| blob | dcd4134a434a25e9610f7630bfb009a2b96080bf |
1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * U T I L S 2 *
6 * *
7 * C Implementation File *
8 * *
9 * Copyright (C) 1992-2017, 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 along with GCC; see the file COPYING3. If not see *
19 * <http://www.gnu.org/licenses/>. *
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 ****************************************************************************/
59 /* Return the base type of TYPE. */
61 tree
63 {
74 }
75 \f
76 /* EXP is a GCC tree representing an address. See if we can find how strictly
77 the object at this address is aligned and, if so, return the alignment of
78 the object in bits. Otherwise return 0. */
80 unsigned int
82 {
87 {
88 CASE_CONVERT:
91 /* Conversions between pointers and integers don't change the alignment
92 of the underlying object. */
97 /* The value of a COMPOUND_EXPR is that of its second operand. */
103 /* If two addresses are added, the alignment of the result is the
104 minimum of the two alignments. */
111 /* If this is the pattern built for aligning types, decode it. */
114 {
116 return
118 }
120 /* If we don't know the alignment of the offset, we assume that
121 of the base. */
127 else
132 /* If there is a choice between two values, use the smaller one. */
139 {
141 /* The first part of this represents the lowest bit in the constant,
142 but it is originally in bytes, not bits. */
144 }
148 /* If we know the alignment of just one side, use it. Otherwise,
149 use the product of the alignments. */
157 else
162 /* A bit-and expression is as aligned as the maximum alignment of the
163 operands. We typically get here for a complex lhs and a constant
164 negative power of two on the rhs to force an explicit alignment, so
165 don't bother looking at the lhs. */
174 {
182 }
184 /* ... fall through ... */
187 /* For other pointer expressions, we assume that the pointed-to object
188 is at least as aligned as the pointed-to type. Beware that we can
189 have a dummy type here (e.g. a Taft Amendment type), for which the
190 alignment is meaningless and should be ignored. */
195 else
198 }
201 }
202 \f
203 /* We have a comparison or assignment operation on two types, T1 and T2, which
204 are either both array types or both record types. T1 is assumed to be for
205 the left hand side operand, and T2 for the right hand side. Return the
206 type that both operands should be converted to for the operation, if any.
207 Otherwise return zero. */
209 static tree
211 {
212 /* ??? As of today, various constructs lead to here with types of different
213 sizes even when both constants (e.g. tagged types, packable vs regular
214 component types, padded vs unpadded types, ...). While some of these
215 would better be handled upstream (types should be made consistent before
216 calling into build_binary_op), some others are really expected and we
217 have to be careful. */
219 const bool variable_record_on_lhs
225 const bool variable_array_on_lhs
231 /* We must avoid writing more than what the target can hold if this is for
232 an assignment and the case of tagged types is handled in build_binary_op
233 so we use the lhs type if it is known to be smaller or of constant size
234 and the rhs type is not, whatever the modes. We also force t1 in case of
235 constant size equality to minimize occurrences of view conversions on the
236 lhs of an assignment, except for the case of types with a variable part
237 on the lhs but not on the rhs to make the conversion simpler. */
242 && !variable_record_on_lhs
246 /* Otherwise, if the lhs type is non-BLKmode, use it, except for the case of
247 a non-BLKmode rhs and array types with a variable part on the lhs but not
248 on the rhs to make sure the conversion is preserved during gimplification.
249 Note that we know that we will not have any alignment problems since, if
250 we did, the non-BLKmode type could not have been used. */
255 /* If the rhs type is of constant size, use it whatever the modes. At
256 this point it is known to be smaller, or of constant size and the
257 lhs type is not. */
261 /* Otherwise, if the rhs type is non-BLKmode, use it. */
265 /* In this case, both types have variable size and BLKmode. It's
266 probably best to leave the "type mismatch" because changing it
267 could cause a bad self-referential reference. */
269 }
270 \f
271 /* Return an expression tree representing an equality comparison of A1 and A2,
272 two objects of type ARRAY_TYPE. The result should be of type RESULT_TYPE.
