| blob | 9163eb10a7c86eb901229b34c00406916134cea3 |
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. */
254 /* Hooks for debug info back-ends, only supported and used in a restricted set
255 of configurations. */
258 \f
259 /* This is the main program of the back-end. It sets up all the table
260 structures and then generates code. */
262 void
275 Nat number_file,
277 Entity_Id standard_boolean,
278 Entity_Id standard_integer,
279 Entity_Id standard_character,
280 Entity_Id standard_long_long_float,
281 Entity_Id standard_exception_type,
282 Int gigi_operating_mode)
283 {
284 Node_Id gnat_iter;
285 Entity_Id gnat_literal;
305 {
306 /* Use the identifier table to make a permanent copy of the filename as
307 the name table gets reallocated after Gigi returns but before all the
308 debugging information is output. The __gnat_to_canonical_file_spec
309 call translates filenames from pragmas Source_Reference that contain
310 host style syntax not understood by gdb. */
312 = IDENTIFIER_POINTER
313 (get_identifier
314 (__gnat_to_canonical_file_spec
317 /* We rely on the order isomorphism between files and line maps. */
320 /* We create the line map for a source file at once, with a fixed number
321 of columns chosen to avoid jumping over the next power of 2. */
326 }
330 /* Declare the name of the compilation unit as the first global
331 name in order to make the middle-end fully deterministic. */
335 /* Initialize ourselves. */
340 /* If we are just annotating types, give VOID_TYPE zero sizes to avoid
341 errors. */
343 {
346 }
348 /* Enable GNAT stack checking method if needed */
352 /* Retrieve alignment settings. */
356 /* Record the builtin types. Define `integer' and `character' first so that
357 dbx will output them first. */
363 /* Save the type we made for integer as the type for Standard.Integer. */
368 /* Likewise for character as the type for Standard.Character. */
374 /* Likewise for boolean as the type for Standard.Boolean. */
393 /* Declare the building blocks of function nodes. */
398 /* Now declare run-time functions. */
400 malloc_decl
402 ftype,
408 free_decl
410 ftype,
415 NULL_TREE);
416 realloc_decl
418 ftype,
422 /* This is used for 64-bit multiplication with overflow checking. */
424 mulv64_decl
431 /* Name of the _Parent field in tagged record types. */
434 /* Name of the Exception_Data type defined in System.Standard_Library. */
435 exception_data_name_id
438 /* Make the types and functions used for exception processing. */
441 jmpbuf_type
447 /* Functions to get and set the jumpbuf pointer for the current thread. */
448 get_jmpbuf_decl
449 = create_subprog_decl
454 set_jmpbuf_decl
455 = create_subprog_decl
458 NULL_TREE),
461 get_excptr_decl
462 = create_subprog_decl
465 NULL_TREE),
471 {
474 }
477 /* setjmp returns an integer and has one operand, which is a pointer to
478 a jmpbuf. */
479 setjmp_decl
480 = create_subprog_decl
483 NULL_TREE),
488 /* update_setjmp_buf updates a setjmp buffer from the current stack pointer
489 address. */
490 update_setjmp_buf_decl
491 = create_subprog_decl
498 /* Indicate that it never returns. */
501 NULL_TREE);
503 raise_nodefer_decl
504 = create_subprog_decl
508 set_exception_parameter_decl
509 = create_subprog_decl
512 NULL_TREE),
515 /* Hooks to call when entering/leaving an exception handler. */
518 begin_handler_decl
522 Empty);
523 /* __gnat_begin_handler is a dummy procedure. */
526 end_handler_decl
530 Empty);
532 unhandled_except_decl
536 Empty);
538 /* Indicate that it never returns. */
540 reraise_zcx_decl
544 Empty);
546 /* Dummy objects to materialize "others" and "all others" in the exception
547 tables. These are exported by a-exexpr-gcc.adb, so see this unit for
548 the types to use. */
549 others_decl
556 all_others_decl
563 unhandled_others_decl
570 /* If in no exception handlers mode, all raise statements are redirected to
571 __gnat_last_chance_handler. No need to redefine raise_nodefer_decl since
572 this procedure will never be called in this mode. */
574 {
575 /* Indicate that it never returns. */
580 tree decl
581 = create_subprog_decl
584 Empty);
587 }
588 else
589 {
590 /* Otherwise, make one decl for each exception reason. */
596 i == CE_Index_Check_Failed
600 }
602 /* Build the special descriptor type and its null node if needed. */
604 {
616 {
617 tree field
624 elt--;
625 }
630 }
632 longest_float_type_node
637 /* If we are using the GCC exception mechanism, let GCC know. */
641 /* Initialize the GCC support for FP operations. */
644 /* Install the builtins we might need, either internally or as user-available
645 facilities for Intrinsic imports. Note that this must be done after the
646 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. */
2628 gnu_result
2632 }
2633 \f
2634 /* Return true if we are in the body of a loop. */
2638 {
2640 }
2642 /* Find out whether EXPR is a simple additive expression based on the iteration
2643 variable of some enclosing loop in the current function. If so, return the
2644 loop and set *DISP to the displacement and *NEG_P to true if this is for a
2645 subtraction; otherwise, return NULL. */
2649 {
2656 {
2662 }
2663 else
2664 {
2670 }
2687 }
2689 /* Return true if VAL (of type TYPE) can equal the minimum value if MAX is
2690 false, or the maximum value if MAX is true, of TYPE. */
2692 static bool
2694 {
2701 val = (max
2710 else
2712 }
2714 /* Return true if VAL (of type TYPE) can equal the minimum value of TYPE.
2715 If REVERSE is true, minimum value is taken as maximum value. */
2719 {
2721 }
2723 /* Return true if VAL (of type TYPE) can equal the maximum value of TYPE.
2724 If REVERSE is true, maximum value is taken as minimum value. */
2728 {
2730 }
2732 /* Return true if VAL1 can be lower than VAL2. */
2734 static bool
2736 {
2750 }
2752 /* Replace EXPR1 and EXPR2 by invariant expressions if possible. Return
2753 true if both expressions have been replaced and false otherwise. */
2755 static bool
2757 {
2768 }
2770 /* Helper function for walk_tree, used by independent_iterations_p below. */
2772 static tree
2774 {
2778 /* No need to walk into types or decls. */
2786 }
2788 /* Return true if STMT_LIST generates independent iterations in a loop. */
2790 static bool
2792 {
2793 tree_stmt_iterator tsi;
2796 tree iter;
2802 /* Scan the list and return false on anything that is not either a check
2803 or an assignment to a parameter with restricted aliasing. */
2805 {
2809 {
2811 {
2820 }
2823 {
2836 }
2840 }
2841 }
2843 /* At this point we know that the list contains only statements that will
2844 modify parameters with restricted aliasing. Check that the statements
2845 don't at the time read from these parameters. */
2851 }
2853 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Loop_Statement,
2854 to a GCC tree, which is returned. */
2856 static tree
2858 {
2865 tree gnu_result;
2867 /* Push the loop_info structure associated with the LOOP_STMT. */
2870 /* Set location information for statement and end label. */
2876 /* Save the statement for later reuse. */
2880 /* Set the condition under which the loop must keep going.
2881 For the case "LOOP .... END LOOP;" the condition is always true. */
2883 ;
2885 /* For the case "WHILE condition LOOP ..... END LOOP;" it's immediate. */
2890 /* Otherwise we have an iteration scheme and the condition is given by the
2891 bounds of the subtype of the iteration variable. */
2892 else
2893 {
2907 /* We must disable modulo reduction for the iteration variable, if any,
2908 in order for the loop comparison to be effective. */
2910 {
2916 }
2917 else
2918 {
2924 }
2926 /* We use two different strategies to translate the loop, depending on
2927 whether optimization is enabled.
2929 If it is, we generate the canonical loop form expected by the loop
2930 optimizer and the loop vectorizer, which is the do-while form:
2932 ENTRY_COND
2933 loop:
2934 TOP_UPDATE
2935 BODY
2936 BOTTOM_COND
2937 GOTO loop
2939 This avoids an implicit dependency on loop header copying and makes
2940 it possible to turn BOTTOM_COND into an inequality test.
2942 If optimization is disabled, loop header copying doesn't come into
2943 play and we try to generate the loop form with the fewer conditional
2944 branches. First, the default form, which is:
2946 loop:
2947 TOP_COND
2948 BODY
2949 BOTTOM_UPDATE
2950 GOTO loop
2952 It should catch most loops with constant ending point. Then, if we
2953 cannot, we try to generate the shifted form:
2955 loop:
2956 TOP_COND
2957 TOP_UPDATE
2958 BODY
2959 GOTO loop
2961 which should catch loops with constant starting point. Otherwise, if
2962 we cannot, we generate the fallback form:
2964 ENTRY_COND
2965 loop:
2966 BODY
2967 BOTTOM_COND
2968 BOTTOM_UPDATE
2969 GOTO loop
2971 which works in all cases. */
2974 {
2975 /* We can use the do-while form directly if GNU_FIRST-1 doesn't
2976 overflow. */
2978 ;
2980 /* Otherwise, use the do-while form with the help of a special
2981 induction variable in the unsigned version of the base type
2982 or the unsigned version of the size type, whichever is the
2983 largest, in order to have wrap-around arithmetics for it. */
2984 else
2985 {
2988 gnu_base_type
2990 else
2997 }
2999 gnu_first
3001 gnu_one_node);
3004 }
3005 else
3006 {
3007 /* We can use the default form if GNU_LAST+1 doesn't overflow. */
3009 ;
3011 /* Otherwise, we can use the shifted form if neither GNU_FIRST-1 nor
3012 GNU_LAST-1 does. */
3015 {
3016 gnu_first
3018 gnu_one_node);
3019 gnu_last
3021 gnu_one_node);
3023 }
3025 /* Otherwise, use the fallback form. */
3026 else
3028 }
3030 /* If we use the BOTTOM_COND, we can turn the test into an inequality
3031 test but we may have to add ENTRY_COND to protect the empty loop. */
3033 {
3036 {
3037 gnu_cond_expr
3043 }
3044 }
3046 /* Open a new nesting level that will surround the loop to declare the
3047 iteration variable. */
3051 /* If we use the special induction variable, create it and set it to
3052 its initial value. Morever, the regular iteration variable cannot
3053 itself be initialized, lest the initial value wrapped around. */
3055 {
3056 gnu_loop_iv
3060 }
3061 else
3064 /* Declare the iteration variable and set it to its initial value. */
3069 {
3072 }
3077 /* Do all the arithmetics in the base type. */
3080 /* Set either the top or bottom exit condition. */
3084 gnu_last);
3085 else
3088 gnu_last);
3090 /* Set either the top or bottom update statement and give it the source
3091 location of the iteration for better coverage info. */
3093 {
3094 gnu_stmt
3101 gnu_stmt
3103 gnu_loop_iv);
3107 }
3108 else
3109 {
3110 gnu_stmt
3116 }
3117 }
3119 /* If the loop was named, have the name point to this loop. In this case,
3120 the association is not a DECL node, but the end label of the loop. */
3124 /* Make the loop body into its own block, so any allocated storage will be
3125 released every iteration. This is needed for stack allocation. */
3130 /* If we have an iteration scheme, then we are in a statement group. Add
3131 the LOOP_STMT to it, finish it and make it the "loop". */
3133 {
3134 /* First, if we have computed invariant conditions for range (or index)
3135 checks applied to the iteration variable, find out whether they can
3136 be evaluated to false at compile time; otherwise, if there are not
3137 too many of them, combine them with the original checks. If loop
3138 unswitching is enabled, do not require the loop bounds to be also
3139 invariant, as their evaluation will still be ahead of the loop. */
3142 {
3147 {
3151 {
3154 gnu_adjusted_low
3157 low_ok
3160 }
3161 else
3165 {
3168 gnu_adjusted_high
3171 high_ok
3174 }
3175 else
3178 tree range_ok
3182 rci->invariant_cond
3187 else
3188 n_remaining_checks++;
3189 }
3191 /* Note that loop unswitching can only be applied a small number of
3192 times to a given loop (PARAM_MAX_UNSWITCH_LEVEL default to 3). */
3197 {
3202 }
3203 }
3205 /* Second, if loop vectorization is enabled and the iterations of the
3206 loop can easily be proved as independent, mark the loop. */
3208 && flag_tree_loop_vectorize
3215 }
3217 /* If we have an outer COND_EXPR, that's our result and this loop is its
3218 "true" statement. Otherwise, the result is the LOOP_STMT. */
3220 {
3224 }
3225 else
3231 }
3232 \f
3233 /* This page implements a form of Named Return Value optimization modelled
3234 on the C++ optimization of the same name. The main difference is that
3235 we disregard any semantical considerations when applying it here, the
3236 counterpart being that we don't try to apply it to semantically loaded
3237 return types, i.e. types with the TYPE_BY_REFERENCE_P flag set.
3239 We consider a function body of the following GENERIC form:
3241 return_type R1;
3242 [...]
3243 RETURN_EXPR [<retval> = ...]
3244 [...]
3245 RETURN_EXPR [<retval> = R1]
3246 [...]
3247 return_type Ri;
3248 [...]
3249 RETURN_EXPR [<retval> = ...]
3250 [...]
3251 RETURN_EXPR [<retval> = Ri]
3252 [...]
3254 where the Ri are not addressable and we try to fulfill a simple criterion
3255 that would make it possible to replace one or several Ri variables by the
3256 single RESULT_DECL of the function.
3258 The first observation is that RETURN_EXPRs that don't directly reference
3259 any of the Ri variables on the RHS of their assignment are transparent wrt
3260 the optimization. This is because the Ri variables aren't addressable so
3261 any transformation applied to them doesn't affect the RHS; moreover, the
3262 assignment writes the full <retval> object so existing values are entirely
3263 discarded.
3265 This property can be extended to some forms of RETURN_EXPRs that reference
3266 the Ri variables, for example CONSTRUCTORs, but isn't true in the general
3267 case, in particular when function calls are involved.
3269 Therefore the algorithm is as follows:
3271 1. Collect the list of candidates for a Named Return Value (Ri variables
3272 on the RHS of assignments of RETURN_EXPRs) as well as the list of the
3273 other expressions on the RHS of such assignments.
3275 2. Prune the members of the first list (candidates) that are referenced
3276 by a member of the second list (expressions).
3278 3. Extract a set of candidates with non-overlapping live ranges from the
3279 first list. These are the Named Return Values.
