 low bound
2782 -- else
2783 -- ...
2785 -- The nesting ends either when we hit an operand whose length is known
2786 -- at compile time, or on reaching the last operand, whose low bound we
2787 -- take unconditionally whether or not it is null. It's easiest to do
2788 -- this with a recursive procedure:
2790 else
2791 declare
2793 -- Returns the lower bound determined by operands J .. NN
2795 ---------------------
2796 -- Get_Known_Bound --
2797 ---------------------
2800 begin
2804 else
2805 return
2818 begin
2832 -- Now we can safely compute the upper bound, normally
2833 -- Low_Bound + Length - 1.
2835 High_Bound :=
2836 To_Ityp (
2839 Right_Opnd =>
2844 -- Note that calculation of the high bound may cause overflow in some
2845 -- very weird cases, so in the general case we need an overflow check on
2846 -- the high bound. We can avoid this for the common case of string types
2847 -- and other types whose index is Positive, since we chose a wider range
2848 -- for the arithmetic type.
2854 -- Handle the exceptional case where the result is null, in which case
2855 -- case the bounds come from the last operand (so that we get the proper
2856 -- bounds if the last operand is super-flat).
2859 High_Bound :=
2865 Last_Opnd_High_Bound,
2866 High_Bound));
2869 -- Here is where we insert the saved up actions
2873 -- Now we construct an array object with appropriate bounds. We mark
2874 -- the target as internal to prevent useless initialization when
2875 -- Initialize_Scalars is enabled.
2880 -- If the bound is statically known to be out of range, we do not want
2881 -- to abort, we want a warning and a runtime constraint error. Note that
2882 -- we have arranged that the result will not be treated as a static
2883 -- constant, so we won't get an illegality during this insertion.
2888 Object_Definition =>
2891 Constraint =>
2899 -- If the result of the concatenation appears as the initializing
2900 -- expression of an object declaration, we can just rename the
2901 -- result, rather than copying it.
2905 -- Catch the static out of range case now
2911 -- Now we will generate the assignments to do the actual concatenation
2913 -- There is one case in which we will not do this, namely when all the
2914 -- following conditions are met:
2916 -- The result type is Standard.String
2918 -- There are nine or fewer retained (non-null) operands
2920 -- The optimization level is -O0
2922 -- The corresponding System.Concat_n.Str_Concat_n routine is
2923 -- available in the run time.
2925 -- The debug flag gnatd.c is not set
2927 -- If all these conditions are met then we generate a call to the
2928 -- relevant concatenation routine. The purpose of this is to avoid
2929 -- undesirable code bloat at -O0.
2934 and then not Debug_Flag_Dot_C
2935 then
2936 declare
2939 RE_Str_Concat_3,
2940 RE_Str_Concat_4,
2941 RE_Str_Concat_5,
2942 RE_Str_Concat_6,
2943 RE_Str_Concat_7,
2944 RE_Str_Concat_8,
2945 RE_Str_Concat_9);
2947 begin
2949 declare
2953 begin
2968 else
2985 -- Not special case so generate the assignments
2990 declare
2999 Right_Opnd =>
3004 begin
3005 -- Singleton case, simple assignment
3011 Name =>
3018 -- Array case, slice assignment, skipped when argument is fixed
3019 -- length and known to be null.
3022 declare
3025 Name =>
3027 Prefix =>
3029 Discrete_Range =>
3034 begin
3040 -- Here if operand length is not statically known and no
3041 -- operand known to be non-null has been processed yet.
3042 -- If operand length is 0, we do not need to perform the
3043 -- assignment, and we must avoid the evaluation of the
3044 -- high bound of the slice, since it may underflow if the
3045 -- low bound is Ityp'First.
3047 Assign :=
3049 Condition =>
3051 Left_Opnd =>
3054 Then_Statements =>
3064 -- Finally we build the result, which is a reference to the array object
3072 exception
3075 -- Kill warning generated for the declaration of the static out of
3076 -- range high bound, and instead generate a Constraint_Error with
3077 -- an appropriate specific message.
3080 Apply_Compile_Time_Constraint_Error
3084 -- Set_Etype (Cnode, Atyp);
3087 ------------------------
3088 -- Expand_N_Allocator --
3089 ------------------------
3101 -- Generate finalization calls for all nested coextensions of N. This
3102 -- routine may allocate list controllers if necessary.
3105 -- Static coextensions have the same lifetime as the entity they
3106 -- constrain. Such occurrences can be rewritten as aliased objects
3107 -- and their unrestricted access used instead of the coextension.
3110 -- Given a constrained array type E, returns a node representing the
3111 -- code to compute the size in storage elements for the given type.
3112 -- This is done without using the attribute (which malfunctions for
3113 -- large sizes ???)
3115 ---------------------------------------
3116 -- Complete_Coextension_Finalization --
3117 ---------------------------------------
3126 -- Determine whether node N is part of a return statement
3129 -- Determine whether node N is a subtype indicator allocator which
3130 -- acts a coextension. Such coextensions need initialization.
3132 -------------------------------
3133 -- Inside_A_Return_Statement --
3134 -------------------------------
3139 begin
3142 if Nkind_In
3144 then
3147 -- Stop the traversal when we reach a subprogram body
3159 -------------------------------
3160 -- Needs_Initialization_Call --
3161 -------------------------------
3166 begin
3170 N_Object_Declaration
3171 then
3174 return
3178 N_Qualified_Expression;
3184 -- Start of processing for Complete_Coextension_Finalization
3186 begin
3187 -- When a coextension root is inside a return statement, we need to
3188 -- use the finalization chain of the function's scope. This does not
3189 -- apply for controlled named access types because in those cases we
3190 -- can use the finalization chain of the type itself.
3193 and then
3195 or else
3198 then
3199 declare
3204 begin
3210 -- Retrieve the declaration of the body
3212 Decl :=
3213 Parent
3214 (Parent
3222 -- Push the scope of the function body since we are inserting
3223 -- the list before the body, but we are currently in the body
3224 -- itself. Override the finalization list of PtrT since the
3225 -- finalization context is now different.
3229 Pop_Scope;
3232 -- The root allocator may not be controlled, but it still needs a
3233 -- finalization list for all nested coextensions.
3239 Flist :=
3241 Prefix =>
3249 -- Generate:
3250 -- typ! (coext.all)
3253 Ref :=
3256 Expression =>
3259 else
3263 -- No initialization call if not allowed
3269 -- Generate:
3270 -- initialize (Ref)
3271 -- attach_to_final_list (Ref, Flist, 2)
3275 Make_Init_Call (
3281 -- Generate:
3282 -- attach_to_final_list (Ref, Flist, 2)
3284 else
3286 Make_Attach_Call (
3297 -------------------------
3298 -- Rewrite_Coextension --
3299 -------------------------
3304 -- Generate:
3305 -- Cnn : aliased Etyp;
3311 Object_Definition =>
3315 begin
3320 -- Find the proper insertion node for the declaration
3341 ------------------------------
3342 -- Size_In_Storage_Elements --
3343 ------------------------------
3346 begin
3347 -- Logically this just returns E'Max_Size_In_Storage_Elements.
3348 -- However, the reason for the existence of this function is
3349 -- to construct a test for sizes too large, which means near the
3350 -- 32-bit limit on a 32-bit machine, and precisely the trouble
3351 -- is that we get overflows when sizes are greater than 2**31.
3353 -- So what we end up doing for array types is to use the expression:
3355 -- number-of-elements * component_type'Max_Size_In_Storage_Elements
3357 -- which avoids this problem. All this is a bit bogus, but it does
3358 -- mean we catch common cases of trying to allocate arrays that
3359 -- are too large, and which in the absence of a check results in
3360 -- undetected chaos ???
3362 declare
3366 begin
3368 Len :=
3378 else
3379 Res :=
3386 return
3389 Right_Opnd =>
3396 -- Start of processing for Expand_N_Allocator
3398 begin
3399 -- RM E.2.3(22). We enforce that the expected type of an allocator
3400 -- shall not be a remote access-to-class-wide-limited-private type
3402 -- Why is this being done at expansion time, seems clearly wrong ???
3406 -- Set the Storage Pool
3419 else
3425 -- Under certain circumstances we can replace an allocator by an access
3426 -- to statically allocated storage. The conditions, as noted in AARM
3427 -- 3.10 (10c) are as follows:
3429 -- Size and initial value is known at compile time
3430 -- Access type is access-to-constant
3432 -- The allocator is not part of a constraint on a record component,
3433 -- because in that case the inserted actions are delayed until the
3434 -- record declaration is fully analyzed, which is too late for the
3435 -- analysis of the rewritten allocator.
3443 then
3444 -- Here we can do the optimization. For the allocator
3446 -- new x'(y)
3448 -- We insert an object declaration
3450 -- Tnn : aliased x := y;
3452 -- and replace the allocator by Tnn'Unrestricted_Access. Tnn is
3453 -- marked as requiring static allocation.
3458 -- If context is constrained, use constrained subtype directly,
3459 -- so that the constant is not labelled as having a nominally
3460 -- unconstrained subtype.
3481 -- We set the variable as statically allocated, since we don't want
3482 -- it going on the stack of the current procedure!
3488 -- Same if the allocator is an access discriminant for a local object:
3489 -- instead of an allocator we create a local value and constrain the
3490 -- enclosing object with the corresponding access attribute.
3497 -- The current allocator creates an object which may contain nested
3498 -- coextensions. Use the current allocator's finalization list to
3499 -- generate finalization call for all nested coextensions.
3502 Complete_Coextension_Finalization;
3505 -- Check for size too large, we do this because the back end misses
3506 -- proper checks here and can generate rubbish allocation calls when
3507 -- we are near the limit. We only do this for the 32-bit address case
3508 -- since that is from a practical point of view where we see a problem.
3514 then
3515 -- The check we want to generate should look like
3517 -- if Etyp'Max_Size_In_Storage_Elements > 3.5 gigabytes then
3518 -- raise Storage_Error;
3519 -- end if;
3521 -- where 3.5 gigabytes is a constant large enough to accommodate any
3522 -- reasonable request for. But we can't do it this way because at
3523 -- least at the moment we don't compute this attribute right, and
3524 -- can silently give wrong results when the result gets large. Since
3525 -- this is all about large results, that's bad, so instead we only
3526 -- apply the check for constrained arrays, and manually compute the
3527 -- value of the attribute ???
3532 Condition =>
3535 Right_Opnd =>
3542 -- Handle case of qualified expression (other than optimization above)
3543 -- First apply constraint checks, because the bounds or discriminants
3544 -- in the aggregate might not match the subtype mark in the allocator.
3547 Apply_Constraint_Check
3554 -- If the allocator is for a type which requires initialization, and
3555 -- there is no initial value (i.e. operand is a subtype indication
3556 -- rather than a qualified expression), then we must generate a call to
3557 -- the initialization routine using an expressions action node:
3559 -- [Pnnn : constant ptr_T := new (T); Init (Pnnn.all,...); Pnnn]
3561 -- Here ptr_T is the pointer type for the allocator, and T is the
3562 -- subtype of the allocator. A special case arises if the designated
3563 -- type of the access type is a task or contains tasks. In this case
3564 -- the call to Init (Temp.all ...) is replaced by code that ensures
3565 -- that tasks get activated (see Exp_Ch9.Build_Task_Allocate_Block
3566 -- for details). In addition, if the type T is a task T, then the
3567 -- first argument to Init must be converted to the task record type.
3569 declare
3582 begin
3586 -- Case of no initialization procedure present
3590 -- Case of simple initialization required
3604 -- No initialization required
3606 else
3610 -- Case of initialization procedure present, must be called
3612 else
3620 -- Construct argument list for the initialization routine call
3622 Arg1 :=
3628 -- The initialization procedure expects a specific type. if the
3629 -- context is access to class wide, indicate that the object
3630 -- being allocated has the right specific type.
3636 -- If designated type is a concurrent type or if it is private
3637 -- type whose definition is a concurrent type, the first
3638 -- argument in the Init routine has to be unchecked conversion
3639 -- to the corresponding record type. If the designated type is
3640 -- a derived type, we also convert the argument to its root
3641 -- type.
3644 Arg1 :=
3650 then
3651 Arg1 :=
3652 Unchecked_Convert_To
3656 declare
3658 begin
3666 -- For the task case, pass the Master_Id of the access type as
3667 -- the value of the _Master parameter, and _Chain as the value
3668 -- of the _Chain parameter (_Chain will be defined as part of
3669 -- the generated code for the allocator).
3671 -- In Ada 2005, the context may be a function that returns an
3672 -- anonymous access type. In that case the Master_Id has been
3673 -- created when expanding the function declaration.
3678 -- The designated type was an incomplete type, and the
3679 -- access type did not get expanded. Salvage it now.
3683 Expand_N_Full_Type_Declaration
3688 -- If the context of the allocator is a declaration or an
3689 -- assignment, we can generate a meaningful image for it,
3690 -- even though subsequent assignments might remove the
3691 -- connection between task and entity. We build this image
3692 -- when the left-hand side is a simple variable, a simple
3693 -- indexed assignment or a simple selected component.