274 Two arrays are equal in one of two ways: (1) if both have zero length in
275 some dimension (not necessarily the same dimension) or (2) if the lengths
276 in each dimension are equal and the data is equal. We perform the length
277 tests in as efficient a manner as possible. */
279 static tree
281 {
291 /* If the operands have side-effects, they need to be evaluated only once
292 in spite of the multiple references in the comparison. */
299 /* Process each dimension separately and compare the lengths. If any
300 dimension has a length known to be zero, set LENGTH_ZERO_P to true
301 in order to suppress the comparison of the data at the end. */
303 {
309 size_one_node);
311 size_one_node);
314 /* If the length of the first array is a constant, swap our operands
315 unless the length of the second array is the constant zero. */
317 {
318 tree tem;
329 }
331 /* If the length of the second array is the constant zero, we can just
332 use the original stored bounds for the first array and see whether
333 last < first holds. */
335 {
340 ub1
342 lb1
352 }
354 /* Otherwise, if the length is some other constant value, we know that
355 this dimension in the second array cannot be superflat, so we can
356 just use its length computed from the actual stored bounds. */
358 {
361 ub1
363 lb1
365 /* Note that we know that UB2 and LB2 are constant and hence
366 cannot contain a PLACEHOLDER_EXPR. */
367 ub2
369 lb2
372 comparison
380 this_a1_is_null
384 }
386 /* Otherwise, compare the computed lengths. */
387 else
388 {
392 comparison
395 /* If the length expression is of the form (cond ? val : 0), assume
396 that cond is equivalent to (length != 0). That's guaranteed by
397 construction of the array types in gnat_to_gnu_entity. */
400 this_a1_is_null
402 else
406 /* Likewise for the second array. */
409 this_a2_is_null
411 else
414 }
416 /* Append expressions for this dimension to the final expressions. */
428 }
430 /* Unless the length of some dimension is known to be zero, compare the
431 data in the array. */
433 {
435 tree comparison;
438 {
441 }
445 result
447 }
449 /* The result is also true if both sizes are zero. */
453 result);
455 /* If the operands have side-effects, they need to be evaluated before
456 doing the tests above since the place they otherwise would end up
457 being evaluated at run time could be wrong. */
465 }
467 /* Return an expression tree representing an equality comparison of P1 and P2,
468 two objects of fat pointer type. The result should be of type RESULT_TYPE.
470 Two fat pointers are equal in one of two ways: (1) if both have a null
471 pointer to the array or (2) if they contain the same couple of pointers.
472 We perform the comparison in as efficient a manner as possible. */
474 static tree
476 {
480 /* If either operand has side-effects, they have to be evaluated only once
481 in spite of the multiple references to the operand in the comparison. */
485 /* The constant folder doesn't fold fat pointer types so we do it here. */
488 else
491 p1_array_is_null
494 null_pointer_node));
498 else
501 p2_array_is_null
504 null_pointer_node));
506 /* If one of the pointers to the array is null, just compare the other. */
512 /* Otherwise, do the fully-fledged comparison. */
513 same_array
518 else
519 p1_bounds
525 else
526 p2_bounds
530 same_bounds
533 /* P1_ARRAY == P2_ARRAY && (P1_ARRAY == NULL || P1_BOUNDS == P2_BOUNDS). */
537 }
538 \f
539 /* Compute the result of applying OP_CODE to LHS and RHS, where both are of
540 type TYPE. We know that TYPE is a modular type with a nonbinary
541 modulus. */
543 static tree
545 tree rhs)
546 {
552 tree result;
554 /* If this is an addition of a constant, convert it to a subtraction
555 of a constant since we can do that faster. */
557 {
560 }
562 /* For the logical operations, we only need PRECISION bits. For
563 addition and subtraction, we need one more and for multiplication we
564 need twice as many. But we never want to make a size smaller than
565 our size. */
573 /* Unsigned will do for everything but subtraction. */
577 /* If our type is the wrong signedness or isn't wide enough, make a new
578 type and convert both our operands to it. */
581 {
582 /* Copy the type so we ensure it can be modified to make it modular. */
589 }
591 /* Do the operation, then we'll fix it up. */
594 /* For multiplication, we have no choice but to do a full modulus
595 operation. However, we want to do this in the narrowest
596 possible size. */
598 {
599 /* Copy the type so we ensure it can be modified to make it modular. */
607 }
609 /* For subtraction, add the modulus back if we are negative. */
611 {
617 result);
618 }
620 /* For the other operations, subtract the modulus if we are >= it. */
621 else
622 {
629 result);
630 }
633 }
634 \f
635 /* This page contains routines that implement the Ada semantics with regard
636 to atomic objects. They are fully piggybacked on the middle-end support
637 for atomic loads and stores.
639 *** Memory barriers and volatile objects ***
641 We implement the weakened form of the C.6(16) clause that was introduced
642 in Ada 2012 (AI05-117). Earlier forms of this clause wouldn't have been
643 implementable without significant performance hits on modern platforms.
645 We also take advantage of the requirements imposed on shared variables by
646 9.10 (conditions for sequential actions) to have non-erroneous execution
647 and consider that C.6(16) and C.6(17) only prescribe an uniform order of
648 volatile updates with regard to sequential actions, i.e. with regard to
649 reads or updates of atomic objects.
651 As such, an update of an atomic object by a task requires that all earlier
652 accesses to volatile objects have completed. Similarly, later accesses to
653 volatile objects cannot be reordered before the update of the atomic object.
654 So, memory barriers both before and after the atomic update are needed.
656 For a read of an atomic object, to avoid seeing writes of volatile objects
657 by a task earlier than by the other tasks, a memory barrier is needed before
658 the atomic read. Finally, to avoid reordering later reads or updates of
659 volatile objects to before the atomic read, a barrier is needed after the
660 atomic read.
