| blob | 581c57f93a4357e86f3bff22ec85bba100096e12 |
1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * T R A N S *
6 * *
7 * C Implementation File *
8 * *
9 * Copyright (C) 1992-2014, 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 ****************************************************************************/
67 /* We should avoid allocating more than ALLOCA_THRESHOLD bytes via alloca,
68 for fear of running out of stack space. If we need more, we use xmalloc
69 instead. */
70 #define ALLOCA_THRESHOLD 1000
72 /* In configurations where blocks have no end_locus attached, just
73 sink assignments into a dummy global. */
74 #ifndef BLOCK_SOURCE_END_LOCATION
76 #define BLOCK_SOURCE_END_LOCATION(BLOCK) block_end_locus_sink
77 #endif
79 /* For efficient float-to-int rounding, it is necessary to know whether
80 floating-point arithmetic may use wider intermediate results. When
81 FP_ARITH_MAY_WIDEN is not defined, be conservative and only assume
82 that arithmetic does not widen if double precision is emulated. */
83 #ifndef FP_ARITH_MAY_WIDEN
84 #if defined(HAVE_extendsfdf2)
85 #define FP_ARITH_MAY_WIDEN HAVE_extendsfdf2
86 #else
87 #define FP_ARITH_MAY_WIDEN 0
88 #endif
89 #endif
91 /* Pointers to front-end tables accessed through macros. */
102 /* Highest number in the front-end node table. */
105 /* Current node being treated, in case abort called. */
106 Node_Id error_gnat_node;
108 /* True when gigi is being called on an analyzed but unexpanded
109 tree, and the only purpose of the call is to properly annotate
110 types with representation information. */
113 /* Current filename without path. */
117 /* List of N_Validate_Unchecked_Conversion nodes in the unit. */
120 /* When not optimizing, we cache the 'First, 'Last and 'Length attributes
121 of unconstrained array IN parameters to avoid emitting a great deal of
122 redundant instructions to recompute them each time. */
126 tree first;
127 tree last;
128 tree length;
129 };
136 bitmap named_ret_val;
139 };
141 #define f_parm_attr_cache \
142 DECL_STRUCT_FUNCTION (current_function_decl)->language->parm_attr_cache
144 #define f_named_ret_val \
145 DECL_STRUCT_FUNCTION (current_function_decl)->language->named_ret_val
147 #define f_other_ret_val \
148 DECL_STRUCT_FUNCTION (current_function_decl)->language->other_ret_val
150 #define f_gnat_ret \
151 DECL_STRUCT_FUNCTION (current_function_decl)->language->gnat_ret
153 /* A structure used to gather together information about a statement group.
154 We use this to gather related statements, for example the "then" part
155 of a IF. In the case where it represents a lexical scope, we may also
156 have a BLOCK node corresponding to it and/or cleanups. */
163 };
167 /* List of unused struct stmt_group nodes. */
170 /* A structure used to record information on elaboration procedures
171 we've made and need to process.
173 ??? gnat_node should be Node_Id, but gengtype gets confused. */
179 };
183 /* Stack of exception pointer variables. Each entry is the VAR_DECL
184 that stores the address of the raised exception. Nonzero means we
185 are in an exception handler. Not used in the zero-cost case. */
188 /* In ZCX case, current exception pointer. Used to re-raise it. */
191 /* Stack for storing the current elaboration procedure decl. */
194 /* Stack of labels to be used as a goto target instead of a return in
195 some functions. See processing for N_Subprogram_Body. */
198 /* Stack of variable for the return value of a function with copy-in/copy-out
199 parameters. See processing for N_Subprogram_Body. */
202 /* Structure used to record information for a range check. */
204 tree low_bound;
205 tree high_bound;
206 tree type;
207 tree invariant_cond;
208 };
213 /* Structure used to record information for a loop. */
215 tree stmt;
216 tree loop_var;
218 };
223 /* Stack of loop_info structures associated with LOOP_STMT nodes. */
226 /* The stacks for N_{Push,Pop}_*_Label. */
231 /* Map GNAT tree codes to GCC tree codes for simple expressions. */
268 /* Hooks for debug info back-ends, only supported and used in a restricted set
269 of configurations. */
272 \f
273 /* This is the main program of the back-end. It sets up all the table
274 structures and then generates code. */
276 void
289 Nat number_file,
291 Entity_Id standard_boolean,
292 Entity_Id standard_integer,
293 Entity_Id standard_character,
294 Entity_Id standard_long_long_float,
295 Entity_Id standard_exception_type,
296 Int gigi_operating_mode)
297 {
298 Node_Id gnat_iter;
299 Entity_Id gnat_literal;
319 #if TARGET_ABI_OPEN_VMS
321 #endif
324 {
325 /* Use the identifier table to make a permanent copy of the filename as
326 the name table gets reallocated after Gigi returns but before all the
327 debugging information is output. The __gnat_to_canonical_file_spec
328 call translates filenames from pragmas Source_Reference that contain
329 host style syntax not understood by gdb. */
331 = IDENTIFIER_POINTER
332 (get_identifier
333 (__gnat_to_canonical_file_spec
336 /* We rely on the order isomorphism between files and line maps. */
339 /* We create the line map for a source file at once, with a fixed number
340 of columns chosen to avoid jumping over the next power of 2. */
345 }
349 /* Declare the name of the compilation unit as the first global
350 name in order to make the middle-end fully deterministic. */
354 /* Initialize ourselves. */
359 /* If we are just annotating types, give VOID_TYPE zero sizes to avoid
360 errors. */
362 {
365 }
367 /* Enable GNAT stack checking method if needed */
371 /* Retrieve alignment settings. */
375 /* Record the builtin types. Define `integer' and `character' first so that
376 dbx will output them first. */
382 /* Save the type we made for integer as the type for Standard.Integer. */
387 /* Likewise for character as the type for Standard.Character. */
392 /* Likewise for boolean as the type for Standard.Boolean. */
416 /* Now declare run-time functions. */
419 /* malloc is a function declaration tree for a function to allocate
420 memory. */
421 malloc_decl
427 /* malloc32 is a function declaration tree for a function to allocate
428 32-bit memory on a 64-bit system. Needed only on 64-bit VMS. */
429 malloc32_decl
435 /* free is a function declaration tree for a function to free memory. */
436 free_decl
439 ptr_void_type_node,
440 NULL_TREE),
442 Empty);
444 /* This is used for 64-bit multiplication with overflow checking. */
445 mulv64_decl
450 Empty);
452 /* Name of the _Parent field in tagged record types. */
455 /* Name of the Exception_Data type defined in System.Standard_Library. */
456 exception_data_name_id
459 /* Make the types and functions used for exception processing. */
460 jmpbuf_type
466 /* Functions to get and set the jumpbuf pointer for the current thread. */
467 get_jmpbuf_decl
468 = create_subprog_decl
474 set_jmpbuf_decl
475 = create_subprog_decl
478 NULL_TREE),
482 /* setjmp returns an integer and has one operand, which is a pointer to
483 a jmpbuf. */
484 setjmp_decl
485 = create_subprog_decl
488 NULL_TREE),
493 /* update_setjmp_buf updates a setjmp buffer from the current stack pointer
494 address. */
495 update_setjmp_buf_decl
496 = create_subprog_decl
503 /* Hooks to call when entering/leaving an exception handler. */
504 ftype
507 begin_handler_decl
513 end_handler_decl
519 unhandled_except_decl
521 NULL_TREE,
526 reraise_zcx_decl
530 /* Indicate that these never return. */
537 /* If in no exception handlers mode, all raise statements are redirected to
538 __gnat_last_chance_handler. No need to redefine raise_nodefer_decl since
539 this procedure will never be called in this mode. */
541 {
542 tree decl
543 = create_subprog_decl
546 build_pointer_type
556 }
557 else
558 {
559 /* Otherwise, make one decl for each exception reason. */
565 i == CE_Index_Check_Failed
569 }
571 /* Set the types that GCC and Gigi use from the front end. */
572 exception_type
576 /* Make other functions used for exception processing. */
577 get_excptr_decl
578 = create_subprog_decl
581 NULL_TREE),
585 set_exception_parameter_decl
586 = create_subprog_decl
589 ptr_void_type_node,
590 ptr_void_type_node,
591 NULL_TREE),
594 raise_nodefer_decl
595 = create_subprog_decl
599 NULL_TREE),
602 /* Indicate that it never returns. */
607 TYPE_QUAL_VOLATILE);
609 /* Build the special descriptor type and its null node if needed. */
611 {
623 {
624 tree field
631 elt--;
632 }
637 }
639 long_long_float_type
643 {
644 /* In this case, the builtin floating point types are VAX float,
645 so make up a type for use. */
651 }
652 else
655 /* Dummy objects to materialize "others" and "all others" in the exception
656 tables. These are exported by a-exexpr-gcc.adb, so see this unit for
657 the types to use. */
658 others_decl
661 unsigned_char_type_node,
664 all_others_decl
667 unsigned_char_type_node,
670 unhandled_others_decl
673 unsigned_char_type_node,
678 /* Install the builtins we might need, either internally or as
679 user available facilities for Intrinsic imports. */
687 /* Process any Pragma Ident for the main unit. */
692 /* If we are using the GCC exception mechanism, let GCC know. */
696 /* Initialize the GCC support for FP operations. */
699 /* Now translate the compilation unit proper. */
702 /* Then process the N_Validate_Unchecked_Conversion nodes. We do this at
703 the very end to avoid having to second-guess the front-end when we run
704 into dummy nodes during the regular processing. */
709 /* Finally see if we have any elaboration procedures to deal with. */
711 {
714 /* We should have a BIND_EXPR but it may not have any statements in it.
715 If it doesn't have any, we have nothing to do except for setting the
716 flag on the GNAT node. Otherwise, process the function as others. */
722 else
723 {
727 }
728 }
730 /* Destroy ourselves. */
734 /* We cannot track the location of errors past this point. */
736 }
737 \f
738 /* Return a subprogram decl corresponding to __gnat_rcheck_xx for the given
739 CHECK if KIND is EXCEPTION_SIMPLE, or else to __gnat_rcheck_xx_ext. */
741 static tree
743 {
752 {
754 ftype
756 build_pointer_type
759 }
760 else
761 {
766 ftype
768 build_pointer_type
772 }
774 result
779 /* Indicate that it never returns. */
786 }
787 \f
788 /* Return a positive value if an lvalue is required for GNAT_NODE, which is
789 an N_Attribute_Reference. */
791 static int
793 {
795 {
832 }
833 }
835 /* Return a positive value if an lvalue is required for GNAT_NODE. GNU_TYPE
836 is the type that will be used for GNAT_NODE in the translated GNU tree.
837 CONSTANT indicates whether the underlying object represented by GNAT_NODE
838 is constant in the Ada sense. If it is, ADDRESS_OF_CONSTANT indicates
839 whether its value is the address of a constant and ALIASED whether it is
840 aliased. If it isn't, ADDRESS_OF_CONSTANT and ALIASED are ignored.
842 The function climbs up the GNAT tree starting from the node and returns 1
843 upon encountering a node that effectively requires an lvalue downstream.
844 It returns int instead of bool to facilitate usage in non-purely binary
845 logic contexts. */
847 static int
850 {
854 {
864 /* If the parameter is by reference, an lvalue is required. */
870 /* Only the array expression can require an lvalue. */
874 /* ??? Consider that referencing an indexed component with a
875 non-constant index forces the whole aggregate to memory.
876 Note that N_Integer_Literal is conservative, any static
877 expression in the RM sense could probably be accepted. */
884 /* ... fall through ... */
887 /* Only the array expression can require an lvalue. */
901 /* We need to preserve addresses through a renaming. */
905 /* We cannot use a constructor if this is an atomic object because
906 the actual assignment might end up being done component-wise. */
910 /* We don't use a constructor if this is a class-wide object
911 because the effective type of the object is the equivalent
912 type of the class-wide subtype and it smashes most of the
913 data into an array of bytes to which we cannot convert. */
918 /* We cannot use a constructor if the LHS is an atomic object because
919 the actual assignment might end up being done component-wise. */
929 /* ... fall through ... */
933 /* We must look through all conversions because we may need to bypass
934 an intermediate conversion that is meant to be purely formal. */
940 /* We should only reach here through the N_Qualified_Expression case.
941 Force an lvalue for composite types since a block-copy to the newly
942 allocated area of memory is made. */
946 /* We look through dereferences for address of constant because we need
947 to handle the special cases listed above. */
953 /* ... fall through ... */
957 }
960 }
962 /* Return true if T is a constant DECL node that can be safely replaced
963 by its initializer. */
965 static bool
967 {
971 /* Return false for aggregate types that contain a placeholder since
972 their initializers cannot be manipulated easily. */
979 }
981 /* Return an expression equivalent to EXP but where constant DECL nodes
982 have been replaced by their initializer. */
984 static tree
986 {
988 tree op0;
991 {
1028 }
1031 }
1033 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Identifier,
1034 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer
1035 to where we should place the result type. */
1037 static tree
1039 {
1043 /* Whether we should require an lvalue for GNAT_NODE. Needed in
1044 specific circumstances only, so evaluated lazily. < 0 means
1045 unknown, > 0 means known true, 0 means known false. */
1048 /* If GNAT_NODE is a constant, whether we should use the initialization
1049 value instead of the constant entity, typically for scalars with an
1050 address clause when the parent doesn't require an lvalue. */
1053 /* If the Etype of this node does not equal the Etype of the Entity,
1054 something is wrong with the entity map, probably in generic
1055 instantiation. However, this does not apply to types. Since we sometime
1056 have strange Ekind's, just do this test for objects. Also, if the Etype of
1057 the Entity is private, the Etype of the N_Identifier is allowed to be the
1058 full type and also we consider a packed array type to be the same as the
1059 original type. Similarly, a class-wide type is equivalent to a subtype of
1060 itself. Finally, if the types are Itypes, one may be a copy of the other,
1061 which is also legal. */
1084 /* If this is a reference to a deferred constant whose partial view is an
1085 unconstrained private type, the proper type is on the full view of the
1086 constant, not on the full view of the type, which may be unconstrained.
