| blob | dad493cbe066efc6b449b66a51705e1c70bf5485 |
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 ------------------------------------------------------------------------------
78 -----------------------
79 -- Local Subprograms --
80 -----------------------
84 -- Performs validity checks for a binary operator
86 procedure Build_Boolean_Array_Proc_Call
90 -- If a boolean array assignment can be done in place, build call to
91 -- corresponding library procedure.
94 -- Ada 2005 (AI-251): Subsidiary procedure to Expand_N_Allocator and
95 -- Expand_Allocator_Expression. Allocating class-wide interface objects
96 -- this routine displaces the pointer to the allocated object to reference
97 -- the component referencing the corresponding secondary dispatch table.
100 -- Subsidiary to Expand_N_Allocator, for the case when the expression
101 -- is a qualified expression or an aggregate.
104 -- This routine handles expansion of the comparison operators (N_Op_Lt,
105 -- N_Op_Le, N_Op_Gt, N_Op_Ge) when operating on an array type. The basic
106 -- code for these operators is similar, differing only in the details of
107 -- the actual comparison call that is made. Special processing (call a
108 -- run-time routine)
110 function Expand_Array_Equality
116 -- Expand an array equality into a call to a function implementing this
117 -- equality, and a call to it. Loc is the location for the generated nodes.
118 -- Lhs and Rhs are the array expressions to be compared. Bodies is a list
119 -- on which to attach bodies of local functions that are created in the
120 -- process. It is the responsibility of the caller to insert those bodies
121 -- at the right place. Nod provides the Sloc value for the generated code.
122 -- Normally the types used for the generated equality routine are taken
123 -- from Lhs and Rhs. However, in some situations of generated code, the
124 -- Etype fields of Lhs and Rhs are not set yet. In such cases, Typ supplies
125 -- the type to be used for the formal parameters.
128 -- Common expansion processing for Boolean operators (And, Or, Xor) for the
129 -- case of array type arguments.
132 -- Common expansion processing for short-circuit boolean operators
134 function Expand_Composite_Equality
140 -- Local recursive function used to expand equality for nested composite
141 -- types. Used by Expand_Record/Array_Equality, Bodies is a list on which
142 -- to attach bodies of local functions that are created in the process.
143 -- This is the responsibility of the caller to insert those bodies at the
144 -- right place. Nod provides the Sloc value for generated code. Lhs and Rhs
145 -- are the left and right sides for the comparison, and Typ is the type of
146 -- the arrays to compare.
149 -- Routine to expand concatenation of a sequence of two or more operands
150 -- (in the list Operands) and replace node Cnode with the result of the
151 -- concatenation. The operands can be of any appropriate type, and can
152 -- include both arrays and singleton elements.
155 -- N is a N_Op_Divide or N_Op_Multiply node whose result is universal
156 -- fixed. We do not have such a type at runtime, so the purpose of this
157 -- routine is to find the real type by looking up the tree. We also
158 -- determine if the operation must be rounded.
160 function Get_Allocator_Final_List
164 -- If the designated type is controlled, build final_list expression for
165 -- created object. If context is an access parameter, create a local access
166 -- type to have a usable finalization list.
169 -- Ada 2005 (AI-216): A view of an Unchecked_Union object has inferable
170 -- discriminants if it has a constrained nominal type, unless the object
171 -- is a component of an enclosing Unchecked_Union object that is subject
172 -- to a per-object constraint and the enclosing object lacks inferable
173 -- discriminants.
174 --
175 -- An expression of an Unchecked_Union type has inferable discriminants
176 -- if it is either a name of an object with inferable discriminants or a
177 -- qualified expression whose subtype mark denotes a constrained subtype.
180 -- N is an expression whose type is an access. When the type of the
181 -- associated storage pool is derived from Checked_Pool, generate a
182 -- call to the 'Dereference' primitive operation.
184 function Make_Array_Comparison_Op
187 -- Comparisons between arrays are expanded in line. This function produces
188 -- the body of the implementation of (a > b), where a and b are one-
189 -- dimensional arrays of some discrete type. The original node is then
190 -- expanded into the appropriate call to this function. Nod provides the
191 -- Sloc value for the generated code.
193 function Make_Boolean_Array_Op
196 -- Boolean operations on boolean arrays are expanded in line. This function
197 -- produce the body for the node N, which is (a and b), (a or b), or (a xor
198 -- b). It is used only the normal case and not the packed case. The type
199 -- involved, Typ, is the Boolean array type, and the logical operations in
200 -- the body are simple boolean operations. Note that Typ is always a
201 -- constrained type (the caller has ensured this by using
202 -- Convert_To_Actual_Subtype if necessary).
205 -- If N is the node for a comparison whose outcome can be determined at
206 -- compile time, then the node N can be rewritten with True or False. If
207 -- the outcome cannot be determined at compile time, the call has no
208 -- effect. If N is a type conversion, then this processing is applied to
209 -- its expression. If N is neither comparison nor a type conversion, the
210 -- call has no effect.
212 procedure Tagged_Membership
216 -- Construct the expression corresponding to the tagged membership test.
217 -- Deals with a second operand being (or not) a class-wide type.
219 function Safe_In_Place_Array_Op
223 -- In the context of an assignment, where the right-hand side is a boolean
224 -- operation on arrays, check whether operation can be performed in place.
228 -- Performs validity checks for a unary operator
230 -------------------------------
231 -- Binary_Op_Validity_Checks --
232 -------------------------------
235 begin
242 ------------------------------------
243 -- Build_Boolean_Array_Proc_Call --
244 ------------------------------------
246 procedure Build_Boolean_Array_Proc_Call
250 is
263 begin
267 -- Use negated version of the binary operators
279 Call_Node :=
284 Target,
297 else
300 Call_Node :=
304 Target,
315 else
316 -- We use the following equivalences:
318 -- (not X) or (not Y) = not (X and Y) = Nand (X, Y)
319 -- (not X) and (not Y) = not (X or Y) = Nor (X, Y)
320 -- (not X) xor (not Y) = X xor Y
321 -- X xor (not Y) = not (X xor Y) = Nxor (X, Y)
328 else
332 else
340 else
345 Call_Node :=
349 Target,
364 exception
369 --------------------------------
370 -- Displace_Allocator_Pointer --
371 --------------------------------
380 begin
381 -- Do nothing in case of VM targets: the virtual machine will handle
382 -- interfaces directly.
397 then
398 -- If the type of the allocator expression is not an interface type
399 -- we can generate code to reference the record component containing
400 -- the pointer to the secondary dispatch table.
403 declare
406 begin
407 -- 1) Get access to the allocated object
415 -- 2) Add the conversion to displace the pointer to reference
416 -- the secondary dispatch table.
421 -- 3) The 'access to the secondary dispatch table will be used
422 -- as the value returned by the allocator.
432 -- If the type of the allocator expression is an interface type we
433 -- generate a run-time call to displace "this" to reference the
434 -- component containing the pointer to the secondary dispatch table
435 -- or else raise Constraint_Error if the actual object does not
436 -- implement the target interface. This case corresponds with the
437 -- following example:
439 -- function Op (Obj : Iface_1'Class) return access Iface_2'Class is
440 -- begin
441 -- return new Iface_2'Class'(Obj);
442 -- end Op;
444 else
453 New_Occurrence_Of
455 (First_Elmt
457 Loc)))));
463 ---------------------------------
464 -- Expand_Allocator_Expression --
465 ---------------------------------
473 procedure Apply_Accessibility_Check
476 -- Ada 2005 (AI-344): For an allocator with a class-wide designated
477 -- type, generate an accessibility check to verify that the level of the
478 -- type of the created object is not deeper than the level of the access
479 -- type. If the type of the qualified expression is class- wide, then
480 -- always generate the check (except in the case where it is known to be
481 -- unnecessary, see comment below). Otherwise, only generate the check
482 -- if the level of the qualified expression type is statically deeper
483 -- than the access type.
484 --
485 -- Although the static accessibility will generally have been performed
486 -- as a legality check, it won't have been done in cases where the
487 -- allocator appears in generic body, so a run-time check is needed in
488 -- general. One special case is when the access type is declared in the
489 -- same scope as the class-wide allocator, in which case the check can
490 -- never fail, so it need not be generated.
491 --
492 -- As an open issue, there seem to be cases where the static level
493 -- associated with the class-wide object's underlying type is not
494 -- sufficient to perform the proper accessibility check, such as for
495 -- allocators in nested subprograms or accept statements initialized by
496 -- class-wide formals when the actual originates outside at a deeper
497 -- static level. The nested subprogram case might require passing
498 -- accessibility levels along with class-wide parameters, and the task
499 -- case seems to be an actual gap in the language rules that needs to
500 -- be fixed by the ARG. ???
502 -------------------------------
503 -- Apply_Accessibility_Check --
504 -------------------------------
506 procedure Apply_Accessibility_Check
509 is
512 begin
513 -- Note: we skip the accessibility check for the VM case, since
514 -- there does not seem to be any practical way of implementing it.
517 and then Tagged_Type_Expansion
520 and then
522 or else
525 then
526 -- If the allocator was built in place Ref is already a reference
527 -- to the access object initialized to the result of the allocator
528 -- (see Exp_Ch6.Make_Build_In_Place_Call_In_Allocator). Otherwise
529 -- it is the entity associated with the object containing the
530 -- address of the allocated object.
534 else
540 Condition =>
542 Left_Opnd =>
547 Right_Opnd =>
554 -- Local variables
563 -- Type used as source for tag assignment
566 -- Target reference for tag assignment
573 -- Start of processing for Expand_Allocator_Expression
575 begin
580 -- Generate:
581 -- Pnnn : constant ptr_T := new (T); Init (Pnnn.all,...); Pnnn
583 -- Allocate the object with no expression
588 -- Avoid its expansion to avoid generating a call to the default
589 -- C++ constructor
604 -- Locate the enclosing list and insert the C++ constructor call
606 declare
609 begin
617 Id_Ref =>
629 -- Ada 2005 (AI-318-02): If the initialization expression is a call
630 -- to a build-in-place function, then access to the allocated object
631 -- must be passed to the function. Currently we limit such functions
632 -- to those with constrained limited result subtypes, but eventually
633 -- we plan to expand the allowed forms of functions that are treated
634 -- as build-in-place.
638 then
644 -- Actions inserted before:
645 -- Temp : constant ptr_T := new T'(Expression);
646 -- <no CW> Temp._tag := T'tag;
647 -- <CTRL> Adjust (Finalizable (Temp.all));
648 -- <CTRL> Attach_To_Final_List (Finalizable (Temp.all));
650 -- We analyze by hand the new internal allocator to avoid
651 -- any recursion and inappropriate call to Initialize
653 -- We don't want to remove side effects when the expression must be
654 -- built in place. In the case of a build-in-place function call,
655 -- that could lead to a duplication of the call, which was already
656 -- substituted for the allocator.
664 -- For a class wide allocation generate the following code:
666 -- type Equiv_Record is record ... end record;
667 -- implicit subtype CW is <Class_Wide_Subytpe>;
668 -- temp : PtrT := new CW'(CW!(expr));
673 -- Ada 2005 (AI-251): If the expression is a class-wide interface
674 -- object we generate code to move up "this" to reference the
675 -- base of the object before allocating the new object.
677 -- Note that Exp'Address is recursively expanded into a call
678 -- to Base_Address (Exp.Tag)
682 and then Tagged_Type_Expansion
683 then
684 Set_Expression
693 else
694 Set_Expression
702 -- Keep separate the management of allocators returning interfaces
706 Tmp_Node :=
710 Expression =>
714 -- Copy the Comes_From_Source flag for the allocator we just
715 -- built, since logically this allocator is a replacement of
716 -- the original allocator node. This is for proper handling of
717 -- restriction No_Implicit_Heap_Allocations.
719 Set_Comes_From_Source
727 then
728 -- Create local finalization list for access parameter
735 else
746 -- Ada 2005 (AI-251): Handle allocators whose designated type is an
747 -- interface type. In this case we use the type of the qualified
748 -- expression to allocate the object.
750 else
751 declare
755 begin
756 New_Decl :=
759 Type_Definition =>
764 Subtype_Indication =>
769 -- Inherit the final chain to ensure that the expansion of the
770 -- aggregate is correct in case of controlled types
777 -- Declare the object using the previous type declaration
780 Tmp_Node :=
784 Expression =>
788 -- Copy the Comes_From_Source flag for the allocator we just
789 -- built, since logically this allocator is a replacement of
790 -- the original allocator node. This is for proper handling
791 -- of restriction No_Implicit_Heap_Allocations.
793 Set_Comes_From_Source
801 then
802 -- Create local finalization list for access parameter
804 Flist :=
809 else
820 -- Generate an additional object containing the address of the
821 -- returned object. The type of this second object declaration
822 -- is the correct type required for the common processing that
823 -- is still performed by this subprogram. The displacement of
824 -- this pointer to reference the component associated with the
825 -- interface type will be done at the end of common processing.
827 New_Decl :=
843 -- Generate the tag assignment
845 -- Suppress the tag assignment when VM_Target because VM tags are
846 -- represented implicitly in objects.
851 -- Ada 2005 (AI-251): Suppress the tag assignment with class-wide
852 -- interface objects because in this case the tag does not change.
865 then
867 TagR :=
874 Tag_Assign :=
876 Name =>
879 Selector_Name =>
882 Expression =>
884 New_Reference_To
886 Loc)));
888 -- The previous assignment has to be done in any case
896 then
897 declare
902 begin
903 -- If it is an allocation on the secondary stack (i.e. a value
904 -- returned from a function), the object is attached on the
905 -- caller side as soon as the call is completed (see
906 -- Expand_Ctrl_Function_Call)
909 declare
911 begin
915 Object_Definition =>
921 -- Normal case, not a secondary stack allocation
923 else
926 then
927 -- Create local finalization list for access parameter
929 Flist :=
931 else
938 -- Generate an Adjust call if the object will be moved. In Ada
939 -- 2005, the object may be inherently limited, in which case
940 -- there is no Adjust procedure, and the object is built in
941 -- place. In Ada 95, the object can be limited but not
942 -- inherently limited if this allocator came from a return
943 -- statement (we're allocating the result on the secondary
944 -- stack). In that case, the object will be moved, so we _do_
945 -- want to Adjust.
947 if not Aggr_In_Place
949 then
951 Make_Adjust_Call (
952 Ref =>
954 -- An unchecked conversion is needed in the classwide
955 -- case because the designated type can be an ancestor of
956 -- the subtype mark of the allocator.
973 -- Ada 2005 (AI-251): Displace the pointer to reference the record
974 -- component containing the secondary dispatch table of the interface
975 -- type.
983 Tmp_Node :=
990 -- Copy the Comes_From_Source flag for the allocator we just built,
991 -- since logically this allocator is a replacement of the original
992 -- allocator node. This is for proper handling of restriction
993 -- No_Implicit_Heap_Allocations.
995 Set_Comes_From_Source
1006 then
1012 then
1013 -- Apply constraint to designated subtype indication
1021 -- Propagate constraint_error to enclosing allocator
1025 else
1026 -- If we have:
1027 -- type A is access T1;
1028 -- X : A := new T2'(...);
1029 -- T1 and T2 can be different subtypes, and we might need to check
1030 -- both constraints. First check against the type of the qualified
1031 -- expression.
1040 -- A check is also needed in cases where the designated subtype is
1041 -- constrained and differs from the subtype given in the qualified
1042 -- expression. Note that the check on the qualified expression does
1043 -- not allow sliding, but this check does (a relaxation from Ada 83).
1047 then
1048 Apply_Constraint_Check
1057 -- For an access to unconstrained packed array, GIGI needs to see an
1058 -- expression with a constrained subtype in order to compute the
1059 -- proper size for the allocator.
1064 then
1065 declare
1068 begin
1072 Subtype_Indication =>
1079 -- Ada 2005 (AI-318-02): If the initialization expression is a call
1080 -- to a build-in-place function, then access to the allocated object
1081 -- must be passed to the function. Currently we limit such functions
1082 -- to those with constrained limited result subtypes, but eventually
1083 -- we plan to expand the allowed forms of functions that are treated
1084 -- as build-in-place.
1088 then
1093 exception
1098 -----------------------------
1099 -- Expand_Array_Comparison --
1100 -----------------------------
1102 -- Expansion is only required in the case of array types. For the unpacked
1103 -- case, an appropriate runtime routine is called. For packed cases, and
1104 -- also in some other cases where a runtime routine cannot be called, the
1105 -- form of the expansion is:
1107 -- [body for greater_nn; boolean_expression]
1109 -- The body is built by Make_Array_Comparison_Op, and the form of the
1110 -- Boolean expression depends on the operator involved.
1126 -- True for byte addressable target
1129 -- Returns True if the length of the given operand is known to be less
1130 -- than 4. Returns False if this length is known to be four or greater
1131 -- or is not known at compile time.
1133 ------------------------
1134 -- Length_Less_Than_4 --
1135 ------------------------
1140 begin
1144 else
1145 declare
1152 begin
1155 else
1161 else
1170 -- Start of processing for Expand_Array_Comparison
1172 begin
1173 -- Deal first with unpacked case, where we can call a runtime routine
1174 -- except that we avoid this for targets for which are not addressable
1175 -- by bytes, and for the JVM/CIL, since they do not support direct
1176 -- addressing of array components.
