| blob | cfc9fbc3faac157b70dc7d3418eeef7f807aab0c |
1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * T R A N S *
6 * *
7 * C Implementation File *
8 * *
9 * Copyright (C) 1992-2009, 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 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 ****************************************************************************/
63 /* We should avoid allocating more than ALLOCA_THRESHOLD bytes via alloca,
64 for fear of running out of stack space. If we need more, we use xmalloc
65 instead. */
66 #define ALLOCA_THRESHOLD 1000
68 /* Let code below know whether we are targetting VMS without need of
69 intrusive preprocessor directives. */
70 #ifndef TARGET_ABI_OPEN_VMS
71 #define TARGET_ABI_OPEN_VMS 0
72 #endif
74 /* For efficient float-to-int rounding, it is necessary to know whether
75 floating-point arithmetic may use wider intermediate results. When
76 FP_ARITH_MAY_WIDEN is not defined, be conservative and only assume
77 that arithmetic does not widen if double precision is emulated. */
78 #ifndef FP_ARITH_MAY_WIDEN
79 #if defined(HAVE_extendsfdf2)
80 #define FP_ARITH_MAY_WIDEN HAVE_extendsfdf2
81 #else
82 #define FP_ARITH_MAY_WIDEN 0
83 #endif
84 #endif
100 /* Current filename without path. */
103 /* True when gigi is being called on an analyzed but unexpanded
104 tree, and the only purpose of the call is to properly annotate
105 types with representation information. */
108 /* When not optimizing, we cache the 'First, 'Last and 'Length attributes
109 of unconstrained array IN parameters to avoid emitting a great deal of
110 redundant instructions to recompute them each time. */
114 tree first;
115 tree last;
116 tree length;
117 };
126 };
128 #define f_parm_attr_cache \
129 DECL_STRUCT_FUNCTION (current_function_decl)->language->parm_attr_cache
131 /* A structure used to gather together information about a statement group.
132 We use this to gather related statements, for example the "then" part
133 of a IF. In the case where it represents a lexical scope, we may also
134 have a BLOCK node corresponding to it and/or cleanups. */
141 };
145 /* List of unused struct stmt_group nodes. */
148 /* A structure used to record information on elaboration procedures
149 we've made and need to process.
151 ??? gnat_node should be Node_Id, but gengtype gets confused. */
157 };
161 /* Free list of TREE_LIST nodes used for stacks. */
164 /* List of TREE_LIST nodes representing a stack of exception pointer
165 variables. TREE_VALUE is the VAR_DECL that stores the address of
166 the raised exception. Nonzero means we are in an exception
167 handler. Not used in the zero-cost case. */
170 /* List of TREE_LIST nodes used to store the current elaboration procedure
171 decl. TREE_VALUE is the decl. */
174 /* Variable that stores a list of labels to be used as a goto target instead of
175 a return in some functions. See processing for N_Subprogram_Body. */
178 /* List of TREE_LIST nodes representing a stack of LOOP_STMT nodes.
179 TREE_VALUE of each entry is the label of the corresponding LOOP_STMT. */
182 /* List of TREE_LIST nodes representing labels for switch statements.
183 TREE_VALUE of each entry is the label at the end of the switch. */
186 /* List of TREE_LIST nodes containing the stacks for N_{Push,Pop}_*_Label. */
191 /* Map GNAT tree codes to GCC tree codes for simple expressions. */
194 /* Current node being treated, in case abort called. */
195 Node_Id error_gnat_node;
230 /* Hooks for debug info back-ends, only supported and used in a restricted set
231 of configurations. */
234 \f
235 /* This is the main program of the back-end. It sets up all the table
236 structures and then generates code. */
238 void
247 {
248 Entity_Id gnat_literal;
270 /* Declare the name of the compilation unit as the first global
271 name in order to make the middle-end fully deterministic. */
276 {
277 /* Use the identifier table to make a permanent copy of the filename as
278 the name table gets reallocated after Gigi returns but before all the
279 debugging information is output. The __gnat_to_canonical_file_spec
280 call translates filenames from pragmas Source_Reference that contain
281 host style syntax not understood by gdb. */
283 = IDENTIFIER_POINTER
284 (get_identifier
285 (__gnat_to_canonical_file_spec
288 /* We rely on the order isomorphism between files and line maps. */
291 /* We create the line map for a source file at once, with a fixed number
292 of columns chosen to avoid jumping over the next power of 2. */
297 }
299 /* Initialize ourselves. */
304 /* If we are just annotating types, give VOID_TYPE zero sizes to avoid
305 errors. */
307 {
310 }
312 /* If the GNU type extensions to DWARF are available, setup the hooks. */
313 #if defined (DWARF2_DEBUGGING_INFO) && defined (DWARF2_GNU_TYPE_EXTENSIONS)
314 /* We condition the name demangling and the generation of type encoding
315 strings on -gdwarf+ and always set descriptive types on. */
317 {
320 }
322 #endif
324 /* Enable GNAT stack checking method if needed */
328 /* Record the builtin types. Define `integer' and `unsigned char' first so
329 that dbx will output them first. */
339 /* Save the type we made for integer as the type for Standard.Integer. */
343 /* Save the type we made for boolean as the type for Standard.Boolean. */
366 /* Now declare runtime functions. */
369 /* malloc is a function declaration tree for a function to allocate
370 memory. */
371 malloc_decl
379 /* malloc32 is a function declaration tree for a function to allocate
380 32-bit memory on a 64-bit system. Needed only on 64-bit VMS. */
381 malloc32_decl
389 /* free is a function declaration tree for a function to free memory. */
390 free_decl
394 ptr_void_type_node,
395 t)),
398 /* This is used for 64-bit multiplication with overflow checking. */
399 mulv64_decl
405 /* Make the types and functions used for exception processing. */
406 jmpbuf_type
412 /* Functions to get and set the jumpbuf pointer for the current thread. */
413 get_jmpbuf_decl
414 = create_subprog_decl
418 /* Avoid creating superfluous edges to __builtin_setjmp receivers. */
421 set_jmpbuf_decl
422 = create_subprog_decl
424 NULL_TREE,
429 /* setjmp returns an integer and has one operand, which is a pointer to
430 a jmpbuf. */
431 setjmp_decl
432 = create_subprog_decl
441 /* update_setjmp_buf updates a setjmp buffer from the current stack pointer
442 address. */
443 update_setjmp_buf_decl
444 = create_subprog_decl
453 /* Hooks to call when entering/leaving an exception handler. */
454 begin_handler_decl
458 ptr_void_type_node,
459 t)),
462 end_handler_decl
466 ptr_void_type_node,
467 t)),
470 /* If in no exception handlers mode, all raise statements are redirected to
471 __gnat_last_chance_handler. No need to redefine raise_nodefer_decl since
472 this procedure will never be called in this mode. */
474 {
475 tree decl
476 = create_subprog_decl
482 integer_type_node,
483 t))),
488 }
489 else
490 /* Otherwise, make one decl for each exception reason. */
492 {
497 = create_subprog_decl
501 build_pointer_type
504 integer_type_node,
505 t))),
507 }
510 {
515 TYPE_QUAL_VOLATILE);
516 }
518 /* Set the types that GCC and Gigi use from the front end. We would
519 like to do this for char_type_node, but it needs to correspond to
520 the C char type. */
521 exception_type
525 /* Make other functions used for exception processing. */
526 get_excptr_decl
527 = create_subprog_decl
529 NULL_TREE,
532 /* Avoid creating superfluous edges to __builtin_setjmp receivers. */
535 raise_nodefer_decl
536 = create_subprog_decl
541 t)),
544 /* Indicate that these never return. */
549 TYPE_QUAL_VOLATILE);
551 /* Build the special descriptor type and its null node if needed. */
553 {
561 {
567 }
572 }
574 long_long_float_type
578 {
579 /* In this case, the builtin floating point types are VAX float,
580 so make up a type for use. */
585 }
586 else
589 /* Dummy objects to materialize "others" and "all others" in the exception
590 tables. These are exported by a-exexpr.adb, so see this unit for the
591 types to use. */
592 others_decl
597 all_others_decl
604 /* Install the builtins we might need, either internally or as
605 user available facilities for Intrinsic imports. */
609 gnu_constraint_error_label_stack
614 /* Process any Pragma Ident for the main unit. */
615 #ifdef ASM_OUTPUT_IDENT
617 ASM_OUTPUT_IDENT
620 #endif
622 /* If we are using the GCC exception mechanism, let GCC know. */
626 /* Now translate the compilation unit proper. */
630 /* Finally see if we have any elaboration procedures to deal with. */
632 {
635 /* Unshare SAVE_EXPRs between subprograms. These are not unshared by
636 the gimplifier for obvious reasons, but it turns out that we need to
637 unshare them for the global level because of SAVE_EXPRs made around
638 checks for global objects and around allocators for global objects
639 of variable size, in order to prevent node sharing in the underlying
640 expression. Note that this implicitly assumes that the SAVE_EXPR
641 nodes themselves are not shared between subprograms, which would be
642 an upstream bug for which we would not change the outcome. */
645 /* Process the function as others, but for indicating this is an
646 elab proc, to be discarded if empty, then propagate the status
647 up to the GNAT tree node. */
653 }
655 /* We cannot track the location of errors past this point. */
657 }
658 \f
659 /* Return a positive value if an lvalue is required for GNAT_NODE.
660 GNU_TYPE is the type that will be used for GNAT_NODE in the
661 translated GNU tree. ALIASED indicates whether the underlying
662 object represented by GNAT_NODE is aliased in the Ada sense.
664 The function climbs up the GNAT tree starting from the node and
665 returns 1 upon encountering a node that effectively requires an
666 lvalue downstream. It returns int instead of bool to facilitate
667 usage in non purely binary logic contexts. */
669 static int
671 {
675 {
680 {
686 }
694 /* Only the array expression can require an lvalue. */
698 /* ??? Consider that referencing an indexed component with a
699 non-constant index forces the whole aggregate to memory.
700 Note that N_Integer_Literal is conservative, any static
701 expression in the RM sense could probably be accepted. */
708 /* ... fall through ... */
711 /* Only the array expression can require an lvalue. */
723 /* We need to make a real renaming only if the constant object is
724 aliased or if we may use a renaming pointer; otherwise we can
725 optimize and return the rvalue. We make an exception if the object
726 is an identifier since in this case the rvalue can be propagated
727 attached to the CONST_DECL. */
729 /* This should match the constant case of the renaming code. */
730 || Is_Composite_Type
736 }
739 }
741 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Identifier,
742 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer
743 to where we should place the result type. */
745 static tree
747 {
751 /* Whether we should require an lvalue for GNAT_NODE. Needed in
752 specific circumstances only, so evaluated lazily. < 0 means
753 unknown, > 0 means known true, 0 means known false. */
756 /* If GNAT_NODE is a constant, whether we should use the initialization
757 value instead of the constant entity, typically for scalars with an
758 address clause when the parent doesn't require an lvalue. */
761 /* If the Etype of this node does not equal the Etype of the Entity,
762 something is wrong with the entity map, probably in generic
763 instantiation. However, this does not apply to types. Since we sometime
764 have strange Ekind's, just do this test for objects. Also, if the Etype of
765 the Entity is private, the Etype of the N_Identifier is allowed to be the
766 full type and also we consider a packed array type to be the same as the
767 original type. Similarly, a class-wide type is equivalent to a subtype of
768 itself. Finally, if the types are Itypes, one may be a copy of the other,
769 which is also legal. */
792 /* If this is a reference to a deferred constant whose partial view is an
793 unconstrained private type, the proper type is on the full view of the
794 constant, not on the full view of the type, which may be unconstrained.
796 This may be a reference to a type, for example in the prefix of the
797 attribute Position, generated for dispatching code (see Make_DT in
798 exp_disp,adb). In that case we need the type itself, not is parent,
799 in particular if it is a derived type */
804 {
807 }
808 else
809 {
810 /* We want to use the Actual_Subtype if it has already been elaborated,
811 otherwise the Etype. Avoid using Actual_Subtype for packed arrays to
812 simplify things. */
820 else
822 }
824 /* Expand the type of this identifier first, in case it is an enumeral
825 literal, which only get made when the type is expanded. There is no
826 order-of-elaboration issue here. */
829 /* If this is a non-imported scalar constant with an address clause,
830 retrieve the value instead of a pointer to be dereferenced unless
831 an lvalue is required. This is generally more efficient and actually
832 required if this is a static expression because it might be used
833 in a context where a dereference is inappropriate, such as a case
834 statement alternative or a record discriminant. There is no possible
835 volatile-ness short-circuit here since Volatile constants must bei
836 imported per C.6. */
840 {
844 }
847 {
848 /* If this is a deferred constant, the initializer is attached to
849 the full view. */
854 }
855 else
858 /* If we are in an exception handler, force this variable into memory to
859 ensure optimization does not remove stores that appear redundant but are
860 actually needed in case an exception occurs.
862 ??? Note that we need not do this if the variable is declared within the
863 handler, only if it is referenced in the handler and declared in an
864 enclosing block, but we have no way of testing that right now.