3281 4. Adjust the relevant RETURN_EXPRs and replace the occurrences of the
3282 Named Return Values in the function with the RESULT_DECL.
3284 If the function returns an unconstrained type, things are a bit different
3285 because the anonymous return object is allocated on the secondary stack
3286 and RESULT_DECL is only a pointer to it. Each return object can be of a
3287 different size and is allocated separately so we need not care about the
3288 addressability and the aforementioned overlapping issues. Therefore, we
3289 don't collect the other expressions and skip step #2 in the algorithm. */
3291 struct nrv_data
3292 {
3293 bitmap nrv;
3294 tree result;
3295 Node_Id gnat_ret;
3297 };
3299 /* Return true if T is a Named Return Value. */
3303 {
3305 }
3307 /* Helper function for walk_tree, used by finalize_nrv below. */
3309 static tree
3311 {
3315 /* No need to walk into types or decls. */
3323 }
3325 /* Prune Named Return Values in BLOCK and return true if there is still a
3326 Named Return Value in BLOCK or one of its sub-blocks. */
3328 static bool
3330 {
3332 tree t;
3334 /* First recurse on the sub-blocks. */
3338 /* Then make sure to keep at most one NRV per block. */
3341 {
3344 else
3346 }
3349 }
3351 /* Helper function for walk_tree, used by finalize_nrv below. */
3353 static tree
3355 {
3359 /* No need to walk into types. */
3363 /* Change RETURN_EXPRs of NRVs to just refer to the RESULT_DECL; this is a
3364 nop, but differs from using NULL_TREE in that it indicates that we care
3365 about the value of the RESULT_DECL. */
3368 {
3371 /* Strip useless conversions around the return value. */
3377 }
3379 /* Replace the DECL_EXPR of NRVs with an initialization of the RESULT_DECL,
3380 if needed. */
3383 {
3387 {
3392 }
3393 else
3397 /* Identify the NRV to the RESULT_DECL for debugging purposes. */
3400 /* ??? Kludge to avoid an assertion failure during inlining. */
3403 }
3405 /* And replace all uses of NRVs with the RESULT_DECL. */
3409 /* Avoid walking into the same tree more than once. Unfortunately, we
3410 can't just use walk_tree_without_duplicates because it would only
3411 call us for the first occurrence of NRVs in the function body. */
3416 }
3418 /* Likewise, but used when the function returns an unconstrained type. */
3420 static tree
3422 {
3426 /* No need to walk into types. */
3430 /* We need to see the DECL_EXPR of NRVs before any other references so we
3431 walk the body of BIND_EXPR before walking its variables. */
3435 /* Change RETURN_EXPRs of NRVs to assign to the RESULT_DECL only the final
3436 return value built by the allocator instead of the whole construct. */
3439 {
3442 /* This is the construct returned by the allocator. */
3445 {
3450 else
3452 }
3454 /* Strip useless conversions around the return value. */
3459 /* Strip unpadding around the return value. */
3464 /* Assign the new return value to the RESULT_DECL. */
3468 }
3470 /* Adjust the DECL_EXPR of NRVs to call the allocator and save the result
3471 into a new variable. */
3474 {
3481 /* Create an artificial context to build the allocation. */
3486 /* This will return a COMPOUND_EXPR with the allocation in the first
3487 arm and the final return value in the second arm. */
3494 /* The new variable is built as a reference to the allocated space. */
3495 new_var
3501 {
3504 /* The new initial value is a COMPOUND_EXPR with the allocation in
3505 the first arm and the value of P_ARRAY in the second arm. */
3511 /* Build a modified CONSTRUCTOR that references NEW_VAR. */
3518 }
3519 else
3520 {
3521 /* The new initial value is just the allocation. */
3524 }
3528 /* Destroy the artificial context and insert the new statements. */
3533 /* Chain NEW_VAR immediately after VAR and ignore the latter. */
3538 /* Save the new return value and the dereference of NEW_VAR. */
3542 /* ??? Kludge to avoid messing up during inlining. */
3544 }
3546 /* And replace all uses of NRVs with the dereference of NEW_VAR. */
3550 /* Avoid walking into the same tree more than once. Unfortunately, we
3551 can't just use walk_tree_without_duplicates because it would only
3552 call us for the first occurrence of NRVs in the function body. */
3557 }
3559 /* Finalize the Named Return Value optimization for FNDECL. The NRV bitmap
3560 contains the candidates for Named Return Value and OTHER is a list of
3561 the other return values. GNAT_RET is a representative return node. */
3563 static void
3565 {
3568 walk_tree_fn func;
3570 tree iter;
3572 /* We shouldn't be applying the optimization to return types that we aren't
3573 allowed to manipulate freely. */
3576 /* Prune the candidates that are referenced by other return values. */
3586 /* Prune also the candidates that are referenced by nested functions. */
3594 /* Extract a set of NRVs with non-overlapping live ranges. */
3598 /* Adjust the relevant RETURN_EXPRs and replace the occurrences of NRVs. */
3605 else
3609 }
3611 /* Return true if RET_VAL can be used as a Named Return Value for the
3612 anonymous return object RET_OBJ. */
3614 static bool
3616 {
3629 /* For the constrained case, test for addressability. */
3633 /* For the constrained case, test for overalignment. */
3637 /* For the unconstrained case, test for bogus initialization. */
3644 }
3646 /* Build a RETURN_EXPR. If RET_VAL is non-null, build a RETURN_EXPR around
3647 the assignment of RET_VAL to RET_OBJ. Otherwise build a bare RETURN_EXPR
3648 around RESULT_OBJ, which may be null in this case. */
3650 static tree
3652 {
3653 tree result_expr;
3656 {
3657 /* The gimplifier explicitly enforces the following invariant:
3659 RETURN_EXPR
3660 |
3661 INIT_EXPR
3662 / \
3663 / \
3664 RET_OBJ ...
3666 As a consequence, type consistency dictates that we use the type
3667 of the RET_OBJ as the operation type. */
3670 /* Convert the right operand to the operation type. Note that this is
3671 the transformation applied in the INIT_EXPR case of build_binary_op,
3672 with the assumption that the type cannot involve a placeholder. */
3676 /* We always can use an INIT_EXPR for the return object. */
3679 /* If the function returns an aggregate type, find out whether this is
3680 a candidate for Named Return Value. If so, record it. Otherwise,
3681 if this is an expression of some kind, record it elsewhere. */
3687 {
3688 /* Strip useless conversions around the return value. */
3692 /* Now apply the test to the return value. */
3694 {
3698 }
3700 /* Note that we need not care about CONSTRUCTORs here, as they are
3701 totally transparent given the read-compose-write semantics of
3702 assignments from CONSTRUCTORs. */
3705 }
3706 }
3707 else
3711 }
3712 \f
3713 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Subprogram_Body. We
3714 don't return anything. */
3716 static void
3718 {
3719 /* Defining identifier of a parameter to the subprogram. */
3720 Entity_Id gnat_param;
3721 /* The defining identifier for the subprogram body. Note that if a
3722 specification has appeared before for this body, then the identifier
3723 occurring in that specification will also be a defining identifier and all
3724 the calls to this subprogram will point to that specification. */
3725 Entity_Id gnat_subprog_id
3728 /* The FUNCTION_DECL node corresponding to the subprogram spec. */
3729 tree gnu_subprog_decl;
3730 /* Its RESULT_DECL node. */
3731 tree gnu_result_decl;
3732 /* Its FUNCTION_TYPE node. */
3733 tree gnu_subprog_type;
3734 /* The TYPE_CI_CO_LIST of its FUNCTION_TYPE node, if any. */
3735 tree gnu_cico_list;
3736 /* The entry in the CI_CO_LIST that represents a function return, if any. */
3738 tree gnu_result;
3739 location_t locus;
3743 /* If this is a generic object or if it has been eliminated,
3744 ignore it. */
3750 /* If this subprogram acts as its own spec, define it. Otherwise, just get
3751 the already-elaborated tree node. However, if this subprogram had its
3752 elaboration deferred, we will already have made a tree node for it. So
3753 treat it as not being defined in that case. Such a subprogram cannot
3754 have an address clause or a freeze node, so this test is safe, though it
3755 does disable some otherwise-useful error checking. */
3756 gnu_subprog_decl
3767 /* If the function returns by invisible reference, make it explicit in the
3768 function body. See gnat_to_gnu_entity, E_Subprogram_Type case. */
3770 {
3774 }
3776 /* Set the line number in the decl to correspond to that of the body. */
3780 /* Initialize the information structure for the function. */
3789 /* If there are copy-in/copy-out parameters, we need to ensure that they are
3790 properly copied out by the return statement. We do this by making a new
3791 block and converting any return into a goto to a label at the end of the
3792 block. */
3794 {
3803 /* If this is a function with copy-in/copy-out parameters and which does
3804 not return by invisible reference, we also need a variable for the
3805 return value to be placed. */
3807 {
3808 tree gnu_return_type
3811 gnu_return_var
3817 }
3821 /* See whether there are parameters for which we don't have a GCC tree
3822 yet. These must be Out parameters. Make a VAR_DECL for them and
3823 put it into TYPE_CI_CO_LIST, which must contain an empty entry too.
3824 We can match up the entries because TYPE_CI_CO_LIST is in the order
3825 of the parameters. */
3830 {
3832 tree gnu_decl;
3834 /* Skip any entries that have been already filled in; they must
3835 correspond to In Out parameters. */
3839 /* Do any needed dereferences for by-ref objects. */
3845 /* Do any needed references for padded types. */
3848 }
3849 }
3850 else
3853 /* Get a tree corresponding to the code for the subprogram. */
3859 /* Generate the code of the subprogram itself. A return statement will be
3860 present and any Out parameters will be handled there. */
3865 /* If we populated the parameter attributes cache, we need to make sure that
3866 the cached expressions are evaluated on all the possible paths leading to
3867 their uses. So we force their evaluation on entry of the function. */
3870 {
3877 {
3884 }
3890 }
3892 /* If we are dealing with a return from an Ada procedure with parameters
3893 passed by copy-in/copy-out, we need to return a record containing the
3894 final values of these parameters. If the list contains only one entry,
3895 return just that entry though.
3897 For a full description of the copy-in/copy-out parameter mechanism, see
3898 the part of the gnat_to_gnu_entity routine dealing with the translation
3899 of subprograms.
3901 We need to make a block that contains the definition of that label and
3902 the copying of the return value. It first contains the function, then
3903 the label and copy statement. */
3905 {
3906 const Node_Id gnat_end_label
3915 /* If this is a function which returns by invisible reference, the
3916 return value has already been dealt with at the return statements,
3917 so we only need to indirectly copy out the parameters. */
3919 {
3920 tree gnu_ret_deref
3922 tree t;
3927 {
3928 tree gnu_field_deref
3933 }
3934 }
3936 /* Otherwise, if this is a procedure or a function which does not return
3937 by invisible reference, we can do a direct block-copy out. */
3938 else
3939 {
3940 tree gnu_retval;
3944 else
3945 gnu_retval
3947 gnu_cico_list);
3951 }
3955 }
3959 /* Attempt setting the end_locus of our GCC body tree, typically a
3960 BIND_EXPR or STATEMENT_LIST, then the end_locus of our GCC subprogram
3961 declaration tree. */
3965 /* On SEH targets, install an exception handler around the main entry
3966 point to catch unhandled exceptions. */
3969 {
3970 tree t;
3971 tree etype;
3983 }
3987 /* Finally annotate the parameters and disconnect the trees for parameters
3988 that we have turned into variables since they are now unusable. */
3992 {
4001 }
4003 /* Disconnect the variable created for the return value. */
4007 /* If the function returns an aggregate type and we have candidates for
4008 a Named Return Value, finalize the optimization. */
4010 {
4017 }
4019 /* If this is an inlined external function that has been marked uninlinable,
4020 drop the body and stop there. Otherwise compile the body. */
4023 else
4025 }
4026 \f
4027 /* Return true if GNAT_NODE references an Atomic entity. */
4029 static bool
4031 {
4032 Entity_Id gnat_entity;
4035 {
4054 /* ... fall through ... */
4061 }
4064 }
4066 /* Return true if GNAT_NODE references a Volatile_Full_Access entity. */
4068 static bool
4070 {
4071 Entity_Id gnat_entity;
4074 {
4094 }
4097 }
4099 /* Strip any type conversion on GNAT_NODE and return the result. */
4101 static Node_Id
4103 {
4110 }
4112 /* Return true if GNAT_NODE requires outer atomic access, i.e. atomic access
4113 of an object of which GNAT_NODE is a component. */
4115 static bool
4117 {
4121 {
4123 {
4128 gnat_node
4142 }
4143 }
4146 }
4148 /* Return true if GNAT_NODE requires atomic access and set SYNC according to
4149 the associated synchronization setting. */
4151 static bool
4153 {
4158 /* First, scan the parent to find out cases where the flag is irrelevant. */
4160 {
4163 /* Do not mess up machine code insertions. */
4167 /* Nothing to do if we are the prefix of an attribute, since we do not
4168 want an atomic access for things like 'Size. */
4170 /* ... fall through ... */
4173 /* The N_Reference node is like an attribute. */
4181 /* If we are the prefix, then the access is only partial. */
4187 /* Nothing to do for the identifier in an object renaming declaration,
4188 the renaming itself does not need atomic access. */
4193 }
4195 /* Then, scan the node to find the atomic object. */
4198 /* For Atomic itself, only reads and updates of the object as a whole require
4199 atomic access (RM C.6 (15)). But for Volatile_Full_Access, all reads and
4200 updates require atomic access. */
4205 /* If an outer atomic access will also be required, it cancels this one. */
4212 }
4213 \f
4214 /* Create a temporary variable with PREFIX and TYPE, and return it. */
4216 static tree
4218 {
4219 tree gnu_temp
4225 }
4227 /* Create a temporary variable with PREFIX and initialize it with GNU_INIT.
4228 Put the initialization statement into GNU_INIT_STMT and annotate it with
4229 the SLOC of GNAT_NODE. Return the temporary variable. */
4231 static tree
4233 Node_Id gnat_node)
4234 {
4241 }
4243 /* Subroutine of gnat_to_gnu to translate gnat_node, either an N_Function_Call
4244 or an N_Procedure_Call_Statement, to a GCC tree, which is returned.