662 So, memory barriers are needed before and after atomic reads and updates.
663 And, in order to simplify the implementation, we use full memory barriers
664 in all cases, i.e. we enforce sequential consistency for atomic accesses. */
666 /* Return the size of TYPE, which must be a positive power of 2. */
668 static unsigned int
670 {
676 /* We shouldn't reach here without having already detected that the size
677 isn't compatible with an atomic access. */
681 }
683 /* Build an atomic load for the underlying atomic object in SRC. SYNC is
684 true if the load requires synchronization. */
686 tree
688 {
689 tree ptr_type
690 = build_pointer_type
693 tree mem_model
701 /* Remove conversions to get the address of the underlying object. */
713 /* First reinterpret the loaded bits in the original type of the load,
714 then convert to the expected result type. */
717 }
719 /* Build an atomic store from SRC to the underlying atomic object in DEST.
720 SYNC is true if the store requires synchronization. */
722 tree
724 {
725 tree ptr_type
726 = build_pointer_type
729 tree mem_model
737 /* Remove conversions to get the address of the underlying object. */
747 /* First convert the bits to be stored to the original type of the store,
748 then reinterpret them in the effective type. But if the original type
749 is a padded type with the same size, convert to the inner type instead,
750 as we don't want to artificially introduce a CONSTRUCTOR here. */
755 else
761 }
763 /* Build a load-modify-store sequence from SRC to DEST. GNAT_NODE is used for
764 the location of the sequence. Note that, even though the load and the store
765 are both atomic, the sequence itself is not atomic. */
767 tree
769 {
770 /* We will be modifying DEST below so we build a copy. */
775 {
776 /* The load should already have been generated during the translation
777 of the GNAT destination tree; find it out in the GNU tree. */
779 {
782 {
787 /* Find out the loaded object. */
792 else
795 /* Drop atomic and volatile qualifiers for the temporary. */
798 /* And drop BLKmode, if need be, to put it into a register. */
800 {
805 }
807 /* Create the temporary by inserting a SAVE_EXPR. */
814 /* Build the modify of the temporary. */
818 /* Build the store to the object. */
823 }
824 }
828 }
830 /* Something went wrong earlier if we have not found the atomic load. */
832 }
833 \f
834 /* Make a binary operation of kind OP_CODE. RESULT_TYPE is the type
835 desired for the result. Usually the operation is to be performed
836 in that type. For INIT_EXPR and MODIFY_EXPR, RESULT_TYPE must be
837 NULL_TREE. For ARRAY_REF, RESULT_TYPE may be NULL_TREE, in which
838 case the type to be used will be derived from the operands.
839 Don't fold the result if NO_FOLD is true.
841 This function is very much unlike the ones for C and C++ since we
842 have already done any type conversion and matching required. All we
843 have to do here is validate the work done by SEM and handle subtypes. */
845 tree
849 {
869 modulus = (operation_type
875 {
880 /* If there were integral or pointer conversions on the LHS, remove
881 them; we'll be putting them back below if needed. Likewise for
882 conversions between array and record types, except for justified
883 modular types. But don't do this if the right operand is not
884 BLKmode (for packed arrays) unless we are not changing the mode. */
905 (TREE_OPERAND
907 {
910 }
912 /* If a class-wide type may be involved, force use of the RHS type. */
918 /* If we are copying between padded objects with compatible types, use
919 the padded view of the objects, this is very likely more efficient.
920 Likewise for a padded object that is assigned a constructor, if we
921 can convert the constructor to the inner type, to avoid putting a
922 VIEW_CONVERT_EXPR on the LHS. But don't do so if we wouldn't have
923 actually copied anything. */
928 == TYPE_MAIN_VARIANT
931 && !CONTAINS_PLACEHOLDER_P
934 {
935 /* We make an exception for a BLKmode type padding a non-BLKmode
936 inner type and do the conversion of the LHS right away, since
937 unchecked_convert wouldn't do it properly. */
941 {
945 }
946 else
948 }
950 /* If we have a call to a function that returns with variable size, use
951 the RHS type in case we want to use the return slot optimization. */
956 /* Find the best type to use for copying between aggregate types. */
964 /* Otherwise use the LHS type. */
965 else
968 /* Ensure everything on the LHS is valid. If we have a field reference,
969 strip anything that get_inner_reference can handle. Then remove any
970 conversions between types having the same code and mode. And mark
971 VIEW_CONVERT_EXPRs with TREE_ADDRESSABLE. When done, we must have
972 either an INDIRECT_REF, a NULL_EXPR, a SAVE_EXPR or a DECL node. */
975 {
995 {
998 }
999 else
1001 }
1008 /* Convert the right operand to the operation type unless it is
1009 either already of the correct type or if the type involves a
1010 placeholder, since the RHS may not have the same record type. */
1013 {
1016 }
1018 /* If the left operand is not of the same type as the operation
1019 type, wrap it up in a VIEW_CONVERT_EXPR. */
1031 /* ... fall through ... */
1034 /* First look through conversion between type variants. Note that
1035 this changes neither the operation type nor the type domain. */
1039 {
1042 }
1044 /* For a range, make sure the element type is consistent. */
1050 /* Then convert the right operand to its base type. This will prevent
1051 unneeded sign conversions when sizetype is wider than integer. */
1062 gcc_checking_assert
1075 gcc_checking_assert
1077 /* If either operand is a NULL_EXPR, just return a new one. */
1082 integer_zero_node);
1088 integer_zero_node);
1090 /* If either object is a justified modular types, get the
1091 fields from within. */
1094 {
1096 left_operand);
1099 }
1103 {
1105 right_operand);
1108 }
1110 /* If both objects are arrays, compare them specially. */
1117 {
1122 else
1126 }
1128 /* Otherwise, the base types must be the same, unless they are both fat
1129 pointer types or record types. In the latter case, use the best type
1130 and convert both operands to that type. */
1132 {
1135 {
1139 }
1143 {
1144 /* The only way this is permitted is if both types have the same
1145 name. In that case, one of them must not be self-referential.