866 ??? We used to essentially set the TREE_ADDRESSABLE flag on the variable
867 here, but it can now be removed by the Tree aliasing machinery if the
868 address of the variable is never taken. All we can do is to make the
869 variable volatile, which might incur the generation of temporaries just
870 to access the memory in some circumstances. This can be avoided for
871 variables of non-constant size because they are automatically allocated
872 to memory. There might be no way of allocating a proper temporary for
873 them in any case. We only do this for SJLJ though. */
879 /* Some objects (such as parameters passed by reference, globals of
880 variable size, and renamed objects) actually represent the address
881 of the object. In that case, we must do the dereference. Likewise,
882 deal with parameters to foreign convention subprograms. */
887 {
889 tree renamed_obj;
893 gnu_result
896 gnu_result));
898 /* If it's a renaming pointer and we are at the right binding level,
899 we can reference the renamed object directly, since the renamed
900 expression has been protected against multiple evaluations. */
907 /* Return the underlying CST for a CONST_DECL like a few lines below,
908 after dereferencing in this case. */
913 else
917 }
919 /* The GNAT tree has the type of a function as the type of its result. Also
920 use the type of the result if the Etype is a subtype which is nominally
921 unconstrained. But remove any padding from the resulting type. */
924 {
929 }
931 /* If we have a constant declaration and its initializer at hand,
932 try to return the latter to avoid the need to call fold in lots
933 of places and the need of elaboration code if this Id is used as
934 an initializer itself. */
938 {
939 tree object
943 /* If there is a corresponding variable, we only want to return
944 the CST value if an lvalue is not required. Evaluate this
945 now if we have not already done so. */
952 }
956 }
957 \f
958 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Pragma. Return
959 any statements we generate. */
961 static tree
963 {
964 Node_Id gnat_temp;
967 /* Check for (and ignore) unrecognized pragma and do nothing if we are just
968 annotating types. */
974 {
976 /* Do nothing at top level: all such variables are already viewable. */
983 {
989 #ifdef ASM_COMMENT_START
991 #endif
996 /* Use the value only if it fits into a normal register,
997 otherwise use the address. */
1006 #ifdef ASM_COMMENT_START
1012 NULL);
1015 #endif
1017 asm_constraint,
1018 NULL_TREE,
1019 tree_cons
1023 NULL_TREE);
1027 }
1033 {
1046 }
1053 }
1056 }
1057 \f
1058 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Attribute node,
1059 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to
1060 where we should place the result type. ATTRIBUTE is the attribute ID. */
1062 static tree
1064 {
1066 tree gnu_result_type;
1067 tree gnu_expr;
1072 /* If the input is a NULL_EXPR, make a new one. */
1074 {
1078 }
1081 {
1084 /* These are just conversions since representation clauses for
1085 enumeration types are handled in the front-end. */
1086 {
1092 }
1097 /* These just add or subtract the constant 1 since representation
1098 clauses for enumeration types are handled in the front-end. */
1103 {
1105 gnu_expr
1106 = emit_check
1108 gnu_expr,
1109 attribute == Attr_Pred
1113 }
1115 gnu_result
1123 /* Conversions don't change addresses but can cause us to miss the
1124 COMPONENT_REF case below, so strip them off. */
1128 /* If we are taking 'Address of an unconstrained object, this is the
1129 pointer to the underlying array. */
1133 /* If we are building a static dispatch table, we have to honor
1134 TARGET_VTABLE_USES_DESCRIPTORS if we want to be compatible
1135 with the C++ ABI. We do it in the non-static case as well,
1136 see gnat_to_gnu_entity, case E_Access_Subprogram_Type. */
1139 {
1141 /* Descriptors can only be built here for top-level functions. */
1147 /* If we're not going to build the descriptor, we have to retrieve
1148 the one which will be built by the linker (or by the compiler
1149 later if a static chain is requested). */
1151 {
1154 gnu_result);
1156 }
1161 {
1163 {
1167 }
1168 else
1173 }
1177 }
1179 /* ... fall through ... */
1185 gnu_result
1192 /* For 'Code_Address, find an inner ADDR_EXPR and mark it so that we
1193 don't try to build a trampoline. */
1195 {
1203 }
1205 /* For other address attributes applied to a nested function,
1206 find an inner ADDR_EXPR and annotate it so that we can issue
1207 a useful warning with -Wtrampolines. */
1209 {
1213 ;
1217 {
1220 /* Check that we're not violating the No_Implicit_Dynamic_Code
1221 restriction. Be conservative if we don't know anything
1222 about the trampoline strategy for the target. */
1224 }
1225 }
1229 {
1230 tree gnu_obj_type;
1235 /* If this is an unconstrained array, we know the object has been
1236 allocated with the template in front of the object. So compute
1237 the template address. */
1239 gnu_ptr
1241 (TYPE_OBJECT_RECORD_TYPE
1243 gnu_ptr);
1248 {
1251 tree gnu_byte_offset
1259 }
1262 }
1271 /* Remove NOPs from GNU_EXPR and conversions from GNU_PREFIX.
1272 We only use GNU_EXPR to see if a COMPONENT_REF was involved. */
1280 /* Replace an unconstrained array type with the type of the underlying
1281 array. We can't do this with a call to maybe_unconstrained_array
1282 since we may have a TYPE_DECL. For 'Max_Size_In_Storage_Elements,
1283 use the record type that will be used to allocate the object and its
1284 template. */
1286 {
1290 }
1292 /* If we're looking for the size of a field, return the field size.
1293 Otherwise, if the prefix is an object, or if 'Object_Size or
1294 'Max_Size_In_Storage_Elements has been specified, the result is the
1295 GCC size of the type. Otherwise, the result is the RM size of the
1296 type. */
1302 {
1303 /* If this is a padded type, the GCC size isn't relevant to the
1304 programmer. Normally, what we want is the RM size, which was set
1305 from the specified size, but if it was not set, we want the size
1306 of the relevant field. Using the MAX of those two produces the
1307 right result in all case. Don't use the size of the field if it's
1308 a self-referential type, since that's never what's wanted. */
1312 {
1316 gnu_result
1319 }
1321 {
1323 Node_Id gnat_actual_subtype
1325 tree gnu_ptr_type
1330 {
1331 tree gnu_actual_obj_type
1333 gnu_type
1335 gnu_actual_obj_type,
1337 }
1340 }
1341 else
1343 }
1344 else
1349 /* Deal with a self-referential size by returning the maximum size for
1350 a type and by qualifying the size with the object for 'Size of an
1351 object. */
1353 {
1356 else
1358 }
1360 /* If the type contains a template, subtract its size. */
1395 {
1402 else
1403 gnu_result
1404 = build_binary_op
1406 build_binary_op
1418 }
1420 /* ... fall through ... */
1423 {
1430 /* Make sure any implicit dereference gets done. */
1433 /* We treat unconstrained array In parameters specially. */
1443 {
1445 tree gnu_type_temp;
1451 ;
1454 }
1461 /* When not optimizing, look up the slot associated with the parameter
1462 and the dimension in the cache and create a new one on failure. */
1464 {
1470 {
1475 }
1476 }
1478 /* Return the cached expression or build a new one. */
1480 {
1482 {
1485 }
1487 gnu_result
1489 }
1492 {
1494 {
1497 }
1499 gnu_result
1501 }
1504 {
1506 {
1509 }
1510 else
1511 {
1512 /* We used to compute the length as max (hb - lb + 1, 0),
1513 which could overflow for some cases of empty arrays, e.g.
1514 when lb == index_type'first. We now compute the length as
1515 (hb < lb) ? 0 : hb - lb + 1, which would only overflow in
1516 much rarer cases, for extremely large arrays we expect
1517 never to encounter in practice. In addition, the former
1518 computation required the use of potentially constraining
1519 signed arithmetic while the latter doesn't. Note that the
1520 comparison must be done in the original index base type,
1521 otherwise the conversion of either bound to gnu_compute_type
1522 may overflow. */
1526 tree index_type
1528 tree lb
1530 tree hb
1533 gnu_result
1534 = build3
1540 build_binary_op
1544 }
1545 }
1547 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
1548 handling. Note that these attributes could not have been used on
1549 an unconstrained array type. */
1551 gnu_prefix);
1553 /* Cache the expression we have just computed. Since we want to do it
1554 at runtime, we force the use of a SAVE_EXPR and let the gimplifier
1555 create the temporary. */
1557 {
1558 gnu_result
1565 else
1567 }
1569 }
1576 {
1577 HOST_WIDE_INT bitsize;
1578 HOST_WIDE_INT bitpos;
1579 tree gnu_offset;
1580 tree gnu_field_bitpos;
1581 tree gnu_field_offset;
1582 tree gnu_inner;
1590 /* We can have 'Bit on any object, but if it isn't a COMPONENT_REF,
1591 the result is 0. Don't allow 'Bit on a bare component, though. */
1595 {
1598 }
1600 else
1609 {
1617 {
1618 gnu_field_bitpos
1621 gnu_field_offset
1624 }
1625 }
1627 {
1630 }
1631 else
1632 {
1635 }
1638 {
1653 bitsize_one_node);
1659 }
1661 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
1662 handling. */
1665 }
1669 {
1677 }
1705 /* Note this size cannot be self-referential. */
1712 /* This is just a zero cast to the pointer type for our prefix and
1713 dereferenced. */
1715 gnu_result
1718 integer_zero_node));
1723 {
1730 {
1735 ;
1736 }
1744 && (DECL_BY_COMPONENT_PTR_P
1748 }
1752 /* Say we have an unimplemented attribute. Then set the value to be
1753 returned to be a zero and hope that's something we can convert to
1754 the type of this attribute. */
1759 }
1761 /* If this is an attribute where the prefix was unused, force a use of it if
1762 it has a side-effect. But don't do it if the prefix is just an entity
1763 name. However, if an access check is needed, we must do it. See second
1764 example in AARM 11.6(5.e). */
1772 }
1773 \f
1774 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Case_Statement,
1775 to a GCC tree, which is returned. */
1777 static tree
1779 {
1780 tree gnu_result;
1781 tree gnu_expr;
1782 Node_Id gnat_when;
1787 /* The range of values in a case statement is determined by the rules in
1788 RM 5.4(7-9). In almost all cases, this range is represented by the Etype
1789 of the expression. One exception arises in the case of a simple name that
1790 is parenthesized. This still has the Etype of the name, but since it is
1791 not a name, para 7 does not apply, and we need to go to the base type.
1792 This is the only case where parenthesization affects the dynamic
1793 semantics (i.e. the range of possible values at runtime that is covered
1794 by the others alternative.
1796 Another exception is if the subtype of the expression is non-static. In
1797 that case, we also have to use the base type. */
1803 /* We build a SWITCH_EXPR that contains the code with interspersed
1804 CASE_LABEL_EXPRs for each label. */
1811 {
1812 Node_Id gnat_choice;
1815 /* First compile all the different case choices for the current WHEN
1816 alternative. */
1819 {
1823 {
1838 /* This represents either a subtype range or a static value of
1839 some kind; Ekind says which. */
1841 {
1847 }
1849 /* ... fall through ... */
1861 }
1863 /* If the case value is a subtype that raises Constraint_Error at
1864 run-time because of a wrong bound, then gnu_low or gnu_high is
1865 not translated into an INTEGER_CST. In such a case, we need
1866 to ensure that the when statement is not added in the tree,
1867 otherwise it will crash the gimplifier. */
1870 {
1874 gnat_choice);
1875 choices_added++;
1876 }
1877 }
1879 /* Push a binding level here in case variables are declared as we want
1880 them to be local to this set of statements instead of to the block
1881 containing the Case statement. */
1883 {
1887 }
1888 }
1890 /* Now emit a definition of the label all the cases branched to. */
1898 }
1899 \f
1900 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Loop_Statement,
1901 to a GCC tree, which is returned. */
1903 static tree
1905 {
1906 /* ??? It would be nice to use "build" here, but there's no build5. */
1912 tree gnu_result;
1921 /* Save the end label of this LOOP_STMT in a stack so that the corresponding
1922 N_Exit_Statement can find it. */
1926 /* Set the condition under which the loop must keep going.
1927 For the case "LOOP .... END LOOP;" the condition is always true. */
1929 ;
1931 /* For the case "WHILE condition LOOP ..... END LOOP;" it's immediate. */
1936 /* Otherwise we have an iteration scheme and the condition is given by
1937 the bounds of the subtype of the iteration variable. */
1938 else
1939 {
1950 /* We must disable modulo reduction for the loop variable, if any,
1951 in order for the loop comparison to be effective. */
1953 {
1959 }
1960 else
1961 {
1967 }
1969 /* We know the loop variable will not overflow if GNU_LAST is a constant
1970 and is not equal to GNU_LIMIT. If it might overflow, we have to move
1971 the limit test to the end of the loop. In that case, we have to test
1972 for an empty loop outside the loop. */
1976 {
1977 gnu_cond_expr
1983 }
1985 /* Open a new nesting level that will surround the loop to declare the
1986 loop index variable. */
1990 /* Declare the loop index and set it to its initial value. */
1995 /* The loop variable might be a padded type, so use `convert' to get a
1996 reference to the inner variable if so. */
1999 /* Set either the top or bottom exit condition as appropriate depending
2000 on whether or not we know an overflow cannot occur. */
2005 else
2012 gnu_loop_var,
2015 gnu_loop_var,
2017 integer_one_node)));
2019 gnat_iter_scheme);
2020 }
2022 /* If the loop was named, have the name point to this loop. In this case,
2023 the association is not a ..._DECL node, but the end label from this
2024 LOOP_STMT. */
2029 /* Make the loop body into its own block, so any allocated storage will be
2030 released every iteration. This is needed for stack allocation. */
2034 /* If we declared a variable, then we are in a statement group for that
2035 declaration. Add the LOOP_STMT to it and make that the "loop". */
2037 {
2041 }
2043 /* If we have an outer COND_EXPR, that's our result and this loop is its
2044 "true" statement. Otherwise, the result is the LOOP_STMT. */
2046 {
2050 }
2051 else
2057 }
2058 \f
2059 /* Emit statements to establish __gnat_handle_vms_condition as a VMS condition
2060 handler for the current function. */
2062 /* This is implemented by issuing a call to the appropriate VMS specific
2063 builtin. To avoid having VMS specific sections in the global gigi decls
2064 array, we maintain the decls of interest here. We can't declare them
2065 inside the function because we must mark them never to be GC'd, which we
2066 can only do at the global level. */
2071 static void
2073 {
2074 tree establish_stmt;
2076 /* Elaborate the required decls on the first call. Check on the decl for
2077 the gnat condition handler to decide, as this is one we create so we are
2078 sure that it will be non null on subsequent calls. The builtin decl is
2079 looked up so remains null on targets where it is not implemented yet. */
2081 {
2082 vms_builtin_establish_handler_decl
2083 = builtin_decl_for
2086 gnat_vms_condition_handler_decl
2088 NULL_TREE,
2090 ptr_void_type_node,
2091 ptr_void_type_node,
2092 NULL_TREE),
2095 /* ??? DECL_CONTEXT shouldn't have been set because of DECL_EXTERNAL. */
2097 }
2099 /* Do nothing if the establish builtin is not available, which might happen
2100 on targets where the facility is not implemented. */
2104 establish_stmt
2106 build_unary_op
2108 gnat_vms_condition_handler_decl));
2111 }
2112 \f
2113 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Subprogram_Body. We
2114 don't return anything. */
2116 static void
2118 {
2119 /* Defining identifier of a parameter to the subprogram. */
2120 Entity_Id gnat_param;
2121 /* The defining identifier for the subprogram body. Note that if a
2122 specification has appeared before for this body, then the identifier
2123 occurring in that specification will also be a defining identifier and all
2124 the calls to this subprogram will point to that specification. */
2125 Entity_Id gnat_subprog_id
2128 /* The FUNCTION_DECL node corresponding to the subprogram spec. */
2129 tree gnu_subprog_decl;
2130 /* The FUNCTION_TYPE node corresponding to the subprogram spec. */
2131 tree gnu_subprog_type;
2132 tree gnu_cico_list;
2133 tree gnu_result;
2136 /* If this is a generic object or if it has been eliminated,
2137 ignore it. */
2143 /* If this subprogram acts as its own spec, define it. Otherwise, just get
2144 the already-elaborated tree node. However, if this subprogram had its
2145 elaboration deferred, we will already have made a tree node for it. So
2146 treat it as not being defined in that case. Such a subprogram cannot
2147 have an address clause or a freeze node, so this test is safe, though it
2148 does disable some otherwise-useful error checking. */
2149 gnu_subprog_decl
2156 /* Propagate the debug mode. */
2160 /* Set the line number in the decl to correspond to that of the body so that
2161 the line number notes are written correctly. */
2164 /* Initialize the information structure for the function. */
2172 /* If there are Out parameters, we need to ensure that the return statement
2173 properly copies them out. We do this by making a new block and converting
2174 any inner return into a goto to a label at the end of the block. */
2178 /* Get a tree corresponding to the code for the subprogram. */
2182 /* See if there are any parameters for which we don't yet have GCC entities.
