| blob | 7379477215868790973dba1f6f78f5574a61d1ae |
1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * T R A N S *
6 * *
7 * C Implementation File *
8 * *
9 * Copyright (C) 1992-2015, 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 ****************************************************************************/
84 /* We should avoid allocating more than ALLOCA_THRESHOLD bytes via alloca,
85 for fear of running out of stack space. If we need more, we use xmalloc
86 instead. */
87 #define ALLOCA_THRESHOLD 1000
89 /* In configurations where blocks have no end_locus attached, just
90 sink assignments into a dummy global. */
91 #ifndef BLOCK_SOURCE_END_LOCATION
93 #define BLOCK_SOURCE_END_LOCATION(BLOCK) block_end_locus_sink
94 #endif
96 /* Pointers to front-end tables accessed through macros. */
107 /* Highest number in the front-end node table. */
110 /* Current node being treated, in case abort called. */
111 Node_Id error_gnat_node;
113 /* True when gigi is being called on an analyzed but unexpanded
114 tree, and the only purpose of the call is to properly annotate
115 types with representation information. */
118 /* Current filename without path. */
122 /* List of N_Validate_Unchecked_Conversion nodes in the unit. */
125 /* When not optimizing, we cache the 'First, 'Last and 'Length attributes
126 of unconstrained array IN parameters to avoid emitting a great deal of
127 redundant instructions to recompute them each time. */
131 tree first;
132 tree last;
133 tree length;
134 };
141 bitmap named_ret_val;
144 };
146 #define f_parm_attr_cache \
147 DECL_STRUCT_FUNCTION (current_function_decl)->language->parm_attr_cache
149 #define f_named_ret_val \
150 DECL_STRUCT_FUNCTION (current_function_decl)->language->named_ret_val
152 #define f_other_ret_val \
153 DECL_STRUCT_FUNCTION (current_function_decl)->language->other_ret_val
155 #define f_gnat_ret \
156 DECL_STRUCT_FUNCTION (current_function_decl)->language->gnat_ret
158 /* A structure used to gather together information about a statement group.
159 We use this to gather related statements, for example the "then" part
160 of a IF. In the case where it represents a lexical scope, we may also
161 have a BLOCK node corresponding to it and/or cleanups. */
168 };
172 /* List of unused struct stmt_group nodes. */
175 /* A structure used to record information on elaboration procedures
176 we've made and need to process.
178 ??? gnat_node should be Node_Id, but gengtype gets confused. */
184 };
188 /* Stack of exception pointer variables. Each entry is the VAR_DECL
189 that stores the address of the raised exception. Nonzero means we
190 are in an exception handler. Not used in the zero-cost case. */
193 /* In ZCX case, current exception pointer. Used to re-raise it. */
196 /* Stack for storing the current elaboration procedure decl. */
199 /* Stack of labels to be used as a goto target instead of a return in
200 some functions. See processing for N_Subprogram_Body. */
203 /* Stack of variable for the return value of a function with copy-in/copy-out
204 parameters. See processing for N_Subprogram_Body. */
207 /* Structure used to record information for a range check. */
209 tree low_bound;
210 tree high_bound;
211 tree type;
212 tree invariant_cond;
213 };
218 /* Structure used to record information for a loop. */
220 tree stmt;
221 tree loop_var;
223 };
228 /* Stack of loop_info structures associated with LOOP_STMT nodes. */
231 /* The stacks for N_{Push,Pop}_*_Label. */
236 /* Map GNAT tree codes to GCC tree codes for simple expressions. */
273 /* Hooks for debug info back-ends, only supported and used in a restricted set
274 of configurations. */
277 \f
278 /* This is the main program of the back-end. It sets up all the table
279 structures and then generates code. */
281 void
294 Nat number_file,
296 Entity_Id standard_boolean,
297 Entity_Id standard_integer,
298 Entity_Id standard_character,
299 Entity_Id standard_long_long_float,
300 Entity_Id standard_exception_type,
301 Int gigi_operating_mode)
302 {
303 Node_Id gnat_iter;
304 Entity_Id gnat_literal;
324 {
325 /* Use the identifier table to make a permanent copy of the filename as
326 the name table gets reallocated after Gigi returns but before all the
327 debugging information is output. The __gnat_to_canonical_file_spec
328 call translates filenames from pragmas Source_Reference that contain
329 host style syntax not understood by gdb. */
331 = IDENTIFIER_POINTER
332 (get_identifier
333 (__gnat_to_canonical_file_spec
336 /* We rely on the order isomorphism between files and line maps. */
339 /* We create the line map for a source file at once, with a fixed number
340 of columns chosen to avoid jumping over the next power of 2. */
345 }
349 /* Declare the name of the compilation unit as the first global
350 name in order to make the middle-end fully deterministic. */
354 /* Initialize ourselves. */
359 /* If we are just annotating types, give VOID_TYPE zero sizes to avoid
360 errors. */
362 {
365 }
367 /* Enable GNAT stack checking method if needed */
371 /* Retrieve alignment settings. */
375 /* Record the builtin types. Define `integer' and `character' first so that
376 dbx will output them first. */
382 /* Save the type we made for integer as the type for Standard.Integer. */
387 /* Likewise for character as the type for Standard.Character. */
392 /* Likewise for boolean as the type for Standard.Boolean. */
416 /* Now declare run-time functions. */
419 /* malloc is a function declaration tree for a function to allocate
420 memory. */
421 malloc_decl
427 /* free is a function declaration tree for a function to free memory. */
428 free_decl
431 ptr_void_type_node,
432 NULL_TREE),
434 Empty);
436 /* This is used for 64-bit multiplication with overflow checking. */
438 mulv64_decl
443 Empty);
445 /* Name of the _Parent field in tagged record types. */
448 /* Name of the Exception_Data type defined in System.Standard_Library. */
449 exception_data_name_id
452 /* Make the types and functions used for exception processing. */
453 jmpbuf_type
459 /* Functions to get and set the jumpbuf pointer for the current thread. */
460 get_jmpbuf_decl
461 = create_subprog_decl
467 set_jmpbuf_decl
468 = create_subprog_decl
471 NULL_TREE),
475 /* setjmp returns an integer and has one operand, which is a pointer to
476 a jmpbuf. */
477 setjmp_decl
478 = create_subprog_decl
481 NULL_TREE),
486 /* update_setjmp_buf updates a setjmp buffer from the current stack pointer
487 address. */
488 update_setjmp_buf_decl
489 = create_subprog_decl
496 /* Hooks to call when entering/leaving an exception handler. */
497 ftype
500 begin_handler_decl
506 end_handler_decl
512 unhandled_except_decl
514 NULL_TREE,
519 reraise_zcx_decl
523 /* Indicate that these never return. */
530 /* If in no exception handlers mode, all raise statements are redirected to
531 __gnat_last_chance_handler. No need to redefine raise_nodefer_decl since
532 this procedure will never be called in this mode. */
534 {
535 tree decl
536 = create_subprog_decl
539 build_pointer_type
549 }
550 else
551 {
552 /* Otherwise, make one decl for each exception reason. */
558 i == CE_Index_Check_Failed
562 }
564 /* Set the types that GCC and Gigi use from the front end. */
567 /* Make other functions used for exception processing. */
568 get_excptr_decl
569 = create_subprog_decl
572 NULL_TREE),
576 set_exception_parameter_decl
577 = create_subprog_decl
580 ptr_void_type_node,
581 ptr_void_type_node,
582 NULL_TREE),
585 raise_nodefer_decl
586 = create_subprog_decl
590 NULL_TREE),
593 /* Indicate that it never returns. */
598 TYPE_QUAL_VOLATILE);
600 /* Build the special descriptor type and its null node if needed. */
602 {
614 {
615 tree field
622 elt--;
623 }
628 }
630 longest_float_type_node
633 /* Dummy objects to materialize "others" and "all others" in the exception
634 tables. These are exported by a-exexpr-gcc.adb, so see this unit for
635 the types to use. */
636 others_decl
639 unsigned_char_type_node,
642 all_others_decl
645 unsigned_char_type_node,
648 unhandled_others_decl
651 unsigned_char_type_node,
656 /* Install the builtins we might need, either internally or as
657 user available facilities for Intrinsic imports. */
665 /* Process any Pragma Ident for the main unit. */
670 /* If we are using the GCC exception mechanism, let GCC know. */
674 /* Initialize the GCC support for FP operations. */
677 /* Force -fno-strict-aliasing if the configuration pragma was seen. */
681 /* Save the current optimization options again after the above possible
682 global_options changes. */
686 /* Now translate the compilation unit proper. */
689 /* Then process the N_Validate_Unchecked_Conversion nodes. We do this at
690 the very end to avoid having to second-guess the front-end when we run
691 into dummy nodes during the regular processing. */
696 /* Finally see if we have any elaboration procedures to deal with. */
698 {
701 /* We should have a BIND_EXPR but it may not have any statements in it.
702 If it doesn't have any, we have nothing to do except for setting the
703 flag on the GNAT node. Otherwise, process the function as others. */
709 else
710 {
714 }
715 }
717 /* Destroy ourselves. */
721 /* We cannot track the location of errors past this point. */
723 }
724 \f
725 /* Return a subprogram decl corresponding to __gnat_rcheck_xx for the given
726 CHECK if KIND is EXCEPTION_SIMPLE, or else to __gnat_rcheck_xx_ext. */
728 static tree
730 {
739 {
741 ftype
743 build_pointer_type
746 }
747 else
748 {
753 ftype
755 build_pointer_type
759 }
761 result
766 /* Indicate that it never returns. */
773 }
774 \f
775 /* Return a positive value if an lvalue is required for GNAT_NODE, which is
776 an N_Attribute_Reference. */
778 static int
780 {
782 {
822 }
823 }
825 /* Return a positive value if an lvalue is required for GNAT_NODE. GNU_TYPE
826 is the type that will be used for GNAT_NODE in the translated GNU tree.
827 CONSTANT indicates whether the underlying object represented by GNAT_NODE
828 is constant in the Ada sense. If it is, ADDRESS_OF_CONSTANT indicates
829 whether its value is the address of a constant and ALIASED whether it is
830 aliased. If it isn't, ADDRESS_OF_CONSTANT and ALIASED are ignored.
832 The function climbs up the GNAT tree starting from the node and returns 1
833 upon encountering a node that effectively requires an lvalue downstream.
834 It returns int instead of bool to facilitate usage in non-purely binary
835 logic contexts. */
837 static int
840 {
844 {
854 /* If the parameter is by reference, an lvalue is required. */
860 /* Only the array expression can require an lvalue. */
864 /* ??? Consider that referencing an indexed component with a
865 non-constant index forces the whole aggregate to memory.
866 Note that N_Integer_Literal is conservative, any static
867 expression in the RM sense could probably be accepted. */
874 /* ... fall through ... */
877 /* Only the array expression can require an lvalue. */
891 /* We need to preserve addresses through a renaming. */
895 /* We cannot use a constructor if this is an atomic object because
896 the actual assignment might end up being done component-wise. */
900 /* We don't use a constructor if this is a class-wide object
901 because the effective type of the object is the equivalent
902 type of the class-wide subtype and it smashes most of the
903 data into an array of bytes to which we cannot convert. */
908 /* We cannot use a constructor if the LHS is an atomic object because
909 the actual assignment might end up being done component-wise. */
919 /* ... fall through ... */
923 /* We must look through all conversions because we may need to bypass
924 an intermediate conversion that is meant to be purely formal. */
930 /* We should only reach here through the N_Qualified_Expression case.
931 Force an lvalue for composite types since a block-copy to the newly
932 allocated area of memory is made. */
936 /* We look through dereferences for address of constant because we need
937 to handle the special cases listed above. */
943 /* ... fall through ... */
947 }
950 }
952 /* Return true if T is a constant DECL node that can be safely replaced
953 by its initializer. */
955 static bool
957 {
961 /* Return false for aggregate types that contain a placeholder since
962 their initializers cannot be manipulated easily. */
969 }
971 /* Return an expression equivalent to EXP but where constant DECL nodes
972 have been replaced by their initializer. */
974 static tree
976 {
978 tree op0;
981 {
1018 }
1021 }
1023 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Identifier,
1024 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer
1025 to where we should place the result type. */
1027 static tree
1029 {
1033 /* Whether we should require an lvalue for GNAT_NODE. Needed in
1034 specific circumstances only, so evaluated lazily. < 0 means
1035 unknown, > 0 means known true, 0 means known false. */
1038 /* If GNAT_NODE is a constant, whether we should use the initialization
1039 value instead of the constant entity, typically for scalars with an
1040 address clause when the parent doesn't require an lvalue. */
1043 /* If the Etype of this node does not equal the Etype of the Entity,
1044 something is wrong with the entity map, probably in generic
1045 instantiation. However, this does not apply to types. Since we sometime
1046 have strange Ekind's, just do this test for objects. Also, if the Etype of
1047 the Entity is private, the Etype of the N_Identifier is allowed to be the
1048 full type and also we consider a packed array type to be the same as the
1049 original type. Similarly, a class-wide type is equivalent to a subtype of
1050 itself. Finally, if the types are Itypes, one may be a copy of the other,
1051 which is also legal. */
1066 == Packed_Array_Impl_Type
1075 /* If this is a reference to a deferred constant whose partial view is an
1076 unconstrained private type, the proper type is on the full view of the
1077 constant, not on the full view of the type, which may be unconstrained.
1079 This may be a reference to a type, for example in the prefix of the
1080 attribute Position, generated for dispatching code (see Make_DT in
1081 exp_disp,adb). In that case we need the type itself, not is parent,
1082 in particular if it is a derived type */
1089 {
1092 }
1093 else
1094 {
1095 /* We want to use the Actual_Subtype if it has already been elaborated,
1096 otherwise the Etype. Avoid using Actual_Subtype for packed arrays to
1097 simplify things. */
1105 else
1107 }
1109 /* Expand the type of this identifier first, in case it is an enumeral
1110 literal, which only get made when the type is expanded. There is no
1111 order-of-elaboration issue here. */
1114 /* If this is a non-imported elementary constant with an address clause,
1115 retrieve the value instead of a pointer to be dereferenced unless
1116 an lvalue is required. This is generally more efficient and actually
1117 required if this is a static expression because it might be used
1118 in a context where a dereference is inappropriate, such as a case
1119 statement alternative or a record discriminant. There is no possible
1120 volatile-ness short-circuit here since Volatile constants must be
1121 imported per C.6. */
1126 {
1130 }
1133 {
1134 /* If this is a deferred constant, the initializer is attached to
1135 the full view. */
1140 }
1141 else
1144 /* Some objects (such as parameters passed by reference, globals of
1145 variable size, and renamed objects) actually represent the address
1146 of the object. In that case, we must do the dereference. Likewise,
1147 deal with parameters to foreign convention subprograms. */
1152 {
1155 /* If it's a PARM_DECL to foreign convention subprogram, convert it. */
1158 gnu_result
1161 /* If it's a CONST_DECL, return the underlying constant like below. */
1168 /* If it's a renaming pointer and, either the renamed object is constant
1169 or we are at the right binding level, we can reference the renamed
1170 object directly, since it is constant or has been protected against
1171 multiple evaluations. */
1180 /* Otherwise, do the final dereference. */
1181 else
1182 {
1192 }
1193 }
1195 /* If we have a constant declaration and its initializer, try to return the
1196 latter to avoid the need to call fold in lots of places and the need for
1197 elaboration code if this identifier is used as an initializer itself. */
1199 {
1205 /* If there is a (corresponding) variable or this is the address of a
1206 constant, we only want to return the initializer if an lvalue isn't
1207 required. Evaluate this now if we have not already done so. */
1209 require_lvalue
1213 /* Finally retrieve the initializer if this is deemed valid. */
1216 }
1218 /* But for a constant renaming we couldn't do that incrementally for its
1219 definition because of the need to return an lvalue so, if the present
1220 context doesn't itself require an lvalue, we try again here. */
1224 {
1226 require_lvalue
1231 }
1233 /* The GNAT tree has the type of a function set to its result type, so we
1234 adjust here. Also use the type of the result if the Etype is a subtype
1235 that is nominally unconstrained. Likewise if this is a deferred constant
1236 of a discriminated type whose full view can be elaborated statically, to
1237 avoid problematic conversions to the nominal subtype. But remove any
1238 padding from the resulting type. */
1245 {
1249 }
1254 }
1255 \f
1256 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Pragma. Return
1257 any statements we generate. */
1259 static tree
1261 {
1264 Node_Id gnat_temp;
1266 /* Do nothing if we are just annotating types and check for (and ignore)
1267 unrecognized pragmas. */
1274 {
1276 /* Do nothing at top level: all such variables are already viewable. */
1283 {
1287 machine_mode mode;
1289 #ifdef ASM_COMMENT_START
1291 #endif
1296 /* Use the value only if it fits into a normal register,
1297 otherwise use the address. */
1306 #ifdef ASM_COMMENT_START
1312 NULL);
1315 #endif
1317 asm_constraint,
1318 NULL_TREE,
1319 tree_cons
1327 }
1334 {
1338 {
1361 }
1362 }
1368 {
1386 }
1396 {
1397 Node_Id gnat_expr;
1398 /* Preserve the location of the pragma. */
1402 diagnostic_t kind;
1407 /* This is the String form: pragma Warning{s|_As_Error}(String). */
1409 {
1411 {
1424 }
1427 }
1429 /* This is the On/Off form: pragma Warnings (On | Off [,String]). */
1431 {
1433 {
1444 }
1446 /* Deal with optional pattern (but ignore Reason => "..."). */
1448 {
1449 /* pragma Warnings (On | Off, Name) is handled differently. */
1454 }
1455 else
1459 }
1461 else
1464 /* This is the same implementation as in the C family of compilers. */
1466 {
1474 option_index++)
1478 {
1481 }
1482 }
1483 else
1490 }
1495 }
1498 }
1499 \f
1501 /* Check the inlining status of nested function FNDECL in the current context.