1146 Use it as the best type. Even better with a fixed size. */
1159 else
1161 }
1165 {
1169 }
1170 else
1175 }
1176 else
1177 {
1180 }
1182 /* If both objects are fat pointers, compare them specially. */
1184 {
1185 result
1190 else
1194 }
1203 /* The RHS of a shift can be any type. Also, ignore any modulus
1204 (we used to abort, but this is needed for unchecked conversion
1205 to modular types). Otherwise, processing is the same as normal. */
1214 /* For binary modulus, if the inputs are in range, so are the
1215 outputs. */
1231 /* These always produce results lower than either operand. */
1246 else
1250 /* ... fall through ... */
1254 /* Avoid doing arithmetics in ENUMERAL_TYPE or BOOLEAN_TYPE like the
1255 other compilers. Contrary to C, Ada doesn't allow arithmetics in
1256 these types but can generate addition/subtraction for Succ/Pred. */
1264 /* ... fall through ... */
1267 common:
1268 /* The result type should be the same as the base types of the
1269 both operands (and they should be the same). Convert
1270 everything to the result type. */
1276 }
1279 {
1283 }
1284 /* If either operand is a NULL_EXPR, just return a new one. */
1290 {
1295 }
1300 else
1301 result
1305 ;
1307 {
1310 }
1311 else
1317 /* If we are working with modular types, perform the MOD operation
1318 if something above hasn't eliminated the need for it. */
1320 {
1324 else
1326 }
1332 }
1333 \f
1334 /* Similar, but for unary operations. */
1336 tree
1338 {
1342 tree result;
1355 {
1360 else
1367 gcc_checking_assert
1370 /* When not optimizing, fold the result as invert_truthvalue_loc
1371 doesn't fold the result of comparisons. This is intended to undo
1372 the trick used for boolean rvalues in gnat_to_gnu. */
1380 {
1385 /* Make sure the type here is a pointer, not a reference.
1386 GCC wants pointer types for function addresses. */
1390 /* If the underlying object can alias everything, propagate the
1391 property since we are effectively retrieving the object. */
1394 {
1397 result_type
1403 result_type
1407 }
1416 /* Fold a compound expression if it has unconstrained array type
1417 since the middle-end cannot handle it. But we don't it in the
1418 general case because it may introduce aliasing issues if the
1419 first operand is an indirect assignment and the second operand
1420 the corresponding address, e.g. for an allocator. However do
1421 it for a return value to expose it for later recognition. */
1425 {
1431 }
1438 /* If this is for 'Address, find the address of the prefix and add
1439 the offset to the field. Otherwise, do this the normal way. */
1441 {
1442 HOST_WIDE_INT bitsize;
1443 HOST_WIDE_INT bitpos;
1445 machine_mode mode;
1452 /* If INNER is a padding type whose field has a self-referential
1453 size, convert to that inner type. We know the offset is zero
1454 and we need to have that type visible. */
1457 inner);
1459 /* Compute the offset as a byte offset from INNER. */
1466 /* Take the address of INNER, convert it to a pointer to our type
1467 and add the offset. */
1470 inner);
1474 }
1478 /* If this is just a constructor for a padded record, we can
1479 just take the address of the single field and convert it to
1480 a pointer to our type. */
1482 {
1483 result
1488 }
1497 /* ... fallthru ... */
1500 /* If this just a variant conversion or if the conversion doesn't
1501 change the mode, get the result type from this type and go down.