2183 These must be for Out parameters for which we will be making VAR_DECL
2184 nodes here. Fill them in to TYPE_CI_CO_LIST, which must contain the empty
2185 entry as well. We can match up the entries because TYPE_CI_CO_LIST is in
2186 the order of the parameters. */
2191 {
2192 /* Skip any entries that have been already filled in; they must
2193 correspond to In Out parameters. */
2196 ;
2198 /* Do any needed references for padded types. */
2202 }
2204 /* On VMS, establish our condition handler to possibly turn a condition into
2205 the corresponding exception if the subprogram has a foreign convention or
2206 is exported.
2208 To ensure proper execution of local finalizations on condition instances,
2209 we must turn a condition into the corresponding exception even if there
2210 is no applicable Ada handler, and need at least one condition handler per
2211 possible call chain involving GNAT code. OTOH, establishing the handler
2212 has a cost so we want to minimize the number of subprograms into which
2213 this happens. The foreign or exported condition is expected to satisfy
2214 all the constraints. */
2222 /* Generate the code of the subprogram itself. A return statement will be
2223 present and any Out parameters will be handled there. */
2228 /* If we populated the parameter attributes cache, we need to make sure
2229 that the cached expressions are evaluated on all possible paths. */
2232 {
2239 {
2246 }
2250 }
2252 /* If we made a special return label, we need to make a block that contains
2253 the definition of that label and the copying to the return value. That
2254 block first contains the function, then the label and copy statement. */
2256 {
2257 tree gnu_retval;
2268 else
2270 gnu_cico_list);
2275 add_stmt_with_node
2280 }
2284 /* Set the end location. */
2285 Sloc_to_locus
2293 /* Disconnect the trees for parameters that we made variables for from the
2294 GNAT entities since these are unusable after we end the function. */
2305 }
2306 \f
2307 /* Subroutine of gnat_to_gnu to translate gnat_node, either an N_Function_Call
2308 or an N_Procedure_Call_Statement, to a GCC tree, which is returned.
2309 GNU_RESULT_TYPE_P is a pointer to where we should place the result type.
2310 If GNU_TARGET is non-null, this must be a function call and the result
2311 of the call is to be placed into that object. */
2313 static tree
2315 {
2316 tree gnu_result;
2317 /* The GCC node corresponding to the GNAT subprogram name. This can either
2318 be a FUNCTION_DECL node if we are dealing with a standard subprogram call,
2319 or an indirect reference expression (an INDIRECT_REF node) pointing to a
2320 subprogram. */
2322 /* The FUNCTION_TYPE node giving the GCC type of the subprogram. */
2325 gnu_subprog_node);
2326 Entity_Id gnat_formal;
2327 Node_Id gnat_actual;
2332 tree gnu_subprog_call;
2336 /* If we are calling a stubbed function, make this into a raise of
2337 Program_Error. Elaborate all our args first. */
2340 {
2346 {
2347 tree call_expr
2349 N_Raise_Program_Error);
2352 {
2355 }
2356 else
2358 }
2359 }
2361 /* If we are calling by supplying a pointer to a target, set up that
2362 pointer as the first argument. Use GNU_TARGET if one was passed;
2363 otherwise, make a target by building a variable of the maximum size
2364 of the type. */
2366 {
2367 tree gnu_real_ret_type
2371 {
2372 tree gnu_obj_type
2378 /* ??? We may be about to create a static temporary if we happen to
2379 be at the global binding level. That's a regression from what
2380 the 3.x back-end would generate in the same situation, but we
2381 don't have a mechanism in Gigi for creating automatic variables
2382 in the elaboration routines. */
2383 gnu_target
2386 gnat_node);
2387 }
2389 gnu_actual_list
2393 gnu_target,
2395 NULL_TREE);
2397 }
2399 /* The only way we can be making a call via an access type is if Name is an
2400 explicit dereference. In that case, get the list of formal args from the
2401 type the access type is pointing to. Otherwise, get the formals from
2402 entity being called. */
2406 /* Assume here that this must be 'Elab_Body or 'Elab_Spec. */
2408 else
2411 /* Create the list of the actual parameters as GCC expects it, namely a chain
2412 of TREE_LIST nodes in which the TREE_VALUE field of each node is a
2413 parameter-expression and the TREE_PURPOSE field is null. Skip Out
2414 parameters not passed by reference and don't need to be copied in. */
2419 {
2420 tree gnu_formal
2424 /* We must suppress conversions that can cause the creation of a
2425 temporary in the Out or In Out case because we need the real
2426 object in this case, either to pass its address if it's passed
2427 by reference or as target of the back copy done after the call
2428 if it uses the copy-in copy-out mechanism. We do it in the In
2429 case too, except for an unchecked conversion because it alone
2430 can cause the actual to be misaligned and the addressability
2431 test is applied to the real object. */
2432 bool suppress_type_conversion
2437 Node_Id gnat_name = (suppress_type_conversion
2440 tree gnu_actual;
2442 /* If it's possible we may need to use this expression twice, make sure
2443 that any side-effects are handled via SAVE_EXPRs. Likewise if we need
2444 to force side-effects before the call.
2445 ??? This is more conservative than we need since we don't need to do
2446 this for pass-by-ref with no conversion. */
2450 /* If we are passing a non-addressable parameter by reference, pass the
2451 address of a copy. In the Out or In Out case, set up to copy back
2452 out after the call. */
2460 {
2463 /* If the type is by_reference, a copy is not allowed. */
2465 post_error
2468 /* For users of Starlet we issue a warning because the
2469 interface apparently assumes that by-ref parameters
2470 outlive the procedure invocation. The code still
2471 will not work as intended, but we cannot do much
2472 better since other low-level parts of the back-end
2473 would allocate temporaries at will because of the
2474 misalignment if we did not do so here. */
2476 {
2477 post_error
2479 post_error_ne
2483 gnat_formal);
2484 }
2486 /* If the actual type of the object is already the nominal type,
2487 we have nothing to do, except if the size is self-referential
2488 in which case we'll remove the unpadding below. */
2491 ;
2493 /* Otherwise remove unpadding from the object and reset the copy. */
2497 && (TYPE_IS_PADDING_P
2501 /* Otherwise convert to the nominal type of the object if it's
2502 a record type. There are several cases in which we need to
2503 make the temporary using this type instead of the actual type
2504 of the object if they are distinct, because the expectations
2505 of the callee would otherwise not be met:
2506 - if it's a justified modular type,
2507 - if the actual type is a smaller packable version of it. */
2511 gnu_name_type)))
2514 /* Make a SAVE_EXPR to both properly account for potential side
2515 effects and handle the creation of a temporary copy. Special
2516 code in gnat_gimplify_expr ensures that the same temporary is
2517 used as the object and copied back after the call if needed. */
2521 /* Set up to move the copy back to the original. */
2523 {
2525 gnu_name);
2528 }
2529 }
2531 /* Start from the real object and build the actual. */
2534 /* If this was a procedure call, we may not have removed any padding.
2535 So do it here for the part we will use as an input, if any. */
2540 gnu_actual);
2542 /* Do any needed conversions for the actual and make sure that it is
2543 in range of the formal's type. */
2545 {
2546 /* Put back the conversion we suppressed above in the computation
2547 of the real object. Note that we treat a conversion between
2548 aggregate types as if it is an unchecked conversion here. */
2549 gnu_actual
2551 gnu_actual,
2559 gnat_actual);
2560 }
2561 else
2562 {
2566 gnat_actual);
2568 /* We may have suppressed a conversion to the Etype of the actual
2569 since the parent is a procedure call. So put it back here.
2570 ??? We use the reverse order compared to the case above because
2571 of an awkward interaction with the check and actually don't put
2572 back the conversion at all if a check is emitted. This is also
2573 done for the conversion to the formal's type just below. */
2576 gnu_actual);
2577 }
2582 /* Unless this is an In parameter, we must remove any justified modular
2583 building from GNU_NAME to get an lvalue. */
2589 gnu_name);
2591 /* If we have not saved a GCC object for the formal, it means it is an
2592 Out parameter not passed by reference and that does not need to be
2593 copied in. Otherwise, look at the PARM_DECL to see if it is passed by
2594 reference. */
2598 {
2600 {
2601 /* In Out or Out parameters passed by reference don't use the
2602 copy-in copy-out mechanism so the address of the real object
2603 must be passed to the function. */
2606 /* If we have a padded type, be sure we've removed padding. */
2611 gnu_actual);
2613 /* If we have the constructed subtype of an aliased object
2614 with an unconstrained nominal subtype, the type of the
2615 actual includes the template, although it is formally
2616 constrained. So we need to convert it back to the real
2617 constructed subtype to retrieve the constrained part
2618 and takes its address. */
2625 gnu_actual);
2626 }
2628 /* The symmetry of the paths to the type of an entity is broken here
2629 since arguments don't know that they will be passed by ref. */
2632 }
2636 {
2643 {
2646 }
2648 /* Take the address of the object and convert to the proper pointer
2649 type. We'd like to actually compute the address of the beginning
2650 of the array using an ADDR_EXPR of an ARRAY_REF, but there's a
2651 possibility that the ARRAY_REF might return a constant and we'd be
2652 getting the wrong address. Neither approach is exactly correct,
2653 but this is the most likely to work in all cases. */
2656 gnu_actual));
2657 }
2661 {
2662 /* If arg is 'Null_Parameter, pass zero descriptor. */
2667 integer_zero_node);
2668 else
2671 gnat_formal,
2672 gnat_actual));
2673 }
2674 else
2675 {
2684 /* If this is 'Null_Parameter, pass a zero even though we are
2685 dereferencing it. */
2690 BITS_PER_WORD))
2691 gnu_actual
2696 integer_zero_node),
2698 else
2700 }
2703 }
2706 gnu_subprog_addr,
2710 /* If we return by passing a target, the result is the target after the
2711 call. We must not emit the call directly here because this might be
2712 evaluated as part of an expression with conditions to control whether
2713 the call should be emitted or not. */
2715 {
2716 /* Conceptually, what we need is a COMPOUND_EXPR with the call followed
2717 by the target object converted to the proper type. Doing so would
2718 potentially be very inefficient, however, as this expression might
2719 end up wrapped into an outer SAVE_EXPR later on, which would incur a
2720 pointless temporary copy of the whole object.
2722 What we do instead is build a COMPOUND_EXPR returning the address of
2723 the target, and then dereference. Wrapping the COMPOUND_EXPR into a
2724 SAVE_EXPR later on then only incurs a pointer copy. */
2726 tree gnu_result_type
2729 /* Build and return
2730 (result_type) *[gnu_subprog_call (&gnu_target, ...), &gnu_target] */
2732 tree gnu_target_address
2736 gnu_result
2740 gnu_result
2743 gnu_result),
2748 }
2750 /* If it is a function call, the result is the call expression unless
2751 a target is specified, in which case we copy the result into the target
2752 and return the assignment statement. */
2754 {
2757 /* If the function returns an unconstrained array or by reference,
2758 we have to de-dereference the pointer. */
2766 else
2770 }
2772 /* If this is the case where the GNAT tree contains a procedure call
2773 but the Ada procedure has copy in copy out parameters, the special
2774 parameter passing mechanism must be used. */
2776 {
2777 /* List of FIELD_DECLs associated with the PARM_DECLs of the copy
2778 in copy out parameters. */
2783 {
2784 tree gnu_name;
2789 /* If any of the names had side-effects, ensure they are all
2790 evaluated before the call. */
2796 }
2800 else
2807 /* If we are dealing with a copy in copy out parameter, we must
2808 retrieve its value from the record returned in the call. */
2814 || (DECL_BY_DESCRIPTOR_P
2817 {
2818 /* Get the value to assign to this Out or In Out parameter. It is
2819 either the result of the function if there is only a single such
2820 parameter or the appropriate field from the record returned. */
2821 tree gnu_result
2827 /* If the actual is a conversion, get the inner expression, which
2828 will be the real destination, and convert the result to the
2829 type of the actual parameter. */
2830 tree gnu_actual
2833 /* If the result is a padded type, remove the padding. */
2838 gnu_result);
2840 /* If the actual is a type conversion, the real target object is
2841 denoted by the inner Expression and we need to convert the
2842 result to the associated type.