3696 declare
3699 begin
3701 Decls :=
3702 Build_Task_Image_Decls
3704 New_Occurrence_Of
3707 elsif Nkind_In
3710 then
3711 Decls :=
3712 Build_Task_Image_Decls
3714 else
3720 Decls :=
3721 Build_Task_Image_Decls
3724 else
3731 else
3733 New_Reference_To
3743 -- Has_Task is false, Decls not used
3745 else
3749 -- Add discriminants if discriminated type
3751 declare
3755 begin
3763 then
3770 -- If the allocated object will be constrained by the
3771 -- default values for discriminants, then build a subtype
3772 -- with those defaults, and change the allocated subtype
3773 -- to that. Note that this happens in fewer cases in Ada
3774 -- 2005 (AI-363).
3780 or else
3782 then
3792 -- AI-416: when the discriminant constraint is an
3793 -- anonymous access type make sure an accessibility
3794 -- check is inserted if necessary (3.10.2(22.q/2))
3797 and then
3799 then
3800 Apply_Accessibility_Check
3809 -- We set the allocator as analyzed so that when we analyze the
3810 -- expression actions node, we do not get an unwanted recursive
3811 -- expansion of the allocator expression.
3816 -- Here is the transformation:
3817 -- input: new T
3818 -- output: Temp : constant ptr_T := new T;
3819 -- Init (Temp.all, ...);
3820 -- <CTRL> Attach_To_Final_List (Finalizable (Temp.all));
3821 -- <CTRL> Initialize (Finalizable (Temp.all));
3823 -- Here ptr_T is the pointer type for the allocator, and is the
3824 -- subtype of the allocator.
3826 Temp_Decl :=
3836 -- If the designated type is a task type or contains tasks,
3837 -- create block to activate created tasks, and insert
3838 -- declaration for Task_Image variable ahead of call.
3841 declare
3844 begin
3851 else
3860 -- Postpone the generation of a finalization call for the
3861 -- current allocator if it acts as a coextension.
3870 else
3871 Flist :=
3874 -- Anonymous access types created for access parameters
3875 -- are attached to an explicitly constructed controller,
3876 -- which ensures that they can be finalized properly,
3877 -- even if their deallocation might not happen. The list
3878 -- associated with the controller is doubly-linked. For
3879 -- other anonymous access types, the object may end up
3880 -- on the global final list which is singly-linked.
3881 -- Work needed for access discriminants in Ada 2005 ???
3885 else
3890 Make_Init_Call (
3905 -- Ada 2005 (AI-251): If the allocator is for a class-wide interface
3906 -- object that has been rewritten as a reference, we displace "this"
3907 -- to reference properly its secondary dispatch table.
3911 then
3915 exception
3920 -----------------------
3921 -- Expand_N_And_Then --
3922 -----------------------
3927 ------------------------------
3928 -- Expand_N_Case_Expression --
3929 ------------------------------
3942 begin
3943 -- We expand
3945 -- case X is when A => AX, when B => BX ...
3947 -- to
3949 -- do
3950 -- Tnn : typ;
3951 -- case X is
3952 -- when A =>
3953 -- Tnn := AX;
3954 -- when B =>
3955 -- Tnn := BX;
3956 -- ...
3957 -- end case;
3958 -- in Tnn end;
3960 -- However, this expansion is wrong for limited types, and also
3961 -- wrong for unconstrained types (since the bounds may not be the
3962 -- same in all branches). Furthermore it involves an extra copy
3963 -- for large objects. So we take care of this by using the following
3964 -- modified expansion for non-scalar types:
3966 -- do
3967 -- type Pnn is access all typ;
3968 -- Tnn : Pnn;
3969 -- case X is
3970 -- when A =>
3971 -- T := AX'Unrestricted_Access;
3972 -- when B =>
3973 -- T := BX'Unrestricted_Access;
3974 -- ...
3975 -- end case;
3976 -- in Tnn.all end;
3978 Cstmt :=
3985 -- Scalar case
3990 else
3995 Type_Definition =>
3998 Subtype_Indication =>
4009 -- Now process the alternatives
4013 declare
4017 begin
4019 Aexp :=
4025 Append_To
4040 -- Construct and return final expression with actions
4044 else
4045 Fexp :=
4058 -------------------------------------
4059 -- Expand_N_Conditional_Expression --
4060 -------------------------------------
4062 -- Deal with limited types and expression actions
4079 begin
4080 -- Fold at compile time if condition known. We have already folded
4081 -- static conditional expressions, but it is possible to fold any
4082 -- case in which the condition is known at compile time, even though
4083 -- the result is non-static.
4085 -- Note that we don't do the fold of such cases in Sem_Elab because
4086 -- it can cause infinite loops with the expander adding a conditional
4087 -- expression, and Sem_Elab circuitry removing it repeatedly.
4093 else
4102 -- If we are not allowed to use Expression_With_Actions, just
4103 -- skip the optimization, it is not critical for correctness.
4115 else
4119 -- Note that the result is never static (legitimate cases of static
4120 -- conditional expressions were folded in Sem_Eval).
4128 -- If the type is limited or unconstrained, we expand as follows to
4129 -- avoid any possibility of improper copies.
4131 -- Note: it may be possible to avoid this special processing if the
4132 -- back end uses its own mechanisms for handling by-reference types ???
4134 -- type Ptr is access all Typ;
4135 -- Cnn : Ptr;
4136 -- if cond then
4137 -- <<then actions>>
4138 -- Cnn := then-expr'Unrestricted_Access;
4139 -- else
4140 -- <<else actions>>
4141 -- Cnn := else-expr'Unrestricted_Access;
4142 -- end if;
4144 -- and replace the conditional expression by a reference to Cnn.all.
4146 -- This special case can be skipped if the back end handles limited
4147 -- types properly and ensures that no incorrect copies are made.
4150 and then not Back_End_Handles_Limited_Types
4151 then
4154 P_Decl :=
4157 Type_Definition =>
4160 Subtype_Indication =>
4165 Decl :=
4168 Object_Definition =>
4171 New_If :=
4178 Expression =>
4186 Expression =>
4191 New_N :=
4195 -- For other types, we only need to expand if there are other actions
4196 -- associated with either branch.
4200 -- We have two approaches to handling this. If we are allowed to use
4201 -- N_Expression_With_Actions, then we can just wrap the actions into
4202 -- the appropriate expression.
4225 -- if we can't use N_Expression_With_Actions nodes, then we insert
4226 -- the following sequence of actions (using Insert_Actions):
4228 -- Cnn : typ;
4229 -- if cond then
4230 -- <<then actions>>
4231 -- Cnn := then-expr;
4232 -- else
4233 -- <<else actions>>
4234 -- Cnn := else-expr
4235 -- end if;
4237 -- and replace the conditional expression by a reference to Cnn
4239 else
4242 Decl :=
4247 New_If :=
4267 -- If no actions then no expansion needed, gigi will handle it using
4268 -- the same approach as a C conditional expression.
4270 else
4274 -- Fall through here for either the limited expansion, or the case of
4275 -- inserting actions for non-limited types. In both these cases, we must
4276 -- move the SLOC of the parent If statement to the newly created one and
4277 -- change it to the SLOC of the expression which, after expansion, will
4278 -- correspond to what is being evaluated.
4282 then
4287 -- Make sure Then_Actions and Else_Actions are appropriately moved
4288 -- to the new if statement.
4291 Insert_List_Before
4296 Insert_List_Before
4306 -----------------------------------
4307 -- Expand_N_Explicit_Dereference --
4308 -----------------------------------
4311 begin
4312 -- Insert explicit dereference call for the checked storage pool case
4317 -----------------
4318 -- Expand_N_In --
4319 -----------------
4332 -- For each choice we create a simple equality or membership test.
4333 -- The whole membership is rewritten connecting these with OR ELSE.
4335 ---------------------------
4336 -- Expand_Set_Membership --
4337 ---------------------------
4344 -- If the alternative is a subtype mark, create a simple membership
4345 -- test. Otherwise create an equality test for it.
4347 ---------------
4348 -- Make_Cond --
4349 ---------------
4356 begin
4359 then
4360 Cond :=
4364 else
4365 Cond :=
4374 -- Start of processing for Expand_Set_Membership
4376 begin
4382 Res :=
4394 -- Replaces node N by Lop'Valid. This is done when we have an explicit
4395 -- test for the left operand being in range of its subtype.
4397 ----------------------------
4398 -- Substitute_Valid_Check --
4399 ----------------------------
4402 begin
4411 Error_Msg_N -- CODEFIX
4416 -- Start of processing for Expand_N_In
4418 begin
4419 -- If set membership case, expand with separate procedure
4423 Expand_Set_Membership;
4427 -- Not set membership, proceed with expansion
4432 -- Check case of explicit test for an expression in range of its
4433 -- subtype. This is suspicious usage and we replace it with a 'Valid
4434 -- test and give a warning. For floating point types however, this is a
4435 -- standard way to check for finite numbers, and using 'Valid would
4436 -- typically be a pessimization. Also skip this test for predicated
4437 -- types, since it is perfectly reasonable to check if a value meets
4438 -- its predicate.
4448 then
4449 Substitute_Valid_Check;
4453 -- Do validity check on operands
4460 -- Case of explicit range
4463 declare
4474 Constant_Condition_Warnings
4477 -- This must be true for any of the optimization warnings, we
4478 -- clearly want to give them only for source with the flag on. We
4479 -- also skip these warnings in an instance since it may be the
4480 -- case that different instantiations have different ranges.
4483 Warn1
4486 -- For the case where only one bound warning is elided, we also
4487 -- insist on an explicit range and an integer type. The reason is
4488 -- that the use of enumeration ranges including an end point is
4489 -- common, as is the use of a subtype name, one of whose bounds is
4490 -- the same as the type of the expression.
4492 begin
4493 -- If test is explicit x'First .. x'Last, replace by valid check
4495 -- Could use some individual comments for this complex test ???
4508 then
4509 Substitute_Valid_Check;
4513 -- If bounds of type are known at compile time, and the end points
4514 -- are known at compile time and identical, this is another case
4515 -- for substituting a valid test. We only do this for discrete
4516 -- types, since it won't arise in practice for float types.
4527 -- Kill warnings in instances, since they may be cases where we
4528 -- have a test in the generic that makes sense with some types
4529 -- and not with other types.
4531 and then not In_Instance
4532 then
4533 Substitute_Valid_Check;
4537 -- If we have an explicit range, do a bit of optimization based on
4538 -- range analysis (we may be able to kill one or both checks).
4543 -- If either check is known to fail, replace result by False since
4544 -- the other check does not matter. Preserve the static flag for
4545 -- legality checks, because we are constant-folding beyond RM 4.9.
4558 -- If both checks are known to succeed, replace result by True,
4559 -- since we know we are in range.
4572 -- If lower bound check succeeds and upper bound check is not
4573 -- known to succeed or fail, then replace the range check with
4574 -- a comparison against the upper bound.
4589 -- If upper bound check succeeds and lower bound check is not
4590 -- known to succeed or fail, then replace the range check with
4591 -- a comparison against the lower bound.
4607 -- We couldn't optimize away the range check, but there is one
4608 -- more issue. If we are checking constant conditionals, then we
4609 -- see if we can determine the outcome assuming everything is
4610 -- valid, and if so give an appropriate warning.
4616 -- Result is out of range for valid value
4619 Error_Msg_N
4622 -- Result is in range for valid value
4625 Error_Msg_N
4628 -- Lower bound check succeeds if value is valid
4631 Error_Msg_N
4634 -- Upper bound check succeeds if value is valid
4637 Error_Msg_N
4643 -- For all other cases of an explicit range, nothing to be done
4647 -- Here right operand is a subtype mark
4649 else
4650 declare
4658 begin
4661 -- For tagged type, do tagged membership operation
4665 -- No expansion will be performed when VM_Target, as the VM
4666 -- back-ends will handle the membership tests directly (tags
4667 -- are not explicitly represented in Java objects, so the
4668 -- normal tagged membership expansion is not what we want).
4675 -- Update decoration of relocated node referenced by the
4676 -- SCIL node.
4685 -- If type is scalar type, rewrite as x in t'First .. t'Last.
4686 -- This reason we do this is that the bounds may have the wrong
4687 -- type if they come from the original type definition. Also this
4688 -- way we get all the processing above for an explicit range.
4690 -- Don't do this for predicated types, since in this case we
4691 -- want to check the predicate!
4697 Low_Bound =>
4702 High_Bound =>
4711 -- Ada 2005 (AI-216): Program_Error is raised when evaluating
4712 -- a membership test if the subtype mark denotes a constrained
4713 -- Unchecked_Union subtype and the expression lacks inferable
4714 -- discriminants.
4719 then
4724 -- Prevent Gigi from generating incorrect code by rewriting the
4725 -- test as False.
4731 -- Here we have a non-scalar type
4741 -- For the constrained array case, we have to check the subscripts
4742 -- for an exact match if the lengths are non-zero (the lengths
4743 -- must match in any case).
