| blob | 7a83acfd0b40af7e24948e778b6a7f76544870f1 |
1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * T R A N S *
6 * *
7 * C Implementation File *
8 * *
9 * Copyright (C) 1992-2017, Free Software Foundation, Inc. *
10 * *
11 * GNAT is free software; you can redistribute it and/or modify it under *
12 * terms of the GNU General Public License as published by the Free Soft- *
13 * ware Foundation; either version 3, or (at your option) any later ver- *
14 * sion. GNAT is distributed in the hope that it will be useful, but WITH- *
15 * OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY *
16 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License *
17 * for more details. You should have received a copy of the GNU General *
18 * Public License 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 ****************************************************************************/
69 /* We should avoid allocating more than ALLOCA_THRESHOLD bytes via alloca,
70 for fear of running out of stack space. If we need more, we use xmalloc
71 instead. */
72 #define ALLOCA_THRESHOLD 1000
74 /* Pointers to front-end tables accessed through macros. */
85 /* Highest number in the front-end node table. */
88 /* Current node being treated, in case abort called. */
89 Node_Id error_gnat_node;
91 /* True when gigi is being called on an analyzed but unexpanded
92 tree, and the only purpose of the call is to properly annotate
93 types with representation information. */
96 /* List of N_Validate_Unchecked_Conversion nodes in the unit. */
99 /* When not optimizing, we cache the 'First, 'Last and 'Length attributes
100 of unconstrained array IN parameters to avoid emitting a great deal of
101 redundant instructions to recompute them each time. */
105 tree first;
106 tree last;
107 tree length;
108 };
115 bitmap named_ret_val;
118 };
120 #define f_parm_attr_cache \
121 DECL_STRUCT_FUNCTION (current_function_decl)->language->parm_attr_cache
123 #define f_named_ret_val \
124 DECL_STRUCT_FUNCTION (current_function_decl)->language->named_ret_val
126 #define f_other_ret_val \
127 DECL_STRUCT_FUNCTION (current_function_decl)->language->other_ret_val
129 #define f_gnat_ret \
130 DECL_STRUCT_FUNCTION (current_function_decl)->language->gnat_ret
132 /* A structure used to gather together information about a statement group.
133 We use this to gather related statements, for example the "then" part
134 of a IF. In the case where it represents a lexical scope, we may also
135 have a BLOCK node corresponding to it and/or cleanups. */
142 };
146 /* List of unused struct stmt_group nodes. */
149 /* A structure used to record information on elaboration procedures
150 we've made and need to process.
152 ??? gnat_node should be Node_Id, but gengtype gets confused. */
158 };
162 /* Stack of exception pointer variables. Each entry is the VAR_DECL
163 that stores the address of the raised exception. Nonzero means we
164 are in an exception handler. Not used in the zero-cost case. */
167 /* In ZCX case, current exception pointer. Used to re-raise it. */
170 /* Stack for storing the current elaboration procedure decl. */
173 /* Stack of labels to be used as a goto target instead of a return in
174 some functions. See processing for N_Subprogram_Body. */
177 /* Stack of variable for the return value of a function with copy-in/copy-out
178 parameters. See processing for N_Subprogram_Body. */
181 /* Structure used to record information for a range check. */
183 tree low_bound;
184 tree high_bound;
185 tree disp;
187 tree type;
188 tree invariant_cond;
189 tree inserted_cond;
190 };
195 /* Structure used to record information for a loop. */
197 tree stmt;
198 tree loop_var;
199 tree low_bound;
200 tree high_bound;
205 };
210 /* Stack of loop_info structures associated with LOOP_STMT nodes. */
213 /* The stacks for N_{Push,Pop}_*_Label. */
218 /* Map GNAT tree codes to GCC tree codes for simple expressions. */
253 /* Hooks for debug info back-ends, only supported and used in a restricted set
254 of configurations. */
257 \f
258 /* This is the main program of the back-end. It sets up all the table
259 structures and then generates code. */
261 void
274 Nat number_file,
276 Entity_Id standard_boolean,
277 Entity_Id standard_integer,
278 Entity_Id standard_character,
279 Entity_Id standard_long_long_float,
280 Entity_Id standard_exception_type,
281 Int gigi_operating_mode)
282 {
283 Node_Id gnat_iter;
284 Entity_Id gnat_literal;
304 {
305 /* Use the identifier table to make a permanent copy of the filename as
306 the name table gets reallocated after Gigi returns but before all the
307 debugging information is output. The __gnat_to_canonical_file_spec
308 call translates filenames from pragmas Source_Reference that contain
309 host style syntax not understood by gdb. */
311 = IDENTIFIER_POINTER
312 (get_identifier
313 (__gnat_to_canonical_file_spec
316 /* We rely on the order isomorphism between files and line maps. */
319 /* We create the line map for a source file at once, with a fixed number
320 of columns chosen to avoid jumping over the next power of 2. */
325 }
329 /* Declare the name of the compilation unit as the first global
330 name in order to make the middle-end fully deterministic. */
334 /* Initialize ourselves. */
339 /* If we are just annotating types, give VOID_TYPE zero sizes to avoid
340 errors. */
342 {
345 }
347 /* Enable GNAT stack checking method if needed */
351 /* Retrieve alignment settings. */
355 /* Record the builtin types. Define `integer' and `character' first so that
356 dbx will output them first. */
362 /* Save the type we made for integer as the type for Standard.Integer. */
367 /* Likewise for character as the type for Standard.Character. */
373 /* Likewise for boolean as the type for Standard.Boolean. */
392 /* Declare the building blocks of function nodes. */
397 /* Now declare run-time functions. */
398 malloc_decl
401 NULL_TREE),
406 free_decl
413 realloc_decl
417 NULL_TREE),
421 /* This is used for 64-bit multiplication with overflow checking. */
423 mulv64_decl
430 /* Name of the _Parent field in tagged record types. */
433 /* Name of the Exception_Data type defined in System.Standard_Library. */
434 exception_data_name_id
437 /* Make the types and functions used for exception processing. */
440 jmpbuf_type
446 /* Functions to get and set the jumpbuf pointer for the current thread. */
447 get_jmpbuf_decl
448 = create_subprog_decl
453 set_jmpbuf_decl
454 = create_subprog_decl
457 NULL_TREE),
460 get_excptr_decl
461 = create_subprog_decl
464 NULL_TREE),
470 {
473 }
476 /* setjmp returns an integer and has one operand, which is a pointer to
477 a jmpbuf. */
478 setjmp_decl
479 = create_subprog_decl
482 NULL_TREE),
487 /* update_setjmp_buf updates a setjmp buffer from the current stack pointer
488 address. */
489 update_setjmp_buf_decl
490 = create_subprog_decl
497 /* Indicate that it never returns. */
500 NULL_TREE);
502 raise_nodefer_decl
503 = create_subprog_decl
507 set_exception_parameter_decl
508 = create_subprog_decl
511 NULL_TREE),
514 /* Hooks to call when entering/leaving an exception handler. */
517 begin_handler_decl
521 Empty);
522 /* __gnat_begin_handler is a dummy procedure. */
525 end_handler_decl
529 Empty);
531 unhandled_except_decl
535 Empty);
537 /* Indicate that it never returns. */
539 reraise_zcx_decl
543 Empty);
545 /* Dummy objects to materialize "others" and "all others" in the exception
546 tables. These are exported by a-exexpr-gcc.adb, so see this unit for
547 the types to use. */
548 others_decl
555 all_others_decl
562 unhandled_others_decl
569 /* If in no exception handlers mode, all raise statements are redirected to
570 __gnat_last_chance_handler. No need to redefine raise_nodefer_decl since
571 this procedure will never be called in this mode. */
573 {
574 /* Indicate that it never returns. */
579 tree decl
580 = create_subprog_decl
583 Empty);
586 }
587 else
588 {
589 /* Otherwise, make one decl for each exception reason. */
595 i == CE_Index_Check_Failed
599 }
601 /* Build the special descriptor type and its null node if needed. */
603 {
615 {
616 tree field
623 elt--;
624 }
629 }
631 longest_float_type_node
636 /* If we are using the GCC exception mechanism, let GCC know. */
640 /* Initialize the GCC support for FP operations. */
643 /* Install the builtins we might need, either internally or as user-available
644 facilities for Intrinsic imports. Note that this must be done after the
645 GCC exception mechanism is initialized. */
654 /* Process any Pragma Ident for the main unit. */
659 /* Force -fno-strict-aliasing if the configuration pragma was seen. */
663 /* Save the current optimization options again after the above possible
664 global_options changes. */
668 /* Now translate the compilation unit proper. */
671 /* Disable -Waggressive-loop-optimizations since we implement our own
672 version of the warning. */
675 /* Then process the N_Validate_Unchecked_Conversion nodes. We do this at
676 the very end to avoid having to second-guess the front-end when we run
677 into dummy nodes during the regular processing. */
682 /* Finally see if we have any elaboration procedures to deal with. */
684 {
687 /* We should have a BIND_EXPR but it may not have any statements in it.
688 If it doesn't have any, we have nothing to do except for setting the
689 flag on the GNAT node. Otherwise, process the function as others. */
695 else
696 {
700 }
701 }
703 /* Destroy ourselves. */
707 /* We cannot track the location of errors past this point. */
709 }
710 \f
711 /* Return a subprogram decl corresponding to __gnat_rcheck_xx for the given
712 CHECK if KIND is EXCEPTION_SIMPLE, or else to __gnat_rcheck_xx_ext. */
714 static tree
716 {
725 {
727 ftype
731 }
732 else
733 {
738 ftype
743 }
745 /* Indicate that it never returns. */
747 result
753 }
754 \f
755 /* Return a positive value if an lvalue is required for GNAT_NODE, which is
756 an N_Attribute_Reference. */
758 static int
760 {
762 {
802 }
803 }
805 /* Return a positive value if an lvalue is required for GNAT_NODE. GNU_TYPE
806 is the type that will be used for GNAT_NODE in the translated GNU tree.
807 CONSTANT indicates whether the underlying object represented by GNAT_NODE
808 is constant in the Ada sense. If it is, ADDRESS_OF_CONSTANT indicates
809 whether its value is the address of a constant and ALIASED whether it is
810 aliased. If it isn't, ADDRESS_OF_CONSTANT and ALIASED are ignored.
812 The function climbs up the GNAT tree starting from the node and returns 1
813 upon encountering a node that effectively requires an lvalue downstream.
814 It returns int instead of bool to facilitate usage in non-purely binary
815 logic contexts. */
817 static int
820 {
824 {
834 /* If the parameter is by reference, an lvalue is required. */
840 /* Only the array expression can require an lvalue. */
844 /* ??? Consider that referencing an indexed component with a variable
845 index forces the whole aggregate to memory. Note that testing only
846 for literals is conservative, any static expression in the RM sense
847 could probably be accepted with some additional work. */
857 /* ... fall through ... */
860 /* Only the array expression can require an lvalue. */
874 /* We need to preserve addresses through a renaming. */
878 /* We cannot use a constructor if this is an atomic object because
879 the actual assignment might end up being done component-wise. */
883 /* We don't use a constructor if this is a class-wide object
884 because the effective type of the object is the equivalent
885 type of the class-wide subtype and it smashes most of the
886 data into an array of bytes to which we cannot convert. */
891 /* We cannot use a constructor if the LHS is an atomic object because
892 the actual assignment might end up being done component-wise. */
903 /* ... fall through ... */
907 /* We must look through all conversions because we may need to bypass
908 an intermediate conversion that is meant to be purely formal. */
914 /* We should only reach here through the N_Qualified_Expression case.
915 Force an lvalue for composite types since a block-copy to the newly
916 allocated area of memory is made. */
920 /* We look through dereferences for address of constant because we need
921 to handle the special cases listed above. */
927 /* ... fall through ... */
931 }
934 }
936 /* Return true if T is a constant DECL node that can be safely replaced
937 by its initializer. */
939 static bool
941 {
945 /* Return false for aggregate types that contain a placeholder since
946 their initializers cannot be manipulated easily. */
953 }
955 /* Return an expression equivalent to EXP but where constant DECL nodes
956 have been replaced by their initializer. */
958 static tree
960 {
962 tree op0;
965 {
991 /* If the index is not itself constant, then nothing can be folded. */
1012 }
1015 }
1017 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Identifier,
1018 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer
1019 to where we should place the result type. */
1021 static tree
1023 {
1027 /* Whether we should require an lvalue for GNAT_NODE. Needed in
1028 specific circumstances only, so evaluated lazily. < 0 means
1029 unknown, > 0 means known true, 0 means known false. */
1032 /* If GNAT_NODE is a constant, whether we should use the initialization
1033 value instead of the constant entity, typically for scalars with an
1034 address clause when the parent doesn't require an lvalue. */
1037 /* If the Etype of this node is not the same as that of the Entity, then
1038 something went wrong, probably in generic instantiation. However, this
1039 does not apply to types. Since we sometime have strange Ekind's, just
1040 do this test for objects. Moreover, if the Etype of the Entity is private
1041 or incomplete coming from a limited context, the Etype of the N_Identifier
1042 is allowed to be the full/non-limited view and we also consider a packed
1043 array type to be the same as the original type. Similarly, a CW type is
1044 equivalent to a subtype of itself. Finally, if the types are Itypes, one
1045 may be a copy of the other, which is also legal. */
1061 == Packed_Array_Impl_Type
1074 /* If this is a reference to a deferred constant whose partial view is an
1075 unconstrained private type, the proper type is on the full view of the
1076 constant, not on the full view of the type, which may be unconstrained.
1078 This may be a reference to a type, for example in the prefix of the
1079 attribute Position, generated for dispatching code (see Make_DT in
1080 exp_disp,adb). In that case we need the type itself, not is parent,
1081 in particular if it is a derived type */
1088 {
1091 }
1092 else
1093 {
1094 /* We want to use the Actual_Subtype if it has already been elaborated,
1095 otherwise the Etype. Avoid using Actual_Subtype for packed arrays to
1096 simplify things. */
1104 else
1106 }
1108 /* Expand the type of this identifier first, in case it is an enumeral
1109 literal, which only get made when the type is expanded. There is no
1110 order-of-elaboration issue here. */
1113 /* If this is a non-imported elementary constant with an address clause,
1114 retrieve the value instead of a pointer to be dereferenced unless
1115 an lvalue is required. This is generally more efficient and actually
1116 required if this is a static expression because it might be used
1117 in a context where a dereference is inappropriate, such as a case
1118 statement alternative or a record discriminant. There is no possible
1119 volatile-ness short-circuit here since Volatile constants must be
1120 imported per C.6. */
1125 {
1129 }
1132 {
1133 /* If this is a deferred constant, the initializer is attached to
1134 the full view. */
1139 }
1140 else
1143 /* Some objects (such as parameters passed by reference, globals of
1144 variable size, and renamed objects) actually represent the address
1145 of the object. In that case, we must do the dereference. Likewise,
1146 deal with parameters to foreign convention subprograms. */
1151 {
1154 /* If it's a PARM_DECL to foreign convention subprogram, convert it. */
1157 gnu_result
1160 /* If it's a CONST_DECL, return the underlying constant like below. */
1167 /* If it's a renaming pointer, get to the renamed object. */
1173 /* Otherwise, do the final dereference. */
1174 else
1175 {
1185 }
1186 }
1188 /* If we have a constant declaration and its initializer, try to return the
1189 latter to avoid the need to call fold in lots of places and the need for
1190 elaboration code if this identifier is used as an initializer itself. */
1192 {
1198 /* If there is a (corresponding) variable or this is the address of a
1199 constant, we only want to return the initializer if an lvalue isn't
1200 required. Evaluate this now if we have not already done so. */
1202 require_lvalue
1206 /* Finally retrieve the initializer if this is deemed valid. */
1209 }
1211 /* But for a constant renaming we couldn't do that incrementally for its
1212 definition because of the need to return an lvalue so, if the present
1213 context doesn't itself require an lvalue, we try again here. */
1217 {
1219 require_lvalue
1224 }
1226 /* The GNAT tree has the type of a function set to its result type, so we
1227 adjust here. Also use the type of the result if the Etype is a subtype
1228 that is nominally unconstrained. Likewise if this is a deferred constant
1229 of a discriminated type whose full view can be elaborated statically, to
1230 avoid problematic conversions to the nominal subtype. But remove any
1231 padding from the resulting type. */
1238 {
1242 }
1247 }
1248 \f
1249 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Pragma. Return
1250 any statements we generate. */
1252 static tree
1254 {
1257 Node_Id gnat_temp;
1259 /* Do nothing if we are just annotating types and check for (and ignore)
1260 unrecognized pragmas. */
1267 {
1269 /* Do nothing at top level: all such variables are already viewable. */
1276 {
1280 machine_mode mode;
1281 scalar_int_mode int_mode;
1283 #ifdef ASM_COMMENT_START
1285 #endif
1290 /* Use the value only if it fits into a normal register,
1291 otherwise use the address. */
1299 #ifdef ASM_COMMENT_START
1305 NULL);
1308 #endif
1310 asm_constraint,
1311 NULL_TREE,
1312 tree_cons
1320 }
1327 {
1331 {
1354 }
1355 }
1361 {
1379 }
1389 {
1390 Node_Id gnat_expr;
1391 /* Preserve the location of the pragma. */
1395 diagnostic_t kind;
1400 /* This is the String form: pragma Warning{s|_As_Error}(String). */
1402 {
1404 {
1417 }
1420 }
1422 /* This is the On/Off form: pragma Warnings (On | Off [,String]). */
1424 {
1426 {
1437 }
1439 /* Deal with optional pattern (but ignore Reason => "..."). */
1442 {
1443 /* pragma Warnings (On | Off, Name) is handled differently. */
1448 }
1449 else
1453 }
1455 else
1458 /* This is the same implementation as in the C family of compilers. */
1462 {
1470 {
1473 }
1475 {
1478 }
1480 {
1483 }
1486 }
1487 else
1494 }
1499 }
1502 }
1503 \f
1505 /* Check the inline status of nested function FNDECL wrt its parent function.