2843 We also need to convert our gnu assignment target to this type
2844 if the corresponding GNU_NAME was constructed from the GNAT
2845 conversion node and not from the inner Expression. */
2847 {
2848 gnu_result
2849 = convert_with_check
2857 }
2859 /* Unchecked conversions as actuals for Out parameters are not
2860 allowed in user code because they are not variables, but do
2861 occur in front-end expansions. The associated GNU_NAME is
2862 always obtained from the inner expression in such cases. */
2865 gnu_result,
2867 else
2868 {
2870 gnu_result
2872 gnat_actual);
2877 }
2885 }
2886 }
2887 else
2892 }
2893 \f
2894 /* Subroutine of gnat_to_gnu to translate gnat_node, an
2895 N_Handled_Sequence_Of_Statements, to a GCC tree, which is returned. */
2897 static tree
2899 {
2902 /* If just annotating, ignore all EH and cleanups. */
2906 bool setjmp_longjmp
2912 tree gnu_result;
2913 tree gnu_expr;
2914 Node_Id gnat_temp;
2916 /* The GCC exception handling mechanism can handle both ZCX and SJLJ schemes
2917 and we have our own SJLJ mechanism. To call the GCC mechanism, we call
2918 add_cleanup, and when we leave the binding, end_stmt_group will create
2919 the TRY_FINALLY_EXPR.
2921 ??? The region level calls down there have been specifically put in place
2922 for a ZCX context and currently the order in which things are emitted
2923 (region/handlers) is different from the SJLJ case. Instead of putting
2924 other calls with different conditions at other places for the SJLJ case,
2925 it seems cleaner to reorder things for the SJLJ case and generalize the
2926 condition to make it not ZCX specific.
2928 If there are any exceptions or cleanup processing involved, we need an
2929 outer statement group (for Setjmp_Longjmp) and binding level. */
2931 {
2934 }
2936 /* If using setjmp_longjmp, make the variables for the setjmp buffer and save
2937 area for address of previous buffer. Do this first since we need to have
2938 the setjmp buf known for any decls in this block. */
2940 {
2945 gnat_node);
2948 /* The __builtin_setjmp receivers will immediately reinstall it. Now
2949 because of the unstructured form of EH used by setjmp_longjmp, there
2950 might be forward edges going to __builtin_setjmp receivers on which
2951 it is uninitialized, although they will never be actually taken. */
2961 /* When we exit this block, restore the saved value. */
2964 }
2966 /* If we are to call a function when exiting this block, add a cleanup
2967 to the binding level we made above. Note that add_cleanup is FIFO
2968 so we must register this cleanup after the EH cleanup just above. */
2973 /* Now build the tree for the declarations and statements inside this block.
2974 If this is SJLJ, set our jmp_buf as the current buffer. */
2980 gnu_jmpbuf_decl)));
2986 /* Generate code for each statement in the block. */
2994 /* Now generate code for the two exception models, if either is relevant for
2995 this block. */
2997 {
2999 tree gnu_handler;
3001 /* Make a binding level for the exception handling declarations and code
3002 and set up gnu_except_ptr_stack for the handlers to use. */
3008 NULL_TREE,
3013 /* Generate code for each handler. The N_Exception_Handler case does the
3014 real work and returns a COND_EXPR for each handler, which we chain
3015 together here. */
3018 {
3021 /* If this is the first one, set it as the outer one. Otherwise,
3022 point the "else" part of the previous handler to us. Then point
3023 to our "else" part. */
3026 else
3030 }
3032 /* If none of the exception handlers did anything, re-raise but do not
3033 defer abortion. */
3040 else
3043 /* End the binding level dedicated to the exception handlers and get the
3044 whole statement group. */
3049 /* If the setjmp returns 1, we restore our incoming longjmp value and
3050 then check the handlers. */
3053 gnu_jmpsave_decl),
3054 gnat_node);
3058 /* This block is now "if (setjmp) ... <handlers> else <block>". */
3060 (build_call_1_expr
3063 gnu_jmpbuf_decl))),
3065 }
3067 {
3068 tree gnu_handlers;
3070 /* First make a block containing the handlers. */
3078 /* Now make the TRY_CATCH_EXPR for the block. */
3081 }
3082 else
3085 /* Now close our outer block, if we had to make one. */
3087 {
3091 }
3094 }
3095 \f
3096 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
3097 to a GCC tree, which is returned. This is the variant for Setjmp_Longjmp
3098 exception handling. */
3100 static tree
3102 {
3103 /* Unless this is "Others" or the special "Non-Ada" exception for Ada, make
3104 an "if" statement to select the proper exceptions. For "Others", exclude
3105 exceptions where Handled_By_Others is nonzero unless the All_Others flag
3106 is set. For "Non-ada", accept an exception if "Lang" is 'V'. */
3109 Node_Id gnat_temp;
3113 {
3114 tree this_choice;
3117 {
3120 else
3121 this_choice
3122 = build_binary_op
3124 convert
3126 build_component_ref
3127 (build_unary_op
3132 integer_zero_node);
3133 }
3137 {
3139 tree gnu_expr;
3141 /* Exception may be a renaming. Recover original exception which is
3142 the one elaborated and registered. */
3148 this_choice
3149 = build_binary_op
3154 /* If this is the distinguished exception "Non_Ada_Error" (and we are
3155 in VMS mode), also allow a non-Ada exception (a VMS condition) t
3156 match. */
3158 {
3159 tree gnu_comp
3160 = build_component_ref
3165 this_choice
3166 = build_binary_op
3170 this_choice);
3171 }
3172 }
3173 else
3178 }
3181 }
3182 \f
3183 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
3184 to a GCC tree, which is returned. This is the variant for ZCX. */
3186 static tree
3188 {
3190 tree gnu_expr;
3191 tree gnu_etype;
3192 tree gnu_current_exc_ptr;
3193 tree gnu_incoming_exc_ptr;
3194 Node_Id gnat_temp;
3196 /* We build a TREE_LIST of nodes representing what exception types this
3197 handler can catch, with special cases for others and all others cases.
3199 Each exception type is actually identified by a pointer to the exception
3200 id, or to a dummy object for "others" and "all others".
3202 Care should be taken to ensure that the control flow impact of "others"
3203 and "all others" is known to GCC. lang_eh_type_covers is doing the trick
3204 currently. */
3207 {
3209 {
3210 tree gnu_expr
3213 gnu_etype
3215 }
3218 {
3221 /* Exception may be a renaming. Recover original exception which is
3222 the one elaborated and registered. */
3229 /* The Non_Ada_Error case for VMS exceptions is handled
3230 by the personality routine. */
3231 }
3232 else
3235 /* The GCC interface expects NULL to be passed for catch all handlers, so
3236 it would be quite tempting to set gnu_etypes_list to NULL if gnu_etype
3237 is integer_zero_node. It would not work, however, because GCC's
3238 notion of "catch all" is stronger than our notion of "others". Until
3239 we correctly use the cleanup interface as well, doing that would
3240 prevent the "all others" handlers from being seen, because nothing
3241 can be caught beyond a catch all from GCC's point of view. */
3243 }
3248 /* Expand a call to the begin_handler hook at the beginning of the handler,
3249 and arrange for a call to the end_handler hook to occur on every possible
3250 exit path.
3252 The hooks expect a pointer to the low level occurrence. This is required
3253 for our stack management scheme because a raise inside the handler pushes
3254 a new occurrence on top of the stack, which means that this top does not
3255 necessarily match the occurrence this handler was dealing with.
3257 The EXC_PTR_EXPR object references the exception occurrence being
3258 propagated. Upon handler entry, this is the exception for which the
3259 handler is triggered. This might not be the case upon handler exit,
3260 however, as we might have a new occurrence propagated by the handler's
3261 body, and the end_handler hook called as a cleanup in this context.
3263 We use a local variable to retrieve the incoming value at handler entry
3264 time, and reuse it to feed the end_handler hook's argument at exit. */
3269 gnat_node);
3272 gnu_incoming_exc_ptr),
3273 gnat_node);
3274 /* ??? We don't seem to have an End_Label at hand to set the location. */
3276 Empty);
3282 }
3283 \f
3284 /* Subroutine of gnat_to_gnu to generate code for an N_Compilation unit. */
3286 static void
3288 {
3289 /* Make the decl for the elaboration procedure. */
3294 tree gnu_elab_proc_decl
3295 = create_subprog_decl
3299 gnat_unit_entity);
3309 /* For a body, first process the spec if there is one. */
3313 {
3316 }
3321 {
3328 }
3334 /* Process any pragmas and actions following the unit. */
3339 /* Save away what we've made so far and record this potential elaboration
3340 procedure. */
3350 /* Generate elaboration code for this unit, if necessary, and say whether
3351 we did or not. */
3354 /* Invalidate the global renaming pointers. This is necessary because
3355 stabilization of the renamed entities may create SAVE_EXPRs which
3356 have been tied to a specific elaboration routine just above. */
3358 }
3359 \f
3360 /* Return whether GNAT_NODE, an unchecked type conversion, is on the LHS
3361 of an assignment and a no-op as far as gigi is concerned. */
3363 static bool
3365 {
3368 /* The conversion must be on the LHS of an assignment. Otherwise, even
3369 if the conversion was essentially a no-op, it could de facto ensure
3370 type consistency and this should be preserved. */
3377 /* We're interested in artificial conversions generated by the front-end
3378 to make private types explicit, e.g. in Expand_Assign_Array. */
3385 /* The direct conversion to the underlying type is a no-op. */
3389 /* For an array type, the conversion to the PAT is a no-op. */
3395 }
3397 /* This function is the driver of the GNAT to GCC tree transformation
3398 process. It is the entry point of the tree transformer. GNAT_NODE is the
3399 root of some GNAT tree. Return the root of the corresponding GCC tree.
3400 If this is an expression, return the GCC equivalent of the expression. If
3401 it is a statement, return the statement. In the case when called for a
3402 statement, it may also add statements to the current statement group, in
3403 which case anything it returns is to be interpreted as occurring after
3404 anything `it already added. */
3406 tree
3408 {
3412 tree gnu_expr;
3414 Node_Id gnat_temp;
3416 /* Save node number for error message and set location information. */
3424 /* If this node is a non-static subexpression and we are only
3425 annotating types, make this into a NULL_EXPR. */
3432 N_Raise_Constraint_Error));
3434 /* If this is a Statement and we are at top level, it must be part of the
3435 elaboration procedure, so mark us as being in that procedure and push our
3436 context.
3438 If we are in the elaboration procedure, check if we are violating a
3439 No_Elaboration_Code restriction by having a statement there. */
3450 {
3452 {
3457 }
3459 /* Don't check for a possible No_Elaboration_Code restriction violation
3460 on N_Handled_Sequence_Of_Statements, as we want to signal an error on
3461 every nested real statement instead. This also avoids triggering
3462 spurious errors on dummy (empty) sequences created by the front-end
3463 for package bodies in some cases. */
3468 }
3471 {
3472 /********************************/
3473 /* Chapter 2: Lexical Elements */
3474 /********************************/
3484 {
3485 tree gnu_type;
3487 /* Get the type of the result, looking inside any padding and
3488 justified modular types. Then get the value in that type. */
3497 /* If the result overflows (meaning it doesn't fit in its base type),
3498 abort. We would like to check that the value is within the range
3499 of the subtype, but that causes problems with subtypes whose usage
3500 will raise Constraint_Error and with biased representation, so
3501 we don't. */
3503 }
3507 /* If a Entity is present, it means that this was one of the
3508 literals in a user-defined character type. In that case,
3509 just return the value in the CONST_DECL. Otherwise, use the
3510 character code. In that case, the base type should be an
3511 INTEGER_TYPE, but we won't bother checking for that. */
3515 else
3516 gnu_result
3517 = build_int_cst_type
3522 /* If this is of a fixed-point type, the value we want is the
3523 value of the corresponding integer. */
3525 {
3528 gnu_result_type);
3530 }
3532 /* We should never see a Vax_Float type literal, since the front end
3533 is supposed to transform these using appropriate conversions. */
3537 else
3538 {
3543 /* If the real value is zero, so is the result. Otherwise,
3544 convert it to a machine number if it isn't already. That
3545 forces BASE to 0 or 2 and simplifies the rest of our logic. */
3548 else
3549 {
3551 ur_realval
3555 gnu_result
3558 /* If we have a base of zero, divide by the denominator.