4245 GNU_RESULT_TYPE_P is a pointer to where we should place the result type.
4246 If GNU_TARGET is non-null, this must be a function call on the RHS of a
4247 N_Assignment_Statement and the result is to be placed into that object.
4248 If OUTER_ATOMIC_ACCESS is true, then the assignment to GNU_TARGET must be a
4249 load-modify-store sequence. Otherwise, if ATOMIC_ACCESS is true, then the
4250 assignment to GNU_TARGET must be atomic. If, in addition, ATOMIC_SYNC is
4251 true, then the assignment to GNU_TARGET requires atomic synchronization. */
4253 static tree
4256 {
4259 /* The GCC node corresponding to the GNAT subprogram name. This can either
4260 be a FUNCTION_DECL node if we are dealing with a standard subprogram call,
4261 or an indirect reference expression (an INDIRECT_REF node) pointing to a
4262 subprogram. */
4264 /* The FUNCTION_TYPE node giving the GCC type of the subprogram. */
4266 /* The return type of the FUNCTION_TYPE. */
4278 Entity_Id gnat_formal;
4279 Node_Id gnat_actual;
4284 /* If we are calling a stubbed function, raise Program_Error, but Elaborate
4285 all our args first. */
4287 {
4297 {
4300 }
4303 }
4305 /* For a call to a nested function, check the inlining status. */
4310 /* The only way we can be making a call via an access type is if Name is an
4311 explicit dereference. In that case, get the list of formal args from the
4312 type the access type is pointing to. Otherwise, get the formals from the
4313 entity being called. */
4315 {
4318 /* If the access type doesn't require foreign-compatible representation,
4319 be prepared for descriptors. */
4323 }
4325 /* Assume here that this must be 'Elab_Body or 'Elab_Spec. */
4327 else
4330 /* The lifetime of the temporaries created for the call ends right after the
4331 return value is copied, so we can give them the scope of the elaboration
4332 routine at top level. */
4334 {
4337 }
4339 /* First, create the temporary for the return value when:
4341 1. There is no target and the function has copy-in/copy-out parameters,
4342 because we need to preserve the return value before copying back the
4343 parameters.
4345 2. There is no target and the call is made for neither an object nor a
4346 renaming declaration, nor a return statement, nor an allocator, and
4347 the return type has variable size because in this case the gimplifier
4348 cannot create the temporary, or more generally is simply an aggregate
4349 type, because the gimplifier would then create the temporary in the
4350 outermost scope instead of locally.
4352 3. There is a target and it is a slice or an array with fixed size,
4353 and the return type has variable size, because the gimplifier
4354 doesn't handle these cases.
4356 4. There is no target and we have misaligned In Out or Out parameters
4357 passed by reference, because we need to preserve the return value
4358 before copying back the parameters. However, in this case, we'll
4359 defer creating the temporary, see below.
4361 This must be done before we push a binding level around the call, since
4362 we will pop it before copying the return value. */
4365 || (!gnu_target
4373 || (gnu_target
4379 {
4382 }
4384 /* If we don't need a value or have already created it, push a binding level
4385 around the call. This will narrow the lifetime of the temporaries we may
4386 need to make when translating the parameters as much as possible. */
4388 {
4392 }
4394 /* Create the list of the actual parameters as GCC expects it, namely a
4395 chain of TREE_LIST nodes in which the TREE_VALUE field of each node
4396 is an expression and the TREE_PURPOSE field is null. But skip Out
4397 parameters not passed by reference and that need not be copied in. */
4402 {
4407 const bool is_true_formal_parm
4409 const bool is_by_ref_formal_parm
4410 = is_true_formal_parm
4413 /* In the Out or In Out case, we must suppress conversions that yield
4414 an lvalue but can nevertheless cause the creation of a temporary,
4415 because we need the real object in this case, either to pass its
4416 address if it's passed by reference or as target of the back copy
4417 done after the call if it uses the copy-in/copy-out mechanism.
4418 We do it in the In case too, except for an unchecked conversion
4419 to an elementary type or a constrained composite type because it
4420 alone can cause the actual to be misaligned and the addressability
4421 test is applied to the real object. */
4422 const bool suppress_type_conversion
4429 Node_Id gnat_name = suppress_type_conversion
4433 /* If it's possible we may need to use this expression twice, make sure
4434 that any side-effects are handled via SAVE_EXPRs; likewise if we need
4435 to force side-effects before the call. */
4437 {
4441 gnu_name
4443 }
4445 /* If we are passing a non-addressable parameter by reference, pass the
4446 address of a copy. In the Out or In Out case, set up to copy back
4447 out after the call. */
4451 {
4455 /* Do not issue warnings for CONSTRUCTORs since this is not a copy
4456 but sort of an instantiation for them. */
4458 ;
4460 /* If the type is passed by reference, a copy is not allowed. */
4463 gnat_actual);
4465 /* For users of Starlet we issue a warning because the interface
4466 apparently assumes that by-ref parameters outlive the procedure
4467 invocation. The code still will not work as intended, but we
4468 cannot do much better since low-level parts of the back-end
4469 would allocate temporaries at will because of the misalignment
4470 if we did not do so here. */
4472 {
4473 post_error
4475 post_error_ne
4479 gnat_formal);
4480 }
4482 /* If the actual type of the object is already the nominal type,
4483 we have nothing to do, except if the size is self-referential
4484 in which case we'll remove the unpadding below. */
4487 ;
4489 /* Otherwise remove the unpadding from all the objects. */
4491 && TYPE_IS_PADDING_P
4495 /* Otherwise convert to the nominal type of the object if needed.
4496 There are several cases in which we need to make the temporary
4497 using this type instead of the actual type of the object when
4498 they are distinct, because the expectations of the callee would
4499 otherwise not be met:
4500 - if it's a justified modular type,
4501 - if the actual type is a smaller form of it,
4502 - if it's a smaller form of the actual type. */
4506 gnu_name_type)))
4512 /* If this is an In Out or Out parameter and we're returning a value,
4513 we need to create a temporary for the return value because we must
4514 preserve it before copying back at the very end. */
4516 {
4519 }
4521 /* If we haven't pushed a binding level, push it now. This will
4522 narrow the lifetime of the temporary we are about to make as
4523 much as possible. */
4525 {
4529 }
4531 /* Create an explicit temporary holding the copy. */
4532 gnu_temp
4535 /* But initialize it on the fly like for an implicit temporary as
4536 we aren't necessarily having a statement list. */
4538 gnu_temp);
4540 /* Set up to move the copy back to the original if needed. */
4542 {
4543 /* If the original is a COND_EXPR whose first arm isn't meant to
4544 be further used, just deal with the second arm. This is very
4545 likely the conditional expression built for a check. */
4548 && integer_zerop
4552 gnu_stmt
4557 }
4558 }
4560 /* Start from the real object and build the actual. */
4563 /* If atomic access is required for an In or In Out actual parameter,
4564 build the atomic load. */
4566 && !is_by_ref_formal_parm
4571 /* If this was a procedure call, we may not have removed any padding.
4572 So do it here for the part we will use as an input, if any. */
4575 gnu_actual
4578 /* Put back the conversion we suppressed above in the computation of the
4579 real object. And even if we didn't suppress any conversion there, we
4580 may have suppressed a conversion to the Etype of the actual earlier,
4581 since the parent is a procedure call, so put it back here. Note that
4582 we might have a dummy type here if the actual is the dereference of a
4583 pointer to it, but that's OK if the formal is passed by reference. */
4591 else
4594 /* Make sure that the actual is in range of the formal's type. */
4597 gnu_actual
4600 /* Unless this is an In parameter, we must remove any justified modular
4601 building from GNU_NAME to get an lvalue. */
4606 gnu_name
4609 /* First see if the parameter is passed by reference. */
4611 {
4613 {
4614 /* In Out or Out parameters passed by reference don't use the
4615 copy-in/copy-out mechanism so the address of the real object
4616 must be passed to the function. */
4619 /* If we have a padded type, be sure we've removed padding. */
4622 gnu_actual);
4624 /* If we have the constructed subtype of an aliased object
4625 with an unconstrained nominal subtype, the type of the
4626 actual includes the template, although it is formally
4627 constrained. So we need to convert it back to the real
4628 constructed subtype to retrieve the constrained part
4629 and takes its address. */
4635 gnu_actual);
4636 }
4638 /* There is no need to convert the actual to the formal's type before
4639 taking its address. The only exception is for unconstrained array
4640 types because of the way we build fat pointers. */
4642 {
4643 /* Put back a view conversion for In Out or Out parameters. */
4646 gnu_actual);
4648 }
4650 /* The symmetry of the paths to the type of an entity is broken here
4651 since arguments don't know that they will be passed by ref. */
4654 }
4656 /* Then see if the parameter is an array passed to a foreign convention
4657 subprogram. */
4659 {
4665 {
4668 }
4670 /* Take the address of the object and convert to the proper pointer
4671 type. We'd like to actually compute the address of the beginning
4672 of the array using an ADDR_EXPR of an ARRAY_REF, but there's a
4673 possibility that the ARRAY_REF might return a constant and we'd be
4674 getting the wrong address. Neither approach is exactly correct,
4675 but this is the most likely to work in all cases. */
4677 }
4679 /* Otherwise the parameter is passed by copy. */
4680 else
4681 {
4682 tree gnu_size;
4687 /* If we didn't create a PARM_DECL for the formal, this means that
4688 it is an Out parameter not passed by reference and that need not
4689 be copied in. In this case, the value of the actual need not be
4690 read. However, we still need to make sure that its side-effects
4691 are evaluated before the call, so we evaluate its address. */
4693 {
4695 {
4698 }
4700 }
4704 /* If this is 'Null_Parameter, pass a zero even though we are
4705 dereferencing it. */
4711 {
4712 tree type_for_size
4714 gnu_actual
4718 }
4719 else
4721 }
4724 }
4726 gnu_call
4731 /* If we have created a temporary for the return value, initialize it. */
4733 {
4734 tree gnu_stmt
4739 }
4741 /* If this is a subprogram with copy-in/copy-out parameters, we need to
4742 unpack the valued returned from the function into the In Out or Out
4743 parameters. We deal with the function return (if this is an Ada
4744 function) below. */
4746 {
4747 /* List of FIELD_DECLs associated with the PARM_DECLs of the copy-in/
4748 copy-out parameters. */
4752 /* The call sequence must contain one and only one call, even though the
4753 function is pure. Save the result into a temporary if needed. */
4755 {
4757 {
4758 tree gnu_stmt;
4759 gnu_call
4762 }
4765 }
4767 /* The first entry is for the actual return value if this is a
4768 function, so skip it. */
4774 else
4781 /* If we are dealing with a copy-in/copy-out parameter, we must
4782 retrieve its value from the record returned in the call. */
4788 {
4789 /* Get the value to assign to this Out or In Out parameter. It is
4790 either the result of the function if there is only a single such
4791 parameter or the appropriate field from the record returned. */
4792 tree gnu_result
4794 ? gnu_call
4798 /* If the actual is a conversion, get the inner expression, which
4799 will be the real destination, and convert the result to the
4800 type of the actual parameter. */
4801 tree gnu_actual
4804 /* If the result is a padded type, remove the padding. */
4806 gnu_result
4808 gnu_result);
4810 /* If the actual is a type conversion, the real target object is
4811 denoted by the inner Expression and we need to convert the
4812 result to the associated type.
4813 We also need to convert our gnu assignment target to this type
4814 if the corresponding GNU_NAME was constructed from the GNAT
4815 conversion node and not from the inner Expression. */
4817 {
4818 gnu_result
4819 = convert_with_check
4827 }
4829 /* Unchecked conversions as actuals for Out parameters are not
4830 allowed in user code because they are not variables, but do
4831 occur in front-end expansions. The associated GNU_NAME is
4832 always obtained from the inner expression in such cases. */
4835 gnu_result,
4837 else
4838 {
4840 gnu_result
4842 gnat_actual);
4847 }
4849 /* If an outer atomic access is required for an actual parameter,
4850 build the load-modify-store sequence. */
4852 gnu_result
4855 /* Or else, if simple atomic access is required, build the atomic
4856 store. */
4860 /* Otherwise build a regular assignment. */
4861 else
4870 }
4871 }
4873 /* If this is a function call, the result is the call expression unless a
4874 target is specified, in which case we copy the result into the target
4875 and return the assignment statement. */
4877 {
4878 /* If this is a function with copy-in/copy-out parameters, extract the
4879 return value from it and update the return type. */
4881 {
4883 gnu_call
4886 }
4888 /* If the function returns an unconstrained array or by direct reference,
4889 we have to dereference the pointer. */
4895 {
4899 /* If range check is needed, emit code to generate it. */
4901 gnu_call
4903 gnat_parent);
4905 /* ??? If the return type has variable size, then force the return
4906 slot optimization as we would not be able to create a temporary.
4907 That's what has been done historically. */
4910 else
4913 /* Use the required method to move the result to the target. */
4915 gnu_call
4919 else
4920 gnu_call
4926 }
4927 else
4929 }
4931 /* Otherwise, if this is a procedure call statement without copy-in/copy-out
4932 parameters, the result is just the call statement. */
4936 /* Finally, add the copy back statements, if any. */
4942 /* If we have pushed a binding level, pop it and finish up the enclosing
4943 statement group. */
4945 {
4949 }
4951 /* Otherwise, retrieve the statement list, if any. */
4955 /* Otherwise, just return the call expression. */
4956 else
4959 /* If we nevertheless need a value, make a COMPOUND_EXPR to return it.
4960 But first simplify if we have only one statement in the list. */
4962 {
4966 gnu_result
4968 }
4971 }
4972 \f
4973 /* Subroutine of gnat_to_gnu to translate gnat_node, an
4974 N_Handled_Sequence_Of_Statements, to a GCC tree, which is returned. */
4976 static tree
4978 {
4981 /* If just annotating, ignore all EH and cleanups. */
4985 bool fe_sjlj
4991 tree gnu_result;
4992 tree gnu_expr;
4993 Node_Id gnat_temp;
4995 /* The GCC exception handling mechanism can handle both ZCX and SJLJ schemes
4996 and we have our own SJLJ mechanism. To call the GCC mechanism, we call
4997 add_cleanup, and when we leave the binding, end_stmt_group will create
4998 the TRY_FINALLY_EXPR.
5000 ??? The region level calls down there have been specifically put in place
5001 for a ZCX context and currently the order in which things are emitted
5002 (region/handlers) is different from the SJLJ case. Instead of putting
5003 other calls with different conditions at other places for the SJLJ case,
5004 it seems cleaner to reorder things for the SJLJ case and generalize the
5005 condition to make it not ZCX specific.