1507 If a non-inline nested function is referenced from an inline external
1508 function, we cannot honor both requests at the same time without cloning
1509 the nested function in the current unit since it is private to its unit.
1510 We could inline it as well but it's probably better to err on the side
1511 of too little inlining.
1513 This must be done only on nested functions present in the source code
1514 and not on nested functions generated by the compiler, e.g. finalizers,
1515 because they may be not marked inline and we don't want them to block
1516 the inlining of the parent function. */
1518 static void
1520 {
1529 {
1534 {
1537 }
1538 else
1539 {
1541 fndecl);
1543 }
1547 }
1548 }
1549 \f
1550 /* Return an expression for the length of TYPE, an integral type, computed in
1551 RESULT_TYPE, another integral type.
1553 We used to compute the length as MAX (hb - lb + 1, 0) which could overflow
1554 when lb == TYPE'First. We now compute it as (hb >= lb) ? hb - lb + 1 : 0
1555 which would only overflow in much rarer cases, for extremely large arrays
1556 we expect never to encounter in practice. Besides, the former computation
1557 required the use of potentially constraining signed arithmetics while the
1558 latter does not. Note that the comparison must be done in the original
1559 base index type in order to avoid any overflow during the conversion. */
1561 static tree
1563 {
1568 tree length
1574 length
1580 }
1582 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Attribute node,
1583 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to
1584 where we should place the result type. ATTRIBUTE is the attribute ID. */
1586 static tree
1588 {
1595 /* If the input is a NULL_EXPR, make a new one. */
1597 {
1601 }
1604 {
1607 /* These are just conversions since representation clauses for
1608 enumeration types are handled in the front-end. */
1618 /* These just add or subtract the constant 1 since representation
1619 clauses for enumeration types are handled in the front-end. */
1625 gnu_result
1632 /* Conversions don't change the address of references but can cause
1633 build_unary_op to miss the references below, so strip them off.
1634 On the contrary, if the address-of operation causes a temporary
1635 to be created, then it must be created with the proper type. */
1641 /* If we are taking 'Address of an unconstrained object, this is the
1642 pointer to the underlying array. */
1646 /* If we are building a static dispatch table, we have to honor
1647 TARGET_VTABLE_USES_DESCRIPTORS if we want to be compatible
1648 with the C++ ABI. We do it in the non-static case as well,
1649 see gnat_to_gnu_entity, case E_Access_Subprogram_Type. */
1652 {
1654 /* Descriptors can only be built here for top-level functions. */
1662 /* If we're not going to build the descriptor, we have to retrieve
1663 the one which will be built by the linker (or by the compiler
1664 later if a static chain is requested). */
1666 {
1669 gnu_result);
1671 }
1678 {
1680 {
1684 }
1685 else
1691 elt--;
1692 }
1696 }
1698 /* ... fall through ... */
1704 gnu_result
1711 /* For 'Code_Address, find an inner ADDR_EXPR and mark it so that we
1712 don't try to build a trampoline. */
1714 {
1720 /* On targets for which function symbols denote a descriptor, the
1721 code address is stored within the first slot of the descriptor
1722 so we do an additional dereference:
1723 result = *((result_type *) result)
1724 where we expect result to be of some pointer type already. */
1726 gnu_result
1729 gnu_result));
1730 }
1732 /* For 'Access, issue an error message if the prefix is a C++ method
1733 since it can use a special calling convention on some platforms,
1734 which cannot be propagated to the access type. */
1739 gnat_node);
1741 /* For other address attributes applied to a nested function,
1742 find an inner ADDR_EXPR and annotate it so that we can issue
1743 a useful warning with -Wtrampolines. */
1745 {
1750 {
1753 /* Also check the inlining status. */
1756 /* Moreover, for 'Access or 'Unrestricted_Access with non-
1757 foreign-compatible representation, mark the ADDR_EXPR so
1758 that we can build a descriptor instead of a trampoline. */
1765 /* Otherwise, we need to check that we are not violating the
1766 No_Implicit_Dynamic_Code restriction. */
1769 }
1770 }
1774 {
1776 tree gnu_obj_type;
1780 /* If this is fat pointer, the object must have been allocated with the
1781 template in front of the array. So compute the template address; do
1782 it by converting to a thin pointer. */
1784 gnu_ptr
1786 (TYPE_OBJECT_RECORD_TYPE
1788 gnu_ptr);
1792 /* If this is a thin pointer, the object must have been allocated with
1793 the template in front of the array. So compute the template address
1794 and return it. */
1796 gnu_ptr
1798 gnu_ptr,
1800 byte_position
1801 (DECL_CHAIN
1805 }
1814 /* Remove NOPs and conversions between original and packable version
1815 from GNU_EXPR, and conversions from GNU_PREFIX. We use GNU_EXPR
1816 to see if a COMPONENT_REF was involved. */
1821 == RECORD_TYPE
1830 /* Replace an unconstrained array type with the type of the underlying
1831 array. We can't do this with a call to maybe_unconstrained_array
1832 since we may have a TYPE_DECL. For 'Max_Size_In_Storage_Elements,
1833 use the record type that will be used to allocate the object and its
1834 template. */
1836 {
1840 }
1842 /* If we're looking for the size of a field, return the field size. */
1846 /* Otherwise, if the prefix is an object, or if we are looking for
1847 'Object_Size or 'Max_Size_In_Storage_Elements, the result is the
1848 GCC size of the type. We make an exception for padded objects,
1849 as we do not take into account alignment promotions for the size.
1850 This is in keeping with the object case of gnat_to_gnu_entity. */
1856 {
1857 /* If this is a dereference and we have a special dynamic constrained
1858 subtype on the prefix, use it to compute the size; otherwise, use
1859 the designated subtype. */
1861 {
1862 Node_Id gnat_actual_subtype
1864 tree gnu_ptr_type
1869 {
1870 tree gnu_actual_obj_type
1872 gnu_type
1874 gnu_actual_obj_type,
1877 }
1878 }
1881 }
1883 /* Otherwise, the result is the RM size of the type. */
1884 else
1887 /* Deal with a self-referential size by returning the maximum size for
1888 a type and by qualifying the size with the object otherwise. */
1890 {
1893 else
1895 }
1897 /* If the type contains a template, subtract its size. */
1903 /* For 'Max_Size_In_Storage_Elements, adjust the unit. */
1911 {
1924 else
1925 {
1930 /* If the default alignment of "double" or larger scalar types is
1931 specifically capped and there is an alignment clause neither
1932 on the type nor on the prefix itself, return the cap. */
1934 is_capped_double
1937 is_capped_double
1939 else
1949 else
1951 }
1954 }
1963 {
1970 else
1973 }
1975 /* ... fall through ... */
1978 {
1986 /* Make sure any implicit dereference gets done. */
1990 /* We treat unconstrained array In parameters specially. We also note
1991 whether we are dereferencing a pointer to unconstrained array. */
1994 {
1996 /* This is the direct case. */
2002 /* This is the indirect case. Note that we need to be sure that
2003 the access value cannot be null as we'll hoist the load. */
2006 {
2009 }
2010 else
2016 }
2018 /* If the prefix is the view conversion of a constrained array to an
2019 unconstrained form, we retrieve the constrained array because we
2020 might not be able to substitute the PLACEHOLDER_EXPR coming from
2021 the conversion. This can occur with the 'Old attribute applied
2022 to a parameter with an unconstrained type, which gets rewritten
2023 into a constrained local variable very late in the game. */
2026 && !CONTAINS_PLACEHOLDER_P
2029 else
2036 {
2038 tree gnu_type_temp;
2044 ;
2047 }
2054 /* When not optimizing, look up the slot associated with the parameter
2055 and the dimension in the cache and create a new one on failure.
2056 Don't do this when the actual subtype needs debug info (this happens
2057 with -gnatD): in elaborate_expression_1, we create variables that
2058 hold the bounds, so caching attributes isn't very interesting and
2059 causes dependency issues between these variables and cached
2060 expressions. */
2065 {
2071 {
2076 }
2077 }
2079 /* Return the cached expression or build a new one. */
2081 {
2083 {
2086 }
2088 gnu_result
2090 }
2093 {
2095 {
2098 }
2100 gnu_result
2102 }
2105 {
2107 {
2110 }
2112 gnu_result
2114 gnu_result_type);
2115 }
2117 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2118 handling. Note that these attributes could not have been used on
2119 an unconstrained array type. */
2122 /* Cache the expression we have just computed. Since we want to do it
2123 at run time, we force the use of a SAVE_EXPR and let the gimplifier
2124 create the temporary in the outermost binding level. We will make
2125 sure in Subprogram_Body_to_gnu that it is evaluated on all possible
2126 paths by forcing its evaluation on entry of the function. */
2128 {
2129 gnu_result
2132 {
2148 }
2149 }
2151 /* Otherwise, evaluate it each time it is referenced. */
2152 else
2154 {
2157 /* If we are dereferencing a pointer to unconstrained array, we
2158 need to capture the value because the pointed-to bounds may
2159 subsequently be released. */
2161 gnu_result
2167 /* Set the source location onto the predicate of the condition
2168 but not if the expression is cached to avoid messing up the
2169 debug info. */
2173 gnat_node);
2178 }
2181 }
2188 {
2189 HOST_WIDE_INT bitsize;
2190 HOST_WIDE_INT bitpos;
2191 tree gnu_offset;
2192 tree gnu_field_bitpos;
2193 tree gnu_field_offset;
2194 tree gnu_inner;
2195 machine_mode mode;
2202 /* We can have 'Bit on any object, but if it isn't a COMPONENT_REF,
2203 the result is 0. Don't allow 'Bit on a bare component, though. */
2207 {
2210 }
2212 else
2221 {
2229 {
2230 gnu_field_bitpos
2233 gnu_field_offset
2236 }
2237 }
2239 {
2242 }
2243 else
2244 {
2247 }
2250 {
2264 /* ??? Avoid a large unsigned result that will overflow when
2265 converted to the signed universal_integer. */
2268 else
2269 gnu_result
2276 }
2278 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2279 handling. */
2282 }
2286 {
2292 /* The result of {MIN,MAX}_EXPR is unspecified if either operand is
2293 a NaN so we implement the semantics of C99 f{min,max} to make it
2294 predictable in this case: if either operand is a NaN, the other
2295 is returned; if both operands are NaN's, a NaN is returned. */
2298 {
2304 /* If the operands have side-effects, they need to be evaluated
2305 only once in spite of the multiple references in the result. */
2313 integer_zero_node);
2317 integer_zero_node);
2327 /* If the operands have side-effects, they need to be evaluated
2328 before doing the tests above since the place they otherwise
2329 would end up being evaluated at run time could be wrong. */
2331 gnu_result
2335 gnu_result
2337 }
2338 else
2342 }
2368 /* Note this size cannot be self-referential. */
2378 /* What we want is the offset of the ARRAY field in the record
2379 that the thin pointer designates. */
2387 /* This is just a zero cast to the pointer type for our prefix and
2388 dereferenced. */
2390 gnu_result
2393 integer_zero_node));
2398 {
2405 {
2410 ;
2411 }
2419 && (DECL_BY_COMPONENT_PTR_P
2423 }
2427 /* We treat Model as identical to Machine. This is true for at least
2428 IEEE and some other nice floating-point systems. */
2430 /* ... fall through ... */
2433 /* The trick is to force the compiler to store the result in memory so
2434 that we do not have extra precision used. But do this only when this
2435 is necessary, i.e. if FP_ARITH_MAY_WIDEN is true and the precision of
2436 the type is lower than that of the longest floating-point type. */
2443 && fp_arith_may_widen
2446 {
2448 tree field
2458 asm_expr
2470 gnu_result
2474 }
2481 /* This can be a random address so build an alias-all pointer type. */
2482 gnu_expr
2485 gnu_expr);
2490 /* This abort means that we have an unimplemented attribute. */
2492 }
2494 /* If this is an attribute where the prefix was unused, force a use of it if
2495 it has a side-effect. But don't do it if the prefix is just an entity
2496 name. However, if an access check is needed, we must do it. See second
2497 example in AARM 11.6(5.e). */
2501 gnu_result
2506 }
2507 \f
2508 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Case_Statement,
2509 to a GCC tree, which is returned. */
2511 static tree
2513 {
2515 Node_Id gnat_when;
2516 location_t end_locus;
2524 /* We build a SWITCH_EXPR that contains the code with interspersed
2525 CASE_LABEL_EXPRs for each label. */
2534 {
2536 Node_Id gnat_choice;
2538 /* First compile all the different case choices for the current WHEN
2539 alternative. */
2543 {
2548 {
2563 /* This represents either a subtype range or a static value of
2564 some kind; Ekind says which. */
2566 {
2572 }
2574 /* ... fall through ... */
2586 }
2588 /* Everything should be folded into constants at this point. */
2598 gnat_choice);
2600 }
2602 /* This construct doesn't define a scope so we shouldn't push a binding
2603 level around the statement list. Except that we have always done so
2604 historically and this makes it possible to reduce stack usage. As a
2605 compromise, we keep doing it for case statements, for which this has
2606 never been problematic, but not for case expressions in Ada 2012. */
2608 {
2609 const bool is_case_expression
2611 tree group
2616 {
2621 }
2622 }
2623 }
2625 /* Now emit a definition of the label the cases branch to, if any. */
2631 }
2632 \f
2633 /* Return true if we are in the body of a loop. */
2637 {
2639 }
2641 /* Find out whether EXPR is a simple additive expression based on the iteration
2642 variable of some enclosing loop in the current function. If so, return the
2643 loop and set *DISP to the displacement and *NEG_P to true if this is for a
2644 subtraction; otherwise, return NULL. */
2648 {
2655 {
2661 }
2662 else
2663 {
2669 }
2686 }
2688 /* Return true if VAL (of type TYPE) can equal the minimum value if MAX is
2689 false, or the maximum value if MAX is true, of TYPE. */
2691 static bool
2693 {
2700 val = (max
2709 else
2711 }
2713 /* Return true if VAL (of type TYPE) can equal the minimum value of TYPE.
2714 If REVERSE is true, minimum value is taken as maximum value. */
2718 {
2720 }
2722 /* Return true if VAL (of type TYPE) can equal the maximum value of TYPE.
2723 If REVERSE is true, maximum value is taken as minimum value. */
2727 {
2729 }
2731 /* Return true if VAL1 can be lower than VAL2. */
2733 static bool
2735 {
2749 }
2751 /* Replace EXPR1 and EXPR2 by invariant expressions if possible. Return
2752 true if both expressions have been replaced and false otherwise. */
2754 static bool
2756 {
2767 }
2769 /* Helper function for walk_tree, used by independent_iterations_p below. */
2771 static tree
2773 {
2777 /* No need to walk into types or decls. */
2785 }
2787 /* Return true if STMT_LIST generates independent iterations in a loop. */
2789 static bool
2791 {
2792 tree_stmt_iterator tsi;
2795 tree iter;
2801 /* Scan the list and return false on anything that is not either a check
2802 or an assignment to a parameter with restricted aliasing. */
2804 {
2808 {
2810 {
2819 }
2822 {
2835 }
2839 }
2840 }
2842 /* At this point we know that the list contains only statements that will
2843 modify parameters with restricted aliasing. Check that the statements
2844 don't at the time read from these parameters. */
2850 }
2852 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Loop_Statement,
2853 to a GCC tree, which is returned. */
2855 static tree
2857 {
2864 tree gnu_result;
2866 /* Push the loop_info structure associated with the LOOP_STMT. */
2869 /* Set location information for statement and end label. */
2875 /* Save the statement for later reuse. */
2879 /* Set the condition under which the loop must keep going.
2880 For the case "LOOP .... END LOOP;" the condition is always true. */
2882 ;
2884 /* For the case "WHILE condition LOOP ..... END LOOP;" it's immediate. */
2889 /* Otherwise we have an iteration scheme and the condition is given by the
2890 bounds of the subtype of the iteration variable. */
2891 else
2892 {
2906 /* We must disable modulo reduction for the iteration variable, if any,
2907 in order for the loop comparison to be effective. */
2909 {
2915 }
2916 else
2917 {
2923 }
2925 /* We use two different strategies to translate the loop, depending on
2926 whether optimization is enabled.
2928 If it is, we generate the canonical loop form expected by the loop
2929 optimizer and the loop vectorizer, which is the do-while form:
2931 ENTRY_COND
2932 loop:
2933 TOP_UPDATE
2934 BODY
2935 BOTTOM_COND
2936 GOTO loop
2938 This avoids an implicit dependency on loop header copying and makes
2939 it possible to turn BOTTOM_COND into an inequality test.
