| blob | 71c9e862aba6aa17395c7438836ecb1329acd855 |
1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * T R A N S *
6 * *
7 * C Implementation File *
8 * *
9 * Copyright (C) 1992-2010, Free Software Foundation, Inc. *
10 * *
11 * GNAT is free software; you can redistribute it and/or modify it under *
12 * terms of the GNU General Public License as published by the Free Soft- *
13 * ware Foundation; either version 3, or (at your option) any later ver- *
14 * sion. GNAT is distributed in the hope that it will be useful, but WITH- *
15 * OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY *
16 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License *
17 * for more details. You should have received a copy of the GNU General *
18 * Public License distributed with GNAT; see file COPYING3. If not 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 ****************************************************************************/
56 /* We should avoid allocating more than ALLOCA_THRESHOLD bytes via alloca,
57 for fear of running out of stack space. If we need more, we use xmalloc
58 instead. */
59 #define ALLOCA_THRESHOLD 1000
61 /* Let code below know whether we are targetting VMS without need of
62 intrusive preprocessor directives. */
63 #ifndef TARGET_ABI_OPEN_VMS
64 #define TARGET_ABI_OPEN_VMS 0
65 #endif
67 /* For efficient float-to-int rounding, it is necessary to know whether
68 floating-point arithmetic may use wider intermediate results. When
69 FP_ARITH_MAY_WIDEN is not defined, be conservative and only assume
70 that arithmetic does not widen if double precision is emulated. */
71 #ifndef FP_ARITH_MAY_WIDEN
72 #if defined(HAVE_extendsfdf2)
73 #define FP_ARITH_MAY_WIDEN HAVE_extendsfdf2
74 #else
75 #define FP_ARITH_MAY_WIDEN 0
76 #endif
77 #endif
79 /* Pointers to front-end tables accessed through macros. */
89 /* Highest number in the front-end node table. */
92 /* Current node being treated, in case abort called. */
93 Node_Id error_gnat_node;
95 /* True when gigi is being called on an analyzed but unexpanded
96 tree, and the only purpose of the call is to properly annotate
97 types with representation information. */
100 /* Current filename without path. */
103 /* When not optimizing, we cache the 'First, 'Last and 'Length attributes
104 of unconstrained array IN parameters to avoid emitting a great deal of
105 redundant instructions to recompute them each time. */
109 tree first;
110 tree last;
111 tree length;
112 };
121 };
123 #define f_parm_attr_cache \
124 DECL_STRUCT_FUNCTION (current_function_decl)->language->parm_attr_cache
126 /* A structure used to gather together information about a statement group.
127 We use this to gather related statements, for example the "then" part
128 of a IF. In the case where it represents a lexical scope, we may also
129 have a BLOCK node corresponding to it and/or cleanups. */
136 };
140 /* List of unused struct stmt_group nodes. */
143 /* A structure used to record information on elaboration procedures
144 we've made and need to process.
146 ??? gnat_node should be Node_Id, but gengtype gets confused. */
152 };
156 /* Free list of TREE_LIST nodes used for stacks. */
159 /* List of TREE_LIST nodes representing a stack of exception pointer
160 variables. TREE_VALUE is the VAR_DECL that stores the address of
161 the raised exception. Nonzero means we are in an exception
162 handler. Not used in the zero-cost case. */
165 /* List of TREE_LIST nodes used to store the current elaboration procedure
166 decl. TREE_VALUE is the decl. */
169 /* Variable that stores a list of labels to be used as a goto target instead of
170 a return in some functions. See processing for N_Subprogram_Body. */
173 /* List of TREE_LIST nodes representing a stack of LOOP_STMT nodes.
174 TREE_VALUE of each entry is the label of the corresponding LOOP_STMT. */
177 /* List of TREE_LIST nodes representing labels for switch statements.
178 TREE_VALUE of each entry is the label at the end of the switch. */
181 /* List of TREE_LIST nodes containing the stacks for N_{Push,Pop}_*_Label. */
186 /* Map GNAT tree codes to GCC tree codes for simple expressions. */
219 /* Hooks for debug info back-ends, only supported and used in a restricted set
220 of configurations. */
223 \f
224 /* This is the main program of the back-end. It sets up all the table
225 structures and then generates code. */
227 void
237 {
238 Entity_Id gnat_literal;
259 /* Declare the name of the compilation unit as the first global
260 name in order to make the middle-end fully deterministic. */
265 {
266 /* Use the identifier table to make a permanent copy of the filename as
267 the name table gets reallocated after Gigi returns but before all the
268 debugging information is output. The __gnat_to_canonical_file_spec
269 call translates filenames from pragmas Source_Reference that contain
270 host style syntax not understood by gdb. */
272 = IDENTIFIER_POINTER
273 (get_identifier
274 (__gnat_to_canonical_file_spec
277 /* We rely on the order isomorphism between files and line maps. */
280 /* We create the line map for a source file at once, with a fixed number
281 of columns chosen to avoid jumping over the next power of 2. */
286 }
288 /* Initialize ourselves. */
293 /* If we are just annotating types, give VOID_TYPE zero sizes to avoid
294 errors. */
296 {
299 }
301 /* If the GNU type extensions to DWARF are available, setup the hooks. */
302 #if defined (DWARF2_DEBUGGING_INFO) && defined (DWARF2_GNU_TYPE_EXTENSIONS)
303 /* We condition the name demangling and the generation of type encoding
304 strings on -gdwarf+ and always set descriptive types on. */
306 {
309 }
311 #endif
313 /* Enable GNAT stack checking method if needed */
317 /* Retrieve alignment settings. */
321 /* Record the builtin types. Define `integer' and `character' first so that
322 dbx will output them first. */
328 /* Save the type we made for integer as the type for Standard.Integer. */
333 /* Likewise for character as the type for Standard.Character. */
338 /* Likewise for boolean as the type for Standard.Boolean. */
362 /* Now declare runtime functions. */
365 /* malloc is a function declaration tree for a function to allocate
366 memory. */
367 malloc_decl
375 /* malloc32 is a function declaration tree for a function to allocate
376 32-bit memory on a 64-bit system. Needed only on 64-bit VMS. */
377 malloc32_decl
385 /* free is a function declaration tree for a function to free memory. */
386 free_decl
390 ptr_void_type_node,
391 t)),
394 /* This is used for 64-bit multiplication with overflow checking. */
395 mulv64_decl
401 /* Name of the _Parent field in tagged record types. */
404 /* Make the types and functions used for exception processing. */
405 jmpbuf_type
411 /* Functions to get and set the jumpbuf pointer for the current thread. */
412 get_jmpbuf_decl
413 = create_subprog_decl
417 /* Avoid creating superfluous edges to __builtin_setjmp receivers. */
421 set_jmpbuf_decl
422 = create_subprog_decl
424 NULL_TREE,
430 /* setjmp returns an integer and has one operand, which is a pointer to
431 a jmpbuf. */
432 setjmp_decl
433 = 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
452 /* Hooks to call when entering/leaving an exception handler. */
453 begin_handler_decl
457 ptr_void_type_node,
458 t)),
462 end_handler_decl
466 ptr_void_type_node,
467 t)),
471 /* If in no exception handlers mode, all raise statements are redirected to
472 __gnat_last_chance_handler. No need to redefine raise_nodefer_decl since
473 this procedure will never be called in this mode. */
475 {
476 tree decl
477 = create_subprog_decl
481 build_pointer_type
484 integer_type_node,
485 t))),
490 }
491 else
492 /* Otherwise, make one decl for each exception reason. */
494 {
499 = create_subprog_decl
503 build_pointer_type
506 integer_type_node,
507 t))),
509 }
512 {
517 TYPE_QUAL_VOLATILE);
518 }
520 /* Set the types that GCC and Gigi use from the front end. */
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. */
629 /* Finally see if we have any elaboration procedures to deal with. */
631 {
634 /* Unshare SAVE_EXPRs between subprograms. These are not unshared by
635 the gimplifier for obvious reasons, but it turns out that we need to
636 unshare them for the global level because of SAVE_EXPRs made around
637 checks for global objects and around allocators for global objects
638 of variable size, in order to prevent node sharing in the underlying
639 expression. Note that this implicitly assumes that the SAVE_EXPR
640 nodes themselves are not shared between subprograms, which would be
641 an upstream bug for which we would not change the outcome. */
644 /* We should have a BIND_EXPR but it may not have any statements in it.
645 If it doesn't have any, we have nothing to do except for setting the
646 flag on the GNAT node. Otherwise, process the function as others. */
652 else
653 {
656 }
657 }
659 /* We cannot track the location of errors past this point. */
661 }
662 \f
663 /* Return a positive value if an lvalue is required for GNAT_NODE, which is
664 an N_Attribute_Reference. */
666 static int
668 {
670 {
705 }
706 }
708 /* Return a positive value if an lvalue is required for GNAT_NODE. GNU_TYPE
709 is the type that will be used for GNAT_NODE in the translated GNU tree.
710 CONSTANT indicates whether the underlying object represented by GNAT_NODE
711 is constant in the Ada sense. If it is, ADDRESS_OF_CONSTANT indicates
712 whether its value is the address of a constant and ALIASED whether it is
713 aliased. If it isn't, ADDRESS_OF_CONSTANT and ALIASED are ignored.
715 The function climbs up the GNAT tree starting from the node and returns 1
716 upon encountering a node that effectively requires an lvalue downstream.
717 It returns int instead of bool to facilitate usage in non-purely binary
718 logic contexts. */
720 static int
723 {
727 {
737 /* If the parameter is by reference, an lvalue is required. */
743 /* Only the array expression can require an lvalue. */
747 /* ??? Consider that referencing an indexed component with a
748 non-constant index forces the whole aggregate to memory.
749 Note that N_Integer_Literal is conservative, any static
750 expression in the RM sense could probably be accepted. */
757 /* ... fall through ... */
760 /* Only the array expression can require an lvalue. */
774 /* We need to make a real renaming only if the constant object is
775 aliased or if we may use a renaming pointer; otherwise we can
776 optimize and return the rvalue. We make an exception if the object
777 is an identifier since in this case the rvalue can be propagated
778 attached to the CONST_DECL. */
780 || aliased
781 /* This should match the constant case of the renaming code. */
782 || Is_Composite_Type
787 /* We cannot use a constructor if this is an atomic object because
788 the actual assignment might end up being done component-wise. */
792 /* We don't use a constructor if this is a class-wide object
793 because the effective type of the object is the equivalent
794 type of the class-wide subtype and it smashes most of the
795 data into an array of bytes to which we cannot convert. */
800 /* We cannot use a constructor if the LHS is an atomic object because
801 the actual assignment might end up being done component-wise. */
809 /* We must look through all conversions for composite types because we
810 may need to bypass an intermediate conversion to a narrower record
811 type that is generated for a formal conversion, e.g. the conversion
812 to the root type of a hierarchy of tagged types generated for the
813 formal conversion to the class-wide type. */
817 /* ... fall through ... */
826 /* We should only reach here through the N_Qualified_Expression case
827 and, therefore, only for composite types. Force an lvalue since
828 a block-copy to the newly allocated area of memory is made. */
832 /* We look through dereferences for address of constant because we need
833 to handle the special cases listed above. */
839 /* ... fall through ... */
843 }
846 }
848 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Identifier,
849 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer
850 to where we should place the result type. */
852 static tree
854 {
858 /* Whether we should require an lvalue for GNAT_NODE. Needed in
859 specific circumstances only, so evaluated lazily. < 0 means
860 unknown, > 0 means known true, 0 means known false. */
863 /* If GNAT_NODE is a constant, whether we should use the initialization
864 value instead of the constant entity, typically for scalars with an
865 address clause when the parent doesn't require an lvalue. */
868 /* If the Etype of this node does not equal the Etype of the Entity,
869 something is wrong with the entity map, probably in generic
870 instantiation. However, this does not apply to types. Since we sometime
871 have strange Ekind's, just do this test for objects. Also, if the Etype of
872 the Entity is private, the Etype of the N_Identifier is allowed to be the
873 full type and also we consider a packed array type to be the same as the
874 original type. Similarly, a class-wide type is equivalent to a subtype of
875 itself. Finally, if the types are Itypes, one may be a copy of the other,
876 which is also legal. */
899 /* If this is a reference to a deferred constant whose partial view is an
900 unconstrained private type, the proper type is on the full view of the
901 constant, not on the full view of the type, which may be unconstrained.
903 This may be a reference to a type, for example in the prefix of the
904 attribute Position, generated for dispatching code (see Make_DT in
905 exp_disp,adb). In that case we need the type itself, not is parent,
906 in particular if it is a derived type */
911 {
914 }
915 else
916 {
917 /* We want to use the Actual_Subtype if it has already been elaborated,
918 otherwise the Etype. Avoid using Actual_Subtype for packed arrays to
919 simplify things. */
927 else
929 }
931 /* Expand the type of this identifier first, in case it is an enumeral
932 literal, which only get made when the type is expanded. There is no
933 order-of-elaboration issue here. */
936 /* If this is a non-imported scalar constant with an address clause,
937 retrieve the value instead of a pointer to be dereferenced unless
938 an lvalue is required. This is generally more efficient and actually
939 required if this is a static expression because it might be used
940 in a context where a dereference is inappropriate, such as a case
941 statement alternative or a record discriminant. There is no possible
942 volatile-ness short-circuit here since Volatile constants must bei
943 imported per C.6. */
948 {
952 }
955 {
956 /* If this is a deferred constant, the initializer is attached to
957 the full view. */
962 }
963 else
966 /* If we are in an exception handler, force this variable into memory to
967 ensure optimization does not remove stores that appear redundant but are
968 actually needed in case an exception occurs.