4747 function Build_Attribute_Reference
4751 -- Build attribute reference E'Nam (Dim)
4753 -------------------------------
4754 -- Build_Attribute_Reference --
4755 -------------------------------
4757 function Build_Attribute_Reference
4761 is
4762 begin
4763 return
4771 -- Start of processing for Check_Subscripts
4773 begin
4777 Left_Opnd =>
4778 Build_Attribute_Reference
4781 Right_Opnd =>
4782 Build_Attribute_Reference
4787 Left_Opnd =>
4788 Build_Attribute_Reference
4791 Right_Opnd =>
4792 Build_Attribute_Reference
4797 Cond :=
4799 Left_Opnd =>
4810 -- These are the cases where constraint checks may be required,
4811 -- e.g. records with possible discriminants
4813 else
4814 -- Expand the test into a series of discriminant comparisons.
4815 -- The expression that is built is the negation of the one that
4816 -- is used for checking discriminant constraints.
4826 Left_Opnd =>
4833 else
4843 -- At this point, we have done the processing required for the basic
4844 -- membership test, but not yet dealt with the predicate.
4848 -- If a predicate is present, then we do the predicate test, but we
4849 -- most certainly want to omit this if we are within the predicate
4850 -- function itself, since otherwise we have an infinite recursion!
4852 declare
4855 begin
4858 then
4864 -- Analyze new expression, mark left operand as analyzed to
4865 -- avoid infinite recursion adding predicate calls.
4870 -- All done, skip attempt at compile time determination of result
4877 --------------------------------
4878 -- Expand_N_Indexed_Component --
4879 --------------------------------
4887 begin
4888 -- A special optimization, if we have an indexed component that is
4889 -- selecting from a slice, then we can eliminate the slice, since, for
4890 -- example, x (i .. j)(k) is identical to x(k). The only difference is
4891 -- the range check required by the slice. The range check for the slice
4892 -- itself has already been generated. The range check for the
4893 -- subscripting operation is ensured by converting the subject to
4894 -- the subtype of the slice.
4896 -- This optimization not only generates better code, avoiding slice
4897 -- messing especially in the packed case, but more importantly bypasses
4898 -- some problems in handling this peculiar case, for example, the issue
4899 -- of dealing specially with object renamings.
4906 Convert_To
4913 -- Ada 2005 (AI-318-02): If the prefix is a call to a build-in-place
4914 -- function, then additional actuals must be passed.
4918 then
4922 -- If the prefix is an access type, then we unconditionally rewrite if
4923 -- as an explicit dereference. This simplifies processing for several
4924 -- cases, including packed array cases and certain cases in which checks
4925 -- must be generated. We used to try to do this only when it was
4926 -- necessary, but it cleans up the code to do it all the time.
4933 -- Generate index and validity checks
4941 -- All done for the non-packed case
4947 -- For packed arrays that are not bit-packed (i.e. the case of an array
4948 -- with one or more index types with a non-contiguous enumeration type),
4949 -- we can always use the normal packed element get circuit.
4956 -- For a reference to a component of a bit packed array, we have to
4957 -- convert it to a reference to the corresponding Packed_Array_Type.
4958 -- We only want to do this for simple references, and not for:
4960 -- Left side of assignment, or prefix of left side of assignment, or
4961 -- prefix of the prefix, to handle packed arrays of packed arrays,
4962 -- This case is handled in Exp_Ch5.Expand_N_Assignment_Statement
4964 -- Renaming objects in renaming associations
4965 -- This case is handled when a use of the renamed variable occurs
4967 -- Actual parameters for a procedure call
4968 -- This case is handled in Exp_Ch6.Expand_Actuals
4970 -- The second expression in a 'Read attribute reference
4972 -- The prefix of an address or bit or size attribute reference
4974 -- The following circuit detects these exceptions
4976 declare
4980 begin
4981 loop
4986 N_Procedure_Call_Statement)
4988 and then
4990 then
4995 or else
4997 or else
5000 then
5005 then
5008 -- If the expression is an index of an indexed component, it must
5009 -- be expanded regardless of context.
5013 then
5019 then
5025 then
5030 then
5033 else
5038 -- Keep looking up tree for unchecked expression, or if we are the
5039 -- prefix of a possible assignment left side.
5047 ---------------------
5048 -- Expand_N_Not_In --
5049 ---------------------
5051 -- Replace a not in b by not (a in b) so that the expansions for (a in b)
5052 -- can be done. This avoids needing to duplicate this expansion code.
5059 begin
5062 Right_Opnd =>
5067 -- If this is a set membership, preserve list of alternatives
5071 -- We want this to appear as coming from source if original does (see
5072 -- transformations in Expand_N_In).
5077 -- Now analyze transformed node
5082 -------------------
5083 -- Expand_N_Null --
5084 -------------------
5086 -- The only replacement required is for the case of a null of a type that
5087 -- is an access to protected subprogram, or a subtype thereof. We represent
5088 -- such access values as a record, and so we must replace the occurrence of
5089 -- null by the equivalent record (with a null address and a null pointer in
5090 -- it), so that the backend creates the proper value.
5097 begin
5099 Agg :=
5108 -- For subsequent semantic analysis, the node must retain its type.
5109 -- Gigi in any case replaces this type by the corresponding record
5110 -- type before processing the node.
5115 exception
5120 ---------------------
5121 -- Expand_N_Op_Abs --
5122 ---------------------
5128 begin
5131 -- Deal with software overflow checking
5133 if not Backend_Overflow_Checks_On_Target
5136 then
5137 -- The only case to worry about is when the argument is equal to the
5138 -- largest negative number, so what we do is to insert the check:
5140 -- [constraint_error when Expr = typ'Base'First]
5142 -- with the usual Duplicate_Subexpr use coding for expr
5146 Condition =>
5149 Right_Opnd =>
5151 Prefix =>
5157 -- Vax floating-point types case
5164 ---------------------
5165 -- Expand_N_Op_Add --
5166 ---------------------
5171 begin
5174 -- N + 0 = 0 + N = N for integer types
5179 then
5185 then
5191 -- Arithmetic overflow checks for signed integer/fixed point types
5195 then
5199 -- Vax floating-point types case
5206 ---------------------
5207 -- Expand_N_Op_And --
5208 ---------------------
5213 begin
5221 -- Replace AND by AND THEN if Short_Circuit_And_Or active and the
5222 -- type is standard Boolean (do not mess with AND that uses a non-
5223 -- standard Boolean type, because something strange is going on).
5232 -- Otherwise, adjust conditions
5234 else
5247 ------------------------
5248 -- Expand_N_Op_Concat --
5249 ------------------------
5253 -- List of operands to be concatenated
5256 -- Node which is to be replaced by the result of concatenating the nodes
5257 -- in the list Opnds.
5259 begin
5260 -- Ensure validity of both operands
5264 -- If we are the left operand of a concatenation higher up the tree,
5265 -- then do nothing for now, since we want to deal with a series of
5266 -- concatenations as a unit.
5270 then
5274 -- We get here with a concatenation whose left operand may be a
5275 -- concatenation itself with a consistent type. We need to process
5276 -- these concatenation operands from left to right, which means
5277 -- from the deepest node in the tree to the highest node.
5284 -- Now Cnode is the deepest concatenation, and its parents are the
5285 -- concatenation nodes above, so now we process bottom up, doing the
5286 -- operations. We gather a string that is as long as possible up to five
5287 -- operands.
5289 -- The outer loop runs more than once if more than one concatenation
5290 -- type is involved.
5296 -- The inner loop gathers concatenation operands
5301 loop
5313 ------------------------
5314 -- Expand_N_Op_Divide --
5315 ------------------------
5325 and then
5329 begin
5336 -- N / 1 = N for integer types
5343 -- Convert x / 2 ** y to Shift_Right (x, y). Note that the fact that
5344 -- Is_Power_Of_2_For_Shift is set means that we know that our left
5345 -- operand is an unsigned integer, as required for this to work.
5350 -- We cannot do this transformation in configurable run time mode if we
5351 -- have 64-bit integers and long shifts are not available.
5353 and then
5356 then
5360 Right_Opnd =>
5366 -- Do required fixup of universal fixed operation
5373 -- Divisions with fixed-point results
5377 -- No special processing if Treat_Fixed_As_Integer is set, since
5378 -- from a semantic point of view such operations are simply integer
5379 -- operations and will be treated that way.
5384 else
5389 -- Other cases of division of fixed-point operands. Again we exclude the
5390 -- case where Treat_Fixed_As_Integer is set.
5395 then
5398 else
5403 -- Mixed-mode operations can appear in a non-static universal context,
5404 -- in which case the integer argument must be converted explicitly.
5408 then
5416 then
5422 -- Non-fixed point cases, do integer zero divide and overflow checks
5427 -- Check for 64-bit division available, or long shifts if the divisor
5428 -- is a small power of 2 (since such divides will be converted into
5429 -- long shifts).
5432 and then not Support_64_Bit_Divides_On_Target
5433 and then
5435 or else not Support_Long_Shifts_On_Target
5442 then
5446 -- Deal with Vax_Float
5454 --------------------
5455 -- Expand_N_Op_Eq --
5456 --------------------
5471 -- If a constructed equality exists for the type or for its parent,
5472 -- build and analyze call, adding conversions if the operation is
5473 -- inherited.
5476 -- Determines whether a type has a subcomponent of an unconstrained
5477 -- Unchecked_Union subtype. Typ is a record type.
5479 -------------------------
5480 -- Build_Equality_Call --
5481 -------------------------
5488 begin
5491 then
5496 -- If we have an Unchecked_Union, we need to add the inferred
5497 -- discriminant values as actuals in the function call. At this
5498 -- point, the expansion has determined that both operands have
5499 -- inferable discriminants.
5502 declare
5508 begin
5509 -- Per-object constrained selected components require special
5510 -- attention. If the enclosing scope of the component is an
5511 -- Unchecked_Union, we cannot reference its discriminants
5512 -- directly. This is why we use the two extra parameters of
5513 -- the equality function of the enclosing Unchecked_Union.
5515 -- type UU_Type (Discr : Integer := 0) is
5516 -- . . .
5517 -- end record;
5518 -- pragma Unchecked_Union (UU_Type);
5520 -- 1. Unchecked_Union enclosing record:
5522 -- type Enclosing_UU_Type (Discr : Integer := 0) is record
5523 -- . . .
5524 -- Comp : UU_Type (Discr);
5525 -- . . .
5526 -- end Enclosing_UU_Type;
5527 -- pragma Unchecked_Union (Enclosing_UU_Type);
5529 -- Obj1 : Enclosing_UU_Type;
5530 -- Obj2 : Enclosing_UU_Type (1);
5532 -- [. . .] Obj1 = Obj2 [. . .]
5534 -- Generated code:
5536 -- if not (uu_typeEQ (obj1.comp, obj2.comp, a, b)) then
5538 -- A and B are the formal parameters of the equality function
5539 -- of Enclosing_UU_Type. The function always has two extra
5540 -- formals to capture the inferred discriminant values.
5542 -- 2. Non-Unchecked_Union enclosing record:
5544 -- type
5545 -- Enclosing_Non_UU_Type (Discr : Integer := 0)
5546 -- is record
5547 -- . . .
5548 -- Comp : UU_Type (Discr);
5549 -- . . .
5550 -- end Enclosing_Non_UU_Type;
5552 -- Obj1 : Enclosing_Non_UU_Type;
5553 -- Obj2 : Enclosing_Non_UU_Type (1);
5555 -- ... Obj1 = Obj2 ...
5557 -- Generated code:
5559 -- if not (uu_typeEQ (obj1.comp, obj2.comp,
5560 -- obj1.discr, obj2.discr)) then
5562 -- In this case we can directly reference the discriminants of
5563 -- the enclosing record.
5565 -- Lhs of equality
5568 and then Has_Per_Object_Constraint
5570 then
5571 -- Enclosing record is an Unchecked_Union, use formal A
5573 if Is_Unchecked_Union
5575 then
5578 -- Enclosing record is of a non-Unchecked_Union type, it is
5579 -- possible to reference the discriminant.
5581 else
5582 Lhs_Discr_Val :=
5585 Selector_Name =>
5586 New_Copy
5587 (Get_Discriminant_Value
5589 Lhs_Type,
5593 -- Comment needed here ???
5595 else
5596 -- Infer the discriminant value
5598 Lhs_Discr_Val :=
5599 New_Copy
5600 (Get_Discriminant_Value
5602 Lhs_Type,
5606 -- Rhs of equality
5609 and then Has_Per_Object_Constraint
5611 then
5612 if Is_Unchecked_Union
5614 then
5617 else
5618 Rhs_Discr_Val :=
5621 Selector_Name =>
5624 Rhs_Type,
5628 else
5629 Rhs_Discr_Val :=
5632 Rhs_Type,
5641 L_Exp,
5642 R_Exp,
5643 Lhs_Discr_Val,
5644 Rhs_Discr_Val)));
5647 -- Normal case, not an unchecked union
5649 else
5659 ------------------------------------
5660 -- Has_Unconstrained_UU_Component --
5661 ------------------------------------
5663 function Has_Unconstrained_UU_Component
5665 is
5671 function Component_Is_Unconstrained_UU
5673 -- Determines whether the subtype of the component is an
5674 -- unconstrained Unchecked_Union.