2941 If optimization is disabled, loop header copying doesn't come into
2942 play and we try to generate the loop form with the fewer conditional
2943 branches. First, the default form, which is:
2945 loop:
2946 TOP_COND
2947 BODY
2948 BOTTOM_UPDATE
2949 GOTO loop
2951 It should catch most loops with constant ending point. Then, if we
2952 cannot, we try to generate the shifted form:
2954 loop:
2955 TOP_COND
2956 TOP_UPDATE
2957 BODY
2958 GOTO loop
2960 which should catch loops with constant starting point. Otherwise, if
2961 we cannot, we generate the fallback form:
2963 ENTRY_COND
2964 loop:
2965 BODY
2966 BOTTOM_COND
2967 BOTTOM_UPDATE
2968 GOTO loop
2970 which works in all cases. */
2973 {
2974 /* We can use the do-while form directly if GNU_FIRST-1 doesn't
2975 overflow. */
2977 ;
2979 /* Otherwise, use the do-while form with the help of a special
2980 induction variable in the unsigned version of the base type
2981 or the unsigned version of the size type, whichever is the
2982 largest, in order to have wrap-around arithmetics for it. */
2983 else
2984 {
2987 gnu_base_type
2989 else
2996 }
2998 gnu_first
3000 gnu_one_node);
3003 }
3004 else
3005 {
3006 /* We can use the default form if GNU_LAST+1 doesn't overflow. */
3008 ;
3010 /* Otherwise, we can use the shifted form if neither GNU_FIRST-1 nor
3011 GNU_LAST-1 does. */
3014 {
3015 gnu_first
3017 gnu_one_node);
3018 gnu_last
3020 gnu_one_node);
3022 }
3024 /* Otherwise, use the fallback form. */
3025 else
3027 }
3029 /* If we use the BOTTOM_COND, we can turn the test into an inequality
3030 test but we may have to add ENTRY_COND to protect the empty loop. */
3032 {
3035 {
3036 gnu_cond_expr
3042 }
3043 }
3045 /* Open a new nesting level that will surround the loop to declare the
3046 iteration variable. */
3050 /* If we use the special induction variable, create it and set it to
3051 its initial value. Morever, the regular iteration variable cannot
3052 itself be initialized, lest the initial value wrapped around. */
3054 {
3055 gnu_loop_iv
3059 }
3060 else
3063 /* Declare the iteration variable and set it to its initial value. */
3068 {
3071 }
3076 /* Do all the arithmetics in the base type. */
3079 /* Set either the top or bottom exit condition. */
3083 gnu_last);
3084 else
3087 gnu_last);
3089 /* Set either the top or bottom update statement and give it the source
3090 location of the iteration for better coverage info. */
3092 {
3093 gnu_stmt
3100 gnu_stmt
3102 gnu_loop_iv);
3106 }
3107 else
3108 {
3109 gnu_stmt
3115 }
3116 }
3118 /* If the loop was named, have the name point to this loop. In this case,
3119 the association is not a DECL node, but the end label of the loop. */
3123 /* Make the loop body into its own block, so any allocated storage will be
3124 released every iteration. This is needed for stack allocation. */
3129 /* If we have an iteration scheme, then we are in a statement group. Add
3130 the LOOP_STMT to it, finish it and make it the "loop". */
3132 {
3133 /* First, if we have computed invariant conditions for range (or index)
3134 checks applied to the iteration variable, find out whether they can
3135 be evaluated to false at compile time; otherwise, if there are not
3136 too many of them, combine them with the original checks. If loop
3137 unswitching is enabled, do not require the loop bounds to be also
3138 invariant, as their evaluation will still be ahead of the loop. */
3141 {
3146 {
3150 {
3153 gnu_adjusted_low
3156 low_ok
3159 }
3160 else
3164 {
3167 gnu_adjusted_high
3170 high_ok
3173 }
3174 else
3177 tree range_ok
3181 rci->invariant_cond
3186 else
3187 n_remaining_checks++;
3188 }
3190 /* Note that loop unswitching can only be applied a small number of
3191 times to a given loop (PARAM_MAX_UNSWITCH_LEVEL default to 3). */
3196 {
3201 }
3202 }
3204 /* Second, if loop vectorization is enabled and the iterations of the
3205 loop can easily be proved as independent, mark the loop. */
3207 && flag_tree_loop_vectorize
3214 }
3216 /* If we have an outer COND_EXPR, that's our result and this loop is its
3217 "true" statement. Otherwise, the result is the LOOP_STMT. */
3219 {
3223 }
3224 else
3230 }
3231 \f
3232 /* This page implements a form of Named Return Value optimization modelled
3233 on the C++ optimization of the same name. The main difference is that
3234 we disregard any semantical considerations when applying it here, the
3235 counterpart being that we don't try to apply it to semantically loaded
3236 return types, i.e. types with the TYPE_BY_REFERENCE_P flag set.
3238 We consider a function body of the following GENERIC form:
3240 return_type R1;
3241 [...]
3242 RETURN_EXPR [<retval> = ...]
3243 [...]
3244 RETURN_EXPR [<retval> = R1]
3245 [...]
3246 return_type Ri;
3247 [...]
3248 RETURN_EXPR [<retval> = ...]
3249 [...]
3250 RETURN_EXPR [<retval> = Ri]
3251 [...]
3253 where the Ri are not addressable and we try to fulfill a simple criterion
3254 that would make it possible to replace one or several Ri variables by the
3255 single RESULT_DECL of the function.
3257 The first observation is that RETURN_EXPRs that don't directly reference
3258 any of the Ri variables on the RHS of their assignment are transparent wrt
3259 the optimization. This is because the Ri variables aren't addressable so
3260 any transformation applied to them doesn't affect the RHS; moreover, the
3261 assignment writes the full <retval> object so existing values are entirely
3262 discarded.
3264 This property can be extended to some forms of RETURN_EXPRs that reference
3265 the Ri variables, for example CONSTRUCTORs, but isn't true in the general
3266 case, in particular when function calls are involved.
3268 Therefore the algorithm is as follows:
3270 1. Collect the list of candidates for a Named Return Value (Ri variables
3271 on the RHS of assignments of RETURN_EXPRs) as well as the list of the
3272 other expressions on the RHS of such assignments.
3274 2. Prune the members of the first list (candidates) that are referenced
3275 by a member of the second list (expressions).
3277 3. Extract a set of candidates with non-overlapping live ranges from the
3278 first list. These are the Named Return Values.
3280 4. Adjust the relevant RETURN_EXPRs and replace the occurrences of the
3281 Named Return Values in the function with the RESULT_DECL.
3283 If the function returns an unconstrained type, things are a bit different
3284 because the anonymous return object is allocated on the secondary stack
3285 and RESULT_DECL is only a pointer to it. Each return object can be of a
3286 different size and is allocated separately so we need not care about the
3287 addressability and the aforementioned overlapping issues. Therefore, we
3288 don't collect the other expressions and skip step #2 in the algorithm. */
3290 struct nrv_data
3291 {
3292 bitmap nrv;
3293 tree result;
3294 Node_Id gnat_ret;
3296 };
3298 /* Return true if T is a Named Return Value. */
3302 {
3304 }
3306 /* Helper function for walk_tree, used by finalize_nrv below. */
3308 static tree
3310 {
3314 /* No need to walk into types or decls. */
3322 }
3324 /* Prune Named Return Values in BLOCK and return true if there is still a
3325 Named Return Value in BLOCK or one of its sub-blocks. */
3327 static bool
3329 {
3331 tree t;
3333 /* First recurse on the sub-blocks. */
3337 /* Then make sure to keep at most one NRV per block. */
3340 {
3343 else
3345 }
3348 }
3350 /* Helper function for walk_tree, used by finalize_nrv below. */
3352 static tree
3354 {
3358 /* No need to walk into types. */
3362 /* Change RETURN_EXPRs of NRVs to just refer to the RESULT_DECL; this is a
3363 nop, but differs from using NULL_TREE in that it indicates that we care
3364 about the value of the RESULT_DECL. */
3367 {
3370 /* Strip useless conversions around the return value. */
3376 }
3378 /* Replace the DECL_EXPR of NRVs with an initialization of the RESULT_DECL,
3379 if needed. */
3382 {
3386 {
3391 }
3392 else
3396 /* Identify the NRV to the RESULT_DECL for debugging purposes. */
3399 /* ??? Kludge to avoid an assertion failure during inlining. */
3402 }
3404 /* And replace all uses of NRVs with the RESULT_DECL. */
3408 /* Avoid walking into the same tree more than once. Unfortunately, we
3409 can't just use walk_tree_without_duplicates because it would only
3410 call us for the first occurrence of NRVs in the function body. */
3415 }
3417 /* Likewise, but used when the function returns an unconstrained type. */
3419 static tree
3421 {
3425 /* No need to walk into types. */
3429 /* We need to see the DECL_EXPR of NRVs before any other references so we
3430 walk the body of BIND_EXPR before walking its variables. */
3434 /* Change RETURN_EXPRs of NRVs to assign to the RESULT_DECL only the final
3435 return value built by the allocator instead of the whole construct. */
3438 {
3441 /* This is the construct returned by the allocator. */
3444 {
3449 else
3451 }
3453 /* Strip useless conversions around the return value. */
3458 /* Strip unpadding around the return value. */
3463 /* Assign the new return value to the RESULT_DECL. */
3467 }
3469 /* Adjust the DECL_EXPR of NRVs to call the allocator and save the result
3470 into a new variable. */
3473 {
3480 /* Create an artificial context to build the allocation. */
3485 /* This will return a COMPOUND_EXPR with the allocation in the first
3486 arm and the final return value in the second arm. */
3493 /* The new variable is built as a reference to the allocated space. */
3494 new_var
3500 {
3503 /* The new initial value is a COMPOUND_EXPR with the allocation in
3504 the first arm and the value of P_ARRAY in the second arm. */
3510 /* Build a modified CONSTRUCTOR that references NEW_VAR. */
3517 }
3518 else
3519 {
3520 /* The new initial value is just the allocation. */
3523 }
3527 /* Destroy the artificial context and insert the new statements. */
3532 /* Chain NEW_VAR immediately after VAR and ignore the latter. */
3537 /* Save the new return value and the dereference of NEW_VAR. */
3541 /* ??? Kludge to avoid messing up during inlining. */
3543 }
3545 /* And replace all uses of NRVs with the dereference of NEW_VAR. */
3549 /* Avoid walking into the same tree more than once. Unfortunately, we
3550 can't just use walk_tree_without_duplicates because it would only
3551 call us for the first occurrence of NRVs in the function body. */
3556 }
3558 /* Finalize the Named Return Value optimization for FNDECL. The NRV bitmap
3559 contains the candidates for Named Return Value and OTHER is a list of
3560 the other return values. GNAT_RET is a representative return node. */
3562 static void
3564 {
3567 walk_tree_fn func;
3569 tree iter;
3571 /* We shouldn't be applying the optimization to return types that we aren't
3572 allowed to manipulate freely. */
3575 /* Prune the candidates that are referenced by other return values. */
3585 /* Prune also the candidates that are referenced by nested functions. */
3593 /* Extract a set of NRVs with non-overlapping live ranges. */
3597 /* Adjust the relevant RETURN_EXPRs and replace the occurrences of NRVs. */
3604 else
3608 }
3610 /* Return true if RET_VAL can be used as a Named Return Value for the
3611 anonymous return object RET_OBJ. */
3613 static bool
3615 {
3628 /* For the constrained case, test for addressability. */
3632 /* For the constrained case, test for overalignment. */
3636 /* For the unconstrained case, test for bogus initialization. */
3643 }
3645 /* Build a RETURN_EXPR. If RET_VAL is non-null, build a RETURN_EXPR around
3646 the assignment of RET_VAL to RET_OBJ. Otherwise build a bare RETURN_EXPR
3647 around RESULT_OBJ, which may be null in this case. */
3649 static tree
3651 {
3652 tree result_expr;
3655 {
3656 /* The gimplifier explicitly enforces the following invariant:
3658 RETURN_EXPR
3659 |
3660 INIT_EXPR
3661 / \
3662 / \
3663 RET_OBJ ...
3665 As a consequence, type consistency dictates that we use the type
3666 of the RET_OBJ as the operation type. */
3669 /* Convert the right operand to the operation type. Note that this is
3670 the transformation applied in the INIT_EXPR case of build_binary_op,
3671 with the assumption that the type cannot involve a placeholder. */
3675 /* We always can use an INIT_EXPR for the return object. */
3678 /* If the function returns an aggregate type, find out whether this is
3679 a candidate for Named Return Value. If so, record it. Otherwise,
3680 if this is an expression of some kind, record it elsewhere. */
3686 {
3687 /* Strip useless conversions around the return value. */
3691 /* Now apply the test to the return value. */
3693 {
3697 }
3699 /* Note that we need not care about CONSTRUCTORs here, as they are
3700 totally transparent given the read-compose-write semantics of
3701 assignments from CONSTRUCTORs. */
3704 }
3705 }
3706 else
3710 }
3711 \f
3712 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Subprogram_Body. We
3713 don't return anything. */
3715 static void
3717 {
3718 /* Defining identifier of a parameter to the subprogram. */
3719 Entity_Id gnat_param;
3720 /* The defining identifier for the subprogram body. Note that if a
3721 specification has appeared before for this body, then the identifier
3722 occurring in that specification will also be a defining identifier and all
3723 the calls to this subprogram will point to that specification. */
3724 Entity_Id gnat_subprog_id
3727 /* The FUNCTION_DECL node corresponding to the subprogram spec. */
3728 tree gnu_subprog_decl;
3729 /* Its RESULT_DECL node. */
3730 tree gnu_result_decl;
3731 /* Its FUNCTION_TYPE node. */
3732 tree gnu_subprog_type;
3733 /* The TYPE_CI_CO_LIST of its FUNCTION_TYPE node, if any. */
3734 tree gnu_cico_list;
3735 /* The entry in the CI_CO_LIST that represents a function return, if any. */
3737 tree gnu_result;
3738 location_t locus;
3742 /* If this is a generic object or if it has been eliminated,
3743 ignore it. */
3749 /* If this subprogram acts as its own spec, define it. Otherwise, just get
3750 the already-elaborated tree node. However, if this subprogram had its
3751 elaboration deferred, we will already have made a tree node for it. So
3752 treat it as not being defined in that case. Such a subprogram cannot
3753 have an address clause or a freeze node, so this test is safe, though it
3754 does disable some otherwise-useful error checking. */
3755 gnu_subprog_decl
3766 /* If the function returns by invisible reference, make it explicit in the
3767 function body. See gnat_to_gnu_entity, E_Subprogram_Type case. */
3769 {
3773 }
3775 /* Set the line number in the decl to correspond to that of the body. */
3779 /* If the body comes from an expression function, arrange it to be inlined
3780 in almost all cases. */
3784 /* Initialize the information structure for the function. */
3793 /* If there are copy-in/copy-out parameters, we need to ensure that they are
3794 properly copied out by the return statement. We do this by making a new
3795 block and converting any return into a goto to a label at the end of the
3796 block. */
3798 {
3807 /* If this is a function with copy-in/copy-out parameters and which does
3808 not return by invisible reference, we also need a variable for the
3809 return value to be placed. */
3811 {
3812 tree gnu_return_type
3815 gnu_return_var
3821 }
3825 /* See whether there are parameters for which we don't have a GCC tree
3826 yet. These must be Out parameters. Make a VAR_DECL for them and
3827 put it into TYPE_CI_CO_LIST, which must contain an empty entry too.
3828 We can match up the entries because TYPE_CI_CO_LIST is in the order
3829 of the parameters. */
3834 {
3836 tree gnu_decl;
3838 /* Skip any entries that have been already filled in; they must
3839 correspond to In Out parameters. */
3843 /* Do any needed dereferences for by-ref objects. */
3849 /* Do any needed references for padded types. */
3852 }
3853 }
3854 else
3857 /* Get a tree corresponding to the code for the subprogram. */
3863 /* Generate the code of the subprogram itself. A return statement will be
3864 present and any Out parameters will be handled there. */
3869 /* If we populated the parameter attributes cache, we need to make sure that
3870 the cached expressions are evaluated on all the possible paths leading to
3871 their uses. So we force their evaluation on entry of the function. */
3874 {
3881 {
3888 }
3894 }
3896 /* If we are dealing with a return from an Ada procedure with parameters
3897 passed by copy-in/copy-out, we need to return a record containing the
3898 final values of these parameters. If the list contains only one entry,
3899 return just that entry though.
3901 For a full description of the copy-in/copy-out parameter mechanism, see
3902 the part of the gnat_to_gnu_entity routine dealing with the translation
3903 of subprograms.
3905 We need to make a block that contains the definition of that label and
3906 the copying of the return value. It first contains the function, then
3907 the label and copy statement. */
3909 {
3910 const Node_Id gnat_end_label
3919 /* If this is a function which returns by invisible reference, the
3920 return value has already been dealt with at the return statements,
3921 so we only need to indirectly copy out the parameters. */
3923 {
3924 tree gnu_ret_deref
3926 tree t;
3931 {
3932 tree gnu_field_deref
3937 }
3938 }
3940 /* Otherwise, if this is a procedure or a function which does not return
3941 by invisible reference, we can do a direct block-copy out. */
3942 else
3943 {
3944 tree gnu_retval;
3948 else
3949 gnu_retval
3951 gnu_cico_list);
3955 }
3959 }
3963 /* Attempt setting the end_locus of our GCC body tree, typically a
3964 BIND_EXPR or STATEMENT_LIST, then the end_locus of our GCC subprogram
3965 declaration tree. */
3969 /* On SEH targets, install an exception handler around the main entry
3970 point to catch unhandled exceptions. */
3973 {
3974 tree t;
3975 tree etype;
3987 }
3991 /* Finally annotate the parameters and disconnect the trees for parameters
3992 that we have turned into variables since they are now unusable. */
3996 {
4005 }
4007 /* Disconnect the variable created for the return value. */
4011 /* If the function returns an aggregate type and we have candidates for
4012 a Named Return Value, finalize the optimization. */
4014 {
4021 }
4023 /* If this is an inlined external function that has been marked uninlinable,
4024 drop the body and stop there. Otherwise compile the body. */
4027 else
4029 }
4030 \f
4031 /* Return true if GNAT_NODE references an Atomic entity. */
4033 static bool
4035 {
4036 Entity_Id gnat_entity;
4039 {
4058 /* ... fall through ... */
4065 }
4068 }
4070 /* Return true if GNAT_NODE references a Volatile_Full_Access entity. */
4072 static bool
4074 {
4075 Entity_Id gnat_entity;
4078 {
4096 }
4099 }
4101 /* Strip any type conversion on GNAT_NODE and return the result. */
4103 static Node_Id
4105 {
4112 }
4114 /* Return true if GNAT_NODE requires outer atomic access, i.e. atomic access
4115 of an object of which GNAT_NODE is a component. */
4117 static bool
4119 {
4123 {
4125 {
4130 gnat_node
4144 }
4145 }
4148 }
4150 /* Return true if GNAT_NODE requires atomic access and set SYNC according to
4151 the associated synchronization setting. */
4153 static bool
4155 {
4160 /* First, scan the parent to find out cases where the flag is irrelevant. */
4162 {
4165 /* Do not mess up machine code insertions. */
4169 /* Nothing to do if we are the prefix of an attribute, since we do not
4170 want an atomic access for things like 'Size. */
4172 /* ... fall through ... */
4175 /* The N_Reference node is like an attribute. */
4183 /* If we are the prefix, then the access is only partial. */
4189 /* Nothing to do for the identifier in an object renaming declaration,
4190 the renaming itself does not need atomic access. */
4195 }
4197 /* Then, scan the node to find the atomic object. */
4200 /* For Atomic itself, only reads and updates of the object as a whole require
4201 atomic access (RM C.6 (15)). But for Volatile_Full_Access, all reads and
4202 updates require atomic access. */
4207 /* If an outer atomic access will also be required, it cancels this one. */
4214 }
4215 \f
4216 /* Create a temporary variable with PREFIX and TYPE, and return it. */
4218 static tree
4220 {
4221 tree gnu_temp
4227 }
4229 /* Create a temporary variable with PREFIX and initialize it with GNU_INIT.