1088 This may be a reference to a type, for example in the prefix of the
1089 attribute Position, generated for dispatching code (see Make_DT in
1090 exp_disp,adb). In that case we need the type itself, not is parent,
1091 in particular if it is a derived type */
1098 {
1101 }
1102 else
1103 {
1104 /* We want to use the Actual_Subtype if it has already been elaborated,
1105 otherwise the Etype. Avoid using Actual_Subtype for packed arrays to
1106 simplify things. */
1114 else
1116 }
1118 /* Expand the type of this identifier first, in case it is an enumeral
1119 literal, which only get made when the type is expanded. There is no
1120 order-of-elaboration issue here. */
1123 /* If this is a non-imported elementary constant with an address clause,
1124 retrieve the value instead of a pointer to be dereferenced unless
1125 an lvalue is required. This is generally more efficient and actually
1126 required if this is a static expression because it might be used
1127 in a context where a dereference is inappropriate, such as a case
1128 statement alternative or a record discriminant. There is no possible
1129 volatile-ness short-circuit here since Volatile constants must be
1130 imported per C.6. */
1135 {
1139 }
1142 {
1143 /* If this is a deferred constant, the initializer is attached to
1144 the full view. */
1149 }
1150 else
1153 /* Some objects (such as parameters passed by reference, globals of
1154 variable size, and renamed objects) actually represent the address
1155 of the object. In that case, we must do the dereference. Likewise,
1156 deal with parameters to foreign convention subprograms. */
1161 {
1164 /* If it's a PARM_DECL to foreign convention subprogram, convert it. */
1167 gnu_result
1170 /* If it's a CONST_DECL, return the underlying constant like below. */
1177 /* If it's a renaming pointer and, either the renamed object is constant
1178 or we are at the right binding level, we can reference the renamed
1179 object directly, since it is constant or has been protected against
1180 multiple evaluations. */
1189 /* Otherwise, do the final dereference. */
1190 else
1191 {
1201 }
1202 }
1204 /* If we have a constant declaration and its initializer, try to return the
1205 latter to avoid the need to call fold in lots of places and the need for
1206 elaboration code if this identifier is used as an initializer itself. */
1208 {
1214 /* If there is a (corresponding) variable or this is the address of a
1215 constant, we only want to return the initializer if an lvalue isn't
1216 required. Evaluate this now if we have not already done so. */
1218 require_lvalue
1222 /* Finally retrieve the initializer if this is deemed valid. */
1225 }
1227 /* But for a constant renaming we couldn't do that incrementally for its
1228 definition because of the need to return an lvalue so, if the present
1229 context doesn't itself require an lvalue, we try again here. */
1233 {
1235 require_lvalue
1240 }
1242 /* The GNAT tree has the type of a function set to its result type, so we
1243 adjust here. Also use the type of the result if the Etype is a subtype
1244 that is nominally unconstrained. Likewise if this is a deferred constant
1245 of a discriminated type whose full view can be elaborated statically, to
1246 avoid problematic conversions to the nominal subtype. But remove any
1247 padding from the resulting type. */
1254 {
1258 }
1263 }
1264 \f
1265 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Pragma. Return
1266 any statements we generate. */
1268 static tree
1270 {
1273 Node_Id gnat_temp;
1275 /* Do nothing if we are just annotating types and check for (and ignore)
1276 unrecognized pragmas. */
1283 {
1285 /* Do nothing at top level: all such variables are already viewable. */
1292 {
1298 #ifdef ASM_COMMENT_START
1300 #endif
1305 /* Use the value only if it fits into a normal register,
1306 otherwise use the address. */
1315 #ifdef ASM_COMMENT_START
1321 NULL);
1324 #endif
1326 asm_constraint,
1327 NULL_TREE,
1328 tree_cons
1336 }
1343 {
1347 {
1370 }
1371 }
1377 {
1395 }
1405 {
1406 Node_Id gnat_expr;
1407 /* Preserve the location of the pragma. */
1411 diagnostic_t kind;
1416 /* This is the String form: pragma Warning{s|_As_Error}(String). */
1418 {
1420 {
1433 }
1436 }
1438 /* This is the On/Off form: pragma Warnings (On | Off [,String]). */
1440 {
1442 {
1453 }
1456 {
1457 /* pragma Warnings (On | Off, Name) is handled differently. */
1462 }
1463 else
1467 }
1469 else
1472 /* This is the same implementation as in the C family of compilers. */
1474 {
1482 option_index++)
1486 {
1489 }
1490 }
1491 else
1498 }
1503 }
1506 }
1507 \f
1508 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Attribute node,
1509 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to
1510 where we should place the result type. ATTRIBUTE is the attribute ID. */
1512 static tree
1514 {
1520 /* ??? If this is an access attribute for a public subprogram to be used in
1521 a dispatch table, do not translate its type as it's useless there and the
1522 parameter types might be incomplete types coming from a limited with. */
1530 else
1534 /* If the input is a NULL_EXPR, make a new one. */
1536 {
1540 }
1543 {
1546 /* These are just conversions since representation clauses for
1547 enumeration types are handled in the front-end. */
1548 {
1554 }
1559 /* These just add or subtract the constant 1 since representation
1560 clauses for enumeration types are handled in the front-end. */
1565 {
1567 gnu_expr
1568 = emit_check
1570 gnu_expr,
1571 attribute == Attr_Pred
1575 }
1577 gnu_result
1585 /* Conversions don't change addresses but can cause us to miss the
1586 COMPONENT_REF case below, so strip them off. */
1590 /* If we are taking 'Address of an unconstrained object, this is the
1591 pointer to the underlying array. */
1595 /* If we are building a static dispatch table, we have to honor
1596 TARGET_VTABLE_USES_DESCRIPTORS if we want to be compatible
1597 with the C++ ABI. We do it in the non-static case as well,
1598 see gnat_to_gnu_entity, case E_Access_Subprogram_Type. */
1601 {
1603 /* Descriptors can only be built here for top-level functions. */
1611 /* If we're not going to build the descriptor, we have to retrieve
1612 the one which will be built by the linker (or by the compiler
1613 later if a static chain is requested). */
1615 {
1618 gnu_result);
1620 }
1627 {
1629 {
1633 }
1634 else
1640 elt--;
1641 }
1645 }
1647 /* ... fall through ... */
1653 gnu_result
1660 /* For 'Code_Address, find an inner ADDR_EXPR and mark it so that we
1661 don't try to build a trampoline. */
1663 {
1668 }
1670 /* For 'Access, issue an error message if the prefix is a C++ method
1671 since it can use a special calling convention on some platforms,
1672 which cannot be propagated to the access type. */
1677 gnat_node);
1679 /* For other address attributes applied to a nested function,
1680 find an inner ADDR_EXPR and annotate it so that we can issue
1681 a useful warning with -Wtrampolines. */
1683 {
1688 {
1691 /* Check that we're not violating the No_Implicit_Dynamic_Code
1692 restriction. Be conservative if we don't know anything
1693 about the trampoline strategy for the target. */
1695 }
1696 }
1700 {
1702 tree gnu_obj_type;
1706 /* If this is fat pointer, the object must have been allocated with the
1707 template in front of the array. So compute the template address; do
1708 it by converting to a thin pointer. */
1710 gnu_ptr
1712 (TYPE_OBJECT_RECORD_TYPE
1714 gnu_ptr);
1718 /* If this is a thin pointer, the object must have been allocated with
1719 the template in front of the array. So compute the template address
1720 and return it. */
1722 gnu_ptr
1724 gnu_ptr,
1726 byte_position
1727 (DECL_CHAIN
1731 }
1740 /* Remove NOPs and conversions between original and packable version
1741 from GNU_EXPR, and conversions from GNU_PREFIX. We use GNU_EXPR
1742 to see if a COMPONENT_REF was involved. */
1747 == RECORD_TYPE
1756 /* Replace an unconstrained array type with the type of the underlying
1757 array. We can't do this with a call to maybe_unconstrained_array
1758 since we may have a TYPE_DECL. For 'Max_Size_In_Storage_Elements,
1759 use the record type that will be used to allocate the object and its
1760 template. */
1762 {
1766 }
1768 /* If we're looking for the size of a field, return the field size. */
1772 /* Otherwise, if the prefix is an object, or if we are looking for
1773 'Object_Size or 'Max_Size_In_Storage_Elements, the result is the
1774 GCC size of the type. We make an exception for padded objects,
1775 as we do not take into account alignment promotions for the size.
1776 This is in keeping with the object case of gnat_to_gnu_entity. */
1782 {
1783 /* If this is a dereference and we have a special dynamic constrained
1784 subtype on the prefix, use it to compute the size; otherwise, use
1785 the designated subtype. */
1787 {
1788 Node_Id gnat_actual_subtype
1790 tree gnu_ptr_type
1795 {
1796 tree gnu_actual_obj_type
1798 gnu_type
1800 gnu_actual_obj_type,
1803 }
1804 }
1807 }
1809 /* Otherwise, the result is the RM size of the type. */
1810 else
1813 /* Deal with a self-referential size by returning the maximum size for
1814 a type and by qualifying the size with the object otherwise. */
1816 {
1819 else
1821 }
1823 /* If the type contains a template, subtract its size. */
1829 /* For 'Max_Size_In_Storage_Elements, adjust the unit. */
1837 {
1850 else
1851 {
1856 /* If the default alignment of "double" or larger scalar types is
1857 specifically capped and there is an alignment clause neither
1858 on the type nor on the prefix itself, return the cap. */
1860 is_capped_double
1863 is_capped_double
1865 else
1875 else
1877 }
1880 }
1889 {
1896 else
1897 gnu_result
1898 = build_binary_op
1900 build_binary_op
1912 }
1914 /* ... fall through ... */
1917 {
1925 /* Make sure any implicit dereference gets done. */
1929 /* We treat unconstrained array In parameters specially. We also note
1930 whether we are dereferencing a pointer to unconstrained array. */
1933 {
1935 /* This is the direct case. */
1941 /* This is the indirect case. Note that we need to be sure that
1942 the access value cannot be null as we'll hoist the load. */
1945 {
1948 }
1949 else
1955 }
1957 /* If the prefix is the view conversion of a constrained array to an
1958 unconstrained form, we retrieve the constrained array because we
1959 might not be able to substitute the PLACEHOLDER_EXPR coming from
1960 the conversion. This can occur with the 'Old attribute applied
1961 to a parameter with an unconstrained type, which gets rewritten
1962 into a constrained local variable very late in the game. */
1965 && !CONTAINS_PLACEHOLDER_P
1968 else
1975 {
1977 tree gnu_type_temp;
1983 ;
1986 }
1993 /* When not optimizing, look up the slot associated with the parameter
1994 and the dimension in the cache and create a new one on failure. */
1996 {
2002 {
2007 }
2008 }
2010 /* Return the cached expression or build a new one. */
2012 {
2014 {
2017 }
2019 gnu_result
2021 }
2024 {
2026 {
2029 }
2031 gnu_result
2033 }
2036 {
2038 {
2041 }
2042 else
2043 {
2044 /* We used to compute the length as max (hb - lb + 1, 0),
2045 which could overflow for some cases of empty arrays, e.g.
2046 when lb == index_type'first. We now compute the length as
2047 (hb >= lb) ? hb - lb + 1 : 0, which would only overflow in
2048 much rarer cases, for extremely large arrays we expect
2049 never to encounter in practice. In addition, the former
2050 computation required the use of potentially constraining
2051 signed arithmetic while the latter doesn't. Note that
2052 the comparison must be done in the original index type,
2053 to avoid any overflow during the conversion. */
2058 gnu_result
2061 comp_type,
2065 gnu_result
2068 boolean_type_node,
2070 gnu_result,
2072 }
2073 }
2075 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2076 handling. Note that these attributes could not have been used on
2077 an unconstrained array type. */
2080 /* Cache the expression we have just computed. Since we want to do it
2081 at run time, we force the use of a SAVE_EXPR and let the gimplifier
2082 create the temporary in the outermost binding level. We will make
2083 sure in Subprogram_Body_to_gnu that it is evaluated on all possible
2084 paths by forcing its evaluation on entry of the function. */
2086 {
2087 gnu_result
2090 {
2106 }
2107 }
2109 /* Otherwise, evaluate it each time it is referenced. */
2110 else
2112 {
2115 /* If we are dereferencing a pointer to unconstrained array, we
2116 need to capture the value because the pointed-to bounds may
2117 subsequently be released. */
2119 gnu_result
2125 /* Set the source location onto the predicate of the condition
2126 but not if the expression is cached to avoid messing up the
2127 debug info. */
2131 gnat_node);
2136 }
2139 }
2146 {
2147 HOST_WIDE_INT bitsize;
2148 HOST_WIDE_INT bitpos;
2149 tree gnu_offset;
2150 tree gnu_field_bitpos;
2151 tree gnu_field_offset;
2152 tree gnu_inner;
2160 /* We can have 'Bit on any object, but if it isn't a COMPONENT_REF,
2161 the result is 0. Don't allow 'Bit on a bare component, though. */
2165 {
2168 }
2170 else
2179 {
2187 {
2188 gnu_field_bitpos
2191 gnu_field_offset
2194 }
2195 }
2197 {
2200 }
2201 else
2202 {
2205 }
2208 {
2222 /* ??? Avoid a large unsigned result that will overflow when
2223 converted to the signed universal_integer. */
2226 else
2227 gnu_result
2234 }
2236 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2237 handling. */
2240 }
2244 {
2252 }
2278 /* Note this size cannot be self-referential. */
2288 /* What we want is the offset of the ARRAY field in the record
2289 that the thin pointer designates. */
2297 /* This is just a zero cast to the pointer type for our prefix and
2298 dereferenced. */
2300 gnu_result
2303 integer_zero_node));
2308 {
2315 {
2320 ;
2321 }
2329 && (DECL_BY_COMPONENT_PTR_P
2333 }
2337 /* This abort means that we have an unimplemented attribute. */
2339 }
2341 /* If this is an attribute where the prefix was unused, force a use of it if
2342 it has a side-effect. But don't do it if the prefix is just an entity
2343 name. However, if an access check is needed, we must do it. See second
2344 example in AARM 11.6(5.e). */
2348 gnu_result
2353 }
2354 \f
2355 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Case_Statement,
2356 to a GCC tree, which is returned. */
2358 static tree
2360 {
2362 Node_Id gnat_when;
2363 location_t end_locus;
2369 /* The range of values in a case statement is determined by the rules in
2370 RM 5.4(7-9). In almost all cases, this range is represented by the Etype
2371 of the expression. One exception arises in the case of a simple name that
2372 is parenthesized. This still has the Etype of the name, but since it is
2373 not a name, para 7 does not apply, and we need to go to the base type.
2374 This is the only case where parenthesization affects the dynamic
2375 semantics (i.e. the range of possible values at run time that is covered
2376 by the others alternative).
2378 Another exception is if the subtype of the expression is non-static. In
2379 that case, we also have to use the base type. */
2385 /* We build a SWITCH_EXPR that contains the code with interspersed
2386 CASE_LABEL_EXPRs for each label. */
2395 {
2397 Node_Id gnat_choice;
2399 /* First compile all the different case choices for the current WHEN
2400 alternative. */
2403 {
2407 {
2422 /* This represents either a subtype range or a static value of
2423 some kind; Ekind says which. */
2425 {
2431 }
2433 /* ... fall through ... */
2445 }
2447 /* If the case value is a subtype that raises Constraint_Error at
2448 run time because of a wrong bound, then gnu_low or gnu_high is
2449 not translated into an INTEGER_CST. In such a case, we need
2450 to ensure that the when statement is not added in the tree,
2451 otherwise it will crash the gimplifier. */
2454 {
2458 gnat_choice);
2460 }
2461 }
2463 /* This construct doesn't define a scope so we shouldn't push a binding
2464 level around the statement list. Except that we have always done so
2465 historically and this makes it possible to reduce stack usage. As a
2466 compromise, we keep doing it for case statements, for which this has
2467 never been problematic, but not for case expressions in Ada 2012. */
2469 {
2470 const bool is_case_expression
2472 tree group
2477 {
2482 }
2483 }
2484 }
2486 /* Now emit a definition of the label the cases branch to, if any. */
2493 }
2494 \f
2495 /* Find out whether VAR is an iteration variable of an enclosing loop in the
2496 current function. If so, push a range_check_info structure onto the stack
2497 of this enclosing loop and return it. Otherwise, return NULL. */
2501 {
2518 i--)
2523 {
2527 }
2530 }
2532 /* Return true if VAL (of type TYPE) can equal the minimum value if MAX is
2533 false, or the maximum value if MAX is true, of TYPE. */
2535 static bool
2537 {
2544 val = (max
2553 else
2555 }
2557 /* Return true if VAL (of type TYPE) can equal the minimum value of TYPE.
2558 If REVERSE is true, minimum value is taken as maximum value. */
2562 {
2564 }
2566 /* Return true if VAL (of type TYPE) can equal the maximum value of TYPE.
2567 If REVERSE is true, maximum value is taken as minimum value. */
2571 {
2573 }
2575 /* Return true if VAL1 can be lower than VAL2. */
2577 static bool
2579 {
2593 }
2595 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Loop_Statement,
2596 to a GCC tree, which is returned. */
2598 static tree
2600 {
2607 tree gnu_result;
2609 /* Push the loop_info structure associated with the LOOP_STMT. */
2612 /* Set location information for statement and end label. */
2618 /* Save the statement for later reuse. */
2621 /* Set the condition under which the loop must keep going.
2622 For the case "LOOP .... END LOOP;" the condition is always true. */
2624 ;
2626 /* For the case "WHILE condition LOOP ..... END LOOP;" it's immediate. */
2631 /* Otherwise we have an iteration scheme and the condition is given by the
2632 bounds of the subtype of the iteration variable. */
2633 else
2634 {
2648 /* We must disable modulo reduction for the iteration variable, if any,
2649 in order for the loop comparison to be effective. */
2651 {
2657 }
2658 else
2659 {
2665 }
2667 /* We use two different strategies to translate the loop, depending on
2668 whether optimization is enabled.
2670 If it is, we generate the canonical loop form expected by the loop
2671 optimizer and the loop vectorizer, which is the do-while form:
2673 ENTRY_COND
2674 loop:
2675 TOP_UPDATE
2676 BODY
2677 BOTTOM_COND
2678 GOTO loop
2680 This avoids an implicit dependency on loop header copying and makes
2681 it possible to turn BOTTOM_COND into an inequality test.