1503 If a non-inline nested function is referenced from an inline external
1504 function, we cannot honor both requests at the same time without cloning
1505 the nested function in the current unit since it is private to its unit.
1506 We could inline it as well but it's probably better to err on the side
1507 of too little inlining.
1509 This must be invoked only on nested functions present in the source code
1510 and not on nested functions generated by the compiler, e.g. finalizers,
1511 because they are not marked inline and we don't want them to block the
1512 inlining of the parent function. */
1514 static void
1516 {
1518 && current_function_decl
1521 {
1527 {
1530 }
1531 else
1532 {
1534 fndecl);
1536 }
1540 }
1541 }
1542 \f
1543 /* Return an expression for the length of TYPE, an integral type, computed in
1544 RESULT_TYPE, another integral type.
1546 We used to compute the length as MAX (hb - lb + 1, 0) which could overflow
1547 when lb == TYPE'First. We now compute it as (hb >= lb) ? hb - lb + 1 : 0
1548 which would only overflow in much rarer cases, for extremely large arrays
1549 we expect never to encounter in practice. Besides, the former computation
1550 required the use of potentially constraining signed arithmetics while the
1551 latter does not. Note that the comparison must be done in the original
1552 base index type in order to avoid any overflow during the conversion. */
1554 static tree
1556 {
1561 tree length
1567 length
1573 }
1575 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Attribute node,
1576 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to
1577 where we should place the result type. ATTRIBUTE is the attribute ID. */
1579 static tree
1581 {
1587 /* ??? If this is an access attribute for a public subprogram to be used in
1588 a dispatch table, do not translate its type as it's useless in this case
1589 and the parameter types might be incomplete types coming from a limited
1590 context in Ada 2012 (AI05-0151). */
1598 else
1602 /* If the input is a NULL_EXPR, make a new one. */
1604 {
1608 }
1611 {
1614 /* These are just conversions since representation clauses for
1615 enumeration types are handled in the front-end. */
1616 {
1622 }
1627 /* These just add or subtract the constant 1 since representation
1628 clauses for enumeration types are handled in the front-end. */
1633 {
1635 gnu_expr
1636 = emit_check
1638 gnu_expr,
1639 attribute == Attr_Pred
1643 }
1645 gnu_result
1653 /* Conversions don't change addresses but can cause us to miss the
1654 COMPONENT_REF case below, so strip them off. */
1658 /* If we are taking 'Address of an unconstrained object, this is the
1659 pointer to the underlying array. */
1663 /* If we are building a static dispatch table, we have to honor
1664 TARGET_VTABLE_USES_DESCRIPTORS if we want to be compatible
1665 with the C++ ABI. We do it in the non-static case as well,
1666 see gnat_to_gnu_entity, case E_Access_Subprogram_Type. */
1669 {
1671 /* Descriptors can only be built here for top-level functions. */
1679 /* If we're not going to build the descriptor, we have to retrieve
1680 the one which will be built by the linker (or by the compiler
1681 later if a static chain is requested). */
1683 {
1686 gnu_result);
1688 }
1695 {
1697 {
1701 }
1702 else
1708 elt--;
1709 }
1713 }
1715 /* ... fall through ... */
1721 gnu_result
1728 /* For 'Code_Address, find an inner ADDR_EXPR and mark it so that we
1729 don't try to build a trampoline. */
1731 {
1736 }
1738 /* For 'Access, issue an error message if the prefix is a C++ method
1739 since it can use a special calling convention on some platforms,
1740 which cannot be propagated to the access type. */
1745 gnat_node);
1747 /* For other address attributes applied to a nested function,
1748 find an inner ADDR_EXPR and annotate it so that we can issue
1749 a useful warning with -Wtrampolines. */
1751 {
1756 {
1759 /* Also check the inlining status. */
1762 /* Check that we're not violating the No_Implicit_Dynamic_Code
1763 restriction. Be conservative if we don't know anything
1764 about the trampoline strategy for the target. */
1766 }
1767 }
1771 {
1773 tree gnu_obj_type;
1777 /* If this is fat pointer, the object must have been allocated with the
1778 template in front of the array. So compute the template address; do
1779 it by converting to a thin pointer. */
1781 gnu_ptr
1783 (TYPE_OBJECT_RECORD_TYPE
1785 gnu_ptr);
1789 /* If this is a thin pointer, the object must have been allocated with
1790 the template in front of the array. So compute the template address
1791 and return it. */
1793 gnu_ptr
1795 gnu_ptr,
1797 byte_position
1798 (DECL_CHAIN
1802 }
1811 /* Remove NOPs and conversions between original and packable version
1812 from GNU_EXPR, and conversions from GNU_PREFIX. We use GNU_EXPR
1813 to see if a COMPONENT_REF was involved. */
1818 == RECORD_TYPE
1827 /* Replace an unconstrained array type with the type of the underlying
1828 array. We can't do this with a call to maybe_unconstrained_array
1829 since we may have a TYPE_DECL. For 'Max_Size_In_Storage_Elements,
1830 use the record type that will be used to allocate the object and its
1831 template. */
1833 {
1837 }
1839 /* If we're looking for the size of a field, return the field size. */
1843 /* Otherwise, if the prefix is an object, or if we are looking for
1844 'Object_Size or 'Max_Size_In_Storage_Elements, the result is the
1845 GCC size of the type. We make an exception for padded objects,
1846 as we do not take into account alignment promotions for the size.
1847 This is in keeping with the object case of gnat_to_gnu_entity. */
1853 {
1854 /* If this is a dereference and we have a special dynamic constrained
1855 subtype on the prefix, use it to compute the size; otherwise, use
1856 the designated subtype. */
1858 {
1859 Node_Id gnat_actual_subtype
1861 tree gnu_ptr_type
1866 {
1867 tree gnu_actual_obj_type
1869 gnu_type
1871 gnu_actual_obj_type,
1874 }
1875 }
1878 }
1880 /* Otherwise, the result is the RM size of the type. */
1881 else
1884 /* Deal with a self-referential size by returning the maximum size for
1885 a type and by qualifying the size with the object otherwise. */
1887 {
1890 else
1892 }
1894 /* If the type contains a template, subtract its size. */
1900 /* For 'Max_Size_In_Storage_Elements, adjust the unit. */
1908 {
1921 else
1922 {
1927 /* If the default alignment of "double" or larger scalar types is
1928 specifically capped and there is an alignment clause neither
1929 on the type nor on the prefix itself, return the cap. */
1931 is_capped_double
1934 is_capped_double
1936 else
1946 else
1948 }
1951 }
1960 {
1967 else
1970 }
1972 /* ... fall through ... */
1975 {
1983 /* Make sure any implicit dereference gets done. */
1987 /* We treat unconstrained array In parameters specially. We also note
1988 whether we are dereferencing a pointer to unconstrained array. */
1991 {
1993 /* This is the direct case. */
1999 /* This is the indirect case. Note that we need to be sure that
2000 the access value cannot be null as we'll hoist the load. */
2003 {
2006 }
2007 else
2013 }
2015 /* If the prefix is the view conversion of a constrained array to an
2016 unconstrained form, we retrieve the constrained array because we
2017 might not be able to substitute the PLACEHOLDER_EXPR coming from
2018 the conversion. This can occur with the 'Old attribute applied
2019 to a parameter with an unconstrained type, which gets rewritten
2020 into a constrained local variable very late in the game. */
2023 && !CONTAINS_PLACEHOLDER_P
2026 else
2033 {
2035 tree gnu_type_temp;
2041 ;
2044 }
2051 /* When not optimizing, look up the slot associated with the parameter
2052 and the dimension in the cache and create a new one on failure.
2053 Don't do this when the actual subtype needs debug info (this happens
2054 with -gnatD): in elaborate_expression_1, we create variables that
2055 hold the bounds, so caching attributes isn't very interesting and
2056 causes dependency issues between these variables and cached
2057 expressions. */
2062 {
2068 {
2073 }
2074 }
2076 /* Return the cached expression or build a new one. */
2078 {
2080 {
2083 }
2085 gnu_result
2087 }
2090 {
2092 {
2095 }
2097 gnu_result
2099 }
2102 {
2104 {
2107 }
2109 gnu_result
2111 gnu_result_type);
2112 }
2114 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2115 handling. Note that these attributes could not have been used on
2116 an unconstrained array type. */
2119 /* Cache the expression we have just computed. Since we want to do it
2120 at run time, we force the use of a SAVE_EXPR and let the gimplifier
2121 create the temporary in the outermost binding level. We will make
2122 sure in Subprogram_Body_to_gnu that it is evaluated on all possible
2123 paths by forcing its evaluation on entry of the function. */
2125 {
2126 gnu_result
2129 {
2145 }
2146 }
2148 /* Otherwise, evaluate it each time it is referenced. */
2149 else
2151 {
2154 /* If we are dereferencing a pointer to unconstrained array, we
2155 need to capture the value because the pointed-to bounds may
2156 subsequently be released. */
2158 gnu_result
2164 /* Set the source location onto the predicate of the condition
2165 but not if the expression is cached to avoid messing up the
2166 debug info. */
2170 gnat_node);
2175 }
2178 }
2185 {
2186 HOST_WIDE_INT bitsize;
2187 HOST_WIDE_INT bitpos;
2188 tree gnu_offset;
2189 tree gnu_field_bitpos;
2190 tree gnu_field_offset;
2191 tree gnu_inner;
2192 machine_mode mode;
2199 /* We can have 'Bit on any object, but if it isn't a COMPONENT_REF,
2200 the result is 0. Don't allow 'Bit on a bare component, though. */
2204 {
2207 }
2209 else
2218 {
2226 {
2227 gnu_field_bitpos
2230 gnu_field_offset
2233 }
2234 }
2236 {
2239 }
2240 else
2241 {
2244 }
2247 {
2261 /* ??? Avoid a large unsigned result that will overflow when
2262 converted to the signed universal_integer. */
2265 else
2266 gnu_result
2273 }
2275 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2276 handling. */
2279 }
2283 {
2289 /* The result of {MIN,MAX}_EXPR is unspecified if either operand is
2290 a NaN so we implement the semantics of C99 f{min,max} to make it
2291 predictable in this case: if either operand is a NaN, the other
2292 is returned; if both operands are NaN's, a NaN is returned. */
2294 {
2300 /* If the operands have side-effects, they need to be evaluated
2301 only once in spite of the multiple references in the result. */
2309 integer_zero_node);
2313 integer_zero_node);
2323 /* If the operands have side-effects, they need to be evaluated
2324 before doing the tests above since the place they otherwise
2325 would end up being evaluated at run time could be wrong. */
2327 gnu_result
2331 gnu_result
2333 }
2334 else
2338 }
2364 /* Note this size cannot be self-referential. */
2374 /* What we want is the offset of the ARRAY field in the record
2375 that the thin pointer designates. */
2383 /* This is just a zero cast to the pointer type for our prefix and
2384 dereferenced. */
2386 gnu_result
2389 integer_zero_node));
2394 {
2401 {
2406 ;
2407 }
2415 && (DECL_BY_COMPONENT_PTR_P
2419 }
2423 /* We treat Model as identical to Machine. This is true for at least
2424 IEEE and some other nice floating-point systems. */
2426 /* ... fall through ... */
2429 /* The trick is to force the compiler to store the result in memory so
2430 that we do not have extra precision used. But do this only when this
2431 is necessary, i.e. if FP_ARITH_MAY_WIDEN is true and the precision of
2432 the type is lower than that of the longest floating-point type. */
2441 {
2443 tree field
2453 asm_expr
2465 gnu_result
2469 }
2476 /* This can be a random address so build an alias-all pointer type. */
2477 gnu_expr
2480 gnu_expr);
2485 /* This abort means that we have an unimplemented attribute. */
2487 }
2489 /* If this is an attribute where the prefix was unused, force a use of it if
2490 it has a side-effect. But don't do it if the prefix is just an entity
2491 name. However, if an access check is needed, we must do it. See second
2492 example in AARM 11.6(5.e). */
2496 gnu_result
2501 }
2502 \f
2503 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Case_Statement,
2504 to a GCC tree, which is returned. */
2506 static tree
2508 {
2510 Node_Id gnat_when;
2511 location_t end_locus;
2517 /* The range of values in a case statement is determined by the rules in
2518 RM 5.4(7-9). In almost all cases, this range is represented by the Etype
2519 of the expression. One exception arises in the case of a simple name that
2520 is parenthesized. This still has the Etype of the name, but since it is
2521 not a name, para 7 does not apply, and we need to go to the base type.
2522 This is the only case where parenthesization affects the dynamic
2523 semantics (i.e. the range of possible values at run time that is covered
2524 by the others alternative).
2526 Another exception is if the subtype of the expression is non-static. In
2527 that case, we also have to use the base type. */
2533 /* We build a SWITCH_EXPR that contains the code with interspersed
2534 CASE_LABEL_EXPRs for each label. */
2543 {
2545 Node_Id gnat_choice;
2547 /* First compile all the different case choices for the current WHEN
2548 alternative. */
2552 {
2557 {
2572 /* This represents either a subtype range or a static value of
2573 some kind; Ekind says which. */
2575 {
2581 }
2583 /* ... fall through ... */
2595 }
2597 /* Everything should be folded into constants at this point. */
2602 gnat_choice);
2604 }
2606 /* This construct doesn't define a scope so we shouldn't push a binding
2607 level around the statement list. Except that we have always done so
2608 historically and this makes it possible to reduce stack usage. As a
2609 compromise, we keep doing it for case statements, for which this has
2610 never been problematic, but not for case expressions in Ada 2012. */
2612 {
2613 const bool is_case_expression
2615 tree group
2620 {
2625 }
2626 }
2627 }
2629 /* Now emit a definition of the label the cases branch to, if any. */
2636 }
2637 \f
2638 /* Find out whether VAR is an iteration variable of an enclosing loop in the
2639 current function. If so, push a range_check_info structure onto the stack
2640 of this enclosing loop and return it. Otherwise, return NULL. */
2644 {
2660 i--)
2665 {
2669 }
2672 }
2674 /* Return true if VAL (of type TYPE) can equal the minimum value if MAX is
2675 false, or the maximum value if MAX is true, of TYPE. */
2677 static bool
2679 {
2686 val = (max
2695 else
2697 }
2699 /* Return true if VAL (of type TYPE) can equal the minimum value of TYPE.
2700 If REVERSE is true, minimum value is taken as maximum value. */
2704 {
2706 }
2708 /* Return true if VAL (of type TYPE) can equal the maximum value of TYPE.
2709 If REVERSE is true, maximum value is taken as minimum value. */
2713 {
2715 }
2717 /* Return true if VAL1 can be lower than VAL2. */
2719 static bool
2721 {
2735 }
2737 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Loop_Statement,
2738 to a GCC tree, which is returned. */
2740 static tree
2742 {
2749 tree gnu_result;
2751 /* Push the loop_info structure associated with the LOOP_STMT. */
2754 /* Set location information for statement and end label. */
2760 /* Save the statement for later reuse. */
2763 /* Set the condition under which the loop must keep going.
2764 For the case "LOOP .... END LOOP;" the condition is always true. */
2766 ;
2768 /* For the case "WHILE condition LOOP ..... END LOOP;" it's immediate. */
2773 /* Otherwise we have an iteration scheme and the condition is given by the
2774 bounds of the subtype of the iteration variable. */
2775 else
2776 {
2790 /* We must disable modulo reduction for the iteration variable, if any,
2791 in order for the loop comparison to be effective. */
2793 {
2799 }
2800 else
2801 {
2807 }
2809 /* We use two different strategies to translate the loop, depending on
2810 whether optimization is enabled.
2812 If it is, we generate the canonical loop form expected by the loop
2813 optimizer and the loop vectorizer, which is the do-while form:
2815 ENTRY_COND
2816 loop:
2817 TOP_UPDATE
2818 BODY
2819 BOTTOM_COND
2820 GOTO loop
2822 This avoids an implicit dependency on loop header copying and makes
2823 it possible to turn BOTTOM_COND into an inequality test.