5676 function Variant_Is_Unconstrained_UU
5678 -- Determines whether a component of the variant has an unconstrained
5679 -- Unchecked_Union subtype.
5681 -----------------------------------
5682 -- Component_Is_Unconstrained_UU --
5683 -----------------------------------
5685 function Component_Is_Unconstrained_UU
5687 is
5688 begin
5693 declare
5697 begin
5698 -- Unconstrained nominal type. In the case of a constraint
5699 -- present, the node kind would have been N_Subtype_Indication.
5709 ---------------------------------
5710 -- Variant_Is_Unconstrained_UU --
5711 ---------------------------------
5713 function Variant_Is_Unconstrained_UU
5715 is
5718 begin
5723 -- We only need to test one component
5725 declare
5728 begin
5738 -- None of the components withing the variant were of
5739 -- unconstrained Unchecked_Union type.
5744 -- Start of processing for Has_Unconstrained_UU_Component
5746 begin
5754 -- Inspect available components
5757 declare
5760 begin
5763 -- One component is sufficient
5774 -- Inspect available components withing variants
5777 declare
5780 begin
5783 -- One component within a variant is sufficient
5794 -- Neither the available components, nor the components inside the
5795 -- variant parts were of an unconstrained Unchecked_Union subtype.
5800 -- Start of processing for Expand_N_Op_Eq
5802 begin
5809 else
5813 -- It may happen in error situations that the underlying type is not
5814 -- set. The error will be detected later, here we just defend the
5815 -- expander code.
5823 -- Boolean types (requiring handling of non-standard case)
5831 -- Array types
5835 -- If we are doing full validity checking, and it is possible for the
5836 -- array elements to be invalid then expand out array comparisons to
5837 -- make sure that we check the array elements.
5839 if Validity_Check_Operands
5841 then
5842 declare
5844 Force_Validity_Checks;
5845 begin
5848 Expand_Array_Equality
5852 Bodies,
5853 Typl));
5859 -- Packed case where both operands are known aligned
5864 then
5867 -- Where the component type is elementary we can use a block bit
5868 -- comparison (if supported on the target) exception in the case
5869 -- of floating-point (negative zero issues require element by
5870 -- element comparison), and atomic types (where we must be sure
5871 -- to load elements independently) and possibly unaligned arrays.
5878 and then Support_Composite_Compare_On_Target
5879 then
5882 -- For composite and floating-point cases, expand equality loop to
5883 -- make sure of using proper comparisons for tagged types, and
5884 -- correctly handling the floating-point case.
5886 else
5888 Expand_Array_Equality
5892 Bodies,
5893 Typl));
5898 -- Record Types
5902 -- For tagged types, use the primitive "="
5906 -- No need to do anything else compiling under restriction
5907 -- No_Dispatching_Calls. During the semantic analysis we
5908 -- already notified such violation.
5914 -- If this is derived from an untagged private type completed with
5915 -- a tagged type, it does not have a full view, so we use the
5916 -- primitive operations of the private type. This check should no
5917 -- longer be necessary when these types get their full views???
5923 then
5924 -- Search for equality operation, checking that the operands
5925 -- have the same type. Note that we must find a matching entry,
5926 -- or something is very wrong!
5934 and then
5943 -- Find the type's predefined equality or an overriding
5944 -- user- defined equality. The reason for not simply calling
5945 -- Find_Prim_Op here is that there may be a user-defined
5946 -- overloaded equality op that precedes the equality that we want,
5947 -- so we have to explicitly search (e.g., there could be an
5948 -- equality with two different parameter types).
5950 else
5960 and then
5972 -- Ada 2005 (AI-216): Program_Error is raised when evaluating the
5973 -- predefined equality operator for a type which has a subcomponent
5974 -- of an Unchecked_Union type whose nominal subtype is unconstrained.
5981 -- Prevent Gigi from generating incorrect code by rewriting the
5982 -- equality as a standard False.
5989 -- If we can infer the discriminants of the operands, we make a
5990 -- call to the TSS equality function.
5993 and then
5995 then
5996 Build_Equality_Call
5999 else
6000 -- Ada 2005 (AI-216): Program_Error is raised when evaluating
6001 -- the predefined equality operator for an Unchecked_Union type
6002 -- if either of the operands lack inferable discriminants.
6008 -- Prevent Gigi from generating incorrect code by rewriting
6009 -- the equality as a standard False.
6016 -- If a type support function is present (for complex cases), use it
6019 Build_Equality_Call
6022 -- Otherwise expand the component by component equality. Note that
6023 -- we never use block-bit comparisons for records, because of the
6024 -- problems with gaps. The backend will often be able to recombine
6025 -- the separate comparisons that we generate here.
6027 else
6038 -- Test if result is known at compile time
6042 -- If we still have comparison for Vax_Float, process it
6050 -----------------------
6051 -- Expand_N_Op_Expon --
6052 -----------------------
6070 begin
6073 -- If either operand is of a private type, then we have the use of an
6074 -- intrinsic operator, and we get rid of the privateness, by using root
6075 -- types of underlying types for the actual operation. Otherwise the
6076 -- private types will cause trouble if we expand multiplications or
6077 -- shifts etc. We also do this transformation if the result type is
6078 -- different from the base type.
6081 or else
6083 or else
6085 or else
6087 then
6088 declare
6092 begin
6103 -- Test for case of known right argument
6108 -- We only fold small non-negative exponents. You might think we
6109 -- could fold small negative exponents for the real case, but we
6110 -- can't because we are required to raise Constraint_Error for
6111 -- the case of 0.0 ** (negative) even if Machine_Overflows = False.
6112 -- See ACVC test C4A012B.
6116 -- X ** 0 = 1 (or 1.0)
6120 -- Call Remove_Side_Effects to ensure that any side effects
6121 -- in the ignored left operand (in particular function calls
6122 -- to user defined functions) are properly executed.
6128 else
6132 -- X ** 1 = X
6137 -- X ** 2 = X * X
6140 Xnode :=
6145 -- X ** 3 = X * X * X
6148 Xnode :=
6150 Left_Opnd =>
6156 -- X ** 4 ->
6157 -- En : constant base'type := base * base;
6158 -- ...
6159 -- En * En
6169 Expression =>
6174 Xnode :=
6186 -- Case of (2 ** expression) appearing as an argument of an integer
6187 -- multiplication, or as the right argument of a division of a non-
6188 -- negative integer. In such cases we leave the node untouched, setting
6189 -- the flag Is_Natural_Power_Of_2_for_Shift set, then the expansion
6190 -- of the higher level node converts it into a shift.
6192 -- Another case is 2 ** N in any other context. We simply convert
6193 -- this to 1 * 2 ** N, and then the above transformation applies.
6195 -- Note: this transformation is not applicable for a modular type with
6196 -- a non-binary modulus in the multiplication case, since we get a wrong
6197 -- result if the shift causes an overflow before the modular reduction.
6204 and then not Ovflo
6205 then
6206 -- First the multiply and divide cases
6209 declare
6214 begin
6217 and then
6219 or else
6222 or else
6228 then
6234 -- Now the other cases
6246 -- Fall through if exponentiation must be done using a runtime routine
6248 -- First deal with modular case
6252 -- Non-binary case, we call the special exponentiation routine for
6253 -- the non-binary case, converting the argument to Long_Long_Integer
6254 -- and passing the modulus value. Then the result is converted back
6255 -- to the base type.
6265 Exp))));
6267 -- Binary case, in this case, we call one of two routines, either the
6268 -- unsigned integer case, or the unsigned long long integer case,
6269 -- with a final "and" operation to do the required mod.
6271 else
6274 else
6281 Left_Opnd =>
6286 Exp)),
6287 Right_Opnd =>
6292 -- Common exit point for modular type case
6297 -- Signed integer cases, done using either Integer or Long_Long_Integer.
6298 -- It is not worth having routines for Short_[Short_]Integer, since for
6299 -- most machines it would not help, and it would generate more code that
6300 -- might need certification when a certified run time is required.
6302 -- In the integer cases, we have two routines, one for when overflow
6303 -- checks are required, and one when they are not required, since there
6304 -- is a real gain in omitting checks on many machines.
6308 and then
6311 then
6316 else
6325 else
6329 -- Floating-point cases, always done using Long_Long_Float. We do not
6330 -- need separate routines for the overflow case here, since in the case
6331 -- of floating-point, we generate infinities anyway as a rule (either
6332 -- that or we automatically trap overflow), and if there is an infinity
6333 -- generated and a range check is required, the check will fail anyway.
6335 else
6341 -- Common processing for integer cases and floating-point cases.
6342 -- If we are in the right type, we can call runtime routine directly
6347 then
6353 -- Otherwise we have to introduce conversions (conversions are also
6354 -- required in the universal cases, since the runtime routine is
6355 -- typed using one of the standard types).
6357 else
6364 Exp))));
6370 exception
6375 --------------------
6376 -- Expand_N_Op_Ge --
6377 --------------------
6385 begin
6402 -- If we still have comparison, and Vax_Float type, process it
6410 --------------------
6411 -- Expand_N_Op_Gt --
6412 --------------------
6420 begin
6437 -- If we still have comparison, and Vax_Float type, process it
6445 --------------------
6446 -- Expand_N_Op_Le --
6447 --------------------
6455 begin
6472 -- If we still have comparison, and Vax_Float type, process it
6480 --------------------
6481 -- Expand_N_Op_Lt --
6482 --------------------
6490 begin
6507 -- If we still have comparison, and Vax_Float type, process it
6515 -----------------------
6516 -- Expand_N_Op_Minus --
6517 -----------------------
6523 begin
6526 if not Backend_Overflow_Checks_On_Target
6529 then
6530 -- Software overflow checking expands -expr into (0 - expr)
6539 -- Vax floating-point types case
6546 ---------------------
6547 -- Expand_N_Op_Mod --
6548 ---------------------
6568 begin
6574 -- Convert mod to rem if operands are known non-negative. We do this
6575 -- since it is quite likely that this will improve the quality of code,
6576 -- (the operation now corresponds to the hardware remainder), and it
6577 -- does not seem likely that it could be harmful.
6580 and then
6582 then
6588 -- Instead of reanalyzing the node we do the analysis manually. This
6589 -- avoids anomalies when the replacement is done in an instance and
6590 -- is epsilon more efficient.
6599 -- Otherwise, normal mod processing
6601 else
6606 -- Apply optimization x mod 1 = 0. We don't really need that with
6607 -- gcc, but it is useful with other back ends (e.g. AAMP), and is
6608 -- certainly harmless.
6613 then
6614 -- Call Remove_Side_Effects to ensure that any side effects in
6615 -- the ignored left operand (in particular function calls to
6616 -- user defined functions) are properly executed.
6625 -- Deal with annoying case of largest negative number remainder
6626 -- minus one. Gigi does not handle this case correctly, because
6627 -- it generates a divide instruction which may trap in this case.
6629 -- In fact the check is quite easy, if the right operand is -1, then
6630 -- the mod value is always 0, and we can just ignore the left operand
6631 -- completely in this case.
6633 -- The operand type may be private (e.g. in the expansion of an
6634 -- intrinsic operation) so we must use the underlying type to get the
6635 -- bounds, and convert the literals explicitly.
6637 LLB :=
6638 Expr_Value
6642 and then
6644 then
6650 Right_Opnd =>
6663 --------------------------
6664 -- Expand_N_Op_Multiply --
6665 --------------------------
6684 begin
6687 -- Special optimizations for integer types
6691 -- N * 0 = 0 for integer types
6695 then
6696 -- Call Remove_Side_Effects to ensure that any side effects in
6697 -- the ignored left operand (in particular function calls to
6698 -- user defined functions) are properly executed.
6707 -- Similar handling for 0 * N = 0
6711 then
6718 -- N * 1 = 1 * N = N for integer types
6720 -- This optimisation is not done if we are going to
6721 -- rewrite the product 1 * 2 ** N to a shift.
6725 and then not Lp2
6726 then
6732 and then not Rp2
6733 then
6739 -- Convert x * 2 ** y to Shift_Left (x, y). Note that the fact that
6740 -- Is_Power_Of_2_For_Shift is set means that we know that our left
6741 -- operand is an integer, as required for this to work.
6746 -- Convert 2 ** A * 2 ** B into 2 ** (A + B)
6751 Right_Opnd =>
6758 else
6762 Right_Opnd =>
6768 -- Same processing for the operands the other way round
6774 Right_Opnd =>
6780 -- Do required fixup of universal fixed operation
6787 -- Multiplications with fixed-point results
6791 -- No special processing if Treat_Fixed_As_Integer is set, since from
6792 -- a semantic point of view such operations are simply integer
6793 -- operations and will be treated that way.
6797 -- Case of fixed * integer => fixed
6802 -- Case of integer * fixed => fixed
6807 -- Case of fixed * fixed => fixed
6809 else
6814 -- Other cases of multiplication of fixed-point operands. Again we
6815 -- exclude the cases where Treat_Fixed_As_Integer flag is set.
6819 then
6822 else
6827 -- Mixed-mode operations can appear in a non-static universal context,
6828 -- in which case the integer argument must be converted explicitly.