3559 Otherwise, the base must be 2 and we scale the value, which
3560 we know can fit in the mantissa of the type (hence the use
3561 of that type above). */
3563 gnu_result
3566 gnu_result,
3568 gnu_result_type));
3569 else
3570 {
3571 REAL_VALUE_TYPE tmp;
3577 }
3578 }
3580 /* Now see if we need to negate the result. Do it this way to
3581 properly handle -0. */
3583 gnu_result
3585 gnu_result);
3586 }
3593 {
3600 else
3603 /* Build the string with the characters in the literal. Note
3604 that Ada strings are 1-origin. */
3608 /* Put a null at the end of the string in case it's in a context
3609 where GCC will want to treat it as a C string. */
3614 /* Strings in GCC don't normally have types, but we want
3615 this to not be converted to the array type. */
3620 }
3621 else
3622 {
3623 /* Build a list consisting of each character, then make
3624 the aggregate. */
3632 {
3633 gnu_list
3638 gnu_list);
3642 }
3644 gnu_result
3646 }
3653 /**************************************/
3654 /* Chapter 3: Declarations and Types */
3655 /**************************************/
3672 /* If we are just annotating types and this object has an unconstrained
3673 or task type, don't elaborate it. */
3684 && (!type_annotate_only
3686 {
3689 gnu_expr
3692 /* If this object has its elaboration delayed, we must force
3693 evaluation of GNU_EXPR right now and save it for when the object
3694 is frozen. */
3696 {
3699 gnu_expr
3704 else
3708 }
3709 }
3710 else
3716 /* If this is a deferred constant with an address clause, we ignore the
3717 full view since the clause is on the partial view and we cannot have
3718 2 different GCC trees for the object. The only bits of the full view
3719 we will use is the initializer, but it will be directly fetched. */
3732 /* Don't do anything if this renaming is handled by the front end or if
3733 we are just annotating types and this object has a composite or task
3734 type, don't elaborate it. We return the result in case it has any
3735 SAVE_EXPRs in it that need to be evaluated here. */
3737 && ! (type_annotate_only
3741 gnu_result
3744 else
3757 /* These are fully handled in the front end. */
3761 /*************************************/
3762 /* Chapter 4: Names and Expressions */
3763 /*************************************/
3772 {
3774 tree gnu_type;
3782 /* If we got a padded type, remove it too. */
3785 gnu_array_object
3787 gnu_array_object);
3791 /* First compute the number of dimensions of the array, then
3792 fill the expression array, the order depending on whether
3793 this is a Convention_Fortran array or not. */
3798 ;
3807 else
3815 {
3821 gnu_expr
3822 = emit_index_check
3826 gnat_temp);
3830 }
3831 }
3837 {
3838 tree gnu_type;
3844 /* Do any implicit dereferences of the prefix and do any needed
3845 range check. */
3850 {
3851 /* Get the bounds of the slice. */
3852 tree gnu_index_type
3856 /* Get the permitted bounds. */
3857 tree gnu_base_index_type
3859 tree gnu_base_min_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
3861 tree gnu_base_max_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
3868 /* Derive a good type to convert everything to. */
3871 /* Test whether the minimum slice value is too small. */
3874 gnu_min_expr),
3876 gnu_base_min_expr));
3878 /* Test whether the maximum slice value is too large. */
3881 gnu_max_expr),
3883 gnu_base_max_expr));
3885 /* Build a slice index check that returns the low bound,
3886 assuming the slice is not empty. */
3887 gnu_expr = emit_check
3892 /* Build a conditional expression that does the index checks and
3893 returns the low bound if the slice is not empty (max >= min),
3894 and returns the naked low bound otherwise (max < min), unless
3895 it is non-constant and the high bound is; this prevents VRP
3896 from inferring bogus ranges on the unlikely path. */
3900 gnu_max_expr),
3902 gnu_min_expr)),
3903 gnu_expr,
3907 }
3908 else
3909 /* Simply return the naked low bound. */
3914 }
3918 {
3922 tree gnu_field;
3926 {
3931 }
3935 /* For discriminant references in tagged types always substitute the
3936 corresponding discriminant as the actual selected component. */
3941 /* For discriminant references of untagged types always substitute the
3942 corresponding stored discriminant. */
3946 /* Handle extracting the real or imaginary part of a complex.
3947 The real part is the first field and the imaginary the last. */
3952 else
3953 {
3956 /* If there are discriminants, the prefix might be evaluated more
3957 than once, which is a problem if it has side-effects. */
3964 gnu_result
3968 }
3972 }
3976 {
3977 /* The attribute designator (like an enumeration value). */
3980 /* The Elab_Spec and Elab_Body attributes are special in that
3981 Prefix is a unit, not an object with a GCC equivalent. Similarly
3982 for Elaborated, since that variable isn't otherwise known. */
3986 attribute == Attr_Elab_Body
3989 gnat_node));
3992 }
3996 /* Like 'Access as far as we are concerned. */
4004 {
4005 tree gnu_aggr_type;
4007 /* ??? It is wrong to evaluate the type now, but there doesn't
4008 seem to be any other practical way of doing it. */
4012 gnu_aggr_type = gnu_result_type
4017 gnu_aggr_type
4025 gnu_result
4028 gnu_aggr_type);
4031 gnu_aggr_type,
4034 gnu_result
4035 = build_binary_op
4040 (Next
4042 else
4046 }
4054 else
4061 /* Get the operand expression. */
4065 gnu_result
4076 /* Skip further processing if the conversion is deemed a no-op. */
4078 {
4081 }
4085 /* If the result is a pointer type, see if we are improperly
4086 converting to a stricter alignment. */
4089 {
4095 post_error_ne_tree_2
4099 }
4101 /* If we are converting a descriptor to a function pointer, first
4102 build the pointer. */
4114 {
4117 tree gnu_low;
4118 tree gnu_high;
4120 /* GNAT_RANGE is either an N_Range node or an identifier
4121 denoting a subtype. */
4123 {
4126 }
4129 {
4134 }
4135 else
4140 /* If LOW and HIGH are identical, perform an equality test.
4141 Otherwise, ensure that GNU_OBJECT is only evaluated once
4142 and perform a full range test. */
4146 else
4147 {
4149 gnu_result
4155 }
4159 }
4167 ? RDIV_EXPR
4174 /* These can either be operations on booleans or on modular types.
4175 Fall through for boolean types since that's the way GNU_CODES is
4176 set up. */
4178 Modular_Integer_Kind))
4179 {
4180 enum tree_code code
4191 }
4193 /* ... fall through ... */
4205 {
4208 tree gnu_type;
4214 /* If this is a comparison operator, convert any references to
4215 an unconstrained array value into a reference to the
4216 actual array. */
4218 {
4221 }
4223 /* If the result type is a private type, its full view may be a
4224 numeric subtype. The representation we need is that of its base
4225 type, given that it is the result of an arithmetic operation. */
4227 gnu_type = gnu_result_type
4230 /* If this is a shift whose count is not guaranteed to be correct,
4231 we need to adjust the shift count. */
4234 {
4236 tree gnu_max_shift
4244 gnu_rhs
4245 = build_binary_op
4248 gnu_count_type,
4249 gnu_max_shift,
4251 integer_one_node)),
4252 gnu_rhs);
4253 }
4255 /* For right shifts, the type says what kind of shift to do,
4256 so we may need to choose a different type. In this case,
4257 we have to ignore integer overflow lest it propagates all
4258 the way down and causes a CE to be explicitly raised. */
4261 {
4264 }
4267 {
4270 }
4273 {
4279 }
4281 /* Instead of expanding overflow checks for addition, subtraction
4282 and multiplication itself, the front end will leave this to
4283 the back end when Backend_Overflow_Checks_On_Target is set.
4284 As the GCC back end itself does not know yet how to properly
4285 do overflow checking, do it here. The goal is to push
4286 the expansions further into the back end over time. */
4295 else
4298 /* If this is a logical shift with the shift count not verified,
4299 we must return zero if it is too large. We cannot compensate
4300 above in this case. */
4304 gnu_result
4305 = build_cond_expr
4308 gnu_rhs,
4312 gnu_result);
4313 }
4317 {
4320 tree gnu_false
4327 }
4336 /* This case can apply to a boolean or a modular type.
4337 Fall through for a boolean operand since GNU_CODES is set
4338 up to handle this. */
4342 {
4346 gnu_expr);
4348 }
4350 /* ... fall through ... */
4357 else
4364 gnu_result
4367 else
4373 {
4375 tree gnu_type;
4380 /* The Expression operand can either be an N_Identifier or
4381 Expanded_Name, which must represent a type, or a
4382 N_Qualified_Expression, which contains both the object type and an
4383 initial value for the object. */
4388 {
4389 Entity_Id gnat_desig_type
4397 gnu_init
4402 {
4405 }
4406 else
4407 {
4413 }
4414 }
4415 else
4422 ignore_init_type);
4423 }
4426 /**************************/
4427 /* Chapter 5: Statements */
4428 /**************************/
4440 /* Get the LHS and RHS of the statement and convert any reference to an
4441 unconstrained array into a reference to the underlying array.
4442 If we are not to do range checking and the RHS is an N_Function_Call,
4443 pass the LHS to the call function. */
4446 /* If the type has a size that overflows, convert this into raise of
4447 Storage_Error: execution shouldn't have gotten here anyway. */
4451 N_Raise_Storage_Error);
4456 else
4457 {
4458 gnu_rhs
4461 /* If range check is needed, emit code to generate it. */
4464 gnat_node);
4466 gnu_result
4469 /* If the type being assigned is an array type and the two sides
4470 are not completely disjoint, play safe and use memmove. */
4474 {
4488 }
4489 }
4493 {
4496 /* Make the outer COND_EXPR. Avoid non-determinism. */
4505 /* Now make a COND_EXPR for each of the "else if" parts. Put each
4506 into the previous "else" part and point to where to put any
4507 outer "else". Also avoid non-determinism. */
4511 {
4521 }
4524 }
4548 gnu_result
4558 {
4559 /* The gnu function type of the subprogram currently processed. */
4561 /* The return value from the subprogram. */
4563 /* The place to put the return value. */
4564 tree gnu_lhs;
4566 /* If we are dealing with a "return;" from an Ada procedure with
4567 parameters passed by copy in copy out, we need to return a record
4568 containing the final values of these parameters. If the list
4569 contains only one entry, return just that entry.
4571 For a full description of the copy in copy out parameter mechanism,
4572 see the part of the gnat_to_gnu_entity routine dealing with the
4573 translation of subprograms.
4575 But if we have a return label defined, convert this into
4576 a branch to that label. */
4579 {
4583 }
4586 {
4590 else
4591 gnu_ret_val
4594 }
4596 /* If the Ada subprogram is a function, we just need to return the
4597 expression. If the subprogram returns an unconstrained
4598 array, we have to allocate a new version of the result and
4599 return it. If we return by reference, return a pointer. */
4602 {
4603 /* If the current function returns by target pointer and we
4604 are doing a call, pass that target to the call. */
4607 {
4608 gnu_lhs
4613 }
4614 else
4615 {
4619 /* The original return type was unconstrained so dereference
4620 the TARGET pointer in the actual return value's type. */
4621 gnu_lhs
4624 else
4627 /* Do not remove the padding from GNU_RET_VAL if the inner
4628 type is self-referential since we want to allocate the fixed
4629 size in that case. */
4633 && (TYPE_IS_PADDING_P
4635 && (CONTAINS_PLACEHOLDER_P
4641 gnu_ret_val
4645 {
4647 gnu_ret_val
4649 gnu_ret_val,
4654 }
4655 }
4656 }
4657 else
4658 /* If the Ada subprogram is a regular procedure, just return. */
4662 {
4668 }
4671 }
4679 /***************************/
4680 /* Chapter 6: Subprograms */
4681 /***************************/
4684 /* Unless there is a freeze node, declare the subprogram. We consider
4685 this a "definition" even though we're not generating code for
4686 the subprogram because we will be making the corresponding GCC
4687 node here. */
4696 /* This subprogram doesn't exist for code generation purposes, but we
4697 have to elaborate the types of any parameters and result, unless
4698 they are imported types (nothing to generate in this case). */
4700 /* Process the parameter types first. */
4703 = First_Formal_With_Extras
4712 /* Then the result type, set to Standard_Void_Type for procedures. */
4714 {
4715 Entity_Id gnat_temp_type
4720 }
4726 /* For a child unit identifier go up a level to get the specification.
4727 We get this when we try to find the spec of a child unit package
4728 that is the compilation unit being compiled. */
4742 /************************/
4743 /* Chapter 7: Packages */
4744 /************************/
4760 /* If this is the body of a generic package - do nothing. */
4762 {
4765 }
4776 /********************************/
4777 /* Chapter 8: Visibility Rules */
4778 /********************************/
4782 /* Nothing to do here - but these may appear in list of declarations. */
4786 /*********************/
4787 /* Chapter 9: Tasks */
4788 /*********************/
4799 /*********************************************************/
4800 /* Chapter 10: Program Structure and Compilation Issues */
4801 /*********************************************************/
4805 /* This is not called for the main unit, which is handled in function
4806 gigi above. */
4818 /* Simply process whatever unit is being inserted. */
4826 /***************************/
4827 /* Chapter 11: Exceptions */
4828 /***************************/
4831 /* If there is an At_End procedure attached to this node, and the EH
4832 mechanism is SJLJ, we must have at least a corresponding At_End
4833 handler, unless the No_Exception_Handlers restriction is set. */
4848 else
4869 gnu_constraint_error_label_stack
4874 gnu_storage_error_label_stack
4879 gnu_program_error_label_stack
4883 /******************************/
4884 /* Chapter 12: Generic Units */
4885 /******************************/
4895 /* These nodes can appear on a declaration list but there is nothing to
4896 to be done with them. */
4900 /**************************************************/
4901 /* Chapter 13: Representation Clauses and */
4902 /* Implementation-Dependent Features */
4903 /**************************************************/
4908 /* The only one we need to deal with is 'Address since, for the others,
4909 the front-end puts the information elsewhere. */
4913 /* And we only deal with 'Address if the object has a Freeze node. */
4918 /* Get the value to use as the address and save it as the equivalent
4919 for the object. When it is frozen, gnat_to_gnu_entity will do the
4920 right thing. */
4927 /* We do nothing with these. SEM puts the information elsewhere. */
4933 {
4943 /* First retrieve the 3 operand lists built by the front-end. */
4946 {
4953 }
4957 {
4964 }
4968 gnu_clobbers
4971 gnu_clobbers);
4973 /* Then perform some standard checking and processing on the
4974 operands. In particular, mark them addressable if needed. */
4979 oconstraints
4983 {
4985 constraint
4991 {
4992 /* If the operand is going to end up in memory,
4993 mark it addressable. Note that we don't test
4994 allows_mem like in the input case below; this
4995 is modelled on the C front-end. */
4999 }
5000 else
5004 }
5007 {
5009 constraint
5015 {
5016 /* If the operand is going to end up in memory,
5017 mark it addressable. */
5021 }
5022 else
5026 }
5032 }
5033 else
5038 /****************/
5039 /* Added Nodes */
5040 /****************/
5058 {
5061 tree gnu_obj_type;
5063 tree gnu_obj_size;
5065 unsigned int default_allocator_alignment
5068 /* If this is a thin pointer, we must dereference it to create
5069 a fat pointer, then go back below to a thin pointer. The
5070 reason for this is that we need a fat pointer someplace in
5071 order to properly compute the size. */
5075 gnu_ptr));
5077 /* If this is an unconstrained array, we know the object must
5078 have been allocated with the template in front of the object.