5007 If there are any exceptions or cleanup processing involved, we need an
5008 outer statement group (for Fe_Sjlj) and binding level. */
5010 {
5013 }
5015 /* If using fe_sjlj, make the variables for the setjmp buffer and save
5016 area for address of previous buffer. Do this first since we need to have
5017 the setjmp buf known for any decls in this block. */
5019 {
5020 gnu_jmpsave_decl
5022 jmpbuf_ptr_type,
5027 /* The __builtin_setjmp receivers will immediately reinstall it. Now
5028 because of the unstructured form of EH used by fe_sjlj, there
5029 might be forward edges going to __builtin_setjmp receivers on which
5030 it is uninitialized, although they will never be actually taken. */
5032 gnu_jmpbuf_decl
5034 jmpbuf_type,
5035 NULL_TREE,
5041 /* When we exit this block, restore the saved value. */
5045 }
5047 /* If we are to call a function when exiting this block, add a cleanup
5048 to the binding level we made above. Note that add_cleanup is FIFO
5049 so we must register this cleanup after the EH cleanup just above. */
5051 {
5054 /* When not optimizing, disable inlining of finalizers as this can
5055 create a more complex CFG in the parent function. */
5059 /* If there is no end label attached, we use the location of the At_End
5060 procedure because Expand_Cleanup_Actions might reset the location of
5061 the enclosing construct to that of an inner statement. */
5065 }
5067 /* Now build the tree for the declarations and statements inside this block.
5068 If this is SJLJ, set our jmp_buf as the current buffer. */
5072 {
5075 gnu_jmpbuf_decl));
5078 }
5084 /* Generate code for each statement in the block. */
5092 /* Now generate code for the two exception models, if either is relevant for
5093 this block. */
5095 {
5097 tree gnu_handler;
5099 /* Make a binding level for the exception handling declarations and code
5100 and set up gnu_except_ptr_stack for the handlers to use. */
5111 /* Generate code for each handler. The N_Exception_Handler case does the
5112 real work and returns a COND_EXPR for each handler, which we chain
5113 together here. */
5116 {
5119 /* If this is the first one, set it as the outer one. Otherwise,
5120 point the "else" part of the previous handler to us. Then point
5121 to our "else" part. */
5124 else
5128 }
5130 /* If none of the exception handlers did anything, re-raise but do not
5131 defer abortion. */
5134 set_expr_location_from_node
5140 else
5143 /* End the binding level dedicated to the exception handlers and get the
5144 whole statement group. */
5149 /* If the setjmp returns 1, we restore our incoming longjmp value and
5150 then check the handlers. */
5153 gnu_jmpsave_decl),
5154 gnat_node);
5158 /* This block is now "if (setjmp) ... <handlers> else <block>". */
5160 (build_call_n_expr
5163 gnu_jmpbuf_decl))),
5165 }
5167 {
5168 tree gnu_handlers;
5169 location_t locus;
5171 /* First make a block containing the handlers. */
5179 /* Now make the TRY_CATCH_EXPR for the block. */
5182 /* Set a location. We need to find a unique location for the dispatching
5183 code, otherwise we can get coverage or debugging issues. Try with
5184 the location of the end label. */
5188 else
5189 /* Clear column information so that the exception handler of an
5190 implicit transient block does not incorrectly inherit the slocs
5191 of a decision, which would otherwise confuse control flow based
5192 coverage analysis tools. */
5194 }
5195 else
5198 /* Now close our outer block, if we had to make one. */
5200 {
5204 }
5207 }
5208 \f
5209 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
5210 to a GCC tree, which is returned. This is the variant for front-end sjlj
5211 exception handling. */
5213 static tree
5215 {
5216 /* Unless this is "Others" or the special "Non-Ada" exception for Ada, make
5217 an "if" statement to select the proper exceptions. For "Others", exclude
5218 exceptions where Handled_By_Others is nonzero unless the All_Others flag
5219 is set. For "Non-ada", accept an exception if "Lang" is 'V'. */
5222 Node_Id gnat_temp;
5226 {
5227 tree this_choice;
5230 {
5233 else
5234 this_choice
5235 = build_binary_op
5237 convert
5239 build_component_ref
5240 (build_unary_op
5243 not_handled_by_others_decl,
5245 integer_zero_node);
5246 }
5250 {
5252 tree gnu_expr;
5254 /* Exception may be a renaming. Recover original exception which is
5255 the one elaborated and registered. */
5261 this_choice
5262 = build_binary_op
5267 }
5268 else
5273 }
5276 }
5277 \f
5278 /* Return true if no statement in GNAT_LIST can alter the control flow. */
5280 static bool
5282 {
5286 /* This is very conservative, we reject everything except for simple
5287 assignments between identifiers or literals. */
5291 {
5303 }
5306 }
5308 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
5309 to a GCC tree, which is returned. This is the variant for GCC exception
5310 schemes. */
5312 static tree
5314 {
5317 /* We build a TREE_LIST of nodes representing what exception types this
5318 handler can catch, with special cases for others and all others cases.
5320 Each exception type is actually identified by a pointer to the exception
5321 id, or to a dummy object for "others" and "all others". */
5323 gnat_temp;
5325 {
5329 {
5332 }
5335 {
5338 /* Exception may be a renaming. Recover original exception which is
5339 the one elaborated and registered. */
5345 }
5346 else
5349 /* The GCC interface expects NULL to be passed for catch all handlers, so
5350 it would be quite tempting to set gnu_etypes_list to NULL if gnu_etype
5351 is integer_zero_node. It would not work, however, because GCC's
5352 notion of "catch all" is stronger than our notion of "others". Until
5353 we correctly use the cleanup interface as well, doing that would
5354 prevent the "all others" handlers from being seen, because nothing
5355 can be caught beyond a catch all from GCC's point of view. */
5357 }
5362 /* Expand a call to the begin_handler hook at the beginning of the handler,
5363 and arrange for a call to the end_handler hook to occur on every possible
5364 exit path.
5366 The hooks expect a pointer to the low level occurrence. This is required
5367 for our stack management scheme because a raise inside the handler pushes
5368 a new occurrence on top of the stack, which means that this top does not
5369 necessarily match the occurrence this handler was dealing with.
5371 __builtin_eh_pointer references the exception occurrence being
5372 propagated. Upon handler entry, this is the exception for which the
5373 handler is triggered. This might not be the case upon handler exit,
5374 however, as we might have a new occurrence propagated by the handler's
5375 body, and the end_handler hook called as a cleanup in this context.
5377 We use a local variable to retrieve the incoming value at handler entry
5378 time, and reuse it to feed the end_handler hook's argument at exit. */
5380 tree gnu_current_exc_ptr
5384 gnu_incoming_exc_ptr
5391 gnu_incoming_exc_ptr),
5392 gnat_node);
5394 /* Declare and initialize the choice parameter, if present. */
5396 {
5397 tree gnu_param
5403 gnu_incoming_exc_ptr));
5404 }
5408 /* We don't have an End_Label at hand to set the location of the cleanup
5409 actions, so we use that of the exception handler itself instead. */
5413 else
5420 return
5422 }
5423 \f
5424 /* Subroutine of gnat_to_gnu to generate code for an N_Compilation unit. */
5426 static void
5428 {
5433 Entity_Id gnat_entity;
5434 Node_Id gnat_pragma;
5435 /* Make the decl for the elaboration procedure. Emit debug info for it, so
5436 that users can break into their elaboration code in debuggers. Kludge:
5437 don't consider it as a definition so that we have a line map for its body,
5438 but no subprogram description in debug info. */
5439 tree gnu_elab_proc_decl
5440 = create_subprog_decl
5449 /* Initialize the information structure for the function. */
5458 /* For a body, first process the spec if there is one. */
5464 {
5471 }
5473 /* Then process any pragmas and declarations preceding the unit. */
5482 /* Process the unit itself. */
5485 /* Generate code for all the inlined subprograms. */
5489 {
5490 Node_Id gnat_body;
5492 /* Without optimization, process only the required subprograms. */
5496 /* The set of inlined subprograms is computed from data recorded early
5497 during expansion and it can be a strict superset of the final set
5498 computed after semantic analysis, for example if a call to such a
5499 subprogram occurs in a pragma Assert and assertions are disabled.
5500 In that case, semantic analysis resets Is_Public to false but the
5501 entry for the subprogram in the inlining tables is stalled. */
5507 {
5508 /* ??? This happens when only the spec of a package is provided. */
5512 gnat_body
5514 }
5516 /* Define the entity first so we set DECL_EXTERNAL. */
5519 }
5521 /* Process any pragmas and actions following the unit. */
5526 /* Save away what we've made so far and finish it up. */
5533 /* Record this potential elaboration procedure for later processing. */
5540 /* Force the processing for all nodes that remain in the queue. */
5542 }
5543 \f
5544 /* Mark COND, a boolean expression, as predicating a call to a noreturn
5545 function, i.e. predict that it is very likely false, and return it.
5547 The compiler will automatically predict the last edge leading to a call
5548 to a noreturn function as very unlikely taken. This function makes it
5549 possible to expand the prediction to predecessors in case the condition
5550 is made up of several short-circuit operators. */
5552 static tree
5554 {
5564 PRED_NORETURN));
5567 }
5569 /* Subroutine of gnat_to_gnu to translate GNAT_RANGE, a node representing a
5570 range of values, into GNU_LOW and GNU_HIGH bounds. */
5572 static void
5574 {
5575 /* GNAT_RANGE is either an N_Range or an identifier denoting a subtype. */
5577 {
5585 {
5589 *gnu_low
5591 *gnu_high
5593 }
5598 }
5599 }
5601 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Raise_xxx_Error,
5602 to a GCC tree and return it. GNU_RESULT_TYPE_P is a pointer to where
5603 we should place the result type. */
5605 static tree
5607 {
5611 const bool with_extra_info
5612 = Exception_Extra_Info
5617 /* The following processing is not required for correctness. Its purpose is
5618 to give more precise error messages and to record some information. */
5620 {
5630 {
5637 {
5655 }
5663 {
5669 }
5672 && gnu_low_bound
5673 && gnu_high_bound
5676 gnu_result
5680 /* If optimization is enabled and we are inside a loop, we try to
5681 compute invariant conditions for checks applied to the iteration
5682 variable, i.e. conditions that are independent of the variable
5683 and necessary in order for the checks to fail in the course of
5684 some iteration. If we succeed, we consider an alternative:
5686 1. If loop unswitching is enabled, we prepend these conditions
5687 to the original conditions of the checks. This will make it
5688 possible for the loop unswitching pass to replace the loop
5689 with two loops, one of which has the checks eliminated and
5690 the other has the original checks reinstated, and a prologue
5691 implementing a run-time selection. The former loop will be
5692 for example suitable for vectorization.
5694 2. Otherwise, we instead append the conditions to the original
5695 conditions of the checks. At worse, if the conditions cannot
5696 be evaluated at compile time, they will be evaluated as true
5697 at run time only when the checks have already failed, thus
5698 contributing negatively only to the size of the executable.
5699 But the hope is that these invariant conditions be evaluated
5700 at compile time to false, thus taking away the entire checks
5701 with them. */
5704 && (!gnu_low_bound
5706 && (!gnu_high_bound
5709 {
5716 rci->inserted_cond
5723 boolean_type_node,
5725 gnu_cond);
5726 else
5728 boolean_type_node,
5729 gnu_cond,
5731 }
5733 /* Or else, if aggressive loop optimizations are enabled, we just
5734 record that there are checks applied to iteration variables. */
5736 && flag_aggressive_loop_optimizations
5740 }
5745 }
5747 /* The following processing does the common work. */
5748 common:
5755 /* If the type is VOID, this is a statement, so we need to generate the code
5756 for the call. Handle a condition, if there is one. */
5758 {
5760 {
5765 }
5766 }
5767 else
5771 }
5772 \f
5773 /* Return true if GNAT_NODE is on the LHS of an assignment or an actual
5774 parameter of a call. */
5776 static bool
5778 {
5793 }
5795 /* Return true if either GNAT_NODE or a view of GNAT_NODE is on the LHS
5796 of an assignment or an actual parameter of a call. */
5798 static bool
5800 {
5801 Node_Kind kind;
5813 }
5815 /* Return true if GNAT_NODE, an unchecked type conversion, is a no-op as far
5816 as gigi is concerned. This is used to avoid conversions on the LHS. */
5818 static bool
5820 {
5823 /* The conversion must be on the LHS of an assignment or an actual parameter
5824 of a call. Otherwise, even if the conversion was essentially a no-op, it
5825 could de facto ensure type consistency and this should be preserved. */
5831 /* We're interested in artificial conversions generated by the front-end
5832 to make private types explicit, e.g. in Expand_Assign_Array. */
5839 /* The direct conversion to the underlying type is a no-op. */
5843 /* For an array subtype, the conversion to the PAIT is a no-op. */
5848 /* For a record subtype, the conversion to the type is a no-op. */
5854 }
5856 /* Return true if GNAT_NODE represents a statement. */
5858 static bool
5860 {
5876 }
5878 /* This function is the driver of the GNAT to GCC tree transformation process.
5879 It is the entry point of the tree transformer. GNAT_NODE is the root of
5880 some GNAT tree. Return the root of the corresponding GCC tree. If this
5881 is an expression, return the GCC equivalent of the expression. If this
5882 is a statement, return the statement or add it to the current statement
5883 group, in which case anything returned is to be interpreted as occurring
5884 after anything added. */
5886 tree
5888 {
5894 Node_Id gnat_temp;
5897 /* Save node number for error message and set location information. */
5901 /* If we are only annotating types and this node is a statement, return
5902 an empty statement list. */
5906 /* If we are only annotating types and this node is a subexpression, return
5907 a NULL_EXPR, but filter out nodes appearing in the expressions attached
5908 to packed array implementation types. */
5923 N_Raise_Constraint_Error));
5928 {
5931 /* If this is a statement and we are at top level, it must be part of
5932 the elaboration procedure, so mark us as being in that procedure. */
5934 {
5937 }
5939 /* If we are in the elaboration procedure, check if we are violating a
5940 No_Elaboration_Code restriction by having a statement there. Don't
5941 check for a possible No_Elaboration_Code restriction violation on
5942 N_Handled_Sequence_Of_Statements, as we want to signal an error on
5943 every nested real statement instead. This also avoids triggering
5944 spurious errors on dummy (empty) sequences created by the front-end
5945 for package bodies in some cases. */
5950 }
5953 {
5954 /********************************/
5955 /* Chapter 2: Lexical Elements */
5956 /********************************/
5965 /* If atomic access is required on the RHS, build the atomic load. */
5972 {
5973 tree gnu_type;
5975 /* Get the type of the result, looking inside any padding and
5976 justified modular types. Then get the value in that type. */
5985 /* If the result overflows (meaning it doesn't fit in its base type),
5986 abort. We would like to check that the value is within the range
5987 of the subtype, but that causes problems with subtypes whose usage
5988 will raise Constraint_Error and with biased representation, so
5989 we don't. */
5991 }
5995 /* If a Entity is present, it means that this was one of the
5996 literals in a user-defined character type. In that case,
5997 just return the value in the CONST_DECL. Otherwise, use the
5998 character code. In that case, the base type should be an
5999 INTEGER_TYPE, but we won't bother checking for that. */
6003 else
6004 gnu_result
6012 /* If this is of a fixed-point type, the value we want is the value of
6013 the corresponding integer. */
6015 {
6017 gnu_result_type);
6019 }
6021 else
6022 {
6025 /* First convert the value to a machine number if it isn't already.