6832 then
6839 then
6844 -- Non-fixed point cases, check software overflow checking required
6849 -- Deal with VAX float case
6857 --------------------
6858 -- Expand_N_Op_Ne --
6859 --------------------
6864 begin
6865 -- Case of elementary type with standard operator
6869 then
6872 -- Boolean types (requiring handling of non-standard case)
6883 -- If we still have comparison for Vax_Float, process it
6890 -- For all cases other than elementary types, we rewrite node as the
6891 -- negation of an equality operation, and reanalyze. The equality to be
6892 -- used is defined in the same scope and has the same signature. This
6893 -- signature must be set explicitly since in an instance it may not have
6894 -- the same visibility as in the generic unit. This avoids duplicating
6895 -- or factoring the complex code for record/array equality tests etc.
6897 else
6898 declare
6903 begin
6906 Neg :=
6908 Right_Opnd =>
6918 -- For navigation purposes, the inequality is treated as an
6919 -- implicit reference to the corresponding equality. Preserve the
6920 -- Comes_From_ source flag so that the proper Xref entry is
6921 -- generated.
6931 ---------------------
6932 -- Expand_N_Op_Not --
6933 ---------------------
6935 -- If the argument is other than a Boolean array type, there is no special
6936 -- expansion required, except for VMS operations on signed integers.
6938 -- For the packed case, we call the special routine in Exp_Pakd, except
6939 -- that if the component size is greater than one, we use the standard
6940 -- routine generating a gruesome loop (it is so peculiar to have packed
6941 -- arrays with non-standard Boolean representations anyway, so it does not
6942 -- matter that we do not handle this case efficiently).
6944 -- For the unpacked case (and for the special packed case where we have non
6945 -- standard Booleans, as discussed above), we generate and insert into the
6946 -- tree the following function definition:
6948 -- function Nnnn (A : arr) is
6949 -- B : arr;
6950 -- begin
6951 -- for J in a'range loop
6952 -- B (J) := not A (J);
6953 -- end loop;
6954 -- return B;
6955 -- end Nnnn;
6957 -- Here arr is the actual subtype of the parameter (and hence always
6958 -- constrained). Then we replace the not with a call to this function.
6974 begin
6977 -- For boolean operand, deal with non-standard booleans
6986 -- For the VMS "not" on signed integer types, use conversion to and from
6987 -- a predefined modular type.
6990 declare
6994 begin
6995 -- If this is a derived type, retrieve original VMS type so that
6996 -- the proper sized type is used for intermediate values.
7000 else
7004 -- The proper unsigned type must have a size compatible with the
7005 -- operand, to prevent misalignment.
7016 else
7029 -- Only array types need any other processing
7035 -- Case of array operand. If bit packed with a component size of 1,
7036 -- handle it in Exp_Pakd if the operand is known to be aligned.
7041 then
7046 -- Case of array operand which is not bit-packed. If the context is
7047 -- a safe assignment, call in-place operation, If context is a larger
7048 -- boolean expression in the context of a safe assignment, expansion is
7049 -- done by enclosing operation.
7062 -- Special case the negation of a binary operation
7065 and then Safe_In_Place_Array_Op
7067 then
7074 then
7075 declare
7080 begin
7083 -- (not A) op (not B) can be reduced to a single call
7091 -- A xor (not B) can also be special-cased
7104 A_J :=
7109 B_J :=
7114 Loop_Statement :=
7118 Iteration_Scheme =>
7120 Loop_Parameter_Specification =>
7123 Discrete_Subtype_Definition =>
7138 Specification =>
7152 Handled_Statement_Sequence =>
7155 Loop_Statement,
7167 --------------------
7168 -- Expand_N_Op_Or --
7169 --------------------
7174 begin
7182 -- Replace OR by OR ELSE if Short_Circuit_And_Or active and the type
7183 -- is standard Boolean (do not mess with AND that uses a non-standard
7184 -- Boolean type, because something strange is going on).
7193 -- Otherwise, adjust conditions
7195 else
7208 ----------------------
7209 -- Expand_N_Op_Plus --
7210 ----------------------
7213 begin
7217 ---------------------
7218 -- Expand_N_Op_Rem --
7219 ---------------------
7234 -- Set if corresponding operand can be negative
7238 begin
7245 -- Apply optimization x rem 1 = 0. We don't really need that with gcc,
7246 -- but it is useful with other back ends (e.g. AAMP), and is certainly
7247 -- harmless.
7252 then
7253 -- Call Remove_Side_Effects to ensure that any side effects in the
7254 -- ignored left operand (in particular function calls to user defined
7255 -- functions) are properly executed.
7264 -- Deal with annoying case of largest negative number remainder minus
7265 -- one. Gigi does not handle this case correctly, because it generates
7266 -- a divide instruction which may trap in this case.
7268 -- In fact the check is quite easy, if the right operand is -1, then
7269 -- the remainder is always 0, and we can just ignore the left operand
7270 -- completely in this case.
7278 -- We won't mess with trying to find out if the left operand can really
7279 -- be the largest negative number (that's a pain in the case of private
7280 -- types and this is really marginal). We will just assume that we need
7281 -- the test if the left operand can be negative at all.
7289 Right_Opnd =>
7302 -----------------------------
7303 -- Expand_N_Op_Rotate_Left --
7304 -----------------------------
7307 begin
7311 ------------------------------
7312 -- Expand_N_Op_Rotate_Right --
7313 ------------------------------
7316 begin
7320 ----------------------------
7321 -- Expand_N_Op_Shift_Left --
7322 ----------------------------
7325 begin
7329 -----------------------------
7330 -- Expand_N_Op_Shift_Right --
7331 -----------------------------
7334 begin
7338 ----------------------------------------
7339 -- Expand_N_Op_Shift_Right_Arithmetic --
7340 ----------------------------------------
7343 begin
7347 --------------------------
7348 -- Expand_N_Op_Subtract --
7349 --------------------------
7354 begin
7357 -- N - 0 = N for integer types
7362 then
7367 -- Arithmetic overflow checks for signed integer/fixed point types
7370 or else
7372 then
7375 -- VAX floating-point types case
7382 ---------------------
7383 -- Expand_N_Op_Xor --
7384 ---------------------
7389 begin
7407 ----------------------
7408 -- Expand_N_Or_Else --
7409 ----------------------
7414 -----------------------------------
7415 -- Expand_N_Qualified_Expression --
7416 -----------------------------------
7422 begin
7423 -- Do validity check if validity checking operands
7425 if Validity_Checks_On
7426 and then Validity_Check_Operands
7427 then
7431 -- Apply possible constraint check
7441 ------------------------------------
7442 -- Expand_N_Quantified_Expression --
7443 ------------------------------------
7445 -- We expand:
7447 -- for all X in range => Cond
7449 -- into:
7451 -- T := True;
7452 -- for X in range loop
7453 -- if not Cond then
7454 -- T := False;
7455 -- exit;
7456 -- end if;
7457 -- end loop;
7459 -- Conversely, an existentially quantified expression:
7461 -- for some X in range => Cond
7463 -- becomes:
7465 -- T := False;
7466 -- for X in range loop
7467 -- if Cond then
7468 -- T := True;
7469 -- exit;
7470 -- end if;
7471 -- end loop;
7473 -- In both cases, the iteration may be over a container in which case it is
7474 -- given by an iterator specification, not a loop parameter specification.
7486 begin
7487 Decl :=
7491 Expression =>
7501 Test :=
7507 Expression =>
7512 I_Scheme :=
7514 Loop_Parameter_Specification =>
7516 else
7517 I_Scheme :=
7528 -- The components of the scheme have already been analyzed, and the loop
7529 -- parameter declaration has been processed.
7541 ---------------------------------
7542 -- Expand_N_Selected_Component --
7543 ---------------------------------
7545 -- If the selector is a discriminant of a concurrent object, rewrite the
7546 -- prefix to denote the corresponding record type.
7559 -- Gigi needs a temporary for prefixes that depend on a discriminant,
7560 -- unless the context of an assignment can provide size information.
7561 -- Don't we have a general routine that does this???
7563 -----------------------
7564 -- In_Left_Hand_Side --
7565 -----------------------
7568 begin
7576 -- Start of processing for Expand_N_Selected_Component
7578 begin
7579 -- Insert explicit dereference if required
7587 then
7594 -- Deal with discriminant check required
7598 -- Present the discriminant checking function to the backend, so that
7599 -- it can inline the call to the function.
7601 Add_Inlined_Body
7602 (Discriminant_Checking_Func
7605 -- Now reset the flag and generate the call
7611 -- Ada 2005 (AI-318-02): If the prefix is a call to a build-in-place
7612 -- function, then additional actuals must be passed.
7616 then
7620 -- Gigi cannot handle unchecked conversions that are the prefix of a
7621 -- selected component with discriminants. This must be checked during
7622 -- expansion, because during analysis the type of the selector is not
7623 -- known at the point the prefix is analyzed. If the conversion is the
7624 -- target of an assignment, then we cannot force the evaluation.
7629 then
7633 -- Remaining processing applies only if selector is a discriminant
7637 -- If the selector is a discriminant of a constrained record type,
7638 -- we may be able to rewrite the expression with the actual value
7639 -- of the discriminant, a useful optimization in some cases.
7644 then
7645 -- Do this optimization for discrete types only, and not for
7646 -- access types (access discriminants get us into trouble!)
7651 -- Don't do this on the left hand of an assignment statement.
7652 -- Normally one would think that references like this would not
7653 -- occur, but they do in generated code, and mean that we really
7654 -- do want to assign the discriminant!
7658 then
7661 -- Don't do this optimization for the prefix of an attribute or
7662 -- the name of an object renaming declaration since these are
7663 -- contexts where we do not want the value anyway.
7668 then
7671 -- Don't do this optimization if we are within the code for a
7672 -- discriminant check, since the whole point of such a check may
7673 -- be to verify the condition on which the code below depends!
7678 -- Green light to see if we can do the optimization. There is
7679 -- still one condition that inhibits the optimization below but
7680 -- now is the time to check the particular discriminant.
7682 else
7683 -- Loop through discriminants to find the matching discriminant
7684 -- constraint to see if we can copy it.
7691 -- Check if this is the matching discriminant
7695 -- Here we have the matching discriminant. Check for
7696 -- the case of a discriminant of a component that is
7697 -- constrained by an outer discriminant, which cannot
7698 -- be optimized away.
7700 if Denotes_Discriminant
7702 then
7706 and then
7707 Denotes_Discriminant
7709 then
7712 -- Do not retrieve value if constraint is not static. It
7713 -- is generally not useful, and the constraint may be a
7714 -- rewritten outer discriminant in which case it is in
7715 -- fact incorrect.
7719 = N_Object_Declaration
7721 and then
7722 not Is_Static_Expression
7724 then
7727 -- In the context of a case statement, the expression may
7728 -- have the base type of the discriminant, and we need to
7729 -- preserve the constraint to avoid spurious errors on
7730 -- missing cases.
7734 then
7737 Subtype_Mark =>
7739 Expression =>
7743 -- In case that comes out as a static expression,
7744 -- reset it (a selected component is never static).
7749 -- Otherwise we can just copy the constraint, but the
7750 -- result is certainly not static! In some cases the
7751 -- discriminant constraint has been analyzed in the
7752 -- context of the original subtype indication, but for
7753 -- itypes the constraint might not have been analyzed
7754 -- yet, and this must be done now.
7756 else
7768 -- Note: the above loop should always find a matching
7769 -- discriminant, but if it does not, we just missed an
7770 -- optimization due to some glitch (perhaps a previous error),
7771 -- so ignore.
7776 -- The only remaining processing is in the case of a discriminant of
7777 -- a concurrent object, where we rewrite the prefix to denote the
7778 -- corresponding record type. If the type is derived and has renamed
7779 -- discriminants, use corresponding discriminant, which is the one
7780 -- that appears in the corresponding record.
7790 then
7794 New_N :=
7796 Prefix =>
7806 --------------------
7807 -- Expand_N_Slice --
7808 --------------------
7817 -- Check whether the argument is an actual for a procedure call, in
7818 -- which case the expansion of a bit-packed slice is deferred until the
7819 -- call itself is expanded. The reason this is required is that we might
7820 -- have an IN OUT or OUT parameter, and the copy out is essential, and
7821 -- that copy out would be missed if we created a temporary here in
7822 -- Expand_N_Slice. Note that we don't bother to test specifically for an
7823 -- IN OUT or OUT mode parameter, since it is a bit tricky to do, and it
7824 -- is harmless to defer expansion in the IN case, since the call
7825 -- processing will still generate the appropriate copy in operation,
7826 -- which will take care of the slice.
7829 -- Create a named variable for the value of the slice, in cases where
7830 -- the back-end cannot handle it properly, e.g. when packed types or
7831 -- unaligned slices are involved.
7833 -------------------------
7834 -- Is_Procedure_Actual --
7835 -------------------------
7840 begin
7841 loop
7842 -- If our parent is a procedure call we can return
7847 -- If our parent is a type conversion, keep climbing the tree,
7848 -- since a type conversion can be a procedure actual. Also keep
7849 -- climbing if parameter association or a qualified expression,
7850 -- since these are additional cases that do can appear on
7851 -- procedure actuals.