2825 If optimization is disabled, loop header copying doesn't come into
2826 play and we try to generate the loop form with the fewer conditional
2827 branches. First, the default form, which is:
2829 loop:
2830 TOP_COND
2831 BODY
2832 BOTTOM_UPDATE
2833 GOTO loop
2835 It should catch most loops with constant ending point. Then, if we
2836 cannot, we try to generate the shifted form:
2838 loop:
2839 TOP_COND
2840 TOP_UPDATE
2841 BODY
2842 GOTO loop
2844 which should catch loops with constant starting point. Otherwise, if
2845 we cannot, we generate the fallback form:
2847 ENTRY_COND
2848 loop:
2849 BODY
2850 BOTTOM_COND
2851 BOTTOM_UPDATE
2852 GOTO loop
2854 which works in all cases. */
2857 {
2858 /* We can use the do-while form directly if GNU_FIRST-1 doesn't
2859 overflow. */
2861 ;
2863 /* Otherwise, use the do-while form with the help of a special
2864 induction variable in the unsigned version of the base type
2865 or the unsigned version of the size type, whichever is the
2866 largest, in order to have wrap-around arithmetics for it. */
2867 else
2868 {
2871 gnu_base_type
2873 else
2880 }
2882 gnu_first
2884 gnu_one_node);
2887 }
2888 else
2889 {
2890 /* We can use the default form if GNU_LAST+1 doesn't overflow. */
2892 ;
2894 /* Otherwise, we can use the shifted form if neither GNU_FIRST-1 nor
2895 GNU_LAST-1 does. */
2898 {
2899 gnu_first
2901 gnu_one_node);
2902 gnu_last
2904 gnu_one_node);
2906 }
2908 /* Otherwise, use the fallback form. */
2909 else
2911 }
2913 /* If we use the BOTTOM_COND, we can turn the test into an inequality
2914 test but we may have to add ENTRY_COND to protect the empty loop. */
2916 {
2919 {
2920 gnu_cond_expr
2926 }
2927 }
2929 /* Open a new nesting level that will surround the loop to declare the
2930 iteration variable. */
2934 /* If we use the special induction variable, create it and set it to
2935 its initial value. Morever, the regular iteration variable cannot
2936 itself be initialized, lest the initial value wrapped around. */
2938 {
2939 gnu_loop_iv
2943 }
2944 else
2947 /* Declare the iteration variable and set it to its initial value. */
2952 {
2955 }
2958 /* Do all the arithmetics in the base type. */
2961 /* Set either the top or bottom exit condition. */
2965 gnu_last);
2966 else
2969 gnu_last);
2971 /* Set either the top or bottom update statement and give it the source
2972 location of the iteration for better coverage info. */
2974 {
2975 gnu_stmt
2982 gnu_stmt
2984 gnu_loop_iv);
2988 }
2989 else
2990 {
2991 gnu_stmt
2997 }
2998 }
3000 /* If the loop was named, have the name point to this loop. In this case,
3001 the association is not a DECL node, but the end label of the loop. */
3005 /* Make the loop body into its own block, so any allocated storage will be
3006 released every iteration. This is needed for stack allocation. */
3011 /* If we have an iteration scheme, then we are in a statement group. Add
3012 the LOOP_STMT to it, finish it and make it the "loop". */
3014 {
3019 /* First, if we have computed a small number of invariant conditions for
3020 range checks applied to the iteration variable, then initialize these
3021 conditions in front of the loop. Otherwise, leave them set to true.
3023 ??? The heuristics need to be improved, by taking into account the
3024 following datapoints:
3025 - loop unswitching is disabled for big loops. The cap is the
3026 parameter PARAM_MAX_UNSWITCH_INSNS (50).
3027 - loop unswitching can only be applied a small number of times
3028 to a given loop. The cap is PARAM_MAX_UNSWITCH_LEVEL (3).
3029 - the front-end quickly generates useless or redundant checks
3030 that can be entirely optimized away in the end. */
3034 i++)
3035 {
3036 tree low_ok
3043 tree high_ok
3050 tree range_ok
3058 }
3063 }
3065 /* If we have an outer COND_EXPR, that's our result and this loop is its
3066 "true" statement. Otherwise, the result is the LOOP_STMT. */
3068 {
3072 }
3073 else
3079 }
3080 \f
3081 /* This page implements a form of Named Return Value optimization modelled
3082 on the C++ optimization of the same name. The main difference is that
3083 we disregard any semantical considerations when applying it here, the
3084 counterpart being that we don't try to apply it to semantically loaded
3085 return types, i.e. types with the TYPE_BY_REFERENCE_P flag set.
3087 We consider a function body of the following GENERIC form:
3089 return_type R1;
3090 [...]
3091 RETURN_EXPR [<retval> = ...]
3092 [...]
3093 RETURN_EXPR [<retval> = R1]
3094 [...]
3095 return_type Ri;
3096 [...]
3097 RETURN_EXPR [<retval> = ...]
3098 [...]
3099 RETURN_EXPR [<retval> = Ri]
3100 [...]
3102 and we try to fulfill a simple criterion that would make it possible to
3103 replace one or several Ri variables with the RESULT_DECL of the function.
3105 The first observation is that RETURN_EXPRs that don't directly reference
3106 any of the Ri variables on the RHS of their assignment are transparent wrt
3107 the optimization. This is because the Ri variables aren't addressable so
3108 any transformation applied to them doesn't affect the RHS; moreover, the
3109 assignment writes the full <retval> object so existing values are entirely
3110 discarded.
3112 This property can be extended to some forms of RETURN_EXPRs that reference
3113 the Ri variables, for example CONSTRUCTORs, but isn't true in the general
3114 case, in particular when function calls are involved.
3116 Therefore the algorithm is as follows:
3118 1. Collect the list of candidates for a Named Return Value (Ri variables
3119 on the RHS of assignments of RETURN_EXPRs) as well as the list of the
3120 other expressions on the RHS of such assignments.
3122 2. Prune the members of the first list (candidates) that are referenced
3123 by a member of the second list (expressions).
3125 3. Extract a set of candidates with non-overlapping live ranges from the
3126 first list. These are the Named Return Values.
3128 4. Adjust the relevant RETURN_EXPRs and replace the occurrences of the
3129 Named Return Values in the function with the RESULT_DECL.
3131 If the function returns an unconstrained type, things are a bit different
3132 because the anonymous return object is allocated on the secondary stack
3133 and RESULT_DECL is only a pointer to it. Each return object can be of a
3134 different size and is allocated separately so we need not care about the
3135 aforementioned overlapping issues. Therefore, we don't collect the other
3136 expressions and skip step #2 in the algorithm. */
3138 struct nrv_data
3139 {
3140 bitmap nrv;
3141 tree result;
3142 Node_Id gnat_ret;
3144 };
3146 /* Return true if T is a Named Return Value. */
3150 {
3152 }
3154 /* Helper function for walk_tree, used by finalize_nrv below. */
3156 static tree
3158 {
3162 /* No need to walk into types or decls. */
3170 }
3172 /* Prune Named Return Values in BLOCK and return true if there is still a
3173 Named Return Value in BLOCK or one of its sub-blocks. */
3175 static bool
3177 {
3179 tree t;
3181 /* First recurse on the sub-blocks. */
3185 /* Then make sure to keep at most one NRV per block. */
3188 {
3191 else
3193 }
3196 }
3198 /* Helper function for walk_tree, used by finalize_nrv below. */
3200 static tree
3202 {
3206 /* No need to walk into types. */
3210 /* Change RETURN_EXPRs of NRVs to just refer to the RESULT_DECL; this is a
3211 nop, but differs from using NULL_TREE in that it indicates that we care
3212 about the value of the RESULT_DECL. */
3215 {
3218 /* If this is the temporary created for a return value with variable
3219 size in Call_to_gnu, we replace the RHS with the init expression. */
3224 {
3227 }
3228 else
3231 /* Strip useless conversions around the return value. */
3236 {
3239 else
3241 }
3242 }
3244 /* Replace the DECL_EXPR of NRVs with an initialization of the RESULT_DECL,
3245 if needed. */
3248 {
3252 {
3257 }
3258 else
3262 /* Identify the NRV to the RESULT_DECL for debugging purposes. */
3265 /* ??? Kludge to avoid an assertion failure during inlining. */
3268 }
3270 /* And replace all uses of NRVs with the RESULT_DECL. */
3274 /* Avoid walking into the same tree more than once. Unfortunately, we
3275 can't just use walk_tree_without_duplicates because it would only
3276 call us for the first occurrence of NRVs in the function body. */
3281 }
3283 /* Likewise, but used when the function returns an unconstrained type. */
3285 static tree
3287 {
3291 /* No need to walk into types. */
3295 /* We need to see the DECL_EXPR of NRVs before any other references so we
3296 walk the body of BIND_EXPR before walking its variables. */
3300 /* Change RETURN_EXPRs of NRVs to assign to the RESULT_DECL only the final
3301 return value built by the allocator instead of the whole construct. */
3304 {
3307 /* This is the construct returned by the allocator. */
3310 {
3312 ret_val
3315 else
3317 }
3319 /* Strip useless conversions around the return value. */
3324 /* Strip unpadding around the return value. */
3329 /* Assign the new return value to the RESULT_DECL. */
3333 }
3335 /* Adjust the DECL_EXPR of NRVs to call the allocator and save the result
3336 into a new variable. */
3339 {
3346 /* Create an artificial context to build the allocation. */
3351 /* This will return a COMPOUND_EXPR with the allocation in the first
3352 arm and the final return value in the second arm. */
3359 /* The new variable is built as a reference to the allocated space. */
3360 new_var
3366 {
3367 /* The new initial value is a COMPOUND_EXPR with the allocation in
3368 the first arm and the value of P_ARRAY in the second arm. */
3374 /* Build a modified CONSTRUCTOR that references NEW_VAR. */
3382 }
3383 else
3384 {
3385 /* The new initial value is just the allocation. */
3388 }
3392 /* Destroy the artificial context and insert the new statements. */
3397 /* Chain NEW_VAR immediately after VAR and ignore the latter. */
3402 /* Save the new return value and the dereference of NEW_VAR. */
3406 /* ??? Kludge to avoid messing up during inlining. */
3408 }
3410 /* And replace all uses of NRVs with the dereference of NEW_VAR. */
3414 /* Avoid walking into the same tree more than once. Unfortunately, we
3415 can't just use walk_tree_without_duplicates because it would only
3416 call us for the first occurrence of NRVs in the function body. */
3421 }
3423 /* Finalize the Named Return Value optimization for FNDECL. The NRV bitmap
3424 contains the candidates for Named Return Value and OTHER is a list of
3425 the other return values. GNAT_RET is a representative return node. */
3427 static void
3429 {
3432 walk_tree_fn func;
3434 tree iter;
3436 /* We shouldn't be applying the optimization to return types that we aren't
3437 allowed to manipulate freely. */
3440 /* Prune the candidates that are referenced by other return values. */
3449 /* Prune also the candidates that are referenced by nested functions. */
3457 /* Extract a set of NRVs with non-overlapping live ranges. */
3461 /* Adjust the relevant RETURN_EXPRs and replace the occurrences of NRVs. */
3468 else
3472 }
3474 /* Return true if RET_VAL can be used as a Named Return Value for the
3475 anonymous return object RET_OBJ. */
3477 static bool
3479 {
3499 }
3501 /* Build a RETURN_EXPR. If RET_VAL is non-null, build a RETURN_EXPR around
3502 the assignment of RET_VAL to RET_OBJ. Otherwise build a bare RETURN_EXPR
3503 around RESULT_OBJ, which may be null in this case. */
3505 static tree
3507 {
3508 tree result_expr;
3511 {
3512 /* The gimplifier explicitly enforces the following invariant:
3514 RETURN_EXPR
3515 |
3516 INIT_EXPR
3517 / \
3518 / \
3519 RET_OBJ ...
3521 As a consequence, type consistency dictates that we use the type
3522 of the RET_OBJ as the operation type. */
3525 /* Convert the right operand to the operation type. Note that this is
3526 the transformation applied in the INIT_EXPR case of build_binary_op,
3527 with the assumption that the type cannot involve a placeholder. */
3531 /* We always can use an INIT_EXPR for the return object. */
3534 /* If the function returns an aggregate type, find out whether this is
3535 a candidate for Named Return Value. If so, record it. Otherwise,
3536 if this is an expression of some kind, record it elsewhere. */
3542 {
3543 /* Recognize the temporary created for a return value with variable
3544 size in Call_to_gnu. We want to eliminate it if possible. */
3551 /* Strip useless conversions around the return value. */
3555 /* Now apply the test to the return value. */
3557 {
3561 }
3563 /* Note that we need not care about CONSTRUCTORs here, as they are
3564 totally transparent given the read-compose-write semantics of
3565 assignments from CONSTRUCTORs. */
3568 }
3569 }
3570 else
3574 }
3575 \f
3576 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Subprogram_Body. We
3577 don't return anything. */
3579 static void
3581 {
3582 /* Defining identifier of a parameter to the subprogram. */
3583 Entity_Id gnat_param;
3584 /* The defining identifier for the subprogram body. Note that if a
3585 specification has appeared before for this body, then the identifier
3586 occurring in that specification will also be a defining identifier and all
3587 the calls to this subprogram will point to that specification. */
3588 Entity_Id gnat_subprog_id
3591 /* The FUNCTION_DECL node corresponding to the subprogram spec. */
3592 tree gnu_subprog_decl;
3593 /* Its RESULT_DECL node. */
3594 tree gnu_result_decl;
3595 /* Its FUNCTION_TYPE node. */
3596 tree gnu_subprog_type;
3597 /* The TYPE_CI_CO_LIST of its FUNCTION_TYPE node, if any. */
3598 tree gnu_cico_list;
3599 /* The entry in the CI_CO_LIST that represents a function return, if any. */
3601 tree gnu_result;
3602 location_t locus;
3606 /* If this is a generic object or if it has been eliminated,
3607 ignore it. */
3613 /* If this subprogram acts as its own spec, define it. Otherwise, just get
3614 the already-elaborated tree node. However, if this subprogram had its
3615 elaboration deferred, we will already have made a tree node for it. So
3616 treat it as not being defined in that case. Such a subprogram cannot
3617 have an address clause or a freeze node, so this test is safe, though it
3618 does disable some otherwise-useful error checking. */
3619 gnu_subprog_decl
3629 /* If the function returns by invisible reference, make it explicit in the
3630 function body. See gnat_to_gnu_entity, E_Subprogram_Type case. */
3632 {
3636 }
3638 /* Set the line number in the decl to correspond to that of the body. */
3642 /* Initialize the information structure for the function. */
3651 /* If there are copy-in/copy-out parameters, we need to ensure that they are
3652 properly copied out by the return statement. We do this by making a new
3653 block and converting any return into a goto to a label at the end of the
3654 block. */
3656 {
3665 /* If this is a function with copy-in/copy-out parameters and which does
3666 not return by invisible reference, we also need a variable for the
3667 return value to be placed. */
3669 {
3670 tree gnu_return_type
3673 gnu_return_var
3678 }
3682 /* See whether there are parameters for which we don't have a GCC tree
3683 yet. These must be Out parameters. Make a VAR_DECL for them and
3684 put it into TYPE_CI_CO_LIST, which must contain an empty entry too.
3685 We can match up the entries because TYPE_CI_CO_LIST is in the order
3686 of the parameters. */
3691 {
3693 tree gnu_decl;
3695 /* Skip any entries that have been already filled in; they must
3696 correspond to In Out parameters. */
3700 /* Do any needed dereferences for by-ref objects. */
3706 /* Do any needed references for padded types. */
3709 }
3710 }
3711 else
3714 /* Get a tree corresponding to the code for the subprogram. */
3720 /* Generate the code of the subprogram itself. A return statement will be
3721 present and any Out parameters will be handled there. */
3726 /* If we populated the parameter attributes cache, we need to make sure that
3727 the cached expressions are evaluated on all the possible paths leading to
3728 their uses. So we force their evaluation on entry of the function. */
3731 {
3738 {
3745 }
3751 }
3753 /* If we are dealing with a return from an Ada procedure with parameters
3754 passed by copy-in/copy-out, we need to return a record containing the
3755 final values of these parameters. If the list contains only one entry,
3756 return just that entry though.
3758 For a full description of the copy-in/copy-out parameter mechanism, see
3759 the part of the gnat_to_gnu_entity routine dealing with the translation
3760 of subprograms.