1179 and then Byte_Addressable
1181 then
1182 -- The call we generate is:
1184 -- Compare_Array_xn[_Unaligned]
1185 -- (left'address, right'address, left'length, right'length) <op> 0
1187 -- x = U for unsigned, S for signed
1188 -- n = 8,16,32,64 for component size
1189 -- Add _Unaligned if length < 4 and component size is 8.
1190 -- <op> is the standard comparison operator
1194 or else
1196 then
1199 else
1203 else
1206 else
1214 else
1221 else
1228 else
1266 -- Cases where we cannot make runtime call
1268 -- For (a <= b) we convert to not (a > b)
1273 Right_Opnd =>
1280 -- For < the Boolean expression is
1281 -- greater__nn (op2, op1)
1286 -- Switch operands
1291 -- For (a >= b) we convert to not (a < b)
1296 Right_Opnd =>
1303 -- For > the Boolean expression is
1304 -- greater__nn (op1, op2)
1306 else
1312 Expr :=
1321 exception
1326 ---------------------------
1327 -- Expand_Array_Equality --
1328 ---------------------------
1330 -- Expand an equality function for multi-dimensional arrays. Here is an
1331 -- example of such a function for Nb_Dimension = 2
1333 -- function Enn (A : atyp; B : btyp) return boolean is
1334 -- begin
1335 -- if (A'length (1) = 0 or else A'length (2) = 0)
1336 -- and then
1337 -- (B'length (1) = 0 or else B'length (2) = 0)
1338 -- then
1339 -- return True; -- RM 4.5.2(22)
1340 -- end if;
1342 -- if A'length (1) /= B'length (1)
1343 -- or else
1344 -- A'length (2) /= B'length (2)
1345 -- then
1346 -- return False; -- RM 4.5.2(23)
1347 -- end if;
1349 -- declare
1350 -- A1 : Index_T1 := A'first (1);
1351 -- B1 : Index_T1 := B'first (1);
1352 -- begin
1353 -- loop
1354 -- declare
1355 -- A2 : Index_T2 := A'first (2);
1356 -- B2 : Index_T2 := B'first (2);
1357 -- begin
1358 -- loop
1359 -- if A (A1, A2) /= B (B1, B2) then
1360 -- return False;
1361 -- end if;
1363 -- exit when A2 = A'last (2);
1364 -- A2 := Index_T2'succ (A2);
1365 -- B2 := Index_T2'succ (B2);
1366 -- end loop;
1367 -- end;
1369 -- exit when A1 = A'last (1);
1370 -- A1 := Index_T1'succ (A1);
1371 -- B1 := Index_T1'succ (B1);
1372 -- end loop;
1373 -- end;
1375 -- return true;
1376 -- end Enn;
1378 -- Note on the formal types used (atyp and btyp). If either of the arrays
1379 -- is of a private type, we use the underlying type, and do an unchecked
1380 -- conversion of the actual. If either of the arrays has a bound depending
1381 -- on a discriminant, then we use the base type since otherwise we have an
1382 -- escaped discriminant in the function.
1384 -- If both arrays are constrained and have the same bounds, we can generate
1385 -- a loop with an explicit iteration scheme using a 'Range attribute over
1386 -- the first array.
1388 function Expand_Array_Equality
1394 is
1410 -- The parameter types to be used for the formals
1412 function Arr_Attr
1416 -- This builds the attribute reference Arr'Nam (Expr)
1419 -- Create one statement to compare corresponding components, designated
1420 -- by a full set of indices.
1423 -- Given one of the arguments, computes the appropriate type to be used
1424 -- for that argument in the corresponding function formal
1426 function Handle_One_Dimension
1429 -- This procedure returns the following code
1430 --
1431 -- declare
1432 -- Bn : Index_T := B'First (N);
1433 -- begin
1434 -- loop
1435 -- xxx
1436 -- exit when An = A'Last (N);
1437 -- An := Index_T'Succ (An)
1438 -- Bn := Index_T'Succ (Bn)
1439 -- end loop;
1440 -- end;
1441 --
1442 -- If both indices are constrained and identical, the procedure
1443 -- returns a simpler loop:
1444 --
1445 -- for An in A'Range (N) loop
1446 -- xxx
1447 -- end loop
1448 --
1449 -- N is the dimension for which we are generating a loop. Index is the
1450 -- N'th index node, whose Etype is Index_Type_n in the above code. The
1451 -- xxx statement is either the loop or declare for the next dimension
1452 -- or if this is the last dimension the comparison of corresponding
1453 -- components of the arrays.
1454 --
1455 -- The actual way the code works is to return the comparison of
1456 -- corresponding components for the N+1 call. That's neater!
1459 -- This function constructs the test for both arrays being empty
1460 -- (A'length (1) = 0 or else A'length (2) = 0 or else ...)
1461 -- and then
1462 -- (B'length (1) = 0 or else B'length (2) = 0 or else ...)
1465 -- This function constructs the test for arrays having different lengths
1466 -- in at least one index position, in which case the resulting code is:
1468 -- A'length (1) /= B'length (1)
1469 -- or else
1470 -- A'length (2) /= B'length (2)
1471 -- or else
1472 -- ...
1474 --------------
1475 -- Arr_Attr --
1476 --------------
1478 function Arr_Attr
1482 is
1483 begin
1484 return
1491 ------------------------
1492 -- Component_Equality --
1493 ------------------------
1499 begin
1500 -- if a(i1...) /= b(j1...) then return false; end if;
1502 L :=
1507 R :=
1512 Test := Expand_Composite_Equality
1515 -- If some (sub)component is an unchecked_union, the whole operation
1516 -- will raise program error.
1520 -- This node is going to be inserted at a location where a
1521 -- statement is expected: clear its Etype so analysis will set
1522 -- it to the expected Standard_Void_Type.
1527 else
1528 return
1537 ------------------
1538 -- Get_Arg_Type --
1539 ------------------
1545 begin
1551 else
1557 or else
1559 then
1571 --------------------------
1572 -- Handle_One_Dimension --
1573 ---------------------------
1575 function Handle_One_Dimension
1578 is
1580 Ltyp /= Rtyp
1582 -- If the index types are identical, and we are working with
1583 -- constrained types, then we can use the same index for both
1584 -- of the arrays.
1593 begin
1598 -- Case where we generate a loop
1604 else
1616 -- Generate guard for loop, followed by increments of indices
1620 Condition =>
1628 Expression =>
1637 Expression =>
1644 -- If separate indexes, we need a declare block for An and Bn, and a
1645 -- loop without an iteration scheme.
1648 Loop_Stm :=
1651 return
1664 Handled_Statement_Sequence =>
1668 -- If no separate indexes, return loop statement with explicit
1669 -- iteration scheme on its own
1671 else
1672 Loop_Stm :=
1675 Iteration_Scheme =>
1677 Loop_Parameter_Specification =>
1680 Discrete_Subtype_Definition =>
1686 -----------------------
1687 -- Test_Empty_Arrays --
1688 -----------------------
1697 begin
1701 Atest :=
1706 Btest :=
1715 else
1716 Alist :=
1721 Blist :=
1728 return
1734 -----------------------------
1735 -- Test_Lengths_Correspond --
1736 -----------------------------
1742 begin
1745 Rtest :=
1752 else
1753 Result :=
1763 -- Start of processing for Expand_Array_Equality
1765 begin
1769 -- For now, if the argument types are not the same, go to the base type,
1770 -- since the code assumes that the formals have the same type. This is
1771 -- fixable in future ???
1779 -- Build list of formals for function
1792 -- Build statement sequence for function
1794 Func_Body :=
1796 Specification =>
1804 Handled_Statement_Sequence =>
1812 Expression =>
1819 Expression =>
1830 -- If the array type is distinct from the type of the arguments, it
1831 -- is the full view of a private type. Apply an unchecked conversion
1832 -- to insure that analysis of the call succeeds.
1834 declare
1837 begin
1843 then
1849 then
1858 return
1864 -----------------------------
1865 -- Expand_Boolean_Operator --
1866 -----------------------------
1868 -- Note that we first get the actual subtypes of the operands, since we
1869 -- always want to deal with types that have bounds.
1874 begin
1875 -- Special case of bit packed array where both operands are known to be
1876 -- properly aligned. In this case we use an efficient run time routine
1877 -- to carry out the operation (see System.Bit_Ops).
1882 then
1887 -- For the normal non-packed case, the general expansion is to build
1888 -- function for carrying out the comparison (use Make_Boolean_Array_Op)
1889 -- and then inserting it into the tree. The original operator node is
1890 -- then rewritten as a call to this function. We also use this in the
1891 -- packed case if either operand is a possibly unaligned object.
1893 declare
1900 begin
1913 then
1918 and then
1920 then
1922 else
1928 -- Now rewrite the expression with a call
1933 Parameter_Associations =>
1934 New_List (
1935 L,
1936 Make_Type_Conversion
1944 -------------------------------
1945 -- Expand_Composite_Equality --
1946 -------------------------------
1948 -- This function is only called for comparing internal fields of composite
1949 -- types when these fields are themselves composites. This is a special
1950 -- case because it is not possible to respect normal Ada visibility rules.
1952 function Expand_Composite_Equality
1958 is
1964 begin
1967 else
1971 -- Defense against malformed private types with no completion the error
1972 -- will be diagnosed later by check_completion
1982 -- If the operand is an elementary type other than a floating-point
1983 -- type, then we can simply use the built-in block bitwise equality,
1984 -- since the predefined equality operators always apply and bitwise
1985 -- equality is fine for all these cases.
1989 then
1992 -- For composite component types, and floating-point types, use the
1993 -- expansion. This deals with tagged component types (where we use
1994 -- the applicable equality routine) and floating-point, (where we
1995 -- need to worry about negative zeroes), and also the case of any
1996 -- composite type recursively containing such fields.
1998 else
2004 -- Call the primitive operation "=" of this type
2010 -- If this is derived from an untagged private type completed with a
2011 -- tagged type, it does not have a full view, so we use the primitive
2012 -- operations of the private type. This check should no longer be
2013 -- necessary when these types receive their full views ???
2020 then
2022 else
2026 loop
2038 return
2041 Parameter_Associations =>
2042 New_List
2052 -- Inherited equality from parent type. Convert the actuals to
2053 -- match signature of operation.
2055 declare
2058 begin
2059 return
2062 Parameter_Associations =>
2067 else
2068 -- Comparison between Unchecked_Union components
2071 declare
2077 begin
2078 -- Lhs subtype
2084 -- Rhs subtype
2090 -- Lhs of the composite equality
2094 -- Since the enclosing record type can never be an
2095 -- Unchecked_Union (this code is executed for records
2096 -- that do not have variants), we may reference its
2097 -- discriminant(s).
2102 then
2103 Lhs_Discr_Val :=
2106 Selector_Name =>
2107 New_Copy (
2108 Get_Discriminant_Value (
2110 Lhs_Type,
2113 else
2115 Get_Discriminant_Value (
2117 Lhs_Type,
2121 else
2122 -- It is not possible to infer the discriminant since
2123 -- the subtype is not constrained.
2125 return
2130 -- Rhs of the composite equality
2136 then
2137 Rhs_Discr_Val :=
2140 Selector_Name =>
2141 New_Copy (
2142 Get_Discriminant_Value (
2144 Rhs_Type,
2147 else
2149 Get_Discriminant_Value (
2151 Rhs_Type,
2155 else
2156 return
2161 -- Call the TSS equality function with the inferred
2162 -- discriminant values.
2164 return
2168 Lhs,
2169 Rhs,
2170 Lhs_Discr_Val,
2171 Rhs_Discr_Val));
2174 else
2175 return
2184 -- if no TSS has been created for the type, check whether there is
2185 -- a primitive equality declared for it. If it is abstract replace
2186 -- the call with an explicit raise.
2188 declare
2191 begin
2196 return
2199 else
2200 return
2211 -- Predfined equality applies iff no user-defined primitive exists
2215 else
2219 else
2221 -- It can be a simple record or the full view of a scalar private
2227 ------------------------
2228 -- Expand_Concatenate --
2229 ------------------------
2235 -- Result type of concatenation
2238 -- Component type. Elements of this component type can appear as one
2239 -- of the operands of concatenation as well as arrays.
2242 -- Index subtype
2245 -- Index type. This is the base type of the index subtype, and is used
2246 -- for all computed bounds (which may be out of range of Istyp in the
2247 -- case of null ranges).
2250 -- This is the type we use to do arithmetic to compute the bounds and
2251 -- lengths of operands. The choice of this type is a little subtle and
2252 -- is discussed in a separate section at the start of the body code.
2255 -- Raised if concatenation is sure to raise a CE
2258 -- Reset to False if at least one operand is encountered which is known
2259 -- at compile time to be non-null. Used for handling the special case
2260 -- of setting the high bound to the last operand high bound for a null
2261 -- result, thus ensuring a proper high bound in the super-flat case.
2264 -- Number of concatenation operands including possibly null operands
2267 -- Number of operands excluding any known to be null, except that the
2268 -- last operand is always retained, in case it provides the bounds for
2269 -- a null result.
2272 -- Current operand being processed in the loop through operands. After
2273 -- this loop is complete, always contains the last operand (which is not
2274 -- the same as Operands (NN), since null operands are skipped).
2276 -- Arrays describing the operands, only the first NN entries of each
2277 -- array are set (NN < N when we exclude known null operands).
2280 -- True if length of corresponding operand known at compile time
2283 -- Set to the corresponding entry in the Opnds list (but note that null
2284 -- operands are excluded, so not all entries in the list are stored).
2287 -- Set to length of operand. Entries in this array are set only if the
2288 -- corresponding entry in Is_Fixed_Length is True.
2291 -- Set to lower bound of operand. Either an integer literal in the case
2292 -- where the bound is known at compile time, else actual lower bound.
2293 -- The operand low bound is of type Ityp.
2296 -- Set to an entity of type Natural that contains the length of an
2297 -- operand whose length is not known at compile time. Entries in this
2298 -- array are set only if the corresponding entry in Is_Fixed_Length
2299 -- is False. The entity is of type Artyp.
2302 -- The J'th entry in an expression node that represents the total length
2303 -- of operands 1 through J. It is either an integer literal node, or a
2304 -- reference to a constant entity with the right value, so it is fine
2305 -- to just do a Copy_Node to get an appropriate copy. The extra zero'th
2306 -- entry always is set to zero. The length is of type Artyp.
2309 -- A tree node representing the low bound of the result (of type Ityp).
2310 -- This is either an integer literal node, or an identifier reference to
2311 -- a constant entity initialized to the appropriate value.
2314 -- A tree node representing the high bound of the last operand. This
2315 -- need only be set if the result could be null. It is used for the
2316 -- special case of setting the right high bound for a null result.
2317 -- This is of type Ityp.
2320 -- A tree node representing the high bound of the result (of type Ityp)
2323 -- Result of the concatenation (of type Ityp)
2326 -- Collect actions to be inserted if Save_Space is False
2330 -- Set to True if we are saving generated code space by calling routines
2331 -- in packages System.Concat_n.
2334 -- Set True during generation of the assignements of operands into
2335 -- result once an operand known to be non-null has been seen.
2338 -- This function makes an N_Integer_Literal node that is returned in
2339 -- analyzed form with the type set to Artyp. Importantly this literal
2340 -- is not flagged as static, so that if we do computations with it that
2341 -- result in statically detected out of range conditions, we will not
2342 -- generate error messages but instead warning messages.
2345 -- Given a node of type Ityp, returns the corresponding value of type
2346 -- Artyp. For non-enumeration types, this is a plain integer conversion.
2347 -- For enum types, the Pos of the value is returned.
2350 -- The inverse function (uses Val in the case of enumeration types)
2352 ------------------------
2353 -- Make_Artyp_Literal --
2354 ------------------------
2358 begin
2365 --------------
2366 -- To_Artyp --
2367 --------------
2370 begin
2375 return
2381 else
2386 -------------
2387 -- To_Ityp --
2388 -------------
2391 begin
2393 return
2399 -- Case where we will do a type conversion
2401 else
2404 else
2410 -- Local Declarations
2419 begin
2420 -- Choose an appropriate computational type
2422 -- We will be doing calculations of lengths and bounds in this routine
2423 -- and computing one from the other in some cases, e.g. getting the high
2424 -- bound by adding the length-1 to the low bound.
2426 -- We can't just use the index type, or even its base type for this
2427 -- purpose for two reasons. First it might be an enumeration type which
2428 -- is not suitable fo computations of any kind, and second it may simply
2429 -- not have enough range. For example if the index type is -128..+127
2430 -- then lengths can be up to 256, which is out of range of the type.
2432 -- For enumeration types, we can simply use Standard_Integer, this is
2433 -- sufficient since the actual number of enumeration literals cannot
2434 -- possibly exceed the range of integer (remember we will be doing the
2435 -- arithmetic with POS values, not representation values).
2440 -- If index type is Positive, we use the standard unsigned type, to give
2441 -- more room on the top of the range, obviating the need for an overflow
2442 -- check when creating the upper bound. This is needed to avoid junk
2443 -- overflow checks in the common case of String types.
2445 -- ??? Disabled for now
2447 -- elsif Istyp = Standard_Positive then
2448 -- Artyp := Standard_Unsigned;
2450 -- For modular types, we use a 32-bit modular type for types whose size
2451 -- is in the range 1-31 bits. For 32-bit unsigned types, we use the
2452 -- identity type, and for larger unsigned types we use 64-bits.
2459 else
2463 -- Similar treatment for signed types
2465 else
2470 else
2475 -- Supply dummy entry at start of length array
2479 -- Go through operands setting up the above arrays
2486 -- The parent got messed up when we put the operands in a list,
2487 -- so now put back the proper parent for the saved operand.