5079 So pass the template address, but get the total size. Do this
5080 by converting to a thin pointer. */
5082 gnu_ptr
5084 (TYPE_OBJECT_RECORD_TYPE
5086 gnu_ptr);
5091 {
5092 gnu_actual_obj_type
5096 gnu_actual_obj_type
5098 gnu_actual_obj_type,
5100 }
5101 else
5109 {
5112 tree gnu_byte_offset
5120 }
5122 /* If the object was allocated from the default storage pool, the
5123 alignment was greater than what the allocator provides, and this
5124 is not a fat or thin pointer, what we have in gnu_ptr here is an
5125 address dynamically adjusted to match the alignment requirement
5126 (see build_allocator). What we need to pass to free is the
5127 initial allocator's return value, which has been stored just in
5128 front of the block we have. */
5133 {
5134 /* We set GNU_PTR
5135 as * (void **)((void *)GNU_PTR - (void *)sizeof(void *))
5136 in two steps: */
5138 /* GNU_PTR (void *)
5139 = (void *)GNU_PTR - (void *)sizeof (void *)) */
5140 gnu_ptr
5141 = build_binary_op
5146 /* GNU_PTR (void *) = *(void **)GNU_PTR */
5147 gnu_ptr
5148 = build_unary_op
5151 gnu_ptr));
5152 }
5157 gnat_node);
5158 }
5165 {
5168 }
5171 gnu_result
5175 /* If the type is VOID, this is a statement, so we need to
5176 generate the code for the call. Handle a Condition, if there
5177 is one. */
5179 {
5186 }
5187 else
5192 {
5197 /* No need for any warning in this case. */
5199 ;
5201 /* If the result is a pointer type, see if we are either converting
5202 from a non-pointer or from a pointer to a type with a different
5203 alias set and warn if so. If the result is defined in the same
5204 unit as this unchecked conversion, we can allow this because we
5205 can know to make the pointer type behave properly. */
5209 {
5222 || !alias_sets_conflict_p
5225 {
5226 post_error_ne
5229 post_error
5231 gnat_node);
5232 post_error_ne
5235 }
5236 }
5238 /* But if the result is a fat pointer type, we have no mechanism to
5239 do that, so we unconditionally warn in problematic cases. */
5241 {
5242 tree gnu_source_array_type
5246 tree gnu_target_array_type
5256 || !alias_sets_conflict_p
5259 {
5260 post_error_ne
5263 post_error
5265 gnat_node);
5266 }
5267 }
5268 }
5281 }
5283 /* If we pushed our level as part of processing the elaboration routine,
5284 pop it back now. */
5286 {
5291 }
5293 /* Set the location information on the result if it is a real expression.
5294 References can be reused for multiple GNAT nodes and they would get
5295 the location information of their last use. Note that we may have
5296 no result if we tried to build a CALL_EXPR node to a procedure with
5297 no side-effects and optimization is enabled. */
5305 /* If we're supposed to return something of void_type, it means we have
5306 something we're elaborating for effect, so just return. */
5310 /* If the result is a constant that overflows, raise constraint error. */
5313 {
5316 gnu_result
5319 N_Raise_Constraint_Error));
5320 }
5322 /* If our result has side-effects and is of an unconstrained type,
5323 make a SAVE_EXPR so that we can be sure it will only be referenced
5324 once. Note we must do this before any conversions. */
5330 /* Now convert the result to the result type, unless we are in one of the
5331 following cases:
5333 1. If this is the Name of an assignment statement or a parameter of
5334 a procedure call, return the result almost unmodified since the
5335 RHS will have to be converted to our type in that case, unless
5336 the result type has a simpler size. Likewise if there is just
5337 a no-op unchecked conversion in-between. Similarly, don't convert
5338 integral types that are the operands of an unchecked conversion
5339 since we need to ignore those conversions (for 'Valid).
5341 2. If we have a label (which doesn't have any well-defined type), a
5342 field or an error, return the result almost unmodified. Also don't
5343 do the conversion if the result type involves a PLACEHOLDER_EXPR in
5344 its size since those are the cases where the front end may have the
5345 type wrong due to "instantiating" the unconstrained record with
5346 discriminant values. Similarly, if the two types are record types
5347 with the same name don't convert. This will be the case when we are
5348 converting from a packable version of a type to its original type and
5349 we need those conversions to be NOPs in order for assignments into
5350 these types to work properly.
5352 3. If the type is void or if we have no result, return error_mark_node
5353 to show we have no result.
5355 4. Finally, if the type of the result is already correct. */
5377 && (CONTAINS_PLACEHOLDER_P
5381 {
5382 /* Remove padding only if the inner object is of self-referential
5383 size: in that case it must be an object of unconstrained type
5384 with a default discriminant and we want to avoid copying too
5385 much data. */
5391 gnu_result);
5392 }
5405 {
5406 /* Remove any padding. */
5410 gnu_result);
5411 }
5419 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on the result. */
5426 }
5427 \f
5428 /* Subroutine of above to push the exception label stack. GNU_STACK is
5429 a pointer to the stack to update and GNAT_LABEL, if present, is the
5430 label to push onto the stack. */
5432 static void
5434 {
5440 }
5441 \f
5442 /* Record the current code position in GNAT_NODE. */
5444 static void
5446 {
5451 }
5453 /* Insert the code for GNAT_NODE at the position saved for that node. */
5455 static void
5457 {
5460 }
5461 \f
5462 /* Start a new statement group chained to the previous group. */
5464 void
5466 {
5469 /* First see if we can get one from the free list. */
5472 else
5478 }
5480 /* Add GNU_STMT to the current statement group. */
5482 void
5484 {
5486 }
5488 /* Similar, but set the location of GNU_STMT to that of GNAT_NODE. */
5490 void
5492 {
5496 }
5498 /* Add a declaration statement for GNU_DECL to the current statement group.
5499 Get SLOC from Entity_Id. */
5501 void
5503 {
5507 /* If this is a variable that Gigi is to ignore, we may have been given
5508 an ERROR_MARK. So test for it. We also might have been given a
5509 reference for a renaming. So only do something for a decl. Also
5510 ignore a TYPE_DECL for an UNCONSTRAINED_ARRAY_TYPE. */
5518 /* If we are global, we don't want to actually output the DECL_EXPR for
5519 this decl since we already have evaluated the expressions in the
5520 sizes and positions as globals and doing it again would be wrong. */
5522 {
5523 /* Mark everything as used to prevent node sharing with subprograms.
5524 Note that walk_tree knows how to deal with TYPE_DECL, but neither
5525 VAR_DECL nor CONST_DECL. This appears to be somewhat arbitrary. */
5529 {
5533 }
5534 /* In any case, we have to deal with our own TYPE_ADA_SIZE field. */
5541 }
5542 else
5545 /* If this is a variable and an initializer is attached to it, it must be
5546 valid for the context. Similar to init_const in create_var_decl_1. */
5553 {
5554 /* If GNU_DECL has a padded type, convert it to the unpadded
5555 type so the assignment is done properly. */
5558 else
5565 {
5568 }
5571 }
5572 }
5574 /* Callback for walk_tree to mark the visited trees rooted at *TP. */
5576 static tree
5578 {
5582 /* Don't mark a dummy type as visited because we want to mark its sizes
5583 and fields once it's filled in. */
5591 }
5593 /* Utility function to unshare expressions wrapped up in a SAVE_EXPR. */
5595 static tree
5598 {
5605 }
5607 /* Mark nodes rooted at *TP with TREE_VISITED and types as having their
5608 sized gimplified. We use this to indicate all variable sizes and
5609 positions in global types may not be shared by any subprogram. */
5611 void
5613 {
5615 }
5617 /* Add GNU_CLEANUP, a cleanup action, to the current code group and
5618 set its location to that of GNAT_NODE if present. */
5620 static void
5622 {
5626 }
5628 /* Set the BLOCK node corresponding to the current code group to GNU_BLOCK. */
5630 void
5632 {
5635 }
5637 /* Return code corresponding to the current code group. It is normally
5638 a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
5639 BLOCK or cleanups were set. */
5641 tree
5643 {
5647 /* If this is a null list, allocate a new STATEMENT_LIST. Then, if there
5648 are cleanups, make a TRY_FINALLY_EXPR. Last, if there is a BLOCK,
5649 make a BIND_EXPR. Note that we nest in that because the cleanup may
5650 reference variables in the block. */
5662 /* Remove this group from the stack and add it to the free list. */
5668 }
5670 /* Add a list of statements from GNAT_LIST, a possibly-empty list of
5671 statements.*/
5673 static void
5675 {
5676 Node_Id gnat_node;
5682 }
5684 /* Build a tree from GNAT_LIST, a possibly-empty list of statements.
5685 If BINDING_P is true, push and pop a binding level around the list. */
5687 static tree
5689 {
5699 }
5700 \f
5701 /* Push and pop routines for stacks. We keep a free list around so we
5702 don't waste tree nodes. */
5704 static void
5706 {
5710 {
5715 }
5716 else
5720 }
5722 static void
5724 {
5730 }
5731 \f
5732 /* Generate GIMPLE in place for the expression at *EXPR_P. */
5734 int
5737 {
5739 tree op;
5745 {
5747 /* If this is for a scalar, just make a VAR_DECL for it. If for
5748 an aggregate, get a null pointer of the appropriate type and
5749 dereference it. */
5753 integer_zero_node));
5754 else
5755 {
5758 }
5764 /* We should only do this if we are just elaborating for side-effects,
5765 but we can't know that yet. */
5772 /* If we're taking the address of a constant CONSTRUCTOR, force it to
5773 be put into static memory. We know it's going to be readonly given
5774 the semantics we have and it's required to be static memory in
5775 the case when the reference is in an elaboration procedure. */
5777 {
5788 }
5790 /* If we are taking the address of a SAVE_EXPR, we are typically
5791 processing a misaligned argument to be passed by reference in a
5792 procedure call. We just mark the operand as addressable + not
5793 readonly here and let the common gimplifier code perform the
5794 temporary creation, initialization, and "instantiation" in place of
5795 the SAVE_EXPR in further operands, in particular in the copy back
5796 code inserted after the call. */
5798 {
5801 }
5803 /* We let the gimplifier process &COND_EXPR and expect it to yield the
5804 address of the selected operand when it is addressable. Besides, we
5805 also expect addressable_p to only let COND_EXPRs where both arms are
5806 addressable reach here. */
5808 ;
5810 /* Otherwise, if we are taking the address of something that is neither
5811 reference, declaration, or constant, make a variable for the operand
5812 here and then take its address. If we don't do it this way, we may
5813 confuse the gimplifier because it needs to know the variable is
5814 addressable at this point. This duplicates code in
5815 internal_get_tmp_var, which is unfortunate. */
5819 {
5821 gimple stmt;
5832 }
5834 /* ... fall through ... */
5838 }
5839 }
5841 /* Generate GIMPLE in place for the statement at *STMT_P. */
5843 static enum gimplify_status
5845 {
5849 {
5855 {
5858 tree t;
5860 /* Set to emit the statements of the loop. */
5863 /* We first emit the start label and then a conditional jump to
5864 the end label if there's a top condition, then the body of the
5865 loop, then a conditional branch to the end label, then the update,
5866 if any, and finally a jump to the start label and the definition
5867 of the end label. */
5869 gnu_start_label),
5870 stmt_p);
5877 void_type_node,
5878 gnu_end_label)),
5879 stmt_p);
5888 void_type_node,
5889 gnu_end_label)),
5890 stmt_p);
5900 gnu_end_label),
5901 stmt_p);
5903 }
5906 /* Build a statement to jump to the corresponding end label, then
5907 see if it needs to be conditional. */
5916 }
5917 }
5918 \f
5919 /* Force references to each of the entities in packages withed by GNAT_NODE.
5920 Operate recursively but check that we aren't elaborating something more
5921 than once.
5923 This routine is exclusively called in type_annotate mode, to compute DDA
5924 information for types in withed units, for ASIS use. */
5926 static void
5928 {
5931 /* Process each unit only once. As we trace the context of all relevant
5932 units transitively, including generic bodies, we may encounter the
5933 same generic unit repeatedly. */
5937 /* Save entities in all context units. A body may have an implicit_with
5938 on its own spec, if the context includes a child unit, so don't save
5939 the spec twice. */
5946 {
5950 {
5967 }
5969 {
5970 Node_Id gnat_body
5973 /* Retrieve compilation unit node of generic body. */
5978 /* If body is available, elaborate its context. */
5981 }
5982 }
5986 }
5987 \f
5988 /* Do the processing of N_Freeze_Entity, GNAT_NODE. */
5990 static void
5992 {
5994 tree gnu_old;
5995 tree gnu_new;
5996 tree gnu_init
6001 /* If this is a package, need to generate code for the package. */
6003 {
6004 insert_code_for
6008 }
6010 /* Check for old definition after the above call. This Freeze_Node
6011 might be for one its Itypes. */
6012 gnu_old
6015 /* If this entity has an Address representation clause, GNU_OLD is the
6016 address, so discard it here. */
6020 /* Don't do anything for class-wide types they are always
6021 transformed into their root type. */
6027 /* Don't do anything for subprograms that may have been elaborated before
6028 their freeze nodes. This can happen, for example because of an inner call
6029 in an instance body, or a previous compilation of a spec for inlining
6030 purposes. */
6035 || (gnu_old
6040 /* If we have a non-dummy type old tree, we have nothing to do, except
6041 aborting if this is the public view of a private type whose full view was
6042 not delayed, as this node was never delayed as it should have been. We
6043 let this happen for concurrent types and their Corresponding_Record_Type,
6044 however, because each might legitimately be elaborated before it's own
6045 freeze node, e.g. while processing the other. */
6049 {
6057 }
6059 /* Reset the saved tree, if any, and elaborate the object or type for real.