3762 We need to make a block that contains the definition of that label and
3763 the copying of the return value. It first contains the function, then
3764 the label and copy statement. */
3766 {
3767 const Node_Id gnat_end_label
3776 /* If this is a function which returns by invisible reference, the
3777 return value has already been dealt with at the return statements,
3778 so we only need to indirectly copy out the parameters. */
3780 {
3781 tree gnu_ret_deref
3783 tree t;
3788 {
3789 tree gnu_field_deref
3795 }
3796 }
3798 /* Otherwise, if this is a procedure or a function which does not return
3799 by invisible reference, we can do a direct block-copy out. */
3800 else
3801 {
3802 tree gnu_retval;
3806 else
3807 gnu_retval
3809 gnu_cico_list);
3813 }
3817 }
3821 /* Attempt setting the end_locus of our GCC body tree, typically a
3822 BIND_EXPR or STATEMENT_LIST, then the end_locus of our GCC subprogram
3823 declaration tree. */
3827 /* On SEH targets, install an exception handler around the main entry
3828 point to catch unhandled exceptions. */
3831 {
3832 tree t;
3833 tree etype;
3845 }
3849 /* Finally annotate the parameters and disconnect the trees for parameters
3850 that we have turned into variables since they are now unusable. */
3854 {
3863 }
3865 /* Disconnect the variable created for the return value. */
3869 /* If the function returns an aggregate type and we have candidates for
3870 a Named Return Value, finalize the optimization. */
3872 {
3879 }
3881 /* If this is an inlined external function that has been marked uninlinable,
3882 drop the body and stop there. Otherwise compile the body. */
3885 else
3887 }
3888 \f
3889 /* Return true if GNAT_NODE requires atomic synchronization. */
3891 static bool
3893 {
3895 Node_Kind kind;
3898 /* First, scan the node to find the Atomic_Sync_Required flag. */
3901 {
3904 }
3907 {
3919 }
3921 /* Then, scan the parent to find out cases where the flag is irrelevant. */
3924 {
3927 /* Do not mess up machine code insertions. */
3933 /* Do not generate a function call as a renamed object. */
3938 }
3941 }
3942 \f
3943 /* Create a temporary variable with PREFIX and TYPE, and return it. */
3945 static tree
3947 {
3955 }
3957 /* Create a temporary variable with PREFIX and initialize it with GNU_INIT.
3958 Put the initialization statement into GNU_INIT_STMT and annotate it with
3959 the SLOC of GNAT_NODE. Return the temporary variable. */
3961 static tree
3963 Node_Id gnat_node)
3964 {
3971 }
3973 /* Subroutine of gnat_to_gnu to translate gnat_node, either an N_Function_Call
3974 or an N_Procedure_Call_Statement, to a GCC tree, which is returned.
3975 GNU_RESULT_TYPE_P is a pointer to where we should place the result type.
3976 If GNU_TARGET is non-null, this must be a function call on the RHS of a
3977 N_Assignment_Statement and the result is to be placed into that object.
3978 If, in addition, ATOMIC_SYNC is true, then the assignment to GNU_TARGET
3979 requires atomic synchronization. */
3981 static tree
3984 {
3987 /* The GCC node corresponding to the GNAT subprogram name. This can either
3988 be a FUNCTION_DECL node if we are dealing with a standard subprogram call,
3989 or an indirect reference expression (an INDIRECT_REF node) pointing to a
3990 subprogram. */
3992 /* The FUNCTION_TYPE node giving the GCC type of the subprogram. */
3994 /* The return type of the FUNCTION_TYPE. */
4005 Entity_Id gnat_formal;
4006 Node_Id gnat_actual;
4010 /* If we are calling a stubbed function, raise Program_Error, but Elaborate
4011 all our args first. */
4013 {
4023 {
4026 }
4029 }
4031 /* For a call to a nested function, check the inlining status. */
4036 /* The only way we can be making a call via an access type is if Name is an
4037 explicit dereference. In that case, get the list of formal args from the
4038 type the access type is pointing to. Otherwise, get the formals from the
4039 entity being called. */
4043 /* Assume here that this must be 'Elab_Body or 'Elab_Spec. */
4045 else
4048 /* The lifetime of the temporaries created for the call ends right after the
4049 return value is copied, so we can give them the scope of the elaboration
4050 routine at top level. */
4052 {
4055 }
4057 /* First, create the temporary for the return value when:
4059 1. There is no target and the function has copy-in/copy-out parameters,
4060 because we need to preserve the return value before copying back the
4061 parameters.
4063 2. There is no target and this is not an object declaration, and the
4064 return type has variable size, because in these cases the gimplifier
4065 cannot create the temporary.
4067 3. There is a target and it is a slice or an array with fixed size,
4068 and the return type has variable size, because the gimplifier
4069 doesn't handle these cases.
4071 This must be done before we push a binding level around the call, since
4072 we will pop it before copying the return value. */
4075 || (!gnu_target
4078 || (gnu_target
4086 /* Create the list of the actual parameters as GCC expects it, namely a
4087 chain of TREE_LIST nodes in which the TREE_VALUE field of each node
4088 is an expression and the TREE_PURPOSE field is null. But skip Out
4089 parameters not passed by reference and that need not be copied in. */
4094 {
4099 const bool is_true_formal_parm
4101 const bool is_by_ref_formal_parm
4102 = is_true_formal_parm
4105 /* In the Out or In Out case, we must suppress conversions that yield
4106 an lvalue but can nevertheless cause the creation of a temporary,
4107 because we need the real object in this case, either to pass its
4108 address if it's passed by reference or as target of the back copy
4109 done after the call if it uses the copy-in/copy-out mechanism.
4110 We do it in the In case too, except for an unchecked conversion
4111 to an elementary type or a constrained composite type because it
4112 alone can cause the actual to be misaligned and the addressability
4113 test is applied to the real object. */
4114 const bool suppress_type_conversion
4121 Node_Id gnat_name = suppress_type_conversion
4124 tree gnu_actual;
4126 /* If it's possible we may need to use this expression twice, make sure
4127 that any side-effects are handled via SAVE_EXPRs; likewise if we need
4128 to force side-effects before the call.
4129 ??? This is more conservative than we need since we don't need to do
4130 this for pass-by-ref with no conversion. */
4134 /* If we are passing a non-addressable parameter by reference, pass the
4135 address of a copy. In the Out or In Out case, set up to copy back
4136 out after the call. */
4140 {
4144 /* Do not issue warnings for CONSTRUCTORs since this is not a copy
4145 but sort of an instantiation for them. */
4147 ;
4149 /* If the type is passed by reference, a copy is not allowed. */
4152 gnat_actual);
4154 /* For users of Starlet we issue a warning because the interface
4155 apparently assumes that by-ref parameters outlive the procedure
4156 invocation. The code still will not work as intended, but we
4157 cannot do much better since low-level parts of the back-end
4158 would allocate temporaries at will because of the misalignment
4159 if we did not do so here. */
4161 {
4162 post_error
4164 post_error_ne
4168 gnat_formal);
4169 }
4171 /* If the actual type of the object is already the nominal type,
4172 we have nothing to do, except if the size is self-referential
4173 in which case we'll remove the unpadding below. */
4176 ;
4178 /* Otherwise remove the unpadding from all the objects. */
4180 && TYPE_IS_PADDING_P
4184 /* Otherwise convert to the nominal type of the object if needed.
4185 There are several cases in which we need to make the temporary
4186 using this type instead of the actual type of the object when
4187 they are distinct, because the expectations of the callee would
4188 otherwise not be met:
4189 - if it's a justified modular type,
4190 - if the actual type is a smaller form of it,
4191 - if it's a smaller form of the actual type. */
4195 gnu_name_type)))
4201 /* If this is an In Out or Out parameter and we're returning a value,
4202 we need to create a temporary for the return value because we must
4203 preserve it before copying back at the very end. */
4207 /* If we haven't pushed a binding level, push a new one. This will
4208 narrow the lifetime of the temporary we are about to make as much
4209 as possible. The drawback is that we'd need to create a temporary
4210 for the return value, if any (see comment before the loop). So do
4211 it only when this temporary was already created just above. */
4213 {
4217 }
4219 /* Create an explicit temporary holding the copy. */
4220 gnu_temp
4223 /* But initialize it on the fly like for an implicit temporary as
4224 we aren't necessarily having a statement list. */
4226 gnu_temp);
4228 /* Set up to move the copy back to the original if needed. */
4230 {
4231 /* If the original is a COND_EXPR whose first arm isn't meant to
4232 be further used, just deal with the second arm. This is very
4233 likely the conditional expression built for a check. */
4236 && integer_zerop
4240 gnu_stmt
4245 }
4246 }
4248 /* Start from the real object and build the actual. */
4251 /* If this is an atomic access of an In or In Out parameter for which
4252 synchronization is required, build the atomic load. */
4254 && !is_by_ref_formal_parm
4259 /* If this was a procedure call, we may not have removed any padding.
4260 So do it here for the part we will use as an input, if any. */
4263 gnu_actual
4266 /* Put back the conversion we suppressed above in the computation of the
4267 real object. And even if we didn't suppress any conversion there, we
4268 may have suppressed a conversion to the Etype of the actual earlier,
4269 since the parent is a procedure call, so put it back here. */
4272 gnu_actual
4275 else
4276 gnu_actual
4279 /* Make sure that the actual is in range of the formal's type. */
4282 gnu_actual
4285 /* Unless this is an In parameter, we must remove any justified modular
4286 building from GNU_NAME to get an lvalue. */
4291 gnu_name
4294 /* First see if the parameter is passed by reference. */
4296 {
4298 {
4299 /* In Out or Out parameters passed by reference don't use the
4300 copy-in/copy-out mechanism so the address of the real object
4301 must be passed to the function. */
4304 /* If we have a padded type, be sure we've removed padding. */
4307 gnu_actual);
4309 /* If we have the constructed subtype of an aliased object
4310 with an unconstrained nominal subtype, the type of the
4311 actual includes the template, although it is formally
4312 constrained. So we need to convert it back to the real
4313 constructed subtype to retrieve the constrained part
4314 and takes its address. */
4320 gnu_actual);
4321 }
4323 /* There is no need to convert the actual to the formal's type before
4324 taking its address. The only exception is for unconstrained array
4325 types because of the way we build fat pointers. */
4327 {
4328 /* Put back a view conversion for In Out or Out parameters. */
4331 gnu_actual);
4333 }
4335 /* The symmetry of the paths to the type of an entity is broken here
4336 since arguments don't know that they will be passed by ref. */
4339 }
4341 /* Then see if the parameter is an array passed to a foreign convention
4342 subprogram. */
4344 {
4350 {
4353 }
4355 /* Take the address of the object and convert to the proper pointer
4356 type. We'd like to actually compute the address of the beginning
4357 of the array using an ADDR_EXPR of an ARRAY_REF, but there's a
4358 possibility that the ARRAY_REF might return a constant and we'd be
4359 getting the wrong address. Neither approach is exactly correct,
4360 but this is the most likely to work in all cases. */
4362 }
4364 /* Otherwise the parameter is passed by copy. */
4365 else
4366 {
4367 tree gnu_size;
4372 /* If we didn't create a PARM_DECL for the formal, this means that
4373 it is an Out parameter not passed by reference and that need not
4374 be copied in. In this case, the value of the actual need not be
4375 read. However, we still need to make sure that its side-effects
4376 are evaluated before the call, so we evaluate its address. */
4378 {
4380 {
4383 }
4385 }
4389 /* If this is 'Null_Parameter, pass a zero even though we are
4390 dereferencing it. */
4396 gnu_actual
4400 integer_zero_node),
4402 else
4404 }
4407 }
4409 gnu_call
4413 /* If we have created a temporary for the return value, initialize it. */
4415 {
4416 tree gnu_stmt
4421 }
4423 /* If this is a subprogram with copy-in/copy-out parameters, we need to
4424 unpack the valued returned from the function into the In Out or Out
4425 parameters. We deal with the function return (if this is an Ada
4426 function) below. */
4428 {
4429 /* List of FIELD_DECLs associated with the PARM_DECLs of the copy-in/
4430 copy-out parameters. */
4434 /* The call sequence must contain one and only one call, even though the
4435 function is pure. Save the result into a temporary if needed. */
4437 {
4439 {
4440 tree gnu_stmt;
4441 /* If we haven't pushed a binding level, push a new one. This
4442 will narrow the lifetime of the temporary we are about to
4443 make as much as possible. */
4445 {
4449 }
4450 gnu_call
4453 }
4456 }
4458 /* The first entry is for the actual return value if this is a
4459 function, so skip it. */
4465 else
4472 /* If we are dealing with a copy-in/copy-out parameter, we must
4473 retrieve its value from the record returned in the call. */
4479 {
4480 /* Get the value to assign to this Out or In Out parameter. It is
4481 either the result of the function if there is only a single such
4482 parameter or the appropriate field from the record returned. */
4483 tree gnu_result
4485 ? gnu_call
4489 /* If the actual is a conversion, get the inner expression, which
4490 will be the real destination, and convert the result to the
4491 type of the actual parameter. */
4492 tree gnu_actual
4495 /* If the result is a padded type, remove the padding. */
4497 gnu_result
4499 gnu_result);
4501 /* If the actual is a type conversion, the real target object is
4502 denoted by the inner Expression and we need to convert the
4503 result to the associated type.
4504 We also need to convert our gnu assignment target to this type
4505 if the corresponding GNU_NAME was constructed from the GNAT
4506 conversion node and not from the inner Expression. */
4508 {
4509 gnu_result
4510 = convert_with_check
4518 }
4520 /* Unchecked conversions as actuals for Out parameters are not
4521 allowed in user code because they are not variables, but do
4522 occur in front-end expansions. The associated GNU_NAME is
4523 always obtained from the inner expression in such cases. */
4526 gnu_result,
4528 else
4529 {
4531 gnu_result
4533 gnat_actual);
4538 }
4542 else
4549 }
4550 }
4552 /* If this is a function call, the result is the call expression unless a
4553 target is specified, in which case we copy the result into the target
4554 and return the assignment statement. */
4556 {
4557 /* If this is a function with copy-in/copy-out parameters, extract the
4558 return value from it and update the return type. */
4560 {
4565 }
4567 /* If the function returns an unconstrained array or by direct reference,
4568 we have to dereference the pointer. */
4574 {
4578 /* If range check is needed, emit code to generate it. */
4580 gnu_call
4582 gnat_parent);
4584 /* ??? If the return type has variable size, then force the return
4585 slot optimization as we would not be able to create a temporary.
4586 Likewise if it was unconstrained as we would copy too much data.
4587 That's what has been done historically. */
4590 && CONTAINS_PLACEHOLDER_P
4593 else
4598 else
4599 gnu_call
4603 }
4604 else
4606 }
4608 /* Otherwise, if this is a procedure call statement without copy-in/copy-out
4609 parameters, the result is just the call statement. */
4613 /* Finally, add the copy back statements, if any. */
4619 /* If we have pushed a binding level, pop it and finish up the enclosing
4620 statement group. */
4622 {
4626 }
4628 /* Otherwise, retrieve the statement list, if any. */
4632 /* Otherwise, just return the call expression. */
4633 else
4636 /* If we nevertheless need a value, make a COMPOUND_EXPR to return it.
4637 But first simplify if we have only one statement in the list. */
4639 {
4643 gnu_result
4645 }
4648 }
4649 \f
4650 /* Subroutine of gnat_to_gnu to translate gnat_node, an
4651 N_Handled_Sequence_Of_Statements, to a GCC tree, which is returned. */
4653 static tree
4655 {
4658 /* If just annotating, ignore all EH and cleanups. */
4662 bool setjmp_longjmp
4668 tree gnu_result;
4669 tree gnu_expr;
4670 Node_Id gnat_temp;
4671 /* Node providing the sloc for the cleanup actions. */
4674 gnat_node);
4676 /* The GCC exception handling mechanism can handle both ZCX and SJLJ schemes
4677 and we have our own SJLJ mechanism. To call the GCC mechanism, we call
4678 add_cleanup, and when we leave the binding, end_stmt_group will create
4679 the TRY_FINALLY_EXPR.
4681 ??? The region level calls down there have been specifically put in place
4682 for a ZCX context and currently the order in which things are emitted
4683 (region/handlers) is different from the SJLJ case. Instead of putting
4684 other calls with different conditions at other places for the SJLJ case,
4685 it seems cleaner to reorder things for the SJLJ case and generalize the
4686 condition to make it not ZCX specific.
4688 If there are any exceptions or cleanup processing involved, we need an
4689 outer statement group (for Setjmp_Longjmp) and binding level. */
4691 {
4694 }
4696 /* If using setjmp_longjmp, make the variables for the setjmp buffer and save
4697 area for address of previous buffer. Do this first since we need to have
4698 the setjmp buf known for any decls in this block. */
4700 {
4701 gnu_jmpsave_decl
4703 jmpbuf_ptr_type,
4708 /* The __builtin_setjmp receivers will immediately reinstall it. Now
4709 because of the unstructured form of EH used by setjmp_longjmp, there
4710 might be forward edges going to __builtin_setjmp receivers on which
4711 it is uninitialized, although they will never be actually taken. */
4713 gnu_jmpbuf_decl
4715 jmpbuf_type,
4716 NULL_TREE,
4722 /* When we exit this block, restore the saved value. */
4724 gnat_cleanup_loc_node);
4725 }
4727 /* If we are to call a function when exiting this block, add a cleanup
4728 to the binding level we made above. Note that add_cleanup is FIFO
4729 so we must register this cleanup after the EH cleanup just above. */
4732 gnat_cleanup_loc_node);
4734 /* Now build the tree for the declarations and statements inside this block.