2491 -- Set will be True when we have setup one entry in the array
2495 -- Singleton element (or character literal) case
2504 -- Set low bound of operand (no need to set Last_Opnd_High_Bound
2505 -- since we know that the result cannot be null).
2514 -- String literal case (can only occur for strings of course)
2523 -- Capture last operand high bound if result could be null
2526 Last_Opnd_High_Bound :=
2528 Left_Opnd =>
2533 -- Skip null string literal
2543 -- Set length and bounds
2552 -- All other cases
2554 else
2555 -- Check constrained case with known bounds
2558 declare
2564 begin
2565 -- Fixed length constrained array type with known at compile
2566 -- time bounds is last case of fixed length operand.
2569 and then
2571 then
2572 declare
2578 begin
2583 -- Capture last operand bound if result could be null
2586 Last_Opnd_High_Bound :=
2592 -- Exclude null length case unless last operand
2613 -- All cases where the length is not known at compile time, or the
2614 -- special case of an operand which is known to be null but has a
2615 -- lower bound other than 1 or is other than a string type.
2620 -- Capture operand bounds
2624 Prefix =>
2629 Last_Opnd_High_Bound :=
2632 Prefix =>
2637 -- Capture length of operand in entity
2649 Object_Definition =>
2652 Expression =>
2654 Prefix =>
2660 -- Set next entry in aggregate length array
2662 -- For first entry, make either integer literal for fixed length
2663 -- or a reference to the saved length for variable length.
2670 else
2675 -- If entry is fixed length and only fixed lengths so far, make
2676 -- appropriate new integer literal adding new length.
2680 then
2685 -- All other cases, construct an addition node for the length and
2686 -- create an entity initialized to this length.
2688 else
2693 else
2702 Object_Definition =>
2705 Expression =>
2717 -- If we have only skipped null operands, return the last operand
2724 -- If we have only one non-null operand, return it and we are done.
2725 -- There is one case in which this cannot be done, and that is when
2726 -- the sole operand is of the element type, in which case it must be
2727 -- converted to an array, and the easiest way of doing that is to go
2728 -- through the normal general circuit.
2732 then
2737 -- Cases where we have a real concatenation
2739 -- Next step is to find the low bound for the result array that we
2740 -- will allocate. The rules for this are in (RM 4.5.6(5-7)).
2742 -- If the ultimate ancestor of the index subtype is a constrained array
2743 -- definition, then the lower bound is that of the index subtype as
2744 -- specified by (RM 4.5.3(6)).
2746 -- The right test here is to go to the root type, and then the ultimate
2747 -- ancestor is the first subtype of this root type.
2750 Low_Bound :=
2752 Prefix =>
2756 -- If the first operand in the list has known length we know that
2757 -- the lower bound of the result is the lower bound of this operand.
2762 -- OK, we don't know the lower bound, we have to build a horrible
2763 -- expression actions node of the form
2765 -- if Cond1'Length /= 0 then
2766 -- Opnd1 low bound
2767 -- else
2768 -- if Opnd2'Length /= 0 then
2769 -- Opnd2 low bound
2770 -- else
2771 -- ...
2773 -- The nesting ends either when we hit an operand whose length is known
2774 -- at compile time, or on reaching the last operand, whose low bound we
2775 -- take unconditionally whether or not it is null. It's easiest to do
2776 -- this with a recursive procedure:
2778 else
2779 declare
2781 -- Returns the lower bound determined by operands J .. NN
2783 ---------------------
2784 -- Get_Known_Bound --
2785 ---------------------
2788 begin
2792 else
2793 return
2806 begin
2820 -- Now we can safely compute the upper bound, normally
2821 -- Low_Bound + Length - 1.
2823 High_Bound :=
2824 To_Ityp (
2827 Right_Opnd =>
2832 -- Note that calculation of the high bound may cause overflow in some
2833 -- very weird cases, so in the general case we need an overflow check on
2834 -- the high bound. We can avoid this for the common case of string types
2835 -- and other types whose index is Positive, since we chose a wider range
2836 -- for the arithmetic type.
2842 -- Handle the exceptional case where the result is null, in which case
2843 -- case the bounds come from the last operand (so that we get the proper
2844 -- bounds if the last operand is super-flat).
2847 High_Bound :=
2853 Last_Opnd_High_Bound,
2854 High_Bound));
2857 -- Here is where we insert the saved up actions
2861 -- Now we construct an array object with appropriate bounds. We mark
2862 -- the target as internal to prevent useless initialization when
2863 -- Initialize_Scalars is enabled.
2868 -- If the bound is statically known to be out of range, we do not want
2869 -- to abort, we want a warning and a runtime constraint error. Note that
2870 -- we have arranged that the result will not be treated as a static
2871 -- constant, so we won't get an illegality during this insertion.
2876 Object_Definition =>
2879 Constraint =>
2887 -- If the result of the concatenation appears as the initializing
2888 -- expression of an object declaration, we can just rename the
2889 -- result, rather than copying it.
2893 -- Catch the static out of range case now
2899 -- Now we will generate the assignments to do the actual concatenation
2901 -- There is one case in which we will not do this, namely when all the
2902 -- following conditions are met:
2904 -- The result type is Standard.String
2906 -- There are nine or fewer retained (non-null) operands
2908 -- The optimization level is -O0
2910 -- The corresponding System.Concat_n.Str_Concat_n routine is
2911 -- available in the run time.
2913 -- The debug flag gnatd.c is not set
2915 -- If all these conditions are met then we generate a call to the
2916 -- relevant concatenation routine. The purpose of this is to avoid
2917 -- undesirable code bloat at -O0.
2922 and then not Debug_Flag_Dot_C
2923 then
2924 declare
2927 RE_Str_Concat_3,
2928 RE_Str_Concat_4,
2929 RE_Str_Concat_5,
2930 RE_Str_Concat_6,
2931 RE_Str_Concat_7,
2932 RE_Str_Concat_8,
2933 RE_Str_Concat_9);
2935 begin
2937 declare
2941 begin
2956 else
2973 -- Not special case so generate the assignments
2978 declare
2987 Right_Opnd =>
2992 begin
2993 -- Singleton case, simple assignment
2999 Name =>
3006 -- Array case, slice assignment, skipped when argument is fixed
3007 -- length and known to be null.
3010 declare
3013 Name =>
3015 Prefix =>
3017 Discrete_Range =>
3022 begin
3028 -- Here if operand length is not statically known and no
3029 -- operand known to be non-null has been processed yet.
3030 -- If operand length is 0, we do not need to perform the
3031 -- assignment, and we must avoid the evaluation of the
3032 -- high bound of the slice, since it may underflow if the
3033 -- low bound is Ityp'First.
3035 Assign :=
3037 Condition =>
3039 Left_Opnd =>
3042 Then_Statements =>
3052 -- Finally we build the result, which is a reference to the array object
3060 exception
3063 -- Kill warning generated for the declaration of the static out of
3064 -- range high bound, and instead generate a Constraint_Error with
3065 -- an appropriate specific message.
3068 Apply_Compile_Time_Constraint_Error
3072 -- Set_Etype (Cnode, Atyp);
3075 ------------------------
3076 -- Expand_N_Allocator --
3077 ------------------------
3089 -- Generate finalization calls for all nested coextensions of N. This
3090 -- routine may allocate list controllers if necessary.
3093 -- Static coextensions have the same lifetime as the entity they
3094 -- constrain. Such occurrences can be rewritten as aliased objects
3095 -- and their unrestricted access used instead of the coextension.
3098 -- Given a constrained array type E, returns a node representing the
3099 -- code to compute the size in storage elements for the given type.
3100 -- This is done without using the attribute (which malfunctions for
3101 -- large sizes ???)
3103 ---------------------------------------
3104 -- Complete_Coextension_Finalization --
3105 ---------------------------------------
3114 -- Determine whether node N is part of a return statement
3117 -- Determine whether node N is a subtype indicator allocator which
3118 -- acts a coextension. Such coextensions need initialization.
3120 -------------------------------
3121 -- Inside_A_Return_Statement --
3122 -------------------------------
3127 begin
3130 if Nkind_In
3132 then
3135 -- Stop the traversal when we reach a subprogram body
3147 -------------------------------
3148 -- Needs_Initialization_Call --
3149 -------------------------------
3154 begin
3158 N_Object_Declaration
3159 then
3162 return
3166 N_Qualified_Expression;
3172 -- Start of processing for Complete_Coextension_Finalization
3174 begin
3175 -- When a coextension root is inside a return statement, we need to
3176 -- use the finalization chain of the function's scope. This does not
3177 -- apply for controlled named access types because in those cases we
3178 -- can use the finalization chain of the type itself.
3181 and then
3183 or else
3186 then
3187 declare
3192 begin
3198 -- Retrieve the declaration of the body
3200 Decl :=
3201 Parent
3202 (Parent
3210 -- Push the scope of the function body since we are inserting
3211 -- the list before the body, but we are currently in the body
3212 -- itself. Override the finalization list of PtrT since the
3213 -- finalization context is now different.
3217 Pop_Scope;
3220 -- The root allocator may not be controlled, but it still needs a
3221 -- finalization list for all nested coextensions.
3227 Flist :=
3229 Prefix =>
3231 Selector_Name =>
3238 -- Generate:
3239 -- typ! (coext.all)
3242 Ref :=
3245 Expression =>
3248 else
3252 -- No initialization call if not allowed
3258 -- Generate:
3259 -- initialize (Ref)
3260 -- attach_to_final_list (Ref, Flist, 2)
3264 Make_Init_Call (
3270 -- Generate:
3271 -- attach_to_final_list (Ref, Flist, 2)
3273 else
3275 Make_Attach_Call (
3286 -------------------------
3287 -- Rewrite_Coextension --
3288 -------------------------
3293 -- Generate:
3294 -- Cnn : aliased Etyp;
3300 Object_Definition =>
3304 begin
3309 -- Find the proper insertion node for the declaration
3330 ------------------------------
3331 -- Size_In_Storage_Elements --
3332 ------------------------------
3335 begin
3336 -- Logically this just returns E'Max_Size_In_Storage_Elements.
3337 -- However, the reason for the existence of this function is
3338 -- to construct a test for sizes too large, which means near the
3339 -- 32-bit limit on a 32-bit machine, and precisely the trouble
3340 -- is that we get overflows when sizes are greater than 2**31.
3342 -- So what we end up doing for array types is to use the expression:
3344 -- number-of-elements * component_type'Max_Size_In_Storage_Elements
3346 -- which avoids this problem. All this is a big bogus, but it does
3347 -- mean we catch common cases of trying to allocate arrays that
3348 -- are too large, and which in the absence of a check results in
3349 -- undetected chaos ???
3351 declare
3355 begin
3357 Len :=
3367 else
3368 Res :=
3375 return
3378 Right_Opnd =>
3385 -- Start of processing for Expand_N_Allocator
3387 begin
3388 -- RM E.2.3(22). We enforce that the expected type of an allocator
3389 -- shall not be a remote access-to-class-wide-limited-private type
3391 -- Why is this being done at expansion time, seems clearly wrong ???
3395 -- Set the Storage Pool
3408 else
3414 -- Under certain circumstances we can replace an allocator by an access
3415 -- to statically allocated storage. The conditions, as noted in AARM
3416 -- 3.10 (10c) are as follows:
3418 -- Size and initial value is known at compile time
3419 -- Access type is access-to-constant
3421 -- The allocator is not part of a constraint on a record component,
3422 -- because in that case the inserted actions are delayed until the
3423 -- record declaration is fully analyzed, which is too late for the
3424 -- analysis of the rewritten allocator.
3432 then
3433 -- Here we can do the optimization. For the allocator
3435 -- new x'(y)
3437 -- We insert an object declaration
3439 -- Tnn : aliased x := y;
3441 -- and replace the allocator by Tnn'Unrestricted_Access. Tnn is
3442 -- marked as requiring static allocation.
3447 -- If context is constrained, use constrained subtype directly,
3448 -- so that the constant is not labelled as having a nominally
3449 -- unconstrained subtype.
3470 -- We set the variable as statically allocated, since we don't want
3471 -- it going on the stack of the current procedure!
3477 -- Same if the allocator is an access discriminant for a local object:
3478 -- instead of an allocator we create a local value and constrain the
3479 -- the enclosing object with the corresponding access attribute.
3486 -- The current allocator creates an object which may contain nested
3487 -- coextensions. Use the current allocator's finalization list to
3488 -- generate finalization call for all nested coextensions.
3491 Complete_Coextension_Finalization;
3494 -- Check for size too large, we do this because the back end misses
3495 -- proper checks here and can generate rubbish allocation calls when
3496 -- we are near the limit. We only do this for the 32-bit address case
3497 -- since that is from a practical point of view where we see a problem.
3503 then
3504 -- The check we want to generate should look like
3506 -- if Etyp'Max_Size_In_Storage_Elements > 3.5 gigabytes then
3507 -- raise Storage_Error;
3508 -- end if;
3510 -- where 3.5 gigabytes is a constant large enough to accomodate any
3511 -- reasonable request for. But we can't do it this way because at
3512 -- least at the moment we don't compute this attribute right, and
3513 -- can silently give wrong results when the result gets large. Since
3514 -- this is all about large results, that's bad, so instead we only
3515 -- apply the check for constrained arrays, and manually compute the
3516 -- value of the attribute ???
3521 Condition =>
3524 Right_Opnd =>
3531 -- Handle case of qualified expression (other than optimization above)
3532 -- First apply constraint checks, because the bounds or discriminants
3533 -- in the aggregate might not match the subtype mark in the allocator.
3536 Apply_Constraint_Check
3543 -- If the allocator is for a type which requires initialization, and
3544 -- there is no initial value (i.e. operand is a subtype indication
3545 -- rather than a qualified expression), then we must generate a call to
3546 -- the initialization routine using an expressions action node:
3548 -- [Pnnn : constant ptr_T := new (T); Init (Pnnn.all,...); Pnnn]
3550 -- Here ptr_T is the pointer type for the allocator, and T is the
3551 -- subtype of the allocator. A special case arises if the designated
3552 -- type of the access type is a task or contains tasks. In this case
3553 -- the call to Init (Temp.all ...) is replaced by code that ensures
3554 -- that tasks get activated (see Exp_Ch9.Build_Task_Allocate_Block
3555 -- for details). In addition, if the type T is a task T, then the
3556 -- first argument to Init must be converted to the task record type.
3558 declare
3571 begin
3575 -- Case of no initialization procedure present
3579 -- Case of simple initialization required
3593 -- No initialization required
3595 else
3599 -- Case of initialization procedure present, must be called
3601 else
3609 -- Construct argument list for the initialization routine call
3611 Arg1 :=
3617 -- The initialization procedure expects a specific type. if the
3618 -- context is access to class wide, indicate that the object
3619 -- being allocated has the right specific type.
3625 -- If designated type is a concurrent type or if it is private
3626 -- type whose definition is a concurrent type, the first
3627 -- argument in the Init routine has to be unchecked conversion
3628 -- to the corresponding record type. If the designated type is
3629 -- a derived type, we also convert the argument to its root
3630 -- type.
3633 Arg1 :=
3639 then
3640 Arg1 :=
3641 Unchecked_Convert_To
3645 declare
3647 begin
3655 -- For the task case, pass the Master_Id of the access type as
3656 -- the value of the _Master parameter, and _Chain as the value
3657 -- of the _Chain parameter (_Chain will be defined as part of
3658 -- the generated code for the allocator).
3660 -- In Ada 2005, the context may be a function that returns an
3661 -- anonymous access type. In that case the Master_Id has been
3662 -- created when expanding the function declaration.
3667 -- If we have a non-library level task with restriction
3668 -- No_Task_Hierarchy set, then no point in expanding.
3672 then
3676 -- The designated type was an incomplete type, and the
3677 -- access type did not get expanded. Salvage it now.
3681 Expand_N_Full_Type_Declaration
3686 -- If the context of the allocator is a declaration or an
3687 -- assignment, we can generate a meaningful image for it,
3688 -- even though subsequent assignments might remove the
3689 -- connection between task and entity. We build this image
3690 -- when the left-hand side is a simple variable, a simple
3691 -- indexed assignment or a simple selected component.
3694 declare
3697 begin
3699 Decls :=
3700 Build_Task_Image_Decls
3702 New_Occurrence_Of
3705 elsif Nkind_In
3708 then
3709 Decls :=
3710 Build_Task_Image_Decls
3712 else
3718 Decls :=
3719 Build_Task_Image_Decls
3722 else
3729 else
3731 New_Reference_To
3741 -- Has_Task is false, Decls not used
3743 else
3747 -- Add discriminants if discriminated type
3749 declare
3753 begin
3761 then
3768 -- If the allocated object will be constrained by the
3769 -- default values for discriminants, then build a subtype
3770 -- with those defaults, and change the allocated subtype
3771 -- to that. Note that this happens in fewer cases in Ada
3772 -- 2005 (AI-363).
3778 or else
3780 then
3790 -- AI-416: when the discriminant constraint is an
3791 -- anonymous access type make sure an accessibility
3792 -- check is inserted if necessary (3.10.2(22.q/2))
3795 and then
3797 then
3798 Apply_Accessibility_Check
3807 -- We set the allocator as analyzed so that when we analyze the
3808 -- expression actions node, we do not get an unwanted recursive
3809 -- expansion of the allocator expression.