2683 If optimization is disabled, loop header copying doesn't come into
2684 play and we try to generate the loop form with the fewer conditional
2685 branches. First, the default form, which is:
2687 loop:
2688 TOP_COND
2689 BODY
2690 BOTTOM_UPDATE
2691 GOTO loop
2693 It should catch most loops with constant ending point. Then, if we
2694 cannot, we try to generate the shifted form:
2696 loop:
2697 TOP_COND
2698 TOP_UPDATE
2699 BODY
2700 GOTO loop
2702 which should catch loops with constant starting point. Otherwise, if
2703 we cannot, we generate the fallback form:
2705 ENTRY_COND
2706 loop:
2707 BODY
2708 BOTTOM_COND
2709 BOTTOM_UPDATE
2710 GOTO loop
2712 which works in all cases. */
2715 {
2716 /* We can use the do-while form directly if GNU_FIRST-1 doesn't
2717 overflow. */
2719 ;
2721 /* Otherwise, use the do-while form with the help of a special
2722 induction variable in the unsigned version of the base type
2723 or the unsigned version of the size type, whichever is the
2724 largest, in order to have wrap-around arithmetics for it. */
2725 else
2726 {
2729 gnu_base_type
2731 else
2738 }
2740 gnu_first
2742 gnu_one_node);
2745 }
2746 else
2747 {
2748 /* We can use the default form if GNU_LAST+1 doesn't overflow. */
2750 ;
2752 /* Otherwise, we can use the shifted form if neither GNU_FIRST-1 nor
2753 GNU_LAST-1 does. */
2756 {
2757 gnu_first
2759 gnu_one_node);
2760 gnu_last
2762 gnu_one_node);
2764 }
2766 /* Otherwise, use the fallback form. */
2767 else
2769 }
2771 /* If we use the BOTTOM_COND, we can turn the test into an inequality
2772 test but we may have to add ENTRY_COND to protect the empty loop. */
2774 {
2777 {
2778 gnu_cond_expr
2784 }
2785 }
2787 /* Open a new nesting level that will surround the loop to declare the
2788 iteration variable. */
2792 /* If we use the special induction variable, create it and set it to
2793 its initial value. Morever, the regular iteration variable cannot
2794 itself be initialized, lest the initial value wrapped around. */
2796 {
2797 gnu_loop_iv
2801 }
2802 else
2805 /* Declare the iteration variable and set it to its initial value. */
2810 {
2813 }
2816 /* Do all the arithmetics in the base type. */
2819 /* Set either the top or bottom exit condition. */
2823 gnu_last);
2824 else
2827 gnu_last);
2829 /* Set either the top or bottom update statement and give it the source
2830 location of the iteration for better coverage info. */
2832 {
2833 gnu_stmt
2840 gnu_stmt
2842 gnu_loop_iv);
2846 }
2847 else
2848 {
2849 gnu_stmt
2855 }
2856 }
2858 /* If the loop was named, have the name point to this loop. In this case,
2859 the association is not a DECL node, but the end label of the loop. */
2863 /* Make the loop body into its own block, so any allocated storage will be
2864 released every iteration. This is needed for stack allocation. */
2869 /* If we have an iteration scheme, then we are in a statement group. Add
2870 the LOOP_STMT to it, finish it and make it the "loop". */
2872 {
2877 /* First, if we have computed a small number of invariant conditions for
2878 range checks applied to the iteration variable, then initialize these
2879 conditions in front of the loop. Otherwise, leave them set to true.
2881 ??? The heuristics need to be improved, by taking into account the
2882 following datapoints:
2883 - loop unswitching is disabled for big loops. The cap is the
2884 parameter PARAM_MAX_UNSWITCH_INSNS (50).
2885 - loop unswitching can only be applied a small number of times
2886 to a given loop. The cap is PARAM_MAX_UNSWITCH_LEVEL (3).
2887 - the front-end quickly generates useless or redundant checks
2888 that can be entirely optimized away in the end. */
2892 i++)
2893 {
2894 tree low_ok
2901 tree high_ok
2908 tree range_ok
2916 }
2921 }
2923 /* If we have an outer COND_EXPR, that's our result and this loop is its
2924 "true" statement. Otherwise, the result is the LOOP_STMT. */
2926 {
2930 }
2931 else
2937 }
2938 \f
2939 /* Emit statements to establish __gnat_handle_vms_condition as a VMS condition
2940 handler for the current function. */
2942 /* This is implemented by issuing a call to the appropriate VMS specific
2943 builtin. To avoid having VMS specific sections in the global gigi decls
2944 array, we maintain the decls of interest here. We can't declare them
2945 inside the function because we must mark them never to be GC'd, which we
2946 can only do at the global level. */
2951 static void
2953 {
2954 tree establish_stmt;
2956 /* Elaborate the required decls on the first call. Check on the decl for
2957 the gnat condition handler to decide, as this is one we create so we are
2958 sure that it will be non null on subsequent calls. The builtin decl is
2959 looked up so remains null on targets where it is not implemented yet. */
2961 {
2962 vms_builtin_establish_handler_decl
2963 = builtin_decl_for
2966 gnat_vms_condition_handler_decl
2968 NULL_TREE,
2970 ptr_void_type_node,
2971 ptr_void_type_node,
2972 NULL_TREE),
2974 Empty);
2976 /* ??? DECL_CONTEXT shouldn't have been set because of DECL_EXTERNAL. */
2978 }
2980 /* Do nothing if the establish builtin is not available, which might happen
2981 on targets where the facility is not implemented. */
2985 establish_stmt
2987 build_unary_op
2989 gnat_vms_condition_handler_decl));
2992 }
2994 /* This page implements a form of Named Return Value optimization modelled
2995 on the C++ optimization of the same name. The main difference is that
2996 we disregard any semantical considerations when applying it here, the
2997 counterpart being that we don't try to apply it to semantically loaded
2998 return types, i.e. types with the TYPE_BY_REFERENCE_P flag set.
3000 We consider a function body of the following GENERIC form:
3002 return_type R1;
3003 [...]
3004 RETURN_EXPR [<retval> = ...]
3005 [...]
3006 RETURN_EXPR [<retval> = R1]
3007 [...]
3008 return_type Ri;
3009 [...]
3010 RETURN_EXPR [<retval> = ...]
3011 [...]
3012 RETURN_EXPR [<retval> = Ri]
3013 [...]
3015 and we try to fulfill a simple criterion that would make it possible to
3016 replace one or several Ri variables with the RESULT_DECL of the function.
3018 The first observation is that RETURN_EXPRs that don't directly reference
3019 any of the Ri variables on the RHS of their assignment are transparent wrt
3020 the optimization. This is because the Ri variables aren't addressable so
3021 any transformation applied to them doesn't affect the RHS; moreover, the
3022 assignment writes the full <retval> object so existing values are entirely
3023 discarded.
3025 This property can be extended to some forms of RETURN_EXPRs that reference
3026 the Ri variables, for example CONSTRUCTORs, but isn't true in the general
3027 case, in particular when function calls are involved.
3029 Therefore the algorithm is as follows:
3031 1. Collect the list of candidates for a Named Return Value (Ri variables
3032 on the RHS of assignments of RETURN_EXPRs) as well as the list of the
3033 other expressions on the RHS of such assignments.
3035 2. Prune the members of the first list (candidates) that are referenced
3036 by a member of the second list (expressions).
3038 3. Extract a set of candidates with non-overlapping live ranges from the
3039 first list. These are the Named Return Values.
3041 4. Adjust the relevant RETURN_EXPRs and replace the occurrences of the
3042 Named Return Values in the function with the RESULT_DECL.
3044 If the function returns an unconstrained type, things are a bit different
3045 because the anonymous return object is allocated on the secondary stack
3046 and RESULT_DECL is only a pointer to it. Each return object can be of a
3047 different size and is allocated separately so we need not care about the
3048 aforementioned overlapping issues. Therefore, we don't collect the other
3049 expressions and skip step #2 in the algorithm. */
3051 struct nrv_data
3052 {
3053 bitmap nrv;
3054 tree result;
3055 Node_Id gnat_ret;
3057 };
3059 /* Return true if T is a Named Return Value. */
3063 {
3065 }
3067 /* Helper function for walk_tree, used by finalize_nrv below. */
3069 static tree
3071 {
3075 /* No need to walk into types or decls. */
3083 }
3085 /* Prune Named Return Values in BLOCK and return true if there is still a
3086 Named Return Value in BLOCK or one of its sub-blocks. */
3088 static bool
3090 {
3092 tree t;
3094 /* First recurse on the sub-blocks. */
3098 /* Then make sure to keep at most one NRV per block. */
3101 {
3104 else
3106 }
3109 }
3111 /* Helper function for walk_tree, used by finalize_nrv below. */
3113 static tree
3115 {
3119 /* No need to walk into types. */
3123 /* Change RETURN_EXPRs of NRVs to just refer to the RESULT_DECL; this is a
3124 nop, but differs from using NULL_TREE in that it indicates that we care
3125 about the value of the RESULT_DECL. */
3128 {
3131 /* If this is the temporary created for a return value with variable
3132 size in Call_to_gnu, we replace the RHS with the init expression. */
3137 {
3140 }
3141 else
3144 /* Strip useless conversions around the return value. */
3149 {
3152 else
3154 }
3155 }
3157 /* Replace the DECL_EXPR of NRVs with an initialization of the RESULT_DECL,
3158 if needed. */
3161 {
3165 {
3170 }
3171 else
3175 /* Identify the NRV to the RESULT_DECL for debugging purposes. */
3178 /* ??? Kludge to avoid an assertion failure during inlining. */
3181 }
3183 /* And replace all uses of NRVs with the RESULT_DECL. */
3187 /* Avoid walking into the same tree more than once. Unfortunately, we
3188 can't just use walk_tree_without_duplicates because it would only
3189 call us for the first occurrence of NRVs in the function body. */
3194 }
3196 /* Likewise, but used when the function returns an unconstrained type. */
3198 static tree
3200 {
3204 /* No need to walk into types. */
3208 /* We need to see the DECL_EXPR of NRVs before any other references so we
3209 walk the body of BIND_EXPR before walking its variables. */
3213 /* Change RETURN_EXPRs of NRVs to assign to the RESULT_DECL only the final
3214 return value built by the allocator instead of the whole construct. */
3217 {
3220 /* This is the construct returned by the allocator. */
3223 {
3225 ret_val
3228 else
3230 }
3232 /* Strip useless conversions around the return value. */
3237 /* Strip unpadding around the return value. */
3242 /* Assign the new return value to the RESULT_DECL. */
3246 }
3248 /* Adjust the DECL_EXPR of NRVs to call the allocator and save the result
3249 into a new variable. */
3252 {
3259 /* Create an artificial context to build the allocation. */
3264 /* This will return a COMPOUND_EXPR with the allocation in the first
3265 arm and the final return value in the second arm. */
3272 /* The new variable is built as a reference to the allocated space. */
3273 new_var
3279 {
3280 /* The new initial value is a COMPOUND_EXPR with the allocation in
3281 the first arm and the value of P_ARRAY in the second arm. */
3287 /* Build a modified CONSTRUCTOR that references NEW_VAR. */
3295 }
3296 else
3297 {
3298 /* The new initial value is just the allocation. */
3301 }
3305 /* Destroy the artificial context and insert the new statements. */
3310 /* Chain NEW_VAR immediately after VAR and ignore the latter. */
3315 /* Save the new return value and the dereference of NEW_VAR. */
3319 /* ??? Kludge to avoid messing up during inlining. */
3321 }
3323 /* And replace all uses of NRVs with the dereference of NEW_VAR. */
3327 /* Avoid walking into the same tree more than once. Unfortunately, we
3328 can't just use walk_tree_without_duplicates because it would only
3329 call us for the first occurrence of NRVs in the function body. */
3334 }
3336 /* Finalize the Named Return Value optimization for FNDECL. The NRV bitmap
3337 contains the candidates for Named Return Value and OTHER is a list of
3338 the other return values. GNAT_RET is a representative return node. */
3340 static void
3342 {
3345 walk_tree_fn func;
3347 tree iter;
3349 /* We shouldn't be applying the optimization to return types that we aren't
3350 allowed to manipulate freely. */
3353 /* Prune the candidates that are referenced by other return values. */
3362 /* Prune also the candidates that are referenced by nested functions. */
3370 /* Extract a set of NRVs with non-overlapping live ranges. */
3374 /* Adjust the relevant RETURN_EXPRs and replace the occurrences of NRVs. */
3381 else
3385 }
3387 /* Return true if RET_VAL can be used as a Named Return Value for the
3388 anonymous return object RET_OBJ. */
3390 static bool
3392 {
3412 }
3414 /* Build a RETURN_EXPR. If RET_VAL is non-null, build a RETURN_EXPR around
3415 the assignment of RET_VAL to RET_OBJ. Otherwise build a bare RETURN_EXPR
3416 around RESULT_OBJ, which may be null in this case. */
3418 static tree
3420 {
3421 tree result_expr;
3424 {
3425 /* The gimplifier explicitly enforces the following invariant:
3427 RETURN_EXPR
3428 |
3429 MODIFY_EXPR
3430 / \
3431 / \
3432 RET_OBJ ...
3434 As a consequence, type consistency dictates that we use the type
3435 of the RET_OBJ as the operation type. */
3438 /* Convert the right operand to the operation type. Note that it's the
3439 same transformation as in the MODIFY_EXPR case of build_binary_op,
3440 with the assumption that the type cannot involve a placeholder. */
3446 /* If the function returns an aggregate type, find out whether this is
3447 a candidate for Named Return Value. If so, record it. Otherwise,
3448 if this is an expression of some kind, record it elsewhere. */
3454 {
3455 /* Recognize the temporary created for a return value with variable
3456 size in Call_to_gnu. We want to eliminate it if possible. */
3463 /* Strip useless conversions around the return value. */
3467 /* Now apply the test to the return value. */
3469 {
3473 }
3475 /* Note that we need not care about CONSTRUCTORs here, as they are
3476 totally transparent given the read-compose-write semantics of
3477 assignments from CONSTRUCTORs. */
3480 }
3481 }
3482 else
3486 }
3488 /* Build a stub for the subprogram specified by the GCC tree GNU_SUBPROG
3489 and the GNAT node GNAT_SUBPROG. */
3491 static void
3493 {
3501 /* Initialize the information structure for the function. */
3510 /* Loop over the parameters of the stub and translate any of them
3511 passed by descriptor into a by reference one. */
3514 gnu_stub_param;
3517 {
3519 {
3521 gnu_param
3523 gnu_stub_param,
3525 gnat_subprog);
3526 }
3527 else
3531 }
3533 /* Invoke the internal subprogram. */
3535 gnu_subprog);
3539 /* Propagate the return value, if any. */
3542 else
3544 gnu_subprog_call));
3549 }
3550 \f
3551 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Subprogram_Body. We
3552 don't return anything. */
3554 static void
3556 {
3557 /* Defining identifier of a parameter to the subprogram. */
3558 Entity_Id gnat_param;
3559 /* The defining identifier for the subprogram body. Note that if a
3560 specification has appeared before for this body, then the identifier
3561 occurring in that specification will also be a defining identifier and all
3562 the calls to this subprogram will point to that specification. */
3563 Entity_Id gnat_subprog_id
3566 /* The FUNCTION_DECL node corresponding to the subprogram spec. */
3567 tree gnu_subprog_decl;
3568 /* Its RESULT_DECL node. */
3569 tree gnu_result_decl;
3570 /* Its FUNCTION_TYPE node. */
3571 tree gnu_subprog_type;
3572 /* The TYPE_CI_CO_LIST of its FUNCTION_TYPE node, if any. */
3573 tree gnu_cico_list;
3574 /* The entry in the CI_CO_LIST that represents a function return, if any. */
3576 tree gnu_result;
3580 /* If this is a generic object or if it has been eliminated,
3581 ignore it. */
3587 /* If this subprogram acts as its own spec, define it. Otherwise, just get
3588 the already-elaborated tree node. However, if this subprogram had its
3589 elaboration deferred, we will already have made a tree node for it. So
3590 treat it as not being defined in that case. Such a subprogram cannot
3591 have an address clause or a freeze node, so this test is safe, though it
3592 does disable some otherwise-useful error checking. */
3593 gnu_subprog_decl
3603 /* If the function returns by invisible reference, make it explicit in the
3604 function body. See gnat_to_gnu_entity, E_Subprogram_Type case.
3605 Handle the explicit case here and the copy-in/copy-out case below. */
3607 {
3611 }
3613 /* Set the line number in the decl to correspond to that of the body so that
3614 the line number notes are written correctly. */
3617 /* Initialize the information structure for the function. */
3625 /* If there are In Out or Out parameters, we need to ensure that the return
3626 statement properly copies them out. We do this by making a new block and
3627 converting any return into a goto to a label at the end of the block. */
3629 {
3638 /* If this is a function with In Out or Out parameters, we also need a
3639 variable for the return value to be placed. */
3641 {
3642 tree gnu_return_type
3645 /* If the function returns by invisible reference, make it
3646 explicit in the function body. See gnat_to_gnu_entity,
3647 E_Subprogram_Type case. */
3651 gnu_return_var
3656 }
3660 /* See whether there are parameters for which we don't have a GCC tree
3661 yet. These must be Out parameters. Make a VAR_DECL for them and
3662 put it into TYPE_CI_CO_LIST, which must contain an empty entry too.
3663 We can match up the entries because TYPE_CI_CO_LIST is in the order
3664 of the parameters. */
3669 {
3671 tree gnu_decl;
3673 /* Skip any entries that have been already filled in; they must
3674 correspond to In Out parameters. */
3678 /* Do any needed dereferences for by-ref objects. */
3684 /* Do any needed references for padded types. */
3687 }
3688 }
3689 else
3692 /* Get a tree corresponding to the code for the subprogram. */
3696 /* On VMS, establish our condition handler to possibly turn a condition into
3697 the corresponding exception if the subprogram has a foreign convention or
3698 is exported.