970 ??? Note that we need not do this if the variable is declared within the
971 handler, only if it is referenced in the handler and declared in an
972 enclosing block, but we have no way of testing that right now.
974 ??? We used to essentially set the TREE_ADDRESSABLE flag on the variable
975 here, but it can now be removed by the Tree aliasing machinery if the
976 address of the variable is never taken. All we can do is to make the
977 variable volatile, which might incur the generation of temporaries just
978 to access the memory in some circumstances. This can be avoided for
979 variables of non-constant size because they are automatically allocated
980 to memory. There might be no way of allocating a proper temporary for
981 them in any case. We only do this for SJLJ though. */
987 /* Some objects (such as parameters passed by reference, globals of
988 variable size, and renamed objects) actually represent the address
989 of the object. In that case, we must do the dereference. Likewise,
990 deal with parameters to foreign convention subprograms. */
995 {
997 tree renamed_obj;
1001 gnu_result
1004 gnu_result));
1006 /* If it's a renaming pointer and we are at the right binding level,
1007 we can reference the renamed object directly, since the renamed
1008 expression has been protected against multiple evaluations. */
1015 /* Return the underlying CST for a CONST_DECL like a few lines below,
1016 after dereferencing in this case. */
1021 else
1026 }
1028 /* The GNAT tree has the type of a function as the type of its result. Also
1029 use the type of the result if the Etype is a subtype which is nominally
1030 unconstrained. But remove any padding from the resulting type. */
1033 {
1037 }
1039 /* If we have a constant declaration and its initializer, try to return the
1040 latter to avoid the need to call fold in lots of places and the need for
1041 elaboration code if this identifier is used as an initializer itself. */
1045 {
1051 /* If there is a (corresponding) variable or this is the address of a
1052 constant, we only want to return the initializer if an lvalue isn't
1053 required. Evaluate this now if we have not already done so. */
1055 require_lvalue
1059 /* ??? We need to unshare the initializer if the object is external
1060 as such objects are not marked for unsharing if we are not at the
1061 global level. This should be fixed in add_decl_expr. */
1064 }
1069 }
1070 \f
1071 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Pragma. Return
1072 any statements we generate. */
1074 static tree
1076 {
1077 Node_Id gnat_temp;
1080 /* Check for (and ignore) unrecognized pragma and do nothing if we are just
1081 annotating types. */
1087 {
1089 /* Do nothing at top level: all such variables are already viewable. */
1096 {
1102 #ifdef ASM_COMMENT_START
1104 #endif
1109 /* Use the value only if it fits into a normal register,
1110 otherwise use the address. */
1119 #ifdef ASM_COMMENT_START
1125 NULL);
1128 #endif
1130 asm_constraint,
1131 NULL_TREE,
1132 tree_cons
1140 }
1146 {
1159 }
1166 }
1169 }
1170 \f
1171 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Attribute node,
1172 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to
1173 where we should place the result type. ATTRIBUTE is the attribute ID. */
1175 static tree
1177 {
1183 /* If the input is a NULL_EXPR, make a new one. */
1185 {
1189 }
1192 {
1195 /* These are just conversions since representation clauses for
1196 enumeration types are handled in the front-end. */
1197 {
1203 }
1208 /* These just add or subtract the constant 1 since representation
1209 clauses for enumeration types are handled in the front-end. */
1214 {
1216 gnu_expr
1217 = emit_check
1219 gnu_expr,
1220 attribute == Attr_Pred
1224 }
1226 gnu_result
1234 /* Conversions don't change addresses but can cause us to miss the
1235 COMPONENT_REF case below, so strip them off. */
1239 /* If we are taking 'Address of an unconstrained object, this is the
1240 pointer to the underlying array. */
1244 /* If we are building a static dispatch table, we have to honor
1245 TARGET_VTABLE_USES_DESCRIPTORS if we want to be compatible
1246 with the C++ ABI. We do it in the non-static case as well,
1247 see gnat_to_gnu_entity, case E_Access_Subprogram_Type. */
1250 {
1252 /* Descriptors can only be built here for top-level functions. */
1258 /* If we're not going to build the descriptor, we have to retrieve
1259 the one which will be built by the linker (or by the compiler
1260 later if a static chain is requested). */
1262 {
1265 gnu_result);
1267 }
1272 {
1274 {
1278 }
1279 else
1284 }
1288 }
1290 /* ... fall through ... */
1296 gnu_result
1303 /* For 'Code_Address, find an inner ADDR_EXPR and mark it so that we
1304 don't try to build a trampoline. */
1306 {
1314 }
1316 /* For other address attributes applied to a nested function,
1317 find an inner ADDR_EXPR and annotate it so that we can issue
1318 a useful warning with -Wtrampolines. */
1320 {
1324 ;
1328 {
1331 /* Check that we're not violating the No_Implicit_Dynamic_Code
1332 restriction. Be conservative if we don't know anything
1333 about the trampoline strategy for the target. */
1335 }
1336 }
1340 {
1341 tree gnu_obj_type;
1346 /* If this is an unconstrained array, we know the object has been
1347 allocated with the template in front of the object. So compute
1348 the template address. */
1350 gnu_ptr
1352 (TYPE_OBJECT_RECORD_TYPE
1354 gnu_ptr);
1359 {
1360 tree gnu_char_ptr_type
1366 }
1369 }
1378 /* Remove NOPs and conversions between original and packable version
1379 from GNU_EXPR, and conversions from GNU_PREFIX. We use GNU_EXPR
1380 to see if a COMPONENT_REF was involved. */
1385 == RECORD_TYPE
1394 /* Replace an unconstrained array type with the type of the underlying
1395 array. We can't do this with a call to maybe_unconstrained_array
1396 since we may have a TYPE_DECL. For 'Max_Size_In_Storage_Elements,
1397 use the record type that will be used to allocate the object and its
1398 template. */
1400 {
1404 }
1406 /* If we're looking for the size of a field, return the field size.
1407 Otherwise, if the prefix is an object, or if we're looking for
1408 'Object_Size or 'Max_Size_In_Storage_Elements, the result is the
1409 GCC size of the type. Otherwise, it is the RM size of the type. */
1415 {
1416 /* If the prefix is an object of a padded type, the GCC size isn't
1417 relevant to the programmer. Normally what we want is the RM size,
1418 which was set from the specified size, but if it was not set, we
1419 want the size of the field. Using the MAX of those two produces
1420 the right result in all cases. Don't use the size of the field
1421 if it's self-referential, since that's never what's wanted. */
1425 {
1429 gnu_result
1432 }
1434 {
1436 Node_Id gnat_actual_subtype
1438 tree gnu_ptr_type
1443 {
1444 tree gnu_actual_obj_type
1446 gnu_type
1448 gnu_actual_obj_type,
1450 }
1453 }
1454 else
1456 }
1457 else
1460 /* Deal with a self-referential size by returning the maximum size for
1461 a type and by qualifying the size with the object otherwise. */
1463 {
1466 else
1468 }
1470 /* If the type contains a template, subtract its size. */
1476 /* For 'Max_Size_In_Storage_Elements, adjust the unit. */
1484 {
1497 else
1498 {
1504 /* If the default alignment of "double" or larger scalar types is
1505 specifically capped and there is an alignment clause neither
1506 on the type nor on the prefix itself, return the cap. */
1508 is_capped_double
1511 is_capped_double
1513 else
1523 else
1525 }
1528 }
1537 {
1544 else
1545 gnu_result
1546 = build_binary_op
1548 build_binary_op
1560 }
1562 /* ... fall through ... */
1565 {
1572 /* Make sure any implicit dereference gets done. */
1575 /* We treat unconstrained array In parameters specially. */
1585 {
1587 tree gnu_type_temp;
1593 ;
1596 }
1603 /* When not optimizing, look up the slot associated with the parameter
1604 and the dimension in the cache and create a new one on failure. */
1606 {
1612 {
1617 }
1618 }
1620 /* Return the cached expression or build a new one. */
1622 {
1624 {
1627 }
1629 gnu_result
1631 }
1634 {
1636 {
1639 }
1641 gnu_result
1643 }
1646 {
1648 {
1651 }
1652 else
1653 {
1654 /* We used to compute the length as max (hb - lb + 1, 0),
1655 which could overflow for some cases of empty arrays, e.g.
1656 when lb == index_type'first. We now compute the length as
1657 (hb >= lb) ? hb - lb + 1 : 0, which would only overflow in
1658 much rarer cases, for extremely large arrays we expect
1659 never to encounter in practice. In addition, the former
1660 computation required the use of potentially constraining
1661 signed arithmetic while the latter doesn't. Note that
1662 the comparison must be done in the original index type,
1663 to avoid any overflow during the conversion. */
1668 gnu_result
1671 comp_type,
1675 gnu_result
1678 boolean_type_node,
1680 gnu_result,
1682 }
1683 }
1685 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
1686 handling. Note that these attributes could not have been used on
1687 an unconstrained array type. */
1690 /* Cache the expression we have just computed. Since we want to do it
1691 at runtime, we force the use of a SAVE_EXPR and let the gimplifier
1692 create the temporary. */
1694 {
1695 gnu_result
1702 else
1704 }
1706 /* Set the source location onto the predicate of the condition in the
1707 'Length case but do not do it if the expression is cached to avoid
1708 messing up the debug info. */
1713 gnat_node);
1716 }
1723 {
1724 HOST_WIDE_INT bitsize;
1725 HOST_WIDE_INT bitpos;
1726 tree gnu_offset;
1727 tree gnu_field_bitpos;
1728 tree gnu_field_offset;
1729 tree gnu_inner;
1737 /* We can have 'Bit on any object, but if it isn't a COMPONENT_REF,
1738 the result is 0. Don't allow 'Bit on a bare component, though. */
1742 {
1745 }
1747 else
1756 {
1764 {
1765 gnu_field_bitpos
1768 gnu_field_offset
1771 }
1772 }
1774 {
1777 }
1778 else
1779 {
1782 }
1785 {
1800 bitsize_one_node);
1806 }
1808 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
1809 handling. */
1812 }
1816 {
1824 }
1850 /* Note this size cannot be self-referential. */
1857 /* This is just a zero cast to the pointer type for our prefix and
1858 dereferenced. */
1860 gnu_result
1863 integer_zero_node));
1868 {
1875 {
1880 ;
1881 }
1889 && (DECL_BY_COMPONENT_PTR_P
1893 }
1897 /* Say we have an unimplemented attribute. Then set the value to be
1898 returned to be a zero and hope that's something we can convert to
1899 the type of this attribute. */
1904 }
1906 /* If this is an attribute where the prefix was unused, force a use of it if
1907 it has a side-effect. But don't do it if the prefix is just an entity
1908 name. However, if an access check is needed, we must do it. See second
1909 example in AARM 11.6(5.e). */
1917 }
1918 \f
1919 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Case_Statement,
1920 to a GCC tree, which is returned. */
1922 static tree
1924 {
1925 tree gnu_result;
1926 tree gnu_expr;
1927 Node_Id gnat_when;
1932 /* The range of values in a case statement is determined by the rules in
1933 RM 5.4(7-9). In almost all cases, this range is represented by the Etype
1934 of the expression. One exception arises in the case of a simple name that
1935 is parenthesized. This still has the Etype of the name, but since it is
1936 not a name, para 7 does not apply, and we need to go to the base type.
1937 This is the only case where parenthesization affects the dynamic
1938 semantics (i.e. the range of possible values at runtime that is covered
1939 by the others alternative.
1941 Another exception is if the subtype of the expression is non-static. In
1942 that case, we also have to use the base type. */
1948 /* We build a SWITCH_EXPR that contains the code with interspersed
1949 CASE_LABEL_EXPRs for each label. */
1957 {
1959 Node_Id gnat_choice;
1961 /* First compile all the different case choices for the current WHEN
1962 alternative. */
1965 {
1969 {
1984 /* This represents either a subtype range or a static value of
1985 some kind; Ekind says which. */
1987 {
1993 }
1995 /* ... fall through ... */
2007 }
2009 /* If the case value is a subtype that raises Constraint_Error at
2010 run-time because of a wrong bound, then gnu_low or gnu_high is
2011 not translated into an INTEGER_CST. In such a case, we need
2012 to ensure that the when statement is not added in the tree,
2013 otherwise it will crash the gimplifier. */
2016 {
2021 gnat_choice);
2023 }
2024 }
2026 /* Push a binding level here in case variables are declared as we want
2027 them to be local to this set of statements instead of to the block
2028 containing the Case statement. */
2030 {
2034 }
2035 }
2037 /* Now emit a definition of the label all the cases branched to. */
2045 }
2046 \f
2047 /* Return true if VAL (of type TYPE) can equal the minimum value if MAX is
2048 false, or the maximum value if MAX is true, of TYPE. */
2050 static bool
2052 {
2059 val = (max
2067 }
2069 /* Return true if VAL (of type TYPE) can equal the minimum value of TYPE.
2070 If REVERSE is true, minimum value is taken as maximum value. */
2074 {
2076 }
2078 /* Return true if VAL (of type TYPE) can equal the maximum value of TYPE.
2079 If REVERSE is true, maximum value is taken as minimum value. */
2083 {
2085 }
2087 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Loop_Statement,
2088 to a GCC tree, which is returned. */
2090 static tree
2092 {
2098 tree gnu_result;
2100 /* Set location information for statement and end label. */
2106 /* Save the end label of this LOOP_STMT in a stack so that a corresponding
2107 N_Exit_Statement can find it. */
2110 /* Set the condition under which the loop must keep going.