4735 If this is SJLJ, set our jmp_buf as the current buffer. */
4739 {
4742 gnu_jmpbuf_decl));
4745 }
4751 /* Generate code for each statement in the block. */
4759 /* Now generate code for the two exception models, if either is relevant for
4760 this block. */
4762 {
4764 tree gnu_handler;
4766 /* Make a binding level for the exception handling declarations and code
4767 and set up gnu_except_ptr_stack for the handlers to use. */
4778 /* Generate code for each handler. The N_Exception_Handler case does the
4779 real work and returns a COND_EXPR for each handler, which we chain
4780 together here. */
4783 {
4786 /* If this is the first one, set it as the outer one. Otherwise,
4787 point the "else" part of the previous handler to us. Then point
4788 to our "else" part. */
4791 else
4795 }
4797 /* If none of the exception handlers did anything, re-raise but do not
4798 defer abortion. */
4801 set_expr_location_from_node
4807 else
4810 /* End the binding level dedicated to the exception handlers and get the
4811 whole statement group. */
4816 /* If the setjmp returns 1, we restore our incoming longjmp value and
4817 then check the handlers. */
4820 gnu_jmpsave_decl),
4821 gnat_node);
4825 /* This block is now "if (setjmp) ... <handlers> else <block>". */
4827 (build_call_n_expr
4830 gnu_jmpbuf_decl))),
4832 }
4834 {
4835 tree gnu_handlers;
4836 location_t locus;
4838 /* First make a block containing the handlers. */
4846 /* Now make the TRY_CATCH_EXPR for the block. */
4849 /* Set a location. We need to find a unique location for the dispatching
4850 code, otherwise we can get coverage or debugging issues. Try with
4851 the location of the end label. */
4855 else
4856 /* Clear column information so that the exception handler of an
4857 implicit transient block does not incorrectly inherit the slocs
4858 of a decision, which would otherwise confuse control flow based
4859 coverage analysis tools. */
4861 }
4862 else
4865 /* Now close our outer block, if we had to make one. */
4867 {
4871 }
4874 }
4875 \f
4876 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
4877 to a GCC tree, which is returned. This is the variant for Setjmp_Longjmp
4878 exception handling. */
4880 static tree
4882 {
4883 /* Unless this is "Others" or the special "Non-Ada" exception for Ada, make
4884 an "if" statement to select the proper exceptions. For "Others", exclude
4885 exceptions where Handled_By_Others is nonzero unless the All_Others flag
4886 is set. For "Non-ada", accept an exception if "Lang" is 'V'. */
4889 Node_Id gnat_temp;
4893 {
4894 tree this_choice;
4897 {
4900 else
4901 this_choice
4902 = build_binary_op
4904 convert
4906 build_component_ref
4907 (build_unary_op
4912 integer_zero_node);
4913 }
4917 {
4919 tree gnu_expr;
4921 /* Exception may be a renaming. Recover original exception which is
4922 the one elaborated and registered. */
4928 this_choice
4929 = build_binary_op
4934 }
4935 else
4940 }
4943 }
4944 \f
4945 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
4946 to a GCC tree, which is returned. This is the variant for ZCX. */
4948 static tree
4950 {
4953 Node_Id gnat_temp;
4955 /* We build a TREE_LIST of nodes representing what exception types this
4956 handler can catch, with special cases for others and all others cases.
4958 Each exception type is actually identified by a pointer to the exception
4959 id, or to a dummy object for "others" and "all others". */
4962 {
4966 {
4969 }
4972 {
4975 /* Exception may be a renaming. Recover original exception which is
4976 the one elaborated and registered. */
4982 }
4983 else
4986 /* The GCC interface expects NULL to be passed for catch all handlers, so
4987 it would be quite tempting to set gnu_etypes_list to NULL if gnu_etype
4988 is integer_zero_node. It would not work, however, because GCC's
4989 notion of "catch all" is stronger than our notion of "others". Until
4990 we correctly use the cleanup interface as well, doing that would
4991 prevent the "all others" handlers from being seen, because nothing
4992 can be caught beyond a catch all from GCC's point of view. */
4994 }
4999 /* Expand a call to the begin_handler hook at the beginning of the handler,
5000 and arrange for a call to the end_handler hook to occur on every possible
5001 exit path.
5003 The hooks expect a pointer to the low level occurrence. This is required
5004 for our stack management scheme because a raise inside the handler pushes
5005 a new occurrence on top of the stack, which means that this top does not
5006 necessarily match the occurrence this handler was dealing with.
5008 __builtin_eh_pointer references the exception occurrence being
5009 propagated. Upon handler entry, this is the exception for which the
5010 handler is triggered. This might not be the case upon handler exit,
5011 however, as we might have a new occurrence propagated by the handler's
5012 body, and the end_handler hook called as a cleanup in this context.
5014 We use a local variable to retrieve the incoming value at handler entry
5015 time, and reuse it to feed the end_handler hook's argument at exit. */
5017 gnu_current_exc_ptr
5027 gnu_incoming_exc_ptr),
5028 gnat_node);
5030 /* Declare and initialize the choice parameter, if present. */
5032 {
5033 tree gnu_param
5039 gnu_incoming_exc_ptr));
5040 }
5042 /* We don't have an End_Label at hand to set the location of the cleanup
5043 actions, so we use that of the exception handler itself instead. */
5045 gnat_node);
5051 return
5053 }
5054 \f
5055 /* Subroutine of gnat_to_gnu to generate code for an N_Compilation unit. */
5057 static void
5059 {
5064 Entity_Id gnat_entity;
5065 Node_Id gnat_pragma;
5066 /* Make the decl for the elaboration procedure. */
5067 tree gnu_elab_proc_decl
5068 = create_subprog_decl
5071 gnat_unit);
5077 /* Initialize the information structure for the function. */
5086 /* For a body, first process the spec if there is one. */
5092 {
5099 }
5101 /* Then process any pragmas and declarations preceding the unit. */
5110 /* Process the unit itself. */
5113 /* Generate code for all the inlined subprograms. */
5117 {
5118 Node_Id gnat_body;
5120 /* Without optimization, process only the required subprograms. */
5126 {
5127 /* ??? This happens when only the spec of a package is provided. */
5131 gnat_body
5133 }
5135 /* Define the entity first so we set DECL_EXTERNAL. */
5138 }
5140 /* Process any pragmas and actions following the unit. */
5145 /* Save away what we've made so far and record this potential elaboration
5146 procedure. */
5159 /* Generate elaboration code for this unit, if necessary, and say whether
5160 we did or not. */
5163 /* Invalidate the global renaming pointers. This is necessary because
5164 stabilization of the renamed entities may create SAVE_EXPRs which
5165 have been tied to a specific elaboration routine just above. */
5168 /* Force the processing for all nodes that remain in the queue. */
5170 }
5171 \f
5172 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Raise_xxx_Error,
5173 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to where
5174 we should place the result type. LABEL_P is true if there is a label to
5175 branch to for the exception. */
5177 static tree
5179 {
5183 const bool with_extra_info
5184 = Exception_Extra_Info
5192 {
5202 {
5208 {
5228 }
5235 && gnu_low_bound
5236 && gnu_high_bound
5239 gnu_result
5243 /* If loop unswitching is enabled, we try to compute invariant
5244 conditions for checks applied to iteration variables, i.e.
5245 conditions that are both independent of the variable and
5246 necessary in order for the check to fail in the course of
5247 some iteration, and prepend them to the original condition
5248 of the checks. This will make it possible later for the
5249 loop unswitching pass to replace the loop with two loops,
5250 one of which has the checks eliminated and the other has
5251 the original checks reinstated, and a run time selection.
5252 The former loop will be suitable for vectorization. */
5255 && (!gnu_low_bound
5257 && (!gnu_high_bound
5260 {
5265 boolean_true_node);
5267 boolean_type_node,
5270 }
5271 }
5276 }
5278 common:
5283 /* If the type is VOID, this is a statement, so we need to generate the code
5284 for the call. Handle a condition, if there is one. */
5286 {
5288 {
5293 }
5294 }
5295 else
5299 }
5300 \f
5301 /* Return true if GNAT_NODE is on the LHS of an assignment or an actual
5302 parameter of a call. */
5304 static bool
5306 {
5321 }
5323 /* Return true if either GNAT_NODE or a view of GNAT_NODE is on the LHS
5324 of an assignment or an actual parameter of a call. */
5326 static bool
5328 {
5329 Node_Kind kind;
5341 }
5343 /* Return true if GNAT_NODE, an unchecked type conversion, is a no-op as far
5344 as gigi is concerned. This is used to avoid conversions on the LHS. */
5346 static bool
5348 {
5351 /* The conversion must be on the LHS of an assignment or an actual parameter
5352 of a call. Otherwise, even if the conversion was essentially a no-op, it
5353 could de facto ensure type consistency and this should be preserved. */
5359 /* We're interested in artificial conversions generated by the front-end
5360 to make private types explicit, e.g. in Expand_Assign_Array. */
5367 /* The direct conversion to the underlying type is a no-op. */
5371 /* For an array subtype, the conversion to the PAIT is a no-op. */
5376 /* For a record subtype, the conversion to the type is a no-op. */
5382 }
5384 /* This function is the driver of the GNAT to GCC tree transformation process.
5385 It is the entry point of the tree transformer. GNAT_NODE is the root of
5386 some GNAT tree. Return the root of the corresponding GCC tree. If this
5387 is an expression, return the GCC equivalent of the expression. If this
5388 is a statement, return the statement or add it to the current statement
5389 group, in which case anything returned is to be interpreted as occurring
5390 after anything added. */
5392 tree
5394 {
5400 Node_Id gnat_temp;
5402 /* Save node number for error message and set location information. */
5406 /* If this node is a statement and we are only annotating types, return an
5407 empty statement list. */
5411 /* If this node is a non-static subexpression and we are only annotating
5412 types, make this into a NULL_EXPR. */
5419 N_Raise_Constraint_Error));
5428 {
5431 /* If this is a statement and we are at top level, it must be part of
5432 the elaboration procedure, so mark us as being in that procedure. */
5434 {
5437 }
5439 /* If we are in the elaboration procedure, check if we are violating a
5440 No_Elaboration_Code restriction by having a statement there. Don't
5441 check for a possible No_Elaboration_Code restriction violation on
5442 N_Handled_Sequence_Of_Statements, as we want to signal an error on
5443 every nested real statement instead. This also avoids triggering
5444 spurious errors on dummy (empty) sequences created by the front-end
5445 for package bodies in some cases. */
5449 }
5452 {
5453 /********************************/
5454 /* Chapter 2: Lexical Elements */
5455 /********************************/
5463 /* If this is an atomic access on the RHS for which synchronization is
5464 required, build the atomic load. */
5471 {
5472 tree gnu_type;
5474 /* Get the type of the result, looking inside any padding and
5475 justified modular types. Then get the value in that type. */
5484 /* If the result overflows (meaning it doesn't fit in its base type),
5485 abort. We would like to check that the value is within the range
5486 of the subtype, but that causes problems with subtypes whose usage
5487 will raise Constraint_Error and with biased representation, so
5488 we don't. */
5490 }
5494 /* If a Entity is present, it means that this was one of the
5495 literals in a user-defined character type. In that case,
5496 just return the value in the CONST_DECL. Otherwise, use the
5497 character code. In that case, the base type should be an
5498 INTEGER_TYPE, but we won't bother checking for that. */
5502 else
5503 gnu_result
5504 = build_int_cst_type
5511 /* If this is of a fixed-point type, the value we want is the value of
5512 the corresponding integer. */
5514 {
5516 gnu_result_type);
5518 }
5520 else
5521 {
5524 /* First convert the value to a machine number if it isn't already.
5525 That will force the base to 2 for non-zero values and simplify
5526 the rest of the logic. */
5528 ur_realval
5534 else
5535 {
5536 REAL_VALUE_TYPE tmp;
5540 /* The base must be 2 as Machine guarantees this, so we scale
5541 the value, which we know can fit in the mantissa of the type
5542 (hence the use of that type above). */
5547 }
5549 /* Now see if we need to negate the result. Do it this way to
5550 properly handle -0. */
5552 gnu_result
5554 gnu_result);
5555 }
5562 {
5569 else
5572 /* Build the string with the characters in the literal. Note
5573 that Ada strings are 1-origin. */
5577 /* Put a null at the end of the string in case it's in a context
5578 where GCC will want to treat it as a C string. */
5583 /* Strings in GCC don't normally have types, but we want
5584 this to not be converted to the array type. */
5589 }
5590 else
5591 {
5592 /* Build a list consisting of each character, then make
5593 the aggregate. */
5603 {
5609 }
5612 }
5619 /**************************************/
5620 /* Chapter 3: Declarations and Types */
5621 /**************************************/
5638 /* If we are just annotating types and this object has an unconstrained
5639 or task type, don't elaborate it. */
5649 && (!type_annotate_only
5651 {
5654 gnu_expr
5657 /* If this object has its elaboration delayed, we must force
5658 evaluation of GNU_EXPR right now and save it for when the object
5659 is frozen. */
5661 {
5663 ;
5665 gnu_expr
5670 else
5674 }
5675 }
5676 else
5682 /* If this is a deferred constant with an address clause, we ignore the
5683 full view since the clause is on the partial view and we cannot have
5684 2 different GCC trees for the object. The only bits of the full view
5685 we will use is the initializer, but it will be directly fetched. */
5698 /* Don't do anything if this renaming is handled by the front end or if
5699 we are just annotating types and this object has a composite or task
5700 type, don't elaborate it. We return the result in case it has any
5701 SAVE_EXPRs in it that need to be evaluated here. */
5703 && ! (type_annotate_only
5707 gnu_result
5710 else
5717 gnu_result
5720 else
5732 /* These are fully handled in the front end. */
5733 /* ??? For package renamings, find a way to use GENERIC namespaces so
5734 that we get proper debug information for them. */
5738 /*************************************/
5739 /* Chapter 4: Names and Expressions */
5740 /*************************************/
5747 /* If this is an atomic access on the RHS for which synchronization is
5748 required, build the atomic load. */
5755 {
5757 tree gnu_type;
5764 /* Convert vector inputs to their representative array type, to fit
5765 what the code below expects. */
5767 {
5771 }
5775 /* If we got a padded type, remove it too. */
5777 gnu_array_object
5779 gnu_array_object);
5783 /* The failure of this assertion will very likely come from a missing
5784 expansion for a packed array access. */
5787 /* First compute the number of dimensions of the array, then
5788 fill the expression array, the order depending on whether
5789 this is a Convention_Fortran array or not. */
5794 ;
5803 else
5811 {
5817 gnu_expr
5818 = emit_index_check
5822 gnat_temp);
5824 gnu_result
5827 /* Array accesses are bound-checked so they cannot trap, but this
5828 is valid only if they are not hoisted ahead of the check. We
5829 need to mark them as no-trap to get decent loop optimizations
5830 in the presence of -fnon-call-exceptions, so we do it when we
5831 know that the original expression had no side-effects. */
5836 }
5840 /* If this is an atomic access on the RHS for which synchronization is
5841 required, build the atomic load. */
5845 }
5849 {
5851 tree gnu_type;
5856 /* Do any implicit dereferences of the prefix and do any needed
5857 range check. */
5862 {
5863 /* Get the bounds of the slice. */
5864 tree gnu_index_type
5868 /* Get the permitted bounds. */
5869 tree gnu_base_index_type
5871 tree gnu_base_min_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
5873 tree gnu_base_max_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
5880 /* Derive a good type to convert everything to. */
5883 /* Test whether the minimum slice value is too small. */
5886 gnu_min_expr),
5888 gnu_base_min_expr));
5890 /* Test whether the maximum slice value is too large. */
5893 gnu_max_expr),
5895 gnu_base_max_expr));
5897 /* Build a slice index check that returns the low bound,
5898 assuming the slice is not empty. */
5899 gnu_expr = emit_check
5904 /* Build a conditional expression that does the index checks and
5905 returns the low bound if the slice is not empty (max >= min),
5906 and returns the naked low bound otherwise (max < min), unless
5907 it is non-constant and the high bound is; this prevents VRP
5908 from inferring bogus ranges on the unlikely path. */
5912 gnu_max_expr),
5914 gnu_min_expr)),
5915 gnu_expr,
5919 }
5920 else
5921 /* Simply return the naked low bound. */
5924 /* If this is a slice with non-constant size of an array with constant
5925 size, set the maximum size for the allocation of temporaries. */
5932 }
5936 {
5940 tree gnu_field;
5944 /* For discriminant references in tagged types always substitute the
5945 corresponding discriminant as the actual selected component. */
5950 /* For discriminant references of untagged types always substitute the
5951 corresponding stored discriminant. */
5955 /* Handle extracting the real or imaginary part of a complex.