1502 This is needed for conversions of CONST_DECLs, to eventually get
1503 to the address of their CORRESPONDING_VARs. */
1518 /* ... fall through ... */
1521 common:
1523 /* If we are taking the address of a padded record whose field
1524 contains a template, take the address of the field. */
1528 {
1531 }
1535 }
1541 {
1545 /* If TYPE is a thin pointer, either first retrieve the base if this
1546 is an expression with an offset built for the initialization of an
1547 object with an unconstrained nominal subtype, or else convert to
1548 the fat pointer. */
1550 {
1557 {
1560 }
1562 {
1563 operand
1565 operand);
1567 }
1568 }
1570 /* If we want to refer to an unconstrained array, use the appropriate
1571 expression. But this will never survive down to the back-end. */
1573 {
1578 }
1580 /* If we are dereferencing an ADDR_EXPR, return its operand. */
1584 /* Otherwise, build and fold the indirect reference. */
1585 else
1586 {
1589 }
1592 {
1596 }
1604 }
1608 {
1609 tree modulus = ((operation_type
1615 /* If this is a modular type, there are various possibilities
1616 depending on the operation and whether the modulus is a
1617 power of two or not. */
1620 {
1624 /* The fastest in the negate case for binary modulus is
1625 the straightforward code; the TRUNC_MOD_EXPR below
1626 is an AND operation. */
1630 operand),
1631 modulus);
1633 /* For nonbinary negate case, return zero for zero operand,
1634 else return the modulus minus the operand. If the modulus
1635 is a power of two minus one, we can do the subtraction
1636 as an XOR since it is equivalent and faster on most machines. */
1638 {
1640 modulus,
1645 else
1651 boolean_type_node,
1652 operand,
1653 build_int_cst
1656 }
1657 else
1658 {
1659 /* For the NOT cases, we need a constant equal to
1660 the modulus minus one. For a binary modulus, we
1661 XOR against the constant and subtract the operand from
1662 that constant for nonbinary modulus. */
1670 else
1673 }
1676 }
1677 }
1679 /* ... fall through ... */
1685 }
1691 }
1692 \f
1693 /* Similar, but for COND_EXPR. */
1695 tree
1698 {
1700 tree result;
1702 /* The front-end verified that result, true and false operands have
1703 same base type. Convert everything to the result type. */
1707 /* If the result type is unconstrained, take the address of the operands and
1708 then dereference the result. Likewise if the result type is passed by
1709 reference, because creating a temporary of this type is not allowed. */
1713 {
1718 }
1723 /* If we have a common SAVE_EXPR (possibly surrounded by arithmetics)
1724 in both arms, make sure it gets evaluated by moving it ahead of the
1725 conditional expression. This is necessary because it is evaluated
1726 in only one place at run time and would otherwise be uninitialized
1727 in one of the arms. */
1738 }
1740 /* Similar, but for COMPOUND_EXPR. */
1742 tree
1744 {
1746 tree result;
1748 /* If the result type is unconstrained, take the address of the operand and
1749 then dereference the result. Likewise if the result type is passed by
1750 reference, but this is natively handled in the gimplifier. */
1753 {
1757 }
1760 expr_operand);
1766 }
1767 \f
1768 /* Conveniently construct a function call expression. FNDECL names the
1769 function to be called, N is the number of arguments, and the "..."
1770 parameters are the argument expressions. Unlike build_call_expr
1771 this doesn't fold the call, hence it will always return a CALL_EXPR. */
1773 tree
1775 {
1784 }
1785 \f
1786 /* Build a goto to LABEL for a raise, with an optional call to Local_Raise.
1787 MSG gives the exception's identity for the call to Local_Raise, if any. */
1789 static tree
1791 {
1796 /* If Local_Raise is present, build Local_Raise (Exception'Identity). */
1798 {
1799 tree gnu_local_raise
1801 tree gnu_exception_entity
1803 tree gnu_call
1806 gnu_exception_entity));
1807 gnu_result
1809 }
1813 }
1815 /* Expand the SLOC of GNAT_NODE, if present, into tree location information
1816 pointed to by FILENAME, LINE and COL. Fall back to the current location
1817 if GNAT_NODE is absent or has no SLOC. */
1819 static void
1821 {
1826 {
1830 }
1832 {
1833 str = Get_Name_String
1837 }
1838 else
1839 {
1843 }
1852 }
1854 /* Build a call to a function that raises an exception and passes file name
1855 and line number, if requested. MSG says which exception function to call.