6026 That will force the base to 2 for non-zero values and simplify
6027 the rest of the logic. */
6029 ur_realval
6035 else
6036 {
6037 REAL_VALUE_TYPE tmp;
6041 /* The base must be 2 as Machine guarantees this, so we scale
6042 the value, which we know can fit in the mantissa of the type
6043 (hence the use of that type above). */
6048 }
6050 /* Now see if we need to negate the result. Do it this way to
6051 properly handle -0. */
6053 gnu_result
6055 gnu_result);
6056 }
6063 {
6070 else
6073 /* Build the string with the characters in the literal. Note
6074 that Ada strings are 1-origin. */
6078 /* Put a null at the end of the string in case it's in a context
6079 where GCC will want to treat it as a C string. */
6084 /* Strings in GCC don't normally have types, but we want
6085 this to not be converted to the array type. */
6090 }
6091 else
6092 {
6093 /* Build a list consisting of each character, then make
6094 the aggregate. */
6104 {
6110 }
6113 }
6120 /**************************************/
6121 /* Chapter 3: Declarations and Types */
6122 /**************************************/
6139 /* If we are just annotating types and this object has an unconstrained
6140 or task type, don't elaborate it. */
6150 && (!type_annotate_only
6152 {
6155 gnu_expr
6160 }
6161 else
6164 /* If this is a deferred constant with an address clause, we ignore the
6165 full view since the clause is on the partial view and we cannot have
6166 2 different GCC trees for the object. The only bits of the full view
6167 we will use is the initializer, but it will be directly fetched. */
6173 /* If this object has its elaboration delayed, we must force evaluation
6174 of GNU_EXPR now and save it for the freeze point. Note that we need
6175 not do anything special at the global level since the lifetime of the
6176 temporary is fully contained within the elaboration routine. */
6178 {
6180 {
6183 }
6184 }
6185 else
6193 /* Don't do anything if this renaming is handled by the front end and it
6194 does not need debug info. Note that we consider renamings don't need
6195 debug info when optimizing: our way to describe them has a
6196 memory/elaboration footprint.
6198 Don't do anything neither if we are just annotating types and this
6199 object has a composite or task type, don't elaborate it. */
6202 && !optimize
6203 && can_materialize_object_renaming_p
6205 && ! (type_annotate_only
6209 {
6210 tree gnu_temp
6214 /* See case 2 of renaming in gnat_to_gnu_entity. */
6217 }
6224 /* See the above case for the rationale. */
6226 {
6227 tree gnu_temp
6233 }
6237 {
6243 /* Materializing renamed subprograms will only benefit the debugging
6244 information as they aren't referenced in the generated code. So
6245 skip them when they aren't needed. Avoid doing this if:
6247 - there is a freeze node: in this case the renamed entity is not
6248 elaborated yet,
6249 - the renamed subprogram is intrinsic: it will not be available in
6250 the debugging information (note that both or only one of the
6251 renaming and the renamed subprograms can be intrinsic). */
6262 }
6271 /* These are fully handled in the front end. */
6272 /* ??? For package renamings, find a way to use GENERIC namespaces so
6273 that we get proper debug information for them. */
6277 /*************************************/
6278 /* Chapter 4: Names and Expressions */
6279 /*************************************/
6282 /* Make sure the designated type is complete before dereferencing. */
6287 /* If atomic access is required on the RHS, build the atomic load. */
6294 {
6295 tree gnu_array_object
6297 tree gnu_type;
6304 /* Convert vector inputs to their representative array type, to fit
6305 what the code below expects. */
6307 {
6311 }
6315 /* If we got a padded type, remove it too. */
6317 gnu_array_object
6319 gnu_array_object);
6321 /* The failure of this assertion will very likely come from a missing
6322 expansion for a packed array access. */
6325 /* First compute the number of dimensions of the array, then
6326 fill the expression array, the order depending on whether
6327 this is a Convention_Fortran array or not. */
6332 ;
6341 else
6347 /* Start with the prefix and build the successive references. */
6353 {
6359 gnu_result
6362 /* Array accesses are bound-checked so they cannot trap, but this
6363 is valid only if they are not hoisted ahead of the check. We
6364 need to mark them as no-trap to get decent loop optimizations
6365 in the presence of -fnon-call-exceptions, so we do it when we
6366 know that the original expression had no side-effects. */
6372 /* If aggressive loop optimizations are enabled, we warn for loops
6373 overrunning a simple array of size 1 not at the end of a record.
6374 This is aimed to catch misuses of the trailing array idiom. */
6376 && flag_aggressive_loop_optimizations
6392 {
6395 }
6396 }
6400 /* If atomic access is required on the RHS, build the atomic load. */
6404 }
6408 {
6409 tree gnu_array_object
6420 /* If this is a slice with non-constant size of an array with constant
6421 size, set the maximum size for the allocation of temporaries. */
6429 }
6433 {
6434 Entity_Id gnat_prefix
6441 /* gnat_to_gnu_entity does not save the GNU tree made for renamed
6442 discriminants so avoid making recursive calls on each reference
6443 to them by following the appropriate link directly here. */
6445 {
6446 /* For discriminant references in tagged types always substitute
6447 the corresponding discriminant as the actual component. */
6452 /* For discriminant references in untagged types always substitute
6453 the corresponding stored discriminant. */
6456 }
6458 /* Handle extracting the real or imaginary part of a complex.
6459 The real part is the first field and the imaginary the last. */
6464 else
6465 {
6468 gnu_result
6472 && lvalue_required_for_attribute_p
6474 }
6478 /* If atomic access is required on the RHS, build the atomic load. */
6482 }
6486 {
6487 /* The attribute designator. */
6490 /* The Elab_Spec and Elab_Body attributes are special in that Prefix
6491 is a unit, not an object with a GCC equivalent. */
6493 return
6499 gnat_node);
6502 }
6506 /* Like 'Access as far as we are concerned. */
6514 {
6515 tree gnu_aggr_type;
6517 /* ??? It is wrong to evaluate the type now, but there doesn't
6518 seem to be any other practical way of doing it. */
6522 gnu_aggr_type = gnu_result_type
6527 gnu_aggr_type
6537 gnu_result
6540 gnu_aggr_type);
6543 gnu_aggr_type,
6546 gnu_result
6547 = build_binary_op
6552 (Next
6554 else
6558 }
6566 else
6576 /* If this is a qualified expression for a tagged type, we mark the type
6577 as used. Because of polymorphism, this might be the only reference to
6578 the tagged type in the program while objects have it as dynamic type.
6579 The debugger needs to see it to display these objects properly. */
6583 gnu_result
6587 kind == N_Type_Conversion
6595 /* Skip further processing if the conversion is deemed a no-op. */
6597 {
6601 }
6603 /* If the result is a pointer type, see if we are improperly
6604 converting to a stricter alignment. */
6607 {
6613 post_error_ne_tree_2
6617 }
6619 /* If we are converting a descriptor to a function pointer, first
6620 build the pointer. */
6632 {
6641 {
6645 }
6647 /* If LOW and HIGH are identical, perform an equality test. Otherwise,
6648 ensure that GNU_OBJ is evaluated only once and perform a full range
6649 test. */
6651 gnu_result
6653 else
6654 {
6663 gnu_result
6665 }
6668 gnu_result
6670 }
6678 ? RDIV_EXPR
6687 /* These can either be operations on booleans or on modular types.
6688 Fall through for boolean types since that's the way GNU_CODES is
6689 set up. */
6691 {
6692 enum tree_code code
6703 }
6705 /* ... fall through ... */
6725 {
6729 tree gnu_type;
6735 /* Pending generic support for efficient vector logical operations in
6736 GCC, convert vectors to their representative array type view and
6737 fallthrough. */
6741 /* If this is a comparison operator, convert any references to an
6742 unconstrained array value into a reference to the actual array. */
6744 {
6750 {
6753 }
6754 }
6756 /* If this is a shift whose count is not guaranteed to be correct,
6757 we need to adjust the shift count. */
6759 {
6761 tree gnu_max_shift
6768 gnu_rhs
6769 = build_binary_op
6772 gnu_count_type,
6773 gnu_max_shift,
6775 gnu_rhs);
6776 }
6778 /* For right shifts, the type says what kind of shift to do,
6779 so we may need to choose a different type. In this case,
6780 we have to ignore integer overflow lest it propagates all
6781 the way down and causes a CE to be explicitly raised. */
6783 {
6786 }
6789 {
6792 }
6795 {
6801 }
6803 /* Instead of expanding overflow checks for addition, subtraction
6804 and multiplication itself, the front end will leave this to
6805 the back end when Backend_Overflow_Checks_On_Target is set. */
6807 && Backend_Overflow_Checks_On_Target
6813 else
6814 {
6815 /* Some operations, e.g. comparisons of arrays, generate complex
6816 trees that need to be annotated while they are being built. */
6819 }
6821 /* If this is a logical shift with the shift count not verified,
6822 we must return zero if it is too large. We cannot compensate
6823 above in this case. */
6826 gnu_result
6827 = build_cond_expr
6830 gnu_rhs,
6834 gnu_result);
6835 }
6839 {
6842 tree gnu_false
6846 gnu_result
6848 }
6857 /* This case can apply to a boolean or a modular type.
6858 Fall through for a boolean operand since GNU_CODES is set
6859 up to handle this. */
6861 {
6865 gnu_expr);
6867 }
6869 /* ... fall through ... */
6876 /* Instead of expanding overflow checks for negation and absolute
6877 value itself, the front end will leave this to the back end
6878 when Backend_Overflow_Checks_On_Target is set. */
6880 && Backend_Overflow_Checks_On_Target
6883 gnu_result
6886 else
6892 {
6894 tree gnu_type;
6899 /* The Expression operand can either be an N_Identifier or
6900 Expanded_Name, which must represent a type, or a
6901 N_Qualified_Expression, which contains both the object type and an
6902 initial value for the object. */
6907 {
6908 Entity_Id gnat_desig_type
6916 gnu_init
6922 else
6923 {
6927 }
6929 /* See the N_Qualified_Expression case for the rationale. */
6934 }
6935 else
6942 ignore_init_type);
6943 }
6946 /**************************/
6947 /* Chapter 5: Statements */
6948 /**************************/
6956 /* When not optimizing, turn null statements from source into gotos to
6957 the next statement that the middle-end knows how to preserve. */
6959 {
6970 }
6971 else
6976 /* Get the LHS and RHS of the statement and convert any reference to an
6977 unconstrained array into a reference to the underlying array. */
6980 /* If the type has a size that overflows, convert this into raise of
6981 Storage_Error: execution shouldn't have gotten here anyway. */
6985 N_Raise_Storage_Error);
6987 {
6988 bool outer_atomic_access
6990 bool atomic_access
6991 = !outer_atomic_access
6993 gnu_result
6996 }
6997 else
6998 {
7000 const Entity_Id gnat_type
7002 const bool regular_array_type_p
7004 const bool use_memset_p
7005 = (regular_array_type_p
7009 /* If we'll use memset, we need to find the inner expression. */
7011 {
7012 Node_Id gnat_inner
7016 gnat_inner
7019 }
7020 else
7023 /* If range check is needed, emit code to generate it. */
7026 gnat_node);
7028 /* If an outer atomic access is required on the LHS, build the load-
7029 modify-store sequence. */
7033 /* Or else, if atomic access is required, build the atomic store. */
7037 /* Or else, use memset when the conditions are met. */
7039 {
7043 tree size
7048 {
7049 tree mask
7053 }
7055 }
7057 /* Otherwise build a regular assignment. */
7058 else
7059 gnu_result
7062 /* If the assignment type is a regular array and the two sides are
7063 not completely disjoint, play safe and use memmove. But don't do
7064 it for a bit-packed array as it might not be byte-aligned. */
7066 && regular_array_type_p
7068 {
7072 tree size
7078 }
7079 }
7083 {
7086 /* Make the outer COND_EXPR. Avoid non-determinism. */
7095 /* Now make a COND_EXPR for each of the "else if" parts. Put each
7096 into the previous "else" part and point to where to put any
7097 outer "else". Also avoid non-determinism. */
7101 {
7111 }
7114 }
7126 /* The only way to enter the block is to fall through to it. */
7128 {
7135 }
7136 else
7141 gnu_result
7151 {
7154 /* If the subprogram is a function, we must return the expression. */
7156 {
7159 /* If this function has copy-in/copy-out parameters parameters and
7160 doesn't return by invisible reference, get the real object for
7161 the return. See Subprogram_Body_to_gnu. */
7165 else
7168 /* Get the GCC tree for the expression to be returned. */
7171 /* Do not remove the padding from GNU_RET_VAL if the inner type is
7172 self-referential since we want to allocate the fixed size. */
7174 && type_is_padding_self_referential
7178 /* If the function returns by direct reference, return a pointer
7179 to the return value. */
7184 /* Otherwise, if it returns an unconstrained array, we have to
7185 allocate a new version of the result and return it. */
7187 {
7190 /* And find out whether this is a candidate for Named Return
7191 Value. If so, record it. */
7193 {
7196 /* Strip useless conversions around the return value. */
7200 /* Strip unpadding around the return value. */
7202 && TYPE_IS_PADDING_P
7206 /* Now apply the test to the return value. */
7208 {
7214 }
7215 }
7218 gnu_ret_val,
7223 }
7225 /* Otherwise, if it returns by invisible reference, dereference
7226 the pointer it is passed using the type of the return value
7227 and build the copy operation manually. This ensures that we
7228 don't copy too much data, for example if the return type is
7229 unconstrained with a maximum size. */
7231 {
7232 tree gnu_ret_deref
7234 gnu_ret_obj);
7239 }
7240 }
7242 else
7245 /* If we have a return label defined, convert this into a branch to
7246 that label. The return proper will be handled elsewhere. */
7248 {
7251 gnu_ret_val));
7256 /* When not optimizing, make sure the return is preserved. */
7259 }
7261 /* Otherwise, build a regular return. */
7262 else
7264 }
7268 gnu_result
7272 /***************************/
7273 /* Chapter 6: Subprograms */
7274 /***************************/
7277 /* Unless there is a freeze node, declare the entity. We consider
7278 this a definition even though we're not generating code for the
7279 subprogram because we will be making the corresponding GCC node.