2111 For the case "LOOP .... END LOOP;" the condition is always true. */
2113 ;
2115 /* For the case "WHILE condition LOOP ..... END LOOP;" it's immediate. */
2120 /* Otherwise we have an iteration scheme and the condition is given by the
2121 bounds of the subtype of the iteration variable. */
2122 else
2123 {
2136 /* We must disable modulo reduction for the iteration variable, if any,
2137 in order for the loop comparison to be effective. */
2139 {
2145 }
2146 else
2147 {
2153 }
2155 /* We use two different strategies to translate the loop, depending on
2156 whether optimization is enabled.
2158 If it is, we try to generate the canonical form of loop expected by
2159 the loop optimizer, which is the do-while form:
2161 ENTRY_COND
2162 loop:
2163 TOP_UPDATE
2164 BODY
2165 BOTTOM_COND
2166 GOTO loop
2168 This makes it possible to bypass loop header copying and to turn the
2169 BOTTOM_COND into an inequality test. This should catch (almost) all
2170 loops with constant starting point. If we cannot, we try to generate
2171 the default form, which is:
2173 loop:
2174 TOP_COND
2175 BODY
2176 BOTTOM_UPDATE
2177 GOTO loop
2179 It will be rotated during loop header copying and an entry test added
2180 to yield the do-while form. This should catch (almost) all loops with
2181 constant ending point. If we cannot, we generate the fallback form:
2183 ENTRY_COND
2184 loop:
2185 BODY
2186 BOTTOM_COND
2187 BOTTOM_UPDATE
2188 GOTO loop
2190 which works in all cases but for which loop header copying will copy
2191 the BOTTOM_COND, thus adding a third conditional branch.
2193 If optimization is disabled, loop header copying doesn't come into
2194 play and we try to generate the loop forms with the less conditional
2195 branches directly. First, the default form, it should catch (almost)
2196 all loops with constant ending point. Then, if we cannot, we try to
2197 generate the shifted form:
2199 loop:
2200 TOP_COND
2201 TOP_UPDATE
2202 BODY
2203 GOTO loop
2205 which should catch loops with constant starting point. Otherwise, if
2206 we cannot, we generate the fallback form. */
2209 {
2210 /* We can use the do-while form if GNU_FIRST-1 doesn't overflow. */
2212 {
2217 }
2219 /* Otherwise, we can use the default form if GNU_LAST+1 doesn't. */
2221 ;
2223 /* Otherwise, use the fallback form. */
2224 else
2226 }
2227 else
2228 {
2229 /* We can use the default form if GNU_LAST+1 doesn't overflow. */
2231 ;
2233 /* Otherwise, we can use the shifted form if neither GNU_FIRST-1 nor
2234 GNU_LAST-1 does. */
2237 {
2243 }
2245 /* Otherwise, use the fallback form. */
2246 else
2248 }
2253 /* If we use the BOTTOM_COND, we can turn the test into an inequality
2254 test but we have to add an ENTRY_COND to protect the empty loop. */
2256 {
2258 gnu_cond_expr
2264 }
2266 /* Open a new nesting level that will surround the loop to declare the
2267 iteration variable. */
2271 /* Declare the iteration variable and set it to its initial value. */
2276 /* Do all the arithmetics in the base type. */
2279 /* Set either the top or bottom exit condition. */
2282 gnu_last);
2284 /* Set either the top or bottom update statement and give it the source
2285 location of the iteration for better coverage info. */
2291 gnat_iter_scheme);
2292 }
2294 /* If the loop was named, have the name point to this loop. In this case,
2295 the association is not a DECL node, but the end label of the loop. */
2299 /* Make the loop body into its own block, so any allocated storage will be
2300 released every iteration. This is needed for stack allocation. */
2305 /* If we declared a variable, then we are in a statement group for that
2306 declaration. Add the LOOP_STMT to it and make that the "loop". */
2308 {
2312 }
2314 /* If we have an outer COND_EXPR, that's our result and this loop is its
2315 "true" statement. Otherwise, the result is the LOOP_STMT. */
2317 {
2321 }
2322 else
2328 }
2329 \f
2330 /* Emit statements to establish __gnat_handle_vms_condition as a VMS condition
2331 handler for the current function. */
2333 /* This is implemented by issuing a call to the appropriate VMS specific
2334 builtin. To avoid having VMS specific sections in the global gigi decls
2335 array, we maintain the decls of interest here. We can't declare them
2336 inside the function because we must mark them never to be GC'd, which we
2337 can only do at the global level. */
2342 static void
2344 {
2345 tree establish_stmt;
2347 /* Elaborate the required decls on the first call. Check on the decl for
2348 the gnat condition handler to decide, as this is one we create so we are
2349 sure that it will be non null on subsequent calls. The builtin decl is
2350 looked up so remains null on targets where it is not implemented yet. */
2352 {
2353 vms_builtin_establish_handler_decl
2354 = builtin_decl_for
2357 gnat_vms_condition_handler_decl
2359 NULL_TREE,
2361 ptr_void_type_node,
2362 ptr_void_type_node,
2363 NULL_TREE),
2366 /* ??? DECL_CONTEXT shouldn't have been set because of DECL_EXTERNAL. */
2368 }
2370 /* Do nothing if the establish builtin is not available, which might happen
2371 on targets where the facility is not implemented. */
2375 establish_stmt
2377 build_unary_op
2379 gnat_vms_condition_handler_decl));
2382 }
2383 \f
2384 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Subprogram_Body. We
2385 don't return anything. */
2387 static void
2389 {
2390 /* Defining identifier of a parameter to the subprogram. */
2391 Entity_Id gnat_param;
2392 /* The defining identifier for the subprogram body. Note that if a
2393 specification has appeared before for this body, then the identifier
2394 occurring in that specification will also be a defining identifier and all
2395 the calls to this subprogram will point to that specification. */
2396 Entity_Id gnat_subprog_id
2399 /* The FUNCTION_DECL node corresponding to the subprogram spec. */
2400 tree gnu_subprog_decl;
2401 /* Its RESULT_DECL node. */
2402 tree gnu_result_decl;
2403 /* The FUNCTION_TYPE node corresponding to the subprogram spec. */
2404 tree gnu_subprog_type;
2405 tree gnu_cico_list;
2406 tree gnu_result;
2409 /* If this is a generic object or if it has been eliminated,
2410 ignore it. */
2416 /* If this subprogram acts as its own spec, define it. Otherwise, just get
2417 the already-elaborated tree node. However, if this subprogram had its
2418 elaboration deferred, we will already have made a tree node for it. So
2419 treat it as not being defined in that case. Such a subprogram cannot
2420 have an address clause or a freeze node, so this test is safe, though it
2421 does disable some otherwise-useful error checking. */
2422 gnu_subprog_decl
2429 /* If the function returns by invisible reference, make it explicit in the
2430 function body. See gnat_to_gnu_entity, E_Subprogram_Type case. */
2432 {
2436 }
2438 /* Propagate the debug mode. */
2442 /* Set the line number in the decl to correspond to that of the body so that
2443 the line number notes are written correctly. */
2446 /* Initialize the information structure for the function. */
2454 /* If there are Out parameters, we need to ensure that the return statement
2455 properly copies them out. We do this by making a new block and converting
2456 any inner return into a goto to a label at the end of the block. */
2462 /* Get a tree corresponding to the code for the subprogram. */
2466 /* See if there are any parameters for which we don't yet have GCC entities.
2467 These must be for Out parameters for which we will be making VAR_DECL
2468 nodes here. Fill them in to TYPE_CI_CO_LIST, which must contain the empty
2469 entry as well. We can match up the entries because TYPE_CI_CO_LIST is in
2470 the order of the parameters. */
2475 {
2476 /* Skip any entries that have been already filled in; they must
2477 correspond to In Out parameters. */
2480 ;
2482 /* Do any needed references for padded types. */
2486 }
2488 /* On VMS, establish our condition handler to possibly turn a condition into
2489 the corresponding exception if the subprogram has a foreign convention or
2490 is exported.
2492 To ensure proper execution of local finalizations on condition instances,
2493 we must turn a condition into the corresponding exception even if there
2494 is no applicable Ada handler, and need at least one condition handler per
2495 possible call chain involving GNAT code. OTOH, establishing the handler
2496 has a cost so we want to minimize the number of subprograms into which
2497 this happens. The foreign or exported condition is expected to satisfy
2498 all the constraints. */
2506 /* Generate the code of the subprogram itself. A return statement will be
2507 present and any Out parameters will be handled there. */
2512 /* If we populated the parameter attributes cache, we need to make sure
2513 that the cached expressions are evaluated on all possible paths. */
2516 {
2523 {
2530 }
2534 }
2536 /* If we are dealing with a return from an Ada procedure with parameters
2537 passed by copy-in/copy-out, we need to return a record containing the
2538 final values of these parameters. If the list contains only one entry,
2539 return just that entry though.
2541 For a full description of the copy-in/copy-out parameter mechanism, see
2542 the part of the gnat_to_gnu_entity routine dealing with the translation
2543 of subprograms.
2545 We need to make a block that contains the definition of that label and
2546 the copying of the return value. It first contains the function, then
2547 the label and copy statement. */
2549 {
2550 tree gnu_retval;
2561 else
2563 gnu_cico_list);
2569 }
2573 /* Set the end location. */
2574 Sloc_to_locus
2582 /* Finally annotate the parameters and disconnect the trees for parameters
2583 that we have turned into variables since they are now unusable. */
2587 {
2593 }
2599 }
2600 \f
2601 /* Subroutine of gnat_to_gnu to translate gnat_node, either an N_Function_Call
2602 or an N_Procedure_Call_Statement, to a GCC tree, which is returned.
2603 GNU_RESULT_TYPE_P is a pointer to where we should place the result type.
2604 If GNU_TARGET is non-null, this must be a function call on the RHS of a
2605 N_Assignment_Statement and the result is to be placed into that object. */
2607 static tree
2609 {
2610 /* The GCC node corresponding to the GNAT subprogram name. This can either
2611 be a FUNCTION_DECL node if we are dealing with a standard subprogram call,
2612 or an indirect reference expression (an INDIRECT_REF node) pointing to a
2613 subprogram. */
2615 /* The FUNCTION_TYPE node giving the GCC type of the subprogram. */
2618 Entity_Id gnat_formal;
2619 Node_Id gnat_actual;
2624 tree gnu_call;
2629 /* If we are calling a stubbed function, raise Program_Error, but Elaborate
2630 all our args first. */
2632 {
2642 {
2645 }
2648 }
2650 /* The only way we can be making a call via an access type is if Name is an
2651 explicit dereference. In that case, get the list of formal args from the
2652 type the access type is pointing to. Otherwise, get the formals from the
2653 entity being called. */
2657 /* Assume here that this must be 'Elab_Body or 'Elab_Spec. */
2659 else
2662 /* If we are translating a statement, open a new nesting level that will
2663 surround it to declare the temporaries created for the call. */
2665 {
2668 }
2670 /* The lifetime of the temporaries created for the call ends with the call
2671 so we can give them the scope of the elaboration routine at top level. */
2673 {
2676 }
2678 /* Create the list of the actual parameters as GCC expects it, namely a
2679 chain of TREE_LIST nodes in which the TREE_VALUE field of each node
2680 is an expression and the TREE_PURPOSE field is null. But skip Out
2681 parameters not passed by reference and that need not be copied in. */
2686 {
2690 /* In the Out or In Out case, we must suppress conversions that yield
2691 an lvalue but can nevertheless cause the creation of a temporary,
2692 because we need the real object in this case, either to pass its
2693 address if it's passed by reference or as target of the back copy
2694 done after the call if it uses the copy-in copy-out mechanism.
2695 We do it in the In case too, except for an unchecked conversion
2696 because it alone can cause the actual to be misaligned and the
2697 addressability test is applied to the real object. */
2698 bool suppress_type_conversion
2703 Node_Id gnat_name = suppress_type_conversion
2706 tree gnu_actual;
2708 /* If it's possible we may need to use this expression twice, make sure
2709 that any side-effects are handled via SAVE_EXPRs; likewise if we need
2710 to force side-effects before the call.
2711 ??? This is more conservative than we need since we don't need to do
2712 this for pass-by-ref with no conversion. */
2716 /* If we are passing a non-addressable parameter by reference, pass the
2717 address of a copy. In the Out or In Out case, set up to copy back
2718 out after the call. */
2726 {
2729 /* Do not issue warnings for CONSTRUCTORs since this is not a copy
2730 but sort of an instantiation for them. */
2732 ;
2734 /* If the type is passed by reference, a copy is not allowed. */
2737 gnat_actual);
2739 /* For users of Starlet we issue a warning because the interface
2740 apparently assumes that by-ref parameters outlive the procedure
2741 invocation. The code still will not work as intended, but we
2742 cannot do much better since low-level parts of the back-end
2743 would allocate temporaries at will because of the misalignment
2744 if we did not do so here. */
2746 {
2747 post_error
2749 post_error_ne
2753 gnat_formal);
2754 }
2756 /* If the actual type of the object is already the nominal type,
2757 we have nothing to do, except if the size is self-referential
2758 in which case we'll remove the unpadding below. */
2761 ;
2763 /* Otherwise remove the unpadding from all the objects. */
2765 && TYPE_IS_PADDING_P
2769 /* Otherwise convert to the nominal type of the object if needed.
2770 There are several cases in which we need to make the temporary
2771 using this type instead of the actual type of the object when
2772 they are distinct, because the expectations of the callee would
2773 otherwise not be met:
2774 - if it's a justified modular type,
2775 - if the actual type is a smaller form of it,
2776 - if it's a smaller form of the actual type. */
2780 gnu_name_type)))
2786 /* Create an explicit temporary holding the copy. This ensures that
2787 its lifetime is as narrow as possible around a statement. */
2794 /* But initialize it on the fly like for an implicit temporary as
2795 we aren't necessarily dealing with a statement. */
2796 gnu_stmt
2800 /* From now on, the real object is the temporary. */
2802 gnu_temp);
2804 /* Set up to move the copy back to the original if needed. */
2806 {
2808 gnu_temp);
2811 }
2812 }
2814 /* Start from the real object and build the actual. */
2817 /* If this was a procedure call, we may not have removed any padding.