6060 If there is a full declaration, elaborate it and copy the type to
6061 GNAT_ENTITY. Likewise if this is the record subtype corresponding to
6062 a class wide type or subtype. */
6064 {
6073 }
6077 {
6080 /* Propagate back-annotations from full view to partial view. */
6090 /* The above call may have defined this entity (the simplest example
6091 of this is when we have a private enumeral type since the bounds
6092 will have the public view. */
6098 }
6099 else
6102 /* If we've made any pointers to the old version of this type, we
6103 have to update them. */
6107 }
6108 \f
6109 /* Process the list of inlined subprograms of GNAT_NODE, which is an
6110 N_Compilation_Unit. */
6112 static void
6114 {
6115 Entity_Id gnat_entity;
6116 Node_Id gnat_body;
6118 /* If we can inline, generate Gimple for all the inlined subprograms.
6119 Define the entity first so we set DECL_EXTERNAL. */
6124 {
6128 {
6129 /* ??? This really should always be Present. */
6133 gnat_body
6135 }
6138 {
6141 }
6142 }
6143 }
6144 \f
6145 /* Elaborate decls in the lists GNAT_DECLS and GNAT_DECLS2, if present.
6146 We make two passes, one to elaborate anything other than bodies (but
6147 we declare a function if there was no spec). The second pass
6148 elaborates the bodies.
6150 GNAT_END_LIST gives the element in the list past the end. Normally,
6151 this is Empty, but can be First_Real_Statement for a
6152 Handled_Sequence_Of_Statements.
6154 We make a complete pass through both lists if PASS1P is true, then make
6155 the second pass over both lists if PASS2P is true. The lists usually
6156 correspond to the public and private parts of a package. */
6158 static void
6161 {
6163 Node_Id gnat_decl;
6173 {
6174 /* For package specs, we recurse inside the declarations,
6175 thus taking the two pass approach inside the boundary. */
6183 /* Similarly for any declarations in the actions of a
6184 freeze node. */
6186 {
6189 }
6191 /* Package bodies with freeze nodes get their elaboration deferred
6192 until the freeze node, but the code must be placed in the right
6193 place, so record the code position now. */
6201 (Corresponding_Spec
6204 record_code_position
6207 /* We defer most subprogram bodies to the second pass. */
6209 {
6211 {
6217 }
6218 }
6220 /* For bodies and stubs that act as their own specs, the entity
6221 itself must be elaborated in the first pass, because it may
6222 be used in other declarations. */
6224 {
6225 Node_Id gnat_subprog_id
6232 }
6234 /* Concurrent stubs stand for the corresponding subprogram bodies,
6235 which are deferred like other bodies. */
6238 ;
6240 else
6242 }
6244 /* Here we elaborate everything we deferred above except for package bodies,
6245 which are elaborated at their freeze nodes. Note that we must also
6246 go inside things (package specs and freeze nodes) the first pass did. */
6252 {
6268 }
6269 }
6270 \f
6271 /* Make a unary operation of kind CODE using build_unary_op, but guard
6272 the operation by an overflow check. CODE can be one of NEGATE_EXPR
6273 or ABS_EXPR. GNU_TYPE is the type desired for the result. Usually
6274 the operation is to be performed in that type. GNAT_NODE is the gnat
6275 node conveying the source location for which the error should be
6276 signaled. */
6278 static tree
6280 Node_Id gnat_node)
6281 {
6290 }
6292 /* Make a binary operation of kind CODE using build_binary_op, but guard
6293 the operation by an overflow check. CODE can be one of PLUS_EXPR,
6294 MINUS_EXPR or MULT_EXPR. GNU_TYPE is the type desired for the result.
6295 Usually the operation is to be performed in that type. GNAT_NODE is
6296 the GNAT node conveying the source location for which the error should
6297 be signaled. */
6299 static tree
6302 {
6307 tree gnu_expr;
6310 tree rhs_lt_zero;
6311 tree check_pos;
6312 tree check_neg;
6313 tree check;
6318 /* Prefer a constant or known-positive rhs to simplify checks. */
6323 {
6327 }
6330 ? integer_zero_node
6333 /* ??? Should use more efficient check for operand_equal_p (lhs, rhs, 0) */
6335 /* Try a few strategies that may be cheaper than the general
6336 code at the end of the function, if the rhs is not known.
6337 The strategies are:
6338 - Call library function for 64-bit multiplication (complex)
6339 - Widen, if input arguments are sufficiently small
6340 - Determine overflow using wrapped result for addition/subtraction. */
6343 {
6344 /* Even for add/subtract double size to get another base type. */
6348 {
6354 }
6359 {
6366 tree check = build_binary_op
6375 return
6377 }
6380 {
6382 tree wrapped_expr = convert
6387 tree result = convert
6390 /* Overflow when (rhs < 0) ^ (wrapped_expr < lhs)), for addition
6391 or when (rhs < 0) ^ (wrapped_expr > lhs) for subtraction. */
6392 tree check = build_binary_op
6397 return
6399 }
6400 }
6403 {
6405 /* When rhs >= 0, overflow when lhs > type_max - rhs. */
6410 /* When rhs < 0, overflow when lhs < type_min - rhs. */
6417 /* When rhs >= 0, overflow when lhs < type_min + rhs. */
6422 /* When rhs < 0, overflow when lhs > type_max + rhs. */
6429 /* The check here is designed to be efficient if the rhs is constant,
6430 but it will work for any rhs by using integer division.
6431 Four different check expressions determine wether X * C overflows,
6432 depending on C.
6433 C == 0 => false
6434 C > 0 => X > type_max / C || X < type_min / C
6435 C == -1 => X == type_min
6436 C < -1 => X > type_min / C || X < type_max / C */
6458 }
6462 /* If we can fold the expression to a constant, just return it.
6463 The caller will deal with overflow, no need to generate a check. */
6471 }
6473 /* Emit code for a range check. GNU_EXPR is the expression to be checked,
6474 GNAT_RANGE_TYPE the gnat type or subtype containing the bounds against
6475 which we have to check. GNAT_NODE is the GNAT node conveying the source
6476 location for which the error should be signaled. */
6478 static tree
6480 {
6486 /* If GNU_EXPR has GNAT_RANGE_TYPE as its base type, no check is needed.
6487 This can for example happen when translating 'Val or 'Value. */
6491 /* If GNU_EXPR has an integral type that is narrower than GNU_RANGE_TYPE,
6492 we can't do anything since we might be truncating the bounds. No
6493 check is needed in this case. */
6499 /* Checked expressions must be evaluated only once. */
6502 /* There's no good type to use here, so we might as well use
6503 integer_type_node. Note that the form of the check is
6504 (not (expr >= lo)) or (not (expr <= hi))
6505 the reason for this slightly convoluted form is that NaNs
6506 are not considered to be in range in the float case. */
6507 return emit_check
6509 invert_truthvalue
6513 invert_truthvalue
6517 gnu_high)))),
6519 }
6520 \f
6521 /* Emit code for an index check. GNU_ARRAY_OBJECT is the array object which
6522 we are about to index, GNU_EXPR is the index expression to be checked,
6523 GNU_LOW and GNU_HIGH are the lower and upper bounds against which GNU_EXPR
6524 has to be checked. Note that for index checking we cannot simply use the
6525 emit_range_check function (although very similar code needs to be generated
6526 in both cases) since for index checking the array type against which we are
6527 checking the indices may be unconstrained and consequently we need to get
6528 the actual index bounds from the array object itself (GNU_ARRAY_OBJECT).
6529 The place where we need to do that is in subprograms having unconstrained
6530 array formal parameters. GNAT_NODE is the GNAT node conveying the source
6531 location for which the error should be signaled. */
6533 static tree
6536 {
6537 tree gnu_expr_check;
6539 /* Checked expressions must be evaluated only once. */
6542 /* Must do this computation in the base type in case the expression's
6543 type is an unsigned subtypes. */
6546 /* If GNU_LOW or GNU_HIGH are a PLACEHOLDER_EXPR, qualify them by
6547 the object we are handling. */
6551 /* There's no good type to use here, so we might as well use
6552 integer_type_node. */
6553 return emit_check
6556 gnu_expr_check,
6558 gnu_low)),
6560 gnu_expr_check,
6562 gnu_high))),
6564 }
6565 \f
6566 /* GNU_COND contains the condition corresponding to an access, discriminant or
6567 range check of value GNU_EXPR. Build a COND_EXPR that returns GNU_EXPR if
6568 GNU_COND is false and raises a CONSTRAINT_ERROR if GNU_COND is true.
6569 REASON is the code that says why the exception was raised. GNAT_NODE is
6570 the GNAT node conveying the source location for which the error should be
6571 signaled. */
6573 static tree
6575 {
6576 tree gnu_call
6578 tree gnu_result
6582 gnu_expr);
6584 /* GNU_RESULT has side effects if and only if GNU_EXPR has:
6585 we don't need to evaluate it just for the check. */
6588 /* ??? Unfortunately, if we don't put a SAVE_EXPR around this whole thing,
6589 we will repeatedly do the test and, at compile time, we will repeatedly
6590 visit it during unsharing, which leads to an exponential explosion. */
6592 }
6593 \f
6594 /* Return an expression that converts GNU_EXPR to GNAT_TYPE, doing overflow
6595 checks if OVERFLOW_P is true and range checks if RANGE_P is true.
6596 GNAT_TYPE is known to be an integral type. If TRUNCATE_P true, do a
6597 float to integer conversion with truncation; otherwise round.
6598 GNAT_NODE is the GNAT node conveying the source location for which the
6599 error should be signaled. */
6601 static tree
6604 {
6611 /* If we are not doing any checks, the output is an integral type, and
6612 the input is not a floating type, just do the conversion. This
6613 shortcut is required to avoid problems with packed array types
6614 and simplifies code in all cases anyway. */
6619 /* First convert the expression to its base type. This
6620 will never generate code, but makes the tests below much simpler.
6621 But don't do this if converting from an integer type to an unconstrained
6622 array type since then we need to get the bounds from the original
6623 (unpacked) type. */
6627 /* If overflow checks are requested, we need to be sure the result will
6628 fit in the output base type. But don't do this if the input
6629 is integer and the output floating-point. */
6632 {
6633 /* Ensure GNU_EXPR only gets evaluated once. */
6641 /* Convert the lower bounds to signed types, so we're sure we're
6642 comparing them properly. Likewise, convert the upper bounds
6643 to unsigned types. */
6657 /* Check each bound separately and only if the result bound
6658 is tighter than the bound on the input type. Note that all the
6659 types are base types, so the bounds must be constant. Also,
6660 the comparison is done in the base type of the input, which
6661 always has the proper signedness. First check for input
6662 integer (which means output integer), output float (which means
6663 both float), or mixed, in which case we always compare.
6664 Note that we have to do the comparison which would *fail* in the
6665 case of an error since if it's an FP comparison and one of the
6666 values is a NaN or Inf, the comparison will fail. */
6673 gnu_cond
6674 = invert_truthvalue
6677 gnu_out_lb)));
6685 gnu_cond
6687 invert_truthvalue
6689 gnu_input,
6691 gnu_out_ub))));
6696 }
6698 /* Now convert to the result base type. If this is a non-truncating
6699 float-to-integer conversion, round. */
6702 {
6708 /* The following calculations depend on proper rounding to even
6709 of each arithmetic operation. In order to prevent excess
6710 precision from spoiling this property, use the widest hardware
6711 floating-point type if FP_ARITH_MAY_WIDEN is true. */
6712 calc_type
6715 /* FIXME: Should not have padding in the first place. */
6720 /* Compute the exact value calc_type'Pred (0.5) at compile time. */
6724 half_minus_pred_half);
6727 /* If the input is strictly negative, subtract this value
6728 and otherwise add it from the input. For 0.5, the result
6729 is exactly between 1.0 and the machine number preceding 1.0
6730 (for calc_type). Since the last bit of 1.0 is even, this 0.5
6731 will round to 1.0, while all other number with an absolute
6732 value less than 0.5 round to 0.0. For larger numbers exactly
6733 halfway between integers, rounding will always be correct as
6734 the true mathematical result will be closer to the higher
6735 integer compared to the lower one. So, this constant works
6736 for all floating-point numbers.
6738 The reason to use the same constant with subtract/add instead
6739 of a positive and negative constant is to allow the comparison
6740 to be scheduled in parallel with retrieval of the constant and
6741 conversion of the input to the calc_type (if necessary). */
6748 gnu_add_pred_half
6750 gnu_subtract_pred_half
6754 }
6760 else
6763 /* Finally, do the range check if requested. Note that if the
6764 result type is a modular type, the range check is actually
6765 an overflow check. */
6773 }
6774 \f
6775 /* Return true if TYPE is a smaller packable version of RECORD_TYPE. */
6777 static bool
6779 {
6782 /* We're not interested in variants here. */
6786 /* Like a variant, a packable version keeps the original TYPE_NAME. */
6797 }
6799 /* Return true if GNU_EXPR can be directly addressed. This is the case
6800 unless it is an expression involving computation or if it involves a
6801 reference to a bitfield or to an object not sufficiently aligned for
6802 its type. If GNU_TYPE is non-null, return true only if GNU_EXPR can
6803 be directly addressed as an object of this type.