3700 To ensure proper execution of local finalizations on condition instances,
3701 we must turn a condition into the corresponding exception even if there
3702 is no applicable Ada handler, and need at least one condition handler per
3703 possible call chain involving GNAT code. OTOH, establishing the handler
3704 has a cost so we want to minimize the number of subprograms into which
3705 this happens. The foreign or exported condition is expected to satisfy
3706 all the constraints. */
3714 /* Generate the code of the subprogram itself. A return statement will be
3715 present and any Out parameters will be handled there. */
3720 /* If we populated the parameter attributes cache, we need to make sure that
3721 the cached expressions are evaluated on all the possible paths leading to
3722 their uses. So we force their evaluation on entry of the function. */
3725 {
3732 {
3739 }
3745 }
3747 /* If we are dealing with a return from an Ada procedure with parameters
3748 passed by copy-in/copy-out, we need to return a record containing the
3749 final values of these parameters. If the list contains only one entry,
3750 return just that entry though.
3752 For a full description of the copy-in/copy-out parameter mechanism, see
3753 the part of the gnat_to_gnu_entity routine dealing with the translation
3754 of subprograms.
3756 We need to make a block that contains the definition of that label and
3757 the copying of the return value. It first contains the function, then
3758 the label and copy statement. */
3760 {
3761 tree gnu_retval;
3771 else
3773 gnu_cico_list);
3779 }
3783 /* Attempt setting the end_locus of our GCC body tree, typically a
3784 BIND_EXPR or STATEMENT_LIST, then the end_locus of our GCC subprogram
3785 declaration tree. */
3789 /* On SEH targets, install an exception handler around the main entry
3790 point to catch unhandled exceptions. */
3793 {
3794 tree t;
3795 tree etype;
3807 }
3811 /* Finally annotate the parameters and disconnect the trees for parameters
3812 that we have turned into variables since they are now unusable. */
3816 {
3825 }
3827 /* Disconnect the variable created for the return value. */
3831 /* If the function returns an aggregate type and we have candidates for
3832 a Named Return Value, finalize the optimization. */
3834 {
3841 }
3845 /* If there is a stub associated with the function, build it now. */
3848 }
3849 \f
3850 /* Return true if GNAT_NODE requires atomic synchronization. */
3852 static bool
3854 {
3856 Node_Kind kind;
3859 /* First, scan the node to find the Atomic_Sync_Required flag. */
3862 {
3865 }
3868 {
3880 }
3882 /* Then, scan the parent to find out cases where the flag is irrelevant. */
3885 {
3888 /* Do not mess up machine code insertions. */
3894 /* Do not generate a function call as a renamed object. */
3899 }
3902 }
3903 \f
3904 /* Create a temporary variable with PREFIX and TYPE, and return it. */
3906 static tree
3908 {
3916 }
3918 /* Create a temporary variable with PREFIX and initialize it with GNU_INIT.
3919 Put the initialization statement into GNU_INIT_STMT and annotate it with
3920 the SLOC of GNAT_NODE. Return the temporary variable. */
3922 static tree
3924 Node_Id gnat_node)
3925 {
3932 }
3934 /* Subroutine of gnat_to_gnu to translate gnat_node, either an N_Function_Call
3935 or an N_Procedure_Call_Statement, to a GCC tree, which is returned.
3936 GNU_RESULT_TYPE_P is a pointer to where we should place the result type.
3937 If GNU_TARGET is non-null, this must be a function call on the RHS of a
3938 N_Assignment_Statement and the result is to be placed into that object.
3939 If, in addition, ATOMIC_SYNC is true, then the assignment to GNU_TARGET
3940 requires atomic synchronization. */
3942 static tree
3945 {
3948 /* The GCC node corresponding to the GNAT subprogram name. This can either
3949 be a FUNCTION_DECL node if we are dealing with a standard subprogram call,
3950 or an indirect reference expression (an INDIRECT_REF node) pointing to a
3951 subprogram. */
3953 /* The FUNCTION_TYPE node giving the GCC type of the subprogram. */
3955 /* The return type of the FUNCTION_TYPE. */
3966 Entity_Id gnat_formal;
3967 Node_Id gnat_actual;
3971 /* If we are calling a stubbed function, raise Program_Error, but Elaborate
3972 all our args first. */
3974 {
3984 {
3987 }
3990 }
3992 /* The only way we can be making a call via an access type is if Name is an
3993 explicit dereference. In that case, get the list of formal args from the
3994 type the access type is pointing to. Otherwise, get the formals from the
3995 entity being called. */
3999 /* Assume here that this must be 'Elab_Body or 'Elab_Spec. */
4001 else
4004 /* The lifetime of the temporaries created for the call ends right after the
4005 return value is copied, so we can give them the scope of the elaboration
4006 routine at top level. */
4008 {
4011 }
4013 /* First, create the temporary for the return value when:
4015 1. There is no target and the function has copy-in/copy-out parameters,
4016 because we need to preserve the return value before copying back the
4017 parameters.
4019 2. There is no target and this is not an object declaration, and the
4020 return type has variable size, because in these cases the gimplifier
4021 cannot create the temporary.
4023 3. There is a target and it is a slice or an array with fixed size,
4024 and the return type has variable size, because the gimplifier
4025 doesn't handle these cases.
4027 This must be done before we push a binding level around the call, since
4028 we will pop it before copying the return value. */
4031 || (!gnu_target
4034 || (gnu_target
4042 /* Create the list of the actual parameters as GCC expects it, namely a
4043 chain of TREE_LIST nodes in which the TREE_VALUE field of each node
4044 is an expression and the TREE_PURPOSE field is null. But skip Out
4045 parameters not passed by reference and that need not be copied in. */
4050 {
4054 const bool is_true_formal_parm
4056 const bool is_by_ref_formal_parm
4057 = is_true_formal_parm
4061 /* In the Out or In Out case, we must suppress conversions that yield
4062 an lvalue but can nevertheless cause the creation of a temporary,
4063 because we need the real object in this case, either to pass its
4064 address if it's passed by reference or as target of the back copy
4065 done after the call if it uses the copy-in/copy-out mechanism.
4066 We do it in the In case too, except for an unchecked conversion
4067 because it alone can cause the actual to be misaligned and the
4068 addressability test is applied to the real object. */
4069 const bool suppress_type_conversion
4074 Node_Id gnat_name = suppress_type_conversion
4077 tree gnu_actual;
4079 /* If it's possible we may need to use this expression twice, make sure
4080 that any side-effects are handled via SAVE_EXPRs; likewise if we need
4081 to force side-effects before the call.
4082 ??? This is more conservative than we need since we don't need to do
4083 this for pass-by-ref with no conversion. */
4087 /* If we are passing a non-addressable parameter by reference, pass the
4088 address of a copy. In the Out or In Out case, set up to copy back
4089 out after the call. */
4093 {
4097 /* Do not issue warnings for CONSTRUCTORs since this is not a copy
4098 but sort of an instantiation for them. */
4100 ;
4102 /* If the type is passed by reference, a copy is not allowed. */
4105 gnat_actual);
4107 /* For users of Starlet we issue a warning because the interface
4108 apparently assumes that by-ref parameters outlive the procedure
4109 invocation. The code still will not work as intended, but we
4110 cannot do much better since low-level parts of the back-end
4111 would allocate temporaries at will because of the misalignment
4112 if we did not do so here. */
4114 {
4115 post_error
4117 post_error_ne
4121 gnat_formal);
4122 }
4124 /* If the actual type of the object is already the nominal type,
4125 we have nothing to do, except if the size is self-referential
4126 in which case we'll remove the unpadding below. */
4129 ;
4131 /* Otherwise remove the unpadding from all the objects. */
4133 && TYPE_IS_PADDING_P
4137 /* Otherwise convert to the nominal type of the object if needed.
4138 There are several cases in which we need to make the temporary
4139 using this type instead of the actual type of the object when
4140 they are distinct, because the expectations of the callee would
4141 otherwise not be met:
4142 - if it's a justified modular type,
4143 - if the actual type is a smaller form of it,
4144 - if it's a smaller form of the actual type. */
4148 gnu_name_type)))
4154 /* If this is an In Out or Out parameter and we're returning a value,
4155 we need to create a temporary for the return value because we must
4156 preserve it before copying back at the very end. */
4160 /* If we haven't pushed a binding level, push a new one. This will
4161 narrow the lifetime of the temporary we are about to make as much
4162 as possible. The drawback is that we'd need to create a temporary
4163 for the return value, if any (see comment before the loop). So do
4164 it only when this temporary was already created just above. */
4166 {
4170 }
4172 /* Create an explicit temporary holding the copy. */
4173 gnu_temp
4176 /* But initialize it on the fly like for an implicit temporary as
4177 we aren't necessarily having a statement list. */
4179 gnu_temp);
4181 /* Set up to move the copy back to the original if needed. */
4183 {
4184 /* If the original is a COND_EXPR whose first arm isn't meant to
4185 be further used, just deal with the second arm. This is very
4186 likely the conditional expression built for a check. */
4189 && integer_zerop
4193 gnu_stmt
4198 }
4199 }
4201 /* Start from the real object and build the actual. */
4204 /* If this is an atomic access of an In or In Out parameter for which
4205 synchronization is required, build the atomic load. */
4207 && !is_by_ref_formal_parm
4212 /* If this was a procedure call, we may not have removed any padding.
4213 So do it here for the part we will use as an input, if any. */
4216 gnu_actual
4219 /* Put back the conversion we suppressed above in the computation of the
4220 real object. And even if we didn't suppress any conversion there, we
4221 may have suppressed a conversion to the Etype of the actual earlier,
4222 since the parent is a procedure call, so put it back here. */
4225 gnu_actual
4228 else
4229 gnu_actual
4232 /* Make sure that the actual is in range of the formal's type. */
4235 gnu_actual
4238 /* Unless this is an In parameter, we must remove any justified modular
4239 building from GNU_NAME to get an lvalue. */
4244 gnu_name
4247 /* First see if the parameter is passed by reference. */
4249 {
4251 {
4252 /* In Out or Out parameters passed by reference don't use the
4253 copy-in/copy-out mechanism so the address of the real object
4254 must be passed to the function. */
4257 /* If we have a padded type, be sure we've removed padding. */
4260 gnu_actual);
4262 /* If we have the constructed subtype of an aliased object
4263 with an unconstrained nominal subtype, the type of the
4264 actual includes the template, although it is formally
4265 constrained. So we need to convert it back to the real
4266 constructed subtype to retrieve the constrained part
4267 and takes its address. */
4273 gnu_actual);
4274 }
4276 /* There is no need to convert the actual to the formal's type before
4277 taking its address. The only exception is for unconstrained array
4278 types because of the way we build fat pointers. */
4280 {
4281 /* Put back a view conversion for In Out or Out parameters. */
4284 gnu_actual);
4286 }
4288 /* The symmetry of the paths to the type of an entity is broken here
4289 since arguments don't know that they will be passed by ref. */
4292 }
4294 /* Then see if the parameter is an array passed to a foreign convention
4295 subprogram. */
4297 {
4303 {
4306 }
4308 /* Take the address of the object and convert to the proper pointer
4309 type. We'd like to actually compute the address of the beginning
4310 of the array using an ADDR_EXPR of an ARRAY_REF, but there's a
4311 possibility that the ARRAY_REF might return a constant and we'd be
4312 getting the wrong address. Neither approach is exactly correct,
4313 but this is the most likely to work in all cases. */
4315 }
4317 /* Then see if the parameter is passed by descriptor. */
4319 {
4322 /* If this is 'Null_Parameter, pass a zero descriptor. */
4326 gnu_actual
4328 else
4330 fill_vms_descriptor
4333 }
4335 /* Otherwise the parameter is passed by copy. */
4336 else
4337 {
4338 tree gnu_size;
4343 /* If we didn't create a PARM_DECL for the formal, this means that
4344 it is an Out parameter not passed by reference and that need not
4345 be copied in. In this case, the value of the actual need not be
4346 read. However, we still need to make sure that its side-effects
4347 are evaluated before the call, so we evaluate its address. */
4349 {
4351 {
4354 }
4356 }
4360 /* If this is 'Null_Parameter, pass a zero even though we are
4361 dereferencing it. */
4367 gnu_actual
4371 integer_zero_node),
4373 else
4375 }
4378 }
4380 gnu_call
4384 /* If we have created a temporary for the return value, initialize it. */
4386 {
4387 tree gnu_stmt
4392 }
4394 /* If this is a subprogram with copy-in/copy-out parameters, we need to
4395 unpack the valued returned from the function into the In Out or Out
4396 parameters. We deal with the function return (if this is an Ada
4397 function) below. */
4399 {
4400 /* List of FIELD_DECLs associated with the PARM_DECLs of the copy-in/
4401 copy-out parameters. */
4405 /* The call sequence must contain one and only one call, even though the
4406 function is pure. Save the result into a temporary if needed. */
4408 {
4410 {
4411 tree gnu_stmt;
4412 /* If we haven't pushed a binding level, push a new one. This
4413 will narrow the lifetime of the temporary we are about to
4414 make as much as possible. */
4416 {
4420 }
4421 gnu_call
4424 }
4427 }
4429 /* The first entry is for the actual return value if this is a
4430 function, so skip it. */
4436 else
4443 /* If we are dealing with a copy-in/copy-out parameter, we must
4444 retrieve its value from the record returned in the call. */
4450 || (DECL_BY_DESCRIPTOR_P
4453 {
4454 /* Get the value to assign to this Out or In Out parameter. It is
4455 either the result of the function if there is only a single such
4456 parameter or the appropriate field from the record returned. */
4457 tree gnu_result
4459 ? gnu_call
4463 /* If the actual is a conversion, get the inner expression, which
4464 will be the real destination, and convert the result to the
4465 type of the actual parameter. */
4466 tree gnu_actual
4469 /* If the result is a padded type, remove the padding. */
4471 gnu_result
4473 gnu_result);
4475 /* If the actual is a type conversion, the real target object is
4476 denoted by the inner Expression and we need to convert the
4477 result to the associated type.
4478 We also need to convert our gnu assignment target to this type
4479 if the corresponding GNU_NAME was constructed from the GNAT
4480 conversion node and not from the inner Expression. */
4482 {
4483 gnu_result
4484 = convert_with_check
4492 }
4494 /* Unchecked conversions as actuals for Out parameters are not
4495 allowed in user code because they are not variables, but do
4496 occur in front-end expansions. The associated GNU_NAME is
4497 always obtained from the inner expression in such cases. */
4500 gnu_result,
4502 else
4503 {
4505 gnu_result
4507 gnat_actual);
4512 }
4516 else
4523 }
4524 }
4526 /* If this is a function call, the result is the call expression unless a
4527 target is specified, in which case we copy the result into the target
4528 and return the assignment statement. */
4530 {
4531 /* If this is a function with copy-in/copy-out parameters, extract the
4532 return value from it and update the return type. */
4534 {
4539 }
4541 /* If the function returns an unconstrained array or by direct reference,
4542 we have to dereference the pointer. */
4548 {
4552 /* If range check is needed, emit code to generate it. */
4554 gnu_call
4556 gnat_parent);
4558 /* ??? If the return type has variable size, then force the return
4559 slot optimization as we would not be able to create a temporary.
4560 Likewise if it was unconstrained as we would copy too much data.
4561 That's what has been done historically. */
4564 && CONTAINS_PLACEHOLDER_P
4567 else
4572 else
4573 gnu_call
4577 }
4578 else
4580 }
4582 /* Otherwise, if this is a procedure call statement without copy-in/copy-out
4583 parameters, the result is just the call statement. */
4587 /* Finally, add the copy back statements, if any. */
4593 /* If we have pushed a binding level, pop it and finish up the enclosing
4594 statement group. */
4596 {
4600 }
4602 /* Otherwise, retrieve the statement list, if any. */
4606 /* Otherwise, just return the call expression. */
4607 else
4610 /* If we nevertheless need a value, make a COMPOUND_EXPR to return it.
4611 But first simplify if we have only one statement in the list. */
4613 {
4617 gnu_result
4619 }
4622 }
4623 \f
4624 /* Subroutine of gnat_to_gnu to translate gnat_node, an
4625 N_Handled_Sequence_Of_Statements, to a GCC tree, which is returned. */
4627 static tree
4629 {
4632 /* If just annotating, ignore all EH and cleanups. */
4636 bool setjmp_longjmp
4642 tree gnu_result;
4643 tree gnu_expr;
4644 Node_Id gnat_temp;
4645 /* Node providing the sloc for the cleanup actions. */
4648 gnat_node);
4650 /* The GCC exception handling mechanism can handle both ZCX and SJLJ schemes
4651 and we have our own SJLJ mechanism. To call the GCC mechanism, we call
4652 add_cleanup, and when we leave the binding, end_stmt_group will create
4653 the TRY_FINALLY_EXPR.
4655 ??? The region level calls down there have been specifically put in place
4656 for a ZCX context and currently the order in which things are emitted
4657 (region/handlers) is different from the SJLJ case. Instead of putting
4658 other calls with different conditions at other places for the SJLJ case,
4659 it seems cleaner to reorder things for the SJLJ case and generalize the
4660 condition to make it not ZCX specific.