7280 When there is a freeze node, it is considered the definition of
7281 the subprogram and we do nothing until after it is encountered.
7282 That's an efficiency issue: the types involved in the profile
7283 are far more likely to be frozen between the declaration and
7284 the freeze node than before the declaration, so we save some
7285 updates of the GCC node by waiting until the freeze node.
7286 The counterpart is that we assume that there is no reference
7287 to the subprogram between the declaration and the freeze node
7288 in the expanded code; otherwise, it will be interpreted as an
7289 external reference and very likely give rise to a link failure. */
7297 /* This subprogram doesn't exist for code generation purposes, but we
7298 have to elaborate the types of any parameters and result, unless
7299 they are imported types (nothing to generate in this case).
7301 The parameter list may contain types with freeze nodes, e.g. not null
7302 subtypes, so the subprogram itself may carry a freeze node, in which
7303 case its elaboration must be deferred. */
7305 /* Process the parameter types first. */
7308 = First_Formal_With_Extras
7316 /* Then the result type, set to Standard_Void_Type for procedures. */
7317 {
7318 Entity_Id gnat_temp_type
7323 }
7329 /* For a child unit identifier go up a level to get the specification.
7330 We get this when we try to find the spec of a child unit package
7331 that is the compilation unit being compiled. */
7346 /************************/
7347 /* Chapter 7: Packages */
7348 /************************/
7364 /* If this is the body of a generic package - do nothing. */
7366 {
7369 }
7380 /********************************/
7381 /* Chapter 8: Visibility Rules */
7382 /********************************/
7386 /* Nothing to do here - but these may appear in list of declarations. */
7390 /*********************/
7391 /* Chapter 9: Tasks */
7392 /*********************/
7403 /*********************************************************/
7404 /* Chapter 10: Program Structure and Compilation Issues */
7405 /*********************************************************/
7408 /* This is not called for the main unit on which gigi is invoked. */
7420 /* These nodes should only be present when annotating types. */
7430 /* Simply process whatever unit is being inserted. */
7433 else
7434 {
7437 }
7440 /***************************/
7441 /* Chapter 11: Exceptions */
7442 /***************************/
7445 /* If there is an At_End procedure attached to this node, and the EH
7446 mechanism is front-end, we must have at least a corresponding At_End
7447 handler, unless the No_Exception_Handlers restriction is set. */
7462 else
7467 /* Only for reraise in back-end exceptions mode. */
7474 /* Clear the current exception pointer so that the occurrence won't be
7475 deallocated. */
7515 /******************************/
7516 /* Chapter 12: Generic Units */
7517 /******************************/
7527 /* These nodes can appear on a declaration list but there is nothing to
7528 to be done with them. */
7532 /**************************************************/
7533 /* Chapter 13: Representation Clauses and */
7534 /* Implementation-Dependent Features */
7535 /**************************************************/
7540 /* The only one we need to deal with is 'Address since, for the others,
7541 the front-end puts the information elsewhere. */
7545 /* And we only deal with 'Address if the object has a Freeze node. */
7550 /* Get the value to use as the address and save it as the equivalent
7551 for the object. When it is frozen, gnat_to_gnu_entity will do the
7552 right thing. */
7559 /* We do nothing with these. SEM puts the information elsewhere. */
7565 {
7575 /* First retrieve the 3 operand lists built by the front-end. */
7578 {
7585 }
7589 {
7596 }
7600 gnu_clobbers
7603 gnu_clobbers);
7605 /* Then perform some standard checking and processing on the
7606 operands. In particular, mark them addressable if needed. */
7614 {
7616 constraint
7622 {
7623 /* If the operand is going to end up in memory,
7624 mark it addressable. Note that we don't test
7625 allows_mem like in the input case below; this
7626 is modelled on the C front-end. */
7628 {
7635 }
7636 }
7637 else
7641 }
7644 {
7646 constraint
7652 {
7653 /* If the operand is going to end up in memory,
7654 mark it addressable. */
7656 {
7663 }
7664 }
7665 else
7669 }
7675 }
7676 else
7681 /****************/
7682 /* Added Nodes */
7683 /****************/
7686 /* This construct doesn't define a scope so we don't push a binding
7687 level around the statement list, but we wrap it in a SAVE_EXPR to
7688 protect it from unsharing. Elaborate the expression as part of the
7689 same statement group as the actions so that the type declaration
7690 gets inserted there as well. This ensures that the type elaboration
7691 code is issued past the actions computing values on which it might
7692 depend. */
7701 gnu_result
7725 {
7726 tree gnu_ptr
7731 /* If this is a thin pointer, we must first dereference it to create
7732 a fat pointer, then go back below to a thin pointer. The reason
7733 for this is that we need to have a fat pointer someplace in order
7734 to properly compute the size. */
7738 gnu_ptr));
7740 /* If this is a fat pointer, the object must have been allocated with
7741 the template in front of the array. So pass the template address,
7742 and get the total size; do it by converting to a thin pointer. */
7744 gnu_ptr
7746 (TYPE_OBJECT_RECORD_TYPE
7748 gnu_ptr);
7752 /* If this is a thin pointer, the object must have been allocated with
7753 the template in front of the array. So pass the template address,
7754 and get the total size. */
7756 gnu_ptr
7758 gnu_ptr,
7760 byte_position
7761 (DECL_CHAIN
7764 /* If we have a special dynamic constrained subtype on the node, use
7765 it to compute the size; otherwise, use the designated subtype. */
7767 {
7768 gnu_actual_obj_type
7772 gnu_actual_obj_type
7774 gnu_actual_obj_type,
7777 }
7778 else
7784 gnu_result
7788 gnat_node);
7789 }
7797 else
7802 /* The only validation we currently do on an unchecked conversion is
7803 that of aliasing assumptions. */
7813 /* These nodes should only be present when annotating types. */
7819 /* Other nodes are not supposed to reach here. */
7821 }
7823 /* If we pushed the processing of the elaboration routine, pop it back. */
7827 /* When not optimizing, turn boolean rvalues B into B != false tests
7828 so that we can put the location information of the reference to B on
7829 the inequality operator for better debug info. */
7840 {
7841 gnu_result
7847 }
7849 /* Set the location information on the result if it's not a simple name.
7850 Note that we may have no result if we tried to build a CALL_EXPR node
7851 to a procedure with no side-effects and optimization is enabled. */
7855 /* If we're supposed to return something of void_type, it means we have
7856 something we're elaborating for effect, so just return. */
7860 /* If the result is a constant that overflowed, raise Constraint_Error. */
7862 {
7864 gnu_result
7867 N_Raise_Constraint_Error));
7868 }
7870 /* If the result has side-effects and is of an unconstrained type, protect
7871 the expression in case it will be referenced multiple times, i.e. for
7872 its value and to compute the size of an object. But do it neither for
7873 an object nor a renaming declaration, nor a return statement of a call
7874 to a function that returns an unconstrained record type with default
7875 discriminant, because there is no size to be computed in these cases
7876 and this will create a useless temporary. We must do this before any
7877 conversions. */
7888 /* Now convert the result to the result type, unless we are in one of the
7889 following cases:
7891 1. If this is the LHS of an assignment or an actual parameter of a
7892 call, return the result almost unmodified since the RHS will have
7893 to be converted to our type in that case, unless the result type
7894 has a simpler size. Likewise if there is just a no-op unchecked
7895 conversion in-between. Similarly, don't convert integral types
7896 that are the operands of an unchecked conversion since we need
7897 to ignore those conversions (for 'Valid).
7899 2. If we have a label (which doesn't have any well-defined type), a
7900 field or an error, return the result almost unmodified. Similarly,
7901 if the two types are record types with the same name, don't convert.
7902 This will be the case when we are converting from a packable version
7903 of a type to its original type and we need those conversions to be
7904 NOPs in order for assignments into these types to work properly.
7906 3. If the type is void or if we have no result, return error_mark_node
7907 to show we have no result.
7909 4. If this is a call to a function that returns with variable size and
7910 the call is used as the expression in either an object or a renaming
7911 declaration, return the result unmodified because we want to use the
7912 return slot optimization in this case.
7914 5. Finally, if the type of the result is already correct. */
7932 && (CONTAINS_PLACEHOLDER_P
7936 {
7937 /* Remove padding only if the inner object is of self-referential
7938 size: in that case it must be an object of unconstrained type
7939 with a default discriminant and we want to avoid copying too
7940 much data. */
7943 gnu_result);
7944 }
7953 {
7954 /* Remove any padding. */
7957 gnu_result);
7958 }
7968 ;
7973 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on the result. */
7980 }
7982 /* Similar to gnat_to_gnu, but discard any object that might be created in
7983 the course of the translation of GNAT_NODE, which must be an "external"
7984 expression in the sense that it will be elaborated elsewhere. */
7986 tree
7988 {
7992 /* Force the local context and create a fake scope that we zap
7993 at the end so declarations will not be stuck either in the
7994 global varpool or in the current scope. */
7996 {
7999 }
8010 /* Do not import locations from external units. */
8015 }
8016 \f
8017 /* Subroutine of above to push the exception label stack. GNU_STACK is
8018 a pointer to the stack to update and GNAT_LABEL, if present, is the
8019 label to push onto the stack. */
8021 static void
8023 {
8029 }
8030 \f
8031 /* Return true if the statement list STMT_LIST is empty. */
8033 static bool
8035 {
8036 tree_stmt_iterator tsi;
8039 {
8042 /* Anything else than an empty STMT_STMT counts as something. */
8045 }
8048 }
8050 /* Record the current code position in GNAT_NODE. */
8052 static void
8054 {
8059 }
8061 /* Insert the code for GNAT_NODE at the position saved for that node. */
8063 static void
8065 {
8068 /* It's too late to remove the STMT_STMT itself at this point. */
8073 }
8074 \f
8075 /* Start a new statement group chained to the previous group. */
8077 void
8079 {
8082 /* First see if we can get one from the free list. */
8085 else
8091 }
8093 /* Add GNU_STMT to the current statement group. If it is an expression with
8094 no effects, it is ignored. */
8096 void
8098 {
8100 }
8102 /* Similar, but the statement is always added, regardless of side-effects. */
8104 void
8106 {
8108 }
8110 /* Like add_stmt, but set the location of GNU_STMT to that of GNAT_NODE. */
8112 void
8114 {
8115 /* Do not emit a location for renamings that come from generic instantiation,
8116 they are likely to disturb debugging. */
8120 }
8122 /* Similar, but the statement is always added, regardless of side-effects. */
8124 void
8126 {
8130 }
8132 /* Add a declaration statement for GNU_DECL to the current statement group.
8133 Get SLOC from Entity_Id. */
8135 void
8137 {
8141 /* If this is a variable that Gigi is to ignore, we may have been given
8142 an ERROR_MARK. So test for it. We also might have been given a
8143 reference for a renaming. So only do something for a decl. Also
8144 ignore a TYPE_DECL for an UNCONSTRAINED_ARRAY_TYPE. */
8152 /* If we are external or global, we don't want to output the DECL_EXPR for
8153 this DECL node since we already have evaluated the expressions in the
8154 sizes and positions as globals and doing it again would be wrong. */
8156 {
8157 /* Mark everything as used to prevent node sharing with subprograms.
8158 Note that walk_tree knows how to deal with TYPE_DECL, but neither
8159 VAR_DECL nor CONST_DECL. This appears to be somewhat arbitrary. */
8163 {
8167 }
8168 /* In any case, we have to deal with our own TYPE_ADA_SIZE field. */
8173 }
8174 else
8177 /* If this is a variable and an initializer is attached to it, it must be
8178 valid for the context. Similar to init_const in create_var_decl. */
8185 {
8188 {
8191 }
8193 /* If GNU_DECL has a padded type, convert it to the unpadded
8194 type so the assignment is done properly. */
8200 }
8201 }
8203 /* Callback for walk_tree to mark the visited trees rooted at *TP. */
8205 static tree
8207 {
8213 /* Don't mark a dummy type as visited because we want to mark its sizes
8214 and fields once it's filled in. */
8222 }
8224 /* Mark nodes rooted at T with TREE_VISITED and types as having their
8225 sized gimplified. We use this to indicate all variable sizes and
8226 positions in global types may not be shared by any subprogram. */
8228 void
8230 {
8232 }
8234 /* Add GNU_CLEANUP, a cleanup action, to the current code group and
8235 set its location to that of GNAT_NODE if present, but with column info
8236 cleared so that conditional branches generated as part of the cleanup
8237 code do not interfere with coverage analysis tools. */
8239 static void
8241 {
8245 }
8247 /* Set the BLOCK node corresponding to the current code group to GNU_BLOCK. */
8249 void
8251 {
8254 }
8256 /* Return code corresponding to the current code group. It is normally
8257 a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
8258 BLOCK or cleanups were set. */
8260 tree
8262 {
8266 /* If this is a null list, allocate a new STATEMENT_LIST. Then, if there
8267 are cleanups, make a TRY_FINALLY_EXPR. Last, if there is a BLOCK,
8268 make a BIND_EXPR. Note that we nest in that because the cleanup may
8269 reference variables in the block. */
8281 /* Remove this group from the stack and add it to the free list. */
8287 }
8289 /* Return whether the current statement group may fall through. */
8293 {
8296 else
8298 }
8300 /* Add a list of statements from GNAT_LIST, a possibly-empty list of
8301 statements.*/
8303 static void
8305 {
8306 Node_Id gnat_node;
8312 }
8314 /* Build a tree from GNAT_LIST, a possibly-empty list of statements.