3814 -- Here is the transformation:
3815 -- input: new T
3816 -- output: Temp : constant ptr_T := new T;
3817 -- Init (Temp.all, ...);
3818 -- <CTRL> Attach_To_Final_List (Finalizable (Temp.all));
3819 -- <CTRL> Initialize (Finalizable (Temp.all));
3821 -- Here ptr_T is the pointer type for the allocator, and is the
3822 -- subtype of the allocator.
3824 Temp_Decl :=
3834 -- If the designated type is a task type or contains tasks,
3835 -- create block to activate created tasks, and insert
3836 -- declaration for Task_Image variable ahead of call.
3839 declare
3842 begin
3849 else
3858 -- Postpone the generation of a finalization call for the
3859 -- current allocator if it acts as a coextension.
3868 else
3869 Flist :=
3872 -- Anonymous access types created for access parameters
3873 -- are attached to an explicitly constructed controller,
3874 -- which ensures that they can be finalized properly,
3875 -- even if their deallocation might not happen. The list
3876 -- associated with the controller is doubly-linked. For
3877 -- other anonymous access types, the object may end up
3878 -- on the global final list which is singly-linked.
3879 -- Work needed for access discriminants in Ada 2005 ???
3883 else
3888 Make_Init_Call (
3903 -- Ada 2005 (AI-251): If the allocator is for a class-wide interface
3904 -- object that has been rewritten as a reference, we displace "this"
3905 -- to reference properly its secondary dispatch table.
3909 then
3913 exception
3918 -----------------------
3919 -- Expand_N_And_Then --
3920 -----------------------
3925 ------------------------------
3926 -- Expand_N_Case_Expression --
3927 ------------------------------
3940 begin
3941 -- We expand
3943 -- case X is when A => AX, when B => BX ...
3945 -- to
3947 -- do
3948 -- Tnn : typ;
3949 -- case X is
3950 -- when A =>
3951 -- Tnn := AX;
3952 -- when B =>
3953 -- Tnn := BX;
3954 -- ...
3955 -- end case;
3956 -- in Tnn end;
3958 -- However, this expansion is wrong for limited types, and also
3959 -- wrong for unconstrained types (since the bounds may not be the
3960 -- same in all branches). Furthermore it involves an extra copy
3961 -- for large objects. So we take care of this by using the following
3962 -- modified expansion for non-scalar types:
3964 -- do
3965 -- type Pnn is access all typ;
3966 -- Tnn : Pnn;
3967 -- case X is
3968 -- when A =>
3969 -- T := AX'Unrestricted_Access;
3970 -- when B =>
3971 -- T := BX'Unrestricted_Access;
3972 -- ...
3973 -- end case;
3974 -- in Tnn.all end;
3976 Cstmt :=
3983 -- Scalar case
3988 else
3993 Type_Definition =>
3996 Subtype_Indication =>
4007 -- Now process the alternatives
4011 declare
4015 begin
4017 Aexp :=
4023 Append_To
4038 -- Construct and return final expression with actions
4042 else
4043 Fexp :=
4056 -------------------------------------
4057 -- Expand_N_Conditional_Expression --
4058 -------------------------------------
4060 -- Deal with limited types and expression actions
4077 begin
4078 -- Fold at compile time if condition known. We have already folded
4079 -- static conditional expressions, but it is possible to fold any
4080 -- case in which the condition is known at compile time, even though
4081 -- the result is non-static.
4083 -- Note that we don't do the fold of such cases in Sem_Elab because
4084 -- it can cause infinite loops with the expander adding a conditional
4085 -- expression, and Sem_Elab circuitry removing it repeatedly.
4091 else
4100 -- If we are not allowed to use Expression_With_Actions, just
4101 -- skip the optimization, it is not critical for correctness.
4113 else
4117 -- Note that the result is never static (legitimate cases of static
4118 -- conditional expressions were folded in Sem_Eval).
4126 -- If the type is limited or unconstrained, we expand as follows to
4127 -- avoid any possibility of improper copies.
4129 -- Note: it may be possible to avoid this special processing if the
4130 -- back end uses its own mechanisms for handling by-reference types ???
4132 -- type Ptr is access all Typ;
4133 -- Cnn : Ptr;
4134 -- if cond then
4135 -- <<then actions>>
4136 -- Cnn := then-expr'Unrestricted_Access;
4137 -- else
4138 -- <<else actions>>
4139 -- Cnn := else-expr'Unrestricted_Access;
4140 -- end if;
4142 -- and replace the conditional expresion by a reference to Cnn.all.
4144 -- This special case can be skipped if the back end handles limited
4145 -- types properly and ensures that no incorrect copies are made.
4148 and then not Back_End_Handles_Limited_Types
4149 then
4152 P_Decl :=
4155 Type_Definition =>
4158 Subtype_Indication =>
4163 Decl :=
4166 Object_Definition =>
4169 New_If :=
4176 Expression =>
4184 Expression =>
4189 New_N :=
4193 -- For other types, we only need to expand if there are other actions
4194 -- associated with either branch.
4198 -- We have two approaches to handling this. If we are allowed to use
4199 -- N_Expression_With_Actions, then we can just wrap the actions into
4200 -- the appropriate expression.
4223 -- if we can't use N_Expression_With_Actions nodes, then we insert
4224 -- the following sequence of actions (using Insert_Actions):
4226 -- Cnn : typ;
4227 -- if cond then
4228 -- <<then actions>>
4229 -- Cnn := then-expr;
4230 -- else
4231 -- <<else actions>>
4232 -- Cnn := else-expr
4233 -- end if;
4235 -- and replace the conditional expression by a reference to Cnn
4237 else
4240 Decl :=
4245 New_If :=
4265 -- If no actions then no expansion needed, gigi will handle it using
4266 -- the same approach as a C conditional expression.
4268 else
4272 -- Fall through here for either the limited expansion, or the case of
4273 -- inserting actions for non-limited types. In both these cases, we must
4274 -- move the SLOC of the parent If statement to the newly created one and
4275 -- change it to the SLOC of the expression which, after expansion, will
4276 -- correspond to what is being evaluated.
4280 then
4285 -- Make sure Then_Actions and Else_Actions are appropriately moved
4286 -- to the new if statement.
4289 Insert_List_Before
4294 Insert_List_Before
4304 -----------------------------------
4305 -- Expand_N_Explicit_Dereference --
4306 -----------------------------------
4309 begin
4310 -- Insert explicit dereference call for the checked storage pool case
4315 -----------------
4316 -- Expand_N_In --
4317 -----------------
4327 -- For each disjunct we create a simple equality or membership test.
4328 -- The whole membership is rewritten as a short-circuit disjunction.
4330 ---------------------------
4331 -- Expand_Set_Membership --
4332 ---------------------------
4339 -- If the alternative is a subtype mark, create a simple membership
4340 -- test. Otherwise create an equality test for it.
4342 ---------------
4343 -- Make_Cond --
4344 ---------------
4351 begin
4354 then
4355 Cond :=
4359 else
4368 -- Start of proessing for Expand_N_In
4370 begin
4376 Res :=
4388 -- Replaces node N by Lop'Valid. This is done when we have an explicit
4389 -- test for the left operand being in range of its subtype.
4391 ----------------------------
4392 -- Substitute_Valid_Check --
4393 ----------------------------
4396 begin
4405 Error_Msg_N -- CODEFIX
4410 -- Start of processing for Expand_N_In
4412 begin
4415 Expand_Set_Membership;
4419 -- Check case of explicit test for an expression in range of its
4420 -- subtype. This is suspicious usage and we replace it with a 'Valid
4421 -- test and give a warning. For floating point types however, this is a
4422 -- standard way to check for finite numbers, and using 'Valid vould
4423 -- typically be a pessimization.
4431 then
4432 Substitute_Valid_Check;
4436 -- Do validity check on operands
4443 -- Case of explicit range
4446 declare
4459 Constant_Condition_Warnings
4462 -- This must be true for any of the optimization warnings, we
4463 -- clearly want to give them only for source with the flag on. We
4464 -- also skip these warnings in an instance since it may be the
4465 -- case that different instantiations have different ranges.
4468 Warn1
4471 -- For the case where only one bound warning is elided, we also
4472 -- insist on an explicit range and an integer type. The reason is
4473 -- that the use of enumeration ranges including an end point is
4474 -- common, as is the use of a subtype name, one of whose bounds is
4475 -- the same as the type of the expression.
4477 begin
4478 -- If test is explicit x'first .. x'last, replace by valid check
4491 then
4492 Substitute_Valid_Check;
4496 -- If bounds of type are known at compile time, and the end points
4497 -- are known at compile time and identical, this is another case
4498 -- for substituting a valid test. We only do this for discrete
4499 -- types, since it won't arise in practice for float types.
4510 -- Kill warnings in instances, since they may be cases where we
4511 -- have a test in the generic that makes sense with some types
4512 -- and not with other types.
4514 and then not In_Instance
4515 then
4516 Substitute_Valid_Check;
4520 -- If we have an explicit range, do a bit of optimization based on
4521 -- range analysis (we may be able to kill one or both checks).
4526 -- If either check is known to fail, replace result by False since
4527 -- the other check does not matter. Preserve the static flag for
4528 -- legality checks, because we are constant-folding beyond RM 4.9.
4542 -- If both checks are known to succeed, replace result by True,
4543 -- since we know we are in range.
4557 -- If lower bound check succeeds and upper bound check is not
4558 -- known to succeed or fail, then replace the range check with
4559 -- a comparison against the upper bound.
4575 -- If upper bound check succeeds and lower bound check is not
4576 -- known to succeed or fail, then replace the range check with
4577 -- a comparison against the lower bound.
4594 -- We couldn't optimize away the range check, but there is one
4595 -- more issue. If we are checking constant conditionals, then we
4596 -- see if we can determine the outcome assuming everything is
4597 -- valid, and if so give an appropriate warning.
4603 -- Result is out of range for valid value
4606 Error_Msg_N
4609 -- Result is in range for valid value
4612 Error_Msg_N
4615 -- Lower bound check succeeds if value is valid
4618 Error_Msg_N
4621 -- Upper bound check succeeds if value is valid
4624 Error_Msg_N
4630 -- For all other cases of an explicit range, nothing to be done
4634 -- Here right operand is a subtype mark
4636 else
4637 declare
4645 begin
4648 -- For tagged type, do tagged membership operation
4652 -- No expansion will be performed when VM_Target, as the VM
4653 -- back-ends will handle the membership tests directly (tags
4654 -- are not explicitly represented in Java objects, so the
4655 -- normal tagged membership expansion is not what we want).
4662 -- Update decoration of relocated node referenced by the
4663 -- SCIL node.
4672 -- If type is scalar type, rewrite as x in t'first .. t'last.
4673 -- This reason we do this is that the bounds may have the wrong
4674 -- type if they come from the original type definition. Also this
4675 -- way we get all the processing above for an explicit range.
4680 Low_Bound =>
4685 High_Bound =>
4692 -- Ada 2005 (AI-216): Program_Error is raised when evaluating
4693 -- a membership test if the subtype mark denotes a constrained
4694 -- Unchecked_Union subtype and the expression lacks inferable
4695 -- discriminants.
4700 then
4705 -- Prevent Gigi from generating incorrect code by rewriting the
4706 -- test as False.
4712 -- Here we have a non-scalar type
4722 -- For the constrained array case, we have to check the subscripts
4723 -- for an exact match if the lengths are non-zero (the lengths
4724 -- must match in any case).
4728 function Build_Attribute_Reference
4732 -- Build attribute reference E'Nam (Dim)
4734 -------------------------------
4735 -- Build_Attribute_Reference --
4736 -------------------------------
4738 function Build_Attribute_Reference
4742 is
4743 begin
4744 return
4752 -- Start of processing for Check_Subscripts
4754 begin
4758 Left_Opnd =>
4759 Build_Attribute_Reference
4762 Right_Opnd =>
4763 Build_Attribute_Reference
4768 Left_Opnd =>
4769 Build_Attribute_Reference
4772 Right_Opnd =>
4773 Build_Attribute_Reference
4778 Cond :=
4780 Left_Opnd =>
4791 -- These are the cases where constraint checks may be required,
4792 -- e.g. records with possible discriminants
4794 else
4795 -- Expand the test into a series of discriminant comparisons.
4796 -- The expression that is built is the negation of the one that
4797 -- is used for checking discriminant constraints.
4807 Left_Opnd =>
4814 else
4825 --------------------------------
4826 -- Expand_N_Indexed_Component --
4827 --------------------------------
4835 begin
4836 -- A special optimization, if we have an indexed component that is
4837 -- selecting from a slice, then we can eliminate the slice, since, for
4838 -- example, x (i .. j)(k) is identical to x(k). The only difference is
4839 -- the range check required by the slice. The range check for the slice
4840 -- itself has already been generated. The range check for the
4841 -- subscripting operation is ensured by converting the subject to
4842 -- the subtype of the slice.
4844 -- This optimization not only generates better code, avoiding slice
4845 -- messing especially in the packed case, but more importantly bypasses
4846 -- some problems in handling this peculiar case, for example, the issue
4847 -- of dealing specially with object renamings.
4854 Convert_To
4861 -- Ada 2005 (AI-318-02): If the prefix is a call to a build-in-place
4862 -- function, then additional actuals must be passed.
4866 then
4870 -- If the prefix is an access type, then we unconditionally rewrite if
4871 -- as an explicit dereference. This simplifies processing for several
4872 -- cases, including packed array cases and certain cases in which checks
4873 -- must be generated. We used to try to do this only when it was
4874 -- necessary, but it cleans up the code to do it all the time.
4881 -- Generate index and validity checks
4889 -- All done for the non-packed case
4895 -- For packed arrays that are not bit-packed (i.e. the case of an array
4896 -- with one or more index types with a non-contiguous enumeration type),
4897 -- we can always use the normal packed element get circuit.
4904 -- For a reference to a component of a bit packed array, we have to
4905 -- convert it to a reference to the corresponding Packed_Array_Type.
4906 -- We only want to do this for simple references, and not for:
4908 -- Left side of assignment, or prefix of left side of assignment, or
4909 -- prefix of the prefix, to handle packed arrays of packed arrays,
4910 -- This case is handled in Exp_Ch5.Expand_N_Assignment_Statement
4912 -- Renaming objects in renaming associations
4913 -- This case is handled when a use of the renamed variable occurs
4915 -- Actual parameters for a procedure call
4916 -- This case is handled in Exp_Ch6.Expand_Actuals
4918 -- The second expression in a 'Read attribute reference
4920 -- The prefix of an address or bit or size attribute reference
4922 -- The following circuit detects these exceptions
4924 declare
4928 begin
4929 loop
4934 N_Procedure_Call_Statement)
4936 and then
4938 then
4943 or else
4945 or else
4948 then
4953 then
4956 -- If the expression is an index of an indexed component, it must
4957 -- be expanded regardless of context.
4961 then
4967 then
4973 then
4978 then
4981 else
4986 -- Keep looking up tree for unchecked expression, or if we are the
4987 -- prefix of a possible assignment left side.
4995 ---------------------
4996 -- Expand_N_Not_In --
4997 ---------------------
4999 -- Replace a not in b by not (a in b) so that the expansions for (a in b)
5000 -- can be done. This avoids needing to duplicate this expansion code.
5007 begin
5010 Right_Opnd =>
5015 -- If this is a set membership, preserve list of alternatives
5019 -- We want this to appear as coming from source if original does (see
5020 -- transformations in Expand_N_In).
5025 -- Now analyze transformed node
5030 -------------------
5031 -- Expand_N_Null --
5032 -------------------
5034 -- The only replacement required is for the case of a null of type that is
5035 -- an access to protected subprogram. We represent such access values as a
5036 -- record, and so we must replace the occurrence of null by the equivalent
5037 -- record (with a null address and a null pointer in it), so that the
5038 -- backend creates the proper value.
5045 begin
5047 Agg :=
5056 -- For subsequent semantic analysis, the node must retain its type.
5057 -- Gigi in any case replaces this type by the corresponding record
5058 -- type before processing the node.
5063 exception
5068 ---------------------
5069 -- Expand_N_Op_Abs --
5070 ---------------------
5076 begin
5079 -- Deal with software overflow checking
5081 if not Backend_Overflow_Checks_On_Target
5084 then
5085 -- The only case to worry about is when the argument is equal to the
5086 -- largest negative number, so what we do is to insert the check:
5088 -- [constraint_error when Expr = typ'Base'First]
5090 -- with the usual Duplicate_Subexpr use coding for expr
5094 Condition =>
5097 Right_Opnd =>
5099 Prefix =>
5105 -- Vax floating-point types case
5112 ---------------------
5113 -- Expand_N_Op_Add --
5114 ---------------------
5119 begin
5122 -- N + 0 = 0 + N = N for integer types
5127 then
5133 then
5139 -- Arithmetic overflow checks for signed integer/fixed point types
5143 then
5147 -- Vax floating-point types case
5154 ---------------------
5155 -- Expand_N_Op_And --
5156 ---------------------
5161 begin
5169 -- Replace AND by AND THEN if Short_Circuit_And_Or active and the
5170 -- type is standard Boolean (do not mess with AND that uses a non-
5171 -- standard Boolean type, because something strange is going on).
5180 -- Otherwise, adjust conditions
5182 else
5191 ------------------------
5192 -- Expand_N_Op_Concat --
5193 ------------------------
5197 -- List of operands to be concatenated
5200 -- Node which is to be replaced by the result of concatenating the nodes
5201 -- in the list Opnds.