4662 If there are any exceptions or cleanup processing involved, we need an
4663 outer statement group (for Setjmp_Longjmp) and binding level. */
4665 {
4668 }
4670 /* If using setjmp_longjmp, make the variables for the setjmp buffer and save
4671 area for address of previous buffer. Do this first since we need to have
4672 the setjmp buf known for any decls in this block. */
4674 {
4675 gnu_jmpsave_decl
4677 jmpbuf_ptr_type,
4682 /* The __builtin_setjmp receivers will immediately reinstall it. Now
4683 because of the unstructured form of EH used by setjmp_longjmp, there
4684 might be forward edges going to __builtin_setjmp receivers on which
4685 it is uninitialized, although they will never be actually taken. */
4687 gnu_jmpbuf_decl
4689 jmpbuf_type,
4690 NULL_TREE,
4696 /* When we exit this block, restore the saved value. */
4698 gnat_cleanup_loc_node);
4699 }
4701 /* If we are to call a function when exiting this block, add a cleanup
4702 to the binding level we made above. Note that add_cleanup is FIFO
4703 so we must register this cleanup after the EH cleanup just above. */
4706 gnat_cleanup_loc_node);
4708 /* Now build the tree for the declarations and statements inside this block.
4709 If this is SJLJ, set our jmp_buf as the current buffer. */
4715 gnu_jmpbuf_decl)));
4721 /* Generate code for each statement in the block. */
4729 /* Now generate code for the two exception models, if either is relevant for
4730 this block. */
4732 {
4734 tree gnu_handler;
4736 /* Make a binding level for the exception handling declarations and code
4737 and set up gnu_except_ptr_stack for the handlers to use. */
4748 /* Generate code for each handler. The N_Exception_Handler case does the
4749 real work and returns a COND_EXPR for each handler, which we chain
4750 together here. */
4753 {
4756 /* If this is the first one, set it as the outer one. Otherwise,
4757 point the "else" part of the previous handler to us. Then point
4758 to our "else" part. */
4761 else
4765 }
4767 /* If none of the exception handlers did anything, re-raise but do not
4768 defer abortion. */
4771 set_expr_location_from_node
4777 else
4780 /* End the binding level dedicated to the exception handlers and get the
4781 whole statement group. */
4786 /* If the setjmp returns 1, we restore our incoming longjmp value and
4787 then check the handlers. */
4790 gnu_jmpsave_decl),
4791 gnat_node);
4795 /* This block is now "if (setjmp) ... <handlers> else <block>". */
4797 (build_call_n_expr
4800 gnu_jmpbuf_decl))),
4802 }
4804 {
4805 tree gnu_handlers;
4806 location_t locus;
4808 /* First make a block containing the handlers. */
4816 /* Now make the TRY_CATCH_EXPR for the block. */
4819 /* Set a location. We need to find a unique location for the dispatching
4820 code, otherwise we can get coverage or debugging issues. Try with
4821 the location of the end label. */
4825 else
4826 /* Clear column information so that the exception handler of an
4827 implicit transient block does not incorrectly inherit the slocs
4828 of a decision, which would otherwise confuse control flow based
4829 coverage analysis tools. */
4831 }
4832 else
4835 /* Now close our outer block, if we had to make one. */
4837 {
4841 }
4844 }
4845 \f
4846 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
4847 to a GCC tree, which is returned. This is the variant for Setjmp_Longjmp
4848 exception handling. */
4850 static tree
4852 {
4853 /* Unless this is "Others" or the special "Non-Ada" exception for Ada, make
4854 an "if" statement to select the proper exceptions. For "Others", exclude
4855 exceptions where Handled_By_Others is nonzero unless the All_Others flag
4856 is set. For "Non-ada", accept an exception if "Lang" is 'V'. */
4859 Node_Id gnat_temp;
4863 {
4864 tree this_choice;
4867 {
4870 else
4871 this_choice
4872 = build_binary_op
4874 convert
4876 build_component_ref
4877 (build_unary_op
4882 integer_zero_node);
4883 }
4887 {
4889 tree gnu_expr;
4891 /* Exception may be a renaming. Recover original exception which is
4892 the one elaborated and registered. */
4898 this_choice
4899 = build_binary_op
4905 /* If this is the distinguished exception "Non_Ada_Error" (and we are
4906 in VMS mode), also allow a non-Ada exception (a VMS condition) t
4907 match. */
4909 {
4910 tree gnu_comp
4911 = build_component_ref
4916 this_choice
4917 = build_binary_op
4921 this_choice);
4922 }
4923 }
4924 else
4929 }
4932 }
4933 \f
4934 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
4935 to a GCC tree, which is returned. This is the variant for ZCX. */
4937 static tree
4939 {
4942 Node_Id gnat_temp;
4944 /* We build a TREE_LIST of nodes representing what exception types this
4945 handler can catch, with special cases for others and all others cases.
4947 Each exception type is actually identified by a pointer to the exception
4948 id, or to a dummy object for "others" and "all others". */
4951 {
4955 {
4958 }
4961 {
4964 /* Exception may be a renaming. Recover original exception which is
4965 the one elaborated and registered. */
4972 /* The Non_Ada_Error case for VMS exceptions is handled
4973 by the personality routine. */
4974 }
4975 else
4978 /* The GCC interface expects NULL to be passed for catch all handlers, so
4979 it would be quite tempting to set gnu_etypes_list to NULL if gnu_etype
4980 is integer_zero_node. It would not work, however, because GCC's
4981 notion of "catch all" is stronger than our notion of "others". Until
4982 we correctly use the cleanup interface as well, doing that would
4983 prevent the "all others" handlers from being seen, because nothing
4984 can be caught beyond a catch all from GCC's point of view. */
4986 }
4991 /* Expand a call to the begin_handler hook at the beginning of the handler,
4992 and arrange for a call to the end_handler hook to occur on every possible
4993 exit path.
4995 The hooks expect a pointer to the low level occurrence. This is required
4996 for our stack management scheme because a raise inside the handler pushes
4997 a new occurrence on top of the stack, which means that this top does not
4998 necessarily match the occurrence this handler was dealing with.
5000 __builtin_eh_pointer references the exception occurrence being
5001 propagated. Upon handler entry, this is the exception for which the
5002 handler is triggered. This might not be the case upon handler exit,
5003 however, as we might have a new occurrence propagated by the handler's
5004 body, and the end_handler hook called as a cleanup in this context.
5006 We use a local variable to retrieve the incoming value at handler entry
5007 time, and reuse it to feed the end_handler hook's argument at exit. */
5009 gnu_current_exc_ptr
5019 gnu_incoming_exc_ptr),
5020 gnat_node);
5022 /* Declare and initialize the choice parameter, if present. */
5024 {
5025 tree gnu_param
5031 gnu_incoming_exc_ptr));
5032 }
5034 /* We don't have an End_Label at hand to set the location of the cleanup
5035 actions, so we use that of the exception handler itself instead. */
5037 gnat_node);
5043 return
5045 }
5046 \f
5047 /* Subroutine of gnat_to_gnu to generate code for an N_Compilation unit. */
5049 static void
5051 {
5056 Node_Id gnat_pragma;
5057 /* Make the decl for the elaboration procedure. */
5058 tree gnu_elab_proc_decl
5059 = create_subprog_decl
5062 gnat_unit);
5068 /* Initialize the information structure for the function. */
5077 /* For a body, first process the spec if there is one. */
5083 {
5090 }
5092 /* Then process any pragmas and declarations preceding the unit. */
5101 /* Process the unit itself. */
5104 /* If we can inline, generate code for all the inlined subprograms. */
5106 {
5107 Entity_Id gnat_entity;
5112 {
5116 {
5117 /* ??? This really should always be present. */
5120 gnat_body
5122 }
5125 {
5126 /* Define the entity first so we set DECL_EXTERNAL. */
5129 }
5130 }
5131 }
5133 /* Process any pragmas and actions following the unit. */
5138 /* Save away what we've made so far and record this potential elaboration
5139 procedure. */
5152 /* Generate elaboration code for this unit, if necessary, and say whether
5153 we did or not. */
5156 /* Invalidate the global renaming pointers. This is necessary because
5157 stabilization of the renamed entities may create SAVE_EXPRs which
5158 have been tied to a specific elaboration routine just above. */
5160 }
5161 \f
5162 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Raise_xxx_Error,
5163 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to where
5164 we should place the result type. LABEL_P is true if there is a label to
5165 branch to for the exception. */
5167 static tree
5169 {
5173 const bool with_extra_info
5174 = Exception_Extra_Info
5182 {
5192 {
5198 {
5218 }
5225 && gnu_low_bound
5226 && gnu_high_bound
5229 gnu_result
5233 /* If loop unswitching is enabled, we try to compute invariant
5234 conditions for checks applied to iteration variables, i.e.
5235 conditions that are both independent of the variable and
5236 necessary in order for the check to fail in the course of
5237 some iteration, and prepend them to the original condition
5238 of the checks. This will make it possible later for the
5239 loop unswitching pass to replace the loop with two loops,
5240 one of which has the checks eliminated and the other has
5241 the original checks reinstated, and a run time selection.
5242 The former loop will be suitable for vectorization. */
5244 && (!gnu_low_bound
5246 && (!gnu_high_bound
5249 {
5254 boolean_true_node);
5256 boolean_type_node,
5259 }
5260 }
5265 }
5267 common:
5272 /* If the type is VOID, this is a statement, so we need to generate the code
5273 for the call. Handle a condition, if there is one. */
5275 {
5277 {
5282 }
5283 }
5284 else
5288 }
5289 \f
5290 /* Return true if GNAT_NODE is on the LHS of an assignment or an actual
5291 parameter of a call. */
5293 static bool
5295 {
5310 }
5312 /* Return true if either GNAT_NODE or a view of GNAT_NODE is on the LHS
5313 of an assignment or an actual parameter of a call. */
5315 static bool
5317 {
5318 Node_Kind kind;
5330 }
5332 /* Return true if GNAT_NODE, an unchecked type conversion, is a no-op as far
5333 as gigi is concerned. This is used to avoid conversions on the LHS. */
5335 static bool
5337 {
5340 /* The conversion must be on the LHS of an assignment or an actual parameter
5341 of a call. Otherwise, even if the conversion was essentially a no-op, it
5342 could de facto ensure type consistency and this should be preserved. */
5348 /* We're interested in artificial conversions generated by the front-end
5349 to make private types explicit, e.g. in Expand_Assign_Array. */
5356 /* The direct conversion to the underlying type is a no-op. */
5360 /* For an array subtype, the conversion to the PAT is a no-op. */
5365 /* For a record subtype, the conversion to the type is a no-op. */
5371 }
5373 /* This function is the driver of the GNAT to GCC tree transformation process.
5374 It is the entry point of the tree transformer. GNAT_NODE is the root of
5375 some GNAT tree. Return the root of the corresponding GCC tree. If this
5376 is an expression, return the GCC equivalent of the expression. If this
5377 is a statement, return the statement or add it to the current statement
5378 group, in which case anything returned is to be interpreted as occurring
5379 after anything added. */
5381 tree
5383 {
5389 Node_Id gnat_temp;
5391 /* Save node number for error message and set location information. */
5395 /* If this node is a statement and we are only annotating types, return an
5396 empty statement list. */
5400 /* If this node is a non-static subexpression and we are only annotating
5401 types, make this into a NULL_EXPR. */
5408 N_Raise_Constraint_Error));
5417 {
5420 /* If this is a statement and we are at top level, it must be part of
5421 the elaboration procedure, so mark us as being in that procedure. */
5423 {
5426 }
5428 /* If we are in the elaboration procedure, check if we are violating a
5429 No_Elaboration_Code restriction by having a statement there. Don't
5430 check for a possible No_Elaboration_Code restriction violation on
5431 N_Handled_Sequence_Of_Statements, as we want to signal an error on
5432 every nested real statement instead. This also avoids triggering
5433 spurious errors on dummy (empty) sequences created by the front-end
5434 for package bodies in some cases. */
5438 }
5441 {
5442 /********************************/
5443 /* Chapter 2: Lexical Elements */
5444 /********************************/
5452 /* If this is an atomic access on the RHS for which synchronization is
5453 required, build the atomic load. */
5460 {
5461 tree gnu_type;
5463 /* Get the type of the result, looking inside any padding and
5464 justified modular types. Then get the value in that type. */
5473 /* If the result overflows (meaning it doesn't fit in its base type),
5474 abort. We would like to check that the value is within the range
5475 of the subtype, but that causes problems with subtypes whose usage
5476 will raise Constraint_Error and with biased representation, so
5477 we don't. */
5479 }
5483 /* If a Entity is present, it means that this was one of the
5484 literals in a user-defined character type. In that case,
5485 just return the value in the CONST_DECL. Otherwise, use the
5486 character code. In that case, the base type should be an
5487 INTEGER_TYPE, but we won't bother checking for that. */
5491 else
5492 gnu_result
5493 = build_int_cst_type
5500 /* If this is of a fixed-point type, the value we want is the
5501 value of the corresponding integer. */
5503 {
5505 gnu_result_type);
5507 }
5509 /* Convert the Ureal to a vax float (represented on a signed type). */
5511 {
5513 gnu_result_type);
5514 }
5516 else
5517 {
5520 /* First convert the real value to a machine number if it isn't
5521 already. That forces BASE to 2 for non-zero values and simplifies
5522 the rest of our logic. */
5525 ur_realval
5531 else
5532 {
5533 REAL_VALUE_TYPE tmp;
5535 gnu_result
5538 /* The base must be 2 as Machine guarantees this, so we scale
5539 the value, which we know can fit in the mantissa of the type
5540 (hence the use of that type above). */
5546 }
5548 /* Now see if we need to negate the result. Do it this way to
5549 properly handle -0. */
5551 gnu_result
5553 gnu_result);
5554 }
5561 {
5568 else
5571 /* Build the string with the characters in the literal. Note
5572 that Ada strings are 1-origin. */
5576 /* Put a null at the end of the string in case it's in a context
5577 where GCC will want to treat it as a C string. */
5582 /* Strings in GCC don't normally have types, but we want
5583 this to not be converted to the array type. */
5588 }
5589 else
5590 {
5591 /* Build a list consisting of each character, then make
5592 the aggregate. */
5602 {
5608 }
5611 }
5618 /**************************************/
5619 /* Chapter 3: Declarations and Types */
5620 /**************************************/
5637 /* If we are just annotating types and this object has an unconstrained
5638 or task type, don't elaborate it. */
5648 && (!type_annotate_only
5650 {
5653 gnu_expr
5656 /* If this object has its elaboration delayed, we must force
5657 evaluation of GNU_EXPR right now and save it for when the object
5658 is frozen. */
5660 {
5662 ;
5664 gnu_expr
5669 else
5673 }
5674 }
5675 else
5681 /* If this is a deferred constant with an address clause, we ignore the
5682 full view since the clause is on the partial view and we cannot have
5683 2 different GCC trees for the object. The only bits of the full view
5684 we will use is the initializer, but it will be directly fetched. */
5697 /* Don't do anything if this renaming is handled by the front end or if
5698 we are just annotating types and this object has a composite or task
5699 type, don't elaborate it. We return the result in case it has any
5700 SAVE_EXPRs in it that need to be evaluated here. */
5702 && ! (type_annotate_only
5706 gnu_result
5709 else
5722 /* These are fully handled in the front end. */
5726 /*************************************/
5727 /* Chapter 4: Names and Expressions */
5728 /*************************************/
5735 /* If this is an atomic access on the RHS for which synchronization is
5736 required, build the atomic load. */
5743 {
5745 tree gnu_type;
5752 /* Convert vector inputs to their representative array type, to fit
5753 what the code below expects. */
5755 {
5759 }
5763 /* If we got a padded type, remove it too. */
5765 gnu_array_object
5767 gnu_array_object);
5771 /* The failure of this assertion will very likely come from a missing
5772 expansion for a packed array access. */
5775 /* First compute the number of dimensions of the array, then
5776 fill the expression array, the order depending on whether
5777 this is a Convention_Fortran array or not. */
5782 ;
5791 else
5799 {
5805 gnu_expr
5806 = emit_index_check
5810 gnat_temp);
5814 }
5818 /* If this is an atomic access on the RHS for which synchronization is
5819 required, build the atomic load. */
5823 }
5827 {
5829 tree gnu_type;
5834 /* Do any implicit dereferences of the prefix and do any needed
5835 range check. */
5840 {
5841 /* Get the bounds of the slice. */
5842 tree gnu_index_type
5846 /* Get the permitted bounds. */
5847 tree gnu_base_index_type
5849 tree gnu_base_min_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
5851 tree gnu_base_max_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
5858 /* Derive a good type to convert everything to. */
5861 /* Test whether the minimum slice value is too small. */
5864 gnu_min_expr),
5866 gnu_base_min_expr));
5868 /* Test whether the maximum slice value is too large. */
5871 gnu_max_expr),
5873 gnu_base_max_expr));
5875 /* Build a slice index check that returns the low bound,
5876 assuming the slice is not empty. */
5877 gnu_expr = emit_check
5882 /* Build a conditional expression that does the index checks and
5883 returns the low bound if the slice is not empty (max >= min),
5884 and returns the naked low bound otherwise (max < min), unless
5885 it is non-constant and the high bound is; this prevents VRP
5886 from inferring bogus ranges on the unlikely path. */
5890 gnu_max_expr),
5892 gnu_min_expr)),
5893 gnu_expr,
5897 }
5898 else
5899 /* Simply return the naked low bound. */
5902 /* If this is a slice with non-constant size of an array with constant
5903 size, set the maximum size for the allocation of temporaries. */
5910 }
5914 {
5918 tree gnu_field;
5922 {
5927 }
5931 /* For discriminant references in tagged types always substitute the
5932 corresponding discriminant as the actual selected component. */
5937 /* For discriminant references of untagged types always substitute the
5938 corresponding stored discriminant. */
5942 /* Handle extracting the real or imaginary part of a complex.