5956 The real part is the first field and the imaginary the last. */
5961 else
5962 {
5965 /* If there are discriminants, the prefix might be evaluated more
5966 than once, which is a problem if it has side-effects. */
5973 gnu_result
5977 && lvalue_required_for_attribute_p
5979 }
5983 /* If this is an atomic access on the RHS for which synchronization is
5984 required, build the atomic load. */
5988 }
5992 {
5993 /* The attribute designator. */
5996 /* The Elab_Spec and Elab_Body attributes are special in that Prefix
5997 is a unit, not an object with a GCC equivalent. */
5999 return
6007 }
6011 /* Like 'Access as far as we are concerned. */
6019 {
6020 tree gnu_aggr_type;
6022 /* ??? It is wrong to evaluate the type now, but there doesn't
6023 seem to be any other practical way of doing it. */
6027 gnu_aggr_type = gnu_result_type
6032 gnu_aggr_type
6039 NULL);
6043 gnu_result
6046 gnu_aggr_type);
6049 gnu_aggr_type,
6052 gnu_result
6053 = build_binary_op
6058 (Next
6060 else
6064 }
6072 else
6079 /* Get the operand expression. */
6083 /* If this is a qualified expression for a tagged type, we mark the type
6084 as used. Because of polymorphism, this might be the only reference to
6085 the tagged type in the program while objects have it as dynamic type.
6086 The debugger needs to see it to display these objects properly. */
6090 gnu_result
6094 kind == N_Type_Conversion
6101 /* Skip further processing if the conversion is deemed a no-op. */
6103 {
6106 }
6110 /* If the result is a pointer type, see if we are improperly
6111 converting to a stricter alignment. */
6114 {
6120 post_error_ne_tree_2
6124 }
6126 /* If we are converting a descriptor to a function pointer, first
6127 build the pointer. */
6139 {
6144 /* GNAT_RANGE is either an N_Range node or an identifier denoting a
6145 subtype. */
6147 {
6150 }
6153 {
6157 gnu_low
6159 gnu_high
6161 }
6162 else
6167 /* If LOW and HIGH are identical, perform an equality test. Otherwise,
6168 ensure that GNU_OBJ is evaluated only once and perform a full range
6169 test. */
6171 gnu_result
6173 else
6174 {
6183 gnu_result
6185 }
6188 gnu_result
6190 }
6198 ? RDIV_EXPR
6205 /* These can either be operations on booleans or on modular types.
6206 Fall through for boolean types since that's the way GNU_CODES is
6207 set up. */
6209 {
6210 enum tree_code code
6221 }
6223 /* ... fall through ... */
6235 {
6239 tree gnu_type;
6245 /* Pending generic support for efficient vector logical operations in
6246 GCC, convert vectors to their representative array type view and
6247 fallthrough. */
6251 /* If this is a comparison operator, convert any references to an
6252 unconstrained array value into a reference to the actual array. */
6254 {
6257 }
6259 /* If this is a shift whose count is not guaranteed to be correct,
6260 we need to adjust the shift count. */
6262 {
6264 tree gnu_max_shift
6271 gnu_rhs
6272 = build_binary_op
6275 gnu_count_type,
6276 gnu_max_shift,
6278 integer_one_node)),
6279 gnu_rhs);
6280 }
6282 /* For right shifts, the type says what kind of shift to do,
6283 so we may need to choose a different type. In this case,
6284 we have to ignore integer overflow lest it propagates all
6285 the way down and causes a CE to be explicitly raised. */
6287 {
6290 }
6293 {
6296 }
6299 {
6305 }
6307 /* Instead of expanding overflow checks for addition, subtraction
6308 and multiplication itself, the front end will leave this to
6309 the back end when Backend_Overflow_Checks_On_Target is set.
6310 As the GCC back end itself does not know yet how to properly
6311 do overflow checking, do it here. The goal is to push
6312 the expansions further into the back end over time. */
6321 else
6322 {
6323 /* Some operations, e.g. comparisons of arrays, generate complex
6324 trees that need to be annotated while they are being built. */
6327 }
6329 /* If this is a logical shift with the shift count not verified,
6330 we must return zero if it is too large. We cannot compensate
6331 above in this case. */
6334 gnu_result
6335 = build_cond_expr
6338 gnu_rhs,
6342 gnu_result);
6343 }
6347 {
6350 tree gnu_false
6354 gnu_result
6356 }
6365 /* This case can apply to a boolean or a modular type.
6366 Fall through for a boolean operand since GNU_CODES is set
6367 up to handle this. */
6369 {
6373 gnu_expr);
6375 }
6377 /* ... fall through ... */
6386 gnu_result
6389 else
6395 {
6397 tree gnu_type;
6402 /* The Expression operand can either be an N_Identifier or
6403 Expanded_Name, which must represent a type, or a
6404 N_Qualified_Expression, which contains both the object type and an
6405 initial value for the object. */
6410 {
6411 Entity_Id gnat_desig_type
6419 gnu_init
6425 else
6426 {
6430 }
6432 /* See the N_Qualified_Expression case for the rationale. */
6437 }
6438 else
6445 ignore_init_type);
6446 }
6449 /**************************/
6450 /* Chapter 5: Statements */
6451 /**************************/
6459 /* When not optimizing, turn null statements from source into gotos to
6460 the next statement that the middle-end knows how to preserve. */
6462 {
6473 }
6474 else
6479 /* Get the LHS and RHS of the statement and convert any reference to an
6480 unconstrained array into a reference to the underlying array. */
6483 /* If the type has a size that overflows, convert this into raise of
6484 Storage_Error: execution shouldn't have gotten here anyway. */
6488 N_Raise_Storage_Error);
6490 gnu_result
6493 else
6494 {
6496 const Entity_Id gnat_type
6498 const bool regular_array_type_p
6500 const bool use_memset_p
6501 = (regular_array_type_p
6505 /* If we'll use memset, we need to find the inner expression. */
6507 {
6508 Node_Id gnat_inner
6512 gnat_inner
6515 }
6516 else
6519 /* If range check is needed, emit code to generate it. */
6522 gnat_node);
6524 /* If atomic synchronization is required, build an atomic store. */
6528 /* Or else, use memset when the conditions are met. */
6530 {
6534 tree size
6539 {
6540 tree mask
6544 }
6546 }
6548 /* Otherwise build a regular assignment. */
6549 else
6550 gnu_result
6553 /* If the assignment type is a regular array and the two sides are
6554 not completely disjoint, play safe and use memmove. But don't do
6555 it for a bit-packed array as it might not be byte-aligned. */
6557 && regular_array_type_p
6559 {
6563 tree size
6569 }
6570 }
6574 {
6577 /* Make the outer COND_EXPR. Avoid non-determinism. */
6586 /* Now make a COND_EXPR for each of the "else if" parts. Put each
6587 into the previous "else" part and point to where to put any
6588 outer "else". Also avoid non-determinism. */
6592 {
6602 }
6605 }
6617 /* The only way to enter the block is to fall through to it. */
6619 {
6626 }
6627 else
6632 gnu_result
6642 {
6645 /* If the subprogram is a function, we must return the expression. */
6647 {
6650 /* If this function has copy-in/copy-out parameters parameters and
6651 doesn't return by invisible reference, get the real object for
6652 the return. See Subprogram_Body_to_gnu. */
6656 else
6659 /* Get the GCC tree for the expression to be returned. */
6662 /* Do not remove the padding from GNU_RET_VAL if the inner type is
6663 self-referential since we want to allocate the fixed size. */
6665 && TYPE_IS_PADDING_P
6667 && CONTAINS_PLACEHOLDER_P
6671 /* If the function returns by direct reference, return a pointer
6672 to the return value. */
6677 /* Otherwise, if it returns an unconstrained array, we have to
6678 allocate a new version of the result and return it. */
6680 {
6683 /* And find out whether this is a candidate for Named Return
6684 Value. If so, record it. */
6686 {
6689 /* Strip useless conversions around the return value. */
6693 /* Strip unpadding around the return value. */
6695 && TYPE_IS_PADDING_P
6699 /* Now apply the test to the return value. */
6701 {
6707 }
6708 }
6711 gnu_ret_val,
6716 }
6718 /* Otherwise, if it returns by invisible reference, dereference
6719 the pointer it is passed using the type of the return value
6720 and build the copy operation manually. This ensures that we
6721 don't copy too much data, for example if the return type is
6722 unconstrained with a maximum size. */
6724 {
6725 tree gnu_ret_deref
6727 gnu_ret_obj);
6732 }
6733 }
6735 else
6738 /* If we have a return label defined, convert this into a branch to
6739 that label. The return proper will be handled elsewhere. */
6741 {
6744 gnu_ret_val));
6749 /* When not optimizing, make sure the return is preserved. */
6752 }
6754 /* Otherwise, build a regular return. */
6755 else
6757 }
6761 gnu_result
6765 /***************************/
6766 /* Chapter 6: Subprograms */
6767 /***************************/
6770 /* Unless there is a freeze node, declare the subprogram. We consider
6771 this a "definition" even though we're not generating code for
6772 the subprogram because we will be making the corresponding GCC
6773 node here. */
6782 /* This subprogram doesn't exist for code generation purposes, but we
6783 have to elaborate the types of any parameters and result, unless
6784 they are imported types (nothing to generate in this case).
6786 The parameter list may contain types with freeze nodes, e.g. not null
6787 subtypes, so the subprogram itself may carry a freeze node, in which
6788 case its elaboration must be deferred. */
6790 /* Process the parameter types first. */
6793 = First_Formal_With_Extras
6801 /* Then the result type, set to Standard_Void_Type for procedures. */
6802 {
6803 Entity_Id gnat_temp_type
6808 }
6814 /* For a child unit identifier go up a level to get the specification.
6815 We get this when we try to find the spec of a child unit package
6816 that is the compilation unit being compiled. */
6830 /************************/
6831 /* Chapter 7: Packages */
6832 /************************/
6848 /* If this is the body of a generic package - do nothing. */
6850 {
6853 }
6864 /********************************/
6865 /* Chapter 8: Visibility Rules */
6866 /********************************/
6870 /* Nothing to do here - but these may appear in list of declarations. */
6874 /*********************/
6875 /* Chapter 9: Tasks */
6876 /*********************/
6887 /*********************************************************/
6888 /* Chapter 10: Program Structure and Compilation Issues */
6889 /*********************************************************/
6892 /* This is not called for the main unit on which gigi is invoked. */
6901 /* Simply process whatever unit is being inserted. */
6904 else
6905 {
6908 }
6915 /***************************/
6916 /* Chapter 11: Exceptions */
6917 /***************************/
6920 /* If there is an At_End procedure attached to this node, and the EH
6921 mechanism is SJLJ, we must have at least a corresponding At_End
6922 handler, unless the No_Exception_Handlers restriction is set. */
6937 else
6942 /* Only for reraise in back-end exceptions mode. */
6949 /* Clear the current exception pointer so that the occurrence won't be
6950 deallocated. */
6989 /******************************/
6990 /* Chapter 12: Generic Units */
6991 /******************************/
7001 /* These nodes can appear on a declaration list but there is nothing to
7002 to be done with them. */
7006 /**************************************************/
7007 /* Chapter 13: Representation Clauses and */
7008 /* Implementation-Dependent Features */
7009 /**************************************************/
7014 /* The only one we need to deal with is 'Address since, for the others,
7015 the front-end puts the information elsewhere. */
7019 /* And we only deal with 'Address if the object has a Freeze node. */
7024 /* Get the value to use as the address and save it as the equivalent
7025 for the object. When it is frozen, gnat_to_gnu_entity will do the
7026 right thing. */
7033 /* We do nothing with these. SEM puts the information elsewhere. */
7039 {
7049 /* First retrieve the 3 operand lists built by the front-end. */
7052 {
7059 }
7063 {
7070 }
7074 gnu_clobbers
7077 gnu_clobbers);
7079 /* Then perform some standard checking and processing on the
7080 operands. In particular, mark them addressable if needed. */
7088 {
7090 constraint
7096 {
7097 /* If the operand is going to end up in memory,
7098 mark it addressable. Note that we don't test
7099 allows_mem like in the input case below; this
7100 is modelled on the C front-end. */
7102 {
7109 }
7110 }
7111 else
7115 }
7118 {
7120 constraint
7126 {
7127 /* If the operand is going to end up in memory,
7128 mark it addressable. */
7130 {
7137 }
7138 }
7139 else
7143 }
7149 }
7150 else
7155 /****************/
7156 /* Added Nodes */
7157 /****************/
7160 /* This construct doesn't define a scope so we don't push a binding
7161 level around the statement list, but we wrap it in a SAVE_EXPR to
7162 protect it from unsharing. Elaborate the expression as part of the
7163 same statement group as the actions so that the type declaration
7164 gets inserted there as well. This ensures that the type elaboration
7165 code is issued past the actions computing values on which it might
7166 depend. */
7176 gnu_result
7201 {
7206 /* If this is a thin pointer, we must first dereference it to create
7207 a fat pointer, then go back below to a thin pointer. The reason
7208 for this is that we need to have a fat pointer someplace in order
7209 to properly compute the size. */
7213 gnu_ptr));
7215 /* If this is a fat pointer, the object must have been allocated with
7216 the template in front of the array. So pass the template address,
7217 and get the total size; do it by converting to a thin pointer. */
7219 gnu_ptr
7221 (TYPE_OBJECT_RECORD_TYPE
7223 gnu_ptr);
7227 /* If this is a thin pointer, the object must have been allocated with
7228 the template in front of the array. So pass the template address,
7229 and get the total size. */
7231 gnu_ptr
7233 gnu_ptr,
7235 byte_position
7236 (DECL_CHAIN
7239 /* If we have a special dynamic constrained subtype on the node, use
7240 it to compute the size; otherwise, use the designated subtype. */
7242 {
7243 gnu_actual_obj_type
7247 gnu_actual_obj_type
7249 gnu_actual_obj_type,
7252 }
7253 else
7256 gnu_result
7259 gnu_obj_type,
7262 gnat_node);
7263 }
7271 else
7276 /* The only validation we currently do on an unchecked conversion is
7277 that of aliasing assumptions. */
7289 /* These nodes should only be present when annotating types. */
7295 /* Other nodes are not supposed to reach here. */
7297 }
7299 /* If we pushed the processing of the elaboration routine, pop it back. */
7303 /* When not optimizing, turn boolean rvalues B into B != false tests
7304 so that the code just below can put the location information of the
7305 reference to B on the inequality operator for better debug info. */
7319 boolean_false_node));
7321 /* Set the location information on the result. Note that we may have
7322 no result if we tried to build a CALL_EXPR node to a procedure with
7323 no side-effects and optimization is enabled. */
7327 /* If we're supposed to return something of void_type, it means we have
7328 something we're elaborating for effect, so just return. */
7332 /* If the result is a constant that overflowed, raise Constraint_Error. */
7334 {
7336 gnu_result
7339 N_Raise_Constraint_Error));
7340 }
7342 /* If the result has side-effects and is of an unconstrained type, make a
7343 SAVE_EXPR so that we can be sure it will only be referenced once. But
7344 this is useless for a call to a function that returns an unconstrained
7345 type with default discriminant, as we cannot compute the size of the
7346 actual returned object. We must do this before any conversions. */
7354 /* Now convert the result to the result type, unless we are in one of the
7355 following cases:
7357 1. If this is the LHS of an assignment or an actual parameter of a
7358 call, return the result almost unmodified since the RHS will have
7359 to be converted to our type in that case, unless the result type
7360 has a simpler size. Likewise if there is just a no-op unchecked
7361 conversion in-between. Similarly, don't convert integral types
7362 that are the operands of an unchecked conversion since we need
7363 to ignore those conversions (for 'Valid).
7365 2. If we have a label (which doesn't have any well-defined type), a
7366 field or an error, return the result almost unmodified. Similarly,
7367 if the two types are record types with the same name, don't convert.
7368 This will be the case when we are converting from a packable version
7369 of a type to its original type and we need those conversions to be
7370 NOPs in order for assignments into these types to work properly.
7372 3. If the type is void or if we have no result, return error_mark_node
7373 to show we have no result.
7375 4. If this a call to a function that returns an unconstrained type with
7376 default discriminant, return the call expression unmodified since we
7377 cannot compute the size of the actual returned object.