5203 begin
5204 -- Ensure validity of both operands
5208 -- If we are the left operand of a concatenation higher up the tree,
5209 -- then do nothing for now, since we want to deal with a series of
5210 -- concatenations as a unit.
5214 then
5218 -- We get here with a concatenation whose left operand may be a
5219 -- concatenation itself with a consistent type. We need to process
5220 -- these concatenation operands from left to right, which means
5221 -- from the deepest node in the tree to the highest node.
5228 -- Now Cnode is the deepest concatenation, and its parents are the
5229 -- concatenation nodes above, so now we process bottom up, doing the
5230 -- operations. We gather a string that is as long as possible up to five
5231 -- operands.
5233 -- The outer loop runs more than once if more than one concatenation
5234 -- type is involved.
5240 -- The inner loop gathers concatenation operands
5245 loop
5257 ------------------------
5258 -- Expand_N_Op_Divide --
5259 ------------------------
5269 and then
5273 begin
5280 -- N / 1 = N for integer types
5287 -- Convert x / 2 ** y to Shift_Right (x, y). Note that the fact that
5288 -- Is_Power_Of_2_For_Shift is set means that we know that our left
5289 -- operand is an unsigned integer, as required for this to work.
5294 -- We cannot do this transformation in configurable run time mode if we
5295 -- have 64-bit integers and long shifts are not available.
5297 and then
5300 then
5304 Right_Opnd =>
5310 -- Do required fixup of universal fixed operation
5317 -- Divisions with fixed-point results
5321 -- No special processing if Treat_Fixed_As_Integer is set, since
5322 -- from a semantic point of view such operations are simply integer
5323 -- operations and will be treated that way.
5328 else
5333 -- Other cases of division of fixed-point operands. Again we exclude the
5334 -- case where Treat_Fixed_As_Integer is set.
5339 then
5342 else
5347 -- Mixed-mode operations can appear in a non-static universal context,
5348 -- in which case the integer argument must be converted explicitly.
5352 then
5360 then
5366 -- Non-fixed point cases, do integer zero divide and overflow checks
5371 -- Check for 64-bit division available, or long shifts if the divisor
5372 -- is a small power of 2 (since such divides will be converted into
5373 -- long shifts).
5376 and then not Support_64_Bit_Divides_On_Target
5377 and then
5379 or else not Support_Long_Shifts_On_Target
5386 then
5390 -- Deal with Vax_Float
5398 --------------------
5399 -- Expand_N_Op_Eq --
5400 --------------------
5415 -- If a constructed equality exists for the type or for its parent,
5416 -- build and analyze call, adding conversions if the operation is
5417 -- inherited.
5420 -- Determines whether a type has a subcomponent of an unconstrained
5421 -- Unchecked_Union subtype. Typ is a record type.
5423 -------------------------
5424 -- Build_Equality_Call --
5425 -------------------------
5432 begin
5435 then
5440 -- If we have an Unchecked_Union, we need to add the inferred
5441 -- discriminant values as actuals in the function call. At this
5442 -- point, the expansion has determined that both operands have
5443 -- inferable discriminants.
5446 declare
5452 begin
5453 -- Per-object constrained selected components require special
5454 -- attention. If the enclosing scope of the component is an
5455 -- Unchecked_Union, we cannot reference its discriminants
5456 -- directly. This is why we use the two extra parameters of
5457 -- the equality function of the enclosing Unchecked_Union.
5459 -- type UU_Type (Discr : Integer := 0) is
5460 -- . . .
5461 -- end record;
5462 -- pragma Unchecked_Union (UU_Type);
5464 -- 1. Unchecked_Union enclosing record:
5466 -- type Enclosing_UU_Type (Discr : Integer := 0) is record
5467 -- . . .
5468 -- Comp : UU_Type (Discr);
5469 -- . . .
5470 -- end Enclosing_UU_Type;
5471 -- pragma Unchecked_Union (Enclosing_UU_Type);
5473 -- Obj1 : Enclosing_UU_Type;
5474 -- Obj2 : Enclosing_UU_Type (1);
5476 -- [. . .] Obj1 = Obj2 [. . .]
5478 -- Generated code:
5480 -- if not (uu_typeEQ (obj1.comp, obj2.comp, a, b)) then
5482 -- A and B are the formal parameters of the equality function
5483 -- of Enclosing_UU_Type. The function always has two extra
5484 -- formals to capture the inferred discriminant values.
5486 -- 2. Non-Unchecked_Union enclosing record:
5488 -- type
5489 -- Enclosing_Non_UU_Type (Discr : Integer := 0)
5490 -- is record
5491 -- . . .
5492 -- Comp : UU_Type (Discr);
5493 -- . . .
5494 -- end Enclosing_Non_UU_Type;
5496 -- Obj1 : Enclosing_Non_UU_Type;
5497 -- Obj2 : Enclosing_Non_UU_Type (1);
5499 -- ... Obj1 = Obj2 ...
5501 -- Generated code:
5503 -- if not (uu_typeEQ (obj1.comp, obj2.comp,
5504 -- obj1.discr, obj2.discr)) then
5506 -- In this case we can directly reference the discriminants of
5507 -- the enclosing record.
5509 -- Lhs of equality
5512 and then Has_Per_Object_Constraint
5514 then
5515 -- Enclosing record is an Unchecked_Union, use formal A
5519 then
5520 Lhs_Discr_Val :=
5524 -- Enclosing record is of a non-Unchecked_Union type, it is
5525 -- possible to reference the discriminant.
5527 else
5528 Lhs_Discr_Val :=
5531 Selector_Name =>
5532 New_Copy
5533 (Get_Discriminant_Value
5535 Lhs_Type,
5539 -- Comment needed here ???
5541 else
5542 -- Infer the discriminant value
5544 Lhs_Discr_Val :=
5545 New_Copy
5546 (Get_Discriminant_Value
5548 Lhs_Type,
5552 -- Rhs of equality
5555 and then Has_Per_Object_Constraint
5557 then
5558 if Is_Unchecked_Union
5560 then
5561 Rhs_Discr_Val :=
5565 else
5566 Rhs_Discr_Val :=
5569 Selector_Name =>
5572 Rhs_Type,
5576 else
5577 Rhs_Discr_Val :=
5580 Rhs_Type,
5589 L_Exp,
5590 R_Exp,
5591 Lhs_Discr_Val,
5592 Rhs_Discr_Val)));
5595 -- Normal case, not an unchecked union
5597 else
5607 ------------------------------------
5608 -- Has_Unconstrained_UU_Component --
5609 ------------------------------------
5611 function Has_Unconstrained_UU_Component
5613 is
5619 function Component_Is_Unconstrained_UU
5621 -- Determines whether the subtype of the component is an
5622 -- unconstrained Unchecked_Union.
5624 function Variant_Is_Unconstrained_UU
5626 -- Determines whether a component of the variant has an unconstrained
5627 -- Unchecked_Union subtype.
5629 -----------------------------------
5630 -- Component_Is_Unconstrained_UU --
5631 -----------------------------------
5633 function Component_Is_Unconstrained_UU
5635 is
5636 begin
5641 declare
5645 begin
5646 -- Unconstrained nominal type. In the case of a constraint
5647 -- present, the node kind would have been N_Subtype_Indication.
5657 ---------------------------------
5658 -- Variant_Is_Unconstrained_UU --
5659 ---------------------------------
5661 function Variant_Is_Unconstrained_UU
5663 is
5666 begin
5671 -- We only need to test one component
5673 declare
5676 begin
5686 -- None of the components withing the variant were of
5687 -- unconstrained Unchecked_Union type.
5692 -- Start of processing for Has_Unconstrained_UU_Component
5694 begin
5702 -- Inspect available components
5705 declare
5708 begin
5711 -- One component is sufficient
5722 -- Inspect available components withing variants
5725 declare
5728 begin
5731 -- One component within a variant is sufficient
5742 -- Neither the available components, nor the components inside the
5743 -- variant parts were of an unconstrained Unchecked_Union subtype.
5748 -- Start of processing for Expand_N_Op_Eq
5750 begin
5757 else
5761 -- It may happen in error situations that the underlying type is not
5762 -- set. The error will be detected later, here we just defend the
5763 -- expander code.
5771 -- Boolean types (requiring handling of non-standard case)
5779 -- Array types
5783 -- If we are doing full validity checking, and it is possible for the
5784 -- array elements to be invalid then expand out array comparisons to
5785 -- make sure that we check the array elements.
5787 if Validity_Check_Operands
5789 then
5790 declare
5792 Force_Validity_Checks;
5793 begin
5796 Expand_Array_Equality
5800 Bodies,
5801 Typl));
5807 -- Packed case where both operands are known aligned
5812 then
5815 -- Where the component type is elementary we can use a block bit
5816 -- comparison (if supported on the target) exception in the case
5817 -- of floating-point (negative zero issues require element by
5818 -- element comparison), and atomic types (where we must be sure
5819 -- to load elements independently) and possibly unaligned arrays.
5826 and then Support_Composite_Compare_On_Target
5827 then
5830 -- For composite and floating-point cases, expand equality loop to
5831 -- make sure of using proper comparisons for tagged types, and
5832 -- correctly handling the floating-point case.
5834 else
5836 Expand_Array_Equality
5840 Bodies,
5841 Typl));
5846 -- Record Types
5850 -- For tagged types, use the primitive "="
5854 -- No need to do anything else compiling under restriction
5855 -- No_Dispatching_Calls. During the semantic analysis we
5856 -- already notified such violation.
5862 -- If this is derived from an untagged private type completed with
5863 -- a tagged type, it does not have a full view, so we use the
5864 -- primitive operations of the private type. This check should no
5865 -- longer be necessary when these types get their full views???
5871 then
5872 -- Search for equality operation, checking that the operands
5873 -- have the same type. Note that we must find a matching entry,
5874 -- or something is very wrong!
5882 and then
5891 -- Find the type's predefined equality or an overriding
5892 -- user- defined equality. The reason for not simply calling
5893 -- Find_Prim_Op here is that there may be a user-defined
5894 -- overloaded equality op that precedes the equality that we want,
5895 -- so we have to explicitly search (e.g., there could be an
5896 -- equality with two different parameter types).
5898 else
5908 and then
5920 -- Ada 2005 (AI-216): Program_Error is raised when evaluating the
5921 -- predefined equality operator for a type which has a subcomponent
5922 -- of an Unchecked_Union type whose nominal subtype is unconstrained.
5929 -- Prevent Gigi from generating incorrect code by rewriting the
5930 -- equality as a standard False.
5937 -- If we can infer the discriminants of the operands, we make a
5938 -- call to the TSS equality function.
5941 and then
5943 then
5944 Build_Equality_Call
5947 else
5948 -- Ada 2005 (AI-216): Program_Error is raised when evaluating
5949 -- the predefined equality operator for an Unchecked_Union type
5950 -- if either of the operands lack inferable discriminants.
5956 -- Prevent Gigi from generating incorrect code by rewriting
5957 -- the equality as a standard False.
5964 -- If a type support function is present (for complex cases), use it
5967 Build_Equality_Call
5970 -- Otherwise expand the component by component equality. Note that
5971 -- we never use block-bit comparisons for records, because of the
5972 -- problems with gaps. The backend will often be able to recombine
5973 -- the separate comparisons that we generate here.
5975 else
5986 -- Test if result is known at compile time
5990 -- If we still have comparison for Vax_Float, process it
5998 -----------------------
5999 -- Expand_N_Op_Expon --
6000 -----------------------
6018 begin
6021 -- If either operand is of a private type, then we have the use of an
6022 -- intrinsic operator, and we get rid of the privateness, by using root
6023 -- types of underlying types for the actual operation. Otherwise the
6024 -- private types will cause trouble if we expand multiplications or
6025 -- shifts etc. We also do this transformation if the result type is
6026 -- different from the base type.
6029 or else
6031 or else
6033 or else
6035 then
6036 declare
6040 begin
6051 -- Test for case of known right argument
6056 -- We only fold small non-negative exponents. You might think we
6057 -- could fold small negative exponents for the real case, but we
6058 -- can't because we are required to raise Constraint_Error for
6059 -- the case of 0.0 ** (negative) even if Machine_Overflows = False.
6060 -- See ACVC test C4A012B.
6064 -- X ** 0 = 1 (or 1.0)
6068 -- Call Remove_Side_Effects to ensure that any side effects
6069 -- in the ignored left operand (in particular function calls
6070 -- to user defined functions) are properly executed.
6076 else
6080 -- X ** 1 = X
6085 -- X ** 2 = X * X
6088 Xnode :=
6093 -- X ** 3 = X * X * X
6096 Xnode :=
6098 Left_Opnd =>
6104 -- X ** 4 ->
6105 -- En : constant base'type := base * base;
6106 -- ...
6107 -- En * En
6117 Expression =>
6122 Xnode :=
6134 -- Case of (2 ** expression) appearing as an argument of an integer
6135 -- multiplication, or as the right argument of a division of a non-
6136 -- negative integer. In such cases we leave the node untouched, setting
6137 -- the flag Is_Natural_Power_Of_2_for_Shift set, then the expansion
6138 -- of the higher level node converts it into a shift.
6140 -- Another case is 2 ** N in any other context. We simply convert
6141 -- this to 1 * 2 ** N, and then the above transformation applies.
6143 -- Note: this transformation is not applicable for a modular type with
6144 -- a non-binary modulus in the multiplication case, since we get a wrong
6145 -- result if the shift causes an overflow before the modular reduction.
6152 and then not Ovflo
6153 then
6154 -- First the multiply and divide cases
6157 declare
6162 begin
6165 and then
6167 or else
6170 or else
6176 then
6182 -- Now the other cases
6194 -- Fall through if exponentiation must be done using a runtime routine
6196 -- First deal with modular case
6200 -- Non-binary case, we call the special exponentiation routine for
6201 -- the non-binary case, converting the argument to Long_Long_Integer
6202 -- and passing the modulus value. Then the result is converted back
6203 -- to the base type.
6213 Exp))));
6215 -- Binary case, in this case, we call one of two routines, either the
6216 -- unsigned integer case, or the unsigned long long integer case,
6217 -- with a final "and" operation to do the required mod.
6219 else
6222 else
6229 Left_Opnd =>
6234 Exp)),
6235 Right_Opnd =>
6240 -- Common exit point for modular type case
6245 -- Signed integer cases, done using either Integer or Long_Long_Integer.
6246 -- It is not worth having routines for Short_[Short_]Integer, since for
6247 -- most machines it would not help, and it would generate more code that
6248 -- might need certification when a certified run time is required.
6250 -- In the integer cases, we have two routines, one for when overflow
6251 -- checks are required, and one when they are not required, since there
6252 -- is a real gain in omitting checks on many machines.
6256 and then
6259 then
6264 else
6273 else
6277 -- Floating-point cases, always done using Long_Long_Float. We do not
6278 -- need separate routines for the overflow case here, since in the case
6279 -- of floating-point, we generate infinities anyway as a rule (either
6280 -- that or we automatically trap overflow), and if there is an infinity
6281 -- generated and a range check is required, the check will fail anyway.
6283 else
6289 -- Common processing for integer cases and floating-point cases.
6290 -- If we are in the right type, we can call runtime routine directly
6295 then
6301 -- Otherwise we have to introduce conversions (conversions are also
6302 -- required in the universal cases, since the runtime routine is
6303 -- typed using one of the standard types).
6305 else
6312 Exp))));
6318 exception
6323 --------------------
6324 -- Expand_N_Op_Ge --
6325 --------------------
6333 begin
6350 -- If we still have comparison, and Vax_Float type, process it
6358 --------------------
6359 -- Expand_N_Op_Gt --
6360 --------------------
6368 begin
6385 -- If we still have comparison, and Vax_Float type, process it
6393 --------------------
6394 -- Expand_N_Op_Le --
6395 --------------------
6403 begin
6420 -- If we still have comparison, and Vax_Float type, process it
6428 --------------------
6429 -- Expand_N_Op_Lt --
6430 --------------------
6438 begin
6455 -- If we still have comparison, and Vax_Float type, process it
6463 -----------------------
6464 -- Expand_N_Op_Minus --
6465 -----------------------
6471 begin
6474 if not Backend_Overflow_Checks_On_Target
6477 then
6478 -- Software overflow checking expands -expr into (0 - expr)
6487 -- Vax floating-point types case
6494 ---------------------
6495 -- Expand_N_Op_Mod --
6496 ---------------------
6516 begin
6522 -- Convert mod to rem if operands are known non-negative. We do this
6523 -- since it is quite likely that this will improve the quality of code,
6524 -- (the operation now corresponds to the hardware remainder), and it
6525 -- does not seem likely that it could be harmful.
6528 and then
6530 then
6536 -- Instead of reanalyzing the node we do the analysis manually. This
6537 -- avoids anomalies when the replacement is done in an instance and
6538 -- is epsilon more efficient.
6547 -- Otherwise, normal mod processing
6549 else
6554 -- Apply optimization x mod 1 = 0. We don't really need that with
6555 -- gcc, but it is useful with other back ends (e.g. AAMP), and is
6556 -- certainly harmless.
6561 then
6562 -- Call Remove_Side_Effects to ensure that any side effects in
6563 -- the ignored left operand (in particular function calls to
6564 -- user defined functions) are properly executed.
6573 -- Deal with annoying case of largest negative number remainder
6574 -- minus one. Gigi does not handle this case correctly, because
6575 -- it generates a divide instruction which may trap in this case.
6577 -- In fact the check is quite easy, if the right operand is -1, then
6578 -- the mod value is always 0, and we can just ignore the left operand
6579 -- completely in this case.