2818 So do it here for the part we will use as an input, if any. */
2821 gnu_actual
2824 /* Put back the conversion we suppressed above in the computation of the
2825 real object. And even if we didn't suppress any conversion there, we
2826 may have suppressed a conversion to the Etype of the actual earlier,
2827 since the parent is a procedure call, so put it back here. */
2830 gnu_actual
2833 else
2834 gnu_actual
2837 /* Make sure that the actual is in range of the formal's type. */
2840 gnu_actual
2843 /* Unless this is an In parameter, we must remove any justified modular
2844 building from GNU_NAME to get an lvalue. */
2849 gnu_name
2852 /* If we have not saved a GCC object for the formal, it means it is an
2853 Out parameter not passed by reference and that need not be copied in.
2854 Otherwise, first see if the parameter is passed by reference. */
2858 {
2860 {
2861 /* In Out or Out parameters passed by reference don't use the
2862 copy-in copy-out mechanism so the address of the real object
2863 must be passed to the function. */
2866 /* If we have a padded type, be sure we've removed padding. */
2869 gnu_actual);
2871 /* If we have the constructed subtype of an aliased object
2872 with an unconstrained nominal subtype, the type of the
2873 actual includes the template, although it is formally
2874 constrained. So we need to convert it back to the real
2875 constructed subtype to retrieve the constrained part
2876 and takes its address. */
2882 gnu_actual);
2883 }
2885 /* There is no need to convert the actual to the formal's type before
2886 taking its address. The only exception is for unconstrained array
2887 types because of the way we build fat pointers. */
2891 /* The symmetry of the paths to the type of an entity is broken here
2892 since arguments don't know that they will be passed by ref. */
2895 }
2899 {
2905 {
2908 }
2910 /* Take the address of the object and convert to the proper pointer
2911 type. We'd like to actually compute the address of the beginning
2912 of the array using an ADDR_EXPR of an ARRAY_REF, but there's a
2913 possibility that the ARRAY_REF might return a constant and we'd be
2914 getting the wrong address. Neither approach is exactly correct,
2915 but this is the most likely to work in all cases. */
2917 }
2921 {
2924 /* If this is 'Null_Parameter, pass a zero descriptor. */
2928 gnu_actual
2930 else
2933 gnat_formal,
2934 gnat_actual));
2935 }
2936 else
2937 {
2938 tree gnu_size;
2944 {
2945 /* Make sure side-effects are evaluated before the call. */
2949 }
2953 /* If this is 'Null_Parameter, pass a zero even though we are
2954 dereferencing it. */
2960 gnu_actual
2964 integer_zero_node),
2966 else
2968 }
2971 }
2977 /* If it's a function call, the result is the call expression unless a target
2978 is specified, in which case we copy the result into the target and return
2979 the assignment statement. */
2981 {
2984 /* If the function returns an unconstrained array or by direct reference,
2985 we have to dereference the pointer. */
2991 {
2995 /* If range check is needed, emit code to generate it. */
2997 gnu_result
2999 gnat_parent);
3001 /* ??? If the return type has non-constant size, then force the
3002 return slot optimization as we would not be able to generate
3003 a temporary. That's what has been done historically. */
3006 else
3009 gnu_result
3014 }
3015 else
3016 {
3020 }
3023 }
3025 /* If this is the case where the GNAT tree contains a procedure call but the
3026 Ada procedure has copy-in/copy-out parameters, then the special parameter
3027 passing mechanism must be used. */
3029 {
3030 /* List of FIELD_DECLs associated with the PARM_DECLs of the copy-in/
3031 copy-out parameters. */
3036 {
3039 /* The call sequence must contain one and only one call, even though
3040 the function is pure. Save the result into a temporary. */
3047 gnu_stmt
3051 /* Add the call statement to the list and start from its result. */
3056 }
3060 else
3067 /* If we are dealing with a copy in copy out parameter, we must
3068 retrieve its value from the record returned in the call. */
3074 || (DECL_BY_DESCRIPTOR_P
3077 {
3078 /* Get the value to assign to this Out or In Out parameter. It is
3079 either the result of the function if there is only a single such
3080 parameter or the appropriate field from the record returned. */
3081 tree gnu_result
3083 ? gnu_call
3087 /* If the actual is a conversion, get the inner expression, which
3088 will be the real destination, and convert the result to the
3089 type of the actual parameter. */
3090 tree gnu_actual
3093 /* If the result is a padded type, remove the padding. */
3095 gnu_result
3097 gnu_result);
3099 /* If the actual is a type conversion, the real target object is
3100 denoted by the inner Expression and we need to convert the
3101 result to the associated type.
3102 We also need to convert our gnu assignment target to this type
3103 if the corresponding GNU_NAME was constructed from the GNAT
3104 conversion node and not from the inner Expression. */
3106 {
3107 gnu_result
3108 = convert_with_check
3116 }
3118 /* Unchecked conversions as actuals for Out parameters are not
3119 allowed in user code because they are not variables, but do
3120 occur in front-end expansions. The associated GNU_NAME is
3121 always obtained from the inner expression in such cases. */
3124 gnu_result,
3126 else
3127 {
3129 gnu_result
3131 gnat_actual);
3136 }
3144 }
3145 }
3146 else
3154 }
3155 \f
3156 /* Subroutine of gnat_to_gnu to translate gnat_node, an
3157 N_Handled_Sequence_Of_Statements, to a GCC tree, which is returned. */
3159 static tree
3161 {
3164 /* If just annotating, ignore all EH and cleanups. */
3168 bool setjmp_longjmp
3174 tree gnu_result;
3175 tree gnu_expr;
3176 Node_Id gnat_temp;
3178 /* The GCC exception handling mechanism can handle both ZCX and SJLJ schemes
3179 and we have our own SJLJ mechanism. To call the GCC mechanism, we call
3180 add_cleanup, and when we leave the binding, end_stmt_group will create
3181 the TRY_FINALLY_EXPR.
3183 ??? The region level calls down there have been specifically put in place
3184 for a ZCX context and currently the order in which things are emitted
3185 (region/handlers) is different from the SJLJ case. Instead of putting
3186 other calls with different conditions at other places for the SJLJ case,
3187 it seems cleaner to reorder things for the SJLJ case and generalize the
3188 condition to make it not ZCX specific.
3190 If there are any exceptions or cleanup processing involved, we need an
3191 outer statement group (for Setjmp_Longjmp) and binding level. */
3193 {
3196 }
3198 /* If using setjmp_longjmp, make the variables for the setjmp buffer and save
3199 area for address of previous buffer. Do this first since we need to have
3200 the setjmp buf known for any decls in this block. */
3202 {
3207 gnat_node);
3210 /* The __builtin_setjmp receivers will immediately reinstall it. Now
3211 because of the unstructured form of EH used by setjmp_longjmp, there
3212 might be forward edges going to __builtin_setjmp receivers on which
3213 it is uninitialized, although they will never be actually taken. */
3223 /* When we exit this block, restore the saved value. */
3226 }
3228 /* If we are to call a function when exiting this block, add a cleanup
3229 to the binding level we made above. Note that add_cleanup is FIFO
3230 so we must register this cleanup after the EH cleanup just above. */
3235 /* Now build the tree for the declarations and statements inside this block.
3236 If this is SJLJ, set our jmp_buf as the current buffer. */
3242 gnu_jmpbuf_decl)));
3248 /* Generate code for each statement in the block. */
3256 /* Now generate code for the two exception models, if either is relevant for
3257 this block. */
3259 {
3261 tree gnu_handler;
3263 /* Make a binding level for the exception handling declarations and code
3264 and set up gnu_except_ptr_stack for the handlers to use. */
3270 NULL_TREE,
3275 /* Generate code for each handler. The N_Exception_Handler case does the
3276 real work and returns a COND_EXPR for each handler, which we chain
3277 together here. */
3280 {
3283 /* If this is the first one, set it as the outer one. Otherwise,
3284 point the "else" part of the previous handler to us. Then point
3285 to our "else" part. */
3288 else
3292 }
3294 /* If none of the exception handlers did anything, re-raise but do not
3295 defer abortion. */
3298 set_expr_location_from_node
3304 else
3307 /* End the binding level dedicated to the exception handlers and get the
3308 whole statement group. */
3313 /* If the setjmp returns 1, we restore our incoming longjmp value and
3314 then check the handlers. */
3317 gnu_jmpsave_decl),
3318 gnat_node);
3322 /* This block is now "if (setjmp) ... <handlers> else <block>". */
3324 (build_call_1_expr
3327 gnu_jmpbuf_decl))),
3329 }
3331 {
3332 tree gnu_handlers;
3334 /* First make a block containing the handlers. */
3342 /* Now make the TRY_CATCH_EXPR for the block. */
3345 }
3346 else
3349 /* Now close our outer block, if we had to make one. */
3351 {
3355 }
3358 }
3359 \f
3360 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
3361 to a GCC tree, which is returned. This is the variant for Setjmp_Longjmp
3362 exception handling. */
3364 static tree
3366 {
3367 /* Unless this is "Others" or the special "Non-Ada" exception for Ada, make
3368 an "if" statement to select the proper exceptions. For "Others", exclude
3369 exceptions where Handled_By_Others is nonzero unless the All_Others flag
3370 is set. For "Non-ada", accept an exception if "Lang" is 'V'. */
3373 Node_Id gnat_temp;
3377 {
3378 tree this_choice;
3381 {
3384 else
3385 this_choice
3386 = build_binary_op
3388 convert
3390 build_component_ref
3391 (build_unary_op
3396 integer_zero_node);
3397 }
3401 {
3403 tree gnu_expr;
3405 /* Exception may be a renaming. Recover original exception which is
3406 the one elaborated and registered. */
3412 this_choice
3413 = build_binary_op
3418 /* If this is the distinguished exception "Non_Ada_Error" (and we are
3419 in VMS mode), also allow a non-Ada exception (a VMS condition) t
3420 match. */
3422 {
3423 tree gnu_comp
3424 = build_component_ref
3429 this_choice
3430 = build_binary_op
3434 this_choice);
3435 }
3436 }
3437 else
3442 }
3445 }
3446 \f
3447 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
3448 to a GCC tree, which is returned. This is the variant for ZCX. */
3450 static tree
3452 {
3454 tree gnu_expr;
3455 tree gnu_etype;
3456 tree gnu_current_exc_ptr;
3457 tree gnu_incoming_exc_ptr;
3458 Node_Id gnat_temp;
3460 /* We build a TREE_LIST of nodes representing what exception types this
3461 handler can catch, with special cases for others and all others cases.
3463 Each exception type is actually identified by a pointer to the exception
3464 id, or to a dummy object for "others" and "all others". */
3467 {
3469 {
3470 tree gnu_expr
3473 gnu_etype
3475 }
3478 {
3481 /* Exception may be a renaming. Recover original exception which is
3482 the one elaborated and registered. */
3489 /* The Non_Ada_Error case for VMS exceptions is handled
3490 by the personality routine. */
3491 }
3492 else
3495 /* The GCC interface expects NULL to be passed for catch all handlers, so
3496 it would be quite tempting to set gnu_etypes_list to NULL if gnu_etype
3497 is integer_zero_node. It would not work, however, because GCC's
3498 notion of "catch all" is stronger than our notion of "others". Until
3499 we correctly use the cleanup interface as well, doing that would
3500 prevent the "all others" handlers from being seen, because nothing
3501 can be caught beyond a catch all from GCC's point of view. */
3503 }
3508 /* Expand a call to the begin_handler hook at the beginning of the handler,
3509 and arrange for a call to the end_handler hook to occur on every possible
3510 exit path.
3512 The hooks expect a pointer to the low level occurrence. This is required
3513 for our stack management scheme because a raise inside the handler pushes
3514 a new occurrence on top of the stack, which means that this top does not
3515 necessarily match the occurrence this handler was dealing with.
3517 __builtin_eh_pointer references the exception occurrence being
3518 propagated. Upon handler entry, this is the exception for which the
3519 handler is triggered. This might not be the case upon handler exit,
3520 however, as we might have a new occurrence propagated by the handler's
3521 body, and the end_handler hook called as a cleanup in this context.
3523 We use a local variable to retrieve the incoming value at handler entry
3524 time, and reuse it to feed the end_handler hook's argument at exit. */
3526 gnu_current_exc_ptr
3532 gnat_node);
3535 gnu_incoming_exc_ptr),
3536 gnat_node);
3537 /* ??? We don't seem to have an End_Label at hand to set the location. */
3539 Empty);
3545 }
3546 \f
3547 /* Subroutine of gnat_to_gnu to generate code for an N_Compilation unit. */
3549 static void
3551 {
3556 /* Make the decl for the elaboration procedure. */
3557 tree gnu_elab_proc_decl
3558 = create_subprog_decl
3566 /* Initialize the information structure for the function. */
3575 /* For a body, first process the spec if there is one. */
3579 {
3582 }
3584 /* If we can inline, generate code for all the inlined subprograms. */
3586 {
3587 Entity_Id gnat_entity;
3592 {
3596 {
3597 /* ??? This really should always be present. */
3600 gnat_body
3602 }
3605 {
3606 /* Define the entity first so we set DECL_EXTERNAL. */
3609 }
3610 }
3611 }
3614 {
3621 }
3627 /* Process any pragmas and actions following the unit. */
3632 /* Save away what we've made so far and record this potential elaboration
3633 procedure. */
3639 Sloc_to_locus
3648 /* Generate elaboration code for this unit, if necessary, and say whether
3649 we did or not. */
3652 /* Invalidate the global renaming pointers. This is necessary because
3653 stabilization of the renamed entities may create SAVE_EXPRs which
3654 have been tied to a specific elaboration routine just above. */
3656 }
3657 \f
3658 /* Return true if GNAT_NODE, an unchecked type conversion, is a no-op as far
3659 as gigi is concerned. This is used to avoid conversions on the LHS. */
3661 static bool
3663 {
3666 /* The conversion must be on the LHS of an assignment or an actual parameter
3667 of a call. Otherwise, even if the conversion was essentially a no-op, it
3668 could de facto ensure type consistency and this should be preserved. */
3678 /* We're interested in artificial conversions generated by the front-end
3679 to make private types explicit, e.g. in Expand_Assign_Array. */
3686 /* The direct conversion to the underlying type is a no-op. */
3690 /* For an array subtype, the conversion to the PAT is a no-op. */
3695 /* For a record subtype, the conversion to the type is a no-op. */
3701 }
3703 /* This function is the driver of the GNAT to GCC tree transformation process.