7379 5. Finally, if the type of the result is already correct. */
7397 && (CONTAINS_PLACEHOLDER_P
7401 {
7402 /* Remove padding only if the inner object is of self-referential
7403 size: in that case it must be an object of unconstrained type
7404 with a default discriminant and we want to avoid copying too
7405 much data. */
7410 gnu_result);
7411 }
7420 {
7421 /* Remove any padding. */
7424 gnu_result);
7425 }
7433 == gnu_result_type
7435 ;
7440 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on the result. */
7447 }
7448 \f
7449 /* Subroutine of above to push the exception label stack. GNU_STACK is
7450 a pointer to the stack to update and GNAT_LABEL, if present, is the
7451 label to push onto the stack. */
7453 static void
7455 {
7461 }
7462 \f
7463 /* Record the current code position in GNAT_NODE. */
7465 static void
7467 {
7472 }
7474 /* Insert the code for GNAT_NODE at the position saved for that node. */
7476 static void
7478 {
7481 }
7482 \f
7483 /* Start a new statement group chained to the previous group. */
7485 void
7487 {
7490 /* First see if we can get one from the free list. */
7493 else
7499 }
7501 /* Add GNU_STMT to the current statement group. If it is an expression with
7502 no effects, it is ignored. */
7504 void
7506 {
7508 }
7510 /* Similar, but the statement is always added, regardless of side-effects. */
7512 void
7514 {
7516 }
7518 /* Like add_stmt, but set the location of GNU_STMT to that of GNAT_NODE. */
7520 void
7522 {
7523 /* Do not emit a location for renamings that come from generic instantiation,
7524 they are likely to disturb debugging. */
7529 }
7531 /* Similar, but the statement is always added, regardless of side-effects. */
7533 void
7535 {
7539 }
7541 /* Add a declaration statement for GNU_DECL to the current statement group.
7542 Get SLOC from Entity_Id. */
7544 void
7546 {
7550 /* If this is a variable that Gigi is to ignore, we may have been given
7551 an ERROR_MARK. So test for it. We also might have been given a
7552 reference for a renaming. So only do something for a decl. Also
7553 ignore a TYPE_DECL for an UNCONSTRAINED_ARRAY_TYPE. */
7561 /* If we are external or global, we don't want to output the DECL_EXPR for
7562 this DECL node since we already have evaluated the expressions in the
7563 sizes and positions as globals and doing it again would be wrong. */
7565 {
7566 /* Mark everything as used to prevent node sharing with subprograms.
7567 Note that walk_tree knows how to deal with TYPE_DECL, but neither
7568 VAR_DECL nor CONST_DECL. This appears to be somewhat arbitrary. */
7572 {
7576 }
7577 /* In any case, we have to deal with our own TYPE_ADA_SIZE field. */
7582 }
7583 else
7586 /* If this is a variable and an initializer is attached to it, it must be
7587 valid for the context. Similar to init_const in create_var_decl_1. */
7594 {
7595 /* If GNU_DECL has a padded type, convert it to the unpadded
7596 type so the assignment is done properly. */
7599 else
7606 {
7609 }
7612 }
7613 }
7615 /* Callback for walk_tree to mark the visited trees rooted at *TP. */
7617 static tree
7619 {
7625 /* Don't mark a dummy type as visited because we want to mark its sizes
7626 and fields once it's filled in. */
7634 }
7636 /* Mark nodes rooted at T with TREE_VISITED and types as having their
7637 sized gimplified. We use this to indicate all variable sizes and
7638 positions in global types may not be shared by any subprogram. */
7640 void
7642 {
7644 }
7646 /* Add GNU_CLEANUP, a cleanup action, to the current code group and
7647 set its location to that of GNAT_NODE if present, but with column info
7648 cleared so that conditional branches generated as part of the cleanup
7649 code do not interfere with coverage analysis tools. */
7651 static void
7653 {
7657 }
7659 /* Set the BLOCK node corresponding to the current code group to GNU_BLOCK. */
7661 void
7663 {
7666 }
7668 /* Return code corresponding to the current code group. It is normally
7669 a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
7670 BLOCK or cleanups were set. */
7672 tree
7674 {
7678 /* If this is a null list, allocate a new STATEMENT_LIST. Then, if there
7679 are cleanups, make a TRY_FINALLY_EXPR. Last, if there is a BLOCK,
7680 make a BIND_EXPR. Note that we nest in that because the cleanup may
7681 reference variables in the block. */
7693 /* Remove this group from the stack and add it to the free list. */
7699 }
7701 /* Return whether the current statement group may fall through. */
7705 {
7708 else
7710 }
7712 /* Add a list of statements from GNAT_LIST, a possibly-empty list of
7713 statements.*/
7715 static void
7717 {
7718 Node_Id gnat_node;
7724 }
7726 /* Build a tree from GNAT_LIST, a possibly-empty list of statements.
7727 If BINDING_P is true, push and pop a binding level around the list. */
7729 static tree
7731 {
7741 }
7742 \f
7743 /* Generate GIMPLE in place for the expression at *EXPR_P. */
7745 int
7748 {
7751 tree op;
7757 {
7759 /* If this is an aggregate type, build a null pointer of the appropriate
7760 type and dereference it. */
7765 integer_zero_node));
7766 /* Otherwise, just make a VAR_DECL. */
7767 else
7768 {
7771 }
7777 /* We should only do this if we are just elaborating for side-effects,
7778 but we can't know that yet. */
7785 /* If we are taking the address of a constant CONSTRUCTOR, make sure it
7786 is put into static memory. We know that it's going to be read-only
7787 given the semantics we have and it must be in static memory when the
7788 reference is in an elaboration procedure. */
7790 {
7794 }
7801 /* If we are view-converting a CONSTRUCTOR or a call from an aggregate
7802 type to a scalar one, explicitly create the local temporary. That's
7803 required if the type is passed by reference. */
7807 {
7816 }
7823 /* The expressions for the RM bounds must be gimplified to ensure that
7824 they are properly elaborated. See gimplify_decl_expr. */
7828 {
7833 {
7838 {
7842 }
7846 {
7850 }
7852 }
7857 }
7859 /* ... fall through ... */
7863 }
7864 }
7866 /* Generate GIMPLE in place for the statement at *STMT_P. */
7868 static enum gimplify_status
7870 {
7874 {
7880 {
7886 /* Build the condition expression from the test, if any. */
7888 {
7889 /* Deal with the optimization hints. */
7893 annot_expr_ivdep_kind));
7897 annot_expr_no_vector_kind));
7901 annot_expr_vector_kind));
7903 gnu_cond
7906 }
7908 /* Set to emit the statements of the loop. */
7911 /* We first emit the start label and then a conditional jump to the
7912 end label if there's a top condition, then the update if it's at
7913 the top, then the body of the loop, then a conditional jump to
7914 the end label if there's a bottom condition, then the update if
7915 it's at the bottom, and finally a jump to the start label and the
7916 definition of the end label. */
7918 gnu_start_label),
7919 stmt_p);
7940 gnu_end_label),
7941 stmt_p);
7943 }
7946 /* Build a statement to jump to the corresponding end label, then
7947 see if it needs to be conditional. */
7956 }
7957 }
7958 \f
7959 /* Force references to each of the entities in packages withed by GNAT_NODE.
7960 Operate recursively but check that we aren't elaborating something more
7961 than once.
7963 This routine is exclusively called in type_annotate mode, to compute DDA
7964 information for types in withed units, for ASIS use. */
7966 static void
7968 {
7971 /* Process each unit only once. As we trace the context of all relevant
7972 units transitively, including generic bodies, we may encounter the
7973 same generic unit repeatedly. */
7977 /* Save entities in all context units. A body may have an implicit_with
7978 on its own spec, if the context includes a child unit, so don't save
7979 the spec twice. */
7986 {
7990 {
8007 }
8009 {
8010 Node_Id gnat_body
8013 /* Retrieve compilation unit node of generic body. */
8018 /* If body is available, elaborate its context. */
8021 }
8022 }
8026 }
8027 \f
8028 /* Do the processing of GNAT_NODE, an N_Freeze_Entity. */
8030 static void
8032 {
8037 /* If this is a package, we need to generate code for the package. */
8039 {
8040 insert_code_for
8044 }
8046 /* Don't do anything for class-wide types as they are always transformed
8047 into their root type. */
8051 /* Check for an old definition. This freeze node might be for an Itype. */
8052 gnu_old
8055 /* If this entity has an address representation clause, GNU_OLD is the
8056 address, so discard it here. */
8060 /* Don't do anything for subprograms that may have been elaborated before
8061 their freeze nodes. This can happen, for example, because of an inner
8062 call in an instance body or because of previous compilation of a spec
8063 for inlining purposes. */
8071 /* If we have a non-dummy type old tree, we have nothing to do, except
8072 aborting if this is the public view of a private type whose full view was
8073 not delayed, as this node was never delayed as it should have been. We
8074 let this happen for concurrent types and their Corresponding_Record_Type,
8075 however, because each might legitimately be elaborated before its own
8076 freeze node, e.g. while processing the other. */
8080 {
8088 }
8090 /* Reset the saved tree, if any, and elaborate the object or type for real.
8091 If there is a full view, elaborate it and use the result. And, if this
8092 is the root type of a class-wide type, reuse it for the latter. */
8094 {
8099 {
8106 {
8109 }
8110 }
8116 }
8120 {
8129 /* Propagate back-annotations from full view to partial view. */
8139 /* The above call may have defined this entity (the simplest example
8140 of this is when we have a private enumeral type since the bounds
8141 will have the public view). */
8144 }
8145 else
8146 {
8147 tree gnu_init
8153 }
8160 /* If we have an old type and we've made pointers to this type, update those
8161 pointers. If this is a Taft amendment type in the main unit, we need to
8162 mark the type as used since other units referencing it don't see the full
8163 declaration and, therefore, cannot mark it as used themselves. */
8165 {
8170 }
8171 }
8172 \f
8173 /* Elaborate decls in the lists GNAT_DECLS and GNAT_DECLS2, if present.
8174 We make two passes, one to elaborate anything other than bodies (but
8175 we declare a function if there was no spec). The second pass
8176 elaborates the bodies.
8178 GNAT_END_LIST gives the element in the list past the end. Normally,
8179 this is Empty, but can be First_Real_Statement for a
8180 Handled_Sequence_Of_Statements.
8182 We make a complete pass through both lists if PASS1P is true, then make
8183 the second pass over both lists if PASS2P is true. The lists usually
8184 correspond to the public and private parts of a package. */
8186 static void
8189 {
8191 Node_Id gnat_decl;
8201 {
8202 /* For package specs, we recurse inside the declarations,
8203 thus taking the two pass approach inside the boundary. */
8211 /* Similarly for any declarations in the actions of a
8212 freeze node. */
8214 {
8217 }
8219 /* Package bodies with freeze nodes get their elaboration deferred
8220 until the freeze node, but the code must be placed in the right
8221 place, so record the code position now. */
8229 (Corresponding_Spec
8232 record_code_position
8235 /* We defer most subprogram bodies to the second pass. */
8237 {
8239 {
8245 }
8246 }
8248 /* For bodies and stubs that act as their own specs, the entity
8249 itself must be elaborated in the first pass, because it may
8250 be used in other declarations. */
8252 {
8253 Node_Id gnat_subprog_id
8260 }
8262 /* Concurrent stubs stand for the corresponding subprogram bodies,
8263 which are deferred like other bodies. */
8266 ;
8268 else
8270 }
8272 /* Here we elaborate everything we deferred above except for package bodies,
8273 which are elaborated at their freeze nodes. Note that we must also
8274 go inside things (package specs and freeze nodes) the first pass did. */
8280 {
8296 }
8297 }
8298 \f
8299 /* Make a unary operation of kind CODE using build_unary_op, but guard
8300 the operation by an overflow check. CODE can be one of NEGATE_EXPR
8301 or ABS_EXPR. GNU_TYPE is the type desired for the result. Usually
8302 the operation is to be performed in that type. GNAT_NODE is the gnat
8303 node conveying the source location for which the error should be
8304 signaled. */
8306 static tree
8308 Node_Id gnat_node)
8309 {
8318 }
8320 /* Make a binary operation of kind CODE using build_binary_op, but guard
8321 the operation by an overflow check. CODE can be one of PLUS_EXPR,
8322 MINUS_EXPR or MULT_EXPR. GNU_TYPE is the type desired for the result.
8323 Usually the operation is to be performed in that type. GNAT_NODE is
8324 the GNAT node conveying the source location for which the error should
8325 be signaled. */
8327 static tree
8330 {
8340 /* Assert that the precision is a power of 2. */
8343 /* Prefer a constant or known-positive rhs to simplify checks. */
8349 {
8353 }
8357 /* If we can fold the expression to a constant, just return it.
8358 The caller will deal with overflow, no need to generate a check. */
8363 ? boolean_false_node
8366 /* ??? Should use more efficient check for operand_equal_p (lhs, rhs, 0) */
8368 /* Try a few strategies that may be cheaper than the general
8369 code at the end of the function, if the rhs is not known.
8370 The strategies are:
8371 - Call library function for 64-bit multiplication (complex)
8372 - Widen, if input arguments are sufficiently small
8373 - Determine overflow using wrapped result for addition/subtraction. */
8376 {
8377 /* Even for add/subtract double size to get another base type. */
8381 {
8387 }
8391 {
8397 check = build_binary_op
8404 return
8406 }
8409 {
8411 tree wrapped_expr
8417 /* Overflow when (rhs < 0) ^ (wrapped_expr < lhs)), for addition
8418 or when (rhs < 0) ^ (wrapped_expr > lhs) for subtraction. */
8419 check
8423 boolean_type_node,
8426 return
8428 }
8429 }
8432 {
8434 /* When rhs >= 0, overflow when lhs > type_max - rhs. */
8439 /* When rhs < 0, overflow when lhs < type_min - rhs. */
8446 /* When rhs >= 0, overflow when lhs < type_min + rhs. */
8451 /* When rhs < 0, overflow when lhs > type_max + rhs. */
8458 /* The check here is designed to be efficient if the rhs is constant,
8459 but it will work for any rhs by using integer division.
8460 Four different check expressions determine whether X * C overflows,
8461 depending on C.
8462 C == 0 => false
8463 C > 0 => X > type_max / C || X < type_min / C
8464 C == -1 => X == type_min
8465 C < -1 => X > type_min / C || X < type_max / C */
8470 check_pos
8473 rhs),
8476 boolean_type_node,
8479 boolean_type_node,
8482 check_neg
8487 type_min),
8490 boolean_type_node,
8493 boolean_type_node,
8499 }
8502 check_pos);
8505 }
8507 /* Emit code for a range check. GNU_EXPR is the expression to be checked,
8508 GNAT_RANGE_TYPE the gnat type or subtype containing the bounds against
8509 which we have to check. GNAT_NODE is the GNAT node conveying the source
8510 location for which the error should be signaled. */
8512 static tree
8514 {
8518 /* If GNU_EXPR has GNAT_RANGE_TYPE as its base type, no check is needed.
8519 This can for example happen when translating 'Val or 'Value. */
8523 /* Range checks can only be applied to types with ranges. */
8527 /* If GNU_EXPR has an integral type that is narrower than GNU_RANGE_TYPE,
8528 we can't do anything since we might be truncating the bounds. No
8529 check is needed in this case. */
8535 /* Checked expressions must be evaluated only once. */
8538 /* Note that the form of the check is
8539 (not (expr >= lo)) or (not (expr <= hi))
8540 the reason for this slightly convoluted form is that NaNs
8541 are not considered to be in range in the float case. */
8542 return emit_check
8544 invert_truthvalue
8548 TYPE_MIN_VALUE
8550 invert_truthvalue
8554 TYPE_MAX_VALUE
8557 }
8558 \f
8559 /* Emit code for an index check. GNU_ARRAY_OBJECT is the array object which
8560 we are about to index, GNU_EXPR is the index expression to be checked,
8561 GNU_LOW and GNU_HIGH are the lower and upper bounds against which GNU_EXPR
8562 has to be checked. Note that for index checking we cannot simply use the
8563 emit_range_check function (although very similar code needs to be generated
8564 in both cases) since for index checking the array type against which we are
8565 checking the indices may be unconstrained and consequently we need to get
8566 the actual index bounds from the array object itself (GNU_ARRAY_OBJECT).
8567 The place where we need to do that is in subprograms having unconstrained
8568 array formal parameters. GNAT_NODE is the GNAT node conveying the source
8569 location for which the error should be signaled. */
8571 static tree
8574 {
8575 tree gnu_expr_check;
8577 /* Checked expressions must be evaluated only once. */
8580 /* Must do this computation in the base type in case the expression's
8581 type is an unsigned subtypes. */
8584 /* If GNU_LOW or GNU_HIGH are a PLACEHOLDER_EXPR, qualify them by
8585 the object we are handling. */
8589 return emit_check
8592 gnu_expr_check,
8594 gnu_low)),
8596 gnu_expr_check,
8598 gnu_high))),
8600 }
8601 \f
8602 /* GNU_COND contains the condition corresponding to an access, discriminant or
8603 range check of value GNU_EXPR. Build a COND_EXPR that returns GNU_EXPR if
8604 GNU_COND is false and raises a CONSTRAINT_ERROR if GNU_COND is true.
8605 REASON is the code that says why the exception was raised. GNAT_NODE is
8606 the GNAT node conveying the source location for which the error should be
8607 signaled. */
8609 static tree
8611 {
8612 tree gnu_call
8614 tree gnu_result
8618 gnu_expr);
8620 /* GNU_RESULT has side effects if and only if GNU_EXPR has:
8621 we don't need to evaluate it just for the check. */
8625 }
8626 \f
8627 /* Return an expression that converts GNU_EXPR to GNAT_TYPE, doing overflow
8628 checks if OVERFLOW_P is true and range checks if RANGE_P is true.