6581 -- The operand type may be private (e.g. in the expansion of an
6582 -- intrinsic operation) so we must use the underlying type to get the
6583 -- bounds, and convert the literals explicitly.
6585 LLB :=
6586 Expr_Value
6590 and then
6592 then
6598 Right_Opnd =>
6611 --------------------------
6612 -- Expand_N_Op_Multiply --
6613 --------------------------
6632 begin
6635 -- Special optimizations for integer types
6639 -- N * 0 = 0 for integer types
6643 then
6644 -- Call Remove_Side_Effects to ensure that any side effects in
6645 -- the ignored left operand (in particular function calls to
6646 -- user defined functions) are properly executed.
6655 -- Similar handling for 0 * N = 0
6659 then
6666 -- N * 1 = 1 * N = N for integer types
6668 -- This optimisation is not done if we are going to
6669 -- rewrite the product 1 * 2 ** N to a shift.
6673 and then not Lp2
6674 then
6680 and then not Rp2
6681 then
6687 -- Convert x * 2 ** y to Shift_Left (x, y). Note that the fact that
6688 -- Is_Power_Of_2_For_Shift is set means that we know that our left
6689 -- operand is an integer, as required for this to work.
6694 -- Convert 2 ** A * 2 ** B into 2 ** (A + B)
6699 Right_Opnd =>
6706 else
6710 Right_Opnd =>
6716 -- Same processing for the operands the other way round
6722 Right_Opnd =>
6728 -- Do required fixup of universal fixed operation
6735 -- Multiplications with fixed-point results
6739 -- No special processing if Treat_Fixed_As_Integer is set, since from
6740 -- a semantic point of view such operations are simply integer
6741 -- operations and will be treated that way.
6745 -- Case of fixed * integer => fixed
6750 -- Case of integer * fixed => fixed
6755 -- Case of fixed * fixed => fixed
6757 else
6762 -- Other cases of multiplication of fixed-point operands. Again we
6763 -- exclude the cases where Treat_Fixed_As_Integer flag is set.
6767 then
6770 else
6775 -- Mixed-mode operations can appear in a non-static universal context,
6776 -- in which case the integer argument must be converted explicitly.
6780 then
6787 then
6792 -- Non-fixed point cases, check software overflow checking required
6797 -- Deal with VAX float case
6805 --------------------
6806 -- Expand_N_Op_Ne --
6807 --------------------
6812 begin
6813 -- Case of elementary type with standard operator
6817 then
6820 -- Boolean types (requiring handling of non-standard case)
6831 -- If we still have comparison for Vax_Float, process it
6838 -- For all cases other than elementary types, we rewrite node as the
6839 -- negation of an equality operation, and reanalyze. The equality to be
6840 -- used is defined in the same scope and has the same signature. This
6841 -- signature must be set explicitly since in an instance it may not have
6842 -- the same visibility as in the generic unit. This avoids duplicating
6843 -- or factoring the complex code for record/array equality tests etc.
6845 else
6846 declare
6851 begin
6854 Neg :=
6856 Right_Opnd =>
6866 -- For navigation purposes, the inequality is treated as an
6867 -- implicit reference to the corresponding equality. Preserve the
6868 -- Comes_From_ source flag so that the proper Xref entry is
6869 -- generated.
6879 ---------------------
6880 -- Expand_N_Op_Not --
6881 ---------------------
6883 -- If the argument is other than a Boolean array type, there is no special
6884 -- expansion required, except for VMS operations on signed integers.
6886 -- For the packed case, we call the special routine in Exp_Pakd, except
6887 -- that if the component size is greater than one, we use the standard
6888 -- routine generating a gruesome loop (it is so peculiar to have packed
6889 -- arrays with non-standard Boolean representations anyway, so it does not
6890 -- matter that we do not handle this case efficiently).
6892 -- For the unpacked case (and for the special packed case where we have non
6893 -- standard Booleans, as discussed above), we generate and insert into the
6894 -- tree the following function definition:
6896 -- function Nnnn (A : arr) is
6897 -- B : arr;
6898 -- begin
6899 -- for J in a'range loop
6900 -- B (J) := not A (J);
6901 -- end loop;
6902 -- return B;
6903 -- end Nnnn;
6905 -- Here arr is the actual subtype of the parameter (and hence always
6906 -- constrained). Then we replace the not with a call to this function.
6922 begin
6925 -- For boolean operand, deal with non-standard booleans
6934 -- For the VMS "not" on signed integer types, use conversion to and
6935 -- from a predefined modular type.
6938 declare
6942 begin
6943 -- If this is a derived type, retrieve original VMS type so that
6944 -- the proper sized type is used for intermediate values.
6948 else
6952 -- The proper unsigned type must have a size compatible with the
6953 -- operand, to prevent misalignment.
6964 else
6977 -- Only array types need any other processing
6983 -- Case of array operand. If bit packed with a component size of 1,
6984 -- handle it in Exp_Pakd if the operand is known to be aligned.
6989 then
6994 -- Case of array operand which is not bit-packed. If the context is
6995 -- a safe assignment, call in-place operation, If context is a larger
6996 -- boolean expression in the context of a safe assignment, expansion is
6997 -- done by enclosing operation.
7010 -- Special case the negation of a binary operation
7013 and then Safe_In_Place_Array_Op
7015 then
7022 then
7023 declare
7028 begin
7031 -- (not A) op (not B) can be reduced to a single call
7036 -- A xor (not B) can also be special-cased
7049 A_J :=
7054 B_J :=
7059 Loop_Statement :=
7063 Iteration_Scheme =>
7065 Loop_Parameter_Specification =>
7068 Discrete_Subtype_Definition =>
7083 Specification =>
7097 Handled_Statement_Sequence =>
7100 Loop_Statement,
7112 --------------------
7113 -- Expand_N_Op_Or --
7114 --------------------
7119 begin
7127 -- Replace OR by OR ELSE if Short_Circuit_And_Or active and the type
7128 -- is standard Boolean (do not mess with AND that uses a non-standard
7129 -- Boolean type, because something strange is going on).
7138 -- Otherwise, adjust conditions
7140 else
7149 ----------------------
7150 -- Expand_N_Op_Plus --
7151 ----------------------
7154 begin
7158 ---------------------
7159 -- Expand_N_Op_Rem --
7160 ---------------------
7175 -- Set if corresponding operand can be negative
7179 begin
7186 -- Apply optimization x rem 1 = 0. We don't really need that with gcc,
7187 -- but it is useful with other back ends (e.g. AAMP), and is certainly
7188 -- harmless.
7193 then
7194 -- Call Remove_Side_Effects to ensure that any side effects in the
7195 -- ignored left operand (in particular function calls to user defined
7196 -- functions) are properly executed.
7205 -- Deal with annoying case of largest negative number remainder minus
7206 -- one. Gigi does not handle this case correctly, because it generates
7207 -- a divide instruction which may trap in this case.
7209 -- In fact the check is quite easy, if the right operand is -1, then
7210 -- the remainder is always 0, and we can just ignore the left operand
7211 -- completely in this case.
7219 -- We won't mess with trying to find out if the left operand can really
7220 -- be the largest negative number (that's a pain in the case of private
7221 -- types and this is really marginal). We will just assume that we need
7222 -- the test if the left operand can be negative at all.
7230 Right_Opnd =>
7243 -----------------------------
7244 -- Expand_N_Op_Rotate_Left --
7245 -----------------------------
7248 begin
7252 ------------------------------
7253 -- Expand_N_Op_Rotate_Right --
7254 ------------------------------
7257 begin
7261 ----------------------------
7262 -- Expand_N_Op_Shift_Left --
7263 ----------------------------
7266 begin
7270 -----------------------------
7271 -- Expand_N_Op_Shift_Right --
7272 -----------------------------
7275 begin
7279 ----------------------------------------
7280 -- Expand_N_Op_Shift_Right_Arithmetic --
7281 ----------------------------------------
7284 begin
7288 --------------------------
7289 -- Expand_N_Op_Subtract --
7290 --------------------------
7295 begin
7298 -- N - 0 = N for integer types
7303 then
7308 -- Arithmetic overflow checks for signed integer/fixed point types
7311 or else
7313 then
7316 -- VAX floating-point types case
7323 ---------------------
7324 -- Expand_N_Op_Xor --
7325 ---------------------
7330 begin
7344 ----------------------
7345 -- Expand_N_Or_Else --
7346 ----------------------
7351 -----------------------------------
7352 -- Expand_N_Qualified_Expression --
7353 -----------------------------------
7359 begin
7360 -- Do validity check if validity checking operands
7362 if Validity_Checks_On
7363 and then Validity_Check_Operands
7364 then
7368 -- Apply possible constraint check
7378 ---------------------------------
7379 -- Expand_N_Selected_Component --
7380 ---------------------------------
7382 -- If the selector is a discriminant of a concurrent object, rewrite the
7383 -- prefix to denote the corresponding record type.
7396 -- Gigi needs a temporary for prefixes that depend on a discriminant,
7397 -- unless the context of an assignment can provide size information.
7398 -- Don't we have a general routine that does this???
7400 -----------------------
7401 -- In_Left_Hand_Side --
7402 -----------------------
7405 begin
7413 -- Start of processing for Expand_N_Selected_Component
7415 begin
7416 -- Insert explicit dereference if required
7424 then
7431 -- Deal with discriminant check required
7435 -- Present the discriminant checking function to the backend, so that
7436 -- it can inline the call to the function.
7438 Add_Inlined_Body
7439 (Discriminant_Checking_Func
7442 -- Now reset the flag and generate the call
7448 -- Ada 2005 (AI-318-02): If the prefix is a call to a build-in-place
7449 -- function, then additional actuals must be passed.
7453 then
7457 -- Gigi cannot handle unchecked conversions that are the prefix of a
7458 -- selected component with discriminants. This must be checked during
7459 -- expansion, because during analysis the type of the selector is not
7460 -- known at the point the prefix is analyzed. If the conversion is the
7461 -- target of an assignment, then we cannot force the evaluation.
7466 then
7470 -- Remaining processing applies only if selector is a discriminant
7474 -- If the selector is a discriminant of a constrained record type,
7475 -- we may be able to rewrite the expression with the actual value
7476 -- of the discriminant, a useful optimization in some cases.
7481 then
7482 -- Do this optimization for discrete types only, and not for
7483 -- access types (access discriminants get us into trouble!)
7488 -- Don't do this on the left hand of an assignment statement.
7489 -- Normally one would think that references like this would not
7490 -- occur, but they do in generated code, and mean that we really
7491 -- do want to assign the discriminant!
7495 then
7498 -- Don't do this optimization for the prefix of an attribute or
7499 -- the name of an object renaming declaration since these are
7500 -- contexts where we do not want the value anyway.
7505 then
7508 -- Don't do this optimization if we are within the code for a
7509 -- discriminant check, since the whole point of such a check may
7510 -- be to verify the condition on which the code below depends!
7515 -- Green light to see if we can do the optimization. There is
7516 -- still one condition that inhibits the optimization below but
7517 -- now is the time to check the particular discriminant.
7519 else
7520 -- Loop through discriminants to find the matching discriminant
7521 -- constraint to see if we can copy it.
7529 -- Check if this is the matching discriminant
7533 -- Here we have the matching discriminant. Check for
7534 -- the case of a discriminant of a component that is
7535 -- constrained by an outer discriminant, which cannot
7536 -- be optimized away.
7538 if Denotes_Discriminant
7540 then
7544 and then
7545 Denotes_Discriminant
7547 then
7550 -- Do not retrieve value if constraint is not static. It
7551 -- is generally not useful, and the constraint may be a
7552 -- rewritten outer discriminant in which case it is in
7553 -- fact incorrect.
7557 = N_Object_Declaration
7559 and then
7560 not Is_Static_Expression
7562 then
7565 -- In the context of a case statement, the expression may
7566 -- have the base type of the discriminant, and we need to
7567 -- preserve the constraint to avoid spurious errors on
7568 -- missing cases.
7572 then
7575 Subtype_Mark =>
7577 Expression =>
7581 -- In case that comes out as a static expression,
7582 -- reset it (a selected component is never static).
7587 -- Otherwise we can just copy the constraint, but the
7588 -- result is certainly not static! In some cases the
7589 -- discriminant constraint has been analyzed in the
7590 -- context of the original subtype indication, but for
7591 -- itypes the constraint might not have been analyzed
7592 -- yet, and this must be done now.
7594 else
7606 -- Note: the above loop should always find a matching
7607 -- discriminant, but if it does not, we just missed an
7608 -- optimization due to some glitch (perhaps a previous error),
7609 -- so ignore.
7614 -- The only remaining processing is in the case of a discriminant of
7615 -- a concurrent object, where we rewrite the prefix to denote the
7616 -- corresponding record type. If the type is derived and has renamed
7617 -- discriminants, use corresponding discriminant, which is the one
7618 -- that appears in the corresponding record.
7628 then
7632 New_N :=
7634 Prefix =>
7644 --------------------
7645 -- Expand_N_Slice --
7646 --------------------
7655 -- Check whether the argument is an actual for a procedure call, in
7656 -- which case the expansion of a bit-packed slice is deferred until the
7657 -- call itself is expanded. The reason this is required is that we might
7658 -- have an IN OUT or OUT parameter, and the copy out is essential, and
7659 -- that copy out would be missed if we created a temporary here in
7660 -- Expand_N_Slice. Note that we don't bother to test specifically for an
7661 -- IN OUT or OUT mode parameter, since it is a bit tricky to do, and it
7662 -- is harmless to defer expansion in the IN case, since the call
7663 -- processing will still generate the appropriate copy in operation,
7664 -- which will take care of the slice.
7667 -- Create a named variable for the value of the slice, in cases where
7668 -- the back-end cannot handle it properly, e.g. when packed types or
7669 -- unaligned slices are involved.
7671 -------------------------
7672 -- Is_Procedure_Actual --
7673 -------------------------
7678 begin
7679 loop
7680 -- If our parent is a procedure call we can return
7685 -- If our parent is a type conversion, keep climbing the tree,
7686 -- since a type conversion can be a procedure actual. Also keep
7687 -- climbing if parameter association or a qualified expression,
7688 -- since these are additional cases that do can appear on
7689 -- procedure actuals.
7692 N_Parameter_Association,
7693 N_Qualified_Expression)
7694 then
7697 -- Any other case is not what we are looking for
7699 else
7705 ------------------------------
7706 -- Make_Temporary_For_Slice --
7707 ------------------------------
7713 begin
7714 Decl :=
7722 Decl,
7731 -- Start of processing for Expand_N_Slice
7733 begin
7734 -- Special handling for access types
7747 -- Ada 2005 (AI-318-02): If the prefix is a call to a build-in-place
7748 -- function, then additional actuals must be passed.
7752 then
7756 -- The remaining case to be handled is packed slices. We can leave
7757 -- packed slices as they are in the following situations:
7759 -- 1. Right or left side of an assignment (we can handle this
7760 -- situation correctly in the assignment statement expansion).
7762 -- 2. Prefix of indexed component (the slide is optimized away in this
7763 -- case, see the start of Expand_N_Slice.)
7765 -- 3. Object renaming declaration, since we want the name of the
7766 -- slice, not the value.
7768 -- 4. Argument to procedure call, since copy-in/copy-out handling may
7769 -- be required, and this is handled in the expansion of call
7770 -- itself.
7772 -- 5. Prefix of an address attribute (this is an error which is caught
7773 -- elsewhere, and the expansion would interfere with generating the
7774 -- error message).
7778 -- Apply transformation for actuals of a function call, where
7779 -- Expand_Actuals is not used.
7783 then
7784 Make_Temporary_For_Slice;
7790 then
7796 then
7801 then
7804 else
7805 Make_Temporary_For_Slice;
7809 ------------------------------
7810 -- Expand_N_Type_Conversion --
7811 ------------------------------
7820 -- This is called in the case of record and array type conversions to
7821 -- see if there is a change of representation to be handled. Change of
7822 -- representation is actually handled at the assignment statement level,
7823 -- and what this procedure does is rewrite node N conversion as an
7824 -- assignment to temporary. If there is no change of representation,
7825 -- then the conversion node is unchanged.
7828 -- Called when we know that an accessibility check will fail. Rewrites
7829 -- node N to an appropriate raise statement and outputs warning msgs.
7830 -- The Etype of the raise node is set to Target_Type.
7833 -- Handles generation of range check for real target value
7835 -----------------------------------
7836 -- Handle_Changed_Representation --
7837 -----------------------------------
7847 begin
7848 -- Nothing else to do if no change of representation
7853 -- The real change of representation work is done by the assignment
7854 -- statement processing. So if this type conversion is appearing as
7855 -- the expression of an assignment statement, nothing needs to be
7856 -- done to the conversion.
7861 -- Otherwise we need to generate a temporary variable, and do the
7862 -- change of representation assignment into that temporary variable.
7863 -- The conversion is then replaced by a reference to this variable.
7865 else
7868 -- If type is unconstrained we have to add a constraint, copied
7869 -- from the actual value of the left hand side.
7884 Selector_Name =>
7895 -- We convert the bounds explicitly. We use an unchecked
7896 -- conversion because bounds checks are done elsewhere.
7900 Low_Bound =>
7903 Prefix =>
7904 Duplicate_Subexpr_No_Checks
7910 High_Bound =>
7913 Prefix =>
7914 Duplicate_Subexpr_No_Checks
7928 Odef :=
7931 Constraint =>
7937 Decl :=
7944 -- Insert required actions. It is essential to suppress checks
7945 -- since we have suppressed default initialization, which means
7946 -- that the variable we create may have no discriminants.