7854 N_Parameter_Association,
7855 N_Qualified_Expression)
7856 then
7859 -- Any other case is not what we are looking for
7861 else
7867 ------------------------------
7868 -- Make_Temporary_For_Slice --
7869 ------------------------------
7875 begin
7876 Decl :=
7884 Decl,
7893 -- Start of processing for Expand_N_Slice
7895 begin
7896 -- Special handling for access types
7909 -- Ada 2005 (AI-318-02): If the prefix is a call to a build-in-place
7910 -- function, then additional actuals must be passed.
7914 then
7918 -- The remaining case to be handled is packed slices. We can leave
7919 -- packed slices as they are in the following situations:
7921 -- 1. Right or left side of an assignment (we can handle this
7922 -- situation correctly in the assignment statement expansion).
7924 -- 2. Prefix of indexed component (the slide is optimized away in this
7925 -- case, see the start of Expand_N_Slice.)
7927 -- 3. Object renaming declaration, since we want the name of the
7928 -- slice, not the value.
7930 -- 4. Argument to procedure call, since copy-in/copy-out handling may
7931 -- be required, and this is handled in the expansion of call
7932 -- itself.
7934 -- 5. Prefix of an address attribute (this is an error which is caught
7935 -- elsewhere, and the expansion would interfere with generating the
7936 -- error message).
7940 -- Apply transformation for actuals of a function call, where
7941 -- Expand_Actuals is not used.
7945 then
7946 Make_Temporary_For_Slice;
7952 then
7958 then
7963 then
7966 else
7967 Make_Temporary_For_Slice;
7971 ------------------------------
7972 -- Expand_N_Type_Conversion --
7973 ------------------------------
7982 -- This is called in the case of record and array type conversions to
7983 -- see if there is a change of representation to be handled. Change of
7984 -- representation is actually handled at the assignment statement level,
7985 -- and what this procedure does is rewrite node N conversion as an
7986 -- assignment to temporary. If there is no change of representation,
7987 -- then the conversion node is unchanged.
7990 -- Called when we know that an accessibility check will fail. Rewrites
7991 -- node N to an appropriate raise statement and outputs warning msgs.
7992 -- The Etype of the raise node is set to Target_Type.
7995 -- Handles generation of range check for real target value
7997 -----------------------------------
7998 -- Handle_Changed_Representation --
7999 -----------------------------------
8009 begin
8010 -- Nothing else to do if no change of representation
8015 -- The real change of representation work is done by the assignment
8016 -- statement processing. So if this type conversion is appearing as
8017 -- the expression of an assignment statement, nothing needs to be
8018 -- done to the conversion.
8023 -- Otherwise we need to generate a temporary variable, and do the
8024 -- change of representation assignment into that temporary variable.
8025 -- The conversion is then replaced by a reference to this variable.
8027 else
8030 -- If type is unconstrained we have to add a constraint, copied
8031 -- from the actual value of the left hand side.
8045 Prefix =>
8047 Selector_Name =>
8058 -- We convert the bounds explicitly. We use an unchecked
8059 -- conversion because bounds checks are done elsewhere.
8063 Low_Bound =>
8066 Prefix =>
8067 Duplicate_Subexpr_No_Checks
8073 High_Bound =>
8076 Prefix =>
8077 Duplicate_Subexpr_No_Checks
8091 Odef :=
8094 Constraint =>
8100 Decl :=
8107 -- Insert required actions. It is essential to suppress checks
8108 -- since we have suppressed default initialization, which means
8109 -- that the variable we create may have no discriminants.
8112 New_List (
8113 Decl,
8124 -------------------------------
8125 -- Raise_Accessibility_Error --
8126 -------------------------------
8129 begin
8136 Error_Msg_NE
8140 ----------------------
8141 -- Real_Range_Check --
8142 ----------------------
8144 -- Case of conversions to floating-point or fixed-point. If range checks
8145 -- are enabled and the target type has a range constraint, we convert:
8147 -- typ (x)
8149 -- to
8151 -- Tnn : typ'Base := typ'Base (x);
8152 -- [constraint_error when Tnn < typ'First or else Tnn > typ'Last]
8153 -- Tnn
8155 -- This is necessary when there is a conversion of integer to float or
8156 -- to fixed-point to ensure that the correct checks are made. It is not
8157 -- necessary for float to float where it is enough to simply set the
8158 -- Do_Range_Check flag.
8168 begin
8169 -- Nothing to do if conversion was rewritten
8175 -- Nothing to do if range checks suppressed, or target has the same
8176 -- range as the base type (or is the base type).
8180 and then
8182 then
8186 -- Nothing to do if expression is an entity on which checks have been
8187 -- suppressed.
8191 then
8195 -- Nothing to do if bounds are all static and we can tell that the
8196 -- expression is within the bounds of the target. Note that if the
8197 -- operand is of an unconstrained floating-point type, then we do
8198 -- not trust it to be in range (might be infinite)
8200 declare
8204 begin
8211 then
8212 declare
8218 begin
8222 else
8230 then
8238 -- For float to float conversions, we are done
8241 and then
8243 then
8247 -- Otherwise rewrite the conversion as described above
8253 -- Enable overflow except for case of integer to float conversions,
8254 -- where it is never required, since we can never have overflow in
8255 -- this case.
8271 Condition =>
8273 Left_Opnd =>
8276 Right_Opnd =>
8279 Prefix =>
8282 Right_Opnd =>
8285 Right_Opnd =>
8288 Prefix =>
8296 -- Start of processing for Expand_N_Type_Conversion
8298 begin
8299 -- Nothing at all to do if conversion is to the identical type so remove
8300 -- the conversion completely, it is useless, except that it may carry
8301 -- an Assignment_OK attribute, which must be propagated to the operand.
8312 -- Nothing to do if this is the second argument of read. This is a
8313 -- "backwards" conversion that will be handled by the specialized code
8314 -- in attribute processing.
8319 then
8323 -- Check for case of converting to a type that has an invariant
8324 -- associated with it. This required an invariant check. We convert
8326 -- typ (expr)
8328 -- into
8330 -- do invariant_check (typ (expr)) in typ (expr);
8332 -- using Duplicate_Subexpr to avoid multiple side effects
8334 -- Note: the Comes_From_Source check, and then the resetting of this
8335 -- flag prevents what would otherwise be an infinite recursion.
8340 then
8351 -- Here if we may need to expand conversion
8353 -- If the operand of the type conversion is an arithmetic operation on
8354 -- signed integers, and the based type of the signed integer type in
8355 -- question is smaller than Standard.Integer, we promote both of the
8356 -- operands to type Integer.
8358 -- For example, if we have
8360 -- target-type (opnd1 + opnd2)
8362 -- and opnd1 and opnd2 are of type short integer, then we rewrite
8363 -- this as:
8365 -- target-type (integer(opnd1) + integer(opnd2))
8367 -- We do this because we are always allowed to compute in a larger type
8368 -- if we do the right thing with the result, and in this case we are
8369 -- going to do a conversion which will do an appropriate check to make
8370 -- sure that things are in range of the target type in any case. This
8371 -- avoids some unnecessary intermediate overflows.
8373 -- We might consider a similar transformation in the case where the
8374 -- target is a real type or a 64-bit integer type, and the operand
8375 -- is an arithmetic operation using a 32-bit integer type. However,
8376 -- we do not bother with this case, because it could cause significant
8377 -- inefficiencies on 32-bit machines. On a 64-bit machine it would be
8378 -- much cheaper, but we don't want different behavior on 32-bit and
8379 -- 64-bit machines. Note that the exclusion of the 64-bit case also
8380 -- handles the configurable run-time cases where 64-bit arithmetic
8381 -- may simply be unavailable.
8383 -- Note: this circuit is partially redundant with respect to the circuit
8384 -- in Checks.Apply_Arithmetic_Overflow_Check, but we catch more cases in
8385 -- the processing here. Also we still need the Checks circuit, since we
8386 -- have to be sure not to generate junk overflow checks in the first
8387 -- place, since it would be trick to remove them here!
8391 -- All conditions met, go ahead with transformation
8393 declare
8397 begin
8398 R :=
8407 L :=
8425 -- Do validity check if validity checking operands
8427 if Validity_Checks_On
8428 and then Validity_Check_Operands
8429 then
8433 -- Special case of converting from non-standard boolean type
8437 then
8443 -- Case of converting to an access type
8447 -- Apply an accessibility check when the conversion operand is an
8448 -- access parameter (or a renaming thereof), unless conversion was
8449 -- expanded from an Unchecked_ or Unrestricted_Access attribute.
8450 -- Note that other checks may still need to be applied below (such
8451 -- as tagged type checks).
8454 and then
8456 or else
8459 and then Is_Formal
8464 then
8465 Apply_Accessibility_Check
8468 -- If the level of the operand type is statically deeper than the
8469 -- level of the target type, then force Program_Error. Note that this
8470 -- can only occur for cases where the attribute is within the body of
8471 -- an instantiation (otherwise the conversion will already have been
8472 -- rejected as illegal). Note: warnings are issued by the analyzer
8473 -- for the instance cases.
8475 elsif In_Instance_Body
8478 then
8479 Raise_Accessibility_Error;
8481 -- When the operand is a selected access discriminant the check needs
8482 -- to be made against the level of the object denoted by the prefix
8483 -- of the selected name. Force Program_Error for this case as well
8484 -- (this accessibility violation can only happen if within the body
8485 -- of an instantiation).
8487 elsif In_Instance_Body
8492 then
8493 Raise_Accessibility_Error;
8498 -- Case of conversions of tagged types and access to tagged types
8500 -- When needed, that is to say when the expression is class-wide, Add
8501 -- runtime a tag check for (strict) downward conversion by using the
8502 -- membership test, generating:
8504 -- [constraint_error when Operand not in Target_Type'Class]
8506 -- or in the access type case
8508 -- [constraint_error
8509 -- when Operand /= null
8510 -- and then Operand.all not in
8511 -- Designated_Type (Target_Type)'Class]
8516 then
8517 -- Do not do any expansion in the access type case if the parent is a
8518 -- renaming, since this is an error situation which will be caught by
8519 -- Sem_Ch8, and the expansion can interfere with this error check.
8525 -- Otherwise, proceed with processing tagged conversion
8534 -- Create a membership check to test whether Operand is a member
8535 -- of Targ_Typ. If the original Target_Type is an access, include
8536 -- a test for null value. The check is inserted at N.
8538 --------------------
8539 -- Make_Tag_Check --
8540 --------------------
8545 begin
8546 -- Generate:
8547 -- [Constraint_Error
8548 -- when Operand /= null
8549 -- and then Operand.all not in Targ_Typ]
8552 Cond :=
8554 Left_Opnd =>
8559 Right_Opnd =>
8561 Left_Opnd =>
8566 -- Generate:
8567 -- [Constraint_Error when Operand not in Targ_Typ]
8569 else
8570 Cond :=
8582 -- Start of processing for Tagged_Conversion
8584 begin
8587 -- Handle entities from the limited view
8589 Actual_Op_Typ :=
8591 Actual_Targ_Typ :=
8593 else
8600 -- Ada 2005 (AI-251): Handle interface type conversion
8609 -- Create a runtime tag check for a downward class-wide type
8610 -- conversion.
8616 then
8621 -- AI05-0073: If the result subtype of the function is defined
8622 -- by an access_definition designating a specific tagged type
8623 -- T, a check is made that the result value is null or the tag
8624 -- of the object designated by the result value identifies T.
8625 -- Constraint_Error is raised if this check fails.
8628 declare
8632 begin
8633 -- Climb scope stack looking for the enclosing function
8638 loop
8642 -- The function's return subtype must be defined using
8643 -- an access definition.
8646 N_Access_Definition
8647 then
8650 -- The return subtype denotes a specific tagged type,
8651 -- in other words, a non class-wide type.
8655 then
8663 -- We have generated a tag check for either a class-wide type
8664 -- conversion or for AI05-0073.
8667 declare
8669 begin
8670 Conv :=
8681 -- Case of other access type conversions
8686 -- Case of conversions from a fixed-point type
8688 -- These conversions require special expansion and processing, found in
8689 -- the Exp_Fixd package. We ignore cases where Conversion_OK is set,
8690 -- since from a semantic point of view, these are simple integer
8691 -- conversions, which do not need further processing.
8695 then
8696 -- We should never see universal fixed at this case, since the
8697 -- expansion of the constituent divide or multiply should have
8698 -- eliminated the explicit mention of universal fixed.
8702 -- Check for special case of the conversion to universal real that
8703 -- occurs as a result of the use of a round attribute. In this case,
8704 -- the real type for the conversion is taken from the target type of
8705 -- the Round attribute and the result must be marked as rounded.
8710 then
8715 -- Otherwise do correct fixed-conversion, but skip these if the
8716 -- Conversion_OK flag is set, because from a semantic point of view
8717 -- these are simple integer conversions needing no further processing
8718 -- (the backend will simply treat them as integers).