8629 GNAT_TYPE is known to be an integral type. If TRUNCATE_P true, do a
8630 float to integer conversion with truncation; otherwise round.
8631 GNAT_NODE is the GNAT node conveying the source location for which the
8632 error should be signaled. */
8634 static tree
8637 {
8644 /* If we are not doing any checks, the output is an integral type and the
8645 input is not a floating-point type, just do the conversion. This is
8646 required for packed array types and is simpler in all cases anyway. */
8648 && !overflowp
8653 /* First convert the expression to its base type. This
8654 will never generate code, but makes the tests below much simpler.
8655 But don't do this if converting from an integer type to an unconstrained
8656 array type since then we need to get the bounds from the original
8657 (unpacked) type. */
8661 /* If overflow checks are requested, we need to be sure the result will
8662 fit in the output base type. But don't do this if the input
8663 is integer and the output floating-point. */
8666 {
8667 /* Ensure GNU_EXPR only gets evaluated once. */
8675 /* Convert the lower bounds to signed types, so we're sure we're
8676 comparing them properly. Likewise, convert the upper bounds
8677 to unsigned types. */
8691 /* Check each bound separately and only if the result bound
8692 is tighter than the bound on the input type. Note that all the
8693 types are base types, so the bounds must be constant. Also,
8694 the comparison is done in the base type of the input, which
8695 always has the proper signedness. First check for input
8696 integer (which means output integer), output float (which means
8697 both float), or mixed, in which case we always compare.
8698 Note that we have to do the comparison which would *fail* in the
8699 case of an error since if it's an FP comparison and one of the
8700 values is a NaN or Inf, the comparison will fail. */
8707 gnu_cond
8708 = invert_truthvalue
8711 gnu_out_lb)));
8719 gnu_cond
8721 invert_truthvalue
8723 gnu_input,
8725 gnu_out_ub))));
8730 }
8732 /* Now convert to the result base type. If this is a non-truncating
8733 float-to-integer conversion, round. */
8737 {
8743 /* The following calculations depend on proper rounding to even
8744 of each arithmetic operation. In order to prevent excess
8745 precision from spoiling this property, use the widest hardware
8746 floating-point type if FP_ARITH_MAY_WIDEN is true. */
8747 calc_type
8750 /* Compute the exact value calc_type'Pred (0.5) at compile time. */
8754 half_minus_pred_half);
8757 /* If the input is strictly negative, subtract this value
8758 and otherwise add it from the input. For 0.5, the result
8759 is exactly between 1.0 and the machine number preceding 1.0
8760 (for calc_type). Since the last bit of 1.0 is even, this 0.5
8761 will round to 1.0, while all other number with an absolute
8762 value less than 0.5 round to 0.0. For larger numbers exactly
8763 halfway between integers, rounding will always be correct as
8764 the true mathematical result will be closer to the higher
8765 integer compared to the lower one. So, this constant works
8766 for all floating-point numbers.
8768 The reason to use the same constant with subtract/add instead
8769 of a positive and negative constant is to allow the comparison
8770 to be scheduled in parallel with retrieval of the constant and
8771 conversion of the input to the calc_type (if necessary). */
8776 gnu_comp
8778 gnu_add_pred_half
8780 gnu_subtract_pred_half
8784 }
8790 else
8793 /* Finally, do the range check if requested. Note that if the result type
8794 is a modular type, the range check is actually an overflow check. */
8801 }
8802 \f
8803 /* Return true if GNU_EXPR can be directly addressed. This is the case
8804 unless it is an expression involving computation or if it involves a
8805 reference to a bitfield or to an object not sufficiently aligned for
8806 its type. If GNU_TYPE is non-null, return true only if GNU_EXPR can
8807 be directly addressed as an object of this type.
8809 *** Notes on addressability issues in the Ada compiler ***
8811 This predicate is necessary in order to bridge the gap between Gigi
8812 and the middle-end about addressability of GENERIC trees. A tree
8813 is said to be addressable if it can be directly addressed, i.e. if
8814 its address can be taken, is a multiple of the type's alignment on
8815 strict-alignment architectures and returns the first storage unit
8816 assigned to the object represented by the tree.
8818 In the C family of languages, everything is in practice addressable
8819 at the language level, except for bit-fields. This means that these
8820 compilers will take the address of any tree that doesn't represent
8821 a bit-field reference and expect the result to be the first storage
8822 unit assigned to the object. Even in cases where this will result
8823 in unaligned accesses at run time, nothing is supposed to be done
8824 and the program is considered as erroneous instead (see PR c/18287).
8826 The implicit assumptions made in the middle-end are in keeping with
8827 the C viewpoint described above:
8828 - the address of a bit-field reference is supposed to be never
8829 taken; the compiler (generally) will stop on such a construct,
8830 - any other tree is addressable if it is formally addressable,
8831 i.e. if it is formally allowed to be the operand of ADDR_EXPR.
8833 In Ada, the viewpoint is the opposite one: nothing is addressable
8834 at the language level unless explicitly declared so. This means
8835 that the compiler will both make sure that the trees representing
8836 references to addressable ("aliased" in Ada parlance) objects are
8837 addressable and make no real attempts at ensuring that the trees
8838 representing references to non-addressable objects are addressable.
8840 In the first case, Ada is effectively equivalent to C and handing
8841 down the direct result of applying ADDR_EXPR to these trees to the
8842 middle-end works flawlessly. In the second case, Ada cannot afford
8843 to consider the program as erroneous if the address of trees that
8844 are not addressable is requested for technical reasons, unlike C;
8845 as a consequence, the Ada compiler must arrange for either making
8846 sure that this address is not requested in the middle-end or for
8847 compensating by inserting temporaries if it is requested in Gigi.
8849 The first goal can be achieved because the middle-end should not
8850 request the address of non-addressable trees on its own; the only
8851 exception is for the invocation of low-level block operations like
8852 memcpy, for which the addressability requirements are lower since
8853 the type's alignment can be disregarded. In practice, this means
8854 that Gigi must make sure that such operations cannot be applied to
8855 non-BLKmode bit-fields.
8857 The second goal is achieved by means of the addressable_p predicate,
8858 which computes whether a temporary must be inserted by Gigi when the
8859 address of a tree is requested; if so, the address of the temporary
8860 will be used in lieu of that of the original tree and some glue code
8861 generated to connect everything together. */
8863 static bool
8865 {
8866 /* For an integral type, the size of the actual type of the object may not
8867 be greater than that of the expected type, otherwise an indirect access
8868 in the latter type wouldn't correctly set all the bits of the object. */
8874 /* The size of the actual type of the object may not be smaller than that
8875 of the expected type, otherwise an indirect access in the latter type
8876 would be larger than the object. But only record types need to be
8877 considered in practice for this case. */
8884 {
8889 /* All DECLs are addressable: if they are in a register, we can force
8890 them to memory. */
8895 /* Taking the address of a dereference yields the original pointer. */
8900 /* Taking the address yields a pointer to the constant pool. */
8904 /* Taking the address of a static constructor yields a pointer to the
8905 tree constant pool. */
8917 /* All rvalues are deemed addressable since taking their address will
8918 force a temporary to be created by the middle-end. */
8922 /* The address of a compound expression is that of its 2nd operand. */
8926 /* We accept &COND_EXPR as soon as both operands are addressable and
8927 expect the outcome to be the address of the selected operand. */
8933 /* Even with DECL_BIT_FIELD cleared, we have to ensure that
8934 the field is sufficiently aligned, in case it is subject
8935 to a pragma Component_Alignment. But we don't need to
8936 check the alignment of the containing record, as it is
8937 guaranteed to be not smaller than that of its most
8938 aligned field that is not a bit-field. */
8939 && (!STRICT_ALIGNMENT
8942 /* The field of a padding record is always addressable. */
8956 {
8957 /* This is addressable if we can avoid a copy. */
8961 && (!STRICT_ALIGNMENT
8966 && (!STRICT_ALIGNMENT
8972 }
8976 }
8977 }
8978 \f
8979 /* Do the processing for the declaration of a GNAT_ENTITY, a type. If
8980 a separate Freeze node exists, delay the bulk of the processing. Otherwise
8981 make a GCC type for GNAT_ENTITY and set up the correspondence. */
8983 void
8985 {
8986 tree gnu_old
8988 tree gnu_new;
8990 /* If we are to delay elaboration of this type, just do any
8991 elaborations needed for expressions within the declaration and
8992 make a dummy type entry for this node and its Full_View (if
8993 any) in case something points to it. Don't do this if it
8994 has already been done (the only way that can happen is if
8995 the private completion is also delayed). */
9001 {
9005 {
9010 {
9014 }
9015 }
9018 }
9020 /* If we saved away a dummy type for this node it means that this
9021 made the type that corresponds to the full type of an incomplete
9022 type. Clear that type for now and then update the type in the
9023 pointers. */
9025 {
9030 }
9032 /* Now fully elaborate the type. */
9036 /* If we have an old type and we've made pointers to this type, update those
9037 pointers. If this is a Taft amendment type in the main unit, we need to
9038 mark the type as used since other units referencing it don't see the full
9039 declaration and, therefore, cannot mark it as used themselves. */
9041 {
9046 }
9048 /* If this is a record type corresponding to a task or protected type
9049 that is a completion of an incomplete type, perform a similar update
9050 on the type. ??? Including protected types here is a guess. */
9054 {
9055 tree gnu_task_old
9065 }
9066 }
9067 \f
9068 /* GNAT_ENTITY is the type of the resulting constructor, GNAT_ASSOC is the
9069 front of the Component_Associations of an N_Aggregate and GNU_TYPE is the
9070 GCC type of the corresponding record type. Return the CONSTRUCTOR. */
9072 static tree
9074 {
9077 /* We test for GNU_FIELD being empty in the case where a variant
9078 was the last thing since we don't take things off GNAT_ASSOC in
9079 that case. We check GNAT_ASSOC in case we have a variant, but it
9080 has no fields. */
9083 {
9088 /* The expander is supposed to put a single component selector name
9089 in every record component association. */
9092 /* Ignore fields that have Corresponding_Discriminants since we'll
9093 be setting that field in the parent. */
9098 /* Also ignore discriminants of Unchecked_Unions. */
9103 /* Before assigning a value in an aggregate make sure range checks
9104 are done if required. Then convert to the type of the field. */
9110 /* Add the field and expression to the list. */
9112 }
9116 #ifdef ENABLE_CHECKING
9117 /* Verify that every entry in GNU_LIST was used. */
9120 #endif
9123 }
9125 /* Build a possibly nested constructor for array aggregates. GNAT_EXPR is
9126 the first element of an array aggregate. It may itself be an aggregate.
9127 GNU_ARRAY_TYPE is the GCC type corresponding to the array aggregate.
9128 GNAT_COMPONENT_TYPE is the type of the array component; it is needed
9129 for range checking. */
9131 static tree
9133 Entity_Id gnat_component_type)
9134 {
9136 tree gnu_expr;
9140 {
9141 /* If the expression is itself an array aggregate then first build the
9142 innermost constructor if it is part of our array (multi-dimensional
9143 case). */
9149 gnat_component_type);
9150 else
9151 {
9154 /* Before assigning the element to the array, make sure it is
9155 in range. */
9158 }
9165 integer_one_node));
9166 }
9169 }
9170 \f
9171 /* Subroutine of assoc_to_constructor: VALUES is a list of field associations,
9172 some of which are from RECORD_TYPE. Return a CONSTRUCTOR consisting
9173 of the associations that are from RECORD_TYPE. If we see an internal
9174 record, make a recursive call to fill it in as well. */
9176 static tree
9178 {
9183 {
9186 /* _Parent is an internal field, but may have values in the aggregate,
9187 so check for values first. */
9189 {
9192 }
9195 {
9200 }
9201 else
9202 /* If we have a record subtype, the names will match, but not the
9203 actual FIELD_DECLs. */
9206 {
9209 }
9215 }
9218 }
9219 \f
9220 /* Process a N_Validate_Unchecked_Conversion node. */
9222 static void
9224 {
9228 /* If the target is a pointer type, see if we are either converting from a
9229 non-pointer or from a pointer to a type with a different alias set and
9230 warn if so, unless the pointer has been marked to alias everything. */
9233 {
9243 target_alias_set)))
9244 {
9248 gnat_node);
9251 }
9252 }
9254 /* Likewise if the target is a fat pointer type, but we have no mechanism to
9255 mitigate the problem in this case, so we unconditionally warn. */
9257 {
9258 tree gnu_source_desig_type
9262 tree gnu_target_desig_type
9269 target_alias_set)))
9270 {
9274 gnat_node);
9275 }
9276 }
9277 }
9278 \f
9279 /* EXP is to be treated as an array or record. Handle the cases when it is
9280 an access object and perform the required dereferences. */
9282 static tree
9284 {
9285 /* If the type is a pointer, dereference it. */
9290 /* If we got a padded type, remove it too. */
9295 }
9296 \f
9297 /* Convert SLOC into LOCUS. Return true if SLOC corresponds to a source code
9298 location and false if it doesn't. In the former case, set the Gigi global
9299 variable REF_FILENAME to the simple debug file name as given by sinput.
9300 If clear_column is true, set column information to 0. */
9302 static bool
9304 {
9309 {
9312 }
9313 else
9314 {
9320 /* We can have zero if pragma Source_Reference is in effect. */
9324 /* Translate the location. */
9326 }
9328 ref_filename
9329 = IDENTIFIER_POINTER
9330 (get_identifier
9334 }
9336 /* Similar to the above, not clearing the column information. */
9338 bool
9340 {
9342 }
9344 /* Similar to set_expr_location, but start with the Sloc of GNAT_NODE and
9345 don't do anything if it doesn't correspond to a source location. */
9347 static void
9349 {
9350 location_t locus;
9356 }
9358 /* Similar to the above, not clearing the column information. */
9360 static void
9362 {
9364 }
9366 /* More elaborate version of set_expr_location_from_node to be used in more
9367 general contexts, for example the result of the translation of a generic
9368 GNAT node. */
9370 static void
9372 {
9373 /* Set the location information on the node if it is a real expression.
9374 References can be reused for multiple GNAT nodes and they would get
9375 the location information of their last use. Also make sure not to
9376 overwrite an existing location as it is probably more precise. */
9379 {
9380 CASE_CONVERT:
9389 /* ... fall through ... */
9393 {
9396 }
9398 }
9399 }
9400 \f
9401 /* Return a colon-separated list of encodings contained in encoded Ada
9402 name. */
9406 {
9410 }
9412 /* Extract the Ada name from an encoded name. */
9416 {
9420 }
9421 \f
9422 /* Post an error message. MSG is the error message, properly annotated.
9423 NODE is the node at which to post the error and the node to use for the
9424 '&' substitution. */
9426 void
9428 {
9429 String_Template temp;
9430 String_Pointer sp;
9440 }
9442 /* Similar to post_error, but NODE is the node at which to post the error and
9443 ENT is the node to use for the '&' substitution. */
9445 void
9447 {
9448 String_Template temp;
9449 String_Pointer sp;
9459 }
9461 /* Similar to post_error_ne, but NUM is the number to use for the '^'. */
9463 void
9465 {
9468 }
9470 /* Set the end_locus information for GNU_NODE, if any, from an explicit end
9471 location associated with GNAT_NODE or GNAT_NODE itself, whichever makes
9472 most sense. Return true if a sensible assignment was performed. */
9474 static bool
9476 {
9478 location_t end_locus;
9480 /* Pick the GNAT node of which we'll take the sloc to assign to the GCC node
9481 end_locus when there is one. We consider only GNAT nodes with a possible
9482 End_Label attached. If the End_Label actually was unassigned, fallback
9483 on the original node. We'd better assign an explicit sloc associated with
9484 the outer construct in any case. */
9487 {
9500 }
9504 /* Some expanded subprograms have neither an End_Label nor a Sloc
9505 attached. Notify that to callers. For a block statement with no
9506 End_Label, clear column information, so that the tree for a
9507 transient block does not receive the sloc of a source condition. */
9515 {
9526 }
9527 }
9528 \f
9529 /* Similar to post_error_ne, but T is a GCC tree representing the number to
9530 write. If T represents a constant, the text inside curly brackets in
9531 MSG will be output (presumably including a '^'). Otherwise it will not
9532 be output and the text inside square brackets will be output instead. */
9534 void
9536 {
9543 {
9546 }
9547 else
9551 {
9557 ;
9558 else
9560 }
9565 }
9567 /* Similar to post_error_ne_tree, but NUM is a second integer to write. */
9569 void
9572 {
9575 }
9576 \f
9577 /* Initialize the table that maps GNAT codes to GCC codes for simple
9578 binary and unary operations. */
9580 static void
9582 {
9608 }
9610 /* Return a label to branch to for the exception type in KIND or NULL_TREE
9611 if none. */
9613 tree
9615 {
9622 else
9624 }
9626 /* Return the decl for the current elaboration procedure. */
9628 tree
9630 {
9632 }