7949 New_List (
7950 Decl,
7961 -------------------------------
7962 -- Raise_Accessibility_Error --
7963 -------------------------------
7966 begin
7973 Error_Msg_NE
7977 ----------------------
7978 -- Real_Range_Check --
7979 ----------------------
7981 -- Case of conversions to floating-point or fixed-point. If range checks
7982 -- are enabled and the target type has a range constraint, we convert:
7984 -- typ (x)
7986 -- to
7988 -- Tnn : typ'Base := typ'Base (x);
7989 -- [constraint_error when Tnn < typ'First or else Tnn > typ'Last]
7990 -- Tnn
7992 -- This is necessary when there is a conversion of integer to float or
7993 -- to fixed-point to ensure that the correct checks are made. It is not
7994 -- necessary for float to float where it is enough to simply set the
7995 -- Do_Range_Check flag.
8005 begin
8006 -- Nothing to do if conversion was rewritten
8012 -- Nothing to do if range checks suppressed, or target has the same
8013 -- range as the base type (or is the base type).
8017 and then
8019 then
8023 -- Nothing to do if expression is an entity on which checks have been
8024 -- suppressed.
8028 then
8032 -- Nothing to do if bounds are all static and we can tell that the
8033 -- expression is within the bounds of the target. Note that if the
8034 -- operand is of an unconstrained floating-point type, then we do
8035 -- not trust it to be in range (might be infinite)
8037 declare
8041 begin
8048 then
8049 declare
8055 begin
8059 else
8067 then
8075 -- For float to float conversions, we are done
8078 and then
8080 then
8084 -- Otherwise rewrite the conversion as described above
8090 -- Enable overflow except for case of integer to float conversions,
8091 -- where it is never required, since we can never have overflow in
8092 -- this case.
8107 Condition =>
8109 Left_Opnd =>
8112 Right_Opnd =>
8115 Prefix =>
8118 Right_Opnd =>
8121 Right_Opnd =>
8124 Prefix =>
8132 -- Start of processing for Expand_N_Type_Conversion
8134 begin
8135 -- Nothing at all to do if conversion is to the identical type so remove
8136 -- the conversion completely, it is useless, except that it may carry
8137 -- an Assignment_OK attribute, which must be propagated to the operand.
8148 -- Nothing to do if this is the second argument of read. This is a
8149 -- "backwards" conversion that will be handled by the specialized code
8150 -- in attribute processing.
8155 then
8159 -- Here if we may need to expand conversion
8161 -- If the operand of the type conversion is an arithmetic operation on
8162 -- signed integers, and the based type of the signed integer type in
8163 -- question is smaller than Standard.Integer, we promote both of the
8164 -- operands to type Integer.
8166 -- For example, if we have
8168 -- target-type (opnd1 + opnd2)
8170 -- and opnd1 and opnd2 are of type short integer, then we rewrite
8171 -- this as:
8173 -- target-type (integer(opnd1) + integer(opnd2))
8175 -- We do this because we are always allowed to compute in a larger type
8176 -- if we do the right thing with the result, and in this case we are
8177 -- going to do a conversion which will do an appropriate check to make
8178 -- sure that things are in range of the target type in any case. This
8179 -- avoids some unnecessary intermediate overflows.
8181 -- We might consider a similar transformation in the case where the
8182 -- target is a real type or a 64-bit integer type, and the operand
8183 -- is an arithmetic operation using a 32-bit integer type. However,
8184 -- we do not bother with this case, because it could cause significant
8185 -- ineffiencies on 32-bit machines. On a 64-bit machine it would be
8186 -- much cheaper, but we don't want different behavior on 32-bit and
8187 -- 64-bit machines. Note that the exclusion of the 64-bit case also
8188 -- handles the configurable run-time cases where 64-bit arithmetic
8189 -- may simply be unavailable.
8191 -- Note: this circuit is partially redundant with respect to the circuit
8192 -- in Checks.Apply_Arithmetic_Overflow_Check, but we catch more cases in
8193 -- the processing here. Also we still need the Checks circuit, since we
8194 -- have to be sure not to generate junk overflow checks in the first
8195 -- place, since it would be trick to remove them here!
8199 -- All conditions met, go ahead with transformation
8201 declare
8205 begin
8206 R :=
8215 L :=
8233 -- Do validity check if validity checking operands
8235 if Validity_Checks_On
8236 and then Validity_Check_Operands
8237 then
8241 -- Special case of converting from non-standard boolean type
8245 then
8251 -- Case of converting to an access type
8255 -- Apply an accessibility check when the conversion operand is an
8256 -- access parameter (or a renaming thereof), unless conversion was
8257 -- expanded from an Unchecked_ or Unrestricted_Access attribute.
8258 -- Note that other checks may still need to be applied below (such
8259 -- as tagged type checks).
8262 and then
8264 or else
8267 and then Is_Formal
8272 then
8273 Apply_Accessibility_Check
8276 -- If the level of the operand type is statically deeper than the
8277 -- level of the target type, then force Program_Error. Note that this
8278 -- can only occur for cases where the attribute is within the body of
8279 -- an instantiation (otherwise the conversion will already have been
8280 -- rejected as illegal). Note: warnings are issued by the analyzer
8281 -- for the instance cases.
8283 elsif In_Instance_Body
8286 then
8287 Raise_Accessibility_Error;
8289 -- When the operand is a selected access discriminant the check needs
8290 -- to be made against the level of the object denoted by the prefix
8291 -- of the selected name. Force Program_Error for this case as well
8292 -- (this accessibility violation can only happen if within the body
8293 -- of an instantiation).
8295 elsif In_Instance_Body
8300 then
8301 Raise_Accessibility_Error;
8306 -- Case of conversions of tagged types and access to tagged types
8308 -- When needed, that is to say when the expression is class-wide, Add
8309 -- runtime a tag check for (strict) downward conversion by using the
8310 -- membership test, generating:
8312 -- [constraint_error when Operand not in Target_Type'Class]
8314 -- or in the access type case
8316 -- [constraint_error
8317 -- when Operand /= null
8318 -- and then Operand.all not in
8319 -- Designated_Type (Target_Type)'Class]
8324 then
8325 -- Do not do any expansion in the access type case if the parent is a
8326 -- renaming, since this is an error situation which will be caught by
8327 -- Sem_Ch8, and the expansion can interfere with this error check.
8333 -- Otherwise, proceed with processing tagged conversion
8342 -- Create a membership check to test whether Operand is a member
8343 -- of Targ_Typ. If the original Target_Type is an access, include
8344 -- a test for null value. The check is inserted at N.
8346 --------------------
8347 -- Make_Tag_Check --
8348 --------------------
8353 begin
8354 -- Generate:
8355 -- [Constraint_Error
8356 -- when Operand /= null
8357 -- and then Operand.all not in Targ_Typ]
8360 Cond :=
8362 Left_Opnd =>
8367 Right_Opnd =>
8369 Left_Opnd =>
8374 -- Generate:
8375 -- [Constraint_Error when Operand not in Targ_Typ]
8377 else
8378 Cond :=
8390 -- Start of processing for Tagged_Conversion
8392 begin
8395 -- Handle entities from the limited view
8397 Actual_Op_Typ :=
8399 Actual_Targ_Typ :=
8401 else
8408 -- Ada 2005 (AI-251): Handle interface type conversion
8417 -- Create a runtime tag check for a downward class-wide type
8418 -- conversion.
8424 then
8429 -- AI05-0073: If the result subtype of the function is defined
8430 -- by an access_definition designating a specific tagged type
8431 -- T, a check is made that the result value is null or the tag
8432 -- of the object designated by the result value identifies T.
8433 -- Constraint_Error is raised if this check fails.
8436 declare
8440 begin
8441 -- Climb scope stack looking for the enclosing function
8446 loop
8450 -- The function's return subtype must be defined using
8451 -- an access definition.
8454 N_Access_Definition
8455 then
8458 -- The return subtype denotes a specific tagged type,
8459 -- in other words, a non class-wide type.
8463 then
8471 -- We have generated a tag check for either a class-wide type
8472 -- conversion or for AI05-0073.
8475 declare
8477 begin
8478 Conv :=
8489 -- Case of other access type conversions
8494 -- Case of conversions from a fixed-point type
8496 -- These conversions require special expansion and processing, found in
8497 -- the Exp_Fixd package. We ignore cases where Conversion_OK is set,
8498 -- since from a semantic point of view, these are simple integer
8499 -- conversions, which do not need further processing.
8503 then
8504 -- We should never see universal fixed at this case, since the
8505 -- expansion of the constituent divide or multiply should have
8506 -- eliminated the explicit mention of universal fixed.
8510 -- Check for special case of the conversion to universal real that
8511 -- occurs as a result of the use of a round attribute. In this case,
8512 -- the real type for the conversion is taken from the target type of
8513 -- the Round attribute and the result must be marked as rounded.
8518 then
8523 -- Otherwise do correct fixed-conversion, but skip these if the
8524 -- Conversion_OK flag is set, because from a semantic point of view
8525 -- these are simple integer conversions needing no further processing
8526 -- (the backend will simply treat them as integers).
8531 Real_Range_Check;
8536 else
8539 Real_Range_Check;
8543 -- Case of conversions to a fixed-point type
8545 -- These conversions require special expansion and processing, found in
8546 -- the Exp_Fixd package. Again, ignore cases where Conversion_OK is set,
8547 -- since from a semantic point of view, these are simple integer
8548 -- conversions, which do not need further processing.
8552 then
8555 Real_Range_Check;
8556 else
8559 Real_Range_Check;
8562 -- Case of float-to-integer conversions
8564 -- We also handle float-to-fixed conversions with Conversion_OK set
8565 -- since semantically the fixed-point target is treated as though it
8566 -- were an integer in such cases.
8569 and then
8571 or else
8573 then
8574 -- One more check here, gcc is still not able to do conversions of
8575 -- this type with proper overflow checking, and so gigi is doing an
8576 -- approximation of what is required by doing floating-point compares
8577 -- with the end-point. But that can lose precision in some cases, and
8578 -- give a wrong result. Converting the operand to Universal_Real is
8579 -- helpful, but still does not catch all cases with 64-bit integers
8580 -- on targets with only 64-bit floats.
8582 -- The above comment seems obsoleted by Apply_Float_Conversion_Check
8583 -- Can this code be removed ???
8588 Subtype_Mark =>
8590 Expression =>
8598 -- Case of array conversions
8600 -- Expansion of array conversions, add required length/range checks but
8601 -- only do this if there is no change of representation. For handling of
8602 -- this case, see Handle_Changed_Representation.
8608 else
8612 Handle_Changed_Representation;
8614 -- Case of conversions of discriminated types
8616 -- Add required discriminant checks if target is constrained. Again this
8617 -- change is skipped if we have a change of representation.
8621 then
8623 Handle_Changed_Representation;
8625 -- Case of all other record conversions. The only processing required
8626 -- is to check for a change of representation requiring the special
8627 -- assignment processing.
8631 -- Ada 2005 (AI-216): Program_Error is raised when converting from
8632 -- a derived Unchecked_Union type to an unconstrained type that is
8633 -- not Unchecked_Union if the operand lacks inferable discriminants.
8640 then
8641 -- To prevent Gigi from generating illegal code, we generate a
8642 -- Program_Error node, but we give it the target type of the
8643 -- conversion.
8645 declare
8649 begin
8654 else
8655 Handle_Changed_Representation;
8658 -- Case of conversions of enumeration types
8662 -- Special processing is required if there is a change of
8663 -- representation (from enumeration representation clauses).
8667 -- Convert: x(y) to x'val (ytyp'val (y))
8682 -- Case of conversions to floating-point
8685 Real_Range_Check;
8688 -- At this stage, either the conversion node has been transformed into
8689 -- some other equivalent expression, or left as a conversion that can be
8690 -- handled by Gigi, in the following cases:
8692 -- Conversions with no change of representation or type
8694 -- Numeric conversions involving integer, floating- and fixed-point
8695 -- values. Fixed-point values are allowed only if Conversion_OK is
8696 -- set, i.e. if the fixed-point values are to be treated as integers.
8698 -- No other conversions should be passed to Gigi
8700 -- Check: are these rules stated in sinfo??? if so, why restate here???
8702 -- The only remaining step is to generate a range check if we still have
8703 -- a type conversion at this stage and Do_Range_Check is set. For now we
8704 -- do this only for conversions of discrete types.
8708 then
8709 declare
8714 begin
8717 then
8720 -- Before we do a range check, we have to deal with treating a
8721 -- fixed-point operand as an integer. The way we do this is
8722 -- simply to do an unchecked conversion to an appropriate
8723 -- integer type large enough to hold the result.
8725 -- This code is not active yet, because we are only dealing
8726 -- with discrete types so far ???
8730 then
8735 else
8742 -- Reset overflow flag, since the range check will include
8743 -- dealing with possible overflow, and generate the check. If
8744 -- Address is either a source type or target type, suppress
8745 -- range check to avoid typing anomalies when it is a visible
8746 -- integer type.
8751 then
8752 Generate_Range_Check
8759 -- Final step, if the result is a type conversion involving Vax_Float
8760 -- types, then it is subject for further special processing.
8764 then
8770 -----------------------------------
8771 -- Expand_N_Unchecked_Expression --
8772 -----------------------------------
8774 -- Remove the unchecked expression node from the tree. Its job was simply
8775 -- to make sure that its constituent expression was handled with checks
8776 -- off, and now that that is done, we can remove it from the tree, and
8777 -- indeed must, since Gigi does not expect to see these nodes.
8781 begin
8786 ----------------------------------------
8787 -- Expand_N_Unchecked_Type_Conversion --
8788 ----------------------------------------
8790 -- If this cannot be handled by Gigi and we haven't already made a
8791 -- temporary for it, do it now.
8798 begin
8799 -- Nothing at all to do if conversion is to the identical type so remove
8800 -- the conversion completely, it is useless, except that it may carry
8801 -- an Assignment_OK indication which must be propagated to the operand.
8805 -- Code duplicates Expand_N_Unchecked_Expression above, factor???
8815 -- If we have a conversion of a compile time known value to a target
8816 -- type and the value is in range of the target type, then we can simply
8817 -- replace the construct by an integer literal of the correct type. We
8818 -- only apply this to integer types being converted. Possibly it may
8819 -- apply in other cases, but it is too much trouble to worry about.
8821 -- Note that we do not do this transformation if the Kill_Range_Check
8822 -- flag is set, since then the value may be outside the expected range.
8823 -- This happens in the Normalize_Scalars case.
8825 -- We also skip this if either the target or operand type is biased
8826 -- because in this case, the unchecked conversion is supposed to
8827 -- preserve the bit pattern, not the integer value.
8835 then
8836 declare
8839 begin
8841 and then
8843 and then
8845 and then
8847 then
8850 -- If Address is the target type, just set the type to avoid a
8851 -- spurious type error on the literal when Address is a visible
8852 -- integer type.
8856 else
8865 -- Nothing to do if conversion is safe
8871 -- Otherwise force evaluation unless Assignment_OK flag is set (this
8872 -- flag indicates ??? -- more comments needed here)
8876 else
8881 ----------------------------
8882 -- Expand_Record_Equality --
8883 ----------------------------
8885 -- For non-variant records, Equality is expanded when needed into:
8887 -- and then Lhs.Discr1 = Rhs.Discr1
8888 -- and then ...
8889 -- and then Lhs.Discrn = Rhs.Discrn
8890 -- and then Lhs.Cmp1 = Rhs.Cmp1
8891 -- and then ...
8892 -- and then Lhs.Cmpn = Rhs.Cmpn
8894 -- The expression is folded by the back-end for adjacent fields. This
8895 -- function is called for tagged record in only one occasion: for imple-
8896 -- menting predefined primitive equality (see Predefined_Primitives_Bodies)
8897 -- otherwise the primitive "=" is used directly.
8899 function Expand_Record_Equality
8905 is
8914 -- Return the first field to compare beginning with C, skipping the
8915 -- inherited components.
8917 ----------------------
8918 -- Suitable_Element --
8919 ----------------------
8922 begin
8928 then
8933 then
8938 then
8944 else
8949 -- Start of processing for Expand_Record_Equality
8951 begin
8952 -- Generates the following code: (assuming that Typ has one Discr and
8953 -- component C2 is also a record)
8955 -- True
8956 -- and then Lhs.Discr1 = Rhs.Discr1
8957 -- and then Lhs.C1 = Rhs.C1
8958 -- and then Lhs.C2.C1=Rhs.C2.C1 and then ... Lhs.C2.Cn=Rhs.C2.Cn
8959 -- and then ...
8960 -- and then Lhs.Cmpn = Rhs.Cmpn
8965 declare
8970 begin
8975 else
8980 Check :=
8982 Lhs =>
8986 Rhs =>
8992 -- If some (sub)component is an unchecked_union, the whole
8993 -- operation will raise program error.
8999 else
9000 Result :=
9013 -----------------------------------
9014 -- Expand_Short_Circuit_Operator --
9015 -----------------------------------
9017 -- Deal with special expansion if actions are present for the right operand
9018 -- and deal with optimizing case of arguments being True or False. We also
9019 -- deal with the special case of non-standard boolean values.
9031 -- If Left = Shortcut_Value then Right need not be evaluated
9034 -- For Opnd a boolean expression, return a Boolean expression equivalent
9035 -- to Opnd /= Shortcut_Value.