8315 If BINDING_P is true, push and pop a binding level around the list. */
8317 static tree
8319 {
8331 }
8332 \f
8333 /* Generate GIMPLE in place for the expression at *EXPR_P. */
8335 int
8338 {
8341 tree op;
8347 {
8349 /* If this is an aggregate type, build a null pointer of the appropriate
8350 type and dereference it. */
8355 integer_zero_node));
8356 /* Otherwise, just make a VAR_DECL. */
8357 else
8358 {
8361 }
8367 /* We should only do this if we are just elaborating for side-effects,
8368 but we can't know that yet. */
8375 /* If we are taking the address of a constant CONSTRUCTOR, make sure it
8376 is put into static memory. We know that it's going to be read-only
8377 given the semantics we have and it must be in static memory when the
8378 reference is in an elaboration procedure. */
8380 {
8384 }
8386 /* Replace atomic loads with their first argument. That's necessary
8387 because the gimplifier would create a temporary otherwise. */
8390 {
8393 {
8399 else
8401 }
8402 else
8404 }
8411 /* If we are view-converting a CONSTRUCTOR or a call from an aggregate
8412 type to a scalar one, explicitly create the local temporary. That's
8413 required if the type is passed by reference. */
8417 {
8426 }
8433 /* The expressions for the RM bounds must be gimplified to ensure that
8434 they are properly elaborated. See gimplify_decl_expr. */
8438 {
8443 {
8448 {
8452 }
8456 {
8460 }
8462 }
8467 }
8469 /* ... fall through ... */
8473 }
8474 }
8476 /* Generate GIMPLE in place for the statement at *STMT_P. */
8478 static enum gimplify_status
8480 {
8484 {
8490 {
8496 /* Build the condition expression from the test, if any. */
8498 {
8499 /* Deal with the optimization hints. */
8503 annot_expr_ivdep_kind));
8507 annot_expr_no_vector_kind));
8511 annot_expr_vector_kind));
8513 gnu_cond
8516 }
8518 /* Set to emit the statements of the loop. */
8521 /* We first emit the start label and then a conditional jump to the
8522 end label if there's a top condition, then the update if it's at
8523 the top, then the body of the loop, then a conditional jump to
8524 the end label if there's a bottom condition, then the update if
8525 it's at the bottom, and finally a jump to the start label and the
8526 definition of the end label. */
8528 gnu_start_label),
8529 stmt_p);
8550 gnu_end_label),
8551 stmt_p);
8553 }
8556 /* Build a statement to jump to the corresponding end label, then
8557 see if it needs to be conditional. */
8566 }
8567 }
8568 \f
8569 /* Force a reference to each of the entities in GNAT_PACKAGE recursively.
8571 This routine is exclusively called in type_annotate mode, to compute DDA
8572 information for types in withed units, for ASIS use. */
8574 static void
8576 {
8577 Entity_Id gnat_entity;
8582 {
8585 /* We are interested only in entities visible from the main unit. */
8589 /* Skip stuff internal to the compiler. */
8599 /* Skip named numbers. */
8603 /* Skip generic declarations. */
8607 /* Skip formal objects. */
8611 /* Skip package bodies. */
8615 /* Skip limited views that point back to the main unit. */
8621 /* Skip types that aren't frozen. */
8625 /* Recurse on real packages that aren't in the main unit. */
8627 {
8631 }
8632 else
8634 }
8635 }
8637 /* Force a reference to each of the entities in packages withed by GNAT_NODE.
8638 Operate recursively but check that we aren't elaborating something more
8639 than once.
8641 This routine is exclusively called in type_annotate mode, to compute DDA
8642 information for types in withed units, for ASIS use. */
8644 static void
8646 {
8647 Entity_Id gnat_with_clause;
8649 /* Process each unit only once. As we trace the context of all relevant
8650 units transitively, including generic bodies, we may encounter the
8651 same generic unit repeatedly. */
8655 /* Save entities in all context units. A body may have an implicit_with
8656 on its own spec, if the context includes a child unit, so don't save
8657 the spec twice. */
8664 {
8674 {
8677 /* Retrieve compilation unit node of generic body. */
8682 /* If body is available, elaborate its context. */
8685 }
8686 }
8690 }
8691 \f
8692 /* Do the processing of GNAT_NODE, an N_Freeze_Entity. */
8694 static void
8696 {
8701 /* If this is a package, we need to generate code for the package. */
8703 {
8704 insert_code_for
8708 }
8710 /* Don't do anything for class-wide types as they are always transformed
8711 into their root type. */
8715 /* Check for an old definition if this isn't an object with address clause,
8716 since the saved GCC tree is the address expression in that case. */
8717 gnu_old
8721 /* Don't do anything for subprograms that may have been elaborated before
8722 their freeze nodes. This can happen, for example, because of an inner
8723 call in an instance body or because of previous compilation of a spec
8724 for inlining purposes. */
8732 /* If we have a non-dummy type old tree, we have nothing to do, except for
8733 aborting, since this node was never delayed as it should have been. We
8734 let this happen for concurrent types and their Corresponding_Record_Type,
8735 however, because each might legitimately be elaborated before its own
8736 freeze node, e.g. while processing the other. */
8740 {
8745 }
8747 /* Reset the saved tree, if any, and elaborate the object or type for real.
8748 If there is a full view, elaborate it and use the result. And, if this
8749 is the root type of a class-wide type, reuse it for the latter. */
8751 {
8756 {
8763 {
8766 }
8767 }
8773 }
8777 {
8786 /* Propagate back-annotations from full view to partial view. */
8796 /* The above call may have defined this entity (the simplest example
8797 of this is when we have a private enumeral type since the bounds
8798 will have the public view). */
8801 }
8802 else
8803 {
8804 tree gnu_init
8810 }
8817 /* If we have an old type and we've made pointers to this type, update those
8818 pointers. If this is a Taft amendment type in the main unit, we need to
8819 mark the type as used since other units referencing it don't see the full
8820 declaration and, therefore, cannot mark it as used themselves. */
8822 {
8829 }
8830 }
8831 \f
8832 /* Elaborate decls in the lists GNAT_DECLS and GNAT_DECLS2, if present.
8833 We make two passes, one to elaborate anything other than bodies (but
8834 we declare a function if there was no spec). The second pass
8835 elaborates the bodies.
8837 GNAT_END_LIST gives the element in the list past the end. Normally,
8838 this is Empty, but can be First_Real_Statement for a
8839 Handled_Sequence_Of_Statements.
8841 We make a complete pass through both lists if PASS1P is true, then make
8842 the second pass over both lists if PASS2P is true. The lists usually
8843 correspond to the public and private parts of a package. */
8845 static void
8848 {
8850 Node_Id gnat_decl;
8860 {
8861 /* For package specs, we recurse inside the declarations,
8862 thus taking the two pass approach inside the boundary. */
8870 /* Similarly for any declarations in the actions of a
8871 freeze node. */
8873 {
8876 }
8878 /* Package bodies with freeze nodes get their elaboration deferred
8879 until the freeze node, but the code must be placed in the right
8880 place, so record the code position now. */
8888 (Corresponding_Spec
8891 record_code_position
8894 /* We defer most subprogram bodies to the second pass. */
8896 {
8898 {
8904 }
8905 }
8907 /* For bodies and stubs that act as their own specs, the entity
8908 itself must be elaborated in the first pass, because it may
8909 be used in other declarations. */
8911 {
8912 Node_Id gnat_subprog_id
8919 }
8921 /* Concurrent stubs stand for the corresponding subprogram bodies,
8922 which are deferred like other bodies. */
8925 ;
8927 /* Renamed subprograms may not be elaborated yet at this point
8928 since renamings do not trigger freezing. Wait for the second
8929 pass to take care of them. */
8931 ;
8933 else
8935 }
8937 /* Here we elaborate everything we deferred above except for package bodies,
8938 which are elaborated at their freeze nodes. Note that we must also
8939 go inside things (package specs and freeze nodes) the first pass did. */
8945 {
8964 }
8965 }
8966 \f
8967 /* Make a unary operation of kind CODE using build_unary_op, but guard
8968 the operation by an overflow check. CODE can be one of NEGATE_EXPR
8969 or ABS_EXPR. GNU_TYPE is the type desired for the result. Usually
8970 the operation is to be performed in that type. GNAT_NODE is the gnat
8971 node conveying the source location for which the error should be
8972 signaled. */
8974 static tree
8976 Node_Id gnat_node)
8977 {
8986 }
8988 /* Make a binary operation of kind CODE using build_binary_op, but guard
8989 the operation by an overflow check. CODE can be one of PLUS_EXPR,
8990 MINUS_EXPR or MULT_EXPR. GNU_TYPE is the type desired for the result.
8991 Usually the operation is to be performed in that type. GNAT_NODE is
8992 the GNAT node conveying the source location for which the error should
8993 be signaled. */
8995 static tree
8998 {
9007 /* Assert that the precision is a power of 2. */
9010 /* Prefer a constant on the RHS to simplify checks. */
9014 {
9018 }
9022 /* If we can fold the expression to a constant, just return it.
9023 The caller will deal with overflow, no need to generate a check. */
9027 /* If no operand is a constant, we use the generic implementation. */
9029 {
9030 /* Never inline a 64-bit mult for a 32-bit target, it's way too long. */
9032 {
9037 }
9042 {
9054 }
9057 tree call
9065 return
9067 }
9069 /* If one operand is a constant, we expose the overflow condition to enable
9070 a subsequent simplication or even elimination. */
9072 {
9076 /* When rhs > 0, overflow when lhs > type_max - rhs. */
9081 /* When rhs < 0, overflow when lhs < type_min - rhs. */
9085 else
9091 {
9094 /* When lhs > 0, overflow when rhs < lhs - type_max. */
9099 /* When lhs < 0, overflow when rhs > lhs - type_min. */
9103 else
9105 }
9106 else
9107 {
9110 /* When rhs > 0, overflow when lhs < type_min + rhs. */
9115 /* When rhs < 0, overflow when lhs > type_max + rhs. */
9119 else
9121 }
9127 {
9134 /* When rhs > 1, overflow outside [type_min/rhs; type_max/rhs]. */
9135 check
9141 }
9143 {
9148 /* When rhs == -1, overflow if lhs == type_min. */
9149 check
9151 else
9152 /* When rhs < -1, overflow outside [type_max/rhs; type_min/rhs]. */
9153 check
9159 }
9160 else
9166 }
9169 }
9171 /* Emit code for a range check. GNU_EXPR is the expression to be checked,
9172 GNAT_RANGE_TYPE the gnat type or subtype containing the bounds against
9173 which we have to check. GNAT_NODE is the GNAT node conveying the source
9174 location for which the error should be signaled. */
9176 static tree
9178 {
9182 /* If GNU_EXPR has GNAT_RANGE_TYPE as its base type, no check is needed.
9183 This can for example happen when translating 'Val or 'Value. */
9187 /* Range checks can only be applied to types with ranges. */
9191 /* If GNU_EXPR has an integral type that is narrower than GNU_RANGE_TYPE,
9192 we can't do anything since we might be truncating the bounds. No
9193 check is needed in this case. */
9199 /* Checked expressions must be evaluated only once. */
9202 /* Note that the form of the check is
9203 (not (expr >= lo)) or (not (expr <= hi))
9204 the reason for this slightly convoluted form is that NaNs
9205 are not considered to be in range in the float case. */
9206 return emit_check
9208 invert_truthvalue
9212 TYPE_MIN_VALUE
9214 invert_truthvalue
9218 TYPE_MAX_VALUE
9221 }
9222 \f
9223 /* GNU_COND contains the condition corresponding to an index, overflow or
9224 range check of value GNU_EXPR. Build a COND_EXPR that returns GNU_EXPR
9225 if GNU_COND is false and raises a CONSTRAINT_ERROR if GNU_COND is true.
9226 REASON is the code that says why the exception is raised. GNAT_NODE is
9227 the node conveying the source location for which the error should be
9228 signaled.
9230 We used to propagate TREE_SIDE_EFFECTS from GNU_EXPR to the COND_EXPR,
9231 overwriting the setting inherited from the call statement, on the ground
9232 that the expression need not be evaluated just for the check. However
9233 that's incorrect because, in the GCC type system, its value is presumed
9234 to be valid so its comparison against the type bounds always yields true
9235 and, therefore, could be done without evaluating it; given that it can
9236 be a computation that overflows the bounds, the language may require the
9237 check to fail and thus the expression to be evaluated in this case. */
9239 static tree
9241 {
9242 tree gnu_call
9244 return
9250 gnu_expr);
9251 }
9252 \f
9253 /* Return an expression that converts GNU_EXPR to GNAT_TYPE, doing overflow
9254 checks if OVERFLOW_P is true and range checks if RANGE_P is true.
9255 If TRUNCATE_P true, do a float-to-integer conversion with truncation,
9256 otherwise round. GNAT_NODE is the GNAT node conveying the source location
9257 for which the error should be signaled. */
9259 static tree
9262 {
9269 /* If we are not doing any checks, the output is an integral type and the
9270 input is not a floating-point type, just do the conversion. This is
9271 required for packed array types and is simpler in all cases anyway. */
9273 && !overflow_p
9278 /* If the mode of the input base type is larger, then converting to it below
9279 may pessimize the final conversion step, for example generate a libcall
9280 instead of a simple instruction, so use a narrower type in this case. */
9287 /* First convert the expression to the base type. This will never generate
9288 code, but makes the tests below simpler. But don't do this if converting
9289 from an integer type to an unconstrained array type since then we need to
9290 get the bounds from the original (unpacked) type. */
9294 /* If overflow checks are requested, we need to be sure the result will fit
9295 in the output base type. But don't do this if the input is integer and
9296 the output floating-point. */
9299 {
9300 /* Ensure GNU_EXPR only gets evaluated once. */
9308 /* Convert the lower bounds to signed types, so we're sure we're
9309 comparing them properly. Likewise, convert the upper bounds
9310 to unsigned types. */
9313 gnu_in_lb
9318 gnu_in_ub
9322 gnu_out_lb
9326 gnu_out_ub
9329 /* Check each bound separately and only if the result bound
9330 is tighter than the bound on the input type. Note that all the
9331 types are base types, so the bounds must be constant. Also,
9332 the comparison is done in the base type of the input, which
9333 always has the proper signedness. First check for input
9334 integer (which means output integer), output float (which means
9335 both float), or mixed, in which case we always compare.
9336 Note that we have to do the comparison which would *fail* in the
9337 case of an error since if it's an FP comparison and one of the
9338 values is a NaN or Inf, the comparison will fail. */
9345 gnu_cond
9346 = invert_truthvalue
9349 gnu_out_lb)));
9357 gnu_cond
9359 invert_truthvalue
9361 gnu_input,
9363 gnu_out_ub))));
9368 }
9370 /* Now convert to the result base type. If this is a non-truncating
9371 float-to-integer conversion, round. */
9375 {
9381 /* The following calculations depend on proper rounding to even
9382 of each arithmetic operation. In order to prevent excess
9383 precision from spoiling this property, use the widest hardware
9384 floating-point type if FP_ARITH_MAY_WIDEN is true. */
9385 calc_type
9388 /* Compute the exact value calc_type'Pred (0.5) at compile time. */
9395 /* If the input is strictly negative, subtract this value
9396 and otherwise add it from the input. For 0.5, the result
9397 is exactly between 1.0 and the machine number preceding 1.0
9398 (for calc_type). Since the last bit of 1.0 is even, this 0.5
9399 will round to 1.0, while all other number with an absolute
9400 value less than 0.5 round to 0.0. For larger numbers exactly
9401 halfway between integers, rounding will always be correct as
9402 the true mathematical result will be closer to the higher
9403 integer compared to the lower one. So, this constant works
9404 for all floating-point numbers.