4230 Put the initialization statement into GNU_INIT_STMT and annotate it with
4231 the SLOC of GNAT_NODE. Return the temporary variable. */
4233 static tree
4235 Node_Id gnat_node)
4236 {
4243 }
4245 /* Subroutine of gnat_to_gnu to translate gnat_node, either an N_Function_Call
4246 or an N_Procedure_Call_Statement, to a GCC tree, which is returned.
4247 GNU_RESULT_TYPE_P is a pointer to where we should place the result type.
4248 If GNU_TARGET is non-null, this must be a function call on the RHS of a
4249 N_Assignment_Statement and the result is to be placed into that object.
4250 If OUTER_ATOMIC_ACCESS is true, then the assignment to GNU_TARGET must be a
4251 load-modify-store sequence. Otherwise, if ATOMIC_ACCESS is true, then the
4252 assignment to GNU_TARGET must be atomic. If, in addition, ATOMIC_SYNC is
4253 true, then the assignment to GNU_TARGET requires atomic synchronization. */
4255 static tree
4258 {
4261 /* The GCC node corresponding to the GNAT subprogram name. This can either
4262 be a FUNCTION_DECL node if we are dealing with a standard subprogram call,
4263 or an indirect reference expression (an INDIRECT_REF node) pointing to a
4264 subprogram. */
4266 /* The FUNCTION_TYPE node giving the GCC type of the subprogram. */
4268 /* The return type of the FUNCTION_TYPE. */
4280 Entity_Id gnat_formal;
4281 Node_Id gnat_actual;
4286 /* If we are calling a stubbed function, raise Program_Error, but Elaborate
4287 all our args first. */
4289 {
4299 {
4302 }
4305 }
4307 /* For a call to a nested function, check the inlining status. */
4312 /* The only way we can be making a call via an access type is if Name is an
4313 explicit dereference. In that case, get the list of formal args from the
4314 type the access type is pointing to. Otherwise, get the formals from the
4315 entity being called. */
4317 {
4320 /* If the access type doesn't require foreign-compatible representation,
4321 be prepared for descriptors. */
4325 }
4327 /* Assume here that this must be 'Elab_Body or 'Elab_Spec. */
4329 else
4332 /* The lifetime of the temporaries created for the call ends right after the
4333 return value is copied, so we can give them the scope of the elaboration
4334 routine at top level. */
4336 {
4339 }
4341 /* First, create the temporary for the return value when:
4343 1. There is no target and the function has copy-in/copy-out parameters,
4344 because we need to preserve the return value before copying back the
4345 parameters.
4347 2. There is no target and the call is made for neither an object nor a
4348 renaming declaration, nor a return statement, nor an allocator, and
4349 the return type has variable size because in this case the gimplifier
4350 cannot create the temporary, or more generally is simply an aggregate
4351 type, because the gimplifier would then create the temporary in the
4352 outermost scope instead of locally.
4354 3. There is a target and it is a slice or an array with fixed size,
4355 and the return type has variable size, because the gimplifier
4356 doesn't handle these cases.
4358 4. There is no target and we have misaligned In Out or Out parameters
4359 passed by reference, because we need to preserve the return value
4360 before copying back the parameters. However, in this case, we'll
4361 defer creating the temporary, see below.
4363 This must be done before we push a binding level around the call, since
4364 we will pop it before copying the return value. */
4367 || (!gnu_target
4375 || (gnu_target
4381 {
4384 }
4386 /* If we don't need a value or have already created it, push a binding level
4387 around the call. This will narrow the lifetime of the temporaries we may
4388 need to make when translating the parameters as much as possible. */
4390 {
4394 }
4396 /* Create the list of the actual parameters as GCC expects it, namely a
4397 chain of TREE_LIST nodes in which the TREE_VALUE field of each node
4398 is an expression and the TREE_PURPOSE field is null. But skip Out
4399 parameters not passed by reference and that need not be copied in. */
4404 {
4409 const bool is_true_formal_parm
4411 const bool is_by_ref_formal_parm
4412 = is_true_formal_parm
4415 /* In the Out or In Out case, we must suppress conversions that yield
4416 an lvalue but can nevertheless cause the creation of a temporary,
4417 because we need the real object in this case, either to pass its
4418 address if it's passed by reference or as target of the back copy
4419 done after the call if it uses the copy-in/copy-out mechanism.
4420 We do it in the In case too, except for an unchecked conversion
4421 to an elementary type or a constrained composite type because it
4422 alone can cause the actual to be misaligned and the addressability
4423 test is applied to the real object. */
4424 const bool suppress_type_conversion
4431 Node_Id gnat_name = suppress_type_conversion
4435 /* If it's possible we may need to use this expression twice, make sure
4436 that any side-effects are handled via SAVE_EXPRs; likewise if we need
4437 to force side-effects before the call. */
4439 {
4443 gnu_name
4445 }
4447 /* If we are passing a non-addressable parameter by reference, pass the
4448 address of a copy. In the Out or In Out case, set up to copy back
4449 out after the call. */
4453 {
4457 /* Do not issue warnings for CONSTRUCTORs since this is not a copy
4458 but sort of an instantiation for them. */
4460 ;
4462 /* If the type is passed by reference, a copy is not allowed. */
4465 gnat_actual);
4467 /* For users of Starlet we issue a warning because the interface
4468 apparently assumes that by-ref parameters outlive the procedure
4469 invocation. The code still will not work as intended, but we
4470 cannot do much better since low-level parts of the back-end
4471 would allocate temporaries at will because of the misalignment
4472 if we did not do so here. */
4474 {
4475 post_error
4477 post_error_ne
4481 gnat_formal);
4482 }
4484 /* If the actual type of the object is already the nominal type,
4485 we have nothing to do, except if the size is self-referential
4486 in which case we'll remove the unpadding below. */
4489 ;
4491 /* Otherwise remove the unpadding from all the objects. */
4493 && TYPE_IS_PADDING_P
4497 /* Otherwise convert to the nominal type of the object if needed.
4498 There are several cases in which we need to make the temporary
4499 using this type instead of the actual type of the object when
4500 they are distinct, because the expectations of the callee would
4501 otherwise not be met:
4502 - if it's a justified modular type,
4503 - if the actual type is a smaller form of it,
4504 - if it's a smaller form of the actual type. */
4508 gnu_name_type)))
4514 /* If this is an In Out or Out parameter and we're returning a value,
4515 we need to create a temporary for the return value because we must
4516 preserve it before copying back at the very end. */
4518 {
4521 }
4523 /* If we haven't pushed a binding level, push it now. This will
4524 narrow the lifetime of the temporary we are about to make as
4525 much as possible. */
4527 {
4531 }
4533 /* Create an explicit temporary holding the copy. */
4534 gnu_temp
4537 /* But initialize it on the fly like for an implicit temporary as
4538 we aren't necessarily having a statement list. */
4540 gnu_temp);
4542 /* Set up to move the copy back to the original if needed. */
4544 {
4545 /* If the original is a COND_EXPR whose first arm isn't meant to
4546 be further used, just deal with the second arm. This is very
4547 likely the conditional expression built for a check. */
4550 && integer_zerop
4554 gnu_stmt
4559 }
4560 }
4562 /* Start from the real object and build the actual. */
4565 /* If atomic access is required for an In or In Out actual parameter,
4566 build the atomic load. */
4568 && !is_by_ref_formal_parm
4573 /* If this was a procedure call, we may not have removed any padding.
4574 So do it here for the part we will use as an input, if any. */
4577 gnu_actual
4580 /* Put back the conversion we suppressed above in the computation of the
4581 real object. And even if we didn't suppress any conversion there, we
4582 may have suppressed a conversion to the Etype of the actual earlier,
4583 since the parent is a procedure call, so put it back here. Note that
4584 we might have a dummy type here if the actual is the dereference of a
4585 pointer to it, but that's OK if the formal is passed by reference. */
4593 else
4596 /* Make sure that the actual is in range of the formal's type. */
4599 gnu_actual
4602 /* Unless this is an In parameter, we must remove any justified modular
4603 building from GNU_NAME to get an lvalue. */
4608 gnu_name
4611 /* First see if the parameter is passed by reference. */
4613 {
4615 {
4616 /* In Out or Out parameters passed by reference don't use the
4617 copy-in/copy-out mechanism so the address of the real object
4618 must be passed to the function. */
4621 /* If we have a padded type, be sure we've removed padding. */
4624 gnu_actual);
4626 /* If we have the constructed subtype of an aliased object
4627 with an unconstrained nominal subtype, the type of the
4628 actual includes the template, although it is formally
4629 constrained. So we need to convert it back to the real
4630 constructed subtype to retrieve the constrained part
4631 and takes its address. */
4637 gnu_actual);
4638 }
4640 /* There is no need to convert the actual to the formal's type before
4641 taking its address. The only exception is for unconstrained array
4642 types because of the way we build fat pointers. */
4644 {
4645 /* Put back a view conversion for In Out or Out parameters. */
4648 gnu_actual);
4650 }
4652 /* The symmetry of the paths to the type of an entity is broken here
4653 since arguments don't know that they will be passed by ref. */
4656 }
4658 /* Then see if the parameter is an array passed to a foreign convention
4659 subprogram. */
4661 {
4667 {
4670 }
4672 /* Take the address of the object and convert to the proper pointer
4673 type. We'd like to actually compute the address of the beginning
4674 of the array using an ADDR_EXPR of an ARRAY_REF, but there's a
4675 possibility that the ARRAY_REF might return a constant and we'd be
4676 getting the wrong address. Neither approach is exactly correct,
4677 but this is the most likely to work in all cases. */
4679 }
4681 /* Otherwise the parameter is passed by copy. */
4682 else
4683 {
4684 tree gnu_size;
4689 /* If we didn't create a PARM_DECL for the formal, this means that
4690 it is an Out parameter not passed by reference and that need not
4691 be copied in. In this case, the value of the actual need not be
4692 read. However, we still need to make sure that its side-effects
4693 are evaluated before the call, so we evaluate its address. */
4695 {
4697 {
4700 }
4702 }
4706 /* If this is 'Null_Parameter, pass a zero even though we are
4707 dereferencing it. */
4713 {
4714 tree type_for_size
4716 gnu_actual
4720 }
4721 else
4723 }
4726 }
4728 gnu_call
4733 /* If we have created a temporary for the return value, initialize it. */
4735 {
4736 tree gnu_stmt
4741 }
4743 /* If this is a subprogram with copy-in/copy-out parameters, we need to
4744 unpack the valued returned from the function into the In Out or Out
4745 parameters. We deal with the function return (if this is an Ada
4746 function) below. */
4748 {
4749 /* List of FIELD_DECLs associated with the PARM_DECLs of the copy-in/
4750 copy-out parameters. */
4754 /* The call sequence must contain one and only one call, even though the
4755 function is pure. Save the result into a temporary if needed. */
4757 {
4759 {
4760 tree gnu_stmt;
4761 gnu_call
4764 }
4767 }
4769 /* The first entry is for the actual return value if this is a
4770 function, so skip it. */
4776 else
4783 /* If we are dealing with a copy-in/copy-out parameter, we must
4784 retrieve its value from the record returned in the call. */
4790 {
4791 /* Get the value to assign to this Out or In Out parameter. It is
4792 either the result of the function if there is only a single such
4793 parameter or the appropriate field from the record returned. */
4794 tree gnu_result
4796 ? gnu_call
4800 /* If the actual is a conversion, get the inner expression, which
4801 will be the real destination, and convert the result to the
4802 type of the actual parameter. */
4803 tree gnu_actual
4806 /* If the result is a padded type, remove the padding. */
4808 gnu_result
4810 gnu_result);
4812 /* If the actual is a type conversion, the real target object is
4813 denoted by the inner Expression and we need to convert the
4814 result to the associated type.
4815 We also need to convert our gnu assignment target to this type
4816 if the corresponding GNU_NAME was constructed from the GNAT
4817 conversion node and not from the inner Expression. */
4819 {
4820 gnu_result
4821 = convert_with_check
4829 }
4831 /* Unchecked conversions as actuals for Out parameters are not
4832 allowed in user code because they are not variables, but do
4833 occur in front-end expansions. The associated GNU_NAME is
4834 always obtained from the inner expression in such cases. */
4837 gnu_result,
4839 else
4840 {
4842 gnu_result
4844 gnat_actual);
4849 }
4851 /* If an outer atomic access is required for an actual parameter,
4852 build the load-modify-store sequence. */
4854 gnu_result
4857 /* Or else, if simple atomic access is required, build the atomic
4858 store. */
4862 /* Otherwise build a regular assignment. */
4863 else
4872 }
4873 }
4875 /* If this is a function call, the result is the call expression unless a
4876 target is specified, in which case we copy the result into the target
4877 and return the assignment statement. */
4879 {
4880 /* If this is a function with copy-in/copy-out parameters, extract the
4881 return value from it and update the return type. */
4883 {
4885 gnu_call
4888 }
4890 /* If the function returns an unconstrained array or by direct reference,
4891 we have to dereference the pointer. */
4897 {
4901 /* If range check is needed, emit code to generate it. */
4903 gnu_call
4905 gnat_parent);
4907 /* ??? If the return type has variable size, then force the return
4908 slot optimization as we would not be able to create a temporary.
4909 That's what has been done historically. */
4912 else
4915 /* Use the required method to move the result to the target. */
4917 gnu_call
4921 else
4922 gnu_call
4928 }
4929 else
4931 }
4933 /* Otherwise, if this is a procedure call statement without copy-in/copy-out
4934 parameters, the result is just the call statement. */
4938 /* Finally, add the copy back statements, if any. */
4944 /* If we have pushed a binding level, pop it and finish up the enclosing
4945 statement group. */
4947 {
4951 }
4953 /* Otherwise, retrieve the statement list, if any. */
4957 /* Otherwise, just return the call expression. */
4958 else
4961 /* If we nevertheless need a value, make a COMPOUND_EXPR to return it.
4962 But first simplify if we have only one statement in the list. */
4964 {
4968 gnu_result
4970 }
4973 }
4974 \f
4975 /* Subroutine of gnat_to_gnu to translate gnat_node, an
4976 N_Handled_Sequence_Of_Statements, to a GCC tree, which is returned. */
4978 static tree
4980 {
4983 /* If just annotating, ignore all EH and cleanups. */
4987 bool fe_sjlj
4993 tree gnu_result;
4994 tree gnu_expr;
4995 Node_Id gnat_temp;
4997 /* The GCC exception handling mechanism can handle both ZCX and SJLJ schemes
4998 and we have our own SJLJ mechanism. To call the GCC mechanism, we call
4999 add_cleanup, and when we leave the binding, end_stmt_group will create
5000 the TRY_FINALLY_EXPR.
5002 ??? The region level calls down there have been specifically put in place
5003 for a ZCX context and currently the order in which things are emitted
5004 (region/handlers) is different from the SJLJ case. Instead of putting
5005 other calls with different conditions at other places for the SJLJ case,
5006 it seems cleaner to reorder things for the SJLJ case and generalize the
5007 condition to make it not ZCX specific.
5009 If there are any exceptions or cleanup processing involved, we need an
5010 outer statement group (for Fe_Sjlj) and binding level. */
5012 {
5015 }
5017 /* If using fe_sjlj, make the variables for the setjmp buffer and save
5018 area for address of previous buffer. Do this first since we need to have
5019 the setjmp buf known for any decls in this block. */
5021 {
5022 gnu_jmpsave_decl
5024 jmpbuf_ptr_type,
5029 /* The __builtin_setjmp receivers will immediately reinstall it. Now
5030 because of the unstructured form of EH used by fe_sjlj, there
5031 might be forward edges going to __builtin_setjmp receivers on which
5032 it is uninitialized, although they will never be actually taken. */
5034 gnu_jmpbuf_decl
5036 jmpbuf_type,
5037 NULL_TREE,
5043 /* When we exit this block, restore the saved value. */
5047 }
5049 /* If we are to call a function when exiting this block, add a cleanup
5050 to the binding level we made above. Note that add_cleanup is FIFO
5051 so we must register this cleanup after the EH cleanup just above. */
5053 {
5056 /* When not optimizing, disable inlining of finalizers as this can
5057 create a more complex CFG in the parent function. */
5061 /* If there is no end label attached, we use the location of the At_End
5062 procedure because Expand_Cleanup_Actions might reset the location of
5063 the enclosing construct to that of an inner statement. */
5067 }
5069 /* Now build the tree for the declarations and statements inside this block.