8723 Real_Range_Check;
8728 else
8731 Real_Range_Check;
8735 -- Case of conversions to a fixed-point type
8737 -- These conversions require special expansion and processing, found in
8738 -- the Exp_Fixd package. Again, ignore cases where Conversion_OK is set,
8739 -- since from a semantic point of view, these are simple integer
8740 -- conversions, which do not need further processing.
8744 then
8747 Real_Range_Check;
8748 else
8751 Real_Range_Check;
8754 -- Case of float-to-integer conversions
8756 -- We also handle float-to-fixed conversions with Conversion_OK set
8757 -- since semantically the fixed-point target is treated as though it
8758 -- were an integer in such cases.
8761 and then
8763 or else
8765 then
8766 -- One more check here, gcc is still not able to do conversions of
8767 -- this type with proper overflow checking, and so gigi is doing an
8768 -- approximation of what is required by doing floating-point compares
8769 -- with the end-point. But that can lose precision in some cases, and
8770 -- give a wrong result. Converting the operand to Universal_Real is
8771 -- helpful, but still does not catch all cases with 64-bit integers
8772 -- on targets with only 64-bit floats.
8774 -- The above comment seems obsoleted by Apply_Float_Conversion_Check
8775 -- Can this code be removed ???
8780 Subtype_Mark =>
8782 Expression =>
8790 -- Case of array conversions
8792 -- Expansion of array conversions, add required length/range checks but
8793 -- only do this if there is no change of representation. For handling of
8794 -- this case, see Handle_Changed_Representation.
8799 else
8803 Handle_Changed_Representation;
8805 -- Case of conversions of discriminated types
8807 -- Add required discriminant checks if target is constrained. Again this
8808 -- change is skipped if we have a change of representation.
8812 then
8814 Handle_Changed_Representation;
8816 -- Case of all other record conversions. The only processing required
8817 -- is to check for a change of representation requiring the special
8818 -- assignment processing.
8822 -- Ada 2005 (AI-216): Program_Error is raised when converting from
8823 -- a derived Unchecked_Union type to an unconstrained type that is
8824 -- not Unchecked_Union if the operand lacks inferable discriminants.
8831 then
8832 -- To prevent Gigi from generating illegal code, we generate a
8833 -- Program_Error node, but we give it the target type of the
8834 -- conversion.
8836 declare
8840 begin
8845 else
8846 Handle_Changed_Representation;
8849 -- Case of conversions of enumeration types
8853 -- Special processing is required if there is a change of
8854 -- representation (from enumeration representation clauses).
8858 -- Convert: x(y) to x'val (ytyp'val (y))
8873 -- Case of conversions to floating-point
8876 Real_Range_Check;
8879 -- At this stage, either the conversion node has been transformed into
8880 -- some other equivalent expression, or left as a conversion that can be
8881 -- handled by Gigi, in the following cases:
8883 -- Conversions with no change of representation or type
8885 -- Numeric conversions involving integer, floating- and fixed-point
8886 -- values. Fixed-point values are allowed only if Conversion_OK is
8887 -- set, i.e. if the fixed-point values are to be treated as integers.
8889 -- No other conversions should be passed to Gigi
8891 -- Check: are these rules stated in sinfo??? if so, why restate here???
8893 -- The only remaining step is to generate a range check if we still have
8894 -- a type conversion at this stage and Do_Range_Check is set. For now we
8895 -- do this only for conversions of discrete types.
8899 then
8900 declare
8905 begin
8908 then
8911 -- Before we do a range check, we have to deal with treating a
8912 -- fixed-point operand as an integer. The way we do this is
8913 -- simply to do an unchecked conversion to an appropriate
8914 -- integer type large enough to hold the result.
8916 -- This code is not active yet, because we are only dealing
8917 -- with discrete types so far ???
8921 then
8926 else
8933 -- Reset overflow flag, since the range check will include
8934 -- dealing with possible overflow, and generate the check. If
8935 -- Address is either a source type or target type, suppress
8936 -- range check to avoid typing anomalies when it is a visible
8937 -- integer type.
8942 then
8943 Generate_Range_Check
8950 -- Final step, if the result is a type conversion involving Vax_Float
8951 -- types, then it is subject for further special processing.
8955 then
8960 -- Here at end of processing
8963 -- Apply predicate check if required. Note that we can't just call
8964 -- Apply_Predicate_Check here, because the type looks right after
8965 -- the conversion and it would omit the check. The Comes_From_Source
8966 -- guard is necessary to prevent infinite recursions when we generate
8967 -- internal conversions for the purpose of checking predicates.
8972 then
8978 -----------------------------------
8979 -- Expand_N_Unchecked_Expression --
8980 -----------------------------------
8982 -- Remove the unchecked expression node from the tree. Its job was simply
8983 -- to make sure that its constituent expression was handled with checks
8984 -- off, and now that that is done, we can remove it from the tree, and
8985 -- indeed must, since Gigi does not expect to see these nodes.
8989 begin
8994 ----------------------------------------
8995 -- Expand_N_Unchecked_Type_Conversion --
8996 ----------------------------------------
8998 -- If this cannot be handled by Gigi and we haven't already made a
8999 -- temporary for it, do it now.
9006 begin
9007 -- Nothing at all to do if conversion is to the identical type so remove
9008 -- the conversion completely, it is useless, except that it may carry
9009 -- an Assignment_OK indication which must be propagated to the operand.
9013 -- Code duplicates Expand_N_Unchecked_Expression above, factor???
9023 -- If we have a conversion of a compile time known value to a target
9024 -- type and the value is in range of the target type, then we can simply
9025 -- replace the construct by an integer literal of the correct type. We
9026 -- only apply this to integer types being converted. Possibly it may
9027 -- apply in other cases, but it is too much trouble to worry about.
9029 -- Note that we do not do this transformation if the Kill_Range_Check
9030 -- flag is set, since then the value may be outside the expected range.
9031 -- This happens in the Normalize_Scalars case.
9033 -- We also skip this if either the target or operand type is biased
9034 -- because in this case, the unchecked conversion is supposed to
9035 -- preserve the bit pattern, not the integer value.
9043 then
9044 declare
9047 begin
9049 and then
9051 and then
9053 and then
9055 then
9058 -- If Address is the target type, just set the type to avoid a
9059 -- spurious type error on the literal when Address is a visible
9060 -- integer type.
9064 else
9073 -- Nothing to do if conversion is safe
9079 -- Otherwise force evaluation unless Assignment_OK flag is set (this
9080 -- flag indicates ??? -- more comments needed here)
9084 else
9089 ----------------------------
9090 -- Expand_Record_Equality --
9091 ----------------------------
9093 -- For non-variant records, Equality is expanded when needed into:
9095 -- and then Lhs.Discr1 = Rhs.Discr1
9096 -- and then ...
9097 -- and then Lhs.Discrn = Rhs.Discrn
9098 -- and then Lhs.Cmp1 = Rhs.Cmp1
9099 -- and then ...
9100 -- and then Lhs.Cmpn = Rhs.Cmpn
9102 -- The expression is folded by the back-end for adjacent fields. This
9103 -- function is called for tagged record in only one occasion: for imple-
9104 -- menting predefined primitive equality (see Predefined_Primitives_Bodies)
9105 -- otherwise the primitive "=" is used directly.
9107 function Expand_Record_Equality
9113 is
9122 -- Return the first field to compare beginning with C, skipping the
9123 -- inherited components.
9125 ----------------------
9126 -- Suitable_Element --
9127 ----------------------
9130 begin
9136 then
9141 then
9146 then
9152 else
9157 -- Start of processing for Expand_Record_Equality
9159 begin
9160 -- Generates the following code: (assuming that Typ has one Discr and
9161 -- component C2 is also a record)
9163 -- True
9164 -- and then Lhs.Discr1 = Rhs.Discr1
9165 -- and then Lhs.C1 = Rhs.C1
9166 -- and then Lhs.C2.C1=Rhs.C2.C1 and then ... Lhs.C2.Cn=Rhs.C2.Cn
9167 -- and then ...
9168 -- and then Lhs.Cmpn = Rhs.Cmpn
9173 declare
9178 begin
9183 else
9188 Check :=
9190 Lhs =>
9194 Rhs =>
9200 -- If some (sub)component is an unchecked_union, the whole
9201 -- operation will raise program error.
9207 else
9208 Result :=
9221 -----------------------------------
9222 -- Expand_Short_Circuit_Operator --
9223 -----------------------------------
9225 -- Deal with special expansion if actions are present for the right operand
9226 -- and deal with optimizing case of arguments being True or False. We also
9227 -- deal with the special case of non-standard boolean values.
9239 -- If Left = Shortcut_Value then Right need not be evaluated
9242 -- For Opnd a boolean expression, return a Boolean expression equivalent
9243 -- to Opnd /= Shortcut_Value.
9245 --------------------
9246 -- Make_Test_Expr --
9247 --------------------
9250 begin
9253 else
9259 -- Entity for a temporary variable holding the value of the operator,
9260 -- used for expansion in the case where actions are present.
9262 -- Start of processing for Expand_Short_Circuit_Operator
9264 begin
9265 -- Deal with non-standard booleans
9273 -- Check for cases where left argument is known to be True or False
9277 -- Mark SCO for left condition as compile time known
9283 -- Rewrite True AND THEN Right / False OR ELSE Right to Right.
9284 -- Any actions associated with Right will be executed unconditionally
9285 -- and can thus be inserted into the tree unconditionally.
9294 -- Rewrite False AND THEN Right / True OR ELSE Right to Left.
9295 -- In this case we can forget the actions associated with Right,
9296 -- since they will never be executed.
9298 else
9308 -- If Actions are present for the right operand, we have to do some
9309 -- special processing. We can't just let these actions filter back into
9310 -- code preceding the short circuit (which is what would have happened
9311 -- if we had not trapped them in the short-circuit form), since they
9312 -- must only be executed if the right operand of the short circuit is
9313 -- executed and not otherwise.
9315 -- the temporary variable C.
9320 -- The old approach is to expand:
9322 -- left AND THEN right
9324 -- into
9326 -- C : Boolean := False;
9327 -- IF left THEN
9328 -- Actions;
9329 -- IF right THEN
9330 -- C := True;
9331 -- END IF;
9332 -- END IF;
9334 -- and finally rewrite the operator into a reference to C. Similarly
9335 -- for left OR ELSE right, with negated values. Note that this
9336 -- rewrite causes some difficulties for coverage analysis because
9337 -- of the introduction of the new variable C, which obscures the
9338 -- structure of the test.
9340 -- We use this "old approach" if use of N_Expression_With_Actions
9341 -- is False (see description in Opt of when this is or is not set).
9348 Defining_Identifier =>
9349 Op_Var,
9350 Object_Definition =>
9352 Expression =>
9361 Expression =>
9362 New_Occurrence_Of
9373 -- The new approach, activated for now by the use of debug flag
9374 -- -gnatd.X is to use the new Expression_With_Actions node for the
9375 -- right operand of the short-circuit form. This should solve the
9376 -- traceability problems for coverage analysis.
9378 else
9391 -- No actions present, check for cases of right argument True/False
9395 -- Mark SCO for left condition as compile time known
9401 -- Change (Left and then True), (Left or else False) to Left.
9402 -- Note that we know there are no actions associated with the right
9403 -- operand, since we just checked for this case above.
9408 -- Change (Left and then False), (Left or else True) to Right,
9409 -- making sure to preserve any side effects associated with the Left
9410 -- operand.
9412 else
9421 -------------------------------------
9422 -- Fixup_Universal_Fixed_Operation --
9423 -------------------------------------
9428 begin
9429 -- We must have a type conversion immediately above us
9433 -- Normally the type conversion gives our target type. The exception
9434 -- occurs in the case of the Round attribute, where the conversion
9435 -- will be to universal real, and our real type comes from the Round
9436 -- attribute (as well as an indication that we must round the result)
9440 then
9444 -- Normal case where type comes from conversion above us
9446 else
9451 ------------------------------
9452 -- Get_Allocator_Final_List --
9453 ------------------------------
9455 function Get_Allocator_Final_List
9459 is
9463 -- The entity whose finalization list must be used to attach the
9464 -- allocated object.
9466 begin
9469 -- If the context is an access parameter, we need to create a
9470 -- non-anonymous access type in order to have a usable final list,
9471 -- because there is otherwise no pool to which the allocated object
9472 -- can belong. We create both the type and the finalization chain
9473 -- here, because freezing an internal type does not create such a
9474 -- chain. The Final_Chain that is thus created is shared by the
9475 -- access parameter. The access type is tested against the result
9476 -- type of the function to exclude allocators whose type is an
9477 -- anonymous access result type. We freeze the type at once to
9478 -- ensure that it is properly decorated for the back-end, even
9479 -- if the context and current scope is a loop.
9482 in N_Subprogram_Specification
9483 and then
9484 PtrT /=
9486 then
9491 Type_Definition =>
9493 Subtype_Indication =>
9500 -- Ada 2005 (AI-318-02): If the context is a return object
9501 -- declaration, then the anonymous return subtype is defined to have
9502 -- the same accessibility level as that of the function's result
9503 -- subtype, which means that we want the scope where the function is
9504 -- declared.