5943 The real part is the first field and the imaginary the last. */
5948 else
5949 {
5952 /* If there are discriminants, the prefix might be evaluated more
5953 than once, which is a problem if it has side-effects. */
5960 gnu_result
5964 && lvalue_required_for_attribute_p
5966 }
5970 /* If this is an atomic access on the RHS for which synchronization is
5971 required, build the atomic load. */
5975 }
5979 {
5980 /* The attribute designator. */
5983 /* The Elab_Spec and Elab_Body attributes are special in that Prefix
5984 is a unit, not an object with a GCC equivalent. */
5986 return
5994 }
5998 /* Like 'Access as far as we are concerned. */
6006 {
6007 tree gnu_aggr_type;
6009 /* ??? It is wrong to evaluate the type now, but there doesn't
6010 seem to be any other practical way of doing it. */
6014 gnu_aggr_type = gnu_result_type
6019 gnu_aggr_type
6026 NULL);
6030 gnu_result
6033 gnu_aggr_type);
6036 gnu_aggr_type,
6039 gnu_result
6040 = build_binary_op
6045 (Next
6047 else
6051 }
6059 else
6066 /* Get the operand expression. */
6070 /* If this is a qualified expression for a tagged type, we mark the type
6071 as used. Because of polymorphism, this might be the only reference to
6072 the tagged type in the program while objects have it as dynamic type.
6073 The debugger needs to see it to display these objects properly. */
6077 gnu_result
6081 kind == N_Type_Conversion
6088 /* Skip further processing if the conversion is deemed a no-op. */
6090 {
6093 }
6097 /* If the result is a pointer type, see if we are improperly
6098 converting to a stricter alignment. */
6101 {
6107 post_error_ne_tree_2
6111 }
6113 /* If we are converting a descriptor to a function pointer, first
6114 build the pointer. */
6126 {
6131 /* GNAT_RANGE is either an N_Range node or an identifier denoting a
6132 subtype. */
6134 {
6137 }
6140 {
6145 }
6146 else
6151 /* If LOW and HIGH are identical, perform an equality test. Otherwise,
6152 ensure that GNU_OBJ is evaluated only once and perform a full range
6153 test. */
6155 gnu_result
6157 else
6158 {
6167 gnu_result
6169 }
6172 gnu_result
6174 }
6182 ? RDIV_EXPR
6189 /* These can either be operations on booleans or on modular types.
6190 Fall through for boolean types since that's the way GNU_CODES is
6191 set up. */
6193 {
6194 enum tree_code code
6205 }
6207 /* ... fall through ... */
6219 {
6223 tree gnu_type;
6229 /* Pending generic support for efficient vector logical operations in
6230 GCC, convert vectors to their representative array type view and
6231 fallthrough. */
6235 /* If this is a comparison operator, convert any references to an
6236 unconstrained array value into a reference to the actual array. */
6238 {
6241 }
6243 /* If this is a shift whose count is not guaranteed to be correct,
6244 we need to adjust the shift count. */
6246 {
6248 tree gnu_max_shift
6255 gnu_rhs
6256 = build_binary_op
6259 gnu_count_type,
6260 gnu_max_shift,
6262 integer_one_node)),
6263 gnu_rhs);
6264 }
6266 /* For right shifts, the type says what kind of shift to do,
6267 so we may need to choose a different type. In this case,
6268 we have to ignore integer overflow lest it propagates all
6269 the way down and causes a CE to be explicitly raised. */
6271 {
6274 }
6277 {
6280 }
6283 {
6289 }
6291 /* Instead of expanding overflow checks for addition, subtraction
6292 and multiplication itself, the front end will leave this to
6293 the back end when Backend_Overflow_Checks_On_Target is set.
6294 As the GCC back end itself does not know yet how to properly
6295 do overflow checking, do it here. The goal is to push
6296 the expansions further into the back end over time. */
6305 else
6306 {
6307 /* Some operations, e.g. comparisons of arrays, generate complex
6308 trees that need to be annotated while they are being built. */
6311 }
6313 /* If this is a logical shift with the shift count not verified,
6314 we must return zero if it is too large. We cannot compensate
6315 above in this case. */
6318 gnu_result
6319 = build_cond_expr
6322 gnu_rhs,
6326 gnu_result);
6327 }
6331 {
6334 tree gnu_false
6338 gnu_result
6340 }
6349 /* This case can apply to a boolean or a modular type.
6350 Fall through for a boolean operand since GNU_CODES is set
6351 up to handle this. */
6353 {
6357 gnu_expr);
6359 }
6361 /* ... fall through ... */
6370 gnu_result
6373 else
6379 {
6381 tree gnu_type;
6386 /* The Expression operand can either be an N_Identifier or
6387 Expanded_Name, which must represent a type, or a
6388 N_Qualified_Expression, which contains both the object type and an
6389 initial value for the object. */
6394 {
6395 Entity_Id gnat_desig_type
6403 gnu_init
6409 else
6410 {
6414 }
6416 /* See the N_Qualified_Expression case for the rationale. */
6421 }
6422 else
6429 ignore_init_type);
6430 }
6433 /**************************/
6434 /* Chapter 5: Statements */
6435 /**************************/
6443 /* When not optimizing, turn null statements from source into gotos to
6444 the next statement that the middle-end knows how to preserve. */
6446 {
6457 }
6458 else
6463 /* Get the LHS and RHS of the statement and convert any reference to an
6464 unconstrained array into a reference to the underlying array. */
6467 /* If the type has a size that overflows, convert this into raise of
6468 Storage_Error: execution shouldn't have gotten here anyway. */
6472 N_Raise_Storage_Error);
6474 gnu_result
6477 else
6478 {
6479 gnu_rhs
6482 /* If range check is needed, emit code to generate it. */
6485 gnat_node);
6489 else
6490 gnu_result
6493 /* If the type being assigned is an array type and the two sides are
6494 not completely disjoint, play safe and use memmove. But don't do
6495 it for a bit-packed array as it might not be byte-aligned. */
6500 {
6514 }
6515 }
6519 {
6522 /* Make the outer COND_EXPR. Avoid non-determinism. */
6531 /* Now make a COND_EXPR for each of the "else if" parts. Put each
6532 into the previous "else" part and point to where to put any
6533 outer "else". Also avoid non-determinism. */
6537 {
6547 }
6550 }
6562 /* The only way to enter the block is to fall through to it. */
6564 {
6571 }
6572 else
6577 gnu_result
6587 {
6590 /* If the subprogram is a function, we must return the expression. */
6592 {
6595 /* If this function has copy-in/copy-out parameters, get the real
6596 object for the return. See Subprogram_to_gnu. */
6599 else
6602 /* Get the GCC tree for the expression to be returned. */
6605 /* Do not remove the padding from GNU_RET_VAL if the inner type is
6606 self-referential since we want to allocate the fixed size. */
6608 && TYPE_IS_PADDING_P
6610 && CONTAINS_PLACEHOLDER_P
6614 /* If the function returns by direct reference, return a pointer
6615 to the return value. */
6620 /* Otherwise, if it returns an unconstrained array, we have to
6621 allocate a new version of the result and return it. */
6623 {
6626 /* And find out whether this is a candidate for Named Return
6627 Value. If so, record it. */
6629 {
6632 /* Strip useless conversions around the return value. */
6636 /* Strip unpadding around the return value. */
6638 && TYPE_IS_PADDING_P
6642 /* Now apply the test to the return value. */
6644 {
6650 }
6651 }
6654 gnu_ret_val,
6659 }
6661 /* Otherwise, if it returns by invisible reference, dereference
6662 the pointer it is passed using the type of the return value
6663 and build the copy operation manually. This ensures that we
6664 don't copy too much data, for example if the return type is
6665 unconstrained with a maximum size. */
6667 {
6668 tree gnu_ret_deref
6670 gnu_ret_obj);
6675 }
6676 }
6678 else
6681 /* If we have a return label defined, convert this into a branch to
6682 that label. The return proper will be handled elsewhere. */
6684 {
6687 gnu_ret_val));
6692 /* When not optimizing, make sure the return is preserved. */
6695 }
6697 /* Otherwise, build a regular return. */
6698 else
6700 }
6704 gnu_result
6708 /***************************/
6709 /* Chapter 6: Subprograms */
6710 /***************************/
6713 /* Unless there is a freeze node, declare the subprogram. We consider
6714 this a "definition" even though we're not generating code for
6715 the subprogram because we will be making the corresponding GCC
6716 node here. */
6725 /* This subprogram doesn't exist for code generation purposes, but we
6726 have to elaborate the types of any parameters and result, unless
6727 they are imported types (nothing to generate in this case).
6729 The parameter list may contain types with freeze nodes, e.g. not null
6730 subtypes, so the subprogram itself may carry a freeze node, in which
6731 case its elaboration must be deferred. */
6733 /* Process the parameter types first. */
6736 = First_Formal_With_Extras
6744 /* Then the result type, set to Standard_Void_Type for procedures. */
6745 {
6746 Entity_Id gnat_temp_type
6751 }
6757 /* For a child unit identifier go up a level to get the specification.
6758 We get this when we try to find the spec of a child unit package
6759 that is the compilation unit being compiled. */
6773 /************************/
6774 /* Chapter 7: Packages */
6775 /************************/
6791 /* If this is the body of a generic package - do nothing. */
6793 {
6796 }
6807 /********************************/
6808 /* Chapter 8: Visibility Rules */
6809 /********************************/
6813 /* Nothing to do here - but these may appear in list of declarations. */
6817 /*********************/
6818 /* Chapter 9: Tasks */
6819 /*********************/
6830 /*********************************************************/
6831 /* Chapter 10: Program Structure and Compilation Issues */
6832 /*********************************************************/
6835 /* This is not called for the main unit on which gigi is invoked. */
6844 /* Simply process whatever unit is being inserted. */
6847 else
6848 {
6851 }
6858 /***************************/
6859 /* Chapter 11: Exceptions */
6860 /***************************/
6863 /* If there is an At_End procedure attached to this node, and the EH
6864 mechanism is SJLJ, we must have at least a corresponding At_End
6865 handler, unless the No_Exception_Handlers restriction is set. */
6880 else
6885 /* Only for reraise in back-end exceptions mode. */
6892 /* Clear the current exception pointer so that the occurrence won't be
6893 deallocated. */
6932 /******************************/
6933 /* Chapter 12: Generic Units */
6934 /******************************/
6944 /* These nodes can appear on a declaration list but there is nothing to
6945 to be done with them. */
6949 /**************************************************/
6950 /* Chapter 13: Representation Clauses and */
6951 /* Implementation-Dependent Features */
6952 /**************************************************/
6957 /* The only one we need to deal with is 'Address since, for the others,
6958 the front-end puts the information elsewhere. */
6962 /* And we only deal with 'Address if the object has a Freeze node. */
6967 /* Get the value to use as the address and save it as the equivalent
6968 for the object. When it is frozen, gnat_to_gnu_entity will do the
6969 right thing. */
6976 /* We do nothing with these. SEM puts the information elsewhere. */
6982 {
6992 /* First retrieve the 3 operand lists built by the front-end. */
6995 {
7002 }
7006 {
7013 }
7017 gnu_clobbers
7020 gnu_clobbers);
7022 /* Then perform some standard checking and processing on the
7023 operands. In particular, mark them addressable if needed. */
7031 {
7033 constraint
7039 {
7040 /* If the operand is going to end up in memory,
7041 mark it addressable. Note that we don't test
7042 allows_mem like in the input case below; this
7043 is modelled on the C front-end. */
7045 {
7052 }
7053 }
7054 else
7058 }
7061 {
7063 constraint
7069 {
7070 /* If the operand is going to end up in memory,
7071 mark it addressable. */
7073 {
7080 }
7081 }
7082 else
7086 }
7092 }
7093 else
7098 /****************/
7099 /* Added Nodes */
7100 /****************/
7103 /* This construct doesn't define a scope so we don't push a binding level
7104 around the statement list; but we wrap it in a SAVE_EXPR to protect it
7105 from unsharing. */
7110 gnu_result
7135 {
7140 /* If this is a thin pointer, we must first dereference it to create
7141 a fat pointer, then go back below to a thin pointer. The reason
7142 for this is that we need to have a fat pointer someplace in order
7143 to properly compute the size. */
7147 gnu_ptr));
7149 /* If this is a fat pointer, the object must have been allocated with
7150 the template in front of the array. So pass the template address,
7151 and get the total size; do it by converting to a thin pointer. */
7153 gnu_ptr
7155 (TYPE_OBJECT_RECORD_TYPE
7157 gnu_ptr);
7161 /* If this is a thin pointer, the object must have been allocated with
7162 the template in front of the array. So pass the template address,
7163 and get the total size. */
7165 gnu_ptr
7167 gnu_ptr,
7169 byte_position
7170 (DECL_CHAIN
7173 /* If we have a special dynamic constrained subtype on the node, use
7174 it to compute the size; otherwise, use the designated subtype. */
7176 {
7177 gnu_actual_obj_type
7181 gnu_actual_obj_type
7183 gnu_actual_obj_type,
7186 }
7187 else
7190 gnu_result
7193 gnu_obj_type,
7196 gnat_node);
7197 }
7205 else
7210 /* The only validation we currently do on an unchecked conversion is
7211 that of aliasing assumptions. */
7223 /* These nodes should only be present when annotating types. */
7229 /* Other nodes are not supposed to reach here. */
7231 }
7233 /* If we pushed the processing of the elaboration routine, pop it back. */
7237 /* When not optimizing, turn boolean rvalues B into B != false tests
7238 so that the code just below can put the location information of the
7239 reference to B on the inequality operator for better debug info. */
7253 boolean_false_node));
7255 /* Set the location information on the result. Note that we may have
7256 no result if we tried to build a CALL_EXPR node to a procedure with
7257 no side-effects and optimization is enabled. */
7261 /* If we're supposed to return something of void_type, it means we have
7262 something we're elaborating for effect, so just return. */
7266 /* If the result is a constant that overflowed, raise Constraint_Error. */
7268 {
7270 gnu_result
7273 N_Raise_Constraint_Error));
7274 }
7276 /* If the result has side-effects and is of an unconstrained type, make a
7277 SAVE_EXPR so that we can be sure it will only be referenced once. But
7278 this is useless for a call to a function that returns an unconstrained
7279 type with default discriminant, as we cannot compute the size of the
7280 actual returned object. We must do this before any conversions. */
7288 /* Now convert the result to the result type, unless we are in one of the
7289 following cases:
7291 1. If this is the LHS of an assignment or an actual parameter of a
7292 call, return the result almost unmodified since the RHS will have
7293 to be converted to our type in that case, unless the result type
7294 has a simpler size. Likewise if there is just a no-op unchecked
7295 conversion in-between. Similarly, don't convert integral types
7296 that are the operands of an unchecked conversion since we need
7297 to ignore those conversions (for 'Valid).
7299 2. If we have a label (which doesn't have any well-defined type), a
7300 field or an error, return the result almost unmodified. Similarly,
7301 if the two types are record types with the same name, don't convert.
7302 This will be the case when we are converting from a packable version
7303 of a type to its original type and we need those conversions to be
7304 NOPs in order for assignments into these types to work properly.
7306 3. If the type is void or if we have no result, return error_mark_node
7307 to show we have no result.
7309 4. If this a call to a function that returns an unconstrained type with
7310 default discriminant, return the call expression unmodified since we
7311 cannot compute the size of the actual returned object.
7313 5. Finally, if the type of the result is already correct. */
7331 && (CONTAINS_PLACEHOLDER_P
7335 {
7336 /* Remove padding only if the inner object is of self-referential
7337 size: in that case it must be an object of unconstrained type
7338 with a default discriminant and we want to avoid copying too
7339 much data. */
7344 gnu_result);
7345 }
7354 {
7355 /* Remove any padding. */
7358 gnu_result);
7359 }
7367 == gnu_result_type
7369 ;
7374 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on the result. */
7381 }
7382 \f
7383 /* Subroutine of above to push the exception label stack. GNU_STACK is
7384 a pointer to the stack to update and GNAT_LABEL, if present, is the
7385 label to push onto the stack. */
7387 static void
7389 {
7395 }
7396 \f
7397 /* Record the current code position in GNAT_NODE. */
7399 static void
7401 {
7406 }
7408 /* Insert the code for GNAT_NODE at the position saved for that node. */
7410 static void
7412 {
7415 }
7416 \f
7417 /* Start a new statement group chained to the previous group. */
7419 void
7421 {
7424 /* First see if we can get one from the free list. */
7427 else
7433 }
7435 /* Add GNU_STMT to the current statement group. If it is an expression with
7436 no effects, it is ignored. */
7438 void
7440 {
7442 }
7444 /* Similar, but the statement is always added, regardless of side-effects. */
7446 void
7448 {
7450 }
7452 /* Like add_stmt, but set the location of GNU_STMT to that of GNAT_NODE. */
7454 void
7456 {
7460 }
7462 /* Similar, but the statement is always added, regardless of side-effects. */
7464 void
7466 {
7470 }
7472 /* Add a declaration statement for GNU_DECL to the current statement group.