9037 --------------------
9038 -- Make_Test_Expr --
9039 --------------------
9042 begin
9045 else
9051 -- Entity for a temporary variable holding the value of the operator,
9052 -- used for expansion in the case where actions are present.
9054 -- Start of processing for Expand_Short_Circuit_Operator
9056 begin
9057 -- Deal with non-standard booleans
9065 -- Check for cases where left argument is known to be True or False
9069 -- Mark SCO for left condition as compile time known
9075 -- Rewrite True AND THEN Right / False OR ELSE Right to Right.
9076 -- Any actions associated with Right will be executed unconditionally
9077 -- and can thus be inserted into the tree unconditionally.
9086 -- Rewrite False AND THEN Right / True OR ELSE Right to Left.
9087 -- In this case we can forget the actions associated with Right,
9088 -- since they will never be executed.
9090 else
9100 -- If Actions are present for the right operand, we have to do some
9101 -- special processing. We can't just let these actions filter back into
9102 -- code preceding the short circuit (which is what would have happened
9103 -- if we had not trapped them in the short-circuit form), since they
9104 -- must only be executed if the right operand of the short circuit is
9105 -- executed and not otherwise.
9107 -- the temporary variable C.
9112 -- The old approach is to expand:
9114 -- left AND THEN right
9116 -- into
9118 -- C : Boolean := False;
9119 -- IF left THEN
9120 -- Actions;
9121 -- IF right THEN
9122 -- C := True;
9123 -- END IF;
9124 -- END IF;
9126 -- and finally rewrite the operator into a reference to C. Similarly
9127 -- for left OR ELSE right, with negated values. Note that this
9128 -- rewrite causes some difficulties for coverage analysis because
9129 -- of the introduction of the new variable C, which obscures the
9130 -- structure of the test.
9132 -- We use this "old approach" if use of N_Expression_With_Actions
9133 -- is False (see description in Opt of when this is or is not set).
9140 Defining_Identifier =>
9141 Op_Var,
9142 Object_Definition =>
9144 Expression =>
9153 Expression =>
9154 New_Occurrence_Of
9165 -- The new approach, activated for now by the use of debug flag
9166 -- -gnatd.X is to use the new Expression_With_Actions node for the
9167 -- right operand of the short-circuit form. This should solve the
9168 -- traceability problems for coverage analysis.
9170 else
9183 -- No actions present, check for cases of right argument True/False
9187 -- Mark SCO for left condition as compile time known
9193 -- Change (Left and then True), (Left or else False) to Left.
9194 -- Note that we know there are no actions associated with the right
9195 -- operand, since we just checked for this case above.
9200 -- Change (Left and then False), (Left or else True) to Right,
9201 -- making sure to preserve any side effects associated with the Left
9202 -- operand.
9204 else
9213 -------------------------------------
9214 -- Fixup_Universal_Fixed_Operation --
9215 -------------------------------------
9220 begin
9221 -- We must have a type conversion immediately above us
9225 -- Normally the type conversion gives our target type. The exception
9226 -- occurs in the case of the Round attribute, where the conversion
9227 -- will be to universal real, and our real type comes from the Round
9228 -- attribute (as well as an indication that we must round the result)
9232 then
9236 -- Normal case where type comes from conversion above us
9238 else
9243 ------------------------------
9244 -- Get_Allocator_Final_List --
9245 ------------------------------
9247 function Get_Allocator_Final_List
9251 is
9255 -- The entity whose finalization list must be used to attach the
9256 -- allocated object.
9258 begin
9261 -- If the context is an access parameter, we need to create a
9262 -- non-anonymous access type in order to have a usable final list,
9263 -- because there is otherwise no pool to which the allocated object
9264 -- can belong. We create both the type and the finalization chain
9265 -- here, because freezing an internal type does not create such a
9266 -- chain. The Final_Chain that is thus created is shared by the
9267 -- access parameter. The access type is tested against the result
9268 -- type of the function to exclude allocators whose type is an
9269 -- anonymous access result type. We freeze the type at once to
9270 -- ensure that it is properly decorated for the back-end, even
9271 -- if the context and current scope is a loop.
9274 in N_Subprogram_Specification
9275 and then
9276 PtrT /=
9278 then
9283 Type_Definition =>
9285 Subtype_Indication =>
9292 -- Ada 2005 (AI-318-02): If the context is a return object
9293 -- declaration, then the anonymous return subtype is defined to have
9294 -- the same accessibility level as that of the function's result
9295 -- subtype, which means that we want the scope where the function is
9296 -- declared.
9300 then
9303 -- Case of an access discriminant, or (Ada 2005) of an anonymous
9304 -- access component or anonymous access function result: find the
9305 -- final list associated with the scope of the type. (In the
9306 -- anonymous access component kind, a list controller will have
9307 -- been allocated when freezing the record type, and PtrT has an
9308 -- Associated_Final_Chain attribute designating it.)
9318 ---------------------------------
9319 -- Has_Inferable_Discriminants --
9320 ---------------------------------
9325 -- Determines whether the left-most prefix of a selected component is a
9326 -- formal parameter in a subprogram. Assumes N is a selected component.
9328 --------------------------------
9329 -- Prefix_Is_Formal_Parameter --
9330 --------------------------------
9335 begin
9336 -- Move to the left-most prefix by climbing up the tree
9340 loop
9347 -- Start of processing for Has_Inferable_Discriminants
9349 begin
9350 -- For identifiers and indexed components, it is sufficient to have a
9351 -- constrained Unchecked_Union nominal subtype.
9355 and then
9358 -- For selected components, the subtype of the selector must be a
9359 -- constrained Unchecked_Union. If the component is subject to a
9360 -- per-object constraint, then the enclosing object must have inferable
9361 -- discriminants.
9366 -- A small hack. If we have a per-object constrained selected
9367 -- component of a formal parameter, return True since we do not
9368 -- know the actual parameter association yet.
9374 -- Otherwise, check the enclosing object and the selector
9377 and then
9381 -- The call to Has_Inferable_Discriminants will determine whether
9382 -- the selector has a constrained Unchecked_Union nominal type.
9386 -- A qualified expression has inferable discriminants if its subtype
9387 -- mark is a constrained Unchecked_Union subtype.
9391 and then
9399 -------------------------------
9400 -- Insert_Dereference_Action --
9401 -------------------------------
9410 -- Return true if type of P is derived from Checked_Pool;
9412 -----------------------------
9413 -- Is_Checked_Storage_Pool --
9414 -----------------------------
9419 begin
9428 else
9436 -- Start of processing for Insert_Dereference_Action
9438 begin
9443 then
9454 -- Pool
9458 -- Storage_Address. We use the attribute Pool_Address, which uses
9459 -- the pointer itself to find the address of the object, and which
9460 -- handles unconstrained arrays properly by computing the address
9461 -- of the template. i.e. the correct address of the corresponding
9462 -- allocation.
9468 -- Size_In_Storage_Elements
9471 Left_Opnd =>
9473 Prefix =>
9477 Right_Opnd =>
9480 -- Alignment
9483 Prefix =>
9488 exception
9493 --------------------------------
9494 -- Integer_Promotion_Possible --
9495 --------------------------------
9502 begin
9505 return
9507 -- We only do the transformation for source constructs. We assume
9508 -- that the expander knows what it is doing when it generates code.
9512 -- If the operand type is Short_Integer or Short_Short_Integer,
9513 -- then we will promote to Integer, which is available on all
9514 -- targets, and is sufficient to ensure no intermediate overflow.
9515 -- Furthermore it is likely to be as efficient or more efficient
9516 -- than using the smaller type for the computation so we do this
9517 -- unconditionally.
9519 and then
9521 or else
9524 -- Test for interesting operation, which includes addition,
9525 -- division, exponentiation, multiplication, subtraction, absolute
9526 -- value and unary negation. Unary "+" is omitted since it is a
9527 -- no-op and thus can't overflow.
9530 N_Op_Add,
9531 N_Op_Divide,
9532 N_Op_Expon,
9533 N_Op_Minus,
9534 N_Op_Multiply,
9535 N_Op_Subtract);
9538 ------------------------------
9539 -- Make_Array_Comparison_Op --
9540 ------------------------------
9542 -- This is a hand-coded expansion of the following generic function:
9544 -- generic
9545 -- type elem is (<>);
9546 -- type index is (<>);
9547 -- type a is array (index range <>) of elem;
9549 -- function Gnnn (X : a; Y: a) return boolean is
9550 -- J : index := Y'first;
9552 -- begin
9553 -- if X'length = 0 then
9554 -- return false;
9556 -- elsif Y'length = 0 then
9557 -- return true;
9559 -- else
9560 -- for I in X'range loop
9561 -- if X (I) = Y (J) then
9562 -- if J = Y'last then
9563 -- exit;
9564 -- else
9565 -- J := index'succ (J);
9566 -- end if;
9568 -- else
9569 -- return X (I) > Y (J);
9570 -- end if;
9571 -- end loop;
9573 -- return X'length > Y'length;
9574 -- end if;
9575 -- end Gnnn;
9577 -- Note that since we are essentially doing this expansion by hand, we
9578 -- do not need to generate an actual or formal generic part, just the
9579 -- instantiated function itself.
9581 function Make_Array_Comparison_Op
9584 is
9605 begin
9606 -- if J = Y'last then
9607 -- exit;
9608 -- else
9609 -- J := index'succ (J);
9610 -- end if;
9612 Inner_If :=
9614 Condition =>
9617 Right_Opnd =>
9625 Else_Statements =>
9626 New_List (
9629 Expression =>
9635 -- if X (I) = Y (J) then
9636 -- if ... end if;
9637 -- else
9638 -- return X (I) > Y (J);
9639 -- end if;
9641 Loop_Body :=
9643 Condition =>
9645 Left_Opnd =>
9650 Right_Opnd =>
9659 Expression =>
9661 Left_Opnd =>
9666 Right_Opnd =>
9672 -- for I in X'range loop
9673 -- if ... end if;
9674 -- end loop;
9676 Loop_Statement :=
9680 Iteration_Scheme =>
9682 Loop_Parameter_Specification =>
9685 Discrete_Subtype_Definition =>
9692 -- if X'length = 0 then
9693 -- return false;
9694 -- elsif Y'length = 0 then
9695 -- return true;
9696 -- else
9697 -- for ... loop ... end loop;
9698 -- return X'length > Y'length;
9699 -- end if;
9701 Length1 :=
9706 Length2 :=
9711 Final_Expr :=
9716 If_Stat :=
9718 Condition =>
9720 Left_Opnd =>
9724 Right_Opnd =>
9727 Then_Statements =>
9728 New_List (
9734 Condition =>
9736 Left_Opnd =>
9740 Right_Opnd =>
9743 Then_Statements =>
9744 New_List (
9749 Loop_Statement,
9753 -- (X : a; Y: a)
9764 -- function Gnnn (...) return boolean is
9765 -- J : index := Y'first;
9766 -- begin
9767 -- if ... end if;
9768 -- end Gnnn;
9772 Func_Body :=
9774 Specification =>
9784 Expression =>
9789 Handled_Statement_Sequence =>
9796 ---------------------------
9797 -- Make_Boolean_Array_Op --
9798 ---------------------------
9800 -- For logical operations on boolean arrays, expand in line the following,
9801 -- replacing 'and' with 'or' or 'xor' where needed:
9803 -- function Annn (A : typ; B: typ) return typ is
9804 -- C : typ;
9805 -- begin
9806 -- for J in A'range loop
9807 -- C (J) := A (J) op B (J);
9808 -- end loop;
9809 -- return C;
9810 -- end Annn;
9812 -- Here typ is the boolean array type
9814 function Make_Boolean_Array_Op
9817 is
9835 begin
9836 A_J :=
9841 B_J :=
9846 C_J :=
9852 Op :=
9858 Op :=
9863 else
9864 Op :=
9870 Loop_Statement :=
9874 Iteration_Scheme =>
9876 Loop_Parameter_Specification =>
9879 Discrete_Subtype_Definition =>
9901 Func_Body :=
9903 Specification =>
9914 Handled_Statement_Sequence =>
9917 Loop_Statement,
9924 ------------------------
9925 -- Rewrite_Comparison --
9926 ------------------------
9930 -- Set to True if first pass with Assume_Valid generates a warning in
9931 -- which case we skip the second pass to avoid warning overloaded.
9934 -- Set to Standard_True or Standard_False
9936 begin
9945 -- Now start looking at the comparison in detail. We potentially go
9946 -- through this loop twice. The first time, Assume_Valid is set False
9947 -- in the call to Compile_Time_Compare. If this call results in a
9948 -- clear result of always True or Always False, that's decisive and
9949 -- we are done. Otherwise we repeat the processing with Assume_Valid
9950 -- set to True to generate additional warnings. We can skip that step
9951 -- if Constant_Condition_Warnings is False.
9954 declare
9961 -- Res indicates if compare outcome can be compile time determined
9966 begin
9977 and then Constant_Condition_Warnings
9980 and then not In_Instance
9983 then
9984 Error_Msg_N
10002 and then Constant_Condition_Warnings
10005 and then not In_Instance
10008 then
10009 Error_Msg_N
10019 -- If this is the first iteration, then we actually convert the
10020 -- comparison into True or False, if the result is certain.
10026 else
10038 -- If this is the second iteration (AV = True), and the original
10039 -- node comes from source and we are not in an instance, then give
10040 -- a warning if we know result would be True or False. Note: we
10041 -- know Constant_Condition_Warnings is set if we get here.
10044 and then not In_Instance
10045 then
10047 Error_Msg_N
10049 N);
10051 Error_Msg_N
10053 N);
10058 -- Skip second iteration if not warning on constant conditions or
10059 -- if the first iteration already generated a warning of some kind or
10060 -- if we are in any case assuming all values are valid (so that the
10061 -- first iteration took care of the valid case).
10069 ----------------------------
10070 -- Safe_In_Place_Array_Op --
10071 ----------------------------
10073 function Safe_In_Place_Array_Op
10077 is
10081 -- Operand is safe if it cannot overlap part of the target of the
10082 -- operation. If the operand and the target are identical, the operand
10083 -- is safe. The operand can be empty in the case of negation.
10086 -- Check that N is a stand-alone entity
10088 ------------------
10089 -- Is_Unaliased --
10090 ------------------
10093 begin
10094 return
10100 ---------------------
10101 -- Is_Safe_Operand --
10102 ---------------------
10105 begin
10116 return
10123 else
10128 -- Start of processing for Is_Safe_In_Place_Array_Op
10130 begin
10131 -- Skip this processing if the component size is different from system
10132 -- storage unit (since at least for NOT this would cause problems).
10137 -- Cannot do in place stuff on VM_Target since cannot pass addresses
10142 -- Cannot do in place stuff if non-standard Boolean representation
10150 else
10156 -----------------------
10157 -- Tagged_Membership --
10158 -----------------------
10160 -- There are two different cases to consider depending on whether the right
10161 -- operand is a class-wide type or not. If not we just compare the actual
10162 -- tag of the left expr to the target type tag:
10163 --
10164 -- Left_Expr.Tag = Right_Type'Tag;
10165 --
10166 -- If it is a class-wide type we use the RT function CW_Membership which is
10167 -- usually implemented by looking in the ancestor tables contained in the
10168 -- dispatch table pointed by Left_Expr.Tag for Typ'Tag
10170 -- Ada 2005 (AI-251): If it is a class-wide interface type we use the RT
10171 -- function IW_Membership which is usually implemented by looking in the
10172 -- table of abstract interface types plus the ancestor table contained in
10173 -- the dispatch table pointed by Left_Expr.Tag for Typ'Tag
10175 procedure Tagged_Membership
10179 is
10189 begin
10192 -- Handle entities from the limited view
10201 Obj_Tag :=
10204 Selector_Name =>
10209 -- No need to issue a run-time check if we statically know that the
10210 -- result of this membership test is always true. For example,
10211 -- considering the following declarations:
10213 -- type Iface is interface;
10214 -- type T is tagged null record;
10215 -- type DT is new T and Iface with null record;
10217 -- Obj1 : T;
10218 -- Obj2 : DT;
10220 -- These membership tests are always true:
10222 -- Obj1 in T'Class
10223 -- Obj2 in T'Class;
10224 -- Obj2 in Iface'Class;
10226 -- We do not need to handle cases where the membership is illegal.
10227 -- For example:
10229 -- Obj1 in DT'Class; -- Compile time error
10230 -- Obj1 in Iface'Class; -- Compile time error
10235 and then Interface_Present_In_Ancestor
10238 then
10243 -- Ada 2005 (AI-251): Class-wide applied to interfaces
10247 -- Support to: "Iface_CW_Typ in Typ'Class"
10250 then
10251 -- Issue error if IW_Membership operation not available in a
10252 -- configurable run time setting.
10255 Error_Msg_CRT
10261 Result :=
10268 New_Reference_To (
10269 Node (First_Elmt
10271 Loc)));
10273 -- Ada 95: Normal case
10275 else
10278 Typ_Tag_Node =>
10279 New_Reference_To (
10280 Node (First_Elmt
10282 Loc),
10286 -- Generate the SCIL node for this class-wide membership test.
10287 -- Done here because the previous call to Build_CW_Membership
10288 -- relocates Obj_Tag.
10299 -- Right_Type is not a class-wide type
10301 else
10302 -- No need to check the tag of the object if Right_Typ is abstract
10307 else
10308 Result :=
10311 Right_Opnd =>
10312 New_Reference_To
10318 ------------------------------
10319 -- Unary_Op_Validity_Checks --
10320 ------------------------------
10323 begin