5070 If this is SJLJ, set our jmp_buf as the current buffer. */
5074 {
5077 gnu_jmpbuf_decl));
5080 }
5086 /* Generate code for each statement in the block. */
5094 /* Now generate code for the two exception models, if either is relevant for
5095 this block. */
5097 {
5099 tree gnu_handler;
5101 /* Make a binding level for the exception handling declarations and code
5102 and set up gnu_except_ptr_stack for the handlers to use. */
5113 /* Generate code for each handler. The N_Exception_Handler case does the
5114 real work and returns a COND_EXPR for each handler, which we chain
5115 together here. */
5118 {
5121 /* If this is the first one, set it as the outer one. Otherwise,
5122 point the "else" part of the previous handler to us. Then point
5123 to our "else" part. */
5126 else
5130 }
5132 /* If none of the exception handlers did anything, re-raise but do not
5133 defer abortion. */
5136 set_expr_location_from_node
5142 else
5145 /* End the binding level dedicated to the exception handlers and get the
5146 whole statement group. */
5151 /* If the setjmp returns 1, we restore our incoming longjmp value and
5152 then check the handlers. */
5155 gnu_jmpsave_decl),
5156 gnat_node);
5160 /* This block is now "if (setjmp) ... <handlers> else <block>". */
5162 (build_call_n_expr
5165 gnu_jmpbuf_decl))),
5167 }
5169 {
5170 tree gnu_handlers;
5171 location_t locus;
5173 /* First make a block containing the handlers. */
5181 /* Now make the TRY_CATCH_EXPR for the block. */
5184 /* Set a location. We need to find a unique location for the dispatching
5185 code, otherwise we can get coverage or debugging issues. Try with
5186 the location of the end label. */
5190 else
5191 /* Clear column information so that the exception handler of an
5192 implicit transient block does not incorrectly inherit the slocs
5193 of a decision, which would otherwise confuse control flow based
5194 coverage analysis tools. */
5196 }
5197 else
5200 /* Now close our outer block, if we had to make one. */
5202 {
5206 }
5209 }
5210 \f
5211 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
5212 to a GCC tree, which is returned. This is the variant for front-end sjlj
5213 exception handling. */
5215 static tree
5217 {
5218 /* Unless this is "Others" or the special "Non-Ada" exception for Ada, make
5219 an "if" statement to select the proper exceptions. For "Others", exclude
5220 exceptions where Handled_By_Others is nonzero unless the All_Others flag
5221 is set. For "Non-ada", accept an exception if "Lang" is 'V'. */
5224 Node_Id gnat_temp;
5228 {
5229 tree this_choice;
5232 {
5235 else
5236 this_choice
5237 = build_binary_op
5239 convert
5241 build_component_ref
5242 (build_unary_op
5245 not_handled_by_others_decl,
5247 integer_zero_node);
5248 }
5252 {
5254 tree gnu_expr;
5256 /* Exception may be a renaming. Recover original exception which is
5257 the one elaborated and registered. */
5263 this_choice
5264 = build_binary_op
5269 }
5270 else
5275 }
5278 }
5279 \f
5280 /* Return true if no statement in GNAT_LIST can alter the control flow. */
5282 static bool
5284 {
5288 /* This is very conservative, we reject everything except for simple
5289 assignments between identifiers or literals. */
5293 {
5305 }
5308 }
5310 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
5311 to a GCC tree, which is returned. This is the variant for GCC exception
5312 schemes. */
5314 static tree
5316 {
5319 /* We build a TREE_LIST of nodes representing what exception types this
5320 handler can catch, with special cases for others and all others cases.
5322 Each exception type is actually identified by a pointer to the exception
5323 id, or to a dummy object for "others" and "all others". */
5325 gnat_temp;
5327 {
5331 {
5334 }
5337 {
5340 /* Exception may be a renaming. Recover original exception which is
5341 the one elaborated and registered. */
5347 }
5348 else
5351 /* The GCC interface expects NULL to be passed for catch all handlers, so
5352 it would be quite tempting to set gnu_etypes_list to NULL if gnu_etype
5353 is integer_zero_node. It would not work, however, because GCC's
5354 notion of "catch all" is stronger than our notion of "others". Until
5355 we correctly use the cleanup interface as well, doing that would
5356 prevent the "all others" handlers from being seen, because nothing
5357 can be caught beyond a catch all from GCC's point of view. */
5359 }
5364 /* Expand a call to the begin_handler hook at the beginning of the handler,
5365 and arrange for a call to the end_handler hook to occur on every possible
5366 exit path.
5368 The hooks expect a pointer to the low level occurrence. This is required
5369 for our stack management scheme because a raise inside the handler pushes
5370 a new occurrence on top of the stack, which means that this top does not
5371 necessarily match the occurrence this handler was dealing with.
5373 __builtin_eh_pointer references the exception occurrence being
5374 propagated. Upon handler entry, this is the exception for which the
5375 handler is triggered. This might not be the case upon handler exit,
5376 however, as we might have a new occurrence propagated by the handler's
5377 body, and the end_handler hook called as a cleanup in this context.
5379 We use a local variable to retrieve the incoming value at handler entry
5380 time, and reuse it to feed the end_handler hook's argument at exit. */
5382 tree gnu_current_exc_ptr
5386 gnu_incoming_exc_ptr
5393 gnu_incoming_exc_ptr),
5394 gnat_node);
5396 /* Declare and initialize the choice parameter, if present. */
5398 {
5399 tree gnu_param
5405 gnu_incoming_exc_ptr));
5406 }
5410 /* We don't have an End_Label at hand to set the location of the cleanup
5411 actions, so we use that of the exception handler itself instead. */
5415 else
5422 return
5424 }
5425 \f
5426 /* Subroutine of gnat_to_gnu to generate code for an N_Compilation unit. */
5428 static void
5430 {
5435 Entity_Id gnat_entity;
5436 Node_Id gnat_pragma;
5437 /* Make the decl for the elaboration procedure. Emit debug info for it, so
5438 that users can break into their elaboration code in debuggers. Kludge:
5439 don't consider it as a definition so that we have a line map for its body,
5440 but no subprogram description in debug info. */
5441 tree gnu_elab_proc_decl
5442 = create_subprog_decl
5451 /* Initialize the information structure for the function. */
5460 /* For a body, first process the spec if there is one. */
5466 {
5473 }
5475 /* Then process any pragmas and declarations preceding the unit. */
5484 /* Process the unit itself. */
5487 /* Generate code for all the inlined subprograms. */
5491 {
5492 Node_Id gnat_body;
5494 /* Without optimization, process only the required subprograms. */
5498 /* The set of inlined subprograms is computed from data recorded early
5499 during expansion and it can be a strict superset of the final set
5500 computed after semantic analysis, for example if a call to such a
5501 subprogram occurs in a pragma Assert and assertions are disabled.
5502 In that case, semantic analysis resets Is_Public to false but the
5503 entry for the subprogram in the inlining tables is stalled. */
5509 {
5510 /* ??? This happens when only the spec of a package is provided. */
5514 gnat_body
5516 }
5518 /* Define the entity first so we set DECL_EXTERNAL. */
5521 }
5523 /* Process any pragmas and actions following the unit. */
5528 /* Save away what we've made so far and finish it up. */
5535 /* Record this potential elaboration procedure for later processing. */
5542 /* Force the processing for all nodes that remain in the queue. */
5544 }
5545 \f
5546 /* Mark COND, a boolean expression, as predicating a call to a noreturn
5547 function, i.e. predict that it is very likely false, and return it.
5549 The compiler will automatically predict the last edge leading to a call
5550 to a noreturn function as very unlikely taken. This function makes it
5551 possible to expand the prediction to predecessors in case the condition
5552 is made up of several short-circuit operators. */
5554 static tree
5556 {
5566 PRED_NORETURN));
5569 }
5571 /* Subroutine of gnat_to_gnu to translate GNAT_RANGE, a node representing a
5572 range of values, into GNU_LOW and GNU_HIGH bounds. */
5574 static void
5576 {
5577 /* GNAT_RANGE is either an N_Range or an identifier denoting a subtype. */
5579 {
5587 {
5591 *gnu_low
5593 *gnu_high
5595 }
5600 }
5601 }
5603 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Raise_xxx_Error,
5604 to a GCC tree and return it. GNU_RESULT_TYPE_P is a pointer to where
5605 we should place the result type. */
5607 static tree
5609 {
5613 const bool with_extra_info
5614 = Exception_Extra_Info
5619 /* The following processing is not required for correctness. Its purpose is
5620 to give more precise error messages and to record some information. */
5622 {
5632 {
5639 {
5657 }
5665 {
5671 }
5674 && gnu_low_bound
5675 && gnu_high_bound
5678 gnu_result
5682 /* If optimization is enabled and we are inside a loop, we try to
5683 compute invariant conditions for checks applied to the iteration
5684 variable, i.e. conditions that are independent of the variable
5685 and necessary in order for the checks to fail in the course of
5686 some iteration. If we succeed, we consider an alternative:
5688 1. If loop unswitching is enabled, we prepend these conditions
5689 to the original conditions of the checks. This will make it
5690 possible for the loop unswitching pass to replace the loop
5691 with two loops, one of which has the checks eliminated and
5692 the other has the original checks reinstated, and a prologue
5693 implementing a run-time selection. The former loop will be
5694 for example suitable for vectorization.
5696 2. Otherwise, we instead append the conditions to the original
5697 conditions of the checks. At worse, if the conditions cannot
5698 be evaluated at compile time, they will be evaluated as true
5699 at run time only when the checks have already failed, thus
5700 contributing negatively only to the size of the executable.
5701 But the hope is that these invariant conditions be evaluated
5702 at compile time to false, thus taking away the entire checks
5703 with them. */
5706 && (!gnu_low_bound
5708 && (!gnu_high_bound
5711 {
5718 rci->inserted_cond
5725 boolean_type_node,
5727 gnu_cond);
5728 else
5730 boolean_type_node,
5731 gnu_cond,
5733 }
5735 /* Or else, if aggressive loop optimizations are enabled, we just
5736 record that there are checks applied to iteration variables. */
5738 && flag_aggressive_loop_optimizations
5742 }
5747 }
5749 /* The following processing does the common work. */
5750 common:
5757 /* If the type is VOID, this is a statement, so we need to generate the code
5758 for the call. Handle a condition, if there is one. */
5760 {
5762 {
5767 }
5768 }
5769 else
5773 }
5774 \f
5775 /* Return true if GNAT_NODE is on the LHS of an assignment or an actual
5776 parameter of a call. */
5778 static bool
5780 {
5795 }
5797 /* Return true if either GNAT_NODE or a view of GNAT_NODE is on the LHS
5798 of an assignment or an actual parameter of a call. */
5800 static bool
5802 {
5803 Node_Kind kind;
5815 }
5817 /* Return true if GNAT_NODE, an unchecked type conversion, is a no-op as far
5818 as gigi is concerned. This is used to avoid conversions on the LHS. */
5820 static bool
5822 {
5825 /* The conversion must be on the LHS of an assignment or an actual parameter
5826 of a call. Otherwise, even if the conversion was essentially a no-op, it
5827 could de facto ensure type consistency and this should be preserved. */
5833 /* We're interested in artificial conversions generated by the front-end
5834 to make private types explicit, e.g. in Expand_Assign_Array. */
5841 /* The direct conversion to the underlying type is a no-op. */
5845 /* For an array subtype, the conversion to the PAIT is a no-op. */
5850 /* For a record subtype, the conversion to the type is a no-op. */
5856 }
5858 /* Return true if GNAT_NODE represents a statement. */
5860 static bool
5862 {
5878 }
5880 /* This function is the driver of the GNAT to GCC tree transformation process.
5881 It is the entry point of the tree transformer. GNAT_NODE is the root of
5882 some GNAT tree. Return the root of the corresponding GCC tree. If this
5883 is an expression, return the GCC equivalent of the expression. If this
5884 is a statement, return the statement or add it to the current statement
5885 group, in which case anything returned is to be interpreted as occurring
5886 after anything added. */
5888 tree
5890 {
5896 Node_Id gnat_temp;
5899 /* Save node number for error message and set location information. */
5903 /* If we are only annotating types and this node is a statement, return
5904 an empty statement list. */
5908 /* If we are only annotating types and this node is a subexpression, return
5909 a NULL_EXPR, but filter out nodes appearing in the expressions attached
5910 to packed array implementation types. */
5925 N_Raise_Constraint_Error));
5930 {
5933 /* If this is a statement and we are at top level, it must be part of
5934 the elaboration procedure, so mark us as being in that procedure. */
5936 {
5939 }
5941 /* If we are in the elaboration procedure, check if we are violating a
5942 No_Elaboration_Code restriction by having a statement there. Don't
5943 check for a possible No_Elaboration_Code restriction violation on
5944 N_Handled_Sequence_Of_Statements, as we want to signal an error on
5945 every nested real statement instead. This also avoids triggering
5946 spurious errors on dummy (empty) sequences created by the front-end
5947 for package bodies in some cases. */
5952 }
5955 {
5956 /********************************/
5957 /* Chapter 2: Lexical Elements */
5958 /********************************/
5967 /* If atomic access is required on the RHS, build the atomic load. */
5974 {
5975 tree gnu_type;
5977 /* Get the type of the result, looking inside any padding and
5978 justified modular types. Then get the value in that type. */
5987 /* If the result overflows (meaning it doesn't fit in its base type),
5988 abort. We would like to check that the value is within the range
5989 of the subtype, but that causes problems with subtypes whose usage
5990 will raise Constraint_Error and with biased representation, so
5991 we don't. */
5993 }
5997 /* If a Entity is present, it means that this was one of the
5998 literals in a user-defined character type. In that case,
5999 just return the value in the CONST_DECL. Otherwise, use the
6000 character code. In that case, the base type should be an
6001 INTEGER_TYPE, but we won't bother checking for that. */
6005 else
6006 gnu_result
6014 /* If this is of a fixed-point type, the value we want is the value of
6015 the corresponding integer. */
6017 {
6019 gnu_result_type);
6021 }
6023 else
6024 {
6027 /* First convert the value to a machine number if it isn't already.
6028 That will force the base to 2 for non-zero values and simplify
6029 the rest of the logic. */
6031 ur_realval
6037 else
6038 {
6039 REAL_VALUE_TYPE tmp;
6043 /* The base must be 2 as Machine guarantees this, so we scale
6044 the value, which we know can fit in the mantissa of the type
6045 (hence the use of that type above). */
6050 }
6052 /* Now see if we need to negate the result. Do it this way to
6053 properly handle -0. */
6055 gnu_result
6057 gnu_result);
6058 }
6065 {
6072 else
6075 /* Build the string with the characters in the literal. Note
6076 that Ada strings are 1-origin. */
6080 /* Put a null at the end of the string in case it's in a context
6081 where GCC will want to treat it as a C string. */
6086 /* Strings in GCC don't normally have types, but we want
6087 this to not be converted to the array type. */
6092 }
6093 else
6094 {
6095 /* Build a list consisting of each character, then make
6096 the aggregate. */
6106 {
6112 }
6115 }
6122 /**************************************/
6123 /* Chapter 3: Declarations and Types */
6124 /**************************************/
6141 /* If we are just annotating types and this object has an unconstrained
6142 or task type, don't elaborate it. */
6152 && (!type_annotate_only
6154 {
6157 gnu_expr
6162 }
6163 else
6166 /* If this is a deferred constant with an address clause, we ignore the
6167 full view since the clause is on the partial view and we cannot have
6168 2 different GCC trees for the object. The only bits of the full view
6169 we will use is the initializer, but it will be directly fetched. */
6175 /* If this object has its elaboration delayed, we must force evaluation
6176 of GNU_EXPR now and save it for the freeze point. Note that we need
6177 not do anything special at the global level since the lifetime of the
6178 temporary is fully contained within the elaboration routine. */
6180 {
6182 {
6185 }
6186 }
6187 else
6195 /* Don't do anything if this renaming is handled by the front end and it
6196 does not need debug info. Note that we consider renamings don't need
6197 debug info when optimizing: our way to describe them has a
6198 memory/elaboration footprint.
6200 Don't do anything neither if we are just annotating types and this
6201 object has a composite or task type, don't elaborate it. */
6204 && !optimize
6205 && can_materialize_object_renaming_p
6207 && ! (type_annotate_only
6211 {
6212 tree gnu_temp
6216 /* See case 2 of renaming in gnat_to_gnu_entity. */
6219 }
6226 /* See the above case for the rationale. */
6228 {
6229 tree gnu_temp
6235 }
6239 {
6245 /* Materializing renamed subprograms will only benefit the debugging
6246 information as they aren't referenced in the generated code. So
6247 skip them when they aren't needed. Avoid doing this if:
6249 - there is a freeze node: in this case the renamed entity is not
6250 elaborated yet,
6251 - the renamed subprogram is intrinsic: it will not be available in
6252 the debugging information (note that both or only one of the
6253 renaming and the renamed subprograms can be intrinsic). */
6264 }
6273 /* These are fully handled in the front end. */
6274 /* ??? For package renamings, find a way to use GENERIC namespaces so
6275 that we get proper debug information for them. */
6279 /*************************************/
6280 /* Chapter 4: Names and Expressions */
6281 /*************************************/
6284 /* Make sure the designated type is complete before dereferencing. */
6289 /* If atomic access is required on the RHS, build the atomic load. */
6296 {
6297 tree gnu_array_object
6299 tree gnu_type;
6306 /* Convert vector inputs to their representative array type, to fit
6307 what the code below expects. */
6309 {
6313 }
6317 /* If we got a padded type, remove it too. */
6319 gnu_array_object
6321 gnu_array_object);
6323 /* The failure of this assertion will very likely come from a missing
6324 expansion for a packed array access. */
6327 /* First compute the number of dimensions of the array, then
6328 fill the expression array, the order depending on whether
6329 this is a Convention_Fortran array or not. */
6334 ;
6343 else
6349 /* Start with the prefix and build the successive references. */
6355 {
6361 gnu_result
6364 /* Array accesses are bound-checked so they cannot trap, but this
6365 is valid only if they are not hoisted ahead of the check. We
6366 need to mark them as no-trap to get decent loop optimizations
6367 in the presence of -fnon-call-exceptions, so we do it when we
6368 know that the original expression had no side-effects. */
6374 /* If aggressive loop optimizations are enabled, we warn for loops
6375 overrunning a simple array of size 1 not at the end of a record.