3704 It is the entry point of the tree transformer. GNAT_NODE is the root of
3705 some GNAT tree. Return the root of the corresponding GCC tree. If this
3706 is an expression, return the GCC equivalent of the expression. If this
3707 is a statement, return the statement or add it to the current statement
3708 group, in which case anything returned is to be interpreted as occurring
3709 after anything added. */
3711 tree
3713 {
3719 Node_Id gnat_temp;
3721 /* Save node number for error message and set location information. */
3725 /* If this node is a statement and we are only annotating types, return an
3726 empty statement list. */
3730 /* If this node is a non-static subexpression and we are only annotating
3731 types, make this into a NULL_EXPR. */
3738 N_Raise_Constraint_Error));
3747 {
3748 /* If this is a statement and we are at top level, it must be part of
3749 the elaboration procedure, so mark us as being in that procedure. */
3751 {
3754 }
3756 /* If we are in the elaboration procedure, check if we are violating a
3757 No_Elaboration_Code restriction by having a statement there. Don't
3758 check for a possible No_Elaboration_Code restriction violation on
3759 N_Handled_Sequence_Of_Statements, as we want to signal an error on
3760 every nested real statement instead. This also avoids triggering
3761 spurious errors on dummy (empty) sequences created by the front-end
3762 for package bodies in some cases. */
3766 }
3769 {
3770 /********************************/
3771 /* Chapter 2: Lexical Elements */
3772 /********************************/
3782 {
3783 tree gnu_type;
3785 /* Get the type of the result, looking inside any padding and
3786 justified modular types. Then get the value in that type. */
3795 /* If the result overflows (meaning it doesn't fit in its base type),
3796 abort. We would like to check that the value is within the range
3797 of the subtype, but that causes problems with subtypes whose usage
3798 will raise Constraint_Error and with biased representation, so
3799 we don't. */
3801 }
3805 /* If a Entity is present, it means that this was one of the
3806 literals in a user-defined character type. In that case,
3807 just return the value in the CONST_DECL. Otherwise, use the
3808 character code. In that case, the base type should be an
3809 INTEGER_TYPE, but we won't bother checking for that. */
3813 else
3814 gnu_result
3815 = build_int_cst_type
3820 /* If this is of a fixed-point type, the value we want is the
3821 value of the corresponding integer. */
3823 {
3826 gnu_result_type);
3828 }
3830 /* We should never see a Vax_Float type literal, since the front end
3831 is supposed to transform these using appropriate conversions. */
3835 else
3836 {
3841 /* If the real value is zero, so is the result. Otherwise,
3842 convert it to a machine number if it isn't already. That
3843 forces BASE to 0 or 2 and simplifies the rest of our logic. */
3846 else
3847 {
3849 ur_realval
3853 gnu_result
3856 /* If we have a base of zero, divide by the denominator.
3857 Otherwise, the base must be 2 and we scale the value, which
3858 we know can fit in the mantissa of the type (hence the use
3859 of that type above). */
3861 gnu_result
3864 gnu_result,
3866 gnu_result_type));
3867 else
3868 {
3869 REAL_VALUE_TYPE tmp;
3875 }
3876 }
3878 /* Now see if we need to negate the result. Do it this way to
3879 properly handle -0. */
3881 gnu_result
3883 gnu_result);
3884 }
3891 {
3898 else
3901 /* Build the string with the characters in the literal. Note
3902 that Ada strings are 1-origin. */
3906 /* Put a null at the end of the string in case it's in a context
3907 where GCC will want to treat it as a C string. */
3912 /* Strings in GCC don't normally have types, but we want
3913 this to not be converted to the array type. */
3918 }
3919 else
3920 {
3921 /* Build a list consisting of each character, then make
3922 the aggregate. */
3930 {
3931 gnu_list
3936 gnu_list);
3940 }
3942 gnu_result
3944 }
3951 /**************************************/
3952 /* Chapter 3: Declarations and Types */
3953 /**************************************/
3970 /* If we are just annotating types and this object has an unconstrained
3971 or task type, don't elaborate it. */
3981 && (!type_annotate_only
3983 {
3986 gnu_expr
3989 /* If this object has its elaboration delayed, we must force
3990 evaluation of GNU_EXPR right now and save it for when the object
3991 is frozen. */
3993 {
3996 gnu_expr
4001 else
4005 }
4006 }
4007 else
4013 /* If this is a deferred constant with an address clause, we ignore the
4014 full view since the clause is on the partial view and we cannot have
4015 2 different GCC trees for the object. The only bits of the full view
4016 we will use is the initializer, but it will be directly fetched. */
4029 /* Don't do anything if this renaming is handled by the front end or if
4030 we are just annotating types and this object has a composite or task
4031 type, don't elaborate it. We return the result in case it has any
4032 SAVE_EXPRs in it that need to be evaluated here. */
4034 && ! (type_annotate_only
4038 gnu_result
4041 else
4054 /* These are fully handled in the front end. */
4058 /*************************************/
4059 /* Chapter 4: Names and Expressions */
4060 /*************************************/
4069 {
4071 tree gnu_type;
4078 /* Convert vector inputs to their representative array type, to fit
4079 what the code below expects. */
4084 /* If we got a padded type, remove it too. */
4086 gnu_array_object
4088 gnu_array_object);
4092 /* First compute the number of dimensions of the array, then
4093 fill the expression array, the order depending on whether
4094 this is a Convention_Fortran array or not. */
4099 ;
4108 else
4116 {
4122 gnu_expr
4123 = emit_index_check
4127 gnat_temp);
4131 }
4132 }
4138 {
4140 tree gnu_type;
4145 /* Do any implicit dereferences of the prefix and do any needed
4146 range check. */
4151 {
4152 /* Get the bounds of the slice. */
4153 tree gnu_index_type
4157 /* Get the permitted bounds. */
4158 tree gnu_base_index_type
4160 tree gnu_base_min_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
4162 tree gnu_base_max_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
4169 /* Derive a good type to convert everything to. */
4172 /* Test whether the minimum slice value is too small. */
4175 gnu_min_expr),
4177 gnu_base_min_expr));
4179 /* Test whether the maximum slice value is too large. */
4182 gnu_max_expr),
4184 gnu_base_max_expr));
4186 /* Build a slice index check that returns the low bound,
4187 assuming the slice is not empty. */
4188 gnu_expr = emit_check
4193 /* Build a conditional expression that does the index checks and
4194 returns the low bound if the slice is not empty (max >= min),
4195 and returns the naked low bound otherwise (max < min), unless
4196 it is non-constant and the high bound is; this prevents VRP
4197 from inferring bogus ranges on the unlikely path. */
4201 gnu_max_expr),
4203 gnu_min_expr)),
4204 gnu_expr,
4208 }
4209 else
4210 /* Simply return the naked low bound. */
4213 /* If this is a slice with non-constant size of an array with constant
4214 size, set the maximum size for the allocation of temporaries. */
4221 }
4225 {
4229 tree gnu_field;
4233 {
4238 }
4242 /* For discriminant references in tagged types always substitute the
4243 corresponding discriminant as the actual selected component. */
4248 /* For discriminant references of untagged types always substitute the
4249 corresponding stored discriminant. */
4253 /* Handle extracting the real or imaginary part of a complex.
4254 The real part is the first field and the imaginary the last. */
4259 else
4260 {
4263 /* If there are discriminants, the prefix might be evaluated more
4264 than once, which is a problem if it has side-effects. */
4271 gnu_result
4275 && lvalue_required_for_attribute_p
4277 }
4281 }
4285 {
4286 /* The attribute designator. */
4289 /* The Elab_Spec and Elab_Body attributes are special in that Prefix
4290 is a unit, not an object with a GCC equivalent. */
4292 return
4300 }
4304 /* Like 'Access as far as we are concerned. */
4312 {
4313 tree gnu_aggr_type;
4315 /* ??? It is wrong to evaluate the type now, but there doesn't
4316 seem to be any other practical way of doing it. */
4320 gnu_aggr_type = gnu_result_type
4325 gnu_aggr_type
4335 gnu_result
4338 gnu_aggr_type);
4341 gnu_aggr_type,
4344 gnu_result
4345 = build_binary_op
4350 (Next
4352 else
4356 }
4364 else
4371 /* Get the operand expression. */
4375 gnu_result
4379 kind == N_Type_Conversion
4386 /* Skip further processing if the conversion is deemed a no-op. */
4388 {
4391 }
4395 /* If the result is a pointer type, see if we are improperly
4396 converting to a stricter alignment. */
4399 {
4405 post_error_ne_tree_2
4409 }
4411 /* If we are converting a descriptor to a function pointer, first
4412 build the pointer. */
4424 {
4429 /* GNAT_RANGE is either an N_Range node or an identifier denoting a
4430 subtype. */
4432 {
4435 }
4438 {
4443 }
4444 else
4449 /* If LOW and HIGH are identical, perform an equality test. Otherwise,
4450 ensure that GNU_OBJ is evaluated only once and perform a full range
4451 test. */
4453 gnu_result
4455 else
4456 {
4465 gnu_result
4467 }
4471 }
4479 ? RDIV_EXPR
4486 /* These can either be operations on booleans or on modular types.
4487 Fall through for boolean types since that's the way GNU_CODES is
4488 set up. */
4490 Modular_Integer_Kind))
4491 {
4492 enum tree_code code
4503 }
4505 /* ... fall through ... */
4517 {
4521 tree gnu_type;
4527 /* Pending generic support for efficient vector logical operations in
4528 GCC, convert vectors to their representative array type view and
4529 fallthrough. */
4533 /* If this is a comparison operator, convert any references to
4534 an unconstrained array value into a reference to the
4535 actual array. */
4537 {
4540 }
4542 /* If the result type is a private type, its full view may be a
4543 numeric subtype. The representation we need is that of its base
4544 type, given that it is the result of an arithmetic operation. */
4546 gnu_type = gnu_result_type
4549 /* If this is a shift whose count is not guaranteed to be correct,
4550 we need to adjust the shift count. */
4552 {
4554 tree gnu_max_shift
4561 gnu_rhs
4562 = build_binary_op
4565 gnu_count_type,
4566 gnu_max_shift,
4568 integer_one_node)),
4569 gnu_rhs);
4570 }
4572 /* For right shifts, the type says what kind of shift to do,
4573 so we may need to choose a different type. In this case,
4574 we have to ignore integer overflow lest it propagates all
4575 the way down and causes a CE to be explicitly raised. */
4577 {
4580 }
4583 {
4586 }
4589 {
4595 }
4597 /* Instead of expanding overflow checks for addition, subtraction
4598 and multiplication itself, the front end will leave this to
4599 the back end when Backend_Overflow_Checks_On_Target is set.
4600 As the GCC back end itself does not know yet how to properly
4601 do overflow checking, do it here. The goal is to push
4602 the expansions further into the back end over time. */
4611 else
4612 {
4613 /* Some operations, e.g. comparisons of arrays, generate complex
4614 trees that need to be annotated while they are being built. */
4617 }
4619 /* If this is a logical shift with the shift count not verified,
4620 we must return zero if it is too large. We cannot compensate
4621 above in this case. */
4624 gnu_result
4625 = build_cond_expr
4628 gnu_rhs,
4632 gnu_result);
4633 }
4637 {
4640 tree gnu_false
4644 gnu_result
4646 }
4655 /* This case can apply to a boolean or a modular type.