7473 Get SLOC from Entity_Id. */
7475 void
7477 {
7481 /* If this is a variable that Gigi is to ignore, we may have been given
7482 an ERROR_MARK. So test for it. We also might have been given a
7483 reference for a renaming. So only do something for a decl. Also
7484 ignore a TYPE_DECL for an UNCONSTRAINED_ARRAY_TYPE. */
7492 /* If we are external or global, we don't want to output the DECL_EXPR for
7493 this DECL node since we already have evaluated the expressions in the
7494 sizes and positions as globals and doing it again would be wrong. */
7496 {
7497 /* Mark everything as used to prevent node sharing with subprograms.
7498 Note that walk_tree knows how to deal with TYPE_DECL, but neither
7499 VAR_DECL nor CONST_DECL. This appears to be somewhat arbitrary. */
7503 {
7507 }
7508 /* In any case, we have to deal with our own TYPE_ADA_SIZE field. */
7513 }
7514 else
7517 /* If this is a variable and an initializer is attached to it, it must be
7518 valid for the context. Similar to init_const in create_var_decl_1. */
7525 {
7526 /* If GNU_DECL has a padded type, convert it to the unpadded
7527 type so the assignment is done properly. */
7530 else
7537 {
7540 }
7543 }
7544 }
7546 /* Callback for walk_tree to mark the visited trees rooted at *TP. */
7548 static tree
7550 {
7556 /* Don't mark a dummy type as visited because we want to mark its sizes
7557 and fields once it's filled in. */
7565 }
7567 /* Mark nodes rooted at T with TREE_VISITED and types as having their
7568 sized gimplified. We use this to indicate all variable sizes and
7569 positions in global types may not be shared by any subprogram. */
7571 void
7573 {
7575 }
7577 /* Add GNU_CLEANUP, a cleanup action, to the current code group and
7578 set its location to that of GNAT_NODE if present, but with column info
7579 cleared so that conditional branches generated as part of the cleanup
7580 code do not interfere with coverage analysis tools. */
7582 static void
7584 {
7588 }
7590 /* Set the BLOCK node corresponding to the current code group to GNU_BLOCK. */
7592 void
7594 {
7597 }
7599 /* Return code corresponding to the current code group. It is normally
7600 a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
7601 BLOCK or cleanups were set. */
7603 tree
7605 {
7609 /* If this is a null list, allocate a new STATEMENT_LIST. Then, if there
7610 are cleanups, make a TRY_FINALLY_EXPR. Last, if there is a BLOCK,
7611 make a BIND_EXPR. Note that we nest in that because the cleanup may
7612 reference variables in the block. */
7624 /* Remove this group from the stack and add it to the free list. */
7630 }
7632 /* Return whether the current statement group may fall through. */
7636 {
7639 else
7641 }
7643 /* Add a list of statements from GNAT_LIST, a possibly-empty list of
7644 statements.*/
7646 static void
7648 {
7649 Node_Id gnat_node;
7655 }
7657 /* Build a tree from GNAT_LIST, a possibly-empty list of statements.
7658 If BINDING_P is true, push and pop a binding level around the list. */
7660 static tree
7662 {
7672 }
7673 \f
7674 /* Generate GIMPLE in place for the expression at *EXPR_P. */
7676 int
7679 {
7681 tree op;
7687 {
7689 /* If this is for a scalar, just make a VAR_DECL for it. If for
7690 an aggregate, get a null pointer of the appropriate type and
7691 dereference it. */
7695 integer_zero_node));
7696 else
7697 {
7700 }
7706 /* We should only do this if we are just elaborating for side-effects,
7707 but we can't know that yet. */
7714 /* If we are taking the address of a constant CONSTRUCTOR, make sure it
7715 is put into static memory. We know that it's going to be read-only
7716 given the semantics we have and it must be in static memory when the
7717 reference is in an elaboration procedure. */
7719 {
7723 }
7730 /* If we are view-converting a CONSTRUCTOR or a call from an aggregate
7731 type to a scalar one, explicitly create the local temporary. That's
7732 required if the type is passed by reference. */
7736 {
7745 }
7752 /* The expressions for the RM bounds must be gimplified to ensure that
7753 they are properly elaborated. See gimplify_decl_expr. */
7757 {
7762 {
7767 {
7771 }
7775 {
7779 }
7781 }
7786 }
7788 /* ... fall through ... */
7792 }
7793 }
7795 /* Generate GIMPLE in place for the statement at *STMT_P. */
7797 static enum gimplify_status
7799 {
7803 {
7809 {
7815 /* Build the condition expression from the test, if any. */
7817 {
7818 /* Deal with the optimization hints. */
7822 annot_expr_ivdep_kind));
7826 annot_expr_no_vector_kind));
7830 annot_expr_vector_kind));
7832 gnu_cond
7835 }
7837 /* Set to emit the statements of the loop. */
7840 /* We first emit the start label and then a conditional jump to the
7841 end label if there's a top condition, then the update if it's at
7842 the top, then the body of the loop, then a conditional jump to
7843 the end label if there's a bottom condition, then the update if
7844 it's at the bottom, and finally a jump to the start label and the
7845 definition of the end label. */
7847 gnu_start_label),
7848 stmt_p);
7869 gnu_end_label),
7870 stmt_p);
7872 }
7875 /* Build a statement to jump to the corresponding end label, then
7876 see if it needs to be conditional. */
7885 }
7886 }
7887 \f
7888 /* Force references to each of the entities in packages withed by GNAT_NODE.
7889 Operate recursively but check that we aren't elaborating something more
7890 than once.
7892 This routine is exclusively called in type_annotate mode, to compute DDA
7893 information for types in withed units, for ASIS use. */
7895 static void
7897 {
7900 /* Process each unit only once. As we trace the context of all relevant
7901 units transitively, including generic bodies, we may encounter the
7902 same generic unit repeatedly. */
7906 /* Save entities in all context units. A body may have an implicit_with
7907 on its own spec, if the context includes a child unit, so don't save
7908 the spec twice. */
7915 {
7919 {
7936 }
7938 {
7939 Node_Id gnat_body
7942 /* Retrieve compilation unit node of generic body. */
7947 /* If body is available, elaborate its context. */
7950 }
7951 }
7955 }
7956 \f
7957 /* Do the processing of GNAT_NODE, an N_Freeze_Entity. */
7959 static void
7961 {
7966 /* If this is a package, we need to generate code for the package. */
7968 {
7969 insert_code_for
7973 }
7975 /* Don't do anything for class-wide types as they are always transformed
7976 into their root type. */
7980 /* Check for an old definition. This freeze node might be for an Itype. */
7981 gnu_old
7984 /* If this entity has an address representation clause, GNU_OLD is the
7985 address, so discard it here. */
7989 /* Don't do anything for subprograms that may have been elaborated before
7990 their freeze nodes. This can happen, for example, because of an inner
7991 call in an instance body or because of previous compilation of a spec
7992 for inlining purposes. */
8000 /* If we have a non-dummy type old tree, we have nothing to do, except
8001 aborting if this is the public view of a private type whose full view was
8002 not delayed, as this node was never delayed as it should have been. We
8003 let this happen for concurrent types and their Corresponding_Record_Type,
8004 however, because each might legitimately be elaborated before its own
8005 freeze node, e.g. while processing the other. */
8009 {
8017 }
8019 /* Reset the saved tree, if any, and elaborate the object or type for real.
8020 If there is a full view, elaborate it and use the result. And, if this
8021 is the root type of a class-wide type, reuse it for the latter. */
8023 {
8033 }
8037 {
8040 /* Propagate back-annotations from full view to partial view. */
8050 /* The above call may have defined this entity (the simplest example
8051 of this is when we have a private enumeral type since the bounds
8052 will have the public view). */
8055 }
8056 else
8057 {
8058 tree gnu_init
8064 }
8071 /* If we have an old type and we've made pointers to this type, update those
8072 pointers. If this is a Taft amendment type in the main unit, we need to
8073 mark the type as used since other units referencing it don't see the full
8074 declaration and, therefore, cannot mark it as used themselves. */
8076 {
8081 }
8082 }
8083 \f
8084 /* Elaborate decls in the lists GNAT_DECLS and GNAT_DECLS2, if present.
8085 We make two passes, one to elaborate anything other than bodies (but
8086 we declare a function if there was no spec). The second pass
8087 elaborates the bodies.
8089 GNAT_END_LIST gives the element in the list past the end. Normally,
8090 this is Empty, but can be First_Real_Statement for a
8091 Handled_Sequence_Of_Statements.
8093 We make a complete pass through both lists if PASS1P is true, then make
8094 the second pass over both lists if PASS2P is true. The lists usually
8095 correspond to the public and private parts of a package. */
8097 static void
8100 {
8102 Node_Id gnat_decl;
8112 {
8113 /* For package specs, we recurse inside the declarations,
8114 thus taking the two pass approach inside the boundary. */
8122 /* Similarly for any declarations in the actions of a
8123 freeze node. */
8125 {
8128 }
8130 /* Package bodies with freeze nodes get their elaboration deferred
8131 until the freeze node, but the code must be placed in the right
8132 place, so record the code position now. */
8140 (Corresponding_Spec
8143 record_code_position
8146 /* We defer most subprogram bodies to the second pass. */
8148 {
8150 {
8156 }
8157 }
8159 /* For bodies and stubs that act as their own specs, the entity
8160 itself must be elaborated in the first pass, because it may
8161 be used in other declarations. */
8163 {
8164 Node_Id gnat_subprog_id
8171 }
8173 /* Concurrent stubs stand for the corresponding subprogram bodies,
8174 which are deferred like other bodies. */
8177 ;
8179 else
8181 }
8183 /* Here we elaborate everything we deferred above except for package bodies,
8184 which are elaborated at their freeze nodes. Note that we must also
8185 go inside things (package specs and freeze nodes) the first pass did. */
8191 {
8207 }
8208 }
8209 \f
8210 /* Make a unary operation of kind CODE using build_unary_op, but guard
8211 the operation by an overflow check. CODE can be one of NEGATE_EXPR
8212 or ABS_EXPR. GNU_TYPE is the type desired for the result. Usually
8213 the operation is to be performed in that type. GNAT_NODE is the gnat
8214 node conveying the source location for which the error should be
8215 signaled. */
8217 static tree
8219 Node_Id gnat_node)
8220 {
8229 }
8231 /* Make a binary operation of kind CODE using build_binary_op, but guard
8232 the operation by an overflow check. CODE can be one of PLUS_EXPR,
8233 MINUS_EXPR or MULT_EXPR. GNU_TYPE is the type desired for the result.
8234 Usually the operation is to be performed in that type. GNAT_NODE is
8235 the GNAT node conveying the source location for which the error should
8236 be signaled. */
8238 static tree
8241 {
8246 tree gnu_expr;
8249 tree rhs_lt_zero;
8250 tree check_pos;
8251 tree check_neg;
8252 tree check;
8257 /* Prefer a constant or known-positive rhs to simplify checks. */
8262 {
8266 }
8269 ? boolean_false_node
8272 /* ??? Should use more efficient check for operand_equal_p (lhs, rhs, 0) */
8274 /* Try a few strategies that may be cheaper than the general
8275 code at the end of the function, if the rhs is not known.
8276 The strategies are:
8277 - Call library function for 64-bit multiplication (complex)
8278 - Widen, if input arguments are sufficiently small
8279 - Determine overflow using wrapped result for addition/subtraction. */
8282 {
8283 /* Even for add/subtract double size to get another base type. */
8287 {
8293 }
8298 {
8305 tree check = build_binary_op
8314 return
8316 }
8319 {
8321 tree wrapped_expr = convert
8326 tree result = convert
8329 /* Overflow when (rhs < 0) ^ (wrapped_expr < lhs)), for addition
8330 or when (rhs < 0) ^ (wrapped_expr > lhs) for subtraction. */
8331 tree check = build_binary_op
8336 return
8338 }
8339 }
8342 {
8344 /* When rhs >= 0, overflow when lhs > type_max - rhs. */
8349 /* When rhs < 0, overflow when lhs < type_min - rhs. */
8356 /* When rhs >= 0, overflow when lhs < type_min + rhs. */
8361 /* When rhs < 0, overflow when lhs > type_max + rhs. */
8368 /* The check here is designed to be efficient if the rhs is constant,
8369 but it will work for any rhs by using integer division.
8370 Four different check expressions determine whether X * C overflows,
8371 depending on C.
8372 C == 0 => false
8373 C > 0 => X > type_max / C || X < type_min / C
8374 C == -1 => X == type_min
8375 C < -1 => X > type_min / C || X < type_max / C */
8380 check_pos
8383 rhs),
8386 boolean_type_node,
8389 boolean_type_node,
8392 check_neg
8397 type_min),
8400 boolean_type_node,
8403 boolean_type_node,
8409 }
8413 /* If we can fold the expression to a constant, just return it.
8414 The caller will deal with overflow, no need to generate a check. */
8419 check_pos);
8422 }
8424 /* Emit code for a range check. GNU_EXPR is the expression to be checked,
8425 GNAT_RANGE_TYPE the gnat type or subtype containing the bounds against
8426 which we have to check. GNAT_NODE is the GNAT node conveying the source
8427 location for which the error should be signaled. */
8429 static tree
8431 {
8435 /* If GNU_EXPR has GNAT_RANGE_TYPE as its base type, no check is needed.
8436 This can for example happen when translating 'Val or 'Value. */
8440 /* Range checks can only be applied to types with ranges. */
8444 /* If GNU_EXPR has an integral type that is narrower than GNU_RANGE_TYPE,
8445 we can't do anything since we might be truncating the bounds. No
8446 check is needed in this case. */
8452 /* Checked expressions must be evaluated only once. */
8455 /* Note that the form of the check is
8456 (not (expr >= lo)) or (not (expr <= hi))
8457 the reason for this slightly convoluted form is that NaNs
8458 are not considered to be in range in the float case. */
8459 return emit_check
8461 invert_truthvalue
8465 TYPE_MIN_VALUE
8467 invert_truthvalue
8471 TYPE_MAX_VALUE
8474 }
8475 \f
8476 /* Emit code for an index check. GNU_ARRAY_OBJECT is the array object which
8477 we are about to index, GNU_EXPR is the index expression to be checked,
8478 GNU_LOW and GNU_HIGH are the lower and upper bounds against which GNU_EXPR
8479 has to be checked. Note that for index checking we cannot simply use the
8480 emit_range_check function (although very similar code needs to be generated
8481 in both cases) since for index checking the array type against which we are
8482 checking the indices may be unconstrained and consequently we need to get
8483 the actual index bounds from the array object itself (GNU_ARRAY_OBJECT).
8484 The place where we need to do that is in subprograms having unconstrained
8485 array formal parameters. GNAT_NODE is the GNAT node conveying the source
8486 location for which the error should be signaled. */
8488 static tree
8491 {
8492 tree gnu_expr_check;
8494 /* Checked expressions must be evaluated only once. */
8497 /* Must do this computation in the base type in case the expression's
8498 type is an unsigned subtypes. */
8501 /* If GNU_LOW or GNU_HIGH are a PLACEHOLDER_EXPR, qualify them by
8502 the object we are handling. */
8506 return emit_check
8509 gnu_expr_check,
8511 gnu_low)),
8513 gnu_expr_check,
8515 gnu_high))),
8517 }
8518 \f
8519 /* GNU_COND contains the condition corresponding to an access, discriminant or
8520 range check of value GNU_EXPR. Build a COND_EXPR that returns GNU_EXPR if
8521 GNU_COND is false and raises a CONSTRAINT_ERROR if GNU_COND is true.
8522 REASON is the code that says why the exception was raised. GNAT_NODE is
8523 the GNAT node conveying the source location for which the error should be
8524 signaled. */
8526 static tree
8528 {
8529 tree gnu_call
8531 tree gnu_result
8535 gnu_expr);
8537 /* GNU_RESULT has side effects if and only if GNU_EXPR has:
8538 we don't need to evaluate it just for the check. */
8542 }
8543 \f
8544 /* Return an expression that converts GNU_EXPR to GNAT_TYPE, doing overflow
8545 checks if OVERFLOW_P is true and range checks if RANGE_P is true.