6376 This is aimed to catch misuses of the trailing array idiom. */
6378 && flag_aggressive_loop_optimizations
6394 {
6397 }
6398 }
6402 /* If atomic access is required on the RHS, build the atomic load. */
6406 }
6410 {
6411 tree gnu_array_object
6422 /* If this is a slice with non-constant size of an array with constant
6423 size, set the maximum size for the allocation of temporaries. */
6431 }
6435 {
6436 Entity_Id gnat_prefix
6443 /* gnat_to_gnu_entity does not save the GNU tree made for renamed
6444 discriminants so avoid making recursive calls on each reference
6445 to them by following the appropriate link directly here. */
6447 {
6448 /* For discriminant references in tagged types always substitute
6449 the corresponding discriminant as the actual component. */
6454 /* For discriminant references in untagged types always substitute
6455 the corresponding stored discriminant. */
6458 }
6460 /* Handle extracting the real or imaginary part of a complex.
6461 The real part is the first field and the imaginary the last. */
6466 else
6467 {
6470 gnu_result
6474 && lvalue_required_for_attribute_p
6476 }
6480 /* If atomic access is required on the RHS, build the atomic load. */
6484 }
6488 {
6489 /* The attribute designator. */
6492 /* The Elab_Spec and Elab_Body attributes are special in that Prefix
6493 is a unit, not an object with a GCC equivalent. */
6495 return
6501 gnat_node);
6504 }
6508 /* Like 'Access as far as we are concerned. */
6516 {
6517 tree gnu_aggr_type;
6519 /* ??? It is wrong to evaluate the type now, but there doesn't
6520 seem to be any other practical way of doing it. */
6524 gnu_aggr_type = gnu_result_type
6529 gnu_aggr_type
6539 gnu_result
6542 gnu_aggr_type);
6545 gnu_aggr_type,
6548 gnu_result
6549 = build_binary_op
6554 (Next
6556 else
6560 }
6568 else
6578 /* If this is a qualified expression for a tagged type, we mark the type
6579 as used. Because of polymorphism, this might be the only reference to
6580 the tagged type in the program while objects have it as dynamic type.
6581 The debugger needs to see it to display these objects properly. */
6585 gnu_result
6589 kind == N_Type_Conversion
6597 /* Skip further processing if the conversion is deemed a no-op. */
6599 {
6603 }
6605 /* If the result is a pointer type, see if we are improperly
6606 converting to a stricter alignment. */
6609 {
6615 post_error_ne_tree_2
6619 }
6621 /* If we are converting a descriptor to a function pointer, first
6622 build the pointer. */
6634 {
6643 {
6647 }
6649 /* If LOW and HIGH are identical, perform an equality test. Otherwise,
6650 ensure that GNU_OBJ is evaluated only once and perform a full range
6651 test. */
6653 gnu_result
6655 else
6656 {
6665 gnu_result
6667 }
6670 gnu_result
6672 }
6680 ? RDIV_EXPR
6689 /* These can either be operations on booleans or on modular types.
6690 Fall through for boolean types since that's the way GNU_CODES is
6691 set up. */
6693 {
6694 enum tree_code code
6705 }
6707 /* ... fall through ... */
6727 {
6731 tree gnu_type;
6737 /* Pending generic support for efficient vector logical operations in
6738 GCC, convert vectors to their representative array type view and
6739 fallthrough. */
6743 /* If this is a comparison operator, convert any references to an
6744 unconstrained array value into a reference to the actual array. */
6746 {
6752 {
6755 }
6756 }
6758 /* If this is a shift whose count is not guaranteed to be correct,
6759 we need to adjust the shift count. */
6761 {
6763 tree gnu_max_shift
6770 gnu_rhs
6771 = build_binary_op
6774 gnu_count_type,
6775 gnu_max_shift,
6777 gnu_rhs);
6778 }
6780 /* For right shifts, the type says what kind of shift to do,
6781 so we may need to choose a different type. In this case,
6782 we have to ignore integer overflow lest it propagates all
6783 the way down and causes a CE to be explicitly raised. */
6785 {
6788 }
6791 {
6794 }
6797 {
6803 }
6805 /* Instead of expanding overflow checks for addition, subtraction
6806 and multiplication itself, the front end will leave this to
6807 the back end when Backend_Overflow_Checks_On_Target is set. */
6809 && Backend_Overflow_Checks_On_Target
6815 else
6816 {
6817 /* Some operations, e.g. comparisons of arrays, generate complex
6818 trees that need to be annotated while they are being built. */
6821 }
6823 /* If this is a logical shift with the shift count not verified,
6824 we must return zero if it is too large. We cannot compensate
6825 above in this case. */
6828 gnu_result
6829 = build_cond_expr
6832 gnu_rhs,
6836 gnu_result);
6837 }
6841 {
6844 tree gnu_false
6848 gnu_result
6850 }
6859 /* This case can apply to a boolean or a modular type.
6860 Fall through for a boolean operand since GNU_CODES is set
6861 up to handle this. */
6863 {
6867 gnu_expr);
6869 }
6871 /* ... fall through ... */
6878 /* Instead of expanding overflow checks for negation and absolute
6879 value itself, the front end will leave this to the back end
6880 when Backend_Overflow_Checks_On_Target is set. */
6882 && Backend_Overflow_Checks_On_Target
6885 gnu_result
6888 else
6894 {
6896 tree gnu_type;
6901 /* The Expression operand can either be an N_Identifier or
6902 Expanded_Name, which must represent a type, or a
6903 N_Qualified_Expression, which contains both the object type and an
6904 initial value for the object. */
6909 {
6910 Entity_Id gnat_desig_type
6918 gnu_init
6924 else
6925 {
6929 }
6931 /* See the N_Qualified_Expression case for the rationale. */
6936 }
6937 else
6944 ignore_init_type);
6945 }
6948 /**************************/
6949 /* Chapter 5: Statements */
6950 /**************************/
6958 /* When not optimizing, turn null statements from source into gotos to
6959 the next statement that the middle-end knows how to preserve. */
6961 {
6972 }
6973 else
6978 /* Get the LHS and RHS of the statement and convert any reference to an
6979 unconstrained array into a reference to the underlying array. */
6982 /* If the type has a size that overflows, convert this into raise of
6983 Storage_Error: execution shouldn't have gotten here anyway. */
6987 N_Raise_Storage_Error);
6989 {
6990 bool outer_atomic_access
6992 bool atomic_access
6993 = !outer_atomic_access
6995 gnu_result
6998 }
6999 else
7000 {
7002 const Entity_Id gnat_type
7004 const bool regular_array_type_p
7006 const bool use_memset_p
7007 = (regular_array_type_p
7011 /* If we'll use memset, we need to find the inner expression. */
7013 {
7014 Node_Id gnat_inner
7018 gnat_inner
7021 }
7022 else
7025 /* If range check is needed, emit code to generate it. */
7028 gnat_node);
7030 /* If an outer atomic access is required on the LHS, build the load-
7031 modify-store sequence. */
7035 /* Or else, if atomic access is required, build the atomic store. */
7039 /* Or else, use memset when the conditions are met. */
7041 {
7042 tree value
7044 ? integer_zero_node
7048 tree size
7053 {
7054 tree mask
7058 }
7060 }
7062 /* Otherwise build a regular assignment. */
7063 else
7064 gnu_result
7067 /* If the assignment type is a regular array and the two sides are
7068 not completely disjoint, play safe and use memmove. But don't do
7069 it for a bit-packed array as it might not be byte-aligned. */
7071 && regular_array_type_p
7073 {
7077 tree size
7083 }
7084 }
7088 {
7091 /* Make the outer COND_EXPR. Avoid non-determinism. */
7100 /* Now make a COND_EXPR for each of the "else if" parts. Put each
7101 into the previous "else" part and point to where to put any
7102 outer "else". Also avoid non-determinism. */
7106 {
7116 }
7119 }
7131 /* The only way to enter the block is to fall through to it. */
7133 {
7140 }
7141 else
7146 gnu_result
7156 {
7159 /* If the subprogram is a function, we must return the expression. */
7161 {
7164 /* If this function has copy-in/copy-out parameters parameters and
7165 doesn't return by invisible reference, get the real object for
7166 the return. See Subprogram_Body_to_gnu. */
7170 else
7173 /* Get the GCC tree for the expression to be returned. */
7176 /* Do not remove the padding from GNU_RET_VAL if the inner type is
7177 self-referential since we want to allocate the fixed size. */
7179 && type_is_padding_self_referential
7183 /* If the function returns by direct reference, return a pointer
7184 to the return value. */
7189 /* Otherwise, if it returns an unconstrained array, we have to
7190 allocate a new version of the result and return it. */
7192 {
7195 /* And find out whether this is a candidate for Named Return
7196 Value. If so, record it. */
7198 {
7201 /* Strip useless conversions around the return value. */
7205 /* Strip unpadding around the return value. */
7207 && TYPE_IS_PADDING_P
7211 /* Now apply the test to the return value. */
7213 {
7219 }
7220 }
7223 gnu_ret_val,
7228 }
7230 /* Otherwise, if it returns by invisible reference, dereference
7231 the pointer it is passed using the type of the return value
7232 and build the copy operation manually. This ensures that we
7233 don't copy too much data, for example if the return type is
7234 unconstrained with a maximum size. */
7236 {
7237 tree gnu_ret_deref
7239 gnu_ret_obj);
7244 }
7245 }
7247 else
7250 /* If we have a return label defined, convert this into a branch to
7251 that label. The return proper will be handled elsewhere. */
7253 {
7256 gnu_ret_val));
7261 /* When not optimizing, make sure the return is preserved. */
7264 }
7266 /* Otherwise, build a regular return. */
7267 else
7269 }
7278 /***************************/
7279 /* Chapter 6: Subprograms */
7280 /***************************/
7283 /* Unless there is a freeze node, declare the entity. We consider
7284 this a definition even though we're not generating code for the
7285 subprogram because we will be making the corresponding GCC node.
7286 When there is a freeze node, it is considered the definition of
7287 the subprogram and we do nothing until after it is encountered.
7288 That's an efficiency issue: the types involved in the profile
7289 are far more likely to be frozen between the declaration and
7290 the freeze node than before the declaration, so we save some
7291 updates of the GCC node by waiting until the freeze node.
7292 The counterpart is that we assume that there is no reference
7293 to the subprogram between the declaration and the freeze node
7294 in the expanded code; otherwise, it will be interpreted as an
7295 external reference and very likely give rise to a link failure. */
7303 /* This subprogram doesn't exist for code generation purposes, but we
7304 have to elaborate the types of any parameters and result, unless
7305 they are imported types (nothing to generate in this case).
7307 The parameter list may contain types with freeze nodes, e.g. not null
7308 subtypes, so the subprogram itself may carry a freeze node, in which
7309 case its elaboration must be deferred. */
7311 /* Process the parameter types first. */
7314 = First_Formal_With_Extras
7322 /* Then the result type, set to Standard_Void_Type for procedures. */
7323 {
7324 Entity_Id gnat_temp_type
7329 }
7335 /* For a child unit identifier go up a level to get the specification.
7336 We get this when we try to find the spec of a child unit package
7337 that is the compilation unit being compiled. */
7352 /************************/
7353 /* Chapter 7: Packages */
7354 /************************/
7370 /* If this is the body of a generic package - do nothing. */
7372 {
7375 }
7386 /********************************/
7387 /* Chapter 8: Visibility Rules */
7388 /********************************/
7392 /* Nothing to do here - but these may appear in list of declarations. */
7396 /*********************/
7397 /* Chapter 9: Tasks */
7398 /*********************/
7409 /*********************************************************/
7410 /* Chapter 10: Program Structure and Compilation Issues */
7411 /*********************************************************/
7414 /* This is not called for the main unit on which gigi is invoked. */
7426 /* These nodes should only be present when annotating types. */
7436 /* Simply process whatever unit is being inserted. */
7439 else
7440 {
7443 }
7446 /***************************/
7447 /* Chapter 11: Exceptions */
7448 /***************************/
7451 /* If there is an At_End procedure attached to this node, and the EH
7452 mechanism is front-end, we must have at least a corresponding At_End
7453 handler, unless the No_Exception_Handlers restriction is set. */
7468 else
7473 /* Only for reraise in back-end exceptions mode. */
7480 /* Clear the current exception pointer so that the occurrence won't be
7481 deallocated. */
7527 /******************************/
7528 /* Chapter 12: Generic Units */
7529 /******************************/
7539 /* These nodes can appear on a declaration list but there is nothing to
7540 to be done with them. */
7544 /**************************************************/
7545 /* Chapter 13: Representation Clauses and */
7546 /* Implementation-Dependent Features */
7547 /**************************************************/
7552 /* The only one we need to deal with is 'Address since, for the others,
7553 the front-end puts the information elsewhere. */
7557 /* And we only deal with 'Address if the object has a Freeze node. */
7562 /* Get the value to use as the address and save it as the equivalent
7563 for the object. When it is frozen, gnat_to_gnu_entity will do the
7564 right thing. */
7571 /* We do nothing with these. SEM puts the information elsewhere. */
7577 {
7587 /* First retrieve the 3 operand lists built by the front-end. */
7590 {
7597 }
7601 {
7608 }
7612 gnu_clobbers
7615 gnu_clobbers);
7617 /* Then perform some standard checking and processing on the
7618 operands. In particular, mark them addressable if needed. */
7626 {
7628 constraint
7634 {
7635 /* If the operand is going to end up in memory,
7636 mark it addressable. Note that we don't test
7637 allows_mem like in the input case below; this
7638 is modelled on the C front-end. */
7640 {
7647 }
7648 }
7649 else
7653 }
7656 {
7658 constraint
7664 {
7665 /* If the operand is going to end up in memory,
7666 mark it addressable. */
7668 {
7675 }
7676 }
7677 else
7681 }
7687 }
7688 else
7693 /****************/
7694 /* Added Nodes */
7695 /****************/
7697 /* Markers are created by the ABE mechanism to capture information which
7698 is either unavailable of expensive to recompute. Markers do not have
7699 and runtime semantics, and should be ignored. */
7707 /* This construct doesn't define a scope so we don't push a binding
7708 level around the statement list, but we wrap it in a SAVE_EXPR to
7709 protect it from unsharing. Elaborate the expression as part of the
7710 same statement group as the actions so that the type declaration
7711 gets inserted there as well. This ensures that the type elaboration
7712 code is issued past the actions computing values on which it might
7713 depend. */
7722 gnu_result
7746 {
7747 tree gnu_ptr
7752 /* If this is a thin pointer, we must first dereference it to create
7753 a fat pointer, then go back below to a thin pointer. The reason
7754 for this is that we need to have a fat pointer someplace in order
7755 to properly compute the size. */
7759 gnu_ptr));
7761 /* If this is a fat pointer, the object must have been allocated with
7762 the template in front of the array. So pass the template address,
7763 and get the total size; do it by converting to a thin pointer. */
7765 gnu_ptr
7767 (TYPE_OBJECT_RECORD_TYPE
7769 gnu_ptr);
7773 /* If this is a thin pointer, the object must have been allocated with
7774 the template in front of the array. So pass the template address,
7775 and get the total size. */
7777 gnu_ptr
7779 gnu_ptr,
7781 byte_position
7782 (DECL_CHAIN
7785 /* If we have a special dynamic constrained subtype on the node, use
7786 it to compute the size; otherwise, use the designated subtype. */
7788 {
7789 gnu_actual_obj_type
7793 gnu_actual_obj_type
7795 gnu_actual_obj_type,
7798 }
7799 else
7805 gnu_result
7809 gnat_node);
7810 }
7818 else
7823 /* The only validation we currently do on an unchecked conversion is
7824 that of aliasing assumptions. */
7834 /* These nodes should only be present when annotating types. */
7840 /* Other nodes are not supposed to reach here. */
7842 }
7844 /* If we pushed the processing of the elaboration routine, pop it back. */
7848 /* When not optimizing, turn boolean rvalues B into B != false tests
7849 so that we can put the location information of the reference to B on
7850 the inequality operator for better debug info. */
7861 {
7862 gnu_result
7868 }
7870 /* Set the location information on the result if it's not a simple name.
7871 Note that we may have no result if we tried to build a CALL_EXPR node
7872 to a procedure with no side-effects and optimization is enabled. */
7876 /* If we're supposed to return something of void_type, it means we have
7877 something we're elaborating for effect, so just return. */
7881 /* If the result is a constant that overflowed, raise Constraint_Error. */
7883 {
7885 gnu_result
7888 N_Raise_Constraint_Error));
7889 }
7891 /* If the result has side-effects and is of an unconstrained type, protect
7892 the expression in case it will be referenced multiple times, i.e. for
7893 its value and to compute the size of an object. But do it neither for
7894 an object nor a renaming declaration, nor a return statement of a call
7895 to a function that returns an unconstrained record type with default
7896 discriminant, because there is no size to be computed in these cases
7897 and this will create a useless temporary. We must do this before any
7898 conversions. */
7909 /* Now convert the result to the result type, unless we are in one of the
7910 following cases:
7912 1. If this is the LHS of an assignment or an actual parameter of a
7913 call, return the result almost unmodified since the RHS will have
7914 to be converted to our type in that case, unless the result type
7915 has a simpler size. Likewise if there is just a no-op unchecked
7916 conversion in-between. Similarly, don't convert integral types
7917 that are the operands of an unchecked conversion since we need
7918 to ignore those conversions (for 'Valid).
7920 2. If we have a label (which doesn't have any well-defined type), a
7921 field or an error, return the result almost unmodified. Similarly,
7922 if the two types are record types with the same name, don't convert.