4656 Fall through for a boolean operand since GNU_CODES is set
4657 up to handle this. */
4661 {
4665 gnu_expr);
4667 }
4669 /* ... fall through ... */
4676 else
4683 gnu_result
4686 else
4692 {
4694 tree gnu_type;
4699 /* The Expression operand can either be an N_Identifier or
4700 Expanded_Name, which must represent a type, or a
4701 N_Qualified_Expression, which contains both the object type and an
4702 initial value for the object. */
4707 {
4708 Entity_Id gnat_desig_type
4716 gnu_init
4721 {
4724 }
4725 else
4726 {
4732 }
4733 }
4734 else
4741 ignore_init_type);
4742 }
4745 /**************************/
4746 /* Chapter 5: Statements */
4747 /**************************/
4755 /* When not optimizing, turn null statements from source into gotos to
4756 the next statement that the middle-end knows how to preserve. */
4758 {
4768 }
4769 else
4774 /* Get the LHS and RHS of the statement and convert any reference to an
4775 unconstrained array into a reference to the underlying array. */
4778 /* If the type has a size that overflows, convert this into raise of
4779 Storage_Error: execution shouldn't have gotten here anyway. */
4783 N_Raise_Storage_Error);
4785 gnu_result
4787 else
4788 {
4789 gnu_rhs
4792 /* If range check is needed, emit code to generate it. */
4795 gnat_node);
4797 gnu_result
4800 /* If the type being assigned is an array type and the two sides
4801 are not completely disjoint, play safe and use memmove. */
4805 {
4819 }
4820 }
4824 {
4827 /* Make the outer COND_EXPR. Avoid non-determinism. */
4836 /* Now make a COND_EXPR for each of the "else if" parts. Put each
4837 into the previous "else" part and point to where to put any
4838 outer "else". Also avoid non-determinism. */
4842 {
4852 }
4855 }
4879 gnu_result
4889 {
4892 /* If we have a return label defined, convert this into a branch to
4893 that label. The return proper will be handled elsewhere. */
4895 {
4898 /* When not optimizing, make sure the return is preserved. */
4902 }
4904 /* If the subprogram is a function, we must return the expression. */
4906 {
4911 /* Do not remove the padding from GNU_RET_VAL if the inner type is
4912 self-referential since we want to allocate the fixed size. */
4914 && TYPE_IS_PADDING_P
4916 && CONTAINS_PLACEHOLDER_P
4920 /* If the subprogram returns by direct reference, return a pointer
4921 to the return value. */
4926 /* Otherwise, if it returns an unconstrained array, we have to
4927 allocate a new version of the result and return it. */
4929 {
4932 gnu_ret_val,
4937 }
4939 /* If the subprogram returns by invisible reference, dereference
4940 the pointer it is passed using the type of the return value
4941 and build the copy operation manually. This ensures that we
4942 don't copy too much data, for example if the return type is
4943 unconstrained with a maximum size. */
4945 {
4946 gnu_ret_obj
4948 gnu_result_decl);
4954 }
4956 /* Otherwise, build a regular return. */
4957 else
4959 }
4960 else
4961 {
4964 }
4967 }
4975 /***************************/
4976 /* Chapter 6: Subprograms */
4977 /***************************/
4980 /* Unless there is a freeze node, declare the subprogram. We consider
4981 this a "definition" even though we're not generating code for
4982 the subprogram because we will be making the corresponding GCC
4983 node here. */
4992 /* This subprogram doesn't exist for code generation purposes, but we
4993 have to elaborate the types of any parameters and result, unless
4994 they are imported types (nothing to generate in this case). */
4996 /* Process the parameter types first. */
4999 = First_Formal_With_Extras
5008 /* Then the result type, set to Standard_Void_Type for procedures. */
5010 {
5011 Entity_Id gnat_temp_type
5016 }
5022 /* For a child unit identifier go up a level to get the specification.
5023 We get this when we try to find the spec of a child unit package
5024 that is the compilation unit being compiled. */
5038 /************************/
5039 /* Chapter 7: Packages */
5040 /************************/
5056 /* If this is the body of a generic package - do nothing. */
5058 {
5061 }
5072 /********************************/
5073 /* Chapter 8: Visibility Rules */
5074 /********************************/
5078 /* Nothing to do here - but these may appear in list of declarations. */
5082 /*********************/
5083 /* Chapter 9: Tasks */
5084 /*********************/
5095 /*********************************************************/
5096 /* Chapter 10: Program Structure and Compilation Issues */
5097 /*********************************************************/
5100 /* This is not called for the main unit on which gigi is invoked. */
5109 /* Simply process whatever unit is being inserted. */
5117 /***************************/
5118 /* Chapter 11: Exceptions */
5119 /***************************/
5122 /* If there is an At_End procedure attached to this node, and the EH
5123 mechanism is SJLJ, we must have at least a corresponding At_End
5124 handler, unless the No_Exception_Handlers restriction is set. */
5139 else
5160 gnu_constraint_error_label_stack
5165 gnu_storage_error_label_stack
5170 gnu_program_error_label_stack
5174 /******************************/
5175 /* Chapter 12: Generic Units */
5176 /******************************/
5186 /* These nodes can appear on a declaration list but there is nothing to
5187 to be done with them. */
5191 /**************************************************/
5192 /* Chapter 13: Representation Clauses and */
5193 /* Implementation-Dependent Features */
5194 /**************************************************/
5199 /* The only one we need to deal with is 'Address since, for the others,
5200 the front-end puts the information elsewhere. */
5204 /* And we only deal with 'Address if the object has a Freeze node. */
5209 /* Get the value to use as the address and save it as the equivalent
5210 for the object. When it is frozen, gnat_to_gnu_entity will do the
5211 right thing. */
5218 /* We do nothing with these. SEM puts the information elsewhere. */
5224 {
5234 /* First retrieve the 3 operand lists built by the front-end. */
5237 {
5244 }
5248 {
5255 }
5259 gnu_clobbers
5262 gnu_clobbers);
5264 /* Then perform some standard checking and processing on the
5265 operands. In particular, mark them addressable if needed. */
5270 oconstraints
5274 {
5276 constraint
5282 {
5283 /* If the operand is going to end up in memory,
5284 mark it addressable. Note that we don't test
5285 allows_mem like in the input case below; this
5286 is modelled on the C front-end. */
5290 }
5291 else
5295 }
5298 {
5300 constraint
5306 {
5307 /* If the operand is going to end up in memory,
5308 mark it addressable. */
5312 }
5313 else
5317 }
5323 }
5324 else
5329 /****************/
5330 /* Added Nodes */
5331 /****************/
5349 {
5352 tree gnu_obj_type;
5354 tree gnu_obj_size;
5356 /* If this is a thin pointer, we must dereference it to create
5357 a fat pointer, then go back below to a thin pointer. The
5358 reason for this is that we need a fat pointer someplace in
5359 order to properly compute the size. */
5363 gnu_ptr));
5365 /* If this is an unconstrained array, we know the object must
5366 have been allocated with the template in front of the object.
5367 So pass the template address, but get the total size. Do this
5368 by converting to a thin pointer. */
5370 gnu_ptr
5372 (TYPE_OBJECT_RECORD_TYPE
5374 gnu_ptr);
5379 {
5380 gnu_actual_obj_type
5384 gnu_actual_obj_type
5386 gnu_actual_obj_type,
5387 get_identifier
5389 }
5390 else
5397 {
5398 tree gnu_char_ptr_type
5404 }
5406 gnu_result
5410 gnat_node);
5411 }
5418 {
5421 }
5424 gnu_result
5427 /* If the type is VOID, this is a statement, so we need to
5428 generate the code for the call. Handle a Condition, if there
5429 is one. */
5431 {
5438 }
5439 else
5444 {
5449 /* No need for any warning in this case. */
5451 ;
5453 /* If the result is a pointer type, see if we are either converting
5454 from a non-pointer or from a pointer to a type with a different
5455 alias set and warn if so. If the result is defined in the same
5456 unit as this unchecked conversion, we can allow this because we
5457 can know to make the pointer type behave properly. */
5461 {
5474 || !alias_sets_conflict_p
5477 {
5478 post_error_ne
5481 post_error
5483 gnat_node);
5484 post_error_ne
5487 }
5488 }
5490 /* But if the result is a fat pointer type, we have no mechanism to
5491 do that, so we unconditionally warn in problematic cases. */
5493 {
5494 tree gnu_source_array_type
5498 tree gnu_target_array_type
5508 || !alias_sets_conflict_p
5511 {
5512 post_error_ne
5515 post_error
5517 gnat_node);
5518 }
5519 }
5520 }
5525 /* SCIL nodes require no processing for GCC. Other nodes should only
5526 be present when annotating types. */
5529 }
5531 /* If we pushed the processing of the elaboration routine, pop it back. */
5535 /* When not optimizing, turn boolean rvalues B into B != false tests
5536 so that the code just below can put the location information of the
5537 reference to B on the inequality operator for better debug info. */
5550 boolean_false_node));
5552 /* Set the location information on the result if it is a real expression.
5553 References can be reused for multiple GNAT nodes and they would get
5554 the location information of their last use. Note that we may have
5555 no result if we tried to build a CALL_EXPR node to a procedure with
5556 no side-effects and optimization is enabled. */
5564 /* If we're supposed to return something of void_type, it means we have
5565 something we're elaborating for effect, so just return. */
5569 /* If the result is a constant that overflowed, raise Constraint_Error. */
5571 {
5573 gnu_result
5576 N_Raise_Constraint_Error));
5577 }
5579 /* If our result has side-effects and is of an unconstrained type,
5580 make a SAVE_EXPR so that we can be sure it will only be referenced
5581 once. Note we must do this before any conversions. */
5587 /* Now convert the result to the result type, unless we are in one of the
5588 following cases:
5590 1. If this is the Name of an assignment statement or a parameter of
5591 a procedure call, return the result almost unmodified since the
5592 RHS will have to be converted to our type in that case, unless
5593 the result type has a simpler size. Likewise if there is just
5594 a no-op unchecked conversion in-between. Similarly, don't convert
5595 integral types that are the operands of an unchecked conversion
5596 since we need to ignore those conversions (for 'Valid).
5598 2. If we have a label (which doesn't have any well-defined type), a
5599 field or an error, return the result almost unmodified. Also don't
5600 do the conversion if the result type involves a PLACEHOLDER_EXPR in
5601 its size since those are the cases where the front end may have the
5602 type wrong due to "instantiating" the unconstrained record with
5603 discriminant values. Similarly, if the two types are record types
5604 with the same name don't convert. This will be the case when we are
5605 converting from a packable version of a type to its original type and
5606 we need those conversions to be NOPs in order for assignments into
5607 these types to work properly.
5609 3. If the type is void or if we have no result, return error_mark_node
5610 to show we have no result.
5612 4. Finally, if the type of the result is already correct. */
5634 && (CONTAINS_PLACEHOLDER_P
5638 {
5639 /* Remove padding only if the inner object is of self-referential
5640 size: in that case it must be an object of unconstrained type
5641 with a default discriminant and we want to avoid copying too
5642 much data. */
5647 gnu_result);
5648 }
5661 {
5662 /* Remove any padding. */
5665 gnu_result);
5666 }
5674 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on the result. */
5681 }
5682 \f
5683 /* Subroutine of above to push the exception label stack. GNU_STACK is
5684 a pointer to the stack to update and GNAT_LABEL, if present, is the
5685 label to push onto the stack. */
5687 static void
5689 {
5695 }
5696 \f
5697 /* Record the current code position in GNAT_NODE. */
5699 static void
5701 {
5706 }
5708 /* Insert the code for GNAT_NODE at the position saved for that node. */
5710 static void
5712 {
5715 }
5716 \f
5717 /* Start a new statement group chained to the previous group. */
5719 void
5721 {
5724 /* First see if we can get one from the free list. */
5727 else
5733 }
5735 /* Add GNU_STMT to the current statement group. */
5737 void
5739 {
5741 }
5743 /* Similar, but set the location of GNU_STMT to that of GNAT_NODE. */
5745 void
5747 {
5751 }
5753 /* Add a declaration statement for GNU_DECL to the current statement group.
5754 Get SLOC from Entity_Id. */
5756 void
5758 {
5762 /* If this is a variable that Gigi is to ignore, we may have been given
5763 an ERROR_MARK. So test for it. We also might have been given a
5764 reference for a renaming. So only do something for a decl. Also
5765 ignore a TYPE_DECL for an UNCONSTRAINED_ARRAY_TYPE. */
5773 /* If we are global, we don't want to actually output the DECL_EXPR for
5774 this decl since we already have evaluated the expressions in the
5775 sizes and positions as globals and doing it again would be wrong. */
5777 {
5778 /* Mark everything as used to prevent node sharing with subprograms.
5779 Note that walk_tree knows how to deal with TYPE_DECL, but neither
5780 VAR_DECL nor CONST_DECL. This appears to be somewhat arbitrary. */
5784 {
5788 }
5789 /* In any case, we have to deal with our own TYPE_ADA_SIZE field. */
5796 }
5797 else
5800 /* If this is a variable and an initializer is attached to it, it must be
5801 valid for the context. Similar to init_const in create_var_decl_1. */
5808 {
5809 /* If GNU_DECL has a padded type, convert it to the unpadded
5810 type so the assignment is done properly. */
5813 else
5820 {
5823 }
5826 }
5827 }
5829 /* Callback for walk_tree to mark the visited trees rooted at *TP. */
5831 static tree
5833 {
5839 /* Don't mark a dummy type as visited because we want to mark its sizes
5840 and fields once it's filled in. */
5848 }
5850 /* Mark nodes rooted at T with TREE_VISITED and types as having their
5851 sized gimplified. We use this to indicate all variable sizes and
5852 positions in global types may not be shared by any subprogram. */
5854 void
5856 {
5858 }
5860 /* Utility function to unshare expressions wrapped up in a SAVE_EXPR. */
5862 static tree
5865 {
5872 }
5874 /* Add GNU_CLEANUP, a cleanup action, to the current code group and
5875 set its location to that of GNAT_NODE if present. */
5877 static void
5879 {
5883 }
5885 /* Set the BLOCK node corresponding to the current code group to GNU_BLOCK. */
5887 void
5889 {
5892 }
5894 /* Return code corresponding to the current code group. It is normally
5895 a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
5896 BLOCK or cleanups were set. */
5898 tree
5900 {
5904 /* If this is a null list, allocate a new STATEMENT_LIST. Then, if there
5905 are cleanups, make a TRY_FINALLY_EXPR. Last, if there is a BLOCK,
5906 make a BIND_EXPR. Note that we nest in that because the cleanup may
5907 reference variables in the block. */
5919 /* Remove this group from the stack and add it to the free list. */
5925 }
5927 /* Add a list of statements from GNAT_LIST, a possibly-empty list of
5928 statements.*/
5930 static void
5932 {
5933 Node_Id gnat_node;
5939 }
5941 /* Build a tree from GNAT_LIST, a possibly-empty list of statements.