1856 GNAT_NODE is the node conveying the source location for which the error
1857 should be signaled, or Empty in which case the error is signaled for the
1858 current location. KIND says which kind of exception node this is for,
1859 among N_Raise_{Constraint,Storage,Program}_Error. */
1861 tree
1863 {
1868 /* If this is to be done as a goto, handle that case. */
1874 return
1878 filename),
1879 line);
1880 }
1882 /* Similar to build_call_raise, with extra information about the column
1883 where the check failed. */
1885 tree
1887 {
1892 /* If this is to be done as a goto, handle that case. */
1898 return
1902 filename),
1904 }
1906 /* Similar to build_call_raise_column, for an index or range check exception ,
1907 with extra information of the form "INDEX out of range FIRST..LAST". */
1909 tree
1912 {
1917 /* If this is to be done as a goto, handle that case. */
1923 return
1927 filename),
1932 }
1933 \f
1934 /* qsort comparer for the bit positions of two constructor elements
1935 for record components. */
1937 static int
1939 {
1944 const int ret
1948 }
1950 /* Return a CONSTRUCTOR of TYPE whose elements are V. */
1952 tree
1954 {
1961 /* Scan the elements to see if they are all constant or if any has side
1962 effects, to let us set global flags on the resulting constructor. Count
1963 the elements along the way for possible sorting purposes below. */
1965 {
1966 /* The predicate must be in keeping with output_constructor. */
1981 }
1983 /* For record types with constant components only, sort field list
1984 by increasing bit position. This is necessary to ensure the
1985 constructor can be output as static data. */
1995 }
1996 \f
1997 /* Return a COMPONENT_REF to access FIELD in RECORD, or NULL_TREE if the field
1998 is not found in the record. Don't fold the result if NO_FOLD is true. */
2000 static tree
2002 {
2004 tree ref;
2008 /* Try to fold a conversion from another record or union type unless the type
2009 contains a placeholder as it might be needed for a later substitution. */
2013 {
2016 /* If this is an unpadding operation, convert the underlying object to
2017 the unpadded type directly. */
2021 /* Otherwise try to access FIELD directly in the underlying type, but
2022 make sure that the form of the reference doesn't change too much;
2023 this can happen for an unconstrained bit-packed array type whose
2024 constrained form can be an integer type. */
2028 }
2030 /* If this field is not in the specified record, see if we can find a field
2031 in the specified record whose original field is the same as this one. */
2033 {
2034 tree new_field;
2036 /* First loop through normal components. */
2038 new_field;
2043 /* Next, loop through DECL_INTERNAL_P components if we haven't found the
2044 component in the first search. Doing this search in two steps is
2045 required to avoid hidden homonymous fields in the _Parent field. */
2048 new_field;
2052 {
2053 tree field_ref
2058 }
2061 }
2066 /* If the field's offset has overflowed, do not try to access it, as doing
2067 so may trigger sanity checks deeper in the back-end. Note that we don't
2068 need to warn since this will be done on trying to declare the object. */
2088 /* The generic folder may punt in this case because the inner array type
2089 can be self-referential, but folding is in fact not problematic. */
2092 {
2100 }
2103 }
2105 /* Likewise, but return NULL_EXPR and generate a Constraint_Error if the
2106 field is not found in the record. */
2108 tree
2110 {
2115 /* Assume this is an invalid user field so raise Constraint_Error. */
2118 N_Raise_Constraint_Error));
2119 }
2120 \f
2121 /* Helper for build_call_alloc_dealloc, with arguments to be interpreted
2122 identically. Process the case where a GNAT_PROC to call is provided. */
2127 {
2129 tree gnu_call;
2131 /* A storage pool's underlying type is a record type (for both predefined
2132 storage pools and GNAT simple storage pools). The secondary stack uses
2133 the same mechanism, but its pool object (SS_Pool) is an integer. */
2135 {
2136 /* The size is the third parameter; the alignment is the
2137 same type. */
2138 Entity_Id gnat_size_type
2149 /* The first arg is always the address of the storage pool; next
2150 comes the address of the object, for a deallocator, then the
2151 size and alignment. */
2155 else
2158 }
2160 /* Secondary stack case. */
2161 else
2162 {
2163 /* The size is the second parameter. */
2164 Entity_Id gnat_size_type
2170 /* The first arg is the address of the object, for a deallocator,
2171 then the size. */
2174 else
2176 }
2179 }
2181 /* Helper for build_call_alloc_dealloc, to build and return an allocator for
2182 DATA_SIZE bytes aimed at containing a DATA_TYPE object, using the default
2183 __gnat_malloc allocator. Honor DATA_TYPE alignments greater than what the
2184 latter offers. */
2188 {
2189 /* When the DATA_TYPE alignment is stricter than what malloc offers
2190 (super-aligned case), we allocate an "aligning" wrapper type and return
2191 the address of its single data field with the malloc's return value
2192 stored just in front. */
2195 unsigned int system_allocator_alignment
2198 tree aligning_type
2201 system_allocator_alignment,
2203 gnat_node)
2206 tree size_to_malloc
2212 {
2213 /* Latch malloc's return value and get a pointer to the aligning field
2214 first. */
2217 tree aligning_record_addr
2220 tree aligning_record
2223 tree aligning_field
2227 tree aligning_field_addr
2230 /* Then arrange to store the allocator's return value ahead
2231 and return. */
2232 tree storage_ptr_slot_addr
2238 tree storage_ptr_slot
2241 storage_ptr_slot_addr));
2243 return
2247 aligning_field_addr);
2248 }
2249 else
2251 }
2253 /* Helper for build_call_alloc_dealloc, to release a DATA_TYPE object
2254 designated by DATA_PTR using the __gnat_free entry point. */
2258 {
2259 /* In the regular alignment case, we pass the data pointer straight to free.