7923 This will be the case when we are converting from a packable version
7924 of a type to its original type and we need those conversions to be
7925 NOPs in order for assignments into these types to work properly.
7927 3. If the type is void or if we have no result, return error_mark_node
7928 to show we have no result.
7930 4. If this is a call to a function that returns with variable size and
7931 the call is used as the expression in either an object or a renaming
7932 declaration, return the result unmodified because we want to use the
7933 return slot optimization in this case.
7935 5. Finally, if the type of the result is already correct. */
7953 && (CONTAINS_PLACEHOLDER_P
7957 {
7958 /* Remove padding only if the inner object is of self-referential
7959 size: in that case it must be an object of unconstrained type
7960 with a default discriminant and we want to avoid copying too
7961 much data. */
7964 gnu_result);
7965 }
7974 {
7975 /* Remove any padding. */
7978 gnu_result);
7979 }
7989 ;
7994 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on the result. */
8001 }
8003 /* Similar to gnat_to_gnu, but discard any object that might be created in
8004 the course of the translation of GNAT_NODE, which must be an "external"
8005 expression in the sense that it will be elaborated elsewhere. */
8007 tree
8009 {
8013 /* Force the local context and create a fake scope that we zap
8014 at the end so declarations will not be stuck either in the
8015 global varpool or in the current scope. */
8017 {
8020 }
8031 /* Do not import locations from external units. */
8036 }
8037 \f
8038 /* Return true if the statement list STMT_LIST is empty. */
8040 static bool
8042 {
8043 tree_stmt_iterator tsi;
8046 {
8049 /* Anything else than an empty STMT_STMT counts as something. */
8052 }
8055 }
8057 /* Record the current code position in GNAT_NODE. */
8059 static void
8061 {
8066 }
8068 /* Insert the code for GNAT_NODE at the position saved for that node. */
8070 static void
8072 {
8075 /* It's too late to remove the STMT_STMT itself at this point. */
8080 }
8081 \f
8082 /* Start a new statement group chained to the previous group. */
8084 void
8086 {
8089 /* First see if we can get one from the free list. */
8092 else
8098 }
8100 /* Add GNU_STMT to the current statement group. If it is an expression with
8101 no effects, it is ignored. */
8103 void
8105 {
8107 }
8109 /* Similar, but the statement is always added, regardless of side-effects. */
8111 void
8113 {
8115 }
8117 /* Like add_stmt, but set the location of GNU_STMT to that of GNAT_NODE. */
8119 void
8121 {
8122 /* Do not emit a location for renamings that come from generic instantiation,
8123 they are likely to disturb debugging. */
8127 }
8129 /* Similar, but the statement is always added, regardless of side-effects. */
8131 void
8133 {
8137 }
8139 /* Add a declaration statement for GNU_DECL to the current statement group.
8140 Get SLOC from Entity_Id. */
8142 void
8144 {
8148 /* If this is a variable that Gigi is to ignore, we may have been given
8149 an ERROR_MARK. So test for it. We also might have been given a
8150 reference for a renaming. So only do something for a decl. Also
8151 ignore a TYPE_DECL for an UNCONSTRAINED_ARRAY_TYPE. */
8159 /* If we are external or global, we don't want to output the DECL_EXPR for
8160 this DECL node since we already have evaluated the expressions in the
8161 sizes and positions as globals and doing it again would be wrong. */
8163 {
8164 /* Mark everything as used to prevent node sharing with subprograms.
8165 Note that walk_tree knows how to deal with TYPE_DECL, but neither
8166 VAR_DECL nor CONST_DECL. This appears to be somewhat arbitrary. */
8170 {
8174 }
8175 /* In any case, we have to deal with our own TYPE_ADA_SIZE field. */
8180 }
8181 else
8184 /* If this is a variable and an initializer is attached to it, it must be
8185 valid for the context. Similar to init_const in create_var_decl. */
8192 {
8195 {
8198 }
8200 /* If GNU_DECL has a padded type, convert it to the unpadded
8201 type so the assignment is done properly. */
8207 }
8208 }
8210 /* Callback for walk_tree to mark the visited trees rooted at *TP. */
8212 static tree
8214 {
8220 /* Don't mark a dummy type as visited because we want to mark its sizes
8221 and fields once it's filled in. */
8229 }
8231 /* Mark nodes rooted at T with TREE_VISITED and types as having their
8232 sized gimplified. We use this to indicate all variable sizes and
8233 positions in global types may not be shared by any subprogram. */
8235 void
8237 {
8239 }
8241 /* Add GNU_CLEANUP, a cleanup action, to the current code group and
8242 set its location to that of GNAT_NODE if present, but with column info
8243 cleared so that conditional branches generated as part of the cleanup
8244 code do not interfere with coverage analysis tools. */
8246 static void
8248 {
8252 }
8254 /* Set the BLOCK node corresponding to the current code group to GNU_BLOCK. */
8256 void
8258 {
8261 }
8263 /* Return code corresponding to the current code group. It is normally
8264 a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
8265 BLOCK or cleanups were set. */
8267 tree
8269 {
8273 /* If this is a null list, allocate a new STATEMENT_LIST. Then, if there
8274 are cleanups, make a TRY_FINALLY_EXPR. Last, if there is a BLOCK,
8275 make a BIND_EXPR. Note that we nest in that because the cleanup may
8276 reference variables in the block. */
8288 /* Remove this group from the stack and add it to the free list. */
8294 }
8296 /* Return whether the current statement group may fall through. */
8300 {
8303 else
8305 }
8307 /* Add a list of statements from GNAT_LIST, a possibly-empty list of
8308 statements.*/
8310 static void
8312 {
8313 Node_Id gnat_node;
8319 }
8321 /* Build a tree from GNAT_LIST, a possibly-empty list of statements.
8322 If BINDING_P is true, push and pop a binding level around the list. */
8324 static tree
8326 {
8338 }
8339 \f
8340 /* Generate GIMPLE in place for the expression at *EXPR_P. */
8342 int
8345 {
8348 tree op;
8354 {
8356 /* If this is an aggregate type, build a null pointer of the appropriate
8357 type and dereference it. */
8362 integer_zero_node));
8363 /* Otherwise, just make a VAR_DECL. */
8364 else
8365 {
8368 }
8374 /* We should only do this if we are just elaborating for side-effects,
8375 but we can't know that yet. */
8382 /* If we are taking the address of a constant CONSTRUCTOR, make sure it
8383 is put into static memory. We know that it's going to be read-only
8384 given the semantics we have and it must be in static memory when the
8385 reference is in an elaboration procedure. */
8387 {
8391 }
8393 /* Replace atomic loads with their first argument. That's necessary
8394 because the gimplifier would create a temporary otherwise. */
8397 {
8400 {
8406 else
8408 }
8409 else
8411 }
8418 /* If we are view-converting a CONSTRUCTOR or a call from an aggregate
8419 type to a scalar one, explicitly create the local temporary. That's
8420 required if the type is passed by reference. */
8424 {
8433 }
8440 /* The expressions for the RM bounds must be gimplified to ensure that
8441 they are properly elaborated. See gimplify_decl_expr. */
8445 {
8450 {
8455 {
8459 }
8463 {
8467 }
8469 }
8474 }
8476 /* ... fall through ... */
8480 }
8481 }
8483 /* Generate GIMPLE in place for the statement at *STMT_P. */
8485 static enum gimplify_status
8487 {
8491 {
8497 {
8503 /* Build the condition expression from the test, if any. */
8505 {
8506 /* Deal with the optimization hints. */
8510 annot_expr_ivdep_kind),
8511 integer_zero_node);
8515 annot_expr_unroll_kind),
8516 integer_one_node);
8520 annot_expr_unroll_kind),
8525 annot_expr_no_vector_kind),
8526 integer_zero_node);
8530 annot_expr_vector_kind),
8531 integer_zero_node);
8533 gnu_cond
8536 }
8538 /* Set to emit the statements of the loop. */
8541 /* We first emit the start label and then a conditional jump to the
8542 end label if there's a top condition, then the update if it's at
8543 the top, then the body of the loop, then a conditional jump to
8544 the end label if there's a bottom condition, then the update if
8545 it's at the bottom, and finally a jump to the start label and the
8546 definition of the end label. */
8548 gnu_start_label),
8549 stmt_p);
8570 gnu_end_label),
8571 stmt_p);
8573 }
8576 /* Build a statement to jump to the corresponding end label, then
8577 see if it needs to be conditional. */
8586 }
8587 }
8588 \f
8589 /* Force a reference to each of the entities in GNAT_PACKAGE recursively.
8591 This routine is exclusively called in type_annotate mode, to compute DDA
8592 information for types in withed units, for ASIS use. */
8594 static void
8596 {
8597 Entity_Id gnat_entity;
8602 {
8605 /* We are interested only in entities visible from the main unit. */
8609 /* Skip stuff internal to the compiler. */
8619 /* Skip named numbers. */
8623 /* Skip generic declarations. */
8627 /* Skip formal objects. */
8631 /* Skip package bodies. */
8635 /* Skip limited views that point back to the main unit. */
8641 /* Skip types that aren't frozen. */
8645 /* Recurse on real packages that aren't in the main unit. */
8647 {
8651 }
8652 else
8654 }
8655 }
8657 /* Force a reference to each of the entities in packages withed by GNAT_NODE.
8658 Operate recursively but check that we aren't elaborating something more
8659 than once.
8661 This routine is exclusively called in type_annotate mode, to compute DDA
8662 information for types in withed units, for ASIS use. */
8664 static void
8666 {
8667 Entity_Id gnat_with_clause;
8669 /* Process each unit only once. As we trace the context of all relevant
8670 units transitively, including generic bodies, we may encounter the
8671 same generic unit repeatedly. */
8675 /* Save entities in all context units. A body may have an implicit_with
8676 on its own spec, if the context includes a child unit, so don't save
8677 the spec twice. */
8684 {
8694 {
8697 /* Retrieve compilation unit node of generic body. */
8702 /* If body is available, elaborate its context. */
8705 }
8706 }
8710 }
8711 \f
8712 /* Do the processing of GNAT_NODE, an N_Freeze_Entity. */
8714 static void
8716 {
8721 /* If this is a package, generate code for the package body, if any. */
8723 {
8728 }
8730 /* Don't do anything for class-wide types as they are always transformed
8731 into their root type. */
8735 /* Check for an old definition if this isn't an object with address clause,
8736 since the saved GCC tree is the address expression in that case. */
8737 gnu_old
8741 /* Don't do anything for subprograms that may have been elaborated before
8742 their freeze nodes. This can happen, for example, because of an inner
8743 call in an instance body or because of previous compilation of a spec
8744 for inlining purposes. */
8752 /* If we have a non-dummy type old tree, we have nothing to do, except for
8753 aborting, since this node was never delayed as it should have been. We
8754 let this happen for concurrent types and their Corresponding_Record_Type,
8755 however, because each might legitimately be elaborated before its own
8756 freeze node, e.g. while processing the other. */
8760 {
8765 }
8767 /* Reset the saved tree, if any, and elaborate the object or type for real.
8768 If there is a full view, elaborate it and use the result. And, if this
8769 is the root type of a class-wide type, reuse it for the latter. */
8771 {
8776 {
8783 {
8786 }
8787 }
8793 }
8797 {
8806 /* Propagate back-annotations from full view to partial view. */
8816 /* The above call may have defined this entity (the simplest example
8817 of this is when we have a private enumeral type since the bounds
8818 will have the public view). */
8821 }
8822 else
8823 {
8824 tree gnu_init
8830 }
8837 /* If we have an old type and we've made pointers to this type, update those
8838 pointers. If this is a Taft amendment type in the main unit, we need to
8839 mark the type as used since other units referencing it don't see the full
8840 declaration and, therefore, cannot mark it as used themselves. */
8842 {
8849 }
8850 }
8851 \f
8852 /* Elaborate decls in the lists GNAT_DECLS and GNAT_DECLS2, if present.
8853 We make two passes, one to elaborate anything other than bodies (but
8854 we declare a function if there was no spec). The second pass
8855 elaborates the bodies.
8857 GNAT_END_LIST gives the element in the list past the end. Normally,
8858 this is Empty, but can be First_Real_Statement for a
8859 Handled_Sequence_Of_Statements.
8861 We make a complete pass through both lists if PASS1P is true, then make
8862 the second pass over both lists if PASS2P is true. The lists usually
8863 correspond to the public and private parts of a package. */
8865 static void
8868 {
8870 Node_Id gnat_decl;
8880 {
8881 /* For package specs, we recurse inside the declarations,
8882 thus taking the two pass approach inside the boundary. */
8890 /* Similarly for any declarations in the actions of a
8891 freeze node. */
8893 {
8896 }
8898 /* Package bodies with freeze nodes get their elaboration deferred
8899 until the freeze node, but the code must be placed in the right
8900 place, so record the code position now. */
8908 (Corresponding_Spec
8911 record_code_position
8914 /* We defer most subprogram bodies to the second pass. */
8916 {
8918 {
8924 }
8925 }
8927 /* For bodies and stubs that act as their own specs, the entity
8928 itself must be elaborated in the first pass, because it may
8929 be used in other declarations. */
8931 {
8932 Node_Id gnat_subprog_id
8939 }
8941 /* Concurrent stubs stand for the corresponding subprogram bodies,
8942 which are deferred like other bodies. */
8945 ;
8947 /* Renamed subprograms may not be elaborated yet at this point
8948 since renamings do not trigger freezing. Wait for the second
8949 pass to take care of them. */
8951 ;
8953 else
8955 }
8957 /* Here we elaborate everything we deferred above except for package bodies,
8958 which are elaborated at their freeze nodes. Note that we must also
8959 go inside things (package specs and freeze nodes) the first pass did. */
8965 {
8984 }
8985 }
8986 \f
8987 /* Make a unary operation of kind CODE using build_unary_op, but guard
8988 the operation by an overflow check. CODE can be one of NEGATE_EXPR
8989 or ABS_EXPR. GNU_TYPE is the type desired for the result. Usually
8990 the operation is to be performed in that type. GNAT_NODE is the gnat
8991 node conveying the source location for which the error should be
8992 signaled. */
8994 static tree
8996 Node_Id gnat_node)
8997 {
9006 }
9008 /* Make a binary operation of kind CODE using build_binary_op, but guard
9009 the operation by an overflow check. CODE can be one of PLUS_EXPR,
9010 MINUS_EXPR or MULT_EXPR. GNU_TYPE is the type desired for the result.
9011 Usually the operation is to be performed in that type. GNAT_NODE is
9012 the GNAT node conveying the source location for which the error should
9013 be signaled. */
9015 static tree
9018 {
9027 /* Assert that the precision is a power of 2. */
9030 /* Prefer a constant on the RHS to simplify checks. */
9034 {
9038 }
9042 /* If we can fold the expression to a constant, just return it.
9043 The caller will deal with overflow, no need to generate a check. */
9047 /* If no operand is a constant, we use the generic implementation. */
9049 {
9050 /* Never inline a 64-bit mult for a 32-bit target, it's way too long. */
9052 {
9057 }
9062 {
9074 }
9077 tree call
9085 return
9087 }
9089 /* If one operand is a constant, we expose the overflow condition to enable
9090 a subsequent simplication or even elimination. */
9092 {
9096 /* When rhs > 0, overflow when lhs > type_max - rhs. */
9101 /* When rhs < 0, overflow when lhs < type_min - rhs. */
9105 else
9111 {
9114 /* When lhs > 0, overflow when rhs < lhs - type_max. */
9119 /* When lhs < 0, overflow when rhs > lhs - type_min. */
9123 else
9125 }
9126 else
9127 {
9130 /* When rhs > 0, overflow when lhs < type_min + rhs. */
9135 /* When rhs < 0, overflow when lhs > type_max + rhs. */
9139 else
9141 }
9147 {
9154 /* When rhs > 1, overflow outside [type_min/rhs; type_max/rhs]. */
9155 check
9161 }
9163 {
9168 /* When rhs == -1, overflow if lhs == type_min. */
9169 check
9171 else
9172 /* When rhs < -1, overflow outside [type_max/rhs; type_min/rhs]. */
9173 check
9179 }
9180 else
9186 }
9189 }
9191 /* Emit code for a range check. GNU_EXPR is the expression to be checked,
9192 GNAT_RANGE_TYPE the gnat type or subtype containing the bounds against
9193 which we have to check. GNAT_NODE is the GNAT node conveying the source
9194 location for which the error should be signaled. */
9196 static tree
9198 {
9202 /* If GNU_EXPR has GNAT_RANGE_TYPE as its base type, no check is needed.
9203 This can for example happen when translating 'Val or 'Value. */
9207 /* Range checks can only be applied to types with ranges. */
9211 /* If GNU_EXPR has an integral type that is narrower than GNU_RANGE_TYPE,
9212 we can't do anything since we might be truncating the bounds. No
9213 check is needed in this case. */
9219 /* Checked expressions must be evaluated only once. */
9222 /* Note that the form of the check is
9223 (not (expr >= lo)) or (not (expr <= hi))
9224 the reason for this slightly convoluted form is that NaNs
9225 are not considered to be in range in the float case. */
9226 return emit_check
9228 invert_truthvalue
9232 TYPE_MIN_VALUE
9234 invert_truthvalue
9238 TYPE_MAX_VALUE
9241 }
9242 \f
9243 /* GNU_COND contains the condition corresponding to an index, overflow or
9244 range check of value GNU_EXPR. Build a COND_EXPR that returns GNU_EXPR
9245 if GNU_COND is false and raises a CONSTRAINT_ERROR if GNU_COND is true.
9246 REASON is the code that says why the exception is raised. GNAT_NODE is
9247 the node conveying the source location for which the error should be
9248 signaled.