9508 then
9511 -- Case of an access discriminant, or (Ada 2005) of an anonymous
9512 -- access component or anonymous access function result: find the
9513 -- final list associated with the scope of the type. (In the
9514 -- anonymous access component kind, a list controller will have
9515 -- been allocated when freezing the record type, and PtrT has an
9516 -- Associated_Final_Chain attribute designating it.)
9526 ---------------------------------
9527 -- Has_Inferable_Discriminants --
9528 ---------------------------------
9533 -- Determines whether the left-most prefix of a selected component is a
9534 -- formal parameter in a subprogram. Assumes N is a selected component.
9536 --------------------------------
9537 -- Prefix_Is_Formal_Parameter --
9538 --------------------------------
9543 begin
9544 -- Move to the left-most prefix by climbing up the tree
9548 loop
9555 -- Start of processing for Has_Inferable_Discriminants
9557 begin
9558 -- For identifiers and indexed components, it is sufficient to have a
9559 -- constrained Unchecked_Union nominal subtype.
9563 and then
9566 -- For selected components, the subtype of the selector must be a
9567 -- constrained Unchecked_Union. If the component is subject to a
9568 -- per-object constraint, then the enclosing object must have inferable
9569 -- discriminants.
9574 -- A small hack. If we have a per-object constrained selected
9575 -- component of a formal parameter, return True since we do not
9576 -- know the actual parameter association yet.
9582 -- Otherwise, check the enclosing object and the selector
9585 and then
9589 -- The call to Has_Inferable_Discriminants will determine whether
9590 -- the selector has a constrained Unchecked_Union nominal type.
9594 -- A qualified expression has inferable discriminants if its subtype
9595 -- mark is a constrained Unchecked_Union subtype.
9599 and then
9607 -------------------------------
9608 -- Insert_Dereference_Action --
9609 -------------------------------
9618 -- Return true if type of P is derived from Checked_Pool;
9620 -----------------------------
9621 -- Is_Checked_Storage_Pool --
9622 -----------------------------
9627 begin
9636 else
9644 -- Start of processing for Insert_Dereference_Action
9646 begin
9651 then
9662 -- Pool
9666 -- Storage_Address. We use the attribute Pool_Address, which uses
9667 -- the pointer itself to find the address of the object, and which
9668 -- handles unconstrained arrays properly by computing the address
9669 -- of the template. i.e. the correct address of the corresponding
9670 -- allocation.
9676 -- Size_In_Storage_Elements
9679 Left_Opnd =>
9681 Prefix =>
9685 Right_Opnd =>
9688 -- Alignment
9691 Prefix =>
9696 exception
9701 --------------------------------
9702 -- Integer_Promotion_Possible --
9703 --------------------------------
9710 begin
9713 return
9715 -- We only do the transformation for source constructs. We assume
9716 -- that the expander knows what it is doing when it generates code.
9720 -- If the operand type is Short_Integer or Short_Short_Integer,
9721 -- then we will promote to Integer, which is available on all
9722 -- targets, and is sufficient to ensure no intermediate overflow.
9723 -- Furthermore it is likely to be as efficient or more efficient
9724 -- than using the smaller type for the computation so we do this
9725 -- unconditionally.
9727 and then
9729 or else
9732 -- Test for interesting operation, which includes addition,
9733 -- division, exponentiation, multiplication, subtraction, absolute
9734 -- value and unary negation. Unary "+" is omitted since it is a
9735 -- no-op and thus can't overflow.
9738 N_Op_Add,
9739 N_Op_Divide,
9740 N_Op_Expon,
9741 N_Op_Minus,
9742 N_Op_Multiply,
9743 N_Op_Subtract);
9746 ------------------------------
9747 -- Make_Array_Comparison_Op --
9748 ------------------------------
9750 -- This is a hand-coded expansion of the following generic function:
9752 -- generic
9753 -- type elem is (<>);
9754 -- type index is (<>);
9755 -- type a is array (index range <>) of elem;
9757 -- function Gnnn (X : a; Y: a) return boolean is
9758 -- J : index := Y'first;
9760 -- begin
9761 -- if X'length = 0 then
9762 -- return false;
9764 -- elsif Y'length = 0 then
9765 -- return true;
9767 -- else
9768 -- for I in X'range loop
9769 -- if X (I) = Y (J) then
9770 -- if J = Y'last then
9771 -- exit;
9772 -- else
9773 -- J := index'succ (J);
9774 -- end if;
9776 -- else
9777 -- return X (I) > Y (J);
9778 -- end if;
9779 -- end loop;
9781 -- return X'length > Y'length;
9782 -- end if;
9783 -- end Gnnn;
9785 -- Note that since we are essentially doing this expansion by hand, we
9786 -- do not need to generate an actual or formal generic part, just the
9787 -- instantiated function itself.
9789 function Make_Array_Comparison_Op
9792 is
9813 begin
9814 -- if J = Y'last then
9815 -- exit;
9816 -- else
9817 -- J := index'succ (J);
9818 -- end if;
9820 Inner_If :=
9822 Condition =>
9825 Right_Opnd =>
9833 Else_Statements =>
9834 New_List (
9837 Expression =>
9843 -- if X (I) = Y (J) then
9844 -- if ... end if;
9845 -- else
9846 -- return X (I) > Y (J);
9847 -- end if;
9849 Loop_Body :=
9851 Condition =>
9853 Left_Opnd =>
9858 Right_Opnd =>
9867 Expression =>
9869 Left_Opnd =>
9874 Right_Opnd =>
9880 -- for I in X'range loop
9881 -- if ... end if;
9882 -- end loop;
9884 Loop_Statement :=
9888 Iteration_Scheme =>
9890 Loop_Parameter_Specification =>
9893 Discrete_Subtype_Definition =>
9900 -- if X'length = 0 then
9901 -- return false;
9902 -- elsif Y'length = 0 then
9903 -- return true;
9904 -- else
9905 -- for ... loop ... end loop;
9906 -- return X'length > Y'length;
9907 -- end if;
9909 Length1 :=
9914 Length2 :=
9919 Final_Expr :=
9924 If_Stat :=
9926 Condition =>
9928 Left_Opnd =>
9932 Right_Opnd =>
9935 Then_Statements =>
9936 New_List (
9942 Condition =>
9944 Left_Opnd =>
9948 Right_Opnd =>
9951 Then_Statements =>
9952 New_List (
9957 Loop_Statement,
9961 -- (X : a; Y: a)
9972 -- function Gnnn (...) return boolean is
9973 -- J : index := Y'first;
9974 -- begin
9975 -- if ... end if;
9976 -- end Gnnn;
9980 Func_Body :=
9982 Specification =>
9992 Expression =>
9997 Handled_Statement_Sequence =>
10004 ---------------------------
10005 -- Make_Boolean_Array_Op --
10006 ---------------------------
10008 -- For logical operations on boolean arrays, expand in line the following,
10009 -- replacing 'and' with 'or' or 'xor' where needed:
10011 -- function Annn (A : typ; B: typ) return typ is
10012 -- C : typ;
10013 -- begin
10014 -- for J in A'range loop
10015 -- C (J) := A (J) op B (J);
10016 -- end loop;
10017 -- return C;
10018 -- end Annn;
10020 -- Here typ is the boolean array type
10022 function Make_Boolean_Array_Op
10025 is
10043 begin
10044 A_J :=
10049 B_J :=
10054 C_J :=
10060 Op :=
10066 Op :=
10071 else
10072 Op :=
10078 Loop_Statement :=
10082 Iteration_Scheme =>
10084 Loop_Parameter_Specification =>
10087 Discrete_Subtype_Definition =>
10109 Func_Body :=
10111 Specification =>
10122 Handled_Statement_Sequence =>
10125 Loop_Statement,
10132 ------------------------
10133 -- Rewrite_Comparison --
10134 ------------------------
10138 -- Set to True if first pass with Assume_Valid generates a warning in
10139 -- which case we skip the second pass to avoid warning overloaded.
10142 -- Set to Standard_True or Standard_False
10144 begin
10153 -- Now start looking at the comparison in detail. We potentially go
10154 -- through this loop twice. The first time, Assume_Valid is set False
10155 -- in the call to Compile_Time_Compare. If this call results in a
10156 -- clear result of always True or Always False, that's decisive and
10157 -- we are done. Otherwise we repeat the processing with Assume_Valid
10158 -- set to True to generate additional warnings. We can skip that step
10159 -- if Constant_Condition_Warnings is False.
10162 declare
10169 -- Res indicates if compare outcome can be compile time determined
10174 begin
10185 and then Constant_Condition_Warnings
10188 and then not In_Instance
10191 then
10192 Error_Msg_N
10210 and then Constant_Condition_Warnings
10213 and then not In_Instance
10216 then
10217 Error_Msg_N
10227 -- If this is the first iteration, then we actually convert the
10228 -- comparison into True or False, if the result is certain.
10234 else
10246 -- If this is the second iteration (AV = True), and the original
10247 -- node comes from source and we are not in an instance, then give
10248 -- a warning if we know result would be True or False. Note: we
10249 -- know Constant_Condition_Warnings is set if we get here.
10252 and then not In_Instance
10253 then
10255 Error_Msg_N
10257 N);
10259 Error_Msg_N
10261 N);
10266 -- Skip second iteration if not warning on constant conditions or
10267 -- if the first iteration already generated a warning of some kind or
10268 -- if we are in any case assuming all values are valid (so that the
10269 -- first iteration took care of the valid case).
10277 ----------------------------
10278 -- Safe_In_Place_Array_Op --
10279 ----------------------------
10281 function Safe_In_Place_Array_Op
10285 is
10289 -- Operand is safe if it cannot overlap part of the target of the
10290 -- operation. If the operand and the target are identical, the operand
10291 -- is safe. The operand can be empty in the case of negation.
10294 -- Check that N is a stand-alone entity
10296 ------------------
10297 -- Is_Unaliased --
10298 ------------------
10301 begin
10302 return
10308 ---------------------
10309 -- Is_Safe_Operand --
10310 ---------------------
10313 begin
10324 return
10331 else
10336 -- Start of processing for Is_Safe_In_Place_Array_Op
10338 begin
10339 -- Skip this processing if the component size is different from system
10340 -- storage unit (since at least for NOT this would cause problems).
10345 -- Cannot do in place stuff on VM_Target since cannot pass addresses
10350 -- Cannot do in place stuff if non-standard Boolean representation
10358 else
10364 -----------------------
10365 -- Tagged_Membership --
10366 -----------------------
10368 -- There are two different cases to consider depending on whether the right
10369 -- operand is a class-wide type or not. If not we just compare the actual
10370 -- tag of the left expr to the target type tag:
10371 --
10372 -- Left_Expr.Tag = Right_Type'Tag;
10373 --
10374 -- If it is a class-wide type we use the RT function CW_Membership which is
10375 -- usually implemented by looking in the ancestor tables contained in the
10376 -- dispatch table pointed by Left_Expr.Tag for Typ'Tag
10378 -- Ada 2005 (AI-251): If it is a class-wide interface type we use the RT
10379 -- function IW_Membership which is usually implemented by looking in the
10380 -- table of abstract interface types plus the ancestor table contained in
10381 -- the dispatch table pointed by Left_Expr.Tag for Typ'Tag
10383 procedure Tagged_Membership
10387 is
10397 begin
10400 -- Handle entities from the limited view
10409 Obj_Tag :=
10412 Selector_Name =>
10417 -- No need to issue a run-time check if we statically know that the
10418 -- result of this membership test is always true. For example,
10419 -- considering the following declarations:
10421 -- type Iface is interface;
10422 -- type T is tagged null record;
10423 -- type DT is new T and Iface with null record;
10425 -- Obj1 : T;
10426 -- Obj2 : DT;
10428 -- These membership tests are always true:
10430 -- Obj1 in T'Class
10431 -- Obj2 in T'Class;
10432 -- Obj2 in Iface'Class;
10434 -- We do not need to handle cases where the membership is illegal.
10435 -- For example:
10437 -- Obj1 in DT'Class; -- Compile time error
10438 -- Obj1 in Iface'Class; -- Compile time error
10443 and then Interface_Present_In_Ancestor
10446 then
10451 -- Ada 2005 (AI-251): Class-wide applied to interfaces
10455 -- Support to: "Iface_CW_Typ in Typ'Class"
10458 then
10459 -- Issue error if IW_Membership operation not available in a
10460 -- configurable run time setting.
10463 Error_Msg_CRT
10469 Result :=
10476 New_Reference_To (
10477 Node (First_Elmt
10479 Loc)));
10481 -- Ada 95: Normal case
10483 else
10486 Typ_Tag_Node =>
10487 New_Reference_To (
10488 Node (First_Elmt
10490 Loc),
10494 -- Generate the SCIL node for this class-wide membership test.
10495 -- Done here because the previous call to Build_CW_Membership
10496 -- relocates Obj_Tag.
10507 -- Right_Type is not a class-wide type
10509 else
10510 -- No need to check the tag of the object if Right_Typ is abstract
10515 else
10516 Result :=
10519 Right_Opnd =>
10520 New_Reference_To
10526 ------------------------------
10527 -- Unary_Op_Validity_Checks --
10528 ------------------------------
10531 begin