8546 GNAT_TYPE is known to be an integral type. If TRUNCATE_P true, do a
8547 float to integer conversion with truncation; otherwise round.
8548 GNAT_NODE is the GNAT node conveying the source location for which the
8549 error should be signaled. */
8551 static tree
8554 {
8561 /* If we are not doing any checks, the output is an integral type, and
8562 the input is not a floating type, just do the conversion. This
8563 shortcut is required to avoid problems with packed array types
8564 and simplifies code in all cases anyway. */
8569 /* First convert the expression to its base type. This
8570 will never generate code, but makes the tests below much simpler.
8571 But don't do this if converting from an integer type to an unconstrained
8572 array type since then we need to get the bounds from the original
8573 (unpacked) type. */
8577 /* If overflow checks are requested, we need to be sure the result will
8578 fit in the output base type. But don't do this if the input
8579 is integer and the output floating-point. */
8582 {
8583 /* Ensure GNU_EXPR only gets evaluated once. */
8591 /* Convert the lower bounds to signed types, so we're sure we're
8592 comparing them properly. Likewise, convert the upper bounds
8593 to unsigned types. */
8607 /* Check each bound separately and only if the result bound
8608 is tighter than the bound on the input type. Note that all the
8609 types are base types, so the bounds must be constant. Also,
8610 the comparison is done in the base type of the input, which
8611 always has the proper signedness. First check for input
8612 integer (which means output integer), output float (which means
8613 both float), or mixed, in which case we always compare.
8614 Note that we have to do the comparison which would *fail* in the
8615 case of an error since if it's an FP comparison and one of the
8616 values is a NaN or Inf, the comparison will fail. */
8623 gnu_cond
8624 = invert_truthvalue
8627 gnu_out_lb)));
8635 gnu_cond
8637 invert_truthvalue
8639 gnu_input,
8641 gnu_out_ub))));
8646 }
8648 /* Now convert to the result base type. If this is a non-truncating
8649 float-to-integer conversion, round. */
8652 {
8658 /* The following calculations depend on proper rounding to even
8659 of each arithmetic operation. In order to prevent excess
8660 precision from spoiling this property, use the widest hardware
8661 floating-point type if FP_ARITH_MAY_WIDEN is true. */
8662 calc_type
8665 /* FIXME: Should not have padding in the first place. */
8669 /* Compute the exact value calc_type'Pred (0.5) at compile time. */
8673 half_minus_pred_half);
8676 /* If the input is strictly negative, subtract this value
8677 and otherwise add it from the input. For 0.5, the result
8678 is exactly between 1.0 and the machine number preceding 1.0
8679 (for calc_type). Since the last bit of 1.0 is even, this 0.5
8680 will round to 1.0, while all other number with an absolute
8681 value less than 0.5 round to 0.0. For larger numbers exactly
8682 halfway between integers, rounding will always be correct as
8683 the true mathematical result will be closer to the higher
8684 integer compared to the lower one. So, this constant works
8685 for all floating-point numbers.
8687 The reason to use the same constant with subtract/add instead
8688 of a positive and negative constant is to allow the comparison
8689 to be scheduled in parallel with retrieval of the constant and
8690 conversion of the input to the calc_type (if necessary). */
8695 gnu_comp
8697 gnu_add_pred_half
8699 gnu_subtract_pred_half
8703 }
8709 else
8712 /* Finally, do the range check if requested. Note that if the result type
8713 is a modular type, the range check is actually an overflow check. */
8720 }
8721 \f
8722 /* Return true if GNU_EXPR can be directly addressed. This is the case
8723 unless it is an expression involving computation or if it involves a
8724 reference to a bitfield or to an object not sufficiently aligned for
8725 its type. If GNU_TYPE is non-null, return true only if GNU_EXPR can
8726 be directly addressed as an object of this type.
8728 *** Notes on addressability issues in the Ada compiler ***
8730 This predicate is necessary in order to bridge the gap between Gigi
8731 and the middle-end about addressability of GENERIC trees. A tree
8732 is said to be addressable if it can be directly addressed, i.e. if
8733 its address can be taken, is a multiple of the type's alignment on
8734 strict-alignment architectures and returns the first storage unit
8735 assigned to the object represented by the tree.
8737 In the C family of languages, everything is in practice addressable
8738 at the language level, except for bit-fields. This means that these
8739 compilers will take the address of any tree that doesn't represent
8740 a bit-field reference and expect the result to be the first storage
8741 unit assigned to the object. Even in cases where this will result
8742 in unaligned accesses at run time, nothing is supposed to be done
8743 and the program is considered as erroneous instead (see PR c/18287).
8745 The implicit assumptions made in the middle-end are in keeping with
8746 the C viewpoint described above:
8747 - the address of a bit-field reference is supposed to be never
8748 taken; the compiler (generally) will stop on such a construct,
8749 - any other tree is addressable if it is formally addressable,
8750 i.e. if it is formally allowed to be the operand of ADDR_EXPR.
8752 In Ada, the viewpoint is the opposite one: nothing is addressable
8753 at the language level unless explicitly declared so. This means
8754 that the compiler will both make sure that the trees representing
8755 references to addressable ("aliased" in Ada parlance) objects are
8756 addressable and make no real attempts at ensuring that the trees
8757 representing references to non-addressable objects are addressable.
8759 In the first case, Ada is effectively equivalent to C and handing
8760 down the direct result of applying ADDR_EXPR to these trees to the
8761 middle-end works flawlessly. In the second case, Ada cannot afford
8762 to consider the program as erroneous if the address of trees that
8763 are not addressable is requested for technical reasons, unlike C;
8764 as a consequence, the Ada compiler must arrange for either making
8765 sure that this address is not requested in the middle-end or for
8766 compensating by inserting temporaries if it is requested in Gigi.
8768 The first goal can be achieved because the middle-end should not
8769 request the address of non-addressable trees on its own; the only
8770 exception is for the invocation of low-level block operations like
8771 memcpy, for which the addressability requirements are lower since
8772 the type's alignment can be disregarded. In practice, this means
8773 that Gigi must make sure that such operations cannot be applied to
8774 non-BLKmode bit-fields.
8776 The second goal is achieved by means of the addressable_p predicate,
8777 which computes whether a temporary must be inserted by Gigi when the
8778 address of a tree is requested; if so, the address of the temporary
8779 will be used in lieu of that of the original tree and some glue code
8780 generated to connect everything together. */
8782 static bool
8784 {
8785 /* For an integral type, the size of the actual type of the object may not
8786 be greater than that of the expected type, otherwise an indirect access
8787 in the latter type wouldn't correctly set all the bits of the object. */
8793 /* The size of the actual type of the object may not be smaller than that
8794 of the expected type, otherwise an indirect access in the latter type
8795 would be larger than the object. But only record types need to be
8796 considered in practice for this case. */
8803 {
8808 /* All DECLs are addressable: if they are in a register, we can force
8809 them to memory. */
8814 /* Taking the address of a dereference yields the original pointer. */
8819 /* Taking the address yields a pointer to the constant pool. */
8823 /* Taking the address of a static constructor yields a pointer to the
8824 tree constant pool. */
8836 /* All rvalues are deemed addressable since taking their address will
8837 force a temporary to be created by the middle-end. */
8841 /* The address of a compound expression is that of its 2nd operand. */
8845 /* We accept &COND_EXPR as soon as both operands are addressable and
8846 expect the outcome to be the address of the selected operand. */
8852 /* Even with DECL_BIT_FIELD cleared, we have to ensure that
8853 the field is sufficiently aligned, in case it is subject
8854 to a pragma Component_Alignment. But we don't need to
8855 check the alignment of the containing record, as it is
8856 guaranteed to be not smaller than that of its most
8857 aligned field that is not a bit-field. */
8858 && (!STRICT_ALIGNMENT
8861 /* The field of a padding record is always addressable. */
8875 {
8876 /* This is addressable if we can avoid a copy. */
8880 && (!STRICT_ALIGNMENT
8885 && (!STRICT_ALIGNMENT
8891 }
8895 }
8896 }
8897 \f
8898 /* Do the processing for the declaration of a GNAT_ENTITY, a type. If
8899 a separate Freeze node exists, delay the bulk of the processing. Otherwise
8900 make a GCC type for GNAT_ENTITY and set up the correspondence. */
8902 void
8904 {
8905 tree gnu_old
8907 tree gnu_new;
8909 /* If we are to delay elaboration of this type, just do any
8910 elaborations needed for expressions within the declaration and
8911 make a dummy type entry for this node and its Full_View (if
8912 any) in case something points to it. Don't do this if it
8913 has already been done (the only way that can happen is if
8914 the private completion is also delayed). */
8920 {
8924 {
8929 {
8933 }
8934 }
8937 }
8939 /* If we saved away a dummy type for this node it means that this
8940 made the type that corresponds to the full type of an incomplete
8941 type. Clear that type for now and then update the type in the
8942 pointers. */
8944 {
8949 }
8951 /* Now fully elaborate the type. */
8955 /* If we have an old type and we've made pointers to this type, update those
8956 pointers. If this is a Taft amendment type in the main unit, we need to
8957 mark the type as used since other units referencing it don't see the full
8958 declaration and, therefore, cannot mark it as used themselves. */
8960 {
8965 }
8967 /* If this is a record type corresponding to a task or protected type
8968 that is a completion of an incomplete type, perform a similar update
8969 on the type. ??? Including protected types here is a guess. */
8973 {
8974 tree gnu_task_old
8984 }
8985 }
8986 \f
8987 /* GNAT_ENTITY is the type of the resulting constructor, GNAT_ASSOC is the
8988 front of the Component_Associations of an N_Aggregate and GNU_TYPE is the
8989 GCC type of the corresponding record type. Return the CONSTRUCTOR. */
8991 static tree
8993 {
8996 /* We test for GNU_FIELD being empty in the case where a variant
8997 was the last thing since we don't take things off GNAT_ASSOC in
8998 that case. We check GNAT_ASSOC in case we have a variant, but it
8999 has no fields. */
9002 {
9007 /* The expander is supposed to put a single component selector name
9008 in every record component association. */
9011 /* Ignore fields that have Corresponding_Discriminants since we'll
9012 be setting that field in the parent. */
9017 /* Also ignore discriminants of Unchecked_Unions. */
9022 /* Before assigning a value in an aggregate make sure range checks
9023 are done if required. Then convert to the type of the field. */
9029 /* Add the field and expression to the list. */
9031 }
9035 #ifdef ENABLE_CHECKING
9036 /* Verify that every entry in GNU_LIST was used. */
9039 #endif
9042 }
9044 /* Build a possibly nested constructor for array aggregates. GNAT_EXPR is
9045 the first element of an array aggregate. It may itself be an aggregate.
9046 GNU_ARRAY_TYPE is the GCC type corresponding to the array aggregate.
9047 GNAT_COMPONENT_TYPE is the type of the array component; it is needed
9048 for range checking. */
9050 static tree
9052 Entity_Id gnat_component_type)
9053 {
9055 tree gnu_expr;
9059 {
9060 /* If the expression is itself an array aggregate then first build the
9061 innermost constructor if it is part of our array (multi-dimensional
9062 case). */
9068 gnat_component_type);
9069 else
9070 {
9073 /* Before assigning the element to the array, make sure it is
9074 in range. */
9077 }
9084 integer_one_node));
9085 }
9088 }
9089 \f
9090 /* Subroutine of assoc_to_constructor: VALUES is a list of field associations,
9091 some of which are from RECORD_TYPE. Return a CONSTRUCTOR consisting
9092 of the associations that are from RECORD_TYPE. If we see an internal
9093 record, make a recursive call to fill it in as well. */
9095 static tree
9097 {
9102 {
9105 /* _Parent is an internal field, but may have values in the aggregate,
9106 so check for values first. */
9108 {
9111 }
9114 {
9119 }
9120 else
9121 /* If we have a record subtype, the names will match, but not the
9122 actual FIELD_DECLs. */
9125 {
9128 }
9134 }
9137 }
9138 \f
9139 /* Process a N_Validate_Unchecked_Conversion node. */
9141 static void
9143 {
9147 /* If the target is a pointer type, see if we are either converting from a
9148 non-pointer or from a pointer to a type with a different alias set and
9149 warn if so, unless the pointer has been marked to alias everything. */
9152 {
9162 target_alias_set)))
9163 {
9167 gnat_node);
9170 }
9171 }
9173 /* Likewise if the target is a fat pointer type, but we have no mechanism to
9174 mitigate the problem in this case, so we unconditionally warn. */
9176 {
9177 tree gnu_source_desig_type
9181 tree gnu_target_desig_type
9188 target_alias_set)))
9189 {
9193 gnat_node);
9194 }
9195 }
9196 }
9197 \f
9198 /* EXP is to be treated as an array or record. Handle the cases when it is
9199 an access object and perform the required dereferences. */
9201 static tree
9203 {
9204 /* If the type is a pointer, dereference it. */
9209 /* If we got a padded type, remove it too. */
9214 }
9215 \f
9216 /* Convert SLOC into LOCUS. Return true if SLOC corresponds to a source code
9217 location and false if it doesn't. In the former case, set the Gigi global
9218 variable REF_FILENAME to the simple debug file name as given by sinput.
9219 If clear_column is true, set column information to 0. */
9221 static bool
9223 {
9228 {
9231 }
9232 else
9233 {
9239 /* We can have zero if pragma Source_Reference is in effect. */
9243 /* Translate the location. */
9245 }
9247 ref_filename
9248 = IDENTIFIER_POINTER
9249 (get_identifier
9253 }
9255 /* Similar to the above, not clearing the column information. */
9257 bool
9259 {
9261 }
9263 /* Similar to set_expr_location, but start with the Sloc of GNAT_NODE and
9264 don't do anything if it doesn't correspond to a source location. */
9266 static void
9268 {
9269 location_t locus;
9275 }
9277 /* Similar to the above, not clearing the column information. */
9279 static void
9281 {
9283 }
9285 /* More elaborate version of set_expr_location_from_node to be used in more
9286 general contexts, for example the result of the translation of a generic
9287 GNAT node. */
9289 static void
9291 {
9292 /* Set the location information on the node if it is a real expression.
9293 References can be reused for multiple GNAT nodes and they would get
9294 the location information of their last use. Also make sure not to
9295 overwrite an existing location as it is probably more precise. */
9298 {
9299 CASE_CONVERT:
9307 /* ... fall through ... */
9311 {
9314 }
9316 }
9317 }
9318 \f
9319 /* Return a colon-separated list of encodings contained in encoded Ada
9320 name. */
9324 {
9328 }
9330 /* Extract the Ada name from an encoded name. */
9334 {
9338 }
9339 \f
9340 /* Post an error message. MSG is the error message, properly annotated.
9341 NODE is the node at which to post the error and the node to use for the
9342 '&' substitution. */
9344 void
9346 {
9347 String_Template temp;
9348 String_Pointer sp;
9358 }
9360 /* Similar to post_error, but NODE is the node at which to post the error and
9361 ENT is the node to use for the '&' substitution. */
9363 void
9365 {
9366 String_Template temp;
9367 String_Pointer sp;
9377 }
9379 /* Similar to post_error_ne, but NUM is the number to use for the '^'. */
9381 void
9383 {
9386 }
9388 /* Set the end_locus information for GNU_NODE, if any, from an explicit end
9389 location associated with GNAT_NODE or GNAT_NODE itself, whichever makes
9390 most sense. Return true if a sensible assignment was performed. */
9392 static bool
9394 {
9396 location_t end_locus;
9398 /* Pick the GNAT node of which we'll take the sloc to assign to the GCC node
9399 end_locus when there is one. We consider only GNAT nodes with a possible
9400 End_Label attached. If the End_Label actually was unassigned, fallback
9401 on the original node. We'd better assign an explicit sloc associated with
9402 the outer construct in any case. */
9405 {
9418 }
9422 /* Some expanded subprograms have neither an End_Label nor a Sloc
9423 attached. Notify that to callers. For a block statement with no
9424 End_Label, clear column information, so that the tree for a
9425 transient block does not receive the sloc of a source condition. */
9433 {
9444 }
9445 }
9446 \f
9447 /* Similar to post_error_ne, but T is a GCC tree representing the number to
9448 write. If T represents a constant, the text inside curly brackets in
9449 MSG will be output (presumably including a '^'). Otherwise it will not
9450 be output and the text inside square brackets will be output instead. */
9452 void
9454 {
9461 {
9464 }
9465 else
9469 {
9475 ;
9476 else
9478 }
9483 }
9485 /* Similar to post_error_ne_tree, but NUM is a second integer to write. */
9487 void
9490 {
9493 }
9494 \f
9495 /* Initialize the table that maps GNAT codes to GCC codes for simple
9496 binary and unary operations. */
9498 static void
9500 {
9526 }
9528 /* Return a label to branch to for the exception type in KIND or NULL_TREE
9529 if none. */
9531 tree
9533 {
9540 else
9542 }
9544 /* Return the decl for the current elaboration procedure. */
9546 tree
9548 {
9550 }