9250 We used to propagate TREE_SIDE_EFFECTS from GNU_EXPR to the COND_EXPR,
9251 overwriting the setting inherited from the call statement, on the ground
9252 that the expression need not be evaluated just for the check. However
9253 that's incorrect because, in the GCC type system, its value is presumed
9254 to be valid so its comparison against the type bounds always yields true
9255 and, therefore, could be done without evaluating it; given that it can
9256 be a computation that overflows the bounds, the language may require the
9257 check to fail and thus the expression to be evaluated in this case. */
9259 static tree
9261 {
9262 tree gnu_call
9264 return
9270 gnu_expr);
9271 }
9272 \f
9273 /* Return an expression that converts GNU_EXPR to GNAT_TYPE, doing overflow
9274 checks if OVERFLOW_P is true and range checks if RANGE_P is true.
9275 If TRUNCATE_P true, do a float-to-integer conversion with truncation,
9276 otherwise round. GNAT_NODE is the GNAT node conveying the source location
9277 for which the error should be signaled. */
9279 static tree
9282 {
9289 /* If we are not doing any checks, the output is an integral type and the
9290 input is not a floating-point type, just do the conversion. This is
9291 required for packed array types and is simpler in all cases anyway. */
9293 && !overflow_p
9298 /* If the mode of the input base type is larger, then converting to it below
9299 may pessimize the final conversion step, for example generate a libcall
9300 instead of a simple instruction, so use a narrower type in this case. */
9307 /* First convert the expression to the base type. This will never generate
9308 code, but makes the tests below simpler. But don't do this if converting
9309 from an integer type to an unconstrained array type since then we need to
9310 get the bounds from the original (unpacked) type. */
9314 /* If overflow checks are requested, we need to be sure the result will fit
9315 in the output base type. But don't do this if the input is integer and
9316 the output floating-point. */
9319 {
9320 /* Ensure GNU_EXPR only gets evaluated once. */
9328 /* Convert the lower bounds to signed types, so we're sure we're
9329 comparing them properly. Likewise, convert the upper bounds
9330 to unsigned types. */
9333 gnu_in_lb
9338 gnu_in_ub
9342 gnu_out_lb
9346 gnu_out_ub
9349 /* Check each bound separately and only if the result bound
9350 is tighter than the bound on the input type. Note that all the
9351 types are base types, so the bounds must be constant. Also,
9352 the comparison is done in the base type of the input, which
9353 always has the proper signedness. First check for input
9354 integer (which means output integer), output float (which means
9355 both float), or mixed, in which case we always compare.
9356 Note that we have to do the comparison which would *fail* in the
9357 case of an error since if it's an FP comparison and one of the
9358 values is a NaN or Inf, the comparison will fail. */
9365 gnu_cond
9366 = invert_truthvalue
9369 gnu_out_lb)));
9377 gnu_cond
9379 invert_truthvalue
9381 gnu_input,
9383 gnu_out_ub))));
9388 }
9390 /* Now convert to the result base type. If this is a non-truncating
9391 float-to-integer conversion, round. */
9395 {
9401 /* The following calculations depend on proper rounding to even
9402 of each arithmetic operation. In order to prevent excess
9403 precision from spoiling this property, use the widest hardware
9404 floating-point type if FP_ARITH_MAY_WIDEN is true. */
9405 calc_type
9408 /* Compute the exact value calc_type'Pred (0.5) at compile time. */
9415 /* If the input is strictly negative, subtract this value
9416 and otherwise add it from the input. For 0.5, the result
9417 is exactly between 1.0 and the machine number preceding 1.0
9418 (for calc_type). Since the last bit of 1.0 is even, this 0.5
9419 will round to 1.0, while all other number with an absolute
9420 value less than 0.5 round to 0.0. For larger numbers exactly
9421 halfway between integers, rounding will always be correct as
9422 the true mathematical result will be closer to the higher
9423 integer compared to the lower one. So, this constant works
9424 for all floating-point numbers.
9426 The reason to use the same constant with subtract/add instead
9427 of a positive and negative constant is to allow the comparison
9428 to be scheduled in parallel with retrieval of the constant and
9429 conversion of the input to the calc_type (if necessary). */
9434 gnu_comp
9436 gnu_add_pred_half
9438 gnu_subtract_pred_half
9442 }
9448 else
9451 /* Finally, do the range check if requested. Note that if the result type
9452 is a modular type, the range check is actually an overflow check. */
9454 || (overflow_p
9460 }
9461 \f
9462 /* Return true if GNU_EXPR can be directly addressed. This is the case
9463 unless it is an expression involving computation or if it involves a
9464 reference to a bitfield or to an object not sufficiently aligned for
9465 its type. If GNU_TYPE is non-null, return true only if GNU_EXPR can
9466 be directly addressed as an object of this type.
9468 *** Notes on addressability issues in the Ada compiler ***
9470 This predicate is necessary in order to bridge the gap between Gigi
9471 and the middle-end about addressability of GENERIC trees. A tree
9472 is said to be addressable if it can be directly addressed, i.e. if
9473 its address can be taken, is a multiple of the type's alignment on
9474 strict-alignment architectures and returns the first storage unit
9475 assigned to the object represented by the tree.
9477 In the C family of languages, everything is in practice addressable
9478 at the language level, except for bit-fields. This means that these
9479 compilers will take the address of any tree that doesn't represent
9480 a bit-field reference and expect the result to be the first storage
9481 unit assigned to the object. Even in cases where this will result
9482 in unaligned accesses at run time, nothing is supposed to be done
9483 and the program is considered as erroneous instead (see PR c/18287).
9485 The implicit assumptions made in the middle-end are in keeping with
9486 the C viewpoint described above:
9487 - the address of a bit-field reference is supposed to be never
9488 taken; the compiler (generally) will stop on such a construct,
9489 - any other tree is addressable if it is formally addressable,
9490 i.e. if it is formally allowed to be the operand of ADDR_EXPR.
9492 In Ada, the viewpoint is the opposite one: nothing is addressable
9493 at the language level unless explicitly declared so. This means
9494 that the compiler will both make sure that the trees representing
9495 references to addressable ("aliased" in Ada parlance) objects are
9496 addressable and make no real attempts at ensuring that the trees
9497 representing references to non-addressable objects are addressable.
9499 In the first case, Ada is effectively equivalent to C and handing
9500 down the direct result of applying ADDR_EXPR to these trees to the
9501 middle-end works flawlessly. In the second case, Ada cannot afford
9502 to consider the program as erroneous if the address of trees that
9503 are not addressable is requested for technical reasons, unlike C;
9504 as a consequence, the Ada compiler must arrange for either making
9505 sure that this address is not requested in the middle-end or for
9506 compensating by inserting temporaries if it is requested in Gigi.
9508 The first goal can be achieved because the middle-end should not
9509 request the address of non-addressable trees on its own; the only
9510 exception is for the invocation of low-level block operations like
9511 memcpy, for which the addressability requirements are lower since
9512 the type's alignment can be disregarded. In practice, this means
9513 that Gigi must make sure that such operations cannot be applied to
9514 non-BLKmode bit-fields.
9516 The second goal is achieved by means of the addressable_p predicate,
9517 which computes whether a temporary must be inserted by Gigi when the
9518 address of a tree is requested; if so, the address of the temporary
9519 will be used in lieu of that of the original tree and some glue code
9520 generated to connect everything together. */
9522 static bool
9524 {
9525 /* For an integral type, the size of the actual type of the object may not
9526 be greater than that of the expected type, otherwise an indirect access
9527 in the latter type wouldn't correctly set all the bits of the object. */
9533 /* The size of the actual type of the object may not be smaller than that
9534 of the expected type, otherwise an indirect access in the latter type
9535 would be larger than the object. But only record types need to be
9536 considered in practice for this case. */
9543 {
9548 /* All DECLs are addressable: if they are in a register, we can force
9549 them to memory. */
9554 /* Taking the address of a dereference yields the original pointer. */
9559 /* Taking the address yields a pointer to the constant pool. */
9563 /* Taking the address of a static constructor yields a pointer to the
9564 tree constant pool. */
9576 /* All rvalues are deemed addressable since taking their address will
9577 force a temporary to be created by the middle-end. */
9581 /* The address of a compound expression is that of its 2nd operand. */
9585 /* We accept &COND_EXPR as soon as both operands are addressable and
9586 expect the outcome to be the address of the selected operand. */
9592 /* Even with DECL_BIT_FIELD cleared, we have to ensure that
9593 the field is sufficiently aligned, in case it is subject
9594 to a pragma Component_Alignment. But we don't need to
9595 check the alignment of the containing record, as it is
9596 guaranteed to be not smaller than that of its most
9597 aligned field that is not a bit-field. */
9598 && (!STRICT_ALIGNMENT
9601 /* The field of a padding record is always addressable. */
9615 {
9616 /* This is addressable if we can avoid a copy. */
9620 && (!STRICT_ALIGNMENT
9625 && (!STRICT_ALIGNMENT
9631 }
9635 }
9636 }
9637 \f
9638 /* Do the processing for the declaration of a GNAT_ENTITY, a type or subtype.
9639 If a Freeze node exists for the entity, delay the bulk of the processing.
9640 Otherwise make a GCC type for GNAT_ENTITY and set up the correspondence. */
9642 void
9644 {
9645 tree gnu_old
9648 /* If we are to delay elaboration of this type, just do any elaboration
9649 needed for expressions within the declaration and make a dummy node
9650 for it and its Full_View (if any), in case something points to it.
9651 Do not do this if it has already been done (the only way that can
9652 happen is if the private completion is also delayed). */
9654 {
9658 {
9663 {
9667 }
9668 }
9671 }
9673 /* If we saved away a dummy type for this node, it means that this made the
9674 type that corresponds to the full type of an incomplete type. Clear that
9675 type for now and then update the type in the pointers below. But, if the
9676 saved type is not dummy, it very likely means that we have a use before
9677 declaration for the type in the tree, what we really cannot handle. */
9679 {
9684 }
9686 /* Now fully elaborate the type. */
9690 /* If we have an old type and we've made pointers to this type, update those
9691 pointers. If this is a Taft amendment type in the main unit, we need to
9692 mark the type as used since other units referencing it don't see the full
9693 declaration and, therefore, cannot mark it as used themselves. */
9695 {
9700 }
9702 /* If this is a record type corresponding to a task or protected type
9703 that is a completion of an incomplete type, perform a similar update
9704 on the type. ??? Including protected types here is a guess. */
9708 {
9709 tree gnu_task_old
9719 }
9720 }
9721 \f
9722 /* Subroutine of assoc_to_constructor: VALUES is a list of field associations,
9723 some of which are from RECORD_TYPE. Return a CONSTRUCTOR consisting of the
9724 associations that are from RECORD_TYPE. If we see an internal record, make
9725 a recursive call to fill it in as well. */
9727 static tree
9729 {
9731 tree field;
9734 {
9737 /* _Parent is an internal field, but may have values in the aggregate,
9738 so check for values first. */
9740 {
9743 }
9746 {
9751 }
9752 else
9753 /* If we have a record subtype, the names will match, but not the
9754 actual FIELD_DECLs. */
9757 {
9760 }
9766 }
9769 }
9771 /* GNAT_ENTITY is the type of the resulting constructor, GNAT_ASSOC is the
9772 front of the Component_Associations of an N_Aggregate and GNU_TYPE is the
9773 GCC type of the corresponding record type. Return the CONSTRUCTOR. */
9775 static tree
9777 {
9780 /* We test for GNU_FIELD being empty in the case where a variant
9781 was the last thing since we don't take things off GNAT_ASSOC in
9782 that case. We check GNAT_ASSOC in case we have a variant, but it
9783 has no fields. */
9786 {
9791 /* The expander is supposed to put a single component selector name
9792 in every record component association. */
9795 /* Ignore discriminants that have Corresponding_Discriminants in tagged
9796 types since we'll be setting those fields in the parent subtype. */
9802 /* Also ignore discriminants of Unchecked_Unions. */
9807 /* Before assigning a value in an aggregate make sure range checks
9808 are done if required. Then convert to the type of the field. */
9814 /* Add the field and expression to the list. */
9816 }
9821 {
9822 /* Verify that every entry in GNU_LIST was used. */
9825 }
9828 }
9830 /* Build a possibly nested constructor for array aggregates. GNAT_EXPR is
9831 the first element of an array aggregate. It may itself be an aggregate.
9832 GNU_ARRAY_TYPE is the GCC type corresponding to the array aggregate.
9833 GNAT_COMPONENT_TYPE is the type of the array component; it is needed
9834 for range checking. */
9836 static tree
9838 Entity_Id gnat_component_type)
9839 {
9844 {
9845 tree gnu_expr;
9847 /* If the expression is itself an array aggregate then first build the
9848 innermost constructor if it is part of our array (multi-dimensional
9849 case). */
9855 gnat_component_type);
9856 else
9857 {
9858 /* If the expression is a conversion to an unconstrained array type,
9859 skip it to avoid spilling to memory. */
9864 else
9867 /* Before assigning the element to the array, make sure it is
9868 in range. */
9871 }
9878 integer_one_node));
9879 }
9882 }
9883 \f
9884 /* Process a N_Validate_Unchecked_Conversion node. */
9886 static void
9888 {
9892 /* If the target is a pointer type, see if we are either converting from a
9893 non-pointer or from a pointer to a type with a different alias set and
9894 warn if so, unless the pointer has been marked to alias everything. */
9897 {
9907 target_alias_set)))
9908 {
9912 gnat_node);
9915 }
9916 }
9918 /* Likewise if the target is a fat pointer type, but we have no mechanism to
9919 mitigate the problem in this case, so we unconditionally warn. */
9921 {
9922 tree gnu_source_desig_type
9926 tree gnu_target_desig_type
9933 target_alias_set)))
9934 {
9938 gnat_node);
9939 }
9940 }
9941 }
9942 \f
9943 /* EXP is to be used in a context where access objects are implicitly
9944 dereferenced. Handle the cases when it is an access object. */
9946 static Node_Id
9948 {
9951 /* Make sure the designated type is complete before dereferencing. */
9956 }
9958 /* EXP is to be treated as an array or record. Handle the cases when it is
9959 an access object and perform the required dereferences. */
9961 static tree
9963 {
9964 /* If the type is a pointer, dereference it. */
9969 /* If we got a padded type, remove it too. */
9974 }
9975 \f
9976 /* Convert SLOC into LOCUS. Return true if SLOC corresponds to a source code
9977 location and false if it doesn't. If CLEAR_COLUMN is true, set the column
9978 information to 0. */
9980 bool
9982 {
9987 {
9990 }
9997 /* We can have zero if pragma Source_Reference is in effect. */
10001 /* Translate the location. */
10002 *locus
10006 }
10008 /* Similar to set_expr_location, but start with the Sloc of GNAT_NODE and
10009 don't do anything if it doesn't correspond to a source location. And,
10010 if CLEAR_COLUMN is true, set the column information to 0. */
10012 static void
10014 {
10015 location_t locus;
10021 }
10023 /* More elaborate version of set_expr_location_from_node to be used in more
10024 general contexts, for example the result of the translation of a generic
10025 GNAT node. */
10027 static void
10029 {
10030 /* Set the location information on the node if it is a real expression.
10031 References can be reused for multiple GNAT nodes and they would get
10032 the location information of their last use. Also make sure not to
10033 overwrite an existing location as it is probably more precise. */
10036 {
10037 CASE_CONVERT:
10046 /* ... fall through ... */
10050 {
10053 }
10055 }
10056 }
10058 /* Set the end_locus information for GNU_NODE, if any, from an explicit end
10059 location associated with GNAT_NODE or GNAT_NODE itself, whichever makes
10060 most sense. Return true if a sensible assignment was performed. */
10062 static bool
10064 {
10065 Node_Id gnat_end_label;
10066 location_t end_locus;
10068 /* Pick the GNAT node of which we'll take the sloc to assign to the GCC node
10069 end_locus when there is one. We consider only GNAT nodes with a possible
10070 End_Label attached. If the End_Label actually was unassigned, fallback
10071 on the original node. We'd better assign an explicit sloc associated with
10072 the outer construct in any case. */
10075 {
10088 }
10093 /* Some expanded subprograms have neither an End_Label nor a Sloc
10094 attached. Notify that to callers. For a block statement with no
10095 End_Label, clear column information, so that the tree for a
10096 transient block does not receive the sloc of a source condition. */
10103 {
10114 }
10115 }
10116 \f
10117 /* Return a colon-separated list of encodings contained in encoded Ada
10118 name. */
10122 {
10126 }
10128 /* Extract the Ada name from an encoded name. */
10132 {
10136 }
10137 \f
10138 /* Post an error message. MSG is the error message, properly annotated.
10139 NODE is the node at which to post the error and the node to use for the
10140 '&' substitution. */
10142 void
10144 {
10145 String_Template temp;
10146 String_Pointer sp;
10156 }
10158 /* Similar to post_error, but NODE is the node at which to post the error and
10159 ENT is the node to use for the '&' substitution. */
10161 void
10163 {
10164 String_Template temp;
10165 String_Pointer sp;
10175 }
10177 /* Similar to post_error_ne, but NUM is the number to use for the '^'. */
10179 void
10181 {
10184 }
10186 /* Similar to post_error_ne, but T is a GCC tree representing the number to
10187 write. If T represents a constant, the text inside curly brackets in
10188 MSG will be output (presumably including a '^'). Otherwise it will not
10189 be output and the text inside square brackets will be output instead. */
10191 void
10193 {
10200 {
10203 }
10204 else
10208 {
10214 ;
10215 else
10217 }
10222 }
10224 /* Similar to post_error_ne_tree, but NUM is a second integer to write. */
10226 void
10229 {
10232 }
10234 /* Return a label to branch to for the exception type in KIND or Empty
10235 if none. */
10237 Entity_Id
10239 {
10241 {
10253 }
10256 }
10258 /* Return the decl for the current elaboration procedure. */
10260 static tree
10262 {
10264 }
10266 /* Initialize the table that maps GNAT codes to GCC codes for simple
10267 binary and unary operations. */
10269 static void
10271 {
10296 }