2260 In the superaligned case, we need to retrieve the initial allocator
2261 return value, stored in front of the data block at allocation time. */
2264 unsigned int system_allocator_alignment
2267 tree free_ptr;
2270 {
2271 /* DATA_FRONT_PTR (void *)
2272 = (void *)DATA_PTR - (void *)sizeof (void *)) */
2273 tree data_front_ptr
2274 = build_binary_op
2279 /* FREE_PTR (void *) = *(void **)DATA_FRONT_PTR */
2280 free_ptr
2281 = build_unary_op
2284 }
2285 else
2289 }
2291 /* Build a GCC tree to call an allocation or deallocation function.
2292 If GNU_OBJ is nonzero, it is an object to deallocate. Otherwise,
2293 generate an allocator.
2295 GNU_SIZE is the number of bytes to allocate and GNU_TYPE is the contained
2296 object type, used to determine the to-be-honored address alignment.
2297 GNAT_PROC, if present, is a procedure to call and GNAT_POOL is the storage
2298 pool to use. If not present, malloc and free are used. GNAT_NODE is used
2299 to provide an error location for restriction violation messages. */
2301 tree
2304 Node_Id gnat_node)
2305 {
2306 /* Explicit proc to call ? This one is assumed to deal with the type
2307 alignment constraints. */
2312 /* Otherwise, object to "free" or "malloc" with possible special processing
2313 for alignments stricter than what the default allocator honors. */
2316 else
2317 {
2318 /* Assert that we no longer can be called with this special pool. */
2321 /* Check that we aren't violating the associated restriction. */
2323 {
2329 }
2331 }
2332 }
2333 \f
2334 /* Build a GCC tree that corresponds to allocating an object of TYPE whose
2335 initial value is INIT, if INIT is nonzero. Convert the expression to
2336 RESULT_TYPE, which must be some pointer type, and return the result.
2338 GNAT_PROC and GNAT_POOL optionally give the procedure to call and
2339 the storage pool to use. GNAT_NODE is used to provide an error
2340 location for restriction violation messages. If IGNORE_INIT_TYPE is
2341 true, ignore the type of INIT for the purpose of determining the size;
2342 this will cause the maximum size to be allocated if TYPE is of
2343 self-referential size. */
2345 tree
2348 {
2351 /* If the initializer, if present, is a NULL_EXPR, just return a new one. */
2355 /* If we are just annotating types, also return a NULL_EXPR. */
2359 N_Raise_Constraint_Error));
2361 /* If the initializer, if present, is a COND_EXPR, deal with each branch. */
2366 ignore_init_type),
2369 ignore_init_type));
2371 /* If RESULT_TYPE is a fat or thin pointer, set SIZE to be the sum of the
2372 sizes of the object and its template. Allocate the whole thing and
2373 fill in the parts that are known. */
2375 {
2376 tree storage_type
2383 init);
2385 /* If the size overflows, pass -1 so Storage_Error will be raised. */
2395 /* If there is an initializing expression, then make a constructor for
2396 the entire object including the bounds and copy it into the object.
2397 If there is no initializing expression, just set the bounds. */
2399 {
2406 init);
2407 storage_init
2410 }
2411 else
2412 storage_init
2421 }
2425 /* If we have an initializing expression, see if its size is simpler
2426 than the size from the type. */
2432 /* If the size is still self-referential, reference the initializing
2433 expression, if it is present. If not, this must have been a
2434 call to allocate a library-level object, in which case we use
2435 the maximum size. */
2437 {
2440 else
2442 }
2444 /* If the size overflows, pass -1 so Storage_Error will be raised. */
2451 gnat_node));
2453 /* If we have an initial value, protect the new address, assign the value
2454 and return the address with a COMPOUND_EXPR. */
2456 {
2460 storage_init
2463 }
2466 }
2467 \f
2468 /* Indicate that we need to take the address of T and that it therefore
2469 should not be allocated in a register. Return true if successful. */
2471 bool
2473 {
2476 {
2485 CASE_CONVERT:
2513 }
2514 }
2515 \f
2516 /* Return true if EXP is a stable expression for the purpose of the functions
2517 below and, therefore, can be returned unmodified by them. We accept things
2518 that are actual constants or that have already been handled. */
2520 static bool
2522 {
2525 }
2527 /* Save EXP for later use or reuse. This is equivalent to save_expr in tree.c
2528 but we know how to handle our own nodes. */
2530 tree
2532 {
2540 {
2544 }
2546 /* If this is a COMPONENT_REF of a fat pointer, save the entire fat pointer.
2547 This may be more efficient, but will also allow us to more easily find
2548 the match for the PLACEHOLDER_EXPR. */
2555 }
2557 /* Protect EXP for immediate reuse. This is a variant of gnat_save_expr that
2558 is optimized under the assumption that EXP's value doesn't change before
2559 its subsequent reuse(s) except through its potential reevaluation. */
2561 tree
2563 {
2570 /* If EXP has no side effects, we theoretically don't need to do anything.