5942 If BINDING_P is true, push and pop a binding level around the list. */
5944 static tree
5946 {
5956 }
5957 \f
5958 /* Push and pop routines for stacks. We keep a free list around so we
5959 don't waste tree nodes. */
5961 static void
5963 {
5967 {
5972 }
5973 else
5977 }
5979 static void
5981 {
5987 }
5988 \f
5989 /* Generate GIMPLE in place for the expression at *EXPR_P. */
5991 int
5994 {
5996 tree op;
6002 {
6004 /* If this is for a scalar, just make a VAR_DECL for it. If for
6005 an aggregate, get a null pointer of the appropriate type and
6006 dereference it. */
6010 integer_zero_node));
6011 else
6012 {
6015 }
6021 /* We should only do this if we are just elaborating for side-effects,
6022 but we can't know that yet. */
6030 {
6031 /* If we are taking the address of a constant CONSTRUCTOR, make sure
6032 it is put into static memory. We know it's going to be read-only
6033 given the semantics we have and it must be in static memory when
6034 the reference is in an elaboration procedure. */
6036 {
6047 }
6049 /* Otherwise explicitly create the local temporary. That's required
6050 if the type is passed by reference. */
6051 else
6052 {
6062 }
6065 }
6072 /* The expressions for the RM bounds must be gimplified to ensure that
6073 they are properly elaborated. See gimplify_decl_expr. */
6077 {
6082 {
6087 {
6091 }
6095 {
6099 }
6101 }
6106 }
6108 /* ... fall through ... */
6112 }
6113 }
6115 /* Generate GIMPLE in place for the statement at *STMT_P. */
6117 static enum gimplify_status
6119 {
6123 {
6129 {
6134 tree t;
6136 /* Build the condition expression from the test, if any. */
6138 gnu_cond
6142 /* Set to emit the statements of the loop. */
6145 /* We first emit the start label and then a conditional jump to the
6146 end label if there's a top condition, then the update if it's at
6147 the top, then the body of the loop, then a conditional jump to
6148 the end label if there's a bottom condition, then the update if
6149 it's at the bottom, and finally a jump to the start label and the
6150 definition of the end label. */
6152 gnu_start_label),
6153 stmt_p);
6174 gnu_end_label),
6175 stmt_p);
6177 }
6180 /* Build a statement to jump to the corresponding end label, then
6181 see if it needs to be conditional. */
6190 }
6191 }
6192 \f
6193 /* Force references to each of the entities in packages withed by GNAT_NODE.
6194 Operate recursively but check that we aren't elaborating something more
6195 than once.
6197 This routine is exclusively called in type_annotate mode, to compute DDA
6198 information for types in withed units, for ASIS use. */
6200 static void
6202 {
6205 /* Process each unit only once. As we trace the context of all relevant
6206 units transitively, including generic bodies, we may encounter the
6207 same generic unit repeatedly. */
6211 /* Save entities in all context units. A body may have an implicit_with
6212 on its own spec, if the context includes a child unit, so don't save
6213 the spec twice. */
6220 {
6224 {
6241 }
6243 {
6244 Node_Id gnat_body
6247 /* Retrieve compilation unit node of generic body. */
6252 /* If body is available, elaborate its context. */
6255 }
6256 }
6260 }
6261 \f
6262 /* Do the processing of GNAT_NODE, an N_Freeze_Entity. */
6264 static void
6266 {
6271 /* If this is a package, we need to generate code for the package. */
6273 {
6274 insert_code_for
6278 }
6280 /* Don't do anything for class-wide types as they are always transformed
6281 into their root type. */
6285 /* Check for an old definition. This freeze node might be for an Itype. */
6286 gnu_old
6289 /* If this entity has an address representation clause, GNU_OLD is the
6290 address, so discard it here. */
6294 /* Don't do anything for subprograms that may have been elaborated before
6295 their freeze nodes. This can happen, for example, because of an inner
6296 call in an instance body or because of previous compilation of a spec
6297 for inlining purposes. */
6305 /* If we have a non-dummy type old tree, we have nothing to do, except
6306 aborting if this is the public view of a private type whose full view was
6307 not delayed, as this node was never delayed as it should have been. We
6308 let this happen for concurrent types and their Corresponding_Record_Type,
6309 however, because each might legitimately be elaborated before its own
6310 freeze node, e.g. while processing the other. */
6314 {
6322 }
6324 /* Reset the saved tree, if any, and elaborate the object or type for real.
6325 If there is a full view, elaborate it and use the result. And, if this
6326 is the root type of a class-wide type, reuse it for the latter. */
6328 {
6338 }
6342 {
6345 /* Propagate back-annotations from full view to partial view. */
6355 /* The above call may have defined this entity (the simplest example
6356 of this is when we have a private enumeral type since the bounds
6357 will have the public view). */
6360 }
6361 else
6362 {
6363 tree gnu_init
6369 }
6376 /* If we've made any pointers to the old version of this type, we
6377 have to update them. */
6381 }
6382 \f
6383 /* Elaborate decls in the lists GNAT_DECLS and GNAT_DECLS2, if present.
6384 We make two passes, one to elaborate anything other than bodies (but
6385 we declare a function if there was no spec). The second pass
6386 elaborates the bodies.
6388 GNAT_END_LIST gives the element in the list past the end. Normally,
6389 this is Empty, but can be First_Real_Statement for a
6390 Handled_Sequence_Of_Statements.
6392 We make a complete pass through both lists if PASS1P is true, then make
6393 the second pass over both lists if PASS2P is true. The lists usually
6394 correspond to the public and private parts of a package. */
6396 static void
6399 {
6401 Node_Id gnat_decl;
6411 {
6412 /* For package specs, we recurse inside the declarations,
6413 thus taking the two pass approach inside the boundary. */
6421 /* Similarly for any declarations in the actions of a
6422 freeze node. */
6424 {
6427 }
6429 /* Package bodies with freeze nodes get their elaboration deferred
6430 until the freeze node, but the code must be placed in the right
6431 place, so record the code position now. */
6439 (Corresponding_Spec
6442 record_code_position
6445 /* We defer most subprogram bodies to the second pass. */
6447 {
6449 {
6455 }
6456 }
6458 /* For bodies and stubs that act as their own specs, the entity
6459 itself must be elaborated in the first pass, because it may
6460 be used in other declarations. */
6462 {
6463 Node_Id gnat_subprog_id
6470 }
6472 /* Concurrent stubs stand for the corresponding subprogram bodies,
6473 which are deferred like other bodies. */
6476 ;
6478 else
6480 }
6482 /* Here we elaborate everything we deferred above except for package bodies,
6483 which are elaborated at their freeze nodes. Note that we must also
6484 go inside things (package specs and freeze nodes) the first pass did. */
6490 {
6506 }
6507 }
6508 \f
6509 /* Make a unary operation of kind CODE using build_unary_op, but guard
6510 the operation by an overflow check. CODE can be one of NEGATE_EXPR
6511 or ABS_EXPR. GNU_TYPE is the type desired for the result. Usually
6512 the operation is to be performed in that type. GNAT_NODE is the gnat
6513 node conveying the source location for which the error should be
6514 signaled. */
6516 static tree
6518 Node_Id gnat_node)
6519 {
6528 }
6530 /* Make a binary operation of kind CODE using build_binary_op, but guard
6531 the operation by an overflow check. CODE can be one of PLUS_EXPR,
6532 MINUS_EXPR or MULT_EXPR. GNU_TYPE is the type desired for the result.
6533 Usually the operation is to be performed in that type. GNAT_NODE is
6534 the GNAT node conveying the source location for which the error should
6535 be signaled. */
6537 static tree
6540 {
6545 tree gnu_expr;
6548 tree rhs_lt_zero;
6549 tree check_pos;
6550 tree check_neg;
6551 tree check;
6556 /* Prefer a constant or known-positive rhs to simplify checks. */
6561 {
6565 }
6568 ? boolean_false_node
6571 /* ??? Should use more efficient check for operand_equal_p (lhs, rhs, 0) */
6573 /* Try a few strategies that may be cheaper than the general
6574 code at the end of the function, if the rhs is not known.
6575 The strategies are:
6576 - Call library function for 64-bit multiplication (complex)
6577 - Widen, if input arguments are sufficiently small
6578 - Determine overflow using wrapped result for addition/subtraction. */
6581 {
6582 /* Even for add/subtract double size to get another base type. */
6586 {
6592 }
6597 {
6604 tree check = build_binary_op
6613 return
6615 }
6618 {
6620 tree wrapped_expr = convert
6625 tree result = convert
6628 /* Overflow when (rhs < 0) ^ (wrapped_expr < lhs)), for addition
6629 or when (rhs < 0) ^ (wrapped_expr > lhs) for subtraction. */
6630 tree check = build_binary_op
6635 return
6637 }
6638 }
6641 {
6643 /* When rhs >= 0, overflow when lhs > type_max - rhs. */
6648 /* When rhs < 0, overflow when lhs < type_min - rhs. */
6655 /* When rhs >= 0, overflow when lhs < type_min + rhs. */
6660 /* When rhs < 0, overflow when lhs > type_max + rhs. */
6667 /* The check here is designed to be efficient if the rhs is constant,
6668 but it will work for any rhs by using integer division.
6669 Four different check expressions determine wether X * C overflows,
6670 depending on C.
6671 C == 0 => false
6672 C > 0 => X > type_max / C || X < type_min / C
6673 C == -1 => X == type_min
6674 C < -1 => X > type_min / C || X < type_max / C */
6679 check_pos
6682 rhs),
6685 boolean_type_node,
6688 boolean_type_node,
6691 check_neg
6696 type_min),
6699 boolean_type_node,
6702 boolean_type_node,
6708 }
6712 /* If we can fold the expression to a constant, just return it.
6713 The caller will deal with overflow, no need to generate a check. */
6718 check_pos);
6721 }
6723 /* Emit code for a range check. GNU_EXPR is the expression to be checked,
6724 GNAT_RANGE_TYPE the gnat type or subtype containing the bounds against
6725 which we have to check. GNAT_NODE is the GNAT node conveying the source
6726 location for which the error should be signaled. */
6728 static tree
6730 {
6736 /* If GNU_EXPR has GNAT_RANGE_TYPE as its base type, no check is needed.
6737 This can for example happen when translating 'Val or 'Value. */
6741 /* If GNU_EXPR has an integral type that is narrower than GNU_RANGE_TYPE,
6742 we can't do anything since we might be truncating the bounds. No
6743 check is needed in this case. */
6749 /* Checked expressions must be evaluated only once. */
6752 /* Note that the form of the check is
6753 (not (expr >= lo)) or (not (expr <= hi))
6754 the reason for this slightly convoluted form is that NaNs
6755 are not considered to be in range in the float case. */
6756 return emit_check
6758 invert_truthvalue
6762 invert_truthvalue
6766 gnu_high)))),
6768 }
6769 \f
6770 /* Emit code for an index check. GNU_ARRAY_OBJECT is the array object which
6771 we are about to index, GNU_EXPR is the index expression to be checked,
6772 GNU_LOW and GNU_HIGH are the lower and upper bounds against which GNU_EXPR
6773 has to be checked. Note that for index checking we cannot simply use the
6774 emit_range_check function (although very similar code needs to be generated
6775 in both cases) since for index checking the array type against which we are
6776 checking the indices may be unconstrained and consequently we need to get
6777 the actual index bounds from the array object itself (GNU_ARRAY_OBJECT).
6778 The place where we need to do that is in subprograms having unconstrained
6779 array formal parameters. GNAT_NODE is the GNAT node conveying the source
6780 location for which the error should be signaled. */
6782 static tree
6785 {
6786 tree gnu_expr_check;
6788 /* Checked expressions must be evaluated only once. */
6791 /* Must do this computation in the base type in case the expression's
6792 type is an unsigned subtypes. */
6795 /* If GNU_LOW or GNU_HIGH are a PLACEHOLDER_EXPR, qualify them by
6796 the object we are handling. */
6800 return emit_check
6803 gnu_expr_check,
6805 gnu_low)),
6807 gnu_expr_check,
6809 gnu_high))),
6811 }
6812 \f
6813 /* GNU_COND contains the condition corresponding to an access, discriminant or
6814 range check of value GNU_EXPR. Build a COND_EXPR that returns GNU_EXPR if
6815 GNU_COND is false and raises a CONSTRAINT_ERROR if GNU_COND is true.
6816 REASON is the code that says why the exception was raised. GNAT_NODE is
6817 the GNAT node conveying the source location for which the error should be
6818 signaled. */
6820 static tree
6822 {
6823 tree gnu_call
6825 tree gnu_result
6829 gnu_expr);
6831 /* GNU_RESULT has side effects if and only if GNU_EXPR has:
6832 we don't need to evaluate it just for the check. */
6836 }
6837 \f
6838 /* Return an expression that converts GNU_EXPR to GNAT_TYPE, doing overflow
6839 checks if OVERFLOW_P is true and range checks if RANGE_P is true.
6840 GNAT_TYPE is known to be an integral type. If TRUNCATE_P true, do a
6841 float to integer conversion with truncation; otherwise round.
6842 GNAT_NODE is the GNAT node conveying the source location for which the
6843 error should be signaled. */
6845 static tree
6848 {
6855 /* If we are not doing any checks, the output is an integral type, and
6856 the input is not a floating type, just do the conversion. This
6857 shortcut is required to avoid problems with packed array types
6858 and simplifies code in all cases anyway. */
6863 /* First convert the expression to its base type. This
6864 will never generate code, but makes the tests below much simpler.