6805 *** Notes on addressability issues in the Ada compiler ***
6807 This predicate is necessary in order to bridge the gap between Gigi
6808 and the middle-end about addressability of GENERIC trees. A tree
6809 is said to be addressable if it can be directly addressed, i.e. if
6810 its address can be taken, is a multiple of the type's alignment on
6811 strict-alignment architectures and returns the first storage unit
6812 assigned to the object represented by the tree.
6814 In the C family of languages, everything is in practice addressable
6815 at the language level, except for bit-fields. This means that these
6816 compilers will take the address of any tree that doesn't represent
6817 a bit-field reference and expect the result to be the first storage
6818 unit assigned to the object. Even in cases where this will result
6819 in unaligned accesses at run time, nothing is supposed to be done
6820 and the program is considered as erroneous instead (see PR c/18287).
6822 The implicit assumptions made in the middle-end are in keeping with
6823 the C viewpoint described above:
6824 - the address of a bit-field reference is supposed to be never
6825 taken; the compiler (generally) will stop on such a construct,
6826 - any other tree is addressable if it is formally addressable,
6827 i.e. if it is formally allowed to be the operand of ADDR_EXPR.
6829 In Ada, the viewpoint is the opposite one: nothing is addressable
6830 at the language level unless explicitly declared so. This means
6831 that the compiler will both make sure that the trees representing
6832 references to addressable ("aliased" in Ada parlance) objects are
6833 addressable and make no real attempts at ensuring that the trees
6834 representing references to non-addressable objects are addressable.
6836 In the first case, Ada is effectively equivalent to C and handing
6837 down the direct result of applying ADDR_EXPR to these trees to the
6838 middle-end works flawlessly. In the second case, Ada cannot afford
6839 to consider the program as erroneous if the address of trees that
6840 are not addressable is requested for technical reasons, unlike C;
6841 as a consequence, the Ada compiler must arrange for either making
6842 sure that this address is not requested in the middle-end or for
6843 compensating by inserting temporaries if it is requested in Gigi.
6845 The first goal can be achieved because the middle-end should not
6846 request the address of non-addressable trees on its own; the only
6847 exception is for the invocation of low-level block operations like
6848 memcpy, for which the addressability requirements are lower since
6849 the type's alignment can be disregarded. In practice, this means
6850 that Gigi must make sure that such operations cannot be applied to
6851 non-BLKmode bit-fields.
6853 The second goal is achieved by means of the addressable_p predicate
6854 and by inserting SAVE_EXPRs around trees deemed non-addressable.
6855 They will be turned during gimplification into proper temporaries
6856 whose address will be used in lieu of that of the original tree. */
6858 static bool
6860 {
6861 /* The size of the real type of the object must not be smaller than
6862 that of the expected type, otherwise an indirect access in the
6863 latter type would be larger than the object. Only records need
6864 to be considered in practice. */
6871 {
6876 /* All DECLs are addressable: if they are in a register, we can force
6877 them to memory. */
6891 /* We accept &COND_EXPR as soon as both operands are addressable and
6892 expect the outcome to be the address of the selected operand. */
6898 /* Even with DECL_BIT_FIELD cleared, we have to ensure that
6899 the field is sufficiently aligned, in case it is subject
6900 to a pragma Component_Alignment. But we don't need to
6901 check the alignment of the containing record, as it is
6902 guaranteed to be not smaller than that of its most
6903 aligned field that is not a bit-field. */
6904 && (!STRICT_ALIGNMENT
6907 /* The field of a padding record is always addressable. */
6921 {
6922 /* This is addressable if we can avoid a copy. */
6926 && (!STRICT_ALIGNMENT
6931 && (!STRICT_ALIGNMENT
6937 }
6941 }
6942 }
6943 \f
6944 /* Do the processing for the declaration of a GNAT_ENTITY, a type. If
6945 a separate Freeze node exists, delay the bulk of the processing. Otherwise
6946 make a GCC type for GNAT_ENTITY and set up the correspondence. */
6948 void
6950 {
6951 tree gnu_old
6953 tree gnu_new;
6955 /* If we are to delay elaboration of this type, just do any
6956 elaborations needed for expressions within the declaration and
6957 make a dummy type entry for this node and its Full_View (if
6958 any) in case something points to it. Don't do this if it
6959 has already been done (the only way that can happen is if
6960 the private completion is also delayed). */
6966 {
6970 {
6976 }
6979 }
6981 /* If we saved away a dummy type for this node it means that this
6982 made the type that corresponds to the full type of an incomplete
6983 type. Clear that type for now and then update the type in the
6984 pointers. */
6986 {
6991 }
6993 /* Now fully elaborate the type. */
6997 /* If we have an old type and we've made pointers to this type,
6998 update those pointers. */
7003 /* If this is a record type corresponding to a task or protected type
7004 that is a completion of an incomplete type, perform a similar update
7005 on the type. ??? Including protected types here is a guess. */
7009 {
7010 tree gnu_task_old
7020 }
7021 }
7022 \f
7023 /* GNAT_ENTITY is the type of the resulting constructors,
7024 GNAT_ASSOC is the front of the Component_Associations of an N_Aggregate,
7025 and GNU_TYPE is the GCC type of the corresponding record.
7027 Return a CONSTRUCTOR to build the record. */
7029 static tree
7031 {
7034 /* We test for GNU_FIELD being empty in the case where a variant
7035 was the last thing since we don't take things off GNAT_ASSOC in
7036 that case. We check GNAT_ASSOC in case we have a variant, but it
7037 has no fields. */
7041 {
7046 /* The expander is supposed to put a single component selector name
7047 in every record component association. */
7050 /* Ignore fields that have Corresponding_Discriminants since we'll
7051 be setting that field in the parent. */
7056 /* Also ignore discriminants of Unchecked_Unions. */
7061 /* Before assigning a value in an aggregate make sure range checks
7062 are done if required. Then convert to the type of the field. */
7068 /* Add the field and expression to the list. */
7070 }
7074 #ifdef ENABLE_CHECKING
7075 {
7076 tree gnu_field;
7078 /* Verify every entry in GNU_LIST was used. */
7081 }
7082 #endif
7085 }
7087 /* Build a possibly nested constructor for array aggregates. GNAT_EXPR is
7088 the first element of an array aggregate. It may itself be an aggregate.
7089 GNU_ARRAY_TYPE is the GCC type corresponding to the array aggregate.
7090 GNAT_COMPONENT_TYPE is the type of the array component; it is needed
7091 for range checking. */
7093 static tree
7095 Entity_Id gnat_component_type)
7096 {
7099 tree gnu_expr;
7102 {
7103 /* If the expression is itself an array aggregate then first build the
7104 innermost constructor if it is part of our array (multi-dimensional
7105 case). */
7111 gnat_component_type);
7112 else
7113 {
7116 /* Before assigning the element to the array, make sure it is
7117 in range. */
7120 }
7122 gnu_expr_list
7124 gnu_expr_list);
7127 }
7130 }
7131 \f
7132 /* Subroutine of assoc_to_constructor: VALUES is a list of field associations,
7133 some of which are from RECORD_TYPE. Return a CONSTRUCTOR consisting
7134 of the associations that are from RECORD_TYPE. If we see an internal
7135 record, make a recursive call to fill it in as well. */
7137 static tree
7139 {
7144 {
7147 /* _Parent is an internal field, but may have values in the aggregate,
7148 so check for values first. */
7150 {
7153 }
7156 {
7161 }
7162 else
7163 /* If we have a record subtype, the names will match, but not the
7164 actual FIELD_DECLs. */
7167 {
7170 }
7176 }
7179 }
7180 \f
7181 /* EXP is to be treated as an array or record. Handle the cases when it is
7182 an access object and perform the required dereferences. */
7184 static tree
7186 {
7187 /* If the type is a pointer, dereference it. */
7192 /* If we got a padded type, remove it too. */
7198 }
7199 \f
7200 /* Protect EXP from multiple evaluation. This may make a SAVE_EXPR. */
7202 tree
7204 {
7207 /* If this has no side effects, we don't need to do anything. */
7211 /* If it is a conversion, protect what's inside the conversion.
7212 Similarly, if we're indirectly referencing something, we only
7213 actually need to protect the address since the data itself can't
7214 change in these situations. */
7223 /* If EXP is a fat pointer or something that can be placed into a register,
7224 just make a SAVE_EXPR. */
7228 /* Otherwise, dereference, protect the address, and re-reference. */
7229 else
7230 return
7234 exp)));
7235 }
7236 \f
7237 /* This is equivalent to stabilize_reference in tree.c, but we know how to
7238 handle our own nodes and we take extra arguments. FORCE says whether to
7239 force evaluation of everything. We set SUCCESS to true unless we walk
7240 through something we don't know how to stabilize. */
7242 tree
7244 {
7247 tree result;
7249 /* Assume we'll success unless proven otherwise. */
7253 {
7258 /* No action is needed in this case. */
7262 CASE_CONVERT:
7266 result
7269 success));
7276 force));
7282 success),
7289 success),
7291 force),
7293 force));
7300 success),
7302 force),
7311 /* This generates better code than the scheme in protect_multiple_eval
7312 because large objects will be returned via invisible reference in
7313 most ABIs so the temporary will directly be filled by the callee. */
7318 /* Constructors with 1 element are used extensively to formally
7319 convert objects to special wrapping types. */
7322 {
7323 tree index
7325 tree value
7327 result
7330 force));
7331 }
7332 else
7333 {
7336 }
7342 /* ... fall through to failure ... */
7344 /* If arg isn't a kind of lvalue we recognize, make no change.
7345 Caller should recognize the error for an invalid lvalue. */
7349 }
7353 /* TREE_THIS_VOLATILE and TREE_SIDE_EFFECTS attached to the initial
7354 expression may not be sustained across some paths, such as the way via
7355 build1 for INDIRECT_REF. We re-populate those flags here for the general
7356 case, which is consistent with the GCC version of this routine.
7358 Special care should be taken regarding TREE_SIDE_EFFECTS, because some
7359 paths introduce side effects where there was none initially (e.g. calls
7360 to save_expr), and we also want to keep track of that. */
7366 }
7368 /* Wrapper around maybe_stabilize_reference, for common uses without
7369 lvalue restrictions and without need to examine the success
7370 indication. */
7372 static tree
7374 {
7377 }
7379 /* Similar to stabilize_reference_1 in tree.c, but supports an extra
7380 arg to force a SAVE_EXPR for everything. */
7382 static tree
7384 {
7387 tree result;
7389 /* We cannot ignore const expressions because it might be a reference
7390 to a const array but whose index contains side-effects. But we can
7391 ignore things that are actual constant or that already have been
7392 handled by this function. */
7398 {
7407 /* If this is a COMPONENT_REF of a fat pointer, save the entire
7408 fat pointer. This may be more efficient, but will also allow
7409 us to more easily find the match for the PLACEHOLDER_EXPR. */
7414 force),
7418 else
7423 /* Constants need no processing. In fact, we should never reach
7424 here. */
7428 /* Recursively stabilize each operand. */
7432 force));
7436 /* Recursively stabilize each operand. */
7439 force));
7444 }
7451 }
7452 \f
7453 /* Convert SLOC into LOCUS. Return true if SLOC corresponds to a source code
7454 location and false if it doesn't. In the former case, set the Gigi global
7455 variable REF_FILENAME to the simple debug file name as given by sinput. */
7457 bool
7459 {
7464 {
7467 }
7468 else
7469 {
7475 /* Translate the location according to the line-map.h formula. */
7479 }
7481 ref_filename
7482 = IDENTIFIER_POINTER
7483 (get_identifier
7487 }
7489 /* Similar to set_expr_location, but start with the Sloc of GNAT_NODE and
7490 don't do anything if it doesn't correspond to a source location. */
7492 static void
7494 {
7495 location_t locus;
7501 }
7502 \f
7503 /* Return a colon-separated list of encodings contained in encoded Ada
7504 name. */
7508 {
7512 }
7514 /* Extract the Ada name from an encoded name. */
7518 {
7522 }
7523 \f
7524 /* Post an error message. MSG is the error message, properly annotated.
7525 NODE is the node at which to post the error and the node to use for the
7526 "&" substitution. */
7528 void
7530 {
7531 String_Template temp;
7532 Fat_Pointer fp;
7538 }
7540 /* Similar, but NODE is the node at which to post the error and ENT
7541 is the node to use for the "&" substitution. */
7543 void
7545 {
7546 String_Template temp;
7547 Fat_Pointer fp;
7553 }
7555 /* Similar, but NODE is the node at which to post the error, ENT is the node
7556 to use for the "&" substitution, and N is the number to use for the ^. */
7558 void
7560 {
7561 String_Template temp;
7562 Fat_Pointer fp;
7570 }
7571 \f
7572 /* Similar to post_error_ne_num, but T is a GCC tree representing the
7573 number to write. If the tree represents a constant that fits within
7574 a host integer, the text inside curly brackets in MSG will be output
7575 (presumably including a '^'). Otherwise that text will not be output
7576 and the text inside square brackets will be output instead. */
7578 void
7580 {
7583 Fat_Pointer fp;
7591 #if HOST_BITS_PER_WIDE_INT > HOST_BITS_PER_INT
7592 &&
7593 compare_tree_int
7595 #endif
7596 )
7597 {
7600 }
7601 else
7605 {
7611 ;
7612 else
7614 }
7621 }
7623 /* Similar to post_error_ne_tree, except that NUM is a second
7624 integer to write in the message. */
7626 void
7629 {
7632 }
7633 \f
7634 /* Initialize the table that maps GNAT codes to GCC codes for simple
7635 binary and unary operations. */
7637 static void
7639 {
7665 }
7667 /* Return a label to branch to for the exception type in KIND or NULL_TREE
7668 if none. */
7670 tree
7672 {
7679 else
7681 }