2571 However, we may be recursively passed more and more complex expressions
2572 involving checks which will be reused multiple times and eventually be
2573 unshared for gimplification; in order to avoid a complexity explosion
2574 at that point, we protect any expressions more complex than a simple
2575 arithmetic expression. */
2577 {
2581 }
2583 /* If this is a conversion, protect what's inside the conversion. */
2589 /* If we're indirectly referencing something, we only need to protect the
2590 address since the data itself can't change in these situations. */
2592 {
2596 }
2598 /* Likewise if we're indirectly referencing part of something. */
2604 /* If this is a COMPONENT_REF of a fat pointer, save the entire fat pointer.
2605 This may be more efficient, but will also allow us to more easily find
2606 the match for the PLACEHOLDER_EXPR. */
2612 /* If this is a fat pointer or a scalar, just make a SAVE_EXPR. Likewise
2613 for a CALL_EXPR as large objects are returned via invisible reference
2614 in most ABIs so the temporary will directly be filled by the callee. */
2620 /* Otherwise reference, protect the address and dereference. */
2621 return
2624 }
2626 /* This is equivalent to stabilize_reference_1 in tree.c but we take an extra
2627 argument to force evaluation of everything. */
2629 static tree
2631 {
2635 tree result;
2641 {
2648 /* If this is a COMPONENT_REF of a fat pointer, save the entire
2649 fat pointer. This may be more efficient, but will also allow
2650 us to more easily find the match for the PLACEHOLDER_EXPR. */
2653 result
2657 /* If the expression has side-effects, then encase it in a SAVE_EXPR
2658 so that it will only be evaluated once. */
2659 /* The tcc_reference and tcc_comparison classes could be handled as
2660 below, but it is generally faster to only evaluate them once. */
2663 else
2668 /* Recursively stabilize each operand. */
2669 result
2676 /* Recursively stabilize each operand. */
2677 result
2684 }
2691 }
2693 /* This is equivalent to stabilize_reference in tree.c but we know how to
2694 handle our own nodes and we take extra arguments. FORCE says whether to
2695 force evaluation of everything in REF. INIT is set to the first arm of
2696 a COMPOUND_EXPR present in REF, if any. */
2698 tree
2700 {
2701 return
2703 }
2705 /* Rewrite reference REF and call FUNC on each expression within REF in the
2706 process. DATA is passed unmodified to FUNC. INIT is set to the first
2707 arm of a COMPOUND_EXPR present in REF, if any. */
2709 tree
2711 {
2714 tree result;
2717 {
2722 /* No action is needed in this case. */
2725 CASE_CONVERT:
2731 result
2734 init));
2759 result
2762 init),
2770 /* We expect only the pattern built in Call_to_gnu. */
2777 {
2778 /* This can only be an atomic load. */
2781 /* An atomic load is an INDIRECT_REF of its first argument. */
2788 init));
2789 else
2795 }
2804 }
2806 /* TREE_THIS_VOLATILE and TREE_SIDE_EFFECTS set on the initial expression
2807 may not be sustained across some paths, such as the way via build1 for
2808 INDIRECT_REF. We reset those flags here in the general case, which is
2809 consistent with the GCC version of this routine.
2811 Special care should be taken regarding TREE_SIDE_EFFECTS, because some
2812 paths introduce side-effects where there was none initially (e.g. if a
2813 SAVE_EXPR is built) and we also want to keep track of that. */
2825 }
2827 /* This is equivalent to get_inner_reference in expr.c but it returns the
2828 ultimate containing object only if the reference (lvalue) is constant,
2829 i.e. if it doesn't depend on the context in which it is evaluated. */
2831 tree
2833 {
2835 {
2837 {
2848 {
2857 }
2867 }
2870 }
2872 done:
2874 }
2876 /* Return true if EXPR is the addition or the subtraction of a constant and,
2877 if so, set *ADD to the addend, *CST to the constant and *MINUS_P to true
2878 if this is a subtraction. */
2880 bool
2882 {
2883 /* Skip overflow checks. */
2892 {
2894 {
2899 }
2901 {
2906 }
2907 }
2909 {
2911 {
2916 }
2917 }
2920 }
2922 /* If EXPR is an expression that is invariant in the current function, in the
2923 sense that it can be evaluated anywhere in the function and any number of
2924 times, return EXPR or an equivalent expression. Otherwise return NULL. */
2926 tree
2928 {
2935 /* Look through temporaries created to capture values. */
2940 {
2942 /* Look into CONSTRUCTORs built to initialize padded types. */
2946 }
2948 /* We are only interested in scalar types at the moment and, even if we may
2949 have gone through padding types in the above loop, we must be back to a
2950 scalar value at this point. */
2957 /* Deal with addition or subtraction of constants. */
2959 {
2962 return
2965 else
2967 }
2973 {
2975 {
2990 CASE_CONVERT:
3001 }
3004 }
3006 object:
3027 }