6865 But don't do this if converting from an integer type to an unconstrained
6866 array type since then we need to get the bounds from the original
6867 (unpacked) type. */
6871 /* If overflow checks are requested, we need to be sure the result will
6872 fit in the output base type. But don't do this if the input
6873 is integer and the output floating-point. */
6876 {
6877 /* Ensure GNU_EXPR only gets evaluated once. */
6885 /* Convert the lower bounds to signed types, so we're sure we're
6886 comparing them properly. Likewise, convert the upper bounds
6887 to unsigned types. */
6901 /* Check each bound separately and only if the result bound
6902 is tighter than the bound on the input type. Note that all the
6903 types are base types, so the bounds must be constant. Also,
6904 the comparison is done in the base type of the input, which
6905 always has the proper signedness. First check for input
6906 integer (which means output integer), output float (which means
6907 both float), or mixed, in which case we always compare.
6908 Note that we have to do the comparison which would *fail* in the
6909 case of an error since if it's an FP comparison and one of the
6910 values is a NaN or Inf, the comparison will fail. */
6917 gnu_cond
6918 = invert_truthvalue
6921 gnu_out_lb)));
6929 gnu_cond
6931 invert_truthvalue
6933 gnu_input,
6935 gnu_out_ub))));
6940 }
6942 /* Now convert to the result base type. If this is a non-truncating
6943 float-to-integer conversion, round. */
6946 {
6952 /* The following calculations depend on proper rounding to even
6953 of each arithmetic operation. In order to prevent excess
6954 precision from spoiling this property, use the widest hardware
6955 floating-point type if FP_ARITH_MAY_WIDEN is true. */
6956 calc_type
6959 /* FIXME: Should not have padding in the first place. */
6963 /* Compute the exact value calc_type'Pred (0.5) at compile time. */
6967 half_minus_pred_half);
6970 /* If the input is strictly negative, subtract this value
6971 and otherwise add it from the input. For 0.5, the result
6972 is exactly between 1.0 and the machine number preceding 1.0
6973 (for calc_type). Since the last bit of 1.0 is even, this 0.5
6974 will round to 1.0, while all other number with an absolute
6975 value less than 0.5 round to 0.0. For larger numbers exactly
6976 halfway between integers, rounding will always be correct as
6977 the true mathematical result will be closer to the higher
6978 integer compared to the lower one. So, this constant works
6979 for all floating-point numbers.
6981 The reason to use the same constant with subtract/add instead
6982 of a positive and negative constant is to allow the comparison
6983 to be scheduled in parallel with retrieval of the constant and
6984 conversion of the input to the calc_type (if necessary). */
6989 gnu_comp
6991 gnu_add_pred_half
6993 gnu_subtract_pred_half
6997 }
7003 else
7006 /* Finally, do the range check if requested. Note that if the result type
7007 is a modular type, the range check is actually an overflow check. */
7014 }
7015 \f
7016 /* Return true if TYPE is a smaller form of ORIG_TYPE. */
7018 static bool
7020 {
7023 /* We're not interested in variants here. */
7027 /* Like a variant, a packable version keeps the original TYPE_NAME. */
7038 }
7040 /* Return true if GNU_EXPR can be directly addressed. This is the case
7041 unless it is an expression involving computation or if it involves a
7042 reference to a bitfield or to an object not sufficiently aligned for
7043 its type. If GNU_TYPE is non-null, return true only if GNU_EXPR can
7044 be directly addressed as an object of this type.
7046 *** Notes on addressability issues in the Ada compiler ***
7048 This predicate is necessary in order to bridge the gap between Gigi
7049 and the middle-end about addressability of GENERIC trees. A tree
7050 is said to be addressable if it can be directly addressed, i.e. if
7051 its address can be taken, is a multiple of the type's alignment on
7052 strict-alignment architectures and returns the first storage unit
7053 assigned to the object represented by the tree.
7055 In the C family of languages, everything is in practice addressable
7056 at the language level, except for bit-fields. This means that these
7057 compilers will take the address of any tree that doesn't represent
7058 a bit-field reference and expect the result to be the first storage
7059 unit assigned to the object. Even in cases where this will result
7060 in unaligned accesses at run time, nothing is supposed to be done
7061 and the program is considered as erroneous instead (see PR c/18287).
7063 The implicit assumptions made in the middle-end are in keeping with
7064 the C viewpoint described above:
7065 - the address of a bit-field reference is supposed to be never
7066 taken; the compiler (generally) will stop on such a construct,
7067 - any other tree is addressable if it is formally addressable,
7068 i.e. if it is formally allowed to be the operand of ADDR_EXPR.
7070 In Ada, the viewpoint is the opposite one: nothing is addressable
7071 at the language level unless explicitly declared so. This means
7072 that the compiler will both make sure that the trees representing
7073 references to addressable ("aliased" in Ada parlance) objects are
7074 addressable and make no real attempts at ensuring that the trees
7075 representing references to non-addressable objects are addressable.
7077 In the first case, Ada is effectively equivalent to C and handing
7078 down the direct result of applying ADDR_EXPR to these trees to the
7079 middle-end works flawlessly. In the second case, Ada cannot afford
7080 to consider the program as erroneous if the address of trees that
7081 are not addressable is requested for technical reasons, unlike C;
7082 as a consequence, the Ada compiler must arrange for either making
7083 sure that this address is not requested in the middle-end or for
7084 compensating by inserting temporaries if it is requested in Gigi.
7086 The first goal can be achieved because the middle-end should not
7087 request the address of non-addressable trees on its own; the only
7088 exception is for the invocation of low-level block operations like
7089 memcpy, for which the addressability requirements are lower since
7090 the type's alignment can be disregarded. In practice, this means
7091 that Gigi must make sure that such operations cannot be applied to
7092 non-BLKmode bit-fields.
7094 The second goal is achieved by means of the addressable_p predicate
7095 and by inserting SAVE_EXPRs around trees deemed non-addressable.
7096 They will be turned during gimplification into proper temporaries
7097 whose address will be used in lieu of that of the original tree. */
7099 static bool
7101 {
7102 /* For an integral type, the size of the actual type of the object may not
7103 be greater than that of the expected type, otherwise an indirect access
7104 in the latter type wouldn't correctly set all the bits of the object. */
7110 /* The size of the actual type of the object may not be smaller than that
7111 of the expected type, otherwise an indirect access in the latter type
7112 would be larger than the object. But only record types need to be
7113 considered in practice for this case. */
7120 {
7125 /* All DECLs are addressable: if they are in a register, we can force
7126 them to memory. */
7131 /* Taking the address of a dereference yields the original pointer. */
7136 /* Taking the address yields a pointer to the constant pool. */
7140 /* Taking the address of a static constructor yields a pointer to the
7141 tree constant pool. */
7153 /* All rvalues are deemed addressable since taking their address will
7154 force a temporary to be created by the middle-end. */
7158 /* The address of a compound expression is that of its 2nd operand. */
7162 /* We accept &COND_EXPR as soon as both operands are addressable and
7163 expect the outcome to be the address of the selected operand. */
7169 /* Even with DECL_BIT_FIELD cleared, we have to ensure that
7170 the field is sufficiently aligned, in case it is subject
7171 to a pragma Component_Alignment. But we don't need to
7172 check the alignment of the containing record, as it is
7173 guaranteed to be not smaller than that of its most
7174 aligned field that is not a bit-field. */
7175 && (!STRICT_ALIGNMENT
7178 /* The field of a padding record is always addressable. */
7192 {
7193 /* This is addressable if we can avoid a copy. */
7197 && (!STRICT_ALIGNMENT
7202 && (!STRICT_ALIGNMENT
7208 }
7212 }
7213 }
7214 \f
7215 /* Do the processing for the declaration of a GNAT_ENTITY, a type. If
7216 a separate Freeze node exists, delay the bulk of the processing. Otherwise
7217 make a GCC type for GNAT_ENTITY and set up the correspondence. */
7219 void
7221 {
7222 tree gnu_old
7224 tree gnu_new;
7226 /* If we are to delay elaboration of this type, just do any
7227 elaborations needed for expressions within the declaration and
7228 make a dummy type entry for this node and its Full_View (if
7229 any) in case something points to it. Don't do this if it
7230 has already been done (the only way that can happen is if
7231 the private completion is also delayed). */
7237 {
7241 {
7247 }
7250 }
7252 /* If we saved away a dummy type for this node it means that this
7253 made the type that corresponds to the full type of an incomplete
7254 type. Clear that type for now and then update the type in the
7255 pointers. */
7257 {
7262 }
7264 /* Now fully elaborate the type. */
7268 /* If we have an old type and we've made pointers to this type,
7269 update those pointers. */
7274 /* If this is a record type corresponding to a task or protected type
7275 that is a completion of an incomplete type, perform a similar update
7276 on the type. ??? Including protected types here is a guess. */
7280 {
7281 tree gnu_task_old
7291 }
7292 }
7293 \f
7294 /* GNAT_ENTITY is the type of the resulting constructors,
7295 GNAT_ASSOC is the front of the Component_Associations of an N_Aggregate,
7296 and GNU_TYPE is the GCC type of the corresponding record.
7298 Return a CONSTRUCTOR to build the record. */
7300 static tree
7302 {
7305 /* We test for GNU_FIELD being empty in the case where a variant
7306 was the last thing since we don't take things off GNAT_ASSOC in
7307 that case. We check GNAT_ASSOC in case we have a variant, but it
7308 has no fields. */
7312 {
7317 /* The expander is supposed to put a single component selector name
7318 in every record component association. */
7321 /* Ignore fields that have Corresponding_Discriminants since we'll
7322 be setting that field in the parent. */
7327 /* Also ignore discriminants of Unchecked_Unions. */
7332 /* Before assigning a value in an aggregate make sure range checks
7333 are done if required. Then convert to the type of the field. */
7339 /* Add the field and expression to the list. */
7341 }
7345 #ifdef ENABLE_CHECKING
7346 {
7347 tree gnu_field;
7349 /* Verify every entry in GNU_LIST was used. */
7352 }
7353 #endif
7356 }
7358 /* Build a possibly nested constructor for array aggregates. GNAT_EXPR is
7359 the first element of an array aggregate. It may itself be an aggregate.
7360 GNU_ARRAY_TYPE is the GCC type corresponding to the array aggregate.
7361 GNAT_COMPONENT_TYPE is the type of the array component; it is needed
7362 for range checking. */
7364 static tree
7366 Entity_Id gnat_component_type)
7367 {
7370 tree gnu_expr;
7373 {
7374 /* If the expression is itself an array aggregate then first build the
7375 innermost constructor if it is part of our array (multi-dimensional
7376 case). */
7382 gnat_component_type);
7383 else
7384 {
7387 /* Before assigning the element to the array, make sure it is
7388 in range. */
7391 }
7393 gnu_expr_list
7395 gnu_expr_list);
7398 }
7401 }
7402 \f
7403 /* Subroutine of assoc_to_constructor: VALUES is a list of field associations,
7404 some of which are from RECORD_TYPE. Return a CONSTRUCTOR consisting
7405 of the associations that are from RECORD_TYPE. If we see an internal
7406 record, make a recursive call to fill it in as well. */
7408 static tree
7410 {
7415 {
7418 /* _Parent is an internal field, but may have values in the aggregate,
7419 so check for values first. */
7421 {
7424 }
7427 {
7432 }
7433 else
7434 /* If we have a record subtype, the names will match, but not the
7435 actual FIELD_DECLs. */
7438 {
7441 }
7447 }
7450 }
7451 \f
7452 /* EXP is to be treated as an array or record. Handle the cases when it is
7453 an access object and perform the required dereferences. */
7455 static tree
7457 {
7458 /* If the type is a pointer, dereference it. */
7463 /* If we got a padded type, remove it too. */
7468 }
7469 \f
7470 /* Convert SLOC into LOCUS. Return true if SLOC corresponds to a source code
7471 location and false if it doesn't. In the former case, set the Gigi global
7472 variable REF_FILENAME to the simple debug file name as given by sinput. */
7474 bool
7476 {
7481 {
7484 }
7485 else
7486 {
7492 /* Translate the location according to the line-map.h formula. */
7496 }
7498 ref_filename
7499 = IDENTIFIER_POINTER
7500 (get_identifier
7504 }
7506 /* Similar to set_expr_location, but start with the Sloc of GNAT_NODE and
7507 don't do anything if it doesn't correspond to a source location. */
7509 static void
7511 {
7512 location_t locus;
7518 }
7519 \f
7520 /* Return a colon-separated list of encodings contained in encoded Ada
7521 name. */
7525 {
7529 }
7531 /* Extract the Ada name from an encoded name. */
7535 {
7539 }
7540 \f
7541 /* Post an error message. MSG is the error message, properly annotated.
7542 NODE is the node at which to post the error and the node to use for the
7543 '&' substitution. */
7545 void
7547 {
7548 String_Template temp;
7549 Fat_Pointer fp;
7555 }
7557 /* Similar to post_error, but NODE is the node at which to post the error and
7558 ENT is the node to use for the '&' substitution. */
7560 void
7562 {
7563 String_Template temp;
7564 Fat_Pointer fp;
7570 }
7572 /* Similar to post_error_ne, but NUM is the number to use for the '^'. */
7574 void
7576 {
7579 }
7580 \f
7581 /* Similar to post_error_ne, but T is a GCC tree representing the number to
7582 write. If T represents a constant, the text inside curly brackets in
7583 MSG will be output (presumably including a '^'). Otherwise it will not
7584 be output and the text inside square brackets will be output instead. */
7586 void
7588 {
7595 {
7598 }
7599 else
7603 {
7609 ;
7610 else
7612 }
7617 }
7619 /* Similar to post_error_ne_tree, but NUM is a second integer to write. */
7621 void
7624 {
7627 }
7628 \f
7629 /* Initialize the table that maps GNAT codes to GCC codes for simple
7630 binary and unary operations. */
7632 static void
7634 {
7660 }
7662 /* Return a label to branch to for the exception type in KIND or NULL_TREE
7663 if none. */
7665 tree
7667 {
7674 else
7676 }