9406 The reason to use the same constant with subtract/add instead
9407 of a positive and negative constant is to allow the comparison
9408 to be scheduled in parallel with retrieval of the constant and
9409 conversion of the input to the calc_type (if necessary). */
9414 gnu_comp
9416 gnu_add_pred_half
9418 gnu_subtract_pred_half
9422 }
9428 else
9431 /* Finally, do the range check if requested. Note that if the result type
9432 is a modular type, the range check is actually an overflow check. */
9434 || (overflow_p
9440 }
9441 \f
9442 /* Return true if GNU_EXPR can be directly addressed. This is the case
9443 unless it is an expression involving computation or if it involves a
9444 reference to a bitfield or to an object not sufficiently aligned for
9445 its type. If GNU_TYPE is non-null, return true only if GNU_EXPR can
9446 be directly addressed as an object of this type.
9448 *** Notes on addressability issues in the Ada compiler ***
9450 This predicate is necessary in order to bridge the gap between Gigi
9451 and the middle-end about addressability of GENERIC trees. A tree
9452 is said to be addressable if it can be directly addressed, i.e. if
9453 its address can be taken, is a multiple of the type's alignment on
9454 strict-alignment architectures and returns the first storage unit
9455 assigned to the object represented by the tree.
9457 In the C family of languages, everything is in practice addressable
9458 at the language level, except for bit-fields. This means that these
9459 compilers will take the address of any tree that doesn't represent
9460 a bit-field reference and expect the result to be the first storage
9461 unit assigned to the object. Even in cases where this will result
9462 in unaligned accesses at run time, nothing is supposed to be done
9463 and the program is considered as erroneous instead (see PR c/18287).
9465 The implicit assumptions made in the middle-end are in keeping with
9466 the C viewpoint described above:
9467 - the address of a bit-field reference is supposed to be never
9468 taken; the compiler (generally) will stop on such a construct,
9469 - any other tree is addressable if it is formally addressable,
9470 i.e. if it is formally allowed to be the operand of ADDR_EXPR.
9472 In Ada, the viewpoint is the opposite one: nothing is addressable
9473 at the language level unless explicitly declared so. This means
9474 that the compiler will both make sure that the trees representing
9475 references to addressable ("aliased" in Ada parlance) objects are
9476 addressable and make no real attempts at ensuring that the trees
9477 representing references to non-addressable objects are addressable.
9479 In the first case, Ada is effectively equivalent to C and handing
9480 down the direct result of applying ADDR_EXPR to these trees to the
9481 middle-end works flawlessly. In the second case, Ada cannot afford
9482 to consider the program as erroneous if the address of trees that
9483 are not addressable is requested for technical reasons, unlike C;
9484 as a consequence, the Ada compiler must arrange for either making
9485 sure that this address is not requested in the middle-end or for
9486 compensating by inserting temporaries if it is requested in Gigi.
9488 The first goal can be achieved because the middle-end should not
9489 request the address of non-addressable trees on its own; the only
9490 exception is for the invocation of low-level block operations like
9491 memcpy, for which the addressability requirements are lower since
9492 the type's alignment can be disregarded. In practice, this means
9493 that Gigi must make sure that such operations cannot be applied to
9494 non-BLKmode bit-fields.
9496 The second goal is achieved by means of the addressable_p predicate,
9497 which computes whether a temporary must be inserted by Gigi when the
9498 address of a tree is requested; if so, the address of the temporary
9499 will be used in lieu of that of the original tree and some glue code
9500 generated to connect everything together. */
9502 static bool
9504 {
9505 /* For an integral type, the size of the actual type of the object may not
9506 be greater than that of the expected type, otherwise an indirect access
9507 in the latter type wouldn't correctly set all the bits of the object. */
9513 /* The size of the actual type of the object may not be smaller than that
9514 of the expected type, otherwise an indirect access in the latter type
9515 would be larger than the object. But only record types need to be
9516 considered in practice for this case. */
9523 {
9528 /* All DECLs are addressable: if they are in a register, we can force
9529 them to memory. */
9534 /* Taking the address of a dereference yields the original pointer. */
9539 /* Taking the address yields a pointer to the constant pool. */
9543 /* Taking the address of a static constructor yields a pointer to the
9544 tree constant pool. */
9556 /* All rvalues are deemed addressable since taking their address will
9557 force a temporary to be created by the middle-end. */
9561 /* The address of a compound expression is that of its 2nd operand. */
9565 /* We accept &COND_EXPR as soon as both operands are addressable and
9566 expect the outcome to be the address of the selected operand. */
9572 /* Even with DECL_BIT_FIELD cleared, we have to ensure that
9573 the field is sufficiently aligned, in case it is subject
9574 to a pragma Component_Alignment. But we don't need to
9575 check the alignment of the containing record, as it is
9576 guaranteed to be not smaller than that of its most
9577 aligned field that is not a bit-field. */
9578 && (!STRICT_ALIGNMENT
9581 /* The field of a padding record is always addressable. */
9595 {
9596 /* This is addressable if we can avoid a copy. */
9600 && (!STRICT_ALIGNMENT
9605 && (!STRICT_ALIGNMENT
9611 }
9615 }
9616 }
9617 \f
9618 /* Do the processing for the declaration of a GNAT_ENTITY, a type or subtype.
9619 If a Freeze node exists for the entity, delay the bulk of the processing.
9620 Otherwise make a GCC type for GNAT_ENTITY and set up the correspondence. */
9622 void
9624 {
9625 tree gnu_old
9628 /* If we are to delay elaboration of this type, just do any elaboration
9629 needed for expressions within the declaration and make a dummy node
9630 for it and its Full_View (if any), in case something points to it.
9631 Do not do this if it has already been done (the only way that can
9632 happen is if the private completion is also delayed). */
9634 {
9638 {
9643 {
9647 }
9648 }
9651 }
9653 /* If we saved away a dummy type for this node, it means that this made the
9654 type that corresponds to the full type of an incomplete type. Clear that
9655 type for now and then update the type in the pointers below. But, if the
9656 saved type is not dummy, it very likely means that we have a use before
9657 declaration for the type in the tree, what we really cannot handle. */
9659 {
9664 }
9666 /* Now fully elaborate the type. */
9670 /* If we have an old type and we've made pointers to this type, update those
9671 pointers. If this is a Taft amendment type in the main unit, we need to
9672 mark the type as used since other units referencing it don't see the full
9673 declaration and, therefore, cannot mark it as used themselves. */
9675 {
9680 }
9682 /* If this is a record type corresponding to a task or protected type
9683 that is a completion of an incomplete type, perform a similar update
9684 on the type. ??? Including protected types here is a guess. */
9688 {
9689 tree gnu_task_old
9699 }
9700 }
9701 \f
9702 /* Subroutine of assoc_to_constructor: VALUES is a list of field associations,
9703 some of which are from RECORD_TYPE. Return a CONSTRUCTOR consisting of the
9704 associations that are from RECORD_TYPE. If we see an internal record, make
9705 a recursive call to fill it in as well. */
9707 static tree
9709 {
9711 tree field;
9714 {
9717 /* _Parent is an internal field, but may have values in the aggregate,
9718 so check for values first. */
9720 {
9723 }
9726 {
9731 }
9732 else
9733 /* If we have a record subtype, the names will match, but not the
9734 actual FIELD_DECLs. */
9737 {
9740 }
9746 }
9749 }
9751 /* GNAT_ENTITY is the type of the resulting constructor, GNAT_ASSOC is the
9752 front of the Component_Associations of an N_Aggregate and GNU_TYPE is the
9753 GCC type of the corresponding record type. Return the CONSTRUCTOR. */
9755 static tree
9757 {
9760 /* We test for GNU_FIELD being empty in the case where a variant
9761 was the last thing since we don't take things off GNAT_ASSOC in
9762 that case. We check GNAT_ASSOC in case we have a variant, but it
9763 has no fields. */
9766 {
9771 /* The expander is supposed to put a single component selector name
9772 in every record component association. */
9775 /* Ignore discriminants that have Corresponding_Discriminants in tagged
9776 types since we'll be setting those fields in the parent subtype. */
9782 /* Also ignore discriminants of Unchecked_Unions. */
9787 /* Before assigning a value in an aggregate make sure range checks
9788 are done if required. Then convert to the type of the field. */
9794 /* Add the field and expression to the list. */
9796 }
9801 {
9802 /* Verify that every entry in GNU_LIST was used. */
9805 }
9808 }
9810 /* Build a possibly nested constructor for array aggregates. GNAT_EXPR is
9811 the first element of an array aggregate. It may itself be an aggregate.
9812 GNU_ARRAY_TYPE is the GCC type corresponding to the array aggregate.
9813 GNAT_COMPONENT_TYPE is the type of the array component; it is needed
9814 for range checking. */
9816 static tree
9818 Entity_Id gnat_component_type)
9819 {
9824 {
9825 tree gnu_expr;
9827 /* If the expression is itself an array aggregate then first build the
9828 innermost constructor if it is part of our array (multi-dimensional
9829 case). */
9835 gnat_component_type);
9836 else
9837 {
9838 /* If the expression is a conversion to an unconstrained array type,
9839 skip it to avoid spilling to memory. */
9844 else
9847 /* Before assigning the element to the array, make sure it is
9848 in range. */
9851 }
9858 integer_one_node));
9859 }
9862 }
9863 \f
9864 /* Process a N_Validate_Unchecked_Conversion node. */
9866 static void
9868 {
9872 /* If the target is a pointer type, see if we are either converting from a
9873 non-pointer or from a pointer to a type with a different alias set and
9874 warn if so, unless the pointer has been marked to alias everything. */
9877 {
9887 target_alias_set)))
9888 {
9892 gnat_node);
9895 }
9896 }
9898 /* Likewise if the target is a fat pointer type, but we have no mechanism to
9899 mitigate the problem in this case, so we unconditionally warn. */
9901 {
9902 tree gnu_source_desig_type
9906 tree gnu_target_desig_type
9913 target_alias_set)))
9914 {
9918 gnat_node);
9919 }
9920 }
9921 }
9922 \f
9923 /* EXP is to be used in a context where access objects are implicitly
9924 dereferenced. Handle the cases when it is an access object. */
9926 static Node_Id
9928 {
9931 /* Make sure the designated type is complete before dereferencing. */
9936 }
9938 /* EXP is to be treated as an array or record. Handle the cases when it is
9939 an access object and perform the required dereferences. */
9941 static tree
9943 {
9944 /* If the type is a pointer, dereference it. */
9949 /* If we got a padded type, remove it too. */
9954 }
9955 \f
9956 /* Convert SLOC into LOCUS. Return true if SLOC corresponds to a source code
9957 location and false if it doesn't. If CLEAR_COLUMN is true, set the column
9958 information to 0. */
9960 bool
9962 {
9967 {
9970 }
9977 /* We can have zero if pragma Source_Reference is in effect. */
9981 /* Translate the location. */
9982 *locus
9986 }
9988 /* Similar to set_expr_location, but start with the Sloc of GNAT_NODE and
9989 don't do anything if it doesn't correspond to a source location. And,
9990 if CLEAR_COLUMN is true, set the column information to 0. */
9992 static void
9994 {
9995 location_t locus;
10001 }
10003 /* More elaborate version of set_expr_location_from_node to be used in more
10004 general contexts, for example the result of the translation of a generic
10005 GNAT node. */
10007 static void
10009 {
10010 /* Set the location information on the node if it is a real expression.
10011 References can be reused for multiple GNAT nodes and they would get
10012 the location information of their last use. Also make sure not to
10013 overwrite an existing location as it is probably more precise. */
10016 {
10017 CASE_CONVERT:
10026 /* ... fall through ... */
10030 {
10033 }
10035 }
10036 }
10038 /* Set the end_locus information for GNU_NODE, if any, from an explicit end
10039 location associated with GNAT_NODE or GNAT_NODE itself, whichever makes
10040 most sense. Return true if a sensible assignment was performed. */
10042 static bool
10044 {
10045 Node_Id gnat_end_label;
10046 location_t end_locus;
10048 /* Pick the GNAT node of which we'll take the sloc to assign to the GCC node
10049 end_locus when there is one. We consider only GNAT nodes with a possible
10050 End_Label attached. If the End_Label actually was unassigned, fallback
10051 on the original node. We'd better assign an explicit sloc associated with
10052 the outer construct in any case. */
10055 {
10068 }
10073 /* Some expanded subprograms have neither an End_Label nor a Sloc
10074 attached. Notify that to callers. For a block statement with no
10075 End_Label, clear column information, so that the tree for a
10076 transient block does not receive the sloc of a source condition. */
10083 {
10094 }
10095 }
10096 \f
10097 /* Return a colon-separated list of encodings contained in encoded Ada
10098 name. */
10102 {
10106 }
10108 /* Extract the Ada name from an encoded name. */
10112 {
10116 }
10117 \f
10118 /* Post an error message. MSG is the error message, properly annotated.
10119 NODE is the node at which to post the error and the node to use for the
10120 '&' substitution. */
10122 void
10124 {
10125 String_Template temp;
10126 String_Pointer sp;
10136 }
10138 /* Similar to post_error, but NODE is the node at which to post the error and
10139 ENT is the node to use for the '&' substitution. */
10141 void
10143 {
10144 String_Template temp;
10145 String_Pointer sp;
10155 }
10157 /* Similar to post_error_ne, but NUM is the number to use for the '^'. */
10159 void
10161 {
10164 }
10166 /* Similar to post_error_ne, but T is a GCC tree representing the number to
10167 write. If T represents a constant, the text inside curly brackets in
10168 MSG will be output (presumably including a '^'). Otherwise it will not
10169 be output and the text inside square brackets will be output instead. */
10171 void
10173 {
10180 {
10183 }
10184 else
10188 {
10194 ;
10195 else
10197 }
10202 }
10204 /* Similar to post_error_ne_tree, but NUM is a second integer to write. */
10206 void
10209 {
10212 }
10214 /* Return a label to branch to for the exception type in KIND or NULL_TREE
10215 if none. */
10217 tree
10219 {
10221 {
10233 }
10236 }
10238 /* Return the decl for the current elaboration procedure. */
10240 static tree
10242 {
10244 }
10246 /* Initialize the table that maps GNAT codes to GCC codes for simple
10247 binary and unary operations. */
10249 static void
10